v18 bss parameter guide
TRANSCRIPT
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V18.0 BSS Parameter User Guide (BPUG)
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PUBLICATION HISTORY
System release: GSM/BSS V18
January 2009
Issue 18.04/EN
Update for v18 Customer Readiness after review (iPOR Id 422749)
December 2008
Issue 18.03/EN
Update for v18 Channel Readiness
AMR Maximization parameters (§ 5.38), Single BCCH Multizone Enhancement (§ 5.20)
Enhanced Very Early Assignment (§ 5.46).
October 2008
Issue 18.02/EN
Update for v18 Customer Readiness after review (iPOR Id 391287)
AMR Maximization parameters (§ 5.38).
September 2008
Issue 18.01/EN
Update for v18 Customer Readiness
2G 3G UTRAN FDD TDD Cell Reselection (§ 4.4) Single BCCH Multizone Enhancement
(§4.8.2, §4.8.6, §4.10.6); AMR Based on Traffic (§4.22.8); AMR Maximization (§ 4.22.9);
Queuing HR (§ 4.22.10 ); Repeated Downlink FACCH (§ 4.22.11); Smart BTS Power
Management (§4.28 ); Enhanced Very Early Assignment (§ 4.29).
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System release: GSM/BSS V17
May 2008
Issue 17.04/EN
Update for v17 Channel Readiness + 8 Weeks.
Update of 2G-3G Reselection description (§4.8.24);
March 2008
Issue 17.03/EN
Update for v17 Channel Readiness.
Update of Enhanced Measurement Reporting Parameters (§4.8.24); update of GSM to UMTShandovers parameters (§4.5.8); clarification on msTxPwrMax2ndBand on Power Control
Parameters section (§ 5.16)
October 2007
Issue 17.02/EN
Update for v17 Customer Readiness.
Update of GSM to UMTS handover with normal measurement reporting (§4.8.24); update of
legacy measurement reporting to include UTRAN neighbours (§4.5.8); update of reporting
priority criteria used in EMR (§4.6.5); summary of differences between MR and EMR (§4.6.8);
new section on eMLPP Preemption (§4.12); clarification of types of TDMA priorities (§6.19.2);new recommendation for trafficPCMAllocationPriority; new range for hoMarginBeg;
clarification of bscHopReconfUse; diversity mandatory for ICA (§4.18); list of Railway
parameters (§3.3); update of handover decision table for AMR TCH (§4.8.4); clarification of
Downlink DTX activation (§4.11.10).
July 2007
Issue 17.01/EN
Update for v17 Business Readiness + 21 weeks:
Legacy measurement report (§4.5); Enhanced Measurement Report (§4.6); Downlink FER
(§4.6.11); GSM to UMTS Handover (§4.8.24, §7.7); Single BCCH Multizone Enhancement
(§4.8.2, §4.8.6, §4.10.6); AMR-HR on preempted pDTCH (§4.22.6, impact on AboT §4.22.8);
A5/3 Encryption (§4.27); Smart BTS Power management (§4.28); Novel adaptive receiver
(§4.26); BSS CS Paging Coordination (§4.13.8); H3 impact on BTS cabinet power setting
(§4.16); new recommended values for modeModifyMandatory (§5.18); addition of RxQual
criteria for interzone handovers (§4.8.6); removal of reference to gsmProtocol in ICA (§5.30);
Sysinfo broadcast cycle (§4.17.3).
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System release: GSM/BSS V16
March 2007
Issue 16.04/EN
Update for V16 ChR + 8 Weeks: Update of Network Synchronization (§ 4.34); Update of TX
Power Offset for signalling Channels parameters (§ 5.34); Update of network Synchronization
Impacts (§ 6.36); Addition of Network Synchronization Engineering planning (§ 6.37) and
Network Synchronization First Trial Results (§ 6.38)
November 2006
Issue 16.03/EN
Update for V16 ChR after review: Update of CellAllocation (§ 5.21); update PCM error
correction (§ 4.17.3); update of AMR based on traffic parameters (§ 5.34)
October 2006
Issue 16.02/EN
Update for V16 ChR: Update of TEPMOS for AMR and not EFR calls (§ 6.32.2 and § 6.32.6)
I Multipaging command message (§ 4.10.5); UI Multipaging command message (§ 4.10.6);
Tx Power Offset for signalling Channels (§ 4.23.9); update coderPoolConfiguration (§ 5.34);
update PCM error correction (§ 4.17.3); update rescue Handover (§ 4.6.1) and PBGT formula
(§ 4.5.1); PCM priority (§ 6.27.5); update Cabinet power description (§ 4.13.1)
May 2006
Issue 16.01/EN
Update for V16 CuR: 6.16 Frequency Spacing Between Two TRXs of the Same Area
March 2006
Issue 16.0/EN
Update for V16. CuR: Repeated Downlink FACCH (§ 4.23.8); Tx Power Offset for signalling
Channels (§ 4.23.9); Directed Retry Handover and queuing (§ 4.5.5, § 4.23.5 removed from
WPS description); updates on CellAllocation and mobileAllocation description (§ 5.21);updates
on AMR mechanism (§ 4.23.2, §4.23.4);updates on TCH allocation management (§ 4.9.1,
§4.9.2); updates on interference cancellation (§ 4.15, 6.22); update on lRxQualDLH and
lRxQualULH description (§ 5.10);update on dARPPh1Priority description (§ 5.36); update
coderPoolConfiguration (§ 5.34); update on extended cell description (§ 5.12)
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CONTENTS
1. ABOUT THIS DOCUMENT .........................................................................................................13
1.1. OBJECT..................................................................................................................................13 1.2. SCOPE ...................................................................................................................................13 1.3. AUDIENCE FOR THIS DOCUMENT ..............................................................................................13 1.4. DISCLAIMER ...........................................................................................................................13 1.5. DOCUMENT STRUCTURE ..........................................................................................................14 1.6. UPDATES TO PREVIOUS RECOMMENDATIONS ............................................................................15
1.6.1 between V17 and V18...................................................................................................15 1.6.2 between V16 and V17...................................................................................................15
2. RELATED DOCUMENTS............................................................................................................16
2.1. APPLICABLE DOCUMENTS ........................................................................................................16 2.2. REFERENCE DOCUMENTS .......................................................................................................16
3. CLASSIFICATION OF BSS PARAMETERS ..............................................................................19
3.1. P ARAMETER LIST ....................................................................................................................19 3.2. GSM UNUSED PARAMETERS....................................................................................................29 3.3. R AILWAY-SPECIFIC PARAMETERS (GSM-R)..............................................................................29 3.4. P ARAMETERS VERSUS BSS FEATURES AND PROCEDURES .......................................................30
3.4.1 2G Cell Selection and Reselection ...............................................................................30 3.4.2 2G-3G UTRAN FDD & TDD Cell Reselection..............................................................30 3.4.3 Legacy Measurement Reporting...................................................................................30 3.4.4 Enhanced Measurement Reporting ..............................................................................30 3.4.5 Level averaging.............................................................................................................30 3.4.6 Quality averaging ..........................................................................................................30 3.4.7 Distance averaging .......................................................................................................30 3.4.8 Cell eligibility..................................................................................................................30 3.4.9 Radio Link Failure .........................................................................................................31 3.4.10 Interference management.............................................................................................31 3.4.11 PCH and RACH control parameters .............................................................................31 3.4.12 Concentric Cell ..............................................................................................................31 3.4.13 Extended cell.................................................................................................................31
3.4.14 Queuing and priority management................................................................................31 3.4.15 eMLPP Preemption.......................................................................................................31 3.4.16 SMS-CB ........................................................................................................................31 3.4.17 Frequency Hopping.......................................................................................................32 3.4.18 Dynamic barring of access class ..................................................................................32 3.4.19 DTX ...............................................................................................................................32 3.4.20 Uplink Power control .....................................................................................................32 3.4.21 Downlink Power control.................................................................................................32 3.4.22 Directed retry handover.................................................................................................32 3.4.23 Uplink intracell handover...............................................................................................32 3.4.24 Downlink intracell handover..........................................................................................32 3.4.25 Intercell handover on bad uplink quality criterion..........................................................32 3.4.26 Intercell handover on bad downlink quality criterion .....................................................33
3.4.27 Intercell handover on bad uplink level criterion.............................................................33 3.4.28 Intercell handover on bad downlink level criterion ........................................................33 3.4.29 Intercell handover on power budget criterion................................................................33
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3.4.30 Microcellular algorithm ..................................................................................................33 3.4.31 Intercell handover on distance criterion ........................................................................33 3.4.32 Handover for traffic reasons..........................................................................................33 3.4.33 Handover decision according to adjacent cell...............................................................33 3.4.34 General protection against HO PingPong.....................................................................33
3.4.35 Call clearing...................................................................................................................33 3.4.36 Frequency Band favouring............................................................................................34 3.4.37 Minimum Time between Handover ...............................................................................34 3.4.38 Radio resource control at cell level ...............................................................................34 3.4.39 Pre-synchronised Handover..........................................................................................34 3.4.40 Interferer cancellation....................................................................................................34 3.4.41 Early HO decision .........................................................................................................34 3.4.42 Maximum RxLev for PBGT ...........................................................................................34 3.4.43 Cell Tiering ....................................................................................................................34 3.4.44 TTY support on BSC/TCU 3000....................................................................................34 3.4.45 Protection against intracell HO Ping-pong....................................................................34 3.4.46 Automatic Handover adaptation....................................................................................34 3.4.47 GSM to UMTS Handover ..............................................................................................35
3.4.48 Adaptative Full/Half Rate ..............................................................................................35 3.4.49 Wireless Priority Service ...............................................................................................35 3.4.50 Network Synchronization ..............................................................................................35 3.4.51 Repeated Downlink FACCH..........................................................................................35 3.4.52 Tx Power Offset for Signalling.......................................................................................35 3.4.53 Novel adaptive Receiver ...............................................................................................35 3.4.54 A5/3 Encryption Algorithm.............................................................................................36 3.4.55 BTS Smart Power Management ...................................................................................36 3.4.56 Enhanced Very Early Assignment ................................................................................36 3.4.57 AMR Maximization ........................................................................................................36
4. ALGORITHMS .............................................................................................................................37
4.1. INTRODUCTION .......................................................................................................................37 4.2. CONVENTIONS AND UNITS .......................................................................................................37
4.2.1 Unit ................................................................................................................................37 4.2.2 Phase 2 BTS and MS maximum transmitting output powers .......................................38 4.2.3 GSM Products sensitivity and power ............................................................................40 4.2.4 Conversion rules ...........................................................................................................41 4.2.5 Accuracy related to measurements ..............................................................................41 4.2.6 Frequency band ............................................................................................................42
4.3. 2G CELL SELECTION AND RESELECTION ..................................................................................43
4.3.1 Overview .......................................................................................................................43 4.3.2 Selection or reselection between cells of current Location Area..................................44
4.3.3 Reselection to a cell of a different Location Area..........................................................44 4.3.4 Additional reselection criterion (for phase 2).................................................................45
4.4. 2G - 3G UTRAN FDD & TDD CELL RESELECTION ..................................................................48
4.4.1 UE algorithm in GSM circuit mode................................................................................48 4.4.2 3G neighbouring cell information in SI2quater..............................................................51 4.4.3 Control Information in SI2Quater ..................................................................................52
4.5. LEGACY MEASUREMENT REPORTING .......................................................................................53
4.5.1 Principle.........................................................................................................................53 4.5.2 Neighbour cell Monitoring .............................................................................................53 4.5.3 Serving cell monitoring..................................................................................................54 4.5.4 Reporting Period ...........................................................................................................54
4.5.5 Neighbour Cell Lists......................................................................................................54 4.5.6 Measurement Report Content.......................................................................................55 4.5.7 Multiband reporting .......................................................................................................56
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4.5.8 UTRAN cell reporting using legacy measurement reports (V17)..................................56 4.5.9 Note on powerControlIndicator parameter....................................................................59 4.5.10 Note on Rxlev Uplink/Downlink difference....................................................................60
4.6. ENHANCED MEASUREMENT REPORTING (EMR) .......................................................................61
4.6.1 Principle.........................................................................................................................61 4.6.2 Reporting period............................................................................................................61 4.6.3 Enhanced Measurement Report content ......................................................................61 4.6.4 Neighbour Cell lists .......................................................................................................62 4.6.5 Order of reporting priority of neighbour cells.................................................................63 4.6.6 Measurement Information message .............................................................................63 4.6.7 MI/SACCH scheduling ..................................................................................................66 4.6.8 Main differences between Normal and Enhanced Measurement Reporting ................66 4.6.9 New BSS parameters....................................................................................................67 4.6.10 Impact of EMR on Interference Matrix ..........................................................................68 4.6.11 Impact of EMR on Radio Measurement Distribution (RMD).........................................69
4.7. UPLINK MEASUREMENT PROCESSING ......................................................................................70
4.7.1 Principle.........................................................................................................................70 4.7.2 Averaging process ........................................................................................................71 4.7.3 Rescaling.......................................................................................................................72 4.7.4 Missing downlink measurements..................................................................................72
4.8. DIRECT TCH ALLOCATION AND H ANDOVER ALGORITHMS .........................................................75
4.8.1 General formulas...........................................................................................................75 4.8.2 Direct TCH Allocation....................................................................................................78 4.8.3 Handovers.....................................................................................................................82 4.8.4 Handovers decision priority...........................................................................................85 4.8.5 Directed Retry Handover...............................................................................................87 4.8.6 Concentric/DualCoupling/DualBand Cell Handover .....................................................90 4.8.7 Rescue Handover .........................................................................................................96 4.8.8 Power Budget Handover...............................................................................................98 4.8.9 Handover for traffic reasons..........................................................................................98 4.8.10 Handover decision according to adjacent cell priorities and load.............................. 101 4.8.11 Automatic cell tiering.................................................................................................. 102 4.8.12 Microcellular Handover .............................................................................................. 107 4.8.13 Forced Handover ....................................................................................................... 110 4.8.14 Early HandOver Decision........................................................................................... 111 4.8.15 Maximum RxLev for Power Budget ........................................................................... 112 4.8.16 Pre-synchronized HO................................................................................................. 113 4.8.17 Radio channel allocation............................................................................................ 113 4.8.18 Define eligible neighbor cells for intercell handover (except directed retry) .............. 114 4.8.19 Handover to 2nd best candidate when return to old channel .................................... 115 4.8.20 Protection against RunHandover=1........................................................................... 115 4.8.21 General protection against HO ping-pong ................................................................. 116 4.8.22 Automatic handover adaptation ................................................................................. 118 4.8.23 Protection against Intracell HO Ping-Pong ................................................................ 121 4.8.24 GSM to UMTS handover............................................................................................ 124
4.9. H ANDOVER ALGORITHMS ON THE MOBILE SIDE ..................................................................... 135 4.10. POWER CONTROL ALGORITHMS ........................................................................................... 136
4.10.1 Step by step Power Control ....................................................................................... 136 4.10.2 One shot Power Control............................................................................................. 137 4.10.3 Fast Power Control at TCH assignment .................................................................... 139 4.10.4 Power Control on mobile side .................................................................................... 140 4.10.5 AMR Power Control ................................................................................................... 140 4.10.6 Power Adaptation After An Interzone HO .................................................................. 141
4.11. TCH ALLOCATION M ANAGEMENT ......................................................................................... 144
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4.11.1 TCH Allocation and Priority........................................................................................ 144 4.11.2 Queuing...................................................................................................................... 148 4.11.3 Barring of access class .............................................................................................. 152 4.11.4 Radio link failure process (run by the MS)................................................................. 157 4.11.5 Radio link failure process (run by the BTS) ............................................................... 157
4.11.6 Call reestablishment procedure ................................................................................. 158 4.11.7 Call Clearing Process (run by BTS) ........................................................................... 159 4.11.8 Interference Management (BTS and BSC) ................................................................ 159 4.11.9 Uplink DTX................................................................................................................. 159 4.11.10 Downlink DTX......................................................................................................... 161
4.12. EMLPP PREEMPTION .......................................................................................................... 163
4.12.1 Principle of eMLPP..................................................................................................... 163 4.12.2 End-to-end perspective.............................................................................................. 164 4.12.3 Preemption attributes................................................................................................. 166 4.12.4 BSS Radio Resource preemption algorithm.............................................................. 167 4.12.5 Activation parameter .................................................................................................. 170 4.12.6 eMLPP preemption versus PDTCH preemption ........................................................ 170
4.12.7 Interworking................................................................................................................171 4.12.8 Restrictions.................................................................................................................172
4.13. PCH AND RACH CHANNEL CONTROL ................................................................................... 173
4.13.1 Paging command Process ......................................................................................... 173 4.13.2 Paging command repetition process (run by BTS) .................................................... 175 4.13.3 Request access command process........................................................................... 177 4.13.4 Request access command repetition process ........................................................... 177 4.13.5 I Multipaging command message .............................................................................. 178 4.13.6 UI Multipaging command message............................................................................ 180 4.13.7 Network Mode of Operation I support in BSS............................................................ 182 4.13.8 BSS CS Paging Coordination .................................................................................... 184
4.14. FREQUENCY HOPPING ......................................................................................................... 186 4.14.1 Frequency hopping principles .................................................................................... 186 4.14.2 Main benefits of frequency hopping........................................................................... 187 4.14.3 Synthesised frequency hopping................................................................................. 189 4.14.4 Baseband frequency Hopping.................................................................................... 190 4.14.5 Ad-Hoc frequency plan............................................................................................... 192
4.15. BSC OVERLOAD M ANAGEMENT MECHANISMS....................................................................... 193
4.15.1 BSC3000 Overload Management .............................................................................. 193 4.15.2 Load Balancing .......................................................................................................... 195 4.15.3 Evolution of Load Balancing....................................................................................... 195
4.16. C ABINET OUTPUT POWER SETTING ...................................................................................... 197
4.16.1 Cabinet power description.......................................................................................... 197 4.16.2 Pr computation........................................................................................................... 198 4.16.3 Ps computation .......................................................................................................... 198
4.17. SYSTEM INFORMATION MESSAGES RELATED FEATURES ........................................................ 200
4.17.1 Dual Band Handling ................................................................................................... 200 4.17.2 SI2Quater & SI13 on Extended or Normal BCCH...................................................... 203 4.17.3 Summary of SYSINFO Scheduling............................................................................ 205
4.18. INTERFERENCE C ANCELLATION ............................................................................................ 206 4.19. EXTENDED CCCH ............................................................................................................... 208
4.19.1 Customer/service provider benefits ........................................................................... 208
4.19.2 Feature functional description.................................................................................... 208 4.20. CELLULAR TELEPHONE TEXT MODEM (TTY) ......................................................................... 209
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5.1. INTRODUCTION .................................................................................................................... 283 5.2. 2G CELL SELECTION AND RESELECTION P ARAMETERS.......................................................... 284 5.3. 2G-3G CELL RESELECTION PARAMETERS............................................................................. 289 5.4. LEGACY MEASUREMENT REPORTING P ARAMETERS ............................................................... 292 5.5. ENHANCED MEASUREMENT REPORTING P ARAMETERS .......................................................... 293
5.6. R ADIO LINK F AILURE P ARAMETERS....................................................................................... 297 5.7. SIGNAL QUALITY AVERAGING P ARAMETERS .......................................................................... 300 5.8. SIGNAL STRENGTH AVERAGING P ARAMETERS....................................................................... 302 5.9. NEIGHBOR CELL AVERAGING P ARAMETERS .......................................................................... 305 5.10. DISTANCE AVERAGING P ARAMETERS .................................................................................... 307 5.11. H ANDOVER (GLOBAL) P ARAMETERS ..................................................................................... 309 5.12. INTRACELL H ANDOVER P ARAMETERS.................................................................................... 322 5.13. INTERCELL H ANDOVER THRESHOLD P ARAMETERS ................................................................ 325 5.14. H ANDOVER FOR MICROCELLULAR NETWORK P ARAMETERS ................................................... 328 5.15. DISTANCE M ANAGEMENT P ARAMETERS ................................................................................ 330 5.16. POWER CONTROL P ARAMETERS........................................................................................... 334 5.17. TCH ALLOCATION M ANAGEMENT P ARAMETERS .................................................................... 342 5.18. EMLPP R ADIO RESOURCE PREEMPTION PARAMETER ........................................................... 356
5.19. DIRECTED RETRY H ANDOVER P ARAMETERS ......................................................................... 357 5.20. CONCENTRIC CELL P ARAMETERS ......................................................................................... 361 5.21. INTERFERENCE LEVEL P ARAMETERS .................................................................................... 371 5.22. R ADIO RESSOURCES CONTROL AT CELL LEVEL .................................................................... 374 5.23. BSS TIMERS ....................................................................................................................... 375 5.24. P AGING P ARAMETERS.......................................................................................................... 382 5.25. FREQUENCY HOPPING P ARAMETERS .................................................................................... 387 5.26. BSC LOAD M ANAGEMENT P ARAMETERS............................................................................... 394 5.27. DUALB AND CELL P ARAMETERS ............................................................................................ 395 5.28. DTX P ARAMETERS .............................................................................................................. 402 5.29. MISCELLANEOUS ................................................................................................................. 403 5.30. INTERFERENCE C ANCELLATION P ARAMETERS ....................................................................... 406 5.31. PCM ERROR CORRECTION P ARAMETERS ............................................................................. 408
5.32. CELL TIERING P ARAMETERS................................................................................................. 409 5.33. ENCODING P ARAMETERS ..................................................................................................... 412 5.34. SMS-CELL BROADCAST P ARAMETERS ................................................................................. 413 5.35. PROTECTION AGAINST INTRACELL HO PING-PONG P ARAMETERS .......................................... 414 5.36. AUTOMATIC H ANDOVER ADAPTATION P ARAMETERS .............................................................. 415 5.37. GSM TO UMTS HANDOVER PARAMETERS............................................................................. 417 5.38. AMR - ADAPTATIVE MULTI R ATE FR/HR P ARAMETERS ......................................................... 425 5.39. WPS - WIRELESS PRIORITY SERVICES P ARAMETERS ............................................................ 444 5.40. NETWORK SYNCHRONIZATION PARAMETERS ......................................................................... 445 5.41. NETWORK MODE OF OPERATION P ARAMETERS ..................................................................... 447 5.42. BSS CS P AGING COORDINATION PARAMETER ...................................................................... 448 5.43. NOVEL ADAPTIVE RECEIVER PARAMETER .............................................................................. 448 5.44. A5/3 ENCRYPTION ALGORITHM PARAMETERS........................................................................ 449 5.45. BTS SMART POWER M ANAGEMENT P ARAMETERS................................................................. 451 5.46. ENHANCED VERY E ARLY ASSIGNMENT P ARAMETERS ............................................................ 453
6. ENGINEERING ISSUES........................................................................................................... 454
6.1. GSM/GPRS TS SHARING: PRIORITY H ANDLING AND QUEUING ............................................. 454
6.1.1 Resources reserved for priority 0 and preemption..................................................... 454 6.1.2 GSM/GPRS TS sharing and queuing: ....................................................................... 455 6.1.3 Resources strategy .................................................................................................... 456
6.2. MINIMUM TIME BETWEEN H ANDOVER.................................................................................... 457
6.2.1 Micro-cellular network ................................................................................................ 457 6.2.2 Non micro-cellular network......................................................................................... 459
6.3. DIRECTED RETRY H ANDOVER BENEFIT ................................................................................. 460
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6.3.1 Benefit of feature on mono-layer structure................................................................. 460 6.3.2 Benefit of feature on multi-layers structure ................................................................ 461
6.4. CONCENTRIC CELLS ............................................................................................................ 464
6.4.1 Concentric Cell Parameter Definition......................................................................... 465
6.4.2 Concentric Cell Field Experience............................................................................... 468 6.5. IMPACT OF DTX ON AVERAGING ........................................................................................... 472 6.6. BEST NEIGHBOUR CELLS STABILITY ..................................................................................... 473 6.7. TCH ALLOCATION GENERAL RULES ..................................................................................... 474 6.8. GENERAL R ADIO FREQUENCY RULES ................................................................................... 475 6.9. DIFFERENCE BETWEEN UPLINK AND DOWNLINK LEVELS ........................................................ 476 6.10. EFFECTS OF SMS-CELL BROADCAST USE ON “NOOFBLOCKSFOR ACCESSGRANT”................. 477 6.11. IMPACT OF THE AVERAGING ON THE H ANDOVERS .................................................................. 478
6.11.1 Global statistics.......................................................................................................... 478 6.11.2 Study of reactivity....................................................................................................... 479 6.11.3 Ping pong vs Reactivity.............................................................................................. 479
6.12. IMPACT OF C ALL RE-ESTABLISHMENT ON THE NETWORK ....................................................... 480 6.12.1 Impact on capacity ..................................................................................................... 480 6.12.2 Impact on call drops................................................................................................... 480
6.13. MINIMUM COUPLING LOSS (MCL)......................................................................................... 481
6.13.1 Broadband noise ........................................................................................................ 481 6.13.2 Blocking...................................................................................................................... 481 6.13.3 How to improve the MCL............................................................................................ 482
6.14. MICROCELL BENEFITS.......................................................................................................... 483
6.14.1 Frequency super reuse .............................................................................................. 483 6.14.2 Traffic Homogenization .............................................................................................. 483 6.14.3 Radio conditions improvement................................................................................... 483 6.14.4 Microcell Field Experience ......................................................................................... 484
6.15. INTERFERENCE C ANCELLATION USAGE ................................................................................. 485 6.16. STREET CORNER ENVIRONMENT .......................................................................................... 486
6.16.1 Description ................................................................................................................. 486 6.16.2 Case A: Mobile moving straight ................................................................................. 487 6.16.3 Case B: Mobile turning at the cross road................................................................... 488
6.17. SYNCHRONIZED HO VERSUS NOT SYNCHRONIZED HO.......................................................... 489
6.17.1 Introduction.................................................................................................................489 6.17.2 OMC-R Parameter settings........................................................................................ 489 6.17.3 Timing HO.................................................................................................................. 490
6.18. BTS SENSITIVITY................................................................................................................. 494 6.18.1 Definition of sensitivity................................................................................................ 494 6.18.2 Static and dynamic sensitivity .................................................................................... 495 6.18.3 Typical / guaranteed sensitivity.................................................................................. 495 6.18.4 Space diversity gains ................................................................................................. 495 6.18.5 Cross-polarization antenna use ................................................................................. 496 6.18.6 Circular polarization and crosspolar antennas........................................................... 497
6.19. SDCCH DIMENSIONING AND TDMA PRIORITIES.................................................................... 499
6.19.1 SDCCH Dimensioning................................................................................................ 499 6.19.2 TDMA priorities .......................................................................................................... 501
6.20. ENGINEERING GUIDELINES FOR EXCEPTIONAL EVENTS.......................................................... 503
6.20.1 BSS prerequisite ........................................................................................................ 503 6.20.2 BSS: Suggestions for parameters to be modified for the special event .................... 504
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6.20.3 NSS level.................................................................................................................... 505
6.21. IMPACT OF AUTOMATIC H ANDOVER ADAPTATION ACTIVATION................................................. 508
6.21.1 Related parameters.................................................................................................... 508 6.21.2 Deployment Optimization and Monitoring.................................................................. 509
6.22. H ANDOVER FOR TRAFFIC REASONS ACTIVATION GUIDELINE .................................................. 513
6.22.1 Algorithms and Parameters Definition ....................................................................... 513 6.22.2 Expected effects and recommended parameters ...................................................... 515
6.23. DISABLING AMR BASED ON TRAFFIC IN V15.1.1.................................................................... 519
7. APPENDIX A: MAIN EXCHANGE PROCEDURES AT BSC LEVEL...................................... 520
7.1. ESTABLISHMENT PROCEDURE .............................................................................................. 520 7.2. CHANNEL MODE PROCEDURE .............................................................................................. 521 7.3. DEDICATED CHANNEL ASSIGNMENT ...................................................................................... 522 7.4. INTRACELL H ANDOVER PROCEDURE ..................................................................................... 523 7.5. INTRABSS H ANDOVER PROCEDURE ..................................................................................... 524 7.6. INTERBSS H ANDOVER PROCEDURE ..................................................................................... 525 7.7. 2G-3G H ANDOVER PROCEDURE........................................................................................... 526 7.8. RESOURCE RELEASE PROCEDURE (EXAMPLE)...................................................................... 527 7.9. SACCH DEACTIVATION PROCEDURE ................................................................................... 528 7.10. MOBILE TERMINATING C ALL ................................................................................................. 529 7.11. MOBILE ORIGINATING C ALL .................................................................................................. 530
8. APPENDIX B: ERLANG TABLE.............................................................................................. 531
9. ABBREVIATIONS & DEFINITIONS......................................................................................... 534
9.1. ABBREVIATIONS ................................................................................................................... 534 9.2. DEFINITIONS........................................................................................................................ 540
10. INDEX ....................................................................................................................................... 543
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1. ABOUT THIS DOCUMENT
1.1. OBJECT
This document describes BSS GSM and Nortel algorithms and parameters from an
engineering point of view.
This document is written by Nortel BSS experts and contains extensive Nortel BSS
parameters setting know-how. Informations coming from experiments, studies, simulations are
also related in the document.
The parameters are called by the name used in the features and algorithms. For their
corresponding name (when different) at the OMC, refer to [R6].
The parameters described in this document are the ones used in the features and algorithms.
Refer to [R2] to have a description of all BSS parameters.
1.2. SCOPE
This version is issued for the ChR milestone of the V18 BSS GSM release.
1.3. AUDIENCE FOR THIS DOCUMENT
Draft and preliminary: Nortel R&D, PLM and Eng'
Standard: customers and Nortel R&D, Product Line Management and Engineering teams.'
1.4. DISCLAIMER
Depending on particular objective, call profile and network characteristics, a parameter setting
can never be judged as being universally optimized.
The recommended setting presented in this document should result in good network
performance; however several iterations and improvements may be required in order to be
optimal according to customer specificities. Every effort is made to incorporate suggestions
and feedback received from customers.
PRELIMINARY VERSION
The recommended setting has been validated with product and system tests in lab. This
document will be updated and adjusted after the first results from VO site or new Product
Test/End-to-end labs if available.
STANDARD VERSION
This is a living document and the contents will be modified based on feedback received from
R&D, Engineering and customers.
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1.5. DOCUMENT STRUCTURE
In chapter §3 CLASSIFICATION OF BSS PARAMETERS, BSS algorithm parameters are
presented in alphabetic order according to their group. Process and related objects are also
provided.
Chapter §4 ALGORITHMS describes the GSM Nortel BSS algorithms and recommends ways
to use them efficiently.
BSS parameters used in the algorithms are described in chapter §5 ALGORITHM
PARAMETERS. For each parameter, a recommended value and a default value are given.
Engineering rules explain how to select the parameter value.
In chapter §6 ENGINEERING ISSUE, engineering issues resulting from studies on parameter
setting and on products, simulations and experiments are developped.
Chapter §7 APPENDIX A: MAIN EXCHANGE PROCEDURES AT BSC LEVEL gives the main
exchange procedures at BSC level.
In chapter §8 APPENDIX B: ERLANG TABLE, an Erlang table presents the maximum offered
load according to the number of channels and the blocking rate.
In chapter §9 ABBREVIATIONS & DEFINITIONS, the signification of all the abbrevations used
in this document and some key-definitions are explained.
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1.6. UPDATES TO PREVIOUS RECOMMENDATIONS
1.6.1 BETWEEN V17 AND V18
No modification
1.6.2 BETWEEN V16 AND V17
modeModifyMandatory:
New recommended value set to “not used”. This parameter is no longer useful but setting to
“used” may yield undesirable side-effects in particular circumstances.
enhancedTRAUframeIndication :
This parameter is no longer useful in V17 due to the end of support of the PCM Error
Correction feature.
pcmErrorCorrection :
This parameter is no longer useful in V17 duie to the end of support of the PCM Error
Correction feature.
bscHopReconfUse :
New recommended value for BSC that manage only BTS with hybrid coupling.
Old recommendation : “false (mandatory for hybrid coupling).”
New recommendation : “the value (true or false) is indifferent for a BSC that manages only
BTS with hybrid coupling”.
trafficPCMAllocationPriority :
New recommended value for BCCH TDMA.
Old recommendation : highest priority (0) for BCCH TDMA.
New recommendation : lowest priority (255) for BCCH TDMA.
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3. CLASSIFICATION OF BSS PARAMETERS
3.1. PARAMETER LIST
The following table gives a classification of the main BSS tunable parameters sorted by
alphabetical order, the object they are associated to at the OMC-R (as they are described in
[R1]) and the main features using those parameters.
Parameter name BSS Object- Feature(s) using this parameter
accessClassCongestion V9 bts Barring of access class
adaptiveReceiver V17 transceiver Novel Adaptive Receiver
adjacent_cell_umbrella_ref V9 bts Directed Retry Handover
allocPriorityTable V7 bts TCH Allocation and Priority
Queuing
WPS – Queuing management
allocPriorityThreshold V7 bts TCH Allocation and Priority
Queuing
allocPriorityTimers V7 bts Queuing
WPS – Queuing management
allocWaitThreshold V7 bts Queuing
WPS – Queuing management
allOtherCasesPriority V7 bts TCH Allocation and Priority
Queuing
amrUlFrAdaptationSet V15 bts AMR Codec mode adaptation
amrUlHrAdaptationSet V15 bts AMR Codec mode adaptation
amrDlFrAdaptationSet V15 bts AMR Codec mode adaptation
amrUlHrAdaptationSet V15 bts AMR Codec mode adaptation
amrDirectAllocIntRxLevDL V14 bts AMR Handover mechanisms
Direct TCH Allocation
amrDirectAllocIntRxLevUL V14 bts AMR Handover mechanisms
Direct TCH Allocation
amrDirectAllocRxLevDL V14 bts AMR Handover mechanisms
Direct TCH Allocation
amrDirectAllocRxLevUL V14 bts AMR Handover mechanisms
Direct TCH Allocation
amrFRIntercellCodecMThresh V14 handOverControl AMR Handover mechanisms
amrFRIntracellCodecMThresh V14 handOverControl AMR Handover mechanisms
amrHRIntercellCodecMThresh V14 handOverControl AMR Handover mechanisms
amrHRtoFRIntracellCodecMThresh V14 handOverControl AMR Handover mechanisms
amriRxLevDLH V14 handOverControl AMR Handover mechanisms
amriRxLevULH V14 handOverControl AMR Handover mechanisms
amrReserved1 V16 handOverControl AMR RATSCCH Proceudre
amrReserved2 V14 handOverControl AMR Legacy L1M
answerPagingPriority V7 bts TCH Allocation and Priority
Queuing
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assignRequestPriority V7 bts TCH Allocation and Priority
Queuing
averagingPeriod V7 handOverControl Radio channel allocation
Interference Management
baseColourCode V7 bts Network Synchronization
bCCHFrequency V7 adjacentCellHandover
bCCHFrequency V7 adjacentCellReselection
bCCHFrequency V7 bts
biZonePowerOffset V12 adjacentCellHandover General formulas
Direct TCH Allocation
Concentric/DualCoupling/DualBand CellHandover
biZonePowerOffset V12 handoverControl General formulas
Direct TCH Allocation
Concentric/DualCoupling/DualBand Cell
Handover
bscHopReconfUse V8 bsc Reconfiguration procedure
bscMSAccessClassBarringFunction V9 bsc Barring of access class
bscQueuingOption V7 signallingPoint Queuing
WPS – Queuing management
bsMsmtProcessingMode V7 bts Measurement Processing
bsPowerControl V7 powerControl Power Control Algorithms
AMR Power Control
bssMapT1 V7 bsc
bssMapT12 V7 bsc
bssMapT13 V7 bsc
bssMapT19 V8 bsc
bssMapT20 V8 bsc
bssMapT4 V7 bsc
bssMapT7 V7 bsc
bssMapT8 V7 bsc
bssMapTchoke V7 bsc
bssPagingCoordination V17 bts BSS CS Paging Coordination
bssSccpConnEst V7 signallingPoint
bsTxPwrMax V7 powerControl General formulas
Cabinet Output Power Setting
btsSMSynchroMode V15 btsSiteManager Network Synchronization
bts Time Between HO configuration V9
V12
bts Minimum time between Handover
General protection against HO ping-pong
btsHopReconfRestart V8 bts Reconfiguration procedure
btsIsHopping V7 bts Frequency Hopping
btsMSAccessClassBarringFunction V9 bts Barring of access class
btsThresholdHopReconf V8 bts Reconfiguration procedure
callClearing V7 bts Call Clearing Process
callReestablishment V7 bts Radio link failure process,
Call reestablishment procedure
callReestablishmentPriority V7 bts TCH Allocation and Priority
Queuing
capacityTimeRejection V14 handOverControl Protection against Intracell HO Ping-Pong
AMR Handover mechanisms
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cellAllocation V7 bts Frequency Hopping
cellBarQualify V8 bts Selection, Reselection Algorithms
cellBarred V7 bts Selection, Reselection Algorithms
cellDeletionCount V7 bts Measurement Processing
Handovers screening
cellDtxDownLink V7 bts DTX
cellReselectHysteresis V8 bts Selection, Reselection Algorithms
cellReselectOffset V7 bts Selection, Reselection Algorithms
cellReselInd V8 bts Selection, Reselection Algorithms
cellType V7 adjacentCellHandOver Microcellular Algo
cellType V7 bts Microcellular Algo
channelType V7 channel
cId V17 adjacentCellUTRAN GSM to UMTS handover
coderPoolConfiguration V14 transcoder AMR Channel allocation
Cellular Telephone Text Modem (TTY)
compressedModeUTRAN V17 bts GSM to UMTS handover
concentAlgoExtMsRange V9 handOverControl Direct TCH Allocation
Concentric/DualCoupling/DualBand CellHandover
concentAlgoExtRxLev V9 handOverControl Direct TCH Allocation
Concentric/DualCoupling/DualBand CellHandover
concentAlgoExtRxLevUL V18 handOverControl Direct TCH Allocation
Concentric/DualCoupling/DualBand Cell
Handover
concentAlgoIntMsRange V9 handOverControl Concentric/DualCoupling/DualBand CellHandover
concentAlgoIntRxLev V9 handOverControl Concentric/DualCoupling/DualBand CellHandover
concentAlgoIntRxLevUL V18 handOverControl Direct TCH Allocation
Concentric/DualCoupling/DualBand CellHandover
concentric_cell V9
V12
bts Concentric/DualCoupling/DualBand CellHandover
cpueNumber V12 btsSiteManager Cell Group Management
CPU/BIFP LOAD SHARING
cypherModeReject V8 signallingPoint A5/3 Encryption algorithm
dARPPh1Priority V15 transceiver Network Synchronization
Data14_4OnNoHoppingTs V12 bts PCM Error Correction
data mode 14.4 kbit/s V11 transcoder board PCM Error Correction
data non transparent mode V11 bts PCM Error Correction
data non transparent mode V11 signallingPoint PCM Error Correction
data transparent mode V11 bts PCM Error Correction
data transparent mode V11 signallingPoint PCM Error Correction
delayBetweenRetrans V8 bts Paging command repetition process
directAllocIntFrRxLevDL V18 handOverControl Direct TCH Allocation
directAllocIntFrRxLevUL V18 handOverControl Direct TCH Allocation
directedRetry V9 adjacentCellHandOver Directed Retry Handover
directedRetryModeUsed V9 bts Directed Retry Handover
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directedRetryPrio V12 bts Directed Retry Handover
distHreqt V7 handOverControl Measurement Processing
distWtsList V7 handOverControl Measurement Processing
diversity V7 bts Interference Cancellation
diversityUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
dtxMode V7
V14
bts DTX
EATrafficLoadEnd V18 bts Enhanced Very Early Assignment
EATrafficLoadStart V18 bts Enhanced Very Early Assignment
early classmark sending V10 bts Modified SYS INFO 3
Location Services
earlyClassmarkSendingUTRAN V17 bts GSM to UMTS handover
emergencyCallPriority V7 bts TCH Allocation and Priority
Queuing
enableRepeatedFacchFr V16 bts Repeated Downlink FACCH
enableRepeatedFacchHr V18 bts Repeated Downlink FACCH
encrypAlgoAssComp V8 signallingPoint A5/3 Encryption algorithm
encrypAlgoCiphModComp V8 signallingPoint A5/3 Encryption algorithm
encrypAlgoHoPerf V8 signallingPoint A5/3 Encryption algorithm
encrypAlgoHoReq V8 signallingPoint A5/3 Encryption algorithm
encryptionAlgorSupported V7 bsc A5/3 Encryption algorithm
enhancedTRAUFrameIndication V12 bsc PCM Error Correction
enhCellTieringConfiguration V14 handOverControl Cell Tiering Parameters
estimatedSiteLoad V15 btsSiteManager V15.1 Evolution of Load Balancing
extended cell V9 bts
facchPowerOffset V16 bts Tx Power Offset for Signalling
fDDARFCN V17 adjacentCellUTRAN GSM to UMTS handover
fDDMultiratReporting V17 bts Enhanced Measurement Reporting
GSM to UMTS handover
UTRAN cell reporting using legacymeasurement reports (V17)
fDDreportingThreshold V17 handOverControl Enhanced Measurement Reporting
GSM to UMTS handover
fDDreportingThreshold2 V17 handOverControl Enhanced Measurement Reporting
GSM to UMTS handover
UTRAN cell reporting using legacymeasurement reports (V17)
fhsRef V7 channel Frequency Hopping filteredTrafficCoefficient V15 bts AMR based on traffic
fnOffset V15 btsSiteManager Network Synchronization
forced handover algo V9 adjacentCellHandOver Forced Handover
fullHRCellLoadEnd V18 bts AMR Maximization
fullHRCellLoadStart V18 Bts AMR Maximization
frAMRPriority V14 transceiver AMR Channel allocation
frPowerControlTargetMode V14 transceiver AMR Power Control
frPowerControlTargetModeDl V16 powerControl AMR Power Control
gprsNetworkModeOperation V15 bts Network Mode of Operation I support in BSS
gprsPreemptionForHR V17 bsc pDTCH Preemption by AMR HR calls
gsmToUmtsReselection V14 bts 2G - 3G Cell Reselection
gsmToUMTSServiceHo V17 bsc GSM to UMTS handover
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handOver from signalling channel V7 handOverControl Direct TCH Allocation and Handover Algorithms
hoMargin V7 adjacentCellHandOver Handovers
Power budget formula
Handover for traffic reasons
Define eligible neighbor cells for intercellhandover
Automatic handover adaptation
hoMarginAMR V14 adjacentCellHandOver AMR Handover mechanisms
Handovers
hoMarginAMRUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
hoMarginBeg V11 bts Handovers
Early HandOver Decision
Automatic handover adaptation
Direct TCH Allocation
hoMarginDist V8 adjacentCellHandOver Handover condition for leaving a cell ondistance
Define eligible neighbor cells for intercellhandover
hoMarginDistUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
hoMarginRxLev V8 adjacentCellHandOver Handovers
Define eligible neighbor cells for intercellhandover
hoMarginRxLevUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
hoMarginRxQual V8 adjacentCellHandOver Handovers
Define eligible neighbor cells for intercell
handover hoMarginRxQualUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
hoMarginTiering V14 handOverControl Automatic cell tiering
hoMarginTrafficOffset V12 adjacentCellHandOver Handover for traffic reasons
hoMarginTrafficOffsetUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
hoMarginUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
hoPingpongCombination V12
V14
adjacentCellHandOver General protection against HO ping-pong
hoPingpongCombinationUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
hoPingpongTimeRejection V12 adjacentCellHandOver General protection against HO ping-pong
hoPingpongTimeRejectionUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
hoppingSequenceNumber V7 frequencyHopSystem Synthesised frequency hopping
hoRejectionTimeOverloadUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
hoSecondBestCellConfiguration V9 bsc Handover to 2nd best candidate when returnto old channel
hoTraffic V12 bsc Handover for traffic reasons
hoTraffic V12 bts Handover for traffic reasons
hrAMRPriority V14 transceiver AMR Channel allocation
hrCellLoadEnd V14 bts AMR Channel allocation
hrCellLoadStart V14 bts AMR Channel allocation
hrPowerControlTargetMode V14 powerControl AMR Power Control
hrPowerControlTargetModeDl V16 powerControl AMR Power Control
incomingHandOver V7 handOverControl Handovers
interBscDirectedRetry V9 bsc Directed Retry Handover
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interBscDirectedRetryFromCell V9 bts Directed Retry Handover
interCellHOExtPriority V7 bts TCH Allocation and Priority
Queuing
interCellHOIntPriority V7 bts TCH Allocation and Priority Queuing
interferenceType V12 adjacentCellHandover Automatic cell tiering
interferer cancel algo usage V10 bts Interference Cancellation
intraBscDirectedRetry V9 bsc Directed Retry Handover
intraBscDirectedRetryFromCell V9 bts Directed Retry Handover
intraCell V7
V12
handOverControl Intracell Handover decision for signal quality
intraCellHOIntPriority V7 bts TCH Allocation and Priority
Queuing
intraCellQueuing V8 bts Queuing
intraCellSDCCH V8 handOverControl Intracell Handover decision for signal quality
layer3MsgCyphModComp V8 signallingPoint A5/3 Encryption algorithm
locationAreaCodeUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
lRxLevDLH V7 handOverControl Handover condition for leaving a cell on rxlev
Define eligible neighbor cells for intercellhandover
lRxLevDLP V7 powerControl Power Control Algorithms
AMR Power Control
lRxLevULH V7 handOverControl Handover condition for leaving a cell on rxlev
lRxLevULP V7 powerControl Power Control Algorithms
AMR Power Control
lRxQualDLH V7 handOverControl Handover condition for leaving a cell on rxqual lRxQualDLP V7 powerControl Power Control Algorithms
AMR Power Control
lRxQualULH V7 handOverControl Handover condition for leaving a cell on rxqual
lRxQualULP V7 powerControl Power Control Algorithms
AMR Power Control
maio V7 channel Synthesised frequency hopping
masterBtsSmId V15 btsSiteManager Network Synchronization
maxNumberRetransmission V8 bts Request access command repetition process
measurementProcAlgorithm V12 bts Measurement Processing
Direct TCH Allocation and Handover Algorithms
microCellCaptureTimer V8 adjacentCellHandOver Microcellular Algo
microCellStability V8 adjacentCellHandOver Microcellular Algo
minNbOfTDMA V7 bts
missDistWt V7 handOverControl Measurement Processing
missRxLevWt V7 handOverControl Measurement Processing
missRxQualWt V7 handOverControl Measurement Processing
mobileCountryCodeUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
mobileNetworkCodeUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
mobileAllocation V7 frequencyHopSystem Synthesised frequency hopping
Baseband Frequency Hopping
modeModifyMandatory V9 bsc Directed Retry Handover
msBtsDistanceInterCell V7 handOverControl Handovers screening
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Handover condition for leaving a cell ondistance
msRangeMax V7 handOverControl Handover condition for leaving a cell ondistance
msTxPwrMax V7 bts Accuracy related to measurements
General formulas
Forced Handover
Power Control Algorithms
msTxPwrMax2ndBand V12 bts Concentric/DualCoupling/DualBand CellHandove
msTxPwrMaxCCH V7 bts Selection, Reselection Algorithms
msTxPwrMaxCell V7 adjacentCellHandOver General formulas
Handovers screening
Directed Retry Handover: BTS
Forced Handover
Define eligible neighbor cells for intercellhandover
Power Control Algorithms
multi band reporting V10 bts Multiband reporting
Enhanced Measurement Reporting
GSM to UMTS handover
nbLargeReuseDataChannels V14 bts Automatic cell tiering
nbOfRepeat V8 bts Paging command repetition process
nCapacityFRRequestedCodec V14 handOverControl AMR Handover mechanisms
neighDisfavorOffset V14 handOverControl Automatic handover adaptation
new power control algorithm V9
V12
powerControl Power Control Algorithms
nFRRequestedCodec V14 handOverControl AMR Handover mechanisms
nHRRequestedCodec V14 handOverControl AMR Handover mechanisms
noOfBlocksForAccessGrant V7 bts Paging command Process
noOfMultiframesBetweenPaging V7 bts Paging command Process
notAllowedAccessClasses V7 bts Barring of access class
numberOfPwciSamples V14 handOverControl Automatic cell tiering
numberOfSlotsSpreadTrans V7 bts Request access command repetition process
numberOfTCHFreeBeforeCongestion V9 bts Barring of access class
Handover for traffic reasons
numberOfTCHFreeToEndCongestion V9 bts Barring of access class
Handover for traffic reasons
numberOfTCHQueuedBeforeCongestion V9 bts Barring of access class Handover for traffic reasons
numberOfTCHQueuedToEndCongestion V9 bts Barring of access class
Handover for traffic reasons
offsetLoad V12 adjacentCellHandover Handover decision according to adjacent cellpriorities ans load
offsetPriority V12 adjacentCellHandover Handover decision according to adjacent cellpriorities ans load
offsetPriorityUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
otherServicesPriority V7 bts TCH Allocation and Priority
Queuing
pagingOnCell V9 bts PCH and RACH channel control
pcmErrorCorrection V12 bts PCM Error Correction
penaltyTime V8 bts Selection, Reselection Algorithms
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powerBudgetInterCell V7 handOverControl Handovers screening
Power budget formula
Handover for traffic reasons
powerControlIndicator V7 bts Power Control Algorithms
powerIncrStepSizeDL V14 powerControl Power Control Algorithms
powerIncrStepSizeUL V14 powerControl Power Control Algorithms
powerRedStepSizeDL V14 powerControl Power Control Algorithms
powerRedStepSizeUL V14 powerControl Power Control Algorithms
preemptionAuthor V15 signallingPoint eMLPP Preemption
pRequestedCodec V14 handOverControl AMR Handover mechanisms
preSynchroTimingAdvance V10 adjacentCellHandOver Pre-synchronized HO
priority V7 transceiver
processorLoadSupConf V8
V12
bsc BSC Overload Management Mechanisms
pwciHreqave V14 handOverControl Automatic cell tiering
minTimeQualityIntraCellHO V14 handOverControl Protection against Intracell HO Ping-Pong
AMR Handover mechanisms
qsearchC V17 handOverControl Enhanced Measurement Reporting
GSM to UMTS handover
UTRAN cell reporting using legacymeasurement reports (V17)
radChanSelIntThreshold V8 handOverControl Interference Management
radioLinkTimeout V7 bts Radio link failure process
radResSupBusyTimer V8 bsc
radResSupervision V8 bts
radResSupFreeTimer V8 bsc
reportTypeMeasurement V17 bts Enhanced Measurement Reporting
GSM to UMTS handover
retransDuration V8 bts
rlf1 V8 bts Radio link failure process
rlf2 V8 bts Radio link failure process
rlf3 V8 bts Radio link failure process
rNCId V17 adjacentCellUTRAN GSM to UMTS handover
rndAccTimAdvThreshold V8 bts Request access command process
runCallClear V7 bts Call Clearing Process
runHandOver V7 bts Handovers
Microcellular Algo
Protection against RunHandover=1
runPwrControl V7 bts Power Control Algorithms
AMR Power Control
rxLevAccessMin V7 bts Selection, Reselection Algorithms
rxLevDLIH V7 handOverControl Intracell Handover decision for signal quality
rxLevDLPBGT V11 adjacentCellHandOver Handovers screening
Maximum RxLev for Power Budget
rxLevDLPbgtUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
rxLevHreqave V7 handOverControl Measurement Processing
rxLevHreqaveBeg V11 handOverControl Early HandOver Decision
Automatic handover adaptation
Fast power control at TCH assignment
rxLevHreqt V7 handOverControl Measurement Processing
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rxLevMinCell V7 adjacentCellHandOver General formulas
Handovers screening
Define eligible neighbor cells for intercellhandover
rxLevMinCellUTRAN V17 adjacentCellUTRAN GSM to UMTS handover
rxLevNCellHreqaveBeg V11 handOverControl Early HandOver Decision
Automatic handover adaptation
Fast power control at TCH assignment
rxLevULIH V7 handOverControl Intracell Handover decision for signal quality
rxLevWtsList V7 handOverControl Measurement Processing
rxNCellHreqave V7 handOverControl Measurement Processing
Early HandOver Decision
Automatic handover adaptation
rxQualAveBeg V14 handOverControl Automatic handover adaptation
rxQualDLIH V7 handOverControl Intracell Handover decision for signal quality
rxQualHreqave V7 handOverControl Measurement Processing rxQualHreqt V7 handOverControl Measurement Processing
rxQualULIH V12 handOverControl Intracell Handover decision for signal quality
rxQualWtsList V12 handOverControl Measurement Processing
sacchPowerOffset V16 bts Tx Power Offset for Signalling
sacchPowerOffsetSelection V16 bts Tx Power Offset for Signalling
scramblingCode V17 adjacentCellUTRAN GSM to UMTS handover
selfAdaptActivation V14 bts Automatic handover adaptation
selfTuningObs V12 handOverControl Automatic cell tiering
servingBandReporting V17 bts Enhanced Measurement Reporting
GSM to UMTS handover
servingBandReportingOffset V17 handOverControl Enhanced Measurement Reporting GSM to UMTS handover
servingfactorOffset V14 handOverControl Automatic handover adaptation
sharedPDTCHratio V18 bts AMR Maximization , AMR Channel allocation
siteGsmFctList V7 btsSiteManager
small to large zone HO priority V9 handOverControl TCH Allocation and Priority
Queuing
smartPowerManagementConfig V17 PowerControl BTS Smart Power Management
smartPowerSwitchOffTimer V17 PowerControl BTS Smart Power Management
smsCB V7 bts SMS-Cell Broadcast
speechMode V8
V14
bts AMR - Adaptative Multi Rate FR/HR
speechMode V8
V14
signallingPoint AMR - Adaptative Multi Rate FR/HR
standard indicator AdjC V10
V12
adjacentCellHandover Dual Band Handling
standard indicator AdjC V10
V12
adjacentCellReselect Dual Band Handling
standardIndicator V12 bts Concentric/DualCoupling/DualBand CellHandover
synchronized V7 adjacentCellHandOver Pre-synchronized HO
Handover Algorithms on the Mobile Side
t3101 V9 btst3103 V9 bts
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t3107 V9 bts
t3109 V9 bts
t3111 V9 bts
t3121 V17 bts GSM to UMTS handover
t3122 V9 bts
temporaryOffset V8 bts Selection, Reselection Algorithms
thresholdInterference V7 handOverControl Radio channel allocation
Interference Management
timeBetweenHOConfiguration V9
V12
bsc Power Budget Handover
General protection against HO ping-pong
timerPeriodicUpdateMS V7 bts
tnOffset V15 btsSiteManager Network Synchronization
trafficPCMAllocationPriority V9 transceiver
transceiver equipment class V9 transceiverEquipment Concentric/DualCoupling/DualBand CellHandover
transceiver equipment class V9 transceiverZone Concentric/DualCoupling/DualBand CellHandover
transceiverZone V9 transceiver Concentric/DualCoupling/DualBand CellHandover
3GAccessMinLevel V14 bts 2G - 3G Cell Reselection
3GReselectionARFCN V14 bts 2G - 3G Cell Reselection
3GReselectionOffset V14 bts 2G - 3G Cell Reselection
3GSearchLevel V14 bts 2G - 3G Cell Reselection
3GTechnology V18 bts 2G - 3G Cell Reselection
uplinkPowerControl V8 powerControl Power Control Algorithms
AMR Power Control
uRxLevDLP V7 powerControl Power Control Algorithms
uRxLevULP V7 powerControl Power Control Algorithms
uRxQualDLP V7 powerControl Power Control Algorithms
uRxQualULP V7 powerControl Power Control Algorithms
VEASDCCHOverflowAllowed V18 bts Enhanced Very Early Assignment
wPSManagement V15 bsc WPS - Wireless Priority Service
wPSQueueStepRotation V15 bts WPS - Wireless Priority Service
zone Tx power max reduction V9 transceiverZone Concentric/DualCoupling/DualBand CellHandover
zoneFrequencyHopping V9 transceiverZone Concentric/DualCoupling/DualBand CellHandover
zoneFrequencyThreshold V9 transceiverZone Concentric/DualCoupling/DualBand Cell
Handover
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3.4. PARAMETERS VERSUS BSS FEATURES AND PROCEDURES
Here is the list of the main BSS tunable parameters sorted by procedure or feature.
3.4.1 2G CELL SELECTION AND RESELECTION
cellBarQualify, cellBarred, rxLevAccessMin, msTxPwrMaxCCH, cellReselInd,
cellReselectHysteresis, cellReselectOffset, temporaryOffset, penaltyTime,
rndAccTimAdvThreshold.
3.4.2 2G-3G UTRAN FDD & TDD CELL RESELECTION
3GAccessMinLevel, 3GReselectionARFCN, 3GReselectionOffset, 3GSearchLevel.
3GTechnology
3.4.3 LEGACY MEASUREMENT REPORTING
multiBandReporting, powerControlIndicator , fDDMultiratReporting, fDDreportingThreshold2 ,
qsearchC
3.4.4 ENHANCED MEASUREMENT REPORTING
multiBandReporting, reportTypeMeasurement, servingBandReportingOffset ,
servingBandReporting, fDDMultiratReporting, fDDreportingThreshold,fDDreportingThreshold2, qsearchC
3.4.5 LEVEL AVERAGING
rxLevHreqave, rxLevHreqt, rxLevWtsList, missRxLevWt, rxLevHreqaveBeg.
3.4.6 QUALITY AVERAGING
rxQualHreqave, rxQualHreqt, rxQualWtsList, missRxQualWt.
3.4.7 DISTANCE AVERAGING
distHreqt, distWtsList, missDistWt.
3.4.8 CELL ELIGIBILITY
rxLevMinCell, rxNCellHreqave, cellDeletionCount, rxLevHreqave, missRxLevWt,
msTxPwrMaxCell, msTxPwrMax, hoSecondBestCellConfiguration , rxLevNCellHreqaveBeg.
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3.4.9 RADIO LINK FAILURE
radioLinkTimeOut, rlf1, rlf2, rlf3, t3111, t3109.
3.4.10 INTERFERENCE MANAGEMENT
averagingPeriod, thresholdInterference, radChanSelIntThreshold.
3.4.11 PCH AND RACH CONTROL PARAMETERS
delayBetweenRetrans, maxNumberRetransmission , nbOfRepeat, noOfBlocksForAccessGrant ,
noOfMultiframesBetweenPaging , numberOfSlotsSpreadTrans, pagingOnCell, retransDuration,
t3122, gprsNetworkModeOperation, bssPagingCoordination.
3.4.12 CONCENTRIC CELL
concentric cell, concentAlgoExtMsRange, concentAlgoExtRxLev, concentAlgoExtRxLevUL,
concentAlgoIntMsRange, concentAlgoIntRxLev, concentAlgoIntRxLevUL,
directAllocIntFrRxLevDL , directAllocIntFrRxLevUL , transceiverEquipmentClass ,
transceiverZone, zoneFrequencyHopping, zoneFrequencyThreshold, small to large zone HO
Priority, zone Tx power max reduction, biZonePowerOffset, biZonePowerOffset(n),
rxLevMinCell(n).
3.4.13 EXTENDED CELL
extended cell, rndAccTimAdvThreshold, msRangeMax, callClearing, channelType.
3.4.14 QUEUING AND PRIORITY MANAGEMENT
allocPriorityTable, allocPriorityTimers, allocPriorityThreshold , allocWaitThreshold,
allOtherCasesPriority, answerPagingPriority, assignRequestPriority, bscQueuingOption,
callReestablishmentPriority, emergencyCallPriority, interCellHOExtPriority,
interCellHOIntPriority, intraCellHOIntPriority, otherServicesPriority, small to large zone HO
Priority, directedRetryPrio, intraCellQueuing.
3.4.15 EMLPP PREEMPTION
preemptionAuthor .
3.4.16 SMS-CB
smsCB, noOfBlocksForAccessGrant , channelType.
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3.4.17 FREQUENCY HOPPING
btsIsHopping, hoppingSequenceNumber , maio, siteGsmFctList, cellAllocation,
mobileAllocation, fhsRef , bscHopReconfUse, btsHopReconfRestart, btsThresholdHopReconf ,
zoneFrequencyHopping, zoneFrequencyThreshold.
3.4.18 DYNAMIC BARRING OF ACCESS CLASS
bscMsAccessClassBarringFunction, btsMsAccessClassBarringFunction,
accessClassCongestion, numberOfTCHFreeBeforeCongestion ,
numberOfTCHFreeToEndCongestion , numberOfTCHQueuedBeforeCongestion ,
numberOfTCHQueuedToEndCongestion, notAllowedAccessClasses.
3.4.19 DTX
dtxMode, cellDtxDowlink.
3.4.20 UPLINK POWER CONTROL
uplinkPowerControl, new power control algorithm, runPowerControl, , powerIncrStepSizeUL,
powerRedStepSizeUL, lRxQualULP, uRxQualULP, lRxLevULP, uRxLevULP, msTxPwrMax,
msTxPwrMax2ndBand.
3.4.21 DOWNLINK POWER CONTROL
bsPowerControl, new power control algorithm, runPwrControl, powerIncrStepSizeDL,
powerRedStepSizeDL, lRxQualDLP, uRxQualDLP, lRxLevDLP, uRxLevDLP.
3.4.22 DIRECTED RETRY HANDOVER
interBscDirectedRetry, intraBscDirectedRetry, interBscDirectedRetryFromCell,
intraBscDirectedRetryFromCell, modeModifyMandatory, directedRetryModeUsed,
msTxPwrMaxCell, msTxPwrMax, directedRetry, adjacent cell umbrella ref , directedRetryPrio.
3.4.23 UPLINK INTRACELL HANDOVER
intraCell, intraCellSDCCH, runHandOver , rxLevULIH, lrxQualULH, rxQualULIH.
3.4.24 DOWNLINK INTRACELL HANDOVER
intraCell, intraCellSDCCH, runHandOver , rxLevDLIH, lRxQualDLH, rxQualDLIH.
3.4.25 INTERCELL HANDOVER ON BAD UPLINK QUALITYCRITERION
handOver from signalling channel, runHandOver , lrxQualULH, hoMarginRxQual.
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3.4.26 INTERCELL HANDOVER ON BAD DOWNLINK QUALITYCRITERION
handOver from signalling channel, runHandOver , lRxQualDLH, hoMarginRxQual.
3.4.27 INTERCELL HANDOVER ON BAD UPLINK LEVEL CRITERION
handOver from signalling channel, runHandOver , lRxLevULH, hoMarginRxLev.
3.4.28 INTERCELL HANDOVER ON BAD DOWNLINK LEVELCRITERION
handOver from signalling channel, runHandOver , lRxLevDLH, hoMarginRxLev.
3.4.29 INTERCELL HANDOVER ON POWER BUDGET CRITERION
handOver from signalling channel, runHandOver , powerBudgetInterCell , hoMargin,
rxLevDLPBGT.
3.4.30 MICROCELLULAR ALGORITHM
handOver from signalling channel, runHandOver , cellType, microCellCaptureTimer ,
microCellStability, rxNCellHreqave.
3.4.31 INTERCELL HANDOVER ON DISTANCE CRITERION
msBtsDistanceInterCell, handOver from signalling channel, runHandOver ,hoMarginDist.
3.4.32 HANDOVER FOR TRAFFIC REASONS
handOver from signalling channel, runHandOver , hoTraffic, hoMarginTrafficOffset .
3.4.33 HANDOVER DECISION ACCORDING TO ADJACENT CELL
handOver from signalling channel, runHandOver , offsetLoad, offsetPriority.
3.4.34 GENERAL PROTECTION AGAINST HO PINGPONG
hoPingpongCombination, hoPingpongTimeRejection.
3.4.35 CALL CLEARING
callClearing, runCallClear .
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3.4.47 GSM TO UMTS HANDOVER
gsmToUMTSServiceHO, earlyClassmarkSendingUTRAN , compressedModeUTRAN,
mobileCountryCodeUTRAN, mobileNetworkCodeUTRAN, locationAreaCodeUTRAN, rNCId,
cId, fDDARFCN, scramblingCode, diversityUTRAN, t3121, rxLevMinCellUTRAN,
rxLevDLPbgtUTRAN, hoMarginUTRAN, hoMarginAMRUTRAN, hoMarginRxLevUTRAN,
hoMarginRxQualUTRAN, hoMarginDistUTRAN, hoMarginTrafficOffsetUTRAN ,
offsetpriorityUTRAN, hoPingpongCombinationUTRAN, hoPingpongTimeRejectionUTRAN ,
hoRejectionTimeOverloadUTRAN
3.4.48 ADAPTATIVE FULL/HALF RATE
amrDlFrAdaptationSet, amrDlHrAdaptationSet, amrUlFrAdaptationSet, amrUlHrAdaptationSet,coderPoolConfiguration, speechMode, HRCellLoadStart, HRCellLoadEnd, frAMRPriority,
hrAMRPriority, hrPowerControlTargetMode, hrPowerControlTargetModeDl,
frPowerControlTargetMode, frPowerControlTargetModeDl, bsPowerControl,
uplinkPowerControl, pRequestedCodec, nHRRequestedCodec, nFRRequestedCodec,
amrFRIntercellCodecMThresh , amrFRIntracellCodecMThresh , amrHRIntercellCodecMThresh ,
amrHRtoFRIntracellCodecMThresh , hoMarginAMR, amriRxLevDLH, amriRxLevULH,
nCapacityFRRequestedCodec , amrDirectAllocIntRxLevDL, amrDirectAllocIntRxLevUL,
amrDirectAllocRxLevDL, amrDirectAllocRxLevUL, filteredTrafficCoefficient,
gprsPreemptionForHR.
3.4.49 WIRELESS PRIORITY SERVICE
allocPriorityTable, allocPriorityTimers, allocWaitThreshold, bscQueuingOption,
wPSManagement, wPSQueueStepRotation.
3.4.50 NETWORK SYNCHRONIZATION
btsSMSynchroMode, tnOffset, fnOffset, dARPPh1Priority, masterBtsSmId, baseColourCode
3.4.51 REPEATED DOWNLINK FACCHenableRepeatedFacchFr , enableRepeatedFacchHr
3.4.52 TX POWER OFFSET FOR SIGNALLING
facchPowerOffset, sacchPowerOffset, sacchPowerOffsetSelection
3.4.53 NOVEL ADAPTIVE RECEIVER
adaptiveReceiver
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3.4.54 A5/3 ENCRYPTION ALGORITHM
cypherModeReject, encrypAlgoAssComp, encrypAlgoCiphModComp, encrypAlgoHoPerf ,
encrypAlgoHoReq, encryptionAlgorSupported , layer3MsgCyphModComp
3.4.55 BTS SMART POWER MANAGEMENT
smartPowerManagementConfig , smartPowerSwitchOffTimer
3.4.56 ENHANCED VERY EARLY ASSIGNMENT
EATrafficLoadEnd, EATrafficLoadStart, VEASDCCHOverflowed
3.4.57 AMR MAXIMIZATION
fullHRCellLoadEnd, fullHRCellLoadStart, sharedPDTCHratio
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4. ALGORITHMS
4.1. INTRODUCTION
This chapter describes major BSS GSM algorithms using OMC-R algorithm parameters, both
on the BTS and the MS side.
4.2. CONVENTIONS AND UNITS
In this chapter, the following abbreviations are used:
• RXQUAL_DL: weighted average for DL signal quality (MS measurements)
• RXQUAL_UL: weighted average for UL signal quality (BTS measurements)• RXLEV_DL: weighted average for DL signal strength (MS measurements)
• RXLEV_UL: weighted average for UL signal strength (BTS measurements)
• MS_BS_Dist: weighted average of MS distance from BTS (MS timing
advance)
• RXLEV_NCELL(n): arithmetic average for signal strength on neighbor cell
(reported by the MS)
4.2.1 UNIT
Thresholds on signal quality are given in RXQUAL values. Samples measurements are also
reported in RXQUAL values. When internal calculations are performed, RXQUAL values are
converted into bit error rates (BER) using mean values and compared to thresholds which are
also converted into bit error rate. From the V9 BSS release, the comparison is done with the
upper or the lower limit of the BER range.
RxQual value BER range value Mean BER value
0 BER < 0.2% 0.14%
1 0.2% < BER < 0.4% 0.28%
2 0.4% < BER < 0.8% 0.57%
3 0.8% < BER < 1.6% 1.13%
4 1.6% < BER < 3.2% 2.26%
5 3.2% < BER < 6.4% 4.53%
6 6.4% < BER < 12.8% 9.05%
7 12.8% < BER 18.10%
Signal strength thresholds are given in dBm (from -110 dBm to -47 dBm).
Signal strength measurements reported by the mobiles and the BTS are given in the rxlev
format (from 0 to 63).
The average signal strength measurement values, which are compared to the rxlev
thresholds, are the integer part of the average result.
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4.2.2 PHASE 2 BTS AND MS MAXIMUM TRANSMITTING OUTPUT POWERS
MOBILE PHASE 2 MAXIMUM TRANSMITTING OUTPUT POWER
PowerClass
GSM 850 / GSM 900
Nominal MaximumOutput Power
DCS 1800
Nominal MaximumOutput Power
PCS 1900
Nominal MaximumOutput Power
Tolerance forcondition
Normal Extreme
1 restricted MS Phase 1 1W (30 dBm) 1W (30 dBm) +/- 2 dB +/- 2,5 dB
2 8W (39 dBm) 0,25W (24 dBm) 0,25W (24 dBm) +/- 2 dB +/- 2,5 dB
3 5W (37 dBm) 4W (36 dBm) 2W (33 dBm) +/- 2 dB +/- 2,5 dB
4 2W (33 dBm) +/- 2 dB +/- 2,5 dB
5 0,8W (29 dBm) +/- 2 dB +/- 2,5 dB
ASSOCIATED POWER CONTROL LEVELS
GSM 850 / GSM 900
Powercontrol
level
NominalOutputpower(dBm)
Tolerance(dB) for
conditions
N E0-2 39 ± 2 ± 2,5
3 37 ± 3 ± 4
4 35 ± 3 ± 4
5 33 ± 3 ± 4
6 31 ± 3 ± 4
7 29 ± 3 ± 4
8 27 ± 3 ± 4
9 25 ± 3 ± 4
10 23 ± 3 ± 4
11 21 ± 3 ± 4
12 19 ± 3 ± 4
13 17 ± 3 ± 4
14 15 ± 3 ± 4
15 13 ± 3 ± 4
16 11 ± 5 ± 6
17 9 ± 5 ± 6
18 7 ± 5 ± 6
19-31 5 ± 5 ± 6
DCS 1800
Powercontrol
level
NominalOutputpower(dBm)
Tolerance(dB) for
conditions
N E29 36 ± 2 ± 2,5
30 34 ± 3 ± 4
31 32 ± 3 ± 4
0 30 ± 3 ± 4
1 28 ± 3 ± 4
2 26 ± 3 ± 4
3 24 ± 3 ± 4
4 22 ± 3 ± 4
5 20 ± 3 ± 4
6 18 ± 3 ± 4
7 16 ± 3 ± 4
8 14 ± 3 ± 4
9 12 ± 4 ± 5
10 10 ± 4 ± 5
11 8 ± 4 ± 5
12 6 ± 4 ± 5
13 4 ± 4 ± 5
14 2 ± 5 ± 6
15-28 0 ± 5 ± 6
PCS 1900
Powercontrol
level
NominalOutputpower(dBm)
Tolerance(dB) for
conditions
N E22-29 Reserved
30 33 ± 3 ± 4
31 32 ± 3 ± 4
0 30 ± 3 ± 4
1 28 ± 3 ± 4
2 26 ± 3 ± 4
3 24 ± 3 ± 4
4 22 ± 3 ± 4
5 20 ± 3 ± 4
6 18 ± 3 ± 4
7 16 ± 3 ± 4
8 14 ± 3 ± 4
9 12 ± 4 ± 5
10 10 ± 4 ± 5
11 8 ± 4 ± 5
12 6 ± 4 ± 5
13 4 ± 4 ± 5
14 2 ± 5 ± 6
15 0 ± 5 ± 6
16-21 Reserved
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BASE STATION PHASE 2 MAXIMUM TRANSMITTING OUTPUT POWERS
GSM 850 / GSM 900 GSM 1800 / GSM 1900 Tolerance for condition
Normal ExtremeCLASS 1: [320 - 640[ W [55 - 58[ dBm CLASS 1: [20 - 40[ W [43 - 46[ dBm +/- 2 dB +/- 2,5 dB
CLASS 2: [160 - 320[ W [55 - 58[ dBm CLASS 2: [10 - 20[ W [40 - 43[ dBm +/- 2 dB +/- 2,5 dB
CLASS 3: [80 -160[ W [49 - 52[ dBm CLASS 3: [5 - 10[ W [37 - 40[ dBm +/- 2 dB +/- 2,5 dB
CLASS 4: [40 - 80[W [46 - 49[ dBm CLASS 4: [2.5 - 5[ W [34 - 37[ dBm +/- 2 dB +/- 2,5 dB
CLASS 5: [20 - 40[ W [43 - 46[dBm +/- 2 dB +/- 2,5 dB
CLASS 6: [10 - 20[ W [40 - 43[ dBm +/- 2 dB +/- 2,5 dB
CLASS 7: [5 - 10[ W [37 - 40[ dBm +/- 2 dB +/- 2,5 dB
CLASS 8: [2.5 - 5[ W [34 - 37[ dBm +/- 2 dB +/- 2,5 dB
Settings will be provided to allow output power to be reduced from its maximum level to at
least six steps of nominally 2 dB with an accuracy of ≈1 dB to allow a fine adjustment of the
coverage by the network operator. In addition, the actual absolute output power at each static
RF power step (N) shall be 2*N dB below the absolute output power at static RF power step 0
with a tolerance of ≈3 dB under normal conditions and ≈4dB under extreme conditions. The
static RF power step 0 will be the actual output power according to the TRX power class.
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4.2.3 GSM PRODUCTS SENSITIVITY AND POWER
Please refer to the following documents for information on main RF characteristics of the
Nortel BTS portfolio :
BTS S2000L Engineering Rules : [R47]
BTS S2000H Engineering Rules : [R48]
BTS S4000 Outdoor Engineering Rules : [R49]
BTS S4000 Indoor Engineering Rules : [R50]
BTS eCell Engineering Rules : [R51]
BTS S8000-S8003 Indoor & S8000 Outdoor Engineering Rules : [R52]
BTS S12000 Indoor & Outdoor Engineering Rules : [R53]
BTS 18000 Indoor & Outdoor Engineering Rules : [R54]
BTS 18000 GSM-UMTS Indoor & Outdoor Engineering Rules : [R55]
BTS 6000 GSM Indoor & Outdoor Engineering Rules : [R56]
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4.2.4 CONVERSION RULES
POWER CONVERSION
The main power conversion rules are provided below.
P (dB) = P (dBW) = 10 log (PW)
P (dBm) = P (dBmW) = 10 log (PmW)
P (dB) = P (dBm) - 30
E (dBV / m) = P (dBm) + 20 log FHz + 77,2
DISTANCE - TIMING ADVANCE CONVERSION
The table below gives the conversion rules of the timing advance versus the distance.
One bit corresponds to 554 m and the accuracy is 0.25 bit (i.e 138.5 m)
Timing Advance Distance (m) Recommendation accuracy
0 [0..554[ 25 %
1 [554..1108[ 12.5 %
2 [1108..1662[ 6.1 %
3 [1662.. 3.1 %
…63 [34 902..35456[ 0.4 %
Due to multipath and to MS synchronization accuracy, the gap of timing advances between
two different MS for a given distance can reach 3 bits (i.e. 1,6 km).
The value of the timing advance has an impact on decision taking for handover and call
clearing. The timing advance is calculated by taking into account all the rays coming from a
same signal.
The timing advance must be used carefully as a handover and call clearing criteria, especially
in a microcellular configuration.
4.2.5 ACCURACY RELATED TO MEASUREMENTS
The GSM recommendation specifies the absolute and relative accuracy of the MS and BTS
measurements (Rec. GSM 05.08 § 8.1.2). The table below provides the GSM absolute
accuracy recommendation.
MS and BTS absolute measurement accuracy
from - 110 dBm to - 70 dBm under normal conditions +/- 4 dB
from - 110 dBm to - 48 dBm under normal conditions +/- 6 dB
from - 110 dBm to - 48 dBm under extreme conditions +/- 6 dB
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The overlap between the different ranges (see above normal condition cases) are specified in
the recommendation.
This recommendation is not restrictive and most of the BTS and MS may provide better
results. However, these figures show that the threshold accuracy handover and power
control field strength may be off by a few dB.
The relative accuracy depends on the gap between measurement levels and sensivity levels.
The table below provides the GSM relative accuracy recommendation of a difference between
two measurements lower than 20 dB.
MS and BTS absolute measurement accuracy
lower measured level > sensitivity + 14 dB + 2 / - 2 dB
sensitivity + 14 dB> lower measured level > sensitivity + 1 dB + 2 / - 3 dB
sensitivity + 1 dB > lower measured level + 2 / - 4 dB
For example, the level difference between two field strengths, which are higher than the
sensivity + 14 dBm, must be within the range of [-2 dB to +2 dB].
Output power tolerance must also be considered in the parameters setting because the
parameters bsTxPwrMax and msTxPwrMax are used in the algorithms.
4.2.6 FREQUENCY BAND
Frequency band Fl(n) [lower band] n range Fu(n) [upper band]
P-GSM 900 Fl(n) = 890 + 0,2 * n 1 ≤ n ≤ 124 Fu(n) = Fl(n) + 45
E-GSM 900
Fl(n) = 890 + 0,2 * n
Fl(n) = 890 + 0,2 * (n - 1024)
0 ≤ n ≤ 124
975 ≤ n ≤ 1023 Fu(n) = Fl(n) + 45
R-GSM 900Fl(n) = 890 + 0,2 * n
Fl(n) = 890 + 0,2 * (n - 1024)
0 ≤ n ≤ 124
955 ≤ n ≤ 1023Fu(n) = Fl(n) + 45
DCS 1800 Fl(n) = 1710,2 + 0,2 * (n - 512) 512 ≤ n ≤ 885 Fu(n) = Fl(n) + 95
PCS 1900 Fl(n) = 1850,2 + 0,2 * (n - 512) 512 ≤ n ≤ 810 Fu(n) = Fl(n) + 80
GSM 450 Fl(n) = 450,6 + 0,2 * (n - 259) 259 ≤ n ≤ 293 Fu(n) = Fl(n) + 10
GSM 480 Fl(n) = 479 + 0,2 * (n - 306) 306 ≤ n ≤ 340 Fu(n) = Fl(n) + 10
GSM 850 Fl(n) = 824,2 + 0,2 * (n - 128) 128 ≤ n ≤ 251 Fu(n) = Fl(n) + 45
GSM 750 Fl(n) = 747,2 + 0,2 * (n - 438) 438 ≤ n ≤ 511 Fu(n) = Fl(n) + 30
Frequencies are in MHz.
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4.3. 2G CELL SELECTION AND RESELECTION
4.3.1 OVERVIEW
NETWORK SELECTION
At switch-on, the mobile is required to select, among a set of PLMNs that is further defined
below, the highest priority PLMN that is both :
• "available"
• and "allowable"
An available PLMN is a PLMN on which a cell has been found that is not barred and where
Rxlev > rxLevAccessMin
An allowable PLMN is a PLMN which is not in the list of "forbidden PLMNs" in the MS.
The set of possible PLMNs and their decreasing order of priority is :
• the last PLMN on which the MS performed a successful registration (Location area
update);
• the Home PLMN (this is the PLMN where the MCC and MNC of the PLMN identity
match the MCC and MNC of the IMSI);
• other PLMNs, in the order explicitely defined in the SIM.
This order of priority is valid, whether the MS is a roamer or not.
CELL SELECTION PROCEDURE:
• The selection process begins with a signal strength measurement averaging on the
whole frequency band lasting approximately three seconds in order to sort channels
according to their strength.
• Then, for the most powerful channel, the MS tries to detect the FCH channel, then
decodes the SCH channel, and if the MNC and MCC are not forbidden, it listens to
SYSTEM INFORMATION 1 to 4 to get full information on that cell and possibly select
it depending on the selection criterion.
• If one of the steps fails, the next powerful channel is tried and so on.
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CELL RESELECTION PROCEDURE:
• Reselection criteria are calculated every 5 to 60 seconds period (depending on the
number of cells for which BCCH is in BCCH Allocation and number of multiframes
between paging) because MS must perform at least 5 measurements on every cell
listed in the BCCH Allocation before averaging is allowed. For phase 1 MS, C1 path
loss criterion is used whereas for phase 2 MS, the C2 criterion is used.
• Then, for the most powerful channel, the MS attempts to detect the FCH channel, then
decodes the SCH channel, and if the NCC and BCC are not forbidden, it will listen to
SYSTEM INFORMATION 1 to 4 to get full information on that cell and possibly select
it depending on the selection criterion.
4.3.2 SELECTION OR RESELECTION BETWEEN CELLS OFCURRENT LOCATION AREA
In Phase 1, MS checks that cellBarred flag is not set to “barred” before sorting eligible cells.
In Phase 2, MS checks cellBarred and cellBarQualify flags in order to define the cell’s access
(normal,low,barred).
C1 is the path loss criterion for unbarred cells of allowed PLMN.
To be selected, a cell must have a positive C1:
C1 = RXLEV - rxLevAccessMin - Max (B,0) >0with B = msTxPwrMaxCCH - P
P = maximum RF output power of the MS
Received levels must be higher than rxlevAccessMin and if a mobile state has a classmark
lower than msTxPwrMaxCCH, it must get closer to the cell to have access to it.
4.3.3 RESELECTION TO A CELL OF A DIFFERENT LOCATION AREA
This is an additionnal criteria for reselection towards a “y” cell having a different Location Areafrom the current one. A choice must be made between C1 values for cell having a different
Location Area:
C1(x) < C1(y) - cellReselectHysteresis
The value used for the parameter cellReselectHysteresis is the-one set in the current serving
cell.
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4.3.4 ADDITIONAL RESELECTION CRITERION (FOR PHASE 2)
In Phase 2, MS checks cellBarred and cellBarQualify flags in order to define the cell’s access
(normal, low, barred).
To activate this feature, the cellReselInd parameter will be set to “true”.
The C1 criterion did not provide a way of preventing a fast moving mobile station from
reselecting a “fugitive cell” nor avoiding ping-pong reselection. The idea is to give a cell a
tunable access for reselection and to prevent mobiles from reselecting a cell if that cell is new
to the mobile or if it was recently the serving cell:
C2 = C1 + cellReselectOffset - temporaryOffset * H (penaltyTime - t)
for penaltyTime ≠ 640
C2 = C1 - cellReselectOffset
for penaltyTime = 640
where t is a timer started as soon as a cell enters the mobile best cell list:
• t = penaltyTime if the new cell in the list is the previous serving
cell
• t = 0 otherwise
and H(x) is a function:
• H(penaltyTime - t) = 0 if t ≥ penaltyTime
• H(penaltyTime - t) = 1 if t < penaltyTimetemporaryOffset is a negative offset.
By adding an offset (cellReselectOffset) it is possible to give different priorities, for example, to
different types of cells in case of a multilayer network or to different bands when multiband
operation is used.
The timer penaltyTime ensures that the mobile will reselect a cell which has been received
with a sufficient level for a sufficient time. Some microcellular handover algorithms are based
on this C2 reselection principle.
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Priority of access: cellBarred and cellBarQualify parameters.
The parameters are used to give each cell the authorization to be selected or reselected, and
for all of them a priority of access is given.
The selection procedure is mainly concerned by this priority introduction.
SELECTION
For the server cell and the neighboring cells, the C1 algorithm is computed. The C2 algorithm
is computed only if cell reselection is used (cellReselInd = true).
A priority is affected to each eligible cell and is only applied to Phase II MS.
IF cellBarQualify = TRUE THEN the cell priority is “low”, whatever the “cellBarred” value is.
IF cellBarQualify = FALSE AND IF the cell is barred (cellBarred set to “barred”) THEN the cell
priority is null (the cell can not be reselected in idle mode).
IF cellBarQualify = FALSE AND IF the cell is not barred THEN the priority is “normal”.
For a mobile Phase II: if no cell with NORMAL priority is eligible (cell contained in the eligible
list constituted using the C1 algorithm), then the cells with LOW priority are scanned. So even
if a cell is barred, a phase II mobile is able to select this cell, but it will not be able to perform a
call on it.
For a mobile Phase I: it is not possible to reselect a cell that is barred.
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cellBarred cellBarQualify Priority
barred false no selection possible
barred true low
not barred false normal
not barred true low
Note: To forbid the access of a cell to a MS, the cellBarred set to “not barred” and
incomingHandover set to ”disabled”, is not sufficient. Care must be taken with the
cellBarQualify that gives the priority.
RESELECTION
There is only one kind of priority which is NORMAL.
IF the cell is barred
AND IF cellBarQualify is false
THEN the reselection is not authorized.
cellBarred cellBarQualify Priority
barred false no selection possible
barred true normal
not barred false normal
not barred true normal
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4.4. 2G - 3G UTRAN FDD & TDD CELL RESELECTION
As 3G is deployed, if GSM access network does not provide "GSM to UMTS mobility" for
mobiles in idle mode, all the dual-mode mobiles (e.g. mobile supporting both GSM andUTRAN/FDD radio access technologies) will be stuck on GSM cells:
• when leaving UMTS coverage the mobile will reselect a GSM cell
• when on a GSM cell a dual-mode mobile will only reselect a GSM cell
• switching off-on the mobile will not make the mobile reselect UMTS, since
the mobile is first looking for its last "Registered technology" at power on
• using a different PLMN for UMTS (being the mutimode subscriber HPLMN)
and GSM layers can help, but this will not work for the operators not taking
this option
The cell reselection GSM to 3G technology (FDD or TDD) does not require any specific
algorithm in the GSM-BSS. The intersystem reselection only requires pieces of information to
be broadcast on the BCCH by the GSM-BSS:
• intersystem cell reselection control parameters (as described later in the
document)
• neighboring 3G cell list
The broadcast of this information is ensured using the "System Information 2quater" message
Since 3G technology based on FDD or TDD are very closed from a BSS point of view, in V18
a new O&M parameter is available in order to select the 3G technology (FDD or TDD which
are of course exclusive) and configure up to 4 UTRAN ARFCN (TDD or FDD) with appropriate
intersystem cell reselection control parameters. Then the BSC is able to build the SI 2quater
message accordingly.
4.4.1 UE ALGORITHM IN GSM CIRCUIT MODE
Instead of the C2 criterion used in GSM only network, the multimode cell reselection uses a
criteria based on RLA_C (Received Level Averages for Circuit services), which is an
unweighted average of the received signal levels measured in dBm.
The UE starts measuring 3G cells when RLA_C in serving cell is below or above Qsearch_I(depending on the value of Qsearch_I), the MS starts measuring 3G cells (FDD or TDD).
Main reason is to save mobile battery.
UTRAN/FDD NEIGHBORING CELL RESELECTION
The UTRAN/FDD neighbouring cell n is reselected by the UE if the 2 following conditions are
met for a period of 5s:
1. (CPICH_RSCP(n) > RLA_Cserving + FDD_Qoffset)
2. (CPICH Ec/No)(n) ≥ FDD_Qmin – FDD_Qmin_Offset
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PROCESS IN THE BSS
The intersystem reselection requires new information to be broadcast on the BCCH
via "System Information 2quater" message:
• new intersystem cell reselection control parameters (as described above)
• neighboring 3G cell list
The broadcast of this new information is ensured using the "System Information 2quater"
message.
When the information is updated (following a change at the OMC-R), the CHANGE MARK bit
is set to a new value.
The System Information 2quater is scheduled either on Normal or Extended BCCH (seechapter SI2Quater & SI13 on Extended or Normal BCCH):
• If sent on Normal BCCH:
it shall be sent when TC = 5 if neither of 2bis and 2ter are used
otherwise it shall be sent at least once within any of 4 consecutive
occurrences of TC = 4
• If sent on BCCH Ext, it is sent at least once within any of 4 consecutive
occurrences of TC = 5
As a consequence, System Information 3 message has been updated in order to indicate to
the mobile:
• whether or not SI2quater is broadcast
• if broadcast is done on Normal or Extended BCCH
4.4.2 3G NEIGHBOURING CELL INFORMATION IN SI2QUATER
The GSM standard offers different possibilities to broadcast 3G neighbouring cell information
using SI2quater:
• 1) The BSS broadcast FDD_ARFCN or TDD_ARFCN and primary scrambling
code for each of the UMTS FDD neighbouring cells.
• 2) for each ARFCN, a list of scrambling codes
In this version, neighboring cell scrambling codes are not broadcast, and FDD / TDD
technologies are exclusive (either TDD or FDD ARFCN are broadcast).
Therefore, 3G neighboring cells will be described by up to 4 FDD or TDD AFRCN following 3G
technology selected.
This limitation of 4 ARFCN (TDD or FDD) is due to the fact that the System Information
2quater message segmentation is not supported in this version by the BSS.
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As it will take "some" additional time with that solution (the mobile have to decode the UTRAN
FDD neighbouring cells scrambling codes) 2 additional informations are provided and used by
the network and the mobile when the mobile reports measurement in connected mode:
• a one bit 3G-BA_IND field used to correlate the measurements with a
neighbouring cell list
• a Absolute_Index_Start_EMR used for building the neighbouring cell list in the
mobile. The value of this parameter is dynamic, and depends on the number
of 2G neighbouring cells (this allows shorter Meas. Report messages from the
UE).
4.4.3 CONTROL INFORMATION IN SI2QUATER
The following Control information is broadcast by SI2quater message :
• FDD_Qoffset or TDD_Qoffset (3GReselectionOffset)
• FDD_Qmin (FDD only) (3GAccessMinLevel)
• Qsearch_I applicable for FDD and TDD (3GSearchLevel)
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4.5. LEGACY MEASUREMENT REPORTING
4.5.1 PRINCIPLE
Legacy measurement reporting consists in a mobile in dedicated mode - on a TCH or an
SDCCH - sending downlink signal measurements to the network, at regular intervals.
The BSS then uses these measurements in the uplink power control and handover
procedures.
4.5.2 NEIGHBOUR CELL MONITORING
DOWNLINK SIGNAL STRENGTH MEASUREMENTS
In this entire section, the mobile is assumed to be in dedicated mode.
While in dedicated mode, the mobile performs signal strength monitoring on all declared
neighbouring BCCH carriers. Signal strength measurements are done in every TDMA frame
on at least one of the BCCH carriers indicated in the BCCH allocation (BA), one after another.
As an exception, a dual-mode MS may omit GSM measurements during up to 9 TDMA frames
per SACCH multiframe and use these periods for measurements on UMTS.
Furthermore, an MS on SDCCH is allowed to schedule the measurements freely within the
multiframe as long as the total number of measurement samples is maintained and the
samples on each carrier are evenly spaced.
BSIC DECODING
It is essential for the MS to identify precisely which surrounding BTS is being measured in
order to ensure reliable handover. Because of frequency re-use with small cluster sizes, the
BCCH carrier frequency may not be sufficient to uniquely identify a neighbouring cell, i.e. the
cell in which the MS is situated may have more than one surrounding cell using the same
BCCH frequency. Thus it is necessary for the MS to synchronize to and identify the base
station identification code (BSIC). The 6-bit BSIC shall be transmitted by the network on the
SCH channel of each cell.
The MS shall use at least 4 spare frames per SACCH block period for the purpose of decoding
the BSICs (e.g. in the case of TCH, the four idle frames per SACCH block period). These
frames are termed "search" frames.
The MS shall attempt to demodulate the SCH on the BCCH carrier of as many neighbouring
cells as possible, and decode the BSIC as often as possible, and as a minimum at least once
every 10 seconds.
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4.5.3 SERVING CELL MONITORING
DOWNLINK SIGNAL STRENGTH MEASUREMENTS
For each channel, the measured downlink RXLEV shall be the average of the received
downlink signal level measurement samples in dBm taken on the TCH or SDCCH channel
within the reporting period of length one SACCH multiframe.
Signal strength measurement samples shall be taken on all bursts of the physical channel that
carries the TCH or the SDCCH, including those of the SACCH.
DOWNLINK SIGNAL QUALITY MEASUREMENTS
The received downlink signal quality shall be measured by the mobile in a manner that can be
related to the average BER before channel decoding, assessed over all received bursts in themultiframe, except bursts carrying a portion of a SACCH frame.
4.5.4 REPORTING PERIOD
A measurement report contains values averaged over samples collected over 104 TDMA
frames for a TCH (480 ms = duration of 4 TCH multiframes) and 102 TDMA frames for an
SDCCH (471 ms = duration of 2 SDCCH multiframes).
The mobile sends 1 measurement report every 480 ms for a TCH, and every 471 ms for an
SDCCH. Measurements performed during that measurement period are reported on the next
SACCH block occurrence.
The transmission of a single measurement report message is done on four consecutive bursts
of the SACCH channel :
• For a TCH, there is one SACCH burst available every 120 ms.
• For an SDCCH, the 4 SACCH bursts occur in 4 TDMA frames in immediate
succession, but these 4 TDMAs in succession occur once every 471 ms.
Note : The BTS also performs uplink signal strength and uplink signal quality measurements .However, the BTS delays the processing of these uplink measurements by 480 ms or 471 ms
to ensure that they are synchronised with the downlink measurements from the mobile (i.e.
they relate to the same reporting period as the downlink measurements, which the BTS
receives with a 480 ms or 471 ms delay).
4.5.5 NEIGHBOUR CELL LISTS
Reporting with the MEASUREMENT REPORT message is usually performed on the BCCH
allocation list (i.e. GSM cells only), but could also use cells from the 3G neighbour list in the
case of 2G/3G mobiles.
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The BCCH Allocation list is provided by the network to the mobile through SI5 messages on
SACCH. The number of neighbour cell BCCH carriers in the BCCH allocation cannot exceed
32.
The UTRAN neighbour list is provided to the 2G/3G mobile through Measurement Information
messages sent on SACCH.
4.5.6 MEASUREMENT REPORT CONTENT
2G MEASUREMENT REPORT
Each measurement report contains the following data :• (neighbour cells) RXLEV_NCELL : RXLEV computed from samples taken on the
BCCH frequency of the 6 cells with the highest signal level. For each of the 6 cells, the
number of samples that is used to compute the RXLEV of that cell depends on the
total number of neighbours to be monitored (this number is the size of the BCCH
Allocation list).
• (serving cell) RXLEV_FULL : RXLEV computed from 100 (resp. 12) measurement
samples of the mobile’s TCH (resp. SDCCH). The samples are measured in each of
the 100 (resp. 12) TDMA frames that transmit either the TCH burst (resp. SDCCH) or
the SACCH burst, over the measurement period.
• (serving cell) RXQUAL_FULL : RXQUAL computed from 100 (resp. 12) measurement
samples of the mobile’s TCH (resp. SDCCH)
• (serving cell) RXLEV_SUB : For a TCH, RXLEV computed from 12 samples taken
from the 4 SACCH bursts and – in case of speech only - the 8 Silence Descriptor
(SID) frames. Not applicable for SDCCH because DTX is not allowed on SDCCH : in
that case, RXLEV_SUB = RXLEV_FULL.
• (serving cell) RXQUAL_SUB : For a TCH, RXQUAL computed from the same 12
samples as RXLEV_SUB. Not applicable for SDCCH and in that case, RXQUAL_SUB
= RXQUAL_FULL.
The mobile reports every 480 ms for a TCH and every 471 ms for an SDCCH.
3G MEASUREMENT REPORT
The measurement report is the same as for 2G, except for the RXLEV_NCELL of neighbour
UTRAN cells. The RXLEV_NCELL neighbour cell measurement is replaced by the appropriate
measurement for UTRAN. The measurement quantity reported by mobiles could be either
“CPICH RSCP” or “CPICH Ec/N0”. In Nortel implementation, mobiles are told by the network
to report only RSCP measurements on CPICH channels. However, the mobile selects the
UTRAN cells to report, based on internal measurements of the CPICH Ec/N0.
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4.5.7 MULTIBAND REPORTING
For a multi band MS the number of cells, for each frequency band supported, which must be
included in the measurement report is indicated by the value of the parameter
MULTIBAND_REPORTING, broadcast by the network in SI2ter on BCCH and SI5ter onSACCH.
The value of this parameter is set by the BSS parameter multiBandReporting (class 3, bts
object) :
• Value 0 : reporting of the six strongest cells, irrespective of the band used. No band is
favoured.
• Value 1, 2 or 3 : reporting of the 1, 2 or 3 strongest neighbour cell(s) in the non-
serving band. The remaining positions in the measurement report shall be used for
reporting of cells in the band of the serving cell. If there are still remaining positions,
these shall be used to report the next strongest identified cells in the other bandsirrespective of the band used.
4.5.8 UTRAN CELL REPORTING USING LEGACY MEASUREMENTREPORTS (V17)
If GSM to UMTS Handover feature is enabled (see §4.8.24), the network may request the
2G/3G mobiles to report on UTRAN cells as well as on GSM cells, using either :
• Legacy measurement reports : this option is covered in this subsection.
• Enhanced measurement reports : this option is covered in §4.6
Note that 2G only mobiles never report UTRAN cells. UTRAN cells’ reporting only concerns
2G-3G mobiles and is performed by these mobiles using normal measurement reports only
when HO 2G-3G is enabled (parameter gsmToUMTSServiceHo not equal to
gsmtoUMTSDisabled) and EMR is disabled. In that case, the network informs the 2G/3G
mobiles of the type of measurement report to be used by sending a parameter called
REPORT_TYPE (3GPP name) / reportTypeMeasurement (Nortel BSS parameter name)
which can take only 2 values : “enhanced measurement report” or “normal measurement
report”. It is sent on SACCH inside a message called MEASUREMENT INFORMATION.
BSS PARAMETERS
The choice criteria of 2G and 3G cells that the 2G/3G mobile must include in the Measurement
Report in the list of the 6 cells are driven by 4 network parameters, the use of which is detailed
further on in this subsection :
• fDDMultiratReporting (v17, bts object)
• fDDreportingThreshold2 (v17, handoverControl object)
• qsearchC (v17, handoverControl object)
• multiBandReporting (v10, bts object)
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If the dedicated channel (TCH or SDCCH) uses the BCCH frequency, then qsearchC is
meaningful. However, in that case, the recommended Nortel value is 7 (always search for
UTRAN cells regardless of the downlink power level of the serving cell BCCH carrier).
Conclusion : with Nortel’s recommended value qsearchC = 7, the 2G/3G mobile is required to
always search for and measure UTRAN cells, regardless of the downlink power level of the
serving cell BCCH carrier
CELL CHOICE ALGORITHM
The MS fills the normal measurement report with measurements from 6 neighbour cells
chosen in the following order :
• Strongest valid UTRAN FDD cells :
o a valid UTRAN cell is an identified cell where the primary CPICH has been
received by the mobile when using the scrambling code provided for that
frequency in the neighbour cell list.
o to be eligible, a valid cell’s Ec/N0 must also be greater than
fDDReportingThreshold2 .
o these valid and eligible cells are ranked according to the CPICH RSCP value
and the strongest are included first. The number of such reported cells is
defined by the fDDMultiratReporting parameter.
• Strongest GSM cells (including GSM cells of unknown BSIC) in each of the non-
serving frequency bands in the neighbour list. The number of such reported cells isdefined by the multiBandreporting parameter.
• Strongest GSM cells (including unknown BSIC) in the frequency band of the serving
cell. There is no limitation on the number of such reported cells.
• Remaining strongest GSM cells in each of the non-serving frequency bands in the BA
list.
• Remaining strongest UTRAN FDD cells.
Comments:
• Unlike EMR (§4.6), this algorithm does not discriminate between GSM cells with
known BSIC and GSM cells with unknown BSIC.
• Unlike EMR (§4.6), the RxLev of serving band GSM cells are not required to exceed a
reporting threshold.
• Unlike EMR (§4.6), the RSCP of UTRAN cells is not required to exceed a reporting
threshold.
• Unlike EMR (§4.6), UTRAN cells are included before GSM cells.
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ENGINEERING RECOMMENDATION
Unlike EMR, a normal measurement report contains 6 cells. Therefore, it is necessary to
exercise caution when setting the parameters fDDMultiRatReporting and multiBandReporting.
These parameters define the number of UTRAN cells and non-serving band GSM cells,repsectively, that must be included by the mobile in the list of strongest cells in the
measurement report. Therefore it leaves (6 - fDDMultiRatReporting - multiBandReporting)
spaces for the serving band cells.
Therefore, if EMR is disabled, it is recommended not to exceed fDDMultiRatReporting = 2 and
multiBandReporting = 2.
4.5.9 NOTE ON POWERCONTROLINDICATOR PARAMETER
powerControlIndicator is a BSS parameter that sets the value of the flag "PWRC". "PWRC" is
a field that is broadcast on BCCH channel inside SYSTEM INFORMATION n°3 messages.
PWRC = 1 is equivalent to powerControlIndicator = "do not include BCCH measurements"
PWRC = 0 is equivalent to powerControlIndicator = "include BCCH measurements"
The mobiles are required to interpret this flag as follows :
• if frequency hopping is not used : MS ignores the PWRC flag
• if frequency hopping is used and the BCCH frequency is not part of the Mobile
Allocation frequency list : MS ignores the PWRC flag
• if frequency hopping is used and the BCCH frequency is part of the Mobile Allocation
frequency list :
o if PWRC = 1 : in the RXLEV averaging process, the MS shall discard the
samples measured on the TCH channel's Downlink bursts that have been
transmitted by the BTS on the BCCH frequency
o if PWRC = 0 : in the RXLEV averaging process, the MS shall use the samples
measured on the TCH channel's Downlink bursts that have been transmitted
by the BTS on the BCCH frequency
In practice, in our networks :
• In case of Synthesized Frequency Hopping, there is one TRX which is dedicated to
transmitting the BCCH frequency all 8 Timeslots of the TDMA. If the BCCH frequency
was part of the hopping list of a TCH (on another TRX, of course), then there would be
systematic collisions. Therefore, in case of SFH, BCCH frequency cannot be part of
the hopping frequency list. Therefore, in case of SFH, the setting of
powerControlIndicator is irrelevant.
• In case of Baseband Frequency Hopping (BB FH is the only hopping scheme possible
with Cavity coupling), it is theoretically possible - but not recommended by Nortel - to
include the BCCH frequency in the hopping frequency list. If, in spite of ourrecommendation, the BCCH frequency is part of the hopping frequency, then :
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o if downlink power control is activated, then the TCH channel's Downlink bursts
transmitted on the BCCH frequency should not be used in the Rxlev
averaging process because, unlike the samples from other frequencies, they
are transmitted at full power : so, PWRC must be = 1 and
powerControlIndicator = "do not include BCCH measurements".
o if downlink power control is not activated, then the TCH channel's Downlink
bursts transmitted on the BCCH frequency may be used in the Rxlev
averaging process : PWRC = 0 and powerControlIndicator = "include BCCH
measurements"
4.5.10 NOTE ON RXLEV UPLINK/DOWNLINK DIFFERENCE
On the mobile side, every downlink sample is made up of measurements performed on
several bursts in dBm. On the BTS side, uplink measurements are performed in Watts. So, the
uplink RxLEv average is first computed in Watts before it is converted into dBm.
These two different ways of calculating the RxLev average yield results that are artificially
approximately 2,5 dB higher for the uplink than for the downlink (see chapter Difference
Between Uplink and Downlink Levels.
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4.6. ENHANCED MEASUREMENT REPORTING (EMR)
4.6.1 PRINCIPLE
Compared to Legacy Measurement Reporting, Enhanced Measurement Reporting allows the
mobile to:
• Report more GSM neighbouring cells and, if required, 3G cells
• Enhance the information reported about the quality of the signal received by the
mobile (MEAN_BEP and CV_BEP, downlink FER).
Enhanced Measurement Reporting by the mobile may be used in the context of 2G-3G
handover but is not a mandatory prerequisite.
4.6.2 REPORTING PERIOD
Same as Measurement Reporting.
4.6.3 ENHANCED MEASUREMENT REPORT CONTENT
The Enhanced Measurement Report contains the following information :
• (GSM neighbour cells) RXLEV computed from samples taken on the BCCH frequency
of GSM neighbour cells with the highest signal level. The number of neighbour cells to
be reported belonging to the serving GSM band on the one hand, and to the non-
serving GSM band on the other hand, depends on the values of parameters sent by
the network multibandReporting (v10 parameter), servingBandReporting (v17.0
parameter), and servingBandReportingOffset(v17.0 parameter)
• (3G neighbour cells) The reported value for 3G neighbour cells is the CPICH RSCP.
The CPICH Ec/N0 is not reported in Nortel’s current implementation. The number of
neighbour cells to be reported belonging to the 3G technology depends on the values
of parameters sent by the network fDDMultiratReporting (v17.0 parameter),
fDDreportingThreshold (v17.0 parameter) and fDDreportingThreshold2 (v17.0
parameter)
• (GSM serving cell) : The reported values for the GSM serving cell are :
o RXLEV_VAL : The average over the reporting period of RXLEV measured on
bursts whose associated FACCH, SID, or traffic frame has been the last time
slots of each fully received and correctly decoded data block and on all
SACCH frames. For speech traffic channels, blocks that have not been
erased, shall be considered as correctly decoded. For non-transparent data,
blocks are considered as correctly decoded according the CRC received. For
transparent data, all blocks are considered as correctly decoded.
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o MEAN_BEP : The average over the reporting period of the Mean Bit Error
Probability, computed from each fully received and correctly decoded data
block and from all SACCH frames.
o CV_BEP : The average over the reporting period of the Coefficient of
Variation of the Mean Bit Error Probability, computed from each fully received
and correctly decoded data block.
o RXQUAL_FULL : RXQUAL computed over the reporting period from 100
measurement samples of the mobile’s dedicated traffic channel TCH
o NBR_RCVD_BLOCKS : the number of correctly decoded TCH blocks that
were completed during the measurement report period.
4.6.4 NEIGHBOUR CELL LISTS
EMR reporting is performed on the Neighbour Cell List.
The Neighbour Cell List is the concatenation of 2 lists
• The GSM neighbour cell list
• The 3G neighbour cell list (if any)
GSM NEIGHBOUR CELL LIST
The GSM neighbour cell list is the combination of the BCCH Allocation list received in
SI5/SI5bis/SI5ter with the BSIC list received in one or more instance of the MEASUREMENT
INFORMATION message.
3G NEIGHBOUR CELL LIST
This applies only to a 2G-3G mobile. One or more instances of the Measurement Information
message may provide UTRAN Neighbour Cell Description information. This is used to build
the 3G Neighbour Cell list.
MAXIMUM LIST SIZE
In Nortel’s v17 implementation, the maximum number of cells of the lists in the Measurement
Information message is :
• maximum 32 UMTS cells
• If the 3G list is void, maximum 32 GSM cells
• If the 3G list is non-void, maximum 31 GSM cells
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4.6.5 ORDER OF REPORTING PRIORITY OF NEIGHBOUR CELLS
The Mobile includes measurement results of neighbour cells using the following priority order:
• Highest priority : the number of strongest GSM cells with known and valid BSIC in the
frequency band of the serving cell, according to the value of servingBandReporting;
• 2nd highest priority : the number of strongest GSM cells with known and valid BSIC in
each of the frequency bands in the BCCH Allocation list, excluding the frequency band
of the serving cell, according to the value of multiBandReporting;
• 3rd highest priority : the number of best valid UTRAN cells with a reported value equal
or greater than fDDReportingThreshold in the 3G neighbour cell list, according to the
value of fDDmultiRatReporting. Additionally the CPICH Ec/No shall be equal or
greater than fDDReportingThreshold2 . A valid cell is an identified cell where the
primary CPICH has been received when using the scrambling code provided for that
frequency in the neighbour cell list.• 4th highest priority : the remaining GSM cells with known and valid BSIC or, if allowed
by the flag INVALID_BSIC_REPORTING, with known and allowed NCC part of the
BSIC in any frequency band.
• Last priority : remaining valid UTRAN cells
For each of the priority levels above, the mobile shall apply the following rules :
• if the number of valid cells is less than indicated, the unused positions in the report
shall be left for cells of lower priority;
• if there is not enough space in the report for all valid cells of a given priority, cells shall
be ranked according to :
o for GSM cells belonging to the serving band : RxLev +
servingBandReportingOffset . Note that this ranking criterion shall not affect
the value that is effectively included in the report, which remains RxLev.
o for GSM cells belonging to the non-serving band : RxLev. (reporting offset =
0)
o for UTRAN cells : RSCP. (reporting offset = 0)
4.6.6 MEASUREMENT INFORMATION MESSAGE
PURPOSE OF MI MESSAGE
The activation of EMR in the network requires the network to inform the relevant mobiles that
EMR reports are expected from them.
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To do this, the network sends a new information message to the mobiles, called Measurement
Information. The Measurement Information message is regularly sent by the network to the
mobiles in dedicated mode on the SACCH, in addition to System information messages 5,
5bis, 5ter, and 6.
The following mobiles receive MI messages :
• 2G-3G mobiles that are at least Release 99
• 2G-only mobiles that are at least Release 4
CONTENT
In the version of EMR reporting currently implemented, the MI message contains essentiallythe following information :
• EMR activation flag. The value of this flag is set by the reportTypeMeasurement
parameter.
• Information enabling the mobile to derive the full list of GSM neighbour cells, i.e.
(BCCH frequency, BSIC) pairs, that may be reported in EMR reports.
• INVALID_BSIC_REPORTING : 0 for disabled, 1 for enabled. When set to 1, report on
cells with invalid BSIC and allowed NCC part of BSIC is allowed. The value 1 is
mandatory if feature “switch interference matrix” is activated.
• Number of GSM neighbour cells of the serving band that the Mobile shall include inthe list of strongest cells in the EMR report (up to 3). The value of this number is set
by the servingBandReporting parameter.
• Threshold power level above which serving band cells may be reported among the
servingBandReporting number of reported cells. In v17 implementation, this threshold
is -110 dBm, meaning that all serving band cells may be reported regardless of their
power level.
• (applicable to multi-band mobiles only) Number of GSM neighbour cells of the other
band that the Mobile shall include in the list of strongest cells in the EMR report (up to
3). The value of this number is set by the multiBandReporting parameter (v10
parameter).
• (applicable to multi-band mobiles only) Offset to apply to the reported value when
prioritizing the cells for reporting for GSM serving frequency band. The value of this
offset is set by the servingBandReportingOffset parameter
• (applicable to 2G-3G mobiles only) UTRAN neighbour cell list : list of FDD (ARFCN,
scrambling code, diversity) triplets, identifying each 3G neighbour cell. The values of
these triplets are set by the following AdjacentCellUTRAN object parameters :
o fDDARFCN,
o scramblingCode,
o diversityUTRAN
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• (applicable to 2G-3G mobiles only) UTRAN cells’ measurement parameters :
o Number of FDD cells to be reported in the list of strongest cells in the EMR
message. This number is set by the O&M network parameter
fDDMultiRatReporting.
o CPICH RSCP level above which the mobile will apply a higher priority to
UTRAN cells in the EMR message. The value of this level is set by the O&M
network parameter fDDReportingThreshold.
o CPICH Ec/N0 level above which the mobile will report UTRAN cells in the
EMR message. The value of this level is set by the O&M network parameter
fDDReportingThreshold2 .
o Serving cell BCCH frequency power threshold above which, or below which,
the mobile may search for UTRAN cells. The value of this level is set by the
O&M network parameter qsearchC.
o Type of reporting quantity (value always equal to RSCP in v17
implementation)
RELATION WITH 2G-3G HANDOVER
Note that 2 different versions of the Measurement Information message may be sent by the
network depending on the mobile’s radio access capability (2G or 2G-3G) :
• If EMR reporting is activated but not 2G-3G handover (i.e. the gsmToUMTSServiceHo
parameter is set to "gsmToUMTSDisabled") :
o the BSC only sends 2G Measurement Information to the BTS. However, the
BSC does send the whole L1M configuration to the BTS. The BTS is therefroe
aware of the UTRAN neighbouring cells.
o The BTS only sends 2G Measurement Information messages to 2G-3G
Release 99 mobiles and Release 4 2G mobiles. Thus UMTS cells are hidden
from the mobiles so that mobiles do not report 3G measurement results in
vain, which could adversely affect their performance.
• If both EMR reporting and 2G-3G handover are activated (i.e. the
gsmToUMTSServiceHo parameter is not set to "gsmToUMTSDisabled") :
o the BSC sends to the BTS both the 2G Measurement Information and the
2G/3G Measurement Information messages.
o The BTS sends the 2G/3G Measurement Information to 2G-3G Release 99
mobiles and the 2G Measurement Information to the Release 4 2G mobiles.
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4.6.7 MI/SACCH SCHEDULING
The scheduling of Mesaurement Information and System Information messages in the SACCH
channel is :
SI 5
SI5bis
SI 5ter
SI 6
MI
SI 5
... etc.
4.6.8 MAIN DIFFERENCES BETWEEN NORMAL AND ENHANCEDMEASUREMENT REPORTING
This section attempts at summarising the main differences between normal measurement
reporting (§4.5) and enhanced measurement reporting (§4.6).
MR EMR
A normal measurement report contains up to 6 neighbour cells An enhanced measurement report contains up to 32neighbour cells
No reporting offset is applied to rank cells. Competing cells areranked based only on the strongest RxLev (GSM) and RSCP(UTRAN) values
servingBandReportingOffset is applied to the RxLev of servingband GSM cells for ranking purposes. No offset is applied fornon-serving band GSM cells and UTRAN cells
One (1) reporting threshold is used to define eligible UTRANcells : fDDReportingThreshold2 for Ec/No (non-reportedquantity). No threshold for RSCP.
2 reporting thresholds are used to define eligible UTRAN cells: fDDReportingThreshold for RSCP (reported quantity) andfDDReportingThreshold2 for Ec/No (non-reported quantity)
A parameter (fDDMultiRatReporting) defines the number ofUTRAN cells to be included in the report as a matter of priority
A parameter (fDDMultiRatReporting) defines the number ofUTRAN cells to be included in the report as a matter of priority
A parameter (MultiBandReporting) defines the number of non-
serving band GSM cells to be included in the report as amatter of priority
A parameter (MultiBandReporting) defines the num ber of non-
serving band GSM cells to be included in the report as amatter of priority
There is no required minimum number of serving band GSMcells in the report
A parameter (servingBandReporting) defines the number ofserving band GSM cells to be included in the report as amatter of priority
GSM cells with known BSIC and GSM cells with unknownBSIC are treated the same
GSM cells with known and valid BSIC have higher priority
UTRAN cells have top priority in the report Sering and GSM cells have top priority in the report
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4.6.9 NEW BSS PARAMETERS
The following parameters are created in v17.0 and are needed to support Enhanced
Measurement Reporting :
Parameter name Definition Equivalent in GSM specification
fDDMultiratReporting Number of FDD UTRAN cells to be reported in the listof strongest cells in the EMR message
FDD_MULTIRAT_REPORTING
fDDReportingThreshold defines the CPICH RSCP level above which the MS willapply a higher priority to UTRAN cells in the enhancedmeasurement report message
FDD_REPORTINGTHRESHOLD
fDDReportingThreshold2 defines the CPICH Ec/N0 level above which the MS willreport UTRAN cells in the enhanced measurement
report message
FDD_REPORTINGTHRESHOLD2
qsearchC
search for UTRAN cells if signal level on BCCH ofserving cell :
is below threshold (0-7):
-98, -94, … , -74 dBm, ∞ (always)
or is above threshold (8-15):
-78, -74, … , -54 dBm, ∞ (never)
If the serving BCCH frequency is not part of theBA(SACCH) list, the dedicated channel is not on theBCCH carrier, and qsearchC is not equal to 15, the MSshall ignore the qsearchC parameter value and alwayssearch for UTRAN cells. If qsearchC is equal to 15, theMS shall never search for cells on 3G.
Qsearch_C
reportTypeMeasurement type of measurement report to be reported on this cell :enhanced measurement report or legacy measurementreport
REPORT_TYPE
servingBandReporting defines the number of cells from the GSM servingfrequency band that shall be included in the list ofstrongest cells in the measurement report.
SERVING_BAND_REPORTING
servingBandReportingOffset
If there is not enough space in the report for all validcells, the cells shall be reported that have the highestsum of the reported value (RXLEV) and the parameterservingBandReportingOffset(XXX_REPORTING_OFFSET) for the serving GSMband. Note that this parameter shall not affect the valueitself of the reported measurement.
XXX_REPORTING_OFFSET(XXX=900,1800,400,850,1900)
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4.6.10 IMPACT OF EMR ON INTERFERENCE MATRIX
IMPROVED ACCURACY
There are more GSM neighbours reported with EMR than with legacy measurement reporting
:
• With EMR, up to 32 GSM neighbours if no UTRAN cells are defined in the Neighbour
Cell List
• With standard MR, 6 neighbour cells.
This means that the statistical processing induces less systematic bias error in the case of
EMR.
GREATER NUMBER OF CYCLES
If no 3G cells are declared as neigbours, the number of cycles depends only on the number of
declared real neighbours and the number of fake neighbours, so it is not impacted by EMR.
However, if 3G cells are declared as neighbours, the maximum number of GSM neighbours
(real + fake) is 31 instead of 32. Therefore, more cycles may be required if 3G cells are
present in the Neighbouring Cell List.
CHANGE OF TRAFFIC DISTRIBUTION
If, during the Interference Matrix campaign in a dual band network, the reporting of serving
band neighbours is deliberately favoured by using the servingBandReportingOffset , then, as a
side-effect, the traffic distribution may be modified. This undesirable side-effect may in turn
modify the results of the IM measurements, whjich therefore may no longer reflect the real
situation in the field once the IM has ceased.
Therefore it is recommended to ensure that the chosen value of servingBandReportingOffset
does not cause unacceptable changes in the traffic distribution.
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4.6.11 IMPACT OF EMR ON RADIO MEASUREMENT DISTRIBUTION
(RMD)Thanks to enhanced measurement reports, the downlink FER indicator is available to the
network. Specific distributions are added for the different codec types.
Also, a distribution of estimated downlink voice quality is added. This indicator is based on the
same principle as MOS for uplink, but is a marginally less accurate because the mobile does
not provide the distribution of codecs used during the measurement period.
The post processing tool WQA is modified accordingly.
DOWNLINK FRAME ERASURE RATE
In the EMR message, the mobile provides the number of received traffic frames :
NBR_RCVD_BLOCKS. The BTS knows the number of times each codec have been used
during the measurement period so it is now possible to get a rough estimate of the probable
number of frames, per codec, that have not been decoded by the mobile and a rough
estimate, per codec, of the probable downlink FEP (Frame Erasure Probability). Note that
each sum of estimated number of bad frames is rounded to the nearest integer value at the
end of the connection.
Thanks to RMD feature, downlink FER distributions at the OMC-R level are made available
for the following types of circuit calls:
• EFR and FR speech calls,
• AMR FR speech calls,
• AMR HR speech calls.
DOWNLINK VOICE QUALITY INDICATOR
With EMR, it is possible to estimate the downlink voice quality (DVQI) in the same way as
TEPMOS estimates the uplink voice quality.
Distinction is done for the different codec types (EFR (and FR), AMR FR and AMR HR).
As the downlink FER per codec is an estimated one, the downlink voice quality indicator will
be less precise than TEPMOS, but the formula used to calculate DVQI is similar to the
TEPMOS one.
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4.7. UPLINK MEASUREMENT PROCESSING
4.7.1 PRINCIPLE
Each sample on the uplink side used by the Layer 1 Management in the average computation
is composed of measurements performed in Watts on several bursts. So the uplink samples
are first computed in Watts before being translated into dBm.
The general idea is to perform arithmetic averages. These averages are stored, and each time
a decision has to be taken, an other average (weighted-average) is computed. This weighted-
average is based on a defined number (Hreqt) of arithmetic averages, which are weighted in
order to favor the latest results.
In the new version of the Layer 1 Management (L1mV2), the process of averaging is based on
fully sliding windows.
Examples for Hreqave = 8, Hreqt = 1, run xx = 4
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Example: If r3 is missing, then r3 = r2 X weighting factor.
RULE 3
If no measurement value is available, the missing measurement is replaced by a default value.
Example: If r1 is missing, then r1 = default value.
RULE 4:
In the following, the substitution of a missing value is only done when 6 neighbouring cells are
reported during the considered period.
From L1mV2 missing measurements for neighboring cells are replaced as follows; for both
cases, inputs are:
• Ncell1 no longer belongs to the list of 6 preferred cells at T+1 period,
• T, T+1 correspond to measurement periods.
First case:
IF RxLevNCell1(T) ≤ min(RxLevNCell(T+1) of the 6 reported cells)
THEN RxLevNCell1(T+1) = RxLevNCell1(T)
r1 r2 r3 r4 r5 r6 r7 r8
m1
m2
m3
m4
m5
time
r1 r2 r3 r4 r5 r6 r7 r8
m1
m2
m3
m4
m5
time
r1 r2 r3 r4 r5 r6 r7 r8
m1
m2
m3
m4
m5
time
r1 r2 r3 r4 r5 r6 r7 r8
m1
m2
m3
m4
m5
time
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Second case:
IF RxLevNCell1(T) > min(RxLevNCell(T+1) of the 6 reported cells)
THEN RxLevNCell1(T+1) = min(RxLevNCell(T+1)) - missOffsetdB
missOffset has a fixed value of 3 dB.
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4.8. DIRECT TCH ALLOCATION AND HANDOVER ALGORITHMS
Since V14, a new version of the Layer 1 Management (L1mV2) is applicable (see chapter
Measurement Processing)
CAUTION!
It is understood in all the following formulas that RxLev_XX is computed with L1mV2.
4.8.1 GENERAL FORMULAS
PBGT
The general PBGT formula is computed in the band0 because HO_MARGIN is always specific
to the band0:
PBGT(n) = Min [msTxPwrCapability(Band0), msTxPwrMax]
- Min [msTxPwrCapabilityCell(n), msTxPwrMaxCell(n)]
+ (RxLevNCell(n)ave - RxLevDLave))
• msTxPwrCapability: maximum transmission power capability of the MS according
to the BCCH frequency (Band0) and its power class (§ 4.2.2).
• msTxPwrMax: maximum transmission power level the MS is allowed to use on a
traffic channel in the current cell.• msTxPwrMaxCapabilityCell(n): maximum transmission power capability of the MS
(in the BCCH frequency band) of an adjacent cell (n), according to:
o the BCCH frequency band of the adjacent cell (n)
o the power class of the mobile in this band (§ 4.2.2)
• msTxPwrMaxCell(n): maximum transmission power level the MS is allowed to use
on a traffic channel of neighbour cell n (or the band0 of the neighbour dual band cell n)
• RxLevNCell(n) ave: averaged downlink signal strength of the neighbour cell n
• RxLevDLave: averaged downlink signal strength of the serving cell
However, if the MS is in band1 the PBGT formula is changed.
Indeed, RxLevNCell(n)ave should be replaced by RxLevNCell(n)ave + biZonePowerOffset inorder to simulate what the field strength would be like in band0.
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EXP1
The expression named EXP1 used for defining eligible cells:
EXP1(n) = RxLevNCell(n) ave - [ rxLevMinCell(n) + Max(0, msTxPwrMaxCell(n) -
msTxPwrCapability(n) ) ]
It is also used in the following process:
EXP1Capture(n) = RxLevNCell(n) ave - rxLevMinCell(n)
EXP1DirectedRetry(n) = RxLevNCell(n) ave - [directedRetry(n) + Max(0,
msTxPwrMaxCell(n) - msTxPwrCapability(n)]
EXP1Forced HO (n) = RxLevNCell(n) ave - [forced handover algo(n) + Max(0,
msTxPwrMaxCell(n) - msTxPwrCapability(n)]
• RxLevNCell(n) ave: averaged downlink signal strength of the neighbour cell n
• rxLevMinCell(n): minimum RXLEV value required for a MS to handover towards
cell n
• msTxPwrMaxCell(n): maximum transmission power level the MS is allowed to use
on a traffic channel of neighbour cell n / in the band0 of the neighbour dual band cell
• msTxPwrCapability(n): maximum transmission power capability of the MS
according to the power class of the mobile and the BCCH frequency (the band0) of the
neighbour cell n
• directedRetry(n): minimum signal strength level received by the MS to process
directed retry handovers in BTS mode
• forced handover algo(n): minimum signal strength level received by the mobiles to
be granted access to a neighbor cell in case of forced handover.
Note: If HO decision is made toward the inner zone of a multizone cell, then related
EXP1XX(n) is computed with biZonePowerOffset(n) .
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EXP2
The expression named EXP2 used for defining suitable cells:
EXP2PBGT(n) = Pbgt(n) - AdaptedHoMargin(n)
EXP2Traffic(n) = Pbgt(n) - [hoMargin(n) - hoMarginTrafficOffset(n)]
EXP2Quality(n) = Pbgt(n) - hoMarginRxQual(n)
EXP2Strength(n) = Pbgt(n) - hoMarginRxLev(n)
EXP2Distance(n) = Pbgt(n) - hoMarginDist(n)
EXP2AMR(n) = Pbgt(n) - hoMarginAMR(n)
EXP2bis(n) = rxLevDLPBGT(n) - RxLevDL ave
• AdaptedHoMargin(n): margin computed when AHA feature is enabled. It takes into
account neighDisfavorOffset and servingfactorOffset parameters (see chapter
Automatic handover adaptation)
• hoMargin(n): margin to be used for power budget HO
• hoMarginTrafficOffset(n) : offset to be applied to hoMargin(n) for traffic HO decision
(when current cell is overloaded)
• hoMarginRxQual(n): margin to be used for quality HO
• hoMarginRxLev(n): margin to be used for signal strength HO
• hoMarginDist(n): margin to be used for distance HO
• hoMarginAMR(n): margin to be used for quality intercell HO defined for AMR TCH
channels
• rxLevDLPBGT(n): maximum downlink RxLev received from serving cell to allow a
power budget or traffic HO towards this NCell
Note: If HO decision is made in the inner zone of a multizone cell, then related EXP2XX(n) is
computed with (hoMarginXX(n) + biZonePowerOffset).
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4.8.2 DIRECT TCH ALLOCATION
This chapter describes the Direct TCH Allocation feature which applies to the dualband cell,
the concentric cell and the dualcoupling cell features. Direct TCH Allocation has beenenhanced in v17.0.
PRINCIPLE
The principle of “Direct TCH Allocation” is manifold. It consists in the following aspects :
• At call setup, to allocate a FR TCH directly into the inner-zone of a multizone cell
• At call setup, to allocate an HR TCH directly into the outer-zone of a multizone cell
• At call setup, to allocate an HR TCH directly into the inner-zone of a multizone cell
• On intercell handover, to allocate a TCH directly into the inner-zone of the targetmultizone cell.
At call setup, while the mobile is still on SDCCH (SDCCH is always allocated in the large zone
of a multi-zone cell), the BSC asks the BTS if the call (FR or HR) may be directed to the
appropriate zone by sending the BTS an “Abis Connection state request” message. The
acknowledgement of this request by the BTS provides the BSC with the information allowing
the BSC to decide to perform the requested TCH allocation.
The BTS uses several criteria to decide which zone is eligible. These criteria have been
altered in v17.0 as explained in the next section.
V17.0 ENHANCEMENT PRINCIPLE
CALL SETUP
In initial phase of call establishment, the time spent on SDCCH is usually too short for the BTS
to compute a weighted average on downlink Rxlev measurement before the BST receives the
Abis connection state request from the BSC. Therefore, the allocation criteria for direct TCH
allocation use, by decreasing order of priority:
• a weighted average computed with RxLevHreqAve*RxLevHreqT latest measurements
(unlikely to happen on SDCCH).
• an arithmetic average computed with RxLevHreqAve latest measurements (unlikely to
happen on SDCCH)
• a short and fully reliable average (RxLevHreqAveBeg measurements) in the sense of
the Automatic handover Adaptation feature if this feature is enabled and if the MS is
fast enough or hopping on enough frequencies to filter the Raleigh fading.
• a short, not fully reliable average (from RxLevHreqAveBeg up to RxLevHreqAve-1
measurements) in all other cases.
In the last case, the v17 enhancement consists in the L1M compensating for the lower
reliability of the short average by adding the hoMarginBeg margin to the various allocationthresholds. For all other cases, there is no change in v17.0.
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Note : If hoMarginBeg parameter is set to 63, the Direct TCH allocation procedure only uses
normal averages.
INTERCELL HANDOVER
Some handover decisions (Early Power budget or Directed Retry) may be taken using less
than RxLevNcellHreqAve measurements on the neighbouring cell. So, the allocation
information for direct TCH allocation uses by decreasing order of priority:
• an arithmetic average computed with RxLevNcellHreqAve latest measurements.
• a short and fully reliable average (RxLevNcellHreqAveBeg measurements) in the
sense of the Automatic Handover Adaptation feature if this feature is enabled and if
the MS is going fast enough to filter the Raleigh fading
• a short not fully reliable average (from RxLevNcellHreqAveBeg up toRxLevNcellHreqAve -1 measurements) in all other cases.
In the last case, the L1M now compensates for the lower RxlevNcell average reliability by
adding the hoMarginBeg margin to the BizonePowerOffset(n) parameter in order to ensure the
same grade of service.
Note : If hoMarginBeg parameter is set to 63, inter-cell handover Direct TCH allocation
procedure only uses normal averages.
DIRECT FR TCH ALLOCATION IN INNER-ZONE, AT CALL SETUP
From V18, if using a not fully reliable short average, hoMarginBeg is added to the following
thresholds :
• DirectAllocIntFrRxlevUL
• DirectAllocIntFrRxLevDL
CONCENTRIC CELLS
The criteria for a successful direct TCH allocation in the inner-zone are:
RxLevDL > DirectAllocIntFrRxLevDL
And
RxLevUL>DirectAllocIntFrRxLevUL
and
MS_BS_Dist < concentAlgoExtMsRange (timing advance criterion)
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DUALBAND OR DUALCOUPLING CELLS
The timing advance criterion is disabled for a dualcoupling or dualband cell since the algorithmonly needs to check that the BS Tx power in the innerzone is sufficient to maintain the
communication.
For dualband cells, obviously, a test is also performed on the capability of the mobile to
support the band1.
The criterion for a successful direct TCH allocation in the inner-zone is :
RxLevDL > DirectAllocIntFrRxLevDL
And
RxLevUL>DirectAllocIntFrRxLevUL
DIRECT HR TCH ALLOCATION IN OUTER-ZONE, AT CALL SETUP
In v17, if using a not fully reliable short average, hoMarginBeg is added to the following
thresholds :
• amrDirectAllocRxLevDL
• amrDirectAllocRxLevUL
CONCENTRIC CELLS
The criteria for a successful direct HR TCH allocation in the outer-zone are :
RxLevDL > amrDirectAllocRxLevDL
and
RxLevUL > amrDirectAllocRxLevUL
DUALBAND OR DUALCOUPLING CELLS
The criteria for a successful direct HR TCH allocation in the outer-zone are :
RxLevDL > amrDirectAllocRxLevDL
and
RxLevUL > amrDirectAllocRxLevUL
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DIRECT HR TCH ALLOCATION IN INNER-ZONE, AT CALL SETUP
In v17, if using a not fully reliable short average, hoMarginBeg is added to the following
thresholds :
• amrDirectAllocIntRxLevDL
• amrDirectAllocIntRxLevUL
CONCENTRIC CELLS
The criteria for a successful direct HR TCH allocation in the inner-zone are :
RxLevDL > amrDirectAllocIntRxLevDL
and
RxLevUL > amrDirectAllocIntRxLevUL
and
MS_BS_Dist < concentAlgoExtMsRange (timing advance criterion)
DUALBAND OR DUALCOUPLING CELLS
The criteria for a successful direct HR TCH allocation in the inner-zone are :
RxLevDL > amrDirectAllocIntRxLevDL
and
RxLevUL > amrDirectAllocIntRxLevUL
DIRECT TCH ALLOCATION ON INTER-CELL HANDOVER
In v17, if using a not fully reliable short average, hoMarginBeg is added to bizonePowerOffset.
If the target cell for handover is a multi-zone cell, the BTS is in charge of indicating to the BSC
if a TCH can be allocated in the inner zone of the target cell. This information is provided in the
"additional cells information” IEI within Abis Handover indication or Connection state ack
messages :
This capability (to handover directly in the innerzone/band1 of the adjacent cell) is inhibited
when biZonePowerOffset(n) is set to 63.
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CONCENTRIC OR DUALCOUPLING CELLS
The criterion for the inner-zone of the neighbour cell to be eligible is :
RxLevNCell(n)ave > rxLevMinCell (n) + bizonePowerOffset (n) + Max(0, msTxPwrMaxCell(n) -
msTxPwrCapabilityCell(n) )
DUALBAND CELLS
The criteria for the inner-zone (band 1) of the neighbour dualband cell to be eligible are :
MS supports band 1 of NCell
and
RxLevNCell(n)ave > rxLevMinCell (n) + bizonePowerOffset (n) + Max(0, msTxPwrMaxCell(n) -msTxPwrCapabilityCell(n) )
REMARK ON OUTER TO INNER ZONE INTRA CELL HANDOVER
It should be noted that the BTS provides the same allocation information to the BSC on an
intra-cell handover initiated from a TCH belonging to the Large zone. However, no
hoMarginBeg margin applies to allocation thresholds because a Weighted average is always
available.
4.8.3 HANDOVERSEach runHandOver, after L1M initialisation process for handover, the BTS performs handover
decision process based on regular uplink and downlink measurements on the current cell
(level and quality) and neighbouring cells (level only); the main steps of this process are:
• Triggering: the BTS detects that a handover is needed by comparison with
thresholds: lRxLevXLH for alarm on level; lRxQualXLH for alarm on Quality;
msRangeMax for alarm on distance, there is no “triggering” for handover on
PBGT
• Screening: the BTS determines what are the 6 best suitable cells For the
handover (preferred cells list) and sends them to the BSC in the Handover
Indication message; to be in the preferred cells list, a cell must first be eligible
(eligibility checking) then sorted (Ncells list sorting); the preferred cells list is
an ordered list of sorted cells.
• Selecting: the BSC determines THE target cell according to the resource
found after reducing the preferred cells list to a maximum of three elements
• Executing: allocation, activation, assignment of the new channel, switching
onto this channel
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HANDOVERS TRIGGERING
Intercell handover normally occurs for two main reasons:
• Rescue handovers: when the MS gets too far from the BS (Distance) and/or
radio link measurements show low received signal strength (DL/UL signal
Strength) and/or signal quality on the current serving cell (DL/UL signal
Quality)
• Network Optimization Handovers: a better signal strength is available on an
adjacent cell (Power Budget), the serving cell gets overloaded (Traffic) or in
the particular case of a multilayer network (Capture)
Note: new intercell handover decisions have been introduced for AMR channels
Intracell handovers normally occur for the following reasons:
• Interference handover: radio measurements show a low received signal
quality but a high received signal strength on the serving cell.
• inter-zone handover from a "zone" of a multizone cell to another "zone".
• frequency tiering handover
• specific intracell handover for AMR TCH channels,
HANDOVERS SCREENING
To a given handover is associated (hard coded) a set of expressions used both to check
eligibility of a neighbour cell (a cell from the list of Ncells reported by the MS is eligible if allexpressions attached to this HO cause and neighbour cell are strictly positive) and to sort
target cells list.
See the chapter General formulas to get the detail of each expression.
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4.8.4 HANDOVERS DECISION PRIORITY
HANDOVER DECISION FUNCTIONS FOR SDCCH & TCH/F CHANNELS
The whole set of HO decision functions currently implemented for non AMR channels, with
their priority, is defined in the table below (handover functions are executed in increasing order
of priority as shown below):
HO decision function early HO intercell HO priority comment
Capture false intercell 1
UL signal quality false intercell 2
DL signal quality false intercell 3
UL signal strength false intercell 4
DL signal strength false intercell 5
Distance false intercell 6
Power Budget true intercell 7
Traffic false intercell 8 (d)
Intracell on UL signal strength & quality false intracell 9 (a) (c)
Intracell on DL signal strength & quality false intracell 10 (a) (c)
Interband HO (dualband cells) false intracell 11 (b) (c)
Interband HO (concentric cells) false intracell 11 (b) (c)
Interband HO (dualcoupling cells) false intracell 11 (b) (c)
Frequency tiering false intracell 12 (a) (c)
Directed Retry false intercell 0
(a) intracell and tiering handover functions are exclusive from each other
(b) these handover functions are exclusive from each other (a given cell may be of only one
type among concentric, dual-coupling & dual-band) and do not apply to SDCCH channels.
(c) these intracell handover functions are ihnibited when in directed retry mode.
(d) only for a monozone cell or in the large zone of a multizone cell.
Note: The so-called "Directed Retry" handover is a "pseudo" handover indication message
sent upon request from the BSC. This specific case is mainly intended to provide BSC with a
target cells list for intercell HO and is discussed in chapter Directed Retry Handover .
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HANDOVER DECISION FUNCTIONS FOR AMR TCH CHANNELS
HO decision function early HO intercell HO priority comment
Capture false intercell 1quality intercell HO on UL codec mode false intercell 2
quality intercell HO on DL codec mode false intercell 3
UL signal strength false intercell 4
DL signal strength false intercell 5
Distance false intercell 6
Power Budget false intercell 7
Traffic false intercell 8 (d)
capacity intracell HO on UL / DL codec modes false intracell 9 (b) (c)
quality intracell HO on UL codec mode false intracell 10 (b)
quality intracell HO on DL codec mode false intracell 11 (b)
Interband HO (dualband cells) false intracell 12 (a) (b)
Interband HO (concentric cells) false intracell 12 (a) (b)
Interband HO (dualcoupling cells) false intracell 12 (a) (b)
Frequency tiering false intracell 13 (b)
Directed Retry false intercell 0
(a) these handover functions are exclusive from each other (a given cell may be of only one
type among concentric, dual-coupling & dual-band).
(b) these intracell handover functions are ihnibited when in directed retry mode or in dual
tranfer mode.
(c) this intracell handover function applies to TCH/AFS (Full Rate) channels only.
(d) only for a monozone cell or in the large zone of a multizone cell.
Note: The so-called "Directed Retry" handover is a "pseudo" handover indication message
sent upon request from the BSC. This specific case is mainly intended to provide BSC with a
target cells list for intercell HO and is discussed in chapter Directed Retry Handover .
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4.8.5 DIRECTED RETRY HANDOVER
After the initial establishment procedure, if the MS is attached to a SDCCH and if there is no
TCH resource available, a directed retry handover is required.
The following parameters enable this feature:
• intraBscDirectedRetry (bsc)
• interBscDirectedRetry (bsc)
• intraBscDirectedRetryFromCell (bts)
• interBscDirectedRetryFromCell (bts)
Note: Directed Retry can be activated indepently from Queuing
DIRECTED RETRY HANDOVER: BSC (OR LOCAL) MODE
This mode is enabled by the bts object parameter directedRetryModeUsed set to “bsc”.
One of the adjacent cells is predefined as the one used for directed retry. The
adjacentCellUmbrellaRef parameter gives the position of this cell in the neighbor list.
CAUTION!
In this mode, there is no check of the RF conditions on the predefined target cell before the
directed retry HO occurs: the predefined cell must cover the whole area of the current cell.
To ensure that the MS is pre-synchronised with the predefined target cell (MS has decoded
GSM time and the BSIC), the neighbor cell BCCH must be put in the adjacentCellReselection
parameter bCCHFrequency.
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DIRECTED RETRY HANDOVER: BTS (OR DISTANT) MODE
This mode is enabled by the bts object parameter directedRetryModeUsed set to “bts”. It is
used, for example in the case of a high traffic cell covered by several neighbors.
When the BSC receives the Assign Request message from the MSC, the BSC requests the
BTS through a Connection State Request message to return a list of eligible neighbor cells
generated by the following criteria. This list is immediately sent through a Connection State
Acknowledgement message to the BSC. If the list is empty, the BTS tries to regenerate it later.
As soon as handover conditions are fulfilled for at least one neighbouring cell, the BTS sends
the BSC a spontaneous Handover Indication message with the specific cause “Directed
Retry”.
If RxLevNcell(n) > directedRetry(n) + Max[0, (msTxPwrMaxCell(n) - P)]
where P = maximum RF output power of the MS
then cell n is candidate for Directed Retry Handover
If RxLevNcell(m) = Max(RxLevNcell(n))
then Cell m is chosen by the BSC as the target cell for the Directed Retry HO
CAUTION!The Directed Retry criterion is based on only one measurement of RxLevNcell(n) and not on
NCellHreqave measurements.
In a microcell network, a directed retry HO may handover a call from a macro cell to a micro
cell even if the stability criteria is not fulfilled (microcellular handover type A). In this
environment, to avoid a ping-pong HO, one may put a high value to the adjacentCellHandOver
parameter directedRetryAlgo.
DIRECTED RETRY AND QUEUING
As soon as the directed retry is enabled in the BSS, whatever is the queuing activation, thedirected retry is processed. In that case,
• if queuing is activated, it is the same behavior as before V15.0. The only
change is that if the request could not be queued, the directed retry (if
allowed) is processed independently from the queuing.
• If queuing is desactivated, (or if the request could not be queued), then the
procedure is as follow: when the BSC receives from the MSC an Assignment
Request and there is no TCH available in the cell, then the directed retry
procedure is started and the BSC sends to the MSC a Queuing Indication
message to inform the MSC of a delay in the TCH allocation, and the MS
remains on SDCCH channel.
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If there is a resource in the target cell, the directed retry procedure is
successful and the communication is established.
If there is no resource available in the target cell, the directed retry
procedure fails and the BSS sends an Assignment failure (cause “no radio
resource available”) message to the MSC.If there is no neighbouring cells indicated by the BTS in the connection state
ack message, it means that neighbouring cells information are not available
in the BTS (it depends also on the MS performances) or handover conditions
are not met. Then the BSC starts an internal timer
directedRetryWithNoQueuingTimer (5 seconds, non configurable) in order to
wait for a handover indication message (cause “directed retry”) the BTS
sends if the handover conditions are fulfilled. The BSC processes this
handover indication message as described here above. In case the timer
directedRetryWithNoQueuingTimer expires, the BSC sends an Assignment
failure message (cause “no radio resource available”) to the MSC.
Note: during a directed retry procedure, if there is no TCH available in the target cell, the
procedure can neither be queued, nor execute another directed retry from the target cell.
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4.8.6 CONCENTRIC/DUALCOUPLING/DUALBAND CELL HANDOVER
CONCENTRIC CELL PRINCIPLES
The concept of concentric cell is enlarged and concentric cell parameter may have 4 possible
values: monozone, concentric, dualband or dualcoupling.
CONCENTRIC CELL
Definition: a cell is defined as concentric if it exists two transceiverzones configured to transmit
at different power resulting in two different coverage areas. For the two different
transceiverzones, the same antenna is used.
The principle of the concentric cells is to share the ressources in both zones assuming that the
TRXs are transmitting at different power. The BCCH and the signalling channels use the high
power TRXs (outer zone) thus the BTS needs to check if the link budget MS-BTS is sufficientto allocate a ressource of the inner zone. Furthermore, to avoid a subsequent intracell
handover, the BSC is checking this condition with the BTS each time a first TCH has to be
allocated at the end of the call setup, i.e an Assign Request has been sent by the MSC. The
same checking is done by the curent BTS when an intercell handover is required.
The smaller range of the frequencies in the internal zone, due to low maximum available
power for transmission, means that these internal zone frequencies can be reused a short
distance away. With this greater re-utilization of frequencies an operator can achieve the same
coverage using less bandwidth.
Concentric cell functionalities have been deployed allowing an easier frequency planning in
case of frequency hopping (fractional reuse techniques), and a major enhancement with the
TCH allocation directly in the relevant zone in case of calll setup and handover.
Note: a configuration with HePA on the outer zone and ePA on the inner zone is a kind of
concentric cell and not a kind of dualcoupling cell, eventhough the biZonePowerOffset
parameter has to be set accordingly to that particular case.
Please refer to the associated Functional Note [R10] Concentric cell improvements
(CM888/TF889). See also chapter Concentric Cells.
OuterzoneInnerzone
BCCH and
signalling
channels
traffic
channels
OuterzoneInnerzone
BCCH and
signalling
channels
traffic
channels
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DUALBAND CELL
Definition: a cell is defined as dualband if GSM900 TRXs and DCS1800 TRXs coexist and
share the same BCCH. The propagation loss being different, it results in two different
coverage areas.
Main benefits of dualband cell functionality are:
• The number of cells to configure and monitor is roughly divided by two
• No BCCH pattern has to be defined in the second band
• Frequency Hopping, Power Control, Downlink DTX are available on all second
band DRX’s (instead of all but one with conventional management)
• Slight increase in capacity: one TS saving + DCS and GSM DRX’s in one
pool, which provides more network control of the traffic distribution
• Intra cells Handover between DCS and GSM DRX’s of a same cell instead of
synchronous inter cell handovers reduce the muting time
Please refer to the associated Functional Note [R9] Dual band cells management:TF875. See
also chapter Concentric Cells.
DUALCOUPLING CELL
Definition: a cell is defined as dualcoupling if the TRXs are not combined with the same type of
combiner and thus have not the same coupling loss resulting in two different coverage areas.
In a dualcoupling cell, as the TRXs are not combined with the same type of combiner the most
powerful TRXs define the large zone. Such cells are managed with the concentric cell principle
and dualcoupling cell feature take advantage of it using different coupling modules rather than
a mono type coupling module in a sector.
Please refer to the associated Functional Note [R11] FN for stepped coupling. See also
chapter Concentric Cells.
Outerzone
band0GSM (or DCS)
Innerzone / band1DCS (or GSM)
BCCH and
signalling
channels
traffic channels
Outerzone
band0GSM (or DCS)
Innerzone / band1DCS (or GSM)
BCCH and
signalling
channels
traffic channels
OuterzoneH2D
InnerzoneH4D
BCCH andsignalling
channels
traffic
channels
OuterzoneH2D
InnerzoneH4D
BCCH andsignalling
channels
traffic
channels
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INTERZONE HANDOVERS FOR CONCENTRIC CELL / DUALCOUPLINGCELL
LARGE ZONE TO SMALL ZONE
The MS is permitted to migrate from the large zone to the small zone if:
• the MS is close to the BTS (Timing Advance used to estimate the MS to BTS
distance, only for concentric cells))
• and if RF conditions are good enough (RxLev downlink).
Note: The transceiverZone object parameter zone Tx power max reduction value is always set
to 0 for the large zone, and in the range of [1 to 55]dB for the small zone.
Since V18, a new criterion on uplink RxLev prevents MS from an assignment failure when the
uplink signal strength is not good enough to perform a handover toward the inner zoneThe Concentric/Dualcoupling Cell Handover from Large to Small zone is triggered if:
RxLev_DL > concentAlgoExtRxLev
AND
RxLev_UL>ConcentAlgoExtRxLevUL
AND (only for concentric cells)
MS_BS_Dist < concentAlgoExtMsRange
SMALL ZONE TO LARGE ZONE
The MS is handed over from the small zone to the large one if:
• the MS is far from the BTS (Timing Advance, used to estimate the MS to BTS
distance, only for concentric cells)
• or if RF conditions are too bad (RxLev downlink, RxQual uplink and downlink).
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For a non-AMR channel, or an AMR channel with legacy L1M, the Concentric/Dualcoupling
cell handover from small to large zone is triggered if:
RxLev_DL < concentAlgoIntRxLev
OR
RxLev_UL<concentAlgoIntRxLevUL
OR
RxQual_DL > lRxQualDLH
OR
RxQual_UL > lRxQualULH
OR
(only for concentric cells)
MS_BS_Dist > concentAlgoIntMsRange
For an AMR channel with AMR L1M, the Concentric/Dualcoupling cell handover from small to
large zone is triggered if:
RxLev_DL < concentAlgoIntRxLev
OR
RxLev_UL<concentAlgoIntRxLevUL
OR
(only for concentric cells)
MS_BS_Dist > concentAlgoIntMsRange
OR
Quality intercell HO on UL codec mode criterion is satisfied
OR
Quality intercell HO on DL codec mode criterion is satisfied
Please note that an external priority [0...17] can be given to the Concentric Cell Handover from
a Small to Large zone, because of the small to large Zone HO priority parameter.
INTERZONE HANDOVERS FOR DUALBAND CELLS
Convention:
• if BCCH gsm, then band 0 = gsm, band 1 = dcs and standardIndicator =
gsmdcs
• If BCCH dcs, then band 0 = dcs, band 1 = gsm and standardIndicator =
dcsgsm
The algorithms created for concentric cell are the same for dualband cells, except the timingadvance criterion is not used and the dualband capability of the mobile is checked.
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4.8.7 RESCUE HANDOVER
INTRACELL HANDOVER DECISION FOR SIGNAL QUALITY
The interferences are generally related to a specific TDMA. When signal quality is bad but
signal strength is sufficient, the BSC allocates another channel in the current cell.
Condition to be fulfilled is:
(((RXLEV_UL > rxLevULIH) AND (RXQUAL_UL > rxQualULIH))
OR
((RXLEV_DL > rxlevDLIH) AND (RXQUAL_DL > rxQualDLIH))
Thresholds should be set in order to ensure good subjective voice quality (rxqualXLIH 5 with
frequency hopping or rxqualXLIH 4 without hopping).
This feature is enabled by intraCell or intraCellSDCCH flags.
CAUTION!
In order to avoid the choice of a more interfered channel, channels are allocated in the 2 low
interference pools (hopping and not hopping); if no free channel is detected among these 2
pools and although queuing is allowed, the intracell HO must not be done; if queuing is
allowed, the request is queued then satisfied only after reception of suitable interference level
on idle channels (RF_RESOURCE_INDICATION message); when TDMA removals leads to
intracell HO, the first free resource is taken whatever its interference level.
Note: RF_RESOURCE_INDICATION message is received from BTS and induces the
interference level of channels of a particular TDMA. Therefore a channel has 3 states for the
BTS:
• Busy
• Free with interference measure level available
• Free without interference measure level available (for example the channel has just
been release and the measure are not yet done)
No interference level management is performed on PDTCH channels. The level status ofPDTCH resource is always high (bad level). So intracell HO is not performed on PDTCH
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4.8.8 POWER BUDGET HANDOVER
POWER BUDGET FORMULA
If powerBudgetInterCell parameter is set to “enabled” (handover on Power Budget is allowed),
the following formula is used to determine handover condition for power budget reason. This
handover is preventive and ensures best allocation of a serving cell for a given
communication. The formula used to determine handover condition for power budget reason
is:
EXP2PBGT(n) = Pbgt(n) - AdaptedHoMargin(n)
AdaptedHoMargin(n) is the margin computed when AHA feature is enabled. It takes into
account neighDisfavorOffset and servingfactorOffset parameters (see chapter Automatic
handover adaptation)
MINIMUM TIME BETWEEN HANDOVER
Minimun Time between handover feature is replaced by the General protection against HO
ping-pong feature.
However, in order for the new feature to be enabled the timeBetweenHOConfiguration
parameter must be set to “used”, and the bts Time Between HO configuration parameter must
be set to “1”.
4.8.9 HANDOVER FOR TRAFFIC REASONS
This feature aims at improving the network behaviour when one or several cells are
overloaded by attempting to redirect the most appropriate calls in progress to neighbour cells
with a PBGT handover procedure.
Please refer to the associated Functional Note [R12] Handover for traffic reasons: TF132. See
also chapter Handover for Traffic Reasons Activation Guideline.
This feature is enabled by the new BSC object parameter hoTraffic and by the new BTS object
parameter hoTraffic. For each neighboring cell of the cell (adjacentCellHandover object), a
parameter is defined: hoMarginTrafficOffset is the offset to (negatively) apply to the hoMargin
parameter linked to the power budget when the cell status becomes overloaded (if 0, the
handover for traffic reason is not allowed for this adjacent cell).
This features relies on the definition of the overload condition ; a cell overload condition can
only be determined by the radio resource allocator when the detection mechanism is
activated; it is activated as soon as the handover for traffic reasons feature or the Barring of
access class feature is authorized.
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This overload detection mechanism is based on the number of free TCH or the number of
queued TCH requests in the cell ; TCH resources reserved for maximum priority requests are
not taken into account ; in a concentric cell, TCH resources of the small zone are not taken
into account (no queuing procedure in the small zone) ; in a dualband cell, TCH resources of
the band1 are not taken into account (no queuing procedure in the band1) ; no more operator
warning is sent at the beginning and the end of the overload phase.
The overload begins when:
the number of free TCH <= numberOfTCHFreeBeforeCongestion
OR
the number of queued TCH requests >= numberOfTCHQueuedBeforeCongestion
The overload ends when:
the number of free TCH >= numberOfTCHFreeToEndCongestion
OR
the number of queued TCH requests <= numberOfTCHQueuedToEndCongestion
When the cell status becomes overloaded, a request is done to the L1M to consider a new
ho_margin (hoMargin-hoMarginTrafficOffset) ; this request is sent only to the TRXs which
belong to the large zone/band0 (for concentric/dualband cells).
In case of intra BSS handover (for traffic reasons), the BSC checks the target cell status
during the handover selection phase and if overload condition is set, the BSC will try on the
following cell of the list (a handover between the band0 of a serving cell and the band1 of a
target cell is possible if the eligibility of band1 is indicated in the handover indication
message).
In case of inter BSS handover (for traffic reasons), the target cell overload status is not known
until the HO procedure is launched (HO request). Also, a handover between the band0 of a
serving cell and the band1 of a target cell is not possible (due to the present A interface).
It is advised to set the General protection against HO ping-pong feature with this feature in
order to overcome the associated risk of ping-pong.
CAUTION!
This feature is not applicable for S4000/S2000E-DCU2 or S4000/S2000E-DCU2/DCU4.
This feature is applicable for all cases where PBGT handover is possible; so, handover for
traffic reasons is not possible between microcell and macrocell.
This feature is applicable to concentric/dualband cells but is restricted to the large zone/band0
since the thresholds used to define the overload conditions concern the large zone/band0 ; if a
handover indication is received by the BSC with a cause set to traffic reasons and concerns acommunication established in the small zone/band1 of the cell, the message is discarded.
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This feature is not applicable to a network which sets all the TCH request priorities to the
maximum priority since the cell is always overloaded whatever are the cell overload
thresholds.
Since the handover for traffic reasons feature uses the PBGT handover procedure, the
powerBudgetInterCell parameter shall be set to “true” (the BSC does not control this flag to
modify the hoMarginTrafficOffset). The BTS never transmits the Handover for traffic reasons if
this flag is not set.
There is no standby chain updating for the cell overload status ; thus, in case of switch-over,
the L1M value for hoMarginTrafficOffset is set to 0 and the cell is no longer overloaded.
About hoMarginTrafficOffset setting:
Typically, when hoMargin is reduced by 1dB (which implies that hoMarginTrafficOffset=1 dB),
this affects around 13% of the mobiles, assuming that cell overlapping is larger than the
hoMargin; roughly:
• 1dB of power reduction decreases the cell radius by 6.8% thus the cell
coverage by 13%
• 2dB of power reduction decreases the cell radius by 14%
• 3dB of power reduction decreases the cell radius by 21.9%
If hoMarginTrafficOffset is set to 0 dB, the HO traffic is somehow disabled since PBGT will be
done before the traffic has a chance to be done (higher priority).
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4.8.11 AUTOMATIC CELL TIERING
PREREQUISITE
It requires the implementation of L1mV2 and is exclusively applicable to fractional reuse
pattern networks (see chapter Frequency Hopping).
GOAL
The frequency tiering technique aims at decreasing the global interference level in a fractional
reuse pattern network and offers efficient traffic management at a TRX level through the self-
tuning system at the BTS
EXPECTED GAINS
The main benefits expected are:
• A large capacity increase: The cell tiering increases the fractional load
capabilities, therefore, permits bigger BTS configurations with the same
amount of available frequencies.). In a 1x1 network, the fractional load can go
up to 33.3% and up to 100% in 1x3.
• A better network quality (worst communications, typically at the cell boundary,
do no longer corrupt other communications). The reduction of the global level
of interference may also significantly decrease the global number of dropped
calls and other faults in particularly loaded networks.• A better uplink/downlink balancing (the uplink interference cancellation gain is
balanced by a significant downlink cell tiering improvement)
PRINCIPLES
The mechanism relies on simple dynamic resources allocation strategies that are intended to
allocate the worst communications, in terms of downlink Carrier on Interference ratio (CIR), to
the non-hopping frequencies (like BCCH), taking advantage of their larger reuse pattern and
consequently of their better resistance to interference, while the best communications are
driven to the hopping frequencies.
Evaluation of the calls is based on a ratio (in Watts) of the RxLevDL measured for the serving
cell over the sum of RxLevNCell measured for the BCCH of each neighbour, weighted
according to the type of interference brought (adjacent or co-channel).
This evaluation, called Potential Worst C/I (PWCI), potential because it does not include the
frequency hopping gain, is meant to simulate what the interference on the small pattern would
be like.
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The PWCI is computed by the BTS for all the calls in progress in the cell and arranged into an
averaged PWCI distribution that provides 2 handover decision parameters: lCirDLH (low) and
uCirDLH (high):
• lCirDLH is the abscissa corresponding to an ordinate of P% (percentage of
TCH resources in the large pattern) on the averaged PWCI distribution curve.
• uCirDLH is determined from: uCirDLH = lCirDLH + hoMarginTiering
In V12 P% is calculated as follow:
In V14, with AMR introduction P% is now calculated as follow:
• FH_HR% is the percent of HR calls managed by the hopping pattern in the
cell,
• HR% is the percent of HR calls managed in the cell.
The tiering handover decision can be summarised as:
• If PWCI > uCirDLH => HO is performed from large to small pattern
• If PWCI < lCirDLH => HO is performed from small to large pattern
The number of values required to trace the PWCI distribution curve may be modified via MMI
with the numberOfPwciSamples parameter (whereas cell tiering HO thresholds cannot be
tuned via MMI).
The lCirDLH is defined from the available traffic channels (i.e. TCH & PDTCH) in the non
hopping layer (because these one will be allocated to communications with worst PWCI). In
order to manage speech and data interworking, the averaged number of TCHs reserved for
data is defined with the nbLargeReuseDataChannels parameter.
To avoid the introduction of new configuration parameters or thresholds required by such a
function, the associated selfTuningObs functionality enables to set tiering working parameters
at their most relevant values, fitting with cell real radio profile and dynamically adapted to O&M
events or radio environment modifications ensuring that the gains of the tiering strategy are
always optimum.
P%=Number of non hopping TCH - nbLargeReuseDataChannel
Total number of TCH in the cell - nbLargeReuseDataChannelP%=
Number of non hopping TCH - nbLargeReuseDataChannel
Total number of TCH in the cell - nbLargeReuseDataChannel
P%=(Number of non hopping TCH – nbLargeReuseDataChannel) * (1 + Non_FH_HR%)
(Total number of TCH in the cell – nbLargeReuseDataChannel) * (1 + HR%)P%=
(Number of non hopping TCH – nbLargeReuseDataChannel) * (1 + Non_FH_HR%)
(Total number of TCH in the cell – nbLargeReuseDataChannel) * (1 + HR%)
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Formula of PWCI in Watts:
With
• RXLEV(0) the DL signal strength in Watts received from the serving cell, re-
scaled at maximum power (RxLev_DL + BS_Att)
• RXLEV (i) is the level in Watts measured on the BCCH of a neighbor cell
using the same TCH frequencies set as the current cell. These neighbors
generate co-channel interferences.
• RXLEV (j) is the level in Watts measured on the BCCH of a neighbor cell
using a TCH frequencies set different from that of the current cell. These
neighbors generate adjacent channel interferences.
• ADC corresponds to the first adjacent channel protection factor which is fixed
in the BTS software typically to 18dB
The PWCI value is the same whatever the effective load.
COMPATIBILITY WITH MULTIZONE CELLS
With concentric/dualband/dualcoupling cells, ACT is only applicable within the large zone.
Indeed, the tiering handover decision relies on the following algorithm:
• IF the TDMA bearing the considered channel belongs to the small pattern
AND does not belong to the small zone of a multizone cell:
IF pwCi < lCirDLH
THEN the channel will be put on the large pattern
• IF the TDMA bearing the considered channel belongs to the large pattern
(which implies that it belongs to the large zone):
IF pwCi > uCirDLH
THEN the channel will be put on the small pattern
PWCI=RxLevDL Watts
SUM [RXLevNCell (i)] Watts SUM [RXLevNCell (j) - ADC] WattsPWCI=
RxLevDL Watts
SUM [RXLevNCell (i)] Watts SUM [RXLevNCell (j) - ADC] Watts
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In this case, P is computed by considering exclusively the resources in the large zone
(hopping as well as non hopping). In order to perform a tiering handover, the communication
must be in the large zone and there must be fractional reuse in it. The large pattern will only
be the BCCH frequency (the other TRXs in the large zone must hop) and the communication
will stay in the Large zone.
CELL TIERING MONITORING
The PWCI statistics and uCirDLH/lCirDLH may be transmitted on the Abis interface according
to the selfTuningObs parameter; these statistics are available independently of the activation
of the feature.
The hoRequiredTch counter C1138 has 2 new screenings (tiering handover from large to
small pattern and tiering handover from small to large pattern) ; two new counters are added:
C1802 (hoSuccessTieringTch) and C1801 (hoFailureTieringTchNorr) with 2 screenings each
(0: large pattern to small pattern & 1: small pattern to large pattern).
The table below gives indicative values for the time required to gather nbPwCISamples
measurements for different cell configurations, assuming the average TCH occupancy rate is
75% and that one TCH provides 1 PwCI measurement every 480 ms which is roughly 2 PwCI
measurements per second:
Cell configuration 20000 nbPwCISamples 60000 nbPwCISamples
O2 (14 TCH) # 16 min # 48 min
O4 (29 TCH) # 8 min # 24 min
O8 (59 TCH) # 4 min # 12 minO16 (121 TCH) # 2 min # 6 min
The time required to reach a sufficient statistics as well as the time between two consecutive
tiering threshold updates depends on the number of samples required, and the capacity
(number of TCH) and load of the cell.
So a way to decrease the period between 2 consecutive threshold updates is about the half of
the time required to reach a first reliable statistics.
CAUTIONS
Because it takes advantage of BTS O&M centralization, this feature applies also to 2G
products (equipped exclusively with DRXs).
The activation of this feature implies a previous activation of the L1mV2.
The statistics (for PWCI) are not kept during upgrade and must be gathered again after the
site reconfiguration.
Intracell handover for quality and intracell tiering handover are exclusive (choice managed with
the intracell parameter of the handOverControl object). For mobiles at cells boundaries, if for
PBGT reasons, a handover is decided towards a new cell on a hopping TCH, a subsequent
handover for tiering reasons will be possible towards a non hopping TCH and so on, so
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inducing a risk of ping-pong handovers ; this drawback will be avoided with the well tuning of
hoMarginTiering parameter.
No tiering handover decision is possible if the TDMA bearing the current TCH belongs to the
small zone/band1 of a multizone/dualband cell.
If tiering is activated, no tiering decision is undertaken by the BTS as long as a reliable
statistics has not been gathered (minimum nbPwCISamples for PWCI measurements); field
experiments have shown that at least 20000 PWCI samples are needed.
In V12, statistics are not maintained on the BCF passive chain.
The cell tiering configuration relies on a correct definition of interferes for each cell (through
interfererType). This feature is based on values of PWCI that depend on the overlap, the
available spectrum and the sites' density but neither on the traffic nor the fractional load.
However, when the traffic is low, there are fewer samples than at the busy hour and the PWCI
distribution is therefore a touch less relevant.
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4.8.12 MICROCELLULAR HANDOVER
HANDOVER PECULIARITIES IN MICROCELL ENVIRONMENT
Microcellular algorithms were initially defined to avoid issues due to fast moving mobiles
connected to microcells. People thought that fast moving mobiles would not have enough time
to receive handover information coming from the network or would jump some microcells. To
avoid communication failures, specific handover algorithms were defined to send fast moving
mobiles to the macro layer.
However, experiments performed on several microcellular networks demonstrated that fast
moving mobiles linked to outdoor microcells do not present any issues. Microcellular
algorithms are used mainly to split traffic loads on the two layers, regardless of mobile speed.
Most microcellular algorithms are based on a “capture” threshold. Mobiles linked to amacrocell perform a handover towards the micro layer as soon as the field strength received
from a microcell is sufficiently high (whatever the field strength received from the macrocell)
for a sufficient duration.
The microcellular handover algorithm type A is also based on the stability of the signal. Before
V12, with L1mV1, the stability was checked on the best neighbouring microcell, now L1mV2
launches in parallel the confirmation process for the 6 best microcells.
MICROCELLULAR ALGO TYPE A
The following table describes permitted handover causes according to the type of the serving
cell and the neighbor cell.
Note: the traffic handover is only possible from a large zone (or monozone).
The capture handover algorithm can only be defined from a macrocell to a microcell. However
the type of a cell is defined relative to the type of the neighboring one. It means that the type of
a cell A can be a macrocell from the cell B point of view but can be a microcell from the cell C
point of view. This way, it is possible to use the capture handover algorithm on both sides,
macrocell to microcell and microcell to macrocell.
L1mV2: Selection of the 6 best microcells
MS stability check on these 6 microcells
Selection of the 6 new best microcells
(transmitted to BSC)
Handover execution
L1mV2: Selection of the 6 best microcells
MS stability check on these 6 microcells
Selection of the 6 new best microcells
(transmitted to BSC)
Handover execution
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Neighbour cell cellType [adjacentCellHandover]
normalType umbrellaType microType
normalType
signal quality
signal strength
distance
power budget
traffic
directedRetry (BTSmode)
forced handover
signal qualitysignal strength
distance
power budget
traffic
directedRetry (BTS mode)
forced handover
signal qualitysignal strength
distance
power budget
traffic
directedRetry (BTS mode)
forced handover
umbrellaType
signal quality
signal strength
distance
power budget
trafficdirectedRetry (BTSmode)
forced handover
signal quality
signal strength
distance
power budget
traffic
directedRetry (BTS mode)
forced handover
capture
directedRetry (BTS mode)
forced handover
S e r v i n g c e l l c e l l T y p e
[ b t s ]
microType
signal quality
signal strength
distance
power budget
traffic
directedRetry (BTSmode)
forced handover
signal quality
signal strength
distance
directedRetry
(BTS mode)
forced handover
signal quality
signal strength
distance
power budget
traffic
directedRetry (BTS mode)
forced handover
However the Type A handover algorithm has not been specifically defined to perform
handovers from microcells to the macrocell layer.
A timer linked to that algorithm is tunable via the microCellCaptureTimer parameter. That timer
prevents the BSC from doing a handover on capture reason during a fixed period.
See also General formulas for the capture expression:
EXP1Capture(n) = RxLevNCell(n) ave - rxLevMinCell(n)
Furthermore a strength level stability Criterion (microCellStability) has to be respected beforetriggering a handover toward the microcell.
While microCellCaptureTimer(n) goes on, if a normal handover decision is verified, a handover
towards a cell of the same type or a normal cell is allowed.
While a handover is decided, the list of eligible cells is provided at each runHandover
(microCellCaptureTimer (n) is not reinitialised).
The threshold microCellStability(n) must be put previously to 63 dB. This value ensures that a
handover is performed as long as the field strength received from the neighbor cell is higher
than the “capture” threshold. The value can then be reduced case by case.
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CAUTION!
The microcellular feature is an OMC-R option (must be activated at OMC-R installation).
Thanks to the Advanced Speech Call Items Evolution functionality (refer to [R30]) the range of
the microCellCaptureTimer has been modified.
Initially that modification was designed for GSM-R applications: microcellCaptureTimer at 500s
is to avoid to be captured by a railway station cell for a communication established in the train
and thus to avoid that an on going communication from a train arriving in a railway station with
no stop, is captured by the railway station cells and when leaving the railway station, leads to
a new handover to the railways track cells.
Before V15.1 microCellCaptureTimer, on adjacentCellHandover object, has a range [0 … 255]
which means a maximum of about 255 * runHandOver (runHandOver is expressed in
multiples of 480 ms for SACCH frames and multiples of 470 ms for SDCCH frames) for a
communication, before being captured by a neighbouring cell which has a minimum and a
stable rxlev during this period.The request consists in increasing the range of this parameter, so as it is kept as it is, but the
meaning of specific values are changed to give them greater values (conversion to a value
greater than 255).
microCellCaptureTimervalue received by the BTS
microCellCapture value used by the BTS for the computation
(number of reporting period x*480ms)
0 to 249 0 to 249
250 512 245 s
251 1024 491 s
252 2048 983 s
253 4096 1966 s
254 8192 3932 s
255 16384 7864 s
This table is applicable for a runHandOver = 1. If runHandOver = 2, then 491 seconds are
obtained with MicrocellCapture value set to 250.
Note: if the Handover on SDCCH feature is activated, the timer must be computed by
multiplying the BTS used value by 470 ms.
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4.8.13 FORCED HANDOVER
This feature is used to force a handover towards neighboring cells. If a cell is to be shut down,
forcing handovers avoids dropped calls.
It has to be used in addition to the soft blocking feature (barring of incoming Handover, barring
of new calls).
Through a Connection State Request message, the BSC requests that the BTS sends it a list
of eligible neighbor cells. This list, immediately sent through a Connection State
Acknowledgement message to the BSC, is generated by the following criteria:
EXP1Forced HO =(n) RxLevNCell(n) ave - [forced handover algo(n) + Max(0,
msTxPwrMaxCell(n) - msTxPwrCapability(n)]
By putting a low value to forced handover algo(n) , the HO becomes easier: the cell is
released more rapidly.
CAUTION!
A forced HO is possible after a certain communication duration:
duration = Max( rxQualHreqave * rxQualHreqt, rxLevHreqave * rxLevHreqt,
rxNCellHreqave).
Therefore, when integrating this feature in the soft blocking procedure, the operating mode is
the following:
• soft blocking,
• wait a certain time (20 seconds),
• trigger the forced HO.
There is only one attempt per cell.
Another reason to use a Forced HO with soft blocking is that a Forced HO may interrupt a
Directed Retry HO (if the Connection State Request message of the Forced HO arrives before
the Handover Indication cause Directed Retry message). One must wait a period of time after
the soft blocking so that all calls have time to move from SDCCH channels to TCH channels.
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4.8.14 EARLY HANDOVER DECISION
PROBLEM DESCRIPTION
The time for a mobile to reselect a cell in idle mode is quite long. So, a mobile can start a
communication while camping in another cell, leading to a call drop in the worst case.
If the reselection algorithm execution occurs close to the border of cell A the mobile can setup
a call a short moment after in the cell B while the cell A is still selected. Unfortunately, the MS
has to wait a certain period of time before being able to make an handover. The system has to
perform some measurements before taking some handovers decisions.
This period of time is quite critical, there are some risks of call drop because of the low level ofthe signal.
Another issue is concerned by this feature ; that is the problem of a mobile turning at a street
corner, when the RxLev suddenly decreases in the serving cell and increases for a neighbour
cell.
FEATURE DESCRIPTION
The principle is not to speed the selection process but to allow a handover on PBGT quicker.
Time
Cell A
Cell B
1
2
3
Risk
of
call
drop
1 sel/reselection
algo execution
2 call setup in cell A
3 HO toward cell B
Time
Cell A
Cell B
1
2
3
Risk
of
call
drop
1 sel/reselection
algo execution
2 call setup in cell A
3 HO toward cell B
cell A
cell B
Beginningof new call
cell A actually selected
Endof last call
cell A
cell B
Beginningof new call
cell A actually selected
Endof last call
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Two shorter averages are defined for the level of the serving cell (rxLevHReqaveBeg) and for
the level of the neighbouring cells (rxLevNCellHReqaveBeg).
The L1M will use this new shorter averages at the beginning of the call until Max
(rxLevHreqave*rxLevHreqt, rxQualHreqave*rxQualHreqt) is reached and after loss and
recovery of BSIC.
The L1M must only wait:
• shorter level arithmetic average of serving cell (rxLevHReqaveBeg)
• shorter level average of the neighbouring cell (rxLevNCellHReqaveBeg)
Therefore, the handover can be performed more quickly and with less measurements.
The principle is not to speed the selection process but to allow a handover on PBGT quicker.
It allows to reduce the zone which represents the critical period of time. The first impact of this
feature is to reduce the probability of establishment failure and the call drop ratio.
A third parameter has been created (HOMarginBeg) in order to compensate the lack of
measurements by increasing the HOMargin.
The parameter rxLevNCellHReqaveBeg is used each time a new cell is detected by the
mobile. Therefore, it increases the system reactivity.
EXP2PBGT(n) early = Pbgt(n) - [hoMargin(n) + hoMarginBeg(n)]
UNTIL
Max(rxLevHreqave * rxLevHreqt, rxQualHreqave * rxQualHreqt) is reached
4.8.15 MAXIMUM RXLEV FOR POWER BUDGET
One of the issues to solve, in a microcellular network, is street corner (cross road)
environment:
In case of mobile moving straight the cross road (two orthogonal cells A and B), a handover
for Power Budget may be processed from cell B to cell A. Once the cross is passed, the
mobile is handed again over the cell B.
This ping-pong handover shall be avoided as useless handover leads to voice quality
degradation and signalling increase.
Another advantage of this feature is the possibility to reduce unnecessary handovers at border
of Location Area, interBSC or interMSC HO. In this case the need to perform Power Budget
handovers is diminished against the extra load on NSS and the voice quality.
The feature provides a solution by preventing handover for power budget from the serving cell
if the RXLEV downlink serving cell level exceed a specific threshold
To prevent handovers for power budget from the serving cell if the RXLEV downlink serving
cell level exceed a specific threshold (rxLevDLPBGT), the following expression used in
combination with existing cell selection criteria is actually:
RXLEV_DL < rxLevDLPBGT
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4.8.16 PRE-SYNCHRONIZED HO
During an asynchronous handover, the MS repeats the HO access bursts until it receives the
physical information message containing the timing advance of the new cell. So the speech
cut duration may last as long as the MS receives the new TA (Timing Advance) applied in the
new cell.
The pre-synchronized handover feature allows a Phase 2 MS to make a synchronized
handover between two (2) cells not belonging to the same site but managed by the same
BSC. The procedure is the same as for an intra-site synchronized handover, excepted that the
TA is set in advance and is transmitted to the MS at the beginning of the HO procedure.
CAUTION!
Only intra BSC synchronized handover are possible.
There are two possibilities to set the timing advance in case of pre-synchronized HO:
Presynchro with default value or with a determined Timing Advance.
Two parameters are impacted in the adjacentCellHandOver object to enable this feature:
• synchronized is set to the value “pre sync HO, with timing advance” or “pre sync
HO,default timing advance”.
• preSynchroTimingAdvance indicates the value of the TA.
By comparing not synchronized handovers with synchronized handover, a phonetic gain from
20ms to 40 ms is expected. This is due to the Physical_Info message suppression, which is
not necessary because on pre-synchronized handover, the timing advance value is carried by
the Handover_Command message. Moreover, only four Handover_Access messages are
used on pre-synchronized handover instead of more than four in case of not synchronized
handover.
4.8.17 RADIO CHANNEL ALLOCATION
The radio channel allocation is based on the interference levels computed on the BTS free
channels (SDCCH and TCH).
Every averagingPeriod the BTS sends RF RESOURCE INDICATION messages to the BSC.These messages are related to one TRX and contain the level of interference of the free
channels. These interference levels are classified into one from the five possible interference
bands (thresholdInterference parameter). In each of the five bands, the resources are sorted
from the least to the most recently used.
At the BSC level the free channels are divided into two new groups depending on whether
their interference level is above or below the RadChanSellIntThreshold value. Each group is
itself divided into two sub-groups, depending on whether the resource supports the Frequency
Hopping.
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CAUTION!
• If, during three (3) successive RF RESOURCE INDICATION messages, an
incoherency is noticed at the BSC level concerning the avaibility of a radio
channel, the channel is released and is returned free to the allocator.
• When a resource is released upon a call termination, it always returns to thepool of worst interference level, whatever its level before the allocation. The
next measurement received from the BTS for this resource will be used to
update the level and, consequently, to find the appropriate pool.
• The inner zone of a concentric cell does not support SDCCH channels. Till
V11, although they belong to the same cell, TCH pools for the inner zone are
separated from the same pools of the outer zone, and there are no possible
channel exchanges between the two zones.
• When a SDCCH is requested and no SDCCH is available, the external
priorities are considered as a TCH can be allocated instead of a SDCCH,
following the TCH allocation principles.
• If a TCH is requested and the priority threshold is reached, only priority 0
requests will be served. Other priorities will generate negative responses from
the allocator.
4.8.18 DEFINE ELIGIBLE NEIGHBOR CELLS FOR INTERCELLHANDOVER (EXCEPT DIRECTED RETRY)
When an intercell handover is required, the BTS sends a list of at most 6 best suitable cells
according to EXP1 and EXP2 formulas.
The following diagram shows an example of cell interlapping produced by different values of
lRxLevDLH (threshold out of Cell A) and rxLevMinCell (threshold in Cell B, assuming it is a 2W
mobile and msTXPwrMaxcell is set to 33dB). If values are too restrictive, then Cell B will not
be considered as an eligible cell for handover and the call might be dropped. This might be the
case especially in rural areas where cells have little overlap.
Putting a high value for rxLevMinCell(n) or a high value for msTXPwrMaxCell(n) results in
restricting access to that cell (see following diagram).
There is a different margin for each handover cause:
hoMarginDist, hoMarginRxLev, hoMarginRxQual (can be negative), hoMargin (for power
budget), thus compliance to that formula becomes mandatory i.e a handover can only be
performed towards a neigbourCell for which the (PBGT(n) - hoMargin(dist, rxqual, rxlev)) ispositive.
Cell BCell A
HO 1
-98 dBm
HO 2
-92 dBm
lRxLevDLH
-100 dBm
rxLevMinCell (B)
-95 dBm
Cell BCell A
HO 1
-98 dBm
HO 2
-92 dBm
lRxLevDLH
-100 dBm
rxLevMinCell (B)
-95 dBm
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4.8.19 HANDOVER TO 2ND BEST CANDIDATE WHEN RETURN TOOLD CHANNEL
This feature is triggered by a handover failure during the execution phase.
If hoSecondBestCellConfiguration = 1
then no HO attempt to 2nd best candidate cell
If hoSecondBestCellConfiguration = 2
then HO attempt to 2nd best candidate cell
If hoSecondBestCellConfiguration = 3
then HO attempt to 2nd best candidate cell and to 3rd best candidate cell
(if the HO attempt to 2nd best candidate cell fails)
When the HO attempt towards the last candidate fails, the bssMapTchoke starts at the BSC.
At the expiry of the timer, the BSC asks the BTS to provide a new list of eligible cells.
4.8.20 PROTECTION AGAINST RUNHANDOVER=1
The objective is to get a more responsive handover detection mechanism. To reach this goal,
the HO algorithm shall be run every 480 milliseconds (i.e runHandover =1 SACCH period).
This feature is useful for call drop rate improvement.
With this configuration (runHandover=1), a protection shall be implemented to avoid BSC
overload.
In case of saturated network (no free TCH) the request for handover (HO-Indication message)
will be repeated every 480 ms by the BTS, even if the target cell list has not changed.
This could cause SICD overload problems at the BSC. Although the BSC is protected against
this, such a situation should be avoided as much as possible in order not to disturb cells not
concerned by the congestion situation that could also be supported by the overloaded SICD.
As a consequence, the HO_Indication shall be repeated every 2 SACCH periods (1 second) in
case of run HO = 1.
If the content of the “preferred cell list” IE is modified (i.e. the content or the order of the cell
list), the HO_IND message shall be repeated every runHandover (even if runHandover=1).
In addition to that, the HO_IND message has also to be sent if the reason for handover has
changed, for the reason that there is no “preferred cell list” IE in case of intracell handover for
example.
The value of 1 second is justified by the fact that existing operational networks are currently
working with the value of runHandover=2, and therefore no strongest protection is needed.
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4.8.21 GENERAL PROTECTION AGAINST HO PING-PONG
This feature allows to easily solve some ping-pong handover problems (like ping-pong after
directed retry or ping-pong microcell -> macrocell -> microcell or ping-pongs already managed
by the previous feature Minimum time between Handover ).
It is enabled by the BSC object parameter timeBetweenHOConfiguration and by the BTS
object parameter bts Time Between HO configuration (0 means “not used” and value greater
than 0 means “used”).
For each neighboring cell of a cell (adjacentCellHandover object), two new parameters are
defined: hoPingpongCombination defines up to four combinations (incoming cause, outgoing
cause) used in order to define forbidden handovers during hoPingpongTimeRejection seconds
for all combinations.
When the BSC receives from the BTS a Handover Indication, it calculates the time spent in
the cell since the last handover (named connection_time) and removes from the preferred
cells list the eligible cells for which the connection_time is lower than the corresponding
timeRejection and for which the combination (incoming cause, outgoing cause) corresponds to
a combination defined in HOPingpongCombination.
The incoming causes may be: RXLEV (indifferently for uplink and downlink), RXQUAL
(indifferently for uplink and downlink), DISTANCE, PBGT, CAPTURE, DIRECTED_RETRY,
O&M (for forced handovers), TRAFFIC, AMRQUALITY, ALL (if the incoming cause matches
all the preceding causes), ALLCAPTURE, ALLPBGT.
The outgoing causes may be:
• RXLEV (indifferently for uplink and downlink)
• RXQUAL (indifferently for uplink and downlink)
• DISTANCE
• PBGT
• CAPTURE
• O&M (for forced handovers)
• TRAFFIC
• AMR QUALITY
• ALL (if the incoming cause matches all the preceding causes)
• ALLCAPTURE (if the outgoing cause matches the CAPTURE cause for all themicrocells belonging to the current macrocell)
• ALLPBGT (if the outgoing cause matches the PBGT cause for all the
neighboring cells of the current cell ; this cause can be used to restore the
“Minimum time between handovers” feature
AMR QUALITY cause has been introduced for AMR purpose. See also chapter General
protection against HO Ping Pong in the feature interworking part of AMR chapter.
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CAUTION!
The parameters hoPingpongCombination and hoPingpongTimeRejection must be defined at
the “entering cell” (relatively to the first HO of the combination) level, for the neighbouring cell
(adjacentCellHandover object) corresponding to the “left cell” (still relatively to the first HO of
the combination). Thus, these parameters are known by the “new BSC” whatever the type of
HO is (intra or interBSC).
For interBSS handovers, if the Cause element is not included in the HANDOVER_REQUEST
message sent from the MSC to the target BSC, then this feature is not applied except when
the incoming_cause in hoPingpongCombination parameter is set to ALL.
During upgrades, if bts Time Between HO configuration is greater than 0, then bts Time
Between HO configuration is set to 1, hoPingpongTimeRejection is set to the previous value of
bts Time Between HO configuration and hoPingpongCombination is set to (all, allPBGT) and if
bts Time Between HO configuration is equal to 0, then it keeps the same value,
hoPingpongTimeRejection is set to 0 and hoPingpongCombination is set to empty.
The C1166 counter related to the “Minimum time between handover” feature is removed and
replaced by the C1782 counter incremented when a cell is removed of the preferred cells list
(so, for one handover indication message, it can be incremented several times).
This feature gives no protection against intracell or interzone ping-pong handovers and gives
no protection against ping-pong handovers between more than 2 cells except for allCapture or
allPBGT outgoing causes.
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4.8.22 AUTOMATIC HANDOVER ADAPTATION
This feature adapts handover parameters to radio environment of each call, taking into
account mobile speed and frequency hopping. The objective is to minimize call drops and badquality transients.
PRINCIPLE
In order to eliminate the fading in the measurement processing, some averaging mechanisms
are implemented. But the frequency hopping and the mobile speed introduce frequency and
space diversity and average the attenuation of the received signal:
As shown on the diagram above, the faster the mobile moves the less the fading is impacting
(space diversity).
Mobiles can also be sensitive to the frequency diversity as shown on the diagram below. The
more hopping frequencies are used the less fading is impacting.
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The principle of this feature is to use these averages introduced by the frequency hopping and
the MS speed, in order to decrease the number of measurements take into account or the
handover margin.
DECISIONS FACTORS
FREQUENCY HOPPING
In order to have a sufficient averaging of the Rayleigh fading, the number of frequencies in the
hopping law has to be greater or equal than 4. If the number of frequencies in the hopping law
is less than 4, mobiles are considered as non-hopping, and all processing defined for non
hopping mobiles are applied.
This criterion and all associated mechanisms are applied to the following channels:
• TCH full rate whatever the channel coding (data circuit, EFR, FR, AMR…),
• TCH half rate,
• SDCCH.
MS SPEED EVALUATOR
From internal studies and simulation, a mobile can be considered as a fast mobile, if the
standard deviation in dB of the Rxlev during one period of measurement (i.e. 104 bursts, thus
480ms) is less than 1.4dB.
This standard deviation represents approximately:
• 20 km/h in GSM900,
• 10km/h in GSM1800 and GSM1900,
and is sufficient to have a good averaging of the Rayleigh fading.
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HALF RATE AND SDCCH CHANNELS
For half rate channels, the number of bursts during one period is sufficient to evaluate with a
correct accuracy the standard deviation criteria, then all treatments associated to this criteria
are relevant for this kind of channels.
UPLINK DTX
In case of uplink DTX activation during the period, the number of bursts received is decreased,
thus the accuracy of the calculated standard deviation is decreased. In this case, the standard
deviation is not evaluated and the last calculated standard deviation is taken.
UPLINK POWER CONTROL
In case of uplink power control, the BTS is not able to distinguish between a variation due to
Rayleigh fading and one due to a power control attenuation. Thus if the power control requireda variation of more than 8 dB during the period, then the standard deviation is not evaluated
and the last calculated standard deviation is taken.
AUTO ADAPTATION MECHANISMS
This feature is activated if the selfAdaptActivation parameter is set to “enabled”.
PBGT HANDOVER ADAPTATION
For this mechanism, two new parameters are added: servingfactorOffset, neighDisfavorOffset
and the previous factor hoMarginBeg is reused.
Following tables show for each case, the AdaptedHoMargin value and the averaging windows
taken into account in the PBGT handover mechanism according to
• the MS type: fast or slow mobile or managed by a hopping TCH,
• the number of measurement of the serving cell compared with the normal
averaging window,
• the number of measurement of the neighbouring cell compared with the
normal averaging window.
See chapter EXP2 to understand how AdaptedHoMargin is used.
For each cases of measurement, the tables below give the HO Margin result.
Example:
IF
number of available measurements for the cell < normal window
AND IF
number of available measurements for the neighbour cell < normal window
THEN
AdaptedHoMargin = hoMargin+ neighDisfavorOffset
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Mobile Type: SFH MS
cell measurement neighbour cell measurement AdaptedHoMargin
< rxLevHreqaveBeg < rxLevNCellHreqaveBeg hoMargin + neighDisfavorOffset
< rxLevHreqaveBeg ≥ rxNCellHreqave hoMargin
≥ rxLevHreqave < rxLevNCellHreqaveBeg hoMargin + neighDisfavorOffset - servingfactorOffset
≥ rxLevHreqave ≥ rxNCellHreqave hoMargin - servingfactorOffset
Mobile Type: Slow non SFH MS
cell measurement neighbour cell measurement AdaptedHoMargin
< rxLevHreqaveBeg < rxLevNCellHreqaveBeg hoMargin + hoMarginBeg
< rxLevHreqaveBeg ≥ rxNCellHreqave hoMargin + hoMarginBeg
≥rxLevHreqave < rxLevNCellHreqaveBeg hoMargin + neighDisfavorOffset
≥ rxLevHreqave ≥ rxNCellHreqave hoMargin
Mobile Type: Fast non SFH MS
cell measurement average neighbour cell average AdaptedHoMargin
rxLevHreqaveBeg rxLevNCellHreqaveBeg hoMargin
POWER CONTROL ADAPTATION
For this mechanism, a new parameter is added: rxQualAveBeg.
The following table shows for each case, the averaging taken into account in the power control
mechanism.
Mobile type RxLev average RxQual average
SFH MS rxLevHreqaveBeg rxQualAveBeg
“Fast” non SFH MS rxLevHreqaveBeg rxQualAveBeg
“Slow” non SFH MS no modification
In case of short averaging, due to the measurement quality, no specific value of K (refer to
chapter One shot power control (Pc_2) for more details on this value) is taken into account.
For slow mobile, Fast power control at TCH assignment (Pc_3) is still available in order to
reduce the power control activation time, but the first decision of power control is now taken
with Max[rxLevHreqAveBeg, rxQualAveBeg] measurements, instead of rxLevHreqAveBeg.
4.8.23 PROTECTION AGAINST INTRACELL HO PING-PONG
This feature controls the overall handover process, to avoid oscillations or so called "ping-
pong" handovers, to deal with the complexity introduced by all various situations with
BSC3000
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There are various reasons where intracell handovers needs to be triggered, for instance:
• RxQual degradation with high RxLev,
• transition from inner zone to outer zone in a multi-zone cell
but also
• transition from AMR-FR to AMR-HR,
• transition from outer zone to inner zone in a multi-zone cell.
The first two cases are required to maintain call quality, whereas the last two cases are
decided to optimise system capacity.
PRINCIPLE
For this feature, two kinds of intracell handover are distinguished:
• capacity intracell handover: this expression groups all intracell handovers,
which are triggered in order to increase the network capacity:
interzone handover from the outer to the inner zone,
AMR handover from FR to HR TCH,
tiering from BCCH to TCH frequency pattern.
• quality intracell handover: this expression groups all intracell handovers,
which are triggered if the quality of the call is not sufficient:
normal intracell handover,
inter-zone handover from the inner to the outer zone,
AMR handover from HR to FR TCH,
tiering from TCH to BCCH frequency pattern.
The principle of this feature is to introduce two timers, associated to the intracell handover
type, which delay an intracell handover after an intracell handover:
• capacityTimeRejection: defines the rejection time of a capacity intracell
handover after an intracell handover,
• minTimeQualityIntraCellHO: defines the rejection time of a quality intracell
handover after an intracell handover.
First intracell HO
minTimeQualityIntraCell HO
capacityTimeRejection
Quality intracell
HO request
Capacity intracell
HO requestFirst intracell HO
minTimeQualityIntraCell HO
capacityTimeRejection
Quality intracell
HO request
Capacity intracell
HO request
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4.8.24 GSM TO UMTS HANDOVER
PRINCIPLE
Thanks to this feature, GSM to UMTS handover is possible for dual-mode mobiles in areas of
2G-3G coverage.
This feature requires the setting of O&M parameters in the following domains :
• Normal or Enhanced Measurement Reporting activation and configuration
• UTRAN classmark activation and configuration
• Declaration of neighbouring cells belonging to the UTRAN
• Handover timers, thresholds and margins
PREREQUISITES
Note that EMR is not a preequisite for 2G-3G handover. The system can perform handover on
mobiles that perform normal reporting.
EARLY CLASSMARK SENDING ACTIVATION
Early classmark sending consists in the mobile sending as early as possible after access a
CLASSMARK CHANGE message to provide the network with additional classmark
information.
Early classmark sending activation is mandatory as EMR capability and FDD radio capability
is provided by the mobile to the BSS in the Classmark 3 IE sent in the CLASSMARK CHANGE
message.
Rule :
earlyClassmarkSending (v10 parameter) = allowed.
3G CLASSMARK SENDING ACTIVATION
Although it is not used by the BSS, the UTRAN classmark information is mandatory to perform
a GSM to UMTS handover as the "INTER RAT HANDOVER INFO" IE shall be included by theBSC in HANDOVER REQUIRED message.
The activation flag earlyClassmarkSendingUTRAN is used by the BSC and the MS:
• when the “3G Early Classmark Sending Restriction” field in SYSTEM INFORMATION
TYPE 3 message is set 1 (enabled), the MS is asked to the send its UTRAN
capabilites at the call set-up in the UTRAN CLASSMARK CHANGE message
subsequent to the CLASSMARK CHANGE one.
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• on an incoming handover, if the UTRAN capabilities have not been received by the
the target BSC in the HANDOVER REQUEST message, this BSC sends a
CLASSMARK ENQUIRY message in order to ask the MS to send the UTRAN
CLASSMARK CHANGE message.
Rule :
earlyClassmarkSendingUTRAN = ”enabled”.
USE OF MEASUREMENT INFORMATION MESSAGE
The MEASUREMENT INFORMATION message is used for 3 different purposes:
• declaration of UTRAN neighbouring cells and configuration of UTRAN reporting
requirements
• activation/deactivation of EMR feature
The feature GSM to UMTS handover can be used with either normal measurement reporting
or enhanced measurement reporting. The part of the MEASUREMENT INFORMATION
message related to EMR feature activation is fully described in §4.6.6.
When the mobile does not have the UMTS FDD RAT capability, it shall not receive information
about UTRAN cells. As a consequence, the BSC sends two different version of Measurement
information to the BTS: a 2G version with GSM cell information only and a 2G/3G version with
both GSM and UTRAN cell information. The BTS then broadcasts the appropriate message
according to each mobile’s capability and according to the status of the “GSM to UMTS
handover” activation, as specified in the table below.
GSM to UMTS HO disabled GSM to UMTS HO enabled
EMR disabled EMR enabled EMR disabled EMR enabled
Release 4 2G onlymobiles
No MI message MI 2G message None MI 2G message
2G-3G mobiles No MI message MI 2G message MI 2G-3G message MI 2G-3G message
The 2G measurement information message (2G MI) contains mainly the following information:
• reportTypeMeasurement : parameter that defines the type of measurement report that
the mobiles are required to use
• common (EMR and non-EMR) reporting configuration parameters :
multiBandReporting
• EMR-specific configuration parameters : servingBandReporting,
servingBandReportingOffset
The 2G-3G measurement information message (2G-3G MI) contains mainly the following
information:
• reportTypeMeasurement : parameter that defines the type of measurement report thatthe mobiles are required to use
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• common (EMR and non-EMR) reporting configuration parameters :
multiBandReporting, qsearchC, fDDMultiRatReporting, fDDReportingThreshold2
• EMR-specific reporting configuration parameters : fDDReportingThreshold ,
servingBandReporting, servingBandReportingOffset
• UTRAN cells definition : mobileCountryCodeUTRAN, mobileNetworkCodeUTRAN,
locationAreaCodeUTRAN, rNCId, cId, fDDARFCN, scramblingCode, diversityUTRAN
NEIGHBOUR CELL LISTS
DEFINITION
The Neighbouring Cell List is built by a concatenation of two lists:
• The GSM Neighbour Cell List : it is the list of GSM cells, ordered by ARFCN and
BSIC, as defined in the BSIC_Description parameter of the
MEASUREMENT_INFORMATION message, which takes the first position in the list
• The 3G Neighbour Cell list: it is the list of UMTS cells, ordered by ARFCN &
scrambling code (the ARFCN are ordered the same way as received from the
network. For each ARFCN, scrambling codes are ordered in increasing number).
MAXIMUM SIZE
In this version the list is limited to 32 GSM cells and 32 UMTS cells.
When at least one UTRAN neighbouring cells is declared, only 31 different BCCH frequencies
for GSM neighbouring cells can be declared.
NEW BSS PARAMETERS
CREATION OF A NEW OBJECT
A new object is created alongside adjacentCellHandover: adjacentcellUTRAN.
2G-3G HANDOVER ACTIVATION : GSMTOUMTSSERVICE HO
PARAMETER
The following parameter (gsmToUMTSServiceHO) belonging to bsc object serves to
deactivate the 2G-3G Handover feature in all cells of the BSC or to provide a default GSM to
UMTS handover strategy when the MSC has failed to set one for the call :
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gsmToUMTSServiceHO value range :
• Shall not
• Should not
• Should
• GsmToUMTSDisabled
The MSC may include a similar “service handover” field in BSSMAP “ASSIGNMENT
REQUEST” and BSSMAP “HANDOVER REQUEST” messages sent to the BSS:
• Shall not: the BTS shall never hand off the communication to UTRAN (No UMTS
neighbouring cell can be present in the candidate cells list)
• Should not: the BTS shall not hand off the communication to UTRAN for a PBGT
reason but other criteria are nevertheless authorized to avoid call drop (handover for
alarm reason) or to reduce the load of the current cell when in congestion state
(handover for traffic reason)
• Should: It can be understood either as “immediate” or as “when possible or if
necessary”. The hoMarginUtran(n) parameter setting allows dual-mode MS to go
more or less easily on UTRAN layer. With a very negative values, the PBGT emulates
a capture in order to recover the UTRAN service as soon as possible.
For each call, we must differentiate the following cases :
• Case n°1 : gsmToUMTSServiceHO is set to GsmToUMTSDisabled.
Handover to UMTS is disabled.
• Case n°2 : "service handover" is provided by the MSC, and gsmToUMTSServiceHO
value is different from GsmToUMTSDisabled.
The MSC "service handover" value is sent to the BTS and the handover strategy is
decided by the MSC (according to OMC hoMarginXX setting).
• Case n°3 : "service handover" field is not provided by the MSC and
gsmToUMTSServiceHO is different from GsmToUMTSDisabled
Then, the default OMC "service handover" (i.e. the gsmToUMTSServiceHO
parameter) value is sent to the BTS and the handover strategy is decided by the
Access network instead of the Core network.
Note: In case the gsmToUMTSServiceHO is modified, the change only applies to new calls (or
after a handover) except for a feature deactivation.
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CONFIGURATION PARAMETERS OF CLASSMARK SENDING
The following parameter should be set to “enabled” to allow the mobile to send its UTRAN
Classmark at call setup :
• earlyClassmarkSendingUTRAN
The UTRAN_CLASSMARK_CHANGE message takes about 2 or 3 radio frames to transmit.
However, when supported by the UTRAN network, it is possible to reduce the size of the
message thanks to the compression of UE radio access capabilities and predefined
configuration Information Elements :
compressedModeUTRAN = enabled
Note: During IOT activities, it is recommended to disable this compression.
UMTS NEIGHBOUR CELLS DECLARATION PARAMETERS
The following 8 new parameters belonging to adjacentcellUTRAN object define the UMTS
neighbours :
• mobileCountryCodeUTRAN
• mobileNetworkCodeUTRAN
• locationAreaCodeUTRAN
• rNCId
• cId
• fDDARFCN
• scramblingCode
• diversityUTRAN
Up to 32 UMTS neighbours and 31 GSM neighbours may be declared.
MEASUREMENT REPORTING PARAMETERS
EMR must be activated for 2G-3G handover. The following 7 new parameters serve to
configure the Enhanced Measurement Reporting for 2G-3G handover purposes:
• reportTypeMeasurement
• qsearchC
• fDDMultiRatReporting
• fDDReportingThreshold
• fDDReportingThreshold2
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• servingBandReporting
• servingBandReportingOffset
2G-3G HANDOVER TIMER
t3121 has the same use as t3103 in the GSM inter-BSC handover procedure. It sets the value
before countdown of T3121 timer deined in the GSM specification:
• T3121 starts when the BSC sends an INTER SYSTEM TO UTRAN HANDOVER
message to the mobile.
• T3121 stops when the mobile has correctly seized the UTRAN channel. The purpose
of this timer is for the BSC to keep the old channels long enough for the mobile to be
able to return to the old channels.
• On expiry of T3121 (indicating the mobile is lost), the BSC may release the channels.
2G-3G HANDOVER THRESHOLDS
The following new parameters serve to configure thresholds :
• rxLevMinCellUTRAN
• rxLevDLPbgtUTRAN
These parameters have the same meaning as their counterparts on adjacentCellHandOver
object, but apply to a UTRAN neighbouring cell instead of a GSM neighbour cell.
2G-3G HANDOVER MARGINS
The following new parameters serve to configure margins for various types of handovers to 3G
cells :
• hoMarginUTRAN
• hoMarginAMRUTRAN
• hoMarginRxLevUTRAN
• hoMarginRxQualUTRAN
• hoMarginDistUTRAN
• hoMarginTrafficOffsetUTRAN
• offsetpriorityUTRAN
All these parameters have the same meaning as their counterpart on adjacentCellHandOver
object, but apply to a UTRAN neighbouring cell instead of a GSM neighbour cell.
In practice, all handovers algorithms except Capture and Directed retry are allowed towards
an UMTS neighbouring cell.
Note : the Power Budget handover as defined in GSM may be used to emulate a capture by
UTRAN layer.
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CONFIGURATION PARAMETERS OF PING-PONG MECHANISM FOR 2G-3G HANDOVERS
The existing mechanism to protect against ping-pong handover is used also for 2G-3G
handovers.
The list of outgoing causes for handovers towards UMTS neighbour cells is : traffic, pbgt,
rxLev, rxQual, dist, O&M (forced ho), all. This list is defined by setting the new parameter
hoPingpongCombinationUTRAN.
A specific timer is defined for time Rejection : hoPingpongTimeRejectionUTRAN .
If a pair of causes in the hoPingpongCombinationUTRAN parameter list refers to an incoming
or an outgoing cause that is not implemented in the source or in the target system, the existing
causes will be ignored.
On an incoming UMTS to GSM handover, if the BSC has not received the source "UTRAN
Cell identifier" (HANDOVER REQUIRED message / Old BSS to new BSS information"container / “Cell load information group” IE), no rejection timer will be started for that UTRAN
cell.
UMTS CELL LOAD MANAGEMENT
UMTS cell load management is managed three different ways:
• Through existing anti ping-pong mechanism for incoming 3G to 2G handovers
• Through a new mechanism for outgoing handover failures : When a UMTS cell rejects
the handover, the 2G-MSC sends a BSSMAP HANDOVER REQUIRED REJECT
message including cause “Traffic Load in the target cell higher than in the source cell”or “no radio resource available”. The BSC stores this information and does not attempt
a new handover towards this cell for a given time equal to
hoRejectionTimeOverloadUTRAN parameter.
• Through a new mechanism for incoming handover from UTRAN :
o if the handover cause in the BSSMAP HANDOVER REQUEST message is
either “traffic”, “directed retry” or “reduce load in serving cell” ,
o and if the source RNC and the MSC have implemented the “old BSS to new
BSS information” container
o and if the source RNC has included the “Cell load information group” withinthis container
o then the BSC stores the information and will not try a handover towards this
UTRAN cell for a given time equal to hoRejectionTimeOverloadUTRAN
parameter,
o otherwise, the BSC does not start any rejection timer for that UTRAN cell.
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SUMMARY OF HO 2G-3G PARAMETERS (V17)
Parameter name Definition object
cId Cell identity of the UMTS neighbouring cell for handoveradjacentCellUTRAN
compressedModeUTRAN
flag to indicate whether compressed mode UTRAN is supported ornot. This flag is used by the network to indicate to mobiles whether touse a compressed version of the INTER RAT HANDOVER INFOmessage (UE to UTRAN message).
bts
diversityUTRAN flag indicating whether there is deiversity in the neighbouring UTRANcell
adjacentCellUTRAN
earlyClassmarkSendingUTRAN flag indicating whether UTRAN classmark change message shall besent with Early Classmark Sending
bts
fDDARFCN fDD channel number of the UTRAN neighbouring celladjacentCellUTRAN
fDDMultiratReporting Number of FDD UTRAN cells to be reported in the list of strongestcells in the MR or EMR message
bts
fDDReportingThreshold (used in EMR only) defines the CPICH RSCP level above which theMS will apply a higher priority to UTRAN cells in the enhancedmeasurement report message
Handovercontrol
fDDReportingThreshold2 (used in MR and EMR) defines the CPICH Ec/N0 level above whichthe MS will report UTRAN cells in the normal or enhancedmeasurement report message
Handovercontrol
gSMToUMTSServiceHO This parameter serves to disable 2G-3G handover at BSC level or toindicate the preference (2G versus 3G cells) to be applied forhandovers
bsc
hoMarginUTRAN Handover margin for PBGT handover to a UMTS celladjacentCell
UTRAN
hoMarginAMRUTRAN Handover margin for intercell quality handovers to UMTS, for AMRcalls
adjacentCellUTRAN
hoMarginDistUTRAN handover margin for handover to UMTS on distance criterionadjacentCellUTRAN
hoMarginRxLevUTRAN handover margin for signal strength handover to UMTSadjacentCellUTRAN
hoMarginRxQualUTRAN handover margin for signal quality handover to UMTSadjacentCellUTRAN
hoMarginTrafficOffsetUTRAN offset to be subtracted to the homarginUTRAN to allow handover fortraffic reason when the current cell is congested
adjacentCellUTRAN
hoPingpongCombinationUTRAN list of pair of causes indicating the causes of ping-pong handovers inthe overlapping areas.
adjacentCellUTRAN
hoPingpongTimeRejectionUTRAN time that must elapse before attempting another handover towardsan UTRAN cell.
adjacentCellUTRAN
hoRejectionTimeOverloadUTRAN time that must elapse before attempting another handover towards acongested UTRAN cell
adjacentCellUTRAN
locationAreaCodeUTRAN Location area code of the UMTS neighbouring celladjacentCellUTRAN
mobileCountryCodeUTRAN Mobile country code of the UMTS neighbouring celladjacentCellUTRAN
mobileNetworkCodeUTRAN Mobile network code of the UMTS neighbouring celladjacentCellUTRAN
offsetPriorityUTRAN priority offset applied by the BSC when selecting the candidate cellfor the handover process
adjacentCellUTRAN
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Parameter name Definition object
qsearchC
search for UTRAN cells if signal level on the BCCH of serving cell :
is below threshold (0-7):
-98, -94, … , -74 dBm, ∞ (always)
or is above threshold (8-15):-78, -74, … , -54 dBm, ∞ (never)
If the serving BCCH frequency is not part of the BA(SACCH) list, andif the dedicated channel is not on the BCCH carrier, and if qsearchCis not equal to 15, the MS shall ignore the qsearchC parameter valueand always search for UTRAN cells. If qsearchC is equal to 15, theMS shall never search for UTRAN cells.
Handovercontrol
reportTypeMeasurement type of measurement report to be reported on this cell : enhancedmeasurement report or legacy measurement report
bts
rNCId identity of the UTRAN neighbouring cell’s RNCadjacentCellUTRAN
rxLevDLPbgtUTRAN downlink signal strength threshold above which handovers to UTRANfor cause power budget are inhibited
adjacentCellUTRAN
rxLevMinCellUTRAN minimum signal strength level that the MS must measure on anUMTS neighbour cell to be able to be granted a handover to thisUMTS neighbour cell
adjacentCellUTRAN
scramblingCode Scrambling code of the UMTS neighbouring celladjacentCellUTRAN
servingBandReporting defines the number of cells from the GSM serving frequency bandthat shall be included in the list of strongest cells in the measurementreport.
bts
servingBandReportingOffset
If there is not enough space in the report for all valid cells, the cellsshall be reported that have the highest sum of the reported value(RXLEV) and the parameter servingBandReportingOffset(XXX_REPORTING_OFFSET) for the serving GSM band. Note thatthis parameter shall not affect the value itself of the reportedmeasurement.
Handovercontrol
t3121
t3121 has the same use as t3103 in the GSM inter-BSC handoverprocedure. It sets the value before countdown of T3121 timer definedin the GSM specification .
T3121 starts when the BSC sends an INTER SYSTEM TO UTRANHANDOVER message to the mobile. T3121 stops when the mobilehas correctly seized the UTRAN channel. The purpose of this timer isfor the BSC to keep the old channels long enough for the mobile tobe able to return to the old channels if necessary. On expiry of T3121(indicating the mobile is lost), the BSC may release the channels.
bts
2G-3G HANDOVER ALGORITHMS
REPORTING QUANTITY
In the Enhanced Measurement Report message, the downlink received power level of UMTS
neighbouring cells may be reported by the mobiles using one of two possible reporting
quantities :
• either CPICH RSCP
• or CPICH Ec/N0
In our v17.0 implementation, the reporting quantity that mobiles are expected to report to the
network is always CPICH RSCP. The mobiles are informed of this obligation by the
FDD_REP_QUANT flag that is sent by the network on SACCH in Measurement Information
messages.
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MAPPING BETWEEN RSCP (3G) AND RXLEV (2G)
This CPICH RSCP value is directly comparable to a “classical” RxLev value.
According to the mapping specified in the GSM specification, we can define the following
conversion table between RSCP values and the reported values in range [0..63]. Values below
0 are reported as 0 and values above 63 are reported as 63 by the mobiles. The L1M then
subtracts 5 to the reported value to obtain the equivalent Rxlev signal strength.
RSCP (unit : dBm) Reported value inside EMR(no unit)
L1M converted value (nounit)
RxLev “equivalent” in dBm
RSCP<-120 0 0 <-110
-120<RSCP<-119 0 0 <-110
-119<RSCP<-118 0 0 <-110
-118<RSCP<-117 0 0 <-110
-117<RSCP<-116 0 0 <-110
-116<RSCP<-115 0 0 <-110
-115<RSCP<-114 1 0 <-110
-114<RSCP<-113 2 0 <-110
-113<RSCP<-112 3 0 <-110
-112<RSCP<-111 4 0 <-110
-111<RSCP<-110 5 0 <-110
-110<RSCP<-109 6 1 -110<RxLev<-109
… … … …
-54<RSCP<-53 62 57 -54<RxLev<-53
-53<RSCP<-52 63 58 -53<RxLev<-52
-52<RSCP<-51 63 58 -53<RxLev<-52
… … … …
-26<RSCP<-25 63 58 -53<RxLev<-52
-25<RSCP 63 58 -53<RxLev<-52
ALGORITHMS
Once the power level of all 2G and 3G neighbouring cells can be compared with one another,
all L1M handover algorithms are directly reusable.
For example, the algorithm for a Power Budget handover to UTRAN can be described as
follows :
• The MS listens to UTRAN cells if RxLev < qsearchC
• The MS reports the measured RSCP of the UTRAN cells for which CPICH Ec/N0 ≥
fDDReportingThreshold2
• The “service handover” shall be set to “should”
• The BTS discards UTRAN cells for which :
o either CPICH RSCP < rxLevMinCellUTRAN(n)
o or RxLev of the serving cell > rxlevDLPbgtUTRAN(n)
• PBGT handover decision is taken if :
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o CPICH RSCP(neighbour 3G cell) > RxLev (serving 2G cell) +
hoMarginUtran(neighbour 3G cell).
• UTRAN cells are sorted according to EXP2() values
IMPACT OF HO 2G-3G ON INTERFERENCE MATRIX
UMTS cells are not measured by the Interference Matrix feature.
EMR CASE
The introduction of UTRAN neighbouring cells has an impact on Interference Matrix feature
because of the number of GSM neighbour cells it induces.
If at least one UTRAN neighbour cell is declared, no more than 31 GSM neighbour cells can
be declared, instead of 32. The impacts on IM are the following:
• The algorithm that calculates the number of cycles (used by launching tool on OMC-R
and by BSC for cycle definition) shall be done with only 31 BCCH frequencies
• UTRAN neighbour cell creation must be forbidden if 32 different BCCH frequencies
are already declared for GSM neighbour cells
• GSM neighbour cell creation with a 32nd different BCCH frequency must be forbidden
if at least one UTRAN neighbour cell is declared.
• UTRAN neighbour cell creation, UTRAN neighbour cell deletion, fDDARFCN change,
scramblingCode change, must be forbidden while Interference Matrix feature isrunning on the BSC.
• the control that warns the operator if he tries to activate Interference matrix when one
cell has 32 GSM neighbouring cells (this control exists already in this case) must be
extended to the case where one cell has 31 GSM neighbouring cells and at least one
UTRAN neighbouring cell.
NORMAL MR CASE
Although fewer possibilities are available with MR than with EMR, the way GSM and UTRAN
neighbouring cells are reported in Measurement report messages is manageable, thanks to
multiBandReporting and fDDMultiratReporting parameters. Unlike EMR, the number of
reported non-serving band GSM and UTRAN valid neighbouring cells has an impact on the
number of remaining spare places in the Measurement report message that could be used for
fake neighbours in Interference Matrix.
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4.9. HANDOVER ALGORITHMS ON THE MOBILE SIDE
For an intracell handover, the mobile receives an ASSIGNMENT COMMAND and simply
switches to another timeslot belonging to any TDMA of the cell.
For an intercell handover, upon reception of the HANDOVER COMMAND, the mobile checks
if it has the synchronization information. If not a handover failure is reported and
communication remains on old channel.
Then, if it is a synchronized handover, four access bursts are sent on the new channel before
actually switching to it.
If it is a non synchronized handover, the mobile will send contiguous access bursts on new
cell, expecting a PHYSICAL INFORMATION message to be sent back by the BTS, in order to
know the Timing Advance to be used on the new channel and actually switch to it. If that
message is not received within one second, then there is a handover failure and the mobile
returns to the old channel.
Once on the new cell, the mobile tries to establish level 2 connexion (SABM and UA exchange
procedure). If that procedure fails, then the mobile returns to the old channel, but if it succeeds
the synchronization information with previous best cells is kept for updating with new cell
parameters.
To conclude this paragraph, one realizes that a handover can be a rather lengthy process,
which should not be performed too late in order to ensure its success and not too often to
maintain a smooth voice or data flow.
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4.10. POWER CONTROL ALGORITHMS
The aim of the Power Control feature is to reduce the average interference level on the
Network and to save mobile batteries.
4.10.1 STEP BY STEP POWER CONTROL
CAUTION!
In L1mV2, RxLevXX is always rescaled at the maximum power output (see chapter
Measurement Processing)
This algorithm is a step by step full path loss compensation. The algorithm determines the gap
between the received level at Pmax (theoretical maximum power without taking into account
Power Control) and the power control threshold (lRxLevDLP, lRxLevULP) and compensates
the path loss step by step until the received level reaches the threshold. That algorithm has
been improved in L1mV2 with the introduction of a limitation based on the one shot
computation when there is a need to re-compute the attenuation (high level and good quality)
The basic idea of the step by step power control algorithm is:
• to reduce transmitted power when reception level is high and quality is
good
• to compute a new transmitted power with total path loss compensation
when reception level is high and quality is good
At every runPwrControl event, the Weighted Average is computed at Pmax (SAveRxlev) and
the following algorithm is perfomed by Ms/Bs:
IF (SAveRxLev < lRxLevP) OR (SAveRxQual > lRxQualP)
NewAttRequestdB = Max (CurrentAttRequestdB - IncStepSizeXX, 0)
ELSE IF [(SAveRxLev > uRxLevP) AND (SAveRxQual < uRxQualP)]
TempAttRequestdB = SAveRxLev – lRxLevP
IF (TempAttRequestdB < CurrentAttRequest –IncrStepSizeXX)
NewAttRequestdB = CurrentAttRequestdB – IncStepSizeXX
ELSE IF (TempAttRequestdB > CurrentAttRequest + RedStepSizeXX)
NewAttRequestdB = CurrentAttRequestdB + RedStepSizeXX
ELSE NewAttRequestdB = TempAttRequestdB
ELSE ((lRxLevP ≤SAveRxLev ≤ uRxLevP) OR (uRxQualP ≤ SAveRxQual ≤ lRxQualP))
NewAttRequestdB = LastCommandedAttRequestdB
The resultfor the new attenuation request is stored into NewAttRequestdB
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The figure below summarizes the command for (UL or DL) transmission power according to
RxLev/RxQual values.
CAUTION!
When the MS or the BTS is in the “NEW TX POWER COMPUTATION” zone, the re-
computation of the attenuation does not lead necessarily to a reduction of the emitted power.
Note: This feature is activated at the BTS level by setting the following parameters:
• powerControl object: uplinkPowerControl = enabled and bsPowerControl =
enabled
• bts object: new power control algorithm = step by step
4.10.2 ONE SHOT POWER CONTROL
CAUTION!
In L1mV2, RxLevXX is always rescaled at the maximum power output (see chapter
Measurement Processing).
The enhanced power control is a one shot partial path loss compensation algorithm.
The one shot power control algorithm determines the “optimal” transmit power by computing a
partial path loss compensation and compensates it in one step.
This feature is activated at the BTS level by setting the following parameters:
• powerControl object: uplinkPowerControl = enabled and bsPowerControl =
enabled
• BTS object: new power control algorithm = one shot
RxQual
lRxQual
uRxQual
RxLevlRxLev uRxLev
Increase Tx Power
No new command for MS
(or BS) transmission power
New Tx Power computation
RxQual
lRxQual
uRxQual
RxLevlRxLev uRxLev
Increase Tx Power
No new command for MS
(or BS) transmission power
New Tx Power computation
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At every runPwrControl event, the Weighted Average is computed at Pmax (SAveRxlev) and
the following algorithm is perfomed by Ms/Bs:
IF (SAveRxLev < lRxLevP) OR (SAveRxQual > lRxQualP)
NewAttRequestdB = 0
ELSE
NewAttRequestdB = K * (SaveRxLev - lRxLevP)
The values of K depend on the activation of frequency hopping and of the RxQual. Here are
the values of K, which come from simulation results:
RXQUAL 0 1 2 3 4 5 6 7
K with Frequency Hopping 0,9 0,8 0,7
K without Frequency Hopping 0,7 0,6 0,5
The figure below summarizes the command for (UL or DL) transmission power according to
RxLev/RxQual values.
Please note that if NewAttRequestdB = 0 then the MS power becomes equal to the maximum
power possible in the cell, i.e. Min(msTXPwrMaxCell(n), MSTxPwrMax). The limitation can
come from the mobile (MSTxPwrMax) or from the cell (msTxPwrMax).
Concerning the BTS, the attenuation (difference between current power and max power) is
considered, so if NewAttRequestdB = 0 then the BTS power becomes equal to the maximum
static power possible.
RxQual
lRxQual
RxLevlRxLev
Tx Power max
(MS or BS attenuation = 0)
New Tx Power
computation
RxQual
lRxQual
RxLevlRxLev
Tx Power max
(MS or BS attenuation = 0)
New Tx Power
computation
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CAUTION!
An 8 dB limitation applies on decrease, e.g.the BTS will never decrease its power by more
than 8 dB (some mobiles would lose the BTS)
4.10.3 FAST POWER CONTROL AT TCH ASSIGNMENT
CAUTION!
In L1mV2, RxLevXX is always rescaled at the maximum power output (see chapter
Measurement Processing).
This feature is an improvement of the one shot power control (described above). One shot
power control reactivity is improved by deciding power control on SDCCH allocation and on
TCH allocation with only rxLevHreqaveBeg or rxQualAveBeg measurements. With this
feature, attenuation (possibly decided on SDCCH) is kept at TCH assignment and for each
channel switch-over (start on SDCCH, SDCCH to TCH or TCH to TCH), the few first
measurements (from Max[rxLevHreqAveBeg, rxQualAveBeg] to Max[rxLevHreqave *
rxLevHreqt, rxQualHreqave * rxQualHreqt]-1) may be used to decide power control.
This feature is activated by setting the following parameters:
• powerControl object: uplinkPowerControl = enabled and bsPowerControl =
enabled
• BTS object: new power control algorithm = enhanced one shot
The triggering of the one shot power control is accelerated because rxLevHreqaveBeg or
rxQualAveBeg measurements are taken into account.
Until Max[rxLevHreqave * rxLevHreqt, rxQualHreqave * rxQualHreqt] is reached, theattenuaton is computed with the compensation factor K for uplink and downlink. This factor no
more depends on the rxQualHreqave measurements but only on the frequency activation:
NewAttRequestdB = K * (SaveRxLev - lRxLevP)
• K = 0.5 in case of non hopping channel,
• K = 0.7 in case of hopping channel,
When Max[rxLevHreqAveBeg, rxQualAveBeg] > Max[rxLevHreqave * rxLevHreqt,
rxQualHreqave * rxQualHreqt] this feature is no more activated.
When Max[rxLevHreqave * rxLevHreqt, rxQualHreqave * rxQualHreqt] is reached the usual
average of the one shot power control described before is computed with the K value
depending of the rxQualHreqave measurements.
CAUTION!
This feature is not supported with DCU2 boards or with a mix of DCU2/DCU4 boards.
Note: In some very specific cases with a poor quality and a good level strength (very interfered
environment) the Fast Power Control algorithm may prevent from powering up after a TCH
assignment until max(rxLevHreqave*rxLevHreqt, rxQualHreqave*rxQualHreqt) is reached.
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4.10.4 POWER CONTROL ON MOBILE SIDE
In RACH phase, the MS power is equal to Min [msTxPwrMax, msTxPwrMaxCCH].
When the MS switches from RACH to SDCCH or TCH, it keeps the same power.
In dedicated mode, the mobile transmits at the power required in the POWER COMMAND
message transmitted in the layer1 header of SACCH blocks. This command will be received at
the end of a reporting period (102 frames in SDCCH, 104 in TCH). It will be applied at the
beginning of the following period at a rate of 2dB per 13 frames.
Before triggering an intercell handover due to uplink causes (RXQUAL or RXLEV) and only
step by step power control and for L1mV1 (only), the BTS should request the MS to transmit to
its maximum power capability. In such cases, if the MS can increase its transmit power, no
Handover Indication is transmitted by the BTS.
In the case of a handover, the maximum transmitted power allowed in the target cell is sent tothe mobile in the handover command message (msTxPwrMaxCell).
In case of intracell handover, the power reduction is kept.
The current txpwr value is saved so that it can be sent in the next transmitted uplink SACCH.
For the BTS, the duration of the entire process (from order to acknowledgment) is three
multiframes.
4.10.5 AMR POWER CONTROL
With the introduction of the AMR feature a new Layer 1 Management has been desgined to
take into account AMR channels specificity, including new algorithm for Power Control.
Please refer to section Power Control in the chapter AMR - Adaptative Multi Rate FR/HR.
SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3
BTS sends PC andTA
commands in a
SACCH block
MS gets the
SACCH block
MS starts applying
New PC and TA
One SACCH reporting period
26 * 4 = 104 frames (480 ms)
MS starts transmitting
SACCH concerning
Previous multiframe
BTS gets the
Measurement
Report
SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3
BTS sends PC andTA
commands in a
SACCH block
MS gets the
SACCH block
MS starts applying
New PC and TA
One SACCH reporting period
26 * 4 = 104 frames (480 ms)
MS starts transmitting
SACCH concerning
Previous multiframe
BTS gets the
Measurement
Report
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4.10.6 POWER ADAPTATION AFTER AN INTERZONE HO
This section is only applicable to RF power control in multizone cells (see
Concentric/DualCoupling/DualBand Cell Handover ).
PURPOSE
Before V17.0, after an inter-zone handover, the BSC sets the BTS and MS initial powers on
the new channel of the new zone to values that are identical to those used on the previous
channel in the other zone. As a result, the strength of the uplink and the downlink received
signal may decrease significantly on the establishment on the new channel. The risk is that the
handover could fail or the voice quality could deteriorate until the BTS has adjusted the BTS
and MS output TX power on the first run of the L1M power control process.
In v17.0, if the BSC expects the reception level to decrease following the interzone handover,
the BSC shall adapt the BTS and the MS output power, when activating the new channel, toensure a constant reception level for the MS and for the BTS. If on trhen other hand, the BSC
expects the reception level to increase, the BSC shall keep the BTS and MS power levels
unchanged and will simply wait for the L1M to adjust them via the standard power control
process.
ESTIMATION OF THE THEORETICAL POWER GAP
The BSC has to estimate the power gap in uplink and in downlink that would exist after an
inner to outer zone handover and an outer to inner handover :
• Delta_RxLev_DL_oz_to_iz : DL signal strength gap following an outer to inner HO
• Delta_RxLev_UL_oz_to_iz : UL signal strength gap following an outer to inner HO
• Delta_RxLev_DL_iz_to_oz : DL signal strength gap following an inner to outer HO
• Delta_RxLev_UL_iz_to_oz : UL signal strength gap following an inner to outer HO
This estimation depends only on the following O&M parameters :
• concentric_cell (bts object): parameter defining the type of multizone cell : concentric,
dualband or dualcoupling.
• zoneTxPowerMaxreduction (transceiverZone object): attenuation to be applied to
bsTxPwrMax (maximum theoretical level of BTS transmission power in a cell),
defining the maximum TRX/DRX transmission power in the zone.
• bizonePowerOffset (handoverControl object): Estimated downlink power offset
between inner zone and outer zone TRXs of a multizone cell. For a dual-band cell,
this parameter has to be estimated in a worst case (edge of band1 zone). For a
concentric or dualcoupling cell, bizonePowerOffset = zoneTxPowerMaxreduction
The 3 different cases of concentric cell give different resultrs for the power gap :
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Concentric Dual-coupling Dual-band
Delta_RxLev_DL_ oz_to_iz
ZoneTxPowerMaxReduction [oz]- ZoneTxPowerMaxReduction [iz]
ZoneTxPowerMaxReduction [oz]- ZoneTxPowerMaxReduction [iz]
ZoneTxPowerMaxReduction [oz]- ZoneTxPowerMaxReduction [iz] - bizonePowerOffset (
3)(
4)
Delta_RxLev_UL_
oz_to_iz
0(1) 0(
1) - bizonePowerOffset (
3)
Delta_RxLev_DL_ iz_to_oz(
5)
-(Delta_RxLev_DL_oz_to_iz) -(Delta_RxLev_DL_oz_to_iz) -(Delta_RxLev_DL_oz_to_iz)
Delta_RxLev_UL_ iz_to_oz(
5)
0(1) 0(
1) bizonePowerOffset
Notes :
(1) : for concentric and dualcoupling cells, there is no uplink signal strength gap. The uplink
gap only applies to dualband cells.
(2) : the type of coupler (D, H2D etc) does not impact the formula because the BTS takes the
coupling into account to reach the required output power which is equal to bstxpwrmax -zonetxpowermaxreduction. So it is the same formula as concetric cell.
(3) : The higher the frequency, the steeper the signal strength decrease as a function of MS-
BTS distance. “bizonePowerOffset” is a worst case assessment of this path loss performed at
the inner-zone boundary.
(4) : As both heterogeneous coupling and dual-band could be applied simultaneously to a cell,
zoneTxPwrMaxReduction must be taken into account in te downlink formula
(5) : We hold this truth to be self-evident, that the inner-to-outer zone power gap is the
opposite of the outer-to-inner zone power gap.
CORRECTION OF THE POWER GAP
Upon activating the channel in the destination zone, the BSC considers the relevant
theoretical power gap as well as the last BTS transmission power and MS transmission power
used on the channel of the initial zone. These are reported by the BTS to the BSC in the Abis
connection state ack message.
MS TRANSMISSION POWER ADAPTATION
As explained above, no power adaptation is required on the uplink for a Concentric cell or a
Dual-coupling cell.
In a Dual-band cell :
• if the uplink power gap is less than zero, this power loss shall be corrected with a
command sent to the MS to increase its transmission power
• if the uplink power gap is more than zero, the last MS transmission power level shall
be kept unchanged. However, the new MS transmission power level shall not be
allowed to exceed the maximum power allowed by the network and the maximum MS
output power allowed in that band.
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4.11. TCH ALLOCATION MANAGEMENT
4.11.1 TCH ALLOCATION AND PRIORITY
ALLOCATION AND PRIORITY (RUN BY THE BSC) (ALL_1)
Different priorities are defined in GSM to prioritise TCH resource usage for the different types
of procedures. Basically, GSM procedures can be divided into the following types:
• Assignment Request Messages: coming from MSC. It includes Public calls
and WPS calls. The only difference between the types of Assignment
Requests is basically the priority included in the message.
• InterBSC Handovers
• IntraBSC Intercell Handovers
• Directed Retry Handovers
• IntraCell Handovers: normal Intracell HO, small to Large zone, AMR, cell
tiering …
• TCH overflow cases: this includes different procedures in the signaling phase
when trying to get a resource SDCCH. If this one is not available, a resource
TCH will be requested instead.
For certain procedures like the handovers, where reactivity is crucial, it is important to
immediately have TCH resources available. This can be done by reserving some resources for
them. For other procedures like the Assignment Requests where the communication is not
established yet, it might be more interesting to allow the queuing of the requests for someseconds in order to gain access to the network even if it is a few seconds later. The reactivity
time in this last context is not as important as for the handovers. To be able to control this, a
priority system has been created.
Priorities can be divided into two different groups: external and internal. The BSC is in charge
of converting external priorities into internal ones. Conversion rules will be detailed.
Two kinds of external priorities, NSS external priorities and BSS external, can be defined:
• NSS external priorities are those included in the BSSMAP message coming
from the MSC. As only the Assignment Requests and the Handover Requests
(for interBSC HO) can generate this type of messages, these are the onlyprocedures having an external NSS priority.
• BSS external priorities are defined via OMC parameter settings. They are set
for all types of procedures, even for the Assignment Requests.
The type of external priority of the Assignment Request procedures taken for conversion to an
internal priority is depending on the value of another OMC parameter (bscQueuingOption) that
indicates if the mode is “MSC driven” or “OMC driven”.
The mode “MSC driven” means that it is the NSS external priority which is taken into account
for internal priority conversion of Assignment Request Procedures. For Handover Request and
TCH overflow, it is BSS external priority that is used for conversion.
The mode “OMC driven” means it is the BSS external priority which is taken into account for
conversion, whatever the procedure.
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CAUTION!
Note that if we are in “MSC driven” mode there might be different Assignment Requests
coming from MSC with different priorities, meaning that we could treat them differently
according to the type of call.
However, in “OMC driven” mode there is only one priority, set with a parameter, for all the
types of Assignment Requests. In particular, assignment requests with cause emergency call
are not differentiated from the other assignment requests.
At this point we can start introducing some of the main OMC parameters used for the TCH
allocation management:
ALLOCATION AND PRIORITY PARAMETERS
bscQueuingOption
bscQueuingOption = allowed bscQueuingOption = forced bscQueuingOption = not allowed
MSC driven mode
Queuing is allowed
NSS external priorities are takeninto account for AssignmentRequest.
BSS external priorities are takeninto account for handover requestand TCH overflow
OMC driven mode
Queuing is allowed
BSS external priorities aretaken into account for allprocedures
OMC driven mode
Queuing is not allowed
BSS external priorities are taken intoaccount all procedures.
allocPriorityTable
It is probably the most important parameter for the allocation priority management. It is used to
make the conversion between external and internal priorities and it consists of a vector
containing 18 values. The values can go from 0 to 12 and define the internal priorities
associated to the different procedures. The association between external and internal priority
is done using the index number (or slot number) in this table that goes from 0 to 17. The index
in the table represents the BSS external priority. When NSS external priority is used, in order
to convert into internal priority, we look in the slot NSS external priority - 1.
NSS external priority contained in the BSSMAP message can take a value from 1 to 14. Slots
1 to 5 are reserved for WPS call treatment.Example: allocPriorityTable = 0 8 9 10 11 12 2 2 2 2 2 2 2 2 3 0 4 2
Slot number 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
allocPriorityTable 0 8 9 10 11 12 2 2 2 2 2 2 2 2 3 0 4 2
With this example in MSC driven mode, for a BSS external priority = 16, the internal priority
defined is 4 and for a NSS external priority = 5, we have to look at the slot number = 5 – 1 = 4,
so the internal priority is 11.
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Interest of MSC driven mode is to allow distinction between assignment request and then the
possibility to set different priority for them (WPS calls, VIP users …).
CAUTION!
if WPS is activated, Slots from 1 to 5 are reserved for WPS priorities, as the assignmentrequest coming from the MSC for WPS requests can go from 2 to 6 (see chapter WPS -
Wireless Priority Service).
QUEUING DRIVEN BY THE BSC (ALL_3)
The OMC drive mode is enabled by the bscQueuingOption parameter set to “forced”.
In this mode queuing is used according uniquely to the priority defined with the BSS external
priorities (Slots from 14 to 17).
Queuing is managed by the BSC whatever queuing information coming from the MSC are. So
an assignment request priority is set accordingly to assignRequestPriority and the mapping
associated to in the allocPriorityTable.
CAUTION!
In this mode, WPS can not be efficient because resource allocation request queuing depends
on the type of operation only: thus the priority in the WPS assignement request is not
considered (see chapter WPS - Wireless Priority Service).
In the same way, assignment request with cause emergency calls cannot be differentiated in
this mode, and are treated with priority according to assignRequestPriority.
QUEUING PROCESS
Whatever the queuing mode is, a queue is defined by its size and the maximum waiting time
beyond which it is not allowed to queue the request anymore,. set by these two parameters:
allocWaitThreshold
This parameter is a 13 slot vector. The slot number (0…12) represents the internal priority
queues and the values define the maximum number of TCH allocation requests queued for
each internal priority. The last five slots set to 5 are reserved for WPS call treatment. These
values are accumulative, so the value for one queue represents the maximum number of
requests for that queue and all the queues with lower priorities. Note that the serving
preference for these queues has an increasing order, e.g. if there are two TCH allocation
requests waiting in two different queues, when a TCH resource is released, the request with
the lowest priority is served.
Slot number 0 1 2 3 4 5 6 7 8 9 10 11 12
allocWaitThreshold n 0 n n 0 0 0 0 5 5 5 5 5
n is the integer part of (number of SDCCH sub-channels in the cell)/2.
Note: that while the TCH request is queued it remains in a SDCCH sub-channel. A queue size
longer than the number of sub-channels SDCCH in the cell is so useless. On the other hand a
value closed to the number of SDCCH channels may cause an increase of SDCCH blockingrate due to the lack of SDCCH resources.
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allocPriorityTimers
This parameter is a 13 slot vector. The slot number (0…12) represents the internal priority
queues and the values mean the maximum waiting time (in seconds) in the queue of a TCH
allocation request for each internal priority. The last five slots set to 28 are reserved for WPS
call treatment.
Slot number 0 1 2 3 4 5 6 7 8 9 10 11 12
allocPriorityTimers 5 0 5 5 0 0 0 0 28 28 28 28 28
Note: a too long timer is unrealistic as an user will not wait indefinetely.
Sum up of the recommanded value
Slot number 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
allocPriorityTable 0 8 9 10 11 12 2 2 2 2 2 2 2 2 3 0 4 2
Internal priority /queue number
0 1 2 3 4 5 6 7 8 9 10 11 12
allocWaitThreshold n 0 n n 0 0 0 0 5 5 5 5 5
allocPriorityTimers 5 0 5 5 0 0 0 0 28 28 28 28 28
• procedures coming with an external priority 0 or 15 are associated to internal
priority and queue 0, but queuing is not allowed for intercell handovers
(system rule). In this configuration, only Emergency Call can be queued forthe external priority 0.
• internal priority and queue 1 are reserved for future use
• procedures coming with an external priority from [6 to 13] or 17 are associated
to internal priority and queue 2 and queuing is allowed
• procedures coming with an external priority 14 are associated to internal
priority and queue 3 and queuing is allowed
• procedures coming with an external priority 16 are associated to internal
priority and queue 4 but queuing is not allowed
• procedures coming with an external priority from [1 to 5] are associated to
internal priorities and queues [8 to 12] and queuing is allowed (if WPS
activated)
• internal priorities and queues [5 to 7] are not used
CAUTION!
• There is no queuing for TCH in “signaling mode” (TCH overflow).
• It is important to note that even if Directed Retry Handovers are associated to
an internal priority 2 queuing is not allowed for this type of procedure, as for
the other intercell handover procedures.
• Queuing set for procedures with internal priority 0 has been intentionally
configured for Assignment Requests cause “Emergency Call” (which shouldhave in this case a NSS external priority set to 1 if in MSC driven mode).
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Indeed, the only other procedures with priority 0 are intercell handover for
which queuing is forbidden.
• It is recommended to give different BSS external priorities for the Assignment
Requests and intracell Handovers in order to prioritise the queued allocationsfor Assignment Requests. This type of procedure is more sensitive from an
end-user point of view. A user not succeeding in the assignment request will
experience an establishment failure and have to re-establish the call, whereas
in the intracell Handovers, the call is already established and even in case of
Intracell Handover failure that does not necessarily mean a call drop. The
intracell Handover may be re-tried without a real end-user impact.
Below is the flowchart summarizing the TCH allocation handling if queuing is configured as
recommended in MSC driven mode:
Note: if directed retry handover is activated, another way of leaving the queue is a directed
retry handover. Refer to Directed Retry Handover for more details.
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4.11.3 BARRING OF ACCESS CLASS
On SYS INFO messages, the list of mobile access classes that can not start a call on the cell
is broadcast. Up to V8, this list is represented by the OMC-R parameternotAllowedAccessClasses. A feature allows the modification of what is sent on SYS INFO in
case of congestion.
CAUTION!
As the MS reads SYS INFO messages every 30 seconds in idle mode, there could be a time
window where non-authorized mobiles will still be allowed, e.g. if the MS did not read the
message before the cell selection, it could start a call.
DYNAMIC BARRING OF ACCESS CLASS (ALL_4)
The mechanism consists of temporarily forbidding cell access to some of the mobiles
(according to their access class) when a congestion situation is observed. The congestion
condition is based on:
• The number of free TCH channels.
Note that TCH resources reserved for maximum priority requests (internal
priority = 0) are not considered as free TCH channels.
The parameters are numberOfTCHFreeBeforeCongestion and
numberOfTCHFreeToEndCongestion .
or
• The number of queued requests in the cell.
The parameters are numberOfTCHQueuedBeforeCongestion and
numberOfTCHQueuedToEndCongestion .
The feature is enabled at bsc level by the attribute bscMSAccessClassBarringFunction, and at
bts level by the attribute btsMSAccessClassBarringFunction.
PRINCIPLE
In case of non-congestion, only the list of mobile access classes in notAllowedAccessClasses
is not allowed to select the cell.
In case of congestion, the list of mobile access classes in accessClassCongestion is not
allowed.
Congestion ? YESNO
notAllowedAccessClassesForbidden in the cell
accessClassCongestionForbidden in the cell
Congestion ? YESNO
notAllowedAccessClassesForbidden in the cell
accessClassCongestionForbidden in the cell
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CONGESTION DETERMINATION
To enter a congestion state, either the number of free TCH must be less than
numberOfTCHFreeBeforeCongestion or the number of queued TCH requests must be greater
than numberOfTCHQueuedBeforeCongestion.
To leave a congestion state, either the number of free TCH is greater than
numberOfTCHFreeToEndCongestion or the number of queued TCH request is less than
numberOfTCHQueuedToEndCongestion.
Example with a one TRX cell where one time slot is reserved for requests with an internal
priority equal to 0:
A congestion situation may be detected each time one of the following events occurs:• allocation of a TCH resource
• queuing of a TCH resource request
• blocking of a TCH resource (O&M action)
• TDMA removal for defense or O&M reason
• detection thresholds modification
End of congestion situation may be detected each time one of the following events occurs:
• release of a TCH resource
• a queued TCH resource request is served or aborted
• unblocking of a TCH resource (O&M action)
• TDMA attribution
• detection thresholds modification
Note: The overload state duration of a cell can be monitored thanks to the counter C1714, but
that counter is effectively reported to the OMC-R only if the load of the cell is taken into
account (i.e. only if hoTraffic = enabled at cell and BSC levels).
SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3
SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3
BCCH
BCCH
SA1 SA0 Free TCHUsed TCH
time
SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3BCCH
SA3reserved TS
for priority 0
T: TDMA enter in congestion
T+1: TDMA is still in congestion
T+2: TDMA gets out of congestion
numberOfTCHFreeBeforeCongeston = 1
numberOfTCHFreeToEndCongeston = 3
SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3
SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3
BCCH
BCCH
SA1 SA0 Free TCHUsed TCH
time
SA0 SA1 SA2 SA3 SA0 SA1 SA2 SA3BCCH
SA3reserved TS
for priority 0
T: TDMA enter in congestion
T+1: TDMA is still in congestion
T+2: TDMA gets out of congestion
numberOfTCHFreeBeforeCongeston = 1
numberOfTCHFreeToEndCongeston = 3
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V15.0 CHANGES OF DYNAMIC BARRING OF ACCESS CLASS (ALL_4)
The previous “access class barring” mechanism can be improved on 3 main points:
• The list of forbidden access classes is fixed, so the same customers are
always impacted.
• The number of barred access classes is fixed, so the number of barred
access classes may be insufficient.
• The mechanism is triggered on TCH allocation or release basis, but due to the
Erlang law (which induces sudden traffic modification) and because the MS
rereads the SYS INFO (only every 30 seconds), that mechanism could be
improved.
To ensure the functionning of the new mechanism, two levels of barring are created and run at
the same time:
• One level (low level) to provide point 1 and point 3
• One level (high level) to provide point 2
This feature is controlled by bscMSAccessClassBarringFunction on the bsc object and
btsMSAccessClassBarringFunction on the bts object.
HIGH LEVEL MECHANISM DESCRIPTION
To provide point 2, the number of access classes can be modified (additional or less) in order
to adapt to the length of congestion level. Once the cell enters in the congestion state, a
supervision timer is set, and every 3 minutes (system rule), an adaptation is made based on
the new cell congestion state:
• If the cell is still in the congestion state, 2 additional access classes are barred
(assuming they are not all barred)
• If the cell is not in the congestion state, 2 less access classes are barred (until
none are barred)
Once the cell is no longer in the congestion state, and if no access classes are barred, the
supervision timer (3 minutes) is stopped.
This mechanism is independent of the low level of barring mechanism.
Beginning of congestion:
3 minutes timer is setEnd of congestion :
3 minutes timer
is running
Congestion level
time
End of
congestion
Beginning of
congestion
[0 to 2]Number of access
classes barred [2 to 4] [4 to 6] [6 to 4] [4 to 2] [2 to 0]
No more classes
barred: 3 minutes
timer is stopped
3 minutes
Beginning of congestion:
3 minutes timer is setEnd of congestion :
3 minutes timer
is running
Congestion level
time
End of
congestion
Beginning of
congestion
[0 to 2]Number of access
classes barred [2 to 4] [4 to 6] [6 to 4] [4 to 2] [2 to 0]
No more classes
barred: 3 minutes
timer is stopped
3 minutes
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The barred access classes rotate inside the 3 minute time period according to the low level
mechanism of barring described below:
LOW LEVEL MECHANISM DESCRIPTION
Two parameters are important in this mechanism: the periodicity and the
accessClassCongestion parameter.
Periodicity: the congestion condition is still triggered on a TCH allocation or TCH release
basis, but once the congestion condition is triggered, a 60 seconds interval (system rule) is
used to periodically change which access classes are barred.
accessClassCongestion parameter: this parameter is a list of access classes which are
eligible to be barred during the congestion condition. The principle is that, during each 60
seconds interval of congestion, a different subset of access classes (and thus a different set of
mobile sets) may be barred. Access classes 11 to 15 are managed and can be automatically
barred if they are included in the accessClassCongestion parameter. They can not beautomatically barred if they are not in the accessClassCongestion parameter.
LOW AND HIGH LEVEL MECHANISM EXAMPLE
Let us take an example for the accessClassCongestion = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9].
Next time the cell is in congestion, since the last barred access classes are memorised in the
BSC, the new barred access class are the 2 followings in the list of access classes indicated in
the accessClassCongestion parameter.
In case the BSC12000 switchover, TMU reset for BSC3000 or lock/unlock of the cell, the first
barred access class is the first one in the list of access classes indicated in the
accessClassCongestion parameter.
In case the feature is turned off (cell or BSC level), the BSC sends immediately the system
information with notAllowedAccessClasses parameter included whatever is the cell congestion
status.
Beginning of congestion:
3 minutes timer is set
Congestion level
time
Number of access classes
barred
60 seconds3 minutes
Barred access classes [0,1] [2,3] [4,5] [6,7,8,9] [0,1,2,3] [4,5,6,7] [8,9]
[0 to 2] [2] [2] [2 to 4]
End ofcongestion
Beginning of
congestion
[4] [4] [4 to 2]
Beginning of congestion:
3 minutes timer is set
Congestion level
time
Number of access classes
barred
60 seconds3 minutes
Barred access classes [0,1] [2,3] [4,5] [6,7,8,9] [0,1,2,3] [4,5,6,7] [8,9]
[0 to 2] [2] [2] [2 to 4]
End ofcongestion
Beginning of
congestion
[4] [4] [4 to 2]
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In case the accessClassCongestion parameter is modified while the cell is in congestion, the
list of access classes to be barred will be re-evaluated on the 60s timer expiry, and on the 3
minutes timer expiry, the evaluation will be done on this new list (and not on the list of the
previous 3 minutes timer expiry).
NOTALLOWEDACCESSCLASSES PARAMETER MANAGEMENT
The following principle applies:
• In case of non congestion, only the list of mobile access classes in
“notAllowedAccessClasses” is not allowed to select the cell
• In case of congestion, the list of mobile access classes in
“accessClassCongestion” is not allowed.
Usually all users are authorized, and the notAllowedAccessClasses list is empty.
With the redefinition of the access class barring functionality, the management of the
notAllowedAccessClasses parameter is modified in the following way:
• In case of non congestion, only the list of mobile access classes in the
“notAllowedAccessClasses” parameter is not allowed to select the cell: there
is no modification compared to the previous management.
• In case of congestion, the accessClassCongestion parameter is used to
process access classes rotation on all the access classes listed in the
accessClassCongestion except on the access classes listed in the
notAllowedAccessClasses parameter, which remain barred during the
congestion.
Let us take the example for the accessClassCongestion = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] and
notAllowedAccessClasses = [3, 4].
This means, as described here above, that access class rotation will be done on the following
access class list = [0, 1, 2, 5, 6, 7, 8, 9] and that access classes 3 and 4 remain barred during
the congestion.
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4.11.4 RADIO LINK FAILURE PROCESS (RUN BY THE MS)
It is performed by the MS in dedicated mode on SACCH blocks.
RLC counter is initialized to radioLinkTimeout at the beginning of a dedicated mode.
IF good SACCH block
THEN RLC = Min[RLC+2, radioLinkTimeout]
IF bad SACCH block
THEN RLC = RLC - 1
If RLC reaches 0, then call is dropped and re-establishment is tried if reselection is made on a
cell with CallReestablishment set.
4.11.5 RADIO LINK FAILURE PROCESS (RUN BY THE BTS)
The FrameProcessor sets the CT counter to 0 at channel activation
On each correct SACCH:
IF good SACCH block AND IF (CT = 0)
THEN CT = 4*rlf1 + 4
ELSE CT = Min[4*rlf1 + 4,CT+rlf2]
IF bad SACCH block
CT = max(0,CT-rlf3)
If CT reaches 0, a connection Failure Indication is sent to the BSC every T3115, until a
Deactivate Sacch or RF Channel Release message is received.
This process is started when the first SACCH frame is received correctly, and the CT counter
is set according to rlf1 value. If SACCH frame is not received, then the radio link failure
process is not started, CT value is kept to zero and is not modificated.
Interest of the algorithm: the quality of an uplink communication is now considered for the
decision to cut a communication.
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4.11.6 CALL REESTABLISHMENT PROCEDURE
The call re-establishment procedure allows a mobile station to resume a connection in
progress after a radio link failure, possibly in a new cell and possibly in a new location area.
So this feature avoids losing calls, improving in that way the quality of service. Moreover, in
case of call drop, it reduces the SICD load by avoiding the subscriber to hang off and on.
The Call Re-establishment can be launched following 2 different procedures depending on the
entity which detects the radio link failure:
a) The radio failure is first seen at the MS side (RadioLinkTimeOut value):
The mobile sends a call-reestablishment on a selected cell (previous one or
new one) and the MSC re-allocate new resources. The old resources are
free by the BSS after the rlf1 timer has expired.
b) The radio failure is first seen at the BSS side:
The BTS send a radio_link_failure message to the BSC after rlf1 has
expired, the BSC releases the radio resources and in the same time the
MSC activates the t3109 timer and waits a call-reestablishment. Then, when
the MS has detected the radio link failure as well, it performs the selection
and sends a channel request on the selected cell.
To attempt a call re-establishment on a cell, the parameter callReestablisment of the cell will
be set to “allowed” and the cell will not be barred (see chapter Barring of access class).
The mobile station is not allowed under any circumstance, to access a cell to attempt call re-
establishment later than 20 seconds after it detects the radio link failure causing the call re-
establishment attempt.
The mobile station shall perform the following algorithm to determine which cell to use for the
call re-establishment attempt within 5 seconds max:
• The level measurement samples taken on the serving cell BCCH carrier and
on neigbhor cells carriers (carriers indicated in the BA (SACCH) received on
the serving cell) received in the last 5 seconds shall be averaged.
• The carried with the highest average received level is selected.
• On this carrier the MS shall attempt to decode the BCCH data block
containing the parameters affecting cell selection.
• If the parameter C1 is greater than zero call re-establishment shall be
attempted on this cell.• If the MS is unable to decode the BCCH data block or if the call re-
establishment is not allowed, the carrier with the next highest average
received level shall be taken, and the MS shall repeat steps 2) and 3) above.
• If the cells with the 6 strongest average received level values have been tried
but cannot be used, the call re-establishment attempt shall be abandoned.
Beware, during a re-establishment attempt the mobile station does not return to idle mode,
thus no location updating is performed even if the mobile is not updated in the location area of
the selected cell, however the mobile station will update its location area at the end of the call.
Generally a call re-establishment procedure lasts from 4 seconds to 20 seconds max.
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4.11.7 CALL CLEARING PROCESS (RUN BY BTS)
This process is used to drop calls with mobiles which are located too far away from a serving
cell and that may disturb other communications on adjacent time slots.
Every runCallClear:
IF (MS_BS_Dist > CallClearing)
THEN call needs clearing.
4.11.8 INTERFERENCE MANAGEMENT (BTS AND BSC)
All interference measurements performed by the BTS on the idle channels are performed in
Watts. Each sample is computed in Watt before being translated in dBm and sent to the L1M.
This method of calculation provides a result which is 2.5 dB higher than the one directly
performed in dB.
Every averagingPeriod, BTS computes Interference levels of idle channels (SDCCH and TCH)
according to the 4 defined thresholdInterference (resulting in 5 Interference ranges) and sends
this information to the BSC. It is therefore possible to monitor interference levels at the OMC.
The BSC will use RadChanSelIntThreshold parameter in order to sort available channels
according to their interference level. Thus the BSC will allocate channels using the following
priority:
• Hop and low_IF
• NoHop and low_IF
• Hop and (high_IF or just released)
• NoHop and (high_IF or just released).
Note: No interference level management is performed for PDTCH channel, Therefore the level
status of PDTCH resource is always high level (bad level).
4.11.9 UPLINK DTX
DTX is possible both downlink and uplink, but configuration and activation are uncorrelated in
the 2 mechanisms.
The uplink DTX feature is enabled when dtxMode parameter is set to “msShallUseDtx” (the
shall is dependent on the MS decision or capability.
When uplink DTX is activated on the network, MS gets the information from the BTS
(activation parameter). Then it is allowed to perform uplink DTX, i.e. to transmit
discontinuously only a subset of TCH bursts.
If the MS perform DTX on a call, the minimum number of transmitted bursts is 12 (out of 104
for a complete reporting period of 480ms).
The 12 bursts correspond to the 4 SACCH + 8 fixed positioned TCH bursts.
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4.11.10 DOWNLINK DTX
In the same way as the mobile, the BTS is able to transmit discontinuously (cellDtxDownLink
parameter, bts object).
The activation of downlink DTX follows depends on :
• authorisation for the BSS to use DL DTX, given by the MSC to the BSC at
assignment request, dynamically on a call-by-call basis
• The value of cellDtxDownLink parameter (bts object)
• The type of radio channel : voice half-rate, voice full-rate, cicuit data
• The values of certain bits in the bscDataConfig file (bits n°1, n°2 and n°3 of label 64)
MSC AUTHORISATION
On a call per call basis, the MSC may forbid the BSS to use Downlink DTX.
The MSC indicates this to the BSC by including a 1-bit long field called “DTX Downlink Flag”
inside BSSMAP Assignment Request (for call setup) or BSSMAP VBS/VGCS Assignment
Request (for group call setup, GSM-R only) or BSSMAP Handover Request (for incoming
external handover of a call coming from another BSS) :
- If “DTX Downlink Flag” is present and if DTX Downlink Flag = 1, then the MSC forbids the
use of DL DTX for that particular call
- If “DTX Downlink Flag” is absent or if DTX Downlink Flag is present and DTX Downlink
Flag = 0, then the MSC does not forbid the use of DL DTX for that particular call
In the second case, the decision to use DL DTX for that call is left entirely up to the BSS and
depends on BSS configuration parameters and the type of channel.
CELLDTXDOWNLINK
If cellDtxDownLink = disabled in the cell, then Downlink DTX is unconditionally turned off in
the cell for all types of call (voice and circuit-switched data).
So, cellDtxDownLink = enabled is a necessary condition to activate downlink DTX in the cell,
but it is not sufficient. It further depends on the type of channel (circuit data, voice half-rate,
voice full-rate).
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TYPE OF CHANNEL
CIRCUIT-SWITCHED DATA CHANNELS
DTX downlink is unconditionally turned off for circuit-switched data channels, even if
cellDtxDownLink = enabled.
Note : Bit n°1 of label 64 of bscDataConfigfile, called “DTX Downlink in data”, is not used any
longer in the software. Whatever its value, and whatever the value of cellDtxDownLink, DTX
Downlink is disabled for CS data channels.
FULL-RATE VOICE CHANNELS
If bit n°2 of label 64, called “DTX Downlink FR”, is equal to 1 : DTX Downlink is unconditionally
turned off for FR voice channels. This applies to all types of full-rate codecs supported by the
BSS : AMR FR, EFR and FR.If bit n°2 = 0, and if cellDtxDownLink = “enabled” in the cell, then downlink DTX is used on all
FR Voice channels, provided that its use has not been explicitly forbidden by the MSC at
assignment request stage.
By default, label 64 bit n°2 = 0 so by default DL DTX is activated for FR voice calls.
HALF-RATE VOICE CHANNELS
If bit n°3 of label 64, called “DTX Downlink HR”, is equal to 1 : DTX Downlink is unconditionally
turned off for AMR HR voice channels.
If bit n°3 of label 64 = 0, and if cellDtxDownLink = “enabled” in the cell, then downlink DTX isused on all AMR HR Voice channels, provided that its use has not been explicitly forbidden by
the MSC at assignment request stage.
By default, label 64 bit n°3 = 0 so by default DL DTX is activated for FR voice calls.
SUMMARY
The table below summarises the activation scenarios of DL DTX :
DTX DL flag(from MSC)
cellDtxDownLink
Label 64 bit1
Label 64 bit2
Label 64 bit3
DL DTX forCS data
DL DTX forFR voice
DL DTX forHR voice
1 any value any value any value any value disabled disabled disabled
0 or absent disabled any value any value any value disabled disabled disabled
0 or absent enabled 0 0 0 disabled enabled enabled
0 or absent enabled 0 0 1 disabled enabled disabled
0 or absent enabled 0 1 0 disabled disabled enabled
0 or absent enabled 0 1 1 disabled disabled disabled
0 or absent enabled 1 0 0 disabled enabled enabled
0 or absent enabled 1 0 1 disabled enabled disabled
0 or absent enabled 1 1 0 disabled disabled enabled
0 or absent enabled 1 1 1 disabled disabled disabled
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4.12. EMLPP PREEMPTION
4.12.1 PRINCIPLE OF EMLPP
DEFINITIONS
eMLPP priority : eMLPP priority associated to a call for preemption purposes. The BSC
transparently conveys eMLPP priority between the mobile and the NSS. The BSC does not
process this eMLPP priority.
NSS external priority (also known as BSSMAP priority) : priority associated to a call by the
NSS in the assignment or handover procedure. This priority is sent by the NSS to the BSS and
may then be used by the BSS for queuing or for preemption. Unlike the eMLPP priority, it is
transparent to the mobile.
BSS external priority : queuing priority defined via OMC parameter settings. Each type of
procedure is associated to a BSS external priority for queuing. This priority is used by the BSS
but it is strictly local, therefore the NSS and MS are not aware of it.
internal priority : this priority is local to the BSS. Therefore the NSS and MS are not aware of it.
It is an output of the allocprioritytable.
PRINCIPLE
eMLPP is an extension to GSM networks of the existing MLPP service for fixed lines.
eMLPP covers 2 basic aspects :
• Resource preemption for mobile originated or mobile terminated call establishment
procedures
• Called party preemption for mobile terminated calls
RESOURCE PREEMPTION
eMLPP allows the network to preempt resources from ongoing calls (circuits on the A interface
and/or radio resources in the BSS) to allocate them to an incoming call of greater priority :
o Preemption on the A interface is fully managed (decision and execution), on a per call
basis, by the NSS.
o Preemption on the Radio interface is executed, on a per call basis, by the BSS.
However, the decision to allow the preemption comes from the NSS because the NSS
is in charge of the Call Control procedures.
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• By the BSS in the PAGING REQUEST type 1, 2 ,3 messages sent to the mobile on
the PCH channel. The purpose of including eMLPP priority in paging requests is used
by mobiles who are engaged as listeners in a group call to decide to leave the group
call or not.
• By the NSS in the PAGING message sent to the BSS. The purpose of including
eMLPP priority in BSSMAP PAGING message is so that the BSS may include it in the
Paging Request (see previous bullet point)
• By the NSS in the SETUP message sent to the mobile for mobile-terminated call
establishment. It indicates to the mobile already engaged in a call whether to perform
called party preemption or not.
• By the NSS in the CALL PROCEEDING message by the network to the mobile. This
message is sent by the network to the calling mobile station to indicate that the
requested call establishment information has been received. In this message, the NSS
indicates to the mobile station the eMLPP priority level that the NSS has granted tothe call.
EMLPP SUBSCRIPTION
Two precedence levels are defined by subscriber and stored at the HLR:
• Subscriber’s Maximum Precedence Level. The subscriber may originate a call with a
precedence level up to his maximum precedence level
• Subscriber’s Default Priority Level. In the case no precedence level is sent in the “CM
service request” message, this level is used as the priority of the call
EMLPP PRIORITY SETTING AT MO CALL SETUP
For Mobile Originated point to point calls, the eMLPP priority precedence level is included
inside the CM SERVICE REQUEST message sent by the mobile to the network. Its value is
set as follows.
EMLPP SUBSCRIBER
The user may select an eMLPP priority value for the call. If he does not, the precedence is set
to its default value by the mobile.
The mobile checks that the priority is within the provisioned range.
The MSC validates the priority value, and possibly reduces it to the subscriber’s maximum
precedence stored in the VLR
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NON-EMLPP SUBSCRIBER
A default priority level is set by the MSC.
4.12.3 PREEMPTION ATTRIBUTES
OVERVIEW
Each call that comes into a BSC from the NSS (via ASSIGNMENT REQUEST or HANDOVER
REQUEST) has radio resource preemption capabilities, that have been allocated to it by the
NSS.
BSS Radio resource Preemption works as follows. In case of a lack of available radio
resources, the BSC is capable of allocating currently occupied resources to incoming calls that
have a preemption capability, by preempting resources of ongoing calls that are preemption-vulnerable.
Only TCH channels in dedicated mode, or PDTCH channels used for a CS call, are subject to
preemption.
The preemption mechanism of radio resources that is detailed here is based on the “BSSMAP
Priority” Information Element carried in ASSIGNMENT REQUEST or HANDOVER REQUEST
messages at the BSSMAP layer of the A interface. The BSSMAP priority is the input given to
the BSC by the MSC. The “BSSMAP Priority” Information Element contains preemption
attributes that are the result of the eMLPP functionality implementation in the NSS.
PREEMPTION ATTRIBUTES
The BSSMAP priority information element of a given call is optional and contained in
ASSIGNMENT REQUEST and HANDOVER REQUEST. It is sent by the NSS to the BSS, and
it provides the BSS with the eMLPP preemption capability of the call.
IF THE BSSMAP PRIORITY IS PRESENT
The BSSMAP priority information element is made up of the following 4 attributes : PCI, PVI,QA and Priority.
PCI: preemption capability indicator. The PCI attribute is a flag that specifies whether the call
is allowed to preempt another one or not. It is applicable while negotiating the allocation of
resources :
• PCI = 0 : this allocation request (resulting from assignment or handover) cannot
trigger the preemption procedure.
• PCI = 1 : this allocation request (resulting from assignment or handover) can trigger
the running of the preemption procedure.
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PVI: preemption vulnerability indicator. The PVI attribute is a flag that specifies whether the
call is allowed to be preempted by another call or not.
• PVI = 0 : this connection is not vulnerable to preemption.
• PVI = 1 : this connection is vulnerable to preemption.
QA: queueing allowed indicator. The QA attribute is a flag that specifies whether the call is
allowed to b a queueing procedure or not :
• QA = 0 : queuing is not allowed
• QA = 1 : queuing is allowed
PRIORITY : priority level. The priority attribute is an integer value in the range 1 ... 14 that
specifies the level that is applied to the call. Values 0 and 15 indicate “priority not used”.
It is built by the MSC thanks to a hardcoded lookup table that maps the eMLPP priority of the
call to the BSSMAP priority.
eMLPP priority value BSSMAP priority value
A (strongest priority) 1
B 2
0 3
1 4
2 5
3 6
4 (weakest priority) 7
IF THE BSSMAP PRIORITY IS ABSENT
If the BSSMAP priority is absent, the assignment request for that call is treated by the BSS as
though the flags were defined as follows :
• PCI = 0: no preemption capability;
• PVI = 0: no vulnerability;
• QA = 0: queueing not allowed;
• priority level = 0: no priority.
4.12.4 BSS RADIO RESOURCE PREEMPTION ALGORITHM
PROCEDURE
Definition : a vulnerable resource is a radio resource whose PVI is defined and equals 1.
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Upon receiving an ASSIGNMENT REQUEST or a HANDOVER REQUEST, the BSC follows
the following allocation algorithm :
• If there is an available radio resource, the BSC immediately performs the allocation
without invoking the preemption procedure;
• If there is no available radio resource :
o If PCI = 1 attribute is set for the request, and if a vulnerable resource (PVI = 1)
is available whose priority is strictly weaker than the request’s priority, the
BSC triggers the preemption procedure : the BSC starts the release of the
active call using this vulnerable resource and starts a specific internal timer
(Tpreempt).
If the release of the vulnerable resource is completed before expiry of
Tpreempt, or if another resource is freed up in the meantime, the
assignment is successful.
if Tpreempt expires before the resource is freed up, the preemption
procedure stops and the BSC declares an assignment failure. No
queuing or directed retry is attempted.
o If PCI is absent or if PCI = 0 or if no vulnerable resource exists or if the
weakest priority of the existing vulnerable (PVI =1) resources is at least as
strong as the request’s priority, the BSC does not start a preemption
procedure. Instead :
If allowed, the queuing and directed retry procedures are started,
Otherwise the BSC declares an assignment failure.
PREEMPTION TIMER
The preemption timer value Tpreempt is computed from T3111 timer ( t3111 parameter) as
follows:
Tpreempt = TdeactAck + (4 x T3111)
Tdeactack = 5 seconds (hard-coded).
VULNERABLE TCH SELECTION CRITERIA
The selection algorithm differs depending on the type of transceiver : DRX and DCU2. To
simplify, we assume that only DRX are used (not DCU2).
RANKING OF OCCUPIED TCH RESOURCES
To be considered a possible candidate for preemption by the BSC, a TCH must first fulfill the
following requirements :
o the TCH must be occupied by a FR voice call,
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o If the circuit data allocation request concerns the CSD 14.4 service and if the bts
object parameter data14-4OnNoHoppingTs = enabled, the preferred “busy TCH” pool
is the non-hopping one.
o If the circuit data allocation request concerns the CSD 14.4 service and if the bts
object parameter data14-4OnNoHoppingTs = disabled, the preferred “busy TCH” pool
is the hopping one (same a speech allocation request).
o If the circuit data allocation request concerns CSD services other than 14.4, the
preferred “busy TCH” pool is the non-hopping one(same a speech allocation request).
4.12.5 ACTIVATION PARAMETER
BSS Radio resource preemption must be authorised by a specific O&M parameter :
preemptionAuthor :
• Class 3
• signallingPoint object
• range : forbidden, authorizedWithRelease, authorizedWithForcedHO
preemptionAuthor = “forbidden” means that the BSC never performs radio resource
preemption, whatever the priority and PCI/PVI flags’ values.
preemptionAuthor = “authorizedWithRelease” means that the BSC is allowed to perform radio
resource preemption if necessary and if authorised by the MSC.A successful preemption
results in the preempted call being released.
preemptionAuthor = “authorizedWithForcedHO” means the same thing as preemptionAuthor =“authorizedWithRelease” in the current implementation, despite the different name.
4.12.6 EMLPP PREEMPTION VERSUS PDTCH PREEMPTION
PDTCH “preemption” consists in the BSC negotiating with the PCU to be allowed to use (to
“preempt”) a PDTCH for a CS call.
Although the same word is used, PDTCH “preemption” is not the same as eMLPP preemption.
In particular, PDTCH preemption is targeted on a chosen resource, whereas eMLPP
preemption is not.
PDTCH PREEMPTION
o The BSC receives an allocation request from the MSC
o The BSC chooses a radio resource for that particular allocation request.
o If the chosen resource is a PDTCH, the BSC starts the preemption negotiation with
the PCU. No other resource can be used instead, even if a TCH is freed in the
meantime.
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EMLPP PREEMPTION
o The BSC receives an allocation request from the MSC
o The BSC chooses a preemptable radio resource and starts the release of the call
currently using that resource.
o In parallel, while the preemption procedure is ongoing, the BSC puts the allocation
request that was the cause of the preemption inside a special queue entirely
dedicated to preemption-capable allocation requests.
o The first radio resource that becomes available is allocated to the preemption request
that is at the front of the queue. Therefore the radio resource that was preempted
originally is not necessarily allocated to the request which initially triggered that
particular preemption.
4.12.7 INTERWORKING
HANDOVER
During handover procedures, preemption in best cell is always preferred than fallback to
another one. Preemption leads to favour attempting to obtain a radio resource in the first cell
of the handover list (ensures better quality, but may cause additional delay to the handover
procedure completion), even though a radio resource may be immediately free in a further cell
in the list.
DIRECTED RETRY
If preemption is authorised (i.e. preemptionAuthor = “authorizedWithRelease”), and if no
resource is free, the BSC first looks to see, based on the PVI flag and the relative BSSMAP
priorities, whether a resource could be preempted.
If so, the BSC starts the preemption procedure. Then, either the preemption (and the
assignment) succeeds, or the BSC returns an assignment failure. Directed Retry cannot be
attempted as a fallback.
Therefore, Directed retry may be attempted only after the BSC has decided not to trigger thepreemption procedure (due to lack of potential candidate resources, e.g. PVI of all TCH = 0).
QUEUING
As for Directed retry, queuing may be attempted only after the BSC has decided not to trigger
the preemption procedure (due to lack of potential candidate resources, e.g. PVI of all TCH =
0). To solve a congestion issue, preemption is always considered first by the BSC. If a
preemption procedure is started and if it fails, queuing may not be attempted as a fallback : the
assignment request results in an assignment failure.
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Also, the BSS priority table (allocPriorityTable) is not used by the BSS in the preemption
procedure. Only the external BSSMAP priority given by the MSC is considered by the BSC in
the preemption algorithm, regardless of the corresponding internal priority given by the BSS
priority table.
RESERVED RADIO RESOURCES
Reminder : it is possible to reserve radio resources to assignment requests of internal priority
= 0 thanks to the allocPriorityThreshold parameter. When the number of free resources falls
below allocPriorityThreshold , these remaining free resources may only be allocated to
assignment requests of internal priority = 0.
Even preemption-capable assignment requests cannot use these free timeslots if the value of
their internal priority is different from 0. They have to preempt ongoing calls on other timeslots
and leave these reserved timeslots free.
4.12.8 RESTRICTIONS
Network resources (both radio channels and fixed circuits) used by emergency calls (TS12
service) may not be preempted.
SDCCH channels may not be preempted.
The following TCH channels may not be preempted :
o TCH channels used for signalling (TCH overflow)
o TCH channels used for HR calls
All other TCH, including those used for data calls, are preemptable provided that PVI = 1.
In the very first phase of a mobile originated call establishment, in case there are no SDCCH
and no TCH available, a Channel Request is not capable of triggering a preemption.
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transmit paging messages for the paging group A. This space is necessary to locate several
paging groups.
This parameter is deeply involved in the time needed to establish a call when a paging
message is coming. For instance, if a paging command is to be transmitted in a paging group
P1 just after the paging group P1 occurrence, the paging command will have to wait for at
least noOfMultiframesBetweenPaging x 240ms to be transmitted.
If noOfMultiframesBetweenPaging = 8, the time waited to transmit a paging message can be
of 2 seconds without any other delays.
From the configuration, paging group occurences are determined. In the previous example,
the paging groups will be split as follows:
Nb of Paging groups = (na - nb) x nc
• na = number of CCCH groups per BCCH multiframe• nb = noOfBlocksForAccessGrant
• nc = noOfMultiframesBetweenPaging
Note: see chapter Paging Parameters for more information on this parameter recommended
values.
noOfMultiframesBetweenPaging has also an influence on mobile battery consumption and on
reselection reactivity (see chapter Effects of “noOfMultiFramesBetweenPaging” on Mobile
Batteries and Reselection Reactivity).
4.13.2 PAGING COMMAND REPETITION PROCESS (RUN BY BTS)Paging messages are systematically repeated. Three (3) parameters will manage paging
message repetitions:
• nbOfRepeat
defines the number of times a paging message will be repeated by the BTS
• delayBetweenRetrans
defines the number of occurrence between 2 repetitions of the same paging
group
• retransDuration
defines the maximum time allocated to broadcast a paging message
B C
C H
B C
C H
B C
C H
B C
C H
F C
C H
S C H
F C
C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C
C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C
C H
S C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
I D
L EBlock
bookedfor AGCH
Paging
groupnb0 (A)
Paging
groupnb1
B C C H
B C C H
B C C H
B C C H
F C C H
S C H
F C C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C C H
S C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
I D L EBlock
booked
for AGCH
Paging
group
nb2
Paging
group
nb3
B C C H
B C C H
B C C H
B C C H
F C C H
S C H
F C C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C C H
S C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
I D L EBlock
booked
for AGCH
Paging
group
nb0 (A)
Paging
group
nb1
FN0
FN1
FN2
F C
C H
S C H
F C C H
S C H
F C C H
S C H
B C
C H
B C
C H
B C
C H
B C
C H
B C
C H
B C
C H
B C
C H
B C
C H
F C
C H
S C H
F C
C H
S C H
F C
C H
S C H
F C
C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C
C H
S C H
F C
C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C
C H
S C H
F C
C H
S C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
I D
L EBlock
bookedfor AGCH
Paging
groupnb0 (A)
Paging
groupnb1
B C C H
B C C H
B C C H
B C C H
B C C H
B C C H
B C C H
B C C H
F C C H
S C H
F C C H
S C H
F C C H
S C H
F C C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C C H
S C H
F C C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C C H
S C H
F C C H
S C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
I D L EBlock
booked
for AGCH
Paging
group
nb2
Paging
group
nb3
B C C H
B C C H
B C C H
B C C H
B C C H
B C C H
B C C H
B C C H
F C C H
S C H
F C C H
S C H
F C C H
S C H
F C C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C C H
S C H
F C C H
S C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
S D C C H
F C C H
S C H
F C C H
S C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
S A C C H
I D L EBlock
booked
for AGCH
Paging
group
nb0 (A)
Paging
group
nb1
FN0
FN1
FN2
F C
C H
S C H
F C
C H
S C H
F C C H
S C H
F C C H
S C H
F C C H
S C H
F C C H
S C H
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The following rule is checked at the OMC-R:
retransDuration > (delayBetweenRetrans + 1) x nbOfRepeat
This inequality is to insure at least nbOfRepeat paging transmissions when there is no
blocking on paging channel.
See chapter Paging Parameters and chapter GSM Paging Repetition Process Tuning to find
engineering rules to set these parameters.
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4.13.3 REQUEST ACCESS COMMAND PROCESS
RACH are used when mobiles request a channel to establish a communication (both
terminated and initiated calls, see chapters Mobile Terminating Call and Mobile Originating
Call). Request management is configurated (nb of repetitions, time between repetitions...) at
the OMC-R thanks to different parameters.
4.13.4 REQUEST ACCESS COMMAND REPETITION PROCESS
After sending the initial CHANNEL REQUEST message, the MS starts a timer (T3120) and
listens to AGCH logical channel. When this timer expires and number of retransmissions does
not exceed maxNumberRetransmission , the MS repeats the CHANNEL REQUEST.
See also chapter GSM Paging Repetition Process Tuning.
PHASE 1 MOBILES
When the timer is started, a random value n is drawn with equal probability between 0 and N-1
where N is:
• for the initial access: max (8, numberOfSlotsSpreadTrans)
• for next attempts: numberOfSlotsSpreadTrans
T3120 is set so that there are n RACH slots between T1 and the expiry of T3120. T1 is a fixed
delay thanks to the configuration of the BCCH:
• before initial access, T1 = 0
• after initial access, T1 = 250 ms (for non combined CCCH)
• after initial access, T1 = 350 ms (for combined CCCH)
time
Fixed delay whose
value depends on
whether or not the
BCCH is combined
Variable delay from 0 to
numberOfSlotsSpreadTrans – 1
RACCH
time
Fixed delay whose
value depends on
whether or not the
BCCH is combined
Variable delay from 0 to
numberOfSlotsSpreadTrans – 1
RACCH
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PHASE 2 MOBILES
Rec 04.08 have been modified to avoid double allocation (see chapter Paging Parameters).
When the timer is started, a random value n is drawn with uniform probability distribution in the
interval [S, S+1, ..., S+T-1]:
• where T is numberOfSlotsSpreadTrans
• where S depends on the BCCH configuration and on T (see following table).
numberOfSlotsSpreadTrans S on non-combined BCCH S on combined BCCH
3, 8, 14, 50 55 41
4, 9, 16 76 52
5, 10, 20 109 58
6, 11, 25 163 86
7, 12, 32 217 115
4.13.5 I MULTIPAGING COMMAND MESSAGE
The multipaging command message is a Nortel Specificity. The principle of this
implementation is to form group of paging on the Abis interface. Before BSS V14.3.1, for each
paging message receives from the MSC; one paging message is sent on Abis interface to a
target cell.
The aim of this feature is to reduce the congestion and overload messages on Abis interface.
In order to achieve this goal, a new BSC timer Called T_Paging_Group was introduced, to
define the minimum of time between two occurrences of multi paging command messages on
Abis interface.
Therefore, at emission of one multi paging command message, the BSC starts
T_Paging_Group.
If during T_Paging_Group, more than 10 paging messages are received, then only the 10
first messages are stored, thus others messages are discarded.
time
Fixed delay whose
value depends on
BCCH configuration and
numberOfSlotsSpreadTrans
Variable delay set according to
numberOfSlotsSpreadTrans
time
Fixed delay whose
value depends on
BCCH configuration and
numberOfSlotsSpreadTrans
Variable delay set according to
numberOfSlotsSpreadTrans
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At T_Paging_Group expiry, either no paging message is received from the MSC or at least
more than one paging message is stored and the BSC sends these messages to the BTS.
In both cases the BSC restarts the timer.
Note: The maximum length is 12 paging messages.
A multi paging command is sent by the BSC in two cases:
• As soon as the 12 first paging are received by the BSC, a paging group
message is sent to the BTS leading to avoid discarding paging messages
and waiting for T_Paging_Group timer expiry.
• If T_Paging_Group timer is reached and at least one paging message is
received, a multi paging command is sent
Caution!
The value of this T_Paging_Group is set to 200ms. Only CS paging use I Multipagingcommand, therefore the PS pagings are not combined. Thus a single paging I is used for data
paging.
The following figure illustrates the principles of multipaging command
The two major improvements bring by this feature are:
• a large Lap D bandwidth associated to the BCCH for non-paging messages,
which provides a better quality of service,
• a reduction of the CPU load generated by paging messages at BSC and BTS
levels.
However, it induces a delay (average=100ms, min=0ms, max=200ms) during the paging
management at the BSC level, and the mobile terminated call setup time is lightly increased.
CAUTION!
Note: As this feature increases the BSS capacity, since BSS V14.3.1 it is activated by default.
Pa in MS4
BTS
BSCMSC
Paging MS1
Multi paging command
T_Paging_groupPa in MS2
MS1, MS2, MS3
Pa in MS3
T_Paging_group
Multi paging command
MS4
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4.13.6 UI MULTIPAGING COMMAND MESSAGE
PRINCIPLE
Each time a data request message (I frame on LapD) is used to convey a multipaging
message to the BTS, the BSC has to wait for an acknowledgement before sending the
next multipaging message. Therefore, the paging process is RTD dependent.
Using the Unit Data Request message (UI frame on the LapD), no acknowledgement
is required before sending the next frame, which decreases the lapd bandwidth
associated to the BCCH TRX for paging messages.
Hence, whatever is the paging number per second, the quality of service is increased
and more especially in case of large location area which generates high number ofpaging messages or during exceptional events.
This feature is introduced in V15.1.1 and it allows, at equivalent paging messages
number, to better fill the downlink lapd bandwidth associated to the BCCH for paging
messages and to decrease the use of the uplink lapd bandwidth. Hence it increases
the lapd bandwidth associated to the BCCH for non-paging messages.
SPECIFICATIONS OF THE UI MULTIPAGING COMMAND MESSAGE
UI Multipaging command message uses the same mechanisms (to group the paging
command messages) as the I Multipaging command message described in below
except the ones described here under.
In order to build the UI Multipaging message, the BSC timer T_Paging_Group is
used, which defines the maximum time between 2 occurrences of UI Multi Paging
Command message on the Abis interface.
The BSC starts T_Paging_Group at emission of one UI Multi Paging Command
message.
Until T_Paging_Group expiry, as soon as a MultiPaging command message has
stored 12 unit paging command messages, it is transmitted immediately to the BTS.
At T_Paging_Group expiry, if one or more than one paging command messages arecurrently stored:
• the MultiPaging command message is transmitted to the BTS and
T_Paging_Group timer is restarted
• otherwise T_Paging_Group timer is restarted
Hence, all paging requests messages accepted by the BSC filter are all sent to the
BTS which means up to 105 paging command / second.
Note: The value of this T_Paging_Group is set to 200ms and can not be modified
even via the bsc data config tool.
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The Packet paging message, received from the PCU, are sent by the BSC to the BTS
(on the SAPI GSL) whereas the Circuit paging message from MSC are sent to the
BTS by the BSC on the SAPI RSL. Therefore PS and CS pagings are not sent into the
same multipaging message command.
With I multipaging command message the process of combining paging messages
into one multipaging command message is supported by CS paging only.
The restriction is removed with UI multipaging command feature as it allows
combining the packet paging messages before sending them to the BTS.
FEATURE ACTIVATION
The feature is deactivated by default and can be activated thanks to a build on line.
Recommended upgrade steps are the following:
• Upgrade of the BSC without activation of the UI MultiPaging feature (type 4)
• Upgrade of the BTS supported by the BSC
• Activation of the UI Multipaging feature in the BSC (via a build on line)
CAUTION!
In order to identify bad PCM links and fix it, the operator should monitor the quality of
all the PCM links before the feature activation.
As soon as the BSCe3 and the TRXs of BTS are able to manage this feature, the BSC
sends UI MultiPaging Command messages.
The BSC is aware of the BTS capacity for the Circuit Service thanks to the DRX
catalog file and especially the bit 8 (from 0 to 31) of the hardware mask defined as
follow:
• 0: UI MultiPaging Command message for Circuit Service not supported
• 1: UI MultiPaging Command message for Circuit Service supported
As all types of DRX support this feature (except DCU2), there is no modification of the
"display all" feature, in order to know the activation state of this feature.
Note: As this feature is not implemented on BSC12000 and due to upgrade
constraints, then the BTS has to manage the following types of paging messages: I
paging command, I MultiPaging and UI MultiPaging command messages.
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4.13.7 NETWORK MODE OF OPERATION I SUPPORT IN BSS
The Network Mode of Operation 1 (NMO1) takes benefit of the Gs interface to exchange
messages between the MSC and SGSN in order to coordinate the CS and PS paging
management and to optimize some signaling procedures.
Note that Gs interface (between SGSN and MSC) is a pre-requesite before using NMO1.
The feature should be enabled with gprsNetworkModeOperation (bts object). The parameter is
at BTS object but must be consistent at Routing Area level, i.e. activated (or de-activated) in
all cells of a given Routing Area.
PAGING MANAGEMENT
If NMO1 is activated, CS-Paging are managed through Gb interface for any GPRS-attached
MS. ClassB MS may be simultaneously attached to GSM and GPRS services but cannot
simultaneously perform CS and PS transfer.
If the MS is not attached to GPRS services, the CS-Paging procedure is not modified and
done through the A interface.
If the MS is attached to GPRS, the CS-Paging is sent from the MSC to the SGSN (Gs
interface) and then to the PCU (Gb interface):
• If the target mobile is in GMM STANDBY state, the PCU transmits the Paging
message to the BSC on the SAPI RSL. Therefore the BSC has to broadcast
this message on the CCCH of all target cells.
• If the mobile is in GMM READY state, the PCU sends the Paging on the
PACCH of the TBF or on the CCCH of the cell if there is not an established
TBF for the target mobile. In case Paging is sent on PACCH, the PCU repeats
the paging message 3 times (1 emission + 3 repetitions), with a delay
between 2 occurrences equal to 480 ms. This enhances the probability of
success of the Paging procedure.
The 3 different cases (MS not GPRS-attached, MS in GPRS STANDY state and MS in GPRS
READY state) are illustrated below.
Note that the load of some interfaces is impacted by NMO1 activation:
• less paging on A interface less load on A interface.
• more paging on AGPRS interface more load on AGPRS LAPD TS.
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COMBINED SIGNALING PROCEDURES
Two procedures are combined when using NMO1:
• Combined GSM / GPRS Attach
• Combined LA / RA update.
Each procedure is performed with a single access on packet channels. This is transparent for
the PCU, which manages it as usual without any particular action. The SGSN then informs the
MSC through the Gs inteface.
The following gains are expected:
• decrease of SDCCH occupancy
• less load on A and Abis interfaces
• less load on BSC
• faster cell reselection between 2 LA.
Notes:
• As the combined procedures are performed on packet channels, it is critical to
protect the access to GPRS service and thus set minNbrGprsTs > 0
• There is a LAPD impact on Agprs interface due to the addition of cs_paging
messages for the data attached mobiles.
MSC/VLR
BSC
BTSBTS BTS BTS
SGSN
PCU
MSC/VLR
BSC
BTSBTS BTS BTS
SGSN
PCU
MSC/VLR
BSC
BTSBTS BTS BTS
SGSN
PCU
MS not attached to
GPRS services
Paging procedure not
modified
MS attached to
GPRS services &
standby state
MS attached to
GPRS services &
ready state
BSC broadcasts paging
on CCCH
Paging on:
• PACCH if TBF established
• CCCH if no TBF established
MSC/VLR
BSC
BTSBTS BTS BTS
SGSN
PCU
MSC/VLR
BSC
BTSBTS BTS BTS
SGSN
PCU
MSC/VLR
BSC
BTSBTS BTS BTS
SGSN
PCU
MS not attached to
GPRS services
Paging procedure not
modified
MS attached to
GPRS services &
standby state
MS attached to
GPRS services &
ready state
BSC broadcasts paging
on CCCH
Paging on:
• PACCH if TBF established
• CCCH if no TBF established
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4.13.8 BSS CS PAGING COORDINATION
For details please refer to the functional note ([R57] and also to the aPUG document ([A1]).
PRINCIPLE
When NMO II is used, the network sends all paging messages on the PCH paging channel
even if the mobile has been assigned a packet data channel, which might require the MS to
leave the packet channel to monitoring the occurrence of paging messages. Compared to
NMO II, the BSS CS Paging Coordination is an additional mechanism for handling CS paging.
It provides an NMO I-like mechanism (BSS CS Paging Coordination) without involving the
packet core and Gs interface. This maximizes the end-user availability for receiving CS calls
and the related revenues.
While the network is running with NMO II, the BSC sends all CS paging messages received on A interface both to the BTS and, with BSS CS Paging Coordination feature activated, to the
PCU as well. The PCU then checks whether the corresponding MS is engaged in a PS
session, by checking the IMSI. If so, the PCU sends the CS paging message to the mobile on
PACCH channel.
BSS CS PAGING COORDINATION MECHANISM
ACTIVATION PARAMETER
The activation parameter of this feature is bssPagingCoordination (class 3, bts objet).If the network is running in Network Mode of Operation II and if BSC and PCUSN support the
BSS CS Paging Coordination feature, the bssPagingCoordination parameter serves to set
BSS_PAGING_COORDINATION bit in GPRS Cell Options to “1” to enable the BSS CS
Paging Coordination mechanism for all GPRS/EDGE mobiles.
Therefore, the behaviour of class B mobiles (from Release 97) is modified when enabling this
new BSS CS Paging Coordination in the network, provided that both the BSC and the PCUSN
support the feature.
SI13 UPDATE
The BSC updates the System Information 13 message to indicate the activation/deactivation
of the feature and sends PCU BROADCAST INFO MODIFY to provide the updated content of
the SI13 to the PCU.
DETAILED PAGING COORDINATION MECHANISM
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If the network is running in Network Mode of Operation II, when the BSC receives a CS paging
from A interface :
• the BSC broadcasts this paging message in the target cells (as it has always done so
far), regardless of bssPagingCoordination parameter value,
• and, if bssPagingCoordination is enabled on at least one cell of the area, the BSC
sends the paging message in a single BSC CS Paging message to the PCU (even if
the CS paging addressee is a list of cells) on one of the available Agprs PCM (with a
round-robin mechanism to spread the CS paging load on all Agprs PCMs connectedto this BSC).
When a PCU element receives a CS paging on its Agprs PCM, it broadcasts this message to
all PCU elements connected to the same BSC that issued the CS paging message. Each PCU
element then checks whether the IMSI value included in the BSC CS Paging message
corresponds to one of the existing MS context (i.e. a mobile that is known as currently having
an established TBF). In this case :
• if the bssPagingCoordination parameter is set to “enable BSS paging coordination” in
the corresponding cell, the PCU sends the CS paging on PACCH using the
mechanism used for Network mode of Operation I (see §4.13.7).
• otherwise the paging is discarded.
CS pages onCCCH
MSC/VLRSGSN
PCUSN
BS
C
BTS
BTS BTS
BTS
BTS
CS Pages
CS Pages
broadcast on CCCH
All CS pages
are transferred tothe PCUSN
SPM
SPMSPM
SPM
SPMSPM
SPM
PCUSN
SPM has
found that aTBF is alive
for this MS
CS pages
on PACCH
TBF alive
No TBF alive
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4.14. FREQUENCY HOPPING
4.14.1 FREQUENCY HOPPING PRINCIPLES
Basically, Frequency Hopping aims at spreading the spectrum of the signal to minimise the
impact of potential interferers. Frequency Hopping consists in changing the frequency used by
a channel at regular intervals.
In GSM, the transmission frequency remains the same during the transmission of a whole
burst. Thus, it is possible to have different frequencies on each burst of a frame. The radio
interface of GSM uses then slow Frequency Hopping.
According to the type of coupler used in the BTS, two (2) main types of Frequency Hopping
mechanism can be used:
• Synthesised mode for Hybrid couplers with duplexers: hopping time slots can
hop on a large band of frequencies.
• Baseband mode using Cavity couplers with duplexers: hopping time slots can
hop on a set of frequencies limited by the number of TRXs (only available with
S4000 BTS).
Note: using frequency hopping allows to adapt and maximise the frequency re-use pattern
efficiency by maximising the capacity in term of offered Erlang/Mhz/km2. The pattern to use
will depend on the available frequency band and the traffic requirement.
It is possible (and recommended) to mix different frequency re-use technique, as 4X12 for
BCCH and 1X3 or 1X1 for TCH. Indeed, a traditional 4X12 reuse pattern is appropriate to awide spectrum allocation as for BCCH frequency (only one frequency per cell is needed).
However, in order to increase the number of TRX per cell with a given frequency band, while
keeping a low interference level, the only solution is to use more restricting reuse pattern, as
1X1 or 1X3.
See also chapter General Rules For Synthesised Frequency Hopping.
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4.14.2 MAIN BENEFITS OF FREQUENCY HOPPING
• the higher the number of frequencies in the hopping law, the smaller the
Fading margin taken into account in the link budget (due to Rayleigh fading).
• the smaller the mobile speed and the higher the number of frequencies, the
higher the benefit of the frequency hopping.
• the higher the number of frequencies in the hopping law, the narrower the
Rxqual distribution. However Rxqual mean remains the same (see figure
below). Hence the Frequency Hopping eliminates the number of bad Rxqualsamples but it also reduces the number of good Rxqual ones.
RXLEV cdf versus SFH
FADING MARGIN (dB)
%
1
10
100
-2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1 freq
2 freq
4 freq
8 freq
2
48
RXLEV cdf versus SFH
FADING MARGIN (dB)
%
1
10
100
-2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1 freq
2 freq
4 freq
8 freq
2
48
Frame Erasure Rate versus SFH at –104 dBm (DCS)
NUMBER OF FREQUENCIES FOR HOPPING
F E R ( % )
0.00
2.00
4.00
6.00
8.00
10.00
12.00
1 2 3 4 5 6 7 8
0.5 km/h
1.5 km/h
2.5 km/h
5 km/h25 km/h
0.5
1.5
2.5
5
25
Frame Erasure Rate versus SFH at –104 dBm (DCS)
NUMBER OF FREQUENCIES FOR HOPPING
F E R ( % )
0.00
2.00
4.00
6.00
8.00
10.00
12.00
1 2 3 4 5 6 7 8
0.5 km/h
1.5 km/h
2.5 km/h
5 km/h25 km/h
0.5
1.5
2.5
5
25
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• Increase resistance to Rayleigh fading:
re-centred RxQual distribution for slow moving mobilesbetter stability of the received signal level (smoothing effect)
completion of diversity task on uplink and full benefit on downlink
high improvement for areas of weaker signal strength (inside buildings and
on street level)
• Resistance to interference
spread of interference over all RF spectrum
spread of interference over time
highly loaded sites benefit from lower load on adjacent sites
more efficient error correction gain from digital processing
cdf RxQual with SFH, at 0.5 km/h, -104 dBm (DCS)
BER %
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10
1 freq4 freq8 freq
16 freq4 816
cdf RxQual with SFH, at 0.5 km/h, -104 dBm (DCS)
BER %
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10
1 freq4 freq8 freq
16 freq4 816
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4.14.3 SYNTHESISED FREQUENCY HOPPING
Using synthesised frequency hopping, each TX is associated to one FP (TDMA) and can
transmit on all the frequencies. It is used with hybrid coupling systems then more frequenciesthan TRXs can be used.
The main issue is to ensure that the frequency BCCH is transmitted all the time (on all the TS
of the TDMA) at a constant power even if there is no call to transmit (no voice or data burst).
This is done by a specific configuration which consists in dedicating a TRX to the BCCH
frequency (so the TDMA called BCCH does not hop).
Generally, the number of frequencies is greater than the number of TRX in order to have the
smallest Fading margin in the link budget.
The TDMA configurations in case of synthesised frequency hopping are defined as follows:
• F1 is the BCCH frequency.
• the other two TDMA of the cell have the same MA. HSN and MAIO can be
different.
MA frequency list
TDMA1TX1
TX2
TX3
TX4
BCCH Freq
TDMA3
TDMA2
TDMA4
MAIOMA frequency list
TDMA1TX1
TX2
TX3
TX4
BCCH Freq
TDMA3
TDMA2
TDMA4
MAIO
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4.14.4 BASEBAND FREQUENCY HOPPING
PRINCIPLE
Using baseband frequency hopping, each TX is dedicated to one frequency and is connected
to all the Frame Processor (TDMA) via the FH bus. It is used with cavity coupling system. It
uses exactly the same number of frequencies as TRXs.
The filling is done by the FP according to the configuration of the TDMA (all the parameters for
the frequency hopping are static and not per call basis; so even if there is no call the FP
knows if it has to transmit on the BCCH frequency).
Moreover the TX can have a carrier filling functionality which is not useful for the BCCH
frequency (Carrier filling is already done by the FP) but which can be used in case of other
frequencies carrier filling with the use of a specific BCF load.
For a given cell with the previous configuration (4 TRX), one Mobile Allocation should bedefined:
• MA0 contains all the frequencies except the BCCH frequency (3
frequencies in the exemple).
The baseband frequency hopping configuration is the following:
• hopping on TCH, no hopping on BCCH
FP1 TX1
FP2
FP3
FP4
TX2
TX3
TX4
BCCH Freq
Filling burst when there is no information
to transmit on the BCCH frequency.
If filling is needed on other frequencies,
it is managed by the TXs.
FP1FP1 TX1
FP2FP2
FP3FP3
FP4FP4
TX2
TX3
TX4
BCCH Freq
Filling burst when there is no information
to transmit on the BCCH frequency.
If filling is needed on other frequencies,
it is managed by the TXs.
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TS 0 1 2 3 4 5 6 7
TDMA 0 F1 F1 F1 F1 F1 F1 F1 F1 MAIO=0
TDMA 1 MA0 MA0 MA0 MA0 MA0 MA0 MA0 MA0 MAIO=1
TDMA 2 MA0 MA0 MA0 MA0 MA0 MA0 MA0 MA0 MAIO=2
TDMA 3 MA0 MA0 MA0 MA0 MA0 MA0 MA0 MA0 MAIO=3
• MA: Mobile Allocation (list of hopping frequencies for a TRX)
• MAIO: Mobile Allocation Index Offset between 0 and (Nb of Freq in MA -
1).
• F1: BCCH frequency
CAUTION!
It is not recommended to hop on BCCH frequency when using baseband frequency hopping,
because it can lead to some troubles when downlink DTX or downlink power control are
enabled.
RECONFIGURATION PROCEDURE
This procedure is not applicable to BTS that use hybrid coupling.
With the baseband frequency hopping mechanism (used only by BTS that have cavity
couplers), it is possible to reconfigure the frequencies in certain cases. In case of equipment
failure/recovery within a TRX, the BSC starts the reconfiguration process for a Radio Cell
which supports frequency hopping and uses the Frequency Management GSM function.
This function is supported by the TRX and allows the BSC to configure or to reset a frequency
on a TX which is identified by the TEI of the corresponding TRX. The loss of one TX implies
the loss of one frequency (which is not the BCCH) and of one TDMA (the one defined with the
lowest priority) if no redundant TRX.
Two symmetric mechanisms are managed by the BSC to handle the automatic frequency
reconfiguration in the case of frequency hopping cavity coupling BTS:
• loss of a frequency
the cell is stopped and restarted with new set of frequencies. This may lead
to release the calls if there is more live TX than btsThresholdHopReconf
• recovery of all frequencies
an automatic reconfiguration is triggered by the BSC when all the
frequencies are recovered. This may lead to release the calls
There will be a reconfiguration if the flag bscHopReconfUse is set to “true” (defined at BSC
level) and if there are more frequencies than the threshold btsThresholdHopReconf (defined at
BTS level). Otherwise the cell is badly configured.
When a end of fault occurs if the flag btsHopReconfRestart is set to “true” and if there are
more frequencies than the threshold (btsThresholdHopReconf), there is a complete cell
reconfiguration.
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4.14.5 AD-HOC FREQUENCY PLAN
The Ad-Hoc frequency hopping does not reproduce a pattern all over the network. Frequency
planning is done (HSN, MAIO, MA lists) according to the interference matrix. The particularityis that the number of hopping TRX = the number of hopping frequencies in most of the cases.
A frequency plan optimizes frequency hopping list of each sector in order to reduce the
interferences. The length of the frequency hopping list is variable (it should be at least equal to
the number of TRx on the sector).
For ad-hoc frequency planning, an interference matrix or a very intense and accurate drive
tests campaign is needed. A frequency planing tool can also be used.
For each method the principle is the same: take into account DL BCCH and HO interactions
between cells. The frequencies on the list are planned intelligently in order to avoid collision
with the neighboring cells, allocating same frequencies on the hopping list to cells which are
far in distance or that the interaction between them is the minimum as possible.
There is a reduction on the number of frequencies on the frequency hoping list. It is
recommended to space the maximum as possible (at least 3 channels) the frequencies used
in the same frequency list to maximize frequency hopping gain (fading reduction)
Every sector of one site has a different HSN in order to minimize co-channel or adjacent
collisions.
The main drawback is the cost to maintain the plan since regularly it is recommended to
review the plan in order to optimize its performances.
Ad-hoc should be considered as a spectral efficiency feature in a constraining bad condition
assuming the cost associated. In case of non frequency band constraining conditions, 1x1 has
shown a great cost-performance trade-off and is worth to use in the case of a fast growing
network in order to minimize operational impacts.
In summary Ad-Hoc frequency plan allows good performances if the calculation method is
very precise (either Interference matrix, drive tests or frequency planning tool) and number ofhopping frequencies per TDMA is sufficicent (at least MA list ≥ 4 frequencies)
TDMA1 TX1
TX2
TX3
TX4
BCCH Freq
TDMA3
TDMA2
TDMA4
MA frequency list: n frequencies for n TRX
TDMA1 TX1
TX2
TX3
TX4
BCCH Freq
TDMA3
TDMA2
TDMA4
MA frequency list: n frequencies for n TRX
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4.15. BSC OVERLOAD MANAGEMENT MECHANISMS
The aim of such a feature is to avoid BSC restart or crash because of overload conditions.
Without defense mechanism, an overload of one of the BSC boards will imply a suicide of the
active chain, a switch to the passive chain and at last a suicide of the new active chain. This
implies a suppression of all the communications and an interruption of service.
For further details on this feature please refer to BSS Engineering Rules in chapter Reference
Documents
4.15.1 BSC3000 OVERLOAD MANAGEMENT
The Overload software manages the board load and the global load of the system so as to
avoid the crash in case of overload. On the BSC sub-system an overload situation is mainly
due to the traffic management which is computed on the TMU module. The overload software
uses system indicators to calculate overload levels that allow applications to decrease the load
level.
BSC3000 DIMENSIONING RULES
The BSC is responsible for accepting or rejecting sites creation or reparenting in order to
ensure that the hardware capacity is sufficient to handle the traffic.
The maximum dimensioning of a BSC 3000 is 3000 or 4000 Erlang, 500 Sites, 600 Cells,
1000 or 1500 TRX, 16 SS7 links, 567 LAPD links. A good dimensioning lead to the following
relations:
Carried Traffic ≤ BSC hardware capacity (number of TMU)
Offered Traffic ≤ BSC hardware capacity (number of TMU)
CARRIED TRAFFIC
The carried traffic (or real traffic) is the number of simultaneous voice communication a BSC
handles at the busy hour. The carried traffic is given by the customer for an area or can be
observed with monitoring. It is necessary to consider a margin carried traffic for a lot of
reasons (GPRS traffic is increasing lightly the load on the TMU, Load balancing algorithm
shares fairly the load between TMU, The operator wants to be able to absorb additional traffic
in case of special Event).
As a consequence it is recommanded to use a margin of about 20-25 % when considering the
carried traffic.
Moreover AMR handset penetration should be considered if half rate vocoder is used on a
network since it increases offered capacity on radio sites.
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LIST OF OPERATIONS TO BE FILTERED
• Overload level 1: filtering 33,33% requests of the following messages:
Paging request
Channel request with cause different from “Emergency call” All first layer 3 messages with cause different from emergency call
Handover for traffic reason
Directed retry
• Overload level 2: filtering 66,66% requestsof the messages described above
• Overload level 3: no new traffic is accepted by filtering all previous and
following messages
All first layer 3 messages
All handover indication
All handover requests
PARAMETERS
No specific new counters or configuration parameters are introduced with this feature.
4.15.2 LOAD BALANCING
The Load Balancing is a mechanism that allows a distribution as balanced as possible (from
the traffic weight point of view) of the Cell Groups (CG) among the existing TMUs (See
chapter BSC Boards Management) during the initialization phase. It also allows a
redistribution of the CG on the TMUs (if all the CG are duplex), without disturbing theestablished calls when:
• A TMU module fails or comes into operation (for hardware or operator
reasons)
• An imbalance of the TMU loads is detected by the BSC (on online operations
such as new TMU board, new BTS, or new TRX). In this case, the load
balancing can be manually started.
For further details on this feature please refer to the corresponding chapter in the BSS
Engineering Rules (chapter Reference Documents).
4.15.3 EVOLUTION OF LOAD BALANCING
Some evolutions are introduced in the Cell Group Management and Load Balancing
algorithms used by the BSCe3. These evolutions are made in order to take into account the
introduction of new TMU boards (TMU2), to better introduce new big site configurations.
MAIN EVOLUTIONS
Global dimensioning constraints for the BSC remain unchanged: the BSC capacity is limited
by the following maximum number of managed objects:
• Maximum of 1000 TRX or 1500 per BSC
• Maximum of 600 Cells per BSC
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4.16. CABINET OUTPUT POWER SETTING
This section aims at describing the way to determine the output power of a BTS knowing its
coupling and its associated parameter setting. As described in following figure, two OMCparameters are involved: bsTxPwrMax (powerControl object) and attenuation
(btsSiteManager object).
4.16.1 CABINET POWER DESCRIPTION
There are three steps in the cabinet output power evaluation.
Txtranslation
table
Txtranslation
table
Coupling
system
Coupling
system
OR
SUM
OMC attenuation
(since V9)
DLUattenuation
(until V8)
bsTxPwrMaxPc Pr Ps
Pc: bsTxPwrMax + DLU/OMC attenuation
Pr: given by a translation table
Ps: Cabinet output power
Txtranslation
table
Txtranslation
table
Coupling
system
Coupling
system
OR
SUM
OMC attenuation
(since V9)
DLUattenuation
(until V8)
bsTxPwrMaxPc Pr Ps
Pc: bsTxPwrMax + DLU/OMC attenuation
Pr: given by a translation table
Ps: Cabinet output power
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4.16.2 PR COMPUTATION
According to bsTxPwrMax, the coupling system and the product family (S8000/S12000) Pr
can be defined
For more details on the Pmax per products, please refer to the Engineering Rules (ref. [R47]
to ref. [R56]).
4.16.3 PS COMPUTATION
Then, the effective cabinet output power is:
Ps = Pr - cablesLoss - couplingLoss
Pr is derived from Pc (where Pc = bsTxPwrMax + OMCattenuation or DLU attenuation) based
on the translation table (§ 4.13.2). Pr can only be equivalent to Pmax in case when the
operator has chosen the maximum value for bsTxPwrMax for a given coupling system.
POWER AMPLIFIER 30W
The nominal output power output for PA is 44.8 dBm (+/- 0.5dBm). This nominal output is the
same for all frequencies.
HIGH POWER EDGE POWER AMPLIFIER (HEPA)
The nominal power output for HePA depends on the frequencies and on the product. Please
note that not all product support HePA for all the frequency bands.
For more details on HePA output power as a function of the product and the frequency band,
please refer to the appropriate Engineering rules document ([R47] to [R56])..
COUPLING SYSTEM
To know the input power, it is important to factor in the system coupling losses. Please refer to
the appropriate Engineering rules document ([R47] to [R56]).
CABLE LOSS
For the values of the losses depending on the BTS configuration and frequency band, please
refer to the appropriate Engineering rules document ([R47] to [R56]).
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4.17. SYSTEM INFORMATION MESSAGES RELATED FEATURES
4.17.1 DUAL BAND HANDLING
The purpose of this feature is to allow an operator with licenses in several frequency bands to
support the use of multiband mobile stations in all its bands. In addition, it also allows the
operator to support the use of single band mobile stations in each band of the license. The
specification indicates that GSM900 and GSM1800 frequency bands can be combined. No
frequency band is treated as the primary band. However, parameter setting can help
multiband MS to give a higher priority to one of the bands.
CAUTION!
It has been experimented that with some mobile brands a delay in the other band neighbor
cells reports occurs, i.e. a minimum time is necessary for those mobiles to sendmeasurements from neighbors transmitting of the other band to the current cell.
MULTIBAND MOBILE STATION
A multiband mobile station is a mobile station which:
• supports more than one band
• has the functionality to perform handover, directed retry, channel assignment,
cell selection and cell reselection between the different bands in which it can
operate (within the PLMN)
• has the functionality to make PLMN selection in the different bands in whichcan it operate
• has 2 receivers, one specific to each band
• has 2 transmitters, one specific to each band
MODIFIED SYS INFO 3
Two new fields have been added to SYS INFO 3:
EARLY_CLASSMARK_SENDING_CONTROL
It indicates if multiband MS is authorized to send the early Classmark Change message to theBSC via the BTS. This allows the MSC to receive as soon as possible the multiband
information and to pass it to the target BSC. It will speed up call set-ups and allows to perform
Handover and directed retry when needed. The Classmark Change indicates the frequency
bands supported by the MS and MS power classes to perform HO procedures in the best
conditions.
The corresponding parameter is the class 3 attribute early classmark sending belonging to bts
objects. If it is set to “enabled”, the Classmark_Change message is sent just after the SABM
and UA frames exchange on the Immediate_Assignment procedure. This message makes
interband handover procedures possible. Moreover this parameter allows the mobile to send
its capacity downlink Advanced Receiver performance. That helps to have SAIC mobilepenetration
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In single band networks, early classmark sending will be set to “disabled”.
Note: indeed monoband network may forbid a dual band mobile to use the Early Classmark
sending procedure in order to prevent phase 2 mobiles to send useless information to the
network, and to cope with any potential problems with this feature in the mobiles.
SYS_INFO_2TER_INDICATOR
It is used to inform multiband MS that SYS INFO 2ter information is available.
NEW SYS INFO MESSAGES
The neighbouring cell lists for handover and cell reselection are broadcast towards multiband
and single band mobile stations. The frequencies of neighbouring cells in other frequency
bands than the current cell will be carried by new SYS INFO messages:
• SYS INFO 2ter for reselection neighbours.• SYS INFO 5ter for handover neighbours.
A single band mobile station will only use frequencies from SYS INFO 2 and 5 and if
necessary, 2bis and 5bis for reselection and handover purposes, i.e. frequencies from the
frequency band it supports. The BSC selects neighbour cells from the other band out of the
neighbour list and sends them in SYS INFO 2ter and 5ter (see table below).
Sys info 2
Sys info 5
Sys info 2bis
Sys info 5bis
Sys info 2ter
Sys info 5ter
GSM900 cell GSM900 nei list - GSM1800 nei list
GSM 1800 cell GSM1800 nei list GSM1800 nei list GSM900 nei list
NEIGHBOUR CELL LIST IN SYS INFO
The new SYS INFO 2ter and 5ter messages carry parameters which are needed by multiband
mobile stations to perform respectively cell reselection (2ter) and handover (5ter) towards cell
from another band:
• Multiband Reporting: indicates to multiband MS the minimum number of cells
to report in their measurement report outside the current frequency band. Its
value is equal to the Multiband reporting parameter in the SYS INFO 5ter
message.• Neighbouring Cells List: coding of the frequencies of neighbouring cells.
CAUTION!
Some single band mobiles are disturbed by the receipt of SYS INFO 5ter. They react by
sending an RR status message, that can load the BSC. To avoid this, the sending of these
messages is controlled by the BTS. On the opposite, single band mobile stations are not
disturbed by 2ter messages because they ignore them.
No field called ‘Sys_Info_5ter_Indicator’ exists. To know if 5ter messages are sent, SACCH
filling messages are used.
The parameter cellBarQualify is not used by some dual band MS in selection and reselectionalgorithms.
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MULTIBAND REPORTING
Multiband mobile stations report cells from different frequency bands according to Multiband
Reporting parameter (corresponding to class 3 attribute ‘multi band reporting’ of bts objects)
broadcast in SYS INFO messages:
• the six strongest cells: default value. The multiband MS reports the six
strongest allowed cells regardless of the frequency band.
• 1, 2, 3: the multiband MS reports the strongest or the two, three strongest
allowed cells outside the current frequency band. The remaining space in the
report is used to give information about cells in the current frequency band. If
there are still some remaining positions (not enough neighbours in the current
frequency band), these positions are used to report cells outside the current
frequency band.
CAUTION!
A maximum of six cells will be reported. Only this maximum of 6 ”best” cells will be
transmitted to the BSC by the L1M in a Handover_Indication message .
OHER PROCEDURES
The handling of multiband MS did not need specific changes in L1M. Main changes are on MS
side. However, main procedures can be reviewed with the differences that occur in V10.
• PLMN selection: a single band MS only selects a PLMN from its frequency
band. A multiband MS can select PLMNs of both bands.
• Cell selection & reselection: a single band MS only selects or re-selects cells
from its frequency band. A multiband MS can select or re-select cells of both
bands. Priority can be given to one band (see chapter Selection, Reselection
Algorithms).
• Handovers: a new attribute is introduced in both adjacentCellReselection and
adjacentCellHandover objects. Its name is standardIndicator Adjc and tells the
type of network where the neighboring cell operates (“gsm” or “dcs” or
“gsmdcs” or “dcsgsm”). A single band MS only performs handovers towards
cells from its frequency band. A multiband MS can perform handovers
towards cells of both bands if classmark 3 is supported on NSS side.
If local mode directed retry is chosen, as it is performed towards a specific neighbour, one
type of single band MS (the one which does not support the frequency band of adjacent cell
umbrella ref ) will not use this feature.
For multiband MS, formulas like PBGT or thresholds are the same as single band ones, their
power class is replaced according to the band of the cell they are in (se chapter General
formulas).
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range 0 to 7. This number is called TC. The 3GPP specifications define in which BCCH repeat
period (TC value) a specific SYS INFO message can be sent.
SI2Ter, SI13 and SI2quater can be sent when TC=4.
This means that:
• if 1 of SI2Ter, SI13 and SI2Quater messages has to be sent, it will be sent
every 1.88 seconds.
• if 2 of SI2Ter, SI13 and SI2Quater messages has to be sent, each will be sent
every 3.76 seconds.
• if all of SI2Ter, SI13 and SI2Quater messages has to be sent, each will be
sent every 5.64 seconds.
Redirection procedure duration is directly linked to the time the MS needs to read system
information messages.
On the contrary, the sending of system information on extended BCCH increase load on
AGCH/PCH channel.
BENEFITS
Customers are facing MS issues:
• Devices being unable to read SI13 messages when these are sent on the
Extended BCCH. The impact of the failure to read this message was that the
device is partially or completely unable to connect to GPRS services.
• Devices seeing valid SI messages containing 3G NCells (SI2Quater) as
“corrupted” when sent on the Normal BCCH; continued reception of these
messages resulted in the device rebooting or failing to set up CS calls.
So if customers don’t wish to recall affected MS the feature allows to modify the allocation of
SI2Quater and SI13 messages
SI2Quater and SI13 on Ext BCCH allow as well speeding up 3G toward 2G cell reselection
(see chapter Mobility 2G - 3G Reselection).
The drawback is a PCH / AGCH capacity lost.
CAUTION!
When this feature is enabled, e.g. if SI2Quater and/or SI13 on extended BCCH features are
activated, the parameter noOfBlocksForAccessGrant has to be greater than 0.
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4.17.3 SUMMARY OF SYSINFO SCHEDULING
For each multi-frame, the BCCH block is used to transmit a BCCH system information. TC
defines the index of the multiframe in which the Sysinfo message is sent by the network. The
broadcast cycle is 8 multiframes therefore the TC index ranges from TC = 0 to TC = 7.
In the absence of option SYSINFO messages, the basic cycle is :
SYSINFO 1, SYSINFO 2, SYSINFO 3, SYSINFO 4, SYSINFO 1, SYSINFO 2, SYSINFO 3,
SYSINFO 4.
TC5 may be preempted by the optional SYSINFO 2x that has the highest priority, where 2bis
priority > 2ter priority > 2quater priority. TC4 is shared by remaining optional SYSINFO
messages one after the other in the following order : SYSINFO 2ter, SYSINFO 2quater and
SYSINFO 13.
Optional SYSINFO tobroadcast
TC=0 TC=1 TC=2 TC=3 TC=4 TC=5 TC=6 TC=7
None (Si n°) 1 (SI n°) 2 (SI n°) 3 (SI n°) 4 (SI n°) 1 (SI n°) 2 (SI n°) 3 (SI n°) 4
2bis only or 2ter only or2quater only
1 2 3 4 12bis or2ter or2quater
3 4
13 only 1 2 3 4 13 2 3 4
2bis & (2ter or 2quater or13)
1 2 3 42ter or2quateror 13
2bis 3 4
2ter & (2quater or 13) 1 2 3 42quateror 13
2ter 3 4
2quater & 13 1 2 3 4 13 2quater 3 4
1 2 3 4 2ter 2bis 3 42bis & 2ter & (2quater or13) 1 2 3 4
2quateror 13
2bis 3 4
1 2 3 4 2quater 2bis 3 42bis & 2quater & 13
1 2 3 4 13 2bis 3 4
1 2 3 4 2quater 2ter 3 42ter & 2quater & 13
1 2 3 4 13 2ter 3 4
1 2 3 4 2ter 2bis 3 4
1 2 3 4 2quater 2bis 3 42bis & 2ter & 2quater &13
1 2 3 4 13 2bis 3 4
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4.18. INTERFERENCE CANCELLATION
Note : to activate interference cancellation feature, it is necessary to have receive diversity
enabled. Interference cancellation is a very important feature in a mobile network, especiallywhen capacity is a critical issue and aggressive frequency reuse schemes are applied to
maximize it. Experience has shown gains with an adhoc frequency plan. Preliminary studies
had indicated that in a 1X3 reuse frequency pattern network, capacity could be limited by
uplink interferers. In general, even if capacity is not limited by uplink interferers, it is essential
to mitigate their effect for quality improvement. Moreover it has been experienced that even if
capacity is not UL limited, Interference Cancellation ensures improvements on data
performance in UL, vocal quality in UL and measurement reports in UL, which improve
mobility management. This results in a descreasing number of radio drops (study done with
half MS quite UL weak, half MS quite DL weak).
A BTS-based interference cancellation algorithm is of great interest. Nortel has designed aproprietary signal processing scheme aimed at cancelling the interferers. It works on the Base
Stations equipped with all DRX S8K/S12K and with BTS18000. The effect of the feature
depends on diversity: on a site without diversity, the feature Interference Cancelation will have
no benefit. The algorithm works as well with or without frequency hopping and it can remove
any kind of interferer that has some spatial or temporal coherence (co-channel, adjacent
channel, CDMA signal leaking in the PCS band, TV transmitter, etc..). It can be viewed as a
digital beam-forming technique in which a null of the radiation pattern is pointed towards the
interferer.
The algorithm is based on the use of the Maximum Ratio Combining diversity technique and
the midamble in the GSM burst that is used to gain some indication of the channel
characteristics, and hence an estimate of the noise present. This noise is approximately made
up of interference and thermal-noise. The midamble is a known sequence of bits, which
undergoes changes after propagation. The interference estimation is necessarily biaised since
it is estimated on a short period of time (22 Tsymbol compared to the 148 Tsymbol) and the
interference cancellation in the absence of interference will result in decreasing the SNR ratio.
To avoid this problem, a parameter ρ is introduced.
8 interfering MS ’s
on the 8 TS ’s of F0
MS driving away
from serving BS
BS#2
BS#1call drop:
too high C/I
8 interfering MS ’s
on the 8 TS ’s of F0
MS driving away
from serving BS
BS#2
BS#1call drop:
too high C/I
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4.19. EXTENDED CCCH
This feature consists in the implementation of the extended CCCH feature The need of this
feature has been identified in some configuration where only one CCCH is not sufficient, dueto a high rate of paging and immediate assignment.
4.19.1 CUSTOMER/SERVICE PROVIDER BENEFITS
This feature allows increasing the rate of paging and immediate assignment messages related
to a cell and thus:
• Allows managing large location area with up to 16 TRX per cell,
• Gives the ability to manage multi-layers networks
• Allows managing GPRS traffic.
4.19.2 FEATURE FUNCTIONAL DESCRIPTION
You can allow the configuration of extended CCCH on TS 2, 4 and 6 of the BCCH TDMA.
The following CCCH configurations are now available :
CCCH_Conf = 0:
• TS 0 = FCCH+SCH+BCCH+CCCH
CCCH_Conf = 1:
• TS 0 = FCCH+SCH+BCCH+CCCH+SDCCH/4+SACCH/4
CCCH_Conf = 2:
• TS 0 = FCCH+SCH+BCCH+CCCH
• TS 2 = CCCH
CCCH_Conf = 4:
• TS 0 = FCCH+SCH+BCCH+CCCH
• TS 2 = CCCH
• TS 4 = CCCH
CCCH_Conf = 6:
• TS 0 = FCCH+SCH+BCCH+CCCH
• TS 2 = CCCH
• TS 4 = CCCH
• TS 6 = CCCH
Note: By increasing the number of CCCH, we decrease the number of TCH, so it leads to
reduction of the capacity. For example, an O8 with 1 BCCH has a capacity of 48,65 Erlangs
(with 2% of blocking rate); with 4 CCCH its capacity drops to 45,88 Erlangs.
To configuration of a CCCH block on a TS the channelType parameter must be set to “cCH’.
See also chapter SDCCH Dimensioning an TDMA Models.
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4.20. CELLULAR TELEPHONE TEXT MODEM (TTY)
Deaf, hard of hearing, and speech-impaired persons have been using specific Text Telephone
(referred to as TTY in North America) equipment in the fixed network for many years totransmit text and speech through ordinary speech traffic channels.
To answer US FCC requirements, NORTEL release with BSC/TCU 3000 introduction) BSS
includes now the Cellular text Telephone Modem (CTM) solution for reliable transmission of a
Text Telephone conversation via the speech channel of cellular or PSTN networks.
4.20.1 TTY PRINCIPLE
Data transmission methods exist in the wireless services, but for various reasons, a text
telephone transmission method for the speech path is desired. Two reasons are:
• text telephony is acknowledged as a way to contact the emergency services,
and emergency services in wireless networks are so far only defined for
speech calls.
• alternating speech and text in a call is desired, and one simple way to
accomplish that without special service support (like multimedia) is by
alternating the use of the speech channel.
CTM allows reliable transmission of a text telephone conversation alternating with a speech
conversation through the existing speech communication paths in cellular mobile phone
systems. This reliability is achieved by an improved modulation technique, including error
protection, interleaving and synchronization.
The CTM is intended for use in end terminals (on the mobile or fixed side) and within the BSS
network for the adaptation between CTM and existing traditional text telephone standards.
The signal adaptation Baudot CTM is localized in the TCU 3000 in each TRM board.
NORMAL CASE
“SPEECH/DATA INDICATOR” = “SPEECH + CTM”
If an ASSIGNMENT REQUEST or HANDOVER REQUEST message is received from the
MSC with:
• Circuit Identity Code compatible with TRM capability (EFR+CTM)
• “Speech/data indicator” = “Speech + CTM”
• and “permitted speech version identifiers” = EFR
an ASSIGNMENT COMPLETE or HANDOVER COMPLETE message will be sent to the MSC
with Speech Version (Chosen) = EFR.
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“SPEECH/DATA INDICATOR” = “SPEECH”
If an ASSIGNMENT REQUEST or HANDOVER REQUEST message is received from the
MSC with:
• Circuit Identity Code compatible TRM capability (EFR+CTM)
• “Speech/data indicator” = “Speech”
• and “permitted speech version identifiers” = EFR
• and unavailable archipelago EFR resource (SPU)
an ASSIGNMENT COMPLETE or HANDOVER COMPLETE message will be sent to the MSC
with Speech Version (Chosen) = EFR.
ABNORMAL CASE
On reception by the BSC of an ASSIGNMENT REQUEST or HANDOVER REQUESTmessage with:
• Circuit Identity Code incompatible with TRM capability (the circuit pool implied
by the CIC information element is incompatible with the channel type
indicated)
• “Speech/data indicator” = “Speech + CTM”
• and “permitted speech version identifiers” = EFR
• and unavailable archipelago EFR_CTM resource (SPU)
In a first step an ASSIGNMENT FAILURE or HANDOVER FAILURE message will be sent to
the MSC.
In a second step an ASSIGNMENT COMPLETE or HANDOVER COMPLETE message will be
sent to the MSC with Speech Version (Chosen) = EFR TTY impact
4.20.2 TTY IMPACT
TCU 3000
The TCU 3000 capacity is affected by the CTM implementation according to the configured
archipelagos EFR_CTM number.
Please refer to BSC/TCU 3000 Engineering Rules [R63]
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4.21. SMS-CELL BROADCAST
The objective of this feature is to support new broadcast services as advertising or
information’s with BSC12000 and BSC3000
The goal is to offer an interface for the SMS-CB that allows to send easily the same message
on every cell of a list of BSCs and so that the system can update all the cells in a quicker time.
4.21.1 PRINCIPLE
In the Nortel network’s structure of Cell Broadcast Service a Cell Broadcast Center is
interfaced with the OMC via a non Q3 interface. The OMC act as the SMS-CB manager and
broadcast SMS over all the BSCs placed under its control.
The new requirements concern:
• the broadcast of the same short messages on all the cells which are managed
by an OMC-R or a BSC list.
• the change rate of these short messages: 13 seconds are required;
• The current implementation about the short message broadcast involves
several limitations and OAM constrains which should be raised:
• CBC/OMC-R interface throughput which must be compliant with the user
activity performance.
• OMC-R/BSC interface throughput which must be compliant with the number of
message (TGE) to be processed by the BSC (from 1 up to 2 TGE/sec for all
transactions).
• Heavy OAM constraint to update the data base CBC when network (re)configuration occurs.
Cell
Broadcast
Center
OMC
SMS-CB
manager
BSC
BSC
BS
BS
BS
BS
BS
Cell
Broadcast
Center
OMC
SMS-CB
manager
BSC
BSC
BS
BS
BS
BS
BS
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4.21.2 PERFORMANCES
The following table depicts the number of messages:
CBC / OMC / I/F OMC / BSC / I/F
Messages Old New Old New
Create short message 1 1
Start broadcast (first time) X*Y 1 Y 1
Set short message (continued) 1 1
Stop broadcast (continued) X*Y 0 Y 0
Start broadcast (continued) X*Y 1 Y 1
Stop broadcast (last) X*Y 1 Y 1
Periodic MMI commandsnumber
(1+2*X*Y)*n 2*n
Periodic TGEs number
2*y*n
320*n max or
1200*n max
n
X: BSC number [1:30]
Y: Cell number / BSC12000 [1:160]
X*Y: Cell number / OMC [1:2400]
n: Number of updates of messages
With this solution, SMS-CB has been dimensioned for following capacities:
• 5 messages maximum per cell (broadcast in loop)
• message format: 1 page / 93 characters• broadcast periodicity (30 sec, 1 mn, 2mn, 4 mn, 8 mn or 16 mn), 2 sec (1
message / cell) corresponding to the CBCH maximum capacity
The whole users activity can be:
• on an average: 1 MMI command every 10 sec. for the whole set of users. Or,
1 MMI unitary command every 160 sec. per users, with a maximum of 16
users.
• on a maximum: 1 MMI unitary command every 2 sec. for the whole set users,
during 2 hours maximum. Or 1 MMI unitary command every 32 sec. per users,
during 2 hours maximum, with a maximum of 16 users.
The CBC can be associated to n users among 16 ones: then the number of MMI commands
on the CBC / OMC interface is n every 32 sec.
Every short message modifications involves 2 MMI unitary commands (set short message &
start broadcast) the short message change rate is 32*2n.
Note:
When the OMC-R receives one command for all the cells of one or several BSC, it checks for
each cell if there is a CBCH channel and if the limit of 5 short messages is not exceeded. That
defines a “compliant” cell. It then checks if a threshold S (per BSC) corresponding to a max of
tolerated non compliant cells is reached.
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If the limit of 5 messages is exceeded for one or several cells and if the number of non
compliant cells exceeds the threshold S for one or several BSC, the OMC-R rejects the
command and does not sent the TGEs. The TGEs will not be sent for these BSC(s), but will be
sent for the others. The response (FAILED) to the CBC will report per BSC the non compliant
bts identities (up to the first S bts identities per BSC).
If the number of non compliant cells does not exceed the threshold S for any BSC, the OMC-R
accepts the command and sends the TGEs. The response (SUCCEEDED) to the CBC will
report per BSC the non compliant bts identities (up to S bts identities per BSC).
CBCH CHANNEL RECOMMENDATION
On the air interface the CBCH channel takes 4 TS bursts (4*0.577 ms) on one 51 multiframe.
The CBCH channel takes the place of one SDCCH channel.
The SDCCH channel can be mapped on two different ways on TDMA: with BCCH combined
(SDCCH/4) or on one reserved TS for SDCCH (SDCCH/8). Thus it is the same thing for
CBCH.
The CBCH is not using the radio resources of the CCCH. It is using the radio resources of one
SDCCH channel. The activation and the use of the SMS-CB will not impact the load on the
CCCH.
The activation of the CBCH will take 1 SDCCH channel and so will increase the SD
congestion. After the activation of the CBCH one needs to follow the SDCCH congestion and
maybe if necessary on some cells to increase the number of SDCCH channels.
Once defined on the cell the CBCH channel can only be used to send SMS-CB. Thus the
quantity of SMS-CB sent will not impact the load of the radio channels other than the CBCH.
Throughput calculation:
The CBCH (idem to SDCCH) offers 184 bits for a block message (or 4TS).
The corresponding throughput offered by the CBCH carried on 51 multitrame:
Throughput = 184 * 4 / 4.615 ms / 51 = 781 b/s
The limitations described in the FN are:
• SMS of 88 bytes
• 5 messages per cell
• 2 seconds between each message.
This means a throughput of: 88 * 8 * 5 / 2= 1760 b/s, which is more than 2 times the max
throughput of the CBCH channel.
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4.22. AMR - ADAPTATIVE MULTI RATE FR/HR
Nortel BSS has evolved to introduce sophisticated traffic management features dealing with
call quality management and capacity improvements. This feature manages AMR services,which allow high gains and good trade-off between these 2 objectives.
4.22.1 BASICS AND SPECIFIC TERMINOLOGY
In GSM, speech is transmitted on a radio channel (using a speech coder also called source
coder) which has a fixed raw bit rate. The coder delivers speech frames every 20 ms. From
that standpoint, speech quality tends to improve when the source coder bit rate is increased.
If we use a high coder rate, the speech quality will be very good in excellent radio conditions,
as long as speech frames can be decoded properly. But in bad radio conditions, a high
proportion of speech frames will not be decoded, in which case some interpolation will bedone by the decoder, and speech quality actually drops. If we use a low coder rate, speech
quality will be medium or low, but will resist very well to radio channel impairments, due to the
high level of redundancy. Consequently, present techniques like FR or EFR are the result of
compromises between the source coder rate, and the channel coding, within the boundaries of
the raw bit rate of a GSM channel.
AMR techniques are adaptive, and multirate. It means that it allows adapting the compromise
between source coder rate and channel coding/redundancy to actual radio conditions. AMR
may operate in full rate channels, or half rate channels. This is called the “channel type”
(TCH/FR or TCH/HR). Uplink and downlink always apply the same channel type.
Basis of AMR is that within the channel (FR or HR), there is a set of voice coders, along with
associated channel coding, among which the best combination can be selected to maximize
speech quality according to conditions met on the radio link. This is “codec mode adaptation”.
For codec mode adaptation the receiving side performs link quality measurements of the
incoming link. The measurements are processed yielding a Quality Indicator.
For uplink adaptation, the Quality Indicator, as measured in the BTS is compared to certain
thresholds and generates, also considering possible constraints from network control, a Codec
Mode Command (CMC) indicating the codec mode to be used on the uplink. The Codec Mode
Command is then transmitted inband to the mobile side where the incoming speech signal is
encoded in the corresponding codec mode. For downlink adaptation, the DL Mode Request
Generator within the mobile compares the DL Quality indicator with certain thresholds andgenerates a Codec Mode Request (CMR) indicating the preferred codec mode for the
downlink.
Both for uplink and downlink, the presently applied codec mode is transmitted inband as
Codec Mode Indication (CMI) together with the coded speech data. At the decoder, the Codec
Mode Indication is decoded and applied for decoding of the received speech data.
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The following figure provides the AMR data flow from a "CMR, CMC and CMI" point of view
and explains the CMI, CMC and CMR period.
AMR is introduced to choose in real time the repartition between rate of the source vocoder
and channel protection:
• when the transmission is good, a high rate vocoder is chosen and the
number of bits dedicated to the channel protection is low,
• in case of degraded radio conditions, the vocoder rate is decreased, in
order to provide a better channel protection and allow a better voice
quality.
MS BTS
CMI
CMR
CMI
CMR
CMI
CMC
CMI
CMC
20ms
40ms 20ms
40ms
MS BTS
CMI
CMR
CMI
CMR
CMI
CMC
CMI
CMC
20ms
40ms 20ms
40ms
Half Rate
Full Rate
Source coding
Channel codingGlobal throughput = 11,4 kBits/s
Global throughput = 22,8 kBits/s
Half Rate
Full Rate
Source coding
Channel codingGlobal throughput = 11,4 kBits/s
Global throughput = 22,8 kBits/s
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UPLINK REQUESTED CODEC MODE
The BTS computes for each burst the SNR criteria, which provides a good approximation of
C/I. In order to have a smooth variation of these criteria, the BTS applies the following filter:
(SNR)(k) = ß * (SNR)(k) + (1 - ß) * (SMR)(k - 1)
Where ß is equal to:
0.05 in case of FR no frequency hopping channel and slow moving mobile,
0.1 in others cases of FR channels,
0.1 in case of HR no frequency hopping channel and slow moving mobile,
0.2 in others cases of HR channels.
In case of DTX, the BTS cannot evaluate the SNR criteria, thus during the DTX period, the last
value of (SNR)k is taken into account and at the end of the DX period, a time exponential filter
is used in order to increase the weight of the new measures and keep the same period of
filtering. This filtered SNR is compared to a set of thresholds and allows determining the
requested codec mode. If no uplink correct frames is received, the BTS has no way to
evaluate the quality of the downlink path, the BTS decreases the applied downlink codec
mode of one step each 40ms. This procedure is repeated until an uplink frame is correctly
received or the 4k75 codec mode is selected for the downlink path.
CAUTION! Before V16.0 there was a limitation on UL SNR in order to have homogeneousbehavior for AMR calls with every kind of DRX. From now, UL SNR measurements aretruncated at 24dB (48 in 0.5dB) at SDO level, whatever hardware is used. The 48 value givenfrom the BTS corresponds to 24dB and more. This new implementation improves the powercontrol reactivity. That impacts on the AMR metric. Therefore C/I metric values for both AMRand EFR calls cannot be compared.
PARAMETERS
For each mobile, the following set of parameters has to be defined:
• for each link direction (upLink or DownLink), one threshlod per subsequent
codec in the defined Active Codec Set (ACS),
• one hysteresis (the same value is used for each codec mode, but one for FR
and another one for HR channel).
But these parameters are linked to a set of factors, some of them being determined by the
BTS (frequency hopping, MS speed), others being network dependent (environment profile…).
The following table is implemented in the BSS:
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According to the network configuration, and for each combination of codec mode and link
direction, the operator selects the appropriate thresholds by using the parametersamrUlFrAdaptationSet, amrUlHrAdaptationSet, amrDlFrAdaptationSet, amrDlHrAdaptationSet
(or the single parameter amrAdaptationSet before V15.1.1). These parameters allow to
choose between 3 sets of pre-defined tables (optimistic, pessimistic and typical settings) plus
one set of tables which is user-defined The BSS using the TS configuration and the MS speed
applies the appropriate column for the uplink path.
As specifed in the GERAN recommendations (05.09) the mobile shall use the downlink
thresholds provided by the BSS defined for a reference environement: Typical Urban 3 km/h
with ideal frequency hopping at 900 MHz. The MS shall then apply a normalization factor to
normalize with respect to different channel types. The normalization factor is mobile
dependant.
See also chapter AMR Field Feedback for further informations on the codec adaptation table.
RATSCCH MANAGEMENT
This new channel is used in order to change the set of codec modes (see "L1m" section), and
has the following main characteristics:
• frame stealing (1 speech frame for a FR channel, 2 speech frames for a HR
channel),• priority of RATSCCH frames is lower than FACCH priority,
• a RATSCCH message has to be acknowledged in the next 3 frames by the
MS,
• the content of RATSCCH message is applicable 12 frames after this
message,
• in case of failure (ACK_ERR message), a RATSCCH procedure is repeated
twice. If the procedure completely fails, the MS and the BTS use the previous
set of codec modes.
downlink
5k9 to 4k75 81 90 99 108 1176k7 to 5k9 82 91 100 109 118
10k2 to 6k7 83 92 101 110 119
12k2 to 10k2 84 93 102 111 120
FR hysteresis 85 94 103 112 121
5k9 to 4k75 86 95 104 113 122
6k7 to 5k9 87 96 105 114 123
7k4 to 6k7 88 97 106 115 124
HR hysteresis 89 98 107 116 125
SFH 900
TU3
uplink
FR thresholds
HR thresholds
slow MS -
no FH
fast MS -
no FH< 4 FH
ideal FH
(>= 4 freq)
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When amrReserved1 is set to enabled, this procedure is used by the L1m to modify the set of
codec modes, for a FR channel and in case of handover failure with return on the old FR
channel, in order to avoid inconsistency between the BTS and the MS (the BTS sends the
AMR_CONFIG_REQ message).
For TCH/FR, the default transmission phase shall be such that Codec Mode Indications are
sent aligned with TDMA frame 0 in the uplink and with TDMA frame 4 in the downlink. For
TCH/HR, the default transmission phase shall be such that Mode Indications are sent aligned
with TDMA frame 0 or 1 depending on the subchannel in the uplink and with TDMA frame 4 or
5 depending on the subchannel, in the downlink.
If at call setup or after a handover, the Codec Mode Indication is not aligned, an Ater
procedure is engaged in order to change the default phase in downlink direction.
PRINCIPLES
The RATSCCH as the FACCH shares the dedicated channel of the TCH. Contrarily to the
FACCH the RATSCCH is time synchronous. The RATSCCH allows modification of the AMR
configuration (CMI/CMC phasing, Adaptation Thresholds, ACS)..The introduction of the AMR,
Nortel Networks BTS will support the RATSCCH (All Nortel’s BTS from the S4000 DCU4 to
the most recent BTS will support the AMR speech service.)
The RATSCCH message is composed of a preamble and of a message part. Several
messages have been defined. These messages correspond to different procedures. At the
moment the following have been defined:
• Changing of the Active Codec Set• Changing of the thresholds and hysteresis
PRE-HANDOVER
In case of intracell or intercell handover, the adaptation mechanism has to be frozen to the
ICM. For this result, the BTS has to intercept:
• the Assignment Command in case of intracell,
• the Handover Command in case of intercell handover,
and to perform up to 2 codec mode adaptations, in order to activate the initial codec mode
(5k9 kbits in all cases) and to stop the adaptative mechanism.
This induces:
• an increase of around 150ms on the handover duration from the BSS point of
view,
• a delay of around 150ms on the handover starting time from a MS point of
view, but no impact for the end-user in term of voice quality (i.e. same speech
gap).
In case of handover failure when the MS returns on the old channel, the adaptation
mechanism is restarted by the BTS at reception of the Start Measurement message
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4.22.3 TRAFFIC MANAGEMENT MECHANISMS
CHANNEL ALLOCATION
TCH channel allocation is triggered by the reception of an Assignment request or a Handover
request message from the MSC, or in case of an intraBSC handover. The BSC should
determine whether AMR is to be used, and select between FR or HR. This mechanism is
based on proprietary algorithms, which provide to the operator a full control of the allocation.
These decisions are made based on several criteria:
• OAM flags which indicate if the BSC, the TCU, and the cell support AMR, and
strategy selected
• MS capability, which is reported by the MSC in Assignment request or
Handover request messages
• radio context, for instance as evaluated during the SDCCH phase.
The BSC also has to control the BSS version: an AMR channel is activated only if all nodes
managing the call are at least in V14.
FLAG MANAGEMENT
We use the two following parameters:
• coderPoolConfiguration (AMR, fullrate, enhancedfullrate) attribute. This
attribute indicates enumerated speech coding algorithms supported by the
TCU.
• speechMode (halfRateAMR, fullRateAMR, fullrate, enhancedfullrate) attribute.
This attribute indicates speech coding algorithms supported by the cell.
CHANNEL TYPE MANAGEMENT
In order to select the channel type associated to the connection, the BSC uses the channel
rate and type and permitted speech version information, in order to know the MS capability in
term of:
• FR/HR management
• Speech codec
But the chosen channel type is fixed according to radio criteria and some O&M parameters,
and the BSS has the possibility to modify the channel type during the connection, in all cases.
So at reception of the Assignment Request or Handover Request, the following mediation is
done on the Channel Type octet 4:
IF Target TCH = FR TCH
THEN the BSC always allocates a FR TCH
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IF Target TCH = HR TCH
AND IF AMR HR is allowed in the cell
THEN the BSC allocates a HR TCH
ELSE the BSC allocates a FR TCH.
CELL LOAD STATE
The cell load state is used in order to choose between a FR or a HR channel, and is defined
using following parameters:
• hrCellLoadStart
• hrCellLoadEnd
• filteredTrafficCoefficient
Previously to V15.1.1, if hrCellLoadStart = 0, then FR radio channel is always allocated to the
MS, and if hrCellLoadStart > 0, then HR radio channel is allocated to the MS, according to its
radio conditions. For one call, the cell load state is evaluated at the first TCH allocation in the
cell, thus in case of intracell handover, the cell load state is not reevaluated.
In V15.1.1, the feature AMR based on traffic is introduced. The goal is to enhance the HR
allocation in order to take into account the cell load: AMR HR channels are allocated only
during loaded period. The cell load state is evaluated every 10s (see Filtered Erlang traffic andcell load state)
ASSIGNMENT
In case of assignment, according to:
• the speechMode parameter value of the target cell (signalingPoint +
TranscoderBoard + bts parameters)
• the cell load of the target cell
• the radio condition of the MS
the BSC selects the target Channel Type.
To know the radio conditions, the BSC sends to the BTS a Connection State Request and in
the Connection State Ack the BTS gives the following bit map:
• “small zone” bit indicates if the small zone of the serving is eligible in case of
multi-zone cell
• “HR large” bit indicates if the MS has sufficient radio conditions to manage a
HR channel in the large zone of a mullti-zone cell or in normal cell
• “HR small” bit indicates if the MS has sufficient radio conditions to manage a
HR channel in the small zone of a mullti-zone cell or in normal cell
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4.22.4 AMR L1M
Up to V14, L1m algorithms are common for all types of dedicated channel, but due to
performances of AMR channels:
• A FR AMR channel, specially with low codec mode, is more resistant than the
normal FR channel
• A HR AMR channel, is more sensitive to interference than the normal FR
channel
Some new mechanisms dedicated for AMR channels based on "requested codec mode" in
uplink and downlink paths, which are the best representation of the quality in this case, are
designed.
For this reason, RxQual criterion is not used in AMR L1m algorithm, dealing with AMR
channel.
12K2 AND 7K4 CODEC MODE FALSE ACTIVATION
As seen before following codec mode sets are implemented in the BTS:
AMR FR AMR HR
10k2
6k7 6k7
5k9 5k9
4k75 4k75
In AMR L1m mechanisms, the main criterion for L1m is the requested codec mode provided
by the MS or the BTS. With this set of codec modes, it is impossible to detect if the quality is
good or very good (in both cases the MS and the BTS provide the 10k2 or 6k7 codec mode
according to the channel type).
In order to solve this problem, for an half rate channel, a fourth codec mode (7k4) is added to
the list allowing to distinguished between good and very good radio conditions. Thus the half
rate codec mode set becomes:
AMR HR
7k4
6k7
5k9
4k75
For a full rate channel:
• if the radio conditions are good for uplink and downlink, then the 12k2 kbits
codec mode is configured and the 4k75 discarded allowing to distinguish
between good and very good radio conditions (using RATSCCH channel).
• if the radio conditions are bad for uplink or downlink, then the 12k2 kbits
codec mode is removed and the 4k75 is set back (using RATSCCH channel).
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Thus the codec mode set becomes:
AMR FR AMR FR
12k2
10k2 10k2
6k7 6k7
5k9 5k9
4k75
The following algorithm details the way of changing the codec mode set, for both paths:
1) initial state: the active codec mode set is {12k2, 10k2, 6k7, 5k9}
2) during the last 480ms period, at least one 4k75 code mode or 3 * 5k9 codec mode
are requested for uplink or downlink paths, then the active codec mode set is changeto {10k2, 6k7, 5k9, 4k75}
3) if the active code mode set is {10k2, 6k7, 5k9, 4k75} and during the last 2*480ms
period, no 5k9 nor 4k75 code mode is requested for uplink and downlink paths, then
the active codec mode set is change to {12k2, 10k2, 6k7, 5k9}.
POWER CONTROL
The Power Control feature reduces the average interferences level on the Network and saves
mobile batteries.
Power control algorithms are redesigned for AMR calls, in order to take into account the
requested codec mode. With the following parameters (powerControl object), the operator
defines the target codec mode of each channel type:
Uplink target codec
• hrPowerControlTargetMode
• frPowerControlTargetMode
Downlink target codec
• hrPowerControlTargetModeDl
• frPowerControlTargetModeDl
For the uplink path, SNR and CMR criteria are available, but the SNR is more accurate than
the CMR. For the downlink path only the CMR is available. Thus the AMR power control does
not apply same principles for both paths. This new power control mechanism is also controlled
by the 2 classical power control parameters:
• bsPowerControl for the downlink path,
• uplinkPowerControl for the uplink path.
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UPLINK POWER CONTROL
For the uplink path, the criterion is the SNR, averaged on 2 measurement periods. As this
mechanism shall guarantee a voice quality, the target SNR is the upper threshold of the
adaptation mechanism:
Note: for the 12k2 (or 7k4) value, the BTS takes into account the 10k2 (or 6k7) value plus the
FR (or HR) hysteresis.
At each measurement period, the BTS calculates the new MS power using the following
formula:
IF (Filtered_SNR – Target _SNR) > 0
THEN MS_txpwr(N) = MS_txpwr(N-1) – 0.7*( Filtered_SNR – Target _SNR)
ELSE IF
THEN MS_txpwr(N) = MS_txpwr(N-1) + 1.4*( Target _SNR -Filtered_SNR)
Note: From V 16, the reactivity of UL power control is improved as UL SNR measurements
limited to 24 dB (48 in 0.5 dB) are taken out.
DOWNLINK POWER CONTROL
The power control principle is:
• To decrease the power level of one step if the last requested codec mode of
the 480 ms is greater than the target codec mode,
• To increase the power level of one step if the last requested codec mode of
the 480 ms is lower than the target codec mode
Note: in AMR like in EFR, the parameter lRxLevDLP indicates the threshold below which
power control is inhibited.
HANDOVER MECHANISMS
The following table describes which handover mechanisms are impacted by the AMR
introduction
Handover type modifieduplink and downlink quality yes
uplink and downlink strength no
distance no
power budget no
uplink and downlink intra-cell handover yes
capture no
inter-zone yes
directed retry no
Traffic no
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PRINCIPLE
These 4 handovers are based on "(n,p) voting" principle, using the requested codec mode.
The (n,p) voting principle considers the last p requested codec modes, it compares them to
two parameters: a codec mode threshold defined for the procedure and the specific n value
used for the procedure.
If p is set to 2 SACCH periods (2*12), n is set to 10, the target codec mode is the green one,
and then a handover is triggered in the following example:
This principle applies in uplink and downlink direction independently.
This mechanism is managed by the L1m and triggered at the end of each period of
measurement, thus p has to be a multiple of the number of requested codec mode in one
measurement period (i.e. 480 / 40 = 12).
The following parameters are defined in the handOverControl object:
• pRequestedCodec
• nHRRequestedCodec
• nFRRequestedCodec
If the n parameter is set to a value greater than the p parameter, then all associated features
are deactivated. If the target codec mode is the smallest, then the associated feature is
deactivated.
INTERBSC HANDOVER
In case of interBSC handover, according to:
• the speechMode parameter value of the target cell (signallingPoint +
transcoderBoard + bts parameters)
• the cell load of the target cell
• the Current Channel element
• the Cause element
the BSC selects the target Channel Type:
• if one out of these last 2 optional A interface elements is not set in the
Handover Request message, the chosen channel type is FR
• if these 2 elements are present and the half rate is allowed in the target cell,
then the following table is applied:
t
Handover
decision
pRequestedCodec
t
Handover
decision
pRequestedCodec
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Current Channel type 1
CauseHR FR
uplink quality FR FR
uplink strength FR FR
downlink quality FR FR
downlink strength FR FR
Distance FR FR
O&M intervention FR FR
Better cell HR FR
Directed retry FR FR
Traffic HR FR
In all other case, a FR channel is allocated.
INTRABSC INTERCELL HANDOVER
In case of intraBSC handover, following transitions are defined in order to determine the target
channel type:
Initial Channel type
Handover causeHR AMR FR AMR
AMR quality FR AMR FR AMR
DISTANCE FR AMR FR AMR
PBGT HR AMR FR AMR
TRAFFIC HR AMR FR AMRForced HO FR AMR FR AMR
Capture FR AMR FR AMR
Directed retry FR AMR FR AMR
The speechMode parameter value of the target cell and the cell load are also checked in order
to verify that the half rate is allowed in the cell.
With AMR calls, RxLev and RxQual criteria for uplink and downlink are not used and replaced
by an algorithm based on "(n,p) voting" principle, using the requested codec mode.
Following parameters are introduced in order to specify the target requested codec mode for
FR and HR AMR channel:
• amrHRIntercellCodecMThresh
• amrFRIntercellCodecMThresh
In order to manage the eligible cell list, a new handover margin is introduced in the
adjacentCellHandOver object: hoMarginAMR this parameter is used in order to calculate the
Exp2 (this expression is used to evaluate the PBGT criteria for each cell and to classify eligible
cells, please refer to chapter EXP2).
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IF N(Uplink) ≥ nXXRequestedCodec
OR N(Downlink) ≥ nXXRequestedCodec
THEN the Handover is triggered
With N the number of requested codec mode for the uplink or the downlink strictly lower than
AMRXXIntercellCodecModeThreshold (XX stands for HR or FR)
INTRABSC INTRACELL HANDOVER
In order to select the channel type, the BSC applies the following table:
Handover cause original channel type target channel type
normal intra-cell FR FR
Small to large zone FR or HR FR
large to small zone FR FR or HR according to radio conditions*
large to small zone HR HR**
tiering FH to no FH FR FR
tiering FH to no FH HR FR
tiering no FH to FH FR FR
tiering no FH to FH HR HR
AMR FR to HR FR HR
AMR HR to FR HR FR
*The radio conditions are given by the BTS to the BSC using the Current Cell Add information
element in the Handover Indication message.
**If radio conditions are not sufficient in the small zone to manage this HR MS, the MS
remains in the large one, due to the HR priority.
Intracell handover principle is to give to the mobile a better resource in term of interference, if
its C/I is low, with a high C value.
This principle is only applicable to FR AMR mobiles, due to interaction with HR >FR handover:
in these radio conditions, it is really more efficient to allocate a FR radio TS to a HR AMR
mobile, than to perform a handover from an HR TS to a HR TS. This intracell handover is
triggered only if the intracell parameter of handovercontrol object is set to enable.
The following parameter is introduced on the handoverControl object, in order to specify the
target requested codec mode for FR AMR channel:
• amrFRIntracellCodecMThresh
The minimum level to perform an AMR intracell handover is defined by following parameters
on the handoverControl object:
• amriRxLevDLH
• amriRxLevULH
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So the intracell handover uses the following criteria:
IF N(Uplink) ≥ nFRRequestedCodec AND RxLevUL > amriRxLevULH
OR N(Downlink) ≥ nFRRequestedCodec AND RxLevDL > amriRxLevDLH
THEN the handover is triggered.
With N the number of requested codec mode for the uplink or the downlink strictly lower than
amrFRIntracellCodecMThresh for the uplink or the downlink
INTRACELL HANDOVER AMR FR AMR HR
This handover is used to change the channel type of a mobile from FR to HR if the quality is
sufficient.
Due to the high C/I requirement for HR channel, the requested codec mode of "(n,p) voting"
mechanism is fixed by default to 12k2 kbits/s and a dedicated "n" parameter allows to set the
trade-off between quality and capacity:
• nCapacityFRRequestedCodec
The handover is triggered if the "(n,p) voting" principle is fulfilled in both directions.
Note:
• this mechanism is not linked to the intracell parameter of handovercontrol
object.
• this mechanism is deactivated if nCapacityFRRequestedCodec is greater than
pRequestedCodec.
So the handover AMR FR to HR uses the following criteria:
IF N(Uplink) ≥ nCapacityFRRequestedCodec
AND N(Downlink) ≥ nCapacityFRRequestedCodec
THEN the capacity handover is triggered.
With N the number of requested codec mode for 12k2 in the p requested codec mode for the
uplink and the downlink path,
INTRACELL HANDOVER AMR HR AMR FR
This handover is used to change the channel type of a mobile from HR to FR if the quality is
not sufficient.
The handover is triggered if the "(n,p) voting" principle is fulfilled in one direction.
The following parameter is introduced on the handoverControl object, in order to specify the
target requested codec mode for this handover:
• amrHRtoFRIntracellCodecMThresh
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Note: this mechanism is not linked to the intracell parameter of handovercontrol object, and it
is deactivated if amrHRtoFRIntracellCodecMThresh is set to 4k75.
DIRECT HALF RATE TCH ALLOCATION
In order to avoid some unnecessary handover from FR to HR channel, it is mandatory to
evaluate the radio conditions at following stages:
• primo allocation: SDCCH to TCH in a normal cell,
• primo allocation: SDCCH to large zone TCH in a multi-zones cell,
• primo allocation: SDCCH to small zone TCH in a multi-zones cell,
• inter-zone handover from large to small in a multi-zones cell.
and allocate immediately a HR channel if radio conditions are sufficient.
The principle of this mechanism is to compare the RxLev uplink and downlink to dedicated
thresholds, in order to estimate the MS HR capability.
Following parameters are introduced on the handoverControl object, in order to specified
RxLev thresholds for this handover:
• amrDirectAllocIntRxLevDL
• amrDirectAllocIntRxLevUL
• amrDirectAllocRxLevDL
• amrDirectAllocRxLevUL
So the direct half rate TCH allocation uses the following criteria:
In a normal cell or in the large zone:
IF RxLevDL > amrDirectAllocRxLevDL and RXLevUL > amrDirectAllocRxLevUL
THEN the direct HR TCH allocation is eligible
In a small zone:
IF RxLevDL > amrDirectIntAllocRxLevDL and RXLevUL > amrDirectIntAllocRxLevUL
THEN the direct HR TCH allocation is eligible
In v17.0, the Direct TCH Allocation mechanism has been improved to take into account thecase where only a short, not fully reliable, measurement average is available. In that case, all
algorithm criteria are tightened by adding the hoMarginBeg parameter to the appropriate
thresholds (amrDirectAllocIntRxLevDL, amrDirectAllocIntRxLevUL, amrDirectAllocRxLevDL,
amrDirectAllocRxLevUL).
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SUMMARY
The following table presents a summary of all new L1m decisions:
HO decision channel type p value for (n,p) voting n value for (n,p) voting target codec
quality intercell UL / DL
TCH FR pRequestedCodec nFRRequestedCodec amrFRIntercellCodecMThresh
TCH HR pRequestedCodec nHRRequestedCodec amrHRIntercellCodecMThresh
quality intracell UL / DL
FR FR TCH FR pRequestedCodec nFRRequestedCodec amrFRIntracellCodecMThresh
HR FR TCH HR pRequestedCodec nHRRequestedCodec amrHRtoFRIntracellCodecMThresh
capacity intracell
FR HR TCH FR pRequestedCodec nCapacityFRRequestedCodec fixed to FR codec 12k2
Direct HR TCH allocation channel type averaging window thresholds
outer zone SDCCH 1 … rxLevHreqt*
rxLevHreqave
amrDirectAllocRxLevDL
amrDirectAllocRxLevUL
inner zone SDCCH
TCH FR
TCH HR
1 … rxLevHreqt*
rxLevHreqave
amrDirectAllocIntRxLevDL
amrDirectAllocIntRxLevUL
* in this case, all available measures, up to rxLevHreqt are taken into account.0
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Following figures illustrate all possible transitions for an AMR call, in a multi-zones cell
environment:
INTRACELL HANDOVERS ON QUALITY
INTRACELL HANDOVERS ON CAPACITY
Tiering BCCH to FH FR
Tiering BCCH to FH HRFR
Intracell FR or HR FR
Interzone FR or HR FR
Intracell FR or HR FR
Tiering BCCH to FH FR
Tiering BCCH to FH HRFR
Tiering BCCH to FH FR
Tiering BCCH to FH HRFR
Intracell FR or HR FRIntracell FR or HR FR
Interzone FR or HR FRInterzone FR or HR FR
Intracell FR or HR FRIntracell FR or HR FR
Tiering BCCH to FH FR
Tiering BCCH to FH HR
FR
HR
Interzone FR FR or HR
Interzone HR HR
Capacity FR HR
HR
Capacity FR HR
Direct TCH
allocation
FR or HR
FR or HR
Tiering BCCH to FH FR
Tiering BCCH to FH HR
FR
HR
Interzone FR FR or HR
Interzone HR HR
Capacity FR HR
HR
Capacity FR HR
Direct TCH
allocation
FR or HR
FR or HR
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AMR FR REQUEST
In case of AMR FR request, there is no specific mechanism. The request is granted in the
same conditions as for a non-AMR circuit-switched call.
AMR HR REQUEST
Before v17.0, in case of an AMR HR request, if a preemption has to be done, then the
allocated channel following preemption is an AMR FR channel.
From v17.0, if the “AMR-HR on preempted pDTCH” feature is activated (v17 parameter
gprsPreemptionForHr = enabled), then the BSC is able to preempt a shared GPRS timeslot to
serve an AMR-HR request. The algorithm is as follows :
When the BSC receives an assignement or a handover request for a half-rate speech channel,the BSC searches for an available HR channel in the following order of preference :
• free half-rate channel of a TCH physical channel whose other half-rate channel is
already allocated to a voice AMR HR call (no dialog between BSC and PCU is
needed)
• free TCH physical channel (no dialog between BSC and PCU is needed)
• free half-rate channel of an already preempted PDTCH whose other half-rate channel
is already allocated to a voice AMR HR call (no dialog between BSC and PCU is
needed)
• half-rate channel of a newly preempted PDTCH (BSC and PCU must negotiate)
This feature for AMR-HR preemption may have an impact on the AMR based on Traffic
threshold settings, see 4.23.7
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4.22.7 ENGINEERING RULES
QUEUING/PRIORITY 0
• queuing is not possible for an HR only request,
• for a FR or HR request in queue, only a FR TCH can be allocated.
The number of priority 0 TS takes into account only radio TS which are completely free (i.e. a
free half rate TS is count for 0).
TCH SIGNALLING
A signaling half rate TCH can not be activated at reception of Channel Required.
If a “signaling” Assignment Request (channel type: “speech/ data indicator” field), for a mobileusing a half rate TCH, an assignment procedure is triggered to a SDCCH channel and the
associated CIC is released (this case occurs at the end of a speech call, if a SMS procedure is
started and not finished).
If a “signaling” Assignment Request (channel type: “speech/ data indicator” field), for a mobile
using a full rate TCH, a channel mode modify procedure is triggered to a signaling TCH
channel and the associated CIC is released (this case occurs at the end of a speech call, if a
SMS procedure is started and not finished).
If an AMR HR or FR Assignment Request is received for a mobile using a signaling FR TCH,
the BSC modifies the current signaling FR TCH to a AMR FR TCH and later, if radio
conditions are sufficient, then a handover from AMR FR to AMR HR will be triggered by the
BTS (see section “Principles/ L1m/Handover mechanisms/ handover HR->FR”).
AUTOMATIC CELL TIERING
This mechanism has to be enhanced as show below, in order to take into account AMR HR
calls:
• P% is evaluated as:
• FH_HR% is the percent of HR calls managed by the hopping pattern in the
cell,
• HR% is the percent of HR calls managed in the cell.
These 2 percentages are calculated by the BTS.
P%=
(Number of non hopping TCH – nbLargeReuseDataChannel) * (1 + Non_FH_HR%)
(Total number of TCH in the cell – nbLargeReuseDataChannel) * (1 + HR%)P%=
(Number of non hopping TCH – nbLargeReuseDataChannel) * (1 + Non_FH_HR%)
(Total number of TCH in the cell – nbLargeReuseDataChannel) * (1 + HR%)
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GENERAL PROTECTION AGAINST HO PING PONG
Due to AMR L1m introduction, a new cause value is added in hoPingPongCombination:
AMRquality. This value is used in case of AMR handover triggered for alarm purpose.
In case of interBSC handover, in order to distinguish between RxQual handover and AMR
quality handover, the BSC uses following rules:
• If the handover cause = RxQual and the speech version <> AMR then the
Handover cause = RxQual.
• If the handover cause = RxQual and the speech version = AMR then the
Handover cause = AMR quality.
HANDOVER EFR/FR - AMR
For handover from an AMR cell to a non-AMR cell it is performed via the A interface using
external handover mechanism, in order to allow the fallback to EFR or FR channel (according
to Assignment Request order).
For handover from a non-AMR cell to an AMR cell, in order to decrease the MSC load, the call
is not upgraded to AMR and a normal EFR handover occurs.
Note that interBSC procedure may increase the number of dropped call, so it is recommended
to minimize that trnasition period.
TDMA CONFIGURATION
Due to the half rate channel introduction and to limit the number of contexts in the BSC, the
number of SDCCH per TDMA is limited as following:
normal cell:
• Maximum number of SDCCH per TDMA: 2,
• only one SDCCH TS managed by odd TS per TDMA,
• only one SDCCH TS managed by even TS per TDMA.
extended cell:
• Maximum number of SDCCH per TDMA: 1.
CAUTION!
It is highly recommended to respect that TDMA configuration in case of activation of AMR.
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AMR HR-FR INTERWORKING
In case of deactivation of AMR FR service, following points have to be highlighted:
• direct HR TCH allocation is available, even if AMR FR is not configured in the
cell,
• handovers from FR radio TS to AMR HR are triggered on “requested codec
mode” criterion, but this criterion is available only for AMR calls, thus this kind
of handover is not possible from a FR or EFR channel and decreases the
AMR HR efficiency,
• handovers from (or to) an AMR HR channel to (or from) EFR channel are
performed using an external handover procedure and thus induce:
• more load on the MSC,
• more perturbations on the voice quality, thus it is mandatory to activate AMRFR service, in case of AMR HR activation.
4.22.8 AMR BASED ON TRAFFIC
PRINCIPLE
Before the feature introduction the choice between an half rate and full rate channel was
based only on radio criteria, thus in order to guarantee the voice quality at any time the
operator had to tune the network with conservative values.
With the introduction of AMR based on traffic, AMR HR channels are allocated only during
loaded period, so the operator could choose more aggressive radio thresholds and then get
more radio capacity for the same number of TRX.
In order to minimize impacts of this strategy, this feature tunes the half rate penetration
according to the cell load:
FR capacity
HR capacity
HR
FR
FR capacity
HR capacity
HR
FR
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This feature is based on a smooth mechanism, which allows anticipating the cell load and
switching the allocation into HR mode, when an Erlang threshold is reached.
The following picture illustrates the interworking between these 2 kinds of mechanisms over24 hours:
Two typical periods are observed:
• Low traffic: all calls are allocated in full rate mode and the blocking is
managed thanks to directed retry and traffic handovers features.
• High traffic: call are allocated in half or full rate modes, according to radio
conditions of each calls and the ultimate blocking is managed thanks to
directed retry and traffic handovers features.
FILTERED ERLANG TRAFFIC AND CELL LOAD STATE
Prior to V18, the Filtered Erlang Traffic used the following formula
n n-1
busy_TCH_TS Filtered_TCH_ratio = a* + (1 - a) * Filtered_TCH_ratio
available_TCH_TS
where:
• Filtered_TCH_ration is the busy TCH ratio managed by the cell at period n.
• α is the filter coefficient (filteredTrafficCoefficient parameter).
• busy_TCH_TS is the number of TCH TS allocated to a FR or a HR TCH call
(in case of multi-zones cell, traffic of both zones is taken into account).
• Available_TCH_TS is the number of TCH TS configured and available in the
cell (in case of multi-zones cell, traffic of both zones is taken into account).
The initial value of Filtered_TCH_ration is set to 0.
FR->HR threshold
Max HR
capacity
Max FR
capacity
Traffic
24 hours
t
Avg Erlang
Number of
allocated TCH
Full rate area
Half rate area
Blocking managed
thanks to directed retry
and HO traffic
Blocking managed
thanks to directed retry
and HO traffic
FR->HR threshold
Max HR
capacity
Max FR
capacity
Traffic
24 hours
t
Avg Erlang
Number of
allocated TCH
Full rate area
Half rate area
Blocking managed
thanks to directed retry
and HO traffic
Blocking managed
thanks to directed retry
and HO traffic
Max HR
capacity
Max FR
capacity
Traffic
24 hours
t
Avg Erlang
Number of
allocated TCH
Full rate area
Half rate area
Blocking managed
thanks to directed retry
and HO traffic
Blocking managed
thanks to directed retry
and HO traffic
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From V18, thanks to AMR maximization introdution the the filtered Erlang evaluation was
modified to take into account a configurable number of shared PDTCH
Where:
• Filtered_Erlang is the number of Erlang managed by the cell at second n.
• α is the filter coefficient (filteredTrafficCoefficient parameter).
• busy_TCH_TS is the number of TCH TS allocated to a FR or HR TCH call
voice in this cell (in case of multi-zones cell, traffic of both zones is taken into
account).
• Preempted_PDTCH_ is the number of PDTCH TS allocated to a FR or HR
call voice in this cell (in case of multi-zones cell, traffic of both zones is taken
into account).• shared PDTCH_ratio is a percentage of shared PDTCH TS (configured and
available) taken into account in the Filtered_Erlang.
• available_TCH_TS is the number TCH TS (configured and available) in the
cell
• available_PDTCH is the number PDTCH TS (configured and available) in the
cell
• MinNbrGprsTS is the number of GPRS TS in the cell (cell object parameter)
to guarantee a minimal number of radio TS allocated to GPRS service.
This formula is valid for AMR Based on Traffic and AMR maximization algorithm.
Note that if the denominator of the Filtered_Erlang formula is null or negative, no computation
is done and the previous value of Filtered_Erlang value is kept.
This filtered busy TCH ratio is then compared to the 2 thresholds HRCellLoadStart and
HRCellLoadEnd in order to determine the cell load state:
• If (Filtered_TCH_ration < HRCellLoadEnd),
Then Cell_Load_Staten = min(max (0, Cell_Load_Staten-1 -1); nb of in service DRX)
• Else if (Filtered_TCH_ration >= HRCellLoadStart),
Then Cell_Load_Staten = min(nb of in service DRX, Cell Load_Staten-1 +1).
• Else Cell_Load_Staten = min(Cell_Load_Staten-1; nb of in service DRX)
The initial value of this Cell_Load_Staten is set to 0.
This mechanism is activated whatever values of all associated parameters (AMR FR and / or
HR activated or not, HRCellLoadStart, HRCellLoadEnd …), in order to allow the monitoring at
the OMC-R level of this mechanism.
)1( _ *)1(
_ _ *) _ ( _ _
)) _ _ * _ (Pr _ _ (*)( _ −−+
−+
+= N ErlangFiltered
ratioPDTCH shared TS MinNbrGprsPDTCH availableTS TCH available
ratioPDTCH shared PDTCH eempted TS TCH busy N ErlangFiltered α α
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In case of TDMA / TRX defense mechanism, the BSC has to take into account the new
number of DRX in service at the next period, in order to evaluate the cell load state.
TRAFFIC MANAGEMENT PRINCIPLE
The 3 algorithms used to allocate a HR channel to a mobile are tuned in order to be adapted
to the cell load.
DIRECT HALF-RATE ALLOCATION
Direct half rate allocation: the range between the OMC-R RxLev threshold and -48dBm (the
deactivation value) is divided in N sub-range, thus new subthresholds are dynamically created
by the BSC. At each cell load state modification, appropriate sub-thresholds is used by the
BTS:
The principle is for the BSC to adapt the following OMC-R parameters according to the cell
load state:
• AMRDirectAllocRxLevUL
• AMRDirectAllocRxLevDL
• AMRDirectAllocIntRxLevUL
• AMRDirectAllocIntRxLevDL
The threshold associated to the cell load state i is evaluated according to the following
formula:
amrDirectAlloc
(Int)RxLevxx-110 -48 dBm
Cell load state
S0
S1
S2
S3
S4
SmaxRxLev
distribution
RxLev1RxLev2RxLev3RxLev4amrDirectAlloc
(Int)RxLevxx-110 -48 dBm
Cell load state
S0
S1
S2
S3
S4
SmaxRxLev
distribution
RxLev1RxLev2RxLev3RxLev4
Nb_DRX-iThreshold_i = int AMRDirectAllocyyRxlevxx + (-48 - AMRDirectAllocyyRxlevxx)*
Nb_DRX
⎡ ⎤⎢ ⎥⎣ ⎦
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Where:
• xx is used for UL or DL,
• yy is used for int or nothing.
Every 10 seconds if needed, new thresholds are sent to all DRX.
The initial value of this mechanism is the threshold_0 (-48dBm),
At the end of a defense TDMA procedure, current thresholds are sent to the BTS.
This mechanism is activated only if:
• at least one OMC-R threshold is not equal to -48.
• The AMR HR service is activated in the cell (speechMode parameters of the
BSC & cell object)
In case of modification of one AMRDirectAllocyyRxlevxx parameter, the new value is takeninto account at the next period.
FR TO HR HANDOVER
FR to HR handover: this handover is activated DRX per DRX according to the cell load state:
• S0: no DRX is configured in order to allow the FR to HR handover
• Si: i DRX are configured in order to allow the FR to HR handover and N-i-1
are configured in order to deactivate this handover.
The BSC chooses the i DRX in the cell according to the AMR FR radio allocator priority.
Highest priority TDMA are switched in FR->HR mode in first. Every 10 seconds if needed, new
parameters are sent to all DRX.
The initial is no DRX activated, especially at the end of a defense TDMA procedure.
In case of modification of any AMR FR to HR handover parameter, the new value is taken into
account at the next period.
All Handover Indication messages sent by the BTS, have to be managed by the BSC
whatever the cell load state.
This mechanism is activated only if:
• nCapacityFRRequestedCodec not greater than pRequestedCodec.• The AMR HR service is activated in the cell (speechMode parameters of the
BSC & cell object)
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INTRA CELL HANDOVER
From V18, the following table describes the BSC mediation in case of intra-cell
handover for an AMR call with the cell in AMR Based on Traffic congestion state:
AMR Based on Traffic
Intra-cell incoming handover mediation
Initial Channel type
Handover Cause
HR AMR FR AMR
Intracell uplink
FR only FR only
Intracell downlink
FR only FR only
Capture
FR only FR only
Inter-zone (outer to inner zone) HR preferred (***) HR preferred (***)
Inter-zone (inner to outer zone) FR only FR only
Frequency tiering FR only FR only
Alarm intra-cell HO (FR => FR) for uplink criteria
in case of AMR FR channelNot applicable FR only
Alarm intra-cell HO (FR => FR) for downlink
criteria in case of AMR FR channelNot applicable FR only
HR => FR HO for uplink criteria in case of AMR
HR channelFR only Not applicable
HR => FR HO for downlink criteria in case of
AMR HR channel
FR only Not applicable
Capacity HO (FR => HR) for uplink and downlink
criteria in case of AMR FR channelNot applicable HR only
(***) The HR or FR → HR inter-zone handover is only possible if the HR eligibility in
the inner zone is allowed by the BTS inside the HANDOVER INDICATION message
(i.e. the radio conditions are sufficient to allow HR).
AMR HR preferred is activated only if the AMR HR service is activated in the target
cell (speechMode parameters of the BSC and cell object).
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INTER CELL HANDOVER
From V18, the following table describes the algorithm used on the reception of a HANDOVER
REQUEST inter-cell (from the MSC or internal BSC) for an AMR call with the target cell in
AMR Based on Traffic congestion conditions (Cell Load State > 0):
AMR Based on Traffic
Inter-BSC and inter-cell intra-BSC incoming handover mediation
Initial Channel type
Handover Cause
HR AMR FR AMR
Uplink quality (*) FR only FR only
Uplink strength (*) FR only FR only
Downlink quality (*) FR only FR only
Downlink strength
(*) FR only FR only
Distance FR only FR only
O&M intervention FR only FR only
Better cell HR preferred HR preferred(**)
Directed Retry FR only FR only
Traffic HR preferred HR preferred(**)
(**) New behavior introduced with AMR Based on Traffic evolution.
(*) Note that this handover causes include following Alarm AMR causes:
• Alarm inter-cell HO for uplink criteria in case of AMR FR channel
• Alarm inter-cell HO for downlink criteria in case of AMR FR channel
• Alarm inter-cell HO for uplink criteria in case of AMR HR channel
• Alarm inter-cell HO for downlink criteria in case of AMR HR channel
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4.22.9 AMR MAXIMIZATION
PRINCIPLE
The aim of this feature is to maximize usage of AMR HR in order to reduce congestion, even if
this objective could lead to potential voice quality degradation. It offers temporarily higher cell
capacity to manage traffic peak
• by disabling the RF checks for HR allocation, i.e. forcing 100% new call in HR
• by disabling fall back in AMR FR for ongoing call
• by forcing all incoming handover in AMR HR whatever the received cause
Area of AMR HR maximization application is configurable through 2 new thresholds in additionto the existing “AMR based on traffic” algorithm (See figure below):
• fullHRCellLoadStart
• fullHRCellLoadEnd.
This function is active as soon as these 2 new thresholds are both different from 100.
In case of modification of one any new parameter, the new value is taken into account at the
next period.
Note that the AMR Half Rate speech mode is a pre-requirement of AMR Maximization.
Without Half Rate capacity allowed, all calls will be allocated in FR mode whatever the cellstate (normal, high traffic or congested).
FR - >HR threshold
Max HR capacity
Max FR capacity
Traffic
24 hourst
Avg Erlang
Number of
allocated TCH
Full rate area
Blocking managed thanks to directed retry
and HO traffic
Blocking managed thanks to directed retry
and HO traffic
HRRCellLoadEnd
-
Max HR capacity
Traffic
24 hourst
Avg Erlang
Number of
allocated TCH
Full rate area
Blocking managed thanks to directed retry
and HO traffic
Blocking managed thanks to directed retry
and HO traffic
Max HR capacity
Max FR capacity
Traffic
24 hourst
Avg Erlang
Number of
allocated TCH
Full rate area
AMR HR based on traffic area
Blocking managed thanks to directed retry
and HO traffic
Blocking managed thanks to directed retry
and HO traffic
AMR HR maximization
HRCellLoadStart
FullHRCellLoadStart
FullHRCellLoadEnd
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AMR MAXIMIZATION ALGORITHM
This filtered erlang defined for AMR based on traffic is also used for AMR maxization
algorithmto. The term congestion period used in the following sentence means cell is in AMR
maximization conditions. Indeed the filtered busy TCH ratio obtained thanks to filtered erlang
formula is then compared to the 2 new thresholds fullHRCellLoadStart and fullHRCellLoadEnd
in order to determine the cell load state therefore the congestion period
If the cell is not in congestion period then
If the Filtered erlang is equal or greater than fullHRCellLoadStart, the cell is at the
beginning of the congestion period:
• Direct Half rate allocation (primo allocation) shall be forced in HR mode.
Note that the AMR HR Direct allocation thresholds remain at their previous value
and will be only updated at the end of congestion state.
• The HR to FR handover shall be deactivated: fall back to AMR FR not possible for
on going AMR HR (see Handover during congestion period). In order to prevent
those handovers, the Extended Current Cell Parameters message is sent to all
DRX with the parameter AMRHRToFRIntracellCodecModeThreshold set to
4.75.This parameter is in the AMR Handover Parameters IEI of the Extended
Current Cell Parameters message.
• all incoming Handover shall be forced to Half rate mode whatever the cause
received in the request of the handover if the MS capability supports the HR mode
(channel type);
• all intra cell handover FR to HR rate mode are authorized for all DRX
• The cell load state continues to be calculated.
Else the HR calls are managed by AMR Based on Traffic algorithm
If the cell is in congestion period then
If the Filtered erlang is lower than fullHRCellLoadEnd: The cell is at the ending of
congestion period.
In order to update the controls of the Handover by the BTS, the Extended Current Cell
Parameters message is sent to all DRX with the parameter
AMRHRToFRIntracellCodecModeThreshold set to MMI value.
If the AMR based on Traffic is activated, the current traffic load (AMR BOT criteria) is
calculated thanks to the cell load state elaborated during the congestion period.
New thresholds are elaborated based on this current load and sent to all DRX
using the Extended Current Cell parameters message. The number of DRX allowing
the FR to HR handover is updated according to the current cell load state value.
Else, the cell stays in congestion period. The cell load state continues to be elaborated
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HANDOVER DURING CONGESTION PERIOD
During AMR maximization period, the MS on an AMR-HR channel should not be handed over
to an AMR-FR resource in the serving cell, that is to say that AMR quality intracell handover
on uplink CMC (Codec mode command) or downlink CMR (Codec mode request) shall be
inhibited setting the AMRHRToFRIntracellCodecModeThreshold to 4.75 codec value. AMR
codec mode adaptation is not impacted as it is not correlated with AMR handovers.
Note that, as the AMR Based on Traffic and AMR Maximization thresholds can be reached at
the same time, the AMR Maximization supersedes the AMR BOT mechanism in case of
conflict.
The following table describes the algorithm used on the reception of a handover request inter
cell (from the MSC in the Handover Request message or internal BSC) for an AMR call.
It is based on the value of channel rate and type and handover cause received in the
Handover Request.
AMR Maximization
Inter-BSC and inter-cell intra-BSC incoming handover mediation
Handover cause
Target Cell in
congestion and
MS supports HR
mode
Target Cell not in
congestion
Uplink quality (**) HR FR only
Uplink strength (**) HR FR only
Downlink quality
(**) HR FR only
Downlink strength
(**) HR FR only
Distance HR FR only
O&M intervention HR FR only
Better cell HRFR only or HR
preferred (*)
Directed Retry HR FR only
Traffic HRFR only or HR
preferred (*)
(*): HR preferred according to the AMR Based on Traffic condition: cell Load
State > 0
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(**) Note that this handover causes include following Alarm AMR causes:
• Alarm inter-cell HO for uplink criteria in case of AMR FR channel
• Alarm inter-cell HO for downlink criteria in case of AMR FR channel
• Alarm inter-cell HO for uplink criteria in case of AMR HR channel
• Alarm inter-cell HO for downlink criteria in case of AMR HR channel
The following table describes the BSC mediation in case of intra-cell handover for an AMR call
with the cell in AMR Maximization congestion state:
AMR Maximization
Intra-cell incoming handover mediation
Handover cause
Target Cell in congestion and
MS supports HR mode
Intracell uplink
HR
Intracell downlink
HR
Capture
HR
Inter-zone HR
Frequency tiering HR
Alarm intra-cell HO (FR => FR) for uplink criteria in
case of AMR FR channelHR
Alarm intra-cell HO (FR => FR) for downlink
criteria in case of AMR FR channelHR
HR => FR HO for uplink criteria in case of AMR HR
channelHR
HR => FR HO for downlink criteria in case of AMR
HR channelHR
Capacity HO (FR => HR) for uplink and downlink
criteria in case of AMR FR channelHR
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AMR MAXIMIZATION INTERWORKING
Since ABOT (AMR Based on Traffic) and AMR maximization can be activated independantly,
the following conditions are required for the ABOT and AMR Maximization thresholds
• In case where both ABOT & Maximization activated i.e hrCellLoadStart <> 100 AND
fullHRCellLoadStart <> 100
Then the following rule must be followed
fullHRCellLoadStart > fullHRCellLoadEnd
fullHRCellLoadStart > hrCellLoadStart
fullHRCellLoadEnd > hrCellLoadEnd
• In case where ABOT not activated & Maximization activated i.e hrCellLoadStart =100
AND fullHRCellLoadStart <> 100Then the following rule must be followed
fullHRCellLoadStart > fullHRCellLoadEnd
• In case where ABOT activated & Maximization not activated i.e hrCellLoadStart <>
100 AND fullHRCellLoadStart = 100
Then the following rule must be followed
hrCellLoadStart >= hrCellLoadEnd
4.22.10 QUEUING HRThe previous Nortel implementation does not allow a direct AMR HR allocation for a call that is
being queued. In V18, the requested AMR-HR from queuing can be served in AMR-HR mode.
Moreover in case of one HR resource is released, an HR request queued should take
precedence over a FR request in same queue (same internal priority) in a cell congested or in
high traffic state. This new functionality is available by default on the V18 software load, no
need to activate the feature.
.
FR requested HR requested
Before V18 BSS version FR FR
AMR Maximization (Congestion period) HR HR
AMR Based On Traffic (cell load state > 0) FR HR
AMR Based On Traffic (cell load state = 0) FR FR
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FEATURE ACTIVATION
A dedicated cell class 2 parameter, enableRepeatedFacchFr , is used to enable the feature by
chosing a codec threshold or to disable the support of Repeated FACCH in each cell.for AMR
FR
Since V18 a new dedicated cell class 2 parameter enableRepeatedFacchHr , is used to enable
the feature for AMR HR calls
MECHANISM OF THE FEATURE
When the Repeated FACCH feature has been enabled on the cell, each time the AMNU entity
needs to re-transmit an I-frame on FACCH due to T200 expiry, it sends this frame again to the
SPU entity (with a flag related to the retransmission). The SPU entity sends first the I-frame on
FACCH in TDMA frame M as it does when the feature is disabled. And if the selected CODEC
is lower than the threshold set to activate the feature, it stores the LAPDm frame to berepeated in TDMA frame M+ 8 or M+ 9 for AMR FR calls (resp TDMA frame M+ 6 or M+ 7 for
AMR HR calls if activated)
When repeating FACCH messages, T200 is started when transmitting the subsequent FACCH
(~ 40 ms later) to cope with the case where an MS fails to decode the downlink FACCH block
used to send the first instance of a repeated LAPDm frame.
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PERFORMANCE
When repeating a frame, the applicable T200 duration is increased by about 40 ms (~20%).
This induces a longer time for drop call detection with T200 mechanism because N200 cannot
be modified.
In addition, a new MS shall soft combine the frames to optimize the decoding probability
whereas legacy mobile will simply see an increased probability of decoding Lapdm frame. The
expected benefit for mobiles using soft combining is about 4 dB gain and about 2 dB gain for
legacy mobiles.
This graph presents the expected benefits on softcombining MS and lecacy MS.
Soft combining gain
Legacy MS gain
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4.22.12 TX POWER OFFSET FOR SIGNALING CHANNELS
In order to increase the signaling channels (FACCH and SACCH) robustness in downlink, BTS
may use a power offset (above the Tx power applicable for speech) to transmit the signalingbursts.
The benefit in term of C/I is depending on the power offset for the signaling robustness and
allows the operator increasing the fractional load and thus the spectrum efficiency. Voice
quality can be still acceptable thanks to the use of robust AMR codec.
PRINCIPLE OF THE FEATURE
The Tx Power Offset for Signaling Channels is applicable to:
• The first transmission of HO COMMAND and ASSIGNMENT COMMAND for all AMRcalls in order to maximize the likelihood of decoding these messages from the first
instance,
• Every re-transmission of I-frame on FACCH for all AMR calls (HR and FR) in order to
maximise the likelihood of decoding these messages.
• Every RR and REJect frame on FACCH corresponding to an uplink retransmission for
all AMR calls (HR and FR) in order to improve the two-ways robustness.
• Every UA (respectively DM) frame on FACCH corresponding to an uplink re-
transmission of SABM (respectively DISC) frames for all AMR calls (HR and FR) in
order to improve the two-ways robustness.
• The transmission of all SACCH frames for AMR FR 4.75 kbps, 5.9 kbps and 6.7 kbps
calls (tunable with an OMC-R parameter) in order to avoid radio link time-out (that
leads to drop calls.
On theses messages a power offset (tunable from the OMC-R) is applied up to the nominal Tx
power.
Note: The power offset applies (up to the nominal Tx power of the BTS) on BTS18000, ecell,
as well as S8000 and S12000 fitted with e-DRX or DRX-ND3. For other BTS hardware, the
feature does not apply. In addition this feature is not applicable on BCCH TRX (PA is alwaystransmitting with Pmax and transmitting power should not fluctuate).
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FEATURE ACTIVATION
This feature is activated at cell level; dedicated class 2 parameters are used to enable/disable
the feature in each cell. The parameters related to tune the feature are the following:
• facchPowerOffset
• sacchPowerOffset
• sacchPowerOffsetSelection
Note: If the BTS hardware (DRX or RM) does not support the signalling offset mode (up to
Pnominal), the facchPowerOffset and sacchPowerOffset provisioning is not considered and
the DRX or RM behaves as it behaves when facchPowerOffset and sacchPowerOffset are setto 0 dB.
FEATURE DESCRIPTION
The Tx Power Offset for Signaling Channels is applicable to different type of message;
hereafter the process for each specific handling:
SPECIFIC HANDLING OF HO COMMAND AND ASSIGNMENT COMMAND
For all AMR calls, these messages are transmitted with the maximum power (considering
facchPowerOffset) from the first instance in order to maximize the likelihood of decoding thesemessages with no LAPDm repetition at all, and therefore avoid as far as possible the drop
calls during (inter-cell or AMR triggered) handover procedure.
Since these messages can be segmented, the power offset applies on all segments: the level
3 entity flags all frames of the HO COMMAND and ASSIGNMENT COMMAND messages then
SPU entity checks this flag in each I-frame to apply (or not) the power offset
(facchPowerOffset) on the transmitted frame.
When applying the power offset,
First case:
IF PWR + facchPowerOffset ≤ Pnominal
THEN
SPU modifies the dynamic power control in accordance with PWR + facchPowerOffset
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Second case:
IF PWR + facchPowerOffset > Pnominal
THEN
SPU set the dynamic power control to: 0 BTS transmits the frame at Pnominal
Note: PWR is the BTS transmit power computed by L1M power control algorithm and
applicable for speech and Pnominal is the BTS Tx power set by the static power control
SPECIFIC HANDLING OF RE-TRANSMITTED I-FACCH FRAMES, RR ANDREJECT CORRESPONDING TO RE-TRANSMITTED UPLINK FACCHFRAMES AND UA CORRESPONDING TO RE-TRANSMITTED SABM ORDM
For all AMR calls, every re-transmission of FACCH frames as well as:
• UA (with F bit set to 1) corresponding to a retransmitted SABM or Disconnect Mode,
• and RR and REJect frames on FACCH (with F bit set to 1) corresponding to an uplink
retransmission of a FACCH frame
are transmitted with the maximum power in order to maximise the likelihood of decoding
these messages and therefore avoid as far as possible the drop calls due to N200 overrun.
The BTS LAPDm entity flags each FACCH frame mentioned here-above then SPU entity
checks this flag and apply (or not) the power offset (facchPowerOffset) on the re-transmitted
frame.
When applying the power offset:
SPU (as describes for HO command and assignment command) either modifies the dynamic
power control in accordance with PWR + facchPowerOffset or set this power control to 0
leading the BTS to transmit the frame at Pnominal.
SPECIFIC HANDLING OF SACCH FRAMES
For AMR calls, depending on sacchPowerOffsetSelection provisioning, the transmission of
SACCH frames for AMR FR 4.75 kbps, 5.9 kbps and 6.7 kbps calls are transmitted with the
maximum power (considering sacchPowerOffset) in order to avoid radio link time-out (that
leads to drop calls) and the drop calls due to N200 overrun (for re-transmission).
For SACCH transmission, SPU entity, according to the last selected AMR CODEC and
sacchPowerOffsetSelection provisioning, applies (or not) the power offset (sacchPowerOffset)on the transmitted bursts.
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When applying the power offset:
First case:
IF PWR + sacchPowerOffset ≤ Pnominal
THEN
SPU modifies the dynamic power control in accordance with PWR +
sacchPowerOffset
Second case:
IF PWR + sacchPowerOffset > Pnominal
THEN
SPU set the dynamic power control to: 0 BTS transmits the frame at Pnominal
Note: Correction of RxLev (to remove the impact of the power offset on Tx power control
mechanism) can be approximated by SPU entity and conveyed to the L1m. In another hand,
correction of CMR is not possible since BTS does not have the SNR info from MS. The impact
on the choice of AMR CODEC cannot be by-passed see [R36]
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ENHANCEMENT OF AMR POWER CONTROL MECHANISM
Since this feature improves the downlink robustness, new parameters are introduced to define
dedicated target for uplink and downlink AMR CODEC.
The existing parameters (hrPowerControlTargetMode and frPowerControlTargetMode) still
apply on uplink and two new parameters are introduced for downlink targets:
• hrPowerControlTargetModeDl: downlink AMR codec target to define the downlink
power control threshold for HR AMR calls,
• frPowerControlTargetModeDl: downlink AMR codec target to define the downlink
power control threshold for FR AMR calls,
With setting a lower codec as a Downlink Power control target:
• A more protected AMR speech codec is used in downlink,
• Overall BS attenuation is higher and the overall interference level is decreased
accordingly.
So, in poor radio condition, the transmission power for signaling burst may stay identical
thanks to the Power offset while interference level has decreased.
Since the low target codec for Downlink Power control cannot be reached if the RxLev Power
control threshold limits the BS attenuation and if the Tx Power Offset for Signaling Channels
feature is enabled, lRxLevDLP for AMR communication is set to:
LRxLevDLP - min (facchPowerOffset, sacchPowerOffset).
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4.23. WPS - WIRELESS PRIORITY SERVICE
The current United States industry focus in support of National Security and Emergency
Preparedness telecommunications services is to specify the requirements for Wireless Priority
Services. The initial deployment of WPS is intended to allow qualified and authorized NS/EP
users to obtain priority access to radio traffic channels during situation when Commercial
Mobile Radio Service (CMRS) network congestion is blocking call attempts.
WPS is intended to facilitate emergency response and recovery operations in response to
natural and man-made disasters and events, such as floods, earthquakes, hurricanes, and
terrorist attacks. WPS is also intended to support both national and international emergency
communications.
4.23.1 PRINCIPLE
If a Service user invokes WPS (Wireless Priority Service) and no radio traffic channel is
available in the cell, the WPS request shall be queued according to the WPS priority, the call
initiation time and the state of the queue for the cell.
This feature is an improvement of the queuing services available to WPS users.
The WPS queuing principle is the following:
• The eight (8) current queues are kept unchanged
• Five (5) new queues are added an dedicated to WPS request
For public queue management and related parameters, refer to chapter Queuing.
4.23.2 WPS – QUEUING MANAGEMENT
The new queuing management of WPS requests is activated when queuing is driven by the
MSC (bscQueuingOption parameter is set to “allowed”) and WPS management is activated
(wPSManagement parameter is set to “enabled”)
CAUTION!
The bscQueuingOption is a class 1 parameter, which means that parameter can be set only
when the parent bsc object is locked.
It is important to underline that the internal queues associated with WPS requests and the
internal queues associated with public requests are treated in completely separate ways.
CHARACTERISTIC OF THE WPS QUEUE
Each WPS queue is defined with:
• Its associated priority Pi
• Its queue size Ni, the maximum number of WPS call requests (of priority Pi or
higher) which can be queued simultaneously
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• Its own T11 timer value, which represents the maximum time a WPS call
request of a given priority Pi can remain in queue
The priority Pi is received from the MSC in the assignement request message.
The size Ni of a given WPS queue is set according to the allocWaitThreshold parameter. Inorder to be in accordance with the WPS industry requirement and configuration, each queue
size threshold Ni (with 8< i <12) should be equal (N8=N9=N10=N11=N12) and equals the
maximum number of WPS requests allowed in the WPS queues.
The timer T11 for a given queue can be defined with the allocPriorityTimers parameter. It is
understood that the request will immediately be denied with a cause “no radio resource
available” if this timer is set to “0”.
PROCEDURE TO QUEUE SERVICE REQUEST USER WPS
FIRST CASE: MS IS PUT IN QUEUE
As no radio channel is available, and as the queue size threshold Ni of the queue
corresponding to the WPS priority Pi is not reached, the WPS call request is put in queue i. A
queuing indication message is sent to the MSC.
SECOND CASE: MS IS DENIED (QUEUE FULL)
As no radio channel is available, and as the queue size threshold Ni of the queue
corresponding to the WPS priority Pi is reached, the WPS call request is denied. An
assignement failure message with cause “no radio resource available “is returned to the MSC.
THIRD CASE: MS IS PUT IN QUEUE TAKING THE PLACE OF AN OTHERMS
As no radio resource is available, if the queue size threshold Ni corresponding to the WPS
priority Pi is not reached, but if adding the call request to queue i would cause the threshold Nj
of another internal WPS queue j to be violated, and if the WPS request priority (Pi) is higher
than at least one WPS request (Pk) already in queue in the cell, the BSS takes the following
actions:
• the BSS shall remove the WPS request with the lowest priority (Pk) and the
most recent initiation time from the queue. It sends an assignment failure forthis removed WPS request with the cause “no radio resource available”.
• the BSC shall place the newly arrived WPS request in the queue i according
to the initiation time and the priority level.
A queuing indication for the WPS call request of priority Pi and an assignement failure for the
WPS call request of priority Pk are sent to to the MSC.
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MANAGEMENT OF SERVICE REQUEST USER WPS PUT IN QUEUE
RESOURCE AVAILABLE
If a radio traffic channel becomes available when there are WPS requests in queue, the
process of ressource allocation decribed in the WPS – Public access bandwith protection
(see chapter WPS – Public access bandwith protection below) has to be followed.
T11 EXPIRY
If the WPS request is in queue i for a radio traffic channel and the maximum time allowed for
that queue expires, the WPS request is removed from the queue and the call is cleared. A
clear request with the cause “no radio resource available” is then sent to the MSC.
RADIO CONTACT WITH THE MS IS LOST
If the WPS request is in queue for a radio traffic channel but radio contact with the mobile is
lost (detected by the BTS which informs the BSC), the WPS request is removed from the
queue and the call cleared. A clear request with the cause “Radio Interface Failure” is sent to
the MSC.
MS DISCONNECTS THE CALL
If the MS decides to disconnect the call while the WPS request is queued, the BSC receives a
clear command message from the MSC and processes the release of the call including the
request removing from the WPS queue.
FEATURE ACTIVATION
If the bscQueuingOption parameter is set to “not allowed” then queuing is not performed, i.e.
no request goes into any of the queues 0 to 12, whatever the wPSManagement value is. In all
the following cases, the bscQueuingOption flag is considered as “allowed (MSC driven)”.
One has to well understand the two levels of queuing in “MSC Driven” queuing mode:
• At the MSC level the call request is described by two fields in the assignement
request message: “queuing allowed” set to allowed / not allowed, and “priority
level” (14 are defined)
• At the BSC level the queuing management of the call requests is set to
allowed, so the BSC takes into account the 2 fields described above
WPS queuing is so done according both to the “queuing allowed” field value set in the
assignment request message sent by the MSC (if this field value is set to “queuing not
allowed”, then there is no queuing) and the WPS priority (1 to 5).
In all the following cases, this field value is considered as “queuing allowed” for all WPS and
public call requests.
WPSMANAGEMENT FLAG IS ENABLED
The WPS request is queued according to the mapping (GSM 08.08 priority / internal priority)
done by the customer at the OMC-R.
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Internal priorities correspond to the queues 0 to 7 for public requests, and queues 8 to 12 for
WPS requests.
When the wPSManagement flag is enabled, a recommended mapping of the allocPriorityTable
has to be respected.
When the wPSManagement flag is turned on, it also enables the PURQ AC algorithm feature.
(see chapter WPS – Public access bandwith protection below)
WPSMANAGEMENT FLAG IS DISABLED
It is recommended that the customer sets the mapping (GSM 08.08 priority / internal priority)
at the OMC-R, so that only internal priority 0-7 are used when the wPSManagement flag is
disabled. In this case, if a WPS request is received by the BSC, the request will be managed
like a public call since it will be queued in the public queues.
If no mapping is specified by the customer, the default mapping is done to the internal queue
0.
4.23.3 WPS – ACCESS CLASS BARRING WITH CLASS PERIODICROTATION
In normal conditions, the number of WPS Users should be sufficiently small that there is little
likelihood of them having a significant impact on public use. But in case of exceptional events,
the number of initial access is dramatically increased and can induce a full blocking of the
system.
In V9, a feature called "access class barring" was designed in order to avoid this kind ofproblem, thanks to a dynamic barring of a significant part of users. An enhancement of this
feature has been designed, in order to allow users to access periodically to the network,
without huge network congestion.
To synthesize, one can say that this feature allows users to access the network periodically
during network congestion by modifying the number of barred access classes in function of the
congestion state of the cell, and by periodically changing which access classes are barred.
There are no specific access class parameters that can be tuned in order to optimize WPS
use.
For further details about this change of access class baring, see chapter Barring of access
class.
4.23.4 WPS – PUBLIC ACCESS BANDWITH PROTECTION
The public access bandwidth protection is required in case of cell congestion with WPS users
in the cell. Assuming that the number of WPS users is less important than public users, and
taking into account that WPS users are priority users, this feature ensures that a radio network
bandwidth is available to public users during cell congestion (lack of radio resources).
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PRINCIPLE
The idea of the algorithm is to allocate a specified portion of the traffic channels (as they
become free) with preference to public calls, and to allocate a second portion of the traffic
channels (as they become free) with preference to WPS calls.
The BSC radio resource allocator processes the algorithm which favors WPS calls 1 out of
wPSQueueStepRotation times and then process the algorithm which favors public calls P out
of wPSQueueStepRotation times (P = wPSQueueStepRotation – 1).
With this choice, 1 out of wPSQueueStepRotation of the call capacity can be allocated for
WPS users, wPSQueueStepRotation being 1,2, …,10. (recommended value is 4 and hence
25% can be allocated with preference to WPS requests)
PURQ-AC ALGORITHM WITH SUPERCOUNT
PURQ-AC stands for Public Use Reservation for Queuing - All Calls
This algorithm is only activated if If the wPSManagement flag (BSC level) authorizes the WPS
requests management
When the algorithm is turned on (i.e at the startup of a BSC or after a lock/unlock of the cell),
the priority is given to a WPS call request (1 out of wPSQueueStepRotation times), the
algorithm proceeds to some checks about the state of the WPS queues (left side on the
schema below), then the priority is given to public call requests (P out of
wPSQueueStepRotation times) and the algorithm proceeds also to some checks about thestate of the WPS queues (right side of the schema below).
The aim of the supercount is to allow “10 call running deficit” over allocation, and enhanced
small cell performances. It smoothes out short term variations, and decreases delay. The
Supercount tigger value of 10 is a fixed value. Supercount is initialised to 0 and is reset to 0
when a lock/unlock action is done on the cell for instance.
FEATURE ACTIVATION
If the wPSManagement flag (BSC level) is disabled but queuing indications in the assignement
request message still give the priority to WPS call requests, in case of cell congestion, theWPS users may use all the cell bandwidth (due to their priority) and public users may not have
an access to the network. However that case could only occur if WPS queues are mapped on
internal queues 0-7 instead of the queues dedicated for WPS, because only internal queues 0-
7 are evaluated to serve a queued request when wPSManagementFlaf is turned off. The new
algorithm has a cell based internal management that does not impact any other cells in term of
traffic management.
This feature is linked with the queuing management (public and WPS requests) and hence
parameters related to the queue management have to bet set in order to take advantage of
the benefits provided by the PURQ AC algorithm.
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4.24. SATELLITE ABIS INTERFACE
The use of Satellite Abis links will be possible to allow the connection between BSC and BTS.
In some network areas, there is no earth terrestrial transmission infrastructure between the
BSC and the BTS. This feature solves this problem thanks to a satellite link between these 2
nodes.
To get detailed information about the implementation of this feature, please refer to document
[R31].
More details on recommended parameter associated to feature restrictions are given in the
Satellite Abis Interface - Engineering Guideline (refer to document [R32])
BSCBTS
Abis
Abis
Agprs
Ater BTS
Abis
BSCBTS
Abis
Abis
Agprs
Ater BTS
Abis
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4.25. NETWORK SYNCHRONIZATION
4.25.1 GLOBAL DESCRIPTION
ASYNCHRONOUS NETWORK
When NW synchronization is not applied (asynchronous network), cells get their time base
through the PCM time. As PCM of different cells are not correlated, it can be considered that,
comparing to the hypothetical network time reference, the not co-site cells have on a site
basis:
• Random time bit offsets (from 0 to 156,25)
• Random time slot offsets (integer from 0 to 7)
• Random frame numbers offsets (integer from 0 to 2 715 647).
Consequently, as shown in the figure below, between two not co-site cells there are random:
• Δtime bit offsets
• Δtime slot offsets
• Δframe numbers offsets
General case of non synchronization
It has to be noted that a MS computes - using its timebase counter - the time offset by
measuring the time from the beginning of TS0 on its BCCH carrier and the beginning of the
first TS0 on a neighbor BCCH carrier. Also, the data found on these 2 TS0 may be used for
calculating the FNOffset between its cell and the neighbor cell.
7
FN x-1
0 1 3
FN x FN x FN x
4
FN x
5 6
FN x FN x
5
FN x-1
6
FN x-1
0
FN y
1 2 3
FN y FN y FN y
4
FN y
5 6 7
FN y FN y FN y
7
FN y-1
cell 1
cell 2
Δ time bit offset (random)
Δ time slot offset
(random)
Δ frame number offset = y-x
(random)
7
FN x-1
0 1 3
FN x FN x FN x
4
FN x
5 6
FN x FN x
5
FN x-1
6
FN x-1
0
FN y
1 2 3
FN y FN y FN y
4
FN y
5 6 7
FN y FN y FN y
7
FN y-1
cell 1
cell 2
Δ time bit offset (random)
Δ time slot offset
(random)
Δ frame number offset = y-x
(random)
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Consequently, see general case of synchronization figure on previous page, between two not
co-site burst synchronized cells there are:
• Δtime bit offsets = 0• Random Δtime slot offsets
• Random Δframe numbers offsets
As in the case of an asynchronous network, the co-site cells have the same time bit offsets,
time slot offsets and frame number offsets.
TIME SYNCHRONIZED NETWORK
In a time synchronized network, it can be considered that, comparing to the hypothetical
network time reference, the not co-site cells have on a site basis:
• Time bit offsets = 0
• Known & controlled time slot offsets
• Known&controlled frame numbers offsets
Also, similar to the asynchronous network, the co-site cells have the same time bit offsets,
time slot offsets and frame number offsets.
Consequently, see general case of synchronization figure on previous page, between two not
co-site time synchronized cells there are:
• Δtime bit offsets = 0
• Known & controlled Δtime slot offsets• Known&controlled Δframe numbers offsets
It has to be noted that the main difference between a time synchronized and a burst
synchronized network is that time slot offset planning and frame number offset
planning are possible only in a time synchronized network.
4.25.2 FEATURE ACTIVATION
The parameters related to tune the feature are the following:
• btsSMSynchroMode
• tnOffset,
• fnOffset
• masterBtsSmId
Note: Other network existing parameters may have a significant impact on network
performances when network synchronization is applied:
• baseColourCode TSC (TSC=BCC) planning and therefore whole BSIC (NCC&
BCC) planning.
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• Hopping laws parameters (HSN, MAIO, MA list)
• dARPPh1Priority
Also, it has to be noted that more parameters (for handovers, location services etc…) may
have to be eventually retuned for an optimal functioning when network synchronization feature
is deployed.
4.25.3 FEATURE IMPACTS EXPECTATIONS
Network synchronization simple deployment may have positive impact on location services as
the location precision will improve with a better synchronization of the network elements.
However, synchronizing all BTS in a network, meaning synchronizing interferers and their
victims, doesn’t provide alone any gain of RF quality or RF capacity. On the contrary, thenetwork synchronization may degrade the network RF performances if no additional feature or
engineering solution is applied. (The main degradation is mainly due to the eventual TSC
collisions if a traditional BSIC -NCC/BCC- planning as for an asynchronous network is used)
Therefore, for improving the RF quality and capacity, a network synchronization deployment
must be accompanied by additional features and significant engineering parameter planning.
Please refer to chapter Network synchronization engineering planning methodologies.
After Activing NW synchronization significant modifications of the NW behavior may occur at
various levels:
• Quantity of interferences:
being able to control cell FN Offsets, it may be possible to use some
carefully chosen of hopping laws (HSN, MAIO, MA list, FN) in order to
decrease the collision probability between one or more couples of cells
being able to control cell TN and FN Offsets, it is possible to completely
avoid the collisions between two cells which are not co-site when using a
fractional reuse frequency plan
Note: all this eventual control of the quantity of interferences is possible only
when time synchronizing the network as it is required to control and plan the
FN Offsets (and TN Offsets as well);
• Impact of interferences:
the various features of interferences cancellation and noise cancellation for
both BTS and MS are expected to work optimally (or better) when
synchronizing the network
• Others
HO reactivity, LCS precision …
Please refer to Network Synchronization handbook [R34] for a complete Impact, engineering
rules and KPI Results presentation.
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4.26. NOVEL ADAPTIVE RECEIVER
4.26.1 PRINCIPLE
This v17.0 feature introduces a novel digital processing approach developed by Nortel
Networks for improving reception performances of GSM and EDGE radio communications. It
has been developed to enhance performances in real radio conditions (multipath profiles), with
a particular focus on interference from other radio channels (a major cause of disturbance for
reception performances).
Usual reception schemes are optimal under one specific noise assumption only, basically
thermal noise. However, digital communication faces in practice other noise sources, namely
adjacent channel and/or co-channel interferences, the statistics of which strongly differ from
thermal noise. The consequence is lower reception performances in presence of interferers,
leading to a poorer speech quality or lower throughput for the end-user. The approach
developed by Nortel consists in a scheme that adapts itself to the interference condition
affecting each received burst. In addition, a new filter design strategy has been developed in
order to come out, for each basic noise situation, with a filtering process yielding the minimal
BER.
This new method calls, prior to processing the burst, for an estimation of the noise situation.
This is achieved by a filter bank detector for the adjacent interferers; co-channels interferences
are taken into account later on, after channel sounding. According to the adjacent interference
noise estimated by the detector, a filter matching the noise situation is designed and applied to
the current burst.
Reception performance is significantly improved in most situations, especially with adjacent
interference conditions.
These benefits apply both to GMSK and 8PSK modulations, traffic and data applications. It
thus provides the end-user with an increased throughput for data transmission as well as an
improved quality of service for voice calls.
For more details, please refer to the Functional Note ([R45]).
4.26.2 HW/SW DEPENDENCE
This feature is applicable to :
• Hardware : BTS 6000/BTS18000 Radio Modules, 1900 MHz band only
• Software : v17.0 release.
4.26.3 ACTIVATION GUIDELINES
O&M PARAMETER
adaptiveReceiver is a new Class 2, transceiver object, parameter that serves to activate or
deactivate the Novel Adaptive Receiver. It can take two values :
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• “enabled” : use of the Novel Adaptive Receiver
• “disabled” : use of the legacy signal processing
RECOMMENDATIONS
HILLY TERRAIN PROFILES
For cells operating under very specific radio conditions, namely hard Hilly Terrain profiles, the
Novel Adaptive Receiver structure may possibly cause a slight performance loss compared
with the initial processing. Therefore, it is recommended to disable the adaptive receiver for
these cells. :
adaptiveReceiver = disabled
INTERWORKING WITH RX DIVERSITY
If Rx diversity is used, best receiver performance is achieved by activating both Joint diversity
and Novel Adaptive Receiver features :
adaptiveReceiver = enabled; diversity = enhancedDiversity.
INTERWORKING WITH EXTENDED CELL
Novel Adaptive Receiver does not interwork with the Extended Cell feature.
Therefore, for extended cells, the Novel Adaptive Receiver must be deactivated :
adaptiveReceiver = false.
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4.27. A5/3 ENCRYPTION ALGORITHM
4.27.1 PRINCIPLE
For details, please refer to the Functional Note ([R41]).
PURPOSE OF THE FEATURE
Before v17.0, the only available encryption algorithms available in the BSS were :
• No encryption
• Encryption algorithm version 1, also called A5/1
• Encryption algorithm version 2 (also called A5/2). A5/2 was removed from the GSM
networks at the end of 2006 in compliance with the 3GPP recommendations, as a
consequence of the published attacks against A5/2.
This v17.0 feature provides a new encryption algorithm in the BSS called A5/3.
Also, this feature changes the class of the existing parameter encryptAlgorSupported from
class 0 to class 3 to limit service disruption when changing its setting.
A5/3 ALGORITHM OVERVIEW
The A5/3 algorithm is stream cipher that is used to encrypt/decrypt blocks of data under a
confidentiality key Kc. The algorithm is based on the KASUMI algorithm, which is specified in3GPP TS 35.202. KASUMI is a block cipher that produces a 64-bit output from a 64-bit input
under the control of a 64-bit ciphering key.
4.27.2 HARDWARE DEPENDENCE
A5/3 is supported on :
• DRX ND3
• eDRX
• RM.
4.27.3 CIPHERING ACTIVATION RULES
BSS PARAMETERS
ENCRYPTION ALGORITHM ACTIVATION
The BSS can select A5/3, on MSC request, for a call, assuming that :
• A5/3 is supported by the TRX
• A5/3 is supported by the mobile
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• A5/3 is configured at the O&M level as the preferred encryption algorithm in the BSS
Since the A5/3 encryption algorithm is neither supported by all types of TRX nor by all
mobiles, and more especially by legacy mobiles already deployed by the operators, a fallback
encryption algorithm needs to be available whenever the A5/3 encryption algorithm is
requested by the MSC. In such a case, based on the value of the O&M parameter
encryptAlgorSupported , either “no encryption” or “A5/1” may be defined at O&M level as the
fallback encryption algorithm to be used by the BSS.
The encryptAlgorSupported parameter is an existing parameter which has been modified in
v17.0 as follows :
• The class is changed in v17.0 from class 0 to class 3. Thus, no BDA build is
necessary when changing the value of this parameter : no interruption of service
• The range of values has been expanded and now includes the following values :
o “None” : the BSS will not cipher any calls
o “gsmEncryptionV1” : all the BTS of the BSS will use A5/1 for ciphering, if
requested and allowed by the NSS
o (new value) “gsmEncryptionV3FallbackNoEncryption” : A5/3 is the preferred
algorithm for the BTSs of the BSS, but if this algorithm cannot be used for a
specific call in a specific cell (due to mobile capability limitation or TRX
capability limitation or MSC request), the BSS will not cipher the call
o (new value) “gsmEncryptionV3FallbackV1” : A5/3 is the preferred algorithm
for the BTSs of the BSS, but if this algorithm cannot be used for a specific callin a specific cell (due to mobile capability limitation or TRX capability limitation
or MSC request), the BSS will attempt to use A5/1 instead.
BSSMAP MESSAGES CONFIGURATION PARAMETERS
With a Nortel BSS supporting the A5/3 feature, the NSS must be able to understand ciphering
information fields conveyed by the BSS to the NSS in the following BSSMAP messages :
• CIPHER MODE REJECT
• ASSIGNMENT COMPLETE
• HANDOVER PERFORMED
• HANDOVER REQUEST ACKNOWLEDGE
• CIPHER MODE COMPLETE.
Today (2007), all NSS software on the market supports these messages. Therefore, these
BSSMAP messages and fields must be enabled on the BSS side, otherwise the BSS will not
send them to the NSS, and this risks causing the ciphering procedure to operate in a less-
than-optimal manner.
To prevent this happening, the following BSS parameters must be set to value “true” :
• cypherModeReject
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• encrypAlgoAssComp
• encrypAlgoCiphModComp
• encrypAlgoHoPerf
• encrypAlgoHoReq
• layer3MsgCyphModComp
NSS PARAMETERS
A5/3 is supported by the NSS Nortel since GSM07 by feature AD8028.
A5/3 is datafilled in the MSC by setting the following Office Parameters :
• GMSC_CIPHERING (OFCOPT table) : enables ciphering and deciphering of the radio
interface control between the MSC and the radio network subsystem (RNS) for the
transmission of user data or confidential network parameters.
• GSM_CIPHER_ALGORITHM_SUPPORTED” (OFCENG table) : indicates which GSM
ciphering algorithms are supported, in addition to the “no” encryption option. There are
seven defined algorithms (A5/1, A5/2, A5/3, A5/4, A5/5, A5/6, and A5/7).
4.27.4 PERFORMANCE IMPACT
BTS PROCESSING TIME
The ciphering processing time of the A5/3 encryption algorithm is not degraded compared to
the A5/1 processing time inside the BTS.
CALL SETUP TIME
On the other hand, since the “ciphering mode setting field” may be included in the Radio
Interface ASSIGNMENT COMMAND message, adding 1 byte, the BSS may need to send an
additional frame on the radio interface SDCCH channel in case the existing frame is already
full without this field. This additional frame could lead to 235 ms additional delay at the call
setup.
HANDOVER DURATION
In the same way, since the “ciphering mode setting field” may be added in the Radio Interface
HANDOVER COMMAND message, adding 1 byte, the BSS may need to send an additional
frame on the radio interface dedicated channel in case the existing frame is already full without
this field. This additional frame could lead to 235 ms (handover on SDCCH) or 20 ms
(handover on TCH) additional delay during the handover.
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4.28. BTS SMART POWER MANAGEMENT
4.28.1 DEFINITIONS
Several definitions will be used in this section :
• Configured TRX : TRX that is mapped to a TDMA. The state of a configured TRX’s PA
depends on whether the TRX is active or idle (see definitions below) and on the
circumstances.
• Unconfigured TRX : transient state of the TRX that exists while the TRX has not yet
received the “current cell parameters” from the BTS
• Deconfigured TRX : state of a TRX that exists after having received a “clear config”
command from the BTS
• Spare TRX : TRX that is not mapped to a TDMA. The PA of a spare TRX may be in
state “ON” or state “OFF” depending on the circumstances, as explained in what
follows.
• Active TRX : configured TRX that is being used by signaling or traffic on at least one
of the TDMA’s radio timeslots. The PA of an active TRX is always “ON”.
• Idle TRX : configured TRX whose TDMA is not currently carrying any ongoing traffic or
signalling. The PA of an idle TRX may be in state “ON” or state “OFF” depending on
the circumstances, as explained in what follows.
4.28.2 PRINCIPLE
This feature permits to reduce BTS power consumption by automatically switching the PA off
when no circuit communication is on-going.
On BTS 18000 family, the PA can be switched OFF or ON thanks to an electronic
switch. This switch can be set to ON or OFF by software, thanks to a dedicated new
TX firmware function.
On S8000 and S12000 BTS, the PA RF part can be switched OFF or ON thanks to a
firmware command.
PA switching off can be managed in two different ways, depending on RM hardware:
• Regular smart power management feature: the PA is switched off when no circuit
communication is on-going on the TRX for a configurable time. PA is automatically
switched on as a circuit communication establishment begins
• Enhanced smart power management feature: the PA is switched off per timeslot
when there is nothing to be emitted for the timeslot.
Enhanced smart power management is only available for BTS 18000 families on RM
equipped with PA Andrew. It is not available on RM equipped neither with PA
Powerwave nor on BTS S8000 or S12000.
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When the TRX receives the current cell parameter message activating smart power
management, it activates either “regular” or “enhanced” feature depending on type of
activation requested by the operator.
If enhanced feature is requested on a non compatible PA hardware, regular feature is
activated by the TRX in place. When enhanced feature is activated, the “timing before
PA switching OFF” parameter is ignored by the TRX.
• On BTS 18000 family, if the RM is equipped with PA Andrew, both regular and
enhanced features are supported.
• On BTS 18000 family, if the RM is equipped with PA Powerwave, only regular
smart power management is supported.
• On BTS S8000 and S12000, only regular smart power management is supported.
Note:
• For BTS 18000 families, if some RM is equipped with PA Andrew and
other are equipped with PA Powerwave, enhanced feature can be
activated on RM with PA Andrew, while regular feature is activated on
RM with PA Powerwave.
• If enhanced feature has been requested at MMI on a non compatible
PA, the BTS does not notify the OMC that regular feature has been
actually activated on the TRX in place.
• The "enhanced" feature behavior is not compatible with the PA
Powerwave switching time; this is the reason why it is only availableon RM with PAs Andrew.
4.28.3 BTS BEHAVIOR BEFORE FEATURE INTRODUCTION
Before v17.0, the BTS behaviour is the following:
When the TRX restarts (BTS start up, TRX lock/unlock, TRX trap …) the PA is in an un-
powered state. It remains un-powered until it has received an RF Trans message from the
BSC.
Once the PA has been powered on, it remains so until the next reset or lock of the TRX.
This behaviour applies to all TRX regardless of their state:
• configured TRX (by definition, a configured TRX is mapped to a TDMA),
• spare TRX (by definition, a spare TRX is not mapped to a TDMA)
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4.28.4 REGULAR SMART POWER MANAGEMENT BEHAVIOR
FEATURE DEACTIVATED
CASE OF CONFIGURED TRX
In v17.0, if the feature is deactivated, the TRX behaves as before v17.0.
CASE OF SPARE, UNCONFIGURED OR DECONFIGURED TRX
The feature cannot be activated on a spare, unconfigured or deconfigured TRX. However, the
behaviour has been modified between v16.0 and v17.0 so that a spare or unconfigured or
deconfigured TRX is systematically switched off after a certain time For this, a 30 second
internal timer is started when the “enable TRX procedure” (RF Trans un-configuring) is
performed. When this timer expires, if no TDMA has been configured on the TRX, the PA is
switched off and its display hardware state is set to “OK – OFF cause
SmartPowerManagement”
As soon as the TRX is configured with a TDMA, this PA will be switched on.
FEATURE ACTIVATED
CASE OF TRX CONFIGURED WITH SPECIFIC TDMA
The TRX that are mapped to specific TDMA configurations are not allowed to turn off their PA.
The feature, even if it is activated, does not apply to them. These TDMA configurations are the
following:
• TDMA containing a BCCH channel
• TDMA containing a combined BCCH/SDCCH channel without CBCH
• TDMA containing a combined BCCH/SDCCH channel with CBCH
• TDMA containing a non-combined SDCCH/8 channel with CBCH channel
• TDMA containing a pDTCH channel
ALL OTHER CASES OF CONFIGURED TRX
For all other configured TRX whose TDMA is not in one of the above categories, if the feature
has been activated, the TRX automatically switches its PA OFF after the TDMA has been idle
a certain amount of time (configurable timer). The TRX switches its PA on again when a
channel is activated on the TDMA for a circuit-switched call establishment or for an incoming
handover.
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More precisely :
• when the BTS receives a channel activation message from the BSC :
o If the PA had been switched off, it is switched back on. PA hardware state is
set to OK (or KO).
o If the PA is still on but the TRX is idle, meaning that the smart Power Switch-
Off timer is running, then this timer is immediately stopped.
• when the BTS receives a channel release message from the BSC : if there are no
more ongoing circuit-switched calls on the TRX (TRX has become idle), the
countdown of the smart Power Switch-Off timer is started.
The fact that the PA is switched off has no impact on the TRX operational state : the TRX
remains in the “in service” state.
The PA switching off has no impact on the TRX receive chain.
CASE OF SPARE TRX
The feature does not operate on a spare, unconfigured or deconfigured TRX, even if the
feature is activated on the cell.
However, the behaviour has been modified between v16.0 and v17.0 so that a spare,
unconfigured, or deconfigured TRX is systematically switched off, regardless of the activation
or deactivation of the smart power management feature. For this, a 30-second internal timer is
started when the “enable TRX procedure” (RF Trans un-configuring) is performed. When this
timer expires, if no TDMA has been configured on the TRX, the PA is switched off and itsdisplay hardware state is set to “OK – OFF cause SmartPowerManagement”
As soon as the TRX is configured with a TDMA, it ceases to be a spare, unconfigured or
deconfigured TRX and its PA will be switched on.
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4.28.5 ENHANCED SMART POWER MANAGEMENT BEHAVIOR
Once the “enhanced” feature has been activated, the PA is switched off as soon as there is
nothing to emit during at least two consecutive Timeslots. It is switched on as soon as somesignal has to be sent again.
There is no signal to emit on one timeslot in the two following cases:
• No communication is on-going on the timeslot,
• One communication is on-going on a TCH timeslot but the communication is on DTX
(during silence, no signal is emitted). It is considered that a communication is on DTX
during 50% of the time.
TCH timeslot may be switched off during DTX period while a communication is on-going.
At reception of current cell parameter message activating the feature, the RM (with PA
Andrew) applicative software activates the enhanced feature in the firmware. The PA
switching off and switching on are then managed by the firmware this way:
The firmware knows two timeslots in advance if there is some signal to emit or not.
If nothing has to be emitted (for at least two consecutive TS), the firmware switches the PA off
at the beginning of the first “idle” timeslot. Once PA is switched off, when there is some signal
to emit again, the firmware switches the PA on one timeslot in advance, so that the PA is
switched on at the beginning of the timeslot to emit.
As a consequence, if there are N consecutive idle timeslots, the PA will be effectively switched
off during N-1 timeslots. PA can only be switched off if there are at least 2 consecutive idle
timeslots. It is called “timeslot switching off”.
As PA switching off and on is managed per Timeslot when there is some signal to emit or not,
the enhanced feature can be activated on all the TDMA, whatever the type of channels
configured on the TDMA. BCCH and combined BCCH TDMA will never be switched off
because its Timeslots are never idle; TRX supporting combined BCCH, SDCCH/8 used for
CBCH or PDTCH channel will switch its PA off when there are idle timeslots.
4.28.6 HARDWARE DEPENDENCE
This feature is applicable to RM family only.
4.28.7 ACTIVATION GUIDELINES
O&M PARAMETERS
ACTIVATION PARAMETER
This feature is activated thanks to a BSS parameter called smartPowerManagementConfig :
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• Class 3
• object : powercontrol
• range : “disabled”; “enabled”; “enhanced”;
POWER SWITCH-OFF TIMER
Once the regular feature has been activated, when the TRX has detected its PA has to be
switched off, it is not done immediately but after a “confirmation time” configured at the OMC.
Once the enhanced feature has been activated, the PA is switched off as soon as there are
two consecutive idle timeslots; no timer is managed in that case. When enhance feature is
active no timer is started or stopped until the feature is deactivated.
When it is used, the “confirmation time” is managed thanks to smartPowerSwitchOffTimer
• Class 3
• Object : powercontrol
• range : 5 to 255 minutes
At TRX start up it is initialized at 30 s default value. It is set to smartPowerSwitchOffTimer at
reception of regular feature activation (current cell parameter message, if feature can be
activated on TDMA). It is set to non significant value at reception of enhanced feature
activation.
It is reset to 30 s default value at TRX reset, and at clear config.
RECOMMENDATIONS
CONFIGURATION OF LOGICAL CHANNELS ON TDMA
At radio TS configuration, if BCCH, combined BCCH (and SDCCH/4 or not), SDCCH/8 used
for CBCH channel, or PDTCH channel is configured on the TRX, the regular feature cannot be
activated on the TRX. Enhanced feature can be activated on any type of TDMA.
, As TDMAs that carry BCCH, SDCCH or pDTCH are never switched off when using regular
feature it is recommended to collect these channels as far as possible on the same TDMA
rather than spread them onto several TDMAs or not to configure more pDTCH than are strictly
necessary.
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MINIMUM TIMER VALUE
On BTS family 1800 (without the feature), if there is no call on a TRX for 5 minutes at least,the VVA consign of the PA is reduced by 2 dB.
The aim is to avoid untimely a “high current” alarm when the PA starts transmitting again after
a while without transmission. Such an alarm could occur if the PA gain, which depends on the
VVA consign, is not consistent with the “new” temperature of the PA when it starts transmitting
again (temperature goes down when PA stops transmitting).
With the “smart power management” feature activated, the temperature will fall all the more
as, on top of not transmitting, the PA is actually completely switched off. Moreover, this “off”
state may last the whole night causing even further temperature drop.
Therefore, before a PA is switched off, it is vital that the VVA consign should have been
reduced by 2dB so that when the PA is switched back on again, there are no high current
alarms. To ensure this VVA is reduced by 2dB, as explained above, 5 minutes must elapse
after the last call on the TDMA has been released. If the smart power timer is less than 5
minutes, the PA would be switched off before a VVA consign reduction cpuld be applied. So,
when the PA is switched back on again, it will apply the old consign corresponding to a high
temperature, whereas the PA will have significantly cooled down. This risks triggering an
alarm ans dpossibly damaging the PA.
To prevent this, the smart power swicth off timer minimum value has, by design, been set to 5
minutes.
In case enhanced feature is active, if the PA is switched on then off in the same frame,temperature variation will be low enough to remain compatible with current VVA consign. We
consider this is true even if PA remains completely OFF during 5 minutes. Beyond 5 minutes
off, VVA consign will be “automatically” reduced.
This doesn’t apply to S8000 or S120000 BTS whose power loop behavior doesn’t need such
attenuation.
OPTIMUM TIMER VALUE
When regular smart power management is used, the smaller the switch-off timer :
• the more reactive the power management will be to the minute-by-minute changes to
the call profile as the day progresses towards quieter moments
• the more power is likely to be saved as a result.
• but the more frequently the PA is likely to go through off/on cycles, especially at the
transition from busy hour to quieter hours, thus possibly impacting its life expectancy.
Furthermore, the more TRX per cell, the more TRX are eligible for switch-off, and therefore the
more the feature is expected to make a difference to the power consumption.
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4.29. EVEA: ENHANCED VERY EARLY ASSIGNMENT
4.29.1 PRINCIPLE
When a mobile initiates an access to the network, the BSC allocates a SDCCH channel. Then,
according to the MSC request, the call stays on the signaling channel, or changes on a traffic
channel.
The BSC is able to allocate for signalling purpose a TCH channel instead of a SDCCH
channel, with the introduction of the feature “SDCCH overflow”. This feature is activated as
soon as there is no more SDCCH
Note: PDTCH can't be preempted to perform signaling, because of the timer in the mobile
which expire too quickly and requests a new channel.
The BSC is also able to allocate directly a TCH with a fall back with SDCCH, with the
introduction of “call reestablishment” feature. It is triggered when the establishment cause,
included in channel request message on Air interface, is set to specific cause. The NECI bit is
not used in current version limiting the possibility of using such a mechanism.
Indeed prior to V18, the following 2 processes were available:
EA: Early Assignment; GSM feature consisting to allocate a SDCCH during signaling phase
and then a TCH during speech/data phase.
VEA: Very Early Assignment; GSM feature consisting to allocate a TCH during signaling
phase.
In V18, EVEA: Enhanced Very Early Assignment feature consists mainly in broadcasting NECI
bit in system information so the BSC is able to analyze more accurately the mobile request.
Therefore, when there is no traffic load in cell : according to the type of communication
requested by the mobile in the channel request, the BSC shall allocate a TCH for a speech
call or a CS data call, and to keep SDCCH channels for procedures in signaling mode, like
location update, attach, detach, SMS in idle mode...
4.29.2 ACTIVATION
New parameters which manage the feature activation are:• EATrafficLoadStart
• EATrafficLoadEnd
• VEASDCCHOverflowAllowed
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The EVEA feature is activated as soon as the two new parameters EATrafficLoadStart and
EATrafficLoadEnd are both different from 100.
Note that if EATrafficLoadStart is equal to 100 and EATrafficLoadEnd is different to 100,
EVEA feature is activated.
The VEA allocation is activated until the traffic load in cell is high, and deactivated if the load
increases. To avoid ping pong effects, a hysteresis is managed:
Here below is the synthetic view
No traffic load Traffic load
EVEA deactivated
(v17 behavior) (*)
No SDCCH blocking VEA EA EA
SDCCH blockingVEA, SDCCH overflow if
allowedVEA, no SDCCH overflow EA, SDCCH overflow
(*) Whatever the traffic load
-
Max HR capacity
Max FR capacity
Traffic
24 hours
Time
Number of
allocated TCH
Full rate area-
Max HR capacity
Traffic
24 hours
Number of
allocated TCH
Full rate area
Max HR capacity
Max FR capacity
Traffic
Number of
allocated TCH
Full rate area
AMR HR based on traffic area
EATrafficLoadStart
EATrafficLoadEnd
VEA
VEA
EAEA
EA
VEA
HRCellLoadStart
HRCellLoadEnd
EA
EA EA
EA
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SDCCH BLOCKING
The SDCCH blocking cases are temporary and transitional.
To manage the SDCCH blocking, SDCCH overflow (i.e. allocating a TCH for signaling
call) is allowed:
• if there is no traffic load and,
• if the parameter VEASDCCHOverflowAllowed allows it.
The VEASDCCHOverflowAllowed allows or not to perform SDCCH overflow when
there is no traffic load but there is no more available SDCCH in cell. This parameter is
used only when EVEA is activated and doesn’t impact the actual behavior.
TRAFFIC LOAD
The Filtered TCH ratio used for AboT explained in is reused to evaluate traffic load
and compared to two thresholds:
IF EATrafficLoadStart and EATrafficLoadEnd are both different from 100
THEN
IF Filtered TCH ratio < EATrafficLoadEnd then the traffic is not loaded
ELSE IF Filtered TCH ratio ≥ EATrafficLoadStart THEN the traffic is loaded
ELSE no change
IF EATrafficLoadStart and EATrafficLoadEnd are both equal to 100
THEN
The EVEA feature is deactivated and so the V17 behaviour is kept
At the beginning, the traffic is considered as not loaded
Note : the case traffic load and SDCCH blocking may seem inconsistent but is in fact
is logical : if there is no more SDCCH available, no more signaling communication can
be established and a TCH signaling is used for speech communication (this is VEA
behavior).
CAUTION!
The explanation of the activation/deactivation VEA allocation, is that VEA allocation
may disturbs many features useful when the network is loaded (AMR Based on Traffic
or AMR Maximization features for instance).
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4.29.3 FEATURE INTERWORKING
EVEA feature disturbs the AMR feature because the AMR TDMA priority can't be
checked before allocating a TCH.
No specific allocation is performed during signaling phase; so, the classical allocation
algorithm is run (TS number, TDMA number, and level of interference).
If parameters are consistent, the EVEA feature is complementary with AMR
maximization, because the first one is used only when there is no load, while the
second is used when there is load.
• AMR BOT evolution: no impact.
• Direct HR allocation: no impact; the case TCH FR signaling to TCH HR
speech is already taken into account in EVEA feature.
• HR to FR handover deactivation: no impact; the BSC can’t allocate HR
signaling channel.
• All incoming handover forced to HR: no impact.
• Queueing HR: no impact.
If parameters are inconsistent, then EVEA disturbs ABoT & AMR maximization
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5. ALGORITHM PARAMETERS
5.1. INTRODUCTION
This chapter lists parameters, sorted according to their group, as they were defined in the
previous Chapter.
The following information is provided for each parameter:
• a brief description
• value range and unit
• the recommended value: takes the best benefit of the feature in a standard
network configuration and environment.
• process in which it is used (see Chapter 2)• some engineering rules that must be considered for the parameter setting
• the object that contains this parameter
• the default value. Most of the time, the default value inhibits the feature
characterized by this parameter
• corresponding GSM name
• GSM Recommendation
• parameter type and OMC-R class (see note below)
Note: The recommended value is established from Nortel experience and studies. This value
has to be adapted according to the network specificities. For the recommended value in GSM
900, it is the same value for eGSM and GSM-R when nothing else is recommended for these
two networks. This value is not contractual, and it could change with Nortel new studies results
and experience growth.
The following types of parameters can be distinguished:
• Customer engineering parameters:
Addressing: relative to an object
Design: contract characteristic
Optimization:network tuning
Operation: network operation
• Manufacturer parameters:
System: modifying such a parameter seriously impacts system
behaviour
Product: parameters related to the current system release
DP: stands for permanent data
OMC-R class gives rules to be followed when modifying a parameter:
CLASS Rules
Class 0 Implies reconstruction of the BDA
Class 1Put BSC out of service (i.e. BSC state set to “locked”), takes new parameters into account byresetting active chain and passive chains
Class 2 Declares the object (or its parent) temporarily out-of-service before modification
Class 3 Modification is dynamically taken into account
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5.2. 2G CELL SELECTION AND RESELECTION PARAMETERS
cellReselectHysteresis Class3 V7
Description: Hysteresis to reselect towards a cell:
when the MS is in IDLE mode and reselects a cell with a different
LA (Location Area)
when the MS is in GPRS STANDBY mode and reselects a cell with
a different LA (Location Area) or a different RA (Routing Area)
when the MS is in GPRS ready state and reselects a different cell
Value range: [0 to 14, by steps of 2] dB
Object: bts
Default value: 6 dB
Type: DP, Optimization
Rec. value: 6 dB (rural / low cell overlap), 10 dB (urban / high cell overlap)
Used in: Criteria for reselection towards a cell of a different Location Area(Sel_2)
Eng. Rules: GSM case:
A high value prevents the MS from making frequent location updatesand may also prevent an MS from performing adequate locationupdates, thus risking not receiving calls. The level variation of thesignal is more important in an urban context, so a higher value ofhysteresis should be set. To avoid frequent location updates, there isalso a timer forbidding the reselection of the previous server cell. Fora reselection with change of location area, the value is 15 seconds.
GPRS case:In order to minimize the impact of the introduction of the GPRS in anexisting GSM network, it is recommended not to modify the currentvalue of CellReselectHysteresis used for voice. A high value wouldkeep the link for a long time hence some communications would havea high BLER due to an important load of the cell. The throughputwould then decrease because of the retransmission at RLC/MAClayer.On the other hand a low value would ease the cell reselection ping-pong in data mode which could severely decrease the overall userthroughput due to the gap of transmission during the reselection.
In case of cell overlap (i.e. urban environment, site covered in severalfrequency bands), 10dB should be considered in order to minimizeping-pong reselections.
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Eng. Rules: In GSM 900 & 850MHz, msTxPwrMax = msTxPwrMaxCCH. In GSM1800 or 1900, msTxPwrMaxCCH ≤ msTxPwrMax. Both are verified atOMC-R level. This value is related to typical mobile (handheld orvehicle-mounted) and assumed an environment (urban, rural). If thecell is rural, it is possible to put a higher value because lot of mobiles
have car kits (can transmit at a higher power). In urban environment,the density of mobile increases and care should be taken to reduceinterferences. Furthermore, the major part of the mobile market arehandsets.
Remark: If the cell is used as a neighbor cell of another serving cell in thenetwork, msTxPwrMaxCCH must be identical to the msTxPwrMaxCellpower defined for the corresponding adjacentCellHandOver object(the values must be checked by users).
penaltyTime Class 3 V8
Description: Timer used by an idle mobile before reselecting a cell (C2 criterion)
When a mobile places the cell on the list of strongest carriers, it startsa timer that stops after penaltyTime seconds. This timer is reset whenthe mobile removes the cell from the list.For the entire timer duration, the reselection criterion (C2) is assigneda negative temporaryOffset value.Refer to the cellReselectOffset parameter in the Dictionary.
Value range: [20 to 640, by steps of 20] seconds.
The value “640” is reserved and indicates that the temporary offset isignored in the reselection criterion (C2) calculation. It also changesthe sign in the C2 formula.
Object: bts
Default value: 20Type: DP, Optimization
Rec. value: 20
Used in: Additional reselection criterion (for phase 2) (Sel_3)
Eng. Rules: The longer this timer is, the longer a penalty is applied for reselectingthat cell. The value should be correlated with the expected mobilesspeeds, which are to be managed by that cell.
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rxLevAccessMin Class 3 V7
Description: Minimum signal strength level received by the mobiles for being
granted access to a cell. The information is sent to MS prior toregistering.
As an example, a threshold level of -104 dBm corresponds to anacceptable BER of approximately 10-2 (minimum recommendedvalue).
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: bts
Default value: less than -110 dBm
Type: DP, Optimization
Rec. value: GSM 900/GSM 850: -101 to -100 dBm,
GSM 1800/1900: -99 to -98 dBm
Used in: Selection or reselection between cells of current Location Area(Sel_1), Criteria for reselection towards a cell of a different Location Area (Sel_2), Additional reselection criterion (for phase 2) (Sel_3)
Eng. Rules: Main parameter for selection or reselection.
Notice that the tuning of this parameter strongly depends on theoperator strategy. Decreasing the value eases the access to thenetwork by reducing the quality. This parameter defines the cellaccess size.
Remark: The difference between GSM 900/GSM 850 and GSM 1800/1900 isdue to MS sensitivity (-104 dBm (GSM 900/GSM 850), -102 dBm(GSM 1800/1900)).
Example:
RxLevAccessMin 1 = -100 dBm
RxLevAccessMin 2 = -99 dBm A rough calculation gives the following impact on the cell accesssurface: Access Zone 1 = Access Zone 2 x 1.2
CAUTION! A very low value of RxlevAccessMin allows mobiles to camp andattempt calls. Most of calls attempts at very low field levels fail, or leadto a call drop a few seconds after the call has been established. Thisassessment is also true for GPRS/EDGE procedure, a verypermissive value of RxlevAccessMin leads to data establishmentfailure and TBF drop.
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temporaryOffset Class 3 V8
Description: Negative offset applied during Penalty Time for reselecting a cell (C2criterion)
This negative offset is applied during the entire penaltyTime durationand allows to prevent speeding mobiles from selecting the cell. Referto the cellReselectOffset entry in the Dictionary.
Value range: [0 to 70, by steps of 10] dB
Object: bts
Default value: 70
Type: DP, Optimization
Rec. value: 0 (microcell & macrocell in mono-layer),
70 (macrocell in multi-layers)
Used in: Additional reselection criterion (for phase 2) (Sel_3)
Eng. Rules: The value prevents a mobile from reselecting a cell duringPenaltyTime. By giving the highest possible value, which is higherthan the field strength range (0 to 63), we ensure that the mobile willnot reselect the cell before the timer expires. Then, the value 70means the applied offset is infinite.
It could be dangerous on a microcell or macrocell in a mono-layerenvironment to have a high value, because it slows down thereselection process. However, on a macrocell in a multi-layersenvironment, it is recommended to prevent from reselecting a cell(value 70), in keeping a low value for “penaltyTime” (20 seconds).
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5.3. 2G-3G CELL RESELECTION PARAMETERS
3GTechnology Class 3 V17
Description: FDD or TDD 3G technology selection
Value range: FDD (0) /TDD (1)
Object: bts
Default value: FDD
Type: DP
Rec. value: Accordingly to the technology used for 3G
Used in: 2G - 3G Cell Reselection
Eng. Rules:
gsmToUmtsReselection Class 3 V14
Description: gsmToUmtsReselection is composed of 4 parameters:
3GsearchMinLevel
3GreselectionOffset
3GAccessMinLevel
3GReselectionARFCN
Object: bts
Type: DP
3GAccessMinLevel Class 3 V14
Description: A minimum threshold for Ec/No for UTRAN FDD cell re-selection(GSM spec 45.008 name for this parameter is FDD_Qmin)
Value range: [0: - 20 dB, 1: - 6 dB, 2: - 18 dB, 3: - 8 dB, 4: - 16 dB, 5: - 10 dB, 6: -14 dB, 7: - 12 dB]
Object: bts
Default value: - 12 dB
Type: DP
Rec. value: - 12 dB
Used in: 2G - 3G Cell Reselection Eng. Rules: below the recommended value UE may not be able to reach the 3G
network in good conditions.
Note: The SI2Quater message broadcasted by the BSS is an index [0 to 7]that is interpreted by the mobile depending on the release date of thatmobile:
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Index Mobiles’ interpretationbefore October 2003
Mobiles’ interpretationafter October 2003
0 - 20 dB - 20 dB
1 - 19 dB - 6 dB2 - 18 dB - 18 dB
3 - 17 dB - 8 dB
4 - 16 dB - 16 dB
5 - 15 dB - 10 dB
6 - 14 dB - 14 dB
7 - 13 dB - 12 dB
One should be advised that OMC-R may eventualy display “old”values while the offset is broadcasted.
3GReselectionARFCN Class 3 V14
Description: Neighbouring UMTS cell ARFCN. The BSS does not perform anycheck on UARFCN value so new UMTS frequency band introductionapplies to any BSC architecture.
(GSM spec 45.008 name for this parameter is FDD_ARFCN)
Value range: 0 to 16383
Object: bts
Default value: 0
Type: DP
Rec. value: a non-null value to broadcast the SI2Quater on the BCCH
Used in: 2G - 3G Cell Reselection
Eng. Rules:
3GReselectionOffset Class 3 V14
Description: Applies an offset to RLA_C for cell reselection to access technology /mode FDD (GSM spec 45.008 name for this parameter isFDD_Qoffset)
Value range: [-∞dB, -28 dB, -24 dB, -20 dB, -16 dB, -12 dB, -8 dB, -4 dB, 0 dB, 4dB, 8 dB, 12 dB, 16 dB, 20 dB, 24 dB,28 dB]
Object: bts
Default value: -∞dB
Type: DP
Checks:
Rec. value: see Engineering Rules
Used in: 2G - 3G Cell Reselection
Eng. Rules: that parameter allows a fine tuning in UMTS re-selection byintroducing a favorable/defavorable offset toward a UMTS cell.
The recommanded value by default is “0 dB”.
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3GSearchLevel Class 3 V14
Description: Search for 3G cell if signal level is below or above the threshold
(GSM spec 45.008 name for this parameter is Qsearch_I)
Value range: [0: “< -98 dBm”, 1: “< -94 dBm”, 2: “< -90 dBm”, 3: “< -86 dBm”, 4: “< -82 dBm”, 5: “< -78 dBm”, 6: “< -74 dBm”, 7: “Always”, 8: “> -78 dBm”,9: “> -74 dBm”, 10: “> -70 dBm”,11: “> -66 dBm”, 12: “> -62 dBm”, 13:“> -58 dBm”, 14: “> -54 dBm”, 15: “Never”]
Object: bts
Default value: -98 dBm
Type: DP
Rec. value: see Engineering Rules
Used in: 2G - 3G Cell Reselection
Eng. Rules: this parameter set whether UE should search for UMTS cells or not. It
can allow UE to search above a certain level, below a certain level, oralways. Note that in this last case the UE battery autonomy can beimpacted.
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5.4. LEGACY MEASUREMENT REPORTING PARAMETERS
powerControlIndicator Class 3 V7
Description: Whether MS signal strength measurements on the TCH or SDCCHshould include measurements on BCCH frequency or not.
Value range: [include BCCH measurements / do not include BCCH measurements]
Object: bts
Default value: include BCCH measurements
Type: DP, Optimization
Rec. value: See Eng. Rules
Used in: Power Control Algorithms
Eng. Rules: Downlink measurements performed by the mobile on TCH or SDCCHshould not include measurements done when the channel frequencyis the BCCH frequency if the following two conditions are met:
The radio channel hops at least on two different frequencies, on of
which is the BCCH frequency.
Power control on the downlink is used.
CAUTION! This parameter is only relevant with BTS using cavity couplingbecause only cavity coupling allows to use BCCH frequency as part ofthe hopping frequency list. For BTS using hybrid coupling, the BCCHfrequency is never part of the hopping list, so this parameter isirrelevant in that case. See §4.5.9 for details.
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5.5. ENHANCED MEASUREMENT REPORTING PARAMETERS
fDDMultiratReporting Class 3 V17
Description: (applicable both to normal measurement reporting and EMR) Numberof UTRAN FDD cells to be reported by the mobile in the list ofstrongest cells inside the normal or Enhanced Measurement Reportmessage.
Value range: 0: “no UTRAN cell is favoured”
1: “1 UTRAN strongest cell is favoured”
2: “2 strongest UTRAN cells are favoured”
3: “3 strongest UTRAN cells are favoured”
Object: bts
Default value: 0
Type: DP, Optimization
Rec. value: see Eng. Rules
Used in: Enhanced Measurement Reporting (EMR)
UTRAN cell reporting using legacy measurement reports (V17)
Eng. Rules: The value depends on the network operator strategy.
However, in case of HO2G-3G enabled with normal measurementreporting (EMR disabled), it is necessary to exercise caution whensetting the parameters fDDMultiRatReporting andmultiBandReporting. These parameters define the number of UTRANcells and non-serving band GSM cells, respectively, that must be
included by the mobile in the list of strongest cells in the measurementreport. Therefore it leaves (6 - fDDMultiRatReporting -multiBandReporting) spaces for the serving band GSM cells.Therefore, if EMR is disabled, it is recommended not to exceedfDDMultiRatReporting = 2 and multiBandReporting = 2.
fDDreportingThreshold Class 3 V17
Description: CPICH RSCP level measured on UTRAN cells, above which themobile shall apply a higher priority to UTRAN cells in the enhancedmeasurement report message
Value range: -115 dBm, -109 dBm, -103 dBm, -97 dBm, -91 dBm, -85 dBm, -79dBm, never
Object: handoverControl
Default value: never
Type: DP, Optimization
Rec. value: -97 dBm
Used in: Enhanced Measurement Reporting (EMR)
Eng. Rules: An operator willing to unload GSM network to UMTS network butkeeping calls in good conditions should set this parameter to at least -97dBm, ensuring a high probability of good Ec/No value after the HOand limiting the high increase of UTRAN incoming HO due to ping
pong handover.
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This parameter must be in accordance with 3G to 2G HOparameters.
In order to limit ping pong effect, a hysteresis of 5 dB is
recommended between fDDreportingThreshold and UTRAN hardHO 3G to 2G CPICH RSCP threshold.
fDDreportingThreshold2 Class 3 V17
Description: (applicable both to normal measurement reporting and EMR,applicable from MS release 5) CPICH Ec/N0 level measured onUTRAN cells, above which the mobile shall report UTRAN cells in theenhanced measurement report message
Value range: 0 to 63 (0 means “always reported”)
Object: handoverControl
Default value: 0 (“always reported”)
Type: DP, Optimization
Rec. value: 28
Used in: Enhanced Measurement Reporting (EMR)
UTRAN cell reporting using legacy measurement reports (V17)
Eng. Rules: To ensure a good quality after the handover, a simultaneously not toorestrictive and good C/I value must be required.
Setting this parameter at 28 which corresponds to Ec/No = -10 dBseems to be a good compromise.
This parameter must be in accordance with 3G to 2G HOparameters.
In order to limit ping pong effect, a hysteresis of 2 dB isrecommended between fDDreportingThreshold2 and UTRANhard HO 3G to 2G Ec/No threshold.
Note: The Ec/No step is in half dB:
- “0” means always reported
- In range 1 to 49, “1” means “CPICH Ec/No ≥ -24 dB” and “49” means“CPICH Ec/No ≥ 0 dB”.
CPICH Ec/N0 level measured = - 24 + fDDreportingThreshold2 /2
- Values from 50 to 63 should not be used for Ec/No.
qsearchC Class 3 V17
Description: (applicable both to normal measurement reporting and EMR). Thisparameter is called Qsearch_C in the GSM specification. It gives theserving cell’s BCCH level below which the MS must listen toneighbours. If the serving BCCH frequency is not part of theBA(SACCH) list, the dedicated channel is not on the BCCH carrier,and qsearchC is not equal to 15, the MS shall ignore the qsearchCparameter value and always search for UTRAN cells. If qsearchC isequal to 15, the MS shall never search for UTRAN cells.
Value range: 0: “< -98 dBm”
1: “< -94 dBm”
2: “< -90 dBm”3: “< -86 dBm”
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4: “< -82 dBm”
5: “< -78 dBm”
6: “< -74 dBm”
7: “always”
8: “> -78 dBm”
9: “> -74 dBm”
10: “> -70 dBm”
11: “> -66 dBm”
12: “> -62 dBm”
13: “> -58 dBm”
14: “> -54 dBm”
15: “never”
QsearchC < -XX dBm: the HO towards the UMTS can be done only ifthe RxLev from the serving cell is below -XX dBm.
QsearchC > -XX dBm: the HO towards the UMTS can be done only ifthe RxLev from the serving cell is above -XX dBm.
Object: handoverControl
Default value: 15 (“never”)
Type: DP, Optimization
Rec. value: 7 (“always”)
Used in: Enhanced Measurement Reporting (EMR)
UTRAN cell reporting using legacy measurement reports (V17)
Eng. Rules: Cases where a different value from “always” could be useful have notbeen identified. Therefore value “always” is recommended.
reportTypeMeasurement Class 3 V17
Description: type of measurement report to be reported on this cell : enhancedmeasurement report or legacy measurement report
Value range: 0 : Measurement report
1 : Enhanced Measurement Report
Object: bts
Default value: 0Type: DP, Optimization
Rec. value: 1
Used in: Enhanced Measurement Reporting (EMR)
UTRAN cell reporting using legacy measurement reports (V17)
Eng. Rules: To take advantage of EMR benefits it is recommended to activateEMR.
In case of HO 2G -3G activation either EMR or legacy measurementdoes not have any impact on the Handover 2G to 3G efficiency.
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servingBandReporting Class 3 V17
Description: (applicable to EMR only) This parameter sets the value of theSERVING_BAND_REPORTING field in Measurement Informationmessages.
It defines the number of cells from the GSM serving frequency bandthat shall be included in the list of strongest cells in the enhancedmeasurement report.
Value range: 0 : “no inband cell is favoured”
1: “1 strongest inband cell is favoured”
2: “2 strongest inband cells are favoured”
3: “3 strongest inband cells are favoured”
Object: bts
Default value: 3
Type: DP, Optimization
Rec. value: 3Used in: Enhanced Measurement Reporting (EMR)
Eng. Rules: Depends on the network operator strategy.
servingBandReportingOffset Class 3 V17
Description: (applicable to EMR only) This parameter sets the value of theXXX_REPORTING_OFFSET field in Measurement Informationmessages, for the GSM band (XXX =900 or 1800 or 400 or 850 or1900).
If there is not enough space in the report for all valid cells, the cells
shall be reported that have the highest sum of the reported value(RXLEV) and the parameter servingBandReportingOffset(XXX_REPORTING_OFFSET) for the serving GSM band. Note thatthis parameter shall not affect the value itself of the reportedmeasurement.
Value range: 0, 1, ... 7, 0xFF : 0 dB, 6 dB, …, 42 dB, “not significant”
Object: handoverControl
Default value: empty
Type: DP, Optimization
Rec. value: See Eng. Rules
Used in: Enhanced Measurement Reporting (EMR)
Eng. Rules: This parameter should be tuned if EMR is used during an IMcampaign. If, during the Interference Matrix campaign in a dual bandnetwork, the reporting of serving band neighbours is deliberatelyfavoured by using the servingBandReportingOffset , then, as a side-effect, the traffic distribution may be modified. This undesirable side-effect may in turn modify the results of the IM measurements, whichtherefore may no longer reflect the real situation in the field once theIM has ceased. Therefore it is recommended to ensure that thechosen value of servingBandReportingOffset does not causeunacceptable changes in the traffic distribution.
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5.6. RADIO LINK FAILURE PARAMETERS
callReestablishment Class 3 V7
Description: Whether call re-establishment in a cell is allowed when the radio linkis broken off for propagation reasons
The information is broadcast to the mobiles at regular intervals on thecell BCCH.On receipt of a CHANNEL REQUIRED message with cause “call re-establishment”, the BSC attempts to allocate a TCH in one of the cellswhere call re-establishment is allowed. Then, if no TCH is availablethe BSC attempts to allocate a SDCCH.
Value range: [allowed / not allowed]
Object: bts
Default value: not allowed
Type: DP, Optimization
Rec. value: allowed
Used in: Radio link failure process (run by the MS),
Call reestablishment procedure
Eng. Rules: Enabling or not this feature is a MSC capability issue
radioLinkTimeout Class 2 V7
Description: Maximum value of the counter (S) associated with the downlinkSACCH messages, beyond which the radio link is cut off. It is lower
than or equal to t3109.Mobiles comply with system operating conditions when the counter(S) is assigned a value lower than or equal to t3109.If the receiver is unable to decode a downlink SACCH message(BTS–to–MS direction), the counter is decreased by 1. If the messageis received, the counter is increased by 2. When the counter goesdown to zero, the radio link is declared “faulty”.
Value range: [4 to 64, by steps of 4] SACCH frames (1 unit = 480 ms on TCHs, 470ms on SDCCHs)
Object: bts
Default value: 20 SACCH
Type: DP, Optimization
Rec. value: 2032 when AMR is activated
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Used in: Radio link failure process (run by the MS),
AMR - Adaptative Multi Rate FR/HR
Eng. Rules: radioLinkTimeOut < t3109.
If surrounding cells accept re-establishment (from GSM08 for DMS
MSC), overall process should not be too long. Small value: call might be dropped before a move to a more
favorable environment could occur.
High value: in case of permanent bad conditions, user’s anger and
taxation increase before actual call’s end or reestablishment.
Remark: The rlf1 attribute serves the same goal on the uplink, but the systemdoes not check that the values of the two attributes are consistent.
rlf1 Class 2 V8
Description: Value to compute the initial and maximum value of the (CT) counter
used in the BTS radio link control algorithmThe FP runs the following algorithm to monitor the uplink SACCHs(MS–to–BTS direction):The CT counter is reset to zero when the FP receives a CHANNEL ACTIVATION message.On each occurence of an uplink SACCH, the following occurs:
if the channel is decoded and CT = 0, then CT = 4 * rlf1 + 4
if the channel is decoded and CT ≠ 0, then CT = min (4 * rlf1 + 4,
CT+rlf2)
if the channel is not decoded, then CT = max (0, CT - rlf3)
When the CT counter goes down to zero, the radio link is broken and
the BTS sends a CONNECTION FAILURE INDICATION message tothe BSC.
Value range: [0 to 15]
Object: bts
Default value: 4
Type: DP, Optimization
Rec. value: 4
7 when AMR is activated
Used in: Radio link failure process (run by the BTS),
AMR - Adaptative Multi Rate FR/HR
Eng. Rules: The resulting CT value is the same as “radioLinkTimeOut” value.There is no reason to recommend to cut a communication morerapidly in the uplink or downlink direction. In a network with a lot oftraffic or with many zones of interference, a lower value (between 2and 4) of this parameter is recommended. Typically the value, in sucha case should be 2.
Notes: The radioLinkTimeOut attribute serves the same goal on the downlink,but the system does not check that the values of the two attributes areconsistent.
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rlf2 Class 2 V8
Description: Step value by which the (CT) counter is increased by the radio link
control algorithm when an uplink SACCH is decoded.Refer to the rlf1 entry.
Value range: [1 to 4] SACCH frames
Object: bts
Default value: 2
Type: DP, Optimization
Rec. value: 2
Used in: Radio link failure process (run by the BTS)
Eng. Rules: The value should be higher than rlf3 value, in order to encourage thecontinuity of service. The higher the value, the longer an MS will keep
a bad quality communication in a disturbed zone. The choice of thisvalue must be made by the operator, in keeping with its service qualitylevel.
rlf3 Class 2 V8
Description: Step value by which the (CT) counter is decreased by the radio linkcontrol algorithm when an uplink SACCH is not decoded
Refer to the rlf1 entry.
Value range: [1 to 4] SACCH frames
Object: bts
Default value: 1Type: DP, Optimization
Rec. value: 1
Used in: Radio link failure process (run by the BTS)
Eng. Rules: It is recommended to fix this value to 1. This allows the use of the rlf1value to set the maximal duration of consecutive non-reception ofSACCH frame.
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5.7. SIGNAL QUALITY AVERAGING PARAMETERS
missRxQualWt Class 3 V7
Description: Weight applied to missing Quality measurement
The missing measurement is replaced by the latest computedarithmetic average, or by the latest received raw measurement if noaverage value is available, weighed by this corrective factor whencalculating the average bit error rate in the radio link. The range ofpermitted values makes missing quality measurements not favored.
Value range: [100 to 200] %
Object: handOverControl
Default value: 110
Type: DP, Optimization
Rec. value: 110Used in: Missing Downlink Measurements
Eng. Rules: The higher the value is, the higher the missing measurement will beweighted.
rxQualHreqave Class 3 V7
Description: Number of bit error rate measurements performed on a serving cell,used to compute arithmetic BER averages in handover and powercontrol algorithms
Value range: [1 to 10] number of measurement results
Object: handOverControlDefault value: 8
Type: DP, Optimization
Rec. value: 4 in urban environment,
> 8 in rural environment
Used in: Measurement Processing
Eng. Rules: In order to minimize calculation of temporary averages it is better ifrunHandOver and runPwrControl are multiples or sub multiples ofrxQualHreqAve. Length of weighed average window should bereduced when the cell is small or environment requires quickreactivity. Studies have shown that a reduction of the window size
value (from 8 to 4 for instance) does not increase the number ofhandovers on a network and does not change handover causes.
However, it has a positive impact, because it leads to a greaterreactivity.Then, the weighted average window size (rxQualHreqAve *rxQualHreqt) has to be correlated to the hoMargin value to keep a lowping-pong probability.The larger the window size, the lower the hoMargin should be.
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rxQualHreqt Class 3 V7
Description: Number of arithmetic averages taken into account to compute the
weighted average bit error rate in handover and power controlalgorithms. Each is calculated from rxQualHreqave bit error rate(BER) measurements on a radio link.
Value range: [1 to 16]
Object: handOverControl
Default value: 1
Type: DP, Optimization
Rec. value: 1
Used in: Measurement Processing
Eng. Rules: The quality and signal strength weighted average window shouldencompass the same period. For the sake of simplicity, the default
value disables weighting. The weighed average window size(rxQualHeqAve * rxQualHreqt) must be correlated to the hoMarginvalue to keep a low ping-pong probability.
The larger the window size, the lower the hoMargin should be.
rxQualWtsList Class 3 V7
Description: List of up to sixteen weights used to compute the average bit errorrate on a radio link
The L1M function calculates rxQualHreqave arithmetic averages fromraw measurements, and balances rxQualHreqt averages among those
with the weights defined in rxQualWtsList.Each arithmetic average is partnered with one weight in the list.Weight/average associations are set in the order in which the weightsare recorded. The latest computed arithmetic average is alwayspartnered with the first weight in the list.Super–average = [∑ (averagei x weighti)] / 100, i = 1 to rxQualHreqt
Value range: [0 to 100] %
Object: handOverControl
Default value: 100
Type: DP, Optimization
Rec. value: 100
Used in: Measurement Processing Eng. Rules: Values add up to 100.
If there are several values, the biggest weights must be used for morerecent reports.In rural environment, rxLev and rxQual weighed average window willnot refer to the same time window.
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5.8. SIGNAL STRENGTH AVERAGING PARAMETERS
missRxLevWt Class 3 V7
Description: Weight applied in case of missing signal strength measurementreport
The missing measurement is replaced by the latest computedarithmetic average, or by the latest received raw measurement if noaverage value is available, weighed by this corrective factor whencalculating the average signal strength in the cell.Selecting the greatest value makes missing strength measurementsnot favored.
Value range: [0 to 100] %
Object: handOverControl
Default value: 90
Type: DP, Optimization
Rec. value: 90
Used in: Measurement Processing
Eng. Rules:
rxLevHreqave Class 3 V7
Description: Number of signal strength measurements performed on a serving cell,used to compute arithmetic strength averages in handover and powercontrol algorithms
Value range: [1 to 10] number of measurement resultsObject: handOverControl
Default value: 8
Type: DP, Optimization
Rec. value: 6 for small cells (Dintersite < 800m)
between 8 and 10 for large cells (Dintersite > 1600m)
Used in: Measurement Processing
Eng. Rules: In order to minimize calculation of temporary averages it is better ifrunHandOver and runPwrControl are multiples or sub multiples ofrxLevHreqAve. In an urban environment, the window size should beminimized and the hoMargin value should be high. However, choosing
too small a value leads to averaging meaningless measures in case ofDTX activation uplink or downlink. Then, in an urban environment,according to building density, antenna height and global environment,the window size can fluctuate between 6 and 8. The minimum value,6, may be preferred, because it ensures a good reactivity without badinfluence if the parameter hoMargin is well chosen.
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rxLevHreqaveBeg Class3 V11
Description: Number of measurement reports used in short averaging algorithm on
current cell for signal strength arithmetic averageRefer to the rxLevHreqave entry in the Dictionary.
Value range: [1 to 10]
Object: handOverControl
Default value: 2
Type: DP, Optimization
Rec. value: 2
Used in: Early HandOver Decision
Automatic handover adaptation Fast power control at TCH assignment
Eng. Rules: rxLevHreqaveBeg < rxLevHreqaveThis parameter has to be coupled with hoMarginBeg andrxLevNCellHreqaveBeg.
Remark: This parameter is only available for DCU4 or DRX transceiverarchitecture.
rxLevHreqt Class 3 V7
Description: Number of arithmetic averages taken into account to compute theweighted average signal strength in handover and power controlalgorithms. Each is calculated from rxLevHreqave signal strengthmeasurements on a serving cell.
Value range: [1 to 16]
Object: handOverControl
Default value: 1
Type: DP, Optimization
Rec. value: 1
Used in: Measurement Processing
Eng. Rules: In a urban environment, the window size should be minimized and thehoMargin value should be high.
For the sake of simplicity, weighted averaging is disabled by defaultvalue.
CAUTION! The weighted average is not used for the PBGT. The weighedaverage window size (rxLevHreqAve * rxLevHreqt) has to becorrelated to the hoMargin value to keep a low ping-pong probability.The larger the window size, the lower the hoMargin should be.
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rxLevWtsList Class 3 V7
Description: Values of weights to be used for signal strength weighed average
The L1M function first calculates rxLevHreqave arithmetic averagesfrom raw measurements, and balances rxLevHreqt averages amongthose with the weights defined in rxLevWtsList.Each arithmetic average is partnered with one weight in the list.Weight/average associations are set in the order which the weightsare recorded. The latest computed arithmetic average is alwayspartnered with the first weight in the list.Super–average = [ ∑ (averagei x weighti)] / 100, i = 1 to rxLevHreqt
Value range: [0 to 100] %
Object: handOverControl
Default value: 100
Type: DP, OptimizationRec. value: 100
Used in: Measurement Processing
Eng. Rules: Arithmetic law to be preferred, biggest weight for most recent reports
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5.9. NEIGHBOR CELL AVERAGING PARAMETERS
cellDeletionCount Class 3 V7
Description: The cellDeletionCount is to be compared to the number ofconsecutive Measurement Results messages not containinginformation on one of the neighbour cells that would result in the cellbeing no longer eligible.
(TF 1089-2), from a number ≥ cellDeletionCount the cell will be noneligible, but the information of that neighbour cell will only bediscarded when the number of consecutive Measurement Results withno information on the cell will reach 10 (i.e. 5 sec).
Value range: [0 to 31]
Object: bts
Default value: 5 in rural environment, 2 in microcell environment
Type: DP, Design
Rec. value: 5 in rural,
2 in urban environment
Used in: Measurement Processing
Handovers screening
Eng. Rules: As there is no weighting factors on neighboring cells, low values ofcellDeletionCount are advised and so the rule cellDelectionCount <rxNcellHrequave. A mobile is required to keep synchronizationinformation at least 10 seconds after a cell was removed from the bestcells list. This synchronisation becomes quickly obsolete in the case offast moving mobiles.
CAUTION! This mechanism applies only for Power budget handover.
Remark: Further informations are provided in chapter Best Neighbor CellsStability
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rxNCellHreqave Class 3 V7
Description: Number of measurement results used in the PBGT algorithm to
compute the average neighboring signal strengthNo weighed average is computed for this category of measurement
Value range: [1 to 10] number of measurement results
Object: handOverControl
Default value: 8
Type: DP, Optimization
Rec. value: 6 for small cells (Dintersite < 800m)
between 8 and 10 for large cells (Dintersite > 1600m)
Used in: Measurement Processing
Early HandOver Decision
Automatic handover adaptation Eng. Rules: In the PBGT formula, the RXLEV_DL is the last arithmetic signal
strength on the current cell. In order to use the same time base, weshould have rxNcellHreqAve = rxLevHreqAve.
rxLevNCellHreqaveBeg Class 3 V11
Description: Number of measurement results used in short averaging algorithm tocompute the average neighboring signal strength
Value range: [1 to 10]
Object: handOverControl
Default value: 2
Type: DP, Optimization
Rec. value: 2
Used in: Early HandOver Decision
Eng. Rules: rxLevNCellHreqaveBeg < rxLevNCellHreqave
This parameter has to be coupled with hoMarginBeg andrxLevHreqaveBeg.
Remark: This parameter is only available for DCU4 or DRX transceiverarchitecture.
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5.10. DISTANCE AVERAGING PARAMETERS
distHreqt Class 3 V7
Description: Number of distance measurements, used to compute the weightedaverage MS–to–BTS distance in handover algorithms
Value range: [1 to 16]
Object: handOverControl
Default value: 4
Type: DP, Optimization
Rec. value: 4
Used in: Measurement Processing
Eng. Rules: For distance handover and Call Clearing, a weighted average of theMS-BS distance is computed from timing-advance results.
distWtsList Class 3 V7
Description: List of no more than sixteen weights, used to compute the averageMS–to–BTS distance from distHreqt measurements
The L1M function balances distHreqt raw measurements with theweights defined in the distWtsList list. Each measurement is partneredwith one weight in the list. Weight/measurement associations are setin the order which the weights are recorded. The latest receivedmeasurement is always partnered with the first weight in the list.Super–average = [∑ (measurementi x weighti)] / 100, i = 1 to distHreqt
Value range: [0 to 100] %Object: handOverControl
Default value: 40 30 20 10
Type: DP, Optimization
Rec. value: 40 30 20 10
Used in: Measurement Processing
Eng. Rules: A supply weights to distHreqt values, highest value for latestmeasurements. Choosing an arithmetic law enables to enhance latestvalues while not putting too much weight upon the period of timewhich might not be representative of the current trend.
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missDistWt Class 3 V7
Description: Weight applied to missing Distance measurement.
The missing measurement is replaced by the latest received rawmeasurement weighed by this corrective factor when calculating theaverage MS–BTS distance.The range of permitted values makes missing distance measurementsnot favored.
Value range: [100 to 200] %
Object: handOverControl
Default value: 110
Type: DP, Optimization
Rec. value: TBD
Used in: Measurement Processing
Eng. Rules: The higher the value is, the higher the missing measurement will beweighted.
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5.11. HANDOVER (GLOBAL) PARAMETERS
bts time between HO configuration Class 3 V9
Description: Whether the hoPingpongTimeRejection timer can be used at bts levelwhen processing handovers
Value range: [0 / 1]
“0”:The timer is disabled.
“1”:The timer is used.
Object: bts
Default value: 0
Type: DP, Optimization
Rec. value: 1
Used in: Minimum time between Handover
General protection against HO ping-pong
Eng. Rules: New semantic in order to restore the minimum time between HOfeature (TF218, V9):
timeBetweenHOconfiguration = used
bts time between HO configuration = 1
ho Pingpong combinaison = (all, allPBGT)
ho Pingpong Time Rejection > 0
forced handover algo Class 3 V9
Description: Minimum signal strength level received by the mobiles to be grantedaccess to a neighbor cell in case of forced handover
Value range: [less than -110, -110 to -109, ..., -49 to -48, more than -48] dBm
Object: adjacentCellHandover
Default value: less than -110
Type: DP, Optimization
Rec. value: = rxLevMinCell -1
Used in: Forced Handover
Eng. Rules: The neighbour cell eligibility criterion for forced handover comparesthe Rxlev received by the mobile from the neighbour cells with thevalue of "forced handover algo". If the Rxlev is greater than "forced
handover algo", then the forced handover is triggered. Therefore :
the higher the value of "forced handover algo" parameter, theless efficient the forced handover feature, because fewer mobileswill comply with the eligibility criterion. The mobiles who arelocated too far away from the strongest neighbour cell will bekept by the network on the current cell. So, it will take longer toempty the cell because the operator has to wait for all mobiles tomove around and get closer to a neighbour cell. Note that it doesnot make sense to set "forced handover algo" to a higher valuethan "rxLevMinCell", although nothing prevents from doing so.
the smaller the value of "forced handover algo" parameter, thefaster mobiles will be forced out of the current cell. On the
downside, if "forced handover algo" is significantly lower than"rxlevMinCell", quality of service for the mobile on the destinationcell will be poorer with a risk, ultimately, of call drop.
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Therefore a compromise should be found, and BPUG recommendsthat forced handover algo = RxlevMinCell - 1dB. This is only arecommendation. A different value may be chosen by the customer.
handOver from signalling channel Class 3 V7
Description: Authorization to perform intercell handovers on signalling channels(SDCCH or TCH in signalling mode)
Value range: [enabled / disabled]
Object: handOverControl
Default value: disabled
Type: DP, Design
Rec. value: disabled
Used in: Direct TCH Allocation and Handover Algorithms
Eng. Rules: It is recommended to enable this feature when queuing is activated.
hoMargin Class 3 V7
Description: Margin to use for PBGT handovers to avoid subsequent handover, inPBGT formula
Value range: [-63 to 63] dB
Object: adjacentCellHandOver
Default value: 4
Type: DP, Optimization
Rec. value: between 4 and 6 for small cells
(4 in an 1X1 pattern, 5 or 6 otherwise),5 for large cells.
Used in: Handovers
Power budget formula Handover for traffic reasons Define eligible neighbor cells for intercell handover (except directedretry) Automatic handover adaptation
Eng. Rules: As a general rule, this parameter enables to harden access to a newcell in order to avoid a subsequent return to the current cell (providedrxLevMinCell is set to its minimal value and does not already take intoaccount ping-pong handover protection).
The value of this hoMargin must be correlated to the window sizevalue to keep a low ping-pong probability. In case of ping-pong,handover hoMargin value must be incremented, and the window sizevalue must be decremented.For a dual Band Network where one frequency band is privileged, it isadvised to increase this value in neighbouring objects with afrequency belonging to the low priority frequency band. Thus, theseneighbours will be underprivileged.
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hoMarginBeg Class 3 V11
Description: Margin that is added to hoMargin, concentAlgoExtRxLev,
amrDirectAllocRxLevUL, amrDirectAllocRxLevDL,amrDirectAllocIntRxLevUL, amrDirectAllocRxLevDL,bizonePowerOffset, until rxLevHreqave for short averaging algorithmin order to compensate the lack of reliable measurements
This parameter is coupled with hoMargin, concentAlgoExtRxLev,amrDirectAllocRxLevUL, amrDirectAllocRxLevDL,amrDirectAllocIntRxLevUL, amrDirectAllocRxLevDL,bizonePowerOffset and rxLevHreqaveBeg.
Value range: [0 to 63] dB
Object: bts
Default value: 4 dB
Type: DP, OptimizationRec. value: 4 dB
2 dB with Automatic Handover Adaptation
Used in: Handovers
Early HandOver Decision Automatic handover adaptation Direct TCH Allocation
Eng. Rules:
Remark: This parameter is only available for DCU4 or DRX transceiverarchitecture.
hoMarginDist Class 3 V8
Description: Margin to be used for Distance Handovers
Value range: [-63 to 63] dB
Object: adjacentCellHandOver
Default value: - 24 dB
Type: DP, Optimization
Rec. value: - 2 dB
Depends on the environment and on the value of themsRangeMax Threshold.
Used in: Handover condition for leaving a cell on distance Define eligible neighbor cells for intercell handover (except directedretry)
Eng. Rules: Because the priority of the handover on Distance cause is lower thanthe Quality and Strength causes, it is performed while the quality andthe signal strength on the current cell are still acceptable. Setting anegative value decreases the interference.
CAUTION! PBGT hoMargin in the target cell should be set in order to avoid aping-pong handover. For a dual Band Network where one frequencyband is privileged, it is advised to increase this value in neighbouringobjects with a frequency belonging to the low priority frequency band.Thus, these neighbours will be underprivileged.
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CAUTION! PBGT hoMargin in target cell should be set in order to avoid a ping-pong handover. This parameter, defined per neighbor, is used toselect and sort neighbors. For a dual Band Network where onefrequency band is privileged, it is advised to increase this value inneighbouring objects with a frequency belonging to the low priority
frequency band. Thus, these neighbours will be underprivileged.
hoMarginTrafficOffset Class 3 V12
Description: Minimum signal strength margin with the serving cell that allows toselect the best neighbor cell when a handover is triggered for overloadreasons
Value range: [0 to 63] dB
Object: adjacentCellHandOver
Default value: 0 dB
Type: DP, Optimization
Rec. value: 6 dB (if overlapping exists)
Used in: Handovers
Handover for traffic reasons
Eng. Rules: Since the HO for traffic reasons uses the PBGT HO procedure, theparameter powerBudgetInterCell shall be “enabled”.
It is advised to combine the HO for traffic reason with the feature HOdecision according to priority and Load.This parameter shall be set at a value which guarantees that celloverlapping exists with (hoMargin -hoMarginTrafficOffset).See Paragraph 2.5k9 for more details.When set to “0”, handovers for traffic reasons are not allowed in the
adjacent cell (the PBGT HO is done before because it has a higherpriority than the HO for traffic).
CAUTION Only applicable to BTSs equipped with non mixed DCU4, or DRXboards
hoPingpongCombination Class3 V12
Description: List of couples of causes (HOInitialCause and HONonEssentialCause)indicating the causes of ping-pong handovers in the overlapping areas
The following causes are defined with regard to the neighboring cell:
HOInitialCause indicates the essential handover cause which leads
to enter the neighbor cell (cause of incoming handover). HONonEssentialCause indicates the non-essential handover
cause which leads to leave the cell (cause of outgoing handover).
This parameter defines the combination for which theHOPingpongTimeRejection attribute is used.
Value range: [rxQual, rxLev, distance, powerBudget, capture, directedRetry, OaM,traffic, all, allCapture, allPowerBudget, AMRquality]
Object: adjacentCellHandOver
Default value:
Type: DP, Optimization
Rec. value: (all, PBGT)Used in: General protection against HO ping-pong
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Eng. Rules: This parameter shall be known by the new BSC (whatever the type ofHO is intra or inter BSC) ; so, it must be defined at the “entering cell”(relatively to the first HO of the combination) level, for theneighbouring cell (adjacentCellHandover object) corresponding to the“left cell” (still relatively to the first HO of the combination).
Example: if you perform a handover from cell A to cell B for qualityreason and you want to protect against pingpong HO for PBGTreason (from B to A), you have to declare (rxQual, PBGT) as one ofthe forbidden handover combinations at cell B level (for theneighbouring cell A).
Note: The hoPingpongCombination list can hold up to 4 couples of causes.
CAUTION! No protection against intracell or interzone pingpongHO
No protection against pingpong HO between more than 2 cells exceptfor allcapture / all PBGT causes.Directed retry can only be an initial cause.timeBetweenHOConfiguration and bts Time Between HOconfiguration shall be set accordingly in order for the feature to be
activated.
hoPingpongTimeRejection Class 3 V12
Description: Time before a new handover attempt can be triggered
Refer to bsc object timeBetweenHOConfiguration and bts object btstime between HO configuration attributes in this Dictionary ofParameters for this timer activation.Refer to adjacentCellHandOver object HOPingpongCombination attribute in this Dictionary of Parameters for the combinations forwhich this timer applies.To avoid ping-pong handovers this new timer is started after asuccessful handover. Up to the expiration of this timer, the receipt ofHANDOVER INDICATION message is ignored.
Value range: [0 to 60] s
Object: adjacentCellHandOver
Default value: 30 s
Type: DP, Optimization
Rec. value: between 8 and 30 s
Used in: General protection against HO ping-pong
Eng. Rules: The value of “HOPingpongTimeRejection” may be between 8 and 30to have a real impact. The following rule can be applied:
HOPingpongTimeRejection = 50% TCH effective occupancy averagein a cell.
If the rescue handovers are disabled in the network a too high valuecan result in dropped calls.The value depends on the speed of the mobile, the size of the cell andthe type of cell (micro-micro etc).For an area where there are ping-pong handovers on “Quality” cause(the first HO occurs on “Quality” reason, the second one on PBGT),the value corresponds to the distance between the interference pointand the limit of the cell.Care must be taken for small cells with high speed mobiles.See also chapter Minimum Time Between Handover
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hoSecondBestCellConfiguration Class 3 V9
Description: Number of neighbor cells in which the BSC immediately attempts to
perform a new handover when the previous handover attempt failedwith return to the old channel
Giving the attribute a value greater than 2 allows the BSC to renewthe handover request without waiting for a new set of radiomeasurements (the first attempt is included in this count). The samelist of neighbor eligible cells is used to process the request (no new listis provided by the BTS).
Value range: [1 to 3]
Object: bsc
Default value: 3
Type: DP, Design
Rec. value: 3Used in: Handover to 2nd best candidate when return to old channel
Eng. Rules: The value 1 means no new attempt after a handover failure, 2 meansone new attempt and 3 corresponds to another new attempt if the firstnew attempt has failed. The recommended value optimizes thehandover completion rate.
Comment about the process: when all handover attempts have failed,the mobile returns on the previous channel. The measurement historyis then complety lost, and the BTS will wait until the next (HReqAve xHReqt) period to relaunch a handover request.See also chapter Directed Retry Handover Benefit
hoTraffic Class 3 V12
Description: Whether handovers for traffic reasons at bts level are allowed.
Value range: [disabled / enabled]
Object: bts
Default value: enabled
Type: DP, Optimization
Rec. value: enabled
Used in: Handover for traffic reasons
Eng. Rules: “enabled” will be effective only if it is also “enabled” for the bsc object.
In order to activate the feature “handover decision according toadjacent cell priority and load” (TF716), either hoTraffic shall be“enabled” or btsMSAccessClassBarringFunction shall be “enabled”(with also bscMSAccessClassBarringFunction).See parameter hoMarginTrafficOffset
hoTraffic Class 3 V12
Description: Whether handovers for traffic reasons at bsc level are allowed.
Value range: [disabled / enabled]
Object: bsc
Default value: disabled
Type: DP, Optimization
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Rec. value: enabled (only if “hot spot”cells linked to the BSC)
Used in: Handover for traffic reasons
Eng. Rules: See parameter hoMarginTrafficOffset
incomingHandOver Class 3 V7
Description: Whether incoming handovers are allowed in a cell.
Value range: [disabled / enabled]
Object: handOverControl
Default value: enabled
Type: DP
Rec. value: enabled
Used in:
Eng. Rules:
msTxPwrMax Class 3 V7
Description: Maximum MS transmission power in a serving cell. It is equal tomsTxPwrMaxCCH in a GSM 900 network.
Value range: [5 to 43, by steps of 2] dBm (GSM 900, GSM850, GSM-R, GSM850-GSM1900 and GSM 900 - GSM 1800 networks)
[0 to 36, by steps of 2] dBm (GSM 1800, and GSM 1800 - GSM 900networks)[0 to 33] dBm (GSM 1900 network)[0 to 33] dBm (E-GSM network and 1900-850 network)[0 to 33] dBm (GSM850 network)
Object: bts
Default value: Typical value of 33 dBm for GSM 900 handhelds and 30 dBm forGSM 1800 and 1900 handhelds
Type: DP, Optimization
Rec. value: 33 dBm for GSM 900 in urban environment
39 dBm for GSM 900 in rural environment handhelds
30 dBm for GSM 1800 and 1900 handhelds
33 dBm for GSM 850s
Used in: Accuracy related to measurements
General formulas
Forced Handover One shot power control Power control on mobile side
Eng. Rules: We must have msTxPwrMax = msTxPwrMaxCCH for GSM 900Networks and msTxPwrMaxCCH ≤ msTxPwrMax for GSM 1800 and1900 Networks (check done at OMC-R). This parameter is adapted tomobile classes taken into account in Network Design.
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msTxPwrMaxCell Class 3 V7
Description: Maximum MS transmission power in a neighbor cell. It is equal to
msTxPwrMaxCCH when the cell is declared as a serving cell on thenetwork (the value must be checked by users).
Value range: [5 to 43, by steps of 2] dBm (GSM 900, GSM850, GSM-R and GSM900 - GSM 1800 networks)
[0 to 36, by steps of 2] dBm (GSM 1800 networkand GSM 1800 - GSM 900)[0 to 33] dBm (GSM 1900 network)[0 to 33] dBm (E-GSM network)[0 to 33] dBm (GSM 1900-850 network)
Object: adjacentCellHandOver
Default value: Typical value of 33 dBm for GSM 900/850 handhelds and 30 dBm forGSM 1800 and 1900 handhelds
Type: DP, Optimization
Rec. value: msTxPwrMaxCell = msTxPwrMaxCCCH of the current cell
Used in: General formulas
Handovers screening Directed Retry Handover: BTS (or distant) mode Forced Handover Define eligible neighbor cells for intercell handover (except directedretry) One shot power control Power control on mobile side
See Paragraph 2.5.1 and Paragraph 2.7.
Eng. Rules: If this value is higher than the actual MS classmark, then MS will applyits own capability.
Remark: If the cell is used as a neighbor cell of another serving cell in thenetwork, msTxPwrMaxCell should be identical to themsTxPwrMaxCCH power defined for the correspondingadjacentCellHandOver object (the values must be checked by users).
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offsetLoad Class 3 V12
Description: Load offset applied by the bsc in the cell selection process of the
Handover algorithm.Value range: [0 to 63] dB
Object: adjacentCellHandOver
Default value: 0 dB
Type: DP, Optimization
Rec. value: 3 dB
offsetLoad ≥ hoMarginTrafficOffset (Handovers for traffic reasonfeature activated)
Used in: Handover decision according to adjacent cell priorities and load Eng.Rules: When set to “0”, no offset is effective.
This parameter is set to “0” for the cells that do not belong to the
related bsc object.This parameter allows to put a disadvantage to overloaded eligiblecells for HO (for cells with the same offsetPriority).In order to take into account this parameter, the overload detectionmust be activated ; so either hoTraffic shall be “enabled” (bsc and btsobjects) or btsMSAccessClassBarringFunction shall be “enabled”(with also bscMSAccessClassBarringFunction). A bad offset load parameter tuning can induce a risk of ping-pong HOor longer handover procedures; so, it is advised to set the “Generalprotection against HO ping-pong” feature withHOPingpongCombination including (traffic, all PBGT).See also chapter Handover for Traffic Reasons Activation Guideline.
offsetPriority Class 3 V12
Description: Priority offset applied by the bsc to the cell selection process in theHandover algorithm
Value range: [1 to 5]
Object: adjacentCellHandOver
Default value: 1
Type: DP, Optimization
Rec. value: 1
Used in: Handover decision according to adjacent cell priorities and load
Eng. Rules: “1” is the highest priority.
This parameter allows to classify eligible cells according to its value;so, it is used to optimize the traffic distribution between layers.See also chapter DualBand Networks.
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powerBudgetInterCell Class 3 V7
Description: Authorization to perform intercell handovers for power budget
Value range: [enabled / disabled]
Object: handOverControl
Default value: enabled
Type: DP, Optimization
Rec. value: enabled
Used in: Handovers screening
Power budget formula Handover for traffic reasons
Eng. Rules: Handover on PBGT should be enabled, because for an optimizednetwork it ensures the best quality of service.
runHandOver Class 3 V7
Description: Number of Measurement Results messages that must be receivedbefore the handover algorithm in a cell is triggered
Value range: [1 to 31] SACCH frames (1 unit = 480 ms on TCHs, 470 ms onSDCCHs)
Object: bts
Default value: 1
Type: DP, System
Rec. value: 1
Used in: Handovers
Microcellular Algo type A Protection against RunHandover=1
Eng. Rules: Should be run as often as possible, main impact is upon BSS load.
Therefore, runHandOver may be set to 1 in some environments wherethe reactivity is crucial (microcell, high-speed environment). it isrecommended to set this parameter to 1. However, this parametersetting must be done in accordance with the value of handoverthresholds, margins and timers.See also chapter Impact of the Averaging on the Handovers andchapter Street Corner Environment
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rxLevMinCell Class 3 V7
Description: Minimum signal strength level received by MS for being granted
access to a neighbor cellValue range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: adjacentCellHandOver
Default value: - 95 to -94 dBm (GSM 900 & 850), - 93 to - 92 (GSM 1800 & 1900)
Type: DP, Optimization
Rec. value: - 95 to - 94 dBm (GSM 900 & 850)
- 93 to - 92 dBm (GSM 1800& 1900) in urban environment
RxLevMinCell = lRxLevDLH if HOmargin ≥ 0 in rural environment
Used in: General formulas
Handovers screening
Define eligible neighbor cells for intercell handover (except directedretry)
Eng. Rules: A method to estimate this value is to use MS sensitivity (-104 dBm inGSM 900 for handheld, and -102 dBm in GSM 1800/1900 forhandheld, otherwise -104 dBm) and applying a margin to it. However,if most of communications are handled in an indoor environment, oroverlap between cell coverage is not sufficient, these recommendedvalues can be decreased.
For a dual Band Network where one frequency band is privileged, it isadvised to set this parameter to a lower value in neighbour cellsbelonging to the priority frequency band. Thus, this band will bepreferred. However, it may be greater than the value rxLevAccessMin.Thus the recommended value is -99 to -98 dBm (GSM900) or -97 to -96 dBm (GSM1800) for neighbour cells belonging to the priorityfrequency band.Studies have shown that the subjective quality depends on the wayerroneous bits are spread into each frame. Experiments have shownthat with frequency hopping in TU3 (Typical urban at 3 Km/h) up toRxqual = 5 the subjective quality seems to be good, on the other handwithout frequency hopping Rxqual = 4 seems to be the maximumvalue for which subjective quality is good.The table below gives examples of the margins that could be takeninto account for an infinite C/I and for different mobile speeds.
t 50 km/h u 50 km/h - t 80 km/h u 80 km/h
margin with FH 2 dB 2 dB 2 dB
margin without FH 5 dB 4 dB - 2 dB 2 dB
And that other table below shows the different margins that could betaken into account in a slow mobile area depending of the C/I.
C/I = 35 C/I = 20 C/I = 15
margin with FH 2 dB 3 dB 4 dB
margin without FH 5 dB 6 dB 10 dB
See also chapter Directed Retry Handover Benefit and chapter
DualBand Networks.
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synchronized Class 3 V7
Description: Whether the neighbor cell and the associated serving cell aresynchronous, that is attached to the same BTS
Value range: [not synchronized cells / synchronized cells / pre sync HO with timing
advance / pre sync HO, default timing advance]
“not synchronized cells”: the neighbor cell and the serving cell are
not attached to the same BTS.
“synchronized cells”: the neighbor cell and the serving cell are
attached to the same BTS
“pre sync HO with timing advance”: the handover procedure
between the neighbor cell and the serving cell is pre–synchronized
with the real Time Advance.
“pre sync HO, default timing advance”: a pre–defined timing
advance is used in the pre–synchronized handover procedure
between the serving cell and the neighbor cell. Refer topreSynchroTimingAdvance parameter.
Object: adjacentCellHandOver
Default value: not synchronized cells
Type: DP, Optimization
Rec. value: See Eng. Rules
Used in: Pre-synchronized HO
Handover Algorithms on the Mobile Side
Eng. Rules: It is recommended to use pre-synchronized HO in microcellularenvironment because in small cells the timing advance whenhandovers are triggered is generally a low value (less than 3).
It is also interesting to use this feature for determined path such asrailways, highways, and tunnels where handovers between two cellshappen always at the same place.See also chapter Synchronized HO versus Not Synchronized HO
timeBetweenHOConfiguration Class 3 V9
Description: Whether the HOPingpongTimeRejection timer can be used in a BSSwhen processing handovers. Refer to bts object bts time between HOconfiguration and adjacentCellHandOver objectHOPingpongTimeRejection attributes in this Dictionary of Parameters.
Value range: [used / not used]
Object: bsc
Default value: used
Type: DP, Design
Rec. value: used
Used in: Power Budget Handover
General protection against HO ping-pong
Eng. Rules: see Engineering Rules for the parameter bts time Between HOConfiguration.
See also chapter Minimum Time Between Handover and chapterDirected Retry Handover Benefit.
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5.12. INTRACELL HANDOVER PARAMETERS
intraCell Class 3 V7
Description: Whether intra–bts handovers on TCH are allowed in a cell forinterference reasons or Cell Tiering reasons
Value range: [cellTieringHandover / intraCellHandover / handoverNotAllowed]
cellTieringHandover: the intraBTS handovers are allowed for
CellTiering reason
intraCellHandover: the intraBTS handovers are allowed for
interference reason
handoverNotAllowed: the intra bts handovers are not allowed
Object: handOverControl
Default value: handoverNotAllowed
Type: DP, Design
Rec. value: cellTieringHandover
Used in: Intracell Handover decision for signal quality
Eng. Rules: For mono-TRX cell, do not enable intracell handover(handoverNotAllowed).
As the MS power is not checked before performing an intracellhandover, it is not advised to enable this feature as intraCellHandover.It would lead to a high ratio of intracell handover.To enable “tiering”, the cell tiering conditions shall be fulfilled and thecell tiering advantages shall be estimated as well (see chapter Automatic cell tiering and hoMarginTiering parameter).
intraCellSDCCH Class 3 V8
Description: Whether intraBTS handovers on SDCCH are authorized in a cell forinterference reasons
Value range: [enabled / disabled]
Object: handOverControl
Default value: disabled
Type: DP, Optimization
Rec. value: disabled
Used in: Intracell Handover decision for signal quality
Eng. Rules: None except system ability.
Note that, some mobiles have been reported to drop the call whenthat feature is performed.
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rxLevDLIH Class 3 V7
Description: Maximum interference level in BTS–to–MS direction, beyond which an
intraCell handover may be triggeredValue range: [less than -110, -110 to -109,..., -49 to -48, more than -48] dBm
Object: handOverControl
Default value: -85 to -84 dBm
Type: DP, Optimization
Rec. value: -85 to -84 dBm
Used in: Intracell Handover decision for signal quality
Eng. Rules:
CAUTION! Path balance must be looked for this threshold parameter setting.
rxLevULIH Class 3 V7
Description: Maximum interference level in MS–to–BTS direction, beyond which anintra cell handover may be triggered
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm.
Object: handOverControl
Default value: -85 to -84 dBm
Type: DP, Optimization
Rec. value: -85 to -84 dBm
Used in: Intracell Handover decision for signal quality
Eng. Rules:CAUTION! Path balance must be looked for this threshold parameter setting.
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rxQualDLIH Class 3 V12
Description: Bit error rate threshold in BTS-to-MS direction for intracell handover,
above which a handover may be triggered.Value range: [less than 0.2, 0.2 to 0.4, 0.4 to 0.8, ... , 6.4 to 12.8, more than 12.8] %
Object: handOverControl
Default value: 1.6 to 3.2 %
Type: DP, Optimization
Rec. value: rxQualDLIH ≤ lRxQualDLH
Used in: Intracell Handover decision for signal quality
Eng. Rules: Intracell HO for signal quality uses a different threshold than theintercell one and intracell HO can only use either hopping channelshaving low interference or non hopping channels having lowinterference. This should improve the voice quality and the
performance.The possible drawback could be to increase queuing at BSC level fornetworks experiencing interferences.To favor intracell HO for quality (compared to intercell HO for quality),the following rule shall be satisfied: rxQualDLIH < lRxQualDLH.The intracell HO has a lower priority than the intercell HO for quality.
rxQualULIH Class 3 V12
Description: Bit error rate threshold in MS-to-BTS direction for intracell handover,above which a handover may be triggered.
Value range: [less than 0.2, 0.2 to 0.4, 0.4 to 0.8, ... , 6.4 to 12.8, more than 12.8] %Object: handOverControl
Default value: 1.6 to 3.2 %
Type: DP, Optimization
Rec. value: rxQualULIH ≤ lRxQualULH
Used in: Intracell Handover decision for signal quality
Eng. Rules: Intracell HO for signal quality uses a differentthreshold than theintercell one and intracell HO can only use either hopping channelshaving low interference or non hopping channels having lowinterference. This should improve the voice quality and theperformance.
The possible drawback could be to increase queuing at BSC level fornetworks experiencing interferences.To favor intracell HO for quality (compared to intercell HO for quality),the following rule shall be satisfied: rxQualULIH < lRxQualULH.The intracell HO has a lower priority than the intercell HO for quality.
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5.13. INTERCELL HANDOVER THRESHOLD PARAMETERS
lRxLevDLH Class 3 V7
Description: Signal strength threshold in BTS–to–MS direction, below which ahandover may be triggered
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handOverControl
Default value: -101 to -100 dBm (GSM 900) / -99 to -98 dBm (GSM1800/1900)
Type: DP, Optimization
Rec. value: -95 to -94 dBm in urban environment (900 MHz or 850 MHz)
-101 to -100 dBm in rural environment (900 MHz or 850 MHz)
Used in: Handover condition for leaving a cell on rxlev
Define eligible neighbor cells for intercell handover (except directed
retry)
Eng. Rules: This threshold must be set from the MS sensitivity. A margin must betaken to consider shadowing, fast fading and MS measurementaccuracy. At least, a 3 dB margin can be taken into account in a ruralenvironment and a 10 dB margin in an urban environment.
CAUTION! where the cell is declared as a neighbor, we should have: lRxLevDLH< rxlevMinCell, and path balance must be considered for thisthreshold parameter setting.
See also chapter lRxlevDLH and lRxlevULH Definition.
lRxLevULH Class 3 V7Description: Signal strength threshold in MS–to–BTS direction, below which a
handover may be triggered
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handOverControl
Default value: -101 to -100 dBm (GSM 900) / -99 to -98 dBm (GSM 1800/1900)
Type: DP, Optimization
Rec. value: -95 to -94 dBm in urban environment (900 MHz or 850 MHz)
-101 to -100 dBm in rural environment (900 MHz or 850 MHz)
Used in: Handover condition for leaving a cell on rxlev
Eng. Rules: The recommended values given above correspond to the worst caseBTS (e-cell). An e-cell has -104 dBm Rx sensitivity in all frequencybands and diversity is not applicable, thus leading to "-95 to -94" forurban environments and "-101 to -100" for rural environments whenapplying a 3dB margin in a rural environment and a 10 dB margin inan urban environment. In fact, these thresholds depend on BTSsensitivity. Values should be increased if one of the following points isverified:
the thresholds on quality are permissive
run-handover 3 scarce
mobile speed is high
initial tuning causes frequent level strength handover failure rate
At least, a 3 dB margin can be taken into account in a ruralenvironment and a 10 dB margin in an urban environment.
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CAUTION! where the cell is declared as a neighbor, we should have: lRxLevULH< rxLevMinCell, and path balance must be considered for thisthreshold parameter setting.
See also chapter lRxlevDLH and lRxlevULH Definition.
lRxQualDLH Class 3 V7
Description: Bit error rate threshold in BTS–to–MS direction, above which an intercell handover may be triggered
Value range: [less than 0.2, 0.2 to 0.4, 0.4 to 0.8, ... , 6.4 to 12.8, more than 12.8] %
Object: handOverControl
Default value: 1.6 to 3.2 %
Type: DP, Optimization
Rec. value: 1.6 to 3.2 % (4 in rxqual GSM unit) without frequency hopping.
See Engineering Rules in case of frequency hopping.
Used in: Handover condition for leaving a cell on rxqual
Eng. Rules: According to some experiments and studies, 4 in GSM unit is theupper limit for TU3 no hopping, while 5 in GSM unit for TU3 hopping.Suggested values become 4 in GSM unit (no frequency hopping orMS speed > 80km/h) and 5 in GSM unit (frequency hopping and lowurban speed). High BER rate for threshold is dangerous (risk ofhandover failure). On the contrary, if a tight rxqual threshold is linkedwith a short averaging period, the risk is that a single bad qualityreport will affect the whole result (ie: if 8 samples without weightingand a threshold of 2 in GSM unit: if 7 of these samples are 2 in GSMunit and 1 of them is 5 in GSM unit, handover decision will be takenon a wrong basis). Experience shows whatever the MS speed, rxQual
= 6 does not provide a comfortable voice quality.The average in the above is equal to:(7 * 0.57 + 4.53) B 8 = 1.065 greater than 0.57 (2 in GSM unit).In case of using synthesized frequency hopping, this threshold has tobe increased in order to limit the increase of the number of handoveron quality criteria.In a 1X1 pattern, it is advised to set this value to 5 or 6 (3.2 to 6.4 %or 6.4 to 12.8 %).In case of a 1X3 pattern, the recommended value is 4 or 5 (1.6 to 3.2% or 3.2 to 6.4 %).DTX is often used with Frequency Hopping. There are lessmeasurement reports with DTX, and thus the RxQual_average maybe less reliable. But no degradation was observed when using both
features therefore there is no need to disable handovers on qualitycriteria in this case.
lRxQualULH Class 3 V7
Description: Bit error rate threshold in MS–to–BTS direction, above which an intercell handover may be triggered
Value range: [less than 0.2, 0.2 to 0.4, 0.4 to 0.8, ... , 6.4 to 12.8, more than 12.8] %
Object: handOverControl
Default value: 1.6 to 3.2 %
Type: DP, Optimization
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5.14. HANDOVER FOR MICROCELLULAR NETWORKPARAMETERS
cellType Class 3 V7
Description: Type of the adjacent cell
Value range: [normalType / umbrellaType / microType]
Object: adjacentCellHandOver
Default value: normalType
Type: DP, Design
Rec. value: normalType
Used in: Microcellular Algo type A
Eng. Rules: To run a capture handover (umbrella to micro) on a neighbor, whichmust be microType, the bts must be declared as umbrellaType. It ispossible to manage a three layer network by declaring cell A and cellB as umbrellaType, neighbor B and neighbor C as microType for cell A, neighbor A as umbrellaType and neighbor C as microType for cellB, and finally neighbor B as umbrellaType for cell C.
See also chapter Minimum Time Between Handover
cellType Class 3 V7
Description: Type of the serving cell
Value range: [normalType / umbrellaType / microType]
Object: bts
Default value: normalType
Type: DP, Design
Rec. value: normalType
Used in: Microcellular Algo type A
Eng. Rules: To run a capture handover (umbrella to micro) on a neighbor, whichmust be microType, the bts must be declared as an umbrellaType. Itis possible to manage a three layer network by declaring cell A andcell B as umbrellaType, neighbor B and neighbor C as microType forcell A, neighbor A as umbrellaType and neighbor C as microType forcell B, and finally neighbor B as umbrellaType for cell C.
Remark: The adjacent cell umbrella Ref attribute is defined at the OMC-R if the
cell is a microcell (cellType) and directed retry handovers areprocessed in BSC mode (directed-RetryModeUsed).
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microCellCaptureTimer Class 3 V8
Description: Time used to confirm a capture (signal strength stability) when using
microcell Algorithm type AValue range: Time = N multiplied by runHandOver .
According to microCellCaptureTimer value, N values are thefollowing:
[0 to 249] N = [0 to 249]
250 N = 512
251 N = 1024
252 N = 2048
253 N = 4096
254 N = 8192
255 N = 16384
Object: adjacentCellHandOver
Default value: 0
Type: DP, Design
Rec. value: 8s, whatever runHandOver value
(e.g. if runHandOver = 2 N = 8, if runHandOver = 1 N = 16)
Used in: Microcellular Algo type A
Eng. Rules: Experiments done in urban areas show that a timer of 8 seconds to 10seconds allows a better use of the capture.
See also chapter Impact of the Averaging on the Handovers.
microCellStability Class 3 V8
Description: Strength Level Stability Criterion for Capture Algorithm A
Value range: [0 to 255] dB
Object: adjacentCellHandOver
Default value: 10 dB
Type: DP, Design
Rec. value: 63 dB
Used in: Microcellular Algo type A
Eng. Rules: To allow handovers on capture this parameter has to be set at a value
greater than 0. A value of microCellStability equal to 63 dB has to beset first, because with such a value, the stability constraints arealways verified.
The value of this parameter can then be decreased case by case.
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5.15. DISTANCE MANAGEMENT PARAMETERS
callClearing Class 3 V7
Description: Maximum distance between MS and BTS before call is cleared
It is greater than msRangeMax.This distance defines the cell maximum coverage area.
Value range: [2 to 35] km (non-extended mode)
[2 to 120] km (extended mode)
Object: bts
Default value: 35 in non-extended mode, 90 in extended mode
Type: DP, Product
Rec. value: Depends on the environment, typical value = (1.5 * cell diameter)+ 2 km or best cell distance coverage server
Generaly for non-extended mode: 7 km for urban, 35 km for rural
Used in: Call Clearing Process (run by BTS) (Cc)
Eng. Rules: The value should be related to the current cell coverage. A margin istaken by using the 1.5 coefficient. A 2km margin is also considered tocompensate lack of mobile timing advance accuracy.
If the observation counter shows a high number of call clearings, itmay mean that handover parameters on that cell are too permissive orbadly tuned. At the OMC-R, a control exists: callClearing > msRangeMax
extended cell Class 2 V9
Description: Whether the cell is extended (up to 120 km large) or not
The cell working mode governs the upper limit of the followingattribute values (refer to theses entries in the Dictionary):
callClearing, msRangeMax, and rndAccTimAdvThreshold
attributes of the bts object
concentAlgoExtMsRange and concentAlgoIntMsRange attributes
of the associated handOverControl object if the bts object
describes a concentric cell
Value range: [true (extended) / false (normal)]
Object: bts
Default value: false
Type: DP, Optimization
Rec. value: see Engineering Rules
Used in:
Eng. Rules: Extended cells will be used to reach mobiles that are far from the BTS(in the case of sea shores and pleasure boats, for example).
In an extended cell, two consecutive time slots are reserved for eachchannel. The capacity is then decreased.
CAUTION! Up to V10, an extended cell cannot be concentric. Whatever the MS-BTS distance is, two consecutive time slots are reserved on Airinterface.
See also chapter SDCCH Dimensioning an TDMA Models.
CAUTION! GPRS/EDGE is not supported when extended cell feature is activated.
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msRangeMax Class 3 V7
Description: Maximum MS–to–BTS distance beyond, which a handover may betriggered. It can be set to 1 for a microcell and is less than callClearingin all cases.
Value range: [1 to 34] km (non-extended mode)
[1 to 120] km (extended mode)
Object: handOverControl
Default value: 34 in non-extended mode, 89 in extended mode
Type: DP, Optimization
Rec. value: = callClearing - 1 km
Used in: Handover condition for leaving a cell on distance
Eng. Rules: If the associated serving cell is a concentric cell, the followinginequality, that is not checked by the system, must be true (refer to
this entry in the Dictionary):concentAlgoExtMsRange ≤ concentAlgoIntMsRange ≤ msRangeMax
CAUTION! callClearing > msRangeMax is controled at the OMC level. It must beadapted to current cell extent in order to be an efficient preventivehandover. If value is too small, there is a big risk of ping-ponghandover.
CAUTION! Due to lack of mobile timing advance accuracy this parameter mustnot be set at a too low value (not < 2). Generaly for non-extendedmode (6 km for urban and 34 km for rural)
msBtsDistanceInterCell Class 3 V7
Description: Whether inter–bts handovers are allowed in a cell for distancereasons
Value range: [enabled / disabled]
Object: handOverControl
Default value: enabled
Type: DP, Optimization
Rec. value: enabled
Used in: Handovers screening
Handover condition for leaving a cell on distance
Eng. Rules: Due to the imprecision of some MS on Timing Advance (see chapterDistance - timing advance conversion) and due to the delay spread ina very urban environment, it is possible to set this parameter to“disabled” (in an urban environment). However, for all cells with aradius of more than 1 km, handover on distance must be authorized.
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preSynchroTimingAdvance Class 3 V10
Description: Pre-defined timing advance used in a pre-synchronized handover
procedure between the serving cell and this neighbor cell.Value range: [1 to 35] (km)
Object: adjacentCellHandOver
Default value: Refer to parameter synchronized
Type: DP, Design
Rec. value: see Engineering Rules
Used in: Pre-synchronized HO
Eng. Rules: This value of timing advance is used when the parametersynchronized is set to “pre sync HO with timing advance”. Apredefined timing advance can be defined when phase 2 MSs alwayshandove from the serving cell to this neighbor cell approximately at
the same place (railway, highway).If the parameter synchronized is set to “presyncho HO, default timingadvance”, the default TA value is “-1” (554 m).If the parameter synchronized is set to “presyncho HO, with timingadvance”, the parameter preSynchroTimingAdvance must be tuned tothe estimated value of TA.See also chapter Synchronized HO versus Not Synchronized HO.
CAUTION! preSynchroTimingAdvance value is not controlled at the OMC-R
rndAccTimAdvThreshold Class 3 V8
Description: MS–to–BTS distance beyond which mobile access requests to a cellare refused.
It defines the maximum timing advance value accepted.The effective timing advance value is broadcast in the CHANNELREQUIRED message sent by the BTS to the BSC. If it is above theuser defined threshold, the BSC ignores the request.
Value range: [2 to 35] km (non-extended mode)
[2 to 120] km (extended mode)
Object: bts
Default value: 35 (non-extended cell), 90 (extended cell)
Type: DP, Optimization
Rec. value: msRangeMax (= call clearing - 1km = 1.5* cell diameter + 2 km -1km)
Generally for non-extended mode: 6 km for urban, 35 km for rural
Used in: Request access command process (RA)
Eng. Rules: The maximum authorized value will inhibit the feature.
By adjusting the value to the size of the cell (see recommendedvalue), parasite RACH (noise which is decoded by the system like aRACH) are filtered. This avoids the unnecessary assigment ofSDCCH.For example, for small cells, if the value is 35 km, almost 30% of theRACHs are parasite. If the value is modified to 2, almost no parasitesRACH are detected.
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runCallClear Class 3 V7
Description: Number of “Measurement Results” messages that must be receivedbefore the call clearing algorithm in a cell is triggered
Value range: [1 to 31] SACCH frames (1 unit = 480 ms on TCHs, 470 ms on
SDCCHs)
Object: bts
Default value: 16
Type: DP, System
Rec. value: 16
Used in: Call Clearing Process (run by BTS) (Cc)
Eng. Rules: It is not necessary to run Cc too often, since those calls are going tobe ended anyway. Nevertheless, traffic out of a cell’s range interfereson other cells or timeslots.
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5.16. POWER CONTROL PARAMETERS
bsMsmtProcessingMode Class 2 V7
Description: Whether radio measurements collected by the mobiles for a cell areprocessed by the BTS or the BSC
Value range: [preProcessedMeasurementReporting (BTS) /basicMeasurementReporting (BSC)]
Object: bts
Default value: preProcessedMeasurementReporting
Type: DP, Product
Rec. value: preProcessedMeasurementReporting
Used in: Measurement Processing
Eng. Rules: Since radio measurements are always preprocessed by the BTS,
changing this attribute has no meaning.
bsPowerControl Class 3 V7
Description: Whether BTS transmission power control is allowed at cell level
Value range: [enabled / disabled]
Object: powerControl
Default value: disabled
Type: DP, Optimization
Rec. value: enabled
Used in: Step by step Power control One shot power control Fast power control at TCH assignment Power Control (AMR)
Eng. Rules: Not useful for mono-TRX cells, because BTS power control on BCCHfrequency is not allowed.
CAUTION! During a measurement field campaign, it can be normal to disable thisfeature in order to have the real signal strength and not the adjustedone.
bsTxPwrMax Class 3 V7
Description: Maximum theoretical level of BTS transmission power in a cell
The BSC relays the information to the mobiles in the Abis CELLMODIFY REQUEST message.
Value range: [0 to 47] dBm
Object: powerControl
Default value: 43 dBm
Type: DP, Optimization
Rec. value: depends on the equipment
Used in: General formulas
Cabinet Output Power Setting
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Eng. Rules: This power is used to calculate the cabinet output power. It dependson the attribute “attenuation” of btsSiteManager objects (see chapterPr computation), because the value of the parameter “attenuation” isthen taken into account as DLU attenuation.
Remark: For a GSM 1900 network (standardIndicator of bts object set to
‘pcs1900’), the MD-R checks the following: bsTxPwrMax < 32 (dBm)when an edge frequency is defined for the cell (i.e. if the value isincluded in the cellAllocation attribute values).
Some bsTxPwrMax values are not compatible with the effective poweroutput by the BTS (see chapter Pr computation).
lRxLevDLP Class 3 V7
Description: Signal strength threshold in BTS–to–MS direction, below which thepower control function increases power. It is lower than uRxLevDLP.
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: powerControl
Default value: -95 to -94 dBm
Type: DP, Optimization
Rec. value: -95 to -94 dBm (step by step)
-85 to -84 dBm (one shot)
Used in: Step by step Power control
One shot power control Fast power control at TCH assignment Power Control (AMR)
Eng. Rules: The difference between lower and upper thresholds must be greater
or equal to max (powerIncrStrepSize, powerRedStepSize), because itis controled at the OMC level.
lRxLevDLP > lRxLevDLH, up to V7, because power Control andhandover algorithms are decorrelated.
CAUTION! In case the AMR power control algorithm is activated ( refer to theamrReserved2 parameter) that parameter defines the threshold belowwhich the AMR power control is inhibited.
In that case the recommended values remain the same if the AMRpenetration is low, and the same + 2dB if the AMR penetration is high.
lRxLevULP Class 3 V7
Description: Signal strength threshold in MS–to–BTS direction, below which thepower control function increases power. It is lower than uRxLevULP.
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: powerControl
Default value: -95 to -94 dBm
Type: DP, Optimization
Rec. value: -95 to -94 dBm (step by step)
-85 to -84 dBm (one shot)
Used in: Step by step Power control
One shot power control
Fast power control at TCH assignment Power Control (AMR)
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Eng. Rules: lRxLevULP > lRxLevULH, up to V7, because power Control andhandover algorithms are decorrelated.
CAUTION! In case the AMR power control algorithm is activated ( seeamrReserved2 parameter) that parameter defines the threshold belowwhich the AMR power control is inhibited.
In that case the recommended values remain the same if the AMRpenetration is low, and the same + 2dB if the AMR penetration is high.
lRxQualDLP Class 3 V7
Description: Bit error rate threshold in BTS–to–MS direction, above which thepower control function increases power. It is greater than or equal touRxQualDLP.
Value range: [less than 0.2, 0.2 to 0.4, 0.4 to 0.8, ... , 6.4 to 12.8, more than 12.8] %
Object: powerControl
Default value: 0.4 to 0.8Type: DP, Optimization
Rec. value: 0.8 to 1.6 % (RxQual = 3 in GSM unit) without SFH
3.2 to 6.4 % (RxQual = 5 in GSM unit) with SFH
Used in: Step by step Power control
One shot power control Fast power control at TCH assignment Power Control (AMR)
Eng. Rules: This value must be lower than lRxQualDLH in order to maintainpriority between power control and handover.
lRxQualULP Class 3 V7
Description: Bit error rate threshold in MS–to–BTS direction, above which thepower control function increases power. It is greater than or equal touRxQualULP.
Value range: [less than 0.2, 0.2 to 0.4, 0.4 to 0.8, ... , 6.4 to 12.8, more than 12.8] %
Object: powerControl
Default value: 0.4 to 0.8
Type: DP, Optimization
Rec. value: 0.8 to 1.6 % (RxQual = 3 in GSM unit) without SFH
1.6 to 3.2 % (RxQual = 4 in GSM unit) with SFH
Used in: Step by step Power control
One shot power control Fast power control at TCH assignment Power Control (AMR)
Eng. Rules: This value must be lower than lRxQualULH in order to maintainpriority between power control and handover.
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powerIncrStepSizeDL Class 3 V14
Description: Increment step size for downlink power control.
Value range: [2, 30] dB
Object: powerControl
Default value: 4 dB
Type: DP, Optimization
Rec. value: 4 dB
Used in: Step by step Power control
Eng. Rules: A high step is required to be reactive in increasing the power whenentering an area where propagation is not acceptable.
A higher step (6 dB) is recommended for specific networks orenvironment (high speed trains for example).The attribute powerIncrStepSizeDL must verify: lRxLevDLP +
powerIncrStepSizeDL ≤ uRxLevDLP
CAUTION! Not used in one shot power control nor in AMR power control.
powerIncrStepSizeUL Class 3 V14
Description: Increment step size for uplink power control.
Value range: [2, 30] dB
Object: powerControl
Default value: 4 dB
Type: DP, Optimization
Rec. value: 4 dB
Used in: Step by step Power control
Eng. Rules: A high step is required to be reactive in increasing the power whenentering an area where propagation is not acceptable.
A higher step (6 dB) is recommended for specific networks orenvironment (high speed trains for example).The attribute powerIncrStepSizeUL must verify:lRxLevULP +powerIncrStepSizeUL ≤ uRxLevULP
CAUTION! Not used in one shot power control nor in AMR power control.
powerRedStepSizeDL Class 3 V14
Description: Decrement step size for downlink power control.
Value range: [2, 8] dB
Object: powerControl
Default value: 2 dB
Type: DP, Optimization
Rec. value: 2 dB
Used in: Step by step Power control
Eng. Rules: Small steps are enough to adapt two subsequent changes in qualityand strength. Moreover, calls become sensitive to low MS or BS
TxPower.
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The attribute powerIncrStepSizeDL must verify: uRxLevDLP –powerRedStepSizeDL ≥ lRxLevDLP
CAUTION! Not used in one shot power control.
powerRedStepSizeUL Class 3 V14
Description: Decrement step size for uplink power control.
Value range: [2, 30] dB
Object: powerControl
Default value: 2 dB
Type: DP, Optimization
Rec. value: 2 dB
Used in: Step by step Power control
Eng. Rules: Small steps are enough to adapt two subsequent changes in quality
and strength. Moreover, calls become sensitive to low MS or BStxPower.
The attribute powerRedStepSizeUL must verify: uRxLevULP –powerRedStepSizeUL ≥ lRxLevULP
CAUTION! Not used in one shot power control.
runPwrControl Class 3 V7
Description: Number of Measurement Results messages that must be receivedbefore the power control algorithm in a cell is triggered.
Value range: [1 to 31] frames (1 unit = 480 ms on TCH, 470 ms on SDCCH)
Object: btsDefault value: 4
Type: DP, System
Rec. value: 2
Used in: Power Control Algorithms
Power Control (AMR)
Eng. Rules: The lowest is the parameter value, the best will be the reactivity;nevertheless, it is better to wait for the effect of MS power decreaseon the uplink quality.
uplinkPowerControl Class 3 V8
Description: Whether power control in the MS–to–BTS direction is authorized atcell level
Value range: [enabled / disabled]
Object: powerControl
Default value: enabled
Type: DP, Optimization
Rec. value: enabled
Used in: Power Control Algorithms
Power Control (AMR)
Eng. Rules:
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uRxLevDLP Class 3 V7
Description: Upper strength threshold for BTS txpwr decrease for step by stepalgorithm (it is greater than IRxLevDLP)
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: powerControl
Default value: -85 to -84 dBm
Type: DP, Optimization
Rec. value: = lRxLevDLP + Max (powerIncrStepSizeDL,powerRedStepSizeDL) typically
Used in: Power Control Algorithms
Eng. Rules: Difference between the lower and upper thresholds must be greater orequal to the maximum power step size.
CAUTION! Not used in one shot power control.
uRxLevULP Class 3 V7
Description: Upper strength threshold for MS txpwr decrease for step by stepalgorithm (it is greater than lRxLevULP).
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: powerControl
Default value: -85 to -84 dBm
Type: DP, Optimization
Rec. value: lRxLevULP + Max (powerIncrStepSizeUL, powerRedStepSizeUL)typically
Used in: Power Control Algorithms
Eng. Rules: Difference between the lower and upper threshold, must be greater orequal to the maximum power step size.
CAUTION! Not used in one shot power control.
uRxQualDLP Class 3 V7
Description: Upper quality threshold to reduce BTS txpwr for step by step algorithm(it is lower than or equal to lRxQualDLP).
Value range: [less than 0.2, 0.2 to 0.4, 0.4 to 0.8, ... , 6.4 to 12.8, more than 12.8] %
Object: powerControl
Default value: 0.2 to 0.4
Type: DP, Optimization
Rec. value: 0.8 to 1.6 % (RxQual = 3 in GSM unit) without SFH
3.2 to 6.4 % (RxQual = 5 in GSM unit) with SFH
Used in: Power Control Algorithms
Eng. Rules: This value must be lower than lRxQualDLH in order to maintainpriority between power control and handover.
CAUTION! Not used in one shot power control.
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uRxQualULP Class 3 V7
Description: Upper quality threshold to reduce MS txpwr for step by step algorithm
(it is lower than or equal to lRxQualULP).Value range: [less than 0.2, 0.2 to 0.4, 0.4 to 0.8, ... , 6.4 to 12.8, more than 12.8] %
Object: powerControl
Default value: 0.2 to 0.4
Type: DP, Optimization
Rec. value: 0.8 to 1.6 % (RxQual = 3 in GSM unit) without SFH
1.6 to 3.2 % (RxQual = 4 in GSM unit) wtih SFH
Used in: Power Control Algorithms
Eng. Rules: This value must be lower than lRxQualULH in order to maintainpriority between power control and handover.
There is no reason why this value should differ from uRxQualDLP.CAUTION! Not used in one shot power control.
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5.17. TCH ALLOCATION MANAGEMENT PARAMETERS
accessClassCongestion Class 3 V9
Description: List of access classes that are not authorized in a cell during TCHcongestion phase (class 10 not included)
Value range: [0 to 9] User classes
[11 to 15] Operator classes
Object: bts
Default value: [0,1,2,3,4,5,6,7,8,9]
Type: DP, Design
Rec. value: see Engineering Rules
Used in: Dynamic barring of access class (All_4)
V15.0 Changes of dynamic barring of access class (All_4)
Eng. Rules: Usually, in a low capacity cell (between 1 and 2 TRXs), many classesmust be forbidden in case of congestion (few resources available). Ina high capacity cell, only a few classes must be forbidden.
allocPriorityTable Class 3 V7
Description: Table of eighteen elements that define the internal priorities forprocessing TCH queued allocation requests for each external prioritydefined (among them, fourteen are GSM priorities)
TCH is always allocated using the internal priority.
Value range: [0 to 12]. “0” defines the highest priority.
Object: bts
Default value: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Type: DP, System
Rec. value: 0 2 2 2 2 2 2 2 2 2 2 2 2 3 0 4 2
0 8 9 10 11 12 2 2 2 2 2 2 2 2 3 0 4 2 for WPS use
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3) WPS – Queuing management
Eng. Rules: The default set means that all TCH allocation requests have the same
priority, which is equal to 0.When queuing is activated, set the following parameters in order notto disadvantage the interCell handover procedures:
Priority for interCell handover: 0
Priority for other procedures: ≠ 0
allocPriorityThreshold > 0
CAUTION! When WPS Queuing Management is activated, the WPS priorities (8to 12) have to be set as recommended, otherwise WPS queues will bemanaged like internal public queues.
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allocPriorityThreshold Class 3 V7
Description: Number of free TCHs needed for processing a TCH allocation request
with an internal priority higher than 1These channels are reserved to allocation requests with a maximuminternal priority (priority 0).The TCH allocation is performed according to this algorithm:
Nb of free TCH = 01 ≤ Nb of free TCH ≤
allocPriorityThresholdNb of free TCH >
allocPriorityThreshold
TCH requestof priority 0
queuing if defined orrejected
TCH allocated TCH allocated
TCH requestof priority > 0
queuing if defined orrejected
queuing if defined orrejected
TCH allocated
For GPRS with shared PDTCH, the allocation is performed accordingto this algorithm: free resources are composed of free TCH andshared PDTCH not already used by a GSM call:
Nb of free TCH = 01 ≤ Nb of free TCH ≤
allocPriorityThresholdNb of free TCH >
allocPriorityThreshold
TCH requestof priority 0
queuing if defined orrejected
TCH allocated if TCHfree > 0
if preemption isauthorized and PCU
ACK, allocation of ashared PDTCH
if preemption is notauthorized or PCUNACK, queuing if
defined or rejected
TCH allocated if TCHfree > 0
if preemption isauthorized and PCU
ACK, allocation of ashared PDTCH
if preemption is notauthorized or PCUNACK, queuing if
defined or rejected
TCH requestof priority > 0
queuing if defined orrejected
queuing if defined orrejected
TCH allocated if TCHfree > 0
if preemption isauthorized and PCU
ACK, allocation of ashared PDTCH
if preemption is notauthorized or PCUNACK, queuing ifdefined or rejected
Value range: [0 to 2147483646]
Object: btsDefault value: 0
Type DP, Design
Rec. value: n, with n TRX
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3)
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Eng. Rules: When TCH channels are reserved and the internal priority forassignRequest is ≠ 0, the capacity for incoming calls decreases:
Example:
1 TRX, 7 TCH, 2 % blocking rate, allocPriorityThreshold = 0,
capacity for incoming calls = 2,88 Erlang
1 TRX, 7 TCH, 2 % blocking rate, allocPriorityThreshold = 1,
capacity for incoming calls = 2,23 Erlang
Queuing spreads out the TCH allocation request. As incominghandover requests are not queued, such requests are disadvantaged. A solution is to reserve 1 TCH channel (for 1 or 2 TRXs) or 2 TCHchannels (for at least 2 TRX) for calls of internal priority 0, and set thepriority 0 for incoming handovers only.Note that when TCH channels are reserved for handovers, thecapacity for incoming calls decreases.
allocPriorityTimers Class 3 V7
Description: Table of timers defining the maximum waiting time of TCH allocationsrequest (public and WPS request), according to the internal priority.
Value range: [0 … 65535] for BSC3000
[0 … 2147483646] for BSC12000
Object: bts
Default value: 0 0 0 0 0 0 0 0 28 28 28 28 28
Type: DP, System
Rec. value: 5 0 5 5 0 0 0 0 28 28 28 28 28
Used in: Queuing driven by the MSC (All_2)
Queuing driven by the BSC (All_3) WPS – Queuing management
Eng. Rules: A high value of timer is not realistic, since a subscriber will not waitunless the last TCH is available quickly. The last five parameters inthe table (those set to 28) define the waiting time of WPS callsqueued.
See also chapter Directed Retry Handover Benefit
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allocWaitThreshold Class 3 V7
Description: Table of thresholds defining the maximum number of TCH allocation
requests queued (public and WPS), according to their internal priority. A TCH request of priority Pi, P0<Pi<P7, is queued if the total numberof requests of priority Pj, with j<i, already in the queue does notexceed the waiting threshold of the queue “i” (element “i” of theallocWaitThreshold table). A WPS request priority is queued according to the rules of WPSqueuing.
Value range: [0 to 63] MMI Range
Object: bts
Default value: 0 0 0 0 0 0 0 0 5 5 5 5 5
Type: DP, System
Rec. value: n 0 n n 0 0 0 0 5 5 5 5 5, with n = integer part of (number ofSDCCH subchannels / 2)
Used in: Queuing driven by the MSC (All_2)
Queuing driven by the BSC (All_3) WPS – Queuing management
Eng. Rules: The maximum size in each queue must be lower than the number ofSDCCH channels in the cell.
For an incoming call, when the assignRequest is queued, it remainson the SDCCH subchannel.The last five parameters in the table are determining the maximumnumber of WPS calls of the same priority that can be queued.
allOtherCasesPriority Class 3 V7
Description: Index in the allocPriorityTable that defines the processing priority ofTCH allocation requests with cause “other cases”
This priority is used in primo–allocations or when an SDDCH cannotbe allocated for overload reasons.
Value range: [0 to 17]
Object: bts
Default value: 17
Type: DP, System
Rec. value: 16
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3)
Eng. Rules: The associated internal priority is > 0.
A TCH allocation request (in signaling mode) whose cause is “othercase” is acknowledged when at least allocPriorityThreshold + 1channels are free.Refer also to the allocPriorityTable parameter.
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answerPagingPriority Class 3 V7
Description: Index in the allocPriorityTable that defines the processing priority of
TCH allocation requests with cause “reply to paging”This priority is used in signaling mode on TCH only.
Value range: [0 to 17]
Object: bts
Default value: 17
Type: DP, System
Rec. valueb 16
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3)
Eng. Rules: The associated internal priority is > 0. A TCH allocation request (in signaling mode) whose cause is “othercase” is acknowledged when at least allocPriorityThreshold + 1channels are free.Refer also to the allocPriorityTable parameter.
assignRequestPriority Class 3 V7
Description: Index in the allocPriorityTable that defines the processing priority ofTCH allocation requests with cause “immediate assignment”
This priority is used when radio resource allocation queuing is notrequested by the MSC or not authorized in the BSS (refer to the
bscQueuingOption parameter).
Value range: [0 to 17]
Object: bts
Default value: 17
Type: DP, System
Rec. value: 17
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3)
Eng. Rules: When queuing driven by the MSC is used, this parameter is not
significant.It is recommended not to associate an internal priority equal to 0.There is no queuing for TCH in “signaling mode”.Refer also to the allocPriorityTable parameter.
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bscMSAccessClassBarringFunction Class 3 V9
Description: Enable or disable dynamic barring of access class at the bsc level
Value range: [enabled / disabled]
Object: bsc
Default value: disabled
Type: DP, Design
Rec. value: enabled, see Engineering Rules
Used in: Dynamic barring of access class (All_4)
V15.0 Changes of dynamic barring of access class (All_4)
Eng. Rules: Set to disabled, this parameter allows to inhibit the dynamic barring ofaccess class feature for the whole BSC whatever the values of theother parameters related to All_4 are.
If queuing or directed retry is activated, the following parameters mustbe used:
numberOfTCHQueuedBeforeCongestion
numberOfTCHQueuedToEndCongestion
bscQueuingOption Class 1 V7
Description: Whether radio resource allocation requests are queued in the BSCwhen no resources are available
If no resource is available when an allocation request is received and queuing is notallowed, the allocation request is refused immediately.
Value range: [allowed (MSC driven) / forced (O&M driven) / not allowed] allowed: resource allocation request queuing depends on the type
of operation and indicative items provided with the messages
received from the MSC.
forced: resource allocation request queuing depends on the type of
operation only.
not allowed: resource allocation request queuing is forbidden.
Object: signallingPoint
Default value: forced
Type: DP, Design
Rec. value: forced (O&M driven)allowed (MSC driven) for WPS use
Used in: Queuing driven by the MSC (All_2)
Queuing driven by the BSC (All_3) WPS – Queuing management
Eng. Rules: When queuing is activated, the queued procedures (assignRequestand intraCellHO if OMC driven) statistically take advantage on theother procedures. If all the TCH channels are already allocated, thequeued procedures stay in the queue during a defined time (seeallocPriorityTimers), when the others are rejected.
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Suppose the operator expects to enable the queuing later. Due to theclass of the parameter bscQueuingOption, it is recommended not toset “not allowed”. Otherwise, the BSC will need to be switched off toimplement the feature.See also chapter Directed Retry Handover Benefit
CAUTION! WPS Queuing Management can be activated only ifbscQueuingOption is set to “allowed”, i.e if MSC can handle differentpriorities of assignement request.
btsMSAccessClassBarringFunction Class 3 V9
Description: Enable or disable dynamic barring of access class at the bts level
Value range: [enabled / disabled]
Object bts
Default value: disabled
Type: DP, DesignRec. value: See Engineering Rules
Used in: Dynamic barring of access class (All_4)
V15.0 Changes of dynamic barring of access class (All_4)
Eng. Rules: To enable dynamic barring of access class at the bts level, thisparameter and the bscMSAccessClassBarringFunction parameter ofthe corresponding bsc must be set to enabled.
This feature globally reduces the cell capacity.The fewer the number of TRXs on the cell, the more the capacity isreduced.
callReestablishmentPriority Class 3 V7
Description: Index in the allocPriorityTable that defines the processing priority ofTCH allocation requests with cause “call reestablishment”
This priority is used in primo–allocations or when an SDDCH cannotbe allocated for overload reasons.
Value range: [0 to 17]
Objectb bts
Default value: 17
Type: DP, System
Rec. value: 15
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3)
Eng. Rules: The value that must be given should correspond to a priority 0.
Refer to the allocPriorityTable parameter.
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cellBarQualify Class 3 V8
Description: Cell selection priority used in the C2 algorithm in Phase II
The information is broadcast to the mobiles at regular intervals on thecell BCCH.
Value range: [true (low priority) / false (normal priority)]
Object: bts
Default value: False
Type: DP, Optimization
Rec. value: False
Used in: Selection or reselection between cells of current Location Area(Sel_1)
Additional reselection criterion (for phase 2) (Sel_3) New SYS INFO messages
Eng. Rules: refer to Sel_3 algorithm, see also chapter DualBand Networks.
cellBarred Class 3 V7
Description: Whether direct cell access are barred to mobiles
The information is broadcast to the mobiles at regular intervals on thecell BCCH.During a call, it is transmitted on a signaling link.If the attribute value is changed to “barred”, all in–progress calls cancontinue but the BSC will direct further mobile calls to another cell.
Value range: [barred / not barred]
Object: btsDefault value: not barred
Type: DP, Optimization
Rec. value: not barred
Used in: Selection or reselection between cells of current Location Area(Sel_1)
Additional reselection criterion (for phase 2) (Sel_3)
Eng. Rules: refer to Sel_3 algorithm, see also chapter DualBand Networks.
channelType Class 2 V7
Description: Type of logical channel supported by a radio TS
Value range: [tCHFull / sDCCH / mainBCCH / mainBCCHCombined /bcchsdcch4CBCH / sdcch8CBCH / cCH (V12) / pDTCH (V12)]
Object: channel
Default value: None
Type: DP, Optimization
Rec. value: None.
No recommended value is specified since this parameterdepends on the strategy of the operator.
Used in:
Eng. Rules: In the case of GSM, refer to chapter SDCCH Dimensioning an TDMAModels for the rules with SDCCH.
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emergencyCallPriority Class 3 V7
Description: Index in the table allocPriorityTable for a TCH allocation request
whose cause is “emergency call”This priority is used in primo–allocations or when an SDDCH cannotbe allocated for overload reasons.
Value range: [0 to 17]
Object: bts
Default value: 17
Type: DP, System
Rec. value: 15
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3)
Eng. Rules: The internal priority associated is 0. A TCH allocation request (insignaling mode) whose cause is “emergency call” is acknowledgedwhen at least 1 channel is free.
Refer also to the allocPriorityTable parameter.
interCellHOExtPriority Class 3 V7
Description: Index in the allocPriorityTable that defines the processing priority ofincoming inter–bss handovers in a cell
This priority is used when radio resource allocation queuing is notrequested by the MSC or not authorized in the BSS (refer to the
bscQueuingOption parameter).
Value range: [0 to 17]
Object: bts
Default value: 17
Type: DP, System
Rec. value: 15
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3)
Eng. Rules: The internal priority associated is 0. A TCH allocation request (in
signaling mode) on interBSC handover is aknowledged when at least1 channel is free.
When queuing is used, it is recommended to give the priority 0 andreserve the TCH channels (allocPriorityThreshold) since itdisadvantages requests that cannot be queued.Refer also to the allocPriorityTable parameter.
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interCellHOIntPriority Class 3 V7
Description: Index in the allocPriorityTable that defines the processing priority of
incoming intra–bss handovers in a cellThis priority is always used, whether radio resource allocation queuingis authorized in the BSS or not.
Value range: [0 to 17]
Object: bts
Default value: 17
Type: DP, System
Rec. value: 15
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3)
Eng. Rules: The internal priority associated is 0.
A TCH allocation request (in signaling mode) on intraBSC handover isaknowledged when at least 1 TCH is free.When queuing is used, it is recommended to give the priority 0 andreserve the TCH channels (allocPriorityThreshold) since itdisadvantages requests that cannot be queued.Refer also to the allocPriorityTable parameter.
intraCellHOIntPriority Class 3 V7
Description: Index in the allocPriorityTable that defines the processing priority of an
intra–bts handover in a cellThis priority is always used, whether radio resource allocation queuingis authorized in the BSS or not.
Value range: [0 to 17]
Object: bts
Default value: 17
Type: DP, System
Rec. value: 14
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2)
Queuing driven by the BSC (All_3) Eng. Rules: Refer also to the allocPriorityTable parameter.
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directedRetryPrio V12
Description: Index in the allocPriorityTable that defines the processing priority for
directed retry handoversValue range: [0 to 17]
Object: bts
Default value:
Type: DP, Optimization
Rec. value: 17
Used in: TCH Allocation Management
Eng. Rules: Refer also to the allocPriorityTable parameter.
intraCellQueuing Class 3 V8
Description: Whether intra–bts handover requests are queued for a cell. Thisparameter is significant only when queuing radio resource allocationrequests is allowed in the BSS.
Refer to the bscQueuingOption parameter.
Value range: [enabled / disabled]
Object: bts
Default value: disabled
Type: DP, Optimization
Rec. value: Enabled
Used in: Queuing driven by the MSC (All_2)
Queuing driven by the BSC (All_3)
Eng. Rules: None.
minNbOfTDMA Class 2 V7
Description: Minimum number of TDMA frames that must be working in order forthe cell itself to be working.
The frame carrying the cell BCCH must be among them and issuccessfully configured.
Value range: [1 to 16]Object: bts
Default value: 1
Type: DP, Optimization
Rec. value: 1
Used in:
Eng. Rules: None.
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notAllowedAccessClasses Class 3 V7
Description: List of mobile access classes that are forbidden in the cell, exceptcase of congestion.
This attribute, together with the emergencyCallRestricted attribute,
allows to control access to a cell according to the service classesauthorized.
Value range: List of mobile access class:
[0 to 9]: user classes
[11 to 15]: operator classes
Object: bts
Default value: Leave the field empty
Type: DP,Operation
Rec. value: “null” (empty list)
Used in: Dynamic barring of access class (All_4)
Changes of dynamic barring of access class (All_4)
Eng. Rules: This parameter contains the list of forbidden access classes. Usuallyall users are authorized, in this case, the list must be empty.
numberOfTCHFreeBeforeCongestion Class 3 V9
Description: Minimum number of free TCHs which triggers the beginning of theTCH congestion phase and the beginning of the traffic overloadcondition
Value range: [0 to infinite]
Object: bts
Default value: 0
Type: DP, Design
Rec. value: 1 for cells with 1-2 TRXs
2 or 3 for cells with more than 3 TRXs
Used in: Dynamic barring of access class (All_4)
Changes of dynamic barring of access class (All_4) Handover for traffic reasons
Eng. Rules: Note that the congestion feature does not distinguish betweenreserved or unreserved TCHs. A reserved TCH is a TCH booked for apriority 0 procedure. Setting this parameter must consider the numberof reserved TCHs.
numberOfTCHFreeToEndCongestion Class 3 V9
Description: Threshold that gives the number of free TCHs, which triggers the endof TCH congestion phase and the end of the traffic overload condition.
Value range: [0 to infinite]
Object: bts
Default value: 0
Type: DP, Design
Rec. value: 2 for cells with 1-2 TRXs
3 or 4 cells with more than 3 TRXs
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Used in: Dynamic barring of access class (All_4)
Changes of dynamic barring of access class (All_4) Handover for traffic reasons
Eng. Rules: numberOfTCHFreeToEndCongestion >numberOfTCHFreeBeforeCongestion
Note, this inequality is not checked at the OMC.
numberOfTCHQueuedBeforeCongestion Class 3 V9
Description: Maximum number of TCH allocation requests queued which triggersthe beginning of the TCH congestion phase and the beginning of thetraffic overload condition
Value range: [0 to infinite]
Object: bts
Default value: 0
Type: DP, Design
Rec. value: 2 for cells with 1-2 TRXs
3 or 4 cells with more than 3 TRXs
Used in: Dynamic barring of access class (All_4)
Changes of dynamic barring of access class (All_4) Handover for traffic reasons
Eng. Rules:
numberOfTCHQueuedToEndCongestion Class 3 V9
Description: Maximum number of TCH allocation requests queued which triggersthe end of TCH congestion phase and the end of the traffic overloadcondition
Value range: [0 to infinite]
Object: bts
Default value: 0
Type: DP, Design
Rec. value: 1 for cells with 1-2 TRXs
2 or 3 for cells with more than 3 TRXs
Used in: Dynamic barring of access class (All_4)
Changes of dynamic barring of access class (All_4) Handover for traffic reasons
Eng. Rules:
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otherServicesPriority Class 3 V7
Description: Index in the table allocPriorityTable for a TCH allocation request (in
signaling mode) whose cause is “other services”This priority is used in primo–allocations or when an SDDCH cannot be allocated for
overload reasons.
Value range: [0 to 17]
Object: bts
Default value: 17
Type: DP, System
Rec. value: 16
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3)
Eng. Rules: The internal priority associated is > 0. A TCH allocation request (insignaling mode) whose cause is “other services” is acknowledgedwhen at least allocPriorityThreshold + 1 channels are free.
Refer also to the allocPriorityTable parameter.
priority Class 2 V7
Description: Priority level of a TDMA frame for mapping TDMA onto TRXs.
At least minNbOfTDMA TDMA frames related to a cell must besuccessfully configured for the cell to be working.They include the TDMA frame carrying the cell BCCH and those with
the other priority(ies).
Value range: [0 to 255]
Object: transceiver
Default value:
Type: DP, Optimization
Rec. value: See Engineering Rules
Used in:
Eng. Rules: Refer to section SDCCH Dimensioning and TDMA priorities.
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5.18. EMLPP RADIO RESOURCE PREEMPTION PARAMETER
Note that other parameters related to eMLPP Radio Resource Preemption
(emergencyThreshold and eMLPPThreshold) are only meaningful in GSM-R, therefore theyare not described in this document.
preemptionAuthor Class 3 V15
Description: This parameter activates or deactivates radio resource preemptioncapability in the BSS (used in the context of eMLPP supplementaryservice).
This parameter is available for both GSM-R and public GSM.
Value range: [forbidden, authorizedWithRelease, authorizedForcedHO]Object: signallingPoint
Default value: forbidden
Type: DP
Rec. value: see Eng Rules
Used in: eMLPP Preemption
Eng. Rules: preemptionAuthor = “forbidden” means that the BSC never performsradio resource preemption, whatever the priority and PCI/PVI flags’values.
preemptionAuthor = “authorizedWithRelease” means that the BSC isallowed to perform radio resource preemption if necessary and ifauthorised by the MSC.A successful preemption results in thepreempted call being released.
preemptionAuthor = “authorizedWithForcedHO” means the same thingas preemptionAuthor = “authorizedWithRelease” in the currentimplementation, despite the different name
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5.19. DIRECTED RETRY HANDOVER PARAMETERS
adjacent cell umbrella ref Class 3 V9
Description: Identifier of the adjacentCelHandOver object that describes theneighbor cell towards which a directed retry will be triggered in BSCmode
Value range: [0 to 31]
Object: bts
Default value:
Type: DP, Design
Rec. value: Identifier of the adjacentCellHandOver of the macrocell whichtotally covers the micro cell.
Used in: Directed Retry Handover: BSC (or local) mode
Eng. Rules: BSC mode is especially used in a two layer network. For micro cells,directed retry needs to be triggered towards the macro cell. However,if the recovering of each micro cell is good enough,adjacentUmbrellaRef can identify a micro cell.
To facilitate the procedure, the BCCH frequency of the target neighborcell must be in the reselection list.See also chapter Directed Retry Handover Benefit.
directedRetry Class 3 V9
Description: Minimum signal strength level received by the mobiles to be grantedaccess to the neighbor cell, used in processing directed retry
handovers in BTS mode
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: adjacentCellHandOver
Default value: more than -48 dBm
Type: DP, Optimization
Rec. value: = rxLevMinCell + 3 to 25 dB
Used in: Directed Retry Handover: BTS (or distant) mode
Eng. Rules: The choice of recommended value has to be done regarding thegeneral design of the network. A 3 dB margin must be considered asa minimum on a network to eliminate field strength bumps effect due
to multipath. However, this margin must be increased in an urbanenvironment or with the use of reuse pattern (overall for a 1X1pattern) because of the generated interference when the MS is not onthe best server cell.
See also chapter Directed Retry Handover Benefit.
CAUTION! Directed retry is not allowed between 2 zones of a concentric cell.
For a dual Band Network where one frequency band is privileged, it ispossible to set this parameter to a higher value in neighbour cellsbelonging to the low priority frequency band. Thus, this band will beunderprivileged. However, it will impact the directed retry formonoband MS on this band (less directed retry).
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intraBscDirectedRetry Class 3 V9
Description: Whether intra–bss directed retry handovers are allowed in a BSS
Value range: [allowed / not allowed]
Object: bscDefault value: allowed
Type: DP, Design
Rec. value: allowed
Used in: Directed Retry Handover: BSC (or local) mode
Directed Retry Handover: BTS (or distant) mode
Eng. Rules: See also chapter Directed Retry Handover Benefit.
CAUTION! Directed retry is not allowed between 2 zones of a concentric cell.
intraBscDirectedRetryFromCell Class 3 V9
Description: Whether intra–bss directed retry handovers are allowed in a cell
Value range: [allowed / not allowed]
Object: bts
Default value: allowed
Type: DP, Optimization
Rec. value: allowed
Used in: Directed Retry Handover: BSC (or local) mode
Directed Retry Handover: BTS (or distant) mode
Eng. Rules: If the value is “not allowed” then, the value ofintraBscDirectedRetryFromCell must be set to “not allowed” for theconcerned cells.
See also chapter Directed Retry Handover Benefit.
CAUTION! Directed retry is not allowed between 2 zones of a concentric cell.
modeModifyMandatory Class 3 V9
Description: Whether a CHANNEL MODE MODIFY message should be sent to themobile after a directed retry handover in the BSS
Value range: [used (yes) / not used (no)]
Object: bsc
Default value: not used
Type: DP, Optimization
Rec. value: not used
Used in: Directed Retry Handover
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Eng. Rules: In the early days of GSM, this parameter was useful for mobilesbelonging to specific brands, that used not to be able to switch directlyfrom signaling (SDCCH) to speech (TCH) when executing a Directedretry procedure. For that reason, this parameter used to be set to"used" so that a Channel Mode Modify procedure could be done,
forcing an explicit change of channel upon the mobile. However,today, as these mobile bugs have now presumably been corrected,with few or no faulty mobiles remaining in the field today, thesystematic invokation of the CMM procedure is no longer required.Setting to "used" may, in addition, have detrimental side-effects forsome kinds of inter-cell handovers (problem noted on instances ofintercell 3G-2G Handovers) which will systematically invoke aChannel Mode Modify. Therefore it is recommended to set thisparameter systematically to value “not used”.
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5.20. CONCENTRIC CELL PARAMETERS
biZonePowerOffset Class 3 V12
Description: Offset added in calculation formula to draw up the list of eligible cellsfor handover towards a dualband, dualcoupling, or concentric cellinner zone to take into account the difference of propagation modelsbetween the two bands of the cells and the difference of transmissionpower between TRXs of the two zones due to either BTSconfiguration or coupling.
Value range: [-63 to 63] dB
Object: adjacentCellHandOver
Default value: if main band = 850 MHz biZonePowerOffset = 3 dB
if main band = 1900 MHz biZonePowerOffset = -3 dB
Type: DP, Optimization
Rec. value: See Engineering Rules
Used in: General formulas
Direct TCH allocation Concentric/DualCoupling/DualBand Cell Handover
Eng. Rules: Used for intercell handover to control whether the inner zone is“eligible” or not.
to inhibit Direct TCH Allocation on an adjacent cell (when the
adjacent cell is declared as monozone / concentric / dualband /
dualcoupling) biZonePowerOffset(n) = 63
to allow Direct TCH Allocation on an adjacent cell (when the
adjacent cell is declared as concentric / dualband / dualcoupling)biZonePowerOffset(n) =concentAlgoExtRxLev(n) - rxLevMinCell(n)
Note: Shall be 63 for a monozone adjacent cell.
The higher (in positive) is the value, the more difficult it will be tohandover in the inner zone of the adjacent cell.It is advised to set a value higher than the max offset (in rxLevDLband 0) corresponding to the biggest difference of coverages betweenthe 2 bands (for the adjacent cell) otherwise an intercell handover tothe inner zone would be wrongly decided.
CAUTION! If HO decision is made toward the inner zone of a multizone cell, thenrelated EXP1XX(n) is computed with biZonePowerOffset(n).
See also chapters Concentric Cells and DualBand Networks.
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biZonePowerOffset Class 3 V12
Description: Power offset between inner and outer TRXs of the handOverControl
object of a dualband, dualcoupling, or concentric cell.Value range: [-63 to 63] dB
Object: handOverControl
Default value: if main band = 850 MHz, biZonePowerOffset = 3 dB
if main band = 1900 MHz, biZonePowerOffset = -3 dB
Type: DP, Optimization
Rec. value: See Engineering Rules
Used in: General formulas
Direct TCH allocation Concentric/DualCoupling/DualBand Cell Handover
Eng. Rules: monozone cell:
biZonePowerOffset = 63
concentric cell:
biZonePowerOffset = zone Tx powermax reduction
concentric cell with HePA only on outer zone:
biZonePowerOffset = 3
dualband cell (main band = 850 or 900 MHz):
biZonePowerOffset = 6
dualband cell (main band = 1800 or 1900 MHz):
biZonePowerOffset = - 6 dualcoupling cell:
biZonePowerOffset = zone Tx powermax reduction = coupling lossesdifference between inner and outer zone
dualband + dualcoupling cell combination:
biZonePowerOffset = coupling losses + propagation losses
CAUTION! When using dualcoupling cell DLU attenuation should be NULL andcompensated by the zone Tx power max reduction, see concentriccell parameter
Note: Shall be 63 for a monozone adjacent cell.
CAUTION! If HO decision is made in the small zone of a multizone cell then
related EXP2xx(n) = hoMarginxx(n) + biZonePowerOffset.See also chapters Concentric Cells and DualBand Networks.
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concentAlgoExtMsRange Class 3 V9
Description: MS to BTS distance below which a handover is requested from the
large zone to the small zone if the level criteria is verifiedValue range: [1 to 34] km (non-extended mode)
[1 to 120] km (extended mode)
Object: handOverControl
Default value: 1
Type: DP, Design
Rec. value: 34
Used in: Direct TCH Allocation
Concentric cell / dualcoupling cell intracell handovers
Eng. Rules: The calculated distance between the MS and the BTS is based on
timing advance (TA), which has an accuracy of ± 3 bits (correspondingto more than 1,5 km), thus not very useful in urban areas where thecell size is relatively small and multipath affect the MS_BS distance.
However this parameter can be useful in rural areas or suburbanareas, and concentAlgoExtMsRange should respect following rules:
concentAlgoExtMsRange = concentAlgoIntMsRange - 1 km
concentAlgoExtMsRange < concentAlgointMsRange
concentAlgoExtMsRange < msRangeMax
Note: 34 disable the parameter since condition is always fullfilled.
See also chapters Concentric Cells and DualBand Networks.
concentAlgoIntMsRange Class 3 V9
Description: MS to BTS distance from which a handover from the small zone to thelarge zone will be requested
Value range: [1 to 34] km (non-extended mode)
[1 to 120] km (extended mode)
Object: handOverControl
Default value: 34
Type: DP, Design
Rec. value: 34
Used in: Concentric cell / dualcoupling cell intracell handovers Eng. Rules: The calculated distance between the MS and the BTS is based on
timing advance (TA), which has an accuracy of ± 3 bits (correspondingto more than 1,5 km), thus not very useful in urban areas where thecell size is relatively small and multipath affect the MS_BS distance.
However this parameter can be useful in rural areas or suburbanareas, and concentAlgoIntMsRange should respect following rules:
concentAlgoIntMsRange > concentAlgoExtMsRange
concentAlgoIntMsRange < msRangeMax
Note: 34 disable the parameter since condition is always fullfilled.
See also chapters Concentric Cells and DualBand Networks.
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concentAlgoExtRxLev Class 3 V9
Description: The Downlink level of the MS signal strength above which a handover
is requested from the large zone to the small zoneValue range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handOverControl
Default value: - 95 to - 94
Type: DP, Design
Rec. value: See Engineering Rules
Used in: Direct TCH Allocation
Concentric/DualCoupling/DualBand Cell Handover Concentric cell / dualcoupling cell intracell handovers
Eng. Rules: The recommended value depends on the network design. Depending
on capacity distribution between inner and outer zone, CPT can beused to match the RxLev DL number of samples toconcentAlgoExtRxLev, which defines when users interzone handoverfrom outer to inner zone, i.e. inner zone traffic load.
The following rules shall be respected:
concentAlgoExtRxLev > concentAlgoIntRxLev
concentAlgoExtRxLev≤ rxLevMinCell + biZonePowerOffset
See also chapters Concentric Cells and DualBand Networks.
concentAlgoExtRxLevUL Class 3 V18
Description: The uplink level of the MS signal strength above which a handover isrequested from the large zone to the small zone
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handOverControl
Default value: - 95 to - 94
Type: DP, Design
Rec. value: See Engineering Rules
Used in: Direct TCH Allocation
Concentric/DualCoupling/DualBand Cell Handover Concentric cell / dualcoupling cell intracell handovers
Eng. Rules: The recommended value depends on the network design. Dependingon capacity distribution between inner and outer zone, CPT can be
used to match the RxLev DL number of samples toconcentAlgoExtRxLev, which defines when users interzone handoverfrom outer to inner zone, i.e. inner zone traffic load.
The following rules shall be respected:
concentAlgoExtRxLevUL > concentAlgoIntRxLevUL
See also chapters Concentric Cells and DualBand Networks.
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concentAlgoIntRxLev Class 3 V9
Description: Downlink Level of the MS signal strength below which a handover is
requested from the small zone to the large zoneValue range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handOverControl
Default value: less than -110
Type: DP, Design
Rec. value: See Engineering Rules
Used in: Concentric/DualCoupling/DualBand Cell Handover
Concentric cell / dualcoupling cell intracell handovers
Eng. Rules: In order to avoid unnecessary ping-pong interzone HO a HysteresisMargin should be added:
concentAlgoIntRxLev = concentAlgoExtRxLev - biZonePowerOffset- Hysteresis Marginwhere recommended Hysteresis Margin = 4 dBSee also chapters Concentric Cells and DualBand Networks.
concentAlgoIntRxLevUL Class 3 V18
Description: Uplink Level of the MS signal strength below which a handover isrequested from the small zone to the large zone
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handOverControl
Default value: less than -110Type: DP, Design
Rec. value: See Engineering Rules
Used in: Concentric/DualCoupling/DualBand Cell Handover
Concentric cell / dualcoupling cell intracell handovers
Eng. Rules: In order to avoid unnecessary ping-pong interzone HO a HysteresisMargin should be added:
concentAlgoIntRxLevUL=concentAlgoExtRxLevUL-biZonePowerOffset- Hysteresis Marginwhere recommended Hysteresis Margin = 4 dB
In addition concentAlgoIntRxLevUL has to be set regardingconcentAlgoIntRxLev and the path balance of the cellExample concentAlgoIntRxLev = -85 path balance =4, thereforeconcentAlgoIntRxLevUL = -89
See also chapters Concentric Cells and DualBand Networks.
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directAllocIntFrRxLevUL Class 3 V18
Description: uplink RxLev threshold above which a TCH-FR could be allocated inthe small zone of a multi-zone cell (in conjunction withdirectAllocIntFrRxLevDL).
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handOverControl
Default value: -84 to -83
Type: DP, Design
Rec. value: See Engineering Rules
Used in: Concentric/DualCoupling/DualBand Cell Handover
Concentric cell / dualcoupling cell intracell handovers
Eng. Rules:
directAllocIntFrRxLevDL Class 3 V18
Description: downlink RxLev threshold above which a TCH-FR could be allocatedin the small zone of a multi-zone cell (in conjunction withdirectAllocIntFrRxLevUL).
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handOverControl
Default value: -79 to -78
Type: DP, Design
Rec. value: See Engineering Rules
Used in: Concentric/DualCoupling/DualBand Cell Handover
Concentric cell / dualcoupling cell intracell handovers
Eng. Rules:
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concentric cell Class 2 V9
Description: Whether the cell is monozone, concentric, dualband or dualcoupling
A concentric, dualband, or dualcoupling cell describes a combinationof two transmission zones, the outer (or large) zone and the inner (orsmall) zone. The inner zone is entirely included in the outer zone. A dualband cell is a particular type of concentric cell for which GSM900 and GSM1800 (or GSM 850 and GSM1900) TRXs/DRXs coexistand share the same BCCH. A dualcoupling cell is a particular type of concentric cell for which theTRXs/DRXs are combined with two types of combiners.For concentric configurations (concentric, dualband or dualcoupling),a TDMA frame belongs to one zone or the other, but never to both.
Value range: [monozone / concentric / dualband / dualcoupling]
monozone: normal cell
concentric: two concentric transmission zones dualband: two concentric transmissions zones with GSM 900
TRXs/DRXs for the one and GSM 1800 TRXs/DRXs for the other
dualcoupling: two concentric transmission zones with TRXs/DRXs
combined with one type of combiner for the one and with another
type of combiner for the other
Object: bts
Default value: monozone
Type: DP, Optimization
Rec. value: See Engineering Rules
Used in: Concentric/DualCoupling/DualBand Cell Handover Eng. Rules:
concentric cell:
It is possible to allocate directly a TCH in the innerzone for call set-upor HO and to reuse the same frequency in both zones, and hoppingconcerns the total available number of frequencies. A cell configuration with HePA only on outer zone is concentric cell,not a dualcoupling cell.
dualband cell:
The dualband combining into one cell allows to save up to oneSDCCH in particular configurations, the combining of GSM 900 / GSM1800 (or GSM 850 / GSM 1900) resources into one pool allows to
increase the traffic capacity.
CAUTION! dualband is not supported on S4000 with DCU2/DCU4, S4000 withDCU2, S4000 with DCU4
dualcoupling cell:
The DLU attenuation shall be used: so configure the “attenuation”parameter (btsSiteManager object) to null, configure the max powerfor the cell to the desired max power (power for the outer zone) andconfigure zone Tx power max reduction for the inner zone to the deltavalue.
CAUTION! dualcoupling is not supported on mixed DCU4 or DRX transceiverarchitecture.
See also chapters Concentric Cells and DualBand Networks.
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small to large zone HO priority Class 3 V12
Description: External priority of inter-zone handovers from the inner zone to the
outer zone in a concentric cell. This attribute is defined if theassociated bts object describes a concentric cell.
Value range: [0 to 17]
Object: handOverControl
Default value: 17
Type: DP
Rec. value: 14
Used in: Allocation and priority (run by the BSC) (All_1)
Queuing driven by the MSC (All_2) Queuing driven by the BSC (All_3) Concentric cell / dualcoupling cell intracell handovers
Eng. Rules: Refer also to the allocPriorityTable parameter.
transceiver equipment class Class 2 V9
Description: Class of a TRX/DRX.
The class of a TRX/DRX sets, among others, its maximumtransmission power. The attribute possible values have the followingmeaning:
Class 1 corresponds to GSM 850/900 class 5 or GSM 1800/1900
class 1 (20W to 40W transmitters)
Class 2 corresponds to GSM 900 class 6 which is not supported orGSM 1800/1900 class 2 (10W to 20W transmitters)
Value range: [0 (reserved) / 1 / 2]
Object: transceiverEquipment
Type: DP
Rec. value: monozone: 1
concentric cell: outer=1, inner=1
dualband cell: outer=1, inner=2
dualbcoupling cell: outer=1, inner=2
Used in: Concentric/DualCoupling/DualBand Cell Handover
Eng. Rules: When dual band is used, the class of a TRX/DRX enables todistinguish which DRX and which TDMA are used in the outer zone orinner zone.
Class 1 corresponds to to a TDMA in the frequency band carryingBCCH so belonging to transceiverZone = 0 (large/outer zone).Class 2 corresponds to a TDMA in the frequency band not carryingBCCH so belonging to transceiverZone = 1 (small/inner zone).If the TRX/DRX is partnered with a TDMA frame, its class matches theTRX/DRX class allotted to the zone to which the TDMA frame belongs(refer to the next parameter).
Note: In case of concentric cell configuration, setting inner and outer class to“1” allows a reconfiguration of TRX/DRX from the inner to the outer if
needed.
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transceiver equipment class V9
Description: Class of the TRX/DRXs partnered with the TDMA frames of the zone.
The class of a TRX/DRX sets, among others, its maximumtransmission power. Refer to the previous parameter.
Value range: [1 / 2]
Object: transceiverZone
Type: DP
Rec. value: monozone: 1
concentric cell: outer=1, inner=1
dualband cell: outer=1, inner=2
dualbcoupling cell: outer=1, inner=2
Used in: Concentric/DualCoupling/DualBand Cell Handover
Eng. Rules: When dual band is used, the class of a TRX/DRX enables todistinguish which DRX and which TDMA are used in the outer zone orinner zone.
Class 1 corresponds to to a TDMA in the frequency band carryingBCCH so belonging to transceiverZone = 0 (large/outer zone).Class 2 corresponds to a TDMA in the frequency band not carryingBCCH so belonging to transceiverZone = 1 (small/inner zone).
Note: In case of concentric cell configuration, setting inner and outer class to“1” allows a reconfiguration of TRX/DRX from the inner to the outer ifneeded.
transceiverZone Class 2 V12
Description: Identifier of the transceiverZone object that defines the zone to whicha TDMA frame belongs in a concentric cell.
The transceiverZone objects are only significant for the bts objectsthat describe concentric cells. Two transceiverZone objects arecreated for each created concentric bts object; one describes thelarge or outer transmission zone, and the other describes the smallorinner transmission zone.
Value range: [0 (large outer zone) / 1 (small or inner zone)]
Object: transceiverZone
Type: DP
Rec. value: 0 for outer zone
1 for inner zone
Used in: Concentric/DualCoupling/DualBand Cell Handover
Eng. Rules: When a concentric/dualband/dualcoupling cell is created thetransceiverZone outer zone must set to “0” and the transceiverZoneinner zone must be set to “1”.
It is not applicable for monozone cells.
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zone Tx power max reduction Class 2 V9
Description: Attenuation vs bsTxPwrMax that defines the maximum TRX/DRX
transmission power in the zoneValue range: large zone = [0] dB, small zone = [1 to 55] dB
Object: transceiverZone
Default value: 0 dB
Type: DP, Design
Rec. value: see Engineering Rules
Used in: Concentric cell / dualcoupling cell intracell handovers
Eng. Rules:
concentric cell:
zone Tx Power Max Reduction(outer) = 0
zone Tx Power Max Reduction(inner) ≤ zone Tx Power MaxReduction(outer)(zone Tx Power Max Reduction(inner) = 0 is recommanded)
dualband cell (homogeneous coupling):
zone Tx Power Max Reduction(outer) = 0zone Tx Power Max Reduction(inner) = 1
dualcoupling cell:
zone Tx Power Max Reduction(outer)=0zone Tx Power Max Reduction(inner)=3 simulates the D/H2Dconfigurationzone Tx Power Max Reduction(inner)=4 simulates the H2D/H4Dconfiguration
CAUTION! when using dualcoupling cell DLU attenuation should be NULL andcompensated by the zone Tx power max reduction, see concentriccell parameter
See also chapters Concentric Cells and DualBand Networks.
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5.21. INTERFERENCE LEVEL PARAMETERS
averagingPeriod Class 2 V7
Description: Number of SACCH multiframes over which the interference levels areaveraged. This averaging will be performed immediately before thetransmission of the RESOURCE INDICATION message.
This attribute, together with the “thresholdInterference” attribute,allows users to manage interferences in radio cells. Refer to this entryin the Dictionary.
Value range: [0 to 255] SACCH frame (1 unit = 480 ms on TCH, 470 ms onSDCCH)
Object: handOverControl
Default value: 20
Type: DP, System
Rec. value: 20
Used in: Radio channel allocation
Interference Management (BTS and BSC) (If)
Eng. Rules: Performing this message broadcast has a great impact on the systemload and should not be done too often.
Reducing this value speeds-up the channel allocation algorithm, sinceit checks temporary channel interference non frequently. However, themain purpose of this algorithm is to take into account long terminterference and not short term interference which do not have astatistically large impact on call quality.
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radChanSelIntThreshold Class 3 V8
Description: Maximum interference level on free radio channels, below which the
channels are ranged in the group of allocation priority channelsThe information is used to first allocate the free channels with thelowest interference level. The levels depend on thethresholdInterference attribute value defined for the cell. Refer to thisentry in the Dictionary.The BSC distributes the free radio channels among two groups:
The first group contains the list of channels with a measured
averaged interference level equal to or lower than the defined
level.
The second group contains the list of channels with a measured
averaged interference level higher than the defined level, and
recently released channels for which no measurement is available.
Four resource pools are defined for each SDCCH or TCH type ofchannel:
low interference level radio channels that are authorized to hop
low interference level radio channels that are not authorized to hop
high interference level radio channels that are authorized to hop
high interference level radio channels that are not authorized to
hop
Value range: [0 to 4]
Object: handOverControl
Default value: 1
Type: DP, Optimization
Rec. value: 3
1 (for 1X1 & 1X3)
Used in: Interference Management (BTS and BSC) (If)
Eng. Rules: A high value for this parameter means a tolerant interference sorting.
It is easier to change the value of this pointer than to tune thethresholds themselves since the thresholds are used in the lower layerof signal processing at the BTS.The radChanSellIntThreshold counter can be set after interferencecounters monitoring. Ideally, it should depend on the average traffic
load expected on the cell and on the interference distribution.With low Traffic per TCH, radChanSellIntThreshold can be set to 1.This means that the selection of the non interefered channels is veryselective. The few TCH selected are sufficient for the traffic to becarried. RadChanSellIntThreshold can be decreased to 1 when using1X1 or 1X3 reuse pattern in order to use as more BCCH resources aspossible.
With high Traffic per TCH, radChanSellIntThreshold can be set to 4.This means MS will get allocated to a channel regardless of theinterference as long as there are resources available.
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thresholdInterference Class 2 V7
Description: List of four thresholds defined in ascending order, used to sort idlechannels on the basis of measured interference levels
This attribute, together with the averagingPeriod attribute, allowsmanaging interferences in a radio cell. The classification is used bythe radio resource allocator.For each idle radio channel, the BTS permanently measures thesignal strength level RXLEV.When averagingPeriod “Measurement results” messages have beenreceived, the L1M function in the BTS calculates interference levelaverages, sorts the idle channels according to the five definedinterference levels, and sends the information to the BSC.
Level 0 corresponds to: RXLEV < threshold 1
Level 1 corresponds to: threshold 1 < RXLEV < threshold 2
Level 2 corresponds to: threshold 2 < RXLEV < threshold 3
Level 3 corresponds to: threshold 3 < RXLEV < threshold 4
Level 4 corresponds to: threshold 4 < RXLEV
Value range: [-128 to 0] dBm
Object: handOverControl
Default value: -100 -90 -80 -70
Type: DP, Optimization
Rec. value: -114, -112, -108, -100
Used in: Radio channel allocation
Interference Management (BTS and BSC) (If)
Eng. Rules: Those values define 5 interference level ranges, so free channelclassification can be displayed at the OMC-R level. The setting of thethreshold Interference level should be linked to the interference leveldistribution in the cell. As a first definition, thresholds can be evenlydistributed over the defined range.
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5.23. BSS TIMERS
bssMapT1 Class 1 V7
Description: A interface timer triggered by the BSC in the BSSMAP managementprocedure.
It is started on transmission of BLOCK or UNBLOCK by the BSC andcancelled on receipt of BLOCK ACKNOWLEDGE or UNBLOCK ACKNOWLEDGE sent by the MSC.
Value range: [2 to 300] seconds
Object: bsc
Default value: 5
Type: DP, System
Rec. value: 5, 60 (if using DMS switch)
Used in:Eng. Rules:
bssMapT12 Class 1 V7
Description: A interface timer triggered by the BSC in the BSSMAP managementprocedure.
This timer is used with a Phase I MSC only. It is started ontransmission of RESET CIRCUIT by the BSC and cancelled on receiptof RESET CIRCUIT ACKNOWLEDGE sent by the MSC.
Value range: [2 to 300] seconds
Object: bsc
Default value: 5
Type: DP, System
Rec. value: 5, 60 (if using DMS switch)
Used in:
Eng. Rules:
bssMapT13 Class 1 V7
Description: An interface timer triggered by the BSC in the BSSMAP management
procedure.It is started on receipt of RESET sent by the MSC. On elapse, theBSC sends RESET ACKNOWLEDGE to the MSC.
Value range: [2 to 300] seconds
Object: bsc
Default value: 32
Type: DP, System
Rec. value: 32
Used in:
Eng. Rules:
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bssMapT19 Class 1 V8
Description: A interface timer triggered by the BSC in the BSSMAP management
procedure.This timer is used with a Phase II MSC only. It is started ontransmission of RESET CIRCUIT by the BSC and cancelled on receiptof RESET CIRCUIT ACKNOWLEDGE sent by the MSC.
Value range: [2 to 300] seconds
Object: bsc
Default value: 32
Type: DP, System
Rec. value: 32
Used in:
Eng. Rules:
bssMapT20 Class 1 V8
Description: A interface timer triggered by the BSC in the BSSMAP managementprocedure.
It is started on transmission of CIRCUIT GROUP BLOCK or CIRCUITGROUP UNBLOCK by the BSC and cancelled on receipt of CIRCUITGROUP BLOCK ACKNOWLEDGE or CIRCUIT GROUP UNBLOCK ACKNOWLEDGE sent by the MSC.
Value range: [2 to 300] seconds
Object: bsc
Default value: 32
Type: DP, System
Rec. value: 32
Used in:
Eng. Rules:
bssMapT4 Class 1 V7
Description: A interface timer triggered by the BSC in the BSSMAP managementprocedure.
It is started on transmission of RESET and cancelled on receipt ofRESET ACKNOWLEDGE sent by the MSC. On elapse, the BSCsends RESET.
Value range: [5 to 600] seconds
Object: bsc
Default value: 60
Type: DP, System
Rec. value: 60
Used in:
Eng. Rules:
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bssMapT7 Class 1 V7
Description: A interface timer triggered by the BSC in the BSSMAP management
procedure.It is started on transmission of HANDOVER REQUIRED andcancelled on receipt of HANDOVER COMMAND, RESET, RESETCIRCUIT, CLEAR COMMAND or HANDOVER REQUIRED REJECT.
Value range: [2 to 120] seconds
Object: bsc
Default value: 7
Type: DP, Optimization
Rec. value: 7
Used in:
Eng. Rules:
bssMapT8 Class 1 V7
Description: A interface timer triggered by the BSC in the BSSMAP managementprocedure.
It is greater than t3103 for each cell managed by the BSC. It is startedon transmission of HANDOVER COMMAND and cancelled on receiptof CLEAR COMMAND sent by the MSC or HANDOVER FAILUREsent by MS.
Value range: [0 to 255] seconds
Object: bsc
Default value: 15
Type: DP, Optimization
Rec. value: 15
Used in:
Eng. Rules: It is greater than t3103 for each cell managed by the BSC.
bssMapTchoke Class 1 V7
Description: A interface timer triggered by the BSC in the handover managementprocedure.
It is started by the BSC when the last neighbour cell in the list isrejected. On timer elapse, the BSC asks the BTS to provide a new listof eligible cells.
Value range: [1 to 255] seconds
Object: bsc
Default value: 4
Type: DP, System
Rec. value: 4
Used in:
Eng. Rules: It is strongly recommended to keep this value.
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bssSccpConnEst Class 1 V7
Description: A interface timer triggered by the BSC in the handover management
procedure.It is set on transmission of CONNECTION REQUEST and cancelledon receipt of CONNECTION CONFIRM or CONNECTION REFUSED.
Value rang: [5 to 360, by steps of 5] seconds
Object: signallingPoint
Default value: 5
Type: DP, System
Rec. value: 5
Used in:
Eng. Rules: A high value is dangerous in case of slowing down on A interface.
Then, the minimum value (5 s) must be chosen for this parameter; it isstrongly recommended not to modify this value.
t3101 Class 3 V7
Description: BSC timer triggered during the immediate assignment procedure. Usethe suggested system value.
It is set on transmission of CHANNEL ACTIVATION by the BSC andcancelled on receipt of ESTABLISH INDICATION sent by the BTS.
Value range: [1 to 255] seconds
Object: bts
Default value: 3Type: DP, System
Rec. value: 3
Used in:
Eng. Rules: Most of the time, the timer expires in the case of double allocation (i.e,when two RACHs are sent by the same mobile to the network). Thehigher the timer is the longer unnecessary signaling resources arereserved. Up to 30% of signaling resources are allocated for a secondRACH for phase 1 MS according to numberOfSlotsSpreadTrans (32).To optimize signaling resources (especially in case of Queuing), itcould be useful to decrease the timer value. The minimum timebetween the two messages is 600 ms and the maximum for a lightly
loaded BSS is almost 1.8 seconds when MS is answering.
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t3103 Class 3 V7
Description: BSC timer triggered during the handover procedure. Use the
suggested system value.It is set on transmission of HANDOVER COMMAND by the BSC andcancelled on receipt of either HANDOVER COMPLETE orHANDOVER FAILURE sent by the MS (intra–bss handover), orCLEAR COMMAND sent by the MSC (inter–bss handover). At expiryof T3103, the channel is released.
Value range: [2 to 255] seconds (t3103 < bssMapT8)
Object: bts
Default value: 5 seconds
Type: DP, Optimization
Rec. value: 9 seconds
Used in:
Eng. Rules: The longest procedure (inter BSS handover) is taken as an example.The timer is set on receipt of the HO command and reset on clearcomplete. It means that as long as the timer runs, 2 channels arekept: one on the originating BSC and one on the target BSC. If thetimer is too long, two resources are used which can be a bad in caseof capacity problems.
Tests showed that t3103 set to 9 seconds offers the best compromisebetween the execution of the procedure and the hold of ressources.
t3107 Class 3 V7
Description: BSC timer triggered during the assignment command procedure. Usethe suggested system value.
It is set on transmission of ASSIGN COMMAND by the BSC andcancelled on receipt of either ASSIGN COMPLETE or ASSIGNFAILURE sent by MS.
Value range: [2 to 255] seconds
Object: bts
Default value: 10 seconds
Type: DP, Optimization
Rec. value: 10 seconds in a network without any capacity problems.
If not, the value can be decreased. The minimum theoreticalvalue is 5 seconds.
Used in:
Eng. Rules: At expiry of the timer, the mobile is assumed to be lost and itsresource can be used by another mobile. Mobile on SDCCH is aconstraining case: the timer T200 leads to a 230 ms wait instead of180 ms on TCH, before repeating a message. If no message isrepeated, this procedure lasts about 1 second. However, if the radiolink is bad, it is necessary to repeat some messages. The maximumtime before resetting t3107 is approximately 5 seconds: after this time,the timer will expires: no new message will be received to reset t3107.
The default value of 10 seconds is then a good value to ensure that
the link is not cut too early.
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t3109 Class 3 V7
Description: BSC timer triggered during the SACCH deactivation procedure. Usethe suggested system value.
It is set on receipt of DEACTIVATE SACCH ACKNOWLEDGE sent by
the BTS and cancelled on receipt of RELEASE INDICATION sent bythe BTS. If the timer expires, a RF CHANNEL RELEASE message issent to the BTS and a RF CHANNEL RELEASE ACK is expected.Mobiles comply with system operating conditions when the counter(S) associated with SACCH messages is assigned a value below orequal to t3109.
Value range: [2 to 255] seconds (t3109 ≥ radioLinkTimeout)
Object: bts
Default value: 12 seconds
Type: DP, Optimization
Rec. value: 12 seconds (related to radioLinkTimeOut value)
Used in:
Eng. Rules: On receipt of the Deactivate SACCH message, the radio link controlalgorithm will lead to a decrease on the value of the‘radioLinkTimeOut’ timer and this on MS side or on BTS sideaccording to the situation. t3109 added to t3111 must be greater thanradioLinkTimeOut and greater than the time corresponding to rlf1:t3109 ≥ radioLinkTimeOut
If t3109 is too small, the ressources could be allocated even ifradiolinkTimeOut did not reach zero yet.
CAUTION! When AMR is activated that parameter should be set to 17.
t3111 Class 3 V7
Description: BSC timer triggered during the radio resource clearing procedure. Usethe suggested system value.
It is set on receipt of RELEASE INDICATION sent by the BTS. Onelapse, the BSC sends RF CHANNEL RELEASE.
Value range: [1 to 255] seconds
Object: bts
Default value: 2 seconds
Type: DP, System
Rec. value: 2 seconds
Used in:
Eng. Rules: This timer is used to delay the channel deactivation afterdisconnection of the main signalling link. Its purpose is to allow timefor the possible repetition of the disconnection by the BTS to the MS.
After Release Indication, resources are kept until t3111 expires. Incase of capacity problems, t3111 must be as little as possible. Thesmallest possible value is 2 seconds (range 2-255 seconds).Theminimum theoretic value is 5 times the repetition time which is lessthan 2 seconds No advantage has been found to have a higher valuethan the smallest possible one.This timer is also used in the formula to compute the preemtion timer :Tpreempt = Tdeactack + 4* T3111
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t3122 Class 3 V7
Description: Minimum time that mobiles must wait before issuing a channel
allocation request when an immediate assignment has failed. In asimilar way, in GPRS mode, this value is indicated in the Packet Access Reject (PAREJ) to inform the MS with the waiting time beforesending a new Channel Request. The timer is called T3172 in GPRSmode, with T3172 = T3122.
Value range: [0 to 255] seconds
Object: bts
Default value: 10 seconds
Type: DP, Optimization
Rec. value: 10 seconds
Used in:
Eng. Rules: This value is broadcast to the mobile stations. When an immediateassignment reject command is received (when no SDCCH and noTCH in signalling mode is available or when the A-interface is down),mobile stations wait t3122 seconds before sending the request again.In case of BSC Overload, t3122 is automatically increased ordecreased between its value set by O&M and 30s according to aspecific algorithm.
This parameter can be used to solve a problem of a load pick. Byincreasing the value, the access to the network is regulated.
timerPeriodicUpdateMS Class 3 V7
Description: Time between two location update requests
Value range: [0 to 255] 1/10th of hour. “0” means that no periodic location update isrequested.
Object: bts
Default value: 60
Type: DP, Optimization
Rec. value: 10 (not loaded network)
20 (loaded network)
Used in:
Eng. Rules: Location updatings are performed when initiating a call or when
entering a new location area in idle mode. When those events do notoccur, timerPeriodicUpdateMS is used to ensure a maximum timebetween two location update requests. The value of this timer shouldbe set regarding the value of the same timer used in the switch(‘attach mobile audit’ for a DMS)
If the value chosen is low, the load of the BSC is severely increased.On the contrary, a too high value would lead to a smaller reactivity ofthe mobile (e.g. if a mobile is in a hole of coverage and a shortmessage is sent to it, it will be aware of it only at the next locationupdate which could be several hours later). A good trade-off is 2hours.
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5.24. PAGING PARAMETERS
delayBetweenRetrans Class 2 V8
Description: Number of occurences of a paging sub–group that separates twotransmissions of the same paging message.
Value range: [0 to 22]
Object: bts
Default value: 0
Type: DP, Optimization
Rec. value: 0
Used in: Paging command repetition process (run by BTS) (Pag_rep)
Eng. Rules: The recommended value is 0 because the time between two pagingcommands broadcast must not be too long, otherwise there is a risk of
double allocation. This phenomenon occurs when the suscriberanswers and hangs up very quickly. In that case, the mobile is readyto receive a new paging message, for example the previous one if it isresent. The value of this parameter is linked to the values of thenbOfRepeat and retransDuration parameters. Furthermore, thefollowing inequality, that is not checked by the system, must be true:
retransDuration ≥ (delayBetweenRetrans + 1) x nbOfRepeat See also chapter GSM Paging Repetition Process Tuning.
maxNumberRetransmission Class 3 V8
Description: Maximum number of RACH burst retransmissions allowed in a call in
case of non-system response. The information is broadcast to themobiles at regular intervals on the cell BCCH. It defines the maximumnumber of times a mobile can renew access requests to the BTS onRACH.
Value range: [one / two / four / seven]
Object: bts
Default value: two
Type: DP, Optimization
Rec. value: two in non-interfered areas
four in interfered areas
Used in: Request access command repetition process (RA_rep) Eng. Rules: In interfered areas, it is necessary to repeat RACHs because of bad
conditions. Even if it increases a little overall noise, the gain indecreasing the number of RACHs not received should be significant(under study). In non-interfered areas, the value of ‘two’ is sufficient.‘one’ is not advised because mobile stations can be in holes ofcoverage due to multipath fading and, in these cases, at least oneretransmission is necessary.
See also chapter GSM Paging Repetition Process Tuning.
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nbOfRepeat Class 2 V8
Description: Maximum number of times that paging messages are repeated to
mobiles that belong to the same paging sub-groupIt is set to “3” in former BSS versions (static configuration parameter).The following inequality, that is not checked by the system, must betrue (refer to these entries in the Dictionary):retransDuration ≥ (delayBetweenRetrans + 1) x nbOfRepeat
Value range: [0 to 22]
Object: bts
Default value: 3
Type: DP, Optimization
Rec. value: See Engineering Rules
Used in: Paging command repetition process (run by BTS) (Pag_rep)
Eng. Rules: The value of 3 ensures a good quality of service. With less repetition,paging messages can be lost, and, as the repetitions are performedsystematically, a signicantly higher value would increase the load ofthe system and the risk to page a mobile twice. The value of thisparameter is linked to the values of the delayBetweenRetrans andretransDuration parameters.
That parameter can be tuned regarding the paging parameters andthe TDMA configuration, but very cautiously with some metricmonitoring (see chapter GSM Paging Repetition Process Tuning)
noOfBlocksForAccessGrant Class 2 V7
Description: Number of CCCH blocks not used for paging
A BCCH is combined when it shares the same radio time slot with fourSDCCHs, which can include a CBCH (refer to the channelType entryin the Dictionary). In that case, the attribute value is no greater than to2 (the value must be checked by users).
Value range: [0 to 2] if the cell uses a combined BCCH,
[1 to 7] otherwise.“0” means that PCH blocks are used for sending immediateassignment messages as and when needed.
Object: bts
Default value: 0
Type: DP, System
Rec. value: 0 if no SMS-CB or SMS-CB with combined BCCH
1 if SMS-CB with non-combined BCCH
> 0 if SI2Quater or/and SI13 on ext BCCH are activated
Used in: Paging command Process (Pag)
Effects of SMS-Cell Broadcast Use on “noOfBlocksForAccessGrant” SI2Quater & SI13 on Extended or Normal BCCH
Eng. Rules: See also chapter GSM Paging Repetition Process Tuning.
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noOfMultiframesBetweenPaging Class 2 V7
Description: Number of occurrences of a paging sub–group
The greater this number, the greater the number of paging sub–groups.
Value range: [2 to 9] multi–frame of fifty-one frames
Object: bts
Default value: 6
Type: DP, Optimization
Rec. value: 6 for rural environments
2 or 4 for urban environments
Used in: Paging command Process (Pag)
Eng. Rules: This parameter has an impact on the use of mobile batteries
(determine when an MS needs to listen to paging channels) and onreselection selectivity. For this operation, frequency of measurementsperformed on idle neighbours thanks to the formula: mesurementsdone every Max (5 seconds, ((5*nb of idle neighbors + 6) DIV 7) *noOfMultiframesBetweenPaging /4).
Regarding mobile batteries, a value of 6 is sufficient to have a trade-off between the saving of energy and effective paging. In ruralenvironments, the maximum size of reselection list is usually 4/5. 5seconds is then the maximum in the formula, so it does not slow downthe reselection mechanism. The value of 6 is then advised.In urban environments, the size of the list is a bit higher. Furthermore,in this kind of environment, reselection reactivity is a key issue. Theway to avoid having more than 5 seconds in the formula is to
decrease noOfMultiframesBetweenPaging to 2 or 4 even if itincreases battery consumption. Some studies are in progress todetermine the value with more accuracy.
See also chapter Effects of “noOfMultiFramesBetweenPaging” onMobile Batteries and Reselection Reactivity.
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numberOfSlotsSpreadTrans Class 3 V7
Description: Number of radio time slots over which RACH transmission access are
spread in a random way to avoid collisionsThe information is broadcast to the mobiles at regular intervals on thecell BCCH. In the event of non-system response, the mobile willrenew the RACH bursts after a randomly defined period that varieswith numberOfSlotsSpreadTrans.MS Phase 1The time T between two transmissions of the same RACH burst is thefollowing:T= [D + (N+1) x 4.615]ms
D is the maximum system response pending time:
D= 250 ms for BCCH not combined (i.e. 55 time slots)D= 350 ms for BCCH combined (i.e. 77 time slots)
N is the randomly number generated by the mobile in the range [0to numberOfSlotsSpreadTrans-1]
4.615 ms is the time occupied by a time slot.
MS Phase 2The time T between two transmissions of the same RACH burst is thefollowing (whatever the BCCH is combined or not):T= 4.615 x [S+(N + 1)] ms where
S is a parameter depending on the BCCH configuration and on the
value of numberOfSlotsSpreadTrans (see table hereafter)
N is the randomly number generated by the mobile in the range [0
to numberOfSlotsSpreadTrans-1]
4.615 ms is the time occupied by a time slot.
numberOfSlotsSpreadTransS on non-combined
BCCHS on combined
BCCH
3, 8, 14, 50 55 41
4, 9, 16 76 52
5, 10, 20 109 58
6, 11, 25 163 86
7, 12, 32 217 115
Value range: [3 to 12, 14, 16, 20, 25, 32, 50] time slots
Object: bts
Default value: 32
Type: DP, Optimization
Rec. value: 32
Used in: Request access command repetition process (RA_rep)
Eng. Rules: From Rec 04.08, numberOfSlotsSpreadTrans has a different meaningfor phase 1 and phase 2 mobiles. For phase 1 mobiles, if the value istoo small, two resources may be allocated to the same mobile (doubleallocation). For phase 2 mobiles, it is different. The best trade-off is totake “32” which is very good for phase 2 mobiles and not too bad forphase 1 mobiles.
The choice will depend on the quantities of GSM phase 1 and GSMphase 2 mobiles.
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For Mobile phase 1, numberOfSlotsSpreadTrans = 50 leads to thelower double allocation rate.For Mobile phase 2, numberOfSlotsSpreadTrans = 6, 7, 11, 12, 25, 32(respectively 5, 10, 20) for BCCH combined (respectively BCCH notcombined) leads to the lower double allocation rate.
Therefore, for a network that handles a combination of both types ofmobiles, numberOfSlotsSpreadTrans should be set to 32 (defaultvalue).
See also chapter GSM Paging Repetition Process Tuning.
pagingOnCell Class 3 V9
Description: Enable or disable paging requests in a cell
Value range: [enabled / disabled]
Object: bts
Default value: enabled
Type: DP, Optimization
Rec. value: enabled but can be disabled on special occasions (seeEngineering Rules)
Used in: PCH and RACH channel control
Eng. Rules: When pagingOnCell is set to disabled, the BSC does not send anyPAGING_COMMAND to the cell. This feature is used when operatorswant to forbid mobile terminated call set-up in specific cells. It can beuseful during special events or in places like cinemas, theaters...
retransDuration Class 2 V8
Description: Maximum number of occurrences of a same paging sub-group thatseparates the first and the last transmissions of the same pagingmessage.
Value range: [0 to 22]
Object: bts
Default value: 10
Type: DP, Optimization
Rec. value: 10
Used in: Paging command repetition process (run by BTS) (Pag_rep)
Eng. Rules: If many paging commands must be broadcast, repetitions of oldpaging messages are delayed because fresh paging has a higherpriority. Therefore, repetitions could be so delayed that it leads todouble paging. By setting this parameter to an accurate valueretransDuration , the risk of sending very old paging messages islimited. Anyway, the value of this parameter is linked to the ones ofnbOfRepeat and retransDuration. Furthermore, the followinginequality, that is not checked by the system, must be true:
retransDuration ≥ (delayBetweenRetrans + 1) x nbOfRepeat
See also chapter GSM Paging Repetition Process Tuning.
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5.25. FREQUENCY HOPPING PARAMETERS
bscHopReconfUse Class 1 V8
Description: Whether frequency hopping reconfiguration is authorized in BTSs thatuse cavity coupling
When frequency reconfiguration is authorized, it allows toautomatically reconfigure the hopping sequence whenever afrequency is lost or recovered in the BTS.This parameter is only useful if there is at least one BTS with cavitycoupling in the BSS. Otherwise its effect is neutral regardless of thevalue.
Value range: [true / false]
Object: bsc
Default value: true
Type: DP, Design
Rec. value: true for a BSC that manages at least one BTS using cavitycoupling
The value (true or false) is indifferent for a BSC that managesonly BTS with hybrid coupling
Used in: Reconfiguration procedure
Eng. Rules: If the value is ‘True’ then the value of btsHopReconfRestart (btsobject) must be true in case of cavity coupling in the BTS.
However, when enabling frequency hopping, it is advised to use
hybrid coupling and synthesized frequency hopping.
In order to facilitate the further use of frequency hopping in the
network, the parameter bscHopReconfUse can be set to “True”,
even if frequency hopping is not used yet.
btsHopReconfRestart Class 2 V8
Description: Whether hopping frequency reconfiguration is authorized on TXrestarts in a cell
Value range: [true / false]
Object: bts
Default value: true
Type: DP, Optimization
Rec. value: true (for a BTS using cavity coupling)
false (for a BTS using hybrid coupling)
Used in: Reconfiguration procedure
Eng. Rules: If the value is ‘True’ then the value of bscHopReconfUse must be true.
However, when enabling frequency hopping, it is advised to use
hybrid coupling and synthesized frequency hopping.
With cavity coupling, in order to facilitate the further use of
frequency hopping in the network, the parameter
btsHopReconfRestart can be set to “True”, even if frequency
hopping is not used yet.
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btsIsHopping Class 2 V7
Description: Whether frequency hopping is allowed in a cell
Value range: [hopping / noHopping / hoppingWithCarrierFilling /noHoppingWithCarrierFilling]
Object: bts
Default value: Hopping
Type: DP, Design
Rec. value: Hopping
Used in: Frequency Hopping
Eng. Rules: The two main advantages of using Frequency Hopping are interfererand frequency diversities. Enabling frequency hopping allows to adaptand maximize the frequency reuse efficiency by maximizing thecapacity in terms of offered Erlang/MHz/km². Moreover, enabling
frequency hopping makes easier the task of frequency planning andTRXs addition. Although when using DTX there is a few number ofRxQual measurements, there is no need to disable handovers onquality criteria, as no degradation was observed.
CAUTION! When TRX are hopping, it is highly recommended to modify someTDMA configuration. Channel SDCCH must be set on time slot 1 ofthe concerned TDMA. Moreover this modification can be introducedbefore enabling frequency hopping.
CAUTION! It is also recommended not to use Power Control with FrequencyHopping in case of cavity couplers. Indeed, with cavity couplers, theBCCH frequency can be part of the Mobile Allocation List (that is notpossible in case of Hybrid couplers) and then the gap between the
emitted power of two adjacent bursts could be at its maximum.Remark: Except this particular case (cavity coupler + FH + PWC) there is no
restriction in combining Frequency hopping with Power Control.
btsThresholdHopReconf Class 2 V8
Description: Minimum number of frequencies that must be working in a cell to allowfrequency hopping reconfiguration. If this attribute defines the nominalnumber of cell frequencies, the reconfiguration process is deactivated.Refer to the btsHopReconfRestart parameter.
Value range: [1 to 64]
Object: btsDefault value: 1
Type: DP, Optimization
Rec. value: 1
Used in: Reconfiguration procedure
Eng. Rules: This parameter is checked before reconfiguration is started, for cavitycoupling. If there are less remaining frequencies than the value of thisparameter, the cell is deconfigured. The minimum value (1) allows acell to be reconfigured even if there is only one frequency stillavailable.
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cellAllocation Class 2 V7
Description: List of no more than 64 frequencies allocated to a cell in the network
frequency band.Normally, the maximum number of frequencies that can be set up withthis parameter is 64 per frequency band. However, due to SI13 sizeconstraints, when GPRS or EDGE is activated in the cell and there isat least one hopping data TDMA, the limitation becomes a maximumof 55 frequencies (in V15.0 and V15.0.1) ,52 frequencies (in V15.1and V15.1.1), 49 frequencies (from V16).By definition, all cells covered by a given radio site use the samefrequency band defined by the type of the network (standardIndicator ). All cells declared as neighbor cells of a serving cell use the samefrequency band as the serving cell.
Value range: [1 to 124] (GSM 900 network),
[975 to 1023] & [0 to 124] (E-GSM network),[955 to 1023] & [0 to 124] (GSM-R network),[512 to 885] (GSM 1800 network),[512 to 810] (GSM 1900 network)[128 to 251] (GSM 850 network)
Object: bts
Default value:
Type: DP, Optimization
Rec. value: see Engineering Rules
Used in:
Eng. Rules: This list must include all the frequencies used by TRX of the cell, even
the BCCH frequency and shall respect following rules: With cavity couplers, two (2) consecutive frequencies must be
spaced of at least 600 kHz in order to avoid interference
With hybrid couplers, considering UL power control activated:
in case of intra cell and intrasite configuration Nortel recommends
400kHz frequency spacing between TRX with or without frequency
hopping.
in case of intersite configuration, 200kHz frequency spacing are
necessary between TRX with or without frequency hopping.
These frequency spacings (400kHz in intrasite and intracell, 200kHz
in intersite) guarantee a minimum of 12dB in C/I. This can providecertain quality of service. With particular applications (e.g. EDGE), an
upper frequency spacing is needed (600kHz for EDGE).
It is recommended to declare only 1 hopping frequency list by band
(the use of the frequency band is optimal with all hopping
frequencies in the same list and it is much easier for OAM).
If at least one of the cell allocation ARFCN is in the range [975;
1023] & [0], the BCCH should be in that range also (this monoband
EGSM cell does not support monoband PGSM MS nor dualband
PGSM/DCS1800 MS), else BCCH should be a PGSM one.
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CAUTION! When setting CellAllocation, a check is performed at OMCR in order toverify the number of frequencies. This number is limited by the spreadof frequencies
• if 1 =< spread of frequencies =< 112Then max number of frequencies = 64
• if 113 =< spread of frequencies =< 128
Then max number of frequencies = 29
• if 129 =< spread of frequencies =< 256
Then max number of frequencies = 22
• if 257 =< spread of frequencies =< 512
Then max number of frequencies = 18
The spread of frequencies is the maximal distance between the valueof frequence calculed as (Fmax – Fmin +1).This spread of frequencies
verification is performed for each band separately. For standardindicators like e-gsm and r-gsm, which have 2 ranged bands, thefollowing must be taken into account:
For E-GSM the range is [0..124]U[975..1023] ; so by realigning thefrequence the result is [975…1022, 1023, 1,..124]. the distance forexample100 and 1000 is 125 (not 901) because:
100 belongs to [0...124] spread of frequencies is 101
1000 belong to [975…1023] spread of frequencies is 24
fhsRef Class 2 V7
Description: Identifier of the frequencyHoppingSystem object that defines thefrequency hopping management parameters for the radio time slot
Setting this attribute and the maio attribute allows the time slot to obeyfrequency hopping laws.
Value range: [0 to 63]
Object: channel
Default value:
Type: DP, Optimization
Rec. value: see Engineering Rules
Used in:
Eng. Rules: It is advised to use only one (1) fhsRef per cell (when the Mobile Allocation is the same for all its TRX), because it is time saving forcreation at the OMC.
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hoppingSequenceNumber Class 2 V7
Description: Hopping sequence number used by a radio time slot which obeys
frequency hopping laws.Select different HSNs for nearby cells that use the same set offrequencies.
Value range: [0 to 63]
Object: frequencyHoppingSystem
Default value:
Type: DP, Optimization
Rec. value: see Engineering Rules
Used in: Synthesised frequency hopping
Eng. Rules: In case of synthesized frequency hopping, whatever the fractional
reuse pattern for TCH, using a unique HSN per site allows to avoidfrequency collisions. However, it leads to a specific MAIO plan, morerestricting than with the use of different HSN in cells (needs morefrequencies). Indeed, the frequency load would be higher withdifferent HSN. But it is possible to reach the maximum fractional load(value limited by RF constraints to 16,6 % for 1X1 pattern and 50 %for 1X3 pattern in case of no intra-site collision). When intra-sitecollision is allowed, field experience has shown that with anappropriate tuning of the parameters, 1X1 can go up to 20% fractionalload and 1X3 up to 58% while keeping a very good quality for theoffered capacity.) with a unique HSN per site and then systematicallyavoiding frequency adjacencies.
See also chapter General Rules For Synthesised Frequency Hopping
maio Class 2 V7
Description: Index in the list of frequencies allotted to a radio time slot, whichobeys frequency hopping laws.
Setting this attribute, together with the fhsRef attribute, allows the timeslot to obey frequency hopping laws.
Value range: [0 to N-1] N is the number of frequencies allotted to the time slot.
Object: channel
Default value:
Type: DP, Optimization
Rec. value: see Engineering Rules
Used in: Synthesised frequency hopping
Eng. Rules: The MAIO must be different for each TRX within a cell in order toavoid frequency collision. If the Mobile Allocation contains adjacentfrequencies, the difference between two TRX MAIO within a cell mustbe greater or equal than two (2).
However, for a 1X3 pattern, it is possible to use the same MAIOsequence in all cells of a same site. Moreover, for such a pattern, ifeach list of MA frequencies does not contain adjacent frequencies,adjacent MAIO can be used.For a 1X1 pattern, different MAIO for each TRX must be used and noadjacent MAIO if there are adjacent frequencies in the MA list.
See also chapter General Rules For Synthesised Frequency Hopping
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mobileAllocation Class 2 V7
Description: List of frequencies allocated in the network frequency band to a radiotime slot which obeys frequency hopping laws.
Normally, the maximum number of frequencies that can be set up withthis parameter is 63 i.e. 64 – BCCH frequency. However, due to SI13size constraints, when GPRS or EDGE is activated in the cell andthere is at least one hopping data TDMA (carrying at least onePDTCH), the limitation becomes a maximum of 55 – n frequencies (forV15.0 and V15.0.1) or 52 – n frequencies (for V15.1 and V15.1.1),or49 – n frequencies (from V16) where n is the number of non-hoppingfrequencies in the cell.
Value range: [1 to 124] (GSM 900 network),
[975 to 1023] & [0 to 124] (E-GSM network),[955 to 1023] & [0 to 124] (GSM-R),[512 to 885] (GSM 1800 network),[512 to 810] (GSM 1900 network)[128 to 251] (GSM 850 network).
Object: frequencyHoppingSystem
Type: DP, Optimization
Used in: Synthesised frequency hopping
Baseband Frequency Hopping
Rec. value: see Engineering Rules
Eng. Rules: This list must include all the hopping frequencies used by a TRX. Asthe first TRX of a cell does not hop, it is not related to a MA (TRX
channels frequency is BCCH).The following TRXs may have a common MA containing all thehopping frequencies (not including the BCCH frequency).
With cavity couplers, two (2) consecutive frequencies must be
spaced of at least 600 kHz in order to avoid interference, because
of material constraints.
With hybrid couplers, considering UL power control activated:
in case of intra cell and intrasite configuration Nortel recommends
400kHz frequency spacing between TRX with or without frequency
hopping.
in case of intersite configuration, 200 kHz frequency spacing are
necessary between TRX with or without frequency hopping.
These frequency spacings (400kHz in intrasite and intracell, 200kHz
in intersite) guarantee a minimum of 12dB in C/I. This can provide
certain quality of service. With particular applications (e.g. EDGE), an
upper frequency spacing is needed (600kHz for EDGE).
It is recommended to declare only 1 hopping frequency list by band
(the use of the frequency band is optimal with all hopping
frequencies in the same list and it is much easier for OAM).
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trafficPCMAllocationPriority Class 2 V9
Description: Allocation priority of a TDMA frame on the covering site PCMs
This attribute is used in case of Abis PCM reconfiguration.
Value range: [0 to 255]
Object: transceiver
Default value:
Type: DP, Optimization
Rec. value: 255 for the TDMA supporting the BCCH
0 for the others
Used in:
Eng. Rules: see chapter SDCCH Dimensioning and TDMA priorities.
zoneFrequencyHopping Class 2 V9
Description: Whether frequency hopping is authorised in the zone.
If frequency hopping is not allowed in a zone, a channel objects thatdescribe the radio time slots of the TDMA frames used in the zonecannot be allowed to hop.
Value range: [hopping / not hopping]
Object: transceiverZone
Default value: not hopping
Type: DP
Rec. value: see Engineering Rules
Used in:
Eng. Rules: In case of a dualband cell and if PDTCHs are configured on the innerzone, that parameter must be set to “not hopping” on thetransceiverZone corresponding to the inner zone.
In any other case that parameter must be set to “hopping”.
zoneFrequencyThreshold Class 2 V9
Description: Minimum number of frequencies needed to allow frequencyreconfiguration in the zone.
Value range: [1 to 64]
Object: transceiverZone
Default value: 1
Type: DP
Rec. value: TBD
Used in:
Eng. Rules:
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5.26. BSC LOAD MANAGEMENT PARAMETERS
processorLoadSupConf Class 3 V8
Description: Threshold used in the load control algorithm by the BSC
Value range: [0] The only accepted value is 0 (outOfRangeError).
Object: bsc
Default value: 0
Type: DP, Optimization
Rec. value: 0
Used in: Mechanism defined
Eng. Rules:
CAUTION! This parameter is valid for BSC12000 only.
estimatedSiteLoad Class 3 V15
Description: This parameter is used:
at site creation, in order to preset the erlang consumption of the
new Cell Group
ortherwise, in order to set the erlang consumption
Value range: [0 to 1100] erlangs. 1100 is the internal erlang capacity of a TMU2.
Object: btsSiteManager
Default value: 0
Type: DP
Rec. value: see Engineering Rules
Used in: Evolution of Load Balancing
Eng. Rules: It is usually recommended to try to set the estimatedSiteLoad of a siteat the creation of this site (with the maximum configuration wanted forthis site) to be sure that at this time the global dimensioning of theBSC is correct.
It may also help in handling exceptional events on some parts ofthe network.
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5.27. DUALBAND CELL PARAMETERS
early classmark sending Class 3 V10
Description: Whether Early classmark sending procedure initiated by a multibandmobile and/or a 2G-3G mobile is allowed.
The information is broadcast to the mobiles at regular intervals on thecell BCCH (SYSTEM INFORMATION n°3).
Value range: [Not Allowed, Allowed]
Object: bts
Default value: Not Allowed
Type: DP, Design
Rec. value: Allowed
Used in: Modified SYS INFO 3
Location Services GSM to UMTS handover (v17)
Eng. Rules: When this parameter is set to “allowed”, the mobile sends theClassmark_Change message just after the SABM and UA framesexchanged during the Immediate_Assignment procedure. Thismessage enables interband handover procedures (handovers on TCHand SDCCH, Directed Retry); Morever this parameter allows themobile to send its capacity downlink Advanced Receiver performance.In GSM cells where handover to UTRAN is possible, or UTRANmeasurement reporting is expected from the mobile, the "earlyclassmark sending" must also be requested from the mobile.
Therefore, if the operator is interested to have the SAIC mobile
penetration, it is recommended to set this parameter to “Allowed”In single band networks where no handover to 3G is required, “earlyclassmark sending” will be set to “not allowed”.In dual-band networks and in networks where handover to 3G may berequested, then early classmark sending will be set to “allowed”.
multi band reporting Class 3 V10
Description: Indication of the number of cells to be reported for each GSMfrequency band in multiband operation. This parameter is used bothfor normal and enhanced measurement reporting.
Value range: [0 : “no outband cell is favoured” / 1 : “1 strongest outband cell isfavoured” / 2 : “2 strongest outband cells are favoured” / 3 : “3strongest outband cells are favoured”
Object: bts
Default value: 0 : “no outband cell is favoured”
Type: DP, Optimization
Rec. value: “two strongest outband cells are favoured” (case of privilegedband)
”no outband cell is favoured” (case of no privileged band)
Used in: Multiband reporting
Enhanced Measurement Reporting (EMR)
UTRAN cell reporting using legacy measurement reports (V17)
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Eng. Rules: For values indicating the one (1), two (2) or three (3) strongest cellsout band, the multiband MS respectively reports the one, two or threestrongest allowed cells outside the current frequency band. Theremaining space in the report (at least 5, 4 or 3 cells) is used to giveinformation about cells in the current frequency band. If there are still
some remaining positions, they are used to report cells outside thecurrent frequency band.
When the operator wants to privilege one of the frequency band, it isadvised to report two (2) cells outside the current frequency band, forcells in the privileged frequency band. Then, neighbour cells in thepriority frequency band will be privileged. Actually, if multibandReporting is set to “1”, the risk is to report five (5)priority frequency band neighbour cells with a bad quality or signalstrength (near priority frequency band boundaries for example) andone (1) good neighbour cell in the low priority frequency band, butunder congestion. Thus the MS will not make a handover toward agood neighbour cell and the quality of service may be impacted.For cells outside the privileged frequency band, it is advised to report
three (3) cells outside the current frequency band. Thus, it ensures thereport of all (if less than 3) or at least three (3) neighours in the priorityfrequency band.In case no frequency band is preferred, the report of the “the sixstrongest cells” allows to make a handover toward the best neighbourcell, whatever the current cell is.
In case of 2G-3G handover being enabled, and EMR disabled (use ofnormal measurement reporting), it is necessary to exercise cautionwhen setting the parameters fDDMultiRatReporting andmultiBandReporting . These parameters define the number of UTRANcells and non-serving band GSM cells, respectively, that must beincluded by the mobile in the list of strongest cells in the measurement
report. Therefore it leaves (6 - fDDMultiRatReporting -multiBandReporting ) spaces for the serving band GSM cells.Therefore, if EMR is disabled, it is recommended not to exceedfDDMultiRatReporting = 2 and multiBandReporting = 2.
standard indicator AdjC Class 3 V10
Description: Type of network in which this neighbour cell is working
Value range: [gsm / extended gsm / dcs1800 / pcs1900 / R gsm / gsmdcs / dcsgsm/ gsm850 / gsm850pcs / pcsgsm850]
Object: adjacentCellHandover
Default value: gsm
Type: DP, Optimization
Rec. value: extended gsm if available in the network. See Engineering Rules
Used in: Oher procedures (Dual Band Handling)
Eng. Rules: The indicates standard indicator must have the same value inadjacentCellHandover or adjacentCellReselection objects and in theassociated neighbour bts object.
Refer to the standardIndicator parameter engineering rules to getmore information about neighbours management.
CAUTION! “gsmdcs” and “dcsgsm” are only available for S8000 DRX transceiverarchitecture.
“eGSM” is only available for S8000 CBCF transceiver architecture.
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standard indicator AdjC Class 3 V10
Description: Type of network in which this neighbor cell is working
Value range: [gsm / extended gsm / dcs1800 / pcs1900 / R gsm / gsmdcs (V12) /dcsgsm (V12) / gsm850 / gsm850pcs / pcsgsm850]
Object: adjacentCellReselection
Default value: gsm
Type: DP, Optimization
Rec. value: extended gsm if available in the network. See Engineering Rules
Used in: Oher procedures (Dual Band Handling)
Eng. Rules: The standard indicator must have the same value inadjacentCellHandover or adjacentCellReselection objects and in theassociated neighbour bts object
Refer to the standardIndicator parameter engineering rules to getmore information about neighbours management.
CAUTION! “gsmdcs” and “dcsgsm” are only available for S8000 DRX transceiverarchitecture.
“eGSM” is only available for S8000 CBCF transceiver architecture.
bCCHFrequency Class 3 V7
Description: Radio frequency allocated to a neighbour cell BCCH in the networkfrequency band.
The information is broadcast on the serving cell SACCH.
Value range: [1 to 124] (GSM 900 network),
[512 to 885] (DCS 1800 network),[512 to 810] (PCS 1900 network),[955 to 1023] & [0 to 124] (R–GSM network),[975 to 1023] & [0 to 124] (E–GSM network),[128 to 251] (GSM 850 network).
Object: adjacentCellHandOver
Type: DP
Rec. value:
Used in:
Eng. Rules:
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bCCHFrequency Class 3 V7
Description: Radio frequency used for selection and reselection management. The
information is broadcast on the serving cell BCCH.Value range: [1 to 124] (GSM 900 network ),
[512 to 885] (DCS 1800 network),[512 to 810] (PCS 1900 network),[955 to 1023] & [0 to 124] (R–GSM network),[975 to 1023] & [0 to 124] (E–GSM network).[128 to 251] (GSM 850 network)
Object: adjacentCellReselection
Type: DP
Rec. value:
Used in: Directed Retry Handover: BSC (or local) mode
Eng. Rules:
Note: An adjacentCellReselection object can use the same BCCH as theserving cell to which it is associated. This allows a mobile toimmediately recover the cell on which it was “camping” after beingswitched off, then switched back on, and is especially useful in theselection process.
bCCHFrequency Class 2 V7
Description: Radio frequency allocated to a cell BCCH (Broadcast ControlCHannel) in the network frequency band.
The information is broadcast on the cell SACCH.The BCCH frequency is automatically assigned to the radio time slotcarrying the cell BCCH when the cell is brought into service(absoluteRFChannelNo attribute of the channel object describing thecarrier TDMA frame TS0). It is broadcast to the radio time slotwhenever modified.The BCCH is used by the BTS for broadcasting cell related systeminformation to MS, such as frequency band and list of frequencychannels used, authorized services and access conditions, list ofneighbour cells, and radio parameters (maximum transmissionstrength, minimum reception strength, etc).
Value range: [1 to 124] (GSM 900 network ),
[512 to 885] (DCS 1800 network),
[512 to 810] (PCS 1900 network),[955 to 1023] & [0 to 124] (R–GSM network),[975 to 1023] & [0 to 124] (E–GSM network).[128 to 251] (GSM 850 network)
Object: bts
Type: DP
Rec. value:
Used in:
Eng. Rules: If at least one of the cell allocation ARFCN is in the range [975; 1023]& [0], the BCCH should be in that range also (this monoband EGSMcell does not support monoband PGSM MS nor dualband
PGSM/DCS1800 MS), else BCCH should be a PGSM one.
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standardIndicator Class 2 V10
Description: Type of network in which the cell is working
From the value given to this attribute, the OMC–R determines thenetwork frequency band and the frequencies that can be used by allradio entities (cells and radio time slots) in the related site.
Value range: [gsm / extended gsm / dcs1800 / pcs1900 / R gsm / gsmdcs (V12) /dcsgsm (V12) / gsm 850 / gsm850pcs / pcsgsm850]
Object: bts
Type: DP
Rec. value:
Checks:
GSM 900 network (gsm)The GSM 900 frequency band is 2*25 MHz wide and includes 124
pairs of carrier frequencies, numbered [1 to 124], which are 200 kHzapart:
Uplink direction (MS–to–BTS) = 890 to 915 MHz
f1 = 890 + 0.2xN MHz where N = [1 to 124]
Downlink direction (BTS–to–MS) = 935 to 960 MHz
f2 = f1 + 45 MHz
GSM 850 networkThe GSM 850 frequency band is 2*25 MHz wide and includes 124pairs of carrier frequencies, numbered [1 to 124], which are 200 kHzapart:
Uplink direction (MS–to–BTS) = 824 to 849 MHz
f1 = 824.2 + 0.2x N MHz where N = [1 to 124]
Downlink direction (BTS–to–MS) = 869 to 894 MHz
f2 = f1 + 45 MHz
EXTENDED GSM network (extended gsm)The extended GSM frequency band is 2*35 MHz wide and includes174 pairs of carrier frequencies, numbered [0 to 124] and [975 to1023], which are 200 kHz apart:
Uplink direction (MS–to–BTS) = 880 to 915 MHz
f1 = 880.2 + 0.2x(N – 975) MHz where N = [975 to 1023]f1 = 890 + 0.2xN MHz where N = [0 to 124]
Downlink direction (BTS–to–MS) = 925 to 960 MHz
f2 = f1 + 45 MHz
GSM–R network (R gsm)The GSM–R frequency band is 2*39 MHz wide and includes 194 pairsof carrier frequencies, numbered [0 to 124] and [955 to 1023], whichare 200 kHz apart:
Uplink direction (MS–to–BTS) = 876 to 915 MHz
f1 = 876.2 + 0.2x(N – 955) MHz where N = [955 to 1023]f1 = 890 + 0.2xN MHz where N = [0 to 124
Downlink direction (BTS–to–MS) = 921 to 960 MHz
f2 = f1 + 45 MHz
GSM 1800 network (dcs1800)
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The GSM 1800 frequency band is 2*75 MHz wide and includes 374pairs of carrier frequencies, numbered [512 to 885], which are 200kHz apart:
Uplink direction (MS–to–BTS) = 1710 to 1785 MHz
f1 = 1710k2 + 0.2x(N – 512) MHz where N = [512 to 885] Downlink direction (BTS–to–MS) = 1805 to 1880 MHz
f2 = f1 + 95 MHz
GSM 1900 network (pcs1900)The GSM 1900 frequency band is 2*60 MHz wide and includes 299pairs of carrier frequencies, numbered [512 to 810], which are 200kHz apart:
Uplink direction (MS–to–BTS) = 1850 to 1910 MHz
f1 = 1850.2 + 0.2x(N – 512) MHz where N = [512 to 810]
Downlink direction (BTS–to–MS) = 1930 to 1990 MHz
f2 = f1 + 80 MHz
GSM 900 – GSM 1800 network (gsmdcs)The primary band is GSM 900The secondary band is GSM 1800
GSM 1800 – GSM 900 network (dcsgsm)The primary band is GSM 1800The secondary band is GSM 900
GSM 850 – GSM 1900 network (gsmdcs)The primary band is GSM 850The secondary band is GSM 1900
GSM 1900 – GSM 850 network (dcsgsm)The primary band is GSM 1900The secondary band is GSM 850
Remark: The frequency bands defined hereabove are the definition of theETSI.
Used in: Concentric/DualCoupling/DualBand Cell Handover
Eng. Rules:
As P-GSM range is included in E-GSM one, the following table givesfor each current cell standard indicator, the type (main or other) ofneighbouring cells according to their standard indicator:
standard indicator Adjc (neighbouring cell)
PGSM E GSM GSM 1800
GSM 900 main other other
E GSM main main otherstandardIndicator
(current cell)GSM 1800 other other main
If one of a cell ARFCN is in [975;1023] & [0] range, this monobandEGSM (RGSM or EGSM) cell does not support monoband PGSM MSnor dualband PGSM/DCS1800 MS.If a EGSM cell has a BCCH in PGSM band, a PGSM mobile will listento it and may be handed over in that cell on a TCH in the E band. Inthat case, the mobile will send a handover failure.
Sys-infos management:
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According to recommendations, only « main » frequencies can bepresent in the SI2 and SI2bis (resp. 5 and 5bis).Following table gives the standard indicator of the neighbouring cellsthat can be included in the different sys_info messages.(extended gsm is noted EGSM in the table).
SYS_INFO
SI2 / SI5 SI2 bis / SI5 bis SI2 ter / SI5 ter
GSM 900 GSM GSM if neededE GSM + GSM1800 (1)
E GSMGSM + EGSM
GSM + E GSM ifneeded
GSM 1800standardIndicator
(current cell)
GSM 1800 GSM 1800GSM 1800 ifneeded
GSM + E GSM
Note (1): In that case, the number of frequencies in the frequency listis limited due to their large range.
=> Thus, due to the range of frequencies in EGSM + GSM 1800bands, and the fact that only 1 message (ter) can contain suchneighbours info (if StandardIndicator = GSM), it is stronglyrecommended to set the standard indicator of PGSM cells containingEGSM neighbours to extended gsm (2 messages to encode EGSMneighbours).
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5.28. DTX PARAMETERS
cellDtxDownLink Class 3 V7
Description: Whether the use of discontinuous transmission in BTS–to–MSdirection is allowed in a cell
Value range: [enabled / disabled]
Object: bts
Default value: enabled
Type: DP, Optimization
Rec. value: see Engineering Rules
Used in: Downlink DTX
Eng. Rules: DTXDownLink is particularly interesting in case of low interferednetworks with fractional reuse patterns for frequency plan. In this
case, it is recommended to uses a reactive configuration with a shortdelay between HO decision (runHandover=1) and with short averagewindows (Hreqt = 1, HreqAve = 4). Ho margins can also be lowered.
CAUTION! Using this feature may create a more sensitivity to bad values (fading,frequencies collision). Activation of DTXDownlink when DTX isalready used leads to a diminution in the precision of themeasurement on the cell, on quality and on level.
dtxMode Class 3 V7
Description: MS control of the discontinuous transmission mechanism in a cell
Discontinuous transmission is designed to lessen MS battery
consumption and diminish interference by breaking off thetransmission when no data or speech are being transmitted.
Value range: [FRmsmayuseDTX / HRmsshallnotuseDTX, FRmsshalluseDTX /HRmsshallnotuseDTX, FRmsmayuseDTX / HrmsmayuseDTX,FRmsshallnotuseDTX / HRmsshallnotuseDTX, FRmsshalluseDTX /HrmsshalluseDTX, FRmsshallnotuseDTX / HRmsshalluseDTX]
Object: bts
Default value: msMayUseDtx
Type: DP, Optimization
Rec. value: msShallUseDtx
Used in: Uplink DTX Eng. Rules:
CAUTION! When AMR is activated that parameter should be set toFRmsshalluseDTX / HRmsshalluseDTX
See also chapter Impact of DTX on Averaging
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5.29. MISCELLANEOUS
Data14_4OnNoHoppingTs Class 3 V12
Description: Whether data 14.4 kbit/s transmission rate is allowed at bts level onthe non hopping TSs
Value range: [disabled / enabled]
Object: bts
Default value: disabled
Type: DP, Optimization
Rec. value: TBD
Used in:
Eng. Rules:
data mode 14.4 kbit/s Class 2 V12
Description: Whether data 14.4 kbit/s transmission rate is allowed
Value range: [disabled / enabled]
Object: transcoderBoard
Default value: disabled
Type: DP
Rec. value: TBD
Used in:
Eng. Rules:
data non transparent mode Class 3 V12
Description: Set of transmission rates used for data non transparent modetransmission of the Radio interface and Abis interface.
Value range: [9.6 / 14.4] (kbit/s)
Object: bts
Default value: 9.6 kbit/s
Type: DP
Rec. value: TBD
Used in:
Eng. Rules:
data non transparent mode Class 3 V12
Description: Set of transmission rates used for data non transparent modetransmission of the Radio interface and Abis interface.
Value range: [9.6 / 14.4] (kbit/s)
Object: signallingPoint
Default value: 9.6 kbit/s
Type: DP
Rec. value: TBD
Used in:
Eng. Rules:
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data transparent mode Class 3 V12
Description: Set of transmission rates used for data transparent mode transmission
of the Radio interface and Abis interface.Value range: [“1.2/0.075” / 0.6 / 1.2 / 2.4 / 4.8 / 9.6 / 14.4] (kbit/s)
Object: bts
Default value:
Type: DP
Rec. value: TBD
Used in:
Eng. Rules:
data transparent mode Class 3 V12
Description: Set of transmission rates used for data transparent mode transmissionof the Radio interface and Abis interface.
Value range: [“1.2/0.075” / 0.6 / 1.2 / 2.4 / 4.8 / 9.6 / 14.4] (kbit/s)
Object: signallingPoint
Default value:
Type: DP
Rec. value: TBD
Used in:
Eng. Rules:
measurementProcAlgorithm Class 2 V12
Description: Whether the new L1M interface is used
Value range: [L1MV1, L1MV2]
L1MV1: the older L1M is used
L1MV2: the newer L1M is used
Object: bts
Type: DP, Optimization
Rec. value: L1MV2
Used in: Measurement Processing
Direct TCH Allocation and Handover Algorithms
Eng. Rules: L1MV2 is not supported on DCU2.
It is not recommended to set L1MV2 on a DCU2/DCU4 BTS mixedconfiguration since the enhancements offered will be available only onpart of the site so with a call processing not homogeneous on thewhole communications.Major benefits are:
ability to support advanced capacity and coverage features such
as “Automated cell tiering”
capture process more reactive
less handover failure (better updating of eligible cells)
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diversity = “enabled”, provided diversity antenna(s) have been fitted tothe BTS.
diversity = “disabled” otherwise
2/ In and after v17.0 :diversity = “enhancedDiversity”, for eDRX and Radio Module family,provided diversity antenna(s) have been fitted to the BTS.
diversity = “disabled” in other cases.
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5.31. PCM ERROR CORRECTION PARAMETERS
Note : this feature is no longer supported as of V17.
enhancedTRAUFrameIndication V12
Description: before V17 : Whether the BTS uses the Enhanced TRAU Frame(ETF) for TCU
After V17 : This parameter is no longer useful in V17 as the featurePCM Error Correction is no longer supported
Value range: [notAvailable / available / active]
Object: bsc
Default value: n/a
Type: DI, Optimization
Rec. value: n/a
Used in: PCM Error Correction
Eng. Rules: The PCM Error Correction is no longer supported as of BSS V17release. This parameter is no longer useful and the OMC-R V17automatically forces its value to “notAvailable”.
pcmErrorCorrection Class 2 V12
Description: Before V17 : whether the bts uses the new ETF (Enhanced TRAUFrame) frame (set to “1”) or the ETSI “Rec 08.60” frame (set to “0”).
After V17 : This parameter is no longer useful in V17 as the featurePCM Error Correction is no longer supported.
Value range: [0 / 1]
Object: bts
Default value: n/a
Type: DP, Optimization
Rec. value: n/a
Used in: PCM Error Correction
Eng. Rules: The PCM Error Correction is no longer supported as of BSS V17release. This parameter is no longer useful and the OMC-R V17automatically forces its value to 0.
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5.32. CELL TIERING PARAMETERS
enhCellTieringConfiguration Class 3 V14
Description: This attribute allows to configure the cell tiering algorithm at BTS level
This parameter is composed of the following five parameters:
hoMarginTiering
nbLargeReuseDataChannels
numberOfPcwiSamples
pwciHreqave
selfTuningObs
Object: handOverControl
Type: DP, Optimization
hoMarginTiering Class 3 V14
Description: Hysteresis between the uCirDLH and lCirDLH tiering thresholds. Usedto avoid ping-pong handovers (expressed in dB)
Value range: [0 to 63] dB
Object: handOverControl
Default value: 4 dB
Type: DP, Optimization
Rec. value: 4dB (to be optimized with the HO cell tiering monitoring)
Used in: Automatic cell tiering
Eng. Rules:
interferenceType Class 3 V14
Description: It is used for identifying the type of interference created by a neighborcell. The possible values are not applicable (no interference), adjacentinterference or cochannel interference.
Value range: [notApplicable / adjacent / coChannel]
Object: adjacentCellHandOver
Default value: notApplicable
Type: DP, Optimization
Rec. value: This parameter should be set according to frequency planstrategy.
Used in: Automatic cell tiering
Eng. Rules:
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nbLargeReuseDataChannels Class 3 V14
Description: Mean number of logical channels belonging to the large frequency
reuse pattern and used at the same time for data communicationsValue range: [-16 to +16]
Object: handOverControl
Default value: 0
Type: DP, Optimization
Rec. value: To be determined according to configuration (see below)
Used in: Automatic cell tiering
Eng. Rules: This parameter gives the mean number of radio TS in the large reusepattern (BCCH) used for data communications (and consequently notavailable for tiering).
nbLargeReuseDataChannels = number of timeslots dedicated GPRS
+ average number of timslots for 14.4 if the parameter data 14.4OnNoHoppingTs is set to 1.This last value can be obtained through the counters 1705/2 and1707/2.
numberOfPwciSamples Class 3 V14
Description: Minimum number of PwCI samples required to reach a reliabledistribution (representative of the real distribution in the whole cell) *1000
Value range: [0 to 60]
Object: handOverControl
Default value: 20
Type: DP, Optimization
Rec. value: 20. However, it is a deal between PWCI distribution refresh timeand accurancy (see below).
Used in: Automatic cell tiering
Eng. Rules: It gives the minimum number of PWCI samples required to reach areliable distribution of PWCI that will be representative of the realdistribution in the whole cell x 1000.
The number of samples before a PWCI distribution is undertaken is :1000 x numberOfPwciSamples.
For example, in a cell bearing 29 TCHs and loaded at 75%, at eachmoment, 0.75x29=21.75 TCHs are occupied. Then, every 480 mswe’ll have 21.75 samples available and every second(1000*21.75)/480=45.3 samples. If we set numberOfPwciSamples at20, a PWCI distribution will be computed when 20000 samples will beavailable, wich means that a PWCI distribution will be computed every20000/45.3 = 441.5 seconds ( almost every 7 minutes and a half).
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pwciHreqave Class 3 V12
Description: Averaging window size for PwCI. It defines the number of
measurement reports for a PWCI arithmetic averaging.Value range: [0 to 16]
Object: handOverControl
Default value: 8
Type: DP, Optimization
Rec. value: 8
Used in: Automatic cell tiering
Eng. Rules: In a given cell, each communication in the cell reports itsmeasurements every 480 ms which allows computing the PWCI.When 20000 samples are gathered in the cell, a distribution of all thePWCI is computed and, lCirDLH and uCirDLH are determined for the
cell.In order to take a tiering decision, a PWCI is averaged over apwciHreqAve window, for each communication and compared tolCirDLH and uCirDLH obtained from the previous distribution, to lead(or not) to a handover decision.
selfTuningObs Class 3 V12
Description: BTS mode of the sending the PwCI distribution on the Abis interface.This allows a closer monitoring of the cell tiering feature behavioronce activated.
Value range: [pwCi distribution not sent,pwCi distribution sent after gathering,one pwCi distribution sent per hour]
Object: handOverControl
Default value: pwCi distribution not sent
Type: DP, Optimization
Rec. value: Other than “pwCi distribution not sent” when fine tuning thefeature, with close monitoring needed.
Used in: Automatic cell tiering
Eng. Rules: The possible values are pwCi distribution not sent (PWCI distributionis gathered but not sent onto the Abis interface), pwCi distribution sent
after gathering (the distribution is sent each time a new tieringthreshold is computed for a maximum of 10 cells) or one pwCidistribution sent per hour (the distribution is sent when a new tieringthreshold is computed but no more than one message every hour fora maximum of 40 cells).
Remark: PWCI distribution may be gathered and sent onto the Abis interfaceindependantly of tiering activation.
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5.33. ENCODING PARAMETERS
speechMode Class 3 V12
Description: List of the speech algorithms associated with channel use modes inthe cell
The “full rate” value refers to the standard algorithm. The “enhancedfull rate” value only applies when all the TCUs linked to the BSC areequipped with TCB2 boards.
Value range: list of [algoid] where algoid id: full rate, enhanced, full rate, AMR fullrate, AMR half rate
Object: bts
Default value: [full rate, enhanced full rate]
Type: DP
Rec. value: [full rate, enhanced full rate]Used in: AMR - Adaptative Multi Rate FR/HR
Eng. Rules:
CAUTION! When AMR is activated, SpeechMode must be set to full rate,enhanced full rate, AMR full rate, AMR half rate
speechMode Class 3 V12
Description: List of the speech algorithms associated with channel use modes onthe A interface. The “full rate” value refers to the standard algorithm.The “enhanced full rate” value only applies when all the TCUs linked
to the BSC are equipped with TCB2 boards.Value range: list of [algoid] where algoid id: full rate, enhanced, full rate, AMR full
rate, AMR half rate
Object: signallingPoint
Default value: [full rate, enhanced full rate]
Type: DP
Rec. value: [full rate, enhanced full rate]
Used in: AMR - Adaptative Multi Rate FR/HR
Eng. Rules:
CAUTION! When AMR is activated, SpeechMode must be set to full rate,enhanced full rate, AMR full rate, AMR half rate
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5.34. SMS-CELL BROADCAST PARAMETERS
smsCB Class 3 V12
Description: Whether broadcasting of short messages in unacknowledged mode isauthorized in a cell.
Value range: [used / unused]
Object: bts
Default value: used
Type: DP
Rec. value:
Used in: SMS-Cell Broadcast
Eng. Rules: Configuration of logical channels and broadcast of short messagesare managed by two separate OMC-R functions.
When a short message broadcast is started, the presence of a CBCHin the channelType of a channel object is dependent on a concernedbts object.However, the SMS-CB function are not aware of changes made tothat attribute.Consequently, withdrawing a CBCH from the configuration will stopany short message broadcast in the concerned cell without th SMS-CB function knowing.
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5.35. PROTECTION AGAINST INTRACELL HO PING-PONGPARAMETERS
capacityTimeRejection Class 3 V14
Description: Rejection time of a capacity intracell handover after an intracellhandover
Value range: [0 to 120 s.]
Object: handOverControl
Default value: 0 s.
Type: DP
Rec. value: [15 to 30 s.]
Used in: Protection against Intracell HO Ping-Pong
Handover mechanisms (AMR)
Eng. Rules:
Remark: Applies to a BSC 3000 architecture only.
CAUTION! When AMR is activated that parameter should be set to 40 s
minTimeQualityIntraCellHO Class 3 V14
Description: Rejection time of a quality intracell handover after an intracellhandover
Value range: [0 to 120 s.]
Object: handOverControl
Default value: 0 s.
Type: DP
Rec. value: [0 to 10 s.]
Used in: Protection against Intracell HO Ping-Pong
AMR - Adaptative Multi Rate FR/HR
Eng. Rules:
Remark: Applies to a BSC 3000 architecture only.
Note: That parameter can be named qualityTimeRejection in the literature.
CAUTION! When AMR is activated that parameter should be set to 5 s
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5.36. AUTOMATIC HANDOVER ADAPTATION PARAMETERS
selfAdaptActivation Class 3 V12
Description: Use for activate the Automatic Handover adaptation
Value range: [enabled / disabled]
Object: bts
Default value: disabled
Type: DP
Rec. value: enabled
Used in: Automatic handover adaptation
Eng. Rules:
servingfactorOffset Class 3 V12
Description: This attribute defines the offset linked to the serving cell, used todecrease the HO margin, in some specific cases
Value range: [-63 to 63]
Object: handoverControl
Default value: - 2
Type: DP
Rec. value: 0
Used in: Automatic handover adaptation
Eng. Rules:
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neighDisfavorOffset Class 3 V12
Description: This attribute modifies the offset linked to the neighbouring cell, used
to increase the HO marging, in some specific casesValue range: [-63 to 63]
Object: handoverControl
Default value: 2
Type: DP
Rec. value: 2
Used in: Automatic handover adaptation
Eng. Rules:
Note: That parameter can be named offsetNeighbouringCell at the MMI.
rxQualAveBeg Class 3 V12
Description: This attribute defines the number of quality measurement results usedby the power control mechanism, in short averaging algorithm
Value range: [1 to 10]
Object: handoverControl
Default value: 2
Type: DP
Rec. value: same as RxlevHreqAveBeg
Used in: Automatic handover adaptation
Fast Power Control at TCH assignment (Pc_3)
Eng. Rules:
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5.37. GSM TO UMTS HANDOVER PARAMETERS
cId Class 3 V17
Description: Cell identity of the UMTS neighbouring cell for handover
Value range: 0..65535
Object: adjacentCellUTRAN
Default value: 0
Type: DP
Rec. value: n/a
Used in: GSM to UMTS handover (v17)
Eng. Rules: N/A
compressedModeUTRAN Class 3 V17
Description: flag to indicate whether compressed mode UTRAN is supported ornot. This flag is used by the network to indicate to mobiles whether touse a compressed version of the INTER RAT HANDOVER INFOmessage (UE to UTRAN message).
Value range: enabled/disabled
Object: bts
Default value: disabled
Type: DP
Rec. value: disabled
Used in: GSM to UMTS handover (v17)
Eng. Rules: The UTRAN_CLASSMARK_CHANGE message sent by UE to theBSS takes about 2 or 3 radio frames. However, when supported bythe UTRAN network, it is possible to reduce the size of this messagethanks to the compression of UE radio access capabilities andpredefined configuration IE. This option is indicated inIMMEDIATE_ASSIGNMENT message sent to the UE (IA rest octetsfields). For that purpose, the parameter compressedModeUTRANindicates whether compression of UE information elements is
supported.
diversityUTRAN Class 3 V17
Description: flag indicating whether there is diversity in the neighbouring UTRANcell
Value range: no diversity/diversity
Object: adjacentCellUTRAN
Default value: no diversity
Type: DPRec. value: see Eng. rules
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Used in: GSM to UMTS handover (v17)
Eng. Rules: Please refer to diversity
earlyClassmarkSendingUTRAN Class 3 V17Description: flag indicating whether UTRAN classmark change message shall be
sent with Early Classmark Sending
Value range: disabled/enabled
Object: bts
Default value: disabled
Type: DP
Rec. value: enabled
Used in: GSM to UMTS handover (v17)
Eng. Rules: earlyClassmarkSendingUTRAN shall be set to “enabled” before
handover 2G to 3G feature is activated.fDDARFCN Class 3 V17
Description: fDD channel number of the UTRAN neighbouring cell
Value range: 0..16383
Object: adjacentCellUTRAN
Default value: N/A
Type: DP
Rec. value: N/A
Used in: GSM to UMTS handover (v17)
Eng. Rules: N/A
gsmToUMTSServiceHo Class 3 V17
Description: This parameter serves to disable 2G-3G handover at BSC level or toindicate the preference (2G versus 3G cells) to be applied forhandovers
Value range: “should”/”should not”/”shall not”/”gsm to UMTS HO disabled”
Object: bsc
Default value: “gsm to UMTS HO disabled”
Type: DPRec. value: “should”
Used in: GSM to UMTS handover (v17)
Eng. Rules: See GSM to UMTS handover (v17) section. This parameter is usefulin only 2 cases :
Case n°1 : the “service handover” field in HANDOVER REQUEST and ASSIGNMENT REQUEST is missing.
Case n°2 : the network operator wants to disable the 2G to 3Ghandover on the BSC, regardless of the presence, and/or the value, ofthe “service handover” field.
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hoMarginUTRAN Class 3 V17
Description: Handover margin for PBGT handover to a UMTS cell
Value range: -63 dB to 63 dB, in 1dB steps
Object: adjacentCellUTRANDefault value: 63 dB
Type: DP
Rec. value: - 6
Used in: GSM to UMTS handover (v17)
Eng. Rules: If the operator wants to unload GSM traffic:
UMTS RSCP is lower than GSM Rxlev where a quite a high value isrequired for a good quality. This margin controls the probability toperform a handover.
Note that a the quality of UTRAN neighboring is ensured by thefDDreportingThreshold and fDDreportingThreshold2 parameter
hoMarginAMRUTRAN Class 3 V17
Description: Handover margin for intercell quality handovers to UMTS, for AMRcalls
Value range: -63 dB to 63 dB, in 1dB steps
Object: adjacentCellUTRAN
Default value: 63 dB
Type: DP
Rec. value: see Eng. Rules
Used in: GSM to UMTS handover (v17)
Eng. Rules: TBD
hoMarginRxLevUTRAN Class 3 V17
Description: handover margin for signal strength handover to UMTS
Value range: -63 dB to 63 dB, in 1dB steps
Object: adjacentCellUTRAN
Default value: 63 dB
Type: DP
Rec. value: see Eng. Rules
Used in: GSM to UMTS handover (v17)
Eng. Rules: TBD
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hoMarginRxQualUTRAN Class 3 V17
Description: handover margin to be used for signal quality handover to UMTS
Value range: -63 dB to 63 dB, in 1dB steps
Object: adjacentCellUTRAN
Default value: 63 dB
Type: DP
Rec. value: see Eng. Rules
Used in: GSM to UMTS handover (v17)
Eng. Rules: TBD
hoMarginDistUTRAN Class 3 V17
Description: handover margin for handover to UMTS on distance criterion
Value range: -63 dB to 63 dB, in 1dB steps
Object: adjacentCellUTRAN
Default value: 63 dB
Type: DP
Rec. value: see Eng. Rules
Used in: GSM to UMTS handover (v17)
Eng. Rules: TBD
hoMarginTrafficOffsetUTRAN Class 3 V17
Description: offset to be subtracted to the homarginUTRAN to allow handover fortraffic reason when the current cell is congested
Value range: 0 dB to 63 dB, in 1dB steps
Object: adjacentCellUTRAN
Default value: 63 dB
Type: DP
Rec. value: see Eng. Rules
Used in: GSM to UMTS handover (v17)
Eng. Rules: TBD
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hoPingpongCombinationUTRAN Class 3 V17
Description: list of pair of causes indicating the causes of ping-pong handovers in
the overlapping areas. Each pair is structured as follows : (incomingHO cause, outgoing HO cause). Incoming HO cause indicates theessential handover cause which leads to enter the neighbour cell.outgoing HO cause indicates the non-essential handover cause whichleads to leave the neigbour cell.
Value range: list of pairs of causes (GSM to UMTS HO, UMTS to GSM HO): traffic,powerbudget, directed retry, Rxlev, Rxqual, distance, O&M (forcedHO), all, allpowerbudget.
Object: adjacentCellUTRAN
Default value: (rxqual, pbgt)
Type: DP
Rec. value: (all, pbgt)Used in: GSM to UMTS handover (v17)
Eng. Rules:
hoPingpongTimeRejectionUTRAN Class 3 V17
Description: time that must elapse before attempting another handover towards anUTRAN cell. Refer to HOPingpongCombinationUTRAN attribute forthe combinations of HO causes for which this timer applies. To avoidping-pong handovers this new timer is started after a successful
handover. Up to the expiry of this timer, any HANDOVERINDICATION message received from the BTS is ignored by the BSC.
Value range: : 0...60 (0 means immediately).
Object: adjacentCellUTRAN
Default value: 30 seconds
Type: DP
Rec. value: 30 seconds
Used in: GSM to UMTS handover (v17)
Eng. Rules:
hoRejectionTimeOverloadUTRAN Class 3 V17
Description: time that must elapse before attempting another handover towards acongested UTRAN cell
Value range: 0..60 (60 means “immediately”)
Object: bsc
Default value: 30 seconds
Type: DP
Rec. value: 30 seconds
Used in: GSM to UMTS handover (v17)
Eng. Rules:
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locationAreaCodeUTRAN Class 3 V17
Description: Location area code of the UMTS neighbouring cell
Value range: 0..65535
Object: adjacentCellUTRAN
Default value: N/A
Type: DP
Rec. value: N/A
Used in: GSM to UMTS handover (v17)
Eng. Rules: N/A
mobileCountryCodeUTRAN Class 3 V17
Description: Mobile Country Code (MCC) of the UTRAN neighbouring cellValue range: 000…999 (string)
Object: adjacentCellUTRAN
Default value: N/A
Type: DP
Rec. value: N/A
Used in: GSM to UMTS handover (v17)
Eng. Rules: N/A
mobileNetworkCodeUTRAN Class 3 V17
Description: Mobile Network Code (MNC) of the UTRAN neighbouring cell
Value range: 000…999 (string)
Object: adjacentCellUTRAN
Default value: N/A
Type: DP
Rec. value: N/A
Used in: GSM to UMTS handover (v17)
Eng. Rules: N/A
offsetPriorityUTRAN Class 3 V17
Description: priority offset applied by the BSC when selecting the candidate cell forthe handover process
Value range: 1..5
Object: adjacentCellUTRAN
Default value: 1
Type: DP
Rec. value: 1
Used in: GSM to UMTS handover (v17)
Eng. Rules:
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rNCId Class 3 V17
Description: identity of the UTRAN neighbouring cell’s RNC
Value range: 0..4095
Object: adjacentCellUTRAN
Default value: N/A
Type: DP
Rec. value: N/A
Used in: GSM to UMTS handover (v17)
Eng. Rules: N/A
rxLevDLPbgtUTRAN Class 3 V17
Description: downlink signal strength threshold above which handovers to UTRANfor cause power budget are inhibited
Value range: <-110 dBm, -110<x<-109, … to >-48 dBm
Object: adjacentCellUTRAN
Default value: >-48
Type: DP
Rec. value: see Eng. Rule
Used in: GSM to UMTS handover (v17)
Eng. Rules: This parameter has to be managed carefully because it can prevent
all the UTRAN handover for power budget when set to less than -110.
Moreover, the setting of this parameter has to be done with the help of
some radio measurement campaigns.
This parameter shall be disabled by setting the value to more
than –48 (dBm).
rxLevMinCellUTRAN Class 3 V17
Description: minimum signal strength level that the MS must measure on an UMTSneighbour cell to be able to be granted a handover to this UMTSneighbour cell
Value range: <-110 dBm, -110<x<-109, … to >-48 dBm
Object: adjacentCellUTRAN
Default value: >-48
Type: DP
Rec. value: see Eng. Rule
Used in: GSM to UMTS handover (v17)
Eng. Rules: The value of rxLevMinCellUTRAN must be greater than the value ofminimumCpichRscpValueForHO UTRAN parameter.
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scramblingCode Class 3 V17
Description: scrambling code of the UTRAN neighbouring cell
Value range: 0..511
Object: adjacentCellUTRAN
Default value: N/A
Type: DP
Rec. value: N/A
Used in: GSM to UMTS handover (v17)
Eng. Rules: N/A
t3121 Class 3 V17
Description: t3121 has the same use as t3103 in the GSM inter-BSC handoverprocedure. It sets the value before countdown of T3121 timer definedin the GSM specification .
T3121 starts when the BSC sends an INTER SYSTEM TO UTRANHANDOVER message to the mobile. T3121 stops when the mobilehas correctly seized the UTRAN channel. The purpose of this timer isfor the BSC to keep the old channels long enough for the mobile to beable to return to the old channels if necessary. On expiry of T3121(indicating the mobile is lost), the BSC may release the channels.
Value range: 2..255 seconds
Object: bts
Default value: 12 seconds
Type: DP
Rec. value: 12 seconds
Used in: GSM to UMTS handover (v17)
Eng. Rules: T3121 purpose is very similar to T3103 one. However,INTERSYSTEM TO UTRAN HANDOVER COMMAND message fromBSS to Mobile is much larger than the HANDOVER COMMANDmessage so it takes about one second more to send the inter systemmessage to the MS. An additional safety margin should therefore be
considered for LAPDm repetitions.
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5.38. AMR - ADAPTATIVE MULTI RATE FR/HR PARAMETERS
BTS OBJECT
amrUlFrAdaptationSet Class 3 V15
Description: Define the lines of parameter used for the adaptation mechanism.
It sets the C/I thresholds when AMR speech codecs are used on a FRchannel in UL.when AMR speech codecs are used.
Value range: [0 to3]
Object: bts
Default value: 0
Type: DP
Rec. value: 3Used in: Codec mode adaptation
Eng. Rules:
0: typical radio condition
1: optimistic radio condition
2: pessimistic radio condition
3: personalize with the BSC data configuration table
The recommanded value of 0 offers a good compromise between HRpenetration and radio environment.For optimization of the table amrUlFrAdaptationSet should be turn to 3(refer to AMR Activation Guideline PE/BSS/APP/11438 in Reference
Documents)See also chapter AMR Engineering Studies.
amrUlHrAdaptationSet Class 3 V15
Description: Define the lines of parameter used for the adaptation mechanism.
It sets the C/I thresholds when AMR speech codecs are used on a FRchannel in UL.when AMR speech codecs are used.
Value range: [0 to3]
Object: bts
Default value: 0
Type: DPRec. value: 3
Used in: Codec mode adaptation
Eng. Rules:
0: typical radio condition
1: optimistic radio condition
2: pessimistic radio condition
3: personalize with the BSC data configuration table
The recommanded value of 0 offers a good compromise between HRpenetration and radio environment.For optimization of the table amrUlHrAdaptationSetshould be turn to 3
(refer to AMR Activation Guideline PE/BSS/APP/11438 in ReferenceDocuments)See also chapter AMR Engineering Studies.
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amrDlFrAdaptationSet Class 3 V15
Description: Define the lines of parameter used for the adaptation mechanism.
It sets the C/I thresholds when AMR speech codecs are used on a FRchannel in UL.when AMR speech codecs are used.
Value range: [0 to3]
Object: bts
Default value: 0
Type: DP
Rec. value: 3
Used in: Codec mode adaptation
Eng. Rules:
0: typical radio condition
1: optimistic radio condition
2: pessimistic radio condition
3: personalize with the BSC data configuration table
The recommanded value of 0 offers a good compromise between HRpenetration and radio environment.For optimization of the table amrDlFrAdaptationSetshould be turn to 3(refer to AMR Activation Guideline PE/BSS/APP/11438 in ReferenceDocuments)See also chapter AMR Engineering Studies.
amrDlHrAdaptationSet Class 3 V15
Description: Define the lines of parameter used for the adaptation mechanism.
It sets the C/I thresholds when AMR speech codecs are used on a FRchannel in UL.when AMR speech codecs are used.
Value range: [0 to3]
Object: bts
Default value: 0
Type: DP
Rec. value: 3
Used in: Codec mode adaptation
Eng. Rules:
0: typical radio condition
1: optimistic radio condition
2: pessimistic radio condition
3: personalize with the BSC data configuration table
The recommanded value of 0 offers a good compromise between HRpenetration and radio environment.For optimization of the table amrDlHrAdaptationSetshould be turn to 3(refer to AMR Activation Guideline PE/BSS/APP/11438 in ReferenceDocuments)See also chapter AMR Engineering Studies.
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filteredTrafficCoefficient Class 3 V15
Description: Filter coefficient taken into account in the cell load evaluation.
Value range: [0..1] step 0.001
Object: btsDefault value: 0
Type: DP
Rec. value: 0.5
Used in: AMR based on traffic
Eng. Rules: The parameter shoud be set to 1 to reach V15.1 behaviour (HR callsallocated on RxLev criterion only)
fullHRCellLoadEnd Class 3 V18
Description: This attribute defines the threshold that triggers the ending of
congestion period of AMR MaximizationValue range: [0 to 100]
Object: bts
Default value: 100
Type: DP
Rec. value: 60
Used in: Channel allocation
Eng. Rules: This value should be tuned according to the operator strategy. But incase of activation of AboT the engineering rules related tointerworking between AMR maximization and AboT shall be followed.
fullHRCellLoadStart Class 3 V18
Description: This attribute defines the threshold that triggers the beginning ofcongestion period of AMR Maximization.
Value range: [0 to 100]
Object: bts
Default value: 100
Type: DP
Rec. value: 80
Used in: Channel allocation
Eng. Rules: This value should be tuned according to the operator strategy. But incase of activation of AboT the engineering rules related tointerworking between AMR maximization and AboT shall be followed.
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sharedPDTCHratio Class 3 V18
Description: percentage of shared PDTCH TS (configured and available) taken intoaccount in the Filtered_Erlang
Value range: [0 to 100]
Object: bts
Default value: 0
Type: DP
Rec. value: 60
Used in: Channel allocation
Eng. Rules: This parameter have to be tuned according to the PDTCH configuredon the cell and the MinGprsTS parameter in case of 4 PDTCH andMinGprsTS egal to 1 sharedPDTCHratio =75%
hrCellLoadEnd Class 3 V14
Description: This attribute is used to trigger the end of AMR HR allocation in thecell.
Value range: [0 to 100]
Object: bts
Default value: 0
Type: DP
Rec. value: 40
Used in: Channel allocation
Eng. Rules: The parameter should be set to 0 to reach V15.1 behaviour (HR callsallocated on RxLev criterion only).
This value should be tuned according to the operator strategy and thenumber of TCH (preemptable PDTCH are not taken into account).
60 is a good compromise but it can be increased for cells with morethan 12 TCH.
hrCellLoadStart Class 3 V14
Description: This attribute is used to trigger the beginning of AMR HR allocation inthe cell.
Value range: [0 to 100]
Object: bts
Default value: 100
Type: DP
Rec. value: 0 for AMR FR only, different from 0 to trigger the HR allocation inthe cell.
60 for AMR based on Traffic
Used in: Channel allocation Eng. Rules: This parameter shall be different from “0” to use Half Rate allocation.
The parameter should be set to 1 to reach V15.1 behaviour (HRcalls allocated on RxLev criterion only)
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This value should be tuned according to the operator strategy and thenumber of TCH (preemptable PDTCH are not taken into account).
80 is a good compromise but it can be increased for cells with morethan 12 TCH.
TRANSCODER OBJECT
coderPoolConfiguration Class 2 V12
Description: This attribute indicates enumerated speech coding algorithmssupported by the TCU.
List of algoid [minimumCalls, powerUplink, powerDownlink]
Value range: Algoid: fullRateCoder, enhancedFullRateCoder,amrFullHalfRateCoder, ctmEnhancedFullRateCoder
MinimumCall: 0 to 65535
PowerUL: -15 to +15PowerDL: -15 to +15
Object: Transcoder
Default value: fullRateCoder, minimumCall = 1, pwrUL = 0, pwrDL = 0
enhancedFullRateCoder, minimumCalls = 1, pwrUL = 0, pwrDL = 0amrFullHalfRateCoder, minimumCalls = 1, pwrUL = 0, pwrDL = 0ctmEnhancedFullRateCoder, minimumCalls = 1, pwrUL = 0, pwrDL =0
Type: DP
Rec. value: see Engineering Rules
Used in: Channel allocation (AMR)
Cellular Telephone Text Modem (TTY)
Eng. Rules: Used for the AMR, TTY activation at the TCU level (downlink anduplink amplification level and use to define the minimum of AMRcommunications on the TCU level).
Each coded has to be present only if is is activated by the operator,FR is mandatory.
During normal operation, it dynamically reallocates the resourcesbetween the TRMs to meet traffic demand. For the EFR and FRcodecs, the archipelago capacity is 72, i.e. 216 circuits per TRM. Forthe AMR codec, the archipelago capacity is 60, i.e.180 circuits per
TRM. For the EFR+TTY codec, the archipelago capacity is 48, i.e. 144circuits per TRM.The customer can set for each enabled vocoder type (FR, EFR, AMR)a warrantied minimum number of communications. This field is calledminimumCalls and is used for the initial distribution.The TCU assigns CODEC to each available archipelago in an round-robin manner until the TCU satisfies the minimumCalls condition foreach enabled CODEC. Remaining archipelagoes are configured inorder to achieve as close as possible the CODEC ratios given byminimumCalls parameters.Let nbMinimumCalls = sum of minimumCalls of each enable CODEC.The ratio to achieve for a given CODEC is computed as follows:CODEC_rate = (minimumCalls (for this CODEC) / nbMinimumCalls).
Examples:
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For E1 network with 20% FR, 40% EFR and 40% AMR setting couldbe:
FullRateCoder, minimumCalls = 4, powerUL = 0, powerDL = 0
EnhancedFullRateCoder, minimumCalls = 8, powerUL = 0,
powerDL = 0 amrFullHalfRateCoder, minimumCalls = 8, powerUL = 0,
powerDL = 0
Remark: Whatever is the repartition between the codecs, the two parameterspowerUL and powerDL should always be set to “0“.
For T1 network, no TTY CODEC is available at the MMI. So whentheTCU receives TRM related config messages indicating for eachCODEC(FR, EFR and AMR) their minimumCalls, the equivalentEFR+TTYCODEC is enabled with a minimumCalls set to 1 by default.
CAUTION! For any TCUe3 upgrade from V14/V15 to release V16.0, TTY must beexplicitly set at MMI on G3Trans object via thecoderPoolConfiguration field.
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TRANSCEIVER OBJECT
frAMRPriority Class 2 V14
Description: defines TDMA allocation priority for AMR FR calls.
Value range: [0 to 2]
Object: Transceiver
Default value: 0
Type: DP
Rec. value: 1 for BCCH TDMA
0 for hopping TDMA
Used in: Channel allocation (AMR)
Eng. Rules: BCCH and non-hopping TDMA should be set to low priority, i.e. 1,while hopping TDMA should be set to high priority, i.e. 0.
Priority 0 is given to a high priority TDMA,Priority 1 is given to a low priority TDMA,Priority 2 disables this service on the TDMA.See also chapter Isolated Areas in AMR Monitoring.
CAUTION! Priority 2 is not recommended as it could introduce an AMRcongestion on the cell due to a barring of access to some TDMAs for AMR calls. However, that setting could be interesting in some specificcases.
hrAMRPriority Class 2 V14
Description: defines TDMA allocation priority for AMR HR calls.
Value range: [0 to 2]
Object: Transceiver
Default value: 0
Type: DP
Rec. value: 1 for BCCH TDMA
0 for hopping TDMA
Used in: Channel allocation
Eng. Rules: BCCH and non-hopping TDMA should be set to low priority, i.e. 1,
while hopping TDMA should be set to high priority, i.e. 0Priority 0 is given to a high priority TDMA,Priority 1 is given to a low priority TDMA,Priority 2 disables this service on the TDMA.See also chapter Isolated Areas in AMR Monitoring.
CAUTION! Priority 2 is not recommended as it could introduce an AMRcongestion on the cell due to a barring of access to some TDMAs for AMR calls. However, that setting could be interesting in some specificcases.
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POWER CONTROL OBJECT
Since the introduction of the ML0, there is a treshold preventing from doing Power Controlbelow a defined level when using AMR power control (refer to the amrReserved2 parameter).
The two parameters lRxLevDLP and lRxlevULP setting that threshold are defined in chapter
Power Control Parameters.
hrPowerControlTargetMode Class 3 V14
Description: AMR codec target to define the Uplink power control threshold for HR AMR calls
Value range: [4k75, 5k9, 6k7, 7k4]
Object: power controlDefault value: 7k4
Type: DP
Rec. value: 7k4
Used in: Power Control (AMR)
Eng. Rules: Power has to be decreased when call quality is very good andincreased when the quality could be better.
Even if 7k4 AMR HR is set, which corresponds to the mostconstraining Power control value, AMR Power control has shown tobe more aggressive than EFR Legacy L1m. If cell radio conditions arevery good, optimization to 6k7 HR target could be justified.Power control has to be triggered before handover for quality reason. AMRHRIntercellCodecModeThreshold<hrPowerControlTargetMode
frPowerControlTargetMode Class 3 V14
Description: AMR codec target to define the Uplink power control threshold for FR AMR calls
Value range: [4k75, 5k9, 6k7, 10k2, 12k2]
Object: power control
Default value: 12k2
Type: DP
Rec. value: 12k2
Used in: Power Control (AMR)
Eng. Rules: Power has to be decreased when call quality is very good andincreased when the quality could be better.
Even if 12k2 AMR HR is set, which corresponds to the mostconstraining Power control value, AMR Power control has shown tobe more aggressive than EFR Legacy L1m. If cell radio conditions arevery good, optimization to 10k2 FR target could be justified.Power control has to be triggered before handover for quality reason. AMRFRIntercellCodecModeThreshold<frPowerControlTargetMode
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hrPowerControlTargetModeDl Class 3 V16
Description: AMR codec target to define the downlink power control threshold for
HR AMR callsValue range: [4k75, 5k9, 6k7, 7k4]
Object: power control
Default value: 7k4
Type: DP
Rec. value: 7k4
Used in: Power Control (AMR)
Eng. Rules: Power has to be decreased when call quality is very good andincreased when the quality could be better.
Even if 7k4 AMR HR is set, which corresponds to the mostconstraining Power control value, AMR Power control has shown to
be more aggressive than EFR Legacy L1m. If cell radio conditions arevery good, optimization to 6k7 HR target could be justified.Power control has to be triggered before handover for quality reason. AMRHRIntercellCodecModeThreshold<hrPowerControlTargetModeDl
frPowerControlTargetModeDl Class 3 V16
Description: AMR codec target to define the downlink power control threshold forFR AMR calls
Value range: [4k75, 5k9, 6k7, 10k2, 12k2]
Object: power control
Default value: 12k2
Type: DP
Rec. value: 12k2
Used in: Power Control (AMR)
Eng. Rules: Power has to be decreased when call quality is very good andincreased when the quality could be better.
Even if 12k2 AMR HR is set, which corresponds to the mostconstraining Power control value, AMR Power control has shown tobe more aggressive than EFR Legacy L1m. If cell radio conditions arevery good, optimization to 10k2 FR target could be justified.Power control has to be triggered before handover for quality reason.
AMRFRIntercellCodecModeThreshold<frPowerControlTargetModeDl
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HANDOVER OBJECT
amrDirectAllocRxLevUL Class 3 V14
Description: Uplink RxLev threshold for direct AMR TCH allocation in a normal cellor in the large zone of a bizone cell (in conjunction withamrDirectAllocRxlevDL).
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handoverControl
Default value: - 80 dBm
Type: DP, Optimization
Rec. value: -80 to -79 dBm
Used in: Handover mechanisms (AMR)
Direct TCH Allocation
Eng. Rules: Direct HR allocation enables to avoid some unnecessary handoversfrom FR to HR channels. To define the value of those parameters it isnecessary to study the distribution of RxLev for the codec modedefined as the target for the HR to FR intra cell HO to avoid aimmediate come back on a FR channel after a direct HR allocation.The uplink parameter may be set considering a thresholdcorresponding to 90% of C/I values higher than 16 dB (proposedvalue, depends on the network quality). Furthermore, it has to bechecked that the RxLev value is more restrictive than the threshold togo back to the large zone to avoid an immediate comeback on thelarge zone.
See also chapter Half Rate Penetration Analysis.
amrDirectAllocRxLevDL Class 3 V14
Description: Downlink RxLev threshold for direct AMR TCH allocation in a normalcell or in the large zone of a bizone cell (in conjunction withamrDirectAllocRxlevUL).
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handoverControl
Default value: - 80 dBm
Type: DP, Optimization
Rec. value: -75 to -74 dBm
Used in: Handover mechanisms (AMR)
Direct TCH Allocation
Eng. Rules: Direct HR allocation enables to avoid some unnecessary handoversfrom FR to HR channels. To define the value of those parameters it isnecessary to study the distribution of RxLev for the codec modedefined as the target for the HR to FR intra cell HO to avoid aimmediate come back on a FR channel after a direct HR allocation.The uplink parameter may be set considering a thresholdcorresponding to 90% of C/I values higher than 16 dB (proposedvalue, depends on the network quality). Furthermore, it has to bechecked that the RxLev value is more restrictive than the threshold togo back to the large zone to avoid an immediate comeback on thelarge zone.
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See also chapter Half Rate Penetration Analysis.
amrDirectAllocIntRxLevUL Class 3 V14
Description: UplinkRxLev threshold for directAMR TCH allocation in the inner zoneof a bizone cell (in conjunction with amrDirectAllocIntRxlevDL).
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handoverControl
Default value: - 80 dBm
Type: DP, Optimization
Rec. value: -80 to -79 dBm
Used in: Handover mechanisms (AMR)
Direct TCH Allocation
Eng. Rules: see Engineering Rules of amrDirectAllocRxLevUL.
amrDirectAllocIntRxLevDL Class 3 V14
Description: Downlink RxLev threshold for directAMR TCH allocation in the innerzone of a bizone cell (in conjunction with amrDirectAllocIntRxlevUL).
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handoverControl
Default value: - 80 dBm
Type: DP, Optimization
Rec. value: -75 to -74 dBm
Used in: Handover mechanisms (AMR) Direct TCH Allocation
Eng. Rules: see Engineering Rules of amrDirectAllocRxLevUL.
Furthermore, it has to be checked that the RxLev value is morerestrictive than the threshold to go back to the large zone to avoid animmediate comeback on the large zone.amrDirecAllocIntRxLevDL≥ concentAlgoIntRxLev
amrFRIntercellCodecMThresh Class 3 V14
Description: Target codec mode to trigger an intercell AMR quality handover.
Value range: [4k75, 5k9, 6k7, 10k2, 12k2]Object: handoverControl
Default value: 6k7
Type: DP, Optimization
Rec. value: 10k2
Used in: Handover mechanisms (AMR)
Eng. Rules: The target codec mode has to be more restrictive than the one forintracell handover otherwise intracell handover will not be possiblemost of the time.
amrFRIntercellCodecMThresh<amrFRIntracellCodecMThresh .On the other hand, the codec mode threshold for intercell handover
has to be smaller than the target codec for power control.amrFRIntercellCodecMThresh< frPowerControlTargetMode
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This parameter is directly linked to AMR adaptation set and the C/Ithreshold. Intercell codec target, which directly applies on a C/I target,has to be aligned to C/I relation with RxQual. CPT could be used.C/I associated to HO intercell codec target should be between 7dBand 14 dB depending on radio environment
amrFRIntracellCodecMThresh Class 3 V14
Description: Target codec mode to trigger an intracell quality handover FR to FR
Value range: [4k75, 5k9, 6k7, 10k2, 12k2]
Object: handoverControl
Default value: 4k75
Type: DP, Optimization
Rec. value: 4k75 (AMR intracell deactivation value)
Used in: Handover mechanisms (AMR)
Eng. Rules: The target codec mode has to be less restrictive than the one forintercell handover otherwise intracell handover will not be possiblemost of the time.
amrFRIntercellCodecMThresh<amrFRIntracellCodecMThresh
amrHRIntercellCodecMThresh Class 3 V14
Description: Target codec mode to trigger an intercell quality handover from a HRchannel.
Value range: [4k75, 5k9, 6k7, 7k4]
Object: handoverControl
Default value: 5k9
Type: DP, Optimization
Rec. value: 5k9
Used in: Handover mechanisms (AMR)
Eng. Rules: The target codec mode has to be more restrictive than the one forintracell handover otherwise intracell handover will not be possiblemost of the time.
amrHRIntercellCodecMThresh< amrHRtoFRIntracellCodecMThresh .On the other hand, the codec mode threshold for intercell handoverhas to be smaller than the target codecs for power control.amrHRIntercellCodecMThresh< hrPowerControlTargetMode.
amrHRtoFRIntracellCodecMThresh Class 3 V14
Description: Target codec mode to trigger an AMR intracell quality handover from AMR HR to FR
Value range: [4k75, 5k9, 6k7, 7k4]
Object: handoverControl
Default value: 6k7
Type: DP, Optimization
Rec. value: 6k7
Used in: Handover mechanisms (AMR)
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Eng. Rules: The target codec mode has to be less restrictive than the one forintercell handover otherwise intracell handover will not be possiblemost of the time. In case same intercell and intracell codec target ischosen, intercell has the priority.
amrHRIntercellCodecMThresh <AMRHRtoFRIntracellCodecMThresh
If the operator’s strategy is to increase capacity versus quality, lowvalues for AMRHRtoFRIntracellCodecModeThreshold can be chosento delay a come back on a FR channel.Change of AMR adaptation set could also be used for HR penetrationincrease (see chapter Half Rate Maximization Analysis)
amriRxLevDLH Class 3 V14
Description: Minimum downlink level to receive to trigger an intracell handover FRto FR
Value range: [less than -110, -110 to -109, ..., -49 to -48, more than -48] dBm
Object: handoverControlDefault value: - 75 dBm
Type: DP, Optimization
Rec. value: -75 to -74 dBm
Used in: Handover mechanisms (AMR)
Eng. Rules: Since AMR coding is better than standard coding, the threshold forintracell AMR handover must be more restrictive than the one forstandard calls: amriRxLevDLH>rxLevDLIH.
amriRxLevULH Class 3 V14
Description: Minimum uplink level to receive to trigger an intracell handover FR toFR
Value range: [less than -110, -110 to -109, ... , -49 to -48, more than -48] dBm
Object: handoverControl
Default value: - 75 dBm
Type: DP, Optimization
Rec. value: -75 to -74 dBm
Used in: Handover mechanisms (AMR)
Eng. Rules: Since AMR coding is better than standard coding, the threshold for
intracell AMR handover must be more restrictive than the one forstandard calls: amriRxLevULH>rxLevULIH.
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amrReserved1 Class 3 V16
Description: Allows the activation of RATSCCH procedure for AMR FR calls
Value range: [0 to 2]
0: RATSCCH procedure enabled (default value)
1: RATSCCH procedure disabled - initial Full Rate ACS if optimistic
therefore; ACS is [12.2k, 10.2k, 6.7k, and 5.9k]
2: RATSCCH procedure disabled - initial Full Rate ACS if pessimistic
therefore; ACS is [10.2k, 6.7k, 5.9k and 4.75]
Object: handoverControl
Default value: 0
Type: DP
Rec. value: 0
Used in: AMR Legacy L1M
Eng. Rules: Before v15.1.1, in case of poor uplink radio conditions, the BTS issometimes unable to detect RATSCCH acknowledgements frommobiles. This triggers a mismatch between the AMR Codec Set usedby the mobile and the one used by the BTS. Then the BTS (or MS)cannot correctly decode the codec used by the MS (or BTS). Thissequence leads to a mute call until the next RATSCCH procedure iscorrectly executed.
A workaround for this problem of mute call consists in settingamrReserved1 to value “1” which means “RATSCCH disabled andinitial ACS optimistic” : only codec 5k9, 6k7, 10k2 and 12k2 will beused. The only drawback of the workaround is that this parameter
setting prevents the usage of 4,75 AMR FR codec, useful in case ofvery degraded radio conditions.
In v16, an improvement of the L1M has been implemented whichconsists in the BTS repeating the RATSCCH command until itreceives an acknowledgment from the mobile.
In v17, a further improvement has been implemented. It consists inimproving the robustness of the detection of the acknowledgementmessage received from the mobile : this increases the probability ofcorrectly decoding this message when it is first received.
Thanks to these 2 improvements, amrReserved1 should be set to "0"in V16 and V17.
Warning: pessimistic Codec Set 10,2 / 6,7 / 5,9 /4,75 (amRreserved1= 2) must not be chosen because it would inhibit capacity HO i.e.handover from AMR FR to AMR HR (as 12.2 cannot be used).
amrReserved2 Class 3 V12
Description: Legacy L1m procedures (Power control and Handover) or AMR L1mmechanisms (based on (n,p) voting algorithm and codec target) canbe chosen
Value range: [0 to 3]
Object: handoverControl
Default value: 0
Type: DP
Rec. value: see Engineering Rules
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Used in: AMR Legacy L1M
Eng. Rules:
amrReserved2
AMR alarm handovers
based on
AMR PowerControl
algorithm based on
0 CMR/CMC [(n,p) voting] CMR/CMC
1 RxQual CMR/CMC
2 CMR/CMC [(n,p) voting] RxQual
3 RxQual RxQual
CAUTION! A mix between AMR L1m for Power Control and Legacy L1m for AMRalarm HO is recommended at this stage (amrReserved2 = 1); however AMR activation with full AMR algorithms on HO management andPower Control has shown good performances.
nCapacityFRRequestedCodec Class 3 V14
Description: Number of 12k2 codec mode requested to trigger a capacity handover(FR to HR)
Value range: [0 to 196]
Object: handoverControl
Default value: 44
Type: DP, Optimization
Rec. value: set to 100% of pRequestedCodec, i.e. 48
Used in: Handover mechanisms (AMR)
Eng. Rules: The recommended value was chosen in order to increase capacity inreal good conditions: 100% of the requested codecs should be 12k2meaning the radio conditions are really good. If the operator’s strategyis to increase capacity vs. quality, low value fornCapacityFRRequestedCodec can be chosen.
Higher nCapacityFRRequestedCodec assures a better HR radioconditions and reduce probability intraHO ping pong.See also chapter Half Rate Settings.
nFRRequestedCodec Class 3 V14
Description: Minimum number of codecModeRequest out of pRequestedCodec inthe (n,p) voting mechanism to trigger an AMR HO while in FR mode.
Value range: [0 to 196]
Object: handoverControl
Default value: 24
Type: DP, Optimization
Rec. value: set to 50% of pRequestedCodec, i.e. 24
Used in: Handover mechanisms (AMR)
Eng. Rules:
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nHRRequestedCodec Class 3 V14
Description: Minimum number of codecModeRequest out of pRequestedCodec in
the (n,p) voting mechanism to trigger an AMR HO while in HR mode.Value range: [0 to 196]
Object: handoverControl
Default value: 34
Type: DP, Optimization
Rec. value: set to 50% of pRequestedCodec, i.e. 24
Used in: Handover mechanisms (AMR)
Eng. Rules:
pRequestedCodec Class 3 V14
Description: Number of codec mode requests to consider in the (n,p) votingdecisions.
Value range: [12 to 192] (step of 12)
Object: handoverControl
Default value: 48
Type: DP, Optimization
Rec. value: 48
Used in: Handover mechanisms (AMR)
Eng. Rules: A similar reactivity between AMR and non-AMR calls should bereached. The recommended value corresponds to the same qualityaveraging window as for standard calls in urban environment. Fieldexperimentation should give further information as for the value ofpRequestedCodec.
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ADJACENTCELLHANDOVER
hoMarginAMR Class 3 V14
Description: HO margin taken into account in an intercell quality handover for AMRcalls in order to manage the eligible cell list.
Value range: [-63 to 63] dB
Object: AdjacentCellHandover
Default value: - 2
Type: DP, Optimization
Rec. value: same as hoMarginRxQual
Used in: Handover mechanisms (AMR)
Handovers screening
Eng. Rules: In case of AMR L1mis activated (cf. amrReserved2) Handover cause AMR quality: case where access to another cell should beencouraged, provided target cell field strength is not much lower thanthe current one. If bad quality remains, there is a risk of returnhandover but there is nothing much to be done.
Depending on radio environment:
Interfered environment:
It is better to have a low C/I threshold for Quality HO (chosen via AMRadaptation set or intercell HO codec target) and have homarginAMR =hoMarginRxQual
Coverage limited environment:
It is better to have a high C/I threshold for Quality HO (chosen via AMR adaptation set or intercell HO codec target) and have hoMargin= hoMarginRxQual + 2
REPEATED DOWNLINK FACCH
enableRepeatedFacchFr Class 2 V16
Description: Enable/ disable the Repeated FACCH feature on AMR FR calls
Value range: Disable / FR 4.75 / FR 5.9 and lower / FR 6.7 and lower
Object: btsDefault value: Disable
Type: DP, Optimization
Rec. value: FR 6.7 and lower
Used in: Handover mechanisms (AMR)
Eng. Rules:
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enableRepeatedFacchHr Class 2 V16
Description: Enable/ disable the Repeated FACCH feature on AMR HR calls
Value range: Disable / FR 4.75 / FR 5.9 and lower / FR 6.7 and lower
Object: bts
Default value: Disable
Type: DP, Optimization
Rec. value: FR 6.7 and lower
Used in: Handover mechanisms (AMR)
Eng. Rules:
TX POWER OFFSET FOR SIGNALLING CHANNELS
facchPowerOffset Class 2 V16
Description: Power offset to be applied on FACCH signalling
Value range: [0 to 10] dB (with 2 dB step)
Object: bts
Default value: 0
Type: DP, Optimization
Rec. value: 6
Used in: This parameter is used to tune the power offset to be applied onFACCH re-transmission, specific FACCH messages (for firsttransmission) as well as RR and REJect frames on FACCHcorresponding to an uplink re-transmission (F bit set to 1) and UAframes corresponding to an uplink re-transmission of SABM or DISCframes (F bit set to 1).
Eng. Rules:
sacchPowerOffset Class 2 V16
Description: Power offset to be applied on SACCH signalling
Value range: [0 to 6] dB (with 2 dB step)
Object: bts
Default value: 2
Type: DP, Optimization
Rec. value: 6
Used in: This parameter is used to tune the power offset to be applied onselected SACCH frames transmission
Eng. Rules:
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sacchPowerOffsetSelection Class 2 V16
Description: CODEC selection for applying a power offset on SACCH
Value range: NULL / FR 4.75 kbps / FR 5.9 and lower / FR 6.7 and lower
Object: bts
Default value: NULL
Type: DP, Optimization
Rec. value: FR 6.7 and lower
Used in:
Eng. Rules:
AMR-HR CHANNEL ON PREEMPTED PDTCH
gprsPreemptionForHR Class 3 V17
Description: Activation of PDTCH pre-emption for HR channel
Value range: enabled/disabled
Object: bsc
Default value: disabled
Type: DP, Optimization
Rec. value: enabled
Used in: pDTCH Preemption by AMR FR or HR calls (V17) Eng. Rules: “AMR based on traffic” thresholds may need to be retuned if the
PDTCH preemption for HR channels is enabled.
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5.39. WPS - WIRELESS PRIORITY SERVICES PARAMETERS
wPSManagement Class 3 V15
Description: WPS feature is enabled or disabled
Value range: [disabled ; enabled ]
Object: bsc
Default value: disabled
Type: DP, System
Rec. value: enabled for WPS use
Used in: WPS - Wireless Priority Service
Eng. Rules: In order to enabled the new queuing management of WPS requeststhe wPSManagement flag has to be set to the value “enabled”
CAUTION! Queuing management of WPS requests can only be activated if thebscQueuingOption parameter is set to “allowed” (MSC driven) and theWPS priorities have been set properly
wPSQueueStepRotation Class 3 V15
Description: One out of the wPSQueueStepRotation value to first have anevaluation of the WPS queues in the radio resource allocator.
Value range: [1 to 10]
Object: bts
Default value: 4
Type: DP, System
Rec. value: 4
Used in: WPS - Wireless Priority Service
Eng. Rules: If the operator choose to activate WPS queuing management on itsnetwork this parameter can ensure a minimum amount of non-WPScalls (with low priorities) that can access the network even if it is verycongested
With that parameter fixed to “4”, when a radio resource become freeand there are WPS or public call requests queued, the priority is given1 out of 4 times to a WPS call request and 3 out of 4 times to a publiccall. In that case WPS calls are favored in 25% of the time.
CAUTION! The operator can choose to enabled queuing uniquely on WPS calls,hence public calls are never queued and this parameter becomeobsolete.
The Algorithm for the traffic channel allocation applies at a cell level inthe BSC, and hence wPSQueueStepRotation is a cell parameter.
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5.40. NETWORK SYNCHRONIZATION PARAMETERS
btsSMSynchroMode Class 2 V15
Description: Type of site synchronization.
Activation of the Synchronisation feature (either site synchro eithernetwork synchro features). Its value defines also the synchronizationmode (burst or time)
Value range: [normal, master, slave, gprBurstSync, gpsTimeSync,masterGpsBurstSync, masterGpsTimeSync]
Object: btsSiteManager
Default value: normal
Type: DP, Optimization
Rec. value: normal
Used in: Network Synchronization Eng. Rules:
tnOffset Class 2 V15
Description: Its value allows to specify and control TN difference between BTS incase of network synchronisation by GPS
Value range: [0..7]
Object: btsSiteManager
Default value: 0
Type: DP, Optimization
Rec. value: 0
Used in: Network Synchronization
Eng. Rules:
fnOffset Class 2 V15
Description: Its value allows to specify and control FN difference between BTS incase of network synchronisation by GPS
Value range: [0..84863]
Object: btsSiteManager
Default value: 0
Type: DP, Optimization
Rec. value: N/A
Used in: Network Synchronization
Eng. Rules:
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dARPPh1Priority Class 2 V15
Description: Its value allows specifying the priority of SAIC mobiles on the TDMA.
Value range: [high priority, low priority]
Object: transceiver
Default value: high priority
Type: DP, Optimization
Rec. value: high priority
Used in: Network Synchronization
Eng. Rules: Actually, for radio resource allocation only SDCCH requests are notdifferentiated depending if the mobile requesting is SAIC capable ornot.
masterBtsSmId Class 2 V15
Description: Gives the identity of the master BTS if the BTSSMSynchroMode isslave and remains empty if the BTS is master or normal
Value range: Master BTS id or empty
Object: btsSiteManager
Default value: Empty
Type: DP, Optimization
Rec. value: Depends on context
Used in: Network Synchronization
Eng. Rules:
baseColourCode Class 2 V7
Description: Base station Color Code assigned to a serving cell. It is broadcast onthe cell SCH and is used to distinguish cells that share the sameBCCH frequency.
The (BCC, NCC) pair forms the cell BSIC.The information is broadcast on the cell SCH.Several BCCs may be assigned to a same BTS. Hence, differentcodes can be allotted to cells that may have overlapping areas(adjacent cells).The Base Station Identity Code (BSIC) is a 6–bit code: bits 6-5-4 =NCC (PLMN color code), bits 3-2-1 = BCC (Base station color code). At cell level, the NCC bits can be used to increase BCC colorpossibilities when the NCC is not needed.
The BCC value is determining the TSC (training sequence code) ofthe cell.
Value range: [0 to 7]
Object: bts
Default value: N/A
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Type: DP, Optimization
Rec. value: N/A
Used in: Network Synchronization
Eng. Rules: Several BCCs may be assigned to cells of a same site. Hence,
different codes can be allotted to cells that may have overlappingareas (adjacent cells). See also chapter Set Up Principles of aNeighboring List and a BCC Plan
5.41. NETWORK MODE OF OPERATION PARAMETERS
gprsNetworkModeOperation Class 3 V15
Description: Flag to choose the network mode of operation.
Value Range: [0 - 2] ; 0 = NMO II , 1 = NMO I , 2 = NMO 3 (value forbidden) .
Object: bts.
Default value: 0.
Rec. value: 1.
Used in: Network Mode of Operation I support in BSS
Eng. rules: NMO 1 must be activated or deactivated at RA level: the setting mustbe consistent in all cells of a RA.
NMO1 activation is recommended when GPRS is activated on all cellsof the network: NMO1 should not be activated on a LA where somecells do not affer GPRS service.
As combined procedures are performed on PDTCH with NMO1(combined attach/detach and combined LA/RA update), it is stronglyrecommended to guaranty the continuity of GPRS service by settingminNbrGprsTs > 0.
The feature must be activated first at Core Network level and then atBSS level.
The bscDataConfig must be modified to take the value ofgprsNetworkModeOperation into account. (see [R36] for details)
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5.42. BSS CS PAGING COORDINATION PARAMETER
bssPagingCoordination Class 3 V17
Description: Activation parameter of BSS CS Paging Coordination feature
Value range: 0: disable BSS CS paging coordination/ 1: enable BSS CS pagingcoordination
Object: bts
Default value: disable BSS CS paging coordination
Type: DP, Optimization
Rec. value: see Eng. Rules
Used in: BSS CS Paging Coordination Eng. Rules: On (legacy) PCUSP board, the processing load is expected to
consume a significant proportion of the available processingcapability. In that case, the impact of the feature activation should bemonitored. See section Performance of BSS CS Paging coordination
5.43. NOVEL ADAPTIVE RECEIVER PARAMETER
adaptiveReceiver Class 2 V17Description: Activation parameter of the novel adaptive receiver
Value range: enabled/disabled
Object: transceiver
Default value: disabled
Type: DP, Optimization
Rec. value: enabled
Used in: Novel Adaptive Receiver
Eng. Rules: 1/ For cells operating under very specific radio conditions, namelyhard Hilly Terrain profiles, the Novel Adaptive Receiver structure may
possibly cause a slight performance loss compared with the initialprocessing. Therefore, it is recommended to disable the adaptivereceiver for these cells.
2/ If Rx diversity is used, best receiver performance is achieved byactivating both the Joint diversity and the Novel Adaptive Receiverfeatures
3/ Novel Adaptive Receiver does not interwork with the Extended Cellfeature. Therefore, for extended cells, the Novel Adaptive Receivermust be deactivated.
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5.44. A5/3 ENCRYPTION ALGORITHM PARAMETERS
cypherModeReject Class 1 V8
Description: Whether the CIPHER MODE REJECT messages are used (Phase IIcompliance).
Value range: true/false
Object: signallingPoint
Default value: false
Type: DP
Rec. value: true
Used in: A5/3 Encryption algorithm (V17) Eng. Rules: This parameter must be set to true for the ciphering procedures to
operate correctly between the BSS and the NSS
encrypAlgoAssComp Class 1 V8
Description: Whether the "Chosen encryption algorithm" element is used in the ASSIGN COMPLETE messages (Phase II compliance).
Value range: true/false
Object: signallingPoint
Default value: false
Type: DP
Rec. value: true
Used in: A5/3 Encryption algorithm (V17)
Eng. Rules: This parameter must be set to true for the ciphering procedures tooperate correctly between the BSS and the NSS
encrypAlgoCiphModComp Class 1 V8
Description: Whether the "Chosen encryption algorithm" element is used in theCIPHER MODE COMPLETE messages (Phase II compliance).
Value range: true/false
Object: signallingPoint
Default value: false
Type: DP
Rec. value: true
Used in: A5/3 Encryption algorithm (V17)
Eng. Rules: This parameter must be set to true for the ciphering procedures tooperate correctly between the BSS and the NSS
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encrypAlgoHoPerf Class 1 V8
Description: Whether the "Chosen encryption algorithm" element is used in theHANDOVER PERFORMED messages (Phase II compliance).
Value range: true/false
Object: signallingPoint
Default value: false
Type: DP
Rec. value: true
Used in: A5/3 Encryption algorithm (V17)
Eng. Rules: This parameter must be set to true for the ciphering procedures tooperate correctly between the BSS and the NSS
encrypAlgoHoReq Class 1 V8
Description: Whether the "Chosen encryption algorithm" element is used in theHANDOVER REQUEST ACKNOWLEDGE messages (Phase IIcompliance).
Value range: true/false
Object: signallingPoint
Default value: false
Type: DP
Rec. value: true
Used in: A5/3 Encryption algorithm (V17)
Eng. Rules: This parameter must be set to true for the ciphering procedures tooperate correctly between the BSS and the NSS
encryptionAlgorSupported Class 3 V8
Description: Type of ciphering capability supported by the BTSs of a BSS. Whenno ciphering capability is supported, users’ calls are not encrypted bythe BSS over the air interface.
Value range: [none, gsmEncryptionV1, gsmEncryptionV3FallbackNoEncryption,gsmEncryptionV3FallbackV1]
Object: bsc
Default value: none
Type: DP
Rec. value: see Eng. Rules
Used in: A5/3 Encryption algorithm (V17)
Eng. Rules: The setting of this parameter depends on the level of data integrityand security required by the network operator. A5/3 is more powerfulthan A5/1 but may slightly impact Call setup time and handover
duration.
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Notes: 1/This parameter’s class has been modified from class 0 to class 3 inv17.0.
2/This parameter’s range has been modified from [none /
gsmEncryptionV1 / gsmEncryptionV2] to [none, gsmEncryptionV1,gsmEncryptionV3FallbackNoEncryption,gsmEncryptionV3FallbackV1] in v17.0.
3/A5/2 must no longer be used in any network, as of December 2006.
layer3MsgCyphModeComp Class 1 V8
Description: Whether the "Layer 3 message" element is used in the CIPHERMODE COMPLETE messages (Phase II compliance).
Value range: true/false
Object: signallingPoint
Default value: falseType: DP
Rec. value: true
Used in: A5/3 Encryption algorithm (V17)
Eng. Rules: This parameter must be set to true for the ciphering procedures tooperate correctly between the BSS and the NSS
5.45. BTS SMART POWER MANAGEMENT PARAMETERS
smartPowerManagementConfig Class 3 V17
Description: Enable/disable the smart power management feature.
Value range: disabled/ enabled/enhanced
Object: powerControl
Default value: disabled
Type: DP
Rec. value: enhanced
see Eng. Rules
Used in: BTS Smart Power Management (V17) Eng. Rules: 1/ It is recommended to put combined BCCH and SDCCH/8 TS on the
same TDMA as BCCH.
2/ As a TRX supporting a PDTCH never switches its PA off, it isrecommended not to configure more PDTCH TS than necessary.
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smartPowerSwitchOffTimer Class 3 V17
Description: Sets the initial countdown value of the timer that must expire beforethe PA may be switched OFF.
Value range: 5 to 255 minutes in 1-minute steps
Object: powerControl
Default value: 5 minutes
Type: DP
Rec. value: 5 minutes
see Eng. Rules
Used in: BTS Smart Power Management (V17)
Eng. Rules: The smaller the switch-off timer :
• the more reactive the power management will be to theminute-by-minute changes to the call profile as the dayprogresses towards quieter moments
• the more power is likely to be saved as a result.
• but the more frequently the PA is likely to go through off/oncycles, especially at the transition from busy hour to quieterhours, thus possibly impacting its lifespan.
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5.46. ENHANCED VERY EARLY ASSIGNMENT PARAMETERS
EATrafficLoadEnd Class 3 V18
Description: Used to trigger the activation/deactivation of VEA allocation, accordingto Filtered_TCH_ratio.
Value range: 0...100 step 1
Object: bts
Default value: 100
Type: DP
Rec. value: 40
Used in: Enhanced very Early assignment Eng. Rules:
EATrafficLoadStart Class 3 V18
Description: Used to trigger the activation/deactivation of VEA allocation, accordingto Filtered_TCH_ratio.
Value range: 0...100 step 1
Object: bts
Default value: 100
Type: DP
Rec. value: 60
Used in: Enhanced very Early assignment
Eng. Rules:
VEASDCCHOverflowAllowed Class 3 V18
Description: Used to allow (or not) the SDCCH overflowing when EVEA isactivated.
Value range: Disabled (0) / Allowed(1)
Object: bts
Default value: 0Type: DP
Rec. value: 1
Used in: Enhanced very Early assignment
Eng. Rules:
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6. ENGINEERING ISSUES
6.1. GSM/GPRS TS SHARING: PRIORITY HANDLING ANDQUEUING
With GSM/GPRS TS sharing, the operator’s strategy can be of three main different kinds:
• Minimize the impact of GPRS introduction on GSM.
• Guarantee GPRS quality of service thus impacting on GSM if no resources
are added
• Find a trade-off impacting GSM as little as possible and guaranteeing GPRS
as much as possible.
The tuning of priority handling, queuing and also the use of the preemption mechanismdepends on the adopted strategy.
6.1.1 RESOURCES RESERVED FOR PRIORITY 0 ANDPREEMPTION
allocPriorityThreshold is a parameter used to reserve resources for priority 0 TCH allocation
requests. This reservation of resources decreases the capacity for incoming calls when
resources are reserved for handovers. Depending on the difference between
allocPriorityThreshold and the number of shared PDTCH, several phenomenon can happen.
IF allocPriorityThreshold ≥ shared PDTCH
THEN GPRS preemption mechanism is reserved for priority 0 TCH allocation requests
This behaviour is normal and comes from the definition of allocPriorityThreshold and the
allocation strategy that allocates in priority free TCH.
On the contrary:
IF allocPriorityThreshold ≤ Number of shared PDTCH
THEN the only free resources left for priority 0 TCH allocation request are shared
PDTCH.
• Reestablishment will not be enabled at those periods of time (no
reestablishment on shared PDTCH is allowed).
• A more frequent issue will come from GprsPreemption set to yes enabling the
PCU to NACK a preemption requested by the BSC. This phenomenon
decreases the efficiency of allocPriorityThreshold: reserved resources
considered free by the BSC might not be used to serve a TCH allocation
request when the PCU NACKs the preemption. This phenomenon will only
happen in case of heavy GPRS traffic at the same time as heavy GSM traffic.
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The table below proposes a setting of GSM/GPRS TS dynamic sharing with priority handling
with or without reestablishment (MinNbOfGprsTs is only indicative). With reestablishment, two
sets of values are sometimes proposed, one of them for less GPRS capacity.
Number of TRX allocPriorityThreshold minNbOfGprsTsNumber of shared
PDTCH
1 TRX with or without reestablishment 1 1 0
2 TRX with or without reestablishment 2 1 1
3 TRX without reestablishment 2 2 2
2 2 13 TRX with reestablishment
3 2 2
4 TRX without reestablishemnt 2 2 2
2 2 14TRX with reestablishment
3 2 2
6.1.2 GSM/GPRS TS SHARING AND QUEUING:
No queued allocation request can use the preemption mechanism to leave the queue. The
allocation request must wait until a TCH is free. Hence, a too high number of shared PDTCH
(without adding a TDMA) increases the time a queued request will stay in the queue.
A solution to decrease the length of the queue is to forbid intracell queuing (intraCellQueuing
set to disabled). The intracell handover request will be repeated later (increases the BSC
signaling load) if no resource is free but thanks to the repetition of the handover request if the
radio conditions are still bad, the shared PDTCH preemption will be allowed (not the case if
put in queue).For example on a 2 TDMA cell queuing can be done on 14 TCH TS, but in the case of a 2
TDMA cell with 3 shared PDTCH and minNbOfGprsTs = 0 the queuing can only be done on
11 TCH TS, so queued requests will leave the queue less quickly and one could see an
increase in the number of discarded requests.
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6.1.3 RESOURCES STRATEGY
MINIMIZE IMPACT OF GPRS INTRODUCTION ON GSM
• Gprspreemption is set to no
• MinNbGprsTS is set to 0
It means that all PDTCH configurated are shared by GSM and GPRS and thePCU is not
allowed to NACK the preemption requested by the BSC.Impact on queuing, impact on
preemption depending on allocPriorityThreshold value.
GUARANTEE GPRS QUALITY OF SERVICE
• GprsPreemption set to yes
• MinNumberGprsTs > 0
It means that some resources are always dedicated to GPRS and that the PCU can NACK a
pre-emption requested by the BSC.
Impact on queuing and preemption efficiency since the PCU can NACK the preemption
It might be interesting to activate HO traffic so as to enable a spatial repartition of traffic on
overlapping cells (with protection against HO ping pong): this spatial repartition of traffic will
save PDTCH channels for GPRS traffic and guarantee a constant availability of preemptable
PDTCH.
TRADE-OFF ON GSM AND GPRS
• GprsPreemption set to no
• minNumberGprsTs> 0
IMPACT ON QUEUING.
Minimum resources are guaranteed to GPRS and all the other resources can be used by GSM
calls if needed since the PCU can never NACK a preemption. It might be interesting to
activate HO traffic so as to enable a spatial repartition of traffic on overlapping cells (with
protection against HO ping pong): this spatial repartition of traffic will save PDTCH channelsfor GPRS traffic and guarantee a constant availability of preemptable PDTCH.
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6.2. MINIMUM TIME BETWEEN HANDOVER
Different cases of handovers are given, and for each, the parameter setting influence is
described.
6.2.1 MICRO-CELLULAR NETWORK
HANDOVER MICROCELL TO MICROCELL
Avoiding handover ping-pong is important but a mobile could cross a cell in 2 or 3 seconds. A
delay (bts Time Between HO configuration) should not be used in this case.
The parameter setting should be:
• timeBetweenHOConfiguration = true, because the feature may be important
for other cells in the BSS.
• bts Time Between HO configuration = minimal value, e.g. = rxLevHreqave *
rxLevHreqt * 0.48 sec
Actually, even in such configuration, the value of the delay depends on the speed of the
mobiles. If the speed is low and the mobile speed in the cell is homogeneous then the delay
can be significant and have an action on ping-pong handover. If the speed is non
homogeneous then the most “rapid-moving mobiles” must be considered for the value of the
delay, though ping-pong handovers could occur. The lower the most rapid moving mobiles’
speed, the more important the delay is”. Then bts Time Between HO configuration is a
function of the cell size and the mobile speed.
In such situation, the problem of field variation is solved:
• If the mobile speed is low then the delay will help to avoid a ping-pong
handover
• If the mobile speed is high, the averaging will not show all these variations.
HANDOVER MICROCELL TO MACROCELL
microCell means: its bts object cellType is set to microcell.macroCell means: in the microcell adjacentCellHandOver object, the cellType field
corresponding to this macrocell is set to “umbrella” whatever the value of its cellType field in
its bts object (normal cell, umbrella or microCell). In this way a microCell can be seen as an
umbrella for another microCell.
This kind of handover is only triggered on alarm cause. So, in this case the delay is not very
useful.
Let’s consider the following case:
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With a macroCell, the delay can be used for the microCell. A mobile that goes from microCell
A to macroCell B will perform a handover (on alarm cause). Then, it is worth setting a delay on
cell A to avoid a ping-pong handover (between A and C).
Therefore, this delay is beneficial for a mobile in cell C that turns into the street of cell A. The
same is true in opposite direction.
The only restriction is for a mobile coming from macro B and going to micro C. The delay has
a negative influence for the handover microA-microB. It is the same case as before.
The feature General Protection against HO ping-pong can solve this kind of problem. Forinstance, in this particular case, the parameter hoPingPongCombination should be set to
(alarm, capture) and hoPingPongTimeRejection should be set to the previous V9 value of bts
Time Between HO configuration.
HANDOVER MACROCELL TO MACROCELL
The timer is usefull for a cell intersection where there is much interference.
Let’s take as an example a handover with cause “quality” triggered from macroCell A towards
macroCell B. But just after this change of cell, a handover with cause “power budget” is
attempted. Using an appropriate delay, depending on the speed of the mobile, many ping-pong handovers may be avoided.
This is also achieved through the General Protection against HO PingPong feature (see
chapter General protection against HO ping-pong). In this particular case, the parameter
hoPingPongCombination should be set to (quality, PBGT) and hoPingPongTimeRejection
should be set to the previous V9 value of bts Time Between HO configuration. In order to
inhibit completely the ping-pong hoPingPongCombination should be set to (all, all).
macroCell B
microCell A
microCell C
macroCell B
microCell A
microCell C
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6.2.2 NON MICRO-CELLULAR NETWORK.
The solution is the use of the minimum time between handover. The value of the delay
depends on the distance between the interference point and the point where macroA and
MacroB have the same level. With the hypothesis that the following neighbor cell is far away,the value of the delay depends on the minimun speed of the mobile.
It is not really obvious to recommend a value because it is a question of interference point
position. So, before test and measurement results, the recommended value is the default
value: 16, that corresponds to 8 seconds.
There are two ways to determine the best value:
• system test: the counters show that ping-pong handovers exist. With a little
variation of the delay (bts Time Between HO configuration), it is possible to
see the influence (always with counters). So with only some steps of delay
variation the best value to avoid ping-pong handover and radio link failure canbe found.
• measurements: with mobile measurements, the point of interference and the
equivalence point can be found. Then the delay value can be deduced from
the distance between both points.
However the following “light constraints” are applied to the value of the delay:
• average time of a mobile in the cell (weighted if nedeed for each speed)
• bts Time Between HO configuration.
Those constraints could also be a way to find the best value of minimum time between
handover.
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6.3. DIRECTED RETRY HANDOVER BENEFIT
This paragraph provides theorical studies results of the benefit that Directed Retry can provide
in mono and multi-layers Networks.The Directed Retry is mainly a benefit in the case of smallcongestion zone in the network. In others cases the network is either under-dimensioned or
the queuing gives better results. Moreover, the HOTraffic feature must be favoured instead of
using Directed Retry.
6.3.1 BENEFIT OF FEATURE ON MONO-LAYER STRUCTURE
O HYPOTHESIS
• 12 macroCells with 3 TRX/cell
• Non-combined BCCH
• 22 TCH available for the 12 cells
• 9 cells with 41% use rate (i.e. 9 TCH/22) and 3 overloaded cells with 26
channels requested for 22 available (i.e. 24% of blocking rate)
• 25% of cell overlapping
WITHOUT DIRECTED RETRY
The carried capacity is:
• 9 cells * 9 TCH + 3 * 76% * 26= 140 Erlang
• the highest blocking rate is over 24%
Long duration
Large surface
Duration of
congestion
Directed Retry
CallNormal
situation
Network
under dimensioned
Long duration
Large surface
Duration of
congestion
Directed Retry
CallNormal
situation
Network
under dimensioned
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WITH DIRECTED RETRY
The added carried capacity is:
• 25% cell overlapping => 25% * (24% * 26 requests * 3) = 4,7 Erlang
• the highest blocking rate is over 18%
With Directed Retry and 25% overlapping: gain on traffic 3,3% on the whole set of 12 cells of
this example and gain on blocking rate.
6.3.2 BENEFIT OF FEATURE ON MULTI-LAYERS STRUCTURE
HYPOTHESIS
• blocking rate of 2% max on the macroCell• 3 TRX (22 TCH) with 9 TCH used / 22 (41% use rate)
• 1 TRX per μ -cell with not combined BCCH
• 10 requests for 6 TCH on the μ -cell (48% of blocking rate)
WITHOUT DIRECTED RETRY
Carried capacity of “n” μ-cell under 1 macroCell: = n μ-cell * 52% + 1 macro * 9 * 100%
For “n” μ-cell under 1 umbrella cell: number of carried Erlangs = 5,2n + 9
If n = 1, we have carried 14,2 Erlangs.
WITH DIRECTED RETRY
When the Macrocell begins to be full (the blocking rate will become low (from 2% to 3%)) then
no more calls are redirected from the µ-cell to the macro.
Capacity of microCell + macroCell: we aim to satisfy the 10 + 9 requests (i.e. 19 Erl needed):
n micro * X% * 10 + 1 macro * 9
The macro cell is able to carry: 14.9 Erlang
• 9 requests from the macroCell
• 5.9 requests from the μ-cells
Then, the macroCells keep: X% * ((n macroCell * 10) – 5.9)
WITH N = 1:
The Erlang law gives X = 87.6% (a blocking rate of 12.4%), the carried traffic is:
14.9 + 87.6% * (10-5.9) = 18.5 Erl
Gain 30% on ONE μ-cell and the highest blocking rate is over 12.4% (instead of 48%).
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WITH SEVERAL N:
microCells transfer their calls into one umbrella-cell, and with the hypothesis of our example,
the gain should be (en = enabled, dis = disabled):
As a consequence Gain(%) = f (number of µ-cells under one umbrella).
The best cells to implement directed retry are the cells that have potential problems due to a
lack of TCH resources. Directed Retry may solve the problem of load if the cell is the only one
to have this kind of problem in the close area. If the entire area is congested, almost no
improvement will be observed.
If queuing is enabled on the cell, the parameter setting of the queuing should lead to queues
of size 3 and a waiting timer of 6 seconds in the candidate cell.
Directed Retry can be also activated without queuing. See chapter Directed retry without
queuing activation for further informations.
The last value to set is the rxLev threshold used in the feature to choose a “good” neighborcell (distant mode). As the decision is taken on the basis of one measurement, a margin of a
few dBs needs to be taken to deal with multipath fading. Then, the advised value should be at
least rxLevMinCell + 3 dB.
Gain%=Erl carried DR(en)
Erl carried DR(dis)- 1 Gain%=
X(n) * (10n – 5,9) – (5,2n + 9)
5,2n + 9Gain%=
Erl carried DR(en)
Erl carried DR(dis)- 1 Gain%=
X(n) * (10n – 5,9) – (5,2n + 9)
5,2n + 9
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EXAMPLE OF POSSIBLE CONFIGURATIONS:
At BSC level:
• interBscDirectedRetry = allowed
• intraBscDirectedRetry = allowed
• modeModifyMandatory = used
• bscQueuingOption = forced
• timeBetweenHOConfiguration = true
• HOSecondBestCellConfiguration = 3
At Cell level (where directed retry is implemented):
• allocPriorityTimers = 0 0 6 0 0 0 0 0
• allocWaitThreshold = 0 0 3 0 0 0 0 0
• directedRetryModeUsed = bts
• interBscDirectedRetryFromCell = allowed
• intraBscDirectedRetryFromCell = allowed
At neighbor cell level:
• directedRetry = rxLevMinCell + 3 dB
• hoPingPongTimeRejection = 30 (= the previous V9 value of bts Time Between
HO configuration
• hoPingPongCombination = (DirectedRetry , all) or for instance (DirectedRetry,
PBGT)
At cell level for neighbor cells:
• bts Time Between HO configuration = 1 (V12 update, the parameter changes
its possible vallues)
• allocPriorityThreshold = 3
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6.4. CONCENTRIC CELLS
The concentric cell feature has been introduced from the BSS version V9.1. The main
principle is to define two zones in a cell: inner (or small) and outer (or large) zone. BCCH andsignaling channels use TMDAs of outer zone.
This feature enables the system to have two separate zones within the same cell using
different TDMAs and giving the operator flexibility to have separate frequency hopping
systems. Therefore, concentric cell zones give better spectral efficiency through mobility
management between zones and being able to increase inner zone frequency reuse.
For a good understanding of this feature, please refer to the chapter
Concentric/DualCoupling/DualBand Cell Handover , and the associated Functional Notes [R10] Concentric cell improvements (CM888/TF889) and [R11] FN for stepped coupling.
Expected Network Impacts:
• Radio Quality Improvement: C/I and RxQual improvement and an overall RF
and HO drops improvement
• Slight increase in intracell HO drops, inherent to concentric cell interzone
traffic management.
Outerzone
(large zone)Innerzone
(small zone)
BCCH and
signalling
channels
traffic
channels
Outerzone
(large zone)Innerzone
(small zone)
BCCH and
signalling
channels
traffic
channels
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6.4.1 CONCENTRIC CELL PARAMETER DEFINITION
As shown on the figure above, the definition of inner zone coverage depends mainly on
concentAlgoExtRxLev; concentAlgoIntRxLev and biZonePowerOffset+hysteresis parameters.
Main related parameters to the concentric cell feature are listed below:
Parameter Description
concentric cell enable the concentric cell feature on the cell (also used for dualband / dualcoupling)
concentAlgoExtRxLev level threshold used for TCH Direct Allocation in the inner zone or to trigger an interzone HO from theouter to the inner zone
concentAlgoExtRxLevUL * Uplink level threshold used for TCH Direct Allocation in the inner zone or to trigger an interzone HOfrom the outer to the inner zone
concentAlgoIntRxLev level threshold used to trigger an interzone HO from th inner to the outer zone
concentAlgoIntRxLevUL * Uplink level threshold used to trigger an interzone HO from th inner to the outer zone
biZonePowerOffset offset used to simulate the power difference between TDMAs of the inner and the outer zone (powerdifference either due to power emission, coupling losses or propagation losses)
zone Tx power max reduction set the power difference between the two zones of a concentric/dualaband/dualcoupling cell
concentAlgoExtMsRange distance threshold used for TCH Direct Allocation in the inner zone or to trigger an interzone HO fromthe outer to the inner zone (not used for dualband functionality)
concentAlgoIntMsRange distance threshold used to trigger an interzone HO from th inner to the outer zone
biZonePowerOffset(n) offset used to reflect the difference of propagation between the two zones of an adjacent cell in case ofhandover toward the inner zone
rxLevMinCell(n) minimum signal strength level received by MS for being granted access to a neighbor cell
*From V18 new parameters are added in order to secure uplink path during direct allocation
and interzone HO
CONCENTALGOEXTRXLEV
The concentAlgoExtRxLev value can be set depending on how TRXs capacity in the cell is
shared between the inner and outer zone. The following figure shows CPT cumulative
distribution of RxLev uplink and downlink of a cell before concentric cell activation.
concentAlgoExtRxLev may be deduced from the downlink RxLev distribution which representssamples of communications in function of the strength level.
concentAlgoIntRxLev(inner to outer
threshold)
concentAlgoExtRxLev(outer to inter threshold)
biZonePowerOffset
+ hysteresis Margin
concentAlgoIntRxLev(inner to outer
threshold)
concentAlgoExtRxLev(outer to inter threshold)
biZonePowerOffset
+ hysteresis Margin
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On the figure above we can see that only 10% of the traffic is handled with a level under -86dBm. So if the traffic size of inner zone (% of TS in the inner zone with regard to total number
of TS in the cell) is 90% of the outer zone, it means that 90% of downlink Rxlev sample may
be inside of inner zone, and 10% is outside. A downlink RxLev value L90, L75 or L50 should
then correpsond to 90%, 75% or 50% of traffic on the inner zone.
concentAlgoExtRxLev = LXX (use of the CPT tool)
BIZONEPOWEROFFSET (HANDOVERCONTROL OBJECT)
biZonePowerOffset is used to simulate the power offset between TDMAs of the inner and the
outer zone.
CONCENTRIC CELL CASE
In this case biZonePowerOffset simulates the power difference between the two zones
introduced by zone Tx power max reduction of the inner zone.
• zoneTxPowerMaxReduction(outer) = 0
• zoneTxPowerMaxReduction(inner) = 0, best value tested (see
chapter zone Tx power max reduction)
biZonePowerOffset = zone Tx power max reduction(inner)
DUALCOUPLING CELL CASE
In this case biZonePowerOffset simulates the power difference between the two zones
introduced by coupling losses.
• zone Tx power max reduction(outer)=0
• zone Tx power max reduction(inner)=3 simulates the D/H2D
configuration
• zone Tx power max reduction(inner)=4 simulates the H2D/H4D
configuration
biZonePowerOffset = zone Tx power max reduction(inner)
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Note: DLU Attenuation should be NULL and replaced by zone Tx power max reduction as
explained in the parameter description: zone Tx power max reduction and concentric cell.
DUALBAND CELL CASE
In this case biZonePowerOffset simulates the power difference between the two zones
introduced by propagation losses. It should then be set according to the band used on the cell.
biZonePowerOffset = +3 dB (dualband: main band= 850 or 900 MHz)
biZonePowerOffset = -3 dB (dualband: main band= 1800 or 1900 MHz)
CONCENTALGOINTRXLEV
To avoid ping-pong interzone HO, a hysterisis margin is recommended. The level threshold to
trigger an interzone HO from the inner to the outer zone could be calculated as follow:
concentAlgoIntRxLev = concentAlgoExtRxLev - Hysteresis Margin -
biZonePowerOffset
where Hysteresis Margin = 4 dB is recommended.
BIZONEPOWEROFFSET(N) (ADJACENTCELLHANDOVER OBJECT)
biZonePowerOffset(n) in adjacentCellHandover object reflects the difference of propagation
between the two zones of an adjacent cell in case of handover toward the inner zone. When
attempting an HO directly to the inner zone of an adjacent cell EXP2xx(n) = hoMarginxx(n) +
biZonePowerOffset (n) > 0 shall be respected. So in order to avoid HO in sequence afterincoming HO into inner zone, it’s necessary to respect the following relation:
biZonePowerOffset (n) = concentAlgoExtRxLev(n) - rxLevMinCell(n)
rxLevMinCell(n)
concentAlgo
ExtRxLev(n)
cellA cellB
rxLevMinCell(n)
concentAlgo
ExtRxLev(n)
cellA cellB
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6.4.2 CONCENTRIC CELL FIELD EXPERIENCE
RADIO QUALITY IMPROVEMENT
Inner zone isolation-capacity trade-off is found in concentric cell. The smaller the inner zone
coverage, the better inner zone isolation is found but less traffic, which takes profit of higher
inner zone fractional reuse pattern, is carried. Concentric cell success on improving KPI
performances is based on this balance.
On one hand reducing inner zone coverage:
• provides better isolation of inner zone interferences by keeping only the calls
with very good RxLev to enter the inner zone
• allows deploying a more constraining inner zone frequency plan (or a
consequent inner zone radio quality improvement) and reducing 3107 dropssince inter HO are done in better radio conditions.
On the other hand, one of the inherent risks of using this approach is to block on the outer
zone while resource availability remains on the inner zone. Even though inner zone blocking is
not customer perceived (calls can overflow onto the outer zone radios if available TCH
resources), a compromise exists between the traffic distribution between the zones, and the
improvement in KPI. Therefore, additional tuning of the concentAlgoExt/IntRxLev thresholds
may be necessary on certain sites to set an appropriate threshold for transitioning from and to
the inner zone.
INNER-OUTER ZONE CAPACITY TRADE-OFF
It is recommended having more than 1 TDMA on outer zone since it allows redundancy in
case BCCH TDMA is lost, and also because TDMAs carrying SDCCH channels must also be
on the outer zone. Furthemore, it is advised to have higher capacity in the outer than in the
inner zone, because it minimizes the probability that outer zone is blocked, which would cause
a capacity cell reduction even if inner zone TS are available.
60%-40% outer-inner capacity is recommended.
CONGESTION TARGET FOR HO TRAFFIC
Capacity is shared between inner and outer zone depending on TDMAs allocated in eachzone. Outer zone congestion targets should be updated to take into account reduction in terms
of TDMAs in outer zone. Inner zone is not considered for congestion since no congestion for
the user is found when all TS are occupied.
SDCCH DIMENSIONING
It should be noted that with Concentric Cell SDCCH channels cannot be configured in the
inner zone and all the SDCCH channels will have to be re-mapped to the outer zone radios.
All the sectors prior to implementation of Concentric Cell in the concerned BSCs must follow
Nortel’s recommended rule of spreading the SDCCH channels amongst different radios and
therefore had to be re-mapped carefully such that SDCCH congestion is not encountered.
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CONCENTRIC CELL PARAMETER TUNING
ZONE TX POWER MAX REDUCTION
This parameter is used to reduce the output power of the BTS on the inner zone TDMAs to
improve inner zone isolation. Simulations show it is preferred to keep the inner zone reduction
at 0 dB and rely on power control efficiency to reduce power level. Like this, power control is
always capable to power up to maximum power to save worst call who received punctual
interferences. Inner zone power reduction has not brought any significant KPI improvement
when it has been tested on field trials.
Simplified power control simulation results are shown on graph below. 250 meters of cell
radius in 1900MHz (150 meters for inner zone coverage which corresponds to 40% inner zone
capacity for a uniform traffic distribution) and perfect power control to attempt DL RxLev target
of -86 dBm are considered.
If BTS inner zone TDMA are not attenuated at all (0dB), 14,8 dBm mean BTS TX DL power
would be found while if 8 dB output power would be attenuated, mean BTS TX DL Power
would become 13,4 dBm. Therefore the impact on interference and isolation on innerzone is
very limited and it is preferred to leave power control the possibility to power up rather than
induce an external attenuation
CONCENTALGOEXT/INTRXLEV
It is recommended to set concentAlgoExtRxLev using CPT tool. DL RxLev number of samples
repartition found in CPT is a good indicator on how traffic load is spread around the cell.
concentAlgoExtRxLev threshold can be defined to match inner/outer zone capacity repartition.
It is recommended to define concentAlgoExtRxLev instead of concentAlgoIntRxLev throughCPT methodology. Like this, inner zone RxLev samples are slightly underestimated (signal
BTS Power and RxLev evolution depending on
BTSoffset parameter
0
5
10
15
20
25
30
35
40
45
50
0,00 0,05 0,10 0,15 0,20 0,25
Cell Range [km]
B T S P o
w e r [ d B m ]
-104,0
-102,0
-100,0
-98,0
-96,0
-94,0
-92,0
-90,0
-88,0
-86,0
-84,0
R x L e v [ d B m ]
BTSPower(Offsetpower0)
BTSPower(Offsetpower8dB)
InnerZone Coverage (40%)
RxLev(Offsetpower0)
RxLev(Offsetpower8dB)
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level from concentAlgoExtRxLev and concentAlgoIntRxLev could also be allocated in inner
zone) and a margin to pack the inner zone TDMAs is left.
concentAlgoExt/IntRxLev impact on inner/outer traffic load has not shown to be very sensible
to their value. Same mean values have been spread all over clusters in field trials and they
have required little tuning to avoid outer zone blocking and KPI improvements.
CONCENTALGOEXT/INTMSRANGE
concentAlgoExtMsRange and concentAlgoIntMsRange could be used to reinforce or to
complement inner and outer inter zone handovers using concentAlgoExt/IntRxLev.
The calculated distance between the MS and the BTS is based on timing advance (TA), which
has an accuracy of ± 3 bits (corresponding to more than 1,5 km), due to the shift of
synchronization of some MSs. Thus, this parameter is not very useful in urban areas where
the cell size is relatively small and due to the multipath effect, the MS to BS distance is not
very accurate. However this parameter could be used in rural areas or suburban areas.
BIZONEPOWEROFFSET IN DUALBAND CELLS
6 dB Rxlev DL level difference has been found between 900 MHz and 1800 MHz calls due to
propagation losses in field trials. When a call who is allocated in the outer zone (900MHz) is
inter handover to inner zone (1800MHz), 6 dB level loss is expected to be found due to
propagation loss.
Since biZonePowerOffset is taken into account in power budget handovers, there is a trade-off
between biZonePowerOffset value and number of power budgets of inner zone calls. Having a
biZonePowerOffset too big can reduce significantly power budget of inner cell provoking calls
to be dragged to inner zone cell edge because of overestimating own BCCH level of the
outerzone.
6 dB presents a good trade-off and it is the value recommended.
INTRACELL HANDOVER DROP SLIGHT INCREASE
On activation of concentric cell feature, interzone handovers get triggered based on signal
level within the same cell, increasing the probability of dropped calls. The key to successful
implementation of Concentric Cell is to reduce the other drop call components such as T3103
and RLT Drops.
HYSTERISIS MARGIN DEFINITION
The inner to outer Hysteresis Margin corresponds to the delta between concentAlgoIntRxLev
and concAlgoExtRxLev minus zone TX power maximum reduction. The delta should be
adequate so that the captured traffic in the inner zone (which is the key to spectral efficiency)
is not immediately allocated back to outer zone via a ping-pong handover. A big hysterisis
zone helps to contain the users in the inner zone and keeps this zone packed in order to avoid
losing capacity and interzone HO, therefore it reduces T3107 drops.
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L1M REACTIVITY
It is not recommended to increase L1m reactivity when concentric cell is used for HO
decisions since it can increase significantly interzone HO with the consequent increase on
T3107 drops. An average of 8 frames is recommended.
CONCENTRIC CELL IMPACT ON AMR HR PENETRATION
Interzone handover from inner to outer zone is considered as a quality handover. Therefore,
even though an AMR HR call was on going in the inner zone, after a quality inner to outer
interzone handover AMR FR is allocated in outer zone.
Depending on AMR FR to HR and HR to FR thresholds, this interzone handovers can cause
an increase of intracell HO from HR to FR (inner to outer zone) and immediately from FR to
HR (in the outer zone), reducing AMR HR penetration on the cell.
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6.5. IMPACT OF DTX ON AVERAGING
The RxLev_Full measured on a dedicated channel is the arithmetic mean of 104 received time
slots power, excepted in the case of DTX: then it is the arithmetic mean of only 12 receivedtime slots power.
A study was done to compare the difference (RxLev_Full - RxLev_Sub). It was based on
10800 measurements from a single network, characterized by a great proportion of microcells
and a high RxLev mean value.
The following array presents the results of this study. We considered the difference
(RxLev_Full - RxLev_Sub), without averaging (1 measurement), and then with averaging on 2,
3, 4 and 8 measurements.
number of values for averaging 1 2 3 4 8
mean value of RxLev_Full - RxLev_Sub (dB) - 0,15 - 0,15 - 0,15 - 0,15 - 0,15
standard deviation (dB) 2,12 1,48 1,19 1,03 0,72
The results show that, for an averaging on 4 measurements, the standard deviation is only 1
dB. This is insignificant enough to consider that we can run simulations, and analyze the
measurements with one of the two levels, if we don’t know which one is used.
Moreover, the measurement processing used for the neighbor cells is close to the process
used in the case of DTX: it is the arithmetic mean of about (104/N) received time slots power,
where N is the number of neighbor cells declared, between 1 and 32.
If 6 < N < 12, which is often the case, the two processes are quite comparable. 8 to 10 for
neighbor; standard deviation on RxLev_Sub can be extended to RxLev(i).
This means that the RxLev_NCell(i) measured on a neighbor cell, is close to the RxLev that
would be measured if it was the current cell.
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6.6. BEST NEIGHBOUR CELLS STABILITY
The parameter CellDeletionCount is used to keep a neighbor cell eligible, even if a few
measurements are lost.
A study was done with a measurement file of 2 hours, without handover. Each time one of the
6 best neighbor cells disappeared, the time before it re-appeared, called absent_time, was
calculated. 420 absent_times were found; that follow this distribution:
absent_time (s) % % cumulate
0,66 1,18 1,18
1,32 1,89 3,07
1,98 4,01 7,08
2,64 5,42 12,5
3,3 1,89 14,39
3,96 4,01 18,4
4,62 4,48 22,88
5,28 1,65 24,53
5,94 1,42 25,94
6 to 11 8,02 33,96
> 11 66,04 100
Note: absent_time values are multiples of 0,66 seconds.
For instance, for the recommended value 5 and according to these measurements, in 12,5
percent of the cases the neighbor cell concerned is accessible after 2,64 seconds, in 87,5
percent, it is still missing.
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6.7. TCH ALLOCATION GENERAL RULES
When no queuing is allowed, as no request can be treated by the BSC at the same time, there
are two kinds of TCH allocation requests:
• priority 0: the request is acknowledged if there is at least one free TCH
• priority > 0: the request is acknowledged if there is at least
allocPriorityThreshold + 1 free TCHs
If allocPriorityThreshold equals 0, all the requests are treated in the same manner.
If queuing is in OMC driven mode (run by the BSC), incoming handovers cannot be queued.
The highest priority must be given to incoming handovers.
The queuing plays a part when, there is not enough TCH resources. When traffic increases to
a blocking state, the queuing has no impact on the total ratio of TCH allocation success: the
more call attempts that are acknowledged, the more incoming handovers are refused.
The queuing is prefered when all TCH resources are busy during a short time; it cannot
replace a resource.
Please refer to chapter TCH Allocation Management.
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6.8. GENERAL RADIO FREQUENCY RULES
1) In dB, the path loss slope with distance, decreases as 1/D. This means that the received
signal variation, in dB/m, is greater at the close vicinity of the base station and decreases withthe distance. It depends directly on the propagation exponent.
2) We can assume stationnarity (during some seconds) of the median path loss in dB,
assumption is more and more valid since the MS is far from its antenna cell, close to the
handover area.
3) Shadowing is due to obstruction of the signal paths, created by obstacles. It is known that
these obstacles create log_normal variations of the received signal, ie the received power at a
distance, expressed in dBm, fluctuates as a gaussian random variables.
4) The shadowing “depth” is strongly linked to the position of the mobile as compared with the
dominant building, and as a consequence, that shadowing decorrelates when different
buildings are involved. With a building mean width d = 30m, shadowing can be considered
completely decorrelated.
5) The higher the mobile speed, the smaller the impact of the shadowing on the average
signal.
6) The higher the average window size is, the smaller the impact of the shadowing on the
average signal is.
7) The variance of the signal due to the Rayleigh fading, depends on the speed of the mobile
and of the frequency in use. About 30 to 50 wavelengths must be spanned to ”filter out” the
fading variations with a residual error less than 1 dB. If the number of samples is equal to N =
10 the mean matches the true local mean to within 2 dB at 90%.
8) Whatever the mobile speed, from a certain window size the increase of the size does not
modify the average Rayleigh standard deviation. From 8 to 16 samples, even at a very low
speed the gain is inferior than 0.5 dB.
9) The dispersion of two MRC combined Rayleigh is decreased by more than 1.5 dB for an
MRC order 2, compared to a single channel. It means that diversity reception can help
average out the fading faster than a single channel, i.e the local mean is tracked faster. If d >
20 l, an efficient 2 order space diversity has the same effect as multiplying the speed by 3 to 4.
10) .With Rayleigh fading, it is known that the mean in dB of samples in Watts is greater than
the mean in dB of samples in dBm. The limit is 2.5 dB, that means that the RXLEV tends to beartificially 2.5 dB higher for the uplink than for the downlink.
11) The RxLev_Full as measured on a dedicated channel is the arithmetic mean of 104
received time slots power, in the case of DTX, only 12 times.
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6.9. DIFFERENCE BETWEEN UPLINK AND DOWNLINK LEVELS
At the BTS, averages are performed from measurements made in Watts before . On the
contrary, some MS make measurements in dBm and then, perform their averages. In Rayleighenvironment, the first method of calculating can be up to 2.51 dB higher than the second
method.
This comes from the fact that in Rayleigh fading environment, the information goes through
several paths (at least two) between the BTS and the MS. At the antenna, according to the
phase of the signal, the different path can add up or not. This varies with time and it can vary
from complete cancellation (hole) or, on the contrary, perfect adding. This effect is called
multipath fading.
This effect implies that received levels follow a Gaussian law and its mean has an exponential
density. The evaluation of the bias between the mean of the decibels and the mean in
decibels is then:
10 .Log (e) ξ = 2.51 dB
This comes from the following expression that relates the mean of the natural logarithm of an
exponential random variable of mean one to the Euler constant (ξ):
∑ Ln (x) exp (- x) dx = ξ = 0,57721
The 10.Log (e) factor just accounts for the base 10 log.
In this normalised example:
• averaged mean of Watt samples converted in dB = 0 = BTS
calculation
• averaged mean of dB samples = 2.51 dB = MS calculation
So, the maximum difference between the two ways of calculating the average power is 2.51
dB. The uplink value will be the higher.
However, here, the hypothesis of the Rayleigh fading lead to deal with two paths, if there are
many paths, the value of the correction needs to be decreased.
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6.10. EFFECTS OF SMS-CELL BROADCAST USE ON“NOOFBLOCKSFORACCESSGRANT”
If the SMS-CB feature is activated, SMS-CB messages are carried on the CBCH, a subchannel of the SDCCH. The TDMA model mapping of the SDCCH becomes SDCCH-CBCH/8,
and the CBCH occurs from frame number 8 to frame number 11 of the SDCCH multiframe.
If noOfBlocksForAccessGrant = 0, then a paging message can be transmitted on frames
number 8 and 9.
Then, if the SDCCH is transmitted on the Time Slot 0 of another TDMA than the one carrying
the BCCH, a collision will occur.
In that case, the mobile must choose between an incoming call and a SMS-CB, by selecting
one kind of data to listen.
Setting noOfBlocksForAccessGrant to a value superior or equal to 1 avoids this problem: only
AGCH can be transmitted on that block.
This rule
NoOfBlocksForAccessGrant > 1
is a recommendation requirement on not combined CBCH.
In that case, on the frame number 8 and 9, the MS can just receive an Immediate Assignment.
If an Immediate Assigment message is transmitted, it means that the mobile has sent a
channel request, and is not in idle mode any more. Therefore, the MS won’t listen to theCBCH channel.
Please also refer to chapter Consequences of NoOfBlocksForAccessGrant.
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6.11. IMPACT OF THE AVERAGING ON THE HANDOVERS
The following study applies only to L1M V1.
Simulations have been performed with NMC Engineering tools to determine the impact of
some BSS parameters values in terms of handover reactivity. The simulations were performed
from real RF measurements and network field configuration.
Four Simulations have been performed with the following sets of parameters:
runHandOver Hreqt
1 2 2
2 2 1
3 1 2
4 1 1
The results are spread on three items:
• Global statistics: number of HO in each configuration.
• Study of reactivity: impact of parameters on reactivity.
• Reactivity vs ping-pong.
6.11.1 GLOBAL STATISTICS
HO CAUSE PBGT AND QUALITY DL
For each of the four sets of parameters presented, the amount of HO on quality DL and PBGT
is the same.
HO CAUSE LEVEL DL
The modification of the parameters has a low impact on the total amount of HO detected on
Level DL cause.
HO CAUSE CAPTURE
For each of the four sets of parameters used, the total amount of handovers is the same. The
difference is not significant because microCellCaptureTimer * runHandover is kept constant.
CONCLUSION
The simulations show that:
• Setting Hreqt=1 instead of 2 has a very low impact on the total
amount of handovers (less than 4%)
• Same conclusion for runHandover=1 instead of 2
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6.11.2 STUDY OF REACTIVITY
The second item of the study is to show the impact of runHandover and Hreqt on the
reactivity: how much sooner do the handovers occurs ?
RUNHANDOVER=1
Field simulations have shown that such a value of runHandOver has low impact on reactivity
compared to runHandOver=2. The increase of reactivity due to runHandOver=1 is less than or
equal to 0,5 second.
HREQT=1
The influence of Hreqt on reactivity is much more decisive, 15% are being advanced by setting
Hreqt=1 (hoMargin unchanged). Two reasons can explain this:• After the beginning of communication on a new TCH, L1M waits for a fixed
delay before a new HO: HreqAve*Hreqt*0,48 sec. Among the HO performed
within 8 seconds1 after a callsetup or another HO, 45% are advanced thanks
to Hreqt=1.This can be very helpful if, for example, the callsetup was initiated
on a bad cell, because of Reselection failure.
• Reducing the length of the weighted averaging window can make the
variations of the weighted average less smooth. This effect is observed for
only 2% of the HO. For this particular case, it is still possible to tune hoMargin.
The low impact of this measure can be explained as follows.
HREQT=2
That configuration does not always double the size of the averaging window.
Example: runHandover=1, HreqAve=4, Hreqt=2. Every runHandover, the L1M calculates a
weighted average based on the last average stored and the sliding average of the moment.
These two averages can have up to 3 measures in common.
CONCLUSION
• Hreqt=1 is an efficient way to increase reactivity for 15% of the HO.
• Among the HO performed within 8 seconds (after call setup or another HO),
45% are performed sooner with Hreqt=1 (in average 1,6 sec sooner).
• Among the HO performed long after the beginning of the communication, only
2% are performed sooner because Hreqt=1 makes the weighted average less
smooth.It is still possible to tune hoMargin.
• runHandOver=1 can not advance HO of more than 0,5 sec.
6.11.3 PING PONG VS REACTIVITY
Among the 15% of HOs that were advanced for more than 1 second by Hreqt=1, simulations
show that without changing hoMargin, no supplementary ping pong handover was observed.
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6.12. IMPACT OF CALL RE-ESTABLISHMENT ON THE NETWORK
6.12.1 IMPACT ON CAPACITY
The Call-Reestablishment feature has a big impact on the MSC resources occupation. Without
Call Re-establishment, T3109 (BSC timer) is usually set to a small value (>
Min(radioLinkTimeOut, 4*rlf1+4) which is given in SACCH block) in order to free resources as
soon as possible after a radio link failure (see t3109 recommanded value).
Setting a large value to T3109 for Call Re-establishment leads the MSC to freeze the resource
for the call waiting for a Channel Request from the MS. Therefore, if the MS is unable to select
a destination cell, or if the radio link failure is due to coverage limits (border cells), the
resource is frozen for nothing.
Call Re-establishment should not be activated on border cells, or the impact could be reduced
by decreasing the value of T3109 on these specific locations.
On the other hand, on Sunday network, tests have been performed showing that, after the Call
Re-establishment activation, nearly no trunk erlangs have been noticed by Mandarin Radio
Engineers.
Please also refer to chapter Call reestablishment procedure (Cr).
6.12.2 IMPACT ON CALL DROPS
The Call Re-establishment doesn’t decrease the amount of call drops from a counter point of
view, even if it improves the quality of service. The subscriber is satisfied to get back hiscommunication after few seconds instead of totally loosing it, but this procedure is launched
after a call drop detection, counted by the system.
Moreover, the Call Re-establishment can increase in some cases the overall number of call
drops. For instance, when a temporary destination cell is selected by the MS without providing
a long term solution:
The operator can deduce that Call Re-establishment has a bad influence on call drops
amount. Actually, the communication lasts longer, maybe allowing the subscriber to end his
call properly.
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6.13. MINIMUM COUPLING LOSS (MCL)
The Minimum Coupling Loss is the minimal value recommended in the link budget to avoid
problems in the transmission.
The MCL is calculated to avoid the two major problems which may occur, broadband noise
and blocking. It is mainly used in a micro-cellular and pico-cellular environment where MSs are
likely to operate in the vicinity of the BTS antennas.
6.13.1 BROADBAND NOISE
The Broadband noise takes into account all kinds of noise which disturb the BTS and the MSs.
According to GSM Recommendation 05.05, the MS must keep its output noise level 60 dB
below its power level (for a frequency spacing of 600 kHz). On the BTS part, the received
noise level must be at least 9 dB below its sensitivity.
The decoupling value is the difference between the maximum output noise level and the
maximum received noise level.
Considering a S2000L BTS and a GSM 1800 MS, values are the following in both uplink and
downlink:
UPLINK DOWNLINK
Transmitter Max Power A (dBm) 30 33
Output Noise Level Margin B (dB) 60 60
Max Output Noise Level C (dBm) = A - B -30 -27
Receiver Sensitivity D (dBm) -104 -101
Input Noise Level Margin E (dB) 9 9
Max Input Noise Level F (dBm) -113 -110
Noise Decoupling Value G (dB) = C - F 83 83
As we can notice in the results of the upper table, the values are the same for uplink and
downlink.
6.13.2 BLOCKING
The Blocking takes into account the interferences generated by the others MSs.
The BTS can handle, for the 600 kHz adjacent frequency, a received signal strength 35 dB
below the maximum received power of the current frequency. Over this value, a phenomenon
of flashing occurs.
The flashing phenomenon consists in a BTS or a MS which would emit at a very high value,
and would by this way interfere the communication of the others MSs. The effect of this
phenomenon is the deterioration of the wanted signal.
The decoupling value is the difference between the maximum output power and the maximum
received signal level.
Considering an S2000L BTS and a GSM 1800 MS, values are the following in both uplink and
downlink:
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UPLINK DOWNLINK
Transmitter Max Power A (dBm) 30 33
Max Received Signal Strength B (dB) -35 -44
Decoupling Value C (dB) = A - B 65 77
Moreover, in the blocking case, the probability of collision of the burst between MS and BTS
must be taken into account.
In the blocking case, the downlink is more affected than the uplink. However, this difference is
not very important (except if the study is done at the frequency of the interferer) since the
decoupling value for the Broadband noise is more restricting than the decoupling values for
blocking.
6.13.3 HOW TO IMPROVE THE MCL
If the MCL is not respected, the communications will be deteriorated and will have a poor
quality. To improve that quality (or decrease the probability of such problems to occur), its to
say respect the MCL, solutions consist in increasing the frequency spacing between the cell
and the neighboring cells and/or ensure a better decoupling between BTS antenna and MS.
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6.14. MICROCELL BENEFITS
Microcell is a spectral efficiency feature. This algorithm enables us to shift traffic irrespective of
the traffic condition based on downlink signal strength and mobile speed. This gives flexibilityin filling the micro layer first before loading the macro/umbrella layer.
Different gain can be obtained depending on microcell deployment strategy, e.g. capacity gain,
indoor coverage gain, voice quality improvement… Several microcell strategies should be
considered:
6.14.1 FREQUENCY SUPER REUSE
In a good isolated micro layer network, a separated frequency plan can be allocated for
microcells with a few frequencies for BCCH and high fractional reuse pattern increasing
spectral efficiency increasing capacity keeping same QoS.
6.14.2 TRAFFIC HOMOGENIZATION
One of the most critical frequency plan challenge is high configuration sites. Indeed they are
difficult to control since they create interferences with no way to minimize the collisions.
Declaring cells as microcell allows shifting traffic and homogenizes site configurations having
a cleaner frequency plan.
Benefits of this feature could be realized by rearranging the DRX counts and carrying more
traffic in the micro layer traffic channels and simultaneously carrying lesser traffic and DRXs in
the umbrella layer thus giving room to reduce spectrum from the Macro layer which is moreinterfered. This allows a cleaner and more manageable frequency plan avoiding high
configurations
6.14.3 RADIO CONDITIONS IMPROVEMENT
Cells with low antenna height are normally better isolated by environment protection. If these
cells are declared as micro, shifted traffic generates less interference creating a cleaner
frequency plan. Less interferences are traduced in a better voice quality or feasibility to
increase fractional reuse pattern keeping same voice quality.
On one hand microcell deployment is a good strategy to improve radio conditions., thus the
operator can whether increase fractional reuse and therefore increase network capacity or
increase voice quality, keeping same fractional reuse pattern.
On the other hand, microcell deployment is a good strategy to improve indoor coverage in a
specific area, such as business or travelling hot spots.
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6.14.4 MICROCELL FIELD EXPERIENCE
MICROCELL IMPACT ON AMR HR PENETRATION
Microcell deployment reduces AMR HR penetration. Indeed, in microcell PBGT HO are
disabled, and yet when PBGT HO are activated we assume to be on the best serving cell, so
in the best C/I conditions. This effect has an impact on AMR HR penetration as good C/I
conditions are required for Half Rate, which slightly reduces its penetration.
LRXLEVDLH AND LRXLEVULH DEFINITION
When a micro to umbrella relationship is declared between two different cells, it is important to
have a close look on Call Trace / Call Path Trace in order to determine lRxlevDLH and
lRxlevULH. Depending on micro and macro cell layer design, it has been found some caseswhere a call, which is allocated in the micro cell and getting close to the micro cell limits,
receives an RxLev signal from the macro cell which is even lower than micro cell RxLev
signal. Since Power Budget is deactivated when micro-umbrella relationship is declared, this
phenomenon makes that rescue RxLev handover rarely executed and calls are dragged until
quality handover is triggered, which could happen too late to save the call, increasing the call
drop rate.
In this case, it is recommended to analyze with CT/CPT the level of microcell and the
neighboring macrocell level received to declare the suitable value where level handover can
safely occur.
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6.15. INTERFERENCE CANCELLATION USAGE
All the field results so far lead to the following conclusion:
• 50% for interferer cancel algo usage is a very good compromise between
interference cancellation and pure thermal noise sensitivity: it does not
degrade the sensitivity and gives almost the same interference cancellation
performance as 100% with 5dB cancellation loss in the range I/N=0 to 20dB.
For instance, it will be very useful in a medium traffic area, where the isolated
interferers will be very well removed with no coverage degradation.
• When pure thermal noise sensitivity is not an issue (not coverage but
interference limited situation), 100% achieves the best interference
cancellation.
• In an actual network, some particular synchronization patterns may exhibit a
performance loss when interference cancellation is applied although there aremany interferers. However, on the overall network a typical net gain of about
1dB will be obtained with 50% (remember that 1dB is 26% increased capacity
if the network capacity is limited by the uplink interferers).
The following guidelines should be applied: when the interference cancellation is available,
50% is an excellent compromise between coverage and interference cancellation. When
speed is the main problem (high speed train coverage) 100% is the best value.
Improvement appears when there is an update from a previous v15.1.1 BSS to a later one.
Indeed, before V15.1.1, gain of interferer cancellation was not optimal in case of low Rxlev.
Since V15.1.1 interferer cancellation algorithm has been improved to take into account all
range value for parameter “interferer cancel algo usage” for all RxLev range.
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6.16. STREET CORNER ENVIRONMENT
6.16.1 DESCRIPTION
Especially in micro-cellular network, where the antennas are under the roof, the level received
by the mobile can dramatically fluctuate. Ping pong handovers and call drop were experienced
in this type of environment, and led to bad quality of service as well as a significant increase in
signalling traffic. One of the toughest issues to solve in a micro cellular network is street corner
environment.
Two cases must be distinguished:
• The first one deals with mobile moving straight the cross road. In the case, the
handover toward the cell A must be avoided.
• Mobiles turning at the cross road is the second case. The handover from cell
B to A must be performed quickly before the field of the current cell dropped
under a critical value, leading a call drop.
cell A
cell B
cell A
cell B
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6.16.2 CASE A: MOBILE MOVING STRAIGHT
In the case of a mobile moving straight the cross road, a handover for PBGT may be
processed from cell B to cell A. Once the cross is passed, the mobile is handed again over thecell B. This ping pong handover shall be avoided as useless handover leads to voice quality
degradation.
The parameter rxLevDLPBGT allows to cope with that case. Actually, if the signal received by
the mobile from the serving cell exceeds this threshold, then the handovers with power-budget
criteria are prevented.
cell A
cell B
cell A
cell B
RxLev
Time
rxLevDLPBGT
cell A
cell B
RxLev
Time
rxLevDLPBGT
cell A
cell B
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6.16.3 CASE B: MOBILE TURNING AT THE CROSS ROAD
In a microcell environment, the size of cells is very small (40 to 400 meters). The overlapping
margin between cells is not very important. Moreover, a fast moving mobile may cover a fewhundred meters during the handover process (in the worst configuration, the duration time of a
handover can be more than 1.5 s). The overlapping margin can be insufficient to prevent the
field of the current cell from dropping under a critical value before mobile locks on the next cell
(with standard parameters values). In such environment, reactivity is essential, handovers
have to be performed as quickly as possible.
The problem is solved by the combination of the following features:
• Early Handover decision (see chapter Early HandOver Decision)
• Protection against runHandOver = 1: in a microcell environment reactivity is
essential (see chapter Protection against RunHandover=1).
• Max rxLev for PBGT: the problem of handover toward cell A when mobile
goes straight forward is solved by a negative hoMargin for PBGT that can be
set in order to help handover when mobile turns (see chapter MaximumRxLev for Power Budget)
cell A
cell B
cell A
cell B
RxLev
Time
cell A
cell B
RxLev
Time
cell A
cell B
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6.17. SYNCHRONIZED HO VERSUS NOT SYNCHRONIZED HO
6.17.1 INTRODUCTION
Some tests have been carried in order to compare the timing HO of the three kinds of
handovers. No interBSC handovers were performed as synchronized handovers are only
available for intraBSC HO.
The test plan was the following:
Intra BSC / Intra BTS HO
• Not synchronized HO from Cell A to Cell B (UL & DL)
• Synchronized HO from Cell A to Cell B (UL & DL)
• Pre–synchronized HO from Cell A to Cell B (UL & DL) with different values of
the PresynchTimingAdvance parameter.
Intra BSC / Inter BTS HO
• Not synchronized HO from Cell A to Cell B (UL & DL)
• Pre–synchronized HO from Cell A to Cell B (UL & DL) with different
• values of the PresynchTimingAdvance parameter.
6.17.2 OMC-R PARAMETER SETTINGS
It has to be noted that ECU was enabled on both Cell A and Cell B. ECU may have an
influence on UL measurements.
SYNCHRONIZED HO
Parameters Cell A Cell B
adjacentCellHO object
CellId Cell B Id Cell A Id
Synchronized Synchronized Synchronized
hoMargin -24 -24
NOT SYNCHRONIZED HO
Parameters Cell A Cell B
adjacentCellHO object
CellId Cell B Id Cell A Id
Synchronized Not Synchronized Not Synchronized
hoMargin -24 -24
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PRE-SYNCHRONIZED HO
Parameters Cell A Cell B
AdjacentCellHO objectCellId Cell B Id Cell A Id
Synchronized Pre sync HO with timing advance Pre sync HO with timing advance
PreSynchroTA
0
1
2
3
4
5
6
30
0
1
2
3
4
5
6
30
hoMargin -24 -24
Note: the value - 1 for the PreSynchroTA parameter stands for a TA value equal to 1 (554 m).
6.17.3 TIMING HO
PROCEDURE
The test procedure was based on tone recordings. A specific tone is sent for UL (resp. DL)
from the MS (resp. the land line). The tone is a pattern of a 3 second 500 Hz signal and a 3
second 700 Hz signal. The use of 2 contiguous signal is needed because problems of no
signal emission occurred when a one frequency tone signal is used.
The tone was sent for a minute. An HO occurred approximately every 5,7 seconds. Each
record has a serial of about 10 HOs.
All the averages shown in that study are calculated from these 10 values.
SYNCHRONIZED HO RESULTS
COLLECTED DATA
HO # Muting (ms) Silence (ms) Demuting (ms) Total (ms)
1 26 55 28 109
2 14 60 21 95
3 21 57 15 93
4 31 61 14 106
5 14 52 15 81
6 26 50 19 95
7 70 26 19 115
8 66 28 26 120
9 43 25 46 114
10 49 10 38 97
11 29 18 36 83
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The (1,2,3,4,5,6) HO # are HOs which occurred in the 500 Hz frequency part of the tone.
The (7,8,9,10,11) HO # are HOs which occurred in the 700 Hz frequency part of the tone.
STATISTICS & COMMENTS
• HOs in 500 Hz frequency tone part
Muting (ms) Silence (ms) Demuting (ms) Total (ms)
22 56 19 97
14 50 14 78
31 61 28 120
7 4 5 16
• HOs in 700 Hz frequency tone part
Muting (ms) Silence (ms) Demuting (ms) Total (ms)
51 21 33 106
29 10 19 58
70 28 46 144
17 7 11 35
For both frequencies, the average timing HO of a synchronized HO is the same, around 100
ms. The interesting part is that the time repartition between the muting, silence and demuting
phases are not the same.
The muting and demuting phases appear to be dependent on the frequency. However, the
muting and demuting algorithms at the TCB are not dependent on the frequency. Actually, the
ECU activation on both cells may be responsible of this dependence. It seems that the ECU
algorithm at the BTS makes the muting and demuting dependent on frequency.
When ECU is enabled, it seems that the muting and demuting slopes are correlated to the
frequency.
NOT SYNCHRONIZED HO RESULTS
COLLECTED DATA
HO # Muting (ms) Silence (ms) Demuting (ms) Total (ms)
1 25 133 4 162
2 47 113 84 244
3 40 114 43 197
4 20 137 47 204
5 24 131 43 198
6 48 93 33 174
7 18 123 46 187
8 38 143 38 219
9 25 109 44 178
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The (1,2,3,4,5,6,7,8,9) HO # are HOs which occurred in the 500 Hz tone part of the signal.
STATISTICS & COMMENTS
Muting (ms) Silence (ms) Demuting (ms) Total (ms)32 122 42 196
18 93 4 162
48 143 84 244
12 16 20 25
The Not Synchronized Timing HO is around 200 ms. Unfortunately, the high standard
deviation value does not allow any conclusion on this specific duration.
Note: Not synchronized HO procedure
Here is a brief example of the L3 radio protocol of such a HO:
• DL: HANDOVER COMMAND
• UL: HANDOVER ACCESS
• DL: PHYSICAL INFO
• DL: PHYSICAL INFO
• DL: PHYSICAL INFO
• UL: HANDOVER COMPLETE
The TA is indicated from the target BTS to the MS in the PHYSICAL INFO.
We can make the statement that the not synchronized HO is twice slower than the
synchronous one. It is mainly due to the PHYSICAL INFO expectation of the MS.
PRE-SYNCHRONIZED HO RESULTS
PRINCIPLE
The pre-synchronized handover procedure is exactly the same than the synchronized
handover procedure.
After the Handover Access bursts which shall be sent with a TA value of 0 the MS shall use a
TA as specified in the HO Command by the old BTS, or a default value of 1, if the old BTS did
not provide a TA value.
The BSC indicates in the HO Command message that the handover will be pre-synchronized
and, if needed, the predefined Timing Advance to be used by the MS in the new cell
(preSynchroTimingAdvance parameter).
COLLECTED DATA
The real TA of both cells is 0 (but fluctuant sometimes to a TA value of 1). The aim of these
tests is to evaluate the voice quality loss and/or gain of a pre-synchronized HO versus the
preSynchroTimingAdvance value set at the OMC-R.
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STATISTICS
PreSynchroTA (kms) 0 -1 1 2 3 4 5 6 30
Average (ms) 120 122 89 105 436 739 756 684 705
Minimum 108 94 65 89 79 524 606 532 533
Maximum 129 144 126 105 958 971 970 947 945
Standard Deviation 8 18 17 13 334 172 133 132 133
COMMENTS
It has to be understood that the pre-synchronized handover has been implemented in order to
fasten the handover procedure in a dense (size <2kms) environment or in a railway / highway
optimization. As the setting of the preSynchroTimingAdvance parameter is not that easy (on-
field measurements and TA distributions after HO per pair of cells), the behavior of the MS for
a wrong (2 or 3 steps of TA) and a very wrong (greater than 3 steps of TA) TA value is very
interesting for the network optimization.
Actually, regarding the timing HO results versus different preSynchroTimingAdvance values, it
seems that the MS is able to re-synchronize with the BTS. The drawback is that the speech
cut duration and the handover procedure are highly increased (up to 1 second).
CONCLUSION
Regarding the results of that study, it clearly appears that the synchronized handover is the
faster type of handover. It is available for intraBTS or intracell handovers, or if the Network
Synchronisation is activated. In this case, if the two cells are synchronized by GPS, and they
have the same TNOffset, handover can be synchronized, even if the two cells are not in the
same BSC.
However, the pre-synchronized handover has shown very good results (almost the same
performance than the synchronized one) if the TA after HO is previously known.
Therefore, pre-synchronized HO is a good solution to fasten handover and to decrease (up to
80 ms) the speech cut duration. The fields of appliance should be dense (cell size < 2kms),
railway or highway environment to ensure that the distance after handover is known.
Not synchronized handover still remains the only setting for InterBSC handovers.
Anyway, the UL results of that memo show that the speech cut duration is less than 250 ms.
This value allows to keep a pretty good voice quality during handovers.
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6.18. BTS SENSITIVITY
6.18.1 DEFINITION OF SENSITIVITY
In this chapter, sensitivity figures are clarified, knowing that such notions as static, dynamic,
guaranteed and typical may often lead to confusion.
The sensitivity is completely defined in the GSM recommendation 05.05. §6.2., as the input
level for which all performances in terms of frame erasure, bit error or residual error rates are
met. A reference table specifies rates varying according to the type of GSM channel (traffic,
signaling) and the type of propagation channel (static, urban, rural, hilly terrain).
Sensitivity is measured at antenna connector, and by definition this figure takes into account
all RF elements losses included in BTS cabinet, as shown on the following figure:
Base Station
Rx diversity gain
Duplexor
Combiner
Power Amplifier
Antenna connector
Antenna
Common
Cable losses
Rx sensivity
Base Station
Rx diversity gain
Duplexor
Combiner
Power Amplifier
Antenna connector
Antenna
Common
Cable losses
Rx sensivity
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6.18.2 STATIC AND DYNAMIC SENSITIVITY
Static sensitivity could be viewed as the level at which sensitivity performance is met in the
static channel mode. Yet, the static mode is only one of the propagation models among others
specified in the GSM Recs. reference table. The static mode is the most favorable case(excepted a few cases of fully not correlated antennas and 2-branchs diversity). In terms of
radio, it can be understood that for a given signal input, less communication errors are
expected within a configuration where there are no multi-path effects at all.
6.18.3 TYPICAL / GUARANTEED SENSITIVITY
Typical sensitivity is 1dB better than the worst-case used, mainly due to the variation in
performance of the RF front end and not the variation in the DRX module. The variation in
performance of DRXs on a per cell basis is therefore very tightly controlled. For more details,
please refer to the BTS Engineering Rules ([R47] to [R56]).
6.18.4 SPACE DIVERSITY GAINS
FADING CORRELATION
One major parameter to assess space diversity gain is the fading correlation, which depends
on many factors, such as radio environment (angular distribution of reflectors), antenna
configuration (spacing between antennas) and position of the mobile respective to the BTS.
The sensitivity for fully correlated antennas and not correlated antennas (correlation 0.2) can
be viewed respectively as the worst case and quasi-best case situations. In reality, the
correlation figure lies ‘somewhere between’ both figures, depending on the factors mentioned
previously.
To assess correlation values applicable to engineering is not an easy task. Yet, it can be
observed that by taking 10 wavelengths of antenna separation (recommended distance is 20),
the correlation factor is as low as 0.2 for an angular spread of only 1 degree .These results
give us enough confidence to interpolate the sensitivity at values near the not correlated case,
in such environments as built-up areas (urban, suburban), as well as hilly terrain, which offer a
multiplicity of reflectors. However, this appears less obvious for open area environments,
typically flat rural, for which we will assume a more conservative correlation factor.
BRANCH SENSITIVITY
Diversity gains are calculated by doing the difference between “with” and “without” 2 antennas
figures. Then diversity gains vary a lot with correlation and propagation channels. Yet, it can
be observed that after rounding figures, the overall sensitivity + diversity figure stays relatively
constant, independently of the configuration. The trend is a cumulated figure of -113 dBm for
the S8000 without enhanced coverage option, and -115 dBm for the S8000 with enhanced
coverage option.
This observation partly justifies the uniformity of the diversity gain of 5 dB for the S8000. It
must be stressed that this artifice is only meant to provide separate figures for sensitivity and
diversity gain, which are still distinguished when discussing link budgets
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6.18.5 CROSS-POLARIZATION ANTENNA USE
The use of cross-polarization antenna has followed a growing trend, due to the flexibility
offered in terms of site installation (two antenna packaged into one, offering diversity gain and
coupling 2 TRXs on a single antenna without hybrid coupling).
Cross polar antenna is characterized by:
• 2RF ports for one antenna
• slant polarized transmission.
Hence use of cross polar antennas implies:
• simplification of the coupling stage.
• radio link performances modification.
• diversity of polarization.
SIMPLIFICATION OF COUPLING STAGES
It should be understood that with the same number of antennas as for spatial diversity
crosspolar antennas provide 2 times more RF ports. This means that on one feeder, the
number of supported DRX is divided by two, and the size of the coupling stage too.
RADIO LINK PERFORMANCES
Radio link performances are affected by the transmission over slanted polarization:
measurement reports indicate performances of crosspolar antennas compared to vertical
antenna are lower:
• in urban area of 1dB in 900 MHz and 2dB in 1800 MHz.
• in flat rural area of 3dB in 900 MHz and 1800 MHz.
Note: performances of crosspolar antennas are strongly dependent on environment, and
mainly on reflectors and scatterers: the more they are, the better the performances.
For link budget purposes, crosspolar antennas recommended typical losses are:
• in all environment, 1.5dB in 900 MHz and 1800 MHz.
• in flat open area, 3dB in 900 MHz and 1800 MHz.
POLARIZATION DIVERSITY
Polarization diversity is obtained by processing the two signals coming from the two branches
of one crosspolar antenna. Polarization diversity is estimated after measurements of signal
decorrelation between the two diversity receiving branches of one crosspolar.
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LINK BUDGET FIGURES
Proposed link budget figures for crosspolar antenna use are summarized in the table below:
all environments
900 MHz & 1800 MHz
flat rural, flat open
900 MHz & 1800 MHz
radio link performances (DL & UL) -1.5dB -3dB
diversity gain +4dB (5dB)* +4dB (5dB)*
(*) Crosspolar antennas offer as diversity solution:
• polarization diversity (4dB gain) when 1 crosspolar antenna is used.
• spatial diversity(5dB gain) with 2 crosspolar antennas.
6.18.6 CIRCULAR POLARIZATION AND CROSSPOLAR ANTENNASThis system, Nortel patented, combines two types of advantages:
• the crosspolar antenna benefit of the 2 antennas connectors within one
antenna chassis.
• the robustness of circular polarization against depolarization effect and mobile
positioning.
This system relies on a single 3dB-90° dephaser-hybrid coupler located at the bottom of the
crosspolar antenna feeding the two ports of the crosspolar antenna with exactly the same
feeder length. The system scheme is shown below:
BTS with
polarization
diversity
BTS with
space
diversity
BTS with
polarization
diversity
BTS with
polarization
diversity
BTS with
space
diversity
BTS with
space
diversity
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In term of radio figures, the benefits of the crosspolar antenna use combined with the 3dB-
coupler are:
• the radio transmission is no more affected by the slanted polarization due to
the transmission of the whole signal over a circular polarized wave. Whatever
the position, the mobile receives all the power
• the combining stages are divided by 2
• the diversity gain is:
4dB with 1 crosspolar antenna the polarization diversity gain
5dB with 2 crosspolar antenna the space diversity gain
Recommended figures for this system are
all environments 900 MHz & 1800 MHz
diversity gain polarization diversity
space diversity
+4dB
+5dB
radio link performances
(UL and DL)0dB
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6.19. SDCCH DIMENSIONING AND TDMA PRIORITIES
The aim of this chapter is to define engineering rules associated to SDCCH dimensioning and
TDMA priorities .
6.19.1 SDCCH DIMENSIONING
An SDCCH assignment is provided when one of the following Layer 3 message is received:
• CM Service Request (includes IMSI attach)
• Paging Response
• IMSI Detach
• Location Update
So the number of these messages has to be taken into account in the dimensioning of the
SDCCH channels. Some rules are defined here below.
PARASITE SDCCH ALLOCATION
The level of noise can provide a parasite SDCCH allocation, the BTS seems to receive an
RACH and allocates an SDCCH channel. In this case the SDCCH is assigned for a short
duration (free after T3101 (3 sec by default)). The parasite SDCCH assignment depends of
the BCCH TDMA model.
BTS GEOGRAPHICAL POSITION IN THE LAC
The location update frequency must also be considered for the evaluation of the blocking rate
ratio for SDCCH. For BTS located at the border of a Location Area, a lot of location updates
are performed. Then, the signaling traffic is very high. In this case (as for area with a high
SMS traffic), the number of SDCCH channels must be quite high. Therefore, the blocking rate
ratio to consider for SDCCH must be lower than the-one for TCH.
Thus, a table can be established for the blocking rates to consider, depending on the load of
the network and the kind of signaling.
SDCCH Blocking rateTCH
Blocking rate Middle LAC LAC border
Normal load 2 % 0.1 % 0.1 %
Very loaded 5 % 0.1 % 0.1 %
DOUBLE SDCCH ALLOCATION
The double SDCCH allocation occurs when a second RACH is sent by the mobile before the
Immediate Assignment message of the first RACH is received.
The double allocation issue depends on the numberOfSlotsSpreadTrans value.
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ACTIVATION OF SMS-CB
The SMS-CB is multiplexed with the SDCCH. So the activation of the SMS-CB reduces the
number of SDCCH sub-channels and so the signaling capacity of the BTS. For example:
• SDCCH/4 + SMS-CB => 3 SDCCH available (combined case)
• SDCCH/8 + SMS-CB => 7 SDCCH available (not combined case)
TDMA Model Capacity (erlang)
SDCCH/4 0.439
SDCCH/3 0.194
SDCCH/7 1.579
SDCCH/8 2.057
So the activation of the SMS-CB has a great impact on the signaling capacity of cell (see also
chapter SMS-Cell Broadcast)
Note: in case of SMS-CB, the SDCCH TS number has to be lower than 4 (< 4)
SUBSCRIBERS MOBILITIES
In a high mobility area (rural, highway) a none negligible number of the RACH are requested
for Location Updates. The total number of RACH is then higher than in a low mobility area, it is
then better to increase the number of SDCCH channels.
In a very high mobility area (high speed train) the number of Location Area are generally
reduced in order to avoid a BSS signaling overload due to the LA update. Moreover the TCH
allocation has to be as fast as possible in order to avoid dropped calls set-up. So for the cellswhich are dedicated to the coverage of very high mobility area only, (e.g. cells which cover
only the high speed train railways and not surrounding roads or villages) it is better to reduce
the SDCCH channels number. If the cell is at the boundary of a location area the SDCCH
channels have to be set according to the Location Area update load.
NUMBER OF NETWORKS
The SIM card can contain the Id of only 4 forbidden networks, i.e if there are more than four
networks in a country a mobile can attempted a Location Update on other networks (->
Location Reject). So wherever there are more than four competitors in the same frequency
band it is recommended to increase the number of SDCCH channels.
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6.19.2 TDMA PRIORITIES
It is possible to allocate “priorities” to TDMA frames. Each TDMA has two priorities, each
serving a different purpose :
- the “TRX/TDMA mapping priority”, represented by the parameter priority (transceiver
object)
- the “PCM allocation priority”, represented by the parameter trafficPCMallocationPriority
(transceiver object)
TRX/TDMA MAPPING PRIORITY (PARAMETER : PRIORITY)
This priority defines the order with which the BTS allocates the available hardware resources(the transceivers) to the TDMA frames. In practice, if due to a hardware failure, there are fewer
TRX than TDMA, then only the TDMAs of higher priority will be mapped onto a TRX.
The parameter is called priority (transceiver object).
Among the set of TDMA frames attached to a cell, it is mandatory for the one carrying the
BCCH to have the highest priority allocated and to be the only one to have that priority.
For the TDMA carrying SDCCH channels, that priority should be the second highest priority,
i.e. not as high as the BCCH priority.
For the TDMA carrying only TCH channels that priority should be the lowest.
The generic rule to set the TRX/TDMA mapping priorities is the following :
BCCH TDMA : priority = 0
SDCCH TDMA : priority = 1
TCH TDMA : priority = 2
The typical values for priority of each TDMA model is defined in detail in the Radio Interface
Engineering Rules ([R58]).
PCM ALLOCATION PRIORITY (PARAMETER :TRAFFICPCMALLOCATIONPRIORITY)
The parameter trafficPCMAllocationPriority (transceiver object) defines the priority level of a
TDMA frame for mapping onto a PCM on the A-bis interface. In case of failure of one or more
Abis PCMs, TDMAs of highest such priorities are allocated DS0 on the remaining Abis PCM
links before TDMAs of lower priority.
The engineering rule associated to this parameter will depend on the strategy the operator
wants to use for the corresponding site.
The default engineering rule is to give the lowest priority (255) to the TDMA supporting the
BCCH, because the BCCH is conveyed on a LAPD TS, which is always present. So the BCCHsignalling and the SDCCH signalling is never lost. As the TDMA supporting the BCCH has
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fewer traffic channels than other TDMA, it makes sense to save these other TDMA before
saving the BCCH TDMA.
However, one can privilege:
• the traffic in one of the sectors: for example on a site linked by two PCMs if acell is considered as more important by the operator (strategic coverage), one
can give to the TDMAs of that cell a higher priority than those of the other cell.
Thus, during a PCM failure, those TDMA will be re-configured in priority on the
left PCM.
• circuit traffic instead of packet data traffic, by setting a higher priority for
TDMAs having only TCH compared to TDMA that have also pDTCH
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6.20. ENGINEERING GUIDELINES FOR EXCEPTIONAL EVENTS
This chapter is intended to provide guidelines on how to prepare Nortel GSM networks for
“exceptional events” from an engineering perspective. An exceptional event, as described inthis document, is a temporary event which is known in advance and which will generate an
exceptional high traffic load on the network. Nortel’s estimation is that it is economically not
justifiable to dimension a GSM network for these special events. Commonly, a GSM network
is dimensioned to carry the traffic of the busy hour. The actions proposed in this document are
intended to optimize the behaviour of the network during an exceptional event. The document
covers recommended actions on the NSS and on the BSS. On the NSS, the document
describes a set of recommended verifications that Nortel encourages the operator to do in
order to optimize the DMS behaviour. In addition a set of recommended office parameter
settings on the MSC is given with the aim of optimizing the behaviour of the BSC. On the BSS
side, this document presents the list of strongly recommended verifications and a set of
parameters values to be applied for any wide area special event. Nortel recommends that the
normal parameter setting should be reconfigured after the exceptional event.
On the NSS side, the document is applicable to GSM09, GSM10, GSM11 and GSM12. It is
assumed that all required patches on NSS and BSS are applied. Apart from the paragraphs on
CM, LPP and NSS recommendations in Chapter 4.31.3.1, most of the NSS recommendations
can also easily be applied on non-Nortel NSS equipment.
As signalling is the bottleneck during a high load situation on the BSS, the guiding idea here is
to reduce as much as possible unnecessary signalling during the exceptional event. Nortel’s
estimation is that this should improve the behaviour of the BSC.
The control of this situation is done by various verifications and parameter modifications. Theproposal is organised in 4 main levels:
• Prerequisite
• Basic tuning of parameters
• Overload configuration change
• Other parameter modification
6.20.1 BSS PREREQUISITE
CHECKS
SANITY CHECKS
Should be done at least one month before the foreseen event :
• Verification of the state of the different BSC: no BSC boards should be in a
faulty state
• Recommended values are applied
• Dimensioning rules are respected
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NETWORK:
Each BSC is fully operational and a switchover should be done, LapD load balancing over
TMU, LapD loadsharing, Location Area (LA) sizing,, TCH congestion (this is particularly
important in case of concentric cell use), Call Drop rate, HandOver failure rate (andneighbouring reciprocity).
CHECKS CORRELATED WITH THE SPECIAL EVENT
The Nortel Recommendation is that these checks be done a few hours before the special
event.
LIMITATION OF THE OAM ACTIVITIES
The Operation, Administration and Maintenance shall be minimum. So:
• all Call Traces and Call Path Traces shall be stopped/discarded
• Observations should be limited; temporization for permanent observation
should be set to at least 30 minutes
• Freeze of the network operation: No reparenting activity or NRP should be
performed during the critical period
Moreover, no modification of the network during the special event (such as command files,
OMC commands, …) shall be done.
LIMITATION OF THE SIGNALIZATION TOWARDS THE BSC
• Periodic location updates should be limited on the BSS side (recommended
value for timerPeriodicUpdateMS = 60)
• Operator advertising using SMS should be avoided
• If a degradation of the QoS is acceptable during the corresponding critical
period:
Paging repetition at NSS side should be reduced / suppressed,
Notification of voice mail through SMS should be limited / deactivated
Authentication procedures should be limited / deactivated at NSS level
Ciphering should be limited at NSS level
6.20.2 BSS: SUGGESTIONS FOR PARAMETERS TO BE MODIFIEDFOR THE SPECIAL EVENT
It is suggested that the following parameters be modified before the special event and set
back to the previous value afterwards (when the amount of traffic is back to a ”normal” level):
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These parameters are split into 3 categories.
• The modification of parameters of the 1st category does not lead to any
service interruption. These modifications may be done very quickly and a fewhours before the event.
• Parameters of the 2 nd category are only applied if it can be done without
service interruption (refer to chapter ALGORITHM PARAMETERS).
• Modification of parameters of the 3 rd category is optional and only applicable
on networks in which queuing is already activated. It requires a quite long
preparation and should be decided at least three months before the special
event. It does not lead to service interruption.
Parameters to modify:
• abisSpy = “not in progress”
• unknownCellWarning = “disabled”• interBscDirectedRetry = “not allowed”
• intraBscDirectedRetry = “not allowed”
• Multipaging timer on Abis interface = 200 ms
• maxNumberRetransmission = 1
• bscCapacityLoadReduction dedicated overload mechanism for BSC3000 exist
(see chapter BSC3000 Overload Management)
6.20.3 NSS LEVEL
DMS PREPARATION
Note: the recommendations in this Chapter should also be followed after the exceptional
event.
COMPUTING MODULE (CM)
The Computing Module (CM) of the DMS is protected by a highly efficient overload
mechanism. This mechanism allows the DMS to stand a significant overload.
In order to maintain the craftsperson’s capability to access the DMS in the expected overload
situation, it is suggested that verification is made to ensure that at least the 2 MAP terminalsas well as the ETAS modems are declared as guaranteed background task for the CPU. This
is done by setting for these devices in table TERMDEV the GUAR field to Y. A maximum of 5
devices can be declared in this way. Refer to NTP 411-3001-451 Customer Service Data
Schema Vol 3.
LINK PERIPHERAL PROCESSOR (LPP)
The behaviour of the LPP under heavy traffic conditions can be improved by optimizing the
allocation of BSSAP instances to LIU7s. It should be checked that the following
recommendations are followed.
Context
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Table GSMSSI defines the subsystem instances of the BSSAP local subsystem. These
instances reside on an LIU7 and serve SCCP Class 2 connections between the BSS and the
DMS-MSC.
Table GSMSSI allows the customer to associate BSSAP instances with LIU7s.
BSSAP instances are used only for A-interface messaging. They can be datafilled on any LIU7
in the MSC. Also, there is no restriction that an A-interface LIU7 must have a BSSAP datafilled
against it. However, datafilling the BSSAPs in a non-optimal manner can negatively impact
the DMS-MSC’s performance under heavy messaging conditions.
Further information about table GSMSSI and the BSSAP instances can be obtained in The
CCS7 Application Guide, NTP #411-2231-310. This document includes a datafill example for
GSMSSI.
Recommendations
The recommendation is that all customers apply the following guidelines:
• BSSAP instances in table GSMSSI should only be defined against LIU7s
which have an inservice link to a BSC.
• Each A-interface linkset should at least have one BSSAP instance assigned to
it. The remaining instances (total of 32) should be spread out among the
remaining A-interface LIU7s. Priority should be given to the highest traffic
linksets.
SS7 LINK
Underprovisioned SS7 links can result in link congestion, which potentially inhibit mobile call
processing. It is therefore recommended to audit the link provisioning in the network before thespecial event. During the busy hour the mean link occupancy should not exceed 40%. The
expected subscriber growth in the network has to be taken into account. This check should be
done about 4 months before the special event in order to allow potential HW extensions.
LAC DATAFILL
The Location Area Code (LAC) is a configurable parameter on the BSS and on the NSS (table
LAC). If the values are not the same, Mobile location updates on the MSC will fail. This will
result in all mobiles to repeat the locationupdate attempt. The resulting high signaling load can
decrease stability of the LPP due to the increased signaling traffic. It is therefore highly
recommended to verify that the LAC values on BSS and NSS match up before the specialevent.
BSC PROTECTION
Reduction of the signaling load on the BSC optimizes its behavior in a high traffic situation.
This chapter proposes actions in the NSS, which will help to decrease the signaling load on
the BSC.
SMS VOICEMAIL NOTIFICATION
Most of the GSM networks use voicemail notification via SMS. SMS traffic is real-time cost
intensive on the BSC processors. Furthermore, in a high traffic situation with degraded QoS,
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the Voicemail traffic is expected to significantly increase. The operator should consider to
deactivate the notification of voicemails via SMS. Under very high load the notified subscribers
will not be able to consult their voicemails anyway, due to the high blocking rate at the Air
interface. The deactivation should be done either on the VMS or on the SMSC.
AUTHENTICATION
Authentication in GSM aims at ensuring that only mobiles with an official SIM card can access
the network. Reducing authentication reduces the signaling on the BSS. The operator should
consider to disable the optional authentication activities in the network. This can be done by
modifying parameter AUTH_CONTROL_PARM in table OFCVAR. To configure to a minimum
activity the parameter has to be set as follows
GSM09: AUTH_CONTROL_PARM = NORM_0 PER_0 ATT_0 MO_0 MT_0
IMPACT
It should be noted that even with this minimum setting the authentication procedure will be
executed at the first Attach or Inter-VLR-location update of a mobile at the MSC. This implies
that a reasonable degree of security is reached. The default value of NORM_20 PER_20
ATT_20 MO_20 MT_20 configures that every 20th call, location update and attach will trigger
the authentication procedure. The above described minimum value results in only the first
location update (inter-VLR or attach) to trigger authentication.
The parameter allows to individually set authentication rates for normal (NORM), periodic
(PER) location updates location, Attachs (ATT), mobile originated (MO) and mobile terminated(MT) calls.
PAGE RETRY
The Paging message sent to the BSC is highly costly in terms of BSC CPU processing. After a
timer expires without a response from a mobile, the DMS sends a second Paging message.
Monitoring of live networks has shown that only an insignificant portion of the second paging
message is successfully responded by a mobile. Due to this it is recommended to deactivate
the paging retry. This is done by setting the parameter GSM_PAGE_RETRY in table
GSMVAR to 0.
CIPHERING
Ciphering guarantees confidentiality of GSM communications on the radio interface.
Deactivating Ciphering reduces the signaling on the BSC. The operator should consider
whether the deactivation of ciphering is acceptable during the special event. To deactivate, the
officeparameter GMSC_CIPHERING in table OFCENG of the MSC has to be set to OFF.
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6.21. IMPACT OF AUTOMATIC HANDOVER ADAPTATIONACTIVATION
The Automatic Handover Adaptation feature adapts handover parameters to radioenvironment of each call; taking into account mobile speed and frequency hopping with
BSCe3 The objective is to minimize call drops and bad quality transients.
The feature also has a power control adaptation mechanism in addition to the power budget
handover adaptation.
For a good understanding of this feature, please refer to the Automatic handover adaptation
chapter, or to the Functional Note TF1216 : Automatic handover adaptation ([R17])
6.21.1 RELATED PARAMETERS
All the parameters directly related to this feature are described in the Automatic Handover
Adaptation Parameters chapter, but one should also take into account the following
parameters to monitor an impact of the feature on an existing network.
Parameter Description
selfAdaptActivation Use for activate the Automatic Handover adaptation
servingfactorOffset This attribute defines the offset linked to the serving cell, used to decrease the HO margin
neighDisfavorOffset This attribute modifies the offset linked to the neighbouring cell, used to increase the HO marging
rxLevHreqave Number of signal strength measurements performed on a serving cell, used to compute arithmeticstrength averages in handover and power control algorithms
rxNCellHreqave Number of measurement results used in the PBGT algorithm to compute the average neighboring
signal strength
rxLevHreqaveBeg Number of measurement reports used in short averaging algorithm on current cell for signal strengtharithmetic average
rxLevNCellHreqaveBeg Number of measurement results used in short averaging algorithm to compute the averageneighboring signal strength
rxQualHreqave Number of arithmetic averages taken into account to compute the weighted average bit error rate inhandover and power control algorithms. Each is calculated from rxQualHreqave bit error rate (BER)measurements on a radio link
rxQualAveBeg This attribute defines the number of quality measures used by the power control mechanism, incase of hopping TS or fast MS
hoMargin Margin to use for PBGT handovers to avoid subsequent handover, in PBGT formula
hoMarginBeg Margin to be added to hoMargin until rxLevHreqave for short averaging algorithm in order tocompensate the lack of measurements
runHandOver Number of Measurement Results messages that must be received before the handover algorithm ina cell is triggered
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6.21.2 DEPLOYMENT OPTIMIZATION AND MONITORING
The expected gains when deploying Automatic Handover Adaptation feature are:
• Reduce Overall RF Drops
• Improve HO Drops and HO Failures
• RLT drops and BER improvement due to automatic power control effects
• Reduced time at max power due to better efficiency in power control
Hereunder is an example of activation of AHA that shows those improvements.
FIRST ACTIVATION
Activation parameters setting:
Parameter ValueselfAdaptActivation enabled
servingfactorOffset 2
neighDisfavorOffset 2
rxLevHreqave 8
rxNCellHreqave 8
rxLevHreqaveBeg 2
rxLevNCellHreqaveBeg 2
rxQualHreqave 8
rxQualAveBeg 2
hoMargin 4
hoMarginBeg 4
runHandOver 1
That activation has proven some good results, mainly on RF drops and Minute Of Usage, but
also on HO repartition, as shown below:
RF Drop per Erlang EvolutionRF Drop per Erlang Evolution
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As explained in the feature description the algorithm helps in the Urban areas by making
intelligent decisions for Power Budget handovers and reducing interference by more reactive
adjustment in attenuation.
In coverage limited environment the advantage is highly mitigated. In order to capture the
benefits from the feature in the Suburban and Rural areas through reducing rescue
handovers; appropriate recommendations should be applied (see chapter Final recommendedsetting).
Hereunde are the general conclusions about AHA activation:
• RF MoU/Drop improvement follows more closely the reduction in drop due to
handovers. BSCs with good coverage and having interference issues
definitely showed improvement in drops.
• BSCs with good ratio of hopping radios and having reduction in BER showed
some considerable improvement in RLT drops. These were areas where the
UL BER had shown consistent improvement after the feature activation
• BSCs with very low ratio of hopping Sectors OR even with high ratio of
hopping sectors showed NO considerable improvement in drops if they are
coverage limited OR less RF overlap.
Handover DistributionHandover Distribution
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FINE TUNING
FREQUENCY HOPPING CASE
The power Budget handover adaptation in the frequency hopping case ( > 3 SFH per sector)
uses servingfactorOffset to favor the server as suppose to the neighbor in two of the four
cases. So the setting of “-2” for servingFactorOffset means it will actually favor the server OR
in other words disfavor the neighbor greatly. The neighDisfavorOffset is already applied at “2”
dB such that the two cases where you have enough measurements of your server the
effective HOMargin (eff) will be 8 dB when you have not enough measurements in the
neighbor and 6 dB when you have enough measurements in the server as well as from the
neighbor. In the expectation of making better and more handovers decisions on PBGT in
these two case the HOMargin (eff) should be reduced by 2 dB in both these cases in order not
to disfavor the neighbor by effectively HOMargin of “6” OR “4” by tuning the
servingFactorOffset from “-2” to “0”.
Note: experience results presented in this part are done with 8 SFH per sector.
NON FREQUENCY HOPPING CASE
The power Budget handover adaptation in the non-frequency hopping case ( < 4 SFH per
sector) does not use servingFactorOffset to favor the server as suppose to the neighbor. This
case uses the neighborDisfavorOffset and so the HOMargin (eff) remains at 6 and 4 dB for
cases with server having enough measurements. However, the other two cases where the
neighbor is disfavored when the server is not having enough measurements seems to be very
high with the intial settings; HOMargin (eff) ( 4 + 4 = 8 dB). It was recommended to change the
HOMargin (eff) by tuning hoMarginBeg from “4” dB to “2” dB to get effective margin of “6” dB.
Handover QoSHandover QoS
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FINAL RECOMMENDED SETTING
The table below provides the recommended setting to take advantage of AHA activation
depending on the area characteristics:
Parameter Urban area Suburban area Rural area
selfAdaptActivation enabled enabled enabled
servingfactorOffset 0 2 0
neighDisfavorOffset 2 2 2
rxLevHreqave 8 8 8
rxNCellHreqave 8 8 8
rxLevHreqaveBeg 2 2 2
rxLevNCellHreqaveBeg 2 2 2
rxQualHreqave 8 8 8
rxQualAveBeg 2 2 2
hoMargin 4 4 2
hoMarginBeg 2 2 4
runHandOver 1 1 1
Handover QoSHandover QoS
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6.22. HANDOVER FOR TRAFFIC REASONS ACTIVATIONGUIDELINE
The purpose of this guideline is to define a default activation of the feature “Handovers fortraffic reasons” over the whole BSC. This proposal includes also the usage of the feature
“Handover decision according to adjacent cell priorities and load” and the default activation of
directed retry. We remind that HoTraffic must be favoured for traffic reason instead of using
the feature Directed Retry, which is a solution only for occasional cases of congestion.
For a better understanding please refer to the following Functional Notes and chapters:
• [R12] Handover for traffic reasons: TF132
• Handover for traffic reasons
• [R13] Handover decision according to adjacent cell priorities and load TF716
• Handover decision according to adjacent cell priorities and load
• Directed Retry Handover
The objectives of a BSC deployment of that feature would be:
• to reduce current TCH blocking wherever it happens on normal origination
and during HO phase
• to anticipate unexpected TCH blocking in order to improve traffic carried on
originating and ongoing calls
• to facilitate feature activation process by generalising the settings on the
whole BSC
6.22.1 ALGORITHMS AND PARAMETERS DEFINITION
As the Directed Retry handover is intended to re-direct TCH Allocation on a loaded cell to an
other cell, the traffic handover’s objective is to leverage resources blocking when one cell is
overloaded by redirecting the most appropriate calls in progress to neighbour cells with a
PBGT handover procedure.
OVERLOAD CRITERION
The overload criterion is defined on a cell basis and can take two expressions according to the
operator’s choice :
• If queuing is not activated the number of available TCHs is lower than the
defined threshold,
• If queuing is activated: the number of queued TCH requests is greater than
the defined threshold.
That mechanism is decribed in the chapter Congestion determination.
When overload occurs, the BTS sends, on request from the BSC, HO indications including the
list of candidate neighbors n for which the following expression is fullfilled:
EXP2Traffic(n) = Pbgt(n) - [hoMargin(n) - hoMarginTrafficOffset(n)]
Refer also to the chapter General formulas.
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RELATED PARAMETERS
Parameter Description
hoTraffic (bsc) enable the traffic HO feature at BSC levelhoTraffic (bts) enable the traffic HO feature at BTS level
hoMarginTrafficOffset level strength margin added to compute the neighbor eligibility in case of traffic HO(refer to EXP2Traffic)
numberOfTCHFreeBeforeCongestion minimum number of free TCHs which triggers the beginning of the TCH congestionphase and the beginning of the traffic overload condition
numberOfTCHFreeToEndCongestion number of free TCHs which triggers the end of the TCH congestion phase and the endof the traffic overload condition
hoPingpongCombination list of couples of causes (HOInitialCause and HONonEssentialCause) to preventpossible HO ping pong due to traffic HO
hoPingpongTimeRejection timer associated to the anti ping pong feature
offsetLoad level strength offset added to compute the neighbor eligibility depending on its state ofcongestion (refer to EXP4)
Furthermore and as described in the chapter Expected effects and recommended parameters,
queuing and directed retry parameters have to be set properly. As a reminder:
• Queuing activation: please refer to chapters Queuing and TCH Allocation
Management Parameters
• Directed retry: please refer to chapters Directed Retry Handover and Directed
Retry Handover Parameters
FEATURE INTERWORKING
In order to avoid blocking the originating calls on congested cells, directed retry with default
settings should be enabled, and to avoid a return from non congested to congested cell after
HO traffic activation two features should be used:
• prevent « ping-pong » effect by applying a protection timer for all incoming
relations onto the congested cell
• prevent a « snow ball » effect by using the load status conditions through the
usage of the offset load parameter in :
EXP4(n) = EXP2(n) – [offsetLoad(n) * stateLoad(n)]
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6.22.2 EXPECTED EFFECTS AND RECOMMENDED PARAMETERS
Let’s consider a cell A passing through different states of congestion and the HO interactions
in its neighborhood.
In a normal phase incoming HO toward cell A can be alarm HO, PBGT HO, or traffic HO
coming from congested neighbor cells.
As the congestion state is reached on cell A, depending on the cell load state and the
associated parameter, some procedures are engaged to try to set back the cell to a non
congested state:
• traffic HO are activated from cell A to its non congested neighbor cells, i.e.
PBGT HO with a smaller margin
• traffic HO are disfavored toward congested cell thanks to Handover decision
according to adjacent cell priorities and load feature
• HO toward cell A are also disfavored
When the cell A succeed in balancing the excess of traffic it reaches again a non congested
cell and the normal procedures are applicable again.
PARAMETER TUNING
As described hereabove the expected behaviour takes benefit from the Handover for traffic
reasons feature that allows to balance calls in good radio conditions toward neighbor cells via
a traffic HO, from the directed retry HO that balance TCH assignment to neighbor cells, and
from the Handover decision according to adjacent cell priorities and load feature that prevents
from oading the cell with unnecessary incoming HO.
Directed retry parameters settings are summarized in the following chapter §4.5.5 and
hoMarginTrafficOffset and offsetLoad parameters tuning is explained hereunder.
Cell A Cell A Cell A
Congested cell
Non congested cell
Overload phaseNormal phase Normal phase
Normal HO (PBGT, Qual, Lev, …)
Traffic HO
Prevented HO on load condition
Cell A Cell A Cell A
Congested cell
Non congested cell
Overload phaseNormal phase Normal phase
Normal HO (PBGT, Qual, Lev, …)
Traffic HO
Prevented HO on load condition
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One can observe on the above figure that using traffic HO is likely to simulate an increase in
the non congested neighbor cell coverage of hoMarginTrafficOffset dB. In order to prevent
outgoing traffic HO from A to B to come back on A an offsetLoad value equal to
hoMarginTrafficOffset is recommended. In that case any attempt of HO from “traffic extended”
B cell coverage to A would be discarded.
offsetLoad ≥ hoMarginTrafficOffset
Furthermore, the correct setting of the anti ping pong feature sould harden that behaviour for
the PBGT HO from B to A.
CAUTION!
The following exceptions should be applied:
• Timer protection should not be set from cells like: indoor, microcells, special
coverage, or any relation with HOmarginPBGT < 0
• Offset load should not be set from cells like: indoor, microcells, special
coverage, or any relation with HOmarginPBGT < 0
Cell A congested
hoMarginTrafficOffset
Offset load
Cell B non congestedCell A congested
hoMarginTrafficOffset
Offset load
Cell B non congested
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RECOMMENDED PARAMETERS
CONGESTION DETECTION
Parameter Recommended value
numberOfTCHFreeBeforeCongestion 10 % of potential ressources for circuit cal ls including preemptable PDTCH
numberOfTCHFreeToEndCongestion 20 % of potential ressources for circuit cal ls including preemptable PDTCH
Note: potential ressources for circuit calls including preemptable PDTCH cans be deduced
from the following metric
(C1700 max value (tchFrAveragedAvailableMax) - AllocPriorityThreshold)
HANDOVER FOR TRAFFIC REASONS ACTIVATION
Parameter Recommended value
hoTraffic (bsc) enabled
hoTraffic (bts) enabled
hoMarginTrafficOffset 6 dB
Note: HoMarginTrafficOffset should be tune such as the resulting margin should be equivalent
to the one for rescue HO. This margin can be increase case by case for cell with important
congestion. At on stage it is preferable to add capacity.
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HANDOVER DECISION ACCORDING TO ADJACENT CELL PRIORITIES AND LOAD ACTIVATION
Parameter Recommended value
offsetLoad ≥ hoMarginTrafficOffset
GENERAL PROTECTION AGAINST HO PINGPONG
Parameter Recommended value
hoPingpongCombination (all, PBGT)
hoPingpongTimeRejection at least 20s
DIRECTED RETRY HANDOVER ACTIVATION
Parameter Recommended value
directedRetryModeUsed bts
interBscDirectedRetry allowed
intraBscDirectedRetry allowed
interBscDirectedRetryFromCell allowed
intraBscDirectedRetryFromCell allowed
modeModifyMandatory used
directedRetry - 80 dBm
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6.23. DISABLING AMR BASED ON TRAFFIC IN V15.1.1
Previously to V15.1.1, if hrCellLoadStart > 0, then HR calls can be allocated as long as the
RxLev criterion is matched.
To achieve such a behavior in V15.1.1, since AMR based on traffic is automatically activated,
it is necessary to set the parameters as following:
• filteredTrafficCoefficient = 1
• hrCellLoadStart = 1 (range [0 to 100])
• hrCellLoadEnd = 0 (range [0 to 100])
With this values, the “V15.1 like” behaviour should be reached after nb_of_inService_DRX*10
seconds.
Note: the behaviour with this configuration is based on a theoretical study of the AMR based
on traffic algorithm.
To prevent HR allocation, it is necessary to set the parameters as following :
• hrCellLoadStart = 0 (range [0 to 100])
• amrDirectAllocRxLevUL or amrDirectAllocRxLevDL = more than -48 dBm
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7. APPENDIX A: MAIN EXCHANGE PROCEDURES
AT BSC LEVEL
7.1. ESTABLISHMENT PROCEDURE
SABME: frame to set asynchronous balanced mode (initiate a link for numbered information
transfer).
UA: unnumbered aknowledge
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7.2. CHANNEL MODE PROCEDURE
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7.4. INTRACELL HANDOVER PROCEDURE
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7.5. INTRABSS HANDOVER PROCEDURE
From BTS 1 to BTS 2
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7.6. INTERBSS HANDOVER PROCEDURE
BTS 1 (from BSC 1) to BTS 2 (from BSC 2)
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7.7. 2G-3G HANDOVER PROCEDURE
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7.8. RESOURCE RELEASE PROCEDURE (EXAMPLE)
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7.9. SACCH DEACTIVATION PROCEDURE
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7.10. MOBILE TERMINATING CALL
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7.11. MOBILE ORIGINATING CALL
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8. APPENDIX B: ERLANG TABLE
The table below presents the number of Erlang that are expected with regards to the numberof TCH channels on a given cell and considering a blocking rate of 0,01 %. The computation
follows the Erlang B law.
Additionally, this table gives the number of Erlang expected depending on the AMR Half Rate
penetration.
CAUTION!
The expected number of Erlang with regards to the AMR HR penetration has been calculated
based on an estimation of the gain in capactiy provided by AMR HR. It should not be
considered as contractual but as a good approximation of the expected gain.
% Blocking 2% 2% 2% 2% 2%
AMR HR penetration 0 % 25 % 50 % 75 % 100 %
Number of TCH
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
1920
21
22
23
24
25
26
27
28
29
30
31
32
0,021
0,223
0,602
1,092
1,657
2,276
2,935
3,627
4,345
5,084
5,842
6,615
7,401
8,200
9,010
9,829
10,656
11,491
12,33313,181
14,036
14,896
15,761
16,631
17,504
18,383
19,265
20,150
21,040
21,932
22,827
23,725
0,021
0,230
0,630
1,158
1,783
2,483
3,208
3,972
4,767
5,589
6,434
7,299
8,182
9,082
9,978
10,885
11,800
12,724
13,65614,594
15,540
16,525
17,520
18,524
19,536
20,558
21,587
22,624
23,669
24,643
25,617
26,593
0,022
0,247
0,698
1,324
2,097
3,000
3,882
4,814
5,786
6,794
7,833
8,899
9,991
11,106
12,114
13,119
14,119
15,112
16,09917,077
18,046
19,272
20,517
21,783
23,068
24,374
25,698
27,041
28,403
29,596
30,791
31,989
0,023
0,284
0,849
1,688
2,787
4,138
5,299
6,502
7,732
8,982
10,245
11,516
12,790
14,065
15,360
16,655
17,946
19,234
20,51621,791
23,059
24,579
26,118
27,678
29,257
30,857
32,474
34,112
35,767
37,200
38,629
40,058
0,027
0,365
1,177
2,482
4,294
6,621
8,377
10,152
11,922
13,669
15,385
17,056
18,677
20,241
22,004
23,747
25,468
27,164
28,83430,473
32,082
34,075
36,081
38,102
40,135
42,182
44,240
46,310
48,391
50,467
52,551
54,645
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33
34
35
36
3738
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
6061
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
8384
24,626
25,529
26,435
27,343
28,25429,166
30,081
30,997
31,916
32,836
33,758
34,682
35,607
36,534
37,462
38,392
39,323
40,255
41,189
42,124
43,060
43,997
44,936
45,876
46,816
47,758
48,700
49,64450,589
51,534
52,480
53,428
54,376
55,325
56,275
57,226
58,177
59,129
60,082
61,035
61,990
62,945
63,901
64,857
65,813
66,771
67,729
68,688
69,647
70,607
71,56872,529
27,569
28,545
29,521
30,498
31,53432,574
33,618
34,664
35,714
36,768
37,825
38,886
39,815
40,741
41,662
42,580
43,493
44,402
45,308
46,426
47,549
48,678
49,812
50,951
52,095
53,245
54,399
55,34456,285
57,224
58,158
59,091
60,019
61,029
62,039
63,048
64,057
65,065
66,073
67,080
68,087
69,258
70,434
71,614
72,798
73,987
75,179
76,377
77,340
78,300
79,25880,215
33,191
34,394
35,600
36,808
37,98839,169
40,349
41,528
42,708
43,886
45,065
46,242
47,306
48,364
49,414
50,458
51,494
52,523
53,546
54,862
56,184
57,513
58,847
60,187
61,533
62,886
64,243
65,34566,443
67,537
68,626
69,711
70,792
71,867
72,937
74,003
75,065
76,122
77,174
78,222
79,266
80,665
82,071
83,482
84,900
86,325
87,755
89,192
90,276
91,358
92,43493,508
41,485
42,908
44,329
45,748
47,24848,750
50,255
51,761
53,269
54,779
56,290
57,803
59,197
60,585
61,968
63,346
64,719
66,085
67,447
68,982
70,519
72,059
73,600
75,144
76,690
78,237
79,786
81,12482,456
83,782
85,101
86,414
87,720
89,092
90,459
91,822
93,181
94,536
95,886
97,232
98,574
100,154
101,738
103,323
104,912
106,504
108,098
109,696
111,137
112,578
114,017115,455
56,748
58,857
60,975
63,100
65,07767,051
69,023
70,990
72,954
74,914
76,870
78,822
80,555
82,272
83,973
85,658
87,327
88,979
90,616
92,628
94,640
96,654
98,667
100,682
102,697
104,712
106,726
108,458110,181
111,893
113,592
115,282
116,961
118,865
120,765
122,664
124,559
126,452
128,341
130,227
132,109
134,307
136,512
138,723
140,939
143,163
145,392
147,628
149,435
151,237
153,032154,822
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85
86
87
88
8990
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112113
114
115
116
117
118
73,490
74,452
75,415
76,378
77,34278,306
79,270
80,235
81,201
82,167
83,133
84,100
85,067
86,035
87,003
87,972
88,941
89,910
90,880
91,850
92,820
93,791
94,763
95,734
96,706
97,678
98,651
99,624100,597
101,571
102,545
103,519
104,493
105,468
81,169
82,120
83,069
84,016
85,13186,247
87,365
88,485
89,607
90,732
91,857
92,944
94,033
95,122
96,212
97,303
98,395
99,487
100,581
101,704
102,828
103,955
105,083
106,212
107,342
108,474
109,568
110,663111,758
112,854
113,951
115,047
116,145
117,244
94,578
95,644
96,706
97,764
99,178100,596
102,020
103,448
104,882
106,322
107,765
108,975
110,184
111,393
112,601
113,809
115,017
116,223
117,429
118,717
120,005
121,295
122,587
123,880
125,173
126,467
127,684
128,900130,115
131,331
132,546
133,760
134,974
136,187
116,890
118,324
119,756
121,187
122,918124,654
126,396
128,144
129,899
131,659
133,424
134,758
136,088
137,415
138,736
140,053
141,366
142,675
143,979
145,583
147,190
148,800
150,412
152,025
153,640
155,257
156,717
158,177159,634
161,091
162,547
164,001
165,454
166,906
156,606
158,384
160,156
161,922
164,140166,362
168,590
170,823
173,062
175,307
177,556
179,493
181,428
183,361
185,291
187,220
189,146
191,070
192,993
195,088
197,185
199,284
201,385
203,487
205,590
207,694
209,642
211,588213,531
215,473
217,414
219,352
221,289
223,224
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9. ABBREVIATIONS & DEFINITIONS
9.1. ABBREVIATIONS
For other abbreviations, refer to [R3].
AMNU Advanced Management Unit
AMR Adaptative Multi-Rate
AMR-HR Adaptative Multi-Rate Half Rate
AMR-FR Adaptative Multi-Rate Full Rate
BCC Base station Colour Code
Last three bits of BSIC code. The BCC is used to identify one of the cellssharing the same BCCH frequency. Neighouring cells may, or may not, havedifferent BCC.
BCCH Broadcast Control CHannel
Common mobile logical channel used for broadcasting system informationon the radio interface
BCF Base Common Function
BDA BSC application database
This database contains all the information objects describing the BSS.
BDE OMC-R operations database
This database contains all the information objects describing the BSS underOMCR management control, and the objects required to manage OMC-Rfunctionalities
BER Bit Error Rate
Method of measuring the quality of radio link transmission
A ratio of the number of digital errors received in a specified period to thetotal number of bits received in the same period. Usually expressed as anegative exponent, i.e:
10-6 means one bit error in 106 bits of transmission, or one in a million
BIFP Base Interface Front-end Processor
Set of BSC functional units managing the interface with BTS
BSC Base Station Controller
BSCB BTS Signalling Concentration Board
Board which concentrates 12 LAPD signalling channels between BSC andBTS into 3 channels
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BSIC Base Station Identity Code
Code used to identify a base station which allows mobile stations todistinguish the cells sharing the same BCCH frequency. A BSIC is defined
by an (NCC, BCC) combination
BSS Base Station Subsystem
Radio Cellular Network radio subsystem made up of Base StationControllers, one or more remote TransCoder Units and one or more BaseTransceiver Stations
BTS Base Transceiver Station
CA Cell Allocation
Radio frequency channel allocated to a cell
CBCH Cell Broadcast CHannel
Logical channel used inside a cell to broadcast short messages inunacknowledged mode
CC Call Control
Sublevel of layer 3 on the radio interface charged with managing callprocessing
CCCH Common Control CHannel
Common bidirectional mobile control channel, used for transmittingsignalling information on the radio interface
CCH Control ChannelCommon or dedicated control channel
CGI Cell Global Identifier
Global identifier of a mobile network cell. The CGI contains the Location Area Code (LAC), Mobile Country Code (MCC), Mobile Network Code(MNC) and the cell identifier in the location area
CMC Codec Mode Command
CPU Central Processing Unit
Slave BSC processing unit
CPU-MPU/BIFP Central BSC processing unit handling MPU and BIFP functions
dB Decibel
Measurement unit of relative power level defined as 10 log10 (P1/P2) whereP1 and P2 are the power levels.
dBm Power in dB relative to 1 mW
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DCCH Dedicated Control CHannel
Dedicated radio signalling channel with one SDCCH + one SACCH
DITR Dominant to Interferer TSC Ratio
DLNA Duplexer Low Noise Amplifier
Amplifier installed between BTS and the antenna
DRX Driver and Receiver Unit
Signal processing unit for radio transmission and reception.
DTX Discontinuous Transmission
EFR Enhanced Full Rate vocoder
EIRP Equivalent Isotropic Radiated Power
eMLPP enhanced Multi Level Precedence and Preemption
FACCH Fast Associated Control CHannel
Dedicated signalling channel (Um interface)
FCCH Frequency Correction CHannel
Common frequency synchronization channel
FCH Frequency CHannel
Common frequency synchronization channel
FER Frame Erasure Rate
FH Frequency Hopping
FN Frame Number
FP Frame Processor
FR Full Rate TCH
GSM Global System for Mobile Communications
GSM 900 Radio Cellular Network standard adapted for the 900 MHz frequency band.
GSM 1800 Radio Cellular Network standard adapted for the 1800 MHz frequency band.
GSM 1900 Radio Cellular Network standard adapted for the 1900 MHz frequency band.
HO HandOver: automatic call transfer between two radio channels
HR Half Rate TCH
HSN Hopping Sequence Number
ICM Iinitial Codec Mode
L1M Processor functional unit handling BTS radio measurements
LAC Location Area Code
Code used to identify a location area in the GSM network
LAI Location Area Identity
Geographic identity of a group of cells used to locate a mobile station
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LB Link Budget
LNA Low Noise Amplifier, part of DLNA system
MA Mobile Allocation
MAI Mobile Allocation Index
MAIO Mobile Allocation Index Offset
MCC Mobile Country Code
MTBF Minimum Time Between Failure
MEU Masthead Electronics Unit
Mini-masthead electronics cabinet. Remote amplifier located between BTSand the antenna
MHz MegaHertz
MMU Mass Memory Unit (BSC)
MPU Main Processor Unit (BSC)
Set of BSC functional units charged mainly with call processing functions
MNC Mobile Network Code
Mp Measurement processing
MRC Maximum Radio Combiner
MS Mobile Station
MSC Mobile Services Switching Center
MCL Minimum Coupling Loss
MTBF Mathematical Time Between Failure
It is a mathematical time expectancy between two successive parts ofequipment or unit failure
NCC Network Colour Code
First three bits of the BSIC code. Each country is assigned a list of NCC.
NMC Network Management Centre
NSS Network and Switching SubSystem
Radio Cellular Network subsystem including an MSC, main HLR, VLR, EIRand AUC
NS/EP National Security and Emergency Preparedness
OMC Operation and Maintenance Centre for the radio subsystem
OMC-R Operation and Maintenance Centre - Radio
OMC-S Operation and Maintenance Centre - Switching
OMU Central BSC Operation & Maintenance Unit
OSS Operation SubSystem
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Radio Cellular Network operations subsystem including the OMC-R andOMC-S
PA Power Amplifier
PBGT Power Budget
PC Power Control
PCH Paging CHannel
Common subscriber radio paging channel
PLMN Public Land Mobile Network
PSTN Public Switched Telephone Network
PURQ-AC Public Use Reservation for Queuing – All Calls
RACH Random Access CHannel
Common mobile logical channel, reserved for random access requeststransmitted by mobile stations on the radio interface.
RF Radio Frequency
RLC Radio Link Counter
RX BTS receiver
RXLEV Received signal Level
RXQUAL Received signal Quality
SACCH Slow Associated Control CHannel
Slow logical control channel associated with a traffic channel during acommunication
SCH Synchronization CHannel
Common time division synchronization channel
SDCCH Standalone Dedicated Control CHannel
Dedicated radio signalling channel temporarily allocated during call set up.There are 2 types of SDCCH: SDCCH/8 and SDCCH/4, on which the logicalchannels are grouped by 8 and by 4 respectively and combined with CCH
SFH Slow Frequency Hopping
SFH mobile mobile using an hopping channel
Non SFH mobile mobile using a non hopping channel
SICD Serial Interface Controller LAPD
BSC board controller for Abis and Ater Interface
SNR Signal to Noise Ratio
SPU Signal Processing Unit
SUP SUPervision unit
Functional BSC monitoring unit
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SWC SWitching matrix Controller (BSC 6000)
TA Timing Advance
Alignment process designed to compensate propagation time between amobile and base station
TCH Traffic CHannel
Radio traffic channel
TCH/F Traffic CHannel/Full rate
TCH/H Traffic CHannel/Half rate
TDMA Time Division Multiple Access
Abbreviation used to designate a transmission frame on the radio interface,divided into eight time slots (TS) or channels
TMU Traffic Management Unit
TRX Transmission/reception subsystem of the BTS
TS Time Slot
TSC Training Sequence Code
TSCB Transcoder Signalling Concentration Board (BSC)
Board which concentrates LAPD signalling channels between BSC and TCUinto a single channel
TX BTS transmitter
WPS Wireless Priority Service
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9.2. DEFINITIONS
CODEC MODE
Codec mode is used to designate one of the 8 AMR vocoder and identified using its rate
(12k2, 10k2, 7.95, 7k4, 6k7, 5k9, 5k15, 4k75) give in kbps.
CONCENTRIC CELL
Two concentric geographical zones delimited by distance and level criteria (outer zone and
inner zone).
DUAL BAND CELL
Each group of TRXs is dedicated to a frequency band (900 and 1800 MHz for example) with
different radio propagation condition; the frequency band used for the largest zone (outer) is
the one used by the mono-band MS already existing in the network, since a mono-band MS
must still be able to decode the common channels.
DUAL COUPLING CELL
Each group of TRXs is dedicated to a frequency band and the two groups of TRXs are
combined with coupling systems with different losses, resulting in different coverage areas
with the same TX transmission power.
OuterzoneInnerzone
BCCH and
signallingchannels
trafficchannels
OuterzoneInnerzone
BCCH and
signallingchannels
trafficchannels
Outerzone
band0GSM (or DCS)
Innerzone / band1DCS (or GSM)
BCCH and
signalling
channels
traffic channels
Outerzone
band0GSM (or DCS)
Innerzone / band1DCS (or GSM)
BCCH and
signalling
channels
traffic channels
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ERLANG
Unit of telecommunications traffic intensity.
The number of erlangs represents the average number of resources or circuits occupied
during the peak traffic hour.
FREQUENCY LOAD
Defines the load of a frequency hopping pattern and is evaluated as below:
fl = Nb of hopping TRX in the cell / Nb of frequencies in the hopping law
FREQUENCY HOPPING: AD-HOC
The Ad-Hoc frequency hopping does not reproduce a pattern all over the network. Frequency
planning is done (HSN, MAIO, MA lists) according to the interference matrix. The particularity
is that the number of hopping TRX = the number of hopping frequencies in most of the cases.
FREQUENCY HOPPING PATTERNS: 1X1
This frequency pattern is used in case of frequency hopping. Each hopping TRX of 1*1 cell,
uses all frequencies of the frequency law:
FREQUENCY HOPPING PATTERNS: 1X3
This frequency pattern is used in case of frequency hopping. Each hopping TRX of 1*3 cell,
uses 1/3 frequencies of the frequency law:
OuterzoneH2D
InnerzoneH4D
BCCH and
signallingchannels
traffic
channels
OuterzoneH2D
InnerzoneH4D
BCCH and
signallingchannels
traffic
channels
f1,f2,f3,f4
f1,f2,f3,f4 f1,f2,f3,f4
f1,f2,f3,f4
f1,f2,f3,f4 f1,f2,f3,f4
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MULTIZONE CELL
Used in order to refer following kinds of cell:
• concentric cell (see above)
• heterogeneous coupling cell (see above)
• dual-band cell (see above)
RADIO INTERFACE
Interface between the mobile station (MS) and the BTS.
SPEECH FRAME
Corresponds to 20 ms of speech on the radio interface and theTRAU interface.
TIMING ADVANCE
Delay used to compensate propagation time between mobile and base station.
UM-INTERFACE
See “Radio interface”
WPS CALL
Call which has priority level set in the Assignment Request or Handover Request between 2
and 6 (3GPP TS 48.008)
f1,f2,f3
f7,f8,f9 f4,f5,f6
f1,f2,f3
f7,f8,f9 f4,f5,f6
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10. INDEX
All the parameters listed in the chapter ALGORITHM PARAMETERS are listed and indexedhere below:
accessClassCongestion, 343adaptiveReceiver, 449adjacent cell umbrella ref, 358allocPriorityTable, 343allocPriorityThreshold, 344allocPriorityTimers, 345allocWaitThreshold, 346allOtherCasesPriority, 346amrAdaptationSet, 426, 427, 428
amrDirectAllocIntRxLevDL, 436amrDirectAllocIntRxLevUL, 436amrDirectAllocRxLevDL, 435amrDirectAllocRxLevUL, 435amrFRIntercellCodecMThresh, 436amrFRIntracellCodecMThresh, 437amrHRIntercellCodecMThresh, 437amrHRtoFRIntracellCodecMThresh, 437amriRxLevDLH, 438amriRxLevULH, 438amrReserved1, 439amrReserved2, 439answerPagingPriority, 347
assignRequestPriority, 347averagingPeriod, 372baseColourCode, 447bCCHFrequency_adjacentCellHandover, 398bCCHFrequency_adjacentCellReselection, 398bCCHFrequency_bts, 400biZonePowerOffset_adjacentCellHandover, 362biZonePowerOffset_handoverControl, 363bscHopReconfUse, 388bscMSAccessClassBarringFunction, 348bscQueueingOption, 348bsMsmtProcessingMode, 335bsPowerControl, 335bssMapT1, 376bssMapT12, 376bssMapT13, 376bssMapT19, 377bssMapT20, 377bssMapT4, 377bssMapT7, 378bssMapT8, 378bssMapTchoke, 378bssPagingCoordination, 448bssSccpConnEst, 379bsTxPwrMax, 335bts Time Between HO configuration, 309btsHopReconfRestart, 388btsIsHopping, 389
btsMSAccessClassBarringFunction, 349btsSMSynchroMode, 446btsThresholdHopReconf, 389callClearing, 331callReestablishment, 297callReestablishmentPriority, 349capacityTimeRejection, 415cellAllocation, 390cellBarQualify, 350
cellBarred, 350cellDeletionCount, 305cellDtxDownLink, 403cellReselectHysteresis, 284cellReselectOffset, 285cellReselInd, 285cellType_adjacentCellHandover, 329cellType_bts, 329channelType, 350cId, 418coderPoolConfiguration, 430compressedModeUTRAN, 418concentAlgoExtMsRange, 364
concentAlgoExtRxLev, 365concentAlgoIntMsRange, 364concentAlgoIntRxLev, 366, 367concentric cell, 368cypherModeReject, 449dARPPh1Priority, 447data mode 14.4 kbit/s, 404data non transparent mode_bts, 404data non transparent mode_signalingPoint, 404data transparent mode_bts, 405data transparent mode_signalingPoint, 405Data14_4OnNoHoppingTs, 404delayBetweenRetrans, 383directedRetry, 358directedRetryModeUsed, 359directedRetryPrio, 353distHreqt, 307distWtsList, 307diversity, 407diversityUTRAN, 418dtxMode, 403early classmark sending, 396earlyClassmarkSendingUTRAN, 419emergencyCallPriority, 351enableRepeatedFacchF, 443encrypAlgoAssComp, 450encrypAlgoCiphModComp, 450encrypAlgoHoPerf, 450
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encrypAlgoHoReq, 451encryptionAlgorSupported, 451enhancedTRAUFrameIndication, 409enhCellTieringConfiguration, 410estimatedSiteLoad, 395
extended cell, 331facchPowerOffset, 443fDDARFCN, 419fDDMultiratReporting, 293fDDreportingThreshold, 293fDDreportingThreshold2, 294fhsRef, 391fnOffset, 446forced handover algo, 309frAMRPriority, 432
intraCell, 322intraCellHOIntPriority, 352intraCellQueueing, 353intraCellSDCCH, 322layer3MsgCyphModeComp, 452
locationAreaCodeUTRAN, 423lRxLevDLH, 325lRxLevDLP, 336lRxLevULH, 325lRxLevULP, 336lRxQualDLH, 327lRxQualDLP, 337lRxQualULH, 327lRxQualULP, 337maio, 392