gsm handbook optimize

7/15/2019 GSM Handbook Optimize

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GSM OPTIMISATION

HANDBOOK

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1. Introduction....................................................................................................32. Support Arrangement ....................................................................................43. Optimisation Team Structure .........................................................................54. Bad Perfromance FisH Bone diagram ...........................................................6

5. Information Preparation .................................................................................76. General Optimisation Proceedure..................................................................87. Alarm Analysis...............................................................................................98. Statistics Investigation Procedure................................................................109. Drive Test ....................................................................................................12

9.1. Drive Test Reminder ................................................................................129.2. Drive Test Log Investigation Consideration..............................................12

10. Frequeny Planning.......................................................................................1310.1. BCCH and BSIC planning criteria.........................................................1310.2. Frequency Assignment Criteria ............................................................1310.3. Frequency Retune Procedure...............................................................14

11. Add Neighbor Criteria ..................................................................................1412. High Rise Building Coverage.......................................................................1513. Maximum System Configuration..................................................................1514. HDPC Setting Template ..............................................................................17

14.1. TX Power and Power Control ...............................................................1714.2. Handover ..............................................................................................2014.3. Multiband..............................................................................................2214.4. Miscellaneous.......................................................................................22

15. Tools Available .............................................................................................2416. Problem Root Cause ...................................................................................25

16.1. High SDCCH Blocking..........................................................................2516.2. High TCH Blocking ...............................................................................2616.3. SDCCH Access Failure Rate................................................................2716.4. Handover Failure & Loss ......................................................................2816.5. MSC Connection Rate .........................................................................2916.5. SDCCH and TCH RF Loss ...................................................................3016.6. Power Control.......................................................................................3116.7. Handover Problem................................................................................3116.8. Others...................................................................................................32

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1. INTRODUCTION

Teamwork, “listen to order”, cycle time reduction and follow procedure are criticalto every successful optimisation.

Below is the optimisation flow chart:

No

Yes

Data Analysis

Data Preparation

Com lete

Optimisation

Data Collection

Satisfactory

Result?

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2. SUPPORT ARRANGEMENT

PEG ArrangementOptimisation Flow

Monthly performancemeeting to identifyoptimisation targets.

Account Team suppliesrequired information

PEG preparesINFORMATION FOR

OPTIMISTION

PEG audits network in

Beijing

PEG arrives localoffice to discuss the

optimisation plan with Account Team and

Customer

Start optimisation

PEG derivesoptimisation plan

Start optimisation and skilltransfer and acquisition

OMC Engineer arrives localoffice to setup datacollection platform

Contractor preparesoptimisation informationin Beijing

Engineers perform brief

audit in Beijing tounderstand REAL situation

PEG discuss with account

teams to identifyoptimisation targets.

All engineers return toBeijing to derive plan

Best engineeringarrangement arrives at localoffice

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3. OPTIMISATION TEAM STRUCTURE

Job FunctionBSS Controller - Understand fully on BTS maintenance, BSS configuration

Alarm Monitoring,- Monitor daily alarm

Statistics Monitoring- Investigate problem from statistics

D.B. & Feature Controller

- Check database and monitor feature deployment process

Drive Test Log Investigator - Investigate problem from drive test log

D.B. & FeatureController

Drive Test LogInvestigator

AlarmMonitoring

StatisticsMonitoring

BSSController

MONITORING ACTION

Team Leader

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4. BAD PERFROMANCE FISH BONE DIAGRAM

FrequencyPlan

NetworkTopology

Signaling Mobile

Bad Performance

DatabaseSetting Coverage

Software HardwareCapacity

ExternalInterferenceNeighbor Calculation

Statistics Peggingand Retrieval

CableConnection

Documentation

Example of each major problems:a. Database Setting – improper HOPC settingsb. Neighbor – wrong external neighbor’s BCCH or BSIC values, missing

neighbor c. Coverage – weak, highly overlapped, improper antenna downtilt and

orientationd. External Interference – microwave, repeater, faulty alarme. Calculation – incorrect statistics equationsf. Cable Connection – no/cross connectiong. Statistics Pegging and Collection – SW problem on statistics pegging, or

retrievalh. Capacity – lack of TRCU, improper channel configuration, lack of RSL, MTL

linksi. Frequency Plan – co-channel, adj-channel, improper BSIC planning

j. Software – bugk. Hardware – wrong cable connection, faulty combiner and filter, PCM link

downl. Network Topology – bad site location selection, redundant site deployedm. Signaling – Improper cause value and message sequencen. Mobile – faulty mobile in term of signaling or frequency hopping capabilityo. Documentation – wrong feature/parameter usage description

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5. INFORMATION PREPARATION

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6. GENERAL OPTIMISATION PROCEEDURE

Data Collection & CheckLocal Office NetPlan

Information

1 day

Data Preparation &NetPlan Information

Correction

Network Audit from1. Alarm2. Statistics3. Database4. Check customer statistics equations

1. Suggest Better Database Setting (Channel Reconfiguration,Standard HOPC, Blocking Timer , Congestion Relief)

2. Capture External Interference3. Frequency Retune for high IOI, BER and TCH_RF_LOSS4. Audit External Neighbor 5. Improper ARFCN:BSIC Planning6. GPROC loading7. RSL & MTL Usage

Statistics & DB. mainly ona. SDCCH Access Failureb. CSFRc. Drop Calld. TCH_RF_Losse. HO_Lossf. HO_Failureby ARFCN retune, neighor change and coverage

Hardware

Capacity

Database,Interference& Capacity

NetworkTopology

FP, Neighobr andCoverage

2 days

2 days

12 days

2 days

2 days

2 days

Solve Blocking by:

a. BCCH Optimisationb. Neighor Optimisationc. Add Radiod. Site Reconfiguratione. Add Sitef. Antenna Refinement

Network Topology Problem

due to no available ARFCN isfound by:a. Site Replacementb. Coverage Optimisationc. Capacity Dimensioning

TEMS Log & FP. mainly ona. Undecoded BCCHb. Missing Neighbor c. HO Failured. Incorrect External Neighbor e. Weak Coveragef. High Overlappingg. use non-dominant server by ARFCN retune, neighor change and coverage

1. Hardware Fix (Sleeping Cell, OOS TCU, OOS TS2. Path Balance Issue, Faulty TCU from TCH_RF_Loss Issue)

3. GCLK shift and frequent Phase Lock Loop failure from Alarm

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7. ALARM ANALYSIS

Below lists some important alarms that we focus,

a. Critical and major alarmb. Alarms affect voice quality like MSI, KSW, RXCDR, DRIM, DRIc. GCLK affects HOd. Link alarms affect site availability and voice qualitye. XBL alarm affects acknowledgement of OOS CIC

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8. STATISTICS ANALYSIS PROCEDURE

Statistics Tree Diagram

BAD GOOD

Paging No Response SDCCH Access Failure Rate

MSC Assignment Attempt Rate(MA_REQ_FROM_MSC)

CONN Refused

SD RF Loss

Cipher Mode Fail

(TSMI, IMSI)

TCH Blocking

TCH Assignment Success

Call Setup Sucess Rate

TCH RF Loss Rate

Inter-BSS HO Loss

Intra-BSS HO Loss

Intra-cell HO Loss

HO Loss Rate

Drop Call Rate

Call Sucess Rate

MSC TCH Connection Rate

Firstly, we need to understand account teams and customer performanceequation.

Problem Identification from Statistics1. per carrier on HW, external interference, channel interference, coverage

a. PATH_BALANCE for faulty hardware (Every 3 days) b. IOI for external interference and bad channel assignment (Every Day) c. BER for external interference and bad channel assignment (Every Day)

d. TCH_RF_LOSS for faulty hardware and bad channel assignment (Every Day) e. CHAN_REQ_FAIL_ROLL for faulty hardware and BCCH and SDCCH coverage footprint

difference (Every Day) 2. per cell on usage

a. AVAILABLE_TCH and AVAILABLE_SDCCH (Every Day) b. BUSY_SDCCH_MAX, SDCCH Blocking for faulty hardware (Every Day) c. SDCCH_CONGESTION and BUSY_SDCCH_MEAN for phantom RACH (Weekly) d. BUSY_TCH_MAX, TCH Blocking for faulty hardware (Every Day) e. OK_ACC_PROC_SUC_RACH for sleeping cell (Every Day) f. No TOTAL_CALL, OUT_INTRA_BSS_ATMPT, OUT_INTER_BSS_ATMPT (Every Day) g. CONN_REFUSED { - IMSI_DETACH} for CIC blocking (Weekly) h. cell without any statistics for OOS cell (Every Day)

3. per cell on dual band mobile usage

a. MA_ACCESS_BY_TYPE (Weekly) b. MS_TCH_USAGE_BY_TYPE (Weekly) 4. per cell on Cipher Mode

a. CIPHER_MODE_FAIL (Weekly) 5. per cell on loading

a. BSS GPROC loading mean 70% (Weekly) b. MSC Processor Loading and Subscriber (Weekly) c. RSL TX, RX Utilisation mean 25% (Weekly) d. MTL TX, RX Utilisation mean 20% (Weekly) e. Pages per second (Weekly)

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f. ALLOC_SDCCH, ALLOC_SDCCH_FAIL ,OK_ACC_PROC relationship (Weekly) g. HO per call (Weekly)

6. per cell on paginga. PCH_PAGE_Q_DISCARD (Weekly)

7. per cell for BCCH and BSIC planninga. INV_EST_CAUSE_RACH and BAD_HO_REFNUM_MS (Weekly)

8. per cell inter-BSS HO monitor inga. OUT_INTER_BSS_MS_FAIL + OUT_INTER_BSS_MS_LOST = HP_MSC_REQ_FAIL

(not include blocking) (Weekly) b. OUT_INTER_BSS_MS_ATMPT = HO_MSC_REQ_FAIL + HO_MSC_REQ_OK (Weekly)

Below all are daily task:9. evaluate target

a. calculate system total call, total loss, ho loss, rf loss, drop call%b. calculate how many total loss reduction is required to achieve the goalc. do (b) again for other statistics

10. select worst cells and BSCsd. pick worst 20 cells and worst 5 BSCs

11. per cell on TCH Assignmenta. CONN_REQ_TO_MSC

b. MA_REQ_FROM_MSC, CONN_REFUSED { - IMSI_DETACH}, if CONN_REFUSED ishigh, MSC procedure is required.

c. MA_CMD_TO_MS_BLKD, MA_CMD_TO_MSd. MA_FAIL_FROM_MS, MA_COMPLETE_TO_MSC (same as TOTAL_CALL)

12. per cell on HO Causea. OUT_HO_CAUSE

13. per cell on HO Failurea. OUT_INTRA_BSS_HO_FAIL, OUT_INTER_BSS_HO_FAIL, IN_INTRA_BSS_HO_FAIL

and IN_INTER_BSS_MS_NO_SEIZE for ho failues14. per cell on TCH_RF_LOSS, SD_RF_LOSS, HO Loss

a. TCH_RF_LOSS, OUT_INTRA_BSS_HO_REQ, OUT_INTRA_BSS_HO_ATMPT,OUT_INTER_BSS_HO_REQ, OUT_INTER_BSS_HO_ATMPT

b. SD_RF_LOSS and HO_LOSS relationship on cell coverage

c. OUT_INTER_BSS_HO_LOSTMS, OUT_INTRA_BSS_HO_LOSTMS,OUT_INTRA_CELL_HO_LOSTMS

For hardware fix, it usually takes 3 days to fix, hence we suggest to review those statistics every3 days. For system loading and usage, we will visit them once in a week.Weekly and every 3 days statistics should be reviewed when that corrective action is done.

Special RequestFor growth planning per cell on blocked call setup, we can use ALLOC_TCH_FAIL –HO_FAIL_NO_RESUORCES_INTRA_BSS - HO_FAIL_NO_RESUORCES_INTER_BSS -HO_FAIL_NO_RESUORCES_INTRA_CELL to estimate expanded network total calls.

For coverage analysis and improve MSC connection rate, we can use per LAC

ACCESS_PER_RACH – PAGING_RESPONSE. Difference tells us how many no page reponses.

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9. DRIVE TEST

9.1. Drive Test Reminder

i. prepare cell definition fileii. 2mins per calliii. 10-15mins per log fileiv. force to appropriate band (GSM only, DCS only or Dual)v. mark benchmark route per log file in mapvi. mark on maps about (a) drop call (b) weak coverage (c) lot of rxquality (d)

bad coveragevii. fill in drive test problem sheet

9.2. Drive Test Log Investigation Consideration

General TEMS Log Investigation Concern1. check undecoded BCCH – this affects RF loss and creates log of ping pong

handover 2. decoded neighbor but no handover is attempted – due to missing neighbor or

incorrect external neighbor path3. focus on drop call and rxqual greater than 4 for non-hopping, 5 for hopping for

at least 4 seconds4. look for handover failure – investigation target cell assigned ARFCN/MA from

ASSIGNMENT COMMAND and HANDOVER COMMAND5. mark down weak coverage area, no dominant server, say less than –85dBm6. mark down highly overlapped area

Besides, be careful that when you see a decoded cell, that cell is not definitely aneighbor of serving, it can be due to serving cell having a neighbor which hassame BCCH as decoded cell.

Note: (a) Focus on new site database(b) Due to CCB, no SFH can be deployed(c) Dedicated ARFCN/MA is different from BCCH(d) After Assignment and Handover, the cell ID may not be updated yetdue to serious rxquality at DL.

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10. FREQUENY PLANNING

10.1. BCCH and BSIC planning criteria

a. Cells have same BCCH and BSIC that increases TEMS log review

troublesome.b. Nearby cells have same BCCH:BSIC with ARFCN:BSIC.c. Nearby cells have adjacent BCCH with ARFCN and same BSIC.

10.2. Frequency Assignment Criteria

Non-hopping Case

Hopping Case for non-BCCH

servingcell

servingcell

can’t be co- or ad -cahannel adjacent

channelco-

channel

adjacentchannel

co-channel

BCCH in hopping case is same as the non-hopping case.

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10.3. Frequency Retune Procedure

Frequencies can be grouped into 5 types, they are:-a. same site co- and adj-channel to BCCHb. adjacent site co- and adj-channel to BCCH

c. adjacent site co-channel to ARFCNd. same site co-channel to ARFCNe. same site adj-channel to ARFCNf. adjacent site adj-channel to ARFCNg. others ARFCN

Priority of ARFCN retune is from g. to e. for fix and BBH, from g. to d. for SFH. If no available ARFCN can be found, site planning need to be reviewed.Besides, 400k separation is required for CCB.58, 70 shouldn’t be used for BCCH.MCell generates UL interference on channel 50 and 56.

11. ADD NEIGHBOR CRITERIA

In general, LOS and 2nd Round Interferer will be added as neighbor; however, for 3rd Round, this is very network dependant. field knowledge is required to makethe decision.

servingcell

LOS interferer 3

r Round

Interferer 2

nRound

Interferer

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12. HIGH RISE BUILDING COVERAGE

Introduce high rise building coverage must make sure to have good streetcoverage.

High Rise Building – provide high level (likely above 8th floor) high rise buildingcoverage

盄 High Rise Building

Macro

Micro

Macro – provide low floors and street level coverageMicro – provide street level and indoor coverage

13. MAXIMUM SYSTEM CONFIGURATION

It is important to understand how system grows from phase to phase. It can bedescribed in 3 phases.

Phase 1: Only macro layer, antenna located at tower top with small downtilt. Antenna uses large vertical beam-width.

Phase 2: Start to introduce micro layer, and increase macro cell downtilt andlower macro cell height of macro antenna.

Phase 3: Introduce high rise building coverage to office building and hotel. Beforedeploying this kind of coverage, street level coverage MUST be strong enough

(likely more than –75dBm) to protect interference from high rise buildingcoverage.

For a mature network which its system rxlevel has reach average –75dBm, it istime for us to deploy SFH to expand system capacity.

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14. HDPC SETTING TEMPLATE

14.1. TX Power and Power Control

TX Power Parameter

CurrentSetting

SuggestSetting

Reason

max_tx_ms

max_tx_bts

Downlink Power Control due to Level

Parameter CurrentSetting

SuggestSetting

Reason

decision_alg_num

bts_power_control_allowed

bts_p_con_ack(TIMER)

bts_p_con_interval(TIMER)

pow_inc_step_size

pow_red_step_size

rxlev_dl_pc, hreqave

rxlev_dl_pc, hreqt

decision_1_dl_rxlev_av_p

l_rxlev_dl_p

u_rxlev_dl_p

decision_1_n1

decision_1_p1

decision_1_n2

decision_1_p2

Downlink Power Control due to Quality


SuggestSetting

Reason

decision_alg_num

bts_power_control_allowed

bts_p_con_ack(TIMER)

bts_p_con_interval(TIMER)

pow_inc_step_size

pow_red_step_size

rxqual_dl_pc, hreqave

rxqual_dl_pc, hreqt

rxqual_dl_pc,qual_weight

decision_1_dl_rxqual_ av_p

l_rxqual_dl_pu_rxqual_dl_p

decision_1_n3

decision_1_p3

decision_1_n4

decision_1_p4

w_qual

Uplink Power Control due to Level


SuggestSetting

Reason

decision_alg_num

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ms_power_control_allowed

ms_p_con_ack

ms_p_con_interval

pow_inc_step_size

pow_red_step_size

rxlev_ul_pc, hreqave

rxlev_ul_pc, hreqt

decision_1_ul_rxlev_av_p

l_rxlev_ul_p

u_rxlev_ul_p

decision_1_n1

decision_1_p1

decision_1_n2

decision_1_p2

Uplink Power Control due to Quality


SuggestSetting

Reason

decision_alg_num

ms_power_control_allowed

ms_p_con_ack

ms_p_con_intervalpow_inc_step_size

pow_red_step_size

rxqual_ul_pc, hreqave

rxqual_ul_pc, hreqt

rxqual_ul_pc,qual_weight

decision_1_ul_rxqual_ av_p

l_rxqual_ul_p

u_rxqual_ul_p

decision_1_n3

decision_1_p3

decision_1_n4

decision_1_p4

w_qual

Data and Hopping Quality Power Control


SuggestSetting

Reason

data_qual_flag

l_rxqual_dl_p_data

l_rxqual_ul_p_data

hop_qual_enabled

l_rxqual_dl_p_hopping

l_rxqual_ul_p_hopping

Standard MS HO Power, MS Ho Power Level based on Path Loss Calculations (GSR3)


SuggestSetting

Reason

handover_power_level

use_derived_ho_power 0 1 Reduce MS UL power and interference

Optimised Power Control (GSR4)


SuggestSetting

Reason

dyn_step_adj

dyn_step_adj_fmpr

pow_inc_step_size_dl

pow_inc_step_size_ul

pow_red_step_size_dl

pow_red_step_size_ul

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Oscillation Prevention for MS Power Control


SuggestSetting

Reason

mspwr_alg

Rapid MS Power Down

Parameter

Current

Setting

Suggest

Setting Reasonrpd_pwr_down

rpd_period (TIMER)

rpd_trigger

rpd_offset

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14.2. Handover Inter-cell Handover


SuggestSetting

Reason

inter_cell_handover_allowed

Intra-cell Handover


SuggestSetting

Reason

intra_cell_handover_allowed

ho_ack (TIMER)

hop_count

hop_count_ timer

Uplink Quality


SuggestSetting

Reason

ul_rxqual_ho_allowed

rxqual_ul_ho, hreqave

rxqual_ul_ho, hreqt

rxqual_ul_ho,qual_weight

rxqual_ul_ho,qual_pwr_flag

rxqual_ul_ho,qual_margin

rxqual_ul_ho,adj_qual_margin

decision_1_ul_rxqual_ av_h

l_rxqual_ul_h

u_rxqual_ul_h

decision_1_n6

decision_1_p6

w_qual

Uplink Interference


SuggestSetting

Reason

interfer_ho_allowed

rxlev_ul_ho, hreqave

rxlev_ul_ho, hreqt

rxlev_ul_ho,qual_margin

rxlev_ul_ho,adj_qual_margin

decision_1_ul_rxlev_ av_ih

u_rxlev_ul_ih

decision_1_n7

decision_1_p7

Downlink Quality


SuggestSetting

Reason

dl_rxqual_ho_allowed

rxqual_dl_ho, hreqave

rxqual_dl_ho, hreqt

rxqual_dl_ho,qual_weight

rxqual_dl_ho,qual_pwr_flag

rxqual_dl_ho,

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qual_margin

rxqual_dl_ho,adj_qual_margin

decision_1_dl_rxqual_ av_h

l_rxqual_dl_h

u_rxqual_dl_h

decision_1_n6

decision_1_p6

w_qual

Downlink Interference


SuggestSetting

Reason

interfer_ho_allowed

rxlev_dl_ho, hreqave

rxlev_dl_ho, hreqt

rxlev_dl_ho,qual_margin

rxlev_dl_ho,adj_qual_margin

decision_1_dl_rxlev_ av_ih

u_rxlev_dl_ih

decision_1_n7

decision_1_p7

Uplink Level


SuggestSetting

Reason

ul_rxlev_ho_allowed

rxlev_ul_ho, hreqave

rxlev_ul_ho, hreqt

decision_1_ul_rxlev_ av_h

l_rxlev_ul_h

u_rxlev_ul_h

deicion_1_n5decision_1_p5

Downlink Level


SuggestSetting

Reason

dl_rxlev_ho_allowed

rxlev_dl_ho, hreqave

rxlev_dl_ho, hreqt

decision_1_dl_rxlev_ av_h

l_rxlev_dl_h

u_rxlev_dl_h

decision_1_n5

decision_1_p5

Distance


SuggestSetting

Reason

ms_distance_allowed

rel_tim_adv, hreqave

rel_tim_adv, hreqt

decision_1_tim_adv_av_alg

ms_max_range

decision_1_n8

decision_1_p8

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poor_initial_assignment

timing_advance_period(TIMER)

Define the interval between timing advance changes

Power Budget


SuggestSetting

Reason

pwr_handover_allow

edrxlev_dl_ho, hreqave

rxlev_dl_ho, hreqt

surround_cell,hreqave

decision_1_pbgt_rxlev_av_h

decision_1_ncell_rxlev_av_h_calc

max_tx_ms (servingcell)

ms_tx_pwr_max_def (internal neighbor default)

ms_tx_pwr_max_cell(external neighbor)

use_neighbor_pbgt_ hreqave

1

Data and Hopping Quality Handover Control


SuggestSetting

Reason

data_qual_flag

l_rxqual_dl_h_data

l_rxqual_ul_h_data

hop_qual_enabled

l_rxqual_dl_h_hopping

l_rxqual_ul_h_hopping

14.3. Multiband

Multiband Handover


SuggestSetting

Reason

mb_preference

phase2_classmark_ allowed

early_classmark_sending

early_classmark_delay

interband_ho_allowed

band_preference

band_preference_mode

multiband_reporting

14.4. MiscellaneousCriteria 1


SuggestSetting

Reason

rxlev_min_def 5 rxlev_min_def (internal neighbor default)

rxlev_min_cell 5 rxlev_min_cell (external neighbor)

Criteria 2


SuggestSetting

Reason

ho_margin_def 4,5

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Neighboring Cell Processing


SuggestSetting

Reason

ncell_pro 0

disuse_cnt_hreqave 0

ho_only_max_pwr 1

neighbor_journal 0

worse_neighbor_ho 0

Alternative Processing of Rxqual Measurements


SuggestSetting

Reason

alt_qual_proc 0 0 Quality Band Unit

Broadcast Control Channel Allocation (BA) Reinitialization


SuggestSetting

Reason

ba_alloac_proc 1

Missing Report


SuggestSetting

Reason

missing_rpt 0 0 Waiting for the actual data

Handover Timer


SuggestSetting

Reason

handover_recongnized_period

bssmap_t7

Link Disconnection


SuggestSetting

Reason

radio_link_timeout

rr_t3109

link_about_to_fail

link_fail

full_pwr_rfloss

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15. TOOLS AVAILABLE

COP – Event Counting Tool, Call Trace Product, Generic Look Up, Cell Analysis Tool 2

TEMS and SafcoK1103

Web StatisitcsNetPlanBSS DatabaseGEP

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16. PROBLEM ROOT CAUSE

16.1. High SDCCH Blocking

HIGH SD BLOCKING

BUSY_SD_MAX=MAX CONFIGUREDSD

Find faulty TSfrom BER statsor check alarm

SD_MEAN_HOCDINGTIME CONVERGES to

T3101

May due to Phantom RACH and HO access burst, checkany same ARFCN and BSICPath Imbalance (SDCCH not on BCCH carrier)

1. Check Neighbor BCCHbeing Interfered

2. Missing Neighbor or incorrectneighbor DB Path,TOTAL_CALL/ALLOC_TCHmay be used

3. Review OK_ACC_PROC likeCM_SERVICE_REQ_CALL,PAGE_RESPONSE,LOCATIONUPDATE

4. Neighbor Cell Outage or own cell carrier outage (l

carrier can have max 2 SD)

5. Coverage Hole Lot of locationUpdate?

END

Is out_INTRA_BSS_HO_RETURN ANDout_INTER_BSS_HO_RETURN A LOT?

END

Check neighbor in_intra_BSS_ho_returnand in_inter_bss_ho_Seize, if high,Check neighbor´s fp

LAC BORDER REDESIGN，

check t3121

8. No TCH BLOKING,ENABLE CHANNEL RECONFIGUPATION

7. Neighbor´s tx power reduced

N

N

N

N

Y

Y

Y

Y

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16.2. High TCH Blocking

HIGH TCH BLOCKING

BUSY_TCH_MAX=MAX_CONFIGURED_TCH

Find faulty TS FromBER Stats or checkalarm

1. Any neighbor´s BCCHinterfered

2. Missing Neighbor or incorrect Neighbor BSIC

3. Its GCLK SHIFT causesneighbor´s bsic undecoded

4. Long timer settinga. intra_BSS HO_rrt3103b. channel release_rrt3109

5. checkout_intra_bss_no_return andout_inter_bss_ho_return, it ishigh

END

6. Check any co-located or closemicro-cell,see whether trafficoffload is possible by optismisigDB

7. If SD has no blocking. May reconfigurechannels or enable channel

reconfiguration feature

Find neighbors which has highin_intra_bss_ho_returnin_inter_bss_ho_seize thencheck its fp

9. Coverage hole and improper DT &orientation

10. Add radio to cell withoutadding new cabinet

8. check adjacent cellbusy_tch_max, if thebusy_tch_max-8>configured TCH

Site reconfiguration

Reduce ho margin andenable congestion relief

N

Y

Y

N

N

Y

11. Increase of single or dualbandMSs.

12. Inappropriate congestion HO setting

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16.3. SDCCH Access Failure Rate

Note: SDCCH blocking is excluded.

LOW SDCCH ACCESS SUCCESSRATE

1. Phantom RACH, check anysame ARFCN and BSIC

2. Path Balance, BCCH is OK batSD carrier not OK

3. Link balance, DB power setting

4. HW Problem, check per carrier chan_req_ms_fail stats. or checkalarm

5. UL Interferencea. External check night line IOIb. High cell sitec. High UL Path Lossd. Co. or adj. – channel interference

6. Excessive TA

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16.4. Handover Failure & Loss

High HO Loss / Failure

1. Poor serving cell HDPCsetting

2. Short rr_t3103 4. Bad fp or external Interference -find %of UL/DL Quality by out_ho_cause

5. HO Failure- Incorrect External Neighbor Database

7. HO failure- Check target cell fp

3. MSC Problem

6. Handover_power_level is max?

8. HW (DRCU, Filter…) Fault 9. Radio Calibration

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16.5. MSC Connection Rate

Low MSC Connection Rate

1. Paging Overflow CausingDiscard

2. Coverage Hole 3. SD RF loss

4. TCH BLOCKING 5. Infrequent Location Update 6. Cipher Mode Fail

8. MSC Connection Refused (MTLCongested)

7. Proper setting onms_txpwr_max_cch andms_txpwr_max_def

9. Call clearing timer (t3109<<radio_link_timeout)causing unclear call generating ULinterference

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SDCCH and TCH RF Loss

High SD & TCH RF LOSS

1. a. Neighbor´s BCCH Interferedb. External Interferencec. Use guard bandd. Use AMPS frequency

2. Hardware(a)Path balance

-idea is 108;≥120 (serious UL Path Loss)

;≤100 (serious DL Path Loss)(b)Radio

-check per carrier RF loss stats(c) Neighbor cell outage(d) GCLK SHIFT

3. Neighbor Blocking-check (OUT_INTRA_BSS_HO_REQ_OUT_INTRA_BSS_HO_ATTEMPT)

or (OUT_INTER_BSS_REQ_TO_MSC_OUT_TNETER_BSS_HO_ATTEMPT)

and check neighbor ′s ALLOC_TCH_FAIL

4. Missing Neighbor, usually by drive test or trace-call

5. Coverage hole, check UL Path Loss

7. SD RF LOSSa. Inconsistent coverage

b. Not enough overlapping

c. No SDCCH HO

8. Poor HDPC setting

9. Is out_intra_bss_ho_returnand out_inter_bss_ho_return

a lot? END

Check neighbor in_intra_bss_ho_return and

in_inter_bss_ho_seize if high, check neighbor ′s fp

N

Y

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16.6. Power Control

Sudden Power Drop1. Incorrect call clearing timer setting2. Faulty hardware

Slow Power Control1. ho_only_max_pwr is turned on2. Bad xx_p_con_ack and xx_p_con_interval

Power Control Window1. Any external interference2. Frequency planning technique3. Speed of power down and up4. Street or indoor coverage

16.7. Handover Problem

Ping Pong Handover 1. Bad radio calibration2. Hardware fault3. Negative handover allowed4. Quality handover without turning on qual_pwr flag5. Especially air combing, one of TX, RX antenna is blocked by building

Negative Handover 1. Neighbor journal2. qual_margin_flag=03. Bad radio calibration between BCCH and non-BCCH4. Turn on ho_magrin_rxqual feature with default value

No and Delay Handover

1. Inappriorate hreqave, hreqt and N & P voting2. Negative handover margin3. Improper setting on handover_recognised_period and bssmap_t74. Improper HO algorithm (Type 4, 6)5. Blocking

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16.8. Others

Low Erlang Usage1. Inappropriate C1, C2 and handover criteria

High Rxqual

1. Adjacent site interference2. Same site MAIO assignment problem3. High internal same site hit rate4. External interference like cordless phone, alarm, BTS hardware

Undecode BSIC1. GCLK shift2. BCCH interfered

Spurious Coverage1. Coverage optimization2. TA control

Killed Paging1. Too many access grant block reserved2. Location area too large

No Paging After Mobile is on certain time period1. MSC Location Update Timer < BSS Location Update Timer

No Call Setup1. LACI is different between BSS and MSC2. Cell BAR

Immediate Assignment Reject1. NO SDCCH

gsm handbook optimize

Documents

high sdcch blocking

drive test reminder

bsic planning criteria

high tch blocking

frequency assignment

neighbor criteria

sdcch access failure

optimisation team structure