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W-Handover and Call Drop Problem Optimization Guide

For internal use only

Product name WCDMA RNP Product version

Confidentiality level For internal use only

Total 202 pages


W-Handover and Optimization Guide(For internal use only)




Prepared by Reviewed by

Jiao Anqiang Xie Zhibin, Dong Yan, Hu Wensu, Wan Liang, Yan Lin, Ai Hua, Xu Zili, and Hua Yunlong Wang Chungui

Date Date


Reviewed by Approved by

Date Date

Huawei Technologies Co., Ltd. All Rights Reserved Revision RecordsDate Version Description Completing Problems. V2.0 W-Handover and Call Drop Author Cai Jianyong, Zang Liang, and Jiao Anqiang





According to V3.0 guide requirements, reorganizing Jiao Anqiang and updating V2.0 guide, focusing more on operability of on-site engineers. All traffic statistics is from RNC V1.5. The update includes: Updating flow chart for handover problem optimization Moving part of call drop due to handover problem to handover optimization part Specifying operation-related part to be more applicable to on-site engineers Updating RNC traffic statistics indexes to V1.5 Integrating traffic statistics analysis to NASTAR of the network performance analysis Optimizing some cases, adding new cases, and removing outdated cases and terms Moving content about handover and call drop to the appendix, and keeping operations related to them in the body Adding explanations to SRB&TRB and RL FAILURE. Adding HSDPA-related description HSDPA handover Zhang Hao and DT/CQT flow, definitions of traffic statistics in Li Zhen HSDPA handover, HSDPA handover problems. Adding algorithms and flows of HSDPA handover. Adding V17-related handover description as below: Changes in signaling flow for H2D HHO Changes in triggering events of H2D and D2H D2H handover in HSDPA based on traffic and timers Wang Dekai

2006-04-30 3.1

2006-10-30 3.11



Description Updating description of HSDPA serving cell and traffic statistics of HSDPA-DCH handover Adding call drop indexes in HSDPA DT/statistics


2007-08-09 2008-12-15

3.2 3.3

Adding HSUPA-related description. Adding MBMS-related description. Yearly review

Zhang Hao WangDekai / Hu Wensu

Contents2.1 Handover Performance Indexes 15 2.2 Call Drop Performance Indexes 18 3.1 DT/CQT Index Optimization Flow 19 3.1.1 SHO DT Index Optimization Flow 19 3.1.2 HHO CQT Flow 23 3.1.3 Inter-RAT Handover CQT Flow 26 3.1.4 DT/CQT Flow for HSDPA Handover 28 3.1.5 DT/CQT Flow for HSUPA Handover 31 3.1.6 SHO Ratio Optimization 31 3.1.7 MBMS Mobility Optimization 31 3.2 Traffic Statistics Analysis Flow 33 3.2.1 Analysis Flow for SHO Traffic Statistics 34 3.2.2 Analysis Flow of HHO Traffic statistics 35 3.2.3 Traffic Statistics Analysis Flow for Inter-RAT Handover 36 3.2.4 Traffic Statistics Analysis for HSDPA Handover 39 3.2.5 Traffic Statistics Analysis for HSUPA Handover 40 3.3 SHO Cost Optimization 42 4.1 Definition of Call Drop and Traffic Statistics Indexes 43 4.1.1 Definition of DT Call Drop 43 4.1.2 Descriptions of Traffic Statistics Indexes 43 4.2 DT/CQT Optimization Flow 44 4.2.1 Call Drop Cause Analysis 45 4.2.2 Frequently-adjusted Non-handover Algorithm Parameters 47 4.2.3 Judgment Tree for Call Drop Causes 48 4.3 Traffic Statistics Analysis Flow 49 4.3.1 Analyzing RNC CDR 50 4.3.2 Analyzing Causes to Call Drop 50 4.3.3 Check Cells 51 4.3.4 Further DT for Relocating Problems 51 4.4 Optimization Flow for Tracing Data 51 4.4.1 Obtaining Single Subscriber Tracing Message 52 4.4.2 Obtaining Information about Call Drop Point 53

4.4.3 Analyzing Call Drop due to SRB Reset 53 4.4.4 Analyzing Call Drop due to TRB Reset 53 4.4.5 Analyzing Abnormal Call Drop 54 4.4.6 Performing CQT to Recheck Problems 54 4.5 Optimization Process for MBMS Call Drop 54 5.1 SHO Problems 56 5.1.1 Over High SHO Rate due to Improper SHO Relative Threshold 56 5.1.2 Delayed Handover due to Over Great Intra-frequency Filter Coefficient 57 5.1.3 Missing Neighbor Cell 58 5.1.4 Redundant Neighbor Cells 62 5.1.5 Pilot Pollution 65 5.1.6 Turning Corner Effect 71 5.1.7 Needlepoint Effect 74 5.1.8 Quick Change of Best server Signal 75 5.2 HHO Problems 77 5.2.1 Intra-frequency Ping-pong HHO due to Improperly Configured 1D Event Hysteresis 77 5.2.2 Delayed Origination of Inter-frequency Measurement due to Improper Inter-frequency Measurement Quantity 78 5.3 Inter-RAT Handover Problems 80 5.3.1 Ping-pong Reselection 80 5.3.2 PS Inter-RAT Ping-pong Handoff 81 5.3.3 Failure in handoff from 3G to the 2G network 82 5.3.4 Inter-RAT Handover Call Drop 84 5.4 Call Drop Problems 91 5.4.1 Over Weak Coverage 91 5.4.2 Uplink Interference 92 5.4.3 Abnormal Equipment 95 5.5 HSDPA-related Problems 97 5.5.1 HSDPA Handover Problems 97 5.5.2 HSDPA Call Drop 98 5.6 HSUPA Problems 100 7.1 SRB&TRB Reset 102 7.1.1 RAB 102 7.1.2 SRB 103 7.2 RL FAILURE 105 7.3 SHO Flow 110 7.3.1 Analyzing Signaling Flow for Adding Radio Link 110 7.3.2 Analyzing Signaling Flow for Deleting Radio Link 113 7.3.3 Analyzing Signaling Flow for Adding and Deleting Radio Link 114

7.3.4 SHO Algorithm 117 7.4 Ordinary HHO Flow 124 7.4.1 Ordinary HHO (lur Interface and CELL_DCH State) 124 7.4.2 Inter-CN HHO Flow 126 7.5 HHO Algorithm 129 7.5.1 Intra-frequency HHO Algorithm 129 7.5.2 Inter-frequency HHO Algorithm 129 7.6 Concept and Classification of HSDPA Handover 131 7.6.1 Concept of HSDPA Handover 131 7.6.2 Classification of HSDPA Handover 131 7.6.3 Signaling Flow and Message Analysis of HSDPA Handover 132 7.6.4 HS-PDSCH Serving Cell Update due to DPCH SHO 133 7.6.5 HS-PDSCH Serving Cell Update due to DPCH HHO 140 7.6.6 DPCH Intra-frequency HHO with HS-DSCH Serving Cell Update 141 7.6.7 DPCH Inter-frequency HHO with HS-DSCH Serving Cell Update 142 7.6.8 Handover Between HSDPA and R99 144 7.6.9 Handover between HSDPA and GPRS 153 7.6.10 Direct Retry of HSDPA 153 7.6.11 Switch of Channel Type 155 7.7 Concept and Classification of HSUPA Handover 158 7.7.1 Basic Concepts 158 7.7.2 Classification of HSUPA Handover 159 7.7.3 Signaling Flow and Message Analysis of HSUPA Handover 159 7.7.4 SHO from a HSUPA Cell to a Non-HSUPA Cell 165 7.7.5 SHO from a Non-HSUPA Cell to a HSUPA Cell 170 7.7.6 Handover Between a HSUPA Cell and a GSM/GPRS Cell 173 7.7.7 Direct Retry of HSUPA 173 7.7.8 Switch between Channel Types 175 7.8 Handover from WCDMA to GSM 176 7.9 Handover from GSM to WCDMA 180 7.10 Handover from WCDMA to GPRS 183 7.11 Handover from GRPS to WCDMA 187 7.12 Parameters of Handover from 3G to 2G Network 190 7.13 Data Configuration for Supporting Bi-directional Roaming and Handover Between WCDMA and GSM/GPRS 193


SHO DT data analysis flow 20 Optimization flow for HHO CQT 25 Inter-RAT handover CQT flow 27 DT/CQT flow for HSDPA handover 30 Movement of the MBMS UE between PTM cells 31 Analysis flow for handover traffic statistics data 34 Voce inter-RAT outgoing handover flow 37 Flow chart for analyzing call drop 45 Judgment tree for call drop causes 48 Flow for analyzing call tracing 52 SHO relative threshold 57 Signaling flow recorded by UE before call drop 59 Scrambles recorded by UE active set and scanner before call drop 59 Scrambles in UE active set before call drop 60 UE intra-frequency measurement control point before call drop 61 Analyzing signaling of UE intra-frequency measurement control before call drop 61 Confirming missing neighbor cell without information from scanner 62 Location relationship of 2G redundant neighbor cells 64 Pilot pollution near Yuxing Rd. 65 Best ServiceCell near Yuxing Rd. 65 The 2nd best ServiceCell near Yuxing Rd. 66 The 3rd best ServiceCell near Yuxing Rd. 66 The 4th best ServiceCell near Yuxing Rd. 67 Composition of pilot pollution near Yuxing Rd. 67 RSSI near Yuxing Rd. 68 RSCP of Best ServiceCell near Yuxing Rd. 68 RSCP of SC270 cell near Yuxing Rd. 69 Pilot pollution near Yuxing Rd. after optimization 70 Best ServiceCell near Yuxing Rd. after optimization 70 RSCP of best ServiceCell near Yuxing Rd. after optimization 71

RSCP of SC270 cell near Yuxing Rd. after optimization 71 Turning corner effect-signals attenuation 72 Turning corner effect-signal attenuation recorded by the UE 72 Turning corner effect-traced signaling recorded by the RNC 73 Needle point-signal variance 74 Call drop distribution of PS384K intra-frequency hard handover 75 Signal distribution of cell152 vs. cell88 (signal fluctuation in handover areas) 76 Reporting 1D event 77 Increasing hysteresis to reduce frequently reporting of 1D event 78 Attenuation relationship of RSCP and Ec/No 79 Indoor 3G RSCP distribution 83 Analyzing weak signals 91 Uplink interference according to RNC signaling 93 Uplink interference according to UE signaling 93 Uplink interference information recorded by UE 94 RTWP variation of the cell 89767 94 RTWP variation of the cell 89768 95 Pilot information recorded by scanner 97 UMTS QoS structure 103 SRB and TRB at user panel 103 Signaling flow for adding radio link 111 Signaling flow for deleting radio link 113 SHO signaling flow for adding and deleting radio link 115 Measurement model 117 Example 1A event and trigger delay 119 Periodic report triggered by 1A event 120 Example of 1C event 121 Example 1D event 122 Restriction from hysteresis to measurement report 122 Example of 1E event 123 Example of 1F event 123

Ordinary HHO flow (lur interface and CELL_DCH state) 125 Ordinary inter-CN HHO flow 127 Intra-NodeB synchronization serving cell update 134 Inter-NodeB synchronization serving cell update 136 Inter-NodeB HS-DSCH cell update after radio link is added 138 Inter-NodeB HS-DSCH cell update during HHO (single step method) 140 DPCH intra-frequency HHO with HS-DSCH serving cell update 142 DPCH inter-frequency H