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W-Handover and Call Drop Problem Optimization Guide For internal use only

2011-01-04 All rights reserved Page 1 of 201

Product name Confidentiality level

WCDMA RNP For internal use only

Product versionTotal 201 pages

3.3

W-Handover and Call Drop Problem Optimization

Guide(For internal use only)

Prepared by Jiao Anqiang Date 2006-03-16

Reviewed by Xie Zhibin, Dong Yan, Hu

Wensu, Wan Liang, YanLin, Ai Hua, Xu Zili, and

Hua Yunlong

Date

Reviewed by Wang Chungui Date

Approved by Date

Huawei Technologies Co., Ltd.

All Rights Reserved


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Revision Records

Date Version Description Author

2005-02-01 2.0 Completing V2.0 W-Handover and Call Drop

Problems.

Cai Jianyong,

Zang Liang, and

Jiao Anqiang

2006-03-16 3.0

According to V3.0 guide requirements,

reorganizing 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removing outdated cases and terms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.

Jiao Anqiang

2006-04-30

3.1

Adding HSDPA-related description HSDPA

handover DT/CQT flow, definitions of traffic

statistics in HSDPA handover, HSDPA handover

problems. Adding algorithms and flows of HSDPA

handover.

Zhang Hao and

Li Zhen


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Date Version Description Author

2006-10-30

3.11

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

Updating description of HSDPA serving cell and

traffic statistics of HSDPA-DCH handover

Adding call drop indexes in HSDPA DT/statistics

Wang Dekai

2007-08-09 3.2 Adding HSUPA-related description. Zhang Hao

2008-12-153.3

Adding MBMS-related description.

Yearly review

WangDekai /

Hu Wensu


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2008-12-22 All rights reserved Page4 , Total201

Contents

1 Introduction .................................................................................................................................. 14

2 Handover and Call Drop Performance Indexes ........................................................................ 162.1 Handover Performance Indexes .......................................................................................... 16

2.2 Call Drop Performance Indexes .......................................................................................... 19

3 Handover Index Optimization ..................................................................................................... 203.1 DT/CQT Index Optimization Flow ........................................................................................ 20

3.1.1 SHO DT Index Optimization Flow ............................................................................. 20

3.1.2 HHO CQT Flow ......................................................................................................... 24

3.1.3 Inter-RAT Handover CQT Flow ................................................................................. 27

3.1.4 DT/CQT Flow for HSDPA Handover ......................................................................... 29

3.1.5 DT/CQT Flow for HSUPA Handover ......................................................................... 32

3.1.6 SHO Ratio Optimization ............................................................................................ 32

3.1.7 MBMS Mobility Optimization ..................................................................................... 32

3.2 Traffic Statistics Analysis Flow ............................................................................................ 34

3.2.1 Analysis Flow for SHO Traffic Statistics .................................................................... 35

3.2.2

Analysis Flow of HHO Traffic statistics ..................................................................... 363.2.3 Traffic Statistics Analysis Flow for Inter-RAT Handover ........................................... 37

3.2.4 Traffic Statistics Analysis for HSDPA Handover ....................................................... 40

3.2.5 Traffic Statistics Analysis for HSUPA Handover ....................................................... 41

3.3 SHO Cost Optimization ....................................................................................................... 43

4 CDR Index Optimization .............................................................................................................. 444.1 Definition of Call Drop and Traffic Statistics Indexes .......................................................... 44

4.1.1 Definition of DT Call Drop ......................................................................................... 44

4.1.2 Descriptions of Traffic Statistics Indexes .................................................................. 44

4.2 DT/CQT Optimization Flow .................................................................................................. 45

4.2.1 Call Drop Cause Analysis ......................................................................................... 46

4.2.2 Frequently-adjusted Non-handover Algorithm Parameters ...................................... 48

4.2.3 Judgment Tree for Call Drop Causes ........................................................................ 494.3 Traffic Statistics Analysis Flow ............................................................................................ 50

4.3.1 Analyzing RNC CDR ................................................................................................. 51

4.3.2 Analyzing Causes to Call Drop ................................................................................. 51

4.3.3 Check Cells ............................................................................................................... 52

4.3.4 Further DT for Relocating Problems ......................................................................... 52

4.4 Optimization Flow for Tracing Data ..................................................................................... 52

4.4.1 Obtaining Single Subscriber Tracing Message ......................................................... 53

4.4.2 Obtaining Information about Call Drop Point ............................................................ 53

4.4.3 Analyzing Call Drop due to SRB Reset ..................................................................... 54

4.4.4 Analyzing Call Drop due to TRB Reset ..................................................................... 54

4.4.5 Analyzing Abnormal Call Drop .................................................................................. 54

4.4.6 Performing CQT to Recheck Problems ..................................................................... 55


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4.5 Optimization Process for MBMS Call Drop ......................................................................... 55

5 FAQs Analysis .............................................................................................................................. 565.1 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 .................. 575.1.3 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 ...................................................................................................... 785.3 Inter-RAT Handover Problems ............................................................................................ 80

5.3.1 Ping-pong Reselection .............................................................................................. 805.3.2 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

6 Summary ..................................................................................................................................... 101

7 Appendix ..................................................................................................................................... 1027.1 SRB&TRB Reset ............................................................................................................... 102

7.1.1 RAB ......................................................................................................................... 102

7.1.2 SRB ......................................................................................................................... 103

7.2 RL FAILURE ...................................................................................................................... 104

7.3 SHO Flow .......................................................................................................................... 109

7.3.1 Analyzing Signaling Flow for Adding Radio Link ..................................................... 109

7.3.2 Analyzing Signaling Flow for Deleting Radio Link ................................................... 112

7.3.3 Analyzing Signaling Flow for Adding and Deleting Radio Link ............................... 113

7.3.4 SHO Algorithm ........................................................................................................ 116

7.4 Ordinary HHO Flow

........................................................................................................... 123

7.4.1 Ordinary HHO (lur Interface and CELL_DCH State) ............................................... 123

7.4.2 Inter-CN HHO Flow ................................................................................................. 125

7.5 HHO Algorithm .................................................................................................................. 128

7.5.1 Intra-frequency HHO Algorithm ............................................................................... 128

7.5.2 Inter-frequency HHO Algorithm ............................................................................... 128

7.6 Concept and Classification of HSDPA Handover .............................................................. 130

7.6.1 Concept of HSDPA Handover ................................................................................. 130

7.6.2 Classification of HSDPA Handover ......................................................................... 130

7.6.3 Signaling Flow and Message Analysis of HSDPA Handover .................................. 131

7.6.4 HS-PDSCH Serving Cell Update due to DPCH SHO ............................................. 132

7.6.5 HS-PDSCH Serving Cell Update due to DPCH HHO ............................................. 139

7.6.6

DPCH Intra-frequency HHO with HS-DSCH Serving Cell Update .......................... 1407.6.7 DPCH Inter-frequency HHO with HS-DSCH Serving Cell Update .......................... 141


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7.6.8 Handover Between HSDPA and R99 ...................................................................... 143

7.6.9 Handover between HSDPA and GPRS .................................................................. 152

7.6.10 Direct Retry of HSDPA .......................................................................................... 152

7.6.11 Switch of Channel Type ........................................................................................ 154

7.7 Concept and Classification of HSUPA Handover .............................................................. 157

7.7.1 Basic Concepts ....................................................................................................... 157

7.7.2 Classification of HSUPA Handover ......................................................................... 157

7.7.3 Signaling Flow and Message Analysis of HSUPA Handover .................................. 158

7.7.4 SHO from a HSUPA Cell to a Non-HSUPA Cell ..................................................... 164

7.7.5 SHO from a Non-HSUPA Cell to a HSUPA Cell ..................................................... 169

7.7.6 Handover Between a HSUPA Cell and a GSM/GPRS Cell .................................... 172

7.7.7 Direct Retry of HSUPA ............................................................................................ 172

7.7.8 Switch between Channel Types .............................................................................. 174

7.8 Handover from WCDMA to GSM ....................................................................................... 175

7.9 Handover from GSM to WCDMA ....................................................................................... 179

7.10 Handover from WCDMA to GPRS ................................................................................... 182

7.11 Handover from GRPS to WCDMA ................................................................................... 186

7.12 Parameters of Handover from 3G to 2G Network ........................................................... 189

7.13 Data Configuration for Supporting Bi-directional Roaming and Handover Between WCDMA and

GSM/GPRS ............................................................................................................................. 192


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Figures

Figure 3-1 SHO DT data analysis flow .................................................................................................... 21

Figure 3-2 Optimization flow for HHO CQT ............................................................................................. 26

Figure 3-3 Inter-RAT handover CQT flow ................................................................................................ 28

Figure 3-4 DT/CQT flow for HSDPA handover ........................................................................................ 31

Figure 3-5 Movement of the MBMS UE between PTM cells ................................................................... 32

Figure 3-6 Analysis flow for handover traffic statistics data .................................................................... 35

Figure 3-7 Voce inter-RAT outgoing handover flow ................................................................................ 38

Figure 4-1 Flow chart for analyzing call drop .......................................................................................... 46

Figure 4-2 Judgment tree for call drop causes ........................................................................................ 49

Figure 4-3 Flow for analyzing call tracing ................................................................................................ 53

Figure 5-1 SHO relative threshold ........................................................................................................... 57

Figure 5-2 Signaling flow recorded by UE before call drop ..................................................................... 58

Figure 5-3 Scrambles recorded by UE active set and scanner before call drop ..................................... 59

Figure 5-4 Scrambles in UE active set before call drop .......................................................................... 60

Figure 5-5 UE intra-frequency measurement control point before call drop ........................................... 61

Figure 5-6 Analyzing signaling of UE intra-frequency measurement control before call drop ................ 61

Figure 5-7 Confirming missing neighbor cell without information from scanner ..................................... 62

Figure 5-8 Location relationship of 2G redundant neighbor cells ........................................................... 64

Figure 5-9 Pilot pollution near Yuxing Rd. ............................................................................................... 65

Figure 5-10 Best ServiceCell near Yuxing Rd. ........................................................................................ 65

Figure 5-11 The 2nd best ServiceCell near Yuxing Rd. .......................................................................... 66

Figure 5-12 The 3rd best ServiceCell near Yuxing Rd. ........................................................................... 66

Figure 5-13 The 4th best ServiceCell near Yuxing Rd. ........................................................................... 67

Figure 5-14 Composition of pilot pollution near Yuxing Rd. .................................................................... 67

Figure 5-15 RSSI near Yuxing Rd. .......................................................................................................... 68

Figure 5-16 RSCP of Best ServiceCell near Yuxing Rd. ......................................................................... 68

Figure 5-17 RSCP of SC270 cell near Yuxing Rd. .................................................................................. 69


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Figure 5-18 Pilot pollution near Yuxing Rd. after optimization ................................................................ 70

Figure 5-19 Best ServiceCell near Yuxing Rd. after optimization ........................................................... 70

Figure 5-20 RSCP of best ServiceCell near Yuxing Rd. after optimization ............................................. 71

Figure 5-21 RSCP of SC270 cell near Yuxing Rd. after optimization ..................................................... 71

Figure 5-22 Turning corner effect-signals attenuation ............................................................................ 72

Figure 5-23 Turning corner effect-signal attenuation recorded by the UE .............................................. 72

Figure 5-24 Turning corner effect-traced signaling recorded by the RNC .............................................. 73

Figure 5-25 Needle point-signal variance ............................................................................................... 74

Figure 5-26 Call drop distribution of PS384K intra-frequency hard handover ........................................ 75

Figure 5-27 Signal distribution of cell152 vs. cell88 (signal fluctuation in handover areas) ................... 76

Figure 5-28 Reporting 1D event .............................................................................................................. 77

Figure 5-29 Increasing hysteresis to reduce frequently reporting of 1D event ....................................... 78

Figure 5-30 Attenuation relationship of RSCP and Ec/No ...................................................................... 79

Figure 5-31 Indoor 3G RSCP distribution ............................................................................................... 83

Figure 5-32 Analyzing weak signals ........................................................................................................ 91

Figure 5-33 Uplink interference according to RNC signaling .................................................................. 93

Figure 5-34 Uplink interference according to UE signaling ..................................................................... 93

Figure 5-35 Uplink interference information recorded by UE .................................................................. 94

Figure 5-36 RTWP variation of the cell 89767 ........................................................................................ 94Figure 5-37 RTWP variation of the cell 89768 ........................................................................................ 95

Figure 5-38 Pilot information recorded by scanner ................................................................................. 97

Figure 7-1 UMTS QoS structure ........................................................................................................... 102

Figure 7-2 SRB and TRB at user panel ................................................................................................ 103

Figure 7-3 Signaling flow for adding radio link ....................................................................................... 110

Figure 7-4 Signaling flow for deleting radio link ..................................................................................... 112

Figure 7-5 SHO signaling flow for adding and deleting radio link .......................................................... 114

Figure 7-6 Measurement model ............................................................................................................. 116

Figure 7-7 Example 1A event and trigger delay ..................................................................................... 118

Figure 7-8 Periodic report triggered by 1A event ................................................................................... 119

Figure 7-9 Example of 1C event ........................................................................................................... 120

Figure 7-10 Example 1D event ............................................................................................................. 121

Figure 7-11 Restriction from hysteresis to measurement report ........................................................... 121

Figure 7-12 Example of 1E event .......................................................................................................... 122

Figure 7-13 Example of 1F event .......................................................................................................... 122


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Figure 7-14 Ordinary HHO flow (lur interface and CELL_DCH state) .................................................. 124

Figure 7-15 Ordinary inter-CN HHO flow .............................................................................................. 126

Figure 7-16 Intra-NodeB synchronization serving cell update .............................................................. 133

Figure 7-17 Inter-NodeB synchronization serving cell update .............................................................. 135

Figure 7-18 Inter-NodeB HS-DSCH cell update after radio link is added ............................................. 137

Figure 7-19 Inter-NodeB HS-DSCH cell update during HHO (single step method) .............................. 139

Figure 7-20 DPCH intra-frequency HHO with HS-DSCH serving cell update ...................................... 141

Figure 7-21 DPCH inter-frequency HHO with HS-DSCH serving cell update ...................................... 142

Figure 7-22 handover from HSDPA to R99 ........................................................................................... 143

Figure 7-23 Intra-frequency handover from R99 to R5 ......................................................................... 143

Figure 7-24 DPCH SHO with handover from HSDPA to R99 (inter-NodeB) ......................................... 145

Figure 7-25 DPCH SHO with handover from R99 to HSDPA ............................................................... 146

Figure 7-26 Inter-NodeB SHO with handover from HSDPA to R99 (V17) ............................................ 147

Figure 7-27 Intra-frequency HHO with handover from R5 to R99 ........................................................ 148

Figure 7-28 Intra-frequency HHO with handover form R99 to R5 ........................................................ 148

Figure 7-29 Intra-frequency HHO with handover from R5 to R99 (V17) ............................................... 149

Figure 7-30 Inter-frequency HHO from HS-PDSCH to DCH ................................................................. 150

Figure 7-31 Inter-frequency HHO from DCH to HS-PDSCH ................................................................. 151

Figure 7-32 Handover between HSDPA and GPRS ............................................................................. 152Figure 7-33 Flow for direct retry during setup of a service .................................................................... 153

Figure 7-34 Direct retry triggered by traffic ........................................................................................... 153

Figure 7-35 Switch of channel type ....................................................................................................... 155

Figure 7-36 Intra-frequency SHO between two HSUPA cells ............................................................... 159

Figure 7-37 Signaling for HSUPA cell update triggered by a 1D event ................................................. 159

Figure 7-38 Signaling for HSUPA cell update triggered by a 1D event (reported by the monitor set) .. 160

Figure 7-39 Intra-frequency HHO between two HSUPA cells ............................................................... 160

Figure 7-40 Signaling for intra-frequency HHO between two HSUPA cells .......................................... 161

Figure 7-41 Inter-frequency HHO between two HSUPA cells ............................................................... 161

Figure 7-42 Signaling for inter-frequency HHO between two HSUPA cells .......................................... 162

Figure 7-43 Inter-RNC HSUPA handover .............................................................................................. 163

Figure 7-44 SHO from a HSUPA cell to a non-HSUPA cell ................................................................... 165

Figure 7-45 Addition of an R99 cell when the service is on the E-DCH ................................................ 166

Figure 7-46 Intra-frequency HHO from a HSUPA cell to a non-HSUPA cell ......................................... 167

Figure 7-47 Signaling for intra-frequency HHO from a HSUPA cell to a non-HSUPA cell .................... 167


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Figure 7-48 Inter-frequency HHO from a HSUPA cell to a non-HSUPA cell ......................................... 168

Figure 7-49 Signaling for inter-frequency HHO from a HSUPA cell to a non-HSUPA cell .................... 169

Figure 7-50 SHO from a non-HSUPA cell to a HSUPA cell ................................................................... 170

Figure 7-51 SHO from a non-HSUPA cell to a HSUPA cell (triggered by a 1B event) .......................... 170

Figure 7-52 Intra-frequency HHO from a non-HSUPA cell to a HSUPA cell ......................................... 171

Figure 7-53 Signaling for intra-frequency HHO from a non-HSUPA cell to a HSUPA cell .................... 171

Figure 7-54 Inter-frequency HHO from a non-HSUPA cell to a HSUPA cell ......................................... 172

Figure 7-55 Direct retry from an R99 cell to a HSUPA cell ................................................................... 173

Figure 7-56 Direct retry from a HSUPA cell to an R99 cell ................................................................... 173

Figure 7-57 Direct retry from a HSUPA cell to another HSUPA cell ...................................................... 174

Figure 7-58 Switch between HSUPA channel types ............................................................................. 174

Figure 7-59 Signaling flow for handover from WCDMA to GSM ........................................................... 176

Figure 7-60 Tracing signaling of handover from WCDMA to GSM ....................................................... 176

Figure 7-61 Signaling flow for handover from GSM to WCDMA ........................................................... 179

Figure 7-62 Tracing signaling of handover from GSM to WCDMA ....................................................... 180

Figure 7-63 Flow of handover from WCDMA to GPRS (1) ................................................................... 183

Figure 7-64 Flow of handover from WCDMA to GPRS (2) ................................................................... 183

Figure 7-65 Tracing signaling of handover from WCDMA to GPRS ..................................................... 184

Figure 7-66 Signaling flow for handover from GPRS to WCDMA (1) ................................................... 186Figure 7-67 Signaling flow for handover from GPRS to WCDMA (2) ................................................... 187

Figure 7-68 Data configuration in the location area cell table ............................................................... 193

Figure 7-69 Data configuration of neighbor cell configuration table ...................................................... 194

Figure 7-70 Configuration table for external 3G cells ........................................................................... 196

Figure 7-71 Configuration table for GSM inter-RAT neighbor cells ....................................................... 197

Figure 7-72 Configuration table for 2G reselection parameters ............................................................ 198

Figure 7-73 Parameter configuration table for inter-RAT handover ...................................................... 199


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Tables

Table 2-1 Handover performance indexes and reference values ............................................................ 16

Table 2-2 HSDPA handover performance indexes and reference value ................................................. 17

Table 2-3 HSUPA handover performance indexes and reference value ................................................. 17

Table 2-4 CDR index and reference value .............................................................................................. 19

Table 3-1 SHO failure indexes ................................................................................................................. 36

Table 3-2 HHO failure indexes ................................................................................................................. 36

Table 3-3 Traffic statistics indexes of CS inter-RAT handover preparation failure .................................. 38

Table 3-4 Traffic statistics indexes of PS inter-RAT outgoing handover failure ....................................... 39

Table 4-1 Types of CDR indexes ............................................................................................................. 45

Table 4-2 Thresholds of EcIo and Ec ....................................................................................................... 46

Table 4-3 Traffic statistics indexes for analyzing causes to call drop ...................................................... 51

Table 5-1 Relationship between the filter coefficient and the corresponding tracing time ...................... 58

Table 5-2 2G handover times .................................................................................................................. 63

Table 5-3 Best servers and other cells .................................................................................................... 67

Table 7-1 Timers and counters related to the synchronization and asynchronization ........................... 104

Table 7-2 Timers and counters related to call drop at lub interface ....................................................... 107

Table 7-3 Flow of serving cell update triggered by different events in SHO .......................................... 132

Table 7-4 Scenarios of handover between HSDPA and R99 (V17) ...................................................... 144

Table 7-5 Handover between two HSUPA cells ..................................................................................... 158

Table 7-6 Handover between a HSUPA cell and a non-HSUPA cell ..................................................... 163

Table 7-7 Parameters of handover from 3G to 2G ................................................................................ 190


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W-Handover and Call Drop Problem Optimization Guide

Key words:

Handover, call drop, and optimization

Abstract:

This document, aiming at network optimization of handover success rate and call drop rate, detailsthe specific network operation flow. In addition, it analyzes common problems during network

optimization.

Acronyms and abbreviations:

Acronyms and Abbreviations Full Spelling

AMR Adaptive MultiRate

CHR Call History Record

CDR Call Drop Rate

DCCC Dynamic Channel Configuration Control

RAN Radio Access Network

RNP Radio Network Planning

SRB Signaling Radio Bearer

TRB Traffic Radio Bearer

SHO Soft Handover

HHO Hard Handover

PCH Physical Channel

CN Core Network

O&M Operation and maintenance

MNC Mobile Network Code

MCC Mobile Country Code

LAC Location Area Code

CIO Cell Independent Offset

HSUPA High Speed Uplink Packet Access

E-DCH Enhanced uplink Dedicated Channel

E-AGCH E-DCH Absolute Grant Channel


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E-RGCH E-DCH Relative Grant Channel


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1 IntroductionThis document aims to meet the requirements by on-site engineers on solving handover andcall drop problems and making them qualified during network optimization. It describes themethods for evaluating network handover and call drop performance, testing methods,troubleshooting methods, and frequently asked questions (FAQs).

The appendix provides fundamental knowledge, principles, related parameters, and dataprocessing tools about handover and call drop. This document serves to network KPIoptimization and operation and maintenance (O&M) and helps engineers to locate and solvehandover and call drop problems.

The RRM algorithms and problem implementation in this document are based on V16 RNC. Ifsome RRM algorithms are based on V17 RNC, they will be highlighted. HSUPA is introduced inV18 RNC, so the algorithms related to HSUPA are based on RNC V18. The following sectionsare updated:

Traffic Statistics Analysis for HSDPA Handover

Handover Between HSDPA and R99

Direct Retry of HSDPA

Switch of Channel Type

Actually handover is closely relevant to call drop. Handover failure probably leads to call drop.Therefore handover-caused call drop is arranged in handover success rate optimization part.The CDR optimization includes all related to call drop except handover-caused call drop.

This document does not include usage of related tools.

This document includes the following 12 chapters:

1 Introduction

2 Handover and Call Drop Performance Indexes

3 Handover Index Optimization

4 CDR Index Optimization

5 FAQs Analysis

6 Summary

7 Appendix


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The traffic statistics analysis is based on RNC V1.5 counter. It will be updated upon the updateof RNC counters.


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2 Handover and Call Drop Performance Indexes

2.1 Handover Performance Indexes

According to RNA KPI baseline document, Table 2-1 lists the handover performance indexesand reference values.

Table 2-1Handover performance indexes and reference values

Index Service Statistics methodReference

value

SHO success rate CS&PS DT&Stat. 99%

Intra-frequency HHOsuccess rate

Voice DT&Stat. 90%

VP DT&Stat. 85%

PS UL64K/DL 64K DT&Stat. 85%



Inter-frequency HHOsuccess rate

Voice DT&Stat. 92%

VP DT&Stat. 90%




Inter-RAT handoversuccess rate

Voice handover out DT&Stat. 95%

PS handover out DT&Stat. 92%

SHO ratio N/A DT 35%

SHO cost N/A Stat. 40%


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Table 2-2 lists the HSDPA handover performance indexes and reference value.

Table 2-2HSDPA handover performance indexes and reference value

Index Service Reference value

HSDPA-HSDPA intra-frequencyserving cell update

PS (HSDPA) 99%

HSDPA-HSDPA inter-frequencyserving cell update

PS (HSDPA) 92%

HSDPA-R99 intra-frequency handover PS (HSDPA) 99%

HSDPA-R99 inter-frequency handover PS (HSDPA) 90%

Success rate of R99-to-HSDPA cellhandover

PS (HSDPA) 85%

HSDPA-to-GPRS inter-RAT handover PS (HSDPA) 92%

Note: The HSDPA handover KPIs are to be updated after formal issue by WCDMA&GSM Performance

Research Department.

Table 2-3HSUPA handover performance indexes and reference value


Success rate of inter-cellSHO in HSUPA (includingadding, replacing, anddeleting)

PS (HSUPA)

Success rate of inter-cellSHO serving cell update inHSUPA

PS (HSUPA)

Success rate ofDCH-to-E-DCHreconfiguration in SHOmode (including replacingand deleting)

PS (HSUPA)

Success rate ofE-DCH-to-DCHreconfiguration in SHOmode (including replacingand deleting)

PS(HSUPA)

Success rate of inter-cellintra-frequency HHO inHSUPA

PS (HSUPA)


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Success rate ofintra-frequency HHO from aHSUPA cell to a

non-HSUPA cell

PS (HSUPA)

Success rate ofDCH-to-E-DCHreconfiguration in single-linkmode (the second step ofinter- or intra-frequencyHHO from a non-HSUPAcell to a HSUPA cell)

PS (HSUPA)

Success rate of inter-cellinter-frequency HHO inHSUPA

PS (HSUPA)

Success rate ofinter-frequency HHO from aHSUPA cell to anon-HSUPA cell

PS (HSUPA)

Success rate ofHSUPA-to-GPRS inter-RAThandover

PS (HSUPA) 92%

Note:

The HSUPA handover KPIs are unavailable and to be updated after formal issue by WCDMA&GSM

Performance Department.

Decide the specific value according to project requirements or contract requirements of commercial network


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3 Handover Index Optimization

3.1 DT/CQT Index Optimization Flow

DT and CQT are important to network evaluation and optimization. DT/CQT KPIs act asstandards for verifying networks. Overall DT helps to know entire coverage, to locate missingneighbor cells, and to locate cross-cell coverage. HHO and inter-RAT handover are used incoverage solutions for special scenarios, in while CQT is proper.

The following sections describe the DT/CQT index optimization flow in terms of SHO, HHO, andinter-RAT handover.

3.1.1 SHO DT Index Optimization FlowFigure 3-1 shows the SHO DT data analysis flow.


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Figure 3-1SHO DT data analysis flow

Inputting Analysis DataPerform DT. Collect DT data, related signaling tracing, RNC CHR, and RNC MML scripts.

Obtaining When and Where the Problem Occurs

During the test, SHO-caused call drop might occur or SHO might fail, so record the location andtime for the problem occurrence. This prepares for further location and analysis.


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Missing Neighbor Cell

During the early optimization, call drop is usually due to missing neighbor cell. Forintra-frequency neighbor cells, use the following methods to confirm intra-frequency missingneighbor cell.

Check the active set Ec/Io recorded by UE before call drop and Best Server Ec/Io

recorded by Scanner. Check whether the Best Server scramble recorded byScanner is in the neighbor cell list of intra-frequency measurement control before calldrop. The cause might be intra-frequency missing neighbor cell if all the followingconditions are met:

The Ec/Io recorded by UE is bad.

The Best Server Ec/Io is good.

No Best Server scramble is in the neighbor cell list of measurement control.

If the UE reconnects to the network immediately after call drop and the scramble of

the cell that UE camps on is different from that upon call drop, missing neighbor cellis probable. Confirm it by measurement control (search the messages back from calldrop for the latest intra-frequency measurement control message. Check theneighbor cell list of this measurement control message)

UEs might report detected set information. If corresponding scramble information is

in the monitor set before call drop, the cause must be missing neighbor cell.

Missing neighbor cell causes call drop. Redundant neighbor cells impacts network performanceand increases the consumption of UE intra-frequency measurement. If this problem becomesmore serious, the necessary cells cannot be listed. Therefore pay attention to redundantneighbor cells when analyzing handover problems. For redundant neighbor cells, see 5 .

Pilot Pollution

Pilot pollution is defined as below:

Excessive strong pilots exist at a point, but no one is strong enough to be primary

pilot.

According to the definition, when setting rules for judging pilot pollution, confirm the followingcontent:

Definition of strong pilot

Whether a pilot is strong depends on the absolute strength of the pilot, which ismeasured by RSCP. If the pilot RSCP is greater than a threshold, the pilot is a

strong pilot. Namely, AbsoluteRSCPThRSCPCPICH __ > .

Definition of "excessive"When judging whether excessive pilots exist at a point, the pilot number is thejudgment criteria. If the pilot number is more than a threshold, the pilots at a point

are excessive. Namely, NThNumberCPICH >_

Definition of "no best server strong enough"

When judging whether a best server strong enough exist, the judgment criteria is therelative strength of multiple pilots. If the strength different of the strongest pilot and

the No.)1( +NTh strong pilot is smaller than a threshold, no best server strong

enough exists in the point. Namely,


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lativeRSCPthThst

ThRSCPCPICHRSCPCPICHN Re_)1(1

)__( is more

than NTh

.

lativeRSCPthThst

ThRSCPCPICHRSCPCPICHN Re_)1(1

)__(

is larger than 3.

dBRSCPCPICHRSCPCPICH thst 5)__( 41


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Abnormal Equipment

Check the alarm console for abnormal alarms. Meanwhile analyze traced message, locate theSHO problem by checking the failure message. For help, contact local customer serviceengineers for confirm abnormal equipment.

Reperforming Drive Test and Locating Problems

If the problem is not due to previous causes, perform DT again and collect DT data. Supplementdata from problem analysis.

Adjustment and Implementation

After confirming the cause to the problem, adjust the network by using the following pertinentmethods:

For handover problems caused by pilot pollution, adjust engineering parameters ofan antenna so that a best server forms around the antenna. For handover problemscaused by pilot pollution, adjust engineering parameters of other antennas so thatsignals from other antennas becomes weaker and the number of pilots drops.Construct a new site to cover this area if conditions permit. If the interference is fromtwo sectors of the same NodeB, combine the two cells as one.

For abnormal equipment, consult customer service engineer for abnormal equipment

and transport layer on alarm console. If alarms are present on alarm console,cooperate with customer service engineers.

For call drop caused by delayed handover, adjust antennas to expand the handoverarea, set the handover parameters of 1a event, or increase CIO to enable handoverto occur in advance. The sum of CIO and measured value is used in event

evaluation process. The sum of initially measured value and CIP, as measurementresult, is used to judge intra-frequency handover of UE and acts as cell border inhandover algorithm. The larger the parameter is, the easier the SHO is and UEs inSHO state increases, which consumes resources. If the parameter is small, the SHOis more difficult, which might affects receiving quality.

For needle effect or turning corner effect, setting CIO to 5 dB is proper, but thisincreases handover ratio. For detailed adjustment, see SHO-caused call drop ofFAQs Analysis.

For call drop caused by Ping-pong handover, adjust the antenna to form a best

server or reduce Ping-pong handover by setting the handover parameter of 1B event,which enables deleting a cell in active set to be more difficult. For details, increase

the 1B event threshold, 1B hysteresis, and 1B delay trigger time.

3.1.2 HHO CQT Flow

HHO Types

HHO includes the following types:

Intra-frequency HHO

The frequency of the active set cell before HHO is the same as that of the cell after HHO.

If the cell does not support SHO, HHO might occur. HHO caters for cross-RNC


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intra-frequency handover without lur interface, limited resources at lur interface, and

handover controlled by PS service rate threshold of handover cell. The 1D event ofintra-frequency measurement events determines intra-frequency HHO.

Inter-frequency HHO

The frequency of the active set cell before HHO is different from that of the cell after

HHO. HHO helps to carry out balanced load between carriers and seamless proceeding.Start compression mode to perform inter-frequency measurement according to UEcapability before inter-frequency HHO. HHO judgment for selecting cell depends onperiod measurement report.

Balanced load HHO

It aims to realize balanced load of different frequencies. Its judgment depends on

balanced load HHO.

Inter-frequency coverage usually exists in special scenarios, such as indoor coverage, so CQTare used. The following section details the optimization flow for inter-frequency CQT.

Optimization Flow of HHO CQT

Figure 3-2 shows the optimization flow for HHO CQT.


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Figure 3-2Optimization flow for HHO CQT

Adjustment

The optimization flow for HHO is similar with that of SHO and the difference lies in parameteroptimization.

Confirming inter-frequency missing neighbor cell is similar to that of intra-frequency. When calldrop occurs, the UE does not measure or report inter-frequency neighbor cells. After call drop,the UE re-camps on the inter-frequency neighbor cell.

HHO problems usually refer to delayed handover and Ping-pong handover.

Delayed HHO usually occurs outdoor, so call drop occurs when the UE is moving. There arethree solutions:

Increase the threshold for starting compression mode.

The compression mode starts before inter-frequency or inter-RAT handover. Measure the

quality of inter-frequency or inter-RAT cell by compression mode. Compression modestarts if the CPICH RSCP or Ec/Io meets the conditions. RSCP is usually the triggering

condition.The parameter "inter-frequency measurement quantity" decides to use CPICH Ec/No or

Ec/Io as the measurement target for inter-frequency handover. When setting"inter-frequency measurement quantity", check that the cell is at the carrier coverage

edge or in the carrier coverage center. If intra-frequency neighbor cells lie in all direction

of the cell, the cell is defined as in the carrier coverage center. If no intra-frequency celllies in a direction of the cell, the cell is defined as at the carrier coverage edge.


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In the cell at the carrier coverage edge, when UE moves along the direction where no

intra-frequency neighbor cell lies, the CPICH Ec/No changes slowly due to the identicalattenuation rate of CPICH RSCP and interference. According to simulation, when

CPICH RSCP is smaller than the demodulation threshold (100 dBm or so), the CPICHEc/No can still reach 12 dB or so. Now the inter-frequency handover algorithm based

on CPICH Ec/No is invalid. Therefore, for the cell at the carrier coverage edge, usingCPICH RSCP as inter-frequency measurement quantity to guarantee coverage is moreproper.

In the cell in the carrier coverage center, use CPICH RSCP as inter-frequencymeasurement quantity, but CPICH Ec/No can better reflect the actual communication

quality of links and cell load. Therefore use CPICH Ec/No as inter-frequencymeasurement quantity in the carrier coverage center (not the cell at the carrier coverage

edge), and RSCP as inter-frequency measurement quantity in the cell at the carriercoverage edge.

In compression mode, the quality of target cell (inter-frequency or inter-RAT) is usuallymeasured and obtained. The mobility of MS leads to quality deterioration of the current

cell. Therefore the requirements on starting threshold are: before call drop due to the

quality deterioration of the current cell, the signals of the target cell must be measuredand reporting is complete. The stopping threshold must help to prevent compressionmode from starting and stopping frequently.

The RNC can distinguish CS services from PS services for inter-frequency measurement.

If the RSCP is smaller than 95 dBm, compression mode starts. If the RSCP is greaterthan 90 dBm, compression mode stops. Adjust RSCP accordingly for special scenarios.

Increase the CIO of two inter-frequency cells.

Decrease the target frequency handover trigger threshold of inter-frequencycoverage.

For Ping-pong HHO problems, solve them by increasing HHO hysteresis and delay trigger time.

The intra-frequency HHO optimization is similar to that of inter-frequency. Decrease thehysteresis and delay trigger time of 1D event according to local radio environment to guaranteetimely handover.

3.1.3 Inter-RAT Handover CQT Flow

Flow Chat

Figure 3-3 shows the inter-RAT handover CQT flow.


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Figure 3-3Inter-RAT handover CQT flow

Data Configuration

Inter-RAT handover fails due to incomplete configuration data, so pay attention to the followingdata configuration.

GSM neighbor configuration is complete on RNC. The configuration includes:

Mobile country code (MCC)

Mobile network code (MNC)

Location area code (LAC)

GSM cell identity (CELL ID)

Network color code (NCC)

Base station color code (BCC)

Frequency band indicator (FREQ_BAND)

Frequency number

Cell independent offset (CIO)

Guarantee the correctness of the previous data and GSM network.


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Add location area cell information near 2G MSC to location area cell list of 3G MSC.The format of location area identity (LAI) is MCC + MNC + LAC. Select LAI as LAItype. Select Near VLR area as LAI class and add the corresponding 2G MSC/VLRnumber. The cell GCI format is: MCC + MNC + LAC + CI. Select GCI as LAI type.Select Near VLR area as LAI class and add the corresponding 2G MSC/VLR

number.

Add data of WCDMA neighbor cells on GSM BSS. The data includes:

Downlink frequency

Primary scramble

Main indicator

MCC

MISSING NEIGHBOR CELL

LAC

RNC ID

CELL ID

According to the strategies of unilateral handover of inter-RAT handover, if the dataconfiguration is complete, the inter-RAT handover problems are due to delayed handover. Afrequently-used solution is increasing CIO, increasing the threshold for starting and stoppingcompression mode, increasing the threshold to hand over to GSM.

Causes

The causes to call drop due to 3G-2G inter-RAT handover are as below: After the 2G network modifies its configuration data, it does not inform the 3G

network of modification, so the data configured in two networks are inconsistent.

Missing neighbor cell causes call drop.

The signals fluctuate frequently so call drop occurs.

Handset problems causes call drop. For example, the UE fails to hand over back or

to report inter-RAT measurement report.

The best cell changes upon Physical channel reconfiguration.

Excessive inter-RAT cell are configured (solve it by optimizing number of neighbor

cells).

Improperly configured LAC causes call drop (solve it by checking data configuration).

3.1.4 DT/CQT Flow for HSDPA Handover

Type

According to the difference of handover on DPCH in HSDPA network, the HSDPA handoverincludes:

SHO or softer handover of DPCH, with HS-PDSCH serving cell update


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Intra-frequency and inter-frequency HHO of DPCH, with HS-PDSCH serving cellupdate

According to different technologies used in the serving cell before and after handover, HSDPAhandover includes:

Handover in HSDPA system

Handover between HSDPA and R99 cells

Handover between HSDPA and GPRS cells

Methods

For HSDPA service coverage test and mobility-related test (such as HHO on DPCH withHS-PDSCH serving cell update, handover between HSDPA and R99, and inter-RAT handover),perform DT to know the network conditions.

For location of HSDPA problems and non-mobility problems, perform CQT (in specified point orsmall area).

Flow

When a problem occurs, check R99 network. If there is similar problem with R99 network, solveit (or, check whether the R99 network causes HSDPA service problems, such as weak coverage,missing neighbor cell. Simplify the flow).

Figure 3-4 shows the DT/CQT flow for HSDPA handover.


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Figure 3-4DT/CQT flow for HSDPA handover

The problems with handover of HSDPA subscribers are usually caused by the faulty handoverof R99 network, such as missing neighbor cell and improper configuration of handoverparameters. When the R99 network is normal, if the handover of HSDPA subscribers is stillfaulty, the cause might be improper configuration of HSDPA parameters. Engineers can checkthe following aspects:

Whether the HSDPA function of target cell is enabled and the parameters arecorrectly configured. Engineers mainly check the words of cell and whether thepower is adequate, whether the HS-SCCH power is low. These parameters mightnot directly cause call drop in handover, but lead to abnormal handover and loweredthe user experience.

Whether the protection time length of HSDPA handover is proper. Now the baselinevalue is 0s. Set it by running SET HOCOMM.

Whether the threshold for R99 handover is proper. The handover flow for HSDPA isgreatly different from that of R99, so the handover of R99 service may succeed whilethe HSDPA handover may fail. For example, in H2D handover, when the UE reports1b event, it triggers RB reconfiguration in the original cell, reconfigures servicebearer to DCH, and updates the cell in active set. If the signals of the original celldeteriorate quickly now, the reconfiguration fails.

Whether the protection time length of D2H handover is proper. Now the baselinevalue is 2s. Set it by running SET HOCOMM.


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3.1.5 DT/CQT Flow for HSUPA Handover

The DT/CQT flow for HSUPA handover is similar to that for HSDPA. For details, refer to DT/CQTFlow for HSDPA Handover.

For the test of HSUPA service coverage and mobility-related tests (such as the test of successrate of HSUPA serving cell update), perform DT to know the network conditions. For locatingHSUPA problems and the problems unrelated to mobility, perform CQT (in specified spot orarea).

3.1.6 SHO Ratio Optimization

This part is to be supplemented.

3.1.7 MBMS Mobility Optimization

Currently, the radio network controller (RNC) V18 supports only the broadcast mode of themultimedia broadcast multicast service (MBMS); the MBMS user equipment (UE) moves onlybetween point-to-multipoint (PTM) cells.

Figure 3-5Movement of the MBMS UE between PTM cells

PTM Cell BPTM Cell A




Step1: UE uses PTM RB to receiveMBMS from Cell A only

Step2: UE uses PTM RB toreceive MBMS from A and B

Step3: UE re-selects to Cell Bbut still receive MBMS fromCell A and B

Step4: Far from Cell A, UE usesPTM RB to receive MBMS fromCell B only

The movement of the MBMS UE between PTM cells is similar to the movement of UE

performing PS services in the CELL-FACH state. The UE performs the handover between cells


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through cell reselection and obtains a gain through soft combining or selective combiningbetween two cells to guarantee the receive quality of the service. The UE first moves to thetarget cell and then sends a CELL UPDATE message to notify the serving radio networkcontroller (SRNC) that the cell where the UE stays is changed. The SRNC returns a CELLUPDATE CONFIRM message. The UE receives an MBMS control message from the MCCH in

the target cell and determines whether the MBMS radio bearer to be established is consistentwith that of the neighboring cell. If they are consistent, the original radio bearer is retained. TheMBMS mobility optimization, which guarantees that the UE obtains better quality of service atthe edge of cells, covers the following aspects:

Optimize cell reselection parameters to guarantee that the UE can be reselected tothe best cell in time.

Guarantee that the power of the FACH in each cell is large enough to meet thecoverage requirement of the MBMS UE at the edge of the cells.

Guarantee that the transmission time difference of the UE between different links

meets the requirement of soft combing or selective combining*.

Guarantee that the power, codes, transmission, and CE resources of the target cellare not restricted or faulty, and that the MBMS service is successfully established.

The UE can simultaneously receive the same MBMS service from two PTM cells and combinethe received MBMS service. The UE supports two combining modes:

Soft combining: The transmission time difference between the current cell and the neighboringcell is within (one TTI + 1) timeslots and the TFCI in each transmission time interval (TTI) is thesame.

Selective combining: The transmission time difference between the current cell and the

neighboring cell is within the reception time window stipulated by the radio link controller (RLC).The SCCPCH is decoded and the transmission blocks are combined in the RLC PDU phase


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3.2 Traffic Statistics Analysis Flow

The traffic statistics data is important to network in terms of information source. In addition, it isthe major index to evaluate network performance.

The handover traffic statistics data is includes RNC-oriented data and cell-oriented data. RNCoriented data reflects the handover performance of entire network, while cell-oriented datahelps to locate problematic cells.

The analysis flow for SHO, HHO, inter-RAT handover, and HSDPA handover is similar, but thetraffic statistics indexes are different from them.

Figure 3-6 shows the analysis flow for handover traffic statistics data.


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Figure 3-6Analysis flow for handover traffic statistics data

3.2.1 Analysis Flow for SHO Traffic Statistics

The SHO success rate is defined as below:

SHO success rate = SHO successful times/SHO times

According to the flow, SHO includes SHO preparation process and SHO air interface process.The SHO preparation process is from handover judgment to RL setup completion. The SHO airinterface process is active set update process.

Check the SHO success rate of entire network and cell in busy hour. If they are notqualified, analyze the problematic cells in details.

Sort the SHO (or softer handover) failure times of the cell by TOP N and locate the

cells with TOP N failure times. List the specific indexes of failure causes. If locatingspecific causes from traffic statistics is impossible, analyze the corresponding CHR.

Table 3-1 lists the detailed traffic statistics indexes to SHO (or softer handover) failure

and analysis.


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Table 3-1SHO failure indexes

Failure causes Analysis

Configuration nonsupportThe UE thinks the content of active set update for RNC to add/delete linksdoes not support SHO. This scenario seldom exists in commercial networks.

Synchronizationreconfigurationnonsupport

The UE feeds back that the SHO (or softer handover) for RNC to add/deletelinks is incompatible with other subsequent processes. The RNCguarantees serial processing upon flow processing. This cause is due to theproblematic UE.

Invalid configurationThe UE thinks the content of active set update for RNC to add/delete links isinvalid. This scenario seldom exists in commercial networks.

No response from UE

The RNC fails to receive response to active set update command foradding/deleting links. This is a major cause to SHO (or softer handover)failure. It occurs in areas with weak coverage and small handover area. RFoptimization must be performed in the areas.

Perform DT to re-analyze problems. The traffic statistics data provides the trend and

possible problems. Further location and analysis of problems involves DT and CHRto the cell. DT is usually performed on problematic cells and signaling flow at the UEside and of RNC is traced. For details, see 3.1.3 .

3.2.2 Analysis Flow of HHO Traffic statistics

The HHO traffic statistics includes outgoing HHO success rate and incoming HHO success rate:

Outgoing HHO Success Rate = Outgoing HHO Success Times/Outgoing HHOTimes

Incoming HHO Success Rate = Incoming HHO Success Times/Incoming HHOTimes

Upon HHO failure, pay attention to indexes related to internal NodeB, between NodeBs, andbetween RNCs.

Table 3-2 lists the HHO failure indexes.

Table 3-2HHO failure indexes

Failure cause Analysis

HHO preparation failure

Radio link setup failure Analyze RL setup failure.

Other causes Analyze the problem further based on CHR logs.

Internal NodeB/Between NodeBs/Between RNCs HHO failure

Configurationnonsupport

The UE thinks it cannot support the command for outgoing HHO,because it is incompatible with HHO.

PCH failure The cause is probably weak coverage and strong interference.

Synchronizationreconfigurationnonsupport

The UE feeds back HHO is incompatible with other consequent processesdue to compatibility problems of UE.


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Cell updateCell update occurs upon outgoing HHO. These two processes lead tooutgoing HHO failure.

Invalid configurationThe UE thinks the command for outgoing HHO as invalid. This is acompatibility problem of UE.

Other causes Analyze the problem further based on CHR logs.

3.2.3 Traffic Statistics Analysis Flow for Inter-RAT Handover

The inter-RAT handover success rate includes voice inter-RAT handover success rate and PSinter-RAT handover success rate.

Voice Inter-RAT Outgoing Handover Success Rate = Voice Inter-RAT Outgoing HandoverSuccess Times/Voice Inter-RAT Outgoing Handover Attempt Times

Voice Inter-RAT Outgoing Handover Success Times: when the RNC sends a RELOCATIONREQUIRED message.

Voice Inter-RAT Outgoing Handover Attempt Times: during CS inter-RAT outgoing, when theRNC receives an IU RELEASE COMMAND message, with the reason value SuccessfulRelocation, or Normal Release.

PS Inter-RAT Outgoing Handover Success Rate = PS Inter-RAT Outgoing Handover SuccessTimes/PS Inter-RAT Outgoing Handover Implementation Times

PS Inter-RAT Outgoing Handover Success Times: the RNC sends a CELL CHANGE ORDERFROM UTRAN message to UE.

PS Inter-RAT Outgoing Handover Implementation Times: when the RNC receives an IURELEASE COMMAND message, with the reason value Successful Relocation, or Normal

Release.

Voice Inter-RAT Outgoing Handover Success Rate

The voice inter-RAT outgoing handover includes handover preparation process andimplementation process.

Figure 3-7 shows the voice inter-RAT outgoing handover flow.


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Figure 3-7Voce inter-RAT outgoing handover flow

During CS inter-RAT outgoing handover process, when the RNC sends a RELOCATIONREQUIRED message to CN, if the current CS service is AMR voice service, count it as aninter-RAT handover preparation. When the RNC receives the IU RELEASE COMMANDmessage replied by CN, count it as inter-RAT outgoing handover success according to theSRNC cell being used by UE.

If CS inter-RAT handover fails, check the failure statistics indexes listed in Table 3-3.

Table 3-3Traffic statistics indexes of CS inter-RAT handover preparation failure


RNC-level inter-RAT outgoing handover preparation failure

Expiration ofwaiting for SRNSrelocationcommand

The CN does not respond the corresponding command for handoverpreparation request, because the CN parameter configuration or thecorresponding link connection is problematic. To solve this problem,analyze the causes according to CN and BSS signaling tracing.

SRNS relocationcancellation

After the RNC requests handover preparation, it receives the releasecommand from CN. This includes the following two cases:

The inter-RAT handover request occurs during signaling process like

location update, so the flow is not complete before location update is

complete. Finally the CN sends a release message.

The subscribers that are calling hang UE before handover preparation,

so the CN sends a release message.

The previous two cases, despite incomplete handover, are normal nestingflows.

SRNS relocationexpiration

It corresponds to incorrect configuration of CN, so you must analyze thecauses according to CN and BSS signaling tracing.

SRNS relocationfailure in targetCN/RNC/system

It corresponds to incorrect configuration of CN or BSS nonsupport, so youmust analyze the causes according to CN and BSS signaling tracing.


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Unknown targetRNC

It corresponds to incorrect configuration of MSC parameters withoutinformation like LAC of target cell, so you must check the parameterconfiguration. It occurs easily after adjustment of 2G networks.

Unavailable

resource

It corresponds to incorrect configuration of MSC parameters or unavailable

BSC resources, so you must analyze the causes according to CN and BSSsignaling tracing.

Other causes Analyze the causes according to CN and BSS signaling tracing.

Cell-level inter-RAT outgoing handover preparation failure

SRNS relocationexpiration

The CN parameter configuration or the corresponding link connection isproblematic, so you must analyze the causes according to CN and BSSsignaling tracing.

SRNS relocationfailure in targetCN/RNC/system

It corresponds to incorrect configuration of CN or BSS nonsupport, so youmust analyze the causes according to CN and BSS signaling tracing.

SRNS relocationnonsupport intargetCN/RNC/system

The BSC fails to support some parameters of inter-RAT handover request,so you must analyze the causes according to CN and BSS signalingtracing.

Other causes Analyze the causes according to CN and BSS signaling tracing.

RNC-level/CELL-level inter-RAT outgoing handover failure


The UE fails to support the handover command in the network, so the UEis incompatible with the handover command.

PCH failureThe 2G signals are weak or the interference is strong so the UE fails toconnect to the network.

Other causes

Analyze the problem further according to CHR logs and CN/BSS signaling

tracing.

PS Inter-RAT Handover Success Rate

After the RNC sends the CELL CHANGE ORDER FROM UTRAN message, the PS inter-RAToutgoing handover fails if it receives the CELL CHANGE ORDER FROM UTRAN FAILUREmessage. You must check the indexes listed in Table 3-4.

Table 3-4Traffic statistics indexes of PS inter-RAT outgoing handover failure


RNC-level/CELL-level PS inter-RAT outgoing handover preparation failure


The UE fails to support the handover command of the network, becausethe UE is incompatible with the command.

PCH failureThe 2G signals are weak or the interference is strong, so the UE fails toaccess the network.

Radio networklayer cause

The UE is probably incompatible. The UE detects that the sequencenumber of SNQ in the AUTN message is correct, so the handover fails.The value is synchronization failure.

Transport layer

cause The corresponding transport link is abnormal.


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Other causes You must analyze the causes according to CN and BSS signaling tracing.

3.2.4 Traffic Statistics Analysis for HSDPA Handover

HSDPA switch includes

H-H (HS-DSCH to HS-DSCH) intra-frequency serving cell update

H-H inter-frequency serving cell update

HSDPA-R99 intra-frequency switch

HSDPA-R99 inter-frequency switch

HSDPA-GPRS switch

The traffic statistics indexes are defined as below:

Success rate of H-H intra-frequency serving cell update = (Times of successful

update of serving cell)/(attempt times update of serving cell)

When the RNC sends UE the PHYSICAL CHANNEL RECONFIGURATION message,

if the serving cell is updated, engineers count the attempt times of serving cell in theoriginal serving cell. When the RNC receives the PHYSICAL CHANNEL RECFG

COMPLETE message, if the serving cell changes, the RNC counts the times of

successful update of serving cells in the original serving cell when the UE is in the SHOmode not in the HHO mode.

Success rate of H-H inter-frequency serving cell update = Times of successfuloutgoing inter-frequency HHO from HS-DSCH to HS-DSCH/Times of requestedoutgoing inter-frequency HHO from HS-DSCH to HS-DSCH

When the RNC sends UE the PHYSICAL CHANNEL RECONFIGURATION message,and the inter-frequency HHO is from HS-DSCH to HS-DSCH, the RNC counts the times

of requested outgoing inter-frequency HHO from HS-DSCH to HS-DSCH. When the

RNC receives the PHYSICAL CHANNEL RECFG COMPLETE message from UE, andthe inter-frequency HHO is from HS-DSCH to HS-DSCH, engineers count the times of

successful outgoing inter-frequency HHO from HS-DSCH to HS-DSCH.

Success rate of H-H inter-frequency serving cell update = successful times of

outgoing inter-frequency HHO from HS-DSCH to HS-DSCH/attempt times HHO fromDCH to HS-DSCH in the cell

When the RNC sends the UE the PHYSICAL CHANNEL RECONFIGURATIONmessage, if the switch is the inter-frequency HHO from HS-DSCH to HS-DSCH, the

RNC counts the successful times of inter-frequency HHO from HS-DSCH to HS-DSCHin the cell.

Success rate of H-to-R99 intra-frequency SHO = successful times of switch fromHS-DSCH to DCH in multi-link mode in the cell/attempt times switch from HS-DSCHto DCH in multi-link mode in the cell.Success rate of R99-to-H intra-frequency SHO = successful times of switch fromDCH to HS-DSCH in multi-link mode in the cell/attempt times switch from DCH toHS-DSCH in multi-link mode in the cell.

In the DCCC or RAB MODIFY process, if the RNC decides to switch the channel in thecell, it sends the UE the RF RECONFIGURATION message. According to the channel

state of the UE before and after reconfiguration, the RNC counts the previous indexes in

the HSDPA serving cell.


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Success rate of H-to-R99 intra-frequency HHO = successful times of outgoingintra-frequency HHO from HS-DSCH to DCH in the cell/attempt times outgoingintra-frequency HHO from HS-DSCH to DCH in the cell.

When the RNC sends the UE the PHYSICAL CHANNEL RECONFIGURATION

message, if the switch is the intra-frequency switch from HS-DSCH to DCH, the RNCcounts the attempt times of inter-frequency HHO from HS-DSCH to DCH in the cell.

When the RNC receives the PHYSICAL CHANNEL RECFG COMPLETE messagefrom the UE, if the switch is the intra-frequency HHO from HS-DSCH to DCH, theRNC counts the successful times of outgoing intra-frequency HHO from HS-DSCH toDCH in the cell.

Success rate of H-to-R99 inter-frequency switch updateThe RNC algorithm is unavailable now, so this index is unavailable.

Success rate of H-to-R99 inter-frequency switch update = successful times ofoutgoing HHO from HS-DSCH to DCH in the cell/attempt times outgoinginter-frequency HHO from HS-DSCH to DCH in the cell

When the RNC sends the UE the PHYSICAL CHANNEL RECONFIGURATIONmessage, if the switch is the inter-frequency switch from HS-DSCH to DCH, the RNCcounts the attempt times inter-frequency HHO from HS-DSCH to DCH in the cell. When

the RNC receives the PHYSICAL CHANNEL RECFG COMPLETE message from theUE, if the switch is the inter-frequency HHO from HS-DSCH to DCH, the RNC counts

the successful times of outgoing inter-frequency HHO from HS-DSCH to DCH in thecell.

Success rate of R99-to-HThe RNC algorithm is unavailable now, so this index is unavailable.

Success rate of R99-to-H switch = successful times of switch from DCH to

HS-DSCH in the cell/attempt times of switch from DCH to HS-DSCH in the cell

In the DCCC or RAB MODIFY process, if the RNC decides to switch the channel in thecell, it sends the UE the RF RECONFIGURATION message. According to the channelstate of the UE before and after reconfiguration, the RNC counts the attempt times of

switch from DCH to HS-DSCH in the HSDPA serving cell. In the DCCC or RABMODIFY process, if the RNC receives the RB RECONFIGURATION COMEPLTE

message from UE, and the reconfiguration enables UE to switch from the DCH toHS-DSCH in the same cell, the RNC counts the successful times of switch from DCH to

HS-DSCH in the HSDPA serving cell.

Success rate of H-to-GPRS handover update

The traffic statistics does not include the index, and the index will be supplemented later.

The causes to failure and analysis methods will be summarized later.

3.2.5 Traffic Statistics Analysis for HSUPA Handover

The traffic statistics indexes for HSUPA are defined as below:

Success rate of SHO between HSUPA cells (including adding, replacing, and

deleting) = attempt times of active set update/complete times of active set update.

Success rate of SHO serving cell update between HSUPA cells = successful timesof SHO serving cell update/attempt times of SHO serving cell update.


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Success rate of reconfiguration from DCH to E-DCH in the cell (SHO,intra-frequency HHO, and inter-frequency HHO) = successful times of handover fromDCH to E-DCH/attempt times of handover from DCH to E-DCH.

Success rate of reconfiguration from E-DCH to DCH in the cell (including adding and

replacing) = successful times of handover from E-DCH to DCH in SHOmode/attempt times of handover from E-DCH to DCH in SHO mode.

Success rate of intra-frequency HHO serving cell between HSUPA cells = successfultimes of intra-frequency HHO serving cell between HSUPA cells/attempt times ofintra-frequency HHO serving cell between HSUPA cells.

Success rate of intra-frequency HHO from E-DCH to DCH from a HSUPA cell to anon-HSUPA cell = successful times of intra-frequency HHO from E-DCH toDCH/attempt times of intra-frequency HHO from E-DCH to DCH.

Success rate of inter-frequency HHO serving cell update between HSUPA cells =successful times of inter-frequency HHO serving cell update between HSUPA

cells/attempt times of inter-frequency HHO serving cell update between HSUPAcells.

Successful times of inter-frequency HHO from a HSUPA cell to a non-HSUPA cell =

successful times of inter-frequency HHO from E-DCH to DCH/request times ofinter-frequency HHO from E-DCH to DCH.


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3.3 SHO Cost Optimization

To be supplemented.

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