W Access Problem Optimization Guide 20081115 a 3_3

Product name Confidentiality level

WCDMA RNP For internal use only

Product version Total 134 pages

3.3

W-Access Problem Optimization Guide

(For internal use only)

Prepared by Dong Yan Date 2005-11-21

Reviewed by Wang Liang, Guo Zhengping, Yu Yongxian, and Xu Jianguo

Date

Reviewed by Qin Yan Date

Approved by Date

Huawei Technologies Co., Ltd. All Rights Reserved

Revision Records

Date Version Description Author 2004-08-23 1.00 Outline Guan Shiguo 2004-11-03 1.00 Initial transmittal Guan Shiguo 2004-12-20 1.20 Revising according to review Guan Shiguo 2005-11-21 3.00 According to V3.0 guide requirements, reorganizing and

updating V2.0 guide. The update includes: l Modifying document structure l Adding optimization objectives l Adding delay optimization l Adding some new cases and analysis l Redrawing analysis flow chats l Adding appendix which contain the background knowledge

about access. l Adding analysis of traffic statistics data

Dong Yan

2006-05-19 3.10 V3.10 adds analysis of HSDPA with the following content updated: l Supplementing admission failure analysis and cases about

RRC connection, RAB assignment process in HSDPA service l Adding HSDPA-related DT and traffic statistics values l According to traffic statistics indexes of RNC version

1.6C01B064, adding some traffic statistics indexes l Updating RRC connection analysis

Wang Dekai

2006-06-21 3.11 Adding analysis of traffic statistics in paging problems Dong Yan 2006-10-23 3.12 l Adding analysis of reasons for admission rejection

l Adding algorithms of admission rejection in V17 l Adding analysis of dualband access problems l Adding analysis of impacts brought by dual-carrier direct

retry on the access delay

Wang Dekai

2007-08-25 3.2 Adding HSUPA analysis, including: l Introduction to HSUPA load control algorithms l Description of key parameters in HSUPA load control l Introduction to indexes of success rate of HSPA RAB setup l Strategy of HSPA dualband networking

Gao Bo

2007-12-5 3.3 Adding analysis of MBMS service, including: 3.3.9 Analysis of MBMS service access problems 4.3.6 Analysis of low MBMS service setup success rate

Wang Dekai

2008-11-15 3.3 Review yearly Shan Weizhen / Hu Wensu

W-Access Problem Optimization Guide For internal use only

2008-11-17 Huawei Proprietary. No Spreading Without Permission. of 134

Contents

1 Introduction ............................................................................................................................ 16

2 Evaluating Access Performance ........................................................................................... 17 2.1 Accessibility ............................................................................................................................................. 17 2.2 System Availability ................................................................................................................................... 18 2.3 Access Delay ............................................................................................................................................ 18

3 Analyzing DT/CQT Data ...................................................................................................... 19 3.1 Data Analysis Software............................................................................................................................. 19 3.2 Definition of Access Failure...................................................................................................................... 19

3.2.1 Definition of Call Failure by GENEX Assistant ................................................................................ 19 3.2.2 Definition of Access Failure by Actix Analyzer ................................................................................ 21 3.2.3 Definition of Access Failure by TEMS ............................................................................................. 21

3.3 Flow and Methods for Analyzing Access Failure Problems ........................................................................ 22 3.3.1 Overall Flow for Analyzing Call Failure Problems ........................................................................... 22 3.3.2 Analyzing Paging Problems ............................................................................................................. 23 3.3.3 Analyzing RRC Connection Setup Problems .................................................................................... 25 3.3.4 Analyzing Authentication Problems ................................................................................................. 28 3.3.5 Analyzing Security Mode Problems ................................................................................................. 30 3.3.6 Analyzing PDP Activation Failure Problems..................................................................................... 31 3.3.7 Analyzing RAB or RB Setup Problems ............................................................................................ 32 3.3.8 Analyzing Access Problems in the Case of Dualband Networking ..................................................... 35 3.3.9 Analyzing MBMS service access problems ...................................................................................... 38

3.4 Processing Access Delay .......................................................................................................................... 40 3.4.1 Configuration of Discontinuous Cyclic Period Duration Factor DRX ................................................ 41 3.4.2 Whether to Disable Authentication and Encryption Flow .................................................................. 41 3.4.3 Implementing Early or Late Assignment .......................................................................................... 41 3.4.4 Whether the RRC Connection Is Set up on FACH and DCH ............................................................. 42 3.4.5 Impact of Direct Retry on Access Delay ........................................................................................... 42

4 Analyzing Traffic Statistics Data ......................................................................................... 43 4.1 Tool for Analyzing Data............................................................................................................................ 43 4.2 General Methods for Analyzing Traffic Statistics Data .............................................................................. 43

4.2.1 Flow for Analyzing RNC-level Traffic Statistics Data ....................................................................... 44 4.2.2 Flow for Analyzing Cell-level Traffic Statistics Data ........................................................................ 45

4.3 Accessibility Indexes ................................................................................................................................ 46 4.3.1 Paging Traffic Statistics Indexes ...................................................................................................... 46



4.3.2 Low Success Rate of RRC Setup...................................................................................................... 49 4.3.3 Low Success Rate of CS RAB Setup ................................................................................................ 53 4.3.4 Lower Success Rate of PS RAB Setup ............................................................................................. 57 4.3.5 Low Success Rate of RB Setup ........................................................................................................ 62 4.3.6 Low success rate of MBMS service setup......................................................................................... 64

4.4 System Availability Index ......................................................................................................................... 65 4.4.1 High Admission Rejection Rate ....................................................................................................... 65 4.4.2 High Paging Congestion Rate .......................................................................................................... 65 4.4.3 High Rate of Congested Cell ............................................................................................................ 65

5 Solving Access Problems ...................................................................................................... 66 5.1 Paging Problems....................................................................................................................................... 66

5.1.1 Improper Power Configuration of Paging-related Channels .............................................................. 66 5.1.2 Paging Failure due to UE Location Area Update ............................................................................... 66 5.1.3 Paging Failure due Implicit Detach of UE ........................................................................................ 68

5.2 Cell Selection and Reselection Problem .................................................................................................... 69 5.2.1 Repeating to Send the RRC Connection Request Message due to Cell Reselection ............................ 69

5.3 RRC Setup Problems ................................................................................................................................ 72 5.3.1 Improper Configuration of Parameters of Uplink Access Channel ..................................................... 72 5.3.2 Improper Configuration of AICH Power .......................................................................................... 75 5.3.3 Improper Configuration of FACH Power .......................................................................................... 75 5.3.4 Multiple Times of RRC Connection Request (for Service) and No RAB Assignment Request ........... 78 5.3.5 RRC Connection of HSDPA Subscribers Rejected due to Inadequate Code Resource ........................ 81

5.4 RAB and RB Setup Problems ................................................................................................................... 83 5.4.1 RAB Setup Failure due to Inadequate Resource................................................................................ 83 5.4.2 Handover Failure before Completion of Signaling Flow ................................................................... 84 5.4.3 Admission Failure due to HSDPA Total Bit Rate Threshold Exceeded by HSDPA Bit Rate of Cell .... 86

5.5 Authentication Problems ........................................................................................................................... 87 5.6 Security Mode Problems ........................................................................................................................... 88 5.7 Abnormal Equipment Problems ................................................................................................................ 90

5.7.1 Abnormal NodeB ............................................................................................................................. 90 5.7.2 Abnormal UE .................................................................................................................................. 92

6 Summary ................................................................................................................................. 95

7 Appendix 1: Paging Process .................................................................................................. 96 7.1 Paging Origination ................................................................................................................................... 96

7.1.1 Paging by CN .................................................................................................................................. 96 7.1.2 Paging by UTRAN .......................................................................................................................... 96

7.2 Paging Flow ............................................................................................................................................. 96 7.2.1 Paging Type 1 .................................................................................................................................. 96 7.2.2 Paging Type 2 .................................................................................................................................. 98

7.3 Behaviors of UE after Receiving Paging ................................................................................................... 98



7.3.1 UE in Idle Mode .............................................................................................................................. 98 7.3.2 UE in Connected Mode .................................................................................................................... 99

7.4 DRX Process of UE .................................................................................................................................. 99 7.4.1 DRX Cyclic Length and Paging Occasion ........................................................................................ 99 7.4.2 Relationship of PICH and SCCPCH ............................................................................................... 100 7.4.3 PCH Selection ............................................................................................................................... 102 7.4.4 DRX Examples of UE.................................................................................................................... 102

8 Appendix 2: Access Process Analysis ................................................................................ 104 8.1 Cell Search ............................................................................................................................................. 104

8.1.1 Timeslot Synchronization .............................................................................................................. 105 8.1.2 Frame Synchronization and Scramble Group Identification ............................................................ 105 8.1.3 Identification of Cell Primary Scramble ......................................................................................... 105

8.2 Cell Selection and Reselection ................................................................................................................ 105 8.2.1 Cell Selection ................................................................................................................................ 105 8.2.2 Judgment Criterion (Criterion S) .................................................................................................... 106 8.2.3 Cell Reselection............................................................................................................................. 108

8.3 Random Access ...................................................................................................................................... 114 8.3.1 Random Access Channel ................................................................................................................ 114 8.3.2 Random Access Process ................................................................................................................. 117

9 Appendix 3: Authentication Flow ...................................................................................... 120

10 Appendix 4: Description of Access-related Parameters ................................................ 123 10.1 Engineering Parameters ........................................................................................................................ 123 10.2 Cell Parameters .................................................................................................................................... 123

10.2.1 Transmit Power of FACH ............................................................................................................. 123 10.2.2 Transmit Power of PCH ............................................................................................................... 124 10.2.3 Transmit Power of PICH .............................................................................................................. 124 10.2.4 Cell Reselection Parameter: Measurement Hysteresis 2 (Qhyst2s) ................................................ 124 10.2.5 Cell Reselection Parameter: Reselection Hysteresis Time (Treselections) ...................................... 124 10.2.6 Cell Reselection Parameter: Sintrasearch ...................................................................................... 124 10.2.7 Cell Reselection Parameter: Qoffset2 ........................................................................................... 125 10.2.8 Transmit Power of AICH ............................................................................................................. 125 10.2.9 PRACH-related Parameters .......................................................................................................... 125

11 Appendix 5: HSUPA Load Control .................................................................................. 126 11.1 Admission Decision in HSUPA Cells..................................................................................................... 126

11.1.1 Number of Subscribers ................................................................................................................. 126 11.1.2 lub Transmission Resources and NodeB Credit Resources ............................................................ 126 11.1.3 Power Resources.......................................................................................................................... 130 11.1.4 HSUPA RAB Downlink Admission .............................................................................................. 130 11.1.5 LDR ............................................................................................................................................ 130 11.1.6 OLC ............................................................................................................................................ 131



11.1.7 Description of Parameters ............................................................................................................ 131



Figures

Figure 3-1 Overall flow for analyzing call failure problems in DT/CQT ......................................................... 22

Figure 3-2 Signaling flow of originated UE in locating paging problems ........................................................ 23

Figure 3-3 Flow for analyzing paging problems ............................................................................................. 24

Figure 3-4 Flow for analyzing RRC connection setup problem ....................................................................... 26

Figure 3-5 Authentication failure due to MAC Failure .................................................................................... 29

Figure 3-6 Authentication failure due to Synch Failure ................................................................................... 30

Figure 3-7 Security mode control ................................................................................................................... 30

Figure 3-8 Security mode reject ..................................................................................................................... 31

Figure 3-9 Dualband scenario 1 (f1: R99; f2: R99+HSPA) ............................................................................. 35

Figure 3-10 Dualband scenario 2 (f1: R99+HSPA; f2: R99+HSPA) ................................................................ 35

Figure 3-11 Functions and process of RRC direct retry and re-direction during setup of the RRC connection .. 36

Figure 3-12 Signaling for service-based direct retry of a HSDPA subscriber ................................................... 37

Figure 3-13 Signaling for direct retry of a R99 subscriber after admission rejection ........................................ 38

Figure 3-14 Flow chart of broadcast model in MBMS .................................................................................... 39

Figure 4-1 Flow for analyzing RNC-level traffic statistics data ....................................................................... 44

Figure 4-2 Flow for analyzing cell-level traffic statistics data ......................................................................... 45

Figure 4-3 Position for counting point by counter for paging loss by idle UE .................................................. 47

Figure 4-4 Position for counting point by counter for paging loss by UE in PCH state .................................... 48

Figure 4-5 Position for counting point by counter for RRC connection rejection ............................................. 50

Figure 4-6 Position for counting point by counter for CS RAB assignment failure in RNC traffic statistics starting counting ............................................................................................................................................ 54

Figure 4-7 Position for counting point by counter for PS RAB assignment failure in RNC traffic statistics ...... 57

Figure 4-8 Position for counting point by counter for RB setup failure in traffic statistics ............................... 63

Figure 5-1 Originating signaling flow of paging failure due to UE location area update .................................. 66

Figure 5-2 Content of the Disconnect message in paging failure due to UE location area update ..................... 67

Figure 5-3 Terminating signaling flow of paging failure due to UE location area update ................................. 67

Figure 5-4 Signaling of UE ............................................................................................................................ 69



Figure 5-5 Signal quality when the UE sends the RRC connection request message. ....................................... 70

Figure 5-6 Signal quality when the UE repeats to send the RRC connection request........................................ 71

Figure 5-7 Signaling of UE in a connection process ....................................................................................... 72

Figure 5-8 Single subscriber tracing signaling on RNC .................................................................................. 72

Figure 5-9 Quality of downlink signals .......................................................................................................... 73

Figure 5-10 Regular interference in cell 248................................................................................................... 73

Figure 5-11 Part of magnified chart of interference......................................................................................... 74

Figure 5-12 Signaling upon improper configuration of FACH power .............................................................. 75

Figure 5-13 Signal strength upon the first sending of RRC connection request ................................................ 76

Figure 5-14 Single subscriber tracing signaling by RNC................................................................................. 76

Figure 5-15 Signaling and signal strength upon the second sending of RRC connection request ...................... 77

Figure 5-16 Traced signaling at UE side ......................................................................................................... 78

Figure 5-17 Traced signaling at RNC side ...................................................................................................... 78

Figure 5-18 BLER statistics at UE side .......................................................................................................... 79

Figure 5-19 BLER and RRC message at UE side ........................................................................................... 80

Figure 5-20 BLER and RRC message at UE side ........................................................................................... 81

Figure 5-21 Assignment of HSDPA code tree ................................................................................................. 82

Figure 5-22 RNC log for HSDPA admission rejection .................................................................................... 83

Figure 5-23 Signaling of Disconnect after completion of RB setup ................................................................ 84

Figure 5-24 Signaling of UE upon a connection failure .................................................................................. 85


Figure 5-26 Signal strength before release of connection ................................................................................ 86

Figure 5-27 Rejection messages in security mode........................................................................................... 88

Figure 5-28 Content of the RANAP_SECURITY_MODE_REJECT message................................................. 88

Figure 5-29 ciphering mode information configured in previous security mode command............................... 89

Figure 5-30 Security mode message ............................................................................................................... 89

Figure 5-31 Content of the RANAP_SECURITY_MODE_COMMAND message .......................................... 90

Figure 5-32 Signaling of UE upon failure in receiving RRC Connection Setup message ................................. 91


Figure 5-34 Signal strength upon occurrence of problems .............................................................................. 92

Figure 5-35 Signaling of UE .......................................................................................................................... 93

Figure 5-36 Downlink signal quality .............................................................................................................. 93

Figure 7-1 Flow chart of PAGING TYPE 1 message ...................................................................................... 97



Figure 7-2 Flow chart of PAGING TYPE 2 message ...................................................................................... 98

Figure 7-3 Schematic drawing of UE paging occasion .................................................................................. 100

Figure 7-4 Frame structure of PICH ............................................................................................................. 101

Figure 7-5 Sequence relationship between PICH and SCCPCH .................................................................... 102

Figure 8-1 Number and interval of access timeslots of RACH ...................................................................... 115

Figure 8-2 Structure of random access transmission ..................................................................................... 115

Figure 8-3 Timing relation between PRACH and AICH as seen at the UE .................................................... 116

Figure 8-4 Definition of access timeslot set (taking the uplink and downlink access timeslot fixed difference τp-a 7680 chips as example) ................................................................................................................................ 119

Figure 9-1 Successful authentication process ............................................................................................... 120

Figure 9-2 Authentication Failure (due to MAC Failure) .............................................................................. 121

Figure 9-3 Authentication failure (due to Synch failure) ............................................................................... 122



Tables

Table 2-1 Indexes and recommended values for accessibility related to DT ..................................................... 17

Table 2-2 Indexes and reference values for accessibility related to traffic statistics .......................................... 17

Table 2-3 Indexes and reference for system availability .................................................................................. 18

Table 2-4 Indexes and reference for access delay related to DT ....................................................................... 18

Table 3-1 RB setup delay on the RNC with or without DRD ........................................................................... 42

Table 4-1 Counters related to paging loss for idle UE ..................................................................................... 46

Table 4-2 Counters related to paging loss for UE in PCH state ........................................................................ 48

Table 4-3 Counter related to paging loss due to flow control ........................................................................... 49

Table 4-4 Counters related to PCH congestion ................................................................................................ 49

Table 4-5 Counters related to RRC connection request rejection due to lub interface failure ............................ 50

Table 4-6 Traffic statistics counters related to RRC connection request rejection due to network congestion .... 52

Table 4-7 Counter related to RRC connection failure due to no response ......................................................... 53

Table 4-8 Counters related to RRC connection setup rejection due to redirection ............................................ 53

Table 4-9 Traffic statistics counters related to CS RAB assignment setup failure due to radio network problems ...................................................................................................................................................................... 54

Table 4-10 Traffic statistics counters related to CS RAB assignment setup failure due to insufficient capability ...................................................................................................................................................................... 55

Table 4-11 Counter related to CS RAB assignment setup failure due to transmission network problems .......... 56

Table 4-12 Traffic statistics counters related to PS RAB assignment setup failure due to radio network problems. ...................................................................................................................................................................... 58

Table 4-13 Traffic statistics counters related to PS RAB assignment setup failure due to insufficient capability ...................................................................................................................................................................... 59

Table 4-14 Counter related to PS RAB assignment setup failure due to transmission network problems .......... 60

Table 4-15 Counter related to PS RAB setup failure due to no resource available ............................................ 61

Table 4-16 Traffic statistics counters related to RB setup failure ..................................................................... 63

Table 4-17 Traffic statistics counter related to no response to RB setup ........................................................... 64

Table 4-18 Measurement of MBMS service setup time at IU interface ............................................................ 64

Table 4-19 Measurement of face-to cell MBMS service. ................................................................................. 65



Table 7-1 Mapping relationship between PI and PICH .................................................................................. 101

Table 8-1 Parameters and their description in the criterion S ......................................................................... 107

Table 8-2 Cell reselection parameters and descriptions ................................................................................. 112

Table 8-3 Broadcast parameters and description of cell reselection in system information ............................. 112

Table 8-4 Relationship among the access subchannel, access timeslot, and SFN ............................................ 119

Table 11-1 Number of Credits consumed by different services ...................................................................... 128



W-Access Problem Optimization Guide

Key words WCDMA, radio network optimization, access, DT, and traffic statistics

Abstract The document describes how to locate and solve access problems in WCDMA network optimization, the definition of access problems, test methods, analysis flows, and solutions. Finally, the appendix provides the fundamental knowledge necessary for analyzing access problems by RNO engineers.

Acronyms and abbreviations: Acronyms and abbreviations Full Spelling

DT Drive Test

CQT Call Quality Test

RNC Radio Network Controller

RNP Radio Network Planning

RNO Radio Network Optimization

GBR Guaranteed Bit Rate

GBP Power to meet GBR



1 Introduction

This document aims to meet the requirements on solving access problems by on-site engineers during RNO. It details the methods for evaluating network access performance, test methods, data analysis methods, FAQs, and solutions. The appendix provides the fundamental knowledge about access problems, description of principles, related parameters, and data processing tools. It guides engineers to locate and solve access problems during optimizing network KPI indexes and network O&M. The RRM algorithms and product implementation in this document are for RNC V16, unless specified particularly. 3.3.7 , 3.3.8 , and 3.4.5 are updated.

This document excludes the usage of tools.

It contains 10 chapters, with the structure as below:

l Chapter 1: Introduction l Chapter 2: Evaluating Access Performance l Chapter 3: Analyzing DT/CQT Data l Chapter 4: Analyzing Traffic Statistics Data l Chapter 5: Solving Access Problems l Chapter 6: Summary l Chapter 7: Appendix 1: Paging Process l Chapter 8: Appendix 2: Access Process Analysis l Chapter 9: Appendix 3: Authentication Flow l Chapter 10:Appendix 4: Description of Access-related Parameters

On-site engineers must adjust network optimization parameters according to the importance levels of parameters, the impact of adjustment on network services and network equipment in a proper time. The whole adjustment must follow Radio Network Planning Online Data Modification Regulations and data backup and emergency solutions are necessary. Immediate verification must be performed after adjustment so that the adjustment is correct. The access process of HSPA service is similar to that of original R99 service. There are only some minor differences.



2 Evaluating Access Performance

The access performance includes three aspects: accessibility, system availability, and access delay. The specified indexes for measuring access performance are obtainable by DT and traffic statistics. For the definition of indexes, see the UMTS Radio Network KPI Baseline V3.3.

2.1 Accessibility Table 2-1 lists the indexes and recommended values for accessibility in DT.

Table 2-1 Indexes and recommended values for accessibility related to DT

Index Service Statistics method Reference

MOC success rate Voice DT&CQT 96%

VP DT&CQT 95%

MTC success rate Voice DT&CQT 95%

VP DT&CQT 94%

PDP context activation success rate

PS DT&CQT 96%

HSDPA DT&CQT 96%

Table 2-2 shows the indexes and reference values for accessibility related to traffic statistics.

Table 2-2 Indexes and reference values for accessibility related to traffic statistics


Radio paging success rate N/A Stat. 85%

RRC setup success rate N/A Stat. 97%

RAB setup success rate Voice Stat. 98%

VP Stat. 98%

PS Stat. 97%

HSDPA Stat. 97%



The values previously mentioned are just for reference. Determine the actual values according to the detailed requirements of projects or requirements of commercial network contracts.

2.2 System Availability Table 2-3 lists the indexes and reference for system availability.

Table 2-3 Indexes and reference for system availability


Admission rejection rate All services Stat. 2%

Paging congestion rate All services Stat. 0.5%

Congested cell ratio All services Stat. 1%

The values previously mentioned are just for reference. Determine the actual values according to the detailed requirements of projects or requirements of commercial network contracts.

2.3 Access Delay Table 2-4 lists the indexes and reference for access delay related to DT.

Table 2-4 Indexes and reference for access delay related to DT


Call setup delay Voice CQT 7s

VP ring CQT 7s

VP see the figure CQT 13s

PDP context activation delay PS CQT 4s

HSDPA CQT 2s (average) < 4s (95%)

The values previously mentions are just for reference. Determine the actual values according to the detailed requirements of projects or requirements of commercial network contracts.



3 Analyzing DT/CQT Data

3.1 Data Analysis Software The software for analyzing DT/CQT data includes the following items:

l GENEX Assistant: the post processing software for DT data l Rollback tool for Single subscriber tracing on RNC l Nastar CHR

3.2 Definition of Access Failure If a service fails to be setup, this is an access failure. In DT, the common access failure problems include the following types:

l Voice call failure l VP call failure l PDP activation failure

According to the preset judgment conditions, the DT data analyzers can usually judge the access failure problems during test. The analyzers include GENEX Assistant and Actix Analyzer.

3.2.1 Definition of Call Failure by GENEX Assistant

Originated Call Failure in CS Domain Event definition: the UE sends a RRC REQUEST message. Wherein, the IE establish cause is Originating Conversational Call without reception of the direct transfer message alerting.

The following events are defined according to the stages of failure.

Step 1 RRC connection setup failure: out of the consideration of retransmission times and waiting time, the UE fails to receive the response from RNC or receives the RRC CONNECTION REJECT message after sending the RRC CONNECTION REQUEST message.

Step 2 Initial direct transfer and security mode setup failure: after the UE sends the RRC CONNECTION SETUP COMPLETE message, it fails to send the NAS SETUP message.

Step 3 RAB assignment failure: after the UE receives the CALL PROCEEDING message, it fails receive the RB SETUP message from RNC. Or the UE responds RB SETUP FAIL message after receiving the RB SETUP message. Or the UE receives the DISCONNECTION message with the cause normal release after receiving the RB SETUP message, when the UE does not send the RB SETUP CMP message.

Step 4 The failure after RAB assignment: after the UE sends the RB SETUP COMPLETE message:



l The originated UE receives the DISCONNECT/RELEASE message from CN l The originated UE waits for the CONNECT or ALERTING message until expiration, so

the call clearing process is originated. According to the protocols, after the UE sends the CM SERVICE REQUEST message, the timer T303 starts. If the UE fails to receive the CALLPROCEEDING, ALERTING, CONNECT, OR RELEASE COMPLETE message before expiration of T303, the clearing process starts.

l Before receiving alerting message, the UE enters the idle state and starts to receive system information.

As strictly defined, after the MS enters the CELL_DCH state and before it receives the alerting message, it must send the cell update message with the cause RLC unrecoverable error/ Radio link failure. Take the greater value of the maximum waiting time configured at RLC layer as default and the synchronization time as the judgment time. It is unclear that the UE can report the RLC layer message, so the maximum waiting time is neglected.

----End

Terminated Call Failure in CS Domain The terminated UE receives the paging of type 1, but it does not send the RRC CONNECTION REQUEST message with the cause Terminating Conversational Call or does not send the direct transfer message alerting to CN.

Detailed failure stages include:

Step 1 RRC connection setup failure

After the UE sends the RRC CONNECTION REQUEST message, it fails to receive reply from RNC or receives the RRC CONNECTION REJECT message from RNC.

Step 2 Initial direct transfer and security mode setup failure

After the UE sends the RRC CONNECTION SETUP COMPLETE message, it fails to receive the SETUP direct transfer message, it sends the RELEASE COMPLETE message, or the UE receives the DISCONNECT message from CN.

Step 3 RAB assignment failure

After the UE sends the CALL CONFIRM message, it fails to receive the RB SETUP message from RNC. Or after it receives the RB SETUP message, it replies RB SETUP FAIL message. Or after it receives the RB SETUP message, it receives the DISCONNECT message not due to normal release cause, when the UE has not sends the RB SETUP CMP message.

Step 4 Failure after completion of RAB assignment

After the UE sends the RB SETUP COMPLETE message, the called UE receives the DISCONNECT/RELEASE message from CN

As strictly defined, after the UE enters the CELL_DCH state, it sends the cell update message with the cause RLC unrecoverable error/ Radio link failure before receiving the alerting message. The judgment time should be the greater of maximum waiting time and a synchronization time configure by default at the RLC layer. It is unknown that the test UE can report RLC layer messages, so neglect the strict definition.

----End



3.2.2 Definition of Access Failure by Actix Analyzer The Actix Analyzer defines access failure according to the following principles: after the originated UE sends the RRC Connection Request message, access failure occurs upon any of the following conditions:

l The UE receives the RRC Connection Reject message l It sends or receives the RRC Connection Release message after receiving RRC

Connection setup l It receives any message from BCCH during Call setup message l The timer expires. Namely, a period (T300) after the UE sends the RRC Connection

Request message, it fails to receive the RRC Connection setup message

3.2.3 Definition of Access Failure by TEMS The TEMS defines access failure (for originated voice services) according to the following principles:

Step 1 Random access failure: after dialing, the UE fails to send the RRC Connection Request message.

Step 2 The UE fails to receive the RRC Connection Setup message: after the UE send the RRC Connection Request message, it fails to receive the RRC Connection Setup message.

Step 3 The UE fails to send the RRC Connection Complete message: after the UE receive the RRC Connection Request message, it fails to send the RRC Connection Setup message.

Step 4 The UE receives the RRC Connection Reject message: the UE receives the RRC Connection Reject message, and does not resend the RRC Connection Request message for try.

Step 5 The UE fails to receive the measurement control message: after the UE sends the RRC Connection Complete message, it fails to receive the measurement control message.

Step 6 The UE fails to send the CM Service Request message: after the UE receives the measurement control message, it fails to send the CM Service Request message.

Step 7 The UE receives the Service Request Reject message.

Step 8 The UE fails to receive the Call Proceeding message: after the UE sends the CC SETUP message, it fails to receive the Call Proceeding message.

Step 9 The UE fails to receive the RB Setup message: after the UE receives the Call Proceeding message, it fails to receive RB Setup message.

Step 10 The UE fails to send the RB Setup Complete message: after the UE receives the RB Setup message, it fails to send the RB Setup Complete message.

Step 11 The UE fails to receive the Alerting or Connect message: after the UE sends the RB Setup Complete message, it fails to receive theAlert or Connect message.

Step 12 The UE fails to receive the Connect Acknowledge message: after the UE receives the Alerting or Connect message, it fails to send the Connect Acknowledge message.

----End



3.3 Flow and Methods for Analyzing Access Failure Problems 3.3.1 Overall Flow for Analyzing Call Failure Problems

Figure 3-1 shows the overall flow for analyzing call failure problems.

Figure 3-1 Overall flow for analyzing call failure problems in DT/CQT

By DT data analyzing tool, such as Actix Analyzer and GENEX Assistant, determine the time for Call Fail and obtain the following information:

l Pilot information collected by scanner before and after Call Fail l Information about active set, monitor set, and signaling flow collected by UE

Match the signaling collected by UE and the time of single subscriber tracing by messages. Meanwhile locate the points when problems occur in single subscriber tracing on RNC.

Based on signaling of single subscriber tracing on RNC and UE's signaling flow, determine the point where call fails occurs according to Figure 3-1. Analyze and solve problems according to following sub-flows. The problems include:

l Paging problems l RRC setup problems l RAB and RB setup problems l Authentication and encryption problems



l Abnormal equipment problems

3.3.2 Analyzing Paging Problems Paging problems usually are: the originated UE completes RAB assignment and CC Setup and waits for Alerting message, when it receives the Disconnect direct transfer message from CN. Figure 3-2 shows the signaling flow of originated UE in locating paging problems. According to the signaling flow of called UE, the signaling flow is normal. It occurred that after receiving Paging message it does not originate RRC connection setup request. According to the single subscriber tracing of called UE on RNC, the RNC receives the Paging message from CN without following messages.

Figure 3-2 Signaling flow of originated UE in locating paging problems

The causes of paging problems include:

l The RNC does not send the Paging message. l The power of paging channel and paging indicator channel is low. l The UE reselects a cell.



Figure 3-3 shows the flow for analyzing paging problems.

Figure 3-3 Flow for analyzing paging problems

The following sections described detailed analysis.

Failure in Sending Paging Message by RNC After the RNC receives the paging message from CN, the UU interface does not send the message. Probably the capacity of paging channel is inadequate (currently the network load is low, so it is less probable that the paging channel is congested at UU interface. When the network load is heavy, it is probable) or the equipment is abnormal.

Over Low Power of PCH or PICH After the RNC sends a paging message, the UE fails to receive it. For this problem, check the Ec/Io of the cell where the UE camps and the cell which it monitors. If the Ec/Io of both cells is lower than –12 dB, the power of PCH or PICH is over low or the coverage is weak.

Cell Reselection by UE If the signals of the cell where the UE camps are weak while the signals of monitored cell are strong, the problem might be due to cell reselection. When the UE has its location area (LA) or route area (RA) updated upon paging, the paging message is sent to the original LA or RA, so the UE fails to receive paging message.



3.3.3 Analyzing RRC Connection Setup Problems The RRC connection setup failure can be analyzed through UE signaling flow and single subscriber tracing on RNC. The RRC connection setup process includes the following steps:

Step 1 The UE sends RRC Connection Request message on RACH.

Step 2 The RNC sends the RRC Connection Setup message on FACH.

Step 3 After the UE sets up downlink DCH and synchronizes with it, it sends the RRC Connection Setup CMP message on uplink DCH.

----End

RRC setup fails due to the following causes:

l Uplink RACH problems l Downlink FACH power allocation ratio l Cell reselection parameter problems l Over low transmit power of downlink DCH l Uplink initial power control problems l Congestion l Abnormal equipment problems

Among previous problems, the uplink RACH problem, downlink FACH power allocation ratio problem, cell reselection parameter problem, and abnormal equipment problem are probable.



Figure 3-4 shows the flow for analyzing RRC connection setup problem.

Figure 3-4 Flow for analyzing RRC connection setup problem

The details analysis is as below:

After UE Send RRC Connection Request Message, the RNC Fails to Receive It If the Ec/Io of downlink CPICH is over low, the problem is about coverage.

If the Ec/Io of downlink CPICH is not over low (such as higher than –14 dB), the problem is about RACH, with the following causes:

l The power step of preamble is small l The output power of UE is lower than required. l NodeB is problematic with standing wave. l The parameter of cell radius is improperly configured.

If the power ramp of preamble is small, you can add the preamble ramp times. For example, increase it from 8 to 20.

If the output power of UE is lower than required, there are no specific methods to solve it due to the limitation of UE performance.

For NodeB problems, check whether there is standing wave alarm on NodeB.



If the parameter of cell radius is set over small, the NodeB cannot synchronize with the UEs beyond cell radius. This causes access failure. This usually occurs in wide coverage scenarios like rural and suburban areas.

After the RNC Receives the RRC Setup Request Message from UE, It Sends the RRC Connection Setup Message Which Is Not Received by UE

The causes of this problem include:

l Weak coverage l Improper parameters of cell selection and reselection

Check the CPICH Ec/Io. If it is lower than –12 dB (the default value is configured based on Ec/Io as –12 dB) and

l If there is no more qualified cell listed in the monitor set, the problem is about coverage. l If there is more qualified cell listed in the monitor set, the problem is about cell

reselection.

Solutions are as below:

l When the coverage is weak: If conditions permit, solve coverage problems by enhancing coverage, such as adding sites to cover blind areas and adjusting engineering parameters. If you cannot enhance the coverage, you can increase FACH power. Adjust FACH power according to the coverage conditions of PCPICH Ec/Io. For example, the pilot Ec/Io in all coverage areas after network optimization is larger than –12 dB, the success rate for UE to access from 3G idle mode can be guaranteed if the common channel power is allocated on the condition of Ec/Io equal to –12 dB. When Ec/Io is smaller than –14 dB, the UE reselects a GSM cell. The success rate of RRC setup in weak coverage areas after inter-RAT reselection by UE can be guaranteed if the common power is allocated on the condition of Ec/Io larger than –14 dB.

l Cell selection and reselection: Adjusting cell selection and reselection parameters accelerates cell selection and reselection and helps solve RRC connection setup failure problems caused by improper parameters of cell selection and reselection.

The RRC CONNECTION SETUP message is carried by FACH. After the UTRAN side receives the PRACH preamble, the UE sends the RRC CONNECTION REQUEST message on RACH based on current preamble power. The preamble transmit power keeps increasing until response is received (restricted by maximum retransmission times of preamble). Therefore, in poor coverage areas, unbalanced coverage by RACH and FACH is probable. Consequently the UTRAN side can receive the RRC CONNECTION REQUEST message while the UE fails to receive the RRC CONNECTION SETUP message.

After the RNC Receives the RRC Setup Request Message from UE, It sends the RRC Connection Reject Message

When the RRC Connection Reject message is present, check the cause values, which include congestion and unspecified.

If the cause value is congestion, the network is congested. Check the network load conditions, including utilization of power, code, and CE resources. Determine the type of resource that causes congestion and provide ways of network expansion. For details, see W-Network Expansion Guide.



The admission of RRC connection for HSDPA subscribers is consistent with that for R99 subscribers, including power, code, and CE resources. Pay special attention to code admission. If the code word of HSDPA subscribers is statically assigned, and excessive codes are assigned to HSDPA subscribers, the RRC connection of HSDPAor R99 subscribers fails probably. This is due to that the codes of downlink signaling channel for HSDPA or R99 subscribers are inadequate.

If the cause value is unspecified, check the logs to determine causes of failure.

After Receiving RRC Connection Setup Message, the UE Does Not Send Setup Complete Message

If the downlink signals are normal, the UE might be abnormal. Otherwise initial power of downlink DCH is over low so the downlink cannot synchronize. You can solve the problem by adjusting uplink Eb/No of the service.

After the UE Sends the RRC Setup Complete Message, the RNC Fails to Receive It

It seldom occurs because uplink initial power control leads to increment of UE transmit power. Upon presence of the problems, you can properly raise the Constant Value of DCH so that the initial transmit power of uplink DPCCH of UE increases.

This problem is related to whether the initial target value of uplink SIR is rational and has great impact on uplink initial synchronization at the beginning of link setup.

l If it is set over large, the uplink interference from initial link setup of subscriber becomes over large.

l If it is set over small, the uplink synchronization time increases, and consequently the initial synchronization fails.

This parameter is an RNC-level parameter. It has great impact on network performance, so engineers must be cautious upon adjustment.

The RRC Connection Setup Complete message is sent on uplink DPCH. The UE calculates the initial power of DPCCH according to received IE DPCCH_Power_offest and measured CPICH_RSCP. DPCCH_Initial_power = DPCCH_Power_offset - CPICH_RSCP Wherein, DPCCH_Initial_power = Primary CPICH DL TX Power + UL Interference + Constant Value Constant Value can be configured at OMC. If it is set over small, the UE has lower power to send the RRC CONNECTION SETUP COMPLETE message than required. Current default configuration of Constant Value (the default value of it in version V13C03B151 is –20) usually prevents this problem from happening.

3.3.4 Analyzing Authentication Problems When authentication fails, analyze the problem according to the cause value provided in the authentication failure message replied from UE to the network. Two common cause values include MAC Failure and Sysch Failure.



MAC Failure Check the AUTN parameter in the authentication request message send by network side upon the authentication of network by UE. If the MAC information is incorrect, the UE send the authentication failure message with the cause value MAC failure, shown as in Figure 3-5.

Figure 3-5 Authentication failure due to MAC Failure

The major causes of the problem include:

l Unauthorized subscriber l USIM and HLR set different Ki and OP (OPc) for the subscriber

This problem occurs frequently when a subscriber uses a new USIM. To locate this problem, check whether the Ki and OP (OPc) value of the IMSI are the same. The USIM has default Ki and OP (OPc), but the USIM reader fails to obtain the value. Therefore, the Ki and OP (OPc) of the USIM must be known upon defining a subscriber or the Ki and OP (OPc) of USIM must be made the same value as in HLR.



Sync Failure When the UE detects that the SQN of AUTN message is incorrect, so the authentication fails. The cause value is Synch failure (synchronization failure), as shown in Figure 3-6.

Figure 3-6 Authentication failure due to Synch Failure

The causes of the problem include:

l Authorized subscribers l Equipment problems

3.3.5 Analyzing Security Mode Problems During the security mode control process, the network side sends encrypted information to radio access network (RAN). During the process, the CN side and RAN negotiate to perform encryption algorithm on UE so that the UE uses the encryption algorithm in the subsequent transfers. After the UE performs handover, it can use the encryption algorithm as possible. Namely, the encryption-related parameters are sent to the target RNC.

Figure 3-7 shows the security mode control.

Figure 3-7 Security mode control



Figure 3-8 shows the Security Mode Reject.

Figure 3-8 Security mode reject

The common causes of security mode reject include:

l The UE is unable to support configured encryption algorithm. l The encryption model configuration of RNC does not match that of CN. For example,

the MSC configures the encryption algorithm UEA0 only but the RNC configures UEA1 only.

UE Capability Problems To check the UE capability, refer to the RRC Connect Setup CMP message.

Currently the following UEs fail to support encryption algorithm:

l NEC single-mode UEs l NEC C606 l NEC C616

The following UEs support encryption algorithm:

l Nokia 7600 l Nokia 6650 l Moto A835 l Qualcomm 6200 l Qualcomm 6250 l Siemens U15

To solve the security mode reject problems due to UE capability, change the UE.

Inconsistent Configuration of RNC and CN Encryption Mode Check the MSC or SGSN and RNC whether they have selected the same encryption mode. Namely they must have the same encryption mode.

If the encryption modes are different, set the MSC and SGSN to the security mode selecting all. Set the RNC to select UEA0 or UEA1.

3.3.6 Analyzing PDP Activation Failure Problems For analysis of PDP activation failure problems, see the section 5.1 of W-PS Problem Optimization Guide.



3.3.7 Analyzing RAB or RB Setup Problems When the RAB or RB setup fails, the RNC responds RAB assignment setup failure in the RAB Assignment Response message. Locate the specific failure causes through the failure cause value contained in the related cells.

Common RAB/RB setup failure problems include:

l The RNC directly rejects RAB setup request due to incorrect parameter configuration. l Admission rejection l RAB setup fails due to response of RB setup failure from UE l RAB setup fails due to RB setup failure at air interface

Direct Rejection of RAB Setup Request by RNC Due to Incorrect Parameter Configuration

It seldom occurs that the RNC directly rejects RAB setup request due to incorrect parameter configuration. This occurs due to special operations by special subscribers. It occurs when the RNC directly rejects RAB setup request because subscribing information for PS service in HLR exceeds the UE capability.

For example, the traffic for a special subscriber is 384K in uplink and downlink, but the maximum uplink capacity is 64K. The subscriber sets the uplink and downlink maximum rate in QoS of activation PDP to 384K by using the AT command and UE software (Sony-Ericsson UE software can set QoS of activation request). When the RNC receives the RAB assignment request, it finds that the requested uplink maximum rate exceeds the UE capability, so it directly responds RAB setup failure without originating RB setup.

After the RAB setup fails due to incorrect parameter configuration that exceeds UE capability, the SGSN will renegotiate to originate new RAB assignment until the UE can support and the system completes RAB assignment. For subscribers, the PDP activation can still be successful and the maximum rate obtained from indicator is the maximum rate supported by UE. If the minimum guaranteed rate requested in QoS setup in PDP activation request by UE exceeds UE capacity, the network accepts the PDP activation request by UE at a negotiated low rate; however, when the negotiated rate of network in the PDP activation acceptance message, the UE originates deactivation PDP request. Therefore, PDP activation fails finally.

Admission Rejection For non-HSDPA subscribers, when the system resource (power, code, channel code, Iub transmission resource, and Credit) is inadequate, the admission is rejected and consequently call setup fails. Now you must check the uplink and downlink load, code resource, Iub transmission resource, and CE resource, determine the type of resource that causes congestion, and provide corresponding expansion methods.

l When excessive codes are statically assigned to HSDPA subscribers, the admission fails due to inadequate downlink channel code resource for non-HSDPA subscribers. When the system resource is inadequate and admission fails, the V1.5 or higher RNC conducts different operations according to RAB Downsizing Switch state. For details, see the description of solving inadequate lub bandwidth.

l If the cell does not support the HSDPA service, the admission of R99 subscribers depends on the set R99 admission threshold. If the cell supports the HSDPA service and the downlink power of HSDPA and R99 subscribers is statically assigned, the power admission of non-HSDPA subscribers is judged by (total power of cell - the power statically assigned to HSDPA) * admission threshold. When the power of HSDPA and



R99 subscribers is dynamically assigned, the power admission of non-HSDPA subscribers is consistent with that of original R99 subscribers. The uplink admission decision is based on the RTWP or equivalent number of subscribers. If the uplink load is too high, the admission of non-HSDPA subscribers is rejected.

l If the bandwidth of the lub interface is inadequate, activation of R99 high-speed data services fails due to the limited bandwidth. For example, the AAL2 bandwidth for service on lub interfaces in many cells can support only a 384 Kbps service. If a 12.2 Kbps voice service already exists, the lub interface fails to provide enough bandwidth for a 384 Kbps PS service. In the case of RNC V1.3, the RNC returns an SGSN RAB assignment failure because the requested rate is unavailable. The SGSN then originates RAB assignment through re-negotiation. In the case of RNC V1.5 or later versions, the RNC lowers the rate first if the RAB Downsizing switch is on. If the lub resource is available after the rate is down, the RNC sends a RAB assignment success message to the SGSN. If the lub resource is not available even though the rate is down to 8 Kbps, the RNC returns an SGSN RAB assignment failure. The SGSN then decides whether or not to originate renegotiation based on its internal parameters. If the RAB Downsizing Switch is off, the processing is the same as that in the case of RNC1.3.

l The admission control of NodeB Credit resources is similar to the power admission control. Whether the available Credit can support the currently requested service depends on the spreading factor of the new subscriber. If the current Credit is not adequate, the RNC performs different processing depending on state of the RAB Downsizing switch in the case of RNC V1.5 or later versions. For details, see the handling in the case of inadequate bandwidth of the lub interface as described earlier in this document.

For the admission rejection of HSDPA subscribers, consider the following aspects:

l In the method for statically assigning power of HSDPA and R99 subscribers, consider: − HSDPA subscribers supported by NodeB − HSDPA subscribers supported by cell − Total bit rate of cell − Total guaranteed bit rate − Whether the cell transmit power guaranteed bit rate exceeds the prescribed threshold

l In the method for dynamically assigning power of HSDPA and R99 subscribers, consider: − HSDPA subscribers supported by NodeB − HSDPA subscribers supported by cell − Whether the guaranteed bit rate exceeds the prescribed threshold

For HSDPA subscribers, when the configured bandwidth at lub interface is inadequate, admission rejection will not occur, but the rate become lower. In addition, the AAL2PATH of HSDPA and R99 is respectively configured, and HSDPA AAL2PATH must be configured to HSDPA RT or HSDPA NRT type. If the HSDPA AAL2PATH is configured to R99 AAL2PATH RT or NRT type, RAB assignment will not fail, but the RNC will directly set up HSDPA service to R99 384kbps.

For V17, strategies of the RRM admission algorithm change as follows:

l Downlink power admission control for HSDPA cells is supported. Only dynamic power assignment is available. For the DCH service, consider whether load of the non-HSDPA service (the R99 service) exceeds the admission threshold of the non-HSDPA service (that is, the admission threshold of the original R99 service). In addition, consider whether the non-HSDPA power and the HSDPA GBP (Power to meet GBR) exceed the



threshold of total power of the cell. For the HSDPA service, check whether the HSDPA throughput provided by the cell exceeds the threshold of sum of Guaranteed Bit Rates (GBR) of all subscribers, or whether the GBP of stream services and background services exceeds the HSDPA power of the cell. In addition, consider whether the non-HSDPA power and the HSDPA GBP exceed the threshold of total power of the cell.

l lub interface admission: For the DCH service, the admission depends on the peak bit rate multiplied by the activation factor of the service. For the HSDPA service, the admission depends on the GBR. If the lub interface reaches the congestion threshold, DCCC downsizing occurs. If the RLC_AM re-transmission ratio exceeds the specified threshold, run the SET CORRMALGOSWITCH command to enable lub Overbooking. In this case, TF of the R99 occurs or rate of the HSDPA service decreases based on the related factor. Run the ADD AAL2ADJNODE command to set the service activation factor and the lub congestion threshold. Run the ADD TYPRABRLC command to set trigger and release thresholds of RLC_AM re-transmission.

The UE's Response of RAB Setup Failure due to RB Setup Failure The UE responds RB setup failure due to subscribers' wrong operations.

One case is as blow:

When subscribers are using a downlink 128K data service, they receive the RB setup request of VP service (originating or terminating VP). Because most UEs cannot support performing VP and high rate PS service simultaneously, the UE directly responds RB setup failure due to unsupported configuration.

The other case is as below:

The UE called by 3G UE for VP service camps on GSM network, so it does not support VP service. Therefore, after the RNC receives RAB assignment request, the CN sends the Disconnect command after call proceeding due to Bearer capability not authorized. Now the UE has just received RB_SETUP command, so it has not completed RB setup. After receiving the Disconnect message, it immediately responds RB setup failure, so the RNC responds RAB setup failure due to failure in radio interface procedure.

RAB Setup Failure due to RB Setup Failure at Air Interface Another RB setup failure is as below:

No response to RB setup is received, so the RNC judges that RB setup fails. In details, no ACK or RB setup complete message is received for RB setup. This occurs in weak coverage areas, because the UE does not camp on the best server and originate access, or the coverage is weak.

The UE does not originate to access the network in the best server, so it wishes that the best server (sharp fluctuation of signals leads to sharp fading of signals in the cell on which the UE camps) can be added to the active set during RB setup. The flows cannot be nested (both the network and UE does not support nested flow), so the active set is updated after RB setup is complete. This leads to RB setup in weak coverage cells, so RB setup fails probably. For this case, increase the threshold and speed for starting selection of intra-frequency cells so that the UE can camp on the best server as quickly as possible. If the network load at early stage is low, the UE originates to access the network in the best server, set the threshold for starting selection of intra-frequency to –4 dB and set Treselection to 1. For cells at edge of different LACs, set the threshold lower to decrease signaling traffic of location area update.

The RB setup failure due to weak coverage includes unqualified uplink and downlink coverage.



The RB setup failure due to downlink weak coverage is as below:

The UE fails to receive the RB setup command. Unqualified downlink coverage is partially due to poor demodulation performance of UE. It must be solved by RF optimization.

The RB setup failure due to downlink weak coverage is as below:

The UE receives the RB setup command, but the RAN fails to receive the ACK message or RB Setup Complete message for RB setup. This is probably due to uplink interference. Check RTWP for this.

3.3.8 Analyzing Access Problems in the Case of Dualband Networking

At present, two networking strategies are available:

l Strategy 1 (f1: R99; f2: R99+HSPA) l Strategy 2 (f1: R99+HSPA; f2: R99+HSPA)

Figure 3-9 and Figure 3-10 show the dualband scenarios.

Figure 3-9 Dualband scenario 1 (f1: R99; f2: R99+HSPA)

Figure 3-10 Dualband scenario 2 (f1: R99+HSPA; f2: R99+HSPA)

R99+HSPACELL 3

R99+HSPACELL1

R99+HSPACELL 2

R99+HSPACELL4

R99+HSPACELL5

R99+HSPACELL6

f2

f1

This section describes access process in the case of dualband networking only.

The access in the case of dualband networking involves direct retry and re-direction in the RRC connection stage and RAB direct retry. RAB direct retry includes service-based direct retry and that after admission failure. The direct retry and re-direction algorithms are used to increase first put-through ratio of the UE.

The following figure shows functions and process of RRC direct retry and re-direction during setup of the RRC connection.



Figure 3-11 Functions and process of RRC direct retry and re-direction during setup of the RRC connection

If the RNC receives a RRC connection request, the admission algorithm decides whether a RRC connection is allowed between the UE and the current cell based on the load over the current cell.

l If the RRC connection is allowed, the RNC sends a RRC CONNECTION SETUP message to the UE, and then the UE sets up a RRC connection.

l If the RRC connection is not allowed, the RNC direct retry algorithm module searches for a cell that complies with the direct retry algorithm in the UE candidate list. − If a suitable target cell exists, the RNC sends the target cell data to the UE through a

RRC CONNECTION SETUP message. − If no suitable cell exists, the RNC re-direction algorithm selects another suitable

frequency or radio access system (such as GSM), and then notifies the UE of the REDIRECTION cell through a RRC CONNECTION REJECT message. The UE originates an access request in the specified frequency or system.

The RAB direct retry includes service-based direct retry and RAB direct retry after admission failure.

l Service-based direct retry If a R99 cell and a HSPA cell are at different frequencies but with the same coverage, subscribers who are requesting for the R99 service are assigned to the R99 cell and those who are requesting for the HSPA service are assigned to the HSPA cell if possible. Thus, the R99 service is separated from the HSPA service.

l Direct retry after admission failure After admission failure, the subscriber can be connected to a cell at another frequency with the same coverage, a HCS cell at another frequency, or a cell in another system (for the AMR service only).



If admission of the HSPA service fails and the direct retry fails in all cells, the service returns to the DCH of the local cell and a RAB connection is set up on the DCH again.

In dualband scenario 1, the services are carried in R99 cells as the strategy. In this case, the real-time services do not need inter-frequency direct retry during call setup. Thus, the impact on real-time services decreases and the HSPA subscribers can access the cells that support HSPA through service-based direct retry. To make the UE reside in F1, modify the cell selection and reselection parameter Qoffset2,n of F1 to 50 dB and that of F2 to -50 dB, or bar F2.

In dualband scenario 2, the strategy of random cell residence is used. The UE originates service access in the serving cell. All cells that use two carriers adopt the default value of the Qoffset2,n parameter.

In both scenarios, RRC or RAB direct retry is available for the R99 service and RAB direct retry after admission rejection is available for the HSPA service. If the direct retry of the HSDPA service fails, the service returns to the DCH of the local cell and an RAB connection is set up on the DCH again.

Example 1: In scenario 1, the HSDPA data card resides in the R99 cell. If the PDP is activated, the subscriber accesses the HSDPA cell through direct retry. Figure 3-12 shows the signaling for a service-based direct retry.

Figure 3-12 Signaling for service-based direct retry of a HSDPA subscriber



Example 2: In scenario 1, the admission threshold of the R99 service is exceeded if several R99 subscribers access the cell. If one more R99 subscriber tries to access the cell, the admission is rejected in the R99 cells at F1. In this case, the subscriber accesses a R99+HSDPA cell through direct retry. Figure 3-13 shows the signaling for direct retry after admission rejection.

Figure 3-13 Signaling for direct retry of a R99 subscriber after admission rejection

3.3.9 Analyzing MBMS service access problems MBMS(Multimedia Broadcast and Multicast Service) provides unilateral service from

single point to multi-point. It permits one resource entity transmits data to several receiver entities. MBMS provides three kinds of network model, including Broadcast, Enhanced broadcast and Multicast. RNC Version18 and Version 29 only support broadcast model and flow service.

Figrure3-14 shows the flow chart of broadcast model in MBMS.



Figure 3-14 Flow chart of broadcast model in MBMS

If the MBMS cell is activated, UTRAN will transmit MBMS system information which includes scheduling information of MCCH and configuration information of MCCH radio bearer on BCCH repeatedly.

First, network announces UE by SMS or WEB that MBMS service will be broadcasted. After UE decides to receive MBMS service, it will setup the radio bearer of MCCH according to the MBMS system message received by UE (corresponding to Service Announcement).

After RNC receiving the MBMS Session Start message from SGSN, it will setup IU signaling bearer and service bearer related to MBMS (corresponding to Session Start).

RNC announces UE the change of MCCH information by MICH channel, UE gets the information of available MBMS service and MTCH-related radio bearer from MCCH channel (corresponding to MBMS Notification).

UE monitors MTCH, begins to receive data (corresponding to Data Transfer).

Judging that no data is transmitted in a period, BM-SC sends Session Stop message to announce GGSN/SGSN/RNC to release the related network resource (corresponding to Session Stop).

The causes that UE can’t receive programs include:

1. MBMS service fails in RNC setup, the cause of this failure in current cells can be searched by MML command: DSP CELLMBMSSERVICE.

This command can indicate the following causes for MBMS service failure:

Access Failure, Common Channel Fault, HPU Link Setup Failure, OLC Release, Preempted, Adding cell to multigroup Failure, MCCH Scheduling Failure, PA Parameter Invalid, RLC Parameter Invalid and Invalid value.

Besides, we can check whether RNC MBMS enable switch is on by MML command: LST MBMSSWITCH.



2. If MBMS service is already setup in RNC, but there’s no information in cell, using the following steps to locate problem:

1) Check whether the cell is in corresponding SA(Service Area) by MML command: LST CELLMBMASA and LST MBMSSA.

2) Check whether the MBMS is available in this cell by MML command: DSP CELLMBMSSERVICE. If MBMS isn’t activated, activate it by ACT CELLMBMS.

3) Check whether there’s SCCPCH to carry this service and whether it’s activated, if not activated, activate it by ACT SCCPCH.

3. Service is already setup in cell, but no data is seen sent down according to RNC HPU.

1) First, check out whether there’s data in GGSN

2) Check whether the SGSN user plane address of service is correct.

4. UE keeps staying in CONNECTION state:

This indicates that UE doesn’t read the data on MTCH. This may be caused by TBSIZE configuration problem or incorrect MCCH configuration in SET MTCHFACH.

5. The buffer of UE is 100%, but there’s only voice without figure.

Usually it is because the rate of program resource is higher than the maximum bearer rate of channel.

6. UE quits after several seconds of receiving normal program.

The common channel priority in SET MTCHFACH is configured improperly to overlap that in ADD FACH.

3.4 Processing Access Delay The access delay is usually affected greatly by equipment factors, so optimizing it is hard. If it is greatly different from default index, check whether the parameter configuration is consistent with the default.

A typical process for calls is from sending the RRC CONNECTION REQUEST by originating UE to receiving Alerting message by UE. In terms of signaling flow, the following aspects affect access delay:

l Configuration of discontinuous cyclic period duration factor DRX l Whether to disable authentication and encryption l Early assignment or late assignment l Whether the RRC connection is set up on FACH or DCH l The impact from 13.6K and 3.4 K of signaling connection on delay



3.4.1 Configuration of Discontinuous Cyclic Period Duration Factor DRX

During proceeding delay of paging one UE by another, the paging delay takes the majority. On the one hand, if the configured power of paging channel and paging indicator channel is so improper that the paging message is resent, this increase proceeding delay. On the other hand, DRX determines the time for sending paging message. An overhigh DRX leads to long delay.

When DRX is 6, 7, and 8, the paging period is respectively 640ms, 1280ms, and 2560ms. In terms of statistics probability, if enough UEs originate enough calls, the traffic is in Poisson distribution and the average access delay keeps increasing. According to on-site test result, when DRX is 8, most paging delays are between 1s and 1.5s. The longest paging delay is even longer than 2.5s. When DRX is 6, the paging delay is evenly distributed between 0.35s and 0.95s. Therefore, setting DRX to 6 can effectively lower proceeding delay.

Setting DRX to 6 leads to accelerated power consumption by UE, so you must consider this with the actual network conditions. At the beginning of network operation, the key is to raise the RAN performance. According to partners' signaling, such as Nokia, Ericsson, ZTE, and Lucent, setting DRX to 6 is the majority.

3.4.2 Whether to Disable Authentication and Encryption Flow According to test result,

l For voice calls, the proceeding delay after enabling authentication and encryption flow is 0.6s longer than proceeding delay after disabling authentication and encryption.

l For VP calls, the proceeding delay after enabling authentication and encryption flow is 0.74s longer than proceeding delay after disabling authentication and encryption.

For network security, combined ways of multiple authentications are used at the beginning of network normal operation. For example, 1/2 authentication is used for location area update authentication; some services, such as voice, VP, and short messages, use the synchronization method based on 1/2 authentication; other services use the Always authentication method.

3.4.3 Implementing Early or Late Assignment The different between early and late assignment lies in the different assignment time for TCH.

Early assignment Late assignment

Terminating call Starting assignment before the call is answered

Starting assignment after the call is answered

Originating call Starting assignment before the Alerting message

Starting assignment after the Alerting message

Early assignment increases call completion rate. Late assignment avoids occupation of TCH resource during ringing, so it increases the utilization of TCH resource.

According to test result, the UE receives Alerting message 1.28s earlier in early assignment than in late assignment. Using late assignment helps to receive response signals (ringing) from network more quickly, so it is more rational. However, the UE might fail to put through,



so late assignment affects call completion rate. You must balance the advantages and disadvantages before using it.

3.4.4 Whether the RRC Connection Is Set up on FACH and DCH According to test result, when the request signaling of RRC connection originated by UE is set up on FACH, the average setup duration of voice calls is 0.601s shorter than that set up on DCH3.4K and 0.491s shorter than that set up on DCH 13.6K. The signaling of RRC connection set up on DCH 13.6K comparatively occupy more resource, it is recommendable if the resource at early stage of network operation is adequate.

Note that after RRC connection setup, the signaling is reconfigured on DCH3.4K upon RB setup.

3.4.5 Impact of Direct Retry on Access Delay The direct retry and re-direction algorithms can increase the first put-through ratio of the UE; however, they prolong the access delay. If the access fails due to cell congestion or failure of resource allocation during the RRC connection setup, direct retry of the RRC connection setup occurs. The RNC enables the UE to access another cell at another frequency through Frequency info and Primary CPICH info in the RRC CONNECTION SETUP message. This prolongs the access delay during the RRC connection setup.

If all direct retries of the RRC connection setup fails, RRC re-direction occurs. The re-direction algorithm leads the UE to access a cell at another frequency or a cell in the GSM system through Redirection info in the RRC CONNECTION REJECT message and cell reselection of the UE. Compared with the RRC direct retry algorithm, the re-direction algorithm needs cell reselection, though they have the same triggering condition. Thus, the subscribers find that access delay increases in the case of the re-direction.

In the case of RAB direct retry based on service separation or admission failure, the RNC makes the UE to access a cell at another frequency through Frequency info and Primary CPICH info in the RB SETUP message. This prolongs the access delay during RB setup. The field test shows that the RAB direct retry prolongs the access delay by 220ms. Table 3-1 lists RB setup delay on the RNC with or without DRD.

Table 3-1 RB setup delay on the RNC with or without DRD

RAB_ASSIGNMENT -> RB_SETUP(Avg.)

RB_SETUP -> RB_SETUP_CMP(Avg.)

Total(Avg.)

HSPA service with DRD

80 ms 810 ms 890 ms

HSPA service without DRD

80 ms 590 ms 670 ms

l The data listed in the preceding table is measured on the RNC. l The data listed in the preceding table is measured when the activation time of high-speed link is set

to 400ms.



4 Analyzing Traffic Statistics Data

Analyze traffic statistics data in the following two situations:

l Evaluating network performance Analyze and locate the indexes with different network performance requirements, locate the problem, and enhance network performance.

l Network performance precaution Find the factors in advance that might lead to deterioration of network performance. This helps avoid deterioration of network performance.

This chapter addresses how to analyze traffic statistics data in the first situation. It first provides a general flow for analyzing traffic statistics data, and then describers the consideration and methods for analyzing major indexes.

The version of RNC used here for analyzing traffic statistics data is BSC6800V16C01B064.

4.1 Tool for Analyzing Data The tool for analyzing traffic statistics data is GENEX Nastar.

4.2 General Methods for Analyzing Traffic Statistics Data In terms of statistics targets, analyzing traffic statistics data includes analyzing RNC-level data and cell-level data. Analyzing RNC-level data addresses assessment and analysis of overall network indexes. Analyzing cell-level data helps locate problematic cells. The flow for analyzing RNC-level data contains the flow for analyzing cell-level data.

In actual traffic statistics analysis, the flow is as below:

l Assess overall network indexes l Locate cell-level problems

Therefore, in RNC traffic statistics, the counters for failure cause type is usually cell-level. In the following sections, priority is given to cell-level indexes.



4.2.1 Flow for Analyzing RNC-level Traffic Statistics Data Figure 4-1 shows the flow for analyzing RNC-level traffic statistics data.

Figure 4-1 Flow for analyzing RNC-level traffic statistics data

Analyzing RNC-level traffic statistics data proceeds as below:

l Check whether RNC-level traffic statistics indexes meet requirements If yes, the analysis ends. If no, find the first N cells with worst indexes and analyze the cell indexes.

l After locating cell problems and carrying out solutions, analyze the new data of traffic statistics If the new indexes meet requirements, the analysis ends. If there are still problems, continue the analysis until the indexes meet requirements.



For the methods and flow for analyze problematic cells, see the flow for analyzing cell-level traffic statistics data.

4.2.2 Flow for Analyzing Cell-level Traffic Statistics Data The flow for analyzing cell-level traffic statistics data is as below:

Figure 4-2 Flow for analyzing cell-level traffic statistics data

The flow for analyzing cell-level traffic statistics data proceeds as below:

l Check whether there are cells with unsatisfied indexes If no, the analysis ends.

l If there are cells with unsatisfied indexes, analyze the detailed causes, find major causes of indexes deterioration, and provide proper solutions.

l After carrying out solutions, analyze the new data of traffic statistics until indexes meet requirements.



4.3 Accessibility Indexes 4.3.1 Paging Traffic Statistics Indexes

When the CN pages UE, it sends RNC the PAGING message. After receiving the message, the RNC sends UE the PAGING TYPE 1 message or PAGING TYPE 2 message according to the state of UE.

If the paged UE is in idle, CELL_PCH, or URA_PCH state, the RNC sends PAGING TYPE 1 message on PCCH to UEs in the paged area.

If the paged UE is in CELL_FACH or CELL_DCH state, the RNC sends PAGING TYPE 2 message on DCCH to UEs in the paged area.

In addition, the UTRAN sends the PAGING TYPE 1 message to the UE in idle, CELL_PCH or URA_PCH state, which triggers the UE to modify system information. The UTRAN also sends the PAGING TYPE 1 message to the UE in CELL_PCH or URA_PCH state, which triggers state transition of UE to support data transmission.

When the UE in idle state receives the PAGING TYPE 1 message, it sends RNC the RRC CONNECTION REQUEST message. After the UE in CELL_PCH or URA_PCH state receives the PAGING TYPE 1 message, it sends RNC the CELL UPDATE message. The cause for cell update is paging response. For details, see 3GPP TS 25.331 and 25.413.

The indexes related to analyzing paging traffic statistics performance include:

l The UE in idle state loses paging l The UE in PCH state loses paging l Flow control l PCH congestion

The UE in Idle State Loses Paging As previously mentioned, if the paged UE is in idle state, the RNC sends the PAGING TYPE 1 message to the cells in paged area. Therefore, the index is based on RNC statistics.

Table 4-1 lists the counters related to paging loss for idle UE.

Table 4-1 Counters related to paging loss for idle UE

Counter name Counter description

VS.RANAP.Paging.Att.IdleUE It counts the times that the CN pages idle UEs

VS.RANAP.Paging.Succ.IdleUE It counts the times that the CN succeeds in paging idle UEs

VS.RANAP.Paging.Fail.IdleUE It counts the times that the CN fails to page idle UEs

Wherein, VS.RANAP.Paging.Fail.IdleUE is a calculated index, with the calculation as below:

VS.RANAP.Paging.Fail.IdleUE = VS.RANAP.Paging.Att.IdleUE - VS.RANAP.Paging.Succ.IdleUE

Table 4-6 shows the position for counting point by counter for paging loss by idle UE.



Figure 4-3 Position for counting point by counter for paging loss by idle UE

When the RNC receives the paging message from CN, and the paged UE is in idle state, the RNC takes statistics of VS.RANAP.Paging.Att.IdleUE at the point B upon sending PAGING TYPE 1 message to the cells in paged area.

When the RNC receives the RRC CONNECTION REJECT message from UE, the RNC takes statistics of VS.RANAP.Paging.Succ.IdleUE at the point C if the RRC connection setup request is due to one of the following causes:

l Terminating Conversational Call l Terminating Streaming Call l Terminating Interactive Call l Terminating Background Call l Terminating High Priority Signaling l Terminating Low Priority Signaling l Terminating cause unknown

The causes of paging loss by idle UE usually include:

l Parameter configuration problem. For this problem, check the paging-related parameters whether they are configured as the baseline parameters.

l Weak coverage. For example, the RNC cannot page a UE in indoor UE without being covered by signals, or a UE in blind elevator area.

The UE in PCH State Loses Paging As previously mentioned, if the paged UE is in CEPP_PCH or URA_PCH state, the RNC sends the PAGING TYPE 1 message to the cells in paged area so that the UE transits state to support data transmission. Therefore the index is based on RNC statistics.



Table 4-2 shows the counters related to paging loss for UE in PCH state.

Table 4-2 Counters related to paging loss for UE in PCH state


VS.UTRAN.Paging1.Att It counts the times that the RNC sends the PAGING TYPE 1 message.

VS.UTRAN.SuccPage1 It counts the times that the RNC succeed in sending the PAGING TYPE 1 message.

VS.RRC.Paging1.Fail.PchUE It counts the times that the RNC fails to send the PAGING TYPE 1 message.

Wherein, VS.RRC.Paging1.Fail.PchUE is a calculated index, with the calculation as below:

VS.RRC.Paging1.Fail.PchUE = VS.UTRAN.Paging1.Att - VS.UTRAN.SuccPage1

Figure 4-4 shows the Position for counting point by counter for paging loss by UE in PCH state.

Figure 4-4 Position for counting point by counter for paging loss by UE in PCH state

When the RNC sends the PAGING TYPE 1 message to the UE in CELL_PCH or URA_PCH state, it takes statistics of VS.UTRAN.Paging1.Att at the point A.

When the UE in CELL_PCH or URA_PCH state receives the PAGING TYPE 1 message, it sends RNC the CELL UPDATE message. The cause for cell update is paging response. When the RNC receives the cell update message from UE, with the cause paging response, it takes statistics of VS.UTRAN.SuccPage1 at the point B.

The RNC will not count the times of sending PAGING TYPE 1 message due to modification of system information.

The causes of paging loss by UE in PCH state include:

l Parameter configuration problem. For this problem, check the paging-related parameters whether they are configured as the baseline parameters.

l Weak coverage. For example, the RNC cannot page a UE in indoor UE without being covered by signals, or a UE in blind elevator area.



Flow Control When the lu interface is in flow control state, it drops the paging messages from CN.

Table 4-3 shows the counter related to paging loss due to flow control.

Table 4-3 Counter related to paging loss due to flow control


VS.CN.Page.Loss.IUFC It counts the times that IU interface drops the paging messages due to flow control

When the RNC receives the paging message from CN, and the IU interface is in paging flow control state, the IU interface drops the paging message and counts the time.

When paging messages are dropped due to flow control at IU interface, the traffic of network must be heavy. Therefore, precaution to network expansion must be performed.

PCH Congestion When the RNC receives paging message from CN, and the current paging flow exceeds the maximum capacity of PCH, PCH is congested and paging messages are dropped.

Table 4-4 lists the counters related to PCH congestion.

Table 4-4 Counters related to PCH congestion


VS.CN.Page.Loss.PCHCong It counts the times that paging messages are dropped due to PCH congestion (RNC level)

VS.RRC.Paging1.Loss.PCHCong.Cell It counts the times that paging message are dropped due to PCH congestion (cell level)

VS.CRNC.IUB.PCH.Bandwidth CRNC Iub PCH bandwidth

VS.MAC.CRNCIubBytesPCH.Tx IUB PCH transport channel flow

If paging messages are dropped in the cell due to PCH congestion, the paging traffic of the cell must have reached the maximum traffic. Check the parameters related to repeated paging and PCH. If this problem is due to heavy traffic volume, split the location area.

4.3.2 Low Success Rate of RRC Setup This section analyzes possible causes of low success rate of RRC setup. It also describes phenomena of problems about traffic statistics indexes and corresponding solutions.

In traffic statistics, the major causes of RRC connection setup failure include the following types:

l The RRC connection request is rejected due to lub interface failure l The RRC connection request is rejected due to network congestion



l The RRC connection fails due to no response l The RRC connection fails due to redirection

At the RNC side, the RRC connection setup failure includes two situations:

l After the RNC receives the RRC Connection Request message from UE, it sends UE the RRC Connection Reject message. This corresponds to the first two major causes listed previously. The counter starts counting at the point A shown in Figure 4-5.

Figure 4-5 Position for counting point by counter for RRC connection rejection

l After the RNC sends the RRC CONNECTION SETUP message, it fails to receive the RRC CONNECTION SETUP COMPLETE or RRC CONNECTION SETUP FAILED message from UE. This corresponds to the third cause listed previously.

RRC Connection Request Rejection due to lub Interface Failure The RRC connection request rejection is rejected due to lub interface failure, with the following detailed causes:

l RRC connection setup rejection due to RL setup failure l RRC connection setup rejection due to AAL2 setup failure

The corresponding traffic statistics counters

Table 4-5 lists the counters related to RRC connection request rejection due to lub interface failure.

Table 4-5 Counters related to RRC connection request rejection due to lub interface failure


VS.RRC.Rej.RL.Fail It counts the times that RRC connection setup is rejected due to RL setup failure

VS.RRC.Rej.AAL2.Fail It counts the times that RRC connection setup is rejected due to AAL2 synchronization failure

The indexes listed in Table 4-5 are cell-level indexes.

l RRC connection setup rejection due to RL setup failure



RL setup seldom fails. It might be due to: − Hardware problems of NodeB. For example, power amplifiers are overheated

(seldom). − Restricted number of CEs on NodeB. When the estimation of NodeB credits are too

incorrect to actually reflect the usage conditions of NodeB CEs, the RNC judges that the NodeB CEs are enough, so the RNC sends NodeB the RL setup message. Consequently, the NodeB responds RL setup failure due to restriction of CEs. When the RL setup failure leads to that RRC connection rejected times is unequal to 0, you must check the cell load to confirm that restriction on number of CEs is not present. Check whether there are equipment alarms. Confirm that there is no failure due to air-conditioner and power amplifier problems. For example, in a period, for an operator's network, the RRC connection is rejected hundreds of times due to this cause. According to the following analysis, there are overheating alarms on NodeB and the causes might be load or ambient temperature, such as air-conditioner failure. For these problems, contact NodeB maintenance employees; otherwise, the problems will greatly affect access and handover success rate.

l RRC connection setup rejection due to AAL2 setup failure AAL2 setup seldom fails. It fails when AAL2 resource is restricted or the cell becomes problematic.

RRC Connection Request Rejection due to Network Congestion Find the type of resource that causes RRC connection request rejection due to network congestion. The congestion of radio resources includes the following types:

l Failure in application for power resource l Failure in application for uplink CE resource l Failure in application for downlink CE resource l Failure in application for code resource l Others



Table 4-6 lists the counters related to RRC connection request rejection due to network congestion.

Table 4-6 Traffic statistics counters related to RRC connection request rejection due to network congestion


RRC.FailConnEstab.Cong It counts the times that RRC connection setup is rejected due to network congestion. It is the total rejection times.

VS.RRC.Rej.Power.Cong It counts the times that RRC connection setup is rejected due to failure in application for cell power resource.

VS.RRC.Rej.UL.CE.Cong It counts the times that RRC connection setup is rejected due to failure in application for uplink CE resource.

VS.RRC.Rej.DL.CE.Cong It counts the times that RRC connection setup is rejected due to failure in application for downlink CE resource.

VS.RRC.Rej.Code.Cong It counts the times that RRC connection setup is rejected due to failure in application for code resource.

The previous indexes are cell-level indexes.

l Failure in application for power resource When application for power resource fails, you must check whether the configuration of admission parameters is consistent with the default. If the parameters are properly configured, you need check the current network load by traffic counter and the counter for equivalent number of subscriber. If the network load and congestion rate actually meet the expansion requirements, start network expansion. For detailed expansion methods, see W-Network Expansion Guide.

l Failure in application for uplink/downlink CE resource When the NodeB CE resource is inadequate; you must check the configuration of NodeB CE resource based on the current actual traffic load. For the querying method, see W-Equipment Room Guide.

l Failure in application for code resource When the code resource is inadequate, you must provide rational expansion methods based on actual traffic load. For details, see W-Network Expansion Guide.

l Others There are few such cases, and they are usually product problems. Therefore, this part neglects it.



RRC Connection Failure due to No Response Table 4-7 lists the counter related to RRC connection failure due to no response.

Table 4-7 Counter related to RRC connection failure due to no response


RRC.FailConnEstab.NoReply It counts the times that RRC connection setup fails due to no response

The RRC.FailConnEstab.NoReply is a cell-level index.

The major causes of the problem include the following two types:

l The UE fails to receive the RRC CONNECTION SETUP message from RNC. The cause of the problem is irrational configuration of coverage, cell selection and cell reselection parameters. For details, see 3.3.3 .

l After the UE send the RRC CONNECTION SETUP COMPLETE message, but the RNC does not receive it. Maybe the initial transmit power of uplink DCH is over low. For solutions, see 3.3.3 .

RRC Connection Request Rejection due to Redirection After the UE sends the RRC connection setup request message, the redirection algorithm is triggered if the cell is congestion or assigning resources (mainly the admission and code resource assignment) fails, and the entire RRC direct retrial algorithms fail. If the serving cell of originating UE has inter-frequency neighbor cell or GSM cell, the UE is indicated by the IE Redirection info of RRC connection reject message to redirection to the frequency point of inter-frequency neighbor cell or GSM cell. If there is no inter-frequency neighbor cell or GSM cell, the IE Redirection info of RRC connection reject message is not configured.

Table 4-8 lists the counters related to RRC connection setup rejection due to redirection

Table 4-8 Counters related to RRC connection setup rejection due to redirection


VS.RRC.Rej.Redir.Inter.Att interfrequency cell

VS.RRC.Reject.Redir.Intrat interfRAT cell info

These two indexes are cell-level indexes.

4.3.3 Low Success Rate of CS RAB Setup The causes of CS RAB assignment setup failure in traffic statistics include:

l Radio network problems l Transmission network problems l Other problems



When CS RAB assignment fails, the counter starts counting at the point B shown in Figure 4-6.

Figure 4-6 Position for counting point by counter for CS RAB assignment failure in RNC traffic statistics starting counting

At the point B in Figure 4-6, when the RNC sends CN the RAB ASSIGNMENT RESPONSE message with the cause failure, the corresponding counter starts working according to specific failure causes. The RB SETUP process is marked in broken line and is optional.

Radio Network Problems RAB assignment setup fails due to radio network problems with the following detailed types:

l CS RAB assignment setup failure due to relocation l CS RAB assignment setup failure due to air interface failure l CS RAB assignment setup failure due to insufficient capability l CS RAB assignment setup failure due to other problems of radio networks

Table 4-9 shows the traffic statistics counters related to CS RAB assignment setup failure due to radio network problems.

Table 4-9 Traffic statistics counters related to CS RAB assignment setup failure due to radio network problems


VS.RAB.FailEstabCS.RNL It counts the times that CS RAB assignment setup fails due to radio network problems. It counts the total failure times.

VS.RAB.FailEstCS.Relo It counts the times that CS RAB assignment setup fails due to relocation.

VS.RAB.FailEstCS.RIPFail It counts the times that CS RAB assignment setup fails due to air interface failure.



VS.RAB.FailEstCS.Unsp It counts the times that CS RAB assignment setup fails due to insufficient capability.

The indexes listed in Table 4-9 are cell-level indexes. For detailed VS.RAB.FailEstCS.Unsp, see Table 4-10.

l CS RAB assignment setup fails due to relocation When the RNC carries out relocation, it receives the RAB ASSISNMENT REQUEST message, and then it will not respond to the message but respond the RAB ASSISNMENT RESPONSE message directly to CN (due to Relocation Triggered). This index is seldom present, so neglect it.

l CS RAB assignment setup fails due to air interface failure After the RNC receives the RB Setup Failure message from UE, it sends the RAB Assignment Response message to CN due to Failure in the Radio Interface Procedure. To analyze CS RAB assignment setup fails due to air interface failure, you must analyze the causes of RB setup failure. For details, see RB setup failure in 4.3.5 .

l CS RAB assignment setup fails due to insufficient capability The detailed causes of CS RAB assignment setup failure due to insufficient capability include: − Requested Traffic Class not Available (18) − Requested Maximum Bit Rate not Available (20) − Requested Maximum Bit Rate for DL not Available (33) − Requested Maximum Bit Rate for UL not Available (34) − Requested Guaranteed Bit Rate not Available (21) − Requested Guaranteed Bit Rate for DL not Available (35) − Requested Guaranteed Bit Rate for UL not Available (36) − Requested Transfer Delay not Achievable (22) CS RAB assignment setup fails due to insufficient capability when the cell is congested, such as Requested Maximum Bit Rate not Available. Note that the causes of the indexes include the following causes of failure due to radio resource congestion: − CS RAB is rejected due to inadequate power − CS RAB is rejected due to uplink CE resource − CS RAB is rejected due to downlink CE resource − CS RAB is rejected due to code resource − CS RAB is rejected due to inadequate IUB bandwidth − Others

Table 4-10 lists the traffic statistics counters related to CS RAB assignment setup failure due to insufficient capability.

Table 4-10 Traffic statistics counters related to CS RAB assignment setup failure due to insufficient capability


VS.RAB.FailEstCs.Power.Cong It counts the times that CS RAB assignment fails due to power resource congestion



VS.RAB.FailEstCs.ULCE.Cong It counts the times that CS RAB assignment fails due to uplink CE congestion

VS.RAB.FailEstCs.DLCE.Cong It counts the times that CS RAB assignment fails due to downlink CE congestion

VS.RAB.FailEstCs.Code.Cong It counts the times that CS RAB assignment fails due to code resource congestion

VS.RAB.FailEstCs.IUB.Band It counts the times that CS RAB assignment fails due to inadequate IUB bandwidth


By querying related indexes, determine the type of resource that causes failure and perform corresponding expansion solutions.

l CS RAB assignment setup fails due to other problems of radio networks Other causes may lead to CS RAB assignment setup failure, such as no response to RB setup. For RB setup failure, see 4.3.5 . CS RAB assignment setup fails due to other problems of radio networks, and obtaining the causes directly from traffic statistics is difficult. You might locate problems by DT or other tests.

Transmission Network Problems The detailed causes of CS bearer setup failure which causes RAB assignment setup failure include:

l Signaling Transport Resource Failure(65) l Iu Transport Connection Failed to Establish(66)

Table 4-11 lists the counter related to CS RAB assignment setup failure due to transmission network problems.

Table 4-11 Counter related to CS RAB assignment setup failure due to transmission network problems


VS.RAB.FailEstabCS.TNL It counts the times that CS RAB assignment setup fails due to transmission network problems

The VS.RAB.FailEstabCS.TNL is a cell-level index.

If VS.RAB.FailEstabCS.TNL is present, there are probably transmission problems. You must check whether the transmission at lu interface is normal.

Other Causes The index seldom occurs, so this document neglects it.



4.3.4 Lower Success Rate of PS RAB Setup The causes of PS RAB assignment setup failure in traffic statistics include:

l Radio network problems l Transmission network problems l No resource available l Other problems

Figure 4-7 shows the counter for PS RAB assignment failure starting counting in RNC traffic statistics.

Figure 4-7 Position for counting point by counter for PS RAB assignment failure in RNC traffic statistics

At the point B in Figure 4-7, when the RNC sends CN the RAB ASSIGNMENT RESPONSE message with the cause failure, the corresponding counter starts working according to specific failure causes. The RB SETUP process is marked in broken line and is optional.

Radio Network Problems RAB assignment setup fails due to radio network problems with the following detailed types:

l PS RAB assignment setup failure due to parameter errors l PS RAB assignment setup failure due to relocation l PS RAB assignment setup failure due to air interface failure l PS RAB assignment setup failure due to insufficient capability l PS RAB assignment setup failure due to other problems of radio networks

Table 4-12 shows the traffic statistics counters related to PS RAB assignment setup failure due to radio network problems.



Table 4-12 Traffic statistics counters related to PS RAB assignment setup failure due to radio network problems.


VS.RAB.FailEstPS.Par It counts the times that PS RAB assignment setup fails due to parameter errors. It counts the total failure times.

VS.RAB.FailEstPS.Relo It counts the times that PS RAB assignment setup fails due to relocation.

VS.RAB.FailEstPS.RIPFail It counts the times that PS RAB assignment setup fails due to air interface failure.

VS.RAB.FailEstPS.Unsp It counts the times that PS RAB assignment setup fails due to insufficient capability.

The indexes listed in Table 4-12are cell-level indexes. For detailed VS.RAB.FailEstPS.Unsp, see Table 4-14.

l PS RAB assignment setup fails due to parameter errors The detailed causes include: − Invalid RAB Parameters Value − Invalid RAB Parameters Combination − Condition Violation for SDU Parameters − Condition Violation for Traffic Handling Priority − Condition Violation for Guaranteed Bit Rate.

The index is seldom present, so this part neglects it.

l PS RAB assignment setup fails due to relocation When the RNC carries out relocation, it receives the RAB ASSISNMENT REQUEST message, and then it will not respond to the message but respond the RAB ASSISNMENT RESPONSE message directly to CN (due to Relocation Triggered). This index is seldom present, so neglect it.

l PS RAB assignment setup fails due to air interface failure After the RNC receives the RB Setup Failure message from UE, it sends the RAB Assignment Response message to CN due to Failure in the Radio Interface Procedure. To analyze PS RAB assignment setup fails due to air interface failure, you must analyze the causes of RB setup failure. For details, see RB setup failure in 4.3.5 .

l PS RAB assignment setup fails due to insufficient capability The detailed causes of PS RAB assignment setup failure due to insufficient capability include:

l Requested Traffic Class not Available (18) l Requested Maximum Bit Rate not Available (20) l Requested Maximum Bit Rate for DL not Available (33) l Requested Maximum Bit Rate for UL not Available (34) l Requested Guaranteed Bit Rate not Available (21) l Requested Guaranteed Bit Rate for DL not Available (35)



l Requested Guaranteed Bit Rate for UL not Available (36) l Requested Transfer Delay not Achievable (22)

The index is present when the cell is congested. For detailed causes, such as Requested Maximum Bit Rate not Available, see CDL. Note that the causes of the indexes include the following causes of failure due to radio resource congestion:

l PS RAB is rejected due to inadequate power l PS RAB is rejected due to uplink CE resource l PS RAB is rejected due to downlink CE resource l PS RAB is rejected due to code resource l Others

Table 4-13 lists the traffic statistics counters related to PS RAB assignment setup failure due to insufficient capability.

Table 4-13 Traffic statistics counters related to PS RAB assignment setup failure due to insufficient capability


VS.RAB.FailEstPs.Power.Cong It counts the times that PS RAB assignment fails due to power resource congestion

VS.RAB.FailEstPs.ULCE.Cong It counts the times that PS RAB assignment fails due to uplink CE congestion

VS.RAB.FailEstPs.DLCE.Cong It counts the times that PS RAB assignment fails due to downlink CE congestion

VS.RAB.FailEstPs.Code.Cong It counts the times that PS RAB assignment fails due to code resource congestion

VS.RAB.FailEstPs.IUB.Band It counts the times that PS RAB assignment fails due to inadequate IUB bandwidth


By querying related indexes, determine the type of resource that causes failure and carry out corresponding expansion solutions.

l PS RAB assignment setup fails due to other problems of radio networks Other causes may lead to PS RAB assignment setup failure, such as no response to RB setup. For RB setup failure, see 4.3.5 . PS RAB assignment setup fails due to other problems of radio networks, and obtaining the causes directly from traffic statistics is difficult. You might locate problems by DT or other tests.

Transmission Network Problems The detailed causes of PS bearer setup failure which causes RAB assignment setup failure include:

l Signaling Transport Resource Failure(65) l Iu Transport Connection Failed to Establish(66)



Table 4-14 lists the counter related to PS RAB assignment setup failure due to transmission network problems.

Table 4-14 Counter related to PS RAB assignment setup failure due to transmission network problems


VS.RAB.FailEstabPS.TNL It counts the times that PS RAB assignment setup fails due to transmission network problems

The VS.RAB.FailEstabPS.TNL is a cell-level index.

If VS.RAB.FailEstabPS.TNL is present, there are probably transmission problems. You must check whether the transmission at lu interface is normal.

No Resources Available No resource available causes PS RAB setup failure



Table 4-15 shows the counter related to PS RAB setup failure due to no resource available.

Table 4-15 Counter related to PS RAB setup failure due to no resource available


VS.RAB.FlEstPS.Str.NResAvail It counts the times that PS RAB setup fails due to no resource available

VS.RAB.FlEstPS.Str.NResAvail is a cell-level index. The resource referred in Table 4-15 includes the equipment resources excluding radio layer resources (such as power resource, code resource, and CE resource). VS.RAB.FlEstPS.Str.NResAvail is seldom present, so this document neglects it.

Other Causes The index seldom occurs, so this document neglects it.

For HSDPA service, the cause of low success rate of RAB assignment is the same as that of R99 PS RAB assignment. The traffic statistics indexes of PS RAB involve R99 PS service and HSDPA service.

HSDPA RAB Setup Success Ratio

This KPI can be used to evaluate the RAB setup success ratio of the PS service carried by HSDPA.

KPI Name HSDPA RAB Setup Success Ratio

Measurement Scope

Cell

Formula %100

____ ×=

temptRABSetupAtHSDPAccessRABSetupSuHSDPASRRABHSDPA

Associated Counters

VS.HSDPA.RAB.SuccEstab; VS.HSDPA.RAB.AttEstab

Notes The RNC level KPI is calculated by aggregating all the cell counters.

HSUPA RAB Setup Success Ratio

This KPI can be used to evaluate the RAB setup success ratio of the HSUPA service.



KPI Name HSUPA RAB Setup Success Ratio

Measurement Scope

Cell

Formula %100

____ ×=

temptRABSetupAtHSUPAccessRABSetupSuHSUPASRRABHSUPA

Associated Counters

VS.HSUPA.RAB.SuccEstab; VS.HSUPA.RAB.AttEstab

Notes The RNC level KPI is calculated by aggregating all the cell counters.

4.3.5 Low Success Rate of RB Setup RB setup failure does not serve as one cause of RAB assignment failure in current version, so no special counter is used for RB setup failure. In traffic statistics of current version, CS RB setup failure and PS RB setup failure are not distinguished, so matching the traffic statistics indexes of RB setup failure and the specific causes of RAB setup failure one by one is temporarily impossible.

The major causes of lower success rate of RB setup include the following two types:

l RB setup failure l No response to RB setup

RB Setup failure RB setup failure: after the RNC sends the RB Setup message, it receives the RB Setup Failure message from UE.

The detailed causes of RB setup failure include:

l Unsupported configuration l Physical channel failure l Cell update occurrence l Invalid configuration



In traffic statistics of RNC, the counter for RB setup failure starts counting at the point A shown in Figure 4-8.

Figure 4-8 Position for counting point by counter for RB setup failure in traffic statistics

At the point A shown in Figure 4-8, when the RNC receives the RADIO BEARER SETUP FAILURE message from UE, it takes statistics according to various causes of RB setup failure in the cell where UE camps.

Table 4-16 lists the traffic statistics counters related to RB setup failure.

Table 4-16 Traffic statistics counters related to RB setup failure


VS.FailRBSetup.CfgUnsup RB setup fails due to unsupported cell configuration

VS.FailRBSetup.PhyChFail RB setup fails due to cell physical channel failure

VS.FailRBSetup.CellUpd RB setup fails due to cell update

VS.FailRBSetup.IncCfg RB setup fails due to invalid cell configuration


l Unsupported configuration This is due to maloperations by subscribers. For example, when using downlink 128K data service, a subscriber receives the RB setup request (originating or terminating VP) of VP service, the UE directly responds RB setup failure due to unsupported configuration, namely, most UEs fails to support using VP and high speed (>= 64K) PS service simultaneously.

l Physical channel failure It seldom occurs.

l Cell update occurrence Cell update occurs during RB setup. It seldom occurs, so this document neglects it.

l Invalid configuration This is a common causes of RB setup failure. It is possible that: the 3G UE originates VP service to an terminating MS that camps on GSM cells and that does not support VP service, so after the RNC receives the RAB assignment request, the CN immediately



sends the Disconnect command with the cause Bearer capability not authorized after call proceeding. Consequently, the UE receives the RB_SETUP message and has not completed RB setup, so it responds RB setup failure upon receiving the Disconnect message, and then the RNC responds RAB setup failure.

No response to RB Setup Table 4-17 lists the traffic statistics counter related to no response to RB setup.

Table 4-17 Traffic statistics counter related to no response to RB setup


VS.FailRBSetup.NoReply RB setup fails due to no response to cell RB setup

The previous index is a cell-level index.

This is a common cause of RB setup failure. The RB setup fails because that the UE fails to receive RB SETUP message or the RNC fails to receive response from UE. This occurs in weak coverage areas due to two causes:

l The UE does not originates a call in the best server l The coverage is weak

For locating and solving no response to RB setup, see 3.3.7 .

4.3.6 Low success rate of MBMS service setup After receiving the Session Start message from SGSN, RNC setup IU interface signaling

bearer and service bearer, then according to the SA carried in Session Start, setup the RB bearer for MBMS service in corresponding cell of SA.

Traffic statistic related to MBMS service: measurement of MBMS service setup time at IU interface and measurement of face-to cell MBMS service.

Table 4-18 Measurement of MBMS service setup time at IU interface

Index Description of Index

VS.IU.MBMS.Start MBMS service setup times at IU interface

VS.IU.MBMS.Succ MBMS service setup success times at IU interface

VS.IU.MBMS.Fail MBMS service setup failure times at IU interface

VS.IU.MBMS.Fail.NoRsrc MBMS service setup failure times at IU interface(without available resource)

VS.IU.MBMS.Fail.NNSF MBMS service setup failure times at IU interface(NNSF)

VS.IU.MBMS.Fail.IuUpFail MBMS service setup failure times at IU interface(User plane failure at IU interface)

VS.IU.MBMS.Fail.IuSigFail MBMS service setup failure times at IU interface(signaling connection failure at IU interface)



Table 4-19 Measurement of face-to cell MBMS service.

Index Description of Index

VS.MBMS.MTCHSetupSucc.Cell MBMS service setup success times in cell

VS.MBMS.MTCHSetupFail.Cell MBMS service setup failure times in cell Current RNC support broadcast model only, and there’s no alternation between UE and UTRAN in broadcast model, so MBMS related traffic statistic can only obtained according to MBMS service or cell statistic.

If MBMS service setup success rate at IU interface is low, the causes include:

1. No available resource in RNC

2. NAS Node Selection Function, for details, refer to 3GPP 23.236 4.4.

3. User plane failure at IU interface

4. Signaling connection failure at IU interface

If face-to cell MBMS service setup success rate is low, the causes include:

1. Power, code, transmission, CE admission failure;

2. Common channel problem.

4.4 System Availability Index 4.4.1 High Admission Rejection Rate

To be supplemented.

4.4.2 High Paging Congestion Rate To be supplemented.

4.4.3 High Rate of Congested Cell To be supplemented.



5 Solving Access Problems

5.1 Paging Problems 5.1.1 Improper Power Configuration of Paging-related Channels

Two channels are related to paging: PICH and PCH. When the power of these two channels is too low to meet the requirements for UE demodulation, the UE fails to receive paging messages correctly. By default, the power of PCH is –2 dB and that of PICH is –7 dB. According to the result of parameter optimization, the power configuration guarantees the paging request that Ec/Io is larger than –12 dB. If the network coverage is even worse than –12 dB, consider raising PCH power. If the paging indexes are bad, without DT data of UE and single subscriber tracing data of RNC, you need analyze the distribution chart of network coverage conditions and check whether raising the power allocation ratio of these two channels is necessary.

5.1.2 Paging Failure due to UE Location Area Update

Description and Analysis Figure 5-1 shows the originating signaling flow of paging failure due to UE location area update.

Figure 5-1 Originating signaling flow of paging failure due to UE location area update



According to Figure 5-1, the RNC receives the Disconnect message from CN.

Figure 5-2 shows the content of the Disconnect message.

Figure 5-2 Content of the Disconnect message in paging failure due to UE location area update

According to Figure 5-2, the cause value for the Disconnect message is no route to destination. Therefore, the connection is released because the destination UE cannot be paged.

Figure 5-3 shows the terminating signaling flow of paging failure due to UE location area update.

Figure 5-3 Terminating signaling flow of paging failure due to UE location area update

According to Figure 5-3, the terminating UE has location area and route areas updated. During the process, the UTRAN fails to page UE, so the call fails.



Solution No general solution is for this problem. You can rationally configure the location area and route area to avoid frequent location area update in hot spot areas.

5.1.3 Paging Failure due Implicit Detach of UE The UE has location area updated in a period of usually 2 hours. The CN has a timer, with a longer period than the timer for location area update. If the CN does not receive location area update message of the UE in the preset time by the timer, the CN originates implicit detach and sets the permitted call flag of this UE to be false; therefore, paging the UE fails. This is due to the following causes:

The UE stays in the blind area permanently. The network is usually full coverage by GSM network, so the UE will reselect a GSM cell if coverage by UMTS network is unavailable in some area. This seldom occurs. The causes also include mal-operations, such as directly removing UE battery or USIM card.



5.2 Cell Selection and Reselection Problem 5.2.1 Repeating to Send the RRC Connection Request Message due to Cell Reselection

Description and Analysis Figure 5-4 shows the signaling of UE when cell reselection causes repeating to send RRC Connection Request message.

Figure 5-4 Signaling of UE

The interval between two times of repeating to send request by UE is about 1.2s.



Figure 5-5 Signal quality when the UE sends the RRC connection request message.

Figure 5-5 Signal quality when the UE sends the RRC connection request message.



Figure 5-6 shows the Signal quality when the UE resends the RRC connection request.

Figure 5-6 Signal quality when the UE repeats to send the RRC connection request

According to default system parameter configuration,

l Treselection = 1 l Qhyst2 = 2 dB l Qoffset2 = 0 dB l Sintrasearch = 5

When the signals of target cell are stronger than the serving cell, completing reselection takes 1s. Therefore, the signal fluctuation of target cell and serving cell is similar to previous description. There is little space to optimize the parameters of cell reselection. The minimum Treselection is 1. If Treselection is set to 0, the reselection time will be 8*DRX, much longer than 1s, because the minimum DRX is set to 0.64s. If Treselection is set to 0, the Ec/Io of target cell must be 3 dB higher than that of serving cell according to protocols. After multiple statistics, the time for cell reselection is between 1.2s and 1.4s.

Solution To reduce the time for cell reselection as possible, modify Qhyst2 to 0, SintraSearch to 7. During walking test, ping-pong cell reselection occurs without decrement of reselection time. It is recommended that:

l Qhyst2 remains 2 dB



l SintraSearch is set to enable UE to start intra-frequency measurement early. If the modification does not have great impact on UE power consumption, SintraSearch is set to 7.

5.3 RRC Setup Problems 5.3.1 Improper Configuration of Parameters of Uplink Access Channel

Description and Analysis Figure 5-7 shows the signaling of UE in a connection process.

Figure 5-7 Signaling of UE in a connection process

Figure 5-8 shows the single subscriber tracing signaling on RNC

Figure 5-8 Single subscriber tracing signaling on RNC

After the table shown in Figure 5-9 is sorted by time order, you can see that the RNC responds to the second RRC setup connection message from UE.



Figure 5-9 shows the quality of downlink signals.

Figure 5-9 Quality of downlink signals

According to Figure 5-9, the downlink signals are strong, so the uplink signals should be strong. Why does the first connection fail?

After static test, the problem reoccurs. The problem occurs every half hour. Sometimes, call fails because repeating to send RRC connection request fails four times. According to analysis of signaling for tracing TMSI by RNC, the RNC fails to receive the RRC Connection Request message. The signal strength of the cell: RSCP ranges from –60 dBm to –70 dBm; Ec/No ranges from –2 dB to –4 dB. According to previous interference analysis, regular interference is present in the cell, as shown in Figure 5-10.

Figure 5-10 Regular interference in cell 248



Figure 5-11 shows the part of magnified chart of interference.

Figure 5-11 Part of magnified chart of interference

Interference lasts for 40s each time. The last peak shown in Figure 5-10 is not the periodic interference as previous ones. It lasts for a short time (a sampling point). The interference is present from 8:00 to 21:00. There is no interference in other time.

At first, engineers guess that the interference causes the problem. After sampling data, based on RNC messages, UE messages, and recorded RTWP, there is no interference one minute before and after call fails. Therefore the problem is irrelevant to interference.

The following tests are to locate the causes of problems:

l Test with Qualcomm handset (6200). During one-hour call, no similar phenomenon is present, but the interference is still present. This proves that Qualcomm test handset is normal.

l To check that the problem is not due to AICH, raise the AICH power to 0 dB. Test with Moto handset and the problem is still present. Namely, the problem is irrelevant to AICH power.

l Restore the AICH power to –7 dB, restore the retransmission times of preamble from 8 to 20. During the test more than one hour, the problem is not present.

l Signals are stable and strong during indoor static test: Ec/Io is about –3 dB and RSCP is about –50 dBm. So engineers doubt that the power of Moto handset is problematic in areas with strong signals. After engineers lower the Ec/Io to –7 dB by increasing downlink load, the RRC setup problem remains.

l To further confirm that the problem is not caused by interference, test after 22:00. According to the RTWP, there is no interference, but repeating to send request message occurs fours times in the test longer than one hour, with two times of Call Fail. According to comparative analysis of interference record by NodeB and system information by UE, the interference value is changed. During repeating to send request message, the interference before and after system information remain the same (–105



dB), which proves that the repeating to send request problem of Moto handset is irrelevant to external interference.

According to previous test, a conclusion is drawn that the problem is irrelevant to uplink interference and power configuration of AICH. Since the Qualcomm handset (6200) is normal in the test, the problem must be with uplink RACH of Moto handset.

Solution After engineers change the retransmission times of preamble from 8 to 20, the problem never occurs again.

5.3.2 Improper Configuration of AICH Power The power allocation of AICH directly affects the demodulation of AI by UE. If the power is over low, the UE cannot demodulate AI correctly; therefore connection to network fails. In earlier times, the AICH power is set to –12 dB, so the RRC setup problems usually occur. Now the default AICH power is –6 dB and it is enough to meet the demodulation by Moto, Qualcomm, and NEC handsets when Ec/Io is –12 dB. Different UEs varies in demodulation capability. If a UE has not performed for IOT test, focus on the power allocation of AICH if PRACH problems are with it.

5.3.3 Improper Configuration of FACH Power

Description and Analysis Figure 5-12 shows the signaling upon improper configuration of FACH power.

Figure 5-12 Signaling upon improper configuration of FACH power



Figure 5-13 shows the signal strength upon the first sending of RRC connection request.

Figure 5-13 Signal strength upon the first sending of RRC connection request

In Figure 5-13,

l The second column is the signal strength of serving cell l The third column is the scramble of the serving cell l The fourth and fifth column is the signal strength and scramble of the best monitored

cell. l The signals of these two cells keep fluctuating.

Figure 5-14 shows the single subscriber tracing signaling by RNC

Figure 5-14 Single subscriber tracing signaling by RNC

Because the downlink coverage is weak, so the UE originates the RRC connection request message. Consequently, the RNC receives the RRC connection request message and sends the



RRC connection setup message. However, the downlink signals are weak, so the UE fails to receive the RRC connection setup message.

Figure 5-15 shows the signaling and signal strength upon the second sending of RRC connection request after 2s.

Figure 5-15 Signaling and signal strength upon the second sending of RRC connection request

When the UE sends the RRC connection request message the second time, the downlink signal strength is about –13, so the connection succeeds. According to the Figure 5-15, when the Ec/Io of downlink signals is lower than –12 dB, it is not guaranteed that the UE can correctly demodulate data from downlink FACH.

The current FACH power is –1 dB, which is provided based on the relationship curve of FACH Ec/No and power allocation rate tested on field on the assumption that Ec/Io at cell edge is –12 dB. To raise the receiving success rate when Ec/Io power is –14 dB, raising the FACH power by 2 dB is recommended out of the consideration for the threshold for starting inter-RAT measurement.

Solution After the FACH power is set to 1 dB, the problem no longer exists that RRC connection fails because the UE cannot receive RRC Setup message in downlink.



5.3.4 Multiple Times of RRC Connection Request (for Service) and No RAB Assignment Request

There are no alarms at RNC and NodeB side. According to test, originated out from the cell is unavailable, but (soft handover) SHO is normal.

Figure 5-16 shows the traced signaling at UE side and RNC side.

Figure 5-16 Traced signaling at UE side

Figure 5-17 shows the traced signaling at RNC side. According to UE side, after the UE sends the initial direct transfer message, it does not receive any message. Therefore, it repeats to resend the RRC connection request message after 5s.

Figure 5-17 Traced signaling at RNC side

According to UU interface of RNC, after the RNC receives the initial direct transfer message, it sends the authentication request message (probably there is no authentication, so the RNC directly sends the Security mode command). But there is no response, so the RNC release RRC connection after expiration.



Figure 5-18 shows the BLER statistics at UE side.

Figure 5-18 BLER statistics at UE side

By comparison of messages at UE side and RNC side, the UE fails to receive the measurement control and authentication request message (sometimes Security mode command). According to the BLER statistics at UE side, after the UE sends the initial direct transfer message, the BLER with 32 as the Trch ID is 100%. Therefore decoding signaling RB on downlink transport channel is all wrong, so the UE fails to receive any message from downlink DCH. The RRC setup message is sent on CCH, so the UE can receive it.

From previous analysis, the downlink DCH might be problematic.



Figure 5-19 shows the BLER and RRC message.

Figure 5-19 BLER and RRC message at UE side



According to Figure 5-19, when the cell of PSC 205 is listed in active set and multiple braches of SHO are combined, the BLER increases but call drop does not occur. When signals of other cell are weak, call drops easily, as shown in Figure 5-20.

Figure 5-20 BLER and RRC message at UE side

The signals from the cell of SC 205 are strong, but the downlink BLER is 100%, so the call drops. Therefore, the cell of SC 205 is problematic in downlink.

Meanwhile, another cell under the same NodeB is normal. Therefore engineers doubt that a DSP of downlink NDLP board on NodeB is problematic. After connect a normal cell to the DSP, the problem is still present. Therefore, the DSP must be problematic. After NDLP reset, the DSP becomes normal. The DSP is fixed not after activation and deactivation, but after reset.

5.3.5 RRC Connection of HSDPA Subscribers Rejected due to Inadequate Code Resource

Description and Analysis In the test of maximum throughput rate of HSDPA cells, 15 codes (SF = 16) are statically assigned to HS-PDSCH. The HS-SCCH configures 4 codes (SF = 128). The RRC connection rejection for first HSDPA subscriber to access the network fails.

The cause of RRC connection rejection is congestion, namely, code resource congestion, power resource congestion, and CE resource congestion. The first UE connects to the network without other subscribers, so the cause of RRC connection rejection cannot be power and CE restriction.

After tracing performance of cells under RNC and tracing assignment of code tree, engineers find:



l CCH uses a code word (SF = 32) (PCPICH SF=256, PCCPCH SF=256, AICH SF=256, PICH SF=256, and SCCPCH SF=64)

l Four HS-SCCHs use a code word (SF = 32) l 15 HS-PDSCHs use 30 codes (SF=32)

When an HSPDA subscriber accesses the network, a code word (SF = 128) is necessary for 13.6K signaling. However, no code word is available now, so the RRC connection is rejected.

Figure 5-21 shows the assignment of HSDPA code tree.

Figure 5-21 Assignment of HSDPA code tree

According to the assignment of HSDPA code tree in Figure 5-21, the number of codes assigned for HSDPA subscribers is clear, as well as the rest codes and the occupation by R99 subscribers. Figure 5-21 shows a sample.

Besides tracing code tree, engineers can obtain the cause of admission failure from RNC logs based on the time for admission rejection, and IMSI.



Figure 5-22 shows RNC log for HSDPA admission rejection.

Figure 5-22 RNC log for HSDPA admission rejection

Solution After engineers assign 14 codes for HS-PDSCH, the HSDPA subscriber succeeds in access the network.

When codes are statically assigned to HSDPA subscribers, the admission is usually rejected due to code word restriction. The PS 384Kbps R99 subscribers and other R99 subscribers in the cell use most codes, so the admission of HSDPA subscribers in downlink is rejected because the DCH obtains no code word when HSDPA subscribers connect to the network.

5.4 RAB and RB Setup Problems 5.4.1 RAB Setup Failure due to Inadequate Resource

Description and Analysis A UE originates a call in a cell with strong signals, but fails.



Figure 5-23 shows the signaling of Disconnect after completion of RB setup.

Figure 5-23 Signaling of Disconnect after completion of RB setup

According to Figure 5-23, the UE receives the Disconnect message after completion of RB setup. The CN releases the connection, so the connection fails. The cause value of Disconnect is requested circuit channel not available.

The terminating UE is in the equipment room of RNC. There is indoor coverage system in the equipment room, so the coverage is good. But excessive subscribers are using the network, so the network is congested and the connection fails.

Solution Solve access failure problems due to inadequate capacity by network expansion.

This failure occurs under a special background, because excessive subscribers use the network in the equipment room. Therefore, the test becomes problematic. To guarantee normal test, engineers must restrict the number of subscribers using the network in equipment room. This problem must be noticed during optimization.

5.4.2 Handover Failure before Completion of Signaling Flow

Description and Analysis The UE might hand over from RRC setup completion to RAB assignment or after RB setup completion. If handover fails during this period, the subscriber might feel that connection to the network fails.



Figure 5-24 shows the signaling of UE upon a connection failure according to Analyzer software.

Figure 5-24 Signaling of UE upon a connection failure

Figure 5-25 shows the single subscriber tracing signaling by RNC.




Figure 5-26 shows the signal strength before release of connection.

Figure 5-26 Signal strength before release of connection

According to RNC signaling, the signals from the cell of SC 121 attenuate sharply. The cell of SC 56 needs adding to the active set, the UE cannot receive the ActiveSet Update message from RNC.

Solution To solve the problem, adjust the SHO parameters to enable the target cell to be added to the active set earlier as possible. For details, see guidebooks related to call drop analysis.

5.4.3 Admission Failure due to HSDPA Total Bit Rate Threshold Exceeded by HSDPA Bit Rate of Cell

Description and Analysis After the RNC enables the admission switch of HSDPA subscribers, it sets the number of admission subscribers to 16. The maximum rate upon registration and for RAB assignment is 2048 kpbs. The CELLCAC command involves two parameters as below:

l Average HSDPA throughput per HS-PDSCH code It is 200 kpbs by default.

l Multiplier factor HS-PDSCH transport channel It is 10.

Configure 13 codes to HS-PDSCH when multiple subscribers connect to the network. When the fifteenth HSDPA subscriber accesses the network, the RNC admission is rejected. The first 14 subscribers is connecting to the network and downloading data. After engineers change average HSDPA throughput per HS-PDSCH code to 300 kpbs, more than 16 subscribers can access the network.

The following information is from analysis of tracing log of RNC:

l BM_CraCacHsDschMaxReqRateAdm: DL Hsdpa Admission Fail! ulPreHsDschMaxReqRate=30720000 ulHsDschMaxReqRateThd=26000000



l NBM_CraCacHsDschMaxReqRateAdm: DL Hsdpa Admission Fail! CellHsDschMaxReqRate=28672000 HsPdschNum=13 RatioTotalRate=10 usKave=200

l NBM_CraCacHsdpaAdm: Hsdpa Admission Failure Because Hsdpa Max Req Rate over threshold

l NBM_CraProcPreCac: Cell ulUCId= 656374 Reject RncapInst= 44224 Request Because Hsdpa Adimisson Failed .

l NBM_CraPreAdmUserRsrc: UCId 656374 Alloc Power Resource Failure. l NBM_CraExecDchUserReqFlow: UCId 656374 RncapInst 44224 Alloc Cell Resource

Failure. l NBM_CraSendCellRrFailRsp: SF128 mapping: 4294967295 4294967295 4294967295

4278321151. l File Name: D:\boardproject\V16C01B061\epu/app/src/rr/rncap/rab/RncapRabSetup.c l Line No: 1709 l SRC WARNING->Err In PS RAB Setup: RB Setup Fail. Cause = 168658899 l ulErrorID is 184944608 l CORRM_FrcRabSetupRslt: RAB setup result is failure, error code = 168658899

Obviously, the admission for the 15th subscriber is rejected because the HSPDA bit rate after the access of 15th subscriber exceeded the HSPDA total bit rate, so the admission fails. The analysis is as below:

Configure 13 codes to HS-PDSCH. The rate of each code is 200 kpbs. The multiplier factor of HS-PDSCH transport channel is 10. Therefore, the maximum requested rate of a cell is 13*200Kbps*10=26000000bps. However, during test, after the 14th subscriber accesses the network, the HSDPA admission is accepted. Therefore, CellHsDschMaxReqRate=14*2048Kbps = 28672000bps, which exceeds the threshold. Therefore, HSDPA admission of fifth subscriber fails.

Solution After engineers change the average HSDPA throughput per HS-PDSCH code to 300 kbps, 16 subscribers can access the network. The problem is solved.

5.5 Authentication Problems To be supplemented.



5.6 Security Mode Problems

Description and Analysis Figure 5-27 shows the rejection messages in security mode during tracing single subscriber.

Figure 5-27 Rejection messages in security mode

Figure 5-28 shows the content of the RANAP_SECURITY_MODE_REJECT message at 15:33:28(28).

Figure 5-28 Content of the RANAP_SECURITY_MODE_REJECT message

According to Figure 5-28, the cause of security mode rejection is conflict with already existing integrity protection and or ciphering information. This cause means that the latest integrity protection or ciphering information is inconsistent with the configuration.



Figure 5-29 shows the ciphering mode information configured in previous security mode command.

Figure 5-29 ciphering mode information configured in previous security mode command

According to Figure 5-29, the encryption algorithm configured in the security mode command is no encryption, namely, no encryption is conducted on the message.

According to previous command, another security mode command is found, as shown in Figure 5-30.

Figure 5-30 Security mode message

Setting the security mode succeeds.



Check the RANAP_SECURITY_MODE_COMMAND message, as shown in Figure 5-31.

Figure 5-31 Content of the RANAP_SECURITY_MODE_COMMAND message

According to Figure 5-31, there are two encryption methods: UEA1 and no encryption. According to protocols, there are two encryption methods: encryption and no encryption, engineers need select the algorithm to be encrypted. Namely, UEA1 is needed here.

By comparison of these two encryption mode commands, they are from different CN domain: The CN domain No. of the successful command is 4669, while that of the failed one is 4666. Namely, the CS and PS domain configures different encryption methods.

After the RNC receives the security mode command shown in Figure 5-31, it selects the UEA1 as the encryption algorithm. It then receives the security mode command shown in Figure 5-29 and this command requires no encryption. Therefore, the RNC rejects this security mode command.

Solution After setting the CS and PS encryption algorithm to the same, engineers solve the problem successfully.

5.7 Abnormal Equipment Problems There are various problems about abnormal equipment. Some are about network equipment. Others are about UEs. Engineers must analyze the problem in details. The following sections provide a typical example.

5.7.1 Abnormal NodeB

Description and Analysis The UE cannot connect to the network from a cell all the time during DT. The UE keeps sending the RRC Connection Request message. According to single subscriber tracing by RNC, the RNC receives the RRC Connection Request message and responds the RRC Connection Setup message which the UE fails to receive.



Figure 5-32 shows the signaling of UE upon failure in receiving RRC Connection Setup message.

Figure 5-32 Signaling of UE upon failure in receiving RRC Connection Setup message

Figure 5-33 shows the single subscriber tracing signaling by RNC.




Figure 5-34 shows the normal signal strength upon occurrence of problems.

Figure 5-34 Signal strength upon occurrence of problems

The messages at IUB interface of NodeB and internal message are normal and without alarms according to tracing. To further locate problem in the NodeB equipment room, by test, the UE can sometimes access to the network by antenna where the Ec/Io is about –3 dB, but in rest time it fails with the same phenomena. The RSCP is about –70 dBm. If the UE moves farther, the Ec/Io is about –5 dB and the UE cannot connect to the network in a probability of 80%. The phenomenon is that the UE fails to receive setup message in downlink. According to detection of NodeB console, the output power of NodeB is 24 dBm, but the normal output power is 36 dBm. Therefore the power amplifier is problematic.

Solution After changing the power amplifier, engineers solve the problem successfully.

5.7.2 Abnormal UE There are abundant phenomena about abnormal UE. The following paragraphs provide an example.



Description and Analysis The UE cannot connect to the network for a period. Figure 5-35 shows the signaling of UE.

Figure 5-35 Signaling of UE

Figure 5-36 shows the downlink signal quality.

Figure 5-36 Downlink signal quality

In Figure 5-36,



l The second column is the downlink scramble measured by UE. l The third column is the CPICH Ec/Io measured by UE of the cell. l The fourth and fifth column are the Ec/Io and scramble measured by scanner. l The quality of the signals measured by UE and the signals measured by scanner is much

different from each other during the unconnected time.

Solution This problem is related to UE performance. There are no more solutions except changing UE.



6 Summary

Compared with V2.0, V3.0 addresses operability. It is closer to on-site engineers and can guide on-site engineers to solve actual problems during network optimization. Therefore this guidebook has more updated parts compared with the V2.0 guidebook and addresses the flow for analyzing problems. It guides engineers to solve problem step by step. The fundamental knowledge serves as appendix for reference by on-site engineers.

Compared with V3.0, the V3.1 guidebook adds the following content:

l RRC connection of HSPDA service l Analysis and cases of admission failure in RAB assignment process l HSDPA-related DT and traffic statistics indexes l Some traffic statistics indexes according to that of RNC 1.6C01B064.

In the following versions, the following content needs adding or updating:

l Analyzing of HSUPA access problems l Updating the methods for analyzing traffic statistics and detailed indexes according to

RNC version l Updating the analysis of common problems



7 Appendix 1: Paging Process

7.1 Paging Origination During paging, paging messages are sent on paging control channel (PCCH) to UE in idle mode CELL_PCH or URA_PCH state. The CN might request paging, such as setting up a signaling connection. The UTRAN originates paging the UE in CELL_PCH or URA_PCH state to trigger cell update process. In addition, the UTRAN originates paging the UE in idle mode, CELL_PCH or URA_PCH state to enable UE to read updated system information. In details, the network side originates paging in the following conditions.

7.1.1 Paging by CN The CN originates paging so that the CN can request UTRAN to connect to UE. The paging process is the signaling process without connection at IU interface. The CN triggers paging by sending paging messages. The UTRAN sends the paging message from CN to UE in the paging process at UU interface so that the paged UE is connected to CN.

7.1.2 Paging by UTRAN When the system information changes, the UTRAN triggers paging process to inform UE in idle mode, CELL_PCH and URA_PCH state of updating system information. After this, the UE reads the updated system information.

To trigger the UE in idle mode, CELL_PCH and URA_PCH state for state transition (such as transiting to CELL_FACH state), the UTRAN originates a paging process. As a response to the paging, the UE originates cell update or URA update.

7.2 Paging Flow 7.2.1 Paging Type 1

To setup a call, the CN sends paging message to UTRAN through lu interface. The UTRAN sends the paging message from CN to UE in the paging process at UU interface so that the paged UE is connected to CN.

Paging messages are sent in non-connection message at IU interface. The RNC sends PAGING TYPE 1 message on PCCH in the following two situations:



l After the RNC receives the paging message from CN, the cell Non Searching Indication is specified to non-searching (the RNC does not search whether the UE is in the connected state) in the paging message.

l After the RNC receives the paging message from CN, the cell Non Searching Indication is specified to searching; but the UTRAN cannot find SRNTI (UE in idle state) by IMSI.

If the paging message at IU interface contains LAI or RAI, the RNC will send the PAGING TYPE 1 message to all cells in the specified location area or routing area.

If the paging message at IU interface contains no LAI or RAI, the RNC will send the PAGING TYPE 1 message to all cells under the RNC.

Besides previous situations, the UTRAN sends the PAGING TYPE 2 message on DCCH, which is called the cooperation paging.

Figure 7-1 shows the flow chart of PAGING TYPE 1 message.

Figure 7-1 Flow chart of PAGING TYPE 1 message

CN RNC1 RNC2 NODEB1.1 NODEB2.1 UE

RANAPRANAP

RANAP RANAP

PCCH: PAGING TYPE 1

PAGING

PAGING

PCCH: PAGING TYPE 1

According to Figure 7-1, the CN originates paging in a location area which is distributed under two RNCs. After the RNC receives the paging message, it searches for the matching cells and calculates the paging occasion. It sends the PAGING TYPE 1 message to the cell on PCCH at the paging occasion.



7.2.2 Paging Type 2 Figure 7-2 shows the flow chart of PAGING TYPE 2 message.

Figure 7-2 Flow chart of PAGING TYPE 2 message

CN SRNC UE

RANAPRANAP

PAGING

RRCRRCDCCH: PAGING TYPE 2

According to Figure 7-2, if the UTRAN judges that the paging is cooperation paging, the UE must be in CELL_DCH or CELL_FACH state, so the UTRAN immediately sends the paged UE the PAGING TYPE 2 message on DCCH.

If the UE is in CELL_PC or URA PCH state, the UTRAN sends the PAGING TYPE 1 to UE. After the UE receives the PAGING TYPE 1 message, it originates the cell update process to transit to CELL_FACH state.

Conclusion: If the UE is in CELL_DCH or CELL_FACH state, the network side sends the PAGING TYPE 2 message. If the UE is in other state, the network side sends the PAGING TYPE 1 message.

7.3 Behaviors of UE after Receiving Paging The UTRAN can page multiple UEs in the same paging occasion. The information about the paged UE is contained in the Paging record of PAGING TYPE 1 message. The UE must check every event in Paging record upon receiving PAGING TYPE 1 message. The UE needs to compare the identity of each event and the identity of UE.

7.3.1 UE in Idle Mode If the UE is in idle mode, for the presence of each Paging record IE in the message, the UE will:

l If the IE Used paging identity paging originator is a CN identity, − Compare the IE type of UE identity type in CN IE and the identity of all assigned

UE.



− If one pair matches, this means that UE accepts the paging and forwards the IE CN domain identity, UE identity, and Paging cause to upper layer.

l Otherwise, the UE neglects the paging record.

7.3.2 UE in Connected Mode If the UE is in connected mode, for the presence of each Paging record IE in the message, the UE will:

l If the IE Used paging identity is UTRAN, and the U-RNTI is the same as assigned U-RNTI of UE: − If the Paging record contains the optional IE CN originated page to connected

mode UE, the UE responds that paging is received, and it sends the upper-layer the IE CN domain identity, Paging cause, and Paging record type identifier.

− If the Paging record does not contain the IE CN originated page to connected mode UE, the UE starts cell update process with the cause paging response.

l If the IE is Used paging identity is not UTRAN, the UE will neglects the paging record. If the Paging record contains the IE BCCH modification info, the UE in idle mode, CELL_PCH or URA_PCH state must read the system information again, without reading content of Paging record.

7.4 DRX Process of UE 7.4.1 DRX Cyclic Length and Paging Occasion

UE monitors paging in idle mode in two ways:

l Decode data on SCCPCH every 10ms directly l Decode data on PICH periodically. Only when there is paging indicator, the UE will

decode associated data on SCCPCH, namely, DRX. The UE reduces power consumption by using DRX.

In idle mode, the DRX paging length is calculated as below:

PBPLengthCycleDRX K ×= 2__

Wherein,

l K is the IE CN domain specific DRX cycle length coefficient, which is broadcast in system information. Now the K in CS and PS domain is 8.

l PBP is the paging block period. In FDD mode, the PBP = 1.

Therefore, the previous formula is simplified to:

DRX_Cycle_Length = 28 (1)

The UE paging occasion is calculated as below:

Paging Occasion (CELL SFN) = {(IMSI mod M) mod (DRX cycle length div PBP)} * PBP + n * DRX cycle length + Frame Offset

Wherein,



l n = 0, 1, 2…. . It is necessary to prove that Paging Occasion is smaller than the maximum value of SFN: 4096.

l Frame Offset = 0 (in FDD mode) l M is the number of SCCPCHs that bears PCH, usually equal to 1

Therefore the previous formula is simplified to:

SFN = IMSI mod 2K + n * 2K (2)

The UE only need to monitor paging indicator on PICH frames.

Figure 7-3 shows the schematic drawing of UE paging occasion.

Figure 7-3 Schematic drawing of UE paging occasion

The UE must monitors the frames (paging occasions) indicated by red dots in each paging period, and then decode the qth PI. For the calculation of q, see the formula (3).

7.4.2 Relationship of PICH and SCCPCH The paging indicator channel (PICH) is a physical channel of fixed rate (the spreading factor is 256). It carries paging indicator. The PICH is relevant to SCCPCH mapped by PCH.



Figure 7-4 shows the frame structure of PICH.

Figure 7-4 Frame structure of PICH

b1b0

288 bits for paging indication12 bits (transmission

off)

One radio frame (10 ms)

b287 b288 b299

A 10ms (length) PICH consists of 300 bits (b0, b1… b299). Wherein, the first 288 bits (b0, b1…b288) are to carry paging indicator. The rest 12 bits is for following use.

Each PICH frame carries NP paging. NP is the number of paging indications per frame. It defines the maximum paging indicators supported by each frame on PICH. The UE obtains the value of NP in cell system information. The NP is 18, 36, 72, and 144; namely, the 288 bits are divided by NP, so each division has 288/NP bits. Each division is a paging indicator.

Table 7-1 describes the mapping relationship between {PI0, .., PIN-1} and PICH bits {b0,..,b287}.

Table 7-1 Mapping relationship between PI and PICH

Number of PI per frame (NP)

PIp = 1 PIp = 0

NP=18 {b16p, .. b16p+15} ={1,1,..,1} {b16p, .. b16p+15} = {0,0,..,0}

NP=36 {b8p, .. b8p+7} = {1,1,..,1} {b8p, .. b8p+7} = {0,0,..,0}

NP=72 {b4p, .. b4p+3} = {1, 1,1,1} {b4p, .. b4p+3} = {0, 0,0,0}

NP=144 {b2p, b2p+1} = {1,1} {b2p, b2p+1} = {0,0}

The UE determines by calculating its paging indicator suffix p that p is relevant to the qth bits of PICH frame.

( )( )( ) NpNpSFNSFNSFNSFNPIq mod144

144mod512/64/8/18

×+++×+= (3)

Wherein,

l PI = DRX index mod NP = (IMSI div 8192) mod NP. l SFN is the paging occasion for UE. It is the PCCPCH SFN when PICH is present.

From the formula (3), the UE can know the suffix of PI so that the UE can monitor relevant bits on PICH only. Once the UE detects that the bits are set to 1, it knows that it is paged. It starts receiving and decoding paging messages from 7680 chips after completion of PICH radio frame.



Figure 7-5 shows the time sequence relationship between PICH and SCCPCH.

Figure 7-5 Sequence relationship between PICH and SCCPCH

τPICH

Associated S-CCPCH frame

PICH frame containing paging indicator

The end of PICH radio frame is 7680 chips earlier than associated S-CCPCH frame.

7.4.3 PCH Selection The system information block 5 (SIB5) defines the PCH used in idle mode. In a cell, one or more PCHs are built. In system information, each SCCPCH bears a PCH, so each prescribed PCH corresponds to a unique PICH.

If the SIB5 defines more than one PCH and relevant PICH, the UE selects SCCPCH listed in SIB5 based on IMSI as below:

Index of selected SCCPCH = (IMSI div ((“DRX cycle length”div PBP)*Np*NPICH)) mod K,

Wherein, the K equals to the number of SCCPCHs bearing PCH (for example, those SCCPCHs which bear only one FACH does not counter). These SCCPCHs are marked by 0 to K-1 in the order contained in SIB5. The K is usually 1. Namely, only one SCCPCH bears PCH.

The Index of selected SCCPCH shows the SCCPCH selected by UE-used PCH and the unique corresponding PICH identity.

Now Huawei configures only one PICH and a SCCPCH for a cell. The SCCPCH bears two FACHs and a PCH.

7.4.4 DRX Examples of UE After the cell is set up, the parameter configuration about paging in the broadcast system information is:

l CN domain specific DRX cycle length coefficient = 8 l Number of PI per frame = 36

After the UE receives the information, it calculates the paging occation, PI, and p.

The IMSI of a UE is 448835805669362, so the related parameters are calculated as below:

l DRX cycle length = 28 = 256 l Cell SFN = 448835805669362 mod 28+ n * 28 = 242 + 256 * n (n = 0, 1, 2...) l PI = (448835805669362 div 8192) mod 36 = 14 l q = (14 + [((18 * (242 + [242 / 8] + [242 / 64] + [242 / 512])) mod 144) * 0.25]) mod 36

= 27

From previous data, each frame of the cell PICH carries 36 PIs. Each PI consists of 8 bits (288/36). The UE must monitor the bit216 (27x 8) to bit223 of each PICH radio frame. If



these 8 bits changes to 1, the UE knows that it might be paged, so it receives paging message on SCCPCH.



8 Appendix 2: Access Process Analysis

The UE has two basic operation modes: idle mode and connected mode. When the power is on, the UE is in idle mode. It is identified by non-access layer identity, such as IMSI, TMSI, or P-TMSI. The UTRAN does not save the information of UE in idle mode. It pages respectively the UE that powers on and camps on a cell, or pages all UE in idle mode under an RNC simultaneously. After UE completes RRC connection setup, UE transits from idle mode to the CELL_FACH or CELL_DCH state of connected mode. After the RRC connection is released, the UE transits from connected mode to idle mode.

According to access layer, the access process is the process of UE transiting from idle mode to connected mode. It includes:

l Cell search l Receiving system information broadcast in the cell l Cell selection and reselection l Random access

Once the UE is in connected mode, it can carry out the following non-access layer activities:

l PLMN selection and reselection l Location registration l Service application l Authentication

8.1 Cell Search When the UE is searching for a cell, it selects the corresponding process according to whether there is information about RF channel of UTRA carrier.

l If the UE has no information about RF channel of UTRA carrier, it scans all frequency bands within UTRA band to find the proper cell to camp on in the selected PLMN. In each carrier, the UE searches for the cell with strongest signals.

l If the UE has the saved information about UTRA carrier and cell parameters (such as primary scramble of cell) obtained from previously received measurement control information, the UE tries to camp on the saved cell. If it fails to camp, it scans all frequency bands within UTRA band to find the proper cell to camp on in the selected PLMN.



After the UE locks a frequency, it completes cell search by timeslot synchronization, frame synchronization, and scramble synchronization.

8.1.1 Timeslot Synchronization All synchronization codes of primary SCH in UTRAN are the same, so they are sent in the first 256 chips of each timeslot. The UE can easily synchronize by using a matched filter or similar technologies.

8.1.2 Frame Synchronization and Scramble Group Identification Frame synchronization is fulfilled by using synchronization code of secondary SCH. The secondary SCH has 16 synchronization codes, and they are various in each timeslot. They form 64 groups of code sequence according to code word of each timeslot. The 64 groups of code sequence features that the result after their cyclic shift is unique. The cell scramble group and frame synchronization is determined by performing SSC corelation, FWHT and RS decoding on secondary synchronization.

8.1.3 Identification of Cell Primary Scramble In 8.1.2 , the UE obtains the scramble group of the serving cell. Each scramble group has 8 primary scrambles. The UE keeps searching for the most relevant scramble according to symbol corelation until it determines the primary scramble. After obtaining the code word, the UE can read data from broadcast channel because both the CPICH and PCCPCH use the same scramble and their channel codes are fixed.

8.2 Cell Selection and Reselection After the UE powers on, it searches for cells. After this , it judges whether the current PLMN is suitable according to system information. If the current PLMN is suitable, it performs cell measurement. It judges according to the criterion S whether camping on the cell is suitable. This is the cell selection process.

If the current cell fails to meet the criterion S, the UE starts PLMN selection and cell reselection (First, the UE performs cell reselection in the current PLMN. If no cell meets the conditions, the UE searches for PLMN, and performs cell selection and reselection in other PLMNs). It measures neighbor cells, and then it sorts the measured cells by the criterion R or the criterion H. If a cell meets the criterion S, the UE can camp on it. Cell selection and resection does not only start upon power on, but due to other causes.

8.2.1 Cell Selection The following parameters describe the trigger time, process, and principles for judging suitable cell for cell selection.

Trigger Time The UE starts cell selection in the following situations:

l The UE powers on l The UE transits from connected mode to idle mode l The UE lost cell information in connected mode



l When the UE fails to find a cell for normal camp for cell reselection according to the cell list provided by measurement control system information (TS25.133)

PLMN Selection The UE obtains the PCCPCH scramble according to 8.1.3 . The channel code (SF (=256,1)) of PCCPCH is known, and it is unique in the whole UTRAN. Therefore the UE can read the information on the broadcast channel.

First, the UE obtains SFN from system information sent on BCH (PCCPCH). The first domain of the message is SFNprime. Its value is the initial SFN of the transport block, with its range (0, 2, 4, 6…4094). The rage of SFNprime is (0…2047) after PER coding. The BCH TTI is 20ms. It includes two radio frames, so the step of SFNprime is 2.

The scheduling information is known; namely, SIB_POS = 0 and SIB_REP = 8. After the UE obtains SFN, it can read MIB in the radio frame (SFN = 0, 8, 16…).

After reading MIB, the UE judges according to PLMN identity in MIB whether the current PLMN is the needed PLMN.

l If yes, the UE searches for other SIBs according to the scheduling information of other SIBs contained in MIB, and obtain their content.

l If no, the UE starts cell search from the next frequency.

8.2.2 Judgment Criterion (Criterion S) If the current PLMN is the PLMN needed by UE, the UE reads SIB3 for information about cell selection and reselection. In the IE (Cell selection and re-selection info for SIB3/4),, the UE obtains the following parameters:

l Qqualmin l Qrxlevmin l Maximum allowed UL TX power (UE_TXPWR_MAX_RACH) l Other parameters

After obtaining previous parameters, the UE judge with the criterion S whether the current cell is suitable to camp on.

The criterion S is:

If Srxlev > 0 and Squal > 0, the cell is suitable for UE to camp on.

Wherein,

oncompensatirxlevrxlevmeas

qualqualmeas

PQQSrxlevQQSqual

−−=

−=

min

min



Table 8-1 lists the parameters and their description in the criterion S.

Table 8-1 Parameters and their description in the criterion S

Parameter name Parameter description

Squal Cell Selection quality value, (dB) Not applicable for TDD cells or GSM cells.

Srxlev Cell Selection RX level value (dB)

Qqualmeas Measured cell quality value. The quality of the received signal expressed in CPICH Ec/N0 (dB) for FDD cells. Not applicable for TDD cells or GSM cells.

Qrxlevmeas Measured cell RX level value. This is received signal, CPICH RSCP for FDD cells (dBm), P-CCPCH RSCP for TDD cells (dBm) and RXLEV for GSM cells (dBm).

Qqualmin Minimum required quality level in the cell (dB). Not applicable for TDD cells or GSM cells.

Qrxlevmin Minimum required RX level in the cell. (dBm)

Pcompensation max(UE_TXPWR_MAX_RACH – P_MAX, 0) (dB)

UE_TXPWR_MAX_RACH Maximum TX power level an UE may use when accessing the cell on RACH (read in system information), (dBm)

P_MAX Maximum RF output power of the UE, (dBm)

If the cell meets the criterion S, the UE judges the cell as a suitable cell. Therefore it camps on the cell, reads other needed system information, and originates location registration.

If the cell does not meet the criterion S, the UE searches for the cell meeting the criterion S in the neighbor cells of the cell in the following procedures.

Intra-frequency Neighbor Cell The UE reads the following parameters from SIB11:

l Measurement control system information l Intra-frequency measurement system information l Intra-frequency cell info list l Cell info l Primary CPICH info l Reference time difference to cell l Cell Selection and Re-selection info for SIB11/12 l Others

In the CPICH info, the UE obtains primary scrambling code. The channel code of CPICH is unique in the entire UTRAN. The UE can measure Qqualmeas and Qrxlevmeas (timeslot synchronization and frame synchronization are needed) according to primary scrambling code and reference time difference to cell.



In the Cell Selection and Re-selection info for SIB11/12, the UE obtains the following parameters of neighbor cell:

l Maximum allowed UL TX power l Qqualmin l Qrxlevmin

After this, the UE can calculate the Squal and Srxlev of neighbor cells, and judges whether the neighbor cell meets the previous criterion.

Inter-frequency Neighbor Cell The UE reads the following information from SIB11:

l Inter-frequency measurement system information l Inter-frequency cell info list l Frequency info and cell info l Cell info l Others

The Frequency info contains:

l UARFCN uplink (Nu) l UARFCN downlink (Nd)

By previous information, the UE can calculate the Squal and Srxlev of neighbor cells, and judges whether the neighbor cell meets the previous criterion.

If the UE finds that no cell meets the criterion S, it judges that there is no coverage. Therefore it continues PLMN selection and reselection.

In addition, the UE in idle mode randomly monitors the signal quality of the serving cell and neighbor cells to select a best cell for service. This is cell reselection.

If the UE finds a neighbor cell that meets the criterion S, the UE camps on the cell and reads other needed system information. After this, the UE starts random access and originates location registration.

8.2.3 Cell Reselection The UE completes the following tasks in normally camped state in UTRAN:

l Monitor PCH and PICH as indicated by system information l Monitor related system information l Carry out cell measurement and provide data for evaluating cell reselection

The following paragraphs introduce the trigger time and measurement rule for cell reselection, as well as the principle for evaluating cell reselection.

Trigger Time UE reselects a cell in the following conditions:

l Idle mode time trigger (measured quality value of the serving cell is lower than that of intra-frequency measurement threshold).



l In idle mode, the serving cell in continuous Nserv DRX cannot meet the criterion S (however the system information is configured).

l When the UE detects itself in non-service area.

Measurement Rules The measurement rules when HCS is not used:

If the cell broadcast system information indicates not to use HCS, the UE decides to start the corresponding measurement. In the CPICH Ec/Io measurement state, the Squal corresponds to Sx. In CPICH RSCP measurement state, the Srxlev corresponds to Sx.

l Intra-frequency measurement − If Sx > Sintrasearch, the UE need not to start intra-frequency measurement. − If Sx <= Sintrasearch, the UE starts intra-frequency measurement. − If the system information does not provide Sintrasearch, the UE always starts

intra-frequency. l Inter-frequency measurement

− If Sx > Sintersearch, the UE need not to start inter-frequency measurement. − If Sx <= Sintrasearch, the UE starts inter-frequency measurement. − If the system information does not provide Sintrasearch, the UE always starts

inter-frequency. l Inter-RAT measurement

− If Sx > SsearchRATm, the UE needs not to measurement the system m. − If Sx <= SsearchRATm, the UE starts inter-RAT measurement on the system m. − If the system information does provide SsearchRATm, the UE always starts

inter-RAT measurement on the system m.

The measurement rules when HCS is used:

If the cell broadcast system information indicates not to use HCS, the UE decides to start the corresponding measurement.

l For intra-frequency and inter-frequency threshold-based measurement rules − If Srxlevs <= SsearchHCS or if FDD and Sx <= Sintersearch, the UE measures all

inter-frequency and intra-frequency cells. − Else the UE measures on all intra-frequency and inter-frequency cells, which have

higher HCS priority level than the serving cell unless measurement rules for fast-moving UEs are triggered.

− Else, the UE measure on all intra-frequency and inter-frequency cells, which have equal or higher HCS priority level than the serving cell unless measurement rules for fast-moving UEs are triggered.

l For intra-frequency and inter-frequency measurement rules for fast-moving UEs If the number of cell reselections during time period TCRmax exceeds NCR, high-mobility has been detected. In this high-mobility state, UE shall − Measure intra-frequency and inter-frequency neighbor cells, which have equal or

lower HCS priority than serving cell. − Prioritize re-selection of intra-frequency and inter-frequency neighbor cells on lower

HCS priority level before neighbor cells on same HCS priority level. When the number of cell reselections during time period TCRmax no longer exceeds NCR, UE shall



− Continue these measurements during time period TCrmaxHyst, − Revert to measurements according to the threshold based measurement rules.

The inter-RAT measurement rules with HCS:

l Inter-RAT threshold-based measurement rules − If Srxlevs <= SHCS,RATm or if FDD and Squal <= SSearchRATm, then the UE shall measure

on all inter-RATm cells. − Else if Sx > Slimit,SearchRATm, the UE need not measure neighbor cells in RAT "m" − Else the UE shall measure on all neighbor cells in RAT "m", which have equal or

higher HCS priority level than the serving cell unless measurement rules for fast-moving UEs are triggered.

l Inter-RAT measurement rules for fast-moving UEs If the number of cell reselections during time period TCRmax exceeds NCR, high-mobility has been detected. In this high-mobility state, UE shall − Measure the neighbor cells in RAT "m", which have an equal or lower HCS priority

than the serving cell − Prioritize re-selection of neighbor cells in RAT "m" on lower HCS priority level

before neighbor cells in RAT "m" on same HCS priority level.

When the number of cell reselections during time interval TCRmax no longer exceeds NCR, UE shall

l Continue these measurements during time period TCrmaxHyst, l Revert to measure according to the threshold-based measurement rules.

Judgment Criterion (Criterion H and Criterion R) Evaluating cell reselection occurs in the following situations:

l Internal trigger of UE. For details, see TS 25.133. l The information for evaluating cell reselection on BCCH changes.

The following cell re-selection criteria are used for intra-frequency cells, inter-frequency cells and inter-RAT cells:

The quality level threshold criterion H for hierarchical cell structures is used to determine whether prioritized ranking according to hierarchical cell re-selection rules shall apply, and is defined by:

Hs = Qmeas_LEV,s - Qhcss

Hn = Qmeas_LEV,n - Qhcsn – TOn * Ln

If it is indicated in system information that HCS is not used, the quality level threshold criterion H is not applied.

The cell-ranking criterion R is defined by:



Rs = Qmap,s + Qhysts

Rn = Qmap,n - Qoffsets,n - TOn * (1 – Ln)

Where:

TOn = TEMP_OFFSETn * W(PENALTY_TIMEn – Tn)

Ln = 0 if HCS_PRIOn = HCS_PRIOs

Ln = 1 if HCS_PRIOn <> HCS_PRIOs

W(x) = 0 for x < 0W(x) = 1 for x >= 0

TEMP_OFFSETn applies an offset to the H and R criteria for the duration of PENALTY_TIMEn after a timer Tn has started for that neighbor cell.

TEMP_OFFSETn and PENALTY_TIMEn are only applicable if the usage of HCS is indicated in system information.

The timer Tn is implemented for each neighbor cell. Tn shall be started from zero when one of the following conditions becomes true:

If HCS_PRIOn <> HCS_PRIOs and Qmeas_LEV,n > Qhcsn,

Or

if HCS_PRIOn = HCS_PRIOs and

for serving FDD and neighbor FDD cells if the quality measure for cell selection and reselection is set to CPICH RSCP in the serving cell, and:

Qmap,n > Qmap,s + Qoffset1s,n

for serving FDD and neighbour FDD cells if the quality measure for cell selection and reselection is set to CPICH Ec/No in the serving cell, and:

Qmeas_LEV,n > Qmeas_LEV,s + Qoffset2s,n

for all other serving and neighbour cells:

Qmap,n > Qmap,s + Qoffset1s,n

Tn for the associated neighbour cell shall be stopped as soon as any of the above conditions are no longer fulfilled. Any value calculated for TOn is valid only if the associated timer Tn is still running else TOn shall be set to zero.

At cell-reselection, a timer Tn is stopped only if the corresponding cell is not a neighbour cell of the new serving cell, or if the criteria given above for starting timer Tn for the corresponding cell is no longer fulfilled with the parameters of the new serving cell. On cell re-selection, timer Tn shall be continued to be run for the corresponding cells but the criteria given above shall be evaluated with parameters broadcast in the new serving cell if the corresponding cells are neighbors of the new serving cell.



Table 8-2 Cell reselection parameters and descriptions


Sn Cell Selection value of the neighbor cell, (dB)

Qmap,n Quality of the neighbor cell, after mapping function is applied, derived from CPICH Ec/N0 or CPICH RSCP for FDD cells, from P-CCPCH RSCP for TDD cells and from RXLEV for GSM cells. For FDD cells, the measurement that is used to derive the quality value is set by the Cell_selection_and_reselection_quality_measure information element.

Qmap,s Quality of the serving cell, after mapping function is applied, derived from CPICH Ec/N0 or CPICH RSCP for FDD cells and from P-CCPCH RSCP for TDD cells. For FDD cells, the measurement that is used to derive the quality value is set by the Cell_selection_and_reselection_quality_measure information element.

Qmeas_LEV Quality value. The quality value of the received signal expressed in CPICH_Ec/No or CPICH_RSCP_LEV for FDD cells as set by the Cell_selection_and_reselection_quality_measure information element, P-CCPCH_RSCP_LEV for TDD cells and RXLEV for GSM cells.

The UE shall perform ranking of all cells that fulfill the S criterion among:

l All cells with highest HCS_PRIO meets criterion H, namely, the cells with H > = 0, Note that this rule is not valid when UE high-mobility is detected.

l All cells, not considering HCS priority levels, if no cell fulfil the criterion H >= 0. This case is also valid when it is indicated in system information that HCS is not used, that is when serving cell does not belong to a hierarchical cell structure.

In all cases, the UE shall reselect the new cell, only if the following conditions are met:

l The new cell is better ranked than the serving cell during a time interval Treselection. l M than 1 second has elapsed since the UE camped on the current serving cell.

Table 8-3 Broadcast parameters and description of cell reselection in system information


Qoffset1s,n This specifies the offset between the two cells. It is used for TDD and GSM cells and for FDD cells in case the quality measure for cell selection and re-selection is set to CPICH RSCP.

Qoffset2s,n This specifies the offset between the two cells. It is used for FDD cells in case the quality measure for cell selection and re-selection is set to CPICH Ec/No.

Qhyst1s This specifies the hysteresis value (Qhyst). It is used for TDD and GSM cells and for FDD cells in case the quality measure for cell selection and re-selection is set to CPICH RSCP.




Qhyst2 This specifies the hysteresis value (Qhyst). It is used for FDD cells if the quality measure for cell selection and re-selection is set to CPICH Ec/No.

HCS_PRIOs, HCS_PRIO

This specifies the HCS priority level (0-7) for serving cell and neighbor cells.

Qhcss, Qhcsn This specifies the quality threshold levels for applying prioritized hierarchical cell re-selection.

Qqualmin This specifies the minimum required quality level in the cell in dB. It is not applicable for TDD cells or GSM cells.

Qrxlevmin This specifies the minimum required RX level in the cell in dBm.

PENALTY_TIMEn

This specifies the time duration for which the TEMPORARY_OFFSETn is applied for a neighbor cell.

TEMPORARY_OFFSET1n

This specifies the offset applied to the H and R criteria for a neighbor cell for the duration of PENALTY_TIMEn. It is used for TDD and GSM cells and for FDD cells in case the quality measure for cell selection and re-selection is set to CPICH RSCP.

TEMPORARY_OFFSET2n

This specifies the offset applied to the H and R criteria for a neighbor cell for the duration of PENALTY_TIMEn. It is used for FDD cells in case the quality measure for cell selection and re-selection is set to CPICH Ec/No.

TCRmax This specifies the duration for evaluating allowed amount of cell reselection(s).

NCR This specifies the maximum number of cell reselections.

TCRmaxHyst This specifies the additional time period before the UE can revert to low-mobility measurements.

Treselections This specifies the cell reselection timer value.

SsearchHCS This threshold is used in the measurement rules for cell re-selection when HCS is used. It specifies the limit for Srxlev in the serving cell below which the UE shall initiate measurements of all neighbor cells of the serving cell.

SsearchRAT 1 - SsearchRAT k

This specifies the RAT specific threshold in the serving cell used in the inter-RAT measurement rules.

SHCS,RATm This threshold is used in the measurement rules for cell re-selection when HCS is used. It specifies the RAT specific threshold in the serving cell used in the inter-RAT measurement rules.

Sintrasearch This specifies the threshold (in dB) for intra frequency measurements and for the HCS measurement rules.

Sintersearch This specifies the threshold (in dB) for intra frequency measurements and for the HCS measurement rules.




Slimit,SearchRATm This threshold is used in the measurement rules for cell re-selection when HCS is used. It specifies the RAT specific threshold (in dB) in the serving UTRA cell above which the UE need not perform any inter-RAT measurements in RAT "m".

8.3 Random Access Random access is: after the MS request the system for connection, it receives the response from the system and is probably assigned with DCH.

This process occurs in the signaling connection setup process of the following situations:

l Attach upon power on l Detach upon power off l Location area update l Routing area update l Carrying out any service

3GPP 25.211 defines that the timing relationship of frame structure and physical layer of RACh, PRACH, and access channel.

3GPP 25.213 defines the modulation of preamble on access channel and the spreading modulation of message part (data and control). It also defines the preamble, scramble, and spreading code.

3GPP 25.213 defines the access process.

8.3.1 Random Access Channel RACH is an uplink common transport channel, corresponding to the uplink common physical channel PRACH. The data from RACH is received by NodeB in the whole cell. The feature is with collision and using open loop power control.

The transmission RACH uses the timeslot ALOHA method with fast acquisition indicator. The UE starts transmission in a preset time offset, namely, the access timeslot. Every two 10ms radio frames forms a 20ms access frame, which is divided by 15 access frames into intervals of 5120 chips (1.332ms).



Figure 8-1 shows the timing information and acquisition indicator of access timeslot, and the interval between access timeslots and timeslot number. Whether the information of an access timeslot in the serving cell is available is decided by upper-layer signaling.

Figure 8-1 Number and interval of access timeslots of RACH

#0 #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14

5120 chips

radio frame: 10 ms radio frame: 10 ms

Access slot

Random Access Transmission




The subscriber can originate random access transmission at the beginning of each access timeslot. Figure 8-2 shows the structure of random access transmission. The structure includes message part of 10ms or 20ms.

Figure 8-2 Structure of random access transmission

Message partPreamble

4096 chips10 ms (one radio frame)

Preamble Preamble

Message partPreamble

4096 chips 20 ms (two radio frames)

Preamble Preamble

The preamble length of random access is 4096 chips. It includes a SIGNATURE. The SIGNATURE is 16 chips and is repeated 256 times. In total there are 16 different SIGNATURE.

The 10 ms message part radio frame is split into 15 slots, each of length Tslot = 2560 chips. Each slot consists of two parts, a data part to which the RACH transport channel is mapped and a control part that carries Layer 1 control information. The data and control parts are transmitted in parallel. A 10 ms message part consists of one message part radio frame, while a 20 ms message part consists of two consecutive 10 ms message part radio frames. The message part length is equal to the Transmission Time Interval of the RACH Transport channel in use. This TTI length is configured by higher layers.



The data part consists of 10*2k bits, where k=0,1,2,3. This corresponds to a spreading factor of 256, 128, 64, and 32 respectively for the message data part.

The control part consists of 8 known pilot bits to support channel estimation for coherent detection and 2 TFCI bits. This corresponds to a spreading factor of 256 for the message control part. The pilot bit pattern is described in 3GPP TS 25.211 table 8. The total number of TFCI bits in the random-access message is 15*2 = 30. The TFCI of a radio frame indicates the transport format of the RACH transport channel mapped to the simultaneously transmitted message part radio frame. In case of a 20 ms PRACH message part, the TFCI is repeated in the second radio frame.

The downlink AICH is divided into downlink access slots, each access slot is of length 5120 chips. The downlink access slots are time aligned with the P-CCPCH.

The uplink PRACH is divided into uplink access slots, each access slot is of length 5120 chips. Uplink access slot number n is transmitted from the UE τp-a chips prior to the reception of downlink access slot number n, n = 0, 1, …, 14.

Transmission of downlink acquisition indicators may only start at the beginning of a downlink access slot. Similarly, transmission of uplink RACH preambles and RACH message parts may only start at the beginning of an uplink access slot.

Figure 8-3 shows the PRACH/AICH timing relation.

Figure 8-3 Timing relation between PRACH and AICH as seen at the UE

The preamble-to-preamble distance τp-p shall be larger than or equal to the minimum preamble-to-preamble distance τp-p,min, i.e. τp-p ≥ τp-p,min.

In addition to τp-p,min, the preamble-to-AI distance τp-a and preamble-to-message distance τp-m are defined as follows:

l When AICH_Transmission_Timing is set to 0, then − τp-p,min = 15360 chips (3 access slots) − τp-a = 7680 chips − τp-m = 15360 chips (3 access slots)

l When AICH_Transmission_Timing is set to 1, then − τp-p,min = 20480 chips (4 access slots) − τp-a = 12800 chips



− τp-m = 20480 chips (4 access slots)

The parameter AICH_Transmission_Timing is signaled by higher layers.

8.3.2 Random Access Process

Related Information When the physical layer of UE receives the PHY-DATA-REQ primitives, it starts physical random access process. For details, see 3GPP TRAFFIC STATISTICS 25.321.

Before the UE starts physical random access process, the UE receives the following system information at layer 1 (physical layer) from upper-layer:

l Scramble of preamble l Length of message part, 10ms or 20ms l Value of AICH_Transmission_Timing (0 or 1) l The signature set and RACH subchannel set assigned for each ASC (access subchannel)

number l Power_Ramp_Step (integer > 0) l Preamble_Retrans_Max (integer > 0) l Preamble_Initial_Power l P p-m = Pmessage-control – Ppreamble (in dB) l TFS parameter. It includes the power offset corresponding to each transmission format,

data part and control part of random access message.

Note that the upper-layer might update previous parameters before the UE starts physical random access process.

In addition, before the UE starts physical random access process, the layer 1 shall receive the following information from MAC layer:

l Transmission format for PRACH message part l ASC transmitted on PRACH l The data (TBS) to be sent

Process for Starting Physical Random Access The Process for starting physical random access proceeds as below:

1. Decide available RACH access subchannel set and available uplink access timeslot set of next complete access timeslot set (SFN mod 2 = 0 and SFN mod 2 = 1, the former is called the access timeslot set 1 while the latter is called the access timeslot set 2). Select an uplink access timeslot randomly. The rule for random selection is to select by equivalent probability. If there is no available uplink access timeslot in the current access timeslot set, select one from next access timeslot set.

2. According to provided ASC, select randomly the signature used by access in the signature set.

3. Set the initial value of PRACH preamble retransmission counters to Preamble_Retrans_Max.

4. Set the parameter Commanded Preamble Power to Preamble_Initial_Power.



5. If the parameter Commanded Preamble Power exceeds the maximum allowed value, set the transmit power of preamble to maximum allowed transmit power. If it is lower than the needed minimum value (prescribed by 3GPP TS 25.101), set the transmit power of preamble to the current value to be calculated. This value might be larger or smaller than, equal to Commanded Preamble Power. Otherwise, set the transmit power of preamble to Commanded Preamble Power. Send the preamble with the selected uplink access timeslot, signature, and preamble transmit power.

6. The UE waits for confirmation signals corresponding to the used signature from NodeB. If the UE fails not detect the +1 or –1 acquisition indicator in the downlink access timeslot which has the same number of uplink access timeslot used by transit preamble code, it randomly select the next available access timeslot. According to power ramp step, it increases the Command Preamble Power, deduct the preamble code reset counter by 1. If the Command Preamble Power is 6 dB larger than the maximum allowed power, the UE report layer 1 state ("No ack on AICH") to MAC layer, and then quits the physical random access process. If the retransmission counter value is larger than 0, repeat the sixth step; otherwise, the UE reports layer 1 state ("No ack on AICH") to MAC layer, and then quits physical random access process.

7. If the UE receives an –1 acquisition indicator, it reports layer 1 state ("Nack on AICH received ") to MAC layer, and then quits physical random access process.

8. If the UE receives a +1 acquisition indicator, it sends the random access message part after 3 or 4 uplink access timeslots before last transmission according to the value of AICH_Transmission_Timing. The power for sending control part of random access message is Pp-m higher than the power for sending preamble the last time. For the transmit power of data part, see protocols.

According to previous operation flow for random access, when the UE accesses the network, it first sends preamble, and then waits for the confirmation signals from NodeB in the fixed downlink access timeslot. If the NodeB detects a preamble signal transmitted by UE, the NodeB responds an acquisition indicator signal on downlink AICH. After sending preamble, it detects acquisition indicator (AI) signal in the fixed downlink access timeslot. If the UE is permitted, it keeps sending message part and completes a physical random access. If the UE fails to receive AI, it keeps repeating the handshaking process of "sending preamble to detecting AI" for preset times until permitted. Then it sends the message part and completes a physical random access process. If the UE receives the signal indicating that access is prohibited, it quits this random access process and reports the state. The message part of random access carries the sign information of UE, the type of applicated service, and so on.



Table 8-4 describes the relationship among the access subchannel, access timeslot, and SFN.

Table 8-4 Relationship among the access subchannel, access timeslot, and SFN

SFN modulo 8 of corresponding P-CCPCH frame

Sub-channel number

0 1 2 3 4 5 6 7 8 9 10 11

0 0 1 2 3 4 5 6 7

1 12 13 14 8 9 10 11

2 0 1 2 3 4 5 6 7

3 9 10 11 12 13 14 8

4 6 7 0 1 2 3 4 5

5 8 9 10 11 12 13 14

6 3 4 5 6 7 0 1 2

7 8 9 10 11 12 13 14

Figure 8-4 shows the definition of access timeslot set (taking the uplink and downlink access timeslot fixed difference τp-a = 7680 chips as example).

Figure 8-4 Definition of access timeslot set (taking the uplink and downlink access timeslot fixed difference τp-a 7680 chips as example)

AICH accessslots

10 ms

#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4τp-a

#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4

PRACHaccess slots

SFN mod 2 = 0 SFN mod 2 = 1

10 ms

Access slot set 1 Access slot set 2



9 Appendix 3: Authentication Flow

Figure 9-1 shows a successful authentication process.

Figure 9-1 Successful authentication process

The authentication flow starts from network side. It aims as below:

l The network checks the UE whether the UE is allowed to access the network. l The authentication flow provides random array of authentication quintuple parameters l The UE calculates cipher key (CK). l The UE can calculate the integrity key (IK) related to network side. l The UE can authenticate the network.

Compared with the authentication flow of GSM networks, the authentication flow of 3G networks adds consistency check and the authentication of network by UE. These features further enhance the security of 3G networks.

Before the network side originates authentication, if the VLR has not authenticated the authentication quintuple parameters, the network side first originates the process to HLR for obtaining authentication set, and then waits for response of authentication quintuple parameters. The authentication quintuple parameters include:

l RAND l XRES l AUTN l CK l IK

When detecting that the authentication quintuple parameters are present, the network side sends the authentication request message. This message contains the RAND and AUTN of authentication quintuple parameters. After the UE receives the message, the USIM authenticates AUTN. Namely, the UE authenticates the network. If the authentication passes, the USIM calculates CK, IK, and signature XRES. If the USIM judges that the authentication succeeds, the UE responds XRES in authentication response message.



After the network side receives the authentication response message, it compares the XRES of the message with the XRES of authentication quintuple parameters saved in VLR database. This confirms whether the authentication succeeds. If yes, the flow proceeds. If no, an abnormal processing flow starts. The flow releases the connection between network side and UEs, and releases the occupied network resources and radio resources.

After successful authentication, the UE saves CK and IK to USIM card.

Sometimes, after the UE receives the authentication request message, it reports that the authentication fails. Typical causes of authentication failure include:

l When the UE authenticates the network, it checks the AUTN in authentication request message sent by network side. If the MAC is faulty, the UE sends the authentication failure message with the cause MAC Failure, as shown in Figure 9-2.

Figure 9-2 Authentication Failure (due to MAC Failure)

The network side decides according to subscriber identity reported by UE whether to originate identification process. If the current identity is TMSI (or P-TMSI), the network side originates identification process which requests UE of reporting IMSI. Then the network side restarts authentication flow.

l When UE detects that the SQN of AUTN message is faulty, the authentication fails with the cause Synch failure.



Figure 9-3 Authentication failure (due to Synch failure)

Now the VLR removes all authentication quintuple parameters and starts the process of synchronization with HLR. This process requires HLR to reuse authentication quintuple parameters and to start authentication process.



10 Appendix 4: Description of Access-related Parameters

10.1 Engineering Parameters There are limited adjustable engineering parameters:

l Antenna azimuth l Antenna down tilt l Antenna beamwidth l Antenna gain

To solve access problems caused by coverage, engineers consider adjusting these engineering parameters. For example, constructing new sites in blind areas, increase the antenna gain of serving cells, or decrease the down tilt of antennas in neighbor cells. Avoid the impact on original coverage area by adjustment.

10.2 Cell Parameters The following sections list multiple parameters closely related to access problems. Engineers can adjust these parameters according to the causes when locating the problems.

10.2.1 Transmit Power of FACH This defines the transmit power of FACH.

l If it is set over small, the UE at the cell edge cannot correctly receive the signaling carried by FACH. This impacts the downlink CCH coverage, and consequently impacts the cell coverage.

l If it is set over large, other channels will be impacted, downlink transmit power will be used, and the cell capacity is impacted.

The default power of FACH is –1 dB, and it is based on that the CPICH Ec/Io of coverage cell edge is –12 dB. If the field coverage is worse, raise the FACH power according to CPICH Ec/Io.



10.2.2 Transmit Power of PCH This parameter defines the transmit power of PCH.

l If it is set over small, the UE at the cell edge cannot correctly receive paging messages. Therefore the paging delay increases, paging success rate drops, and access success rate drops.

l If it is set over large, power consumption increases and downlink interference increases.

10.2.3 Transmit Power of PICH It defines the transmit power of PICH.

l If it is set over small, the UE at the cell edge cannot correctly receive paging indicator information. Therefore, the paging delay increases, or mal-operation of reading PCH data is probably performed, the UE consumes more power, the downlink CCH coverage is affected, and finally the cell coverage is affected.

l Because the PICH keeps sending paging indicator information, if the transmit power of PICH is set over large, the PICH will interfere with other channels, consume downlink transmit power, and affects cell capacity. So increasing transmit power of PICH is not recommended. To increase the coverage by PICH signals, decrease NP to 18. Decreasing NP will lead to decrement of paging capacity at UU interface. At the early stage of network construction, setting NP to 18 keeps an adequate paging capacity and it is a typical configuration in the industry.

10.2.4 Cell Reselection Parameter: Measurement Hysteresis 2 (Qhyst2s)

According to criterion R, for cell reselection, the cell performs ranking by the sum of measured value of serving cell and hysteresis. The value of Qhyst2s is closely related to slow fading feature of the area where the cell is. Qhyst2s avoids cell ping-pong reselection due to slow fading when the UE is at the cell edge, because ping-pong reselection leads to frequency location area update (idle mode), URA update (URA_PCH), cell update (CELL_FACH, CELL_PCH), and consequently, network signaling load increases and power consumption by UE increases.

10.2.5 Cell Reselection Parameter: Reselection Hysteresis Time (Treselections)

If the quality of another cell signals (CPICH Ec/No measured by UE) is better than that of serving cell in the time specified by Treselection, the UE reselects the cell to camp on. Treselection avoids ping-pong reselection between cells by UE.

10.2.6 Cell Reselection Parameter: Sintrasearch It is the threshold for starting intra-frequency cell measurement: when the Ec/Io of serving cell is lower than QRelxmin + 2 * Sintrasearch, the intra-frequency cell measurement starts. Sintrasearch affects the speed of cell reselection, and consequently affects the first access success rate of UE and the first paging success rate at IU interface. Set Sintrasearch as large as possible based on little impact on power consumption by UE.



10.2.7 Cell Reselection Parameter: Qoffset2 Before evaluation by criterion R, a neighbor cell has its signal strength deducted by a offset, namely, Qoffset2. For a single-layer cell, set Qoffset2 to 0. Engineers can reach the same goal by Qhyst. Adjusting it is not recommended.

10.2.8 Transmit Power of AICH If it is set over small, the UE at the cell edge cannot correctly receive acquisition indicator. Therefore, the downlink CCH coverage is affected. The default transmit power of AICH is –6 dB. According to optimization result, the default configuration meets the downlink coverage. Since the channel sends data continuously, increasing power lead to increment of needed downlink capacity.

10.2.9 PRACH-related Parameters To solve uplink PRACH problems, adjust PRACH-related parameters, including:

l Retransmission times of preamble l Power step of preamble l Power offset of preamble l Power offset between preamble and message

The previous parameters affect one another. Upon occurrence of PRACH problems, adjust the retransmission times of preamble. The default configuration is 8. It is recommended to set retransmission times of preamble to 20 to avoid PRACH problems.



11 Appendix 5: HSUPA Load Control

The HSUPA load control algorithm described in this chapter is based on UMTS 6.0.

11.1 Admission Decision in HSUPA Cells The admission decision in HSUPA cells includes the following:

l Number of subscribers l Power resources l lub transmission resources l NodeB credit resources

A service is accepted only if all these conditions are met.

11.1.1 Number of Subscribers The RNC must ensure that the number of subscribers in the cell and that in the NodeB do not exceed the related thresholds set in the RNC (Maximum HSUPA user number and NodeB Max Hsupa User Number).

11.1.2 lub Transmission Resources and NodeB Credit Resources

Admission Strategy of lub Resources The lub resource allocation complies with the following principles:

l Physical port: It is equivalent to a resource group. That is, different physical ports cannot share lub resources.

l Each path can belong to only one physical port, while several paths can share the same physical port.

l Physical ports in an ATM network cannot share lub resources with those in an IP network.

l To make full use of physical transmission resources of the lub interface, a path of any type can be configured to the total bandwidth of the physical port where the path is.

l The calculation of consumption of lub resources varies with services:



− For the DCH service, the consumption of lub resources equals to service bandwidth multiplied by the configured activation factor.

− For the HSPA service, the consumption of lub resources equals to GBR of the service multiplied by the configured activation factor.

The admission principles for lub resources are as follows:

l A path of any type can be configured to the total bandwidth of the physical port where the path is. As a result, the sum of bandwidth of all paths on the same physical port might exceed the physical bandwidth. For this reason, two levels of admission are needed: Path-level admission and physical port level admission.

l The lub congestion control must apply to both service congestion and bearer congestion. As for admission, just consider whether lub resources for the related service are adequate.

l The primary path of the service is admitted whenever possible. If this admission fails, try admission of the secondary path.

l The admission threshold varies with admission requests.

The admission requested by the handover has the highest priority, followed by that of new services and that of reconfiguration in the case of rate increase. The admission threshold is set to the reserved bandwidth of the lub interface.

l In the case of handover, the admission uses 100% of the bandwidth by default. The reserved bandwidth is 0 kbps. No new parameter is needed.

l New services are configured on the basis of total bandwidth minus the reserved bandwidth for handover.

l The admission of a reconfiguration request in the case of rate increase is based on the congestion threshold.

The preceding admission strategy of lub resources shows that the setting of activation factor of the BE service greatly impact the number of admitted subscribers. If the activation factor is set to 1.0, the transmission quality of the subscriber can be guaranteed, but the bandwidth of lub interface is greatly wasted. If this parameter is set to a small value, the subscriber suffers packet loss and the bandwidth utilization of the lub interface decreases.

Suppose the following problem occurs in the test: The bandwidth of the lub interface is adequate to bear a 384 Kbps service. If two 384 kbps PS BE services access the lub interface after the activation factor is modified, the traffic rate of both services can reach only 64 kbps when the data source rate is sufficient. The efficient bandwidth usage is only 128 kbps. In this case, the bandwidth of the lub interface is greatly wasted.

This problem occurs because the RLC retransmits the PDU due to random packet loss in the lub transmission. In this case, the delay of transmission of the TCP data packet increases, the TCP flow control is enabled, and the rate decreases. The Overbooking function of the lub resources is adopted to improve bandwidth utilization of the lub interface. To be specific, this function improves the bandwidth utilization by setting the activation factor and avoiding packet loss in the transmission layer.

Admission Strategy of NodeB Credit Resource The basic principle for admission of NodeB Credit resources is similar to that of power resources. That is, whether the admission succeeds depends on whether the available Credit resources in the Local Cell, the Local Cell Group, and the NodeB can support the currently requested service. For details about the local cell, the local cell group, and the CapConsumLaw, refer to 3GPP 25.433.



The CRNC, based on the CapConsumpLaw, addition, deletion, and reconfiguration of common or dedicated channels, borrows or registers the consumed resources from or in the Capacity Credit in the Local Cell, the Local Cell Group (if available), and the NodeB based on the spreading factor of the common or dedicated channel when the common or dedicated channel is set up.

If the UL Capacity Credit is separated from the DL Capacity Credit, maintain the uplinks of the Local Cell, the Local Cell Group (if available), and the NodeB separately from their downlinks. If the UL Capacity Credit is not separated from the DL Capacity Credit, maintain the Global Capacity Credit of the Local Cell, the Local Cell Group (if available), and the NodeB in a centralized manner.

Table 11-1 Number of Credits consumed by different services

Service Direction Type Number of Consumed Credits

12.2kbps AMR DL Local Cell 1

Local Cell Group 1

Node B 1

UL Local Cell 1

Local Cell Group 1

Node B 1

64kbps VP DL Local Cell 2

Local Cell Group 2

Node B 2

UL Local Cell 3

Local Cell Group 3

Node B 3

32kbps PS DL Local Cell 1

Local Cell Group 1

Node B 1

UL Local Cell 1.5

Local Cell Group 1.5

Node B 1.5



Service Direction Type Number of Consumed Credits


Local Cell Group 2

Node B 2

UL Local Cell 3

Local Cell Group 3

Node B 3


Local Cell Group 4

Node B 4

UL Local Cell 5

Local Cell Group 5

Node B 5


Local Cell Group 8

Node B 8

UL Local Cell 10

Local Cell Group 10

Node B 10

The admission decision should be made for the Local Cell, the Local Cell Group, and the NodeB at the same time. The admission is accepted only if all these admissions succeed. The admission threshold varies with admission requests.

l For handover, the admission is accepted only if the CE resources are allocated successfully.

l For a new service, the admission is rejected if the SF of the minimum codes supported by the rest CE resources after the subscriber accesses exceeds the threshold of handover reserved SF of the downlink CE resources. If the SF does not exceed the threshold, the admission succeeds.

l In the case of rate increase, the admission is rejected if the SF of the minimum codes supported by the rest CE resources after the subscriber accesses exceeds the threshold of congestion reserved SF of the downlink CE resources. If the SF does not exceed the threshold, the admission succeeds.



11.1.3 Power Resources For HSUPA cells, the admission of power resources uses only the equivalent number of users (ENU) algorithm. The basic algorithm is the same as the ENU of the DCH. The total ENU of a cell should not exceed the set the threshold (UL threshold of Conv AMR service, UL threshold of Conv non_AMR service, UL Threshold of other services, and UL Handover access threshold).

For RAB over the EDCH, the ENU is calculated on the basis of its GBR.

11.1.4 HSUPA RAB Downlink Admission The downlink power of a cell refers to the reserved power (DL HSUPA reserved factor[%]) of the HSUPA downlink control channel (E-AGCH/E-RGCH/E-HICH).Admission decision for each RAB is not needed.

11.1.5 LDR Different types of channels choose LDR actions as listed in the following table:

LDR Action Type of Channel

DCH HSDPA HSUPA FACH (MBMS)

Inter-Frequency Load Handover √ √ √

BE Rate Reduction √

Inter-RAT Handover in CS Domain

√

Inter-RAT Handover in PS Domain

√ √ √

AMR Rate Reduction √

Iu QoS Negotiation √

Code reshuffling √

MBMS power reduction √

LDR actions supported by the HSUPA subscribers include inter-frequency load handover and inter-RAT handover in the PS domain. If primary congestion occurs in uplink of a HSUPA cell, the HSUPA subscribers can be selected as candidate subscribers together with the DCH subscribers when the inter-frequency load handover or inter-RAT handover in the PS domain is executed. The specific principles for subscriber selection remain unchanged.

If the HSUPA cells adopt the ENU based admission, the uplink LDR is also based on the ENU.



11.1.6 OLC The HSUPA subscribers support only one OLC action: subscriber release. If overload congestion occurs in uplink of a HSUPA cell, the HSUPA subscribers, together with the DCH subscribers, are sorted by priority when the subscriber release is executed. Several subscribers with the lowest priority are chosen for OLC processing.

11.1.7 Description of Parameters

NodeBHsupaMaxUserNum This parameter refers to the maximum number of subscribers over the HSUPA channel of each NodeB. Set this parameter based on specifications of the product and the number of sold HSUPA licenses. If admission of number of HSUPA subscribers of the NodeB is rejected, it indicates that the HSUPA licenses are not enough. In this case, increase the number of the HSUPA licenses.

MAXHSUPAUSERNUM This parameter refers to the maximum number of subscribers supported by the HSUPA channel of a cell. In the case of admission of a HSUPA subscriber, the number of subscribers is check first. If the number of current accessed HSUPA subscribers is smaller than the value of this parameter, the admission proceeds to the next step. If the number of current HSUPA subscribers is larger than the value of this parameter, the admission is rejected. If the value of this parameter is too high, the product is not able to support the accessed subscribers. If the value of this parameter is too small, the HSUPA subscribers are rejected, though the related resources are available.

DLHSUPARSVDFACTOR This parameter reserves resources for the HSUPA downlink control channel. The larger the value of this parameter is, the more resources are reserved for the HSUPA control channel. This might cause waste of resources. If the value of this parameter is too small, the QoS of the HSUPA subscribers is impacted in the case of resource shortage.

UlConvAMRThd This parameter refers to the uplink threshold of the AMR voice service in conversational services. It is used for uplink admission of AMR voice subscribers in conversational services.

The uplink admission control algorithm forecasts the load factor of the system after a new call is accessed based on the load factor of the current system and the service features of the new call. The algorithm then uses the sum of the forecasted load factor and the uplink load factor on the common channel as the new forecasted load factor. At last, the algorithm compares the forecasted load factor with the load factor threshold. If the forecasted load factor does not exceed the load factor threshold, the call is accepted. If the forecasted load factor exceeds the threshold, the call is rejected.

The uplink load threshold includes this parameter, UlConvNonAMRThd, UlOtherThd, and ULHOThd. The relationship between these four parameters can be used to limit the ratio of sessions to other services in the cell and to ensure priority of access of handover subscribers and conversational services.

If the value of this parameter is too large, excessive load might exist over the system after admission of the conversational service. In this case, congestions occur in the system. If the



value of this parameter is too small, subscribers might be rejected though the related resources are available.

Pay attention to the network planning when setting this parameter, UlConvNonAMRThd, UlOtherThd, and ULHOThd. If the value of this parameter is too large, the target coverage is impacted. If the value of this parameter is too small, the target capacity cannot be ensured.

UlConvNonAMRThd This parameter refers to the uplink threshold of non-AMR voice service in conversational services. It is used for uplink admission of non-AMR voice subscribers in conversational services.

The uplink admission control algorithm forecasts the load factor of the system after a new call is accessed based on the load factor of the current system and the service features of the new call. The algorithm then uses the sum of the forecasted load factor and the uplink load factor on the common channel as the new forecasted load factor. At last, the algorithm compares the forecasted load factor with the load factor threshold. If the forecasted load factor does not exceed the load factor threshold, the call is accepted. If the forecasted load factor exceeds the threshold, the call is rejected.

The uplink load threshold includes this parameter, UlConvAMRThd, UlOtherThd, and ULHOThd. The relationship between these four parameters can be used to limit the ratio of sessions to other services in the cell and to ensure priority of access of handover subscribers and conversational services.

If the value of this parameter is too large, excessive load might exist over the system after admission of the service. In this case, congestions occur in the system. If the value of this parameter is too small, subscribers might be rejected though the related resources are available.

Pay attention to the network planning when setting this parameter, UlConvAMRThd, UlOtherThd, and ULHOThd. If the value of this parameter is too large, the target coverage is impacted. If the value of this parameter is too small, the target capacity cannot be ensured.

UlOtherThd This parameter refers to the uplink threshold of services except the conversational services. This parameter is used for uplink admission of other services.

If the value of this parameter is too large, excessive load might exist over the system after admission of the service. In this case, congestions occur in the system. If the value of this parameter is too small, subscribers might be rejected though the related resources are available.

Pay attention to the network planning when setting this parameter, UlConvAMRThd, UlOtherThd, and ULHOThd. If the value of this parameter is too large, the target coverage is impacted. If the value of this parameter is too small, the target capacity cannot be ensured.

ULHOThd This parameter refers to uplink threshold of handover for uplink admission of handover subscribers. This parameter applies only to uplink inter-frequency handover.

The uplink admission control algorithm forecasts the load factor of the system after a new call is accessed based on the load factor of the current system and the service features of the new call. The algorithm then uses the sum of the forecasted load factor and the uplink load factor



on the common channel as the new forecasted load factor. At last, the algorithm compares the forecasted load factor with the load factor threshold. If the forecasted load factor does not exceed the load factor threshold, the call is accepted. If the forecasted load factor exceeds the threshold, the call is rejected.

The uplink load threshold includes this parameter, UlConvAMRThd, UlConvNonAMRThd, and UlOtherThd. The relationship between these four parameters can be used to limit the ratio of sessions to other services in the cell and to ensure priority of access of handover subscribers and conversational services.

The value of this parameter should be lower than the uplink OLC trigger threshold of the intelligent load control.

This parameter is used to reserve resources for handover and ensure quality of the handover. The value of this parameter must exceed the values of UlConvAMRThd and UlConvNonAMRThd. This parameter applies only to inter-frequency handover.

If the value of this parameter is too large, excessive load might exist over the system after admission of the service. In this case, congestions occur in the system. If the value of this parameter is too small, subscribers might be rejected though the related resources are available. Pay attention to UlConvAMRThd, UlConvNonAMRThd, and UlOtherThd when setting this parameter.



List of Reference

1. 3GPP R99 TS 24.008 V3.7.0. 2001-03 2. 3GPP R99 25_series. 2002-09 3. URNP-SANA. W-RNO Access Procedure Analysis Guidance 20041101-A-1.0.doc.

2003-05 4. URNP-SANA. W-Paging Procedure Analysis Guidance 20041101-A-1.0.doc. 2003-12 5. URNP-SANA. W-Paging Problem Analysis Guidance 20041101-A-1.0.doc. 2003-12 6. Joint-research team on RNO project. Call Delay Test Report. 2005-12 7. RAN Radio Performance Dept.. WCDMA RAN Radio Performance Call Access Delay

Optimization Test Report. 2004-02 8. RAN Radio Performance Dept.. W-RAN Traffic Statistics analysis and Problem

Location Guidance-20050926-A-1.0.doc. 2005-09 9. RAN Radio Performance Dept.. UMTS Radio Network KPI baseline (V3.3). 2006-01 10. RRNP. WCDMA RNO Network Event Definition Baseline 1.0. 2005-11

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