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WCDMA (UMTS) Inter-System NetOpt Workshop

WCDMA (UMTS) Inter-System Network

Optimization Workshop

WCDMA (UMTS) Inter-System Network

Optimization Workshop

Student GuideBook 1

80-W0242-4 Rev D

Telefonica, Argentina Training, Buenos Aires, Argentina, August/September 2008

Material Use RestrictionsThese written materials are to be used only in conjunction with the associated instructor-led class. They are not intended to be used solely as reference material.

No part of these written materials may be used or reproduced in any manner whatsoever without the written permission of QUALCOMM Incorporated.

Copyright © 2007 QUALCOMM Incorporated. All rights reserved.

QUALCOMM Incorporated5775 Morehouse DriveSan Diego, CA 92121-1714U.S.A.

This technical data may be subject to U.S. export, re-export or transfer ("export") laws. Diversion contrary to U.S. law is prohibited.

QUALCOMM is a registered trademark and registered service mark of QUALCOMM Incorporated. QUALCOMM University is a trademark of QUALCOMM Incorporated.

cdma2000® is a registered certification mark of the Telecommunications Industry Association. Used under license. All other trademarks and registered trademarks are the property of their respective owners.


WCDMA (UMTS) Inter-System Network Optimization Workshop 80-W0242-4 Rev DTable of Contents

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WCDMA (UMTS) Inter-System NetOpt Workshop About QUALCOMM University

QUALCOMM University (“QU”) offers the advanced technology training solutions you need to stay on the cutting edge of wireless technology.

Visit the QU website for more information about individual training products, international training centers, and distance learning opportunities, along with a complete list of classes—all developed by QUALCOMM, the pioneers of CDMA.

QUALCOMM University: www.qualcommuniversity.comQUALCOMM: www.qualcomm.com

Notes

iii





WCDMA (UMTS) Inter-System NetOpt Workshop Where Can I Learn More?

UMTS/WCDMA Network Planning (2 days)

Want to learn more?QUALCOMM University offers additional in-depth technical training related to this course. To learn more about this or related topics, sign up for the following courses.

To check out the schedules for these courses and enroll, go to:

www.qualcommuniversity.com

Notes

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WCDMA (UMTS) Inter-System NetOpt Workshop CDMA Courses from CDMA University

CDMA University training is offered by the CDMA Development Group (CDG) in association with QUALCOMM. For the latest information on all CDMA University courses, visit http://www.cdmauniversity.com/.

Notes



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WCDMA (UMTS) Inter-System NetOpt Workshop UMTS Courses from QUALCOMM University

For the latest information on all QUALCOMM University courses, visit www.qualcommuniversity.com.

Notes



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Table of Contents – Book 1 Section 1: WCDMA (UMTS) Inter-System Network Optimization Workshop – Overview ....................................... 1-1 Workshop Learning Objectives ............................................................... 1-2 Workshop Topics – Advanced Modules: Inter-System Continuity......... 1-3 Workshop Structure ................................................................................. 1-4 Reference Material From the Standard........................................................................ 1-6 Other Published Sources .............................................................. 1-7 Section 2: Basic Considerations............................................................ 2-1 Section Learning Objectives .................................................................... 2-2 Inter-System Basics ................................................................................. 2-3 Terminology................................................................................. 2-5 Introduction to Inter-RAT............................................................ 2-6 Use Cases ..................................................................................... 2-7 Transition Types .......................................................................... 2-8 State Diagram............................................................................... 2-9 Inter-RAT or Inter-System Continuity....................................... 2-10 Transitions and Terminals...................................................................... 2-11 Inter-RAT Blind Handover / Change..................................................... 2-13 Dual Receiver Terminal............................................................. 2-14 Single Receiver Terminal .......................................................... 2-15 Blind and Non-Blind Handover / Change.............................................. 2-16 Single Receiver and Dual Receiver Terminal........................................ 2-17 Transitions and Terminals – Summary.................................................. 2-18 Call Flow for Inter-System Transitions ................................................. 2-19 Objectives .................................................................................. 2-20 Inter-RAT Handover (CS) 3G to 2G Call Flow.................................................................... 2-21 2G to 3G Call Flow.................................................................... 2-23 2G to 3G Abnormal Cases ......................................................... 2-24 Call Flow Example From 3G to 2G........................................... 2-25 Inter-RAT Cell Change Order (PS) 3G to 2G Call Flow.................................................................... 2-26 Handling Handover Failure............................................ 2-27 Example ......................................................................... 2-28 2G to 3G Call Flow.................................................................... 2-29 Example ......................................................................... 2-30 Call Flow for Inter-System Changes – Summary.................................. 2-31



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Inter-RAT Measurement in UMTS........................................................ 2-32 Idle/Cell_PCH/URA_PCH Mode .............................................. 2-33 Cell_FACH Mode...................................................................... 2-34 Inter-RAT Measurement in GSM/GPRS................................... 2-35 Compressed Mode (CM)............................................................ 2-36 Comparing SF/2 and HLS.............................................. 2-38 SF/2 Compressed Frame Characteristics ....................... 2-39 HLS Frame Characteristics ............................................ 2-40 Summary.................................................................................... 2-41 Basic Considerations – What Did We Learn? ....................................... 2-43 Section 3: Overview of IRAT Issues in UMTS Networks .................. 3-1 Section Learning Objectives .................................................................... 3-2 General Approach to Address Issues ....................................................... 3-3 Identify IRAT Issues Using Network Performance Counters ................. 3-4 Data Collection and Post-Processing Tools Overview ............................ 3-5 Data Collection Hardware........................................................................ 3-6 Data Collection Software......................................................................... 3-7 Data Collection Setup (UE and Scanner)................................................. 3-8 Data Collection Procedure ....................................................................... 3-9 Impact of RF Issues on Inter-RAT Performance ................................... 3-10 Common Issues During IRAT Transition.............................................. 3-11 Recommended Solutions to Address IRAT Issues ................................ 3-14 Overview of IRAT Issues in UMTS Networks – What Did We Learn? ................................................................. 3-17 Section 4: Configuration and Parameter Settings .............................. 4-1 Section Learning Objectives .................................................................... 4-2 Algorithms and Parameters for Inter-RAT Cell Reselection................... 4-3 UTRAN to GERAN Cell Reselection...................................................... 4-4 Inter-RAT Scenarios .................................................................... 4-5 Parameters.................................................................................... 4-6 GSM to UTRAN Cell Reselection (Idle Mode) ...................................... 4-8 GPRS/EDGE to UTRAN Cell Reselection List With or Without PBCCH .......................................................................... 4-9 GPRS to UTRAN Cell Reselection (GPRS Mode with PBCCH) ......... 4-10 GERAN to UTRAN Cell Reselection Parameters................................. 4-11 Q_Search, 3G_Search_Prio, FDD_Qmin .................................. 4-12 Summary – Algorithms and Parameters for Inter-RAT Cell Reselection ......................................................................... 4-13 Typical Compressed Mode and Inter-RAT Transition Mechanisms..... 4-14 Compressed Mode Activation and Configuration ................................. 4-15 Event Triggers for Compressed Mode................................................... 4-16 CM Triggers using Events 2d and 2f ..................................................... 4-17 CM Triggers using Events 1e and 1f ..................................................... 4-18



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Event Triggers for Inter-RAT Transition............................................... 4-19 UTRAN to GERAN HO Parameters (Event Trigger) ........................... 4-20 GERAN to UTRAN HO Parameters ..................................................... 4-23 Q_Search, 3G_Search_Prio, FDD_Qmin .................................. 4-25 Exercises Event Triggers for Inter-RAT (1) .............................................. 4-26 Answers.......................................................................... 4-27 Event Triggers for Inter-RAT (2) .............................................. 4-28 Answers.......................................................................... 4-29 Compressed Mode Using Events 2d and 2f............................... 4-30 Answers.......................................................................... 4-31 Inter-RAT Transition via Event 3a ............................................ 4-32 Answers.......................................................................... 4-33 Compressed Mode and Inter-RAT............................................. 4-34 Answers.......................................................................... 4-35 Summary – Typical Compressed Mode Activation and Configuration ...................................................................... 4-36 A Step Back View – WCDMA-to-GSM/GPRS Handover Process ...... 4-37 Inter-RAT Handover Call Flow Review ....................................................................................... 4-38 Drilling Down ............................................................................ 4-39 Configuration and Parameter Settings – What Did We Learn?............. 4-45 Section 5: Compressed Mode Settings ................................................. 5-1 Section Learning Objectives .................................................................... 5-2 Compressed Mode Settings...................................................................... 5-3 Compressed Mode Measurement Purpose............................................... 5-4 Exercise: Transmission Gap Pattern Sequences ...................................... 5-5 Answers........................................................................................ 5-6 Compressed Mode Parameters – Conceptual View................................. 5-7 Transmission Gap Positions..................................................................... 5-8 TGL and GSM Measurements ................................................................. 5-9 Compressed Mode for GSM Measurements.......................................... 5-10 Exercise: Compressed Mode Configuration .......................................... 5-12 Answers...................................................................................... 5-13 Other Compressed Mode Parameters..................................................... 5-14 Frame Structure Types in DL CM ......................................................... 5-15 OVSF Code During CM ........................................................................ 5-16 Power Control Parameters ..................................................................... 5-17 Other TGPS Parameters......................................................................... 5-18 Inter-RAT Compressed Mode Settings.................................................. 5-19 Compressed Mode Activation and Configuration Settings Examples... 5-20



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Call Flow Network A.................................................................................. 5-21 Network B.................................................................................. 5-22 Network C.................................................................................. 5-23 Network D.................................................................................. 5-24 Examples of Compressed Mode Pattern ................................................ 5-25 CM Parameter Setting Tradeoffs Compressed Mode Duration ...................................................... 5-26 Transmission Gap Density......................................................... 5-27 TGD and TGL............................................................................ 5-28 QUALCOMM Recommended CM Patterns.......................................... 5-29 Inter-RAT Compressed Mode Settings – Summary .............................. 5-30 Compressed Mode with HSDPA ........................................................... 5-31 HSDPA Frames around Compressed Mode Gaps ................................. 5-32 HSDPA to GPRS/EDGE Handover (Call Flow A) ............................... 5-33 HSDPA to GPRS/EDGE Handover (Call Flow B)................................ 5-34 Compressed Mode with HSDPA – Summary........................................ 5-35 Compressed Mode Settings – What Did We Learn? ............................. 5-36 Section 6: Practical Considerations...................................................... 6-1 Section Learning Objectives .................................................................... 6-2 Setting Inter-System Boundaries Consideration ............................................................................... 6-3 Trade-offs..................................................................................... 6-4 Reselection and Handover Boundaries Ping-Pong..................................................................................... 6-5 Between WCDMA and GSM ...................................................... 6-6 Reselection and Handover Example ........................................................ 6-7 Challenges Inter-RAT Timing Trigger........................................................... 6-8 Avoiding Ping-Pong Effect.......................................................... 6-9 Network Planning Inter-system Boundaries and Thresholds................................... 6-10 Estimating Inter-RAT Boundaries and Threshold ..................... 6-11 Sample Area for Observation................................................................. 6-12 Reselection Boundary Estimation.......................................................... 6-13 Loaded........................................................................................ 6-14 Reselection Boundary Verification........................................................ 6-15 Handover and Reselection Boundary Comparison ................................ 6-16 Effective Coverage Consideration ......................................................... 6-17 Performance Evaluation Metrics............................................................ 6-18 Exercise: Performance Metrics for Inter-System Reselection ............... 6-19 Inter-RAT Performance Evaluation....................................................... 6-20 Practical Considerations – What Did We Learn? .................................. 6-31



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Cell Reselection Success Rate ............................................................... 6-21 Cell Reselection Ping-Pong Rate ........................................................... 6-22 Cell Reselection Time............................................................................ 6-23 Service Effects on KPIs ......................................................................... 6-25 Inter-RAT Performance Evaluation....................................................... 6-26 Inter-System Handover or CCO............................................................. 6-27 Inter-System Handover/Change Delays................................................. 6-28 Throughput ........................................................................................ 6-29 Common Handover/COO Failures ........................................................ 6-30 Section 7: Inter-System Continuity: Hands-On Module.................... 7-1 Section Learning Objectives .................................................................... 7-2 Drive Test Objectives .................................................................................... 7-3 Key Steps ..................................................................................... 7-4 Scenarios and Objectives ............................................................. 7-5 Analysis – RF .......................................................................................... 7-6 RF Observations Best Cell PSC............................................................................... 7-7 Best Cell PSC Map ...................................................................... 7-8 Best Cell Ec/No Map .................................................................... 7-9 GSM Serving Cell RxLev Map.................................................. 7-10 Summary.................................................................................... 7-11 Recommendations...................................................................... 7-12 Analysis – Inter-RAT Cell Reselection ................................................. 7-13 System Parameters Verification................................................. 7-14 Parameter Settings ..................................................................... 7-15 Definitions.................................................................................. 7-16 Analysis Flow Chart .................................................................. 7-18 WCDMA to GSM Analysis ....................................................... 7-19 WCDMA to GSM Reselection Map.......................................... 7-20 WCDMA to GSM Performance Statistics ................................. 7-21 WCDMA to GSM Cell Reselection Delay ................................ 7-22 Distribution of Poor Service Durations...................................... 7-23 Serving Cell Ec/No Distribution Before Reselection.................. 7-24 Serving Cell RSCP Distribution Before Reselection................. 7-25 WCDMA to GSM Observations................................................ 7-26 GSM to WCDMA Analysis ....................................................... 7-27 GSM to WCDMA Reselection Map.......................................... 7-28 GSM to WCDMA Performance Statistics ................................. 7-29 GSM to WCDMA Cell Reselection Delay ................................ 7-30 Poor Service Duration Distribution in G W Runs ................. 7-31 GSM to WCDMA Reselection Observations ............................ 7-32



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Analysis – Inter-RAT Handover............................................................ 7-33 WCDMA to GSM Handover Mechanism.................................. 7-34 System Parameters ..................................................................... 7-35 Parameter Settings ..................................................................... 7-37 Definitions and Abbreviations ................................................... 7-39 Analysis Flow Chart .................................................................. 7-40 Event 2d Locations .................................................................... 7-41 Event 2f Locations ..................................................................... 7-42 Event 3a Locations..................................................................... 7-43 Inter-RAT HO Locations ........................................................... 7-44 Performance Statistics................................................................ 7-45 Handover Event Statistics .......................................................... 7-47 CM Duration Distribution.......................................................... 7-48 Best Server Ec/No Distribution (in CM)..................................... 7-49 Best Server RSCP Distribution (in CM).................................... 7-50 UE Tx Power Distribution (in CM) ........................................... 7-51 Downlink BLER Distribution (in CM)...................................... 7-52 Call Drop Summary ................................................................... 7-53 Call Drop Locations in WCDMA.............................................. 7-54 Observations .............................................................................. 7-55 Analysis – Inter-RAT CCO ................................................................... 7-56 WCDMA->GPRS Cell Change Order Mechanism ................... 7-57 System Parameters ..................................................................... 7-58 Parameter Settings ..................................................................... 7-60 Definitions and Abbreviations ................................................... 7-62 Analysis Flow Chart .................................................................. 7-63 Event 2d Locations .................................................................... 7-64 Event 2f Locations ..................................................................... 7-65 Event 3a Locations..................................................................... 7-66 CCO Locations........................................................................... 7-67 Performance Statistics................................................................ 7-68 Events Statistics ......................................................................... 7-70 CM Duration Distribution.......................................................... 7-71 TCP Throughput ........................................................................ 7-72 Call Drop Summary ................................................................... 7-73 Call Drop Locations in WCDMA.............................................. 7-74 Observations .............................................................................. 7-75 Cell Reselection Performance Conclusions ........................................... 7-76 Inter-RAT Handover Conclusions ......................................................... 7-77 Inter-RAT CCO Conclusions................................................................. 7-78 Inter-System Continuity: Hands On Module – What Did We Learn?... 7-79



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Section 8: Appendices ............................................................................ 8-1 Section Introduction................................................................................. 8-2 Appendix A – IRAT Metric Route Selection .......................................... 8-3 (A) Metric Route Selection...................................................................... 8-4 (A) Metric Route Example....................................................................... 8-5 Appendix B – IRAT Log Mask ............................................................... 8-6 (B) Define Log Mask ............................................................................... 8-7 (B) Log Mask Example – Cell Reselection ............................................. 8-8 (B) Log Mask Example – Handover........................................................ 8-9 Appendix C – Test Setup and Test Cases .............................................. 8-10 (C) Test Setup ........................................................................................ 8-11 (C) WCDMA to GSM Cell Reselection Test Case................................ 8-12 (C) GSM to WCDMA Cell Reselection Test Case................................ 8-13 (C) Inter-RAT Handover Test Case....................................................... 8-14 (C) WCDMA to GSM Transition During PS Call Test Case ................ 8-15 (C) GSM to WCDMA Transition During PS Call Test Case ................ 8-16 Appendix D – Conducting the Drive Test ............................................. 8-17 (D) Conducting the Drive Test – What to Observe .............................. 8-18 (D) Conducting the Drive Test – Using CAIT for a Cell Reselection Test ........................................................................................ 8-19 (D) Conducting the Drive Test – Using CAIT for a Handover/PS Test ........................................................................................ 8-20 (D) Conducting the Drive Test – Other Windows in PS Inter-RAT Test ........................................................................................ 8-21




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Acronyms and Abbreviations 3GPP Third Generation Partnership Project AC Alternating Current ACK Acknowledgment AGC Automatic Gain Control AICH Acquisition Indicator CHannel AKA Authentication and Key Agreement AM Acknowledged Mode AMR Adaptive Multi-Rate AS Active Set ASET Active SET ASU Active Set Update BCCH Broadcast Control CHannel BLE BLock Error BLER BLock Error Rate BPL Building Penetration Loss BS Base Station CAIT CDMA Air Interface Tester CapEx Capital Expenditure CC Call Control CCCH Common Control CHannel CCO Cell Change Order CCTrCH Coded Composite Transport CHannel CDF Cumulative Distribution Function CDMA Code Division Multiple Access CFN Connection Frame Number CH CHannel CK Cipher Key CM Compressed Mode CN Core Network CPICH Common PIlot CHannel CR Cell Reselection CRC Coding Rate Configuration CRC Cyclic Redundancy Check CS Circuit Switched dB Decibel dBm Decibel referenced to 1 milliwatt DC Direct Current DCCH Dedicated Control CHannel DCH Dedicated Channel DCR Dropped Call Rate DL DownLink DLBLER DownLink Block Error Rate DPC Downlink Power Control DPCCH Dedicated Physical Control CHannel

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DPCH Dedicated Physical CHannel DPDCH Dedicated Physical Data CHannel DRX Discontinuous Reception DSP Digital Signal Processing DTCH Dedicated Traffic Channel EDGE Enhanced Data for GSM Evolution FACH Forward Access CHannel FDD Frequency Division Duplex FDMA Frequency Division Multiple Access FTP File Transfer Protocol G W GSM to WCDMA GERAN GSM/EDGE Radio Access Network GPRS General Packet Radio Service GPS Global Positioning System GSM Global System for Mobile communications HLS Higher Layer Scheduling HO HandOver HPA High Power Amplifier Hz Hertz ID Identification IE Information Element IK Integrity Key IMA Idle Mode Analysis IOT Inter Operability Testing IRAT Inter-Radio Access Technology IRHO Inter-RAT HandOver KPI Key Performance Indicator L1 Layer 1 LNF LogNormal Fading MAC Medium Access Control MCM Measurement Control Message MHz Megahertz MM Mobility Management MO Mobile Originated MRM Measurement Report Message ms Millisecond MSC Mobile Switching Center MT Mobile Terminated NAS Non-Access Stratum NBAP Node B Application Part NE Network Element NL Neighbor List Node B A logical node responsible for radio transmission/reception

in one or more cells to/from the User Equipment NW Network O&M Operations and Maintenance




OOS Out-of-Service-Area OTA Over-the-Air OVSF Orthogonal Variable Spreading Factor PA Power Amplifier PC Power Control PCCH Paging Control CHannel PCCPCH Primary Common Control Physical CHannel PCP Power Control Preambles P-CPICH Primary Common Pilot CHannel PDF Power Density Function PDP Packet Data Protocol PDU Protocol Data Unit PICH Page Indicator CHannel PLMN Public Land Mobile Network P-RACH Physical Random Access CHannel PRACH Physical Random Access CHannel PS Packet Switched PSC Primary Scrambling Code PSC Primary Synchronization Code QoS Quality of Service RAB Radio Access Bearer RACH Random Access CHannel RAT Radio Access Technologies RB Radio Bearer RF Radio Frequency RIP Radio Interface Protocols RLC Radio Link Control RLS Radio Link Set RNC Radio Network Controller RRC Radio Resource Control RSCP Received Signal Code Power RSSI Received Signal Strength Indicator Rx Receive SC Scrambling Code SC Switched Circuit SCCPCH Secondary Common Control Physical CHannel SCH Synchronization Channel SF/2 Spreading Factor Reduction by 2 SIB System Information Block SIR Signal-to-Interference Ratio SRB Signal Radio Bearer TA Temporal Analyzer TDMA Time Division Multiple Access TPC Transmit Power Control TTI Transmission Timing Interval

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TTT Time-To-Trigger Tx Transmit UE User Equipment UL UpLink ULA UTRAN Location Area ULPC UpLink Power Control UM Unacknowledged Mode UMTS Universal Mobile Telecommunications System URA UTRAN Routing Area USB Universal Serial Bus USIM Universal Subscriber Identity Module UTRAN Universal Terrestrial Radio Access Network W G WCDMA to GSM WCDMA Wideband Code Division Multiple Access


1-1

WCDMA (UMTS) Inter-System Network Optimization Workshop 80-W0242-4 Rev DSection 1: Workshop Overview


Section 1-1



Section 1: WCDMA (UMTS) Inter-System Network Optimization Workshop – Overview

Workshop Overview 1SECTION

Notes


1-2



Section 1-2



Workshop Learning Objectives

Prepare students for initial network optimization of a WCDMA (UMTS) network through practical exercises and real-life troubleshooting of network issues.

Provide step-by-step coaching on how to assess network performance and how to improve network performance.

Notes


1-3



Section 1-3



Workshop Topics –Advanced Modules: Inter-System Continuity

1. Workshop Overview

2. Inter-System Continuity – Basic Considerations

3. Overview of IRAT Issues in UMTS Networks

4. Inter-System Continuity – Configuration and Parameter Settings

5. Inter-System Continuity – Compressed Mode Settings

6. Inter-System Continuity – Practical Considerations

7. Inter-System Continuity – Hands-On Module

8. Appendices

Notes


1-4



Section 1-4



Workshop Structure

Procedures to assess IRAT performance, and identify and address IRAT Issues7: Hands-On Module

Common causes of IRAT issues and recommended solutions to address these issues

3: Overview of IRAT Issuesin UMTS Networks

Test setup & procedures for data collection8: Appendices

Workshop overview and structure1: Workshop Overview

Fundamental knowledge about IRAT2: Basic Considerations

IRAT cell reselection & handover configuration and parameter settings

4: Configuration &Parameter Settings

Parameters for configuring compressed GAP and Power Control; HSDPA Compressed Mode Configuration

5: Compressed ModeSettings

Practical considerations for IRAT6: Practical Considerations

4 days

2 daysDescriptionSection

Notes


1-5



Section 1-5



Workshop Structure

• This workshop combines instructor-based teaching and hands-on exercises for students.

• For the hands-on exercises, log files (most of them collected with QUALCOMM’s QCTest tool, CAIT) have been post-processed and formatted.

• Students will need:– Microsoft Excel: to view tables– Text editor: to view messages– MapInfo: to view 2-D plots– Actix Analyzer: to analyze logs (for the hands-on module only)

Workshop Structure

The exercises will be led by instructors.


1-6



Reference Material: 3GPP Relevant Standards

Important 3GPP Specifications

21.905 Vocabulary specifications23.003 Numbering, addressing and identification23.009 Core Network and Terminals: Handover Procedure23.101 General UMTS Architecture24.008 Core Network protocol25.101 UE radio transmission and reception25.104 FDD BS radio transmission and reception25.133 Requirements for Support of Radio Resource Management25.211 Physical and Transport channels25.212 Multiplexing and channel coding25.213 Spreading and modulation25.214 Physical layer protocol25.215 Physical layer measurements25.301 RIP architecture25.304 UE idle mode and connected mode procedures25.306 UE Radio Access capabilities25.321 MAC protocol25.322 RLC specifications25.331 RRC specifications25.401 UTRAN Descriptions25.433 UTRAN Iub interface NBAP signaling25.931 UTRAN Functions, Examples on Signaling Procedures


1-7



Reference Material: Other Published Sources

[1] H. Holma and A. Toskala, WCDMA for UMTS. Wiley & Sons, LTD.

[2] H. Kaaranen, A. Ahtiainen, L. Laitininen, S. Naghian, V. Niemi, UMTS Networks. Wiley & Sons, LTD.

[3] J. Laiho, A. Wacker, T. Novosad, Radio Network Planning and Optimization for UMTS. Wiley & Sons, LTD.

[4] J. Lempiainen and M. Manninen, UMTS Radio Network Planning Optimization & QOS Management, Kluwer Academic Publishers, 2003.

[5] William C.Y. Lee, Mobile Cellular Telecommunications, 2nd ed., McGraw Hill, 1995.

[6] Kyoung Kim, Handbook of CDMA System Design, Engineering and Optimization, Prentice Hall, 2000.

[7] Walpole, Myers and Myers, Probability and Statistics for Engineers and Scientists. Prentice Hall.

[8] Downing and Clark, Statistics the Easy Way, Barron’s.

[9] Ed Williams, “Aviation Formulary V1.42,” http://williams.best.vwh.net/avform.htm

[10] Bill Walkowski, “Identifying the Culprits,” Wireless Review, January 15, 2001, http://www.wirelessreview.com/ar/wireless_identifying_culprits/

[11] Christophe Chevallier, Christopher Brunner, Andrea Garavaglia, Kevin P. Murray, and Kenneth R. Baker, editors. WCDMA (UMTS) Deployment Handbook, Wiley & Sons, Ltd., 2006. (ISBN-13: 978-0-470-03326-5) (ISBN-10: 0-470-03326-6)


1-8



Comments/Notes


2-1

80-W0242-4 Rev DWCDMA (UMTS) Inter-System Network Optimization WorkshopSection 2: Inter-System Continuity – Basic Considerations


Section 2-1



Inter-System Continuity

– Basic Considerations2SECTION

Section 2: Inter-System Continuity –Basic Considerations

Notes


2-2



Section 2-2



Section Learning Objectives

Define the basic inter-Radio Access Technology (inter-RAT, or IRAT) transitions for different connection modes (Idle, Connected CS, Connected PS).

Describe and understand the call flow for different inter-system transitions.

Define the two main techniques used to perform other RAT measurements and how they work.

Notes


2-3



Section 2-3



Inter-System Basics

• Terminology• Introduction to Inter-RAT• Use Cases• Transition Types• State Diagram• Inter-RAT or Inter-System Continuity

Notes


2-4



Section 2-4



Inter-System Basics (continued)

Basic inter-Radio Access Technology (inter-RAT) transitionsfor different modes (Idle, Connected CS, Connected PS)

• Inter-RAT enables service continuity:– In Idle Mode:

Cell Reselection (WCDMA GSM/GPRS)

– In CS domain:Handover (WCDMA GSM/GPRS)Handover not supported for Video telephony.

– In PS domain: (WCDMA GPRS)Cell Change Order (UMTS to GPRS/EDGE)Cell Reselection (Cell_FACH, Cell_PCH, URA_PCH)

– In PS domain: (WCDMA GPRS)Cell Reselection

Notes


2-5



Section 2-5



Inter-System Basics – Terminology

Inter-RAT (3GPP 25.331, 25.304, 25.214):• Cell Reselection / Handover / Change between UTRAN (WCDMA Radio

Access Network) and other Radio Access Technologies, such as GSM, GPRS, EDGE, and even UMTS TDD, CDMA2000 in the future.

• The term Inter-RAT is mainly used in reference to Radio Aspects.

Inter-System (3GPP 21.905, 23.009, 24.008):• Cell Reselection / Handover / Change between networks using different

radio systems, e.g., UMTS – GSM/GPRS.

• The term Inter-System is mainly used in reference to Signalling Aspects.

This workshop uses Inter-RAT and Inter-System interchangeably.This module focuses only on UMTS FDD GSM / GPRS / EDGE.

Handover, Service Continuity, and Inter-System Transitions

Additional information about service continuity requirements, for UTRAN to GERAN, UTRAN to UTRAN, and GERAN to UTRAN, as well as other possible RAN, can be found in:

22.129: Handover Requirements between UTRAN and GERAN or other Radio Systems

In this specification, service during inter-system handover is required to be as good as GERAN-to-GERAN handover. For PS data services, the main requirement is for the continuity of the PDP context.


2-6



Section 2-6



Inter-System Basics –Introduction to Inter-RAT

Why Inter-System?

• A WCDMA-to-GSM cell transition (reselection / handover / change) is useful at the edge of an WCDMA coverage area,for service continuity.

• Inter-RAT is also useful for extending WCDMA coverage indoors; such coverage is not yet readily available.

Notes


2-7



Section 2-7



Inter-System Basics – Use Cases

“3G to 2G” transitions can happen in the following scenarios:• Leaving contiguous WCDMA coverage, i.e., the border areas of WCDMA

and GSM coverage• Lack of indoor coverage within WCDMA network, i.e., less coverage depth

when compared to that of GSM• Load balance between WCDMA and GSM• Insufficient WCDMA coverage/capacity

“2G to 3G” is not considered as critical as “3G to 2G.”• 2G coverage is considered to be ubiquitous.• “2G to 3G” transitions are mainly beneficial in the PS domain, due to the

better data throughput possible with 3G technology.

Inter-RAT is not a way to fix Pilot Pollution or coverage hole problems within a WCDMA network.

Inter-System and Coverage Deficiency

In this workshop, we assume that the optimization of the inter-system transition is performed on an optimized WCDMA layer. With this in mind, inter-system optimization should not be expected to address the temporary coverage deficiencies due to missing sites, incomplete RF optimization, or the like. However, inter-system transitions due to WCDMA network borders and insufficient in-building coverage should be optimized.

The same idea would be true for areas where the WCDMA runs out of capacity; thus inter-system change would be necessary for call retention. The main issue with this approach is that inter-system measurements would be necessary over the entire area, with possible impacts on performance and capacity.


2-8



Section 2-8



Inter-System Basics – Transition Types

Network Initiated• Cell Change Order (CCO) to UTRAN• Cell Change Order (CCO) from UTRAN

Change / Cell Change Order (CCO)(3GPP TS25.331 8.3.10, 8.3.11 & TS04.18)

Network Initiated• Handover (HO) from UTRAN• Handover (HO) to UTRAN

Handover(3GPP TS25.331 8.3.6, 8.3.7 & TS05.08)

UE/MS Initiated • (except that GPRS mode also supports

Network Controlled Cell Reselection –see next section)

Cell Reselection(3GPP TS25.331 8.3.8, 8.3.9 & TS05.08)

Initiation3G 2G Transition Type

CCO to UTRAN

Although the CCO to UTRAN procedure is described in TS25.331, most current network implementations do not use this, because it would require an NC2 setting (NC0 typical). Instead, temporary suspension of data transfer followed by inter-system cell reselection is typically used.


2-9



Section 2-9



Inter-System Basics – State Diagram

GSMConnected

Mode

Camping on a UTRAN cellCamping on a GSM/GPRS cell

GPRS Packet Idle Mode

Release RRConnection

Establish RRConnection

Release RRCConnection

Establish RRCConnection

Release oftemporary block flow

Initiationof temporaryBlock flow

G-to-W Inter-System Handover

W-to- G Inter-System Handover

Cell Change OrderUTRA RRC

Connected ModeGPRSPacket

TransferModeCCO

Cell Reselection

CS Domain

PS Domain

Inter-System State Diagram

In Release 99, the following features are defined:

Reselection from WCDMA to GSM/GPRS/EDGE, when the UE is in Idle Mode or in a quasi-Idle Mode (Connected Cell_FACH, Cell_PCH, or URA_PCH).Reselection from GSM/GPRS/EDGE to WCDMA when the UE is either in Idle or Packet Idle Mode.Handover between WCDMA and GSM when the UE is in CS domain Connected Mode.Cell Change Order from WCDMA to GPRS/EDGE when the UE is in PS domain Connected (Cell_DCH) Mode.Suspension of data transfer, reselection from GPRS/EDGE to WCDMA, then resumption of data transfer when the UE is in PS domain Connected Mode.

Cell Change Order to UTRAN

Even though CCO-to-UTRAN is defined in 25.331 and 04.18, no handover process is defined, or implemented, in GSM/GRPS to allow for handover from GSM/GPRS to WCDMA in the PS domain. The supported CCO from GPRS to WCDMA cannot be considered a true handover, because the transfer of information is interrupted while the UE performs the cell change. This interruption degrades data throughput and affects the QoS. Because QoS is not maintained, this process cannot be considered a true handover.


2-10



Section 2-10



Inter-System Basics –Inter-RAT or Inter-System Continuity

Idle (CS/PS)• Inter-RAT or Inter-System transition via Cell Reselection.

AMR (CS Connected Cell_DCH State)• Inter-RAT or Inter-System transition via handover.

Video Telephony

• No Inter-RAT or Inter-System transition is possible for CS64 service, because there is no compatible service in GSM Release 99.

PS Data

• In PS Idle Mode or PS Connected Cell_FACH / Cell_PCH / URA_PCH states or GPRS Packet Idle Mode, Inter-System transition via Cell Reselection.

• In PS Connected Cell_DCH state or GPRS Packet Transfer Mode, Inter-System transition via Cell Change Order (but most existing systems support only W-to-G CCO).

• In GPRS Packet Transfer Mode, Inter-System transition can also be achieved via Cell Reselection after temporary data suspension.

In this workshop, an inter-system (or inter-RAT) handover applies only to the CS domain, while an inter-system change or cell change order applies to the PS domain.

A Location Area Update and/or Routing Area Update may occur after the Inter-System Reselection / Handover / Change.

Inter-RAT or Inter-System Continuity

Even though TS25.331 contains descriptions on Inter-RAT Cell Change Order to UTRAN, most systems do not support CCO from GPRS to WCDMA. Currently, Cell Change Orders (CCO) apply only in WCDMA-to-GSM/GPRS/EDGE transitions, when the UE is in PS domain. For GSM/GPRS/EDGE-to-WCDMA transitions in PS domain, the data session is first suspended with the UE going to Packet Idle Mode, then inter-RAT cell reselection takes place. After the reselection, the UE restarts the data sessions.


2-11



Section 2-11



Transitions and Terminals

• Blind Inter-RAT Transitions• Non-Blind Inter-RAT

Transitions• Single Receiver Terminals • Dual Receiver Terminals

Notes


2-12



Section 2-12



Transitions and Terminals (continued)

• Blind inter-RAT transition:– Simpler UE process but performance

is not guaranteed due to no measurement on the other RAT.

• Non-blind inter-RAT transition:– Offers better quality assurance

due to the availability of inter-RAT measurements but the UE process is more complicated.

• Single receiver terminals:– Are simpler but require Compressed

Mode measurements, which must be optimized.

• Dual receiver terminals:

– Do not require Compressed Mode measurements but are difficult/expensive to make.

Differences and performance trade-offs between blind and non-blind inter-RAT transitions, and between single and dual receiver terminals.

Notes


2-13



Section 2-13



Inter-RAT Blind Handover / Change• No measurement is performed on the other RAT before the

handover / change decision.

Inter-RAT Blind Handover / Change

GSM/GPRSWCDMA Cell_DCH

Inter-RAT HO/CCO Command?

Only WCDMAMeasurements

Network makes the handover or CCO decision based on UE-performed

WCDMA measurements only

Notes


2-14



Section 2-14



Inter-RAT Non-Blind Handover / Change –Dual Receiver Terminal

Inter-RAT Non-Blind Handover / Change• Dual receiver terminal

– Making measurements on the target RAT while continuously operating on the serving RAT



WCDMA and GSM/GPRS

Measurements


WCDMA and GSM/GPRS measurements

?

Notes


2-15



Section 2-15



Inter-RAT Non-Blind Handover / Change –Single Receiver Terminal

Inter-RAT Non-blind Handover / Change• Single receiver terminal

– Need to briefly suspend operation on the serving RAT to measure the target RAT Compressed Mode (CM)



WCDMA or GSM/GPRS

Measurements at one time


WCDMA and GSM/GPRS measurements

?

Notes


2-16



Section 2-16



Blind and Non-Blind Handover / Change

Blind Handover / Change• Low complexity – Does not require Compressed Mode or dual receiver.• Suitable for WCDMA Node Bs that are co-located with GSM Node Bs –

WCDMA-GSM boundaries can be easily estimated.• Potentially a long gap in the voice call due to no prior GSM measurements.• For non co-located WCDMA/GSM design, failure rate can be optimized only

in discrete locations.

Non-Blind Handover / Change• Better control – Eliminates guesswork when determining when and where to

do inter-RAT transition.• Quality assurance and higher success rate with measurements.• May require Compressed Mode (CM) measurements in Cell_DCH, which

adds to the complexity of the system and handsets.

Most implementations currently use Non-Blind Handover/CCO.

Blind Handover and Handover Success Rate

During blind handover, the UE and network do not know the actual target of the handover candidate. Therefore the handover must be directed to a single GSM cell, which may not be the ideal candidate for all positions within the cell. However, the handover can be optimized with a good success rate at a specific position, typically high traffic boundaries such as a highway or bridge. This optimized handover may fail in other locations, if the coverage of the WCDMA and GSM cell do not fully overlap.


2-17



Section 2-17



Single Receiver and Dual Receiver Terminal

Single Receiver Terminal• Simpler design.• Requires Compressed Mode (CM) measurement in Cell_DCH.

Dual Receiver Terminal• High cost and possibly bigger form factor due to two RF chains required.• Can perform inter-RAT measurements in parallel with normal call.• Complex to design, in particular considering the isolation requirements.

Most handsets are currently single receiver terminals, and optimization is required on the settings for CM measurements and inter-RAT transitions.

Isolation Requirement for Dual Receiver Handset

The main issue for the isolation requirement in a dual receiver handset is the frequency band used in UMTS and DCS.

The Uplink transmission in the UMTS band (1920~1980 MHz) is very close to the Downlink reception in the DCS 1800 band (1805~1880 MHz). Therefore, self-interference from the UE Uplink WCDMA transmission while making the GSM measurements is a concern.


2-18



Section 2-18



Transitions and Terminals – Summary

• Blind inter-RAT transition:– Simpler UE process, but

performance is not guaranteed due to no measurement on the other RAT.

• Non-blind inter-RAT transition:– Offers better quality assurance

due to the availability of inter-RAT measurements, but the UE process is more complicated.

• Single receiver terminals:– Are simpler, but require

Compressed Mode measurements, which must be optimized.

• Dual receiver terminals:– Do not require Compressed Mode

measurements, but are difficult/expensive to make.

Differences and performance trade-offs between blind and non-blind inter-RAT transitions, and between single and dual receiver terminals:

Notes


2-19



Section 2-19



Call Flow for Inter-System Transitions

• Objectives• Inter-RAT Handover (CS)

– 3G 2G Call Flow– 2G 3G Call Flow – 3G 2G Call Flow Example

• Inter-RAT Cell Change Order (PS)– 3G 2G Call Flow– 3G 2G Call Flow Example– 2G 3G Call Flow– 2G 3G Call Flow Example

• Summary

Notes


2-20



Section 2-20



Call Flow for Inter-System Transitions –Objectives

Call flow for different inter-system transitions

GERANor UTRAN

Multi-RATUE/MS

UTRANor GERAN

Serving RAN Target RAN

Optional Measurement Reporting

Optional Inter-System Transition Command if Network Initiated

Perform Inter-System Transition

Optional Measurements on either or both RAN

Inter-System Transition Message Flow

This slide depicts a simplified version of the various message flows for the inter-system transition. The actual flow depends on the following:

Which measurement is doneType of message that is sentType of transition and vendor implementation

The next section of this workshop covers detailed flows.


2-21



Section 2-21



Inter-RAT Handover (CS) –3G to 2G Call Flow

UE

1

2

3

4

GERANUTRAN

RRC: Measurement Report

RRC: Handover From UTRAN Command

Perform GSM Handover Sequence

RR: Handover Complete

(Optional)

UE

1

2

3

4

GERANUTRAN

RRC: Measurement Report

Handover Fails on the Target System

RRC: Handover From UTRAN Failure

(Optional)

3G to 2G HOSuccessful Case

3G to 2G HOFailure Case

RRC: Handover From UTRAN Command

3G to 2G Call Flow

During the call setup procedure, the UE notifies the UTRAN of its capabilities via the RRC ConnectionSetupComplete message, in response to RRC ConnectionSetup message. The UE sends a UE-RATSpecificCapability record that informs the UTRAN of the UE’s capability to support other radio access technologies (GSM, CDMA2000), as well as multi-carrier (DCS1800, GSM900), multi-mode (FDD, TDD), ciphering algorithm, integrity protection algorithm, positioning capability, Compressed Mode support for Uplink and Downlink, and RAT-specific capability (e.g., GSM Classmark support).

The UTRAN may control a measurement in the UE either by broadcast of system information and/or by transmitting a Measurement Control message. The UTRAN can order a UE to provide Inter-RAT measurement reports by specifying MeasurementType in the Measurement Control message. The Inter-RAT measurements are on Downlink physical channels belonging to radio access technology other than UTRAN, e.g., GSM. These measurements are made during Compressed Mode.

Upon reception of the handover from the UTRAN command message, the UE connects to the target radio access technology, GSM or CDMA2000, by using the contents of the Inter-RAT message. This Inter-RAT record contains a message specified in another standard, as indicated by the system type (GSM or CDMA2000), and carries information about the candidate / target cell identifier(s) and radio parameters relevant for the target radio access technology.

The Frequency Band is also specified when the System Type is set to GSM. The value of this Frequency Band could be either GSM/DCS 1800 Used or GSM/PCS 1900 Used.

The Handover from UTRAN command also includes Radio Access Bearer (RAB) Info information element. This information element uniquely identifies a radio access bearer within a CN domain. The RAB-Info identifies the Core Network (CN) domain which is set to GSM-MAP if the PLMN is GSM or ANSI-41 for handovers to ANSI-41 system. The CN (Core Network) value could be either CS (Circuit Switched) or PS (Packet Switched).

The Handover from UTRAN command also contains a re-establishment timer that indicates which timer to associate with RAB. Two timers can be specified: T314 or T315. Re-establishment timer T314 starts when the criteria for radio link failure are fulfilled. The timer is started if radio bearer(s) associated with T314 exist, or if only RRC connection exists. The default value for this timer is 180 seconds. The T315 re-establishment timer starts when the criteria for radio link failure are fulfilled. The timer is started only if radio bearer(s) associated with T315 exist. The default value for this timer is 180 seconds. When the T315 timer expires, the UE clears all stored variables and releases all its radio resources.

Upon successful completion of the handover, the UTRAN releases the radio connection and removes all context information for the concerned UE.


2-22



Section 2-22



Information Element Description

Inter-RAT handover failure

- Configuration unacceptable- Physical Channel Failure- Protocol Error- Inter-RAT Protocol Error- Unspecified

Handover from UTRAN Failure Cause

Inter-RAT Handover (CS) –3G to 2G Call Flow (continued)

Handover from UTRAN Failure

If the UE fails to connect to the target Radio Access Technology, it restores the old UTRA configuration and establishes the UTRA physical channel(s) used at the time for reception of handover from the UTRAN command. If the UE does not succeed in establishing the UTRA physical channel(s), it should perform a cell update procedure with a cause of “Radio link failure.” When the cell update procedure completes successfully, the UE transmits the handover from UTRAN failure message.

If the information element inter-RAT message received within the handover from UTRAN command message does not include a valid inter-RAT handover message in accordance with the protocol specifications for the target RAT, the UE sets the failure cause in the Handover from UTRAN failure message to “Inter-RAT protocol error.” This message is transmitted on the Uplink DCCH using AM RLC (Radio Link Control). After the transmission of the Handover from UTRAN failure message has been confirmed by RLC, the UE continues with any ongoing processes and procedures as if the invalid handover from UTRAN command message had never been received.


2-23



Section 2-23



Inter-RAT Handover (CS) –2G to 3G Call Flow

Handover triggers:• Orders – the GSM network orders the UE to handover

to UTRAN.• Conditions – the UE meets conditions or thresholds

pre-configured by the GSM network.

UE GSM

INTER SYSTEM HANDOVER TO UTRAN COMMAND

HANDOVER TO UTRAN COMPLETE

UTRAN

Security Procedure + Location and/or Routing Area Update

MS Measurement Reports

2G to 3G Call Flow

The handover to UTRAN procedure is always initiated by the network. The network initiates the handover to UTRAN procedure by sending an INTER SYSTEM TO UTRAN HANDOVER COMMAND message to the UE on the main DCCH. T3121 is also started at the same time. Upon receiving the handover to UTRAN command, the UE starts the release of link layer connections and disconnects the physical channels (including the packet resources, if in class A mode of operation).

After lower layer connections are successfully established on UTRAN, the UE returns a Handover to UTRAN Complete message on UTRAN channels(s); see 3GPP TS 25.331. Upon receiving the Handover to UTRAN Complete message (3GPP TS 25.331), the network stops timer T3121 and releases the old channels. If timer T3121 elapses before either the Handover to UTRAN Complete (3GPP TS 25.331) message is received on the UTRAN channel(s), or a HANDOVER FAILURE message is received on the old channels, or the UE has re-established the call, the old channels are released if they were dedicated channels and all contexts related to the connections with that UE are cleared.


2-24



Section 2-24



Inter-RAT Handover (CS) –2G to 3G Abnormal Cases

Inter-System Handover Failures (3GPP 04.18):• Frequency not implemented• UTRAN configuration unknown• Lower layer failures

Inter-System Handover Failures (3GPP 25.331):• Protocol error• Unsupported configuration• UE fails to perform handover

2G to 3G Abnormal Cases

If the UE is instructed to use a frequency it does not support, the UE stays on the current channel(s) and returns a HANDOVER FAILURE message with cause “frequency not implemented.”

If the UE is instructed to use a UTRAN-predefined configuration that the UE has not read, or is instructed to use a default configuration not implemented by the UE, the UE stays on the current channel(s) and returns a HANDOVER FAILURE message with the cause “UTRAN configuration unknown.”

If connection is not possible on the UTRAN channel(s) (see 3GPP TS 25.331), the UE reactivates the old channel(s), reconnects TCHs, and triggers the establishment of the main signalling link. It then sends a HANDOVER FAILURE message on the main signalling link and resumes normal operation.

When sending a HANDOVER FAILURE message in response to an INTER-SYSTEM TO UTRAN HANDOVER COMMAND, the UE erases all the UTRAN-predefined configurations.


2-25

80-W0242-4 Rev DWCDMA (UMTS) Inter-System Network Optimization Workshop

Section 2: Inter-System Continuity – Basic Considerations


Section 2-25



Inter-RAT Handover (CS) –Call Flow Example From 3G to 2G

Call Flow Example From 3G to 2G

In the Friendly Viewer screen above, the UE received a Handover from UTRAN command (timestamp: 18:38:03.637) and performed a 3G to 2G handover (completion timestamp: 18:38:03.776). Note the 2G system information received after the Handover Complete message:

System information types 5 and 5ter contain the BA list for UE measurements in Active Mode (c.f. SI type 2 for Idle Mode), and are sent on the SACCH; SACCH is the 13th frame in the middle of the multiframe.

System information type 6 contains the NCC permitted, cell identity, cell options and location area information – for the UE to perform location area updates when Location area identity (LAI) changes. System information type 6 is similar to system information type 3 (for Idle Mode), and is also sent on the SACCH (Active Mode).

Additional Information Observed in this Log

GPRS suspension request – No GPRS session was active at the time of the HO, but the suspend is required because the UE was registered in CS and PS domains.

WCDMA RRC States – The RRC connection in WCDMA is disconnected once the call is established in GSM (not shown for simplicity).

Various GSM states (RR, L2) – These states can help interpret the progress of the handover by reviewing the details of the message (not shown for simplicity).


2-26



Section 2-26



Inter-RAT Cell Change Order (PS) –3G to 2G Call Flow

3G to 2G COOSuccessful Case

3G to 2G COOFailure Case

3G to 2G CCO Failure

The CCO failure also could be due to the UE not being able to camp on the target GSM/GPRS cell. This type of failure was omitted from this diagram to simplify the illustration.


2-27



Section 2-27



Inter-RAT Cell Change Order (PS) –Handling Handover Failure

3G to 2G, from the standard:

• UE reverts to original RAT before sending the failure.– Call might drop at network edge if RF conditions have

degraded.

• UE restarts normal operation by reestablishing physical channels used before the Cell Change Order.– Network might re-initiate CM leading to handover from UTRAN.

• If the UE does not successfully get back on original RAT, the Cell Update procedure can help recover from the radio link failure.

Notes


2-28



Section 2-28



Inter-RAT Cell Change Order (PS) –3G to 2G Call Flow Example

3G to 2G Call Flow Example (PS CCO)

In the Friendly Viewer screen above, the UE received a Cell Change Order from UTRAN and performed a 3G to 2G cell change at 10:50:23.207.

Note the 2G system information received (starting from 10:50:23.602) after the CCO message:

The UE was in Packet Idle Mode after the cell change until the immediate assignment (RR Connection Establishment) at 10:50:25.170. Authentication was performed at 10:50:26.217 and ciphering started at 10:50:28.098. Location/routing area updates were done with Temporary Mobile Subscriber Identity (TMSI) reallocation at 10:50:28.57.


2-29



Section 2-29



Inter-RAT Cell Reselection (PS) –2G to 3G Call Flow

2G to 3G Cell Reselection (PS): Successful Case

UE GERANUTRAN

3Camped on UTRAN

Cell

SGSN

4RRC ConnectionEstablishment

2 Suspend Packet Data Services: Packet idle mode

1 Packet Data Transfer through GERAN

GMM: Service Request6

Cell Reselection

WCDMA Measurement

UTRAN Neighbor information

5 GMM Routing Area Update and Security Mode Command

Notes


2-30



Section 2-30



Inter-RAT Cell Reselection (PS) –2G to 3G Call Flow Example

2G to 3G Call Flow Example (PS Cell Reselection)

In this example, the PS packet data transfer was suspended (Packet Idle Mode) before reselecting to the 3G network: No signaling message is observed. After the transition, the UE should establish the RRC connection, then perform a routing area update. At that point, the UE could resume the packet session.


2-31



Section 2-31



Call Flow for Inter-System Changes –Summary

For Non-Blind Connected Mode (Cell_DCH) transitions from UTRAN, the UE must leave some gaps (not transmitting or receiving) for inter-RAT measurement. This requires Compressed Mode techniques.

Target RANGERAN

or UTRANMulti-RAT

UE/MSUTRAN

or GERAN

Serving RAN

Optional Measurement Reporting

Optional Inter-System Change Command if Network Initiated

Perform Inter-System Change

Optional Measurements on either or both RAN

Notes


2-32



Section 2-32



Inter-RAT Measurement in UMTS

• Inter-RAT measurement for Idle/Cell_PCH/URA_PCH

• Inter-RAT measurement for Cell-FACH • Inter-RAT measurement in GSM/GPRS• Inter-RAT measurement for Cell_DCH

– Compressed Mode (CM)– Overview– SF/2– HLS

Notes


2-33



Section 2-33



Inter-RAT Measurement in UMTS –Idle/Cell_PCH/URA_PCH Mode

• The UE wakes up only once every Discontinuous Reception (DRX) cycle.

• If no incoming page or page indicators are detected, the UE can perform all types of measurements before sleeping.

• Parameters:– DRX cycle length – instructs the UE how often it should wake up after DRX.

– SIB 3/4 – contains the measurement requirements and reselection parameters.

– SIB 11/12 – contains the Neighbor List Information.

Retuning in UTRA Idle Mode

More information about all the parameters involved during reselection can be found in 3GPP 25.304 §5.2.6.

CN DRX Cycle Length determines the frequency of paging occasions. The UE can monitor up to 32 intra-frequency WCDMA cells, up to 32 inter-frequency WCDMA cells, and up to 32 inter-RAT cells (GSM neighbors). The UE can read the Base Station Identification Code (BSIC) of the four strongest GSM cells every 30 seconds.UTRAN sets the inter-RAT cell reselection parameters in SIB3 (Idle Mode) / SIB4 (Connected Mode) and SIB11 (Idle Mode) / SIB12 (Connected Mode).SIB3/SIB4 conveys the triggering condition for inter-RAT measurements in addition to the other cell reselection parameters.SIB11/SIB12 conveys the inter-RAT (GSM/GPRS) neighbors and the related parameters (BSIC, ARFCN, required minimum RSSI).


2-34



Section 2-34



Inter-RAT Measurement in UMTS –Cell_FACH Mode

• UE is active all the time during Cell_FACH.

• FACH Measurement Occasions are signaled to the UE.

• Parameters:– SIB11/12 – contains the FACH Measurement occasion cycle length

coefficient and the Neighbor List(s).

– SIB 3/4 – contains the measurement requirements and reselection parameters.

Retuning in UTRA Cell_FACH StateFACH measurement occasions are defined in 25.331 §8.5.11. The occurrence of measurement occasions is defined by the following formula:

SFN div N = C_RNTI mod M_REP + n * M_REPWhere:

N is the TTI (in number of 10 ms frames) of the FACH having the largest TTI on the SCCPCH monitored by UE.C_RNTI is the C-RNTI value of the UE stored in the variable C_RNTI.M_REP is the Measurement Occasion cycle length. According to the equation above, a FACH Measurement Occasion of N frames will be repeated every N * M_REP frame, and M_REP = 2k, where:

– k is the FACH Measurement occasion cycle length coefficient.The value of the FACH Measurement occasion cycle length coefficient is read in System Information Block type 11 or System Information Block type 12 in the IE “FACH measurement occasion info.”

– n = 0,1,2… as long as SFN is below its maximum value.The UE is allowed to measure on other occasions in case the UE moves to an “out of service”area or in case it can simultaneously perform the ordered measurements.Note that filtering shall not be performed for the measurements reported in the IE Measured results on RACH and for cell-reselection in Connected or Idle Mode (TS25.331 §8.6.7.2).


2-35



Section 2-35



Inter-RAT Measurement in GSM/GPRS

• In Idle Mode, the UE can make measurements when listening to its Paging subchannel after waking up from the DRX cycle.

• In Active Mode, the UE can measure the signal strength on the serving cell on the Downlink during the Rx timeslot(s) in every TDMA frame.

• The UE can perform signal strength measurements on other cells between the Tx and Rx timeslots.

• Parameters:– SI2_quater and PSI3_quater (PS) – contains the inter-RAT measurement

requirements and reselection parameters

Rx Tx Rx1 Timeslot~0.577 ms

Signal Level Measurement On the Neighbor Cells

1 TDMA Frame~4.62 ms

Retuning in GSM/GPRS (TS05.08 10.1.1.2)

The UE continuously monitors all BCCH carriers, as indicated by the BCCH Allocation (BA) list and the BCCH carrier of the serving cell. In every TDMA frame (active), or when the UE wakes up after a DRX cycle to listen to the paging group (idle), a received signal level measurement sample is taken on at least one of the BCCH carriers, and so on. When 3G cells are specified in the search list, the UE also makes measurements on these 3G cells during the search time.


2-36



Section 2-36



Inter-RAT Measurement in UMTS –Compressed Mode (CM): Overview

CM creates time gaps during normal WCDMA DL and UL radio frame transmission to allow the UE to tune to a different frequency and measure other GSM/GPRS cells.

• The network uses these measurements to decide whether the UE should perform a handover/change to neighboring Inter-RAT cell (UE-assisted handover/change).

• Generally this will be triggered at the edge of WCDMA coverage.• CM also is used for WCDMA inter-frequency measurements.

There are two main types of CM:1. CM by Spreading Factor (SF) Reduction (commonly used for

AMR voice and PS data – UL & DL)2. CM by Higher Layer Scheduling (HLS) (for PS data only – UL & DL)

Compressed Mode Types

Although CM by Spreading Factor reduction (SF/2) is typically used for AMR voice, it can also be used for PS data to maximize throughput and minimize delay (no limitation of the TFCS compared to HLS).

Higher Layer Scheduling (HLS) can only be used for PS data, due to the delay incurred when TFCS is limited.

There was a third type of CM, puncturing, initially specified by the standard in R99. It is specified for Downlink only. However, puncturing has not been seen deployed in current network implementations. It is not commonly supported by the handset either, due to large MIPS requirements. This type of CM operation has been now removed from the UMTS standard.


2-37



Section 2-37



Inter-RAT Measurement in UMTS –Compressed Mode (CM)

• The UE is active at all times in Cell_DCH.

• The network must create the measurement Opportunities: via Compressed Mode (CM).

• Parameters are required for:– Timing the measurement opportunities

– Repeating the measurement opportunities

– Handling the data stream: Compressed Mode techniques

Notes


2-38



Section 2-38



Inter-RAT Measurement in UMTS –Compressed Mode: Comparing SF/2 and HLS

SF/2: HLS:

One frame(10 ms) Transmission gap available for

inter-frequency measurements

One frame(10 ms)

No Gap

Decrease SFIncrease Data RateIncrease Transmit Power



One frame(10 ms)

No Gap

Rearrange & repack PS data

Restrict TFC so as not to fill all frames

Higher Layer Scheduling

Higher Layer Scheduling transmits less data over a given slot, rather than using lower SF to send the same required amount of data over less time (fewer slots).

The higher layer (above RLC) reduces the amount of data. With less data sent by the MAC layer, fewer transport blocks are sent in a given TTI. Without changing the slot format, with fewer transport blocks to send, the number of active slots during a frame can be reduced and selected slots can be blanked and used for inter-system measurements.


2-39



Section 2-39



Inter-RAT Measurement in UMTS – Compressed Mode: SF/2 Compressed Frame Characteristics

• In the compressed frames, no information bit is transmitted during the transmission gaps; the data rate before and after each gap must be increased to carry the data bits that cannot be sent during the gaps.

– No delay or loss in throughput (suitable for delay-sensitive applications like AMR voice)

• The instantaneous transmit power is increased in the compressed frames, to maintain quality while reducing processing gain (using SF/2).

– Frequent CM frames would lead to frequent occurrences of increased transmit power, which would result in increased interference and reduced network capacity.

– Code tree limitation may result when using lower SF codes. This method cannot be usedif the existing SF = 4.


Increased data rate and transmit power


Power Control and CM SF/2

For CM SF/2, the transmit power is not directly increased. Instead, the SIR target, either DL or UL, is increased. This increase is 3 dB, plus any additional increased signal by deltaSIR1, deltaSIR1after, deltaSIR2, and deltaSIR2after.

For details on the SIR increase or power control during Compressed Mode, see 25.311 §14.9.3 and 25.214 §5.1.2.3.


2-40



Section 2-40



Inter-RAT Measurement in UMTS – Compressed Mode (CM): HLS Frame Characteristics

• Just as for SF/2, no information bit is transmitted during the transmission gaps; data throughput is restricted (via restricting TFC) to allow data rearrangement and packing to create gaps for measurements. – Loss in throughput and additional delay when information data queues up at

the transport and/or higher layers (i.e., not suitable for Circuit Switched data applications).

• There is no change to the transmit power or the processing gain in the HLS frames.– No impact on the interference level and network capacity.– No requirement for more OVSF code tree usage.



Power Control and CM HLS

For CM by HLS, the SIR target increases only in the case of positive DeltaSIR.


2-41



Section 2-41



Inter-RAT Measurement in UMTS – Summary

Main Inter-RAT measurements techniques in UMTS:

• Inter-RAT Measurement in Idle/Cell_PCH/URA_PCH/Cell_FACH

• Compressed Mode via Spreading Factor Reduction by 2 (CM SF/2)– Can be applied in the CS or PS domains.

– Transmission gaps are created by sending the data that should betransmitted in the gaps in the prior and subsequent radio time slots. Consequently, spreading factor and data rate must be doubled momentarily.

• Compressed Mode via Higher Layer Scheduling (CM HLS)– Can be applied in the PS domain only.

– Transmission gaps are created by reducing the amount of data sent.

Notes


2-42



Section 2-42



Inter-RAT Measurement in UMTS – Summary (continued)

CM SF/2 versus CM HLS

• SF/2 and HLS can be used for different applications:– SF/2 for CS and PS domains, while

– HLS for the PS domain only

• For either method, Compressed Mode measurement affects performance on the current services. Therefore, use CM measurement only when absolutely necessary. The following must be defined:– CM configuration mechanism

– CM activation and deactivation mechanism

– Inter-RAT transition mechanism

When is Compressed Mode Necessary?

To limit its effects on performance, use CM only when absolutely necessary. Assess the need for CM initially based on the network plan, then review during the early stages of network optimization.

During network planning, consider the edge of the network where service continuity can be ensured only if inter-system changes are allowed. In this case, the network edge can be defined at the periphery of the area where UMTS service is available, or in-building, if no UMTS in-building coverage solutions are available. If, during optimization, an inter-system change is deemed necessary within the UMTS coverage area to compensate for the lack of coverage or performance, use events to delay activation of CM as much as possible.


2-43



Section 2-43



Inter-System Continuity:Basic Considerations – What Did We Learn?

What are the basics of inter-Radio Access Technology (Inter-RAT)?

– What is different in the various modes (Idle, URA_PCH, Cell_PCH, FACH Connected CS, Connected PS)?

How does the call flow differ for different inter-system transitions?

What are the main techniques used to perform other RAT measurements and how do they work?

Notes


2-44



Comments/Notes


WCDMA (UMTS) Inter-System Network Optimization Workshop

3-1

Section 3: Overview of IRAT Issues in UMTS Networks80-W0242-4 Rev D



Section 3-1


3SECTION

Overview of IRAT Issues in UMTS Networks

Section 3: Overview of IRAT Issues in UMTS Networks

Notes



3-2




Section 3-2



Determine how to isolate and identify IRAT issues.

List guidelines on data collection to troubleshoot IRAT issues.

Describe common IRAT issues in UMTS networks.

List recommended solutions to address these issues.

Notes



3-3




Section 3-3


General Approach to Address Issues

• Identify the cells serving the locations where issues are reported.

• Verify that these cells are radiating and there are no hardware faults/alarm reports.

• Monitor the Network Performance Counters and look at the following statistics:

– RAU/ LAU Failure Rate on WCDMA border cells– IRAT Handover Failure Rate– Low Call Setup Success Rate on WCDMA border cells – High Call Drop Rate on WCDMA border cells – Ratio of RRC Connection Request due to “Inter-RAT reselection”/Total RRC Connection

Request– Compressed Mode Success Rate

• If these statistics are all normal:– Collect UE and scanner logs around the problem areas.

Also enable network IMSI/RNTI traces to debug problem.– Post-process UE and Scanner logs to debug issues.– Recommend and implement solutions to address the issues.

Notes



3-4




Section 3-4


Identify IRAT Issues Using Network Performance Counters

Notes



3-5




Section 3-5


• Data Collection hardware/equipment:– UE, Pilot scanner, GPS receiver, etc.

• Data Collection software:– QXDM, CAIT,TEMS, Agilent, others

• Data Post-Processing tools:– Actix, TEMS, QC Friendly Viewer

• Data Collection Test Setup & Procedure

Data Collection and Post-Processing Tools Overview

Notes



3-6




Section 3-6


Pilot Scanner• UMTS scanner, e.g., Agilent E7476A with GPS receiver.

• Collect Ec/No and RSCP measurements of detectable PSCs for various cells.

UE• Collect signaling protocol messages and RF measurements (PSCs, Ec/No, RSCP,

Tx Power, DL BLER, etc.).

• Use a commercial UE with appropriate logging software (QUALCOMM QXDM/CAIT, TEMS, Agilent’s Nitro).

GPS Receiver• Used to collect instantaneous latitude and longitude information along the drive

route.• Timing information to sync various devices and UE/NW logs.

Data Collection Hardware

Notes



3-7




Section 3-7


Data Collection Software

For UE logging, TEMS/Agilent software also could be used, instead of QXDM/CAIT.

Notes



3-8




Section 3-8


Data Collection Setup (UE and Scanner)

For UE logging, TEMS/Agilent software also could be used, instead of QXDM/CAIT.

Notes



3-9




Section 3-9


Data Collection Procedure

1. Set the UE in Automatic (WCDMA + GSM) mode registered in both CS and PS domain; this reflects user experience.

2. Start scanner logging.

3. Start UE logging and start driving the test van around the problem areas.

– Idle test to address the inter-RAT cell reselection issues

– Long AMR test to troubleshoot the inter-RAT handover issues

– PS data call (with FTP) to address the PS data continuity issues at the inter-RAT boundary

4. Save the UE and scanner logs upon completion of data collection.

5. If needed, enable 3G and 2G network IMSI traces to further debug IRAT issues.

Notes



3-10




Section 3-10


Impact of RF Issues on Inter-RAT Performance

Inter-RAT performance is aggravated by unresolved RF issues.• Non-optimized RF environments often cause Neighbor List issues, resulting in wrong

or missing target cell.– Overshooting cells may provide incorrect information on location.– Event 2d could be triggered (not intended) due to bad RF in non-boundary areas.

• Frequent changes in Active Set cause delay of inter-system reselections and handovers.

– Large number of MRMs.– RNCs typically favor intra-frequency handover processing over inter-RAT processing.

• Unnecessary activation of Compressed Mode– Late trigger of Event e1a (missing strong neighbor) could unnecessarily trigger Event 2d, leading to

Compressed Mode activation.

• Absence of a clear boundary (single W to single G) increases ping-pong, which has detrimental effects on UE battery life and user experience.

Some operators resort to Inter-RAT as a means of fixing Pilot pollution and coverage holes in WCDMA network.

• RF issues should be resolved through RF optimization, not through parameter /NL tuning.

Notes



3-11




Section 3-11


3G ↔ 2G reselection ping-pong in WCDMA border area• Non-optimized IRAT cell reselection parameters

• Non-clean IRAT RF boundary

UE lost service before W2G cell reselection• Non-optimized W2G cell reselection parameters

• UE camping on overshooting 3G Cell, which does not have proper GSM Neighbor List in intended area

Common Issues During IRAT Transition

Notes



3-12




Section 3-12


Call Drop before / during Compressed Mode (CM)• Non-optimized IRAT parameter settings

– Too-late CM activation

Low Ec/No or RSCP causes high Block Error Rate (BLER)

– Too-late “Event3a” triggerCM was activated, but “Event3a” triggered too late

Call Drop due to WCDMA Neighbor List problems• Missing WCDMA neighbors, unnecessary CM activation

Call Drop due to UL/DL Link imbalance• Poor Uplink leads to UE maximum power while Downlink BLER is good

– UL Interference

– Different CPICH powers for different cells

Common Issues During IRAT Transition (continued)

Notes



3-13




Section 3-13


Call Drop due to fast variation & degradation of Ec/No during outdoor / indoor transition

• Frequent activation and deactivation of Compressed Mode.• UE does not have enough time in Compressed Mode to trigger “Event3A.”

Call Drop due to 2G Neighbor List problems• If the BSIC of the GSM cell in Neighbor Cell List sent to UE does not match OTA

BSIC, then the UE would not trigger Event3A for that GSM cell even though it may be the dominant 2G server for that area.

Call Drop in edge of coverage • Ec/No degrades very slowly in unloaded network and no RSCP-based CM trigger

setting.

Call Drop due to “HOfromUTRANcommand” to the wrong GSM cell• Resulting in Call drop in GSM after successful GSM (blind) Handover

– Index Replacement problem in R99 is fixed in R5. Allows correct GSM cell identification

Common Issues During IRAT Transition (continued)

Common Issues During IRAT Transition

CR number 2492 (TS 25.331) for Index Replacement problem in R99 is fixed in R5 and would allow correct GSM cell identification.

Reasons for Failure

This was a hole in R99 specification because GSM cells are referred to by “Cell Index” only in Event Reporting. This hole in the standard has been fixed in the Rel5 specifications by introducing a version ID in MCM and MRM for Inter-RAT measurement.



3-14




Section 3-14


Recommended Solution to Address IRAT Issues

• 3G ↔ 2G reselection ping-pong– Verify the following IRAT cell reselection parameters:

Qrxlevmin, Qqualmin, SsearchRAT, Treselection, and FDD_Qmin.

– Ensure a clean IRAT RF boundary.

• UE Lost Service before W2G cell reselection– Verify W2G Cell reselection parameters.

– Verify whether the UE camped on an Overshooting 3G Cell, which does not have proper GSM Neighbor List in test area. RF optimization is the best way to solve an overshooting cell.

Notes



3-15




Section 3-15


For IRAT Handover/ CCO Failure, verify the following:Are system parameters for Events e2d/e2f and e3a set properly?

Were e2d/e3a events triggered in time?• DL/UL BLER, and UE Tx power was not too high.

Are correct GSM cells included in the NL?

Did the UE report the expected GSM cell in e3a?

Was the IRAT preparation phase successful?• Target GSM cell was not blocked/congested and resources were allocated.

Did the UE receive the “HO from URTAN command” for the correct GSM cell?• IRAT execution phase was successful.

Did the UE acquire the target GSM cell?• GSM cell coverage was not very poor/did not have high interference.

Did the UE come back to the old WCDMA cell if it could not acquire the GSM cell?

Recommended Solution to Address IRAT Issues (continued)

Notes



3-16




Section 3-16


Recommended Solution to Address IRAT Issues (continued)

• Low call success rate (system accessibility) in known WCDMA border area:– Verify Qrxlevmin, Qqualmin, Sintrasearch, and SsearchRAT parameters.

• High call drop rate in WCDMA border area:– Verify CM parameters.

• High ratio of RRC Connection Requests due to Inter-RAT reselection / total number of RRC Connection Requests:– Verify Qrxlevmin, Qqualmin, Sintrasearch, SsearchRAT, FDD_Qmin,

FDD_Qoffset, and FDD_RSCPmin parameters.

• Low Compressed Mode success rate:– Verify GSM Neighbor List and CM parameters.

• Large number of Compressed Mode activations within WCDMA polygon:– Verify WCDMA Neighbor List and CM parameters.– Determine if there is a WCDMA coverage hole in test area.

Notes



3-17




Section 3-17


Overview of IRAT Issues in UMTS Networks –What Did We Learn?

How can we isolate and identify IRAT issues?

What guidelines can we follow for data collection and post-processing to identify the causes of issues?

What are some common causes of IRAT issues?

What solutions are recommended to solve issues based on typical failure signatures?

What Did We Learn?

To isolate and identify IRAT issues, use network performance counters as a starting point to identify outlying cells, then drill down.



3-18



Comments/Notes


4-1

80-W0242-4 Rev DWCDMA (UMTS) Inter-System Network Optimization WorkshopSection 4: Inter-System Continuity – Configuration and Parameter Settings


Section 4-1



Section 4: Inter-System Continuity –Configuration and Parameter Settings

Inter-System Continuity – Configuration and Parameter Settings4

SECTION

Notes


4-2



Section 4-2




Review the algorithms and related parameters for inter-RAT cell reselection.

Describe the typical Compressed Mode and inter-RAT transition mechanisms.

Additional Parameter Details

More details on system parameters listed here are available in the following QUALCOMM document: WCDMA Parameter Setting Guidelines (80-W0028-1). Please refer to the latest revision of this document for the most current recommendations.


4-3



Section 4-3



Algorithms and Parametersfor Inter-RAT Cell Reselection

• 3G: UTRA Idle, Cell_FACH, Cell_PCH / URA_PCH states– UE initiated

• 2G: GSM Idle Mode– UE initiated

• 2.5G: GPRS Packet Idle and Packet Transfer Modes– UE initiated

– Possibly network directed in Packet Transfer Mode, depending on the Network_Control_Order

Notes


4-4



Section 4-4



UTRAN to GERAN Cell Reselection

Squal = Qqualmeas – QqualminSrxlev = Qrxlevmeas – Qrxlevmin

– PcompensationSqual > 0, Srxlev > 0 suitable cellBut Qqualmeas < Qqualmin +

SsearchRAT GSM

Srxlev = Qrxlevmeas – Qrxlevmin– Pcompensation

Srxlev > 0 suitable cellQrxlevmeas GSM – Qoffset >

Qrxlevmeas WCDMA + QhystCheck 1 second reselection timerCheck if condition persists for TreselectionCheck cell belongs to registered PLMNCheck cell is not barredCheck location area is not forbiddenReselect to GSM/GPRS!Attach to GSM/GPRS Core Network

Inter-System Cell Reselection from UTRAN to GERANDuring Idle Mode, the UE wakes up to monitor for potential incoming pages, according to its DRX cycle. If no paging is detected, the UE performs intra-frequency, inter-frequency, or inter-system reselection measurements. All types of reselections follow a similar process, but the parameters involved are different. See 3GPP 25.304 §5.2.6 for information on reselection parameters.The UE can monitor up to 32 intra-frequency WCDMA cells (including the serving cell), up to 32 inter-frequency WCDMA cells (up to 2 additional carriers), and up to 32 inter-RAT cells (GSM neighbors).UTRAN sets the inter-RAT cell reselection parameters in:

SIB3 (Idle Mode) / SIB4 (Connected Mode) – SIB3/SIB4 convey the triggering condition for inter-RAT measurements, in addition to other cell reselection parameters.SIB11 (Idle Mode) / SIB12 (Connected Mode) – SIB11/SIB12 convey the inter-RAT (GSM/GPRS) neighbors and related parameters (BSIC, ARFCN, required minimum RSSI).

The UE shall measure the signal level of each GSM neighbor cell indicated in the measurement control system information of the serving cell, according to the measurement rules defined in TS25.304, at least every TmeasureGSM. The UE shall maintain a running average of 4 measurements for each cell. The measurement samples for each cell shall as far as possible be uniformly distributed over the averaging period.The UE shall attempt to verify the BSIC for each of the 4 best ranked GSM BCCH carriers (the best ranked according to the cell reselection criteria defined in TS25.304) at least every 30 seconds, if GSM cells are measured according to the measurement rules.Additional information on Idle Mode procedure and multi-mode UE can be found in:

21.910: Multi-mode UE issues Categories, principles and procedures.25.304: UE procedures in Idle Mode and procedures for cell reselection in Connected Mode.25.133: Requirements for support of radio resource management.


4-5



Section 4-5



Inter-RAT Scenarios

Q-1 – Edge of a WCDMA coverage area (e.g., border of the WCDMA PLMN)

Q-2 – Inside a WCDMA coverage area (e.g., small/occasional WCDMA coverage holes, poor WCDMA coverage indoors)

GSM/GPRS

WCDMA

Q1Q2

Notes


4-6



Section 4-6



UTRAN to GERAN Cell Reselection Parameters

-113 dBm-57-111 dBm-56Qrxlevmin

-18 dB-18-16 dB-16Qqualmin

2 dB12 dB1Ssearch RAT

WCDMA to GSM cell

reselection

Eng. valueIE valueEng. valueIE value

Q-2Q-1I-RAT Scenario

UTRAN to GERAN Cell Reselection ParametersQqualmin – Minimum quality level in the cell expressed in terms of CPICH Ec/No (–24…0 => –24 … 0 dB).

Setting Trade-off: If set too small, the UE may camp on a cell with very low quality, unable to receive reliable service. If the parameter is too large, the UE will prematurely declare the cell unsuitable and may unnecessarily select another PLMN. If no other PLMN or RAT is available, a lower value may be chosen, since there is no alternative network with better quality.

Qrxlevmin – Minimum quality level in the cell expressed in terms of CPICH RSCP (–58…–13 => –115…–25 dBm).

Setting Trade-off: If set too low, the UE may camp on a cell with very low quality, unable to receive reliable service. If set too high, the UE will prematurely declare the cell unsuitable and may unnecessarily select another PLMN.

Ssearch,RAT – RAT-specific threshold provided by the serving cell and applied to the inter-RAT measurement rules (–16 … +10 => –32...20 dB).

Setting Trade-off: If set too small, the UE will not perform inter-RAT measurements and may miss the opportunity to perform cell reselection to another RAT. If set is too large, the UE will perform inter-RAT measurements very often, most likely leading to unnecessary GSM reselections. Set values such that Sintrasearch > Sintersearch > Ssearch,RAT. The choice of Ssearch RAT = 2 dB for Q1 and Q2 is based on the assumption of avoiding OOS or service interruption (i.e., PS calls in cell_FACH) at the border and indoors. FDD_Qmin and Ssearch RAT values are chosen such that [Qqualmin( = –16 dB) + SsearchRAT], corresponding to CPICH Ec/No trigger value for W to G reselection, is always 2 dB less than FDD_Qmin, in order to avoid ping-pong effects.


4-7



Section 4-7



UTRAN to GERAN Cell Reselection Parameters (continued)

Parameter Recommended Value

Qhyst 2 dB

Qoffset 3 dB (if neighboring cell belongs to different PLMN, RAT, or location area)

Treselection 1 second

UTRAN to GERAN Cell Reselection Parameters (continued)Qhyst – Hysteresis value in the cell ranking criteria for cell reselection when CPICH RSCP is used (0…20 => 0 … 40 dB).

Setting Trade-off: If set too small, the UE may perform frequent cell reselection to cells only marginally better than the current serving cell, which may lead to excessive battery consumption. If set too large, the UE may camp on a relatively weak cell when a significantly better cell is available.

Qoffset – Offset between two cells in the cell ranking criteria for cell reselection when CPICH RSCP is used (Qoffset1s) or when CPICH EC/N0 is used (Qoffset2s) (–50…50 => –50 … 50).

Setting Trade-off: A positive value of Qoffest deters the UE from camping on that cell. If the parameter is set too low, the UE might not be deterred enough from camping on that cell. If the parameter is set too high, the UE may never observe the criteria required to camp on the cell. If applied to all cells in the PLMN, this parameter can be used to adjust the hysteresis in 1 dB increments; whereas Qhyst only allows for adjustments in 2 dB increments. Same trade-offs as for Qhyst.

Treselection – Cell reselection timer value (0…31 => 0…31 s).

Setting Trade-off: If set too large, the UE may camp on a relatively weak cell when a significantly better cell is available, or it may suffer an outage if a neighboring cell has rising CPICH.


4-8



Section 4-8



GSM to UTRAN Cell Reselection (Idle Mode)

Reselection criteria (for a period of 5 sec)RSCP > RLA_C (serving / non-serving) +

FDD_Qoffset ANDEc/No >= FDD_Qmin (default: –12 dB) ANDRSCP >= FDD_RSCP_Threshold (if supported)

5 dB Hysteresis if < 15 sec from previous Reselection

Ping-pong is not allowed within 5 seconds.Reselect to WCDMA!Attach to WCDMA Core Network.

3G_SEARCH_PRIO = 1 (3G cells may be prioritized)Search for 3G if RLA_C < Qsearch_I (7 – always)3G Cell Reselection list contains UTRAN freqsFDD: Up to 3 FDD frequencies

32 cells per frequencyUE monitors serving GSM cell and at least 6

strongest non-serving GSM cells and checks against the FDD cells.

Inter-System Cell Reselection from GSM to UTRAN (TS03.22 and TS05.08)The mobile shall be able to identify and select a new best UTRAN cell on a frequency, which is part of the 3G Cell Reselection list, within 30 seconds after it has been activated, if there is only one UTRAN frequency in the list and radio conditions are good. The allowed time is increased by 30 seconds for each additional UTRAN frequency in the 3G Cell Reselection List. However, multiple UTRAN cells on the same frequency in the list do not increase the allowed time.A multi-RAT mobile shall be able to monitor 64 UTRAN cells, divided into (depending on the MS capability):

FDD cells on up to 3 FDD frequencies, with a maximum of 32 cells per frequency, and/orTDD cells on up to 3 TDD frequencies, with a maximum of 32 cells per frequency.

In case of a conflict with GSM tasks, the GSM tasks take precedence.At least every five seconds, the mobile shall update the value of RLA_C for the serving GSM cell and each of the at least six strongest non-serving GSM cells. At the same time, the mobile must monitor the FDD cells in the 3G Cell Reselection List.If more than one UTRAN cell fulfills the cell reselection criteria, the mobile shall select the cellwith the greatest RSCP value.FDD_RSCP_Threshold is recently introduced in the standard. According to TS45.008 (Release 5), the FDD_RSCP_Threshold is defined as FDD_RSCPmin – min((P_MAX – 21 dBm), 3 dB) if FDD_RSCPmin is broadcast on the serving GSM cell, or Qrxlevmin + Pcompensation + 10 dB, if these parameters are available, otherwise the default value of FDD_RSCPmin (–102 dBm).


4-9



Section 4-9



GPRS/EDGE to UTRAN Cell Reselection ListWith or Without PBCCH

• System information broadcast

• UE dedicated information

In a cell without a PBCCH allocated – The GPRS 3G Cell Reselection list is the union of 3G Cells provided in one or more instances of system information message type 2ter and/or 2quater (5ter on SACCH in Active Mode).

In a cell with a PBCCH allocated – The GPRS 3G Cell Reselection list is the union of 3G Cells and/or 3G frequencies provided in one or more instances of the PSI3quater message.

Inter-RAT cell reselection to UTRAN (3GPP 25.304):

Notes


4-10



Section 4-10



GPRS to UTRAN Cell Reselection(GPRS Mode with PBCCH)

Reselection criteria (for a period of 5 sec):RSCP > RLA_P (serving / non-serving) +

FDD_GPRS_Qoffset ANDEc/No >= FDD_Qmin (default: –12 dB) ANDRSCP >= FDD_RSCP_Threshold (if supported)

5 dB Hysteresis if <15 sec from previous reselectionPing-pong is not allowed within 5 seconds.Reselect to WCDMA!Attach to WCDMA Core Network.

3G_SEARCH_PRIO = 1 (3G cells may be searched)

Initiation for search:Search for 3G if RLA_P < Qsearch_P(7 –

always)3G Cell Reselection list contains UTRAN

freqsFDD: Up to 3 FDD frequencies

32 cells per frequencyUE monitors serving GSM cell and at least 6

strongest non-serving GSM cells and checks against the FDD cells.

Inter-System Cell Reselection from GPRS to UTRAN (TS05.08 §10.1.1.3, §10.1.3.2)For a multi-RAT mobile, cells or frequencies with other radio access technologies may be included in the GPRS 3G Cell Reselection List to be monitored. If the GPRS 3G Cell Reselection List includes UTRAN frequencies, the mobile shall, at least every 5 seconds, update the value RLA_P for the serving cell and each of the at least six strongest non-serving GSM cells. The 3G Cell Reselection List can be modified by Packet Measurement Order or Packet Cell Change Order messages. The network controls the measurements for reselection of those cells by the Qsearch_P broadcast parameter on PBCCH. For this monitoring, the mobile may use search frames that are not required for BSIC decoding or interference measurements in Packet Transfer Mode. In Packet Transfer Mode, the mobile shall be able to send the first access 10 + x seconds (at the latest) after a new best UTRAN cell has been activated, assuming there is only one UTRAN frequency in the list, no new GSM cells are activated at the same time, and radio conditions are good. x is the longest time allocated to receive the necessary system information in the new cell. This is extended by 5 seconds for each additional UTRAN frequency in the GPRS 3G Cell Reselection list, and by the time required for BSIC decoding of new activated GSM cells. In Packet Idle Mode, the mobile shall be able to identify and select a new best UTRAN cell on a frequency within 30 seconds after it has been activated, provided there is only one UTRAN frequency in the list and radio conditions are good. FDD_RSCP_Threshold is recently introduced in the standard. According to TS45.008 (Release 5), the FDD_RSCP_Threshold is defined as FDD_RSCPmin – min((P_MAX – 21 dBm), 3 dB) if FDD_RSCPmin is broadcast on the serving GSM cell, or Qrxlevmin + Pcompensation + 10 dB, if these parameters are available, otherwise the default value of FDD_RSCPmin (–102 dBm).


4-11



Section 4-11



GERAN to UTRAN Cell Reselection Parameters


3G_SEARCH_PRIO depending on scenario (see next slide)

QSearch_P (PS) 7 = ∞ (always)

Qsearch_I (Idle) 7 = ∞ (always)

FDD_Qoffset 0 = – ∞ (always)

FDD_GPRS_Qoffset 0 = – ∞ (always)

FDD_RSCP_threshold = Qrxlevmin + Pcompensation + 10 dB; these parameters can be optionallyretrieved by the UE, otherwise FDD_RSCP_threshold = -∞(criterion not effective)

GERAN to UTRAN Cell Reselection Parameters

3G_Search_Prio – Indicates if 3G cells may be searched when BSIC decoding is required (0 = no, 1 = yes).

Setting Trade-off: If set to 0, the UE gives higher priority to GSM BSIC decoding. If set to 1, UE applies higher priority to UTRAN FDD measurements.

QSearch_I and QSearch_P – In Idle or PS data mode, the search should be done. In Idle Mode,there is no drawback from switching to UMTS. In PS data mode, the throughput and capacity gain can be significant, thus the user and the network both benefit from searching for UMTS.

FDD_Qoffset / FDD_GPRS_Qoffset – Applies an offset to RLA_C / RLA_P for cell reselection to access technology/mode FDD (one or more) 0 = – ∞ (always select a cell if acceptable), 1 = –28 dB, 2 = –24 dB, … , 15 = 28 dB.

Setting Trade-off for FDD_Qoffset / FDD_GPRS_Qoffset: If parameter is too high, UTRAN FDD cells may not be reselected.


4-12


Section 4: Inter-System Continuity – Configuration and Parameter Settings


Section 4-12



–104 dBm5–102 dBm6FDD_RSCPmin

–14 dB6–12 dB7FDD_Qmin

(CS +GPRS)

Eng. Value

IE value

Eng. value

IE value

Q-2Q-1I-RAT Scenarios

GERAN to UTRAN Cell Reselection Parameters –Q_Search, 3G_Search_Prio, FDD_Qmin

FDD_Qmin

FDD_Qmin – Lower FDD_Qmin is chosen for the Q-3 scenario because it has full 3G coverage. A lower Ec/No triggering value could be used to push traffic aggressively onto the WCDMA layer. Note that the FDD_Qmin is used only as the evaluation threshold and, therefore, FDD_Qoffset is set to negative infinity.

FDD_Qmin – A minimum threshold for Ec/No for UTRAN FDD cell reselection, 0 = –20 dB, 1 = –6 dB, 2 = –18 dB, 3 = –8 dB, 4 = –16 dB, 5 = –10 dB, 6 = –14 dB, 7 = –12 dB.

Setting Trade-off: If the parameter is too low (in dB), UTRAN FDD cells may be reselected too frequently. If the parameter is too high (in dB), UTRAN FDD cells may not be reselected.


4-13



Section 4-13



Summary – Algorithms and Parametersfor Inter-RAT Cell Reselection

Algorithms and related parameters for Inter-RAT cell reselection

• 3G: UTRA Idle, Cell_FACH, Cell_PCH / URA_PCH states (UE Initiated)– Parameters: Qrxlevmin, Qqualmin, Pcompensation, Qoffset, Qhyst,

Treselection, SsearchRAT GSM

• 2G: GSM Idle Mode (UE Initiated)– Parameters: 3G_SEARCH_PRIO, Qsearch_I, FDD_Qoffset , FDD_Qmin,

FDD_RSCP_Threshold

• 2.5G: GPRS Packet Idle and Packet Transfer Modes (UE Initiated / NW directed)– Parameters: 3G_SEARCH_PRIO, Qsearch_P, FDD_GPRS_Qoffset,

FDD_Qmin, FDD_RSCP_Threshold

Notes


4-14



Section 4-14



Typical Compressed Mode and Inter-RAT Transition Mechanisms

• Activation and Configuration of Compressed Mode (CM)

• Event Triggers for Compressed Mode

• Inter-RAT Transition

Notes


4-15



Section 4-15



Compressed ModeActivation and Configuration

CM activation/deactivation options:

• Measurement Control Message– Event 2d/2f, Event 1f/1e,

Event 6a/6b or periodic

• Physical Channel Reconfiguration• Transport Channel Reconfiguration

CM configuration options:

• Physical Channel Reconfiguration

• Transport Channel Reconfiguration

• Radio Bearer Setup/Release/Reconfiguration

• RRC Connection Setup• Cell Update Confirm

Inter-RAT transition activation options:

• Event-Triggered: Event 3A• Periodic reporting: MRM meets inter-RAT criteria

Notes


4-16



Section 4-16



Event Triggers for Compressed Mode

The UE Tx power becomes less than an absolute threshold.

6B

The UE Tx power becomes larger than an absolute threshold.

6A

The estimated quality of the currently used frequency is above a certain threshold. – Active Set based measurement

2F

The estimated quality of the currently used frequency is below a certain threshold. – Active Set based measurement

2D

A primary CPICH becomes worse than an absolute threshold. – Cell based measurement

1F

A primary CPICH becomes better than an absolute threshold. – Cell based measurement

1EDefinitionEvent

Star

t Com

pres

sed

Mod

e Stop Com

pressed Mode

Event Triggers for Compressed Mode

Infrastructure manufacturers or operators may use Event 1F, Event 2D, or Event 6A reports from the UE to activate Compressed Mode. They may use Event 1E, Event 2F, or Event 6B to deactivate Compressed Mode. Alternatively, periodic measurements can be used.


4-17




Section 4-17



,10)1(10101

jBestj

N

ijijjfrequencyfrequencyj LogMWMLogWLogMQ

jA

⋅⋅−+⎟⎟⎠

⎞⎜⎜⎝

⎛⋅⋅=⋅= ∑

=

CM Triggers using Events 2d and 2f

Event 2d:

Event 2f:

– QUsed: Quality estimate of the used UTRAN frequency.

– TUsed2d (TUsed2f) is the absolute threshold that applies for the used frequency and Event 2d (2f).

– H2d (H2f) is the hysteresis parameter for the Event 2d (2f).

2/22 ddUsedUsed HTQ −≤2/22 ffUsedUsed HTQ +≥

2/22 ddUsedUsed HTQ +>2/22 ffUsedUsed HTQ −<

Trigger De-trigger

• When UE reports Event 2d, network may direct to start CM operation.

• When UE reports Event 2f, network may direct to stop CM operation.

• Ec/No or RSCP can be used, depending on MeasurementQuantity attribute carried in the Measurement Control message.

Compressed Mode Triggers using Events 2d and 2f

See 3GPP 25.331 §14.2.1.4 (Event 2d), §14.2.1.6 (Event 2f).

In the Measurement Control message, the MeasurementQuantity field is optional. In the cases where the MeasurementQuantity attribute is not specified explicitly, the threshold Tused can be used to determine the measurement quantity:

If Tused > –25 dB, then Ec/No is to be measured.

If Tused < –24 dB, then RSCP is to be measured.

If Tused > 0, then path loss is to be measured.


4-18



Section 4-18



CM Triggers using Events 1e and 1f

Event 1e: Event 1f:

– MNew (MOld) is the measurement result of the cell that becomes better (worse) than an absolute threshold.

– CIONew (CIOOld) is the individual cell offset for the cell becoming better (worse) than the absolute threshold. Otherwise it is equal to 0.

– T1e (T1f) is an absolute threshold.– H1e (H1f) is the hysteresis parameter for the Event 1e (1f).

,2/10 11 eeNewNew HTCIOLogM +≥+⋅ ,2/10 11 eeNewNew HTCIOLogM −<+⋅

,2/10 11 ffOldOld HTCIOLogM −≤+⋅ ,2/10 11 ffOldOld HTCIOLogM +>+⋅

Trigger De-trigger

• When UE reports Event 1f, network may direct to start CM operation.• When UE reports Event 1e, network may direct to stop CM operation.• Ec/No, RSCP or path loss can be used, depending on the

MeasurementQuantity attribute specified in the Measurement Control message.

Compressed Mode Triggers using Events 1e and 1f

See 3GPP 25.331 §14.1.2.5 (Event 1e) and §14.1.2.6 (Event 1f).

In the Measurement Control message, the MeasurementQuantity field is optional. In the cases where the MeasurementQuantity attribute is not specified explicitly, the threshold T1e (T1f) can be used to determine the measurement quantity:

If T1e (T1f) > –25 dB, then Ec/No is to be measured.If 0 < T1e (T1f) < –24 dB, then RSCP is to be measured.If T1e (T1f) > 0, then path loss is to be measured.


4-19



Section 4-19



Event Triggers for Inter-RAT Transition

The estimated quality of the currently used UTRAN frequency is below a certain threshold, and the estimated quality of the other system is above a certain threshold

3A

DefinitionEvent

Trigger De-trigger

2/3aUsedUsed HTQ −≤2/3aRATOtherRATOtherRATOther HTCIOM +≥+

2/3aUsedUsed HTQ +>

2/3aRATOtherRATOtherRATOther HTCIOM −<+

and or

• When the UE sends Event 3A, the network may instruct the UE to start handover.

• Stopping the CM could be triggered by other Events (1e, 2f, etc.).

Event Triggers for Inter-RAT Transition

Infrastructure manufacturers or operators that use the event-triggering method typically use Event 3A reports from the UE to trigger inter-RAT transition (handover / cell change order).

The following conditions must be met to trigger Event 3a:

The estimated quality of the own system must be below a defined threshold.The estimated quality of the other system must be above a defined threshold:

The variables in the formula are defined as follows:

QUsed – quality estimate of the used UTRAN frequencyTUsed – absolute threshold that applies for the used frequency in that measurementH3a – hysteresis parameter for Event 3aMOtherRAT – measurement quantity for the cell of the other systemCIOOtherRAT – cell individual offset for the cell of the other systemTOtherRAT – absolute threshold that applies for the other system in that measurement

,10)1(10101

Best

N

iiUTRANUTRAN LogMWMLogWLogMQ

A

⋅⋅−+⎟⎟⎠

⎞⎜⎜⎝

⎛⋅⋅=⋅= ∑

=


4-20




Section 4-20



UTRAN to GERAN HO Parameters (Event Trigger)

Parameter Recommended ValueMeasurement quantity for UTRAN quality estimate CPICH-RSCP and CPICH-Ec/No

GSM Filter Coefficient 0 (as short as possible)

BSIC Verification Required Required

Threshold Own System 3a -9 dB (Ec/No measurement quantity),

-95 dBm (RSCP measurement quantity)

W (Event 3a) 0

Threshold Other System 3a – 100 dBm

Hysteresis 3a 0 dB

TTT 3a 0 ms

UTRAN to GERAN HO Parameters

Measurement Quantity for UTRAN Quality Estimate – CPICH Ec/No or CPICH RSCP or path loss.

GSM Filter Coefficient – Time constant of the GSM RSSI measurement filter.

Setting Tradeoff: If parameter is set higher than 0, reporting of suitable GSM cells may be delayed. A higher value increases measurement reliability.

BSIC Verification Required – Defines if the UE is required to verify the BSIC of GSM cells.

Setting Tradeoff: BSIC verification provides more reliable information to the UTRAN for controlling handover to a specific GSM cell. The disadvantage is it requires additional UE processing and a longer measurement duration in Compressed Mode.

Threshold Own System 3a – Minimum quality of the serving UTRAN carrier below which handover to GSM should be triggered, provided a suitable GSM cell exists (–115...0 => –115...0 dBm).

Setting Tradeoff: This IE affects one of the inequality criteria that must be satisfied for an Event 3a to occur. If the parameter is too small, handover to suitable GSM cells may be delayed while the call remains on a low quality UTRAN cell. If the parameter is too high, a UE in good UTRAN coverage may be unnecessarily handed over to a GSM cell. UE mobility should also be considered when setting this parameter. For UEs moving at high speed, even higher values (–98 dBm, for example) might be appropriate to allow sufficient time for UE reporting and handover completion before the WCDMA coverage degrades.


4-21




Section 4-21



UTRAN to GERAN HO Parameters (Event Trigger) (continued)


Measurement quantity for UTRAN quality estimate CPICH-RSCP and CPICH-Ec/No

GSM Filter Coefficient 0 (as short as possible)

BSIC Verification Required Required

Threshold Own System 3a -9 dB (Ec/No measurement quantity),

-95 dBm (RSCP measurement quantity)

W (Event 3a) 0

Threshold Other System 3a – 100 dBm

Hysteresis 3a 0 dB

TTT 3a 0 ms


W (Event 3a) – Weighting factor applied to the best active cell quality in the estimation of the quality of the serving UTRAN carrier (0…20 => 0… 2).

Setting Tradeoff: If this parameter value is set too low, the quality of cells other than the best cell does not affect the quality estimate of this serving UTRAN carrier. In this case, when no dominant cell exists, but a few cells with relatively good and similar quality do exist, Event 3a may be triggered prematurely.

Threshold Other System 3a – Minimum required GSM RSSI for reliable handover to GSM (–115...0 => –115...0 dBm).

Setting Tradeoff: If set too high, handover to suitable GSM cells may be delayed. If set too small, a UE may be handed over to an unsuitable GSM cell.

Hysteresis 3a – This IE affects the inequality criteria that must to be satisfied for an Event 3a to occur. It is also used to control the transition out of the “Event 3a triggered” state (0…15 => 0…7.5 dB).

Setting Tradeoff: If set too high, Event 3a triggering may be inhibited even when a suitable GSM cell exists and the quality of the serving UTRAN cell is relatively poor.

Time-to-Trigger 3a – Period between detection of Event 3a and sending of Measurement Report (0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000 => 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000 ms).

Setting Tradeoff: If set too large, Event 3a triggering may be delayed even when a suitable GSM cell exists and the quality of the serving UTRAN cell is relatively poor.


4-22



Section 4-22




-15-15-13-15-15-12Ec/No threshold

-14-14-12-14-14-11Ec/No threshold

1280 ms1280 ms1280 ms1280 ms1280 ms1280 msTime to Trigger for 1e/2f

-106-104-104-106-104-100RSCP threshold

Event2f & Event1e

320 ms320 ms320 ms320 ms320 ms320 msTime to Trigger for 1f/2d

-108-106-106-108-106-102RSCP threshold

Event2d & Event1f

PS(2g=GPRS,No

EDGE)

PS(2g= EDGE)

CSPS

(2g=GPRS,NoEDGE)

PS(2g=

EDGE)CS

Q-2Q-1I-RAT Scenario


While the recommended trigger for Event 3a is RSCP-based, the preference for RSCP versus Ec/No-based triggering for Events 2d/2f/1e/1f depends on the scenario. RSCP is preferred in coverage-limited areas, while Ec/No is preferred in highly-loaded areas. Some vendor implementations may support both measurement quantities for CM triggering.

Threshold values for Q-3 are chosen so that they are always lower than for those for Q-1 and Q-2, because in Q-3 the 3G coverage is better. For the same reason, CM TimetoTrigger values for Q-3 are chosen higher than for Q-1 and Q-2. In order to prevent ping-pong effects for CM activation/deactivation, the TimetoTrigger values are set to allow for a fast CM activation and slow CM deactivation.

Threshold – Quality thresholds below/above which Compressed Mode measurements should be triggered or de-triggered (RSCP: –115...0 => –115...0 dBm).

Setting Trade-off: This IE controls the start and stop of Compressed Mode measurements. If CM duration is too long, it causes too much interference and uses more OVSF space (if SF/2 is used), or reduces data throughput unnecessarily (if HLS is used). If CM duration is too short, the accuracy of inter-RAT measurement will be affected, which may result in degraded handover performance.

Time-to-Trigger (TTT) – Period between detection of Event X and sending of Measurement Report (0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000 => 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000 ms).

Setting Trade-off: If parameter is too large, Event X triggering may be delayed.


4-23



Section 4-23



GERAN to UTRAN HO Parameters


3G_SEARCH_PRIO depends on scenario (see next slide)

FDD_REP_QUANT RSCP

FDD_MULTIRAT_REPORTING 3 cells (max)

Qsearch_C (Connected) 0 = < – 98 dBm or 7 = ∞ (always)

FDD_Qmin –14 or –12 dB, depending on scenario

FDD__Qoffset 0 = – ∞ (always)

GERAN to UTRAN HO Parameters

3G_Search_Prio – Indicates if 3G cells may be searched when BSIC decoding is required (0 = no, 1 = yes).

Setting Trade-off: If set to 0, the UE gives higher priority to GSM BSIC decoding. If set to 1, UE applies higher priority to UTRAN FDD measurements.

FDD_REP_QUANT – Indicates the reporting quantity for UTRAN FDD cells: 0 = RSCP, 1 = Ec/No.Setting Trade-off: RSCP is better indication for coverage; Ec/No better for interference.

FDD_MULTIRAT_REPORTING – Indicates the number of UTRAN FDD cells that shall be included in the list of strongest cells or in the Measurement Report (0..3 => 0..3 cells).

Setting Trade-off: If set too small, only a few cells are measured and reported, saving UE processing. If set high, more cells are measured and reported, requiring higher UE processing.

Qsearch_C – In CS domain Connected Mode, limited advantage can be gained from performing a handover to UTRAN. The higher capacity in UMTS would be a reason to perform such a handover, but the risk of losing the connection during the HO does not compensate for the potential gain. For this reason, disabling the search for UMTS while in Connected Mode is recommended.

Setting Trade-off: Considering only the case 0–7 (measure 3G cells if signal level is below threshold), which is more reasonable: if threshold is too small, the UE will not perform inter-RAT measurements and may miss the opportunity to be handed over to WCDMA. If it is too high, the UE will perform inter-RAT measurements very often, decreasing standby time. Search for 3G cells if signal level is below (0-7) threshold: 0 = –98 dBm, 1 = –94 dBm, … , 6 = –74 dBm, 7 = ∞(always) or above (8-15) threshold: 8 = –78 dBm, 9 = –74 dBm, … , 14 = –54 dBm, 15 = ∞(never).


4-24



Section 4-24



GERAN to UTRAN HO Parameters (continued)


3G_SEARCH_PRIO depends on scenario (see next slide)

FDD_REP_QUANT RSCP

FDD_MULTIRAT_REPORTING 3 cells (max)

Qsearch_C (Connected) 0 = < – 98 dBm or 7 = ∞ (always)

FDD_Qmin –14 or –12 dB, depending on scenario

FDD__Qoffset 0 = – ∞ (always)

GERAN to UTRAN HO Parameters (continued)

FDD_Qmin – A minimum threshold for Ec/No for UTRAN FDD cell reselection, 0 = –20 dB, 1 = –6 dB, 2 = –18 dB, 3 = –8 dB, 4 = –16 dB, 5 = –10 dB, 6 = –14 dB, 7 = –12 dB.

Setting Trade-off: If the parameter is too low (in dB), UTRAN FDD cells may be reselected to too frequently. If the parameter is too high (in dB), UTRAN FDD cells may not be reselected.

FDD_Qoffset – Applies an offset to RLA_C / RLA_P for cell reselection to access technology / mode FDD (one or more) 0 = – ∞ (always select a cell if acceptable), 1 = –28 dB, 2 = –24 dB, … , 15 = 28 dB.

Setting Trade-off: If parameter is too high, UTRAN FDD cells may not be reselected.

Additional Parameters – The following parameters are defined, but no values are currently recommended:

FDD_REPORTING_THRESHOLD – Applies priority reporting if the reported value is above the threshold for GSM frequency band or access technology / mode FDD (one or more), 0, 6, … , 36, ∞ (never).FDD_REPORTING_OFFSET – Applies an offset to the reported value when prioritizing the cells for reporting for GSM frequency band or access technology / mode FDD (one or more), 0, 6, … , 42 dB.


4-25




Section 4-25



GERAN to UTRAN HO Parameters –Q_Search, 3G_Search_Prio, FDD_Qmin

–14 dB6–12 dB7FDD_Qmin

(CS +GPRS)

Yes1No03G_search_prio

always7<-98 dBm0Q_Search_C

CS

Eng. Value

IE value

Eng. value

IE value

Q-2Q-1I-RAT Scenarios:

Q_Search, 3G_Search_Prio, FDD_Qmin

Qsearch_C – At the edge of 3G coverage, it is probably not worth risking loss of the CS connection by pushing traffic to the WCDMA layer unless the 2G coverage is degrading significnatly (< –98 dBm). This approach is different for PS (refer to the cell reselection section for PS).

3G_Search_Prio – At the edge of 3G coverage, we do not need to prioritize the searching of 3G cells for CS.

FDD_Qmin – Lower FDD_Qmin is chosen for the Q-3 scenario because it has full 3G coverage and a lower Ec/No triggering value that could be used to push traffic aggressively onto the WCDMA layer. Note that the FDD_Qmin is used only as the evaluation threshold; therefore, FDD_Qoffset is set to negative infinity.


4-26



Section 4-26



Exercise:Event Triggers for Inter-RAT (1)

A

B

C

Quality

Threshold othersystem (3a)

Threshold usedfrequency (2d)

Threshold ownsystem (3a)

Time

P-CPICH1

GSM

In the following diagram, mark the times when Events 2d/3a are detected and reported together with the effects of Time-To-Trigger 2d and 3a.

Timeto trigger

2d

Timeto trigger

3a

Notes


4-27



Section 4-27



Exercise:Event Triggers for Inter-RAT (1) – Answers

A

B

C

Quality




Time

P-CPICH1

GSM

Event2d

detected

Event2d

reported

Event3a

detected

Event3a

reported

Timeto trigger

3a

Timeto trigger

2d

In the following diagram, mark the times when Events 2d/3a are detected and reported together with the effects of Time-To-Trigger 2d and 3a.

Exercise: Event Triggers for Inter-RAT (1) – Answers

This example assumes a single WCDMA carrier deployed with GSM. The UE is initially served by WCDMA CPICH1, whose measured quality decreases until the estimated quality of the currently used frequency is below a defined threshold; this detection of Event 2d is shown at point A. This Event is reported after the associated Time-to-Trigger delay, which then activates Compressed Mode measurements of the GSM neighbors.

Handover to the GSM neighbor is controlled by Event 3a. Two conditions must be met to detect Event 3a:

The measured quality of the serving WCDMA cell must be below a defined threshold, as occurs at point B. The measured quality of the GSM neighbor must be above a defined threshold, as occurs at point C.

Detection of Event 3a therefore occurs at point C, with reporting after the associated Time-to-Trigger delay.


4-28



Section 4-28



Exercise:Event Triggers for Inter-RAT (2)

Quality




Time

P-CPICH1

GSM

Timeto trigger

2d

Timeto trigger

3a

Threshold usedfrequency (2f)

EventDe-triggered

Timeto trigger

2f

In the following diagram, mark the times when Events 2d/2f/3a are detected and reported as well as the CM period together with the effects of Time-To-Trigger 2d, 2f and 3a.

Notes


4-29



Section 4-29



Exercise:Event Triggers for Inter-RAT (2) – Answers

Quality




Time

P-CPICH1

GSM

Threshold usedfrequency (2f)

Timeto trigger

2d

Timeto trigger

2dTime

to trigger2d

Event2d

reportedEvent

2ddetected

Event2d

detected

Event2d

detected

Event3a

detected

Timeto trigger

3a

Event2f

detected

Timeto trigger

2f

Timeto trigger

2d

Timeto trigger

3a

EventDe-triggered

Timeto trigger

2f

Event2f

reported

Compressed Mode

In the following diagram, mark the times when Events 2d/2f/3a are detected and reported as well as the CM period together with the effects of Time-To-Trigger 2d, 2f and 3a.

Exercise: Event Triggers for Inter-RAT (2) – Answers

In this example, Event 2d is detected several times but is not reported until the third time because of the effect of Time-to-Trigger (TTT). The third time it is detected, the criterion for activating Event 2d persists for over the period of TTT2d, so Event 2d is reported. Compressed Mode measurements are started after receiving the measurement report and CM configuration / activation completed. At this time, the UE monitors the GSM cell in addition to the WCDMA cell.

When the criteria for Event 3a are satisfied for at least the period of TTT3a, the UE can start inter-RAT transition. Near the end of the graph, the radio condition for the WCDMA cell recovers significantly, which triggers the deactivation of Compressed Mode measurements via Event 2f.


4-30



Section 4-30



Open the Word file: Measurement Control Message (e2d,e2f)

• What is the quality measure for CM activation?

• Identify TUsed2d , TUsed2f , H2d , H2f and the TTT in the MCM:

– TUsed2d =– H2d =– TTT2d =– W2d =– TUsed2f =– H2f =– TTT2f =

– W2f =

• What is the measurement reporting mode?

Exercise:Compressed Mode Using Events 2d and 2f

Exercise: Compressed Mode Using Events 2d and 2f

See 3GPP 25.331 §14.2.1.4 (Event 2d), §14.2.1.6 (Event 2f), §14.1.2.5 (Event 1e), and §14.1.2.6 (Event 1f).


4-31




Section 4-31



Exercise: Compressed Mode Using Events 2d and 2f – Answers

Open the Word file: Measurement Control Message (e2d,e2f)

• What is the quality measure for CM activation?

– CPICH RSCP-based CM activation

• Identify TUsed2d , TUsed2f , H2d , H2f and the TTT in the MCM:

– TUsed2d = –100 dBm– H2d = 0 dB– TTT2d = 320 ms– W2d = 0– TUsed2f = –95 dBm– H2f = 0 dB– TTT2f = 1.28 s– W2f = 0

• What is the measurement reporting mode? event-trigger

Exercise: Compressed Mode Using Events 2d and 2f – Answers

See 3GPP 25.331 §14.2.1.4 (Event 2d), §14.2.1.6 (Event 2f), §14.1.2.5 (Event 1e), and §14.1.2.6 (Event 1f).

Note: W = 0 means UE takes no filtering on measured values.

Note: The values selected in the example are for illustration purposes only. Do not use them as recommended values for parameter settings in real-world networks. Also, although the example shows an RSCP-based triggering scheme, in practice Ec/No-based triggering is often used also.


4-32




Section 4-32



Exercise:Inter-RAT Transition via Event 3a

Open the Word file: Measurement Control Message

• What is the GSM neighbor defined in the MCM?

• What are the inter-RAT measurement quantities?

– Intra-freq:

– Inter-RAT:

• What are the triggering conditions for Event 3a?

– Threshold Own System 3a:

– Threshold Other System 3a:

– Hysteresis:

– Time-to-Trigger:

Exercise: Inter-RAT Transition via Event 3a

See 3GPP 25.331 §14.3.1.1 (Event 3a).


4-33



Section 4-33



Exercise:Inter-RAT Transition via Event 3a – Answers

Open the Word file: Measurement Control Message• What is the GSM neighbor defined in the MCM?

– DCS 1800, BCCH ARFCN 87, BSIC 53

• What are the inter-RAT measurement quantities?

– Intra-freq: RSCP

– Inter-RAT: GSM carrier RSSI, BSIC identification & reconfirmation

• What are the triggering conditions for Event 3a?

– Threshold Own System 3a: –102 dBm

– Threshold Other System 3a: –95 dBm

– Hysteresis: 0 dB

– Time-to-Trigger: 60 ms

Exercise: Inter-RAT Transition via Event 3a – Answers

See 3GPP 25.331 §14.3.1.1 (Event 3a).


4-34



Section 4-34



Exercise:Compressed Mode and Inter-RAT

Use the MCM from the previous two exercises: Measurement Control Message (e2d,e2f) and Measurement Control Message and the RF conditions specified in the Excel file CM_activation.xls.

• How many times does the UE go into Compressed Mode?

• How long does the UE spend in CM? How can this time be reduced?

• What is the effect on CM activation/deactivation?

• How can we increase the time in CM without multiple activations and deactivations?

Exercise: Compressed Mode and Inter-RAT

See 3GPP 25.331 §14.2.1.4.


4-35



Section 4-35



Exercise:Compressed Mode and Inter-RAT – Answers

-120-110-100-90-80-70-60-50-40-30-20-10

0

Relative time [s]

Ec/N

o [d

B] /

RSC

P [d

Bm

] / R

XLEV

[dB

m]

RSCP_1 EcNo_1 RXLEV_2 Event 3A Compressed Mode T2d T2f T3own

Exercise: Compressed Mode and Inter-RAT – Answers

How many times does the UE go into Compressed Mode?

The UE goes into CM 3 times.

How long does the UE spend in CM?

Total time in CM: 10 seconds.

How can this time be reduced?

Reduce the e2d threshold.

What is the effect on CM activation/deactivation?

With e2d threshold reduced to –105 dBm, a single CM period is observed.

How can we increase the time in CM, without multiple activation/deactivation?

By decreasing e3a, own threshold, CM time can be increased without increasing the CM activations.


4-36



Section 4-36



Summary – Typical Compressed ModeActivation and Configuration

Triggering conditions of CM:

• Event-trigger or periodic

• If event-trigger => own system gets bad

– Low RSCP or Ec/No of the serving WCDMA cell(s)

– High UE transmit power

Configuration of CM:

• Physical Channel Reconfiguration

• Transport Channel Reconfiguration

• Radio Bearer Setup/Release/Reconfiguration

• RRC Connection Setup• Cell Update ConfirmInter-RAT transition:

• If event-trigger:– Own system gets worse– Other system gets better

• If periodic measurements meet inter-RAT criteria

Notes


4-37



Section 4-37



A Step Back View –WCDMA-to-GSM/GPRS Handover Process

CM

Sta

rtH

O tr

igge

rH

O S

tart

/C

M E

ndC

M T

rigge

r

The Diagram

This diagram shows only the successful branches, i.e., only the “yes” branches. The “no”branches are not shown because no explicit actions are required by either the UE or UTRAN.

Handover from UTRAN Failure

After receiving the HandoverfromUTRANCommand, the UE leaves the WCDMA cell, tuning to the target GSM cell for continuous services. If the UE fails to acquire the target GSM cell, it can tune back to the WCDMA cell and send HandoverfromUTRANFailure message to inform the RAN of the failure causes.


4-38



Section 4-38



Inter-RAT Handover Call Flow –Revisit (1 of 7)

Notes


4-39



Section 4-39



message measurementReport : measurementIdentity 2,

eventResults interFreqEventResults :

eventID e2d

Inter-RAT Handover Call Flow –Drilling Down (2 of 7)

Notes


4-40



Section 4-40



message physicalChannelReconfiguration :dpch-CompressedModeInfo

tgp-SequenceList

tgpsi 2,tgps-Status deactivate : NULL,

tgmp gsm-CarrierRSSIMeasurement,{ tgprc 0, tgsn 4, tgl1 7, tgd 270, tgpl1 8, rpp mode1, itp mode0,ul-DL-Mode ul-and-dl : { ul sf-2, dl sf-2 },dl-FrameType dl-FrameTypeA, deltaSIR1 12, deltaSIRAfter1 6 }

tgpsi 3,

tgps-Status deactivate : NULL,

tgmp gsm-initialBSICIdentification,

{ … }

tgpsi 4,tgps-Status deactivate : NULL,

tgmp gsmBSICReconfirmation,

{ … }


Notes


4-41



Section 4-41



message measurementControl : r3 : measurementCommand setup : interRATMeasurement : interRATCellInfoList

removedInterRATCellList removeAllInterRATCells : NULL,

newInterRATCellListinterRATCellID 0,

technologySpecificInfo gsm : interRATCellIndividualOffset 0,bsic { ncc 3, bcc 4}, frequency-band dcs1800BandUsed, bcch-ARFCN 61

…interRATCellID 10,

technologySpecificInfo gsm : interRATCellIndividualOffset 0,bsic {ncc 6, bcc 1},frequency-band dcs1800BandUsed, bcch-ARFCN 518

interRATMeasQuantitymeasQuantityUTRAN-QualityEstimate

filterCoefficient fc3, modeSpecificInfo fdd : intraFreqMeasQuantity-FDD cpich-RSCP

ratSpecificInfo gsm : measurementQuantity gsm-CarrierRSSI,filterCoefficient fc3,

bsic-VerificationRequired required

interRATReportingQuantityutran-EstimatedQuality FALSE,ratSpecificInfo gsm : observedTimeDifferenceGSM FALSE,

gsm-Carrier-RSSI TRUE

reportCriteria interRATReportingCriteria :

interRATEventList : event3a : thresholdOwnSystem -100, w 0, hysteresis 0, thresholdOtherSystem -90, timeToTrigger ttt640,

measurementReportingModemeasurementReportTransferMode acknowledgedModeRLC,periodicalOrEventTrigger eventTrigger

dpch-CompressedModeStatusInfotgp-SequenceShortList

tgpsi 2,tgps-Status activate : tgcfn 116

tgpsi 3,tgps-Status activate: tgcfn 118

tgpsi 4,tgps-Status activate: tgcfn 122


Notes


4-42



Section 4-42



message measurementReport :measurementIdentity 4,

measuredResults interRATMeasuredResultsList :gsm :

{ gsm-CarrierRSSI '111110'B,bsicReported verifiedBSIC : 7 }

…{ gsm-CarrierRSSI '011101'B,

bsicReported verifiedBSIC : 6 }

eventResults interRATEventResults :

eventID e3a,cellToReportList

bsicReported verifiedBSIC : 7

…bsicReported verifiedBSIC : 6


Notes


4-43



Section 4-43




message handoverFromUTRANCommand-GSM : r3 : toHandoverRAB-Info

rab-Identity gsm-MAP-RAB-Identity : '00000001'B,cn-DomainIdentity cs-domain,nas-Synchronisation-Indicator '0111'B,re-EstablishmentTimer useT314

frequency-band dcs1800BandUsed,

gsm-message gsm-MessageList : {

'00000110 00101011 00110101 01001010 00001101 10110000 00001110 01010110 000001 ...'B

}

Notes


4-44



Section 4-44




GSM RR signaling messageCHANNEL_TYPE UL_DCCH GSM Radio Resources Management Protocol

MESSAGE_TYPE HANDOVER COMPLETERR CauseRR cause value Normal event

Notes


4-45



Section 4-45



Inter-System Continuity: Configuration and Parameter Settings – What Did We Learn?

What are the algorithms and related parameters for different inter-RAT cell reselections?

What are the typical Compressed Mode and inter-RAT handover mechanisms?

Notes


4-46



Comments/Notes


5-1

80-W0242-4 Rev DWCDMA (UMTS) Inter-System Network Optimization WorkshopSection 5: Inter-System Continuity – Compressed Mode Settings


Section 5-1



Section 5: Inter-System Continuity –Compressed Mode Settings

Inter-System Continuity – CompressedMode Settings5

SECTION

Notes


5-2



Section 5-2




Examine the main parameters for Compressed Mode settings and define how they affect the data transmission.

Analyze the implementation differences of some typical inter-RAT Compressed Mode settings, and describe their affects on the observed call flow.

Analyze the implementation of Compressed Mode with HSDPA.

Notes


5-3



Section 5-3



Compressed Mode Settings

Main parameters for Compressed Mode (CM) settings and their effects on data transmission:

• Measurement purpose

• Transmission gap pattern sequences

• Frame handling

• Power control

Compressed Mode Settings

The same Compressed Mode operation can be used for both inter-RAT measurement and inter-frequency measurement. Hence, measurements between the two types of measurements must be carefully coordinated. For instance, to retain the UE in a WCDMA network, one would like to configure the inter-frequency measurement and inter-RAT measurement to ensure that the UE will attempt inter-frequency handover first before attempting the inter-RAT handover.

In keeping with the focus of this workshop and the time limitations, we will assume the proper coordination of Compressed Mode setting has already been taken care of and we will focus on the IRAT aspect of the issues.


5-4



Section 5-4



Compressed Mode Measurement Purpose

• For GSM measurements, three Compressed Mode pattern sequences can be configured by UTRAN using Transmission Gap Measurement Purpose (TGMP):

– GSM carrier RSSI measurement– Initial BSIC identification– BSIC re-confirmation

• Each GSM measurement requires a CM pattern. All three measurements are typically performed, but some vendor implementations may not need BSIC re-confirmation.

• Three independent patterns can be used.– The selected patterns for these three different measurements must

not conflict.

Notes


5-5



Section 5-5



Exercise: Transmission Gap Pattern Sequences

Open the Word file: Physical Channel Reconfiguration Message.

• How many Transmission Gap Pattern (TGP) sequences are configured in this message?

• What are the purposes of the configured TGP sequences? Check Transmission Gap Measurement Purpose (TGMP) – See 3GPP TS25.331 §10.3.6.33.

• Are these sequences set active?

Notes


5-6



Section 5-6



Transmission Gap Pattern Sequences –Answers

Open the Word file: Physical Channel Reconfiguration Message.

• How many Transmission Gap Pattern (TGP) sequences are configured in this message? Three

• What are the purposes of the configured TGP sequences?

– TGPSI 1: GSM Carrier RSSI Measurement– TGPSI 2: GSM Initial BSIC Identification– TGPSI 3: GSM BSIC Reconfirmation

• Are these sequences set active? No. TGPS-Status is deactivated. TGCFN is not provided.

Notes


5-7



Section 5-7



• Allowed TGL values in slots (3, 4, 5, 7, 10, 14)• Allowed TGPL values in frames (1 ... 144)• Allowed TGD values in slots (15 ... 269)

Compressed Mode Parameters –Conceptual View

Compressed Mode ParametersTGSN – A transmission gap pattern begins in a radio frame (called first radio frame of the transmission gap pattern). This pattern contains at least one transmission gap slot. TGSN is the slot number of the first transmission gap slot within the first radio frame of the transmission gap pattern.TGL1 – Duration of the first transmission gap within the transmission gap pattern, expressed in number of slots.TGL2 – Duration of the second transmission gap within the transmission gap pattern, expressed in number of slots. If this parameter is not explicitly set by higher layers, then TGL2 = TGL1.TGD – Duration between the starting slots of two consecutive transmission gaps within a transmission gap pattern, expressed in number of slots. If this parameter is not set by higher layers, then there is only one transmission gap in the transmission gap pattern. The distance between gaps can range from 1 frame to 18 frames, in units of timeslots (15 to 269 slots). If the second transmission gap is to be omitted, then this parameter takes the value “270,” which represents “undefined.”TGPL1(2) – Duration of the first (second) transmission gap pattern, expressed in number of frames (1 to 144). If TGPL2 is omitted, its assumes the default value of TGPL1. TGPRC (Transmission Gap Pattern Repetition Count) – The number of transmission gap patterns within the Transmission Gap Pattern Sequence. There can be 1 to 511 patterns within a finite TGPS, or this parameter can take the value “0”, which represents “infinity” for an endlessly repeating sequence. TGCFN (Transmission Gap Connection Frame Number) – This is the CFN of the first radio frame of the first pattern 1 within the transmission gap pattern sequence TGPS (0 to 255). This is used for L2 transport channel synchronization between UE and UTRAN.


5-8



Section 5-8



When the transmission gap spans two consecutive radio frames, Nfirst and TGL must be set to ensure at least 8 slots are transmitted in each radio frame.

Transmission Gap Positions

Transmission Gap Position with Double Frame

Nfirst specifies the starting slot of the consecutive idle slots– Nfirst = 0,1,2,3,…,14

Nlast shows the number of the final idle slot, and is calculated as follows:– If Nfirst + TGL < 15, then Nlast = Nfirst + TGL –1 (in the same frame)– If Nfirst + TGL > 15, then Nlast = (Nfirst + TGL – 1) mod 15 (in the next frame)


5-9



Section 5-9



• Maximizing the length of the transmission gap enables reliable measurements: 14 slots (9.33 ms).

• With TGL = 14, 15 GSM ARFCNs RSSI can be measured.

• A maximum of 32 GSM neighbor cells are in SIB 11.

• For BSIC identification or reconfirmation, a larger TGL compensates for the large time difference between GSM and WCDMA frame alignment.

• With TGL = 14, time differences of 3500µs can be accommodated.

TGL and GSM Measurements

TGL and the Number of GSM Neighbors

The minimum number of GSM carriers to be measured is defined in relation to TGL in 25.133 §8.1.2.5.1, table 8-4. Depending on the number of GSM neighbors, TGL could be reduced without delaying the reporting of GSM cells.

TGL and BSIC Identification and Reconfirmation

Because GSM and UMTS are asynchronous systems, no direct time correlation exists between them. Therefore, to enable a UMTS UE to decode the BSIC (identification or reconfirmation), the GSM SCH/BCCH must fall within the CM gap. Increasing TGL increases the probability of decoding the BSIC. See 25.133 §8.1.2.5.2 for additional BSIC decoding requirements.

TGL Number of GSM carrier RSSI samples in each gap.

3 1 4 2 5 3 7 6

10 10 14 15


5-10



Section 5-10



Compressed Mode for GSM Measurements

GSM BSIC Identification and Reconfirmation Using Compressed Mode

Compressed Mode for GSM Measurements

This slide shows the Compressed Mode gap of length 14 slots (9.33 ms) that overlaps the FCCH and SCH of a neighbor GSM carrier. A GSM time slot is 0.577 ms long and a GSM frame is 4.615 ms. Because FCCH and SCH are always transmitted on time slot 1, the time duration during which both can be seen is 4.615 + 0.577 = 5.19 ms. However, this does not mean that both FCCH and SCH must be decoded in the same Compressed Mode gap.


5-11



Section 5-11



Compressed Mode for GSM Measurements (continued)

TGL and TGPL Selection:Making sure FCCH/SCH falls in the transmission gap

Compressed Mode for GSM Measurements (continued)

To make sure the GSM FCCH/SCH frames fall in the transmission gap during Compressed Mode, the CM parameters TGL and TGPL should be selected in such a way that the GSM FCCH/SCH frames are sliding against the transmission gaps. Hence, the GSM FCCH/SCH frames will always fall in some of the transmission gaps, where the BSIC information can be obtained.


5-12



Section 5-12



Exercise: Compressed Mode Configuration

• Open the Word file: Physical Channel Reconfiguration Message.

• Extract the Compressed Mode parameters and enter them into the following CM pattern diagram for all three TGP sequences.

Notes


5-13


Section 5: Inter-System Continuity – Compressed Mode Settings


Section 5-13



Compressed Mode Configuration – Answers

• TGPL1 = TGPL2, so TG pattern 1 = TG pattern 2 for all 3 TGPS

• TGSN = 4, TGPL1 = 7 slots, no second gap

• Unspecified number of repetitions in the message (deactivated)

Notes


5-14


Section 5: Inter-System Continuity – Compressed Mode Settings


Section 5-14



Other Compressed Mode Parameters

In addition to the parameters that define transmission gap positions, each TGP sequence is characterized by the following parameters:

• UL/DL Compressed Mode selection – Specifies whether Compressed Mode is used in Uplink only, Downlink only, or both.

– UL Compressed Mode method – The methods for generating the Uplink Compressed Mode gaps are spreading factor reduction or higher layer scheduling.

– DL Compressed Mode method – The methods for generating the Downlink Compressed Mode gaps are spreading factor reduction or higher layer scheduling.

• Downlink frame type – Specifies whether frame structure type 'A' or 'B' (see next slide) is used in Downlink Compressed Mode.

• Scrambling code change – Specifies whether the alternative scrambling code is used in the case of Compressed Mode by spreading factor reduction. Alternative scrambling codes are described in 3GPP 25.213 (also see the slide after next, “OVSF Code During CM”).

Notes


5-15



Section 5-15



• Type A maximizes the gap time for measurements:– No power control during compressed frames because no TPC bits are transmitted.

• Type B is more optimized for power control:– Provides the TPC bits in the first slot of the transmission gap.

Frame Structure Types in DL CM

Slot Format Types

With frame structure Type A, the Pilot field of the last slot in the transmission gap is transmitted. Transmission is turned off during the rest of the transmission gap.

With frame structure Type B, the TPC field of the first slot in the transmission gap and the Pilot field of the last slot in the transmission gap re transmitted. Transmission is turned off during the rest of the transmission gap.

Typically, Type B is used for CM by spreading factor reduction and Type A is used for all other transmission time reduction methods.


5-16



Section 5-16



OVSF Code During CM

• UTRAN can order the UE to use a different scrambling code in a compressed frame than in a non-compressed frame.

– If this occurs, there is a one-to-one mapping between the scrambling code used in the non-compressed frame and the compressed frame.

• Usage of an alternative scrambling code for compressed frames is signalled by higher layers for each physical channel, respectively.

OVSF and CM

A total of 218-1 = 262,143 scrambling codes, numbered 0 to 262,142 can be generated.

The primary scrambling codes consist of scrambling codes n=16*i, where i = 0 to 511. The ith set of secondary scrambling codes consists of scrambling codes 16*i+k, where k = 1 to 15.

Scrambling codes k = 0, 1, …, 8191 are used.

Each of these codes is associated with a left alternative scrambling code and a right alternative scrambling code, which may be used for compressed frames.

The left alternative scrambling code corresponding to scrambling code k is scrambling code number k + 8192. The right alternative scrambling code corresponding to scrambling code k is scrambling code number k + 16384.


5-17



Section 5-17



Power Control Parameters

• RPP – Recovery Period Power control mode specifies the Uplink power control algorithm applied during the recovery period after each transmission gap in Compressed Mode. RPP can take the value 0 or 1. Power control modes are described in 3GPP 25.214.

• ITP – Initial Transmit Power mode selects the Uplink power control method to calculate the initial transmit power after the gap. ITP can take the value 0 or 1. It is described in 3GPP 25.214.

• DeltaSIR1 – Delta in DL SIR target value to be set in the UE during the frame containing the start of the first transmission gap in the transmission gap pattern.

• DeltaSIRafter1 – Delta in DL SIR target value to be set in the UE one frame after the frame containing the start of the first transmission gap in the transmission gap pattern.

Power Control Parameters

The following parameters are sent by the UTRAN to the UE to define the operation of the power control algorithms used during Compressed Mode operation. They are repeated once for each measurement purpose:

Name Range Definition

ITP Enumerated (mode 0, mode 1) Uplink Initial Transmit Power mode used after an Uplink orDownlink transmission gap.

RPP Enumerated (mode 0, mode 1) Uplink Recover Period Power control mode used after anUplink or Downlink transmission gap.

DeltaSIR1 Real (0.3, 0.1 increments) Downlink ∆P1_coding of frame containing the start of thefirst transmission gap in the transmission gap pattern.

DeltaSIRRafter1 Real (0.3, 0.1 increments) Downlink ∆P1_coding of the current frame just followingthe start of the first transmission gap in the transmission gappattern.

DeltaSIR2 Real (0.3, 0.1 increments) Downlink ∆P2_coding of frame containing the start of thesecond transmission gap in the transmission gap pattern.

DeltaSIRRafter2 Real (0.3, 0.1 increments) Downlink ∆P2_coding of the current frame just followingthe start of the second transmission gap in the transmissiongap pattern.


5-18



Section 5-18



Other TGPS Parameters

• N Identify abort – Indicates the maximum number of repeats of patterns that the UE shall use to attempt to decode the unknown BSIC of the GSM cell in the initial BSIC identification procedure.

• T Reconfirm abort – Indicates the maximum time allowed for the reconfirmation of the BSIC of one GSM cell in the BSIC re-confirmation procedure.

Notes


5-19



Section 5-19



Inter-RAT Compressed Mode Settings

We will review the following examples and examine QUALCOMM’s recommended settings:

• Compressed Mode Activation/Deactivation

• Compressed Mode Configuration

• Inter-RAT Transition Trigger

The following slides describe different implementations of typical Inter-RAT Compressed Mode settings, and how they affect the observed call flow.

Notes


5-20



Section 5-20



Compressed Mode Activation and Configuration Settings – Examples

FiniteFiniteInfiniteInfiniteCM Pattern Repetition

Inter-RAT MCM

2 Inter-RAT MCM’s –the first activates the first pattern, the 2nd

deactivates the first and activates the 2nd

pattern

Physical Channel ReconfigurationInter-RAT MCMCM activation message

Radio Bearer Setup

Physical Channel Reconfiguration



CM configuration message

NoneRSCP and Ec/No, whichever triggers firstRSCPRSCP or Ec/NoMeasurement Quantity for

CPICH

None1e & 1f2d & 2f2d & 2fCM activation/ deactivation events

NoneAfter receiving RBSetup Complete

After receiving RBSetup Complete

After receiving RRCConnectionSetup

Complete

When NW sends CM event triggering

information (MCM)

PeriodicEvent-triggered first,

then periodic once CM activated

Event TriggeredEvent TriggeredReporting

Network DNetwork CNetwork BNetwork A

Notes


5-21



Section 5-21



Call Flow – Network A

For any handover:after ASU complete (CM activated):

• Intra-freq MCM• Inter-RAT MCM

UE Network

RRC Connection Setup Complete

Inter-Frequency MCM (2d, 2f)

Measurement Report (2d)

Physical Channel Reconfig. (CM Config.)

Physical Channel Reconfig. Complete

Inter-RAT MCM (GSM cells, CM Act., 3a)

Measurement Report (3a)

GSM RSSI BSIC Ident.

BSIC Reconfirm.

3 CM Patterns:

Reporting

Event-triggered reporting with adequate thresholds can minimize the number of compressed frames and signaling load, but the settings are more difficult to optimize and the implementation may be more complex.

When to send CM triggering info

Sending CM triggering information immediately after “rrcConnectionSetup Complete”may be too early because Cell_FACH does not require Compressed Mode.

Measurement quantity for CPICH

RSCP is the logical measure to check if it is getting close to the network border. Low Ec/No may mean Pilot pollution or interference, which should be solved via network optimization.It is best to check both RSCP and Ec/No to ensure quality and reduce dropped calls.

CM Configuration Message

Physical Channel Reconfiguration message is typically used.

CM Activation Message

Network A uses inter-RAT MCM to specify GSM neighbors, activate CM, and specify thresholds for Event 3a.


5-22



Section 5-22



Call Flow – Network B

For any handover:after ASU complete (CM activated):

• Intra-freq MCM• Inter-RAT MCM

UE Network

RB Setup Complete

Inter-Frequency MCM (2d, 2f)


Physical Chan. Reconfig. (CM Config & Act.)


Inter-RAT MCM (GSM cells, 3a)


3 CM Patterns:

GSM RSSI BSIC Ident.

BSIC Reconfirm.

Reporting

Event-triggered reporting with adequate thresholds can minimize the number of compressed frames and signaling load, but the settings are more difficult to optimize and the implementation may be more complex.

When to send CM triggering info

Sending CM triggering information immediately after “rrcConnectionSetup Complete”may be too early because Cell_FACH does not require Compressed Mode.

Measurement quantity for CPICH

RSCP is the logical measure to check if it is getting close to the network border. Low Ec/No may mean Pilot pollution or interference, which should be solved via network optimization.It is best to check both RSCP and Ec/No to ensure quality and reduce dropped calls.

CM Configuration Message

Physical Channel Reconfiguration message is typically used.

CM Activation Message

Network B uses Physical Channel Reconfiguration message to configure and activate CM. Another inter-RAT MCM programs the inter-RAT cell info list and specifies thresholds for Event 3a after Physical Channel Reconfiguration Complete.


5-23



Section 5-23



Call Flow – Network C

UE Network

RB Setup Complete

Intra-Frequency MCM (RSCP: 1e, 1f)

Measurement Report (1f)

Physical Chan. Reconfig. (CM Config.)


Inter-RAT MCM (GSM cells, CM Act. 1)

Periodic Measurement Report (BSIC)

Inter-RAT MCM (only the top GSM, CM Act. 2)2 seconds later

GSM RSSI

BSIC Identification

Intra-Frequency MCM (1a, 1b, 1c)

Intra-Frequency MCM (Ec/No: 1e, 1f)

Periodic Measurement Report (RSSI)

GSM RSSI & BSIC Identification

2 CM Patterns:

ReportingEvent-triggered reporting with adequate thresholds can minimize the number of compressed frames and signaling load, but the settings are more difficult to optimize and the implementation may be more complex.To limit signaling load, the CM pattern repetitions are finite for both Network C and Network D (CM is active only ~50% of the time).

When to send CM triggering infoSending CM triggering information immediately after “rrcConnectionSetup Complete” may be too early because Cell_FACH does not require Compressed Mode.

Measurement quantity for CPICHRSCP is the logical measure to check if it is getting close to the network border. Low Ec/No may mean Pilot pollution or interference, which should be solved via network optimization.It is best to check both RSCP and Ec/No to ensure quality and reduce dropped calls.

CM Configuration MessagePhysical Channel Reconfiguration message is typically used.

CM Activation MessageFor Network C, the first inter-RAT MCM specifies the inter-RAT cell info list and activates the first pattern for RSSI periodic measurements. After 2 seconds, the second inter-RAT MCM removes all inter-RAT cells except the highest ranked one and activates the second pattern for BSIC identification. No Event 3a is used because of periodic reporting.


5-24



Section 5-24



Call Flow – Network D

UE Network

RB Setup Complete

Inter-RAT MCM (GSM cells)

Periodic Measurement Report (including intra- and inter-RAT meas.)

CM Activation every 10 seconds

RB Setup (CM Config.)GSM RSSI & BSIC Identification

2 CM Patterns:

Intra-Frequency MCM (Periodic)

Inter-RAT MCM (CM Act.)

480 ms of RSSI meas.4.68 s of BSIC ident.

Then no CM for 4.84 sec

Inter-RAT MCM (GSM cells)

Inter-RAT MCM (CM Act.)

ReportingPeriodic reporting is simpler to implement, but there are many compressed frames and a high signaling load. Network D uses periodic reporting for both intra-frequency and inter-RAT measurements, and the UE only sends one report at a time.To limit signaling load, the CM pattern repetitions are finite for both Network C and Network D (CM is active only ~50% of the time).

When to send CM triggering infoSending CM triggering information immediately after “rrcConnectionSetup Complete” may be too early because Cell_FACH does not require Compressed Mode.

Measurement quantity for CPICHRSCP is the logical measure to check if it is getting close to the network border. Low Ec/No may mean Pilot pollution or interference, which should be solved via network optimization.It is best to check both RSCP and Ec/No to ensure quality and reduce dropped calls.

CM Configuration MessageNetwork D uses Radio Bearer Setup message.

CM Activation MessageFor Network D, CM activation is repeated every 10 seconds by sending an inter-RAT MCM, in which CM is active for 5.16 seconds (480 ms of RSSI measurements and 4.68 seconds of BSIC identification).


5-25



Section 5-25



Examples of Compressed Mode Pattern

88270774X+60488270774X+20388270774X02

TGPL2TGPL1TGDTGL2TGL1TGSNTGCFNTGPRCTGMP

44270774X+20050344270774X502


242427014148X+2104121238778X+2038853770X02


662700148X+48783662700148X82TGPL2TGPL1TGDTGL2TGL1TGSNTGCFNTGPRCTGMP

A

B

C

D

Notes


5-26



Section 5-26



CM Parameter Setting Tradeoffs –Compressed Mode Duration

• Compressed Mode Duration measures how long the Compressed Mode lasts. This depends on:

– TGPRC: Number of Transmission Gap Patterns (TGPs) within the TGP Sequence

– TGPL1 and TGPL2: Duration of the transmission gap patterns

• Too short CM duration indicates insufficient time to complete all inter-RAT measurements.– May result in missed or improper transitions, poor quality, and

dropped calls.

• Too long CM duration indicates too many Compressed Mode frames and incidences of high transmit power.– Reduces network capacity

Notes


5-27



Section 5-27



CM Parameter Setting Tradeoffs –Transmission Gap Density

• Transmission Gap Density measures how frequently Compressed Mode frames are used. This depends on:

– TGPL1 and TGPL2: Duration of the transmission gap patterns – TGD: If TGD = 270, there is only 1 gap within a TGP

• Too small gap density Indicates insufficient inter-RAT measurement frequency.– May result in missed or improper transitions, poor quality, and

maybe dropped calls.

• Too large gap density indicates too frequent Compressed Mode frames and incidences of high transmit power.– Reduces network capacity.

Notes


5-28



Section 5-28



CM Parameter Setting Tradeoffs –TGD and TGL

• TGD – If two gaps are present within a gap pattern, this parameter determines the number of slots between the two consecutive transmission gaps within the TGP.

Small TGD localizes the two consecutive gaps.Large TGD spreads out the two consecutive gaps.

• TGL1 and TGL2– Small TGL allows less time for scanning the other RAT or other

frequency.– Large TGL allows more time for scanning the other RAT or other

frequency.– Recommended TGL setting: 14 (the maximum)

Notes


5-29



Section 5-29



QUALCOMM Recommended CM Patterns

N = Number of GSM neighbors

Recommended patterns:• GSM RSSI

• BSIC identification

• BSIC reconfirmation

Vendor implementation may prevent using these values

X + 54X + 48XTGCFN6 (3 seconds)--T Reconfirm. Abort

-24-N Identity AbortMode 0Mode 0Mode 0RPPMode 0Mode 0Mode 0ITP

000DeltaSIRafter2000DeltaSIR2000DeltaSIRafter1000DeltaSIR1

No changeNo changeNo changeScrambling CodeCS: B; PS: ACS: B; PS: ACS: B; PS: ADL Frame Type

CS: SF/2; PS: HLSCS: SF/2; PS: HLSCS: SF/2; PS: HLSUL CM TypeCS: SF/2; PS: HLSCS: SF/2; PS: HLSCS: SF/2; PS: HLSDL CM Type

=TGPL1= TGPL1= TGPL1TGPL212128 (if N =< 30, else 6)TGPL1---TGD---TGL2

141414TGL1888TGSN

24 + (300/TGPL1) * Min(N, 8)Min(192, 24 * N)6 (if n =< 30, else 8)TGPRC

432TGPMP321TGPSI

BSIC reconfirmationGSM RSSI Measurement

Initial BSIC IdentificationIE

QUALCOMM Recommended CM Patterns

As indicated by the additional important CM parameters shown in this slide, CM is complex.

Both the UE and Node B must be aware of the exact configuration of the L1 during Compressed Mode. To precisely define this configuration, a set of parameters has been created.

These parameters are exchanged between upper layers in the UE and network, and are under the control of the UTRAN.


5-30



Section 5-30



Inter-RAT Compressed Mode Settings –Summary

There are different implementations for:

• Compressed Mode Activation/Deactivation• Compressed Mode Configuration• Inter-RAT Transition Trigger

When considering QUALCOMM’s recommended settings, as provided in this section, the engineer must understand each parameter to optimize each type of network.

Notes


5-31



Section 5-31



Compressed Mode with HSDPA

• Compressed Mode applies to the associated DPCH only.– Frames on HSDPA channels are not “compressed.”

• During the Associated DPCH Compressed Mode gap, the UE is expected to:– Ignore any HS-SCCH or corresponding HS-PDSCH frames that

overlap with DL DPCH compressed mode gap. No ACK/NAK is transmitted corresponding to these frames.

– Not transmit any ACK/NAK or CQI on HS-DPCCH if the respective slots overlap with UL DPCH compressed mode gap.

– Transmit DTX in corresponding CQI slots if the ‘CQI measurement period’ overlaps with DL DPCH Compressed Mode gap.

• HSDPA throughput is affected during Compressed Mode since HSDPA data transmission is stopped during the gap.

Compressed Mode with HSDPA

See 3GPP TS 25.214 Section 6A.3 for details.


5-32



Section 5-32



Frames not received by the UE due to overlap with DL CM gap

HSDPA Frames around Compressed Mode Gaps

No HSDPA data received

ACK/NAK is transmitted but not CQI due to overlap with UL CM gap

Frames not transmitted by the UE due to overlap with UL CM gap

ACK/NAK is not transmitted but CQI may be transmitted (see note)

This HSDPA data is effectively lost since no ACK/NAK is sent.

HSDPA Frames around Compressed Mode Gaps

This slide shows only DL DPCH CM gaps.UL DPCH CM gap is delayed by 1024 chips compared to DL DPCH CM gap. However, UL DPCH gap still overlaps frame 1100 on HS-PDCCH by 256 chips.Tau DPCH is assumed to be 0.Frame 1104 on HS-SCCH is not read because the corresponding HS-PDSCH frame overlaps with DL CM gap.Frames 1104-1106 on HS-PDSCH are not received due to overlap with DL CM gap. Frame 1107 on HS-PDSCH is not received since corresponding HS-SCCH frame overlaps with DL CM gap.In frame 1100 on HS-DPCCH, ACK/NAK is transmitted but not CQI due to overlap with UL CM gap.In frame 1103 on HS-DPCCH, ACK/NAK is not transmitted but CQI may be transmitted but only if CQI feedback cycle is 8ms and CQI repetition factor is 4.HSDPA data in HS-PDSCH frames 1101,1102, 1103 can be considered to be lost even though it is actually decoded by the UE. This is because the ACK/NAK is not transmitted by the UE due to overlap with gap. As a result, the Node B receives DTX in the ACK/NAK slots corresponding to those frames and re-transmits the data.


5-33



Section 5-33



HSDPA to GPRS/EDGE Handover (Call Flow A)

UE NetworkInter-Frequency MCM (2d, 2f)


Radio Bearer Reconfiguration (CM Config.)

Radio Bearer Reconfiguration Complete



GSM RSSIBSIC Identification

BSIC Reconfirmation

3 CM Patterns:

CCO from UTRAN (On HSDPA cell)

Handover Complete (on GPRS/EDGE cell)

Call Flow A

UTRAN supports CM during active HSDPA call.


5-34



Section 5-34



HSDPA to GPRS/EDGE Handover (Call Flow B)

UE NetworkInter-Frequency MCM (2d, 2f)


Radio Bearer Reconfiguration (HS->DCH)

Radio Bearer Reconfiguration Complete



CCO from UTRAN

Handover Complete (on GPRS/EDGE cell)

GSM RSSIBSIC Identification

BSIC Reconfirmation

3 CM Patterns:

Call Flow B

UTRAN does not support CM during active HSDPA call.

In this scenario, UTRAN reconfigures the UE to move it from HS-DSCH to R99 DCH upon receipt of event 2d. Data transfer continues over R99 RAB. Following this, the CM activation and HO procedure is similar to R99.


5-35



Section 5-35



Compressed Mode with HSDPA – Summary

• HSDPA data rate can be affected as a result of Compressed Mode activation.

• Data interruption can be expected during the HS to GPRS/EDGE handover.

• System parameters for events 2d, 2f, and 3a are the same as for R99 UMTS.

• Regular Compressed Mode techniques such as SF/2 or HLS may be used for the associated DPCH.

Notes


5-36



Section 5-36



Inter-System Continuity: Compressed Mode Settings – What Did We Learn?

What are the main parameters for the Compressed Mode settings and how do they affect the data transmission?

What are the implementation differences of some typical inter-RAT Compressed Mode settings, and how do they affect the observed call flow?

How is Compressed Mode implemented with HSDPA?

Notes


6-1

80-W0242-4 Rev DWCDMA (UMTS) Inter-System Network Optimization WorkshopSection 6: Inter-System Continuity – Practical Considerations


Section 6-1




– Practical Considerations6SECTION

Section 6: Inter-System Continuity –Practical Considerations

Notes


6-2



Section 6-2




Describe the main trade-offs to consider when setting the inter-system boundaries.

Estimate inter-system boundaries and thresholds from a network planning perspective.

Describe typical performance evaluation metrics for inter-system reselection and inter-system change.

Notes


6-3



Section 6-3



Setting Inter-System Boundaries –Considerations

When setting inter-system boundaries:

• Maximize UMTS utilization.

• Avoid quality degradation at the boundary.

• Remember reselection and handover boundaries might be different.

Notes


6-4



Section 6-4



Setting Inter-System Boundaries – Trade-offs

Maximize WCDMA service area: • New applications or better service can be offered to more subscribers

(e.g., video telephony, PS384).

• Reduce additional traffic loading on the GSM system, resulting in higher utilization of the new infrastructure.

• At the boundary, WCDMA users may have less reliability, lower Ec/No or RSCP, which may result in dropped calls or access failures.

Maximize WCDMA service quality:• Earlier transitions to GSM layer will avoid low Ec/No or RSCP at the

boundary.

• In the PS domain, earlier WCDMA to GPRS transitions significantly reduce user throughput.

• Limit ping-pongs and their impact on service quality.

Notes


6-5



Section 6-5



Reselection and handover are controlled by different parameters.Different timings and their effects should be considered.

• Reselection

– UE performs LAU/RAU after the inter-system reselection.– Typically 5 to 10 seconds for the entire process.– UE may miss calls until this process is completed.

• Handover

– CM has the greatest effect on quality.– Typically 10 to 20 seconds for the entire process.– PS data throughput is reduced while in CM (HLS).– Coverage is affected in CM (SF/2) due to an increase in the required Tx power

(but limited maximum HPA power).

Ping-pong affects service quality in both cases, because it increases the time when service is affected.

Reselection and Handover Boundaries –Ping-Pong

Ping-Pong

Ping-pong refers to the rapid change between both systems. Ping-pong can be due to incorrect parameter settings (insufficient hysteresis) or irregular coverage.


6-6



Section 6-6



Reselection and Handover Boundaries –Between WCDMA and GSM

• Ping-Pong should be minimized– Reselection: limit the time the UE is unreachable due to ongoing LAU/RAU.– Handover: limit the risk of call drop.

• Reselection earlier than handover– Reduces UMTS effective coverage area in Idle Mode.– Reduces the probability of inter-system handover and CCO; only existing call needs

inter-system change or handover.• Handover earlier than reselection

– Increased UMTS coverage area in Idle Mode.– Call originated or terminated in the transition area will be put in CM right away.

CM is typically not enabled before reaching the alerting stage.

• Handover and reselection at same point– Condition may be fulfilled at same location, but different delays are involved.

• GSM to WCDMA boundaries are not as critical– Service continuity is not affected at the boundary.– Boundary should be set to prevent ping-pong.

Reselection and Handover Boundaries

From WCDMA to GSM

The coverage area in this case is not the absolute coverage area limited by the power assignment on the different channels. The effective coverage area is used to highlight the difference. In either case, the reselection or handover parameters should be set to limit the effective coverage before the absolute coverage area is reached.

From GSM to WCDMA

Boundaries between GSM and WCDMA are set to respect a given hysteresis between GSM and WCDMA to limit ping-pong. Determining the respective reselection and handover boundaries in GSM is not as critical as in WCDMA because GSM coverage is expected to be maintained in the WCDMA area.


6-7



Section 6-7



Reselection and Handover Example

• Reselection and handover threshold, typical delays should be considered.– The difference between reselection area and handover is limited at high load, but increases at lower load.

• Introduction of RSCP-based reselection threshold allows greater flexibility boundary matching.

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

0 10 20 30 40 50 60Relative Time [s]

RSC

P [d

Bm

]

-20

-15

-10

-5

0

5

Ec/N

o [d

B]

RSCP [dBm] r2f [dB] Ec/No Qualmin - SsearchRAT [dB] Reselection Area Handover Area

Reselection and Handover

In this example, the reselection variables are:

Treselection = 1 secQqualmin + SsearchRAT = –10 dB (Ec/No)Reselection area based on 8-second reselection delay

The handover variables are:

R1f = -110 dBm (RSCP)TTT1f = 1.28 sec

Handover area is based on 14-second delay.

In this example, the best match between reselection and handover area is:

Qqualmin + SsearchRAT = –8 dB (Ec/No) or more

This setting is not practical, however, because it creates a high risk of triggering reselection in a loaded condition, or in a multiple cell overlapping area.


6-8



Section 6-8



Challenges –Inter-RAT Timing Trigger

Determine optimal parameter settings for CM operation and inter-RAT transitions (cell reselection / handover / cell change).

Cell Reselection• Thresholds (for WCDMA and GSM/GPRS) to ensure successful and seamless

cell reselection while minimizing ping-pong in cell reselection.

• Thresholds for maintaining acceptable call setup reliability while maximizing the WCDMA coverage.

Connected Mode (Handover / Cell Change)• Minimize time in CM (to minimize transmit power peaks – interference and

smaller SF OVSF code), yet activate CM early enough to allow inter-RAT measurements before calls drop.

• Limit measurement reports for CM activation/deactivation to reduce signaling traffic.

Notes


6-9



Section 6-9



Challenges – Avoiding Ping-Pong Effect

• In Connected Mode, avoid frequent successive activation and deactivation of CM.

– Ensure large enough hysteresis and Time-to-Trigger.– Ensure thresholds are not:

Too high – activates CM too early and results in longer CM duration.Too low – activates CM too late, increasing probability of call drops before inter-RAT transitions.

• In Idle Mode, avoid frequent cell reselection between WCDMA and GSM/GPRS.

– Set (Qqualmin + SsearchRAT), FDD_Qmin, and Qrxlevminproperly.

– Ensure large enough hysteresis between systems: Offset and Timing.

– Treselection also affects intra-frequency cell reselection.

Challenges – Avoiding Ping-Pong Effect

When W2G and G2W are supported both ways, one needs to avoid frequent handovers back and forth.

Other cell reselection parameters that affect intra-frequency handover include:

QqualminQrxlevminQhyst1Qoffset1Treselection

Set these cell reselection parameters to optimize both intra-frequency and inter-RAT cell reselections.


6-10



Section 6-10



Network Planning –Inter-system Boundaries and Thresholds

• Only thresholds available, no time considerations

• Contours can be estimated at the intended boundary and within the network

– RSCP

– Ec/No

– Eb/Nt or correlated values

– UE Tx Power (and DPCH Power)

Notes


6-11



Section 6-11



Network Planning – Estimating Inter-RAT Boundaries and Threshold

• Network planning inter-RAT boundariesconsiderations:– WCDMA coverage

RSCP

Ec/No

– WCDMA coverage with CM

Eb/Nt (Uplink and Downlink) considering the power effect of CM SF2

UE Tx Power (and DPCH Power)

– GSM/GPRS/EDGE coverage

RSSI

GSM/GPRS Coverage

This discussion assumes that GSM/GPRS coverage is at least as good as WCDMA. Reasons behind this assumption include:

GSM sites, or a subset, typically are reused for WCDMA deployment.GSM/GPRS typically is deployed at lower frequencies (900 or 1800 MHz), giving it a propagation advantage over WCDMA.

In-band deployment has no frequency advantage on propagation. In this case, WCDMA voice has an advantage over GSM voice. To compare data, one must consider the target data rate.


6-12



Section 6-12



Sample Area for Observation

Fragmentation observed in most plots is due to:

• Terrain

• Dense population

Area of Observation

Only a sample of the boundary is considered in this study. For completeness, the same variable should be observed over the entire area boundary. Thin coverage is observed over the target area. Coverage statistics are shown below and are representative of early UMTS deployment, where site count is minimized.

Coverage by Signal Level CDF of Target Coverage AreaBetter Than:

-88 dBm 57.7 %

-98 dBm 94.5 %

-108 dBm 99.4 %


6-13



Section 6-13



Reselection Boundary Estimation

Reselection boundary can be estimated based on (Qqualmin + SsearchRAT) threshold.

Unloaded, the threshold can be selected to move the boundary outside the target polygon.

Reselection Boundary Estimation Based on Ec/No

A threshold of –12 dB will be exceeded in only 3.7% of the area. With a Treselection value of 1 second or more, reselection to GSM should be very infrequent. Until Treselection for inter-system reselection is implemented, Treselection should be kept at no more than 1 second, to avoid affecting intra-frequency reselections.

An area where Ec/No is < –12 dB within the target coverage area should either be optimized or shifted to a location with lower traffic probability.


6-14



Section 6-14



Reselection Boundary Estimation – Loaded

At high load, Ec/No-based boundary will cause numerous inter-system reselections within the target coverage.

Ec/No Based Reselection at Higher Load

When load increases in the network, the probability of falling below the threshold increases to 28% of the target area. Loaded, the original threshold would not permit using the WCDMA layer efficiently.

To address this, it would be beneficial to use the newly approved RSCP reselection threshold.


6-15



Section 6-15



Reselection Boundary Verification

To ensure that the UE reselects before failing suitability, compare both Ec/Noand RSCP contours.

Reselection Boundary

WCDMA not suitable

(Qrxlevmin)

Ec/No and RSCP Contours

Setting the Ec/No reselection threshold to a high level (–12 dB in this example) at the coverage edge increases the risk of failing the Qrxlevmin criteria. In this case, the UE will start searching for an alternate network before the reselection. While the UE is performing this search, any incoming or outgoing calls may fail.


6-16



Section 6-16



Handover and Reselection Boundary Comparison

Compare Ec/Noand RSCP contours to estimate the respective boundaries for handover/CCO and reselection.

Without time considerations, this comparison is limited.

Reselection Boundary

Handover Boundary

Notes


6-17



Section 6-17



Effective Coverage Consideration

Consider required transmit power (UL and DL) to verify if the handover boundary is compatible with the higher transmit power required for SF/2.

Eb/Nt and Required power

During Monte-Carlo simulation, network planning tools estimate the required transmit power to maintain the target Eb/Nt. From this, the achieved Eb/Nt and the required power are correlated variables. During network planning it is easier to look at the required power, because this can be easily scaled up or down as needed. To estimate if CM will work at the boundary, simply deratethe maximum transmit power by 3 dB.

The same estimation would not be practical for considering the achieved Eb/Nt or the Eb/Ntmargin, in the Downlink in particular, because it would be affected differently based on the handover state.


6-18



Section 6-18



Performance Evaluation Metrics

Performance evaluation metrics for inter-system reselection and inter-system change:

• Different metrics for reselection and handover/CCO performances.

• Consider the performance of both to finalize the settings.

Notes


6-19



Section 6-19



Exercise: Performance Metrics for Inter-System Reselection

• Evaluate inter-RAT cell reselection performance, using the following information from the UE logs:– Cell Reselection Time– Call Setup Success Rate at the boundary– Poor Services Areas at the boundary– Ping-pong events– WCDMA usage

• Evaluate inter-RAT handover/CCO performance, using the following information from UE logs:– Handover/CCO Success Rate– Call Drop Rate– Handover/CCO Delay– Quality (BLER)– Duration of CM– UE Transmit Power– For PS, throughput over the boundary

Notes


6-20



Section 6-20



Inter-RAT Performance Evaluation

• Cell reselection success rate• Cell reselection ping-pong rate• Cell reselection time• Call setup success rate after

reselection• DRX failure rate• Probability of unsuitability• Probability of camping on W• Probability of camping on G

• Qsearch_I• FDD_Qmin• FDD_Qoffset

GSM/GPRS to WCDMA Cell Reselection Test

• Cell reselection success rate• Cell reselection ping-pong rate• Cell reselection time• DRX failure rate• Probability of unsuitability• Probability of camping on W• Probability of camping on G

• S-SearchRAT• Qqualmin• Qrxlevmin• Qhyst1• Qoffset1• Treselection

WCDMA to GSM/GPRS Cell Reselection Test

Test MetricsApplicable System ParametersTest Name

Notes


6-21



Section 6-21



Cell Reselection Success Rate

Number of successful reselections compared to the total number of attempted reselections.

• No unique RRC message identifies attempted reselections• Reselection attempts can be identified by internal UE messages

– Example based on QUALCOMM QCTest UE

– EVENT_WCDMA_TO_GSM_RESELECTION_START

• Reselection failures include different cases– UE declares OOS before reselecting

– UE cannot camp on the intended GSM cell

– Reselection failures can be identified by UE internal messagesExample based on QUALCOMM QCTest UEEVENT_WCDMA_TO_GSM_RESELECTION_END Event Failure (failure cause deleted)

RRC_CPHY_OUT_OF_SERVICE_AREA

Notes


6-22



Section 6-22



Cell Reselection Ping-Pong Rate

Ping-pong

• Rapid change from cell/technology A to cell/technology B, then back to cell/technology A, when only the A to B change was expected.

• Ping-pong rate: Number of inter-system ping-pongs compared to the number of expected inter-system reselections.

• Easy to estimate the expected number of reselections over a coverage edge route, if the route is well defined.

• For coverage-limited areas within the WCDMA, reselections are not expected.

– Ping-pong is not the best metric. Detailed evaluation of RF signal can provide more information.

Notes


6-23



Section 6-23



Cell Reselection Time

Cell Reselection Time

• Measured from the reselection attempts to the completion of LAU/RAU on the target system.

• LAU/RAU should be included because the UE might not receive a call until the procedure is completed, depending on paging scheme.

• Usage of the WCDMA system should be estimated.

• Coverage edge and embedded coverage should have different targets:– At coverage edge, ping-pong and suitability should be prioritized.– In embedded coverage, the temporary reselection to GSM should be

limited, while maintaining good performance.

Notes


6-24



Section 6-24



Cell Reselection Time (continued)

• Reselection time: Calculated average over entire sample.

• Could camp on WCDMA (GSM): Average of time camped on WCDMA (GSM) over average of total time.

Timing and Drive Test

To accurately compare timing during inter-system transition optimization, it is necessary to drive a documented and repeatable route.


6-25


Section 6: Inter-System Continuity – Practical Considerations


Section 6-25



Service Effects on KPIs

Probability of unsuitability

• Unsuitability is defined as Ec/No < Qqualmin or RSCP < Qrxlevmin.

• Unsuitability indicates a delayed reselection with possible effect on call origination or termination.

Alternative

• Call origination/termination success rate.

• More accurately represents the user experience, but more time consuming to determine.

Notes


6-26



Section 6-26




• As defined for Idle Mode reselection• Qsearch_I• Qsearch_P• FDD_Qmin,• FDD_Qoffset

GPRS Packet Idle mode to WCDMA Cell Reselection Test

• Inter-RAT handover success rate• Inter-RAT handover delay• Call drop and BLER analysis• Call drop rate when the Compressed

Mode (CM) is active• Duration of Compressed Mode

activation• UE Tx power

• Measurement related parameters: Event 2D/2F/3A parameters and Event 1E/1F parameters

WCDMA to GSM Voice Call Handover Test

• CCO Success Rate• CM Duration• Throughput• DL BLER During CM

• Event 1E/1F/2D/2F/3A parameters

• CELL_DCH CELL_FACH Inactivity Timer

WCDMA to GSM Data Call Handover Test (CCO) During Download/Upload

Test MetricsSystem Parameters GroupTest Name


Cell Change Order is the data equivalent to handover from UTRAN in AMR calls.

UE Tx power is an important parameter to examine. If the UE Tx power is too high, the increased interference affects the Uplink capacity. UE Tx power also indicates if UE the can maintain the Uplink quality before the handover.


6-27



Section 6-27



Inter-System Handover or CCO

• Number of successful inter-system handovers compared to the total number of attempted inter-system handovers– Inter-system handover (voice) attempts is based on reception of

handover from UTRAN message.

– Inter-system handover failure is based on the absence of Handover complete message on the target RAT.

• CCO is based on:– Attempts: Reception of CCO.

– Failures: No MAC or RLC data received on the target RAT.

• Similar definition (handover) applies from GSM to WCDMA.

Notes


6-28



Section 6-28



Inter-System Handover/Change Delays

ISC delay can be estimated from the last or first CM activation:• From last CM activation: Useful for embedded coverage test where boundary is unknown. In

this case, unsuccessful CM should be counted.

• From first CM activation: Captures and optimizes intermediate CM activations with a single KPI.

Inter-system Handover/Change Delay

In addition to the delay, the number of CM activations or deactivations should be recorded for completeness. In this case, during the optimization, both values should be minimized.

Alternatively, the delay can be measured from the first CM activation. In this case, only one metric should be optimized.


6-29



Section 6-29



Throughput

Over known boundary:• Throughput should be measured over the entire download/upload.

• Capture the entire experience with a single KPI. Consider the time/throughput in:

– WCDMA

– WCDMA CM

– GSM/GPRS

• Valid only if the tests are done over a repeatable route centered around the boundary.

In embedded coverage:• Throughput over entire download/upload possible.• Resulting KPI not as easy to interpret for optimization.

Notes


6-30



Section 6-30



Common Handover/CCO Failures

• RL failure before or during Inter-System Change (ISC)– Typical of delayed ISC

Threshold too lowBSIC reconfirmation too slow

• BSIC identification fails– Sub-optimal Neighbor List

Frequency reuse on GSM too tight at border

– Rapid change of RF conditionsRequires GSM cell coverage optimization

• Target system not acquired after the ISC– WCDMA to GSM

Sub-optimal Neighbor ListRapid change of RF conditions

– GSM to WCDMARapid change of RF conditionsISC triggering too early

Notes


6-31



Section 6-31



Inter-System Continuity: Practical Considerations – What Did We Learn?

How can we estimate inter-system boundaries and thresholds from a network planning perspective?

What are some typical performance evaluation metrics for inter-system reselection and inter-system changes, and how do we collect them?

How can we determine which parameter set performs best?

How can we troubleshoot failure events?

What is the failure recovery mechanism?

Notes


6-32



Comments/Notes


7-1

80-W0242-4 Rev DWCDMA (UMTS) Inter-System Network Optimization WorkshopSection 7: Inter-System Continuity – Hands-On Module


Section 7-1




– Hands-On Module7SECTION

Section 7: Inter-System Continuity –Hands-On Module

Notes


7-2



Section 7-2




Describe how to design and conduct a drive test.

Determine how to analyze the test data and derive key performance indicators for inter-RAT cell reselection, inter-RAT handover, etc.

Notes


7-3



Section 7-3



Drive Test – Objectives

• Conduct a drive test to evaluate inter-system continuity and verify:

– Did the radio link quality degrade at the inter-RAT boundary or during the inter-RAT transition?

– Were there any inter-RAT cell reselection or cell change ping-pong events?

Drive Test Objectives

A drive test is a critical way of studying wireless networks and is used frequently in various system performance evaluations, from voice to data, from intra-frequency to inter-frequency and inter-system, and others. This workshop concentrates on the aspects of inter-system continuity performance evaluation. To test inter-system continuity performance, certain preconditions should be met. In particular, the test system should be stable, equipment should function as designed, the system should have normal traffic, and no special events (such as sudden interference increase due to an external jammer) should occur.

In addition to network performance evaluation, a drive test also is often used to troubleshoot problems (and problem areas) of a wireless network. These types of tests, however, are not discussed in this workshop.


7-4



Section 7-4



Drive Test – Key Steps

Key Steps of Conducting a Drive Test:

1. Specify the test scenarios and corresponding objectives.– Long AMR test evaluates inter-RAT handover.– Idle test evaluates inter-RAT cell reselection.– PS data call (with FTP) evaluates PS data continuity at the

inter-RAT boundary.

2. Select the metric routes (i.e., test routes).

3. Define data collection profiles (i.e., log masks).

4. Setup test systems and define test cases.

5. Conduct tests.

Note: More details are provided in the Appendices.

Notes


7-5



Section 7-5



Drive Test – Scenarios and Objectives

Scenarios should match evaluation objectives.

• Idle Mode scenarios (with CS and/or PS attached) test:

– Cell reselection duration, ping-pong events, WCDMA/GSM coverage, duration of poor services

• Connected Mode scenarios in CS domain test:

– Handover success rate, duration, Compressed Mode duration, success rate, link quality during Compressed Mode, and call drop rate

• Connected mode scenarios in PS domain test:

– Inter-rat transition success rate, duration, ping-pong events, and data throughput during the transition

Scenarios and ObjectivesUMTS coverage boundaries are identified by the cell reselection and handover locations. Theses two types of boundaries can be different.The UE experiences poor service if the serving cell Ec/No is below a certain threshold for a certain period of time. Normally, the threshold is set to Qqualmin. Remaining in an area of poor service increases the probability of the UE missing pages from the RAN. The longer the UE stays in a poor service condition, the higher the probability of missing pages.Cell reselection duration influences the probability of missing pages. This duration is the latency for the UE to acquire the new RAT system and complete registration on the new system. During this period, the UE cannot access the RAN because it is on the new RAT system while the pages are sent over the old RAT system. The longer the duration, the higher the probability of missing pages. Unnecessary inter-RAT cell reselections—such as ping-pong events—prolong the time a UE remains in cell reselection, which increases the probability of missing pages.Inter-RAT handover (or cell change for PS) affects the continuity of call services. The handover (or cell change) duration extends from the initiation of the handover command (or cell change order) to the completion of registration on the new RAN. During this period, call service is discontinued. The shorter the service, the smaller the call service interruption; hence, the less service quality degrades.Compressed Mode also affects call service quality, such as potential higher BLER, potential call drops, and/or lower data throughput. Reducing the Compressed Mode duration can help minimize call service quality degradation.In summary, handover (or cell change) ping-pong causes unnecessary handovers (or cell changes) and can also affect call service quality. These events should be avoided as much as possible.


7-6



Section 7-6



Analysis – RF

• IRAT performance is influenced by RF conditions.– Some operators use IRAT to fix Pilot pollution and

coverage holes in WCDMA networks.– RF issues should be resolved through further RF

optimization.

• RF observation– Inter-RAT boundaries, WCDMA/GSM coverage on the

metric route, any Pilot pollution analysis or Neighbor List analysis, etc.

RF Analysis

RF observation should always be the first step of any test analysis. RF observation is based on the scanner data collected in the scanner logs during the test. Reviewing this data serves two main purposes:

Get an overview of the WCDMA coverage on the test route, including average Ec/No and RSCP strength, and best cell change frequency.Check for any abnormalities in the RF environment, such as call drops or handover failures, which can be a root cause of various performance issues.

The following plots and statistics are included in the RF observation:

Best serving PSC map on the test routeBest serving cell RSCP map on the test routeBest serving cell Ec/No map on the test routeGSM serving cell Rxlev map on the test route


7-7



Section 7-7



RF Observations – Best Cell PSC

Start

End

Strong overshooting PSC 79 (~6 miles away) in the southern part of the route. Since inside the GSM area, might not be an issue.

Several strong servers in this area, ASET size = 2,3 most of the time. No Pilot pollution observed.

PSC 3 creates NL issues

PSC 10 gets very strong for a couple of seconds in this location and then deteriorates quickly, causing call drops.

Best Cell PSC

The best cell PSC map shows the changes of the best cell along the test route. Frequent cell changes indicate a rapidly varying RF environment, which can cause frequent cell reselection or frequent handover. Observing a second- or third-tier Pilot indicates Pilot overshooting in the test area, which can potentially cause call drops.

To display the best cell PSC map:

1. Open the scanner log in Actix and find the attribute:3G UMTS Nth Best CPICH_Scan_SC_SortedBy_EcIoCPICH_Scan_SC_SortedBy_EcIo_0.

2. Drag the attribute to a map.3. To copy the map, right-click the map and select “copy to clipboard.”4. To copy the legend, right-click the legend on the left side of the map and select “copy

legend to clipboard.”


7-8



Section 7-8



RF Observations – Best Cell RSCP Map

9.5–94.6

Std. Dev.(dB)

Average (dBm)

RSCP gradually weakens towards the GSM area.

Start

End

Scanner Bes t Server RSCP

( Below -115.00 (0)

( >= -115.00 to < -105.00 (85)

( >= -105.00 to < -95.00 (132)

( >= -95.00 to < -85.00 (178)

( >= -85.00 to < -75.00 (54)

( A bove -75.00 (1)

Best Cell RSCP Map

The best cell RSCP map shows RF signal attenuation along the test route. As the UE moves away from a WCDMA coverage area, the RSCP normally gets weaker. Weak RSCP spots in a WCDMA coverage area often indicate a coverage hole, which could cause various performance issues.

To display the best cell RSCP map:

1. Open the scanner log in Actix and find the attribute:3G UMTS Nth Best CPICH_Scan_RSCP_SortedBy_EcIoCPICH_Scan_RSCP_SortedBy_EcIo_0. Then drag the attribute to a map.

2. To obtain the best cell RSCP distribution statistics, find the same attribute, right-click it, and select “Display on Workbook.” Click the worksheet named “Statistic Formatted Data”for the distribution statistics.

3. To copy the map, right-click the map and select “copy to clipboard.”4. To copy the legend, right-click the legend on the left side of the map and select “copy



7-9


Section 7: Inter-System Continuity – Hands-On Module


Section 7-9



RF Observations – Best Cell Ec/No Map

3.2–8.5

Std. Dev.(dB)

Average (dB)

Ec/No degrades slower than RSCP, as expected for a coverage boundary area. Overall, good Ec/Noinside the WCDMA area.

Start

End

Scanner Best Server EcNo

( Below -18.0 (0)

( >= -18.0 to < -16.0 (0)

( >= -16.0 to < -14.0 (23)

( >= -14.0 to < -12.0 (46)

( >= -12.0 to < -9.0 (111)

( >= -9.0 to < -6.0 (140)

( Above -6.0 (130)

Best Cell Ec/No Map

The Ec/No map shows interference on the test route.

To display the best cell Ec/No map:

1. Open the scanner log in Actix and find the attribute:

3G UMTS Nth Best CPICH_Scan_Ec/No_SortedBy_EcIoCPICH_Scan_Ec/No_SortedBy_EcIo_0. Then drag the attribute to a map.

2. To obtain the best cell Ec/No distribution statistics, find the same attribute, right-click it, and select “Display on Workbook.” Click the worksheet named “Statistic Formatted Data”for the distribution statistics.

3. To copy the map, right-click the map and select “copy to clipboard.”

4. To copy the legend, right-click the legend on the left side of the map and select “copy legend to clipboard.”


7-10



Section 7-10



RF – GSM Serving Cell RxLev Map

Strong GSM coverage along the route.

Start

End

Good GSM coverage

GSM Serving Cell RxLev

( Below -100 (0)

( >= -100 to < -95 (4)

( >= -95 to < -90 (9)

( >= -90 to < -80 (328)

( >= -80 to < -70 (239)

( >= -70 to < -60 (67)

( Above -60 (13) 7.2–80

Std. Dev.(dB)

Average (dBm)

GSM Serving Cell RxLev Map

The GSM Rxlev map shows the coverage of the GSM network along the test route.

To display the GSM Rxlev map:

1. Open a GSM only Idle Mode log in Actix and find the attribute:GSM GSM Downlink Measurements ServRxLevEither. Then drag the attribute to a map.

2. To obtain the RxLev distribution statistics, find the same attribute, right-click it, and select “Display on Workbook.” Click the worksheet named “Statistic Formatted Data” for the distribution statistics.




7-11



Section 7-11



RF – Summary

• Is the WCDMA coverage boundary observed?• Is the average WCDMA signal strong?• Is the average GSM signal strong?• Are there any overshooting Pilots?• Are there any Pilot pollution spots?• Are there any missing Neighbor List (NL) issues?• How many RNC/ULA/URA boundary crosses are

on the route?

Terms

ULA – UTRAN location area

URA – UTRAN routing area


7-12



Section 7-12



RF – Recommendations

Based on the RF Analysis:

• Should Neighbor Lists be tuned?

• Does Pilot pollution need to be addressed?

– Is there an overshooting Pilot that needs to be addressed?

• Are additional sites needed?

• Are IRAT boundaries appropriate?

Notes


7-13



Section 7-13



Analysis – Inter-RAT Cell Reselection

• Analysis of the results of inter-RAT cell reselection

– W G cell reselection and G W cell reselection

Inter-RAT Cell ReselectionA comprehensive inter-RAT cell reselection analysis should include the following information:1. Inter-RAT cell reselection parameter.

A performance analysis is not valid if the corresponding parameters are predetermined. The parameters recorded here will be the basis of changes derived from the analysis.

2. Performance metrics definitions.3. WCDMA to GSM cell reselection analysis, which includes:

Inter-RAT cell reselection map Performance statisticsCell reselection delay distributionUE Ec/No and RSCP statisticsObservations

4. GSM to WCDMA cell reselection analysis, which includes: Inter-RAT cell reselection map Performance statisticsCell reselection delay distributionObservations


7-14



Section 7-14



Inter-RAT Cell Reselection –System Parameters Verification

System Parameters Verification

System parameters are extracted from the UE log files collected during the drive test. The log files can be imported into Actix, where the parameters can be extracted from the information elements (IE) in the over-the-air (OTA) messages exchanged between the network and the UE. This information can be viewed in the Actix “Protocol Stack Browser.” To open the protocol stack browser: select “View” on the menu bar, select “protocol stack,” then select “UMTS Radio Interface and Protocol Signaling” (see next page). The parameter values also can be obtained from the Actix attributes, as shown here:

From 3G UMTS Uu-RRC BCCH-BCH SysInfoType1:DRX Cycle Length Coefficient: Uu_RRC_CN_DomainSysInfo_cn_DRX_CycleLengthCoeff

From 3G UMTS Uu-RRC BCCH-BCH SysInfoType3:q-QualMin: Uu_RRC_modeSpecificInfo_fdd_q_QualMinq-RxlevMin: Uu_RRC_modeSpecificInfo_fdd_q_RxlevMins-SearchRAT: Uu_RRC_RAT_FDD_Info_s_SearchRATt-Reselection-S: Uu_RRC_CellSelectReselectInfoSIB_3_4_t_Reselection_Sq-Hyst-1-S: Uu_RRC_CellSelectReselectInfoSIB_3_4_q_Hyst_l_S

From GSM Neighbor Cell Info:FDD_Qmin: Uu_FDD_Qmin


7-15



Section 7-15



Inter-RAT Cell Reselection –Parameter Settings

4 dBSsearchRAT

7 (1.28 s)DRX Cycle Length

2 dBQhyst1

–18 dBQqualmin

1 sTreselection

0 (–infinity)FDD_Qoffset

7 (always)QSearch_I

–10 dBFDD_Qmin

–115 dBmQrxlevmin

Operator SettingsTypical QUALCOMM RecommendationsParameter Name

Parameter List Table

Because inter-RAT cell reselection behavior is fairly well known, typical recommended parameter settings can be used as a reference (or baseline) for actual network parameter settings. Using this established baseline, you can devote more attention to the performance analysis of parameters that differ significantly from the recommended settings.

Parameters extracted from OTA messages are compared with the system targets to detect any inconsistencies.

To find FDD_Qoffset and Qsearch_I:

1. Open the protocol stack browser: right-click and select “SuperStream_01” “Protocol stack browser” ”UMTS Radio Interface and Protocol Signaling.”

2. Locate the layer 3 message “RR System Information Type 2qtr.” The parameter values of FDD_Qoffset and Qsearch_I can be found in the message shown in the bottom half of the browser.

Similarly, the DRX Cycle Length Coefficient parameter can be found in the RRC message “BCCH-BCH SysInfoType1.” The parameters q-QualMin, q-RxlevMin, s-SearchRAT, t-Reselection-S, and q-Hyst-1-S can be found in the RRC message “BCCH-BCH SysInfoType3.”


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Section 7-16



Inter-RAT Cell Reselection –Definitions

• WCDMA GSM reselection delay

– Time elapsed from when the UE first acquires the serving GSM cell signal to the Routing Area Update Complete in GSM.

• GSM WCDMA reselection delay

– Time elapsed from when the UE first acquires the serving WCDMA cell Pilot to Location Updating Accept in WCDMA.

• Ping-pong

– Additional GSM WCDMA or WCDMA GSM reselection.– Penalty: UE is unreachable during the transition period of GSM WCDMA

and/or WCDMA GSM reselections.

Notes: WCDMA GSM and W G are used interchangeably. GSM WCDMA and G W are used interchangeably

Notes


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Section 7-17



Inter-RAT Cell Reselection –Definitions (continued)

Time UE is unable to receive calls • W G reselection delay• G W reselection delay

Poor service area• The UE is considered to be in a poor service area when

the serving cell Ec/No stays below a certain threshold for a specified period of time, or longer.

Notes


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Section 7-18



Inter-RAT Cell Reselection –Analysis Flow Chart

Inter-RAT Cell Reselection Map

UE Unsuitable-Of-Service Duration

Histogram

UE Unsuitable-Of-Service Map

UE Inter-RAT Idletest logs

(*.dlf)

RSCP Distribution Before W2G Reselection

Ec/No Distribution Before W2G Reselection

Actix

Inter-RAT Cell Reselection Duration

Best Server (Scanner) Map

Scanner file*.sd5 Actix

Analysis Flow Chart

The drive route log files collected from the UE in Idle Mode are loaded into a UE post-processing and analysis tool, such Actix. Actix produces geographical maps of key performance metrics including:

Inter-RAT cell reselection map, which shows the WCDMA and GSM transition area (or boundaries) in Idle Mode. Compare this map with the inter-RAT handover map to verify the differences between the two transition boundaries.UE Out-Of-Service map, which shows locations where a UE may be unable to receive pages from the network. The OOS is normally due to bad RF signal or inter-RAT transition. Inter-RAT cell reselection duration histogramWCDMA Ec/No distribution before the cell reselectionWCDMA RSCP distribution before the cell reselectionUE Out-Of-Service duration histogram


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Section 7-19



Analysis – Inter-RAT Cell Reselection: WCDMA to GSM Analysis


– W G cell reselection

WCDMA to GSM Cell Reselection

WCDMA to GSM Cell Reselection analysis includes:

Inter-RAT cell reselection map Performance statisticsCell reselection delay distributionUE Ec/No and RSCP statisticsObservations


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Section 7-20



Inter-RAT Cell Reselection –WCDMA to GSM Reselection Map

WCDMA

GSM

WCDMA to GSM Reselection Map

To display the WCDMA to GSM cell reselection locations in Actix:

1. Select the attribute:Super Streams SuperStream01 Queries Bin Queries

W2G_Cell_Reselection.2. Drag the attribute to the map.3. To copy the map, right-click the map and select “copy to clipboard.”4. To copy the legend, right-click the legend on the left side of the map and select “copy



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Section 7-21



Inter-RAT Cell Reselection –WCDMA to GSM Performance Statistics

0.3Average Number of Poor Service Occurrences per Run)

620Average Run Duration (seconds)

17.95Average W G Delay (seconds)

13.55Average Poor Service Duration (in seconds) per Occurrence

0

10

10

Value

Number of W G Cell Reselection Ping-pong Evens per Run

Number of W G Cell Reselections

Number of Runs

WCDMA to GSM Performance StatisticsThe average run duration can be obtained by selecting the customized query: Super Streams SuperStream01 Queries Crossbar Queries Run_Statistics, then display the query on the workbook. The workbook displays the length of each run. Calculate the average run length.

The number of W G cell reselections can be obtained by the customized query “W2G_Cell_Reselection,” as shown on the pervious page.

Using Actix, the Average W G delay can be obtained by selecting the customized query: Super Stream SuperStream01 Queries Crossbar Queries W2G_Cell_Reselect_Delay_Stats. Then display the query in workbook.

The number of W G Cell Reselection Ping-pong events per run can be obtained by dividing the difference of “Number of W G Cell Reselection” and “Number of Runs” by the “Number of Runs.”

The total number of Poor Service occurrences can be obtained by selecting the customized query: Super Stream SuperStream01 Queries Crossbar Queries Poor Service Statistics. Then display the query in workbook. The average number of Poor Service Occurrences per run can be obtained by dividing it by the Number of Runs.

The average Poor Service Duration per occurrence can be obtained by displaying the “Poor Service Statistics” query on the workbook.

Note: In the “Poor Service Statistics” query, the default Ec/No threshold for poor service is –18 dB and the default duration threshold is 12 seconds. To change the thresholds, select the query: Super Stream SuperStream01 Queries Crossbar Queries Poor Service Statistics, then right-click it to select “Edit Analysis Definition.” Select the statistics “Average Poor Service Duration,” click “Edit Statistics,” then click “Edit” in the new pop-up window to change the computation formula. In particular, change the thresholds to the desired values. After the changes, click “OK” to return to the previous window. Do the same change to the statistic “Total Poor Service Occurrence Counts.”


7-22



Section 7-22



W G cell reselection delay was long, averaging 17.95 sec.

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W2G Delay PDF W2G Delay CDF

Inter-RAT Cell Reselection –WCDMA to GSM Cell Reselection Delay

WCDMA to GSM Cell Reselection Delay

To obtain the W G cell reselection delay histogram:

1. Select the customized Actix query: Super Stream SuperStream01 Queries Crossbar Queries “W2G_Cell_Reselect_Delay_Stats.”

2. Right-click the query and select “display the result in the workbook.”3. Copy histogram numbers (row 2, columns B to N) in the workbook to the Excel object (to

row 3) embedded in this slide.

The PDF/CDF plots will be automatically updated.


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Section 7-23



Inter-RAT Cell Reselection –Distribution of Poor Service Durations

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Poor Service Duration PDF Poor Service Duration CDF

Distribution of Poor Service Durations

To obtain the W G Poor Service duration histogram:

1. Select the customized Actix query: Super Stream SuperStream01 Queries Crossbar Queries “Poor Service Statistics.”

2. Right-click the query and select “display the result in the workbook.”3. Copy histogram numbers (row 2, columns B to N) in the workbook to the Excel object (to

row 3) embedded in this slide.

The PDF/CDF plots will be automatically updated.


7-24




Section 7-24



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<=-18 -15 -12 -9 -6 >6

CPICH Ec/No (dB)

PD

F/C

DF

W2G Ec/No PDF W2G Ec/No CDF

Inter-RAT Cell Reselection – Serving Cell Ec/NoDistribution Before Reselection

The serving cell Ec/No in the 10-second window before W G.

Serving Cell Ec/No Distribution Before Reselection

To obtain the Ec/No statistics:

1. Use the customized Actix query “W2G_Cell_Reselect_EcNo_Stats” to produce the Ec/No

histogram for each W2G cell reselection event in a workbook.

2. Copy the workbook contents (except header) in the spreadsheet object embedded in this slide.

The PDF and CDF plot will be updated automatically.

Note: The Ec/No measurement varies by UE implementation. For instance, the QUALCOMM UE chipsets provide two different Ec/No measurements – each has a different filtering/integration period. Actix, however, shows only one of the measurements (referred to as the “finger”measurement, and it is the weaker one). This illustrates the caution that should be applied when comparing the RF measurements of different brands of UEs.


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Section 7-25



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CPICH RSCP (dBm )

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W2G RSCP PDF W2G RSCP CDF

Inter-RAT Cell Reselection – Serving Cell RSCP Distribution Before Reselection

Shows the serving cell RSCP in the 10-second window before W G.

Serving cell RSCP is slightly lower in Set B.

Serving Cell RSCP Distribution Before Reselection

To obtain RSCP statistics:

1. Use the customized Actix query “W2G_Cell_Reselect_RSCP_Stats” to produce the RSCP histogram for each W2G cell reselection event in a workbook.

2. Copy the workbook contents in the spreadsheet object embedded in this slide.


Note: Actix cannot decode the RSCP information from the CAIT log for MSM6275.


7-26



Section 7-26



Inter-RAT Cell Reselection –WCDMA to GSM Observations

• How many ping-pong events are observed?– What are the causes of the ping-pong events?

• How long are the W G cell reselection delays?– What accounts for the majority of the delays?– What are the causes?

• Are there any missing neighbors (in both WCDMA and GSM)?

• What causes the UE to experience poor service?

• Are there any delayed or early W G cell reselections?– What are the causes?

Notes


7-27



Section 7-27



Analysis – Inter-RAT Cell Reselection: GSM to WCDMA Analysis


– G W cell reselection

GSM to WCDMA Cell Reselection

GSM to WCDMA cell reselection analysis includes:

Inter-RAT cell reselection map Performance statisticsCell reselection delay distributionObservations


7-28



Section 7-28



Inter-RAT Cell Reselection –GSM to WCDMA Reselection Map

GSM

WCDMA

There was no ping-pong.

GSM to WCDMA Reselection Map

To display the GSM to WCDMA cell reselection locations in Actix:

1. Select the attribute: Super Streams SuperStream01 Queries Bin Queries G2W_Cell_Reselection. Then drag the attribute to the map.




7-29



Section 7-29



Inter-RAT Cell Reselection –GSM to WCDMA Performance Statistics

0Average Number of Poor Service Occurrences per Run

0Average Poor Service Duration (in seconds) per Occurrence

620Average Run Duration (seconds)

6.87Average G W Reselection Delay (seconds)

0

10

10

Value

Number of Ping-pong Events per Run

Number of G W Reselections

Number of Runs

G W cell reselections were successful and occurred on the boundary consistently.

GSM to WCDMA Performance Statistics

The number of G W reselections can be obtained from the location map shown earlier.

The number of ping-pongs per run can be derived from the difference of “Number of G W Reselections” and “Number of Runs.”

The average G W cell reselection delay can be obtained by displaying the customized query “G2W_Cell_Reselect_Delay_Stats” in the “Statistics Explorer” in Actix.

Actix has difficulty identifying the G W rejects.


7-30



Section 7-30



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Inter-RAT Cell Reselection –GSM to WCDMA Cell Reselection Delay

G W reselection delay was consistent and within the expected range.

GSM to WCDMA Cell Reselection Delay

To view the G W cell reselection delay histogram:

1. Select the customized Actix query: Super Stream SuperStream01 Queries Crossbar Queries “G2W_Cell_Reselect_Delay_Stats.”

2. Right-click the query and select “display the result in the workbook.”3. Copy the histogram numbers (row 2, columns B to N) in the workbook to the Excel object

(to row 3) embedded in this slide. The PDF/CDF plots will be automatically updated.


7-31



Section 7-31



Inter-RAT Cell Reselection – Poor Service Duration Distribution in G W Runs

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UOS Duration PDF UOS Duration CDF

Poor Service Duration Distribution in G W Runs

To view the W G Poor Service duration histogram:

1. Select the customized Actix query: Super Stream SuperStream01 Queries Crossbar Queries “Poor Service Statistics.”

2. Right-click the query and select “display the result in the workbook.”3. Copy the histogram numbers (row 2, columns B to N) in the workbook to the Excel object

(to row 3) embedded in this slide. The PDF/CDF plots will be automatically updated.


7-32



Section 7-32



Inter-RAT Cell Reselection –GSM to WCDMA Reselection Observations

• How many ping-pong events are observed?– What are the causes?

• How long are the G W cell reselection delays?– What are the causes of longer-than-average delays?– What causes the majority of delays?

• Are there any missing neighbors (in both WCDMA and GSM)?

• How often (and how long) does the UE remain in a poor service area?– What are the causes of the poor service?

• Are there any delayed or early G W cell reselections?– What are the causes?

Notes


7-33



Section 7-33



Analysis – Inter-RAT Handover


– WCDMA to GSM handover

Inter-RAT Handover

Inter-RAT handover analysis evaluates how well the network can maintain CS call service continuity when the UE crosses the WCDMA/GSM boundary. The analysis should include:

Inter-RAT handover mechanismInter-RAT handover parameters

– A performance analysis is not useful if the corresponding parameters are predetermined. The parameters recorded here will be the basis of changes derived from the analysis.

Performance metrics definitionsWCDMA to GSM handover analysis, which includes:

– Inter-RAT handover performance maps (events)– Performance statistics (events, handovers, call drops)– CM performance (duration, UE Ec/No, RSCP, BLER, Tx Power)– Call drop analysis– Observations


7-34




Section 7-34



• *CM patterns for– gsm-CarrierRSSIMeasurement

– gsm-initialBSICIdentification

– gsmBSICReconfirmation

• *CM type is SF/2

• **BSIC verification required for GSM cells

Inter-RAT Handover –WCDMA to GSM Handover Mechanism

WCDMA to GSM Handover Mechanism

The CM patterns and CM types can vary depending on the implementation of the infrastructure vendors. This information should be available prior to the data analysis.


7-35




Section 7-35



Inter-RAT Handover –System Parameters

System Paramter List Table

Event 2d:usedFreqThresholdusedFreqWhysteresistimeToTrigger

Event 2f:usedFreqThresholdusedFreqWhysteresistimeToTrigger

Event 3a:thresholdOwnSystemWthresholdOtherSystemhysteresistimeToTrigger

InterRATMeasQuantitymeasQuantityUTRANfilterCoefficientUTRANmeasQuantityGSMfilterCoefficientGSMbsic-VerificationRequired

Event 1e:thresholdUsedFrequencyhysteresistimeToTrigger

Event 1f:thresholdUsedFrequencyhysteresistimeToTrigger

UE Inter-RAT Long AMR Test Logs (*.dlf)

Actix

Measurement Control MessageIntraFrequencyMeasurement

Measurement Control MessageInterFrequencyMeasurement

Measurement Control MessageInterRATMeasurement

System Parameters

System parameters are extracted from the UE log files collected during the drive test. The log files can be imported into Actix. In Actix, the parameters are extracted from the information elements (IE) in the Over-the-Air (OTA) messages exchanged between the network and the UE, and can be viewed in the “Protocol Stack Browser.” Parameters extracted from OTA messages are compared with the system targets.

The parameter values in the slide also can be obtained in the Actix attributes listed below and on the next page. The attributes can be found by selecting 3G UMTS Uu_RRC DL-DCCH MeasurementControl.

For event 1E:

thresholdUsedFrequency: Uu_RRC_Event1e_usedFreqThresholdhysteresise: Uu_RRC_Event1e_hysteresistimeToTrigger: Uu_RRC_Event1e_timeToTrigger

For event 1F:

thresholdUsedFrequency: Uu_RRC_Event1f_usedFreqThresholdhysteresise: Uu_RRC_Event1f_hysteresistimeToTrigger: Uu_RRC_Event1f_timeToTrigger

Note: Events 1e/1f are normally not used together with events 2d/2f. Hence, parameters will not appear together in the same log.


7-36



Section 7-36



Inter-RAT Handover –System Parameters (continued)



Actix










Event 2d:thresholdUsedFrequency: Uu_RRC_Event2d_usedFreqThresholdhysteresise: Uu_RRC_Event2d_hysteresistimeToTrigger: Uu_RRC_Event2d_timeToTriggerusedFreqW: Uu_RRC_Event2d_usedFreqW

Event 2f:thresholdUsedFrequency: Uu_RRC_Event2f_usedFreqThresholdhysteresise: Uu_RRC_Event2f_hysteresistimeToTrigger: Uu_RRC_Event2f_timeToTriggerusedFreqW: Uu_RRC_Event2f_usedFreqW

Event 3a:thresholdOwnSystem: Uu_RRC_Event3a_thresholdOwnSystemthresholdOtherSystem: Uu_RRC_Event3a_thresholdOtherSystemhysteresise: Uu_RRC_Event3a_hysteresistimeToTrigger: Uu_RRC_Event3a_timeToTriggerW: Uu_RRC_Event3a_W

InterRATMeasQuantity:bsic-VerificationRequired: Uu_RRC_ratSpecificInfo_gsm_bsic_VerificationRequiredmeasQuantityGSM: Uu_RRC_ratSpecificInfo_gsm_measurementQuantityfilterCoefficientGSM: Uu_RRC_ratSpecificInfo_gsm_filterCoefficientmeasQuantityUTRAN: Uu_RRC_InterRATReportingQuantity_utran_EstimatedQualityfilterCoefficientUTRAN: Uu_RRC_InterRATReportingQuantity_utran_filterCoefficient


7-37



Section 7-37



Inter-RAT Handover – Parameter Settings

Operator Settings

–12 dB–99 dBm

Used Frequency Threshold

Event 2d 0W

2 dBHysteresis

320 msTime to Trigger

–11 dB–96 dBm


Event 2f 0W

2 dBHysteresis


EventTypical

QUALCOMM Recommendations

Parameter Name

Parameter Settings

Because inter-RAT handover behavior is fairly well known, typical recommended parameter settings can be used as a reference (or baseline) for actual network parameter settings. Using this established baseline, one can devote more attention to the performance analysis of parameters that differ significantly from the recommended settings.


To view the system parameters in Actix:

1. View Protocol Stack UMTS Radio Interface and Protocol Signaling.2. Look for the following attributes in the Measurement Control Message immediately

following call setup that sets up the inter-frequency measurements:usedFreqThresholdusedFreqWHysteresistimeToTrigger


7-38



Section 7-38



Inter-RAT Handover –Parameter Settings (continued)

RequiredBSIC Validation Required

0 msTime to Trigger

Operator Settings

–9 dB–95 dBm


Event 3a0W

0 dBHysteresis

–100 dBmThreshold Other System

Ec/No & RSCPInter-RAT UTRAN Measurement Quantity

3 (458 ms)Inter-RAT UTRAN Filter Coefficient

0GSM Filter Coefficient

Event Typical QUALCOMM RecommendationsParameter Name

Parameter Settings (continued)

Because inter-RAT handover behavior is fairly well known, typical recommended parameter settings can be used as a reference (or baseline) for actual network parameter settings. Using this established baseline, you can devote more attention to the performance analysis of parameters that differ significantly from the recommended settings.


To view the system parameters in Actix:1. View Protocol Stack UMTS Radio Interface and Protocol Signaling.2. Look for the following attributes in the Measurement Control Message immediately

following call setup that sets up the Inter-RAT measurements:usedFreqThresholdusedFreqWHysteresistimeToTrigger

3. Also look for the following attributes in the message:bsic-VerificationRequired, measQuantityGSM, filterCoefficientGSMmeasQuantityUTRAN, filterCoefficientUTRAN


7-39



Section 7-39



Inter-RAT Handover –Definitions and Abbreviations

IRHO: Inter-RAT HandoverSuccessful IRHO

• Control and user plane of the call is successfully moved from WCDMA to GSM

Compressed Mode Duration• Time from CM activation to HandoverfromUTRAN command

Handover Execution Delay• Time from Handover From UTRAN Command to Handover

Complete message

UE Transmit Power / BLER / Ec/No / RSCP during CM• Statistics are taken during Compressed Mode Duration

Notes


7-40



Section 7-40



Inter-RAT Handover –Analysis Flow Chart

Analysis Flow Chart

UE log files collected while making long AMR calls along the drive route are loaded into a post processing and analysis tool such as Actix. Actix produces geographical maps of key performance metrics including:

Compressed Mode (CM) trigger event mapInter-RAT handover (or cell change) event mapCM duration distributionTx power, Ec/No, RSCP, Ec/No and BLER distribution during CM


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Section 7-41



Inter-RAT Handover –Event 2d Locations

Event 2d Locations

To display Event 2d locations in Actix:

1. The query package should already have been imported into Actix using the following steps:

• Go to Tools Analysis Manager Import Choose query file and click OK.2. Select Superstream.3. Go to Queries Binned Queries.4. Right-click on the custom query “Event 2d” and choose “Display on Map.”


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Section 7-42



Inter-RAT Handover –Event 2f Locations

Event 2f Locations

To display Event 2f locations in Actix:

1. Select Superstream.2. Go to Queries Binned Queries.3. Right-click on the custom query “Event 2f” and choose “Display on Map.”


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Section 7-43



Inter-RAT Handover –Event 3a Locations

Event 3a Locations

To display Event 3a locations in Actix:

1. Select Superstream.2. Go to Queries Binned Queries.3. Right-click on the custom query “Event 3a” and choose “Display on Map.”


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Section 7-44



Inter-RAT Handover –Inter-RAT HO Locations

Inter-RAT HO Locations

To display Inter-RAT HO locations in Actix:

1. Select Superstream.2. Go to Queries Binned Queries.3. Right-click on the custom query “HOfromUTRAN” and choose “Display on Map.”


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Section 7-45



Inter-RAT Handover –Performance Statistics

0Number of Call Drops in GSM Coverage

6Total Number of Calls

3Number of Successful IRHOs

1

3

Value

Number of Call Drops in UMTS Coverage

Number of Rounds

Performance Statistics

This information is available from the output of a custom query: “InterRAT HO Statistics(e3a).”

To get this information in Actix:

1. Select Superstream.2. Go to Queries Crosstab Queries.3. Right-click on the custom query “InterRAT HO Statistics(e3a)” and choose “Display on

Workbook.”


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Section 7-46



Inter-RAT Handover –Performance Statistics (continued)

Successful CMStd DevAverage

UE Transmit Power during CM [dBm]

Total Number of CM per Round

Ec/No During CM [dB]

RSCP During CM [dBm]

HO delay [msec]

Downlink BLER During CM [%]

CM Duration [seconds]

Performance Statistics (continued)

The Number of CMs can be obtained from the custom query “InterRAT HO Statistics(e3a).”

All other information is available from the custom query “InterRAT HO Analysis(e3a).” Use the AVERAGE function of Excel to calculate the average of the output of the custom query.

Note: The custom query “InterRAT HO Analysis(e3a)” assumes the maximum time between CM start and HO to be 30 seconds. If this is not true for a specific case, the output of this query will have blanks corresponding to that case. To correct this, open the query definition and change the “Milliseconds before event” to the time difference as observed in the log using the Protocol Stack viewer.

To run the query in Actix:

1. Select Superstream.2. Go to Queries Crosstab Queries.3. Right-click on the custom query “InterRAT HO Analysis(e3a)” or “InterRAT HO

Statistics(e3a)” and choose “Display on Workbook.”

To edit the query:

Right-click on the custom query and choose “Edit Analysis definition.”


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Section 7-47



Inter-RAT Handover –Handover Events Statistics

Value

Number of Event 2f

Average Time between Event 3a and HOfromUTRAN Command [sec]*

Number of HOfromUTRAN Failures

Number of Event 3a

Number of HOfromUTRANCommands

All Rounds

Number of Event 2d

* Average, from the first e3a MRM

Handover Events Statistics

This information is available from the maps and the output of custom queries “InterRAT HO Analysis(e3a)” and “InterRAT HO Statistics(e3a).”


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Section 7-48



Inter-RAT Handover –CM Duration Distribution

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CM Duration Distribution

Only successful CMs are included in this analysis, and it is based on all runs.

To produce the histogram:

1. In Actix:• Select Superstream.

2. Choose the custom query “InterRAT CMduration Histogram(e3a).”• Right-click and choose “Display on Workbook.”• If a histogram is desired for all runs, then do a SUM operation on all rows.• Copy the workbook contents to the spreadsheet object embedded in this slide.• The PDF and CDF plot will be updated automatically.


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Section 7-49



Inter-RAT Handover –Best Server Ec/No Distribution (in CM)

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<= -18 -15 -12 -9 -6 >-6

EcNo(dB)

PDF/

CD

F

BestServerEcNo_CM PDF BestServerEcNo_CM CDF

Best Server Ec/No Distribution



1. In Actix:• Select Superstream.• Choose the custom query “InterRAT BestServerEcNodurinCM Histogram(e3a).”• Right-click and choose “Display on Workbook.”• If a histogram is desired for all runs, then do a SUM operation on all rows.

2. Copy the workbook contents to the spreadsheet object embedded in this slide.• The PDF and CDF plot will be updated automatically.


7-50



Section 7-50



Inter-RAT Handover –Best Server RSCP Distribution (in CM)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

<= -115 -105 -95 -85 -75 >-75

RSCP(dBm)

PDF/

CD

F

BestServerRSCP_CM PDF BestServerRSCP_CM CDF

Best Server RSCP Distribution



1. In Actix:• Select Superstream.• Choose the custom query “InterRAT BestServerRSCPduringCM Histogram(e3a).”• Right-click and choose “Display on Workbook.”• If a histogram is desired for all runs, then do a SUM operation on all rows.



7-51



Section 7-51



Inter-RAT Handover –UE Tx Power Distribution (in CM)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

<= -20 -10 0 10 20 >-20

UE Tx Pow er(dBm)

PDF/

CD

F

TxPower_CM PDF TxPower_CM CDF

UE Tx Power Distribution



1. In Actix:• Select Superstream.• Choose the custom query “InterRAT TxPowerduringCM Histogram(e3a).”• Right-click and choose “Display on Workbook.”• If a histogram is desired for all runs, then do a SUM operation on all rows.



7-52



Section 7-52



Inter-RAT Handover –Downlink BLER Distribution (in CM)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

<= 1 2 4 8 16 >16

BLER(%)

PDF/

CD

F

BLER_CM PDF BLER_CM CDF

Downlink BLER Distribution



1. In Actix:• Select Superstream.• Choose the custom query “InterRAT BLERduringCM Histogram(e3a).”• Right-click and choose “Display on Workbook.”• If a histogram is desired for all runs, then do a SUM operation on all rows.



7-53



Section 7-53



Inter-RAT Handover –Call Drop Summary

Total Number of Call Drops: 1• Call drops in W: 1• Call drops in G: 0

Reasons• Radio link failure: 1• Unexpected network release: 0

Call Drop Summary

Typical root causes for radio link failures are:

Downlink failure, as noticed with increasingly high DL BLER.Uplink failure, as noticed with maxed out UE TxPower.Late CM trigger for IRAT HO resulting in dragging on weak WCDMA link.Neighbor List issues – strong potential candidates not being added to Active Set because they are not neighbors.


7-54



Section 7-54



Inter-RAT Handover –Call Drop Locations in WCDMA

Call Drop Locations in WCDMA

To display the call drop locations in Actix:

1. Select Superstream.2. Go to UMTS Event Data Call.3. Right-click on the custom query “Uu_CallDropped” and choose “Display on Workbook.”


7-55



Section 7-55



Inter-RAT Handover – Observations

Call continuity• Handover performance• Dropped Calls

Compressed Mode operation• Triggers• Duration

Issues• Neighbor List issues• RF issues

Notes


7-56



Section 7-56



Analysis – Inter-RAT CCO

• Analysis of the results of inter-RAT transition for PS data

– WCDMA to GSM/GPRS cell change

Analysis – Inter-RAT CCO

Inter-RAT cell change (for PS data call) analysis evaluates how well the network can maintain PS call service continuity when the UE crosses the WCDMA/GSM/GPRS boundary. The analysis should include:

• WCDMA to GPRS Cell Change Order mechanism• Inter-RAT CCO parameters

– A performance analysis is not useful if the corresponding parameters are predetermined. The parameters recorded here will be the basis of changes derived from the analysis.

• Performance metrics definitions• WCDMA to GPRS CCO performance

– Inter-RAT CCO performance maps– Performance statistics– CM performance (duration, UE Ec/No, RSCP, BLER, Tx Power)– Call drop analysis– Observations


7-57



Section 7-57



WCDMA GPRS Cell Change Order Mechanism

• CM patterns for– gsm-CarrierRSSIMeasurement– gsm-initialBSICIdentification– gsmBSICReconfirmation

• CM type is HLS

• BSIC verification required for GSM cells

Notes


7-58




Section 7-58



Inter-RAT CCO –System Parameters



Actix










Inter-RAT CCO System Parameters

System parameters are extracted from the UE log files collected during the drive test. The log files can be imported into Actix. In Actix, the parameters are extracted from the information elements (IE) in the Over-the-Air (OTA) messages exchanged between the network and the UE, and can be viewed via the “Protocol Stack Browser.” Parameters extracted from OTA messages are compared with the system targets.

The parameter values in the slide also can be obtained from the Actix attributes listed below and on the next page. To find the attributes, select 3G UMTS Uu_RRC DL-DCCH MeasurementControl.

Event 1e:

thresholdUsedFrequency: Uu_RRC_Event1e_usedFreqThresholdhysteresise: Uu_RRC_Event1e_hysteresistimeToTrigger: Uu_RRC_Event1e_timeToTriggerEvent 1f:

thresholdUsedFrequency: Uu_RRC_Event1f_usedFreqThresholdhysteresise: Uu_RRC_Event1f_hysteresistimeToTrigger: Uu_RRC_Event1f_timeToTrigger

Note: Events 1e/1f are normally not used together with events 2d/2f. Hence, parameters will not appear together in the same log.


7-59



Section 7-59



Inter-RAT CCO –System Parameters (continued)







Actix






Event 2d:thresholdUsedFrequency: Uu_RRC_Event2d_usedFreqThresholdhysteresise: Uu_RRC_Event2d_hysteresistimeToTrigger: Uu_RRC_Event2d_timeToTriggerusedFreqW: Uu_RRC_Event2d_usedFreqW

Event 2f:thresholdUsedFrequency: Uu_RRC_Event2f_usedFreqThresholdhysteresise: Uu_RRC_Event2f_hysteresistimeToTrigger: Uu_RRC_Event2f_timeToTriggerusedFreqW: Uu_RRC_Event2f_usedFreqW

Event 3a:thresholdOwnSystem: Uu_RRC_Event3a_thresholdOwnSystemthresholdOtherSystem: Uu_RRC_Event3a_thresholdOtherSystemhysteresise: Uu_RRC_Event3a_hysteresistimeToTrigger: Uu_RRC_Event3a_timeToTriggerW: Uu_RRC_Event3a_W

InterRATMeasQuantity:bsic-VerificationRequired: Uu_RRC_ratSpecificInfo_gsm_bsic_VerificationRequiredmeasQuantityGSM: Uu_RRC_ratSpecificInfo_gsm_measurementQuantityfilterCoefficientGSM: Uu_RRC_ratSpecificInfo_gsm_filterCoefficientmeasQuantityUTRAN: Uu_RRC_InterRATReportingQuantity_utran_EstimatedQualityfilterCoefficientUTRAN: Uu_RRC_InterRATReportingQuantity_utran_filterCoefficient


7-60



Section 7-60



Inter-RAT CCO –Parameter Settings

Operator Settings

–12 dB–99 dBm


Event 2d0W

2 dBHysteresis


–11 dB–96 dBm


Event 2f0W

2 dBHysteresis



Parameter Settings





7-61



Section 7-61



Inter-RAT CCO –Parameter Settings (continued)

RequiredBSIC Validation Required

0 msTime to Trigger

Operator Settings

–9 dB–95 dBmUsed Frequency Threshold

Event 3a0W

0 dBHysteresis

–100 dBmThreshold Other System

Ec/No & RSCPInter-RAT UTRAN Measurement Quantity

3 (458 ms)Inter-RAT UTRAN Filter Coefficient

0GSM Filter Coefficient


Parameter Settings (continued)





7-62



Section 7-62



Inter-RAT CCO –Definitions and Abbreviations

CCO: Cell Change OrderSuccessful CCO

• Control and user plane of the call is successfully moved from WCDMA to GPRS.

Compressed Mode Duration• Time from CM activation to Cell Change Order command

Handover Execution Delay• Time from Cell Change Order command to Routing Area Update

Complete message

UE Transmit Power / BLER / Ec/No / RSCP during CM• Statistics are taken during Compressed Mode Duration.

Notes


7-63



Section 7-63



Inter-RAT CCO –Analysis Flow Chart

Analysis Flow Chart

UE log files collected while making PS data calls along the drive route are loaded into a post processing and analysis tool such as Actix. Actix produces geographical maps of key performance metrics including:

Compressed Mode (CM) trigger event mapInter-RAT handover (or cell change) event mapCM duration distributionTX power, Ec/No, RSCP, Ec/No and BLER distribution during CM


7-64



Section 7-64



Inter-RAT CCO –Event 2d Locations

Event 2d Locations

To display Event 2d locations in Actix:

1. Select Superstream.2. Go to Queries Binned Queries.3. Right-click on the custom query “Event 2d” and choose “Display on Map.”


7-65



Section 7-65



Inter-RAT CCO –Event 2f Locations

Event 2f Locations

To display Event 2f locations in Actix:

1. Select Superstream.2. Go to Queries Binned Queries.3. Right-click on the custom query “Event 2f” and choose “Display on Map.”


7-66



Section 7-66



Inter-RAT CCO –Event 3a Locations

Event 3a Locations

To display Event 3a locations in Actix:

1. Select Superstream.2. Go to Queries Binned Queries.3. Right-click on the custom query “Event 3a” and choose “Display on Map.”


7-67



Section 7-67



Inter-RAT CCO – CCO Locations

Inter-RAT COO Locations

To display Inter-RAT COO locations in Actix:

1. Select Superstream.2. Go to Queries Binned Queries.3. Right-click on the custom query “CCOfromUTRAN” and choose “Display on Map.”


7-68



Section 7-68



Inter-RAT CCO –Performance Statistics

Number of Call Drops in UMTS Coverage

Total Number of Calls

Number of Successful CCOs

Value

Number of Rounds

Performance Statistics

This information is available from the output of the custom query “InterRAT CCO Statistics(e3a).”


7-69



Section 7-69



Successful CM

Std DevAverage

UE Transmit Power during CM [dBm]

Total Number of CM per Round

Ec/No During CM [dB]

RSCP During CM [dBm]

CCO delay [msec]

Downlink BLER During CM [%]

CM Duration [seconds]

Inter-RAT CCO –Performance Statistics (continued)

Performance Statistics (continued)All runs are included in this analysis.

The Number of CMs can be obtained from the custom query “InterRAT CCO Statistics(e3a).”All other information is available from the custom query “InterRAT CCO Analysis(e3a).” Use the AVERAGE function of Excel to calculate the average of the output of the custom query.

Note: The custom query “InterRAT CCO Analysis(e3a)” assumes the maximum time between CM start and HO to be 30 seconds. If this is not true for a case, the output of this query will have blanks corresponding to that case. To correct this, open the query definition and change the “Milliseconds before event” to the time difference observed in the log using Protocol Stackviewer.To run the query in Actix:

1. Select Superstream.2. Go to Queries Crosstab Queries.3. Right-click on the custom query “InterRAT CCO Analysis(e3a)” or “InterRAT CCO

Statistics(e3a)” and choose “Display on Workbook.”To edit the query:

Right-click on the custom query and choose “Edit Analysis definition.”


7-70



Section 7-70



Inter-RAT CCO – Events Statistics

Value

Number of Event 2f

Time between Event 3a and CCO*

Number of CCO Failures

Number of Event 3a

Number of CCO Commands

All Rounds

Number of Event 2d

* Average, from the first e3a MRM

Events Statistics

This information is available from the maps and the output of custom queries “InterRAT CCO Analysis(e3a)” and “InterRAT CCO Statistics(e3a).”


7-71



Section 7-71



CM Duration Distribution

0

0.1

0.2

0.3

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0.7

0.8

0.9

1

<=2 4 6 8 10 12 14 16 18 20 >20

Time (second)

PDF/

CD

F

CM duration PDF CM duration CDF

CM Distribution



1. In Actix:

Select Superstream.Choose the custom query “InterRAT CCO CMduration Histogram(e3a).”Right-click and choose “Display on Workbook.”If a histogram is desired for all runs, then do a SUM operation on all rows.

2. Copy the workbook contents to the spreadsheet object embedded in this slide.



7-72



Section 7-72



TCP Throughput

TCP Throughput

To view the TCP throughput in Actix:

1. Select Superstream.2. Go to Internet TCP Downlink.3. Right-click on the attribute “TCP_ThroughputDL” and choose “Display on Map.”

To create a Superstream of Ethereal and UE logs:1. Open UE log; display any attribute (e.g., ActiveSetEcNo) on the table; note the

approximate time range (e.g., 1:25:33 to 1:29:45).2. Open Ethereal log; display any attribute (e.g., TCP ThroughputDL); note the approximate

time range (e.g., 7:25:12 to 7:29:59).3. Determine the approximate offset between the two logs, in seconds. (In this example,

time offset = 21600 seconds, corresponding to 6 hours).4. Go to Tools Superstream.

Check these two logs.Click on Ethereal log. At the bottom of the window, under details, choose “Time offset”and enter “-21600.”

5. Click OK. Now the Superstream should have synchronized the Ethereal data with GPS information from the UE log.


7-73



Section 7-73



Call Drop Summary

Total Number of Call Drops: 1• Call drops in W: 1• Call drops in G: 0

Reasons• Radio link failure: 1• Unexpected network release: 0

Call Drop Summary

Typical root causes for radio link failures are:

Downlink failure, as noticed with increasingly high DL BLER.Uplink failure, as noticed with maxed out UE TxPower.Late CM trigger for IRAT HO resulting in dragging on weak WCDMA link.Neighbor List issues – strong potential candidates not being added to Active Set because they are not neighbors.


7-74



Section 7-74





To view the call drop locations in Actix:

1. Select Superstream.2. Go to UMTS Event Data Call.3. Right-click on the event “Uu_CallDropped” and choose “Display on Workbook.”


7-75



Section 7-75



Observations

Call continuity• Handover performance• Dropped calls



Notes


7-76



Section 7-76



Cell Reselection• Ping-pong events• Large W G cell reselection delays

RF Issues• Neighbor List• Pilot overshooting or Pilot pollution

Continuity• Unsuitable service areas and durations

Recommendations• Parameter changes• RF optimizations

Cell Reselection Performance Conclusions

Notes


7-77



Section 7-77



Inter-RAT Handover Conclusions





Notes


7-78



Section 7-78



Inter-RAT CCO Conclusions





Notes


7-79



Section 7-79



Inter-System Continuity: Hands on Module –What Did We Learn?

How do we design test cases, select a test metric route, and collect drive test data for inter-system continuity evaluation?

How do we analyze the drive test data using Actix?

What are typical performance evaluation metrics for inter-system reselection and inter-system changes, and how do we derive them from the drive test?

How can we troubleshoot failure events?

What is the failure recovery mechanism?

Notes


7-80



Comments/Notes



8-1

Section 8: Appendices80-W0242-4 Rev D


Section 8-1


WCDMA (UMTS) Inter-System NetOpt Workshop Section 8: Appendices

8SECTION

Appendices

Notes



8-2



Section 8-2


WCDMA (UMTS) Inter-System NetOpt Workshop Section Introduction

This section contains the following Appendices:

A. IRAT Metric Route Selection

B. IRAT Log Mask

C. Test Setup and test cases

D. Conducting Drive Test

Notes



8-3



Section 8-3


WCDMA (UMTS) Inter-System NetOpt Workshop Appendix A –

IRAT Metric Route Selection

• IRAT Metric Route Selection

Notes



8-4



Section 8-4


WCDMA (UMTS) Inter-System NetOpt Workshop (A) Metric Route Selection

Main Route Selection Criteria:

• Start from an area with strong WCDMA coverage and end at an area with no WCDMA, but strong GSM coverage.

• Length of route (~10 minutes).

• Consider starting and ending points that provide parking.

Metric Route Selection

Coverage along the route should be continuous, providing sufficient WCDMA or GSM coverage on each section of the route. The example above illustrates the ideal of only one WCDMA GSM transition boundary on the route.

The duration of route depends on test scenario and network layout. Testing the inter-RAT change behavior over a distinct border, as shown in the picture, could need only a short duration (~10 minutes). Testing a weak WCDMA coverage area with a poorly-defined W G transition border would have a longer duration (and route length) in order to cover all the necessary WG transition areas.

If inter-RAT performance tests are also used to evaluate WCDMA coverage and identify the WCDMA coverage holes, or evaluate indoor-to-outdoor service continuities, the test metric route selection should take those objectives into account. Other route selection considerations include:

Coverage of main roads and small streets.Route crosses areas where issues have been reported/observed.Test ends at the starting point (for circular routes).Parking availability at the start and end location.Ability to easily run the route in clockwise and counter-clockwise directions, if possible.Route includes areas where test vehicle can be driven at different speeds.



8-5



Section 8-5


WCDMA (UMTS) Inter-System NetOpt Workshop (A) Metric Route Example

WCDMA End

GSM/GPRS End

Approximate WCDMA/GSM Boundary

Notes



8-6



Section 8-6


WCDMA (UMTS) Inter-System NetOpt Workshop Appendix B – IRAT Log Mask

• IRAT Log Mask

Notes



8-7



Section 8-7


WCDMA (UMTS) Inter-System NetOpt Workshop (B) Define Log Mask

Guidelines:– Capture enough data to meet the test objectives– Avoid capturing “irrelevant” information

Two basic types of log masks:– Inter-RAT handover log mask: for studying handover or cell

change performance– Inter-RAT cell reselection log mask: for studying inter-system cell

reselection performance

Define Log Mask

Irrelevant information is a vague term. Strictly speaking, any information captured during the test is useful. However, the degree of usefulness varies according to the data collected and the test objectives. For example, RLC throughput is very useful to determine data throughput, but is seldom used for computing AMR call handover statistics. In practice, unanticipated events could occur during the test and one cannot always guarantee that the desired information will be collected to identify the root cause of the event. A good log mask template built on experience is always a good starting point.



8-8



Section 8-8



GSM

/ G

PRS

Layer 1(B) Log Mask Example – Cell Reselection

The log mask for evaluating inter-RAT cell reselectionshould include:

– Layer 1 RF information to verify cell reselection triggers

– Layer 3 RRC signaling to verify cell reselection, LAU and RAU behavior

– GSM/GPRS signaling to verify cell reselection, LAU and RAU behavior

– Positioning information to determine the locations of cell reselection and other events

W-CDMA step 1 searchW-CDMA step 2 searchW-CDMA step 3 searchW-CDMA list-searchW-CDMA finger info for TA - finger/pilot channel parametersW-CDMA AGCW-CDMA DRX modeW-CDMA active setW-CDMA neighbor setCell Reselection Log PacketW-CDMA SIBW-CDMA RACH ParametersW-CDMA PRACH Channel Parameters

W-CDMA RRC signaling messagesNAS signaling messages

All GSM L1 except burst metrics and monitor burstsAll GSM L3GPRS/GRR

GPS (GPS Location, 3D GPS Location)

F3 (Debug) Messages (High, Error, Fatal --Note: Log the Medium messages when needed to debug any issues on the GPRS side.)

All UE Internal Events

Layer 3

Inter-RAT cell reselection test log mask example*

Log Mask Example (continued)This example corresponds to the QUALCOMM CAIT (CDMA Air Interface data collection Tool). Similar information can be obtained with other data collection tools, although the labels and arrangement could be different.



8-9



Section 8-9


WCDMA (UMTS) Inter-System NetOpt Workshop (B) Log Mask Example – Handover

The log mask for evaluating inter-RAT handover should include:

– Layer 1 channel and RF information to verify handover triggers and link qualities

– Layer 2 RLC information for proper low-level debugging

– Layer 3 RRC signaling to verify handover behavior

– GSM/GPRS signaling to verify handover behavior

– Positioning information to determine the location of handover and other events

W-CDMA finger info for TA - finger/pilot channel parameterW-CDMA AGCW-CDMA RACH parametersW-CDMA transport channels downlinkW-CDMA transport channels uplinkW-CDMA common physical channels downlinkW-CDMA dedicated physical channels downlinkW-CDMA physical channels uplinkW-CDMA PRACHW-CDMA active setW-CDMA neighbor setW-CDMA L1 Power Control with Compressed ModeW-CDMA BLER

W-CDMA RLC UL AM StatisticsW-CDMA RLC DL AM StatisticsW-CDMA RLC UL AM PDUW-CDMA RLC UL AM NAK PDUW-CDMA RLC DL AM PDUW-CDMA RLC DL AM NAK PDU

W-CDMA RRC statesW-CDMA RRC signaling messagesNAS Signaling Messages

W-CDMA Compressed Mode GSM MeasurementsAll GSM L1 except burst metrics and monitor burstsAll GSM L3GPRS/GRR

GPS (GPS Location, 3D GPS Location)

F3 (Debug) Messages (High, Error, Fatal --Note: Log the Medium messages when needed to debug any issues on the GPRS side.)

All UE internal Events`

Laye

r 1La

yer 3

Laye

r 2G

SM /

G

PRS

Inter-system handover test log mask example*

Log Mask Example

This example corresponds to the QUALCOMM CAIT (CDMA Air Interface data collection Tool). Similar information can be obtained with other data collection tools, although the labels and arrangement could be different.



8-10



Section 8-10


WCDMA (UMTS) Inter-System NetOpt Workshop Appendix C –

Test Setup and Test Cases

• Test Setup and Test Cases

Notes



8-11



Section 8-11


WCDMA (UMTS) Inter-System NetOpt Workshop (C) Test Setup

GPS Receiver(collocate with the UE)

Notes



8-12

Section 8: Appendices

80-W0242-4 Rev D


Section 8-12


WCDMA (UMTS) Inter-System NetOpt Workshop (C) WCDMA to GSM

Cell Reselection Test Case

Test Case 1 (CS Idle, PS Attached):

1. Start testing at the WCDMA end of the route.

2. Register the UE in both CS and PS domains.

3. Start the CAIT and the scanner logging.

4. Move toward the GSM/GPRS area.

5. Stop logging at the GSM end of the route and save the CAIT and scanner log files.

6. Repeat for additional samples.

Test objective:Evaluate the inter-RAT cell reselection from WCDMA to GSM in Idle Mode.

Notes



8-13

Section 8: Appendices

80-W0242-4 Rev D


Section 8-13


WCDMA (UMTS) Inter-System NetOpt Workshop (C) GSM to WCDMA

Cell Reselection Test Case

Test Case 2 (CS Idle, PS Attached):

1. Start testing at the GSM end of the route.

2. Register UE in both CS and PS domains.

3. Start the CAIT and the scanner logging.

4. Move toward the WCDMA area.

5. Stop logging at the WCDMA end of the route and save the CAIT and scanner log files.


Test objective: Evaluate the inter-RAT cell reselection from GSM to WCDMA in the Idle Mode.

Notes



8-14



Section 8-14


WCDMA (UMTS) Inter-System NetOpt Workshop (C) Inter-RAT Handover Test Case

Test Case 3 (CS CELL_DCH, PS Attached):

1. Start testing at the WCDMA end of the route.2. Get the UE camped on WCDMA and

registered in both CS and PS domains.3. Start the CAIT and the scanner logging.4. Originate an AMR call.5. Move to the GSM/GPRS area.6. Verify successful handover to GSM.7. At the GSM end of the route, release the

call, stop logging, and save the CAIT and scanner log files.


Test objective:Evaluate WCDMA to GSM handover performance for an AMR call.

Notes



8-15



Section 8-15


WCDMA (UMTS) Inter-System NetOpt Workshop (C) WCDMA to GSM

Transition During PS Call Test Case

Test Case 4 (CS Attached, PS CELL_DCH):

1. Start testing at the WCDMA end of the route.2. Get the UE camped on WCDMA and

registered in both CS and PS domains.3. Start Ethereal, CAIT, and scanner logging.4. Make a PS Data call. To ensure that the UE

stays in CELL_DCH, start an FTP download (file size of 15 MB or larger).

5. Move toward the GSM/GPRS area.6. Monitor the FTP data transfer continuity.7. Stop the FTP transfer and release the call at

the GSM end of the route. Then, save the Ethereal, CAIT and scanner log files.


Test objective:Evaluate the inter-RAT handover from WCDMA to GSM/GPRS, preserving PS data continuity while a PS data call is active.

Notes



8-16



Section 8-16


WCDMA (UMTS) Inter-System NetOpt Workshop (C) GSM to WCDMA

Transition During PS Call Test Case

Test Case 5 (CS Attached, PS CELL_DCH):

1. Start testing at the GSM end of the route.2. Get the UE camped on GSM and registered

in both CS and PS domains.3. Start the Ethereal, CAIT and scanner

logging.4. Make a PS Data call. To ensure that the UE

stays in DCH, start an FTP download (file size of 15 MB or larger).

5. Move toward the WCDMA area.6. Monitor the FTP data transfer continuity.7. Stop the FTP transfer and release the call at

the WCDMA end of the route. Then, save the Ethereal, CAIT and scanner log files.


Test objective: Evaluate the inter-RAT handover from GSM/GPRS to WCDMA, preserving PS data continuity while a PS data call is active.

Notes



8-17



Section 8-17


WCDMA (UMTS) Inter-System NetOpt Workshop Appendix D –

Conducting the Drive Test

• Conducting the Drive Test

Notes



8-18



Section 8-18


WCDMA (UMTS) Inter-System NetOpt Workshop (D) Conducting the Drive Test –

What to Observe

• Idle Test– RF quality (Ec/No value)

– UE state/status indication (Idle, DCH, WCDMA, GSM)

• AMR Test – everything above plus:– UE transmit power

– CM and handover events

• Data Test – everything above plus:– Data transfer progress

– RLC throughput

• In addition:– Phone link / GPS failure

What to Observe

It is important to monitor the test to make sure qualitative test logs are collected. This is the first step of test validation. At the end of the test route, the tester should determine if the collected data is useful, and if any backup data should be collected.

For example a test log containing no RAT change, which would occur if the UE remained in WCDMA for the entire test, would not be very useful for analyzing the inter-RAT cell reselection performance.



8-19



Section 8-19



Using CAIT for a Cell Reselection Test

Multipath energy of PSC397 shown on finger 1,2,3,4

Combined Ec/No of PSC 20

Indicates UE in idle Mode

RSSI power

Using CAIT for a Cell Reselection Test

Set the UE in Automatic and circuit switched (CS) + packet switched (PS) mode. To do this:

1. Press the [MENU] soft key and go to Settings Networks.2. Go to “Mode Preference”, choose “Automatic,” and press [OK].3. Go to “Acquisition Order Preference,” choose “WCDMA, GSM,” and press [OK].4. Go to “Service Domain Preference,” choose “CS+PS,” and press [OK].

Repeat this command whenever the UE is power-cycled.

Make sure that correct logging profile is loaded (shown circled in the slide), and that GPS information is available (circled in the slide).



8-20



Section 8-20



Using CAIT for a Handover/PS Test

TrCH id # 1 RABTrCH id # 32 SRB

GSM channels ARFCN measurements are shown in decreasing order; Top 8 will be used to measure BSIC

BLER reporting frequency (500msec)

RSSI power

UE Txpower

Compressed Mode Gaps start

Pilot Scanner can show Ec/No of Active Set

UE measured SIR range

Using CAIT for a Handover/PS Test

1. Set the UE in Automatic and circuit switched + packet switched mode. To do this:

Press the [MENU] soft key and go to Settings Networks Force Mode.Choose “Automatic” and Press [OK].Choose “WCDMA first GSM second” and Press [OK].Choose “Ckt & Pkt Switched” and Press [OK].

2. Change the BLER reporting interval of the UE to 500 milliseconds. To do this:

Goto the View Scripting window of CAIT.Type send_data “4B040800F401” in the Script command field and press Enter.

3. Repeat this command whenever the UE is power-cycled.



8-21



Section 8-21



Ethereal – Captured Packets Summary

FTP Client – Progress Bar

(D) Conducting the Drive Test –Other Windows in PS Inter-RAT Test

Notes



8-22



Comments/Notes
