WCDMA
`FoRUMTS
`
`Radio Access For Third Generation
`Mobile Communications
`
`Revised edition
`
`Edited by
`Harri Holma and Antti Toskala
`Both of Nokia, Finland
`
`JOHN WILEY & SONS, LTD
`Chichester• New York• Weinheim • Brisbane • Singapore • Toronto
`
`Apple Inc v. Cellular Communications Equipment LLC
`APPL-1007 / Page 1 of 41
`
`

`
`Copyright © 2001 by John Wiley & Sons, Ltd,
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`
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`National
`International (+44) 1243 779777
`
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`All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in
`any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under
`the terms of the Copyright Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright
`Licensing Agency, 90 Tottenham Court Road, London, WlP 9HE, UK, without the permission in writing of the
`Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed
`on a computer system, for exclusive use by the purchaser of the publication.
`
`Neither the author( s) nor John Wiley & sons Ltd accept any responsibility or liability for loss or damage occasioned
`to any person or property through using the material, instructions, methods or ideas contained herein, or acting or
`refraining from acting as a result of such use. The author(s) and Publisher expressly disclaim all implied warranties,
`including merchantability of fitness for any particular purpose. There will be no duty on the author(s) or Publisher
`to correct any errors or defects in the software.
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`where John Wiley & Sons is aware of a claim, the product names appear in initial capital or capital letters.
`Readers, however, should contact the appropriate companies for more complete information regarding trademarks
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`Other Wiley Editorial Offices
`
`John Wiley & Sons, Inc., 605 Third Avenue,
`New York, NY 10158-0012, USA
`
`WILEY-VCR Verlag GmbH
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`
`John Wiley & Sons Australia, 33 Park Road, Milton,
`Queensland 4064, Australia
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`John Wiley & Sons (Asia) Pte Ltd, 2 Clementi Loop #02-01,
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`
`British Library Cataloguing in Publication Data
`
`A catalogue record for this book is available from the British Library
`
`ISBN 0 471 48687 6
`
`Typeset by Laser Words, Madras, India
`Printed and bound in Great Britain by Antony Rowe Ltd, Chippenham, Wiltshire.
`This book is printed on acid-free paper responsibly manufactured from sustainable forestry,
`in which at least two trees are planted for each one used for paper production.
`
`APPL-1007 / Page 2 of 41
`
`

`
`'al system, or transmitted, in
`~ or otherwise, except under
`nee issued by the Copyright
`permission in writing of the
`being entered and executed
`
`1r loss or damage occasioned
`cintained herein, or acting or
`claim all implied warranties,
`Jn the author(s) or Publisher
`
`trademarks. In all instances
`.al capital or capital letters.
`nation regarding trademarks
`
`Contents
`
`Preface
`
`Acknowledgements
`
`Abbreviations
`
`1 Introduction
`
`Harri Halma, Antti Toskala and Ukko Lappalainen
`1.1 WCDMA in Third Generation Systems
`1.2 Air Interfaces and Spectrum Allocations for Third Generation Systems
`1.3
`Schedule for Third Generation Systems
`1.4 Differences between WCDMA and Second Generation Air Interfaces
`1.5
`Core Networks
`References
`
`2 UMTS Services and Applications
`
`Jouni Salonen and Antti Toskala
`2.1
`Introduction
`2.2 UMTS Bearer Service
`2.3 UMTS QoS Classes
`2.3.1
`Conversational Class
`2.3.2
`Streaming Class
`2.3.3
`Interactive Class
`2.3.4
`Background Class
`Service Capabilities with Different Terminal Classes
`2.4
`Concluding Remarks
`2.5
`References
`
`Jrestry,
`
`xiii
`xv
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`xvii
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`1
`
`2
`4
`5
`7
`8
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`9
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`9
`10
`11
`12
`18
`20
`21
`22
`23
`23
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`APPL-1007 / Page 3 of 41
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`
`vi
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`WCDMA for UMTS
`
`3 Introduction to WCDMA
`
`Peter Muszynski and Harri Halma
`3 .1
`Introduction
`3.2
`Summary of Main Parameters in WCDMA
`3.3
`Spreading and Despreading
`3.4 Multipath Radio Channels and Rake Reception
`3.5
`Power Control
`Softer and Soft Handovers
`3.6
`References
`
`4 Background and Standardisation of WCDMA
`
`Antti Toskala
`Introduction
`4.1
`4.2 Background in Europe
`4.2.1 Wideband CDMA
`4.2.2 Wideband TDMA
`4.2.3 Wideband TDMAICDMA
`4.2.4 OFDMA
`4.2.5 ODMA
`4.2.6
`ETSI Selection
`4.3
`Background in Japan
`4.4 Background in Korea
`4.5
`Background in the United States
`4.5.1 W-CDMAN/A
`4.5.2 UWC-136
`4.5.3
`cdma2000
`4.5.4
`TR46.l
`4.5.5 WP-CDMA
`4.6
`Creation of 3GPP
`4.7
`Creation of 3GPP2
`4.8 Harmonisation Phase
`4.9
`IMT2000 Process in ITU
`4.10 Beyond 3GPP Release-99
`References
`
`5 Radio Access Network Architecture
`
`Fabio Langoni and Atte Lansisalmi
`5.1
`System Architecture
`5.2 UTRAN Architecture
`5.2.1
`The Radio Network Controller
`5.2.2
`The Node B (Base Station)
`
`25
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`25
`25
`27
`30
`33
`36
`38
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`39
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`39
`39
`40
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`51
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`54
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`56
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`APPL-1007 / Page 4 of 41
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`

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`WCDMA for UMTS
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`Contents
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`25
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`25
`25
`27
`30
`33
`36
`38
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`39
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`39
`39
`40
`41
`41
`42
`42
`42
`43
`44
`44
`44
`44
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`45
`45
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`47
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`48
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`51
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`51
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`55
`56
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`5.4
`
`5.3 General Protocol Model for UTRAN Terrestrial Interfaces
`5.3.l General
`5.3.2 Horizantal Layers
`5.3.3
`Vertical Planes
`Iu, the UTRAN-CN Interface
`5.4.1
`Protocol Structure for Ju CS
`5.4.2
`Protocol Structure for Ju PS
`5.4.3
`RANAP Protocol
`5.4.4
`Ju User Plane Protocol
`5.5 UTRAN Internal Interfaces
`5.5.l
`RNC-RNC Interface (fur Inteiface) and the RNSAP Signalling
`5.5.2
`RNC-Node B Inteiface and the NEAP Signalling
`References
`
`6 Physical Layer
`
`6.3
`
`Antti Toskala
`6.1
`Introduction
`6.2
`Transport Channels and their Mapping to the Physical Channels
`6.2.1 Dedicated Transport Channel
`6.2.2
`Common Transport Channels
`6.2.3 Mapping of Transport Channels onto the Physical Channels
`6.2.4
`Frame Structure of Transport Channels
`Spreading and Modulation
`6.3.1
`Scrambling
`6.3.2
`Channelisation Codes
`6.3.3 Uplink Spreading and Modulation
`6.3.4 Downlink Spreading and Modulation
`6.3.5
`Transmitter Characteristics
`6.4 User Data Transmission
`6.4.1
`Uplink Dedicated Channel
`6.4.2
`Uplink Multiplexing
`6.4.3 User Data Transmission with the Random Access Channel
`6.4.4 Uplink Common Packet Channel
`6.4.5 Downlink Dedicated Channel
`6.4.6 Downlink Multiplexing
`6.4.7 Downlink Shared Channel
`6.4.8
`Forward Access Channel for User Data Transmission
`6.4.9
`Channel Coding for User Data
`6.4.10 Coding for TFCI information
`Signalling
`6.5.1
`Common Pilot Channel (CPICH)
`6.5.2
`Synchronisation Channel (SCH)
`6.5.3
`Primary Common Control Physical Channel (Primary CCPCH)
`6.5.4
`Secondary Common Control Physical Channel (Secondary CCPCH)
`
`6.5
`
`vii
`
`56
`56
`56
`56
`58
`58
`59
`60
`62
`62
`62
`65
`67
`
`69
`
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`70
`71
`71
`73
`74
`74
`74
`75
`75
`80
`83
`84
`84
`86
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`97
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`APPL-1007 / Page 5 of 41
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`

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`viii
`
`WCDMA for UMTS
`
`6.6
`
`Random Access Channel (RACH) for Signalling Transmission
`6.5.5
`Acquisition Indicator Channel (AICH)
`6.5.6
`Paging Indicator Channel (PICH)
`6.5.7
`Physical Channels for CPCH Access Procedure
`6.5.8
`Physical Layer Procedures
`Fast Closed Loop Power Control Procedure
`6.6.1
`6.6.2 Open Loop Power Control
`6.6.3
`Paging Procedure
`6.6.4
`RACH Procedure
`CPCH Operation
`6.6.5
`6.6.6 Cell Search Procedure
`6.6.7
`Transmit Diversity Procedure
`6.6.8 Handover Measurements Procedure
`6.6.9
`Compressed Mode Measurement Procedure
`6.6.10 Other Measurements
`6.6.11 Operation with Adaptive Antennas
`Terminal radio access capabilities
`6.7
`References
`
`7 Radio Interface Protocols
`
`JOO
`101
`101
`102
`103
`103
`103
`104
`105
`106
`106
`108
`108
`110
`112
`113
`113
`116
`
`117
`
`117
`117
`119
`119
`119
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`121
`122
`123
`123
`125
`126
`l27
`128
`128
`129
`129
`129
`130
`130
`131
`133
`147
`
`7.4
`
`7 .5
`
`Jukka Vialen
`7 .1
`Introduction
`7 .2
`Protocol Architecture
`7.3
`The Medium Access Control Protocol
`7.3.l MAC Layer Architecture
`7.3.2 MAC Functions
`7.3.3
`Logical Channels
`7.3.4 Mapping Between Logical Channels And Transport Channels
`7.3.5
`Example Data Flow Through The MAC Layer
`The Radio Link Control Protocol
`7.4.1
`RLC Layer Architecture
`7.4.2
`RLC Functions
`7.4.3
`Example Data Flow Through The RLC Layer
`The Packet Data Convergence Protocol
`7.5.l
`PDCP Layer Architecture
`7.5.2
`PDCP Functions
`The Broadcast/Multicast Control Protocol
`7.6.1
`BMC Layer Architecture
`7.6.2
`BMC Functions
`The Radio Resource Control Protocol
`7. 7.1
`RRC Layer Logical Architecture
`RRC Service States
`7.7.2
`7.7.3
`RRC Functions And Signalling Procedures
`References
`
`7 .6
`
`7.7
`
`APPL-1007 / Page 6 of 41
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`

`
`WCDMA for UMTS
`
`Contents
`
`zsmission
`
`-:hannels
`
`IOO
`IOI
`IOI
`I02
`103
`I03
`I03
`104
`I05
`I06
`I06
`108
`I08
`110
`112
`113
`113
`116
`
`117
`
`117
`117
`119
`119
`119
`I2I
`12I
`122
`123
`123
`125
`I26
`127
`128
`128
`129
`129
`129
`130
`130
`13I
`133
`147
`
`-
`
`8 Radio Network Planning
`
`8.3
`
`Harri Halma, Zhi-Chun Honkasalo, Seppa Hamaliiinen, Jaana Laiho, Kari Sipilii
`and Achim Wacker
`8.1
`Introduction
`8.2 Dimensioning
`Radio Link Budgets and Coverage Efficiency
`8.2.I
`Load Factors and Spectral Efficiency
`8.2.2
`Example Load Factor Calculation
`8.2.3
`Capacity Upgrade Paths
`8.2.4
`Capacity per km2
`8.2.5
`Soft Capacity
`8.2.6
`Capacity and Coverage Planning
`Iterative Capacity and Coverage Prediction
`8.3.I
`Planning Tool
`8.3.2
`Case Study
`8.3.3
`8.3.4 Network Optimisation
`8.4 GSM Co-planning
`8.5 Multi-operator Interference
`Introduction
`8.5.I
`8.5.2 Worst-Case Uplink Calculations
`8.5.3 Downlink Blocking
`8.5.4 Uplink Simulations
`Simulation Results
`8.5.5
`8.5.6 Network Planning with Adjacent Channel Interference
`References
`
`9 Radio Resource Management
`
`Janne Laakso, Harri Halma and Oscar Salonaho
`9.1
`Interference-Based Radio Resource Management
`9.2
`Power Control
`Fast Power Control
`9.2.I
`9.2.2 Outer Loop Power Control
`9.3 Handovers
`Intra-frequency Handovers
`9.3.I
`Inter-system Handovers Between WCDMA and GSM
`9.3.2
`Inter-frequency Handovers within WCDMA
`9.3.3
`Summary of Handovers
`9.3.4
`9.4 Measurement of Air Interface Load
`9.4.I Uplink Load
`9.4.I Downlink Load
`9.5 Admission Control
`Admission Control Principle
`9.5.I
`9.5.2 Wideband Power-Based Admission Control Strategy
`Throughput-Based Admission Control Strategy
`9.5.3
`
`ix
`
`149
`
`149
`149
`I50
`I54
`I59
`I62
`I63
`I65
`167
`I67
`I68
`170
`174
`175
`176
`176
`I77
`I78
`179
`I80
`I8I
`182
`
`183
`
`183
`184
`I84
`I9I
`197
`I97
`204
`206
`206
`207
`207
`2IO
`211
`211
`211
`213
`
`APPL-1007 / Page 7 of 41
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`

`
`x
`
`WCDMA for UMTS
`
`Load Control (Congestion Control)
`9.6
`References
`
`10 Packet Access
`
`Mika Raitola and Harri Halma
`10.l Packet Data Traffic
`10.2 Overview of WCDMA Packet Access
`10.3 Transport Channels for Packet Data
`I0.3.I Common Channels
`I0.3.2 Dedicated Channels
`I0.3.3 Shared Channels
`I0.3.4 Common Packet Channel
`I0.3.5 Selection of Channel Type
`10.4 Example Packet Scheduling Algorithms
`I0.4.I
`Introduction
`I0.4.2 Time Division Scheduling
`I 0.4.3 Code Division Scheduling
`I0.4.4 Transmission Power-Based Scheduling
`Interaction between Packet Scheduler and Other RRM Algorithms
`I0.5.I Packet Scheduler and Handover Control
`I0.5.2 Packet Scheduler and Load Control (Congestion Control)
`I0.5.3 Packet Scheduler and Admission Control
`10.6 Packet Data Performance
`I0.6.I Link-Level Performance
`I0.6.2 System-Level Performance
`References
`
`10.5
`
`11 Physical Layer Performance
`
`Harri Halma, Markku Juntti and Juha Ylitalo
`11.1
`Introduction
`11.2 Coverage
`I I.2.I Uplink Coverage
`11.2.2 Random Access Channel Coverage
`I I.2.3 Downlink Coverage
`I I.2.4 Coverage Improvements
`11.3 Capacity
`11.3.I Downlink Orthogonal Codes
`I I.3.2 Downlink Transmit Diversity
`I I.3.3 Capacity Improvements
`11.4 High Bit Rates
`11.4.I
`Inter-path Inteiference
`11.4.2 Multipath Diversity Gain
`11.4.3 Feasibility of High Bit Rates
`
`213
`214
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`217
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`220
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`220
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`225
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`249
`250
`250
`255
`257
`258
`259
`26I
`262
`
`APPL-1007 / Page 8 of 41
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`

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`WCDMA for UMTS
`
`Contents
`
`ithms
`
`itrol)
`
`213
`214
`
`217
`
`217
`218
`219
`219
`220
`220
`220
`221
`221
`221
`222
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`224
`225
`225
`225
`225
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`226
`228
`236
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`237
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`237
`237
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`247
`248
`249
`250
`250
`255
`257
`258
`259
`261
`262
`
`11.5 Performance Enhancements
`11.5.1 Antenna Solutions
`11.5.2 Multi-user Detection
`References
`
`12 UTRA TDD Mode
`
`Otto Lehtinen, Antti Toskala, Harri Halma and Heli Vdatdjd
`Introduction
`12.l
`12.1.1 Time Division Duplex (TDD)
`12.2 UTRA TDD Physical Layer
`12.2.1 Transport and Physical Channels
`12.2.2 Modulation and Spreading
`12.2.3 Physical Channel Structures, Slot and Frame Format
`12.2.4 UTRA TDD Physical Layer Procedures
`12.3 UTRA TDD Interference Evaluation
`12.3.1 TDD-TDD Inteiference
`12.3.2 TDD and FDD Co-existence
`12.3.3 Unlicensed TDD Operation
`12.3.4 Conclusions on UTRA TDD Interference
`12.4 Concluding Remarks on UTRA TDD
`References
`
`13 Multi-Carrier CDMA in IMT-2000
`
`Antti Toskala
`Introduction
`13.1
`13.2 Logical Channels
`13.2.1 Physical Channels
`13.3 Multi-Carrier Mode Spreading and Modulation
`13.3.1 Uplink Spreading and Modulation
`13.3.2 Downlink Spreading and Modulation
`13.4 User Data Transmission
`13.4.1 Uplink Data Transmission
`13.4.2 Downlink Data Transmission
`13.4.3 Channel Coding for User Data
`13.5 Signalling
`13.5.1 Pilot Channel
`13.5.2 Synch Channel
`13.5.3 Broadcast Channel
`13.5.4 Quick Paging Channel
`13.5.5 Common Power Control Channel
`13.5.6 Common and Dedicated Control Channels
`13.5.7 Random Access Channel (RACH) for Signalling Transmission
`
`xi
`
`263
`264
`268
`272
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`277
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`277
`279
`279
`280
`281
`285
`289
`290
`291
`294
`294
`294
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`297
`298
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`299
`299
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`
`APPL-1007 / Page 9 of 41
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`

`
`xii
`
`WCDMA for UMTS
`
`13.6 Physical Layer Procedures
`13.6.1 Power Control Procedure
`13.6.2 Cell Search Procedure
`13.6.3 Random Access Procedure
`13.6.4 Handover Measurements Procedure
`References
`
`Index
`
`306
`306
`306
`307
`308
`308
`
`309
`
`APPL-1007 / Page 10 of 41
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`

`
`WCDMA for UMTS
`
`306
`306
`306
`307
`308
`308
`
`309
`
`Preface
`
`Second generation telecommunication systems, such as GSM, enabled voice traffic to go
`wireless: the number of mobile phones exceeds the number of landline phones and the mobile
`phone penetration exceeds 70% in countries with the most advanced wireless markets. The
`data handling capabilities of second generation systems are limited, however, and third
`generation systems are needed to provide the high bit rate services that enable high quality
`images and video to be transmitted and received, and to provide access to the web with
`high data rates. These third generation mobile communication systems are referred to in this
`book as UMTS (Universal Mobile Telecommunication System). WCDMA (Wideband Code
`Division Multiple Access) is the main third generation air interface in the world and will
`be deployed in Europe and Asia, including Japan and Korea, in the same frequency band,
`around 2 GHz. The large market for WCDMA and its flexible multimedia capabilities will
`create new business opportunities for manufacturers, operators, and the providers of content
`and applications. This book gives a detailed description of the WCDMA air interface and
`its utilisation. The contents are summarised in Figure 1
`Chapter 1 introduces the third generation air interfaces, the spectrum allocation, the
`time schedule, and the main differences from second generation air interfaces. Chapter 2
`presents example UMTS applications, concept phones and the quality of service classes.
`Chapter 3 introduces the principles of the WCDMA air interface, including spreading, Rake
`receiver, power control and handovers. Chapter 4 presents the background to WCDMA,
`the global harmonisation process and the standardisation. Chapters 5-7 give a detailed
`presentation of the WCDMA standard, while Chapters 8-11 cover the utilisation of the
`standard and its performance. Chapter 5 describes the architecture of the radio access
`network, ii;iterfaces within the radio access network between base stations and radio network
`controllers (RNC), and the interface between the radio access network and the core network.
`Chapter 6 covers the physical layer (layer 1), including spreading, modulation, user data and
`signalling transmission, and the main physical layer procedures of power control, paging,
`transmission diversity and handover measurements. Chapter 7 introduces the radio inter(cid:173)
`face protocols, consisting of the data link layer (layer 2) and the network layer (layer
`3). Chapter 8 presents the guidelines for radio network dimensioning, gives an example of
`detailed capacity and coverage planning, and covers GSM co-planning. Chapter 9 covers the
`radio resource management algorithms that guarantee the efficient utilisation of the air inter(cid:173)
`face resources and the quality of service. These algorithms are power control, handovers,
`admission and load control. Chapter 10 depicts packet access and verifies the approach
`presented in dynamic system simulations. Chapter 11 analyses the coverage and capacity of
`
`APPL-1007 / Page 11 of 41
`
`

`
`xiv
`
`WCDMA for UMTS
`
`Introduction (Chapter 1)
`
`Radio access network J~f
`
`architecture (Chapter 5)
`
`Radio resource management
`(Chapter 9)
`
`Packet access (Chapter 10)
`
`Background and
`standardisation
`(Chapter 4)
`
`Radio interface protocols
`~ (Chapter 7) ~
`/ -~~~:.::::> ·..
`---~ -
`
`.
`
`.. -<~.-~-~=
`1. ~~~~;~ti·
`~'.··· ::d;o1~~;!,~}"";og
`
`Physical layer performance
`(Chap~11)
`
`••
`
`Introduction to WCDMA ~
`(Chapter 3)
`
`· ·
`
`Multicarrier CDMA
`(Chapter 13)
`
`TDD mode
`(Chapter 12)
`
`UMTS Services and
`applications (Chapter 2)
`
`Figure 1. Contents of this book
`
`the WCDMA air interface with bit rates up to 2 Mbps. Chapter 12 introduces the time divi(cid:173)
`sion duplex (TDD) mode of the WCDMA air interface and its differences from the frequency
`division duplex (FDD) mode. In addition to WCDMA, third generation services can also be
`provided with EDGE or with multicarrier CDMA. EDGE is the evolution of GSM for high
`data rates within the GSM carrier spacing. Multicarrier CDMA is the evolution of IS-95 for
`high data rates using three IS-95 carriers, and is introduced in Chapter 13.
`This reprint of the book includes the key modifications of 3GPP specification done since
`the official completion of Release'99 until December 2000.
`This book is aimed at operators, network and terminal manufacturers, service providers,
`university students and frequency regulators. A deep understanding of the WCDMA air
`interface, its capabilities and its optimal usage is the key to success in the UMTS business.
`This book represents the views and opinions of the authors, and does not necessarily
`represent the views of their employers.
`
`APPL-1007 / Page 12 of 41
`
`

`
`WCDMA for UMTS
`
`Proc. IEEE Int. Conj on
`Helsinki, Finland, 1-4
`
`RAMES Multiple Access
`e, April 1998, pp. 16-24.
`Multiple Access Mode
`Conj on Personal Indoor
`l, 1-4 September 1997,
`
`:RAMES Multiple Access
`'ndoor and Mobile Radio
`17, pp. 42-46.
`11ts for the UMTS Terres(cid:173)
`ITS 21.01 version 3.0.1,
`
`Jcedures for the Choice of
`iort, UMTS 30.03 version
`
`Terrestrial Radio Access
`ITS 30.06 version 3.0.0,
`
`ladio Interface for Third
`
`cations Approved in ITU
`
`5
`
`Radio Access Network
`Architecture
`
`Fabio Longoni and Atte Lansisalrni
`
`5.1 System Architecture
`
`This chapter gives a wide overview of the UMTS system architecture, including an intro(cid:173)
`duction to the logical network elements and the interfaces. The UMTS system utilises the
`same well-known architecture that has been used by all main second generation systems
`and even by some first generation systems. The reference list contains the related 3GPP
`specifications.
`The UMTS system consists of a number of logical network elements that each has a
`defined functionality. In the standards, network elements are defined at the logical level,
`but this quite often results in a similar physical implementation, especially since there are a
`number of open interfaces (for an interface to be 'open', the requirement is that it has been
`defined to such a detailed level that the equipment at the endpoints can be from two different
`manufacturers). The network elements can be grouped based on similar functionality, or
`based on which sub-network they belong to.
`Functionally the network elements ar~ grouped into the Radio Access Network (RAN,
`UMTS Terrestrial RAN= UTRAN) that handles all radio-related functionality, and the
`Core Network, which is responsible for switching and routing calls and data connections to
`external l}etworks. To complete the system, the User Equipment (UE) that interfaces with
`the user and the radio interface is defined. The high-level system architecture is shown in
`Figure 5.1.
`From a specification and standardisation point of view, both UE and UTRAN consist of
`completely new protocols, the design of which is based on the needs of the new WCDMA
`radio technology. On the contrary, the definition of CN is adopted from GSM. This gives
`the system with new radio technology a global base of known and rugged CN technology
`that accelerates and facilitates its introduction, and enables such competitive advantages as
`global roaming.
`
`WCDMA for UMTS, edited by Harri Holma and Antti Toskala
`© 2001 John Wiley & Sons, Ltd
`
`APPL-1007 / Page 13 of 41
`
`

`
`52
`
`WCDMA for UMTS
`
`.-----------------------------------.:Uu:'·--············------------------
`
`lu
`
`UE
`
`UT RAN
`
`CN
`
`Figure 5.1. UMTS high-level system architecture
`
`UE)
`
`--------------------------------~-!~~-~)
`Figure 5.2. Network elements in a PLMN
`
`CN
`
`External networks
`'•------------------------------·
`
`Another way to group UMTS network elements is to divide them into sub-networks.
`The UMTS system is modular in the sense that it is possible to have several network
`elements of the same type. In principle, the minimum requirement for a fully featured and
`operational network is to have at least one logical network element of each type (note that
`some features and consequently some network elements are optional). The possibility of
`having several entities of the same type allows the division of the UMTS system into sub(cid:173)
`networks that are operational either on their own or together with other sub-networks, and
`that are distinguished from each other with unique identities. Such a sub-network is called a
`UMTS PLMN (Public Land Mobile Network). Typically one PLMN is operated by a single
`operator, and is connected to other PLMNs as well as to other types of networks, such as
`ISDN, PSTN, the Internet, and so on. Figure 5.2 shows elements in a PLMN and, in order
`to illustrate the connections, also external networks.
`The UTRAN architecture is presented in Section 5 .2. A short introduction to all the
`elements is given below.
`
`The UE consists of two parts:
`
`• The Mobile Equipment (ME) is the radio terminal used for radio communication over
`the Uu interface.
`
`• The UMTS Subscriber Identity Module (USIM) is a smartcard that holds the subscriber
`identity, performs authentication algorithms, and stores authentication and encryption
`keys and some subscription information that is needed at the terminal.
`
`APPL-1007 / Page 14 of 41
`
`

`
`WCDMA for UMTS
`
`Radio Access Network Architecture
`
`53
`
`UTRAN also consists of two distinct elements:
`
`• The Node B converts the data flow between the Iub and Uu interfaces. It also participates
`in radio resource management. (Note that the term 'Node B' from the corresponding
`3GPP specifications is used throughout Chapter 5. The more generic term 'Base Station'
`used elsewhere in this book means exactly the same thing.)
`
`• The Radio Network Controller (RNC) owns and controls the radio resources in its
`domain (the Node Bs connected to it). RNC is the service access point for all services
`UTRAN provides the CN, for example management of connections to the UE.
`
`The main elements of the GSM CN (there are other entities not shown in .Figure 5.2, such
`as those used to provide IN services) are as follows:
`
`• HLR (Home Location Register) is a database located in the user's home system that
`stores the master copy of the user's service profile. The service profile consists of, for
`example, information on allowed services, forbidden roaming areas, and Supplementary
`Service information such as status of call forwarding and the call forwarding number. It
`is created when a new user subscribes to the system, and remains stored as long as the
`subscription is active. For the purpose of routing incoming transactions to the UE (e.g.
`calls or short messages), the HLR also stores the UE location on the level of MSC/VLR
`and/or SGSN, i.e. on the level of serving system.
`
`• MSC/VLR (Mobile Services Switching Centre/Visitor Location Register) is the switch
`(MSC) and database (VLR) that serves the UE in its current location for Circuit Switched
`(CS) services. The MSC function is used to switch the CS transactions, and the VLR
`function holds a copy of the visiting user's service profile, as well as more precise
`information on the UE's location within the serving system. The part of the network
`that is accessed via the MSC/VLR is often referred to as the CS domain.
`
`• GMSC (Gateway MSC) is the switch at the point where UMTS PLMN is connected to
`external CS networks. All incoming and outgoing CS connections go through GMSC.
`• SGSN (Serving GPRS (General Packet Radio Service) Support Node) functionality is
`similar to that of MSC/VLR but is typically used for Packet Switched (PS) services. The
`part of the network that is accessed via the SGSN is often referred to as the PS domain.
`
`• GGSN (Gateway GPRS Support Node) functionality is close to that of GMSC but is in
`relation to PS services.
`
`The external networks can be divided into two groups:
`
`• CS networks. These provide circuit-switched connections, like the existing telephony
`service. ISDN and PSTN are examples of CS networks.
`
`• PS networks. These provide connections for packet data services. The Internet is one
`example of a PS network.
`
`The UMTS standards are structured so that internal functionality of the network elements
`is not specified in detail. Instead, the interfaces between the logical network elements have
`been defined. The following main open interfaces are specified:
`
`CN
`
`tern into sub-networks.
`have several network
`for a fully featured and
`of each type (note that
`ml). The possibility of
`JMTS system into sub(cid:173)
`ither sub-networks, and
`sub-network is called a
`is operated by a single
`:s of networks, such as
`a PLMN and, in order
`
`introduction to all the
`
`o communication over
`
`1at holds the subscriber
`ication and encryption
`ninal.
`
`APPL-1007 / Page 15 of 41
`
`

`
`54
`
`WCDMA for UMTS
`
`• Cu Interface. This is the electrical interface between the USIM smartcard and the ME.
`The interface follows a standard format for smartcards.
`
`• Uu Interface. This is the WCDMA radio interface, which is the subject of the main part
`of this book. The Uu is the interface through which the UE accesses the fixed part of the
`system, and is therefore probably the most important open interface in UMTS. There are
`likely to be many more UE manufacturers than manufacturers of fixed network elements.
`
`•
`
`•
`
`•
`
`Iu Interface. This connects UTRAN to the CN and is introduced in detail in Section 5.4.
`Similarly to the corresponding interfaces in GSM, A (Circuit Switched) and Gb (Packet
`Switched), the open Iu interface gives UMTS operators the possibility of acquiring
`UTRAN and CN from different manufacturers. The enabled competition in this area has
`been one of the success factors of GSM.
`
`Iur Interface. The open Iur interface allows soft handover between RNCs from different
`manufacturers, and therefore complements the open Iu interface. Iur is described in more
`detail in Section 5.5.1.
`Iub Interface. The Iub connects a Node B and an RNC. UMTS is the first commercial
`mobile telephony system where the Controller-Base Station interface is standardised as a
`fully open interface. Like the other open interfaces, open Iub is expected to further moti(cid:173)
`vate competition between manufacturers in this area. It is likely that new manufacturers
`concentrating exclusively on Node Bs will enter the market.
`
`5.2 UTRAN Architecture
`UTRAN architecture is highlighted in Figure 5.3.
`UTRAN consists of one or more Radio Network Sub-systems (RNS). An RNS is a sub(cid:173)
`network within UTRAN and consists of one Radio Network Controller (RNC) and one or
`more Node Bs. RNCs may be connected to each other via an Iur interface. RNCs and Node
`Bs are connected with an Iub Interface.
`Before entering into a brief description of the UTRAN network elements (in this section)
`and a more extensive description of UTRAN interfaces (in the following sections), we
`present the main characteristics of UTRAN that have also been the main requirements for
`
`.. ---·····-----····-----····-------···----·-·····--
`
`Uu
`
`........... LJ.~_)
`
`................................... LJ!.~ . .l\.f'J. )
`
`Figure 5.3. UTRAN architecture
`
`APPL-1007 / Page 16 of 41
`
`

`
`WCDMA for UMTS
`
`Radio Access Network Architecture
`
`55
`
`smartcard and the ME.
`
`:ubject of the main part
`ses the fixed part of the
`ce in UMTS. There are
`ixed network elements.
`
`in detail in Section 5.4.
`itched) and Gb (Packet
`1ossibility of acquiring
`petition in this area has
`
`m RNCs from different
`[ur is described in more
`
`is the first commercial
`'ace is standardised as a
`icpected to further moti(cid:173)
`that new manufacturers
`
`NS). An RNS is a sub(cid:173)
`Jller (RNC) and one or
`3rface. RNCs and Node
`
`lements (in this section)
`'ollowing sections), we
`main requirements for
`
`________ _('._f'.'! __ _
`
`the design of the UTRAN architecture, functions and protocols. These can be summarised
`in the following points:
`
`• Support of UTRA and all the related functionality. In particular, the major impact on
`the design of UTRAN has been the requirement to support soft handover (one terminal
`connected to the network via two or more active cells) and the WCDMA-specific Radio
`Resource Management algorithms.
`• Maximisation of the commonalities in the handling of packet- switched and circuit(cid:173)
`switched data, with a unique air interface protocol stack and with the use of the
`same interface for the connection from UTRAN to both the PS and CS domains of
`the core network.
`• Maximisation of the commonalities with GSM, when possible.
`• Use of the ATM transport as the main transport mechanism in UTRAN.
`
`5.2.1 The Radio Network Controller
`
`The RNC (Radio Network Controller) is the network element responsible for the control of
`the radio resources of UTRAN. It interfaces the CN (normally to one MSC and one SGSN)
`and also terminates the RRC (Radio Resource Control) protocol that defines the messages
`and procedures between the mobile and UTRAN. It logically corresponds to the GSM BSC.
`
`5.2.1.1 Logical Role of the RNC
`The RNC controlling one Node B (i.e. terminating the Iub interface towards the Node B)
`is indicated as the Controlling RNC (CRNC) of the Node B. The Controlling RNC is
`responsible for the load and congestion control of its own cells, and also executes the
`admission control and code allocation for new radio links to be established in those cells.
`In case one mobile-UTRAN connection uses resources from more than one RNS
`(see Figure 5.4), the RNCs involved have two separate logical roles (with respect to this
`mobile-UTRAN connection):
`
`• Serving RNC. The SRNC for one mobile is the RNC that terminates both the Iu link
`for the transport of user data and the corresponding RANAP signalling to/from the
`
`~(
`
`~: ! ........................................ .
`
`Figure 5.4. Logical role of the RNC for one UE UTRAN connection. The left-hand scenario shows
`one UE in inter-RNC soft handover (com