An introduction to LTE, 2nd edition

1.1.2 Architecture of the Radio Access Network 21.3.2 Capacity of a Mobile Telecommunication System 9... The book covers the whole of the system, both the techniquesused for radio commun

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AN INTRODUCTION

TO LTE

AN INTRODUCTION

TO LTE

LTE, LTE-ADVANCED, SAE, VoLTE

AND 4G MOBILE COMMUNICATIONS

Second Edition

Christopher Cox

Director, Chris Cox Communications Ltd, UK

This edition first published 2014

© 2014 John Wiley & Sons, Ltd

Registered office

John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com.

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Library of Congress Cataloging-in-Publication Data

Cox, Christopher (Christopher Ian),

1965-An introduction to LTE LTE, LTE-advanced, SAE, VoLTE and 4G mobile communications / Christopher Cox pages cm

To my nieces, Louise and Zoe

1.1.2 Architecture of the Radio Access Network 2

1.3.2 Capacity of a Mobile Telecommunication System 9

viii Contents

2.7.4 Bearer Implementation Using GRE and PMIP 39

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Contents ix

4.2.4 Reduction of Inter-symbol Interference 78

x Contents

5.3.3 Downlink Multiple User MIMO Revisited 103

6.5.1 Downlink Resource Element Mapping 119

7.6.1 Organization of the System Information 131

7.6.2 Transmission and Reception of the System Information 133

8.1.1 Downlink Transmission and Reception 135

8.1.2 Uplink Transmission and Reception 137

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Contents xi

8.2.4 Radio Network Temporary Identifiers 142

8.2.5 Transmission and Reception of the PDCCH 143

8.4.2 Resource Element Mapping of the PHICH 148

8.4.3 Physical Channel Processing of the PHICH 149

8.5.5 Channel State Reporting Mechanisms 151

8.6.3 Physical Channel Processing of the PUCCH 155

8.9.1 Discontinuous Reception and Paging in RRC_IDLE 159

8.9.2 Discontinuous Reception in RRC_CONNECTED 159

xii Contents

10.1.5 Multiplexing and De-multiplexing 174

10.1.7 Scheduling of Transmissions on the Air Interface 175

12.2.2 Security in the Evolved Packet Core 210

12.2.3 Security in the Radio Access Network 211

13.1.4 Policy and Charging Control Rules 219

13.2.3 Architecture Using a PMIP Based S5/S8 220

13.3.2 Mobile Originated SDF Establishment 223

13.3.3 Server Originated SDF Establishment 224

13.3.6 Other Session Management Procedures 228

13.4.1 Packet Handling at the PDN Gateway 228

13.4.5 Data Transport Using GRE and PMIP 231

xiv Contents

14.2.2 Measurement Triggering on the Same LTE Frequency 241

14.2.3 Cell Reselection to the Same LTE Frequency 242

14.2.4 Measurement Triggering on a Different LTE Frequency 243

14.2.5 Cell Reselection to a Different LTE Frequency 244

15.1.1 Architecture of the 2G/3G Packet Switched Domain 255

15.1.2 S3/S4-Based Inter-operation Architecture 257

15.1.3 Gn/Gp-Based Inter-operation Architecture 258

15.4.1 RRC Connection Release with Redirection 262

16.1.1 Network-Based Mobility Architecture 271

16.1.2 Host-Based Mobility Architecture 273

16.1.3 Access Network Discovery and Selection Function 274

16.2.1 Overview of the Attach Procedure 275

16.2.2 Authentication and Key Agreement 276

16.2.4 Radio Access Network Reselection 280

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Contents xv

16.3.4 Measurements and Handover in RRC_CONNECTED 283

17.1.1 Automatic Configuration of the Physical Cell Identity 289

17.1.3 Random Access Channel Optimization 291

17.3.2 Mobility Robustness Optimization 293

17.4.3 Transfer of Self-Optimization Data 297

19.1.6 Other Physical Layer and MAC Procedures 317

xvi Contents

19.2.3 Downlink Transmission and Feedback 320

19.5.2 Enhanced Inter-Cell Interference Coordination 325

19.5.3 Enhancements to Self-Optimizing Networks 326

20.4.2 Numbering, Addressing and Identification 340

20.6.1 Proximity Services and Device to Device Communications 341

20.6.2 Dynamic Adaptation of the TDD Configuration 342

20.6.3 Enhancements for Machine-Type Communications and Mobile Data 344

20.7.1 Enhancements to Small Cells and Heterogeneous Networks 345

20.7.2 Elevation Beamforming and Full Dimension MIMO 346

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Contents xvii

21.2.1 Architecture of the 2G/3G Circuit Switched Domain 353

21.2.2 Circuit Switched Fallback Architecture 354

21.3.1 Combined EPS/IMSI Attach Procedure 355

21.3.2 Voice Domain Preference and UE Usage Setting 356

21.4.1 Combined Tracking Area/Location Area Update Procedure 357

21.4.2 Alignment of Tracking Areas and Location Areas 357

21.5.1 Mobile-Originated Call Setup using RRC Connection Release 359

21.5.2 Mobile Originated Call Setup using Handover 361

21.5.3 Signalling Messages in the Circuit Switched Domain 362

xviii Contents

22.4.3 The Multimedia Telephony Service for IMS 383

22.5.3 Contents of the REGISTER Request 385

22.5.5 Routing of SIP Requests and Responses 388

22.5.6 Third-Party Registration with Application Servers 389

22.5.7 Subscription for Network-Initiated Deregistration 389

22.6.2 Initial INVITE Request and Response 391

22.6.3 Acceptance of the Initial INVITE 393

22.6.4 Establishment of a Call to a Circuit Switched Network 396

22.8.7 Handover Execution and Completion 403

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Contents xix

23.1.2 Limitations on the Peak Data Rate 415

23.4.2 Transmission of AMR Frames on the Air Interface 425

23.4.3 Transmission of AMR Frames in the Fixed Network 426

This book is about the world’s dominant 4G mobile telecommunication system, LTE

In writing the book, my aim has been to give the reader a concise, system level introduction

to the technology that LTE uses The book covers the whole of the system, both the techniquesused for radio communication between the base station and the mobile phone, and thetechniques used to transfer data and signalling messages across the network I have avoidedgoing into excessive detail, which is more appropriate for specialized treatments of individualtopics and for the LTE specifications themselves Instead, I hope that the reader will comeaway from this book with a sound understanding of the system and of the way in which itsdifferent components interact The reader will then be able to tackle the more advanced booksand the specifications with confidence

The target audience is twofold Firstly, I hope that the book will be valuable for engineerswho are working on LTE, notably those who are transferring from other technologies such asGSM, UMTS and cdma2000, those who are experts in one part of LTE but who want to under-stand the system as a whole and those who are new to mobile telecommunications altogether.Secondly, the book should give a valuable overview to those who are working in non technicalroles, such as project managers, marketing executives and intellectual property consultants.Structurally, the book has four parts The first part lays out the foundations that the readerwill need in the remainder of the book Chapter 1 is an introduction, which relates LTE toearlier mobile telecommunication systems and lays out its requirements and key technicalfeatures Chapter 2 covers the architecture of the system, notably the hardware components andcommunication protocols that it contains and its use of radio spectrum Chapter 3 reviews theradio transmission techniques that LTE has inherited from earlier mobile telecommunicationsystems, while Chapters 4 and 5 describe the more recent techniques of orthogonal frequencydivision multiple access and multiple input multiple output antennas

The second part of the book covers the air interface of LTE Chapter 6 is a high level tion of the air interface, while Chapter 7 relates the low level procedures that a mobile phoneuses when it switches on, to discover the LTE base stations that are nearby Chapter 8 coversthe low level procedures that the base station and mobile phone use to transmit and receiveinformation, while Chapter 9 covers a specific procedure, random access, by which the mobilephone can contact a base station without prior scheduling Chapter 10 covers the higher levelparts of the air interface, namely the medium access control, radio link control and packet dataconvergence protocols

descrip-The third part covers the signalling procedures that govern how a mobile phone behaves

In Chapter 11, we describe the high level procedures that a mobile phone uses when itswitches on, to register itself with the network and establish communications with the outside

xxii Preface

world Chapter 12 covers the security procedures used by LTE, while Chapter 13 coversthe procedures that manage the quality of service and charging characteristics of a datastream Chapter 14 describes the mobility management procedures that the network uses tokeep track of the mobile’s location Chapter 15 describes how LTE inter-operates with theearlier technologies of GSM and UMTS, while Chapter 16 discusses inter-operation withother technologies such as wireless local area networks and cdma2000 Chapter 17 covers theself-configuration and self-optimization capabilities of LTE

The final part covers more specialized topics Chapters 18, 19 and 20 describe the ments that have been made to LTE in later releases of the specifications, notably an enhancedversion of the technology that is known as LTE-Advanced Chapters 21 and 22 cover the twomost important solutions for the delivery of voice calls to LTE devices, namely circuit switchedfallback and the IP multimedia subsystem Finally, Chapter 23 reviews the performance ofLTE and discusses the techniques that are used to estimate the coverage and capacity of anLTE network

enhance-LTE has a large number of acronyms, and it is hard to talk about the subject without usingthem However, they can make the material appear unnecessarily impenetrable to a newcomer,

so I have aimed to keep the use of acronyms to a reasonable minimum, often preferring thefull name or a colloquial one There is a full list of abbreviations in the introductory materialand new terms are highlighted using italics throughout the text

I have also endeavoured to keep the book’s mathematical content to the minimum needed

to understand the system The LTE air interface makes extensive use of complex numbers,Fourier transforms and matrix algebra, but the reader will not require any prior knowledge

of these in order to understand the book We do make limited use of complex numbers inChapters 3 and 4 to illustrate our discussion of modulation, and introduce Fourier transformsand matrices in subsections of Chapters 4 and 5 to cover the more advanced aspects of orthog-onal frequency division multiple access and multiple antennas Readers can, however, skip thismaterial without detracting from their overall appreciation of the subject

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Many people have given me assistance, support and advice during the creation of this book

I am especially grateful to Liz Wingett, Susan Barclay, Sophia Travis, Sandra Grayson, MarkHammond and the rest of the publishing team at John Wiley & Sons, Ltd for the expert know-ledge and gentle encouragement that they have supplied throughout the production process

I am indebted to Michael Salmon and Geoff Varrall for encouraging me to write the first tion of this book and to the publishing team at Wiley for requesting a second The advice andfeedback I have received while preparing the manuscript have been invaluable and have given

edi-me many opportunities to correct errors and improve the material In this respect, I would ticularly like to thank Jeff Cartwright, Joseph Hoy, Julian Nolan, Michael Salmon, MohammadAnas, Obi Chiemeka, Pete Doherty, Les Granfield, Karl van Heeswijk, Kit Kilgour and PaulMason I am especially indebted to Nicola Rivers, for her support and encouragement through-out the preparation of the second edition Naturally, the responsibility for any remaining errors

par-or omissions in the text, and fpar-or any lack of clarity in the explanations, is entirely my own.Much of my knowledge of the more detailed aspects of LTE, notably of circuit switched fall-back and the IP multimedia subsystem, has been gathered while delivering courses on behalf

of various training providers I am indebted to the directors and staff of Imagicom, InformaTelecoms Academy, Wray Castle and Mpirical, for the support and learning opportunitiesthat they have provided to me I would also like to extend my thanks to the delegates whohave attended my training courses on LTE Their questions and corrections have extended myknowledge of the subject, while their feedback has regularly suggested ways to explain topicsmore effectively

Several diagrams in this book have been reproduced from the technical specifications forLTE, with permission from the European Telecommunications Standards Institute (ETSI),

© 2013, 2012, 2011, 2010, 2006 3GPP™ TSs and TRs are the property of ARIB, ATIS,CCSA, ETSI, TTA and TTC who jointly own the copyright for them They are subject to fur-ther modifications and are therefore provided to you ‘as is’ for information purposes only.Further use is strictly prohibited

Analysys Mason Limited kindly supplied the market research data underlying the tions of network traffic and operator revenue in Figures 1.6 and 21.1 I would like to extend myappreciation to Hilary Bailey, Morgan Mullooly, Terry Norman and James Allen for provid-ing this information The measurements of network traffic in Figure 1.5 and the subscriptiondata underlying Figures 1.9 and 1.10 are by Ericsson, and I am grateful to Elin Pettersson andSvante Bergqvist for making these available

xxvi List of Abbreviations

CAMEL Customized applications for mobile network enhanced logic

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List of Abbreviations xxvii

DFT-S-OFDMA Discrete Fourier transform spread OFDMA

xxviii List of Abbreviations

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List of Abbreviations xxix

I-CSCF Interrogating call session control function

IEEE Institute of Electrical and Electronics Engineers

xxx List of Abbreviations

MBSFN Multicast/broadcast over a single frequency network

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List of Abbreviations xxxi

xxxii List of Abbreviations

POLQA Perceptual objective listening quality assessment

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List of Abbreviations xxxiii

RA-RNTI Random access radio network temporary identifier

SCC-AS Service centralization and continuity application server

SC-FDMA Single-carrier frequency division multiple access

xxxiv List of Abbreviations

SI-RNTI System information radio network temporary identifier

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List of Abbreviations xxxv

TD-SCDMA Time division synchronous code division multiple access

xxxvi List of Abbreviations

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Introduction

Our first chapter puts LTE into its historical context, and lays out its requirements and keytechnical features We begin by reviewing the architectures of UMTS and GSM, and by intro-ducing some of the terminology that the two systems use We then summarize the history

of mobile telecommunication systems, discuss the issues that have driven the development ofLTE and show how UMTS has evolved first into LTE and then into an enhanced version known

as LTE-Advanced The chapter closes by reviewing the standardization process for LTE

1.1.1 High-Level Architecture

LTE was designed by a collaboration of national and regional telecommunications standards

bodies known as the Third Generation Partnership Project (3GPP) [1] and is known in full as 3GPP Long-Term Evolution LTE evolved from an earlier 3GPP system known as the Universal

Mobile Telecommunication System (UMTS), which in turn evolved from the Global System for Mobile Communications (GSM) To put LTE into context, we will begin by reviewing the

architectures of UMTS and GSM, and by introducing some of the important terminology

A mobile phone network is officially known as a public land mobile network (PLMN), and

is run by a network operator such as Vodafone or Verizon UMTS and GSM share a common

network architecture, which is shown in Figure 1.1 There are three main components, namelythe core network, the radio access network and the mobile phone

The core network contains two domains The circuit switched (CS) domain transports phone

calls across the geographical region that the network operator is covering, in the same way as

a traditional fixed-line telecommunication system It communicates with the public switched

telephone network (PSTN) so that users can make calls to land lines and with the circuit

switched domains of other network operators The packet switched (PS) domain transports data streams, such as web pages and emails, between the user and external packet data networks

(PDNs) such as the internet

The two domains transport their information in very different ways The CS domain uses a

technique known as circuit switching, in which it sets aside a dedicated two-way connection

An Introduction to LTE: LTE, LTE-Advanced, SAE, VoLTE and 4G Mobile Communications, Second Edition.

Christopher Cox.

© 2014 John Wiley & Sons, Ltd Published 2014 by John Wiley & Sons, Ltd.

2 An Introduction to LTE

Radio access network

Core network

Figure 1.1 High-level architecture of UMTS and GSM

for each individual phone call so that it can transport the information with a constant datarate and minimal delay This technique is effective, but is rather inefficient: the connectionhas enough capacity to handle the worst-case scenario in which both users are speaking at thesame time, but is usually over-dimensioned Furthermore, it is inappropriate for data transfers,

in which the data rate can vary widely

To deal with the problem, the PS domain uses a different technique, known as packet

switch-ing In this technique, a data stream is divided into packets, each of which is labelled with the

address of the required destination device Within the network, routers read the address labels

of the incoming data packets and forward them towards the corresponding destinations Thenetwork’s resources are shared amongst all the users, so the technique is more efficient thancircuit switching However, delays can result if too many devices try to transmit at the sametime, a situation that is familiar from the operation of the internet

The radio access network handles the core network’s radio communications with the user In Figure 1.1, there are actually two separate radio access networks, namely the GSM EDGE radio

access network (GERAN) and the UMTS terrestrial radio access network (UTRAN) These

use the different radio communication techniques of GSM and UMTS, but share a commoncore network between them

The user’s device is known officially as the user equipment (UE) and colloquially as the

mobile It communicates with the radio access network over the air interface, also known as

the radio interface The direction from network to mobile is known as the downlink (DL)

or forward link and the direction from mobile to network is known as the uplink (UL) or

reverse link.

A mobile can work outside the coverage area of its network operator by using the resources

from two public land mobile networks: the visited network, where the mobile is located and the operator’s home network This situation is known as roaming.

1.1.2 Architecture of the Radio Access Network

Figure 1.2 shows the radio access network of UMTS The most important component is

the base station, which in UMTS is officially known as the Node B Each base station has

one or more sets of antennas, through which it communicates with the mobiles in one or

more sectors As shown in the diagram, a typical base station uses three sets of antennas to

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