An Introduction to LTE (2^nd Ed.) LTE, LTE-Advanced, SAE, VoLTE and 4G Mobile Communications

Following on from the successful first edition (March 2012), this book gives a clear explanation of what LTE does and how it works. The content is expressed at a systems level, offering readers the opportunity to grasp the key factors that make LTE the hot topic amongst vendors and operators across the globe. The book assumes no more than a basic knowledge of mobile telecommunication systems, and the reader is not expected to have any previous knowledge of the complex mathematical operations that underpin LTE.

This second edition introduces new material for the current state of the industry, such as the new features of LTE in Releases 11 and 12, notably coordinated multipoint transmission and proximity services; the main short- and long-term solutions for LTE voice calls, namely circuit switched fallback and the IP multimedia subsystem; and the evolution and current state of the LTE market. It also extends some of the material from the first edition, such as inter-operation with other technologies such as GSM, UMTS, wireless local area networks and cdma2000; additional features of LTE Advanced, notably heterogeneous networks and traffic offloading; data transport in the evolved packet core; coverage and capacity estimation for LTE; and a more rigorous treatment of modulation, demodulation and OFDMA. The author breaks down the system into logical blocks, by initially introducing the architecture of LTE, explaining the
techniques used for radio transmission and reception and the overall operation of the system, and concluding with more specialized topics such as LTE voice calls and the later releases of the specifications. This methodical approach enables readers to move on to tackle the specifications and the more advanced texts with confidence.

Acknowledgements xxiii

List of Abbreviations xxv

1 Introduction 1

1.1 Architectural Review of UMTS and GSM 1

1.1.1 High-Level Architecture 1

1.1.2 Architecture of the Radio Access Network 2

1.1.3 Architecture of the Core Network 4

1.1.4 Communication Protocols 5

1.2 History of Mobile Telecommunication Systems 6

1.2.1 From 1G to 3G 6

1.2.2 Third Generation Systems 7

1.3 The Need for LTE 8

1.3.1 The Growth of Mobile Data 8

1.3.2 Capacity of a Mobile Telecommunication System 9

1.3.3 Increasing the System Capacity 10

1.3.4 Additional Motivations 11

1.4 From UMTS to LTE 11

1.4.1 High-Level Architecture of LTE 11

1.4.2 Long-Term Evolution 12

1.4.3 System Architecture Evolution 13

1.4.4 LTE Voice Calls 14

1.4.5 The Growth of LTE 15

1.5 From LTE to LTE-Advanced 16

1.5.1 The ITU Requirements for 4G 16

1.5.2 Requirements of LTE-Advanced 16

1.5.3 4G Communication Systems 16

1.5.4 The Meaning of 4G 17

1.6 The 3GPP Specifications for LTE 17

References 19

2 System Architecture Evolution 21

2.1 High-Level Architecture of LTE 21

2.2 User Equipment 21

2.2.1 Architecture of the UE 21

2.2.2 UE Capabilities 22

2.3 Evolved UMTS Terrestrial Radio Access Network 23

2.3.1 Architecture of the E-UTRAN 23

2.3.2 Transport Network 24

2.3.3 Small Cells and the Home eNB 25

2.4 Evolved Packet Core 25

2.4.1 Architecture of the EPC 25

2.4.2 Roaming Architecture 27

2.4.3 Network Areas 28

2.4.4 Numbering, Addressing and Identification 28

2.5 Communication Protocols 30

2.5.1 Protocol Model 30

2.5.2 Air Interface Transport Protocols 31

2.5.3 Fixed Network Transport Protocols 31

2.5.4 User Plane Protocols 32

2.5.5 Signalling Protocols 33

2.6 Example Signalling Flows 34

2.6.1 Access Stratum Signalling 34

2.6.2 Non-Access Stratum Signalling 35

2.7 Bearer Management 36

2.7.1 The EPS Bearer 36

2.7.2 Default and Dedicated Bearers 37

2.7.3 Bearer Implementation Using GTP 38

2.7.4 Bearer Implementation Using GRE and PMIP 39

2.7.5 Signalling Radio Bearers 39

2.8 State Diagrams 40

2.8.1 EPS Mobility Management 40

2.8.2 EPS Connection Management 40

2.8.3 Radio Resource Control 41

2.9 Spectrum Allocation 43

References 45

3 Digital Wireless Communications 49

3.1 Radio Transmission and Reception 49

3.1.1 Carrier Signal 49

3.1.2 Modulation Techniques 50

3.1.3 The Modulation Process 51

3.1.4 The Demodulation Process 53

3.1.5 Channel Estimation 55

3.1.6 Bandwidth of the Modulated Signal 55

3.2 Radio Transmission in a Mobile Cellular Network 56

3.2.1 Multiple Access Techniques 56

3.2.2 FDD and TDD Modes 56

3.3 Impairments to the Received Signal 58

3.3.1 Propagation Loss 58

3.3.2 Noise and Interference 58

3.3.3 Multipath and Fading 58

3.3.4 Inter-symbol Interference 60

3.4 Error Management 61

3.4.1 Forward Error Correction 61

3.4.2 Automatic Repeat Request 62

3.4.3 Hybrid ARQ 63

References 65

4 Orthogonal Frequency Division Multiple Access 67

4.1 Principles of OFDMA 67

4.1.1 Sub-carriers 67

4.1.2 The OFDM Transmitter 68

4.1.3 The OFDM Receiver 70

4.1.4 The Fast Fourier Transform 72

4.1.5 Block Diagram of OFDMA 72

4.1.6 Details of the Fourier Transform 73

4.2 Benefits and Additional Features of OFDMA 75

4.2.1 Orthogonal Sub-carriers 75

4.2.2 Choice of Sub-carrier Spacing 75

4.2.3 Frequency-Specific Scheduling 77

4.2.4 Reduction of Inter-symbol Interference 78

4.2.5 Cyclic Prefix Insertion 79

4.2.6 Choice of Symbol Duration 80

4.2.7 Fractional Frequency Re-use 81

4.3 Single Carrier Frequency Division Multiple Access 82

4.3.1 Power Variations From OFDMA 82

4.3.2 Block Diagram of SC-FDMA 83

References 85

5 Multiple Antenna Techniques 87

5.1 Diversity Processing 87

5.1.1 Receive Diversity 87

5.1.2 Closed Loop Transmit Diversity 88

5.1.3 Open Loop Transmit Diversity 89

5.2 Spatial Multiplexing 90

5.2.1 Principles of Operation 90

5.2.2 Open Loop Spatial Multiplexing 92

5.2.3 Closed Loop Spatial Multiplexing 94

5.2.4 Matrix Representation 96

5.2.5 Implementation Issues 99

5.2.6 Multiple User MIMO 99

5.3 Beamforming 101

5.3.1 Principles of Operation 101

5.3.2 Beam Steering 102

5.3.3 Downlink Multiple User MIMO Revisited 103

References 104

6 Architecture of the LTE Air Interface 105

6.1 Air Interface Protocol Stack 105

6.2 Logical, Transport and Physical Channels 107

6.2.1 Logical Channels 107

6.2.2 Transport Channels 107

6.2.3 Physical Data Channels 108

6.2.4 Control Information 109

6.2.5 Physical Control Channels 110

6.2.6 Physical Signals 111

6.2.7 Information Flows 111

6.3 The Resource Grid 111

6.3.1 Slot Structure 111

6.3.2 Frame Structure 113

6.3.3 Uplink Timing Advance 115

6.3.4 Resource Grid Structure 116

6.3.5 Bandwidth Options 117

6.4 Multiple Antenna Transmission 118

6.4.1 Downlink Antenna Ports 118

6.4.2 Downlink Transmission Modes 119

6.5 Resource Element Mapping 119

6.5.1 Downlink Resource Element Mapping 119

6.5.2 Uplink Resource Element Mapping 121

References 123

7 Cell Acquisition 125

7.1 Acquisition Procedure 125

7.2 Synchronization Signals 126

7.2.1 Physical Cell Identity 126

7.2.2 Primary Synchronization Signal 127

7.2.3 Secondary Synchronization Signal 128

7.3 Downlink Reference Signals 128

7.4 Physical Broadcast Channel 129

7.5 Physical Control Format Indicator Channel 130

7.6 System Information 131

7.6.1 Organization of the System Information 131

7.6.2 Transmission and Reception of the System Information 133

7.7 Procedures after Acquisition 133

References 134

8 Data Transmission and Reception 135

8.1 Data Transmission Procedures 135

8.1.1 Downlink Transmission and Reception 135

8.1.2 Uplink Transmission and Reception 137

8.1.3 Semi Persistent Scheduling 139

8.2 Transmission of Scheduling Messages on the PDCCH 139

8.2.1 Downlink Control Information 139

8.2.2 Resource Allocation 140

8.2.3 Example: DCI Format 1 141

8.2.4 Radio Network Temporary Identifiers 142

8.2.5 Transmission and Reception of the PDCCH 143

8.3 Data Transmission on the PDSCH and PUSCH 144

8.3.1 Transport Channel Processing 144

8.3.2 Physical Channel Processing 146

8.4 Transmission of Hybrid ARQ Indicators on the PHICH 148

8.4.1 Introduction 148

8.4.2 Resource Element Mapping of the PHICH 148

8.4.3 Physical Channel Processing of the PHICH 149

8.5 Uplink Control Information 149

8.5.1 Hybrid ARQ Acknowledgements 149

8.5.2 Channel Quality Indicator 150

8.5.3 Rank Indication 151

8.5.4 Precoding Matrix Indicator 151

8.5.5 Channel State Reporting Mechanisms 151

8.5.6 Scheduling Requests 152

8.6 Transmission of Uplink Control Information on the PUCCH 153

8.6.1 PUCCH Formats 153

8.6.2 PUCCH Resources 154

8.6.3 Physical Channel Processing of the PUCCH 155

8.7 Uplink Reference Signals 155

8.7.1 Demodulation Reference Signal 155

8.7.2 Sounding Reference Signal 156

8.8 Power Control 157

8.8.1 Uplink Power Calculation 157

8.8.2 Uplink Power Control Commands 158

8.8.3 Downlink Power Control 159

8.9 Discontinuous Reception 159

8.9.1 Discontinuous Reception and Paging in RRC_IDLE 159

8.9.2 Discontinuous Reception in RRC_CONNECTED 159

References 161

9 Random Access 163

9.1 Transmission of Random Access Preambles on the PRACH 163

9.1.1 Resource Element Mapping 163

9.1.2 Preamble Sequence Generation 165

9.1.3 Signal Transmission 165

9.2 Non-Contention-Based Procedure 166

9.3 Contention-Based Procedure 167

References 169

10 Air Interface Layer 2 171

10.1 Medium Access Control Protocol 171

10.1.1 Protocol Architecture 171

10.1.2 Timing Advance Commands 173

10.1.3 Buffer Status Reporting 173

10.1.4 Power Headroom Reporting 173

10.1.5 Multiplexing and De-multiplexing 174

10.1.6 Logical Channel Prioritization 174

10.1.7 Scheduling of Transmissions on the Air Interface 175

10.2 Radio Link Control Protocol 176

10.2.1 Protocol Architecture 176

10.2.2 Transparent Mode 177

10.2.3 Unacknowledged Mode 177

10.2.4 Acknowledged Mode 178

10.3 Packet Data Convergence Protocol 180

10.3.1 Protocol Architecture 180

10.3.2 Header Compression 180

10.3.3 Prevention of Packet Loss during Handover 182

References 183

11 Power-On and Power-Off Procedures 185

11.1 Power-On Sequence 185

11.2 Network and Cell Selection 187

11.2.1 Network Selection 187

11.2.2 Closed Subscriber Group Selection 187

11.2.3 Cell Selection 188

11.3 RRC Connection Establishment 189

11.3.1 Basic Procedure 189

11.3.2 Relationship with Other Procedures 190

11.4 Attach Procedure 191

11.4.1 IP Address Allocation 191

11.4.2 Overview of the Attach Procedure 192

11.4.3 Attach Request 192

11.4.4 Identification and Security Procedures 194

11.4.5 Location Update 195

11.4.6 Default Bearer Creation 196

11.4.7 Attach Accept 197

11.4.8 Default Bearer Update 198

11.5 Detach Procedure 199

References 200

12 Security Procedures 203

12.1 Network Access Security 203

12.1.1 Security Architecture 203

12.1.2 Key Hierarchy 204

12.1.3 Authentication and Key Agreement 205

12.1.4 Security Activation 207

12.1.5 Ciphering 208

12.1.6 Integrity Protection 209

12.2 Network Domain Security 210

12.2.1 Security Protocols 210

12.2.2 Security in the Evolved Packet Core 210

12.2.3 Security in the Radio Access Network 211

References 212

13 Quality of Service, Policy and Charging 215

13.1 Policy and Charging Control 215

13.1.1 Quality of Service Parameters 215

13.1.2 Service Data Flows 217

13.1.3 Charging Parameters 218

13.1.4 Policy and Charging Control Rules 219

13.2 Policy and Charging Control Architecture 219

13.2.1 Basic PCC Architecture 219

13.2.2 Local Breakout Architecture 220

13.2.3 Architecture Using a PMIP Based S5/S8 220

13.2.4 Software Protocols 221

13.3 Session Management Procedures 222

13.3.1 IP-CAN Session Establishment 222

13.3.2 Mobile Originated SDF Establishment 223

13.3.3 Server Originated SDF Establishment 224

13.3.4 Dedicated Bearer Establishment 225

13.3.5 PDN Connectivity Establishment 226

13.3.6 Other Session Management Procedures 228

13.4 Data Transport in the Evolved Packet Core 228

13.4.1 Packet Handling at the PDN Gateway 228

13.4.2 Data Transport Using GTP 229

13.4.3 Differentiated Services 230

13.4.4 Multiprotocol Label Switching 231

13.4.5 Data Transport Using GRE and PMIP 231

13.5 Charging and Billing 231

13.5.1 High Level Architecture 231

13.5.2 Offline Charging 232

13.5.3 Online Charging 233

References 234

14 Mobility Management 237

14.1 Transitions between Mobility Management States 237

14.1.1 S1 Release Procedure 237

14.1.2 Paging Procedure 239

14.1.3 Service Request Procedure 239

14.2 Cell Reselection in RRC_IDLE 241

14.2.1 Objectives 241

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

14.2.6 Fast Moving Mobiles 244

14.2.7 Tracking Area Update Procedure 245

14.2.8 Network Reselection 246

14.3 Measurements in RRC_CONNECTED 247

14.3.1 Objectives 247

14.3.2 Measurement Procedure 247

14.3.3 Measurement Reporting 248

14.3.4 Measurement Gaps 249

14.4 Handover in RRC_CONNECTED 250

14.4.1 X2 Based Handover Procedure 250

14.4.2 Handover Variations 252

References 253

15 Inter-operation with UMTS and GSM 255

15.1 System Architecture 255

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

15.2 Power-On Procedures 259

15.3 Mobility Management in RRC_IDLE 259

15.3.1 Cell Reselection 259

15.3.2 Routing Area Update Procedure 260

15.3.3 Idle Mode Signalling Reduction 262

15.4 Mobility Management in RRC_CONNECTED 262

15.4.1 RRC Connection Release with Redirection 262

15.4.2 Measurement Procedures 264

15.4.3 Optimized Handover 265

References 268

16 Inter-operation with Non-3GPP Technologies 271

16.1 Generic System Architecture 271

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 Generic Signalling Procedures 275

16.2.1 Overview of the Attach Procedure 275

16.2.2 Authentication and Key Agreement 276

16.2.3 PDN Connectivity Establishment 278

16.2.4 Radio Access Network Reselection 280

16.3 Inter-Operation with cdma2000 HRPD 280

16.3.1 System Architecture 280

16.3.2 Preregistration with cdma2000 281

16.3.3 Cell Reselection in RRC_IDLE 282

16.3.4 Measurements and Handover in RRC_CONNECTED 283

References 286

17 Self-Optimizing Networks 289

17.1 Self-Configuration of an eNB 289

17.1.1 Automatic Configuration of the Physical Cell Identity 289

17.1.2 Automatic Neighbour Relations 290

17.1.3 Random Access Channel Optimization 291

17.2 Inter-Cell Interference Coordination 292

17.3 Mobility Management 292

17.3.1 Mobility Load Balancing 292

17.3.2 Mobility Robustness Optimization 293

17.3.3 Energy Saving 295

17.4 Radio Access Network Information Management 295

17.4.1 Introduction 295

17.4.2 Transfer of System Information 296

17.4.3 Transfer of Self-Optimization Data 297

17.5 Drive Test Minimization 297

References 298

18 Enhancements in Release 9 301

18.1 Multimedia Broadcast/Multicast Service 301

18.1.1 Introduction 301

18.1.2 Multicast/Broadcast over a Single Frequency Network 302

18.1.3 Implementation of MBSFN in LTE 302

18.1.4 Architecture of MBMS 304

18.1.5 Operation of MBMS 305

18.2 Location Services 306

18.2.1 Introduction 306

18.2.2 Positioning Techniques 306

18.2.3 Location Service Architecture 307

18.2.4 Location Service Procedures 308

18.3 Other Enhancements in Release 9 309

18.3.1 Dual Layer Beamforming 309

18.3.2 Commercial Mobile Alert System 310

References 310

19 LTE-Advanced and Release 10 313

19.1 Carrier Aggregation 313

19.1.1 Principles of Operation 313

19.1.2 UE Capabilities 314

19.1.3 Scheduling 316

19.1.4 Data Transmission and Reception 316

19.1.5 Uplink and Downlink Feedback 317

19.1.6 Other Physical Layer and MAC Procedures 317

19.1.7 RRC Procedures 317

19.2 Enhanced Downlink MIMO 318

19.2.1 Objectives 318

19.2.2 Downlink Reference Signals 318

19.2.3 Downlink Transmission and Feedback 320

19.3 Enhanced Uplink MIMO 321

19.3.1 Objectives 321

19.3.2 Implementation 321

19.4 Relays 322

19.4.1 Principles of Operation 322

19.4.2 Relaying Architecture 323

19.4.3 Enhancements to the Air Interface 324

19.5 Heterogeneous Networks 324

19.5.1 Introduction 324

19.5.2 Enhanced Inter-Cell Interference Coordination 325

19.5.3 Enhancements to Self-Optimizing Networks 326

19.6 Traffic Offload Techniques 326

19.6.1 Local IP Access 326

19.6.2 Selective IP Traffic Offload 327

19.6.3 Multi-Access PDN Connectivity 327

19.6.4 IP Flow Mobility 329

19.7 Overload Control for Machine-Type Communications 330

References 331

20 Releases 11 and 12 333

20.1 Coordinated Multipoint Transmission and Reception 333

20.1.1 Objectives 333

20.1.2 Scenarios 334

20.1.3 CoMP Techniques 335

20.1.4 Standardization 336

20.1.5 Performance 337

20.2 Enhanced Physical Downlink Control Channel 337

20.3 Interference Avoidance for in Device Coexistence 338

20.4 Machine-Type Communications 339

20.4.1 Device Triggering 339

20.4.2 Numbering, Addressing and Identification 340

20.5 Mobile Data Applications 340

20.6 New Features in Release 12 341

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

20.6.4 Traffic Offloading Enhancements 344

20.7 Release 12 Studies 345

20.7.1 Enhancements to Small Cells and Heterogeneous Networks 345

20.7.2 Elevation Beamforming and Full Dimension MIMO 346

References 346

21 Circuit Switched Fallback 349

21.1 Delivery of Voice and Text Messages over LTE 349

21.1.1 The Market for Voice and SMS 349

21.1.2 Third Party Voice over IP 350

21.1.3 The IP Multimedia Subsystem 351

21.1.4 VoLGA 351

21.1.5 Dual Radio Devices 352

21.1.6 Circuit Switched Fallback 353

21.2 System Architecture 353

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

21.2.2 Circuit Switched Fallback Architecture 354

21.3 Attach Procedure 355

21.3.1 Combined EPS/IMSI Attach Procedure 355

21.3.2 Voice Domain Preference and UE Usage Setting 356

21.4 Mobility Management 357

21.4.1 Combined Tracking Area/Location Area Update Procedure 357

21.4.2 Alignment of Tracking Areas and Location Areas 357

21.4.3 Cell Reselection to UMTS or GSM 358

21.5 Call Setup 359

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

21.5.4 Mobile-Terminated Call Setup 363

21.5.5 Returning to LTE 364

21.6 SMS over SGs 365

21.6.1 System Architecture 365

21.6.2 SMS Delivery 365

21.7 Circuit Switched Fallback to cdma2000 1xRTT 366

21.8 Performance of Circuit Switched Fallback 367

References 368

22 VoLTE and the IP Multimedia Subsystem 371

22.1 Introduction 371

22.1.1 The IP Multimedia Subsystem 371

22.1.2 VoLTE 372

22.1.3 Rich Communication Services 372

22.2 Hardware Architecture of the IMS 373

22.2.1 High-Level Architecture 373

22.2.2 Call Session Control Functions 374

22.2.3 Application Servers 375

22.2.4 Home Subscriber Server 375

22.2.5 User Equipment 375

22.2.6 Relationship with LTE 376

22.2.7 Border Control Functions 377

22.2.8 Media Gateway Functions 378

22.2.9 Multimedia Resource Functions 379

22.2.10 Security Architecture 380

22.2.11 Charging Architecture 380

22.3 Signalling Protocols 381

22.3.1 Session Initiation Protocol 381

22.3.2 Session Description Protocol 382

22.3.3 Other Signalling Protocols 382

22.4 Service Provision in the IMS 382

22.4.1 Service Profiles 382

22.4.2 Media Feature Tags 383

22.4.3 The Multimedia Telephony Service for IMS 383

22.5 VoLTE Registration Procedure 384

22.5.1 Introduction 384

22.5.2 LTE Procedures 384

22.5.3 Contents of the REGISTER Request 385

22.5.4 IMS Registration Procedure 387

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 Call Setup and Release 390

22.6.1 Contents of the INVITE Request 390

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

22.6.5 Call Release 396

22.7 Access Domain Selection 397

22.7.1 Mobile-Originated Calls 397

22.7.2 Mobile-Terminated Calls 398

22.8 Single Radio Voice Call Continuity 398

22.8.1 Introduction 398

22.8.2 SRVCC Architecture 399

22.8.3 Attach, Registration and Call Setup Procedures 400

22.8.4 Handover Preparation 400

22.8.5 Updating the Remote Leg 401

22.8.6 Releasing the Source Leg 403

22.8.7 Handover Execution and Completion 403

22.8.8 Evolution of SRVCC 404

22.9 IMS Centralized Services 405

22.10 IMS Emergency Calls 406

22.10.1 Emergency Call Architecture 406

22.10.2 Emergency Call Setup Procedure 407

22.11 Delivery of SMS Messages over the IMS 408

22.11.1 SMS Architecture 408

22.11.2 Access Domain Selection 409

References 410

23 Performance of LTE and LTE-Advanced 413

23.1 Peak Data Rates of LTE and LTE-Advanced 413

23.1.1 Increase of the Peak Data Rate 413

23.1.2 Limitations on the Peak Data Rate 415

23.2 Coverage of an LTE Cell 416

23.2.1 Uplink Link Budget 416

23.2.2 Downlink Link Budget 418

23.2.3 Propagation Modelling 419

23.2.4 Coverage Estimation 420

23.3 Capacity of an LTE Cell 421

23.3.1 Capacity Estimation 421

23.3.2 Cell Capacity Simulations 422

23.4 Performance of Voice over IP 424

23.4.1 AMR Codec Modes 424

23.4.2 Transmission of AMR Frames on the Air Interface 425

23.4.3 Transmission of AMR Frames in the Fixed Network 426

References 427

Bibliography 429

Index 431