Understanding Cellular Radio

Contents
Preface xi
Objectives xi
Acknowledgments xii
Part I Wireless Communications Systems 1
1 Introduction 3
1.1 Why a book simply explaining technical aspects? 3
1.2 Scope of material covered 4
1.3 Acronyms, abbreviations, and other ways to make it
1.3 complicated 4
1.4 How to read this book 5
1.5 Further reading 6
2 Overview of a Cellular System 7
2.1 Introduction 7
2.2 Why it is called cellular? 7
2.3 System overview 9
3 Basic Cellular System Design 21
3.1 Introduction 21
3.2 The scarcity of radio spectrum 22
3.3 The use of cells as a means to conserve spectrum 27
3.4 Why one channel can serve many users 31
3.5 Basic network design principles 35
3.6 Connecting up the network 41
3.6.1 Leased link 42
3.6.2 Microwave links 43
3.6.3 Satellite links 46

Part II Getting Calls to Moving Subscribers 49
4 Keeping Track of Where the Users Are 51
4.1 Introduction 51
4.2 The concept of location areas 51
4.3 Attach and detach 53
4.4 Periodic location updating 54
4.5 The mobile in a call 55
5 How Calls are Made Between Two Users 57
5.1 Introduction 57
5.2 Paging 57
5.3 Responding to a paging message 59
6 Hand-off 69
6.1 The mobile in a call 69
6.2 Handing the mobile to another cell 69
6.3 Cell selection in idle mode 71
7 Network Management, Roaming, and Authentication 73
7.1 Network management 73
7.1.1 Monitoring the correct working of the network 74
7.1.2 Delivering network statistics 74
7.1.3 Changing network configuration 75
7.1.4 Adding and deleting subscribers 75
7.1.5 Generating bills 76
7.1.6 Monitoring fraud 77
7.1.7 Providing customer care 77
7.2 International roaming 78
7.3 Authentication and ciphering 79
7.4 Call routing 82
Part III Transmitting the Signal 85
8 Radio Propagation 87
8.1 Introduction 87
8.1.1 Distance-related attenuation 89
8.1.2 Slow fading 91
8.1.3 Fast fading 91
8.2 Wideband channels 94
8.3 Predicting cellular coverage 95
8.4 Sectorization 96
8.5 Microcells and underlay/overlay networks 98
9 Radio Systems 101
9.1 From speech to radio waves 101
9.2 Speech coding 102
9.3 Error correction coding and interleaving 106
9.4 Interleaving 110
9.5 Modulation 111
9.6 Frequency hopping 112
9.6.1 Overcoming fading 112
9.6.2 Reducing interference 114
9.7 Equalization 116
9.8 Multiple access 118
9.8.1 FDMA 120
9.8.2 TDMA 121
9.8.3 CDMA 123
9.8.4 CDMA power control 132
9.9 Packet and circuit switching 133
10 TDMA or CDMA 137
10.1 Introduction to the debate 137
10.2 A more general look at CDMA versus TDMA 138
10.2.1 Division of the frequencies 140
10.2.2 Distributing the interference 140
10.2.3 Making TDMA interference more even 141
10.3 Comparison of advantages and disadvantages 142
10.3.1 Capacity 142
10.3.2 Greater range 143
10.3.3 Sectorization 143
10.3.4 No frequency planning 145
10.3.5 Macrocell/microcell 145
10.3.6 Risk 147
10.3.7 Cost 147
10.3.8 Bandwidth flexibility 147
10.3.9 Frequency hopping versus direct sequence 147
10.4 Summary 148
Part IV Specific Radio Systems 151
11 Cellular Systems 153
11.1 The difference between analog and digital cellular 153
11.2 Cellular systems in overview 155
11.3 GSM 160
11.3.1 Framing format 160
11.3.2 How mobiles measure adjacent cells 174
11.3.3 Numbering scheme 175
11.3.4 Spectrum efficiency 176
11.4 CDMAone 177
11.4.1 Soft hand-off 181
12 Cordless Systems 183
12.1 Overview of cordless 183
12.2 DECT 185
12.3 PHS 187
13 Overview of Wireless Local Loop Systems 191
13.1 Introduction 191
13.2 Access technologies 194
13.3 The attraction of WLL systems 197
13.4 Current status of WLL 200
13.5 The differences between WLL and cellular 201
13.6 WLL propagation 201
13.6.1 Fast fading 203
13.6.2 New obstructions 204
13.6.3 Rainfall 204
14 WLL Technologies 207
14.1 Introduction 207
14.2 The Lucent AirLoop WLL system 208
14.2.1 Local exchange (termed a switch in GSM) 211
14.2.2 CATU (termed a base station controller in GSM) 211
14.2.3 CTRU (termed a base station in GSM) 212
14.2.4 The subscriber unit (mobile in GSM) 212
14.3 DECT as a WLL technology 212
15 The Future of WLL 217
15.1 Introduction 217
15.2 Technical advances in WLL 218
15.3 Technical advances in other access techniques 219
15.4 Changing user demand 220
15.5 Predictions for WLL 222
16 Satellite Systems 225
16.1 Why use satellites? 225
16.2 How satellite systems work 226
16.3 Will satellite systems be successful? 227
17 The Future of Cellular 231
17.1 What could be better than current systems? 231
17.2 The third-generation ideal 232
17.2.1 GSM evolution 235
17.3 Mobile/fixed convergence 237
17.4 The longer term future 238
Bibliography 241
Model Answers 247
Glossary 257
About The Author 271
Index 273

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