Wireless Local Loops: Theory and Applications

The demand for greater flexibility both in bandwidth allocation as well as in geographical terms has opened up the new application area of Wireless Local Loops (WLL). WLL provide a telephone system where subscribers are connected to the Public Switches Telephone Network (PSTN) using radio signals rather than copper wire for part or all of the connection between the subscriber and the switch. Divided into two parts, theoretical aspects and applications, Wireless Local Loops brings together contributions from leading world experts in this increasingly important section of wireless communication systems. - Covers all aspects of WLL from design to implementation. - Explains the theoretical aspects of WLL including areas such as propagation, modulation, coding, channel modelling and also traffic engineering issues. - Presents the applications areas of WLL including interference, prototype designs of various access protocols, a mobility manager, a remote management systems and the provision of multimedia services. By providing a self-contained treatment of the progressively important area Wireless Local Loops will have immense appeal to practising engineers, researchers and graduate students needing to understand the bakground to WLL and its major role in the provision of new services.

Table of Contents:
List of Contributors xi Preface xv Acknowledgement xvii Part I Theoretical aspects 1 1 Introduction to WLL: Digital Service Technologies 3 1.1 Background 3 1.2 Advantages of Wireless Systems 5 1.3 WLL Service Requirements 6 1.4 Generic WLL System Architecture 9 1.5 WLL System Technologies 14 1.6 Comparison of WLL Services 29 Appendix A Fixed versus Mobile Cellular Systems 30 Appendix B CDMA versus TDMA in WLL 31 References 33 2 Propagation Models for Wireless Local Loops 35 2.1 Introduction 35 2.2 WLL System Configuration 36 2.3 Delay Spread in WLL Environments 37 2.4 Components of Overall Path Loss 39 2.5 Path Loss Models 43 2.6 Comparison of Propagation Models 55 References 55 2 Propagation Models for Wireless Local Loops 35 2.1 Introduction 35 2.2 WLL System Configuration 36 2.3 Delay Spread in WLL Environments 37 2.4 Components of Overall Path Loss 39 2.5 Path Loss Models 43 2.6 Comparison of Propagation Models 55 References 55 3 Wireless Local Loop Networks Capacity Enhancement by Space Division Multiple Access 57 3.1 Introduction 57 3.2 Background 57 3.3 Technologies for the First Generation of Wireless Local Loop 63 3.4 Multiple Access Techniques 70 3.5 Simulation Description 75 3.6 Performance Results 76 References 77 4 Combined Trellis Coded Quantization/Modulation over a Wireless Local Loop Environment 81 4.1 Introduction 81 4.2 Fundamentals of Trellis Coded Modulation 81 4.3 General Aspects of Combined Trellis Coded Quantization Modulation Schemes 83 4.4 Basic Model 88 4.5 An Example: 4-State 8-Psk Combined Trellis Coded Quantization/Modulation 95 References 99 5 Low Sequency W-CDMA Codes Lead to More Economic WLL and Infostation Terminals 101 5.1 Introduction 101 5.2 Code Selection and Generation 104 5.3 Infostation Transmitter 106 5.4 Terminal Receiver 107 5.5 Simplified Signal Processing for a Low Data Terminal 108 5.6 Noise Analysis and Processing Gain 110 References 112 6 Wide-band Wireless Outdoor to Indoor Local Loop Channel Models for Urban and Suburban Environments at 2 GHz 115 6.1 Introduction 115 6.2 Experimental Procedure 116 6.3 Data Processing 120 6.4 Channel Parameters 123 6.5 Channel Model 131 References 139 7 Traffic Considerations in Comparing Access Techniques for WLL 141 7.1 Introduction 141 7.2 Fixed Wireless Access Networks 142 7.3 Multiple Access Technologies 144 7.4 CDMA Capacity Analysis 146 7.5 Comparison of TDMA and CDMA Results 159 List of Abbreviations 161 References 161 8 Traffic Based Dynamic Channel Allocation Schemes for WLL 163 8.1 Introduction 163 8.2 Access on Allocation Technologies 163 8.3 FWA Network Scenarios 168 8.4 Simulations Results of DCA in FWA Networks 178 List of Abbreviations 189 References 190 9 WLL as an Interferer 191 9.1 Introduction 191 9.2 System Overview of WLL as an Interferer 194 9.3 Architecture of WLL as an Interferer 201 9.4 Problem Definition 201 9.5 Description of the Systems 202 9.6 Spectral Characteristics of Signals 210 9.7 Interference Effects Analysis 214 9.8 Study Case 217 References 228 Part II Applications 231 10 Development of a Prototype of the Broadband Radio Access Integrated Network 233 10.1 Introduction 233 10.2 System Overview 234 10.3 MAC Protocol: RS-ISMA 236 10.4 BRAIN Indoor LAN Prototype 240 References 245 11 PBX based Mobility Manager for WLL 247 11.1 Introduction 247 11.2 A Computer-controlled PBX Architecture 247 11.3 Mobility Management for PBX 248 11.4 Registration Procedures 252 11.5 Call Termination 255 11.6 Performance Issues 258 References 260 12 Remote Management and Upgrade in a Wireless Local Loop System 261 12.1 Introduction 261 12.2 Wireless Local Loop Application Overview 262 12.3 Remote Upgrade of Fixed Subscriber Units 263 12.4 Event Logging for Remote Management 266 References 270 13 Current and Future Services Using Wireless Local Loop (WLL) Systems 271 13.1 Introduction 271 13.2 WLL System Architecture 272 13.3 WLL Service Requirements 274 13.4 Services with Currently Available Systems 276 13.5 Further Considerations for Multimedia Services 280 References 281 Index 283