tv '2s.\--qq T! Reservation - Time Division Multiple Access Protocols for Wireless Personal Communications Theodore V. Buot B.S.Eng (Electro&Comm), M.Eng (Telecomm) Thesis submitted for the degree of Doctor of Philosophy 1n The University of Adelaide Faculty of Engineering Department of Electrical and Electronic Engineering August 1997 Contents Abstract IY Declaration Y Acknowledgments YI List of Publications Yrt List of Abbreviations Ylu Symbols and Notations xi Preface xtv L.Introduction 1 Background, Problems and Trends in Personal Communications and description of this work 2. Literature Review t2 2.1 ALOHA and Random Access Protocols I4 2.1.1 Improvements of the ALOHA Protocol 15 2.1.2 Other RMA Algorithms t6 2.1.3 Random Access Protocols with Channel Sensing 16 2.1.4 Spread Spectrum Multiple Access I7 2.2Fixed Assignment and DAMA Protocols 18 2.3 Protocols for Future Wireless Communications I9 2.3.1 Packet Voice Communications t9 2.3.2Reservation based Protocols for Packet Switching 20 2.3.3 Voice and Data Integration in TDMA Systems 23 3. Teletraffic Source Models for R-TDMA 25 3.1 Arrival Process 26 3.2 Message Length Distribution 29 3.3 Smoothing Effect of Buffered Users 30 3.4 Speech Packet Generation 32 3.4.1 Model for Fast SAD with Hangover 35 3.4.2Bffect of Hangover to the Speech Quality 38 3.5 Video Traffic Models 40 3.5.1 Infinite State Markovian Video Source Model 41 3.5.2 AutoRegressive Video Source Model 43 3.5.3 VBR Source with Channel Load Feedback 43 3.6 Summary 46 4. Performance Analysis of R-TDMA 48 4.1 System Model 48 4.1.1 Channel 49 4.1.2 Slot Reservation 49 4. 1.3 Immediate First Transmission 50 4.l.4Effect of Random Access Collisions 51 4.1.5 Single Carrier System 51 4. 1.6 State (In)DePendence 51 4.2 Analysis Methods 52 4.3 Approximation of a Slotted Random Access Protocol 55 4.3. 1 Finite Population ALOHA 51 4.3.2 Binary Exponential B ack-off 58 4.4 Analysis of the Channel Allocation Queue 6r 4.4.1 System Model (R-TDMA Channel Allocation) 6r 4.4.2 Solving the Steady-State Occupancy 62 4.4.3 Analysis of the Queue 65 4.5 System Model for R-TDMA Protocols 67 4.5.1 S-G Analysis 69 4.5.2 Effect of Retransmission Probability 7l 4.5.3 Stability of ATDMA 73 4.5.4Mean Delay Analysis of ATDMA 75 4.6 Summary 78 5. Reservation-TDMA Protocols for WPC 80 5.1 WPC with R-TDMA Multiaccess Protocol 80 5. 1.1 Logical Channel Structure 83 5.1.2 R-TDMA Support for Voice Traffic 84 5.1.3 R-TDMA Support for Data Traffic 85 5.2 R-TDMA Performance with Packet Voice Traffic 85 5.2.1 Contention Process 86 5.2.2 Channel Allocation Process 87 5.2.3 Results based on the model 89 5.3 Reservation Policy for Data Users 91 5.3.1 Immediate Assignment Allocation Scheme 91 5.3.2 Performance ComParison 92 5.4 Enhancements to the R-TDMA Protocol 94 5.4.1 Effect of Capture and Forward Error Correction 94 5.4.2 Capture and Antenna Beam Overlap 96 5.4.3 R-TDMA with Dynamic Frame Configuration 98 5 .4.4 Integrated Voice lD ata ATDMA Protocol 101 5.5 Multipriority Channel Access 106 5.5.1 Stack Algorithm 107 5.5.2 Approach to Stack Prioritisation 110 5.5.3 Multipriority Stack Algorithm 115 5.6 ATDMA with Stack Algorithm rtl 5.6.1 Analysis of ATDMA with Stack CRA using TFA rt7 5.6.2Yolce and Data Prioritised Stack ATDMA r20 5.7 Random Access and Polling Solution r23 5.7. I Protocol DescriPtion 123 5.1.2 State Transition CYcle 126 5.7.3 ThroughpulDelay Approximation 126 5.7.4 Calcttlation based on the Polling Cycle t28 5.7.5 Stability 130 5.7.6 Simulation Model 131 5.7.7 Base Station Polling Control t32 5.8 Integrated-ScARP Protocol r32 5.9 Summary of Chapter 5 t34 ll 6. MultiMedia Access Protocol 135 6.1 Multislot Reservation for MultiMedia R-TDMA 136 6.1.1 Multislot Allocation Schemes and Fairness Criteria r37 6.1.2 Approximate Analysis using Birth & Death Markov Chains 138 6.1.3 Approximate Analysis using Discrete Markov Analysis r4l 6.2 Multislot Reservation with Multiclass Users 151 6.2.1 Simple Algorithms for Multislot Systems with Heterogeneous Users t52 6.2.2 B est Effort Algorithms for Priori tised Multislot S y stems 153 6.2.3 Simulation Parameters 156 6.3.4 Discussion r59 6.2.5 Summary 160 6.3 Multislot Reservation with Mixed Traffic r63 6.3.1 Reservation Policy for Mixed Traffic t63 6.3.2 Simulation Model 165 6.3.3 Simulation Results and Observations 166 6.4 Variable Coding Rate Multislot Multimedia System 172 6.4.1 Channel Model 173 6.4.2 Channel Coding 174 6.4.3 Simulation Model n5 6.4.4 Summary 17l 6.5 QoS Maintenance for'Wireless Video Transmission 181 6.5.1 System Model 181 6.5.2 Static Optimisation for Video/Data System 183 6.5.3 Video with Dynamic Load Feedback 184 6.5.4 Simulations and Observations r87 6.5.6 Summary of Chapter 6 r87 7. Conclusions 190 7.1 Thesis Summary 190 7.2 Future Work 193 Appendices A Sample Data Source with Buffering 195 B ATDMA Performance 196 C Simulation on the Stability of S-ALOHA 200 D Rough Approximation of R-TDMA with Voice Traffic 202 E Derivation of the Stack Splitting Parameter 203 F Results of the Multiclass Stack Simulations 205 G Results of the SCARP Simulations 208 H Results of the Multiclass Multislot Simulation 2t0 References zll Bibliography 223 lll Abstract Packet switching technology is seen to provide more capacity and flexibility for future Wireless Personal Communications (WPC). A reservation based multiple access protocol has been considered to support packet-switched access in the wireless environment. This thesis is aimed to improve the design and performance of Reservation based Time Division Multiple Access (R-TDMA) protocols for WPC. To provide an efficient voice and data integration, the R-TDMA protocol must support the following, a) fast channel access, b) variable rate transmission and c) fast error recovery. The first two design criteria are essential for all traffic types while the third criteria is required for delay sensitive and error sensitive services. R-TDMA protocol is chosen due to the ease of providing a steady, bursty and variable rate traffic after the design criteria are satisfied. To provide a fast channel access, many possibilities were explored like the use of prioritisation at the random access, the use of stack algorithm, the exploitation of the capture probability by improving the topology and the use of a polling mechanism to support the random access. For the support of a variable rate transmission, the TDMA frame structure is exploited by employing a multislot reservation. It is required by services which are sensitive to the message delivery time and services characterised by multirate transmission. It is used in the provision of priority control for multiclass and mixed traffic. The other aspect of this thesis is the derivation of some performance evaluation tools. The performance evaluation consists of a source traffic modelling and characterisation and the derivations of analytical procedures. Approximations were mainly used and were sustained with simulations. For voice traffic, the packet dropping rate is used as a design benchmark. Multiplexing gains for packet-voice in the order of 1.8 to 2.3 were found to be achievable. For the data traffic, both the mean and the cumulative delay perforrnance benchmarks were considered. The support of video traffic is also investigated which suggests a coding scheme in order to transmit a high quality video. The overall assessment suggests that R-TDMA is a potential technology for WPC. lv Declaration This work contains no material which has been accepted for the award of any other degree or diploma in any university or other tertiary institution and, to the best of my knowledge and belief, contains no material previously published or written by another person, except where due reference has been made in the text. I give consent to this copy of my thesis, when deposited in the University Library, being available for load and photocopying. / ç t¿l étr,tT | ??7 SIGNED DATE: v Acknowledgments I would like to thank all individuals and institutions who on in some way or another has rendered valuable inputs and supports to bring this manuscript into completion. I would like to express my sincere thanks to my supervisor, Prof. Reg Coutts for his constant academic, financial and moral support during my three and a half years of research at the Centre for Telecommunications Information Networking (CTIN) of the University of Adelaide. His very long experience in both industry and research has provided me with valuable inputs regarding the direction of this research. I am indebted to Fujio Watanabe for our constant collaboration during the entire period of this research. His comments and those of his colleagues of the Communications Research Laboratory (CRL, Japan) has provided me with good insights in conducting my performance evaluations. I would also to thank my peers in CTIN, Martin Ostrowski, Dohun Kwon, Yu-ShaoKai and others with there valuable discussions and comments. I am also grateful to John Leske, Derek Rogers, Tony Smith and Sergey Nesterov as well as all the staff of CTIN who answered my needs and not to forget Collette Snowden for editing this document.