MOBILITY MODELS FOR NEXT GENERATION WIRELESS NETWORKS AD HOC, VEHICULAR AND MESH NETWORKS Paolo Santi Istituto di Informatica e Telematica del CNR, Italy WILEY A John Wiley & Sons, Ltd., Publication
Contents List of Figures xv List of Tables xxiii About the Author xxv Preface xxvii Acknowledgments xxxiii List of Abbreviations xxxv Part I INTRODUCTION 1 Next Generation Wireless Networks 3 1.1 WLAN and Mesh Networks 5 1.2 Ad Hoc Networks 8 1.3 Vehicular Networks 10 1.4 Wireless Sensor Networks 13 1.5 Opportunistic Networks 14 References 16 2 Modeling Next Generation Wireless Networks 19 2.1 Radio Channel Models 20 2.2 The Communication Graph 26 2.3 The Energy Model 31 References 32 3 Mobility Models for Next Generation Wireless Networks 33 3.1 Motivation 33 3.2 Cellular vs. Next Generation Wireless Network Mobility Models 35 3.3 A Taxonomy of Existing Mobility Models 38
viii Contents 3.3.1 Spatial Scope 39 3.3.2 Application Scenario 40 3.3.3 Nature 41 3.3.4 Correlation 41 3.3.5 Geography 42 3.3.6 Trajectory 42 3.4 Mobility Models and Real-World Traces: The CRAWDAD Resource 43 3.5 Basic Definitions 45 References 47 Part II "GENERAL-PURPOSE" MOBILITY MODELS 4 Random Walk Models 51 4.1 Discrete Random Walks 52 4.1.1 Random Walks on Grids 53 4.1.2 Random Walks on Graphs 54 4.2 Continuous Random Walks 55 4.2.1 Brownian Motion 55 4.2.2 Levy flight 56 4.3 Other Random Walk Models 57 4.4 Theoretical Properties of Random Walk Models 58 4.4.1 Stationary Node Spatial Distribution 58 4.4.2 The Level-Crossing Phenomenon 59 4.4.3 Hitting Time, Return Time, and Cover Time 60 References 60 5 The Random Waypoint Model 61 5.1 The RWP Model 62 5.2 The Node Spatial Distribution of the RWP Model 64 5.3 The Average Nodal Speed of the RWP Model 69 5.4 Variants of the RWP Model 73 References 74 6 Group Mobility and Other Synthetic Mobility Models 75 6.1 The RPGM Model 76 6.1.1 RPGM with RWP Group Mobility 79 6.1.2 In-Place Mobility Model 79 6.1.3 Convention Mobility Model 80 6.1.4 RPGM and Other Group Mobility Models 82 6.2 Other Synthetic Mobility Models 83 6.2.7 The Smooth Random Mobility Model 83
Contents ix 6.2.2 Gauss-Markov Mobility Model \ 86 References 87 7 Random Trip Models 89 7.1 The Class of Random Trip Models 89 7.1.1 Conditions on Phase and Path 91 7.1.2 Conditions on Trip Duration 92 7.2 Stationarity of Random Trip Models 93 7.3 Examples of Random Trip Models 94 7.3.1 Random Waypoint Model 94 7.3.2 RWP Variants 96 > 7.3.3 Other Random Trip Mobility Models 97 References 98 Part III MOBILITY MODELS FOR WLAN AND MESH NETWORKS 8 WLAN and Mesh Networks 101 8.1 WLAN and Mesh Networks: State of the Art 101 8.1.1 Network Architecture 102 8.7.2 The IEEE 802.11 Standard 104 8.2 WLAN and Mesh Networks: User Scenarios 107 8.2.1 Home WLAN 107 8.2.2 Campus/Corporate WLAN 107 8.2.3 Public Area Hotspots 108 8.2.4 Community Mesh Network 109 8.3 WLAN and Mesh Networks: Perspectives 109 8.4 Further Reading 111 References 111 9 Real-World WLAN Mobility 113 9.1 Real-World WLAN Traces 113 9.2 Features of WLAN Mobility 116 References 119 10 WLAN Mobility Models 121 10.1 The LH Mobility Model 122 10.1.1 Estimating the Transition and Steady-State Probabilities 123 10.1.2 Finding Temporal Correlation in User/AP Association Patterns 124 10.1.3 Timed Location Prediction with the LH Model 127
X Contents 10.2 The KKK Mobility Model 129 10.2.1 Extracting Physical Movement Trajectories from WLAN Traces 129 10.2.2 Extracting Pause Time 132 10.2.3 Dealing with Stationary Sub-Traces 133 10.2.4 Finding Hotspot Locations 133 10.2.5 Mobility Modeling 135 10.3 Final Considerations and Further Reading 137 References 138 Part IV MOBILITY MODELS FOR VEHICULAR NETWORKS 11 Vehicular Networks 141 11.1 Vehicular Networks: State of the Art 141 11.1.1 Motivation 143 11.1.2 Standardization Activities 144 11.2 Vehicular Networks: User Scenarios 146 11.2.1 Active Safety Applications 147 11.2.2 Cooperative Traffic Efficiency Applications 149 11.2.3 Cooperative Local Services 150 11.2.4 Global Internet Services 150 11.3 Vehicular Networks: Perspectives 150 11.4 Further Reading 151 References 152 12 Vehicular Networks: Macroscopic and Microscopic Mobility Models 153 12.1 Vehicular Mobility Models: The Macroscopic View 154 12.2 Vehicular Mobility Models: The Microscopic View 156 12.3 Further Reading 157 References 158 13 Microscopic Vehicular Mobility Models 159 13.1 Simple Microscopic Mobility Models 159 13.1.1 The Graph-Based Mobility Model 159 13.1.2 The Freeway Mobility Model 160 13.1.3 The Manhattan Mobility Model 163 13.2 The SUMO Mobility Model 164 13.2.1 Building the Road Network 166 13.2.2 Building the Traffic Demand 167
Contents xi 13.2.3 Route Computation 167 13.2.4 Running the Simulation and Generating Output 168 13.3 Integrating Vehicular Mobility and Wireless Network Simulation 168 13.3.1 The TraCI Interface for Coupled Vehicular Network Simulation 170 References 172 Part V MOBILITY MODELS FOR WIRELESS SENSOR NETWORKS 14 Wireless Sensor Networks 175 14.1 Wireless Sensor Networks: State of the Art 175 14.1.1 Hardware and Software Platforms 111 14.1.2 Standardization Activities 111 14.2 Wireless Sensor Networks: User Scenarios 180 14.2.1 Environmental Monitoring 180 14.2.2 Industrial Monitoring 181 14.2.3 Health and Well-Being Monitoring 181 14.2.4 Precision Agriculture 181 14.2.5 Seismic, Structural, and Building Monitoring 182 14.2.6 Intrusion Detection 182 14.2.7 Tracking of Objects, People, and Animals 183 14.3 WSNs: Perspectives 183 14.4 Further Reading 184 References 184 15 Wireless Sensor Networks: Passive Mobility Models 185 15.1 Passive Mobility in WSNs 186 15.2 Mobility Models for Wildlife Tracking Applications 187 15.2.1 The ZebraNet Mobility Model 187 75.2.2 The Whale Mobility Model 190 15.3 Modeling Movement Caused by External Forces 191 References 194 16 Wireless Sensor Networks: Active Mobility Models 197 16.1 Active Mobility of Sensor Nodes 198 16.1.1 Active Mobility and Sensing Coverage 198 16.1.2 Motion Control for Sensing Coverage 201 16.1.3 Motion Control for Event Tracking 206
xii Contents 16.2 Active Mobility of Sink Nodes 208 16.2.1 The Data MULE Concept 209 76.2.2 Sink Mobility for Network Lifetime Maximization 210 References 212 Part VI MOBILITY MODELS FOR OPPORTUNISTIC NETWORKS 17 Opportunistic Networks 217 17.1 Opportunistic Networks: State of the Art 217 17.2 Opportunistic Networks: User Scenarios 219 17.2.1 User Scenarios in PSNs 220 17.2.2 User Scenarios in WSNs 221 17.2.3 User Scenarios in Vehicular Networks 221 17.3 Opportunistic Networks: Perspectives 222 17.4 Further Reading 223 References 223 18 Routing in Opportunistic Networks 225 18.1 Mobility-Assisted Routing in Opportunistic Networks 225 18.1.1 Single-Copy Protocols 227 18.1.2 Multi-Copy Protocols 229 18.2 Opportunistic Network Mobility Metrics 231 18.2.1 The Expected Meeting Time 231 18.2.2 The Inter-Meeting Time 232 18.2.3 Contact Duration 233 18.2.4 Relating the Three Metrics 234 References 235 19 Mobile Social Network Analysis 237 19.1 The Social Network Graph 238 19.2 Centrality and Clustering Metrics 239 19.2.1 Centrality Metrics 240 19.2.2 Clustering Metrics 242 19.3 Characterizations of Human Mobility 244 19.3.1 Characterization of Individual Human Mobility Patterns 245 19.3.2 Characterization of Pairwise Contact Patterns 247 19.4 Further Reading 250 References 250
Contents xiii 20 Social-Based Mobility Models 251 20.1 The Weighted Random Waypoint Mobility Model 252 20.2 The Time-Variant Community Mobility Model 254 20.3 The Community-Based Mobility Model 256 20.4 The SWIM Mobility Model 259 20.5 The Self-Similar Least Action Walk Model 264 20.6 The Home-MEG Model 267 20.7 Further Reading 270 References 271 Part VII CASE STUDIES 21 Random Waypoint Model and Wireless Network Simulation 275 21.1 RWP Model and Simulation Accuracy 276 21.2 Removing the Border Effect 278 21.2.1 The Temporal-RWP Model 279 27.2.2 The Spatial-RWP Model 281 21.3 Removing Speed Decay 285 21.4 The RWP Model and "Perfect Simulation" 287 References 290 22 Mobility Modeling and Opportunistic Network Performance Analysis 293 22.1 Unicast in Opportunistic Networks 293 22.1.1 Network Model 294 22.7.2 Epidemic Routing Performance 297 22.1.3 Two-Hops Routing Performance 298 22.2 Broadcast in Opportunistic Networks 299 22.2.7 Network Model 300 22.2.2 Broadcasting with Geometric-Based Mobility 302 22.2.3 Broadcasting with the Home-MEG Model 303 22.2.4 Discussion 306 References 308 Appendix A Elements of Probability Theory 309 A.l Basic Notions of Probability Theory 309 A.2 Probability Distributions 313 A.3 Markov Chains 317 References 321
xiv Contents Appendix B Elements of Graph Theory, Asymptotic Notation, and Miscellaneous Notions 323 B.l Asymptotic Notation 323 B.2 Elements of Graph Theory 326 B.3 Miscellaneous Notions 330 References 333 Index 335