VANET:Vehicular Applicationsand Inter-NetworkingTechnologies

Hannes HartensteinKarlsruhe Institute of Technology (KIT), Germany

Kenneth P LaberteauxToyota Technical Center, USA

A John Wiley and Sons, Ltd, Publication

VANET

VANET:Vehicular Applicationsand Inter-NetworkingTechnologies

Hannes HartensteinKarlsruhe Institute of Technology (KIT), Germany

Kenneth P LaberteauxToyota Technical Center, USA

A John Wiley and Sons, Ltd, Publication

This edition first published 2010© 2010 John Wiley & Sons Ltd.

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Library of Congress Cataloging-in-Publication Data

Hartenstein, Hannes.VANET: vehicular applications and inter-networking technologies / Hannes Hartenstein,

Kenneth Laberteaux, editors.p. cm.

Includes index.ISBN 978-0-470-74056-9 (cloth)

1. Vehicle ad hoc networks (Computer networks) I. Hartenstein, Hannes. II. Laberteaux,Kenneth.

TE228.37.V36 2010388.3’12–dc22 2009026531

A catalogue record for this book is available from the British Library.

ISBN 9780470740569 (H/B)

Set in 10/12pt Palatino by Sunrise Setting Ltd, Torquay, UK.Printed and Bound in Singapore by Markone, Pte.

Dedication

To my parents. HH

To Maria. KPL

Contents

Foreword xv

About the Editors xix

Preface xxi

Acknowledgments xxv

List of Contributors xxvii

1 Introduction 1Hannes Hartenstein and Kenneth P Laberteaux

1.1 Basic Principles and Challenges . . . . . . . . . . . . . . . . . . . . . . . 11.2 Past and Ongoing VANET Activities . . . . . . . . . . . . . . . . . . . . 4

1.2.1 From the beginning to the mid 1990s . . . . . . . . . . . . . . . . 51.2.2 From the mid 1990s to the present . . . . . . . . . . . . . . . . . 71.2.3 Examples of current project results . . . . . . . . . . . . . . . . . 10

1.3 Chapter Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2 Cooperative Vehicular Safety Applications 21Derek Caveney

2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.1.2 Chapter outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2.2 Enabling Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232.2.1 Communication requirements . . . . . . . . . . . . . . . . . . . 232.2.2 Vehicular positioning . . . . . . . . . . . . . . . . . . . . . . . . . 232.2.3 Vehicle sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252.2.4 On-board computation platforms . . . . . . . . . . . . . . . . . . 26

2.3 Cooperative System Architecture . . . . . . . . . . . . . . . . . . . . . . 262.4 Mapping for Safety Applications . . . . . . . . . . . . . . . . . . . . . . 28

2.4.1 Non-parametric path prediction . . . . . . . . . . . . . . . . . . 302.4.2 Parametric path prediction . . . . . . . . . . . . . . . . . . . . . 312.4.3 Stochastic path prediction . . . . . . . . . . . . . . . . . . . . . . 35

viii CONTENTS

2.5 VANET-enabled Active Safety Applications . . . . . . . . . . . . . . . . 372.5.1 Infrastructure-to-vehicle applications . . . . . . . . . . . . . . . 402.5.2 Vehicle-to-vehicle applications . . . . . . . . . . . . . . . . . . . 412.5.3 Pedestrian-to-vehicle applications . . . . . . . . . . . . . . . . . 47

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

3 Information Dissemination in VANETs 49Christian Lochert, Björn Scheuermann and Martin Mauve

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 493.2 Obtaining Local Measurements . . . . . . . . . . . . . . . . . . . . . . . 503.3 Information Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

3.3.1 Protocols for information transport . . . . . . . . . . . . . . . . . 543.3.2 Improving network connectivity . . . . . . . . . . . . . . . . . . 593.3.3 What to transport . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

3.4 Summarizing Measurements . . . . . . . . . . . . . . . . . . . . . . . . 633.5 Geographical Data Aggregation . . . . . . . . . . . . . . . . . . . . . . . 663.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

4 VANET Convenience and Efficiency Applications 81Martin Mauve and Björn Scheuermann

4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814.2 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

4.2.1 Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 824.2.2 Connectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 834.2.3 Competition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

4.3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 874.4 Communication Paradigms . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.4.1 Centralized client/server systems . . . . . . . . . . . . . . . . . 894.4.2 Infrastructure-based peer-to-peer communication . . . . . . . . 904.4.3 VANET communication . . . . . . . . . . . . . . . . . . . . . . . 92

4.5 Probabilistic, Area-based Aggregation . . . . . . . . . . . . . . . . . . . 934.5.1 FM sketches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 944.5.2 Using sketches for data aggregation in VANETs . . . . . . . . . 944.5.3 Soft-state sketches . . . . . . . . . . . . . . . . . . . . . . . . . . 964.5.4 Forming larger area aggregates . . . . . . . . . . . . . . . . . . . 964.5.5 Application study . . . . . . . . . . . . . . . . . . . . . . . . . . 97

4.6 Travel Time Aggregation . . . . . . . . . . . . . . . . . . . . . . . . . . . 994.6.1 Landmark-based aggregation . . . . . . . . . . . . . . . . . . . . 994.6.2 Judging the quality of information . . . . . . . . . . . . . . . . . 1014.6.3 Hierarchical landmark aggregation . . . . . . . . . . . . . . . . 1014.6.4 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

4.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

CONTENTS ix

5 Vehicular Mobility Modeling for VANET 107Jérôme Härri

5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1075.2 Notation Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1125.3 Random Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1135.4 Flow Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

5.4.1 Microscopic flow models . . . . . . . . . . . . . . . . . . . . . . 1165.4.2 Macroscopic flow models . . . . . . . . . . . . . . . . . . . . . . 1215.4.3 Mesoscopic flow models . . . . . . . . . . . . . . . . . . . . . . . 1235.4.4 Lane changing models . . . . . . . . . . . . . . . . . . . . . . . . 1245.4.5 Intersection management . . . . . . . . . . . . . . . . . . . . . . 1285.4.6 Impact of flow models on vehicular mobility . . . . . . . . . . . 129

5.5 Traffic Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1315.5.1 Trip planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1325.5.2 Path planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1335.5.3 Influence of time . . . . . . . . . . . . . . . . . . . . . . . . . . . 1345.5.4 Impact of traffic models on vehicular mobility . . . . . . . . . . 134

5.6 Behavioral Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1355.7 Trace or Survey-based Models . . . . . . . . . . . . . . . . . . . . . . . . 1375.8 Integration with Network Simulators . . . . . . . . . . . . . . . . . . . 139

5.8.1 Network simulators . . . . . . . . . . . . . . . . . . . . . . . . . 1395.8.2 Isolated mobility models . . . . . . . . . . . . . . . . . . . . . . . 1415.8.3 Embedded mobility models . . . . . . . . . . . . . . . . . . . . . 1415.8.4 Federated mobility models . . . . . . . . . . . . . . . . . . . . . 1435.8.5 Application-centric versus network-centric simulations . . . . . 1455.8.6 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

5.9 A Design Framework for Realistic Vehicular Mobility Models . . . . . 1475.9.1 Motion constraints . . . . . . . . . . . . . . . . . . . . . . . . . . 1475.9.2 Traffic generator . . . . . . . . . . . . . . . . . . . . . . . . . . . 1485.9.3 Application-based level of realism . . . . . . . . . . . . . . . . . 149

5.10 Discussion and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . 1505.11 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

6 Physical Layer Considerations for Vehicular Communications 157Ian Tan and Ahmad Bahai

6.1 Standards Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1586.1.1 A brief history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1586.1.2 Technical alterations and operation . . . . . . . . . . . . . . . . 159

6.2 Previous Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1656.3 Wireless Propagation Theory . . . . . . . . . . . . . . . . . . . . . . . . 166

6.3.1 Deterministic multipath models . . . . . . . . . . . . . . . . . . 1666.3.2 Statistical multipath models . . . . . . . . . . . . . . . . . . . . . 1716.3.3 Path loss modeling . . . . . . . . . . . . . . . . . . . . . . . . . . 173

x CONTENTS

6.4 Channel Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1746.4.1 Delay spread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1746.4.2 Coherence bandwidth . . . . . . . . . . . . . . . . . . . . . . . . 1756.4.3 Doppler spread . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1796.4.4 Coherence time . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1816.4.5 Impact on OFDM systems . . . . . . . . . . . . . . . . . . . . . . 182

6.5 Measurement Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1846.6 Empirical Channel Characterization at 5.9 GHz . . . . . . . . . . . . . . 188

6.6.1 Highway environments . . . . . . . . . . . . . . . . . . . . . . . 1886.6.2 Urban environments . . . . . . . . . . . . . . . . . . . . . . . . . 1936.6.3 Rural LOS environments . . . . . . . . . . . . . . . . . . . . . . . 1996.6.4 Results summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 2006.6.5 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

6.7 Future Directions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2066.8 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2076.9 Appendix: Deterministic Multipath Channel Derivations . . . . . . . . 208

6.9.1 Complex baseband channel representation – continuous time . 2086.9.2 Complex baseband channel representation – discrete time . . . 209

6.10 Appendix: LTV Channel Response . . . . . . . . . . . . . . . . . . . . . 2106.11 Appendix: Measurement Theory Details . . . . . . . . . . . . . . . . . . 212

6.11.1 PN sequence bits . . . . . . . . . . . . . . . . . . . . . . . . . . . 2126.11.2 Generation of LTI channel estimates . . . . . . . . . . . . . . . . 2126.11.3 Generation of Ricean K-factor estimates . . . . . . . . . . . . . . 214

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

7 MAC Layer and Scalability Aspects of Vehicular CommunicationNetworks 219Jens Mittag, Felix Schmidt-Eisenlohr, Moritz Killat, Marc Torrent-Moreno

and Hannes Hartenstein

7.1 Introduction: Challenges and Requirements . . . . . . . . . . . . . . . . 2197.2 A Survey on Proposed MAC Approaches for VANETs . . . . . . . . . . 221

7.2.1 Time-division multiple access based approaches . . . . . . . . . 2227.2.2 Space-division multiple access based approaches . . . . . . . . 2237.2.3 Code-division multiple access based approaches . . . . . . . . . 224

7.3 Communication Based on IEEE 802.11p . . . . . . . . . . . . . . . . . . 2257.3.1 The IEEE 802.11 standard . . . . . . . . . . . . . . . . . . . . . . 2257.3.2 IEEE 802.11p: towards wireless access in vehicular

environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2287.3.3 Modeling and simulation of IEEE 802.11p-based networks . . . 232

7.4 Performance Evaluation and Modeling . . . . . . . . . . . . . . . . . . 2377.4.1 Performance results of IEEE 802.11p-based active safety

communications . . . . . . . . . . . . . . . . . . . . . . . . . . . 2387.4.2 Computational costs of simulation . . . . . . . . . . . . . . . . . 2417.4.3 Analytical models for performance of IEEE 802.11 networks . . 241

CONTENTS xi

7.4.4 An empirical model for performance of IEEE 802.11pnetworks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

7.4.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2557.5 Aspects of Congestion Control . . . . . . . . . . . . . . . . . . . . . . . 255

7.5.1 The need for congestion control . . . . . . . . . . . . . . . . . . . 2567.5.2 Congestion control by means of transmit power control . . . . . 2587.5.3 Congestion control by means of rate control . . . . . . . . . . . 265

7.6 Open Issues and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . 267References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269

8 Efficient Application Level Message Coding and Composition 273Craig L Robinson

8.1 Introduction to the Application Environment . . . . . . . . . . . . . . . 2748.1.1 Safety applications and data requirements . . . . . . . . . . . . 2748.1.2 Desirable architectural features . . . . . . . . . . . . . . . . . . . 2768.1.3 Broadcast characteristics . . . . . . . . . . . . . . . . . . . . . . . 277

8.2 Message Dispatcher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2788.2.1 Data element dictionary . . . . . . . . . . . . . . . . . . . . . . . 2798.2.2 Message construction . . . . . . . . . . . . . . . . . . . . . . . . 2808.2.3 What and when to send . . . . . . . . . . . . . . . . . . . . . . . 280

8.3 Example Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2818.3.1 Emergency brake warning . . . . . . . . . . . . . . . . . . . . . . 2818.3.2 Intersection violation warning . . . . . . . . . . . . . . . . . . . 2818.3.3 Message composition . . . . . . . . . . . . . . . . . . . . . . . . 2848.3.4 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2858.3.5 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

8.4 Data Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2868.5 Predictive Coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

8.5.1 Linear predictive coding . . . . . . . . . . . . . . . . . . . . . . . 2888.5.2 System model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2898.5.3 Tolerable error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2898.5.4 Predictive coding transmission policies . . . . . . . . . . . . . . 2908.5.5 Predictive coding results . . . . . . . . . . . . . . . . . . . . . . . 291

8.6 Architecture Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2948.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296

9 Data Security in Vehicular Communication Networks 299André Weimerskirch, Jason J Haas, Yih-Chun Hu and Kenneth P Laberteaux

9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2999.1.1 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3019.1.2 State of the art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301

9.2 Challenges of Data Security in Vehicular Networks . . . . . . . . . . . 3029.3 Network, Applications, and Adversarial Model . . . . . . . . . . . . . . 304

9.3.1 Network model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3049.3.2 Applications model . . . . . . . . . . . . . . . . . . . . . . . . . . 3059.3.3 Attacker model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309

xii CONTENTS

9.4 Security Infrastructure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3139.4.1 Cryptography services . . . . . . . . . . . . . . . . . . . . . . . . 3139.4.2 Key management . . . . . . . . . . . . . . . . . . . . . . . . . . . 316

9.5 Cryptographic Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . 3259.5.1 Certificate verification . . . . . . . . . . . . . . . . . . . . . . . . 3259.5.2 Encryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3269.5.3 Key agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3279.5.4 Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3299.5.5 Secure positioning . . . . . . . . . . . . . . . . . . . . . . . . . . 3349.5.6 Identification of misbehaving nodes . . . . . . . . . . . . . . . . 3359.5.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

9.6 Privacy Protection Mechanisms . . . . . . . . . . . . . . . . . . . . . . . 3379.6.1 Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3409.6.2 Key assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3449.6.3 Tracking vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . 3549.6.4 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355

9.7 Implementation Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . 3569.7.1 Cryptographic schemes and key length . . . . . . . . . . . . . . 3569.7.2 Physical security . . . . . . . . . . . . . . . . . . . . . . . . . . . 3579.7.3 Organizational aspects . . . . . . . . . . . . . . . . . . . . . . . . 3599.7.4 Update of software and renewal of certificates . . . . . . . . . . 359

9.8 Outlook and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 360References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360

10 Standards and Regulations 365John B Kenney

10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36510.2 Layered Architecture for VANETs . . . . . . . . . . . . . . . . . . . . . . 366

10.2.1 General concepts and definitions . . . . . . . . . . . . . . . . . . 36610.2.2 A protocol stack for DSRC . . . . . . . . . . . . . . . . . . . . . . 367

10.3 DSRC Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36910.3.1 DSRC in the United States . . . . . . . . . . . . . . . . . . . . . . 37010.3.2 DSRC in Europe . . . . . . . . . . . . . . . . . . . . . . . . . . . 374

10.4 DSRC Physical Layer Standard . . . . . . . . . . . . . . . . . . . . . . . 37610.4.1 OFDM physical medium dependent (PMD) function . . . . . . 37710.4.2 OFDM physical layer convergence procedure (PLCP) function . 381

10.5 DSRC Data Link Layer Standard (MAC and LLC) . . . . . . . . . . . . 38310.5.1 Medium access control (MAC) sublayer . . . . . . . . . . . . . . 38310.5.2 Logical link control (MAC) sublayer . . . . . . . . . . . . . . . . 392

10.6 DSRC Middle Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39310.6.1 MAC extension for multi-channel operation: IEEE 1609.4 . . . . 39510.6.2 Network services for DSRC: network and transport layers,

IEEE 1609.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39910.6.3 WSA length summary . . . . . . . . . . . . . . . . . . . . . . . . 40710.6.4 Middle layer security: IEEE 1609.2 . . . . . . . . . . . . . . . . . 409

CONTENTS xiii

10.7 DSRC Message Sublayer . . . . . . . . . . . . . . . . . . . . . . . . . . . 41410.7.1 SAE J2735 DSRC message sets . . . . . . . . . . . . . . . . . . . 41410.7.2 Case study: The basic safety message . . . . . . . . . . . . . . . 41710.7.3 Case study: The probe vehicle data message . . . . . . . . . . . 42210.7.4 Case study: The roadside alert message . . . . . . . . . . . . . . 422

10.8 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42210.9 Abbreviations and Acronyms . . . . . . . . . . . . . . . . . . . . . . . . 425References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428

Index 431

Foreword

In August 1997 the National Automated Highway System Consortium (NAHSC)demonstrated several highway automation technologies on interstate I-15 in SanDiego. Several thousand people got rides in automated cars and buses featuringvision-based lane-keeping and car-following. The highlight of the event was afully automated (‘hands-off, feet-off, brains-off’) highway system (AHS). The goalof the AHS demonstration was a proof-of-concept of an AHS architecture thatenhanced highway capacity and safety. Capacity increase was achieved by organizingthe movement of vehicles in closely spaced platoons. The AHS demonstrationinvolved a seven-car vehicle, with vehicles spaced 22ft apart, driving at 60 mph.Taking inter-platoon separation into account, this gives an average inter-vehicledistance (bumper-to-bumper) of 60 feet. At a speed of 60 mph, this amounts to amaximum flow or capacity of 5,280 vehicles/hour, compared with a capacity of 2,000vehicles/hour in today’s highways. Each vehicle had electronic actuators – steering,braking and throttle – that were controlled by the vehicle’s own computer.

Safety was increased because the computer was connected to sensors that pro-vided (1) measurements about the vehicle itself (speed, acceleration, tire slip), (2) thevehicle’s location within the lane, (3) the relative speed and distance between thevehicle and the vehicle in front. Most importantly, an inter-vehicle communicationsystem formed a local area network to exchange information with other vehicles inthe neighborhood, as well as to permit a protocol among neighboring vehicles tosupport cooperative maneuvers such as lane-changing, joining a platoon, and suddenbraking. Computer-controlled driving eliminated driver misjudgement, which isa major cause of accidents today. At the same time, a suite of safety controllaws ensured fail-safe driving despite sensor, communication and computer faults.Although not part of its original goal, the AHS experiment also showed that itcould significantly reduce fuel consumption by greatly reducing driver-inducedacceleration and deceleration surges during congestion.

The AHS experiment met its goals, but there was no direct, practicable pathtowards its wide-scale deployment. The main obstacle is that the AHS conceptrequired all vehicles to be automated: mixing manually driven and automatedvehicles reduces the capacity increase and creates safety issues that were notaddressed in depth in the NAHSC project. However, the project inspired a series offollow-on USDOT research programs to improve mobility and safety through bettersensing, communication, and cooperative control.

xvi FOREWORD

The first follow-on program was dubbed Vehicle-Infrastructure Integration or VII,later renamed SafeTrip-21, and now called IntelliDrive. The different names signalsubtle shifts in assumptions and objectives.

A major push behind VII was the Federal Communications Commission (FCC)ruling dedicating a 75 MHz spectrum in the 5.9 GHz band for the exclusive useof automotive applications. The spectrum became known as Direct Short-RangeCommunications or DSRC. The permissible power levels give DSRC signals a rangeof 1 km with data rates of 6 to 27 Mbps. A community of researchers set aboutdeveloping DSRC standards, including the PHY and MAC layers, a communicationsarchitecture, and mobility and safety applications. The architecture envisaged ad-hoc communications among on-board units (OBUs) in vehicles and roadside units(RSU). The RSUs would function as data repositories and as repeaters. Mobilityapplications dealt with providing traveler information, where safety applicationsused DSRC to alert drivers about potentially conflicting situations based on infor-mation obtained from neighboring vehicles and the roadside.

As the DSRC community was making slow progress in standardization andapplications, the tremendous advances in consumer electronics led to a rangeof wireless-based hand-held devices (GPS-equipped cellphones and PDAs), withlocation-based services, including navigation aids and traffic information. SafeTrip-21 recognized these changes by expanding the focus from DSRC to include thesealternative channels of information. However, the expanded focus also led to adilution of effort. In its reincarnation as IntelliDrive, the focus has narrowed againto safety concerns, with DSRC as the main communication medium.

This US-centric account should not obscure parallel and coordinated develop-ments in Europe and Japan, where there are active programs based on DSRC. (Theonly difference is that Japanese DSRC is in the 5.8 GHz band.)

The international academic and industry research community meanwhile hasorganized itself under the banner of VANET–Vehicle Ad-hoc Networks, holdingannual workshops that bring together researchers from communication networks,computer science, electrical engineering, automotive engineering, and transporta-tion. The VANET workshops have served to catalyze and consolidate a large bodyof research. VANET is now a well-recognized field of research, concerned with alltechnical aspects of vehicular ad-hoc networks, from radio propagation to networkdesign, and performance to applications. The field concerns itself as well with issuesof security and privacy, data reliability and aggregation.

The editors, Hannes Hartenstein and Kenneth P Laberteaux, respectively repre-senting the academic and industry research communities, are eminent scholars in thefield. Both have served important roles in the creation of this research community:Ken Laberteaux, who coined the VANET term, was the driving force in launchingthe first VANET Workshop in 2004, and served as the general co-chair for theWorkshop’s first two years. Hannes Hartenstein was an active contributor to theEuropean Fleetnet Project (which preceded the first VANET Workshop) and servedas VANET Workshop general co-chair in 2005 and technical program co-chair in2006. In addition to this book, both editors continue to actively publish in the field.

VANET has become an exciting field of research, with a large body of knowledgeand many open problems. But for the newcomer, whether graduate student or

FOREWORD xvii

professional, the VANET literature is too vast to master in a reasonable amount oftime. The publication of this volume comes at an opportune moment. The editorshave created a volume that covers the most important contributions to VANET overthe past decade. The book will serve well both as a classroom text that can be used ina graduate course for electrical engineering and computer science, and as a referencetext for the practicing professional.

Pravin VaraiyaBerkeley

About the Editors

Hannes Hartenstein is a professor for decentralized systems and network servicesat the Karlsruhe Institute of Technology (KIT), Germany, which is formed by theUniversity of Karlsruhe and the Research Center Karlsruhe, and a director of theKIT Steinbuch Centre for Computing. Prior to joining the University of Karlsruhe,he was a senior research staff member with NEC Europe. He was NEC’s projectleader (2001–03) for the ‘FleetNet – Internet on the Road’ project partly fundedby the German Ministry of Education and Research (BMBF), and involved in the‘NOW: Network on Wheels’ project (2004–08), also funded by BMBF. He is currentlyactively participating in the EU FP7 project PRE-DRIVE-C2X. He was General Co-Chair of the ACM International Workshop on Vehicular Ad-Hoc Networks (VANET)in 2005, technical co-chair of ACM VANET in 2006, technical co-chair of the IEEESymposium on Wireless Vehicular Communications (WiVeC) 2007, and technical co-chair of the IFIP/IEEE Conference on Wireless On-Demand Network Systems andServices (WONS) in 2008. He is a member of the scientific directorate of the Centerfor Informatics, Schloss Dagstuhl. His research interests include mobile networks,virtual networks, and IT management. He holds a diploma in mathematics anda doctoral degree in computer science, both from Albert-Ludwigs-Universität,Freiburg, Germany.

Kenneth P Laberteaux is a senior principal research engineer for the ToyotaTechnical Center in Ann Arbor, MI. His research focus is information-rich vehicularsafety systems, focusing on architecture, security, and protocol design for vehicle-to-vehicle and vehicle-to-roadside wireless communication. He was a founder andtwo-year (2004–05) general co-chair of the highly selective, international VehicularAd-hoc Networks (VANET) workshop. He serves as the architect and technical leadfor communications research within a multi-year, multi-million dollar Vehicle SafetyCommunications-Applications collaboration project between the US governmentand several automotive companies. He completed his MSc (1996) and PhD (2000)degrees in electrical engineering at the University of Notre Dame, focusing onadaptive control for communications. In 1992, he received his BSE (summa cumlaude) in electrical engineering from the University of Michigan, Ann Arbor.

Preface

The field of vehicular applications and inter-networking technologies (VANET) withits radio-based direct vehicle-to-vehicle and vehicle-to-infrastructure communica-tion strives to harness the power of ubiquitous communication for the sake oftraffic safety and transport efficiency. This book addresses the applications andtechnical aspects of VANET that can be established by short- and medium-rangecommunication primarily based on wireless local area network technology. Thedistinctive set of candidate applications (e.g., collision warning and local trafficinformation for drivers), resources (e.g., licensed spectrum, rechargeable powersource), and the environment (e.g., vehicular traffic flow patterns, privacy concerns)make VANET a unique area of wireless communication.

With about ten years of intense research activity and progress in the field ofVANET, deep insights were gained into how to design VANET, and a large numberof communication methods and protocols were proposed. In this book, leadingexperts in this field survey and evaluate the state of the art in vehicular inter-networking. Since VANET are still an actively evolving field, the chapters of thisbook include latest research results and point to open and future issues. Thus, thebook is intended to serve as a consolidated reference to the current state of researchand should enable the reader to assess the potential and the future options of VANETdeployments. There are plenty of exciting research challenges yet to be solved and,furthermore, there are various deployment challenges to be addressed as innovationheavily depends on acceptance of technology.

Here is a brief synopsis of each chapter:

Chapter 1 provides an introduction to the basic principles and challenges of VANET,presents a short history of VANET activities, and outlines the contributions of thevarious chapters.

Chapter 2 discusses foreseen safety applications and indicates the correspondingrequirements of the communication system.

Chapter 3 describes methods for information dissemination and aggregation withinVANET required to support efficiency and convenience applications.

Chapter 4 builds on Chapter 3 and focuses on ‘non-safety’ applications, thus, onapplications which primarily target efficiency and convenience.

Chapter 5 contains a survey and taxonomy of vehicular mobility models. It empha-sizes the application of those models to the field of VANET.

xxii PREFACE

Chapter 6 details the physical layer aspects of the foreseen IEEE 802.11-basedcommunication system.

Chapter 7 discusses aspects of medium access control, based on IEEE 802.11 and theforeseen 802.11p standard, and provides a treatment of congestion control for thewireless medium.

Chapter 8 details the middleware aspects of VANET as a basis for efficient andsemantically understandable communication.

Chapter 9 deals with security and privacy aspects of VANET.

Chapter 10 covers the current status on standardization activities and regulation inthe field of VANET.

The book is designed i) for a survey course for college engineering studentsranging from third-year undergraduate to first-year graduate, ii) for providing avaluable tool to professional automotive technologists, and iii) as a concise primerfor researchers attracted to this field. It is assumed that the reader has a basicunderstanding of mobile networks and of IEEE 802.11-based wireless LANs. Thisbook does not cover the issue of geographical positioning nor does it deal withhardware implementation issues.

The term VANET as an acronym for vehicular ad-hoc networks was originallyadopted to reflect the ad-hoc nature of these highly dynamic networks. However,because the term ‘ad-hoc network’ was associated widely with unicast-routing-related research, we decided to redefine the acronym VANET to deemphasize ad-hocnetworking. In this book we use the term VANET for the whole field of research, butalso when referring to an instance of a vehicular inter-network.

This book has its roots in a tutorial we presented jointly at the ACM InternationalConference on Mobile Computing and Networking and at the ACM InternationalSymposium on Mobile Ad-Hoc Networking and Computing in Montreal, Quebec,Canada, in 2007. An ‘extract’ of the tutorial was published under the title ‘ATutorial Survey on Vehicular Ad-Hoc Networks’ in the June 2008 issue of the IEEECommunications Magazine.

As this book goes to press, there remain several open issues, especially in the areasof standards and regulations. We endeavor to present updates as well as errata onthis book via the following web page:

http://www.vanetbook.com

The past decade has produced significant VANET research and technology creation,but the next one or two decades will be crucial in determining whether VANETwill soon become a reality. Several automotive companies, research institutions,and government organizations are currently engaged in significant evaluation,modification, and engineering of VANET systems. Demonstrations continue to showthe basic soundness of the underlying VANET technology; although not perfected,near-term VANET technology appears to be ‘good enough’ to ‘be useful.’ Therefore,it seems likely that a ‘first generation’ of VANET will soon coalesce, most likelyaround the nearly completed IEEE 802.11p and 1609 standards. In addition, more

PREFACE xxiii

attention will be given to other topics, such as application refinement, human–machine interfaces, market acceptance/penetration rates, business cases, and ofoverall system effectiveness.

We contend that the fundamental opportunities and synergies of interconnectedvehicles and infrastructures will one day make VANET a reality. However, it isdifficult to predict whether the first widely deployed VANET will be based on near-term technology, or on the fruit of future VANET research. Over future decades,we foresee significant progress in other technologies, such as distributed control,artificial intelligence, vehicle sensors, and energy management. These advanceswill enable the next generation (and the generation after that) of safety, efficiency,and convenience applications. It seems all but certain that the future will bringa sharp increase of transportation demand while transportation resources ebb. Inlight of these challenges, timely, accurate, and trustworthy information becomesincreasingly necessary. And so our work continues, and with it, the hope thatVANET will bring a better tomorrow.

Acknowledgments

We would like to express our gratitude to the following persons:

• all co-authors, whose contributions made this book possible

• the persons who shaped our thinking about VANET. We would particularlylike to mention (in alphabetical order): Wieland Holfelder, Yih-Chun Hu, Jean-Pierre Hubaux, Daniel Jiang, John Kenney, PR Kumar, Martin Mauve, SamOyama, Paolo Santi, Raja Sengupta, Pravin Varaiya, Andre Weimerskirch

• the Wiley staff: Birgit Gruber, Tiina Ruonamaa, Anna Smart, Sarah Tilley, BrettWells

• the Decentralized Systems and Network Services research group at KarlsruheInstitute of Technology and particularly Moritz Killat who spent a significantamount of time in skillfully preparing the final LATEX manuscript

• last, but definitely not least, our families and friends.

Hannes HartensteinKenneth P Laberteaux

Karlsruhe and Ann Arbor

List of Contributors

Ahmad Bahai is a fellow and chief technologist at National Semiconductor. Heis also director of National Semiconductor Labs (NS Labs). Bahai is a consultingprofessor at Stanford University and an adjunct professor and member of theUniversity of California at Berkeley’s Electrical Engineering and Computer ScienceIndustrial Advisory Board. Prior to joining National, he was chief technologyofficer at Algorex and a technical manager at AT&T Bell Labs Advanced WirelessCommunications Labs. Bahai co-invented a multi-carrier spread spectrum theorywhich is being used in most modern wireless systems and standards. He is theauthor of a textbook on OFDM, ‘Multi-carrier Digital Communications’ and servedas the associate editor of IEEE Communication Letters for five years. Bahai hasauthored more than 60 papers in journals/conferences and holds several patents inwireless, analog, and mixed-signal processing systems. Bahai received his master’sdegree in electrical engineering from Imperial College, University of London in 1988and a PhD in electrical engineering from the University of California at Berkeley in1993.

Derek Caveney is a principal research scientist with the Toyota Technical Center,Toyota Motor Engineering & Manufacturing North America, in Ann Arbor, MI.He received the BScE degree in applied mathematics from Queen’s University,Kingston, ON, Canada, in 1999 and the MSc and PhD degrees in mechanical engi-neering from the University of California, Berkeley, in 2001 and 2004, respectively.From 2004 until 2005, he was a visiting postdoctoral scholar with the Center forCollaborative Control of Unmanned Vehicles. His interests include cooperativecontrol of vehicles for safety and mobility.

Jérôme Härri received a MSc degree and a Dr. ès sc. degree in telecommunicationfrom the Swiss Institute of Technology (EPFL), Lausanne, Switzerland. He is anassistant professor at the Institute of Telematics at Universität Karlsruhe (TH),Germany. Previously, he was a research assistant and PhD student at EURECOMin Sophia-Antipolis, France, working on mobility modeling and management formobile wireless ad-hoc networks. His research interests include inter-vehicularcommunication, vehicular mobility modeling, and intelligent transportation sys-tems. He is currently involved in the activities of the CAR 2 CAR CommunicationConsortium.

Jason Haas is currently a PhD candidate at the University of Illinois at Urbana-Champaign, studying under Yih-Chun Hu. He received his BSc degree from the

xxviii LIST OF CONTRIBUTORS

University of Wisconsin-Madison in 2003 in electrical and computer engineeringand in physics. He received his MSc degree from the University of Illinois atUrbana-Champaign in 2007 in electrical and computer engineering. His researchinterests include network security, vehicular networking, physical security, andcyber-physical systems.

Yih-Chun Hu is an assistant professor of electrical and computer engineering at theUniversity of Illinois at Urbana-Champaign. He got his PhD from Carnegie MellonUniversity in 2003 as a student of David B Johnson and was a postdoctoral researcherat the University of California, Berkeley under Doug Tygar. His research interestsare in network security and wireless networks, and he has served as the technicalprogram co-chair of ACM’s VANET conference in 2007 and 2008.

John B Kenney is a communications consultant who specializes in data networks.He recently represented Toyota in the Vehicle Safety Communications consortiumwhere he led the communications research group. He is an active contributor tostandards efforts in the IEEE 802.11 Working Group, IEEE 1609 Working Group,and SAE DSRC Technical Committee. Prior to his work with Toyota he led anetworking research group at the Tellabs Research Center. There he worked onrouter architectures and protocols to support quality of service in high performanceIP and ATM networks. He is also an adjunct professor of electrical engineering atthe University of Notre Dame. He holds a PhD in electrical engineering from theUniversity of Notre Dame and an MSEE from Stanford University.

Moritz Killat studied computer science at the University of Passau and the Uni-versity of Karlsruhe (TH), Germany. Since 2005 he has been with the Institute ofTelematics, University of Karlsruhe (TH), and received a PhD in computer sciencein 2009. His research interests address the analysis and development of combinedapplication and communication simulation for car-to-x communication.

Christian Lochert is an IT consultant working with PSI Transcom GmbH inDüsseldorf, Germany. He received his diploma degree in information systems in2003 from the University of Mannheim, Germany and in 2008 his PhD degree fromthe Heinrich Heine University, Düsseldorf, Germany. His current research interestsinclude vehicular ad-hoc networks, congestion control in mobile ad-hoc networksand real-time communication in cellular networks.

Martin Mauve received the MS and PhD degrees in computer science from theUniversity of Mannheim, Germany, in 1997 and 2000 respectively. From 2000 to 2003,he was an assistant professor at the University of Mannheim. In 2003, he joined theHeinrich Heine University, Düsseldorf, Germany, as a full professor and head of theresearch group for computer networks and communication systems. His researchinterests include distributed multimedia systems, mobile ad-hoc networks and inter-vehicle communication.

Jens Mittag holds a diploma in computer science from the University of Karlsruhe,Germany, and is currently pursuing his PhD within the Decentralized Systems andNetwork Services Research Group at the Karlsruhe Institute of Technology (KIT),Germany. His research interests include mobile networks, simulation environments