Vehicular-2-X Communication (eBook)

Radu Popescu-Zeletin is Professor at the Technical University Berlin, and, since its foundation, has been director of the Fraunhofer Institute for Open Communication Systems, FOKUS, (formerly a GMD Institute).For many years he was head of the Research and Development Department of the BERKOM project at Deutsche Telekom. He has published numerous articles on distributed computer systems and applications. He is an active member of numerous standardization committees and is a leading player in the development of telecommunication standards. As holder of the Chair of Open Communication Systems, he also plays a major role in the development of the vision of I-centric Communications. Prof. Popescu-Zeletin has been appointed chairman of the Scientific Advisory Council of DeTeCon International. As a member of the Motorola Visionary Board, he is one of 30 leading international experts helping to shape the future in the field of mobile communications. He has also been invited by the University of Technology, Tokyo to assume a full professorship; appointment formalities are now underway (early 2004).Prof. Popescu-Zeletin graduated at the Polytechnic Institute in Bucharest, Romania, gained his Ph.D. at the University of Bremen, and habilitated at the Technical University of Berlin. Prof. Popescu-Zeletin is Senior Member of the IEEE, Doctor honoris causa at the Polytechnic Institute in Bucharest, and Professor honoris causa at the Catholic University of Campinas, Brasil. Furthermore he is member of the Motorola Visionary Board 2004/2005 as well as member of the Rumanian Academy. Prof. Popescu-Zeletin is bearer of the Public Service Medal of the Republic of Romania Ilja Radusch received his M.Sc. in Computer Science from the University of Technology Berlin (TUB). Since 2003 he is researcher with the Open Communication Systems (OKS) as well as with Fraunhofer FOKUS since 2005. Since 2006 he is group leader at the Daimler Center for Automotive Information Technology Innovations (DCAITI). He is working in the field of Car-2-Car Communication, Sensor and Ad-hoc Networks, and Context-aware Services. His responsibility includes several projects for industry partners such as Deutsche Telekom and DaimlerChrysler as well as research projects for the German Ministry of Education and Research and the European Union. Furthermore, he is giving various lecture courses at the TU Berlin Mihai Adrian Rigani received his degree in Electrotechnics in 2005 at Polytechnic University of Bucharest. Since then he is research scientist with the Daimler Center for Automotive Information Technology Innovations (DCAITI) at the Open Communication Systems (OKS) department of the Technische Universität Berlin (TUB).

Contents 5
1 Introduction 7
1.1 Overview 8
1.2 Why Vehicular Communication? 8
1.3 Architecture Layers 9
References 10
2 Applications of Vehicular Communication 11
2.1 Safety 11
2.1.1 Critical Traffic Situations 15
2.1.1.1 Cars Passing at Close Distance (Head-on) 16
2.1.1.2 Head-on Vehicle Collision 16
2.1.1.3 Rear-End Vehicle Collision 17
2.1.1.4 Side Collisions at Intersections 18
2.1.2 Classification of Safety Applications 23
2.1.3 Normal Transmission Scheme 26
2.1.3.1 Cooperative Adaptive Cruise Control 26
2.1.3.2 Cooperative Glare Reduction 27
2.1.3.3 Cooperative Merging Assistance 27
2.1.4 Bidirectional Transmission Scheme 28
2.1.4.1 Pre-crash Sensing 28
2.1.5 Non-autonomous Systems 29
2.1.5.1 Cooperative Forward Collision Warning 30
2.1.5.2 Lane Change Assistance 30
2.1.5.3 Wrong Way Driving Warning 31
2.1.6 Quick Warning Alerts 31
2.1.6.1 Cooperative Intersection Collision Warning 33
2.1.6.2 Emergency Electronic Brake Lights 33
2.1.6.3 Approaching Emergency Vehicle Warning 34
2.1.6.4 Rail Collision Warning 34
2.1.6.5 Slow Vehicle Warning 35
2.1.6.6 Post-crash Warning 35
2.1.6.7 Traffic Jam Ahead Warning 35
2.1.6.8 Hazardous Location Notification 35
2.1.6.9 Working Area Warning 36
2.1.6.10 Limited Access Warning 36
2.2 Resource Efficiency 36
2.2.1 Autonomous Systems 37
2.2.2 Normal Traffic Alerts 37
2.2.2.1 Green Light Wave 38
2.2.2.2 Enhanced Route Guidance and Navigation 38
2.3 Infotainment 39
2.3.1 Ad Hoc Services 40
2.3.1.1 Point of Interest (PoI) Notification 40
2.3.1.2 Drive-Through Toll/Park Payment 40
2.3.1.3 Remote Diagnostics 40
2.3.2 Provider Services 41
2.3.2.1 Internet Access 41
2.3.2.2 Repair Notification 41
2.3.2.3 Fleet Management 41
2.4 Summary of Application Requirements 41
References 44
3 Communication Regimes 45
3.1 Bidirectional Communication Regime 46
3.2 Position Based Communication Regime 48
3.3 Multi-Hop Position Based Communication Regime 50
References 51
4 Information in the Vehicular Network 52
4.1 Accuracy of Information 53
4.2 Time Critical Information 53
4.3 Time and Distance for Braking 54
4.4 Time and Distance for Overtaking 61
4.5 Time Zones for Proactive Applications 63
4.5.1 Data Requirements 63
4.5.2 Network Requirements 65
4.5.3 The Cooperative Collision Avoidance System 66
References 70
5 Routing 72
5.1 Multi-hop Routing Protocols 74
5.1.1 Ad Hoc on Demand Distance Vector (AODV) 74
5.1.2 Grid Location Service (GLS) 76
5.1.3 Greedy Perimeter Stateless Routing (GPSR) 79
5.1.4 Geographic Source Routing (GSR) 80
5.1.5 Contention-Based Forwarding (CBF) 81
5.1.6 Octopus 85
5.1.7 Advanced Greedy Forwarding (AGF) 86
5.1.8 Preferred Group Broadcasting (PGB) 86
5.2 Secure Multi-hop Routing 89
5.2.1 Authenticated Routing for Ad Hoc Networks (ARAN) 89
5.2.2 Secure Ad Hoc on Demand Vector (SAODV) 90
5.2.3 Secure Link State Routing Protocol (SLSP) 91
5.2.4 Secure Position Aided Ad Hoc Routing (SPAAR) 91
References 92
6 Medium Access for Vehicular Communications 94
References 101
7 Physical Layer Technologies 103
References 106
8 Security 107
References 110
Index 111

"Chapter 5 Routing (p. 67-68)

Routing refers to move a data packet from source to destination and if required the assignment of a path to the destination. In multi-hop regime routing means to forward packets that contain information through other vehicles [1]. This information refers to alerts about events that already happened, like local danger warnings and traffic flow information. If no vehicle is within the communication range a packet is stored and forwarded as soon as a new vehicle comes into reach. In multi-hop regime the information may be disseminated in two ways: to all surrounding nodes (multicast) or to the ones in a specific area (geocast). Nodes, by exchanging information about network links, compute the best path by which to route messages to other nodes.

Routing in highly mobile ad-hoc networks has to preserve the integrity of message information disseminated in the network while minimizing the number of propagations of each message. Different factors influence the message integrity, e.g. routing algorithm, environmental conditions (physical layer), but also intruder attacks (security). Several algorithms are presented below, and in order to compare them we introduce three vital parameters: PDR, latency and overhead. The PDR (Packet Delivery Ratio) [2, 3] represents the successfully received packets per sent packets. In theory, if no loss of messages occurs, this value should be 1.

In real tests this value is below 1 because in ad-hoc networks one big weakness is that route between a source and a destination is likely to have errors or even break during communication. It was demonstrated in [4] that the data packet loss rate can be decreased significantly by using relative local positions between nodes to discover routes and to make the routing decision for the ad-hoc network. The latency or end-to-end delay [5] represents the time delay from the source sending a packet to the destination receiving it. RTT (Round Trip Time) represents the latency plus time delay from destination back to source, also known as “ping”.

The routing overhead, which represents ratio of control data per payload data should be as low as possible to prevent excessive load of the network. The overhead can be reduced using location-based routing algorithms that may obtain absolute position from a positioning system such as Global Positioning System (GPS) or relative local position between nodes. Other important parameter in routing algorithms is the fault tolerance [6] that requires detection of and recovery from faults.

The above parameters can be unified under the so-called scalability effect. This effect [7–9] ensures adaptability and represents QoS (Quality of Service) impact (PDR, latency, overhead, fault tolerance, etc.) with the growth of network size. A scalable algorithm maintains its QoS parameters with the increase of the network. Routing with multi-hop position based regime is illustrated in Fig. 5.1. Different transmission strategies are possible: Either broadcast the message to all surrounding vehicles until the geocast region is reached, or create a path from source to the geocast region. Each transmission has its advantages and disadvantages. If a path is created, than less network load is required, but if the link is broken, information misses its target. If the flooding approach is used, then multiple paths exists. So, fault tolerance is provided, but also an increase of network load."