1 Vehicular Networks Slides are integrated from researchers at EPFL

2 Outline  Why vehicular networks  Technical challenges  Conclusion

3 Outline  Why vehicular networks  Technicals  Applicaitions  Wireless Urban Grid  Technical challenges  Conclusion

4 Vehicular communications: why?  Combat the awful side-effects of road traffic  Fatal losses yearly on the roads; and injured (huge numbers)  Traffic jams generate a tremendous waste of time and of fuel  Most of these problems can be solved by providing appropriate information to the driver or to the vehicle

5 A modern vehicle is a computer on wheels Processing power: comparable with a Personal Computer + a few dozens of specialized processors Communication: typically over a dedicated channel: Dedicated Short Range Communications (DSRC) In the US, 75 MHz at 5.9 GHz; In Europe, 20 MHz requested but not yet allocated) Protocol: IEEE p Penetration will be progressive (over 2 decades or so) (GPS) - Human-Machine Interface - Navigation system

6 Example of service: electronic brake warning Similar services: Road condition warning Emergency vehicle approaching

7 Other example of service: traffic information

8 Liability-related messages The information carried by these messages is susceptible to be stored in the Event Data Recorder of each vehicle

9 Another application : SmartPark Turn right! 50m to go… Park! Turn left! 30m to go…

10 Other examples of services based on vehicular networks (these ones usually involve road side infrastructure)  Vehicle to road  Electronic toll collection  Vehicles as probes to collect traffic data  Ramp metering to reduce congestion  Road to vehicle  Signal violation warning  Intersection collision warning  Data downloads

11 Message categories and properties Property Category Legitimacy Privacy protection Against other individuals Against the police Traffic information Anonymous safety-related messages Liability-related messages Guaranteed toR, DS, R, D S: Source R: Relay D: Destination Real- time cons- traints

12 Outline  Why vehicular networks  Technicals  Applicaitions  Wireless Urban Grid (another file)  Technical challenges  Conclusion

13 Outline  Why vehicular networks  Technical challenges  Service penetration and connectivity  Research opportunities in the vehicular networks  Conclusion

14 Vehicular communications: a compelling (and tough) research challenge  High speed of the nodes (relative speed up to 500 km/h)  Real time constraints (milliseconds)  Sporadic connectivity (a few seconds or less)  Crucial role of the geographic position of the nodes  Very gradual penetration  Last but not least, a very specific security research question

15 Penetration and connectivity First level approximation:

16 Number of hops Vs penetration (1/2)

17 Hopping on vehicles in the reverse direction

18 Number of hops Vs penetration (2/2)

19 compute connectivity in this case

20 Performance evaluation  Two scenarios drawn from DSRC  ns-2 simulations; single-hop transmission  Effect of message size (including the security overhead) on delay and number of received packets (Not to scale) Rough estimate of incoming traffic: 120 veh * 3.33 msg/(veh*s) * 800 Bytes/msg = approx. 3 Mb/s Rough estimate of incoming traffic: 36 veh * 10 msg/(veh*s) * 800 Bytes/msg = approx. 3 Mb/s

21 Delay Vs message size NTRU No security ECDSA RSA

22 Received packets Vs message size NTRU No security ECDSA RSA

23 Factors in performance evaluation of vehicular networks Performance evaluation Nature of data traffic (e.g., single hop, geocast) Available spectrum (e.g., 75 MHz or 20MHz around 5.9 GHz) Radio propagation model in vehicular environment Kind of antenna (directional or not) Number of radios Penetration rate (e.g., parameter from 5% to 100%) Considered crypto algorithm Vehicle mobility models Road topology Amount of roadside infrastructure (e.g., none) Connectivity Goodput Delay Delay jitter Fairness Examples of design questions: -Is CSMA/CA really the best solution? - To what extent can geographic position be taken into account for routing? Power control

24 Conclusion  The performance of vehicular communications is a difficult and highly relevant problem  Car manufacturers seem to be poised to massively invest in this area  Slow penetration makes connectivity more difficult  Security leads to a substantial overhead and must be taken into account from the beginning of the design process  The field offers plenty of novel research challenges  M. Raya and J.-P. Hubaux, “The Security of Vehicular Ad Hoc Networks”, Workshop on Secure Ad Hoc and Sensor Networks (SASN) 2005

25 Events and resources  Conferences and journals  VANET, colocated with Mobicom  V2V-Com, co-located with Mobiquitous  WIT: Workshop on Intelligent Transportation  VTC: Vehicular Technology Conference  IV: Conference on Intelligent Vehicles  IEEE Transactions on Intelligent Transportation Systems  IEEE Transactions on Vehicular Technology