1. Black-Burst-Based Multihop Broadcast Protocols for Vehicular Networks Gökhan Korkmaz, Eylem Ekici, and Füsun Özgüner Member, IEEE IEEE TVT 2007

2. Outline Introduction 1 Directional Broadcast 2 Intersection Broadcast 3 4 Performance Evaluation 5 Conclusion 4

3. Introduction  In Intervehicular Communication (IVC) systems, broadcast is a frequently used method. Possible applications relying on broadcast include  sharing emergency  traffic  weather  road data among vehicles  delivering advertisements  announcements

4. Introduction  These applications generate packets of various lengths at different rates.  accident warnings are short packets that are generated infrequently  warning packets reporting slippery road conditions are generally short  advertisement packets can be broadcast in very long packets that carry pictures, directions, or even short videos

5. Related Work Source Destination A B C D

6. Goal  Design a special MAC layer for  efficient and reliable multihop message dissemination in VANETs  address the broadcast storm, hidden node, and reliability problems of multihop broadcast in vehicular networks.

7. Directional Broadcast Request to Broadcast (RTB) Packet Intended Broadcast Direction Source A B C Black-burst signal

8. Directional Broadcast Request to Broadcast (RTB) Packet Intended Broadcast Direction Source A B C Black-burst signal

9. 1 Duration of the Black-burst L 1 ： black-burst duration in the first iteration d ： the distance between the source and the vehicle R ： the transmission range N max ： number of segments created SlotTime ： length of one slot 02

10. Duration of the Black-burst Source 10

11. Duration of the Black-burst Source

12. Duration of the Black-burst Source

13. Intersection Broadcast  Urban Multihop Broadcast (UMB) Obstacle Vehicle Infrastructure

14. Intersection Broadcast  Ad hoc Multihop Broadcast (AMB) Vehicle B A C D E F Hunter Vehicle

15. Performance Evaluation  Success Probability Comparison

16. Performance Evaluation  Successful Packet Delivery Percentage

17. Performance Evaluation  Packet Dissemination Speed

18. Conclusion  Two position-based multihop broadcast protocols for IVC networks have been proposed  The UMB protocol employs repeaters installed at the intersections.  AMB is an extension of the UMB protocol with a fully ad hoc intersection broadcast mechanism.  Design a special MAC layer for  efficient and reliable multihop message dissemination in VANETs  address the broadcast storm, hidden node, and reliability problems of multihop broadcast in vehicular networks.