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A Cross Layered MAC and Clustering Scheme for Efficient Broadcast in VANETs

A Cross Layered MAC and Clustering Scheme for Efficient Broadcast in VANETs. Luciano Bononi, Marco Di Felice Department of Computer Science, University of Bologna. IEEE MASS 2007. Outline. Introduction System Model and Assumptions Cross-layered Protocol Scheme

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A Cross Layered MAC and Clustering Scheme for Efficient Broadcast in VANETs

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  1. A Cross Layered MAC and Clustering Scheme for Efficient Broadcast inVANETs Luciano Bononi, Marco Di Felice Department of Computer Science, University of Bologna IEEE MASS 2007

  2. Outline • Introduction • System Model and Assumptions • Cross-layered Protocol Scheme • Backbone Creation and Maintenance • MAC Layer Support • Performance evaluation • Conclusion

  3. Introduction

  4. Introduction • RVC (Road-vehicle Communication)

  5. Introduction • IVC (Inter-vehicle Communication)

  6. C B Introduction • Road-network coverage by wireless communication infrastructures is costly. • Road-safety applications based on IVC strictly rely on the assumption of • Cooperation among vehicles • Distributed coordination among vehicles A

  7. Introduction - Goal • Design an algorithm for efficient broadcast of alert messages in VANETs. • Overhead reduction • Reliability

  8. System Model and Assumptions • In a multi-lane highway scenario • Vehicles travelling in both directions • Vehicles to be equipped with • Sensing capability • Wireless communication • Computation capability • Storage capability • GPS

  9. Backbone Backbone Member (BM) State Normal Vehicle (NV) State

  10. Backbone

  11. Backbone • Each chain member has at most two neighbors A B C Message Message prev_hop next_hop Direction

  12. Backbone Creation Process A B Direction D C BEACON message： <ID, (x,y), R, speed, dir, horizon>

  13. B A Residual Time (RT) • Assume Vehicle A is following Vehicle B • R：the transmission range of the sender vehicle • Δv = vB - vAis the relative speed between nodes B and A • dist(A,B)：the current estimated distance , if Δv > 0 , otherwise

  14. B A Residual Time (RT) = 1 R Direction dist(A, B)

  15. B A Residual Time (RT) = -1 Direction dist(A, B)

  16. Backbone Creation Process Vehicle ID：B Backbone State：NV Time Residual：2 sec A B Direction D C Vehicle ID：C Backbone State：NV Time Residual：5 sec Vehicle ID：D Backbone State：NV Time Residual：4 sec

  17. B A Fit Factor (FF) Backbone Refresh Interval Direction dist(A, B)

  18. Backbone Creation Process A B Direction D C Vehicle ID：D Backbone State：NV Time Residual：4 sec Fit：0.4 Vehicle ID：C Backbone State：NV Time Residual：5 sec Fit：0.9 Vehicle C sends a CANDIDATURE message to Vehicle A Vehicle A sends an ACK_WINNER message to Vehicle C

  19. A Backbone Creation Process Direction B VehicleA replies immediatelywith aCANDIDATURE message to VehicleB Vehicle B sends an ACK_WINNER message to Vehicle A Vehicle A receives a BEACON message from Vehicle B

  20. Fast Multi-Hop Forwarding (FMF) ACK ACK Direction

  21. Basic MAC Scheme A ACK B Direction

  22. Performance evaluation Simulation Parameters

  23. Average Number of Retransmissions

  24. Average Percentage of Collisions

  25. MAC End-to-end Delay, 600 Vehicles

  26. MAC Delay Percentiles, 200 Vehicles

  27. MAC Delay Percentiles, 600 Vehicles

  28. Conclusion • The performance of the DBA-MAC has been compared with other schemes, by showing general advantages in • Performance • Reliability • overhead reduction.

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