1. A Dedicated Multi-channel MAC Protocol Design for VANET with Adaptive Broadcasting Ning Lu 1, Yusheng Ji 2, Fuqiang Liu 1, and Xinhong Wang 1 1 Dept. of Electronics and Information Engineering, Tongji University, Shanghai, China 2 National Institute of Informatics, Tokyo, Japan IEEE WCNC 2010

2. Outline  Introduction  The DMMAC protocol  Performance evaluation  Conclusion

3. Introduction  Many advanced wireless technologies are being applied to transport systems Safe Intelligent Efficient  In particular, the Vehicular ad hoc network (VANET) Vehicle to Vehicle (V2V) communication Vehicle to infrastructure (V2I) communication

4. Introduction  The MAC protocol for VANET is critical to provide efficient and reliable medium access, but Fast topology change High node mobility Different Quality of Service(QoS) requirements

5. Introduction _goals  Authors propose a dedicated multi-channel MAC protocol, called DMMAC, for VANET Adaptability broadcasting provides collision-free and delay-bounded transmissions for safety messages Higher communication throughput Lower network latency

6. The DMMAC protocol_ Background  IEEE 1609.4 provide an important multi-channel MAC CCH(control channel) interval  Safety messages and control packets SCH(service channel) interval  Exchange data

7. The DMMAC protocol  Frame architecture of DMMAC BCH(Basic Channel)

8. The DMMAC protocol CCH Interval SCH Interval Sync Interval ABF CRP ABFL (ABF Length) ABFL min, ABFL max TDMACSMA/CA BCH Basic Channel

9. The DMMAC protocol ABF CRP CCH Interval

10. The DMMAC protocol 1. BCH Reservation process 2. Computation of ABFL 3. Virtual Slot operation

11. The DMMAC protocol  BCH Reservation process ABF CRP CCH Interval Each slot can only reused by one neighbor

12. The DMMAC protocol  BCH Reservation process FI (Frame Information) Free or Busy The slot occupation within One-hop and 2-hop Rule 1: if a packet has been successfully received or transmitting Rule 2 : to reserve a BCH not used within two hop

13. The DMMAC protocol  BCH Reservation process

14. The DMMAC protocol  BCH Reservation process Rule 3: to reserve empty slot Busy Status (BS) Transmitting Vehicle Identifier (ID) Slot information

15. The DMMAC protocol  Computation of ABFL ABF CRP CCH Interval ABFL i = max[AL k ]+SFL AL (Active slot)

16. The DMMAC protocol  Computation of ABFL Rule 4 : ABFL i =ABFL max

17. The DMMAC protocol  Virtual Slot operation ABF CRP CCH Interval Contend to CRP-REQ or CRP-BRD

18. The DMMAC protocol  Virtual Slot operation Rule 5 : if vehicle i want to send CRP. Wait for the ended of ABFs of one-hop Mute slot

19. The DMMAC protocol  Virtual Slot operation Rule 6

20. The DMMAC protocol  Virtual Slot operation Rule 7 : vehicle i can send the CRP-REQ to vehicle j(one-hop)

21. Performance evaluation  Simulator ： NS-2  Parameters

22. Performance evaluation  Sparse scenario

23. Performance evaluation  Dense scenario

24. Performance evaluation  Results of BCH reservation in sparse scenario

25. Performance evaluation  Results of BCH reservation in dense scenario

26. Performance evaluation  Delivery ratio of safety packets

27. Conclusion  This paper presented a dedicated multi-channel MAC(DMMAC) protocol for VANET collision-free and delay-bounded transmission for safety applications