A Dedicated Multi-channel MAC Protocol Design for VANET with

Adaptive Broadcasting

Ning Lu1, Yusheng Ji2, Fuqiang Liu1, and Xinhong Wang1

1Dept. of Electronics and Information Engineering, Tongji University, Shanghai, China

2National Institute of Informatics, Tokyo, Japan

IEEE WCNC 2010

Outline

Introduction The DMMAC protocol Performance evaluation Conclusion

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

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

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

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

The DMMAC protocol

Frame architecture of DMMAC

BCH(Basic Channel)

The DMMAC protocol

CCH Interval SCH Interval

Sync Interval

ABF CRP

ABFL (ABF Length)

ABFLmin , ABFLmax

TDMA CSMA/CABCH Basic Channel

The DMMAC protocol

ABF CRP

CCH Interval

The DMMAC protocol

1. BCH Reservation process

2. Computation of ABFL

3. Virtual Slot operation

The DMMAC protocol

BCH Reservation process

ABF CRP

CCH Interval

Each slot can only reused by one neighbor

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

The DMMAC protocol

BCH Reservation process

The DMMAC protocol

BCH Reservation process

Rule 3: to reserve empty slot

Busy Status(BS)

TransmittingVehicle Identifier(ID)

Slot information

The DMMAC protocol

Computation of ABFL

ABF CRP

CCH Interval

ABFLi = max[ALk]+SFLAL (Active slot)

The DMMAC protocol

Computation of ABFL Rule 4 : ABFLi=ABFL max

The DMMAC protocol

Virtual Slot operation

ABF CRP

CCH Interval

Contend to CRP-REQ or CRP-BRD

The DMMAC protocol

Virtual Slot operationRule 5 : if vehicle i want to send CRP.Wait for the ended of ABFs of one-hop

Mute slot

The DMMAC protocol

Virtual Slot operation

Rule 6

The DMMAC protocol

Virtual Slot operation Rule 7 : vehicle i can send the CRP-REQ to vehicle j(one-hop)

Performance evaluation

Simulator ： NS-2 Parameters

Performance evaluation

Sparse scenario

Performance evaluation

Dense scenario

Performance evaluation

Results of BCH reservation in sparse scenario

Performance evaluation

Results of BCH reservation in dense scenario

Performance evaluation

Delivery ratio of safety packets

Conclusion

This paper presented a dedicated multi-channel MAC(DMMAC) protocol for VANET collision-free and delay-bounded transmission for

safety applications