Triggered CCHI Multichannel MAC protocol for Vehicular Ad Hoc Networks

This paper proposes a Triggered CCHI Multichannel MAC protocol for efficient safety message dissemination in Vehicular Ad Hoc Networks. The proposed protocol allows a vehicle to start control channel interval (CCHI) by terminating service channel interval (SCHI) whenever a safety message arrives during SCHI. It enhances the performance of VANET by reducing resource wastage and unwanted delay caused by fixed interval of CCHI and SCHI. Further, CCHI keeps on increasing until all safety messages are not transmitted. A virtual TDMA beaconing process is also proposed in this paper to ensure delivery of periodic status messages. Multichannel hidden terminal problem is also addressed using cluster member request and cluster head request. An analytical model is developed to evaluate the proposed protocol with respect to packet delivery ratio, throughput, safety message delay and packet loss ratio. Extensive simulation is carried out to validate the analytical model and to demonstrate the improvement in comparison to existing similar MAC protocols and IEEE802.11p.