A multi-priority supported medium access control in Vehicular Ad Hoc Networks

In recent years, Vehicular Ad Hoc Networks (VANETs) experience growing interest in both academia and industry. VANETs apply multiple channels, namely Control Channel (CCH) and Service Channels (SCHs), to provide road safety services and improve the comfort and efficiency of driving. Based on the time slotted p-persistent channel access mechanism, this paper proposes a multiple priority supported medium access control (MAC) protocol for VANETs, which differentiates the packets into multi-priority on the CCH. A Markov analytical model is presented to optimize the packet transmission probabilities with different priorities and the adjustable intervals of the CCH and SCH. Moreover, a contention-free ACK scheme is reported to guarantee the reliable broadcast of the safety packets and avoid collision caused by numerous ACK packets on CCH. Simulation results indicate that the proposed MAC protocol is able to ensure the prioritized transmission of the safety packets, and it can achieve optimal system performance in terms of saturated throughput.