In this paper we present a multi-round contention based medium access control (MAC) protocol VMR-MAC to overcome the slot-wastage problem in vehicular ad hoc networks (VANETs). Vehicular nodes in a two-hop set (THS) could acquire more than one time slot in a frame interval and the whole slot resource is almost uniformly allocated to the users through the round-by-round contention. Moreover, at the end of a super frame each vehicular node releases its time slots to avoid slot collision. The round-based time slot acquisition process and the delay performance of VMR-MAC are analyzed. Numerical and simulation results show that VMR-MAC can significantly improve the broadcast delay performance, as compared to VeMAC, a single-round MAC protocol for VANETs.
['Yiwei Mao', 'Lianfeng Shen']
VMR-MAC: A multi-round contention based MAC protocol for vehicular networks