An Efficient Time Slot Acquisition on the Hybrid TDMA/CSMA Multichannel MAC in VANETs

The multichannel MACs increase the throughput and reduce the collision probability compared to the single-channel MACs. However, coordination of multiple nodes across multichannels is nontrivial. Recently, a multichannel MAC, called HER-MAC, uses both TDMA and CSMA schemes to improve reliability in broadcasting safety messages and efficiency in service channel utilization. Nevertheless, HER-MAC suffers a high collision probability for a large number of vehicle nodes. In this letter, we propose a hybrid TDMA/CSMA multichannel MAC protocol for VANETs that allows efficient broadcasting of messages and increases throughput on the control channel. Furthermore, our proposed MAC eliminates unnecessary control packet such as HELLO and SWITCH packets in HER-MAC. Analysis and simulation results show that the proposed MAC can provide faster time slot acquisition on the control channel than HER-MAC.