Improving Time Slot Acquisition Through RSU's Coordination for TDMA-based MAC Protocol in VANETs

Vehicles and Road Side Units (RSUs) are essential units to create a dynamic network, called Vehicular Ad hoc NETwork (VANETs). An RSU plays a role of collecting and analyzing traffic data given from vehicles. RSUs and vehicles have to assign time slots to broadcast service applications on the control channel in VANETs. One of MAC protocol versions named VeMAC is proposed. VeMAC protocol can decrease the rate of transmission collisions and increase the throughput on the control channel. However, VeNTAC protocol did not consider to special properties of an RSU in VANETs. In this paper, we propose an improvement of time slot acquisition through RSU's coordination for TDMA-based N1AC protocol in VANET, called RCMAC protocol. In our protocol, RSUs exploit time slots assignment and disseminate control information. Hence, RCMAC protocol reduces the rate transmission collisions due to all nodes on the control channel receive a control information from an RSU. Simulation results show that RCMAC protocol outperforms both VeMAC and ADHOC-MAC protocols in term of average of number of frames that all nodes successfully acquire a time slot and average number of access collisions until all nodes successfully acquire a time slot.