An intelligent scheme for slot reservation in vehicular ad hoc networks

Vehicular ad hoc network is a solution for increasing road traffic demand. Non-safety messages are sent during the service channel interval. The slots during which the messages are sent are not decided prior to the transmission. If the reservation of slots is done during the control channel interval, then the non-safety messages can be transmitted without any collision and thus the network performance can be improved. Further, to improve the network performance, the safety packets can be scheduled in the queue according to the time remaining for which sender and receiver are in the range of each other. This work proposes and evaluates the performance of safety message scheduling and infotainment message reservation through a MAC protocol SSIR-MAC to ensure network stability by transmitting beacons without any collision. The safety messages are queued according to their deadline and the slots for the transmission of non-safety packets are reserved during the control channel itself. Further, a hybrid queue is proposed to decrease the delay of enqueue and dequeue operations. Evaluation through extensive simulation results demonstrates the strength of SSIR-MAC. Comparisons are made with IEEE 802.11p standard and with two existing protocols which are relevant to the proposed work.