Mobility Based Routing Protocol with MAC Collision Improvement in Vehicular Ad Hoc Networks

Intelligent transportation system attracts a great deal of research attention because it helps enhance traffic safety, improve driving experiences, and transportation efficiency. Vehicular Ad Hoc Network (VANET) supports wireless connections among vehicles and offers information exchange, thus significantly facilitating intelligent transportation systems. Since the vehicles move fast and often change lanes unpredictably, the network topology evolves rapidly in a random fashion, which imposes diverse challenges in routing protocol design over VANET. When it comes to the 5G era, the fulfilment of ultra low end-to-end delay and ultra high reliability becomes more crucial than ever. In this paper, we propose a novel routing protocol that incorporates mobility status and MAC layer channel contention information. The proposed routing protocol determines next hop by applying mobility information and MAC contention information which differs from existing greedy perimeter stateless routing (GPSR) protocol. First, we use mobility information to estimate link expiration time and distance. Second, a mathematical model of backoff times is proposed based on the MAC layer backoff mechanism. Therefore, the MAC delay of each forwarding node can be evaluated on this basis. Finally, we combine these three aspects to evaluate the forwarding probability of each node. Simulation results of the proposed routing protocol show its performance superiority over the existing approach.