Cluster-based interference-free MAC protocol with load aware in software defined VANET

In order to reduce the interference, a novel, cluster-based medium access control (MAC) protocol with load aware for VANETs is proposed in this paper. First, all vehicles on roads are grouped into stable clusters in the light of their direction, number of neighbors, link reliability, and traffic load. By utilizing the advantages of centralized control in software defined VANETs (SDVN), cluster stability can be maintained in real-time. Second, a contention-free MAC mechanism composed of inter-cluster multi-channel allocation and intra-cluster dynamic TDMA frame allocation is proposed to prevent co-channel interference and hidden terminal interference. Simulation results show that the proposed protocol outperforms some existing protocols in cluster stability, delivery ratio, throughput and delay performance.