Distributed Multichannel and Mobility-Aware Cluster-Based MAC Protocol for Vehicular Ad Hoc Networks

Since vehicular safety applications require periodic dissemination of status and emergency messages, contention-based medium-access-control (MAC) protocols such as IEEE 802.11p have problems in predictability, fairness, low throughput, latency, and high collision rate, particularly in high-density networks. Therefore, a distributed multichannel and mobility-aware cluster-based MAC (DMMAC) protocol is proposed. Through channel scheduling and an adaptive learning mechanism integrated within the fuzzy-logic inference system (FIS), vehicles organize themselves into more stable and nonoverlapped clusters. Each cluster will use a different subchannel from its neighbors in a distributed manner to eliminate the hidden terminal problem. Increasing the system´s reliability, reducing the time delay for vehicular safety applications, and efficiently clustering vehicles in highly dynamic and dense networks in a distributed manner are the main contributions of the proposed MAC protocol. The reliability and connectivity of DMMAC are analyzed in terms of the average cluster size, the communication range within the cluster and between cluster heads (CHs), and the lifetime of a path. Simulation results show that the proposed protocol can support traffic safety and increase vehicular ad hoc networks´ (VANETs) efficiency, reliability, and stability of the cluster topology by increasing the CH´s lifetime and the dwell time of its members.