A Novel TDMA-MAC Protocol for VANET Using Cooperative and Opportunistic Transmissions

This paper presents a novel time division multiple access-medium access control (TDMA-MAC) protocol for vehicular ad hoc networks (VANETs), in which both cooperative and opportunistic transmissions are employed for enhanced communications. When vehicle density is low, the idle time slots of a licensed VANET channel are used for cooperative transmission through a relay. When the vehicle density is high, cognitive radio technique is applied to seek additional time slots available on the cognitive channels for opportunistic transmission. Simulation results show that the proposed TDMA-MAC protocol can reduce latency and packet loss rate significantly when compared with the existing protocols.