A Relay-Optimized Cooperative MAC Protocol for Mobile Ad Hoc Networks

To improve cooperative efficiency in mobile ad hoc networks, a relay-optimized cooperative MAC (RO-CMAC) protocol is proposed in this paper. In the protocol, an optimal relay is selected through two or three contention phases in case of low data rate of direct transmission from a sender to its recipient. In the first phase, all relays with the highest data rates to the sender and its recipient are selected. Then the second phase is performed to decide whether the winning relays in the first phase have their own data packets to send. If have, the third contention phase using an efficient k-round contention resolution (k-CR) scheme is adopted to select unique optimal relay for packet piggyback transmission, which can reduce reservation overhead and improve channel utilization. Simulation results show that the proposed protocol can achieve better performance than the CRP-CMAC and Coop MACA protocols.