Design and Analysis of 802.11-Based MAC Protocol in Multi-Relay Wireless Networks

In this paper, we design and analyze a new 802.11-based cooperative MAC protocol. Since the wireless fading interval sometimes is comparable to the time of multiple-frame transmission, the traditional retransmission schemes may not be optimal. We consider designing a multi-relay system where neighbor nodes can assist the retransmission in order to achieve transmission diversity and combat channel fading. Since the cooperative capacity varies from relay to relay, the key point lies in how to assign different priorities to relays. This paper proposes a priority-based contention mechanism in cooperation, and tries to derive the optimal cooperation contention window size to maximize the network throughput. We present the results both from simulation and from theoretical analysis, which jointly verify the excellent performance of our new protocol.