Cooperative Relay MAC Protocol for Ad Hoc Networks

Based on the characteristic of supporting physical layer multiple rates in IEEE 802.11 standard, in this paper, we propose a Relay based Media Access Control (Relay-MAC) protocol. The key idea of Relay-MAC is using the high rate nodes to assist the low rate nodes in transmission by relay forwarding. According to Relay-MAC, each node in the network monitors the ongoing transmission of control frames, and obtains the channel quality between the source and the destination, then distributed decides whether to be a relay in the cooperative transmission. We make a detailed introduction of the frame format, the relay selection criterion, and the work process of the Relay-MAC. We also analyzed the spatial multiplexing problem presented in scenario with relay node. Finally, we compare the performance of the proposed Relay-MAC with the adaptive rate scheme, and demonstrate its efficiency in terms of network throughput and transmission delay.