Exploiting Asynchronous Amplify-and-Forward Relays to Enhance the Performance of IEEE 802.11 Networks

Cooperative communication is a promising path to recover from performance anomaly in IEEE 802.11 networks. However, a simple solution for employing multiple relays to enhance the relay link quality has not been proposed. The main obstacle for multiple relay utilization in distributed networks is that synchronizing relay transmissions requires huge signaling overhead. In this paper, we investigate the problem from both a physical-layer and MAC-layer point of view. In the physical layer, a simple, practical solution that provides diversity gain from asynchronous relay transmissions is introduced. In the MAC layer, a rate adaptation algorithm, RA-ARF, that takes the extra relay path into account is discussed, and R-MAC is designed to utilize relays in IEEE 802.11 networks. Our simulation results show considerable improvement in network performance using R-MAC.