Cooperative MAC protocol with distributed relay selection and physical rate adaptation

In this paper, a new cooperative MAC protocol with distributed relay selection and rate adaptation is proposed in the context of multi-rate ad hoc networks. When the wireless link between a source and a destination nodes experiences poor channel conditions, a relay station is selected in the vicinity of both nodes so that the low data rate direct link is replaced by a two-hop path with a higher data rate. The relay station is selected through a distributed contention process. The procedure requires no topology knowledge and no communication among potential relays. A data rate adaptation is also performed without any additional signaling. The best-relay selection and the rate adaptation are based on instantaneous channel measurements to adapt to dynamic channel conditions. Results show that cooperative transmissions significantly outperform conventional non-cooperative transmissions in terms of throughput, delay and energy consumption.