Joint Network-Channel Design with Destination-Relay Feedback in Multiple-Access Relay Channel

The multiple-access relay channel (MARC) based on network coding, typically with two sources, one relay, and one destination, has been proposed in recent papers as an approach to achieve diversity gain in wireless networks and reduce the number of transmissions by the relay node. However, conventional network-coding-based MARC scheme wastes the channel resource because the relay forwards the signal every time regardless of the channel conditions. Our new scheme is that, through using the feedback information from the destination to the relay, the relay can use network coding, maximum ratio combining, or keep silent depending on the two source-destination channel link states. Then we derive the closed-form expressions for the outage probability and throughput of the system. Simulation results show that the new scheme improves the bit error rate(BER) and outage probability performance in contrast with direct transmission, and improves the throughput compared with conventional network coding scheme.