Optimizing ARQ strategies in relay networks

In this paper the novel issue of retransmissions allocation in ARQ relay networks is introduced. In ARQ relay networks, the source and relays repeat a signal in response to a request from the destination. The source and relays can repeat once or multiple times with a constant power. Contrary to the protocols where a node is constrained to transmit once, we allow each node to retransmit multiple times. The goal is to allocate the optimal (minimum) number of retransmissions resulting in successful decoding at the destination. We devise an optimization method which is optimal. Moreover, the performance of the protocol with multiple retransmissions is compared to that of protocols with one retransmission per node or all the retransmissions from a single node. The results reveal that multiple retransmission protocols deliver superior performance over the counterparts.