On the performance of adaptive relaying with ARQ

Adaptive relaying schemes significantly improve the performance of relay networks by switching the forwarding technique according to the reliability of the received signal. In adaptive relaying without ARQ all the relays forward irrespective of the decoding status at the destination. This leads to inefficient resource utilization. In ARQ relay networks, the message is repeated upon the request from the destination. In this paper we incorporate ARQ into the adaptive relaying schemes to highlight the gains obtained by using adaptability in conjunction with ARQ. Furthermore, instead of all relays forwarding, only the minimum possible number of relays which ensure successful decoding at the destination participate in forwarding. Different adaptive relaying schemes are taken into consideration. The end-to-end performance and relay selection criteria are determined. Finally, outage probability and throughput of different adaptive schemes with and without ARQ are calculated numerically. The results show that due to the efficient resource allocation and ARQ, adaptive relaying delivers superb performance over the non-ARQ counterpart regarding outage as well as throughput.