Optimal transmission policy of truncated cooperative ARQ protocols using opportunistic amplify and forward relaying

Abstract

In cooperative automatic repeat request (ARQ), the retransmission can be done by the source or by a selected relay. We consider opportunisitic amplify and forward (AF) relaying. The selected relay offers the highest instantaneous signal to noise ratio (SNR) of the relaying link (source-relay-destination). We investigate the optimal combination of source and relays transmission for a destination using a selective combining (SC) or a maximum ratio combining (MRC) of all received signals. This optimization is based on the bit error probability (BEP) at the destination after K transmissions.