Adaptive multi-node incremental relaying for hybrid-ARQ in AF relay networks

This paper proposes an adaptive multi-node incremental relaying technique in cooperative communications with amplify-and-forward (AF) relays. In order to reduce the excessive burden of MRC with all diversity paths at the destination node, the destination node decides if it combines signals over the first N(< K) time slots/frames or over all of the K times slots, where K is the number of relay nodes. Our analytical and simulation results show that the proposed adaptive multi-node incremental relaying outperforms the conventional MRC in terms of outage probability in AF based cooperative communications since the proposed scheme effectively reduces the spectral efficiency loss. Our asymptotic analysis also shows that the proposed adaptive multi-node incremental relaying achieves full diversity order K + 1.