On the Performance of Selection Cooperation ARQ

We extend current automatic repeat request (ARQ) protocols by proposing a cross-layer communication system, which relies on selection cooperation at the physical layer. We argue that selection cooperation is a better alternative to distributed space-time block coding (DTSBC) when coupled with non-cooperative ARQ protocols. The selection cooperation ARQ (SCARQ) system proposed in this paper performs better than competing alternatives, such as the DSTBC ARQ or the non-cooperative ARQ schemes, and has the added benefit of being simple to implement. To facilitate comparisons with cooperative and non-cooperative approaches, we develop a formula to calculate the throughput of the SCARQ system. The accuracy of the throughput formula is verified through Monte Carlo simulations. Using the proposed formula, we determine that a significant improvement in the performance of the retransmission process is achieved by using selection cooperation only among a small number of nodes.