Throughput and Performance Optimization Using an Adaptive Coded Cooperation Protocol

User cooperation enables single antenna terminals to benefit from spatial diversity by partnering with other users to create a virtual transmit antenna array. A promising form of cooperation is called coded cooperation which integrates cooperation with channel coding, showing great performance gains. However, the optimal degree of cooperation between the users changes with the channel conditions and there is no known expressions indicating the required degree of cooperation for given channel conditions. Furthermore, coded cooperation has a fixed throughput which inefficiently use the degrees of freedom of the channel, especially at high SNR. This paper proposes an adaptive coded cooperation protocol based on incremental redundancy using an ARQ/FEC scheme with rate-compatible punctured convolutional codes (RCPC). By employing a ACK/NACK feedback channel from the partner and the destination, each user adapts the size of the frames transmitted in the first and second cooperation phases in order to maximize throughput and to minimize errors due to the channel. Simulation results illustrate the gains and flexibility of our protocol for both reciprocal and non-reciprocal channels.