Impact of relay gain allocation on the performance of cooperative diversity networks

We consider a wireless network with one source/destination pair and several linear amplify-and-forward relays. The influence of the gain allocation at the relays on the performance in cooperative relay communication links is analyzed. We present an optimal gain allocation which results in a coherent combining of all signal contributions at the destination and maximizes the instantaneous throughput of the link. If the channel state information (CSI) at the relays is limited, cooperative diversity schemes can be used. We show that the right choice of the amplification gains is crucial to achieve high outage throughput.