Relay ordering in multi-branch multi-hop cooperative diversity networks

We consider a multi-branch multi-hop cooperative diversity network with the amplify-and-forward protocol. Specifically, each relay receives and combines the signals from the source and all the previous relays and then forwards the combined signal to the destination. We notice that the order of the transmission of the relays have a large impact on the performance of the cooperative network. In order to enhance the performance, an optimum algorithm for relay ordering is proposed at first. However, this optimum algorithm has a very high complexity and it is hard to implement. Therefore, we propose a suboptimum algorithm for relay ordering, which has a much lower complexity and it also achieves almost the same performance as the optimum algorithm.