A decentralized multiple relay selection scheme for cooperative relay networks with distributed space-time coding

In this paper, we develop a novel relay selection scheme for amplify-and-forward relay network with distributed space time coding. Using the criterion of maximizing the received signal-to-noise ratio (SNR), the multiple relay selection problem is presented. The optimal solution of this problem can be obtained by exhaustive search, which has computational complexity growing with the number of relays and leads to a centralized implementation. To circumvent this problem, an opportunistic relaying scheme is introduced and the associated selection function is derived, which is based on the approximate of the received SNR. This selection function can be computed based on the local channel information and, hence can be implemented in decentralized strategy. Simulation results show that the proposed scheme outperforms the existing opportunistic schemes. Moreover, the BER performance of the proposed scheme approaches to that of the optimal scheme with a considerably lower complexity.