Robust Cooperative Relaying in an Amplify-and-Forward Network

It has been shown that cooperative communication can significantly improve performance by utilizing distributed relay nodes. In most cases, cooperative communication systems have been designed and evaluated assuming perfect channel state information (CSI). Due to the feedback delay of the estimated CSI, a level of uncertainty in the channel estimates is inevitable, and systems designed for perfect CSI might not be optimal. In this paper we propose and evaluate several robust relay selection schemes for a best-select, amplify-and-forward cooperative communication system. Simulation results show that the proposed schemes can improve the average received SNR by 1.5 dB when the channel estimates are highly unreliable.