Distributed Power Allocation Schemes for Amplify-and-Forward Networks

In this paper, distributed power allocation schemes are studied for amplify-and-forward (AF) cooperative relay networks, where only partial channel state information (CSI) is available at the source and relays. Aiming at minimizing the total transmit power while providing a target outage probability, a scheme is first investigated in which the source decides transmit power and a relay-forwarding threshold, and each relay makes individually the transmit decision based on the threshold and its own CSI. Then a single relay power allocation scheme is proposed to simplify the implementation complexity, in which only one relay is selected to forward messages. Simulation results illustrate the performance improvement of the proposed schemes.