Relay Network Beamforming and Power Control Using Maximization of Mutual Information

A cooperative beamforming and power control scheme for amplify-and-forward wireless relay networks with single-antenna nodes is developed. Assuming perfect channel state information (CSI) and the existence of the direct link between the source and destination nodes, we design the optimal beamforming and power control weights that maximize the mutual information. In contrast to previous approaches to this problem, we consider the transmission of two independent information signals that can have different powers. The solution is obtained by considering the relay power control problem independently of the power allocation to the information signals. This results in an analytical solution that is then exploited in an iterative algorithm to obtain the final optimal beamforming weights. Our numerical results show that the proposed technique achieves a higher mutual information than previously proposed distributed beamforming and power control techniques.