Filter-and-forward relay beamforming using output power minimization

In this paper, we consider designing the Filter-and-forward (FF) relay beamforming in frequency-selective channels using a new approach. The proposed approach aims to minimize the output power at the destination side while keeping the response to the desired signal at a constant level, and the problem is subject to both total and individual relay transmit power constraints. It is shown that the proposed beamforming design scheme is equivalent to the SINR maximization formulation, in terms of achieving the same output SINR. Despite the equivalence in performance, the proposed approach requires significantly lower computational load for solving the problem.