Robust Linear Processing for Downlink MIMO-Relay Systems

This paper presents a robust linear processing scheme for the downlink of MIMO-relay systems with imperfect channel state information (CSI) aiming to minimize the mean squared error (MSE). The imperfect CSI consists of the channel estimate and the estimation error covariance matrix. The robust linear processing is based on the associated Karush-Kuhn-Tucker conditions. After obtaining the solution to the optimization problem, we investigate the effects of the channel estimation errors and antenna correlation on system performance. Simulation results show that the robust linear filter design scheme is capable of alleviating the effects of CSI errors and improving the robustness of system.