A modified precoding scheme for MIMO downlink channel with imperfect CSIT

In this paper, we consider the multiuser MIMO downlink channel with multiple antennas at both the base station and the users. We concentrate on the case where the transmitter has imperfect channel state information due to estimation error and feedback delay. A channel modification matrix and a scalar factor based on minimum mean square error criterion are derived to form an equivalent channel matrix which has a lower variance of error caused by imperfect estimation and feedback delay, and then used to design the precoding vectors based on maximizing the so-called signal-to-leakage-plus-noise-ratio. We present a scheme that combines co-channel interference suppression and channel modification in an appropriate way. Simulation results validate the presented scheme.