This invention presents methods for MU-MIMO wireless communication systems comprising a BS with plural of antennas placed as a linear array or planar array, plural of UEs, for conducting two-level signal processing at the BS to reduce the system implementation complexity, i.e., the RF precoding/combination and the baseband precoding/detection, for the BS to obtain the second-order statistical information of the channel matrix of each UE to computing the RF precoding matrix through a much smaller number of pilots than that of the transceiving antennas at the BS, where the second-order statistical information of the channel matrix can be obtained through the uplink reference signals or downlink reference signals plus uplink feedback.