This invention presents methods for signal detection and transmission in MU-MIMO wireless communication systems, for multiple UEs transmit uplink SRS to capture the uplink channel coefficients, and to estimate the frequency offsets and time offsets, for the BS estimating the channel coefficients of multiple UEs with the received SRS, for the BS estimating the frequency offsets and time offsets of multiple UEs with the estimated channel coefficients, for the BS modifying the estimated channel coefficients with the estimated frequency offsets and time offsets, for the BS calculating the detection matrices for the uplink MU-MIMO signal detection with the modified channel coefficients and for the BS calculating the precoding matrices for the downlink MU-MIMO signal transmission.