Combined multi-stage mmse and ML multiuser detection for underdetermined MIMO systems

We propose a so-called combined multi-stage minimum mean-square error (MSMMSE-ML MUD) in the underdetermined MIMO systems communicating over Gaussian fading channels. In a MIMO system with M transmitting antennas, after multi-stage MMSE detection is operated for the first (M-T) users, ML detection is executed for the last T users, where the parameter T is adopted to adjust the detection complexity of the last users. Considering an underdetermined MIMO system communicating over Gaussian fading channels, simulation results shows that the proposed method has a higher BER performance than the MSMMSE operated in the system.