Transmit nullforming for a MIMO/SDMA downlink with receive antenna selection

In this paper, we propose a novel downlink null-forming technique for space division multiple access (SDMA) in a multiple-input multiple-output (MIMO) channel where a base station and all terminal stations have multiple antennas. In the SDMA system, simple beamforming is not efficient to achieve good performance due to cochannel interference. The proposed method is based on nullforming and characterized by antenna element selection at each terminal where the selected antenna pair satisfies the lowest spatial correlation condition in all combinations. The results obtained by computer simulations show selective diversity gain of the proposed method and performance improvement due to joint detection at each terminal.