Improvement of multiuser diversity and multiplexing gain using multiple coherent beams

In this paper, we propose a multi-beam multiplexing scheme that can simultaneously achieve the spatial multiplexing gain, multiuser diversity gain and beamforming gain by using coherent multiple beams in the multi-user domain. Multiple beams are generated sequentially so that each beam maximizes receive signal to interference and noise power ratio (SINR) while providing zero interference toward prevously selected users. The use of multiple beams reduces the SNR of each channel (beam) in proportion to the number of beams. However, multiple beams are utilized so that the multiplexing gain is much larger than the decrease of SNR, increasing the overall system capacity. The proposed scheme is also applicable to MIMO as well as MISO schemes.