Coherent opportunistic beamforming with partial channel information in multiuser wireless systems

In this paper, we propose a new beamforming scheme that can work with partial channel information. The proposed beamforming scheme can simultaneously achieve multiuser diversity (MUD) gain and beamforming gain by utilizing the beam weight information of the selected user in addition to the signal-to-noise ratio (SNR) information of all users. To fully exploit spatial multiplexing gain, we further consider the use of multiple beams. Multiple beams are generated in a sequential manner to reduce the interference among users, while virtually increasing the desired signal power. Finally, we analyze the performance of the proposed scheme and verify it by computer simulation. Although the proposed scheme is somewhat affected by the user mobility, numerical results show that the proposed scheme is quite effective in low mobility environments.