Downlink beamforming method for SDMA smart antennas - transmission performance for the angular spread

摘要

Space Division Multiple Access (SDMA) is an attractive candidate for the increase of the channel capacity. In the SDMA system, signals from multiple terminals can be spatially separated and this feature enables the terminals to use the same frequency and the same timing. However, slight channel estimation error affects the transmission quality significantly in downlink. In this paper, we propose a new closed-loop SDMA downlink beam-forming method, which employs transmission diversity for multi-beams and mitigates the influence of multipath fading. The effectiveness for angular spread and the Doppler frequency is evaluated in computer simulations and we will show that the proposed method achieves the 3dB higher SINR than that of the conventional one in flat fading environments.