Channel Estimation Error on Performance of Zero Force Beamforming Based Multiuser SDMA in Downlink

In a MIMO OFDMA multiuser system, the multiuser diversity gain can be achieved both in spatial and frequency domain by joint spatial and frequency scheduling. Although the channel estimation error (CEE) may degrade such multiuser diversity gain, little work has been performed on it. In this paper, we investigate the effect of the CEE on MIMO OFDMA downlink based on multiuser zero force beamforming (ZFB). The effect of channel estimation error on the signal to noise ratio of the desired user is analyzed, and the system spectrum efficiency is evaluated for different CEE value. The simulation results show that ZFB is not sensitive to CEE when a reasonable CEE value is guaranteed in a cellular system. Compared to the multiuser diversity gain from joint spatial frequency scheduling, the performance degradation from CEE is acceptable