Performance analysis of limited feedback multiuser MIMO transmission with channel estimation error

In this paper, the impact of channel estimation error on the performance of multiuser Multiple-Input Multiple-Output (MIMO) transmission based on limited feedback information is analyzed. For zero-forcing beamforming without multiuser scheduling, a sum capacity lower bound is derived based on the quantization cell approximation, which shows that in the presence of the channel estimation error, the worst-case sum capacity converges to a finite ceil regardless of how fast the codebook size B increases at asymptotically high SNR. It is also shown that the larger the variance of the channel estimation error, the earlier the sum capacity begins to converge in terms of B. The case with multiuser selection diversity is also investigated, and it is shown that the sum capacity is bounded when the number of active users approaches infinity. The results are in contrast to the conclusions in the recent literature, and are verified by simulations.