The Effect of Channel Estimation Error in Multiuser Downlink MIMO Relay Channels

This paper considers the effect of channel estimation error in the multiuser downlink MIMO relay channels. We introduce a modified upper bound and a modified power allocation strategy for the previous asymptotic optimal singular value decomposition zero-forcing beamforming (SVD-ZFBF) [2] at first. And then the effect of channel estimation error to SVDZFBF would be discussed. Similar with the full channel side information (CSI) case, SVD-ZFBF can approach the modified upper bound in the large user number case, no matter how large the channel estimation error is. And in the limited user number case, increasing relay station (RS) power would not make SVD-ZFBF approach the upper bound, which is different from the full CSI case. There is a capacity gap, which is mainly related to the channel estimation error from RS to users, between SVD-ZFBF and the upper bound.