Abstract：In multi-user multi-antenna downlink system, when the channels are Rician channels, the performance of those limited feedback strategies designed for uncorrelated Rayleigh Channels will result to the waste of feedback overhead. To solve this problem, a new adaptive feedback strategy is proposed in Rician channels. First, a new concept of the angle distance distribution in the Rician channel is introduced. Based on this theory and using the channel mean information at the transmitter, the proposed strategy can design a special threshold to adjust user’s codebook, which is closer to the channel direction. Moreover, this strategy can still adjust its number of feedback bits adaptively according to different channel distributions without increasing the quantized error of channel direction. The simulation shows that, compared to those strategies proposed for Rayleigh systems, the strategy can reduce feedback overhead greatly without decreasing system sum-rate.
2009, Vol. 31 
