Asymptotic Performance of Mimo Wireless Channels with Limited Feedback

Abstract – We consider a single-user, point-to-point communication system with transmit and receive antennas with independent flat Rayleigh fading between antenna pairs. The mutual information of the multi-input/multioutput (MIMO) channel is maximized when the transmitted symbol vector is a Gaussian random vector with covariance matrix . The optimal depends on how much channel state information is available at the transmitter. Namely, in the absence of any channel state information, the optimal is full-rank and isotropic, whereas with perfect channel knowledge, the optimal has columns which are the eigenvectors of the channel, and has rank at most .