Transmit covariance for spatially-correlated multiple-antenna Ricean fading channels with channel distribution side information at transmitter

In this paper, we cast the problem of finding the capacity-achieving transmit covariance of correlated Ricean MIMO fading channels as an equivalent problem as for uncorrelated Ricean MIMO channels. Perfect channel information is assumed to be available at the receiver, while the transmitter only has channel distribution side information. An iterative algorithm based on Newton method to compute the capacity-achieving transmit covariance for the general case of double-ended correlated MIMO channels is proposed in this paper as well. Additionally, we provide a reduced complexity technique to attain a suboptimal transmit covariance. One of the main contributions in this paper is the characterization of the eigenstructure of the suboptimal transmit covariance. Moreover, Sufficient condition is derived for the optimality of this suboptimal solution.