Capacity optimization for ricean correlated MIMO channels with decorrelator receiver

This paper addresses the capacity optimization problem for MIMO wireless channels with a non-zero mean and transmit antenna correlation. With a decorrelator receiver, the capacity of the MIMO system is a function of the diagonal elements of an inverted noncentral Wishart distributed matrix. Hence, finding the average capacity is difficult. We simplify the problem by approximating the SNR of each spatial stream by a standard noncentral Chi-squared random variable. Using the moments of the SNR, we obtain a Taylor series approximation for the average capacity that is significantly better than the commonly used bound via Jensen´s inequality. The obtained Taylor series approximation is used to design a linear precoder that maximizes the total average capacity of the system. Simulation results are provided to illustrate the performance gain.