Capacity of MIMO Rician fading channels with transmitter and receiver channel state information

This paper investigates the capacity of multiple-input multiple-output (MIMO) wireless communication systems when instantaneous channel state information (CSI) is available at both the transmitter and the receiver in a line-of-sight Rician fading environment. Specifically, an infinite series representation for the ergodic capacity of MIMO channels subject to uncorrelated Rician fading (URiF) is derived, assuming both transmitter and receiver CSI. The ergodic capacity and its associated outage probability are expressed as a function of a cutoff value capturing the optimal power allocation scheme. Moreover, an equation for evaluating the cutoff value using standard numerical search techniques is derived, along with closed-form expressions for the capacity of the URiF MIMO channel when the so-called eigen-mode channel inversion technique and its truncated variant are implemented. We then provide numerical results showing the effects of Ricianness on the capacity of the eigen-mode optimal power and rate adaptation, and the sub-optimal channel inversion techniques and compare the achievable spectral efficiencies with and without channel knowledge at the transmitter thereby highlighting the capacity gains enabled by channel side information in a Rician fading environment.