Characterizing the statistical properties of mutual information in MIMO channels: insights into diversity-multiplexing tradeoff

We consider Gaussian multiple-input multiple-output (MIMO) fading channels assuming that the channel is unknown at the transmitter and perfectly known at the receiver. Taking into account spatial fading correlation both at the transmitter and the receiver, a tight closed-form lower-bounds is provided for ergodic capacity and an accurate closed-form approximations of the variance of mutual information are derived over such channels. Based on these results, we investigate the impact of the number of antennas and transmit and receive correlation on ergodic capacity and on the variance of mutual information and draw insights into the tradeoff between diversity gain and spatial multiplexing gain.