On the Minimum Differential Feedback for Time-Correlated MIMO Rayleigh Block-Fading Channels

In this paper, the authors investigate the differential Channel State Information (CSI) feedback problem for a general Multiple Input Multiple Output (MIMO) system over time-correlated Rayleigh block-fading channels. Specifically, they first derive the analytical minimum differential feedback rate in the presence of channel estimation errors and quantization distortion. With the feedback-channel capacity constraint, in the periodic feedback system, they further study the relationship between the ergodic capacity and the feedback interval. They find that there exists an optimal feedback interval to maximize the ergodic capacity. Analytical results are verified by simulations in a practical differential feedback system employing Lloyd's quantization algorithm.