A Differential Feedback Scheme Exploiting the Temporal and Spectral Correlation

Channel state information (CSI) provided by a limited feedback channel can be utilized to increase system throughput. However, in multiple-input-multiple-output (MIMO) systems, the signaling overhead realizing this CSI feedback can be quite large, whereas the capacity of the uplink feedback channel is typically limited. Hence, it is crucial to reduce the amount of feedback bits. Prior work on limited feedback compression commonly adopted the block-fading channel model, where only temporal or spectral correlation in a wireless channel is considered. In this paper, we propose a differential feedback scheme with full use of the temporal and spectral correlations to reduce the feedback load. Then, the minimal differential feedback rate over a MIMO time-frequency (or doubly)-selective fading channel is investigated. Finally, the analysis is verified by simulation results.