An analytical comparison of partial power-feedback designs for MIMO block fading channels

It has been shown that with perfect feedback (CSIT), the optimal multiple input/multiple output (MIMO) transmission strategy is a cascade of channel encoder banks, power control matrix, and eigen-beamforming matrix. However, the feedback capacity requirement for perfect CSIT is 2n_T×n_R, which is not scalable with respect to n_T or n_R. In this letter, we shall compare the performance of two levels of partial power-feedback strategies, namely, the scalar symmetric feedback and the vector feedback, for MIMO block fading channels. Unlike quasi-static fading, variable rate encoding is not needed for block fading channels to achieve the optimal channel capacity.