Feedback granularity control for multiuser MIMO-OFDMA systems

In this paper, we propose a feedback granularity control scheme for multiuser multiple-input multiple-output orthogonal frequency-division multiple access (MIMO-OFDMA) systems. The proposed scheme resizes the unit and the resolution of the feedback to efficiently exploit channel correlations in both the time and the frequency domains. Two types (centralized and distributed) of granularity search methods are proposed, and their performance characteristics over practical wireless channels are investigated. Simulation results show that the proposed schemes (particularly the distributed method) effectively calculate the optimal granularity, and thus significantly improve the sum-rate of multiuser MIMO-OFDMA systems.