Reduced-Feedback Opportunistic Scheduling and Beamforming with GMD for MIMO-OFDMA

TL;DR

This paper introduces a novel GMD-based channel decomposition method for MIMO-OFDMA systems, enhancing feedback efficiency and system performance by evenly distributing channel gains across subchannels.

Contribution

It proposes GMD-based channel decomposition for reduced-feedback opportunistic scheduling and beamforming, improving performance over SVD-based methods.

Findings

Reduced feedback achieved by using one BFM for all subcarriers.

Improved system performance with more evenly distributed subchannel gains.

Numerical results confirm the effectiveness of the proposed schemes.

Abstract

Opportunistic scheduling and beamforming schemes have been proposed previously by the authors for reduced-feedback MIMO-OFDMA downlink systems where the MIMO channel of each subcarrier is decomposed into layered spatial subchannels. It has been demonstrated that significant feedback reduction can be achieved by returning information about only one beamforming matrix (BFM) for all subcarriers from each MT, compared to one BFM for each subcarrier in the conventional schemes. However, since the previously proposed channel decomposition was derived based on singular value decomposition, the resulting system performance is impaired by the subchannels associated with the smallest singular values. To circumvent this obstacle, this work proposes improved opportunistic scheduling and beamforming schemes based on geometric mean decomposition-based channel decomposition. In addition to the inherent advantage in reduced feedback, the proposed schemes can achieve improved system performance by decomposing the MIMO channels into spatial subchannels with more evenly distributed channel gains. Numerical results confirm the effectiveness of the proposed opportunistic scheduling and beamforming schemes.