Reduced feedback selective cluster index scheduling with user pre-selection for next-generation multi-input multi-output orthogonal frequency division multiple access systems

The joint use of opportunistic scheduling and orthogonal frequency division multiple access (OFDMA) provide significant gains in environments of low mobility and scatter for which channel variations are low. The downside of opportunistic scheduling in multicarrier systems such as OFDMA, lies in the substantial uplink overhead required to feed back by the mobile stations (MSs) describing users' instantaneous link conditions. This study presents a novel approach towards multicarrier opportunistic scheduling for a multi-input multi-output configuration that promises major overhead reductions with only minor degradations on downlink throughput performance. The conventional channel quality indicator, in the form of instantaneous signal-to-noise ratio (SNR) is replaced by an alternative metric, in the form of the strongest cluster indices of each MS, which imposes a significantly reduced overhead. This study examines the performance of the proposes metric for random beamforming and examines the benefits in terms of throughput and feedback overhead over existing schemes. The results show that the proposed scheduling approach maintains performance within 1 dB of a full SNR based feedback scheme, while achieving feedback overhead reduction up to a factor of 24 and also providing improved fairness among users experiencing different channel gain levels.