A CSI feedback scheme for beamforming at AF relays

In cooperative wireless communications, beamforming at relays can be employed to increase the signal-to-noise ratio (SNR). Since beamforming at relays requires that channel state information (CSI) be exchanged, an efficient CSI feedback scheme is proposed to reduce the feedback overhead incorporating an optimization of the combining and beamforming weights. With 802.16e OFDMA time-division duplexing (TDD) systems, the proposed scheme feeds common information back to relays for beamforming, which should be acquired by a destination for combining. The simulation results verify that the proposed scheme reduces the feedback overhead and improves computational efficiency.