Prediction error based feedback for downlink transmit beamforming

This paper examines a downlink transmit beamforming scheme recently proposed in [1]. The idea is based on the use of an adaptive channel estimator at the base-station and requires the mobile to selectively feed back the value of the prediction error. This paper proposes a joint maximum-likelihood and set-membership filtering algorithm for adaptive channel estimation that provides robustness against incorrect feedback due to mobile decision errors. The amount of power and bandwidth-saving possible with this scheme is quantified via an uplink capacity analysis.