Adaptive codebook-based channel prediction and interpolation for multiuser multiple-input multiple-output-orthogonal frequency division multiplexing systems

In multiple-input multiple-output–orthogonal frequency division multiplexing (MIMO–OFDM) communications, the channel state information (CSI) of the forward link at each subcarrier is needed for precoder design at the transmitter to achieve the maximal diversity and/or multiplexing gains. In frequency division duplex (FDD) systems, the CSI needs to be estimated at the receivers and fed back to the transmitters. Owing to the limited network resources, there will be CSI feedback errors due to quantisation, delay and clustering (where one CSI feedback is used to represent a cluster of adjacent subcarriers for feedback reduction). Consequently, the system performance degrades and the gains expected from using MIMO diminish. To mitigate this performance degradation, an adaptive codebook-based CSI prediction and interpolation scheme is proposed for multiuser MIMO–OFDM systems. In this scheme, geodesic CSI prediction is employed at the receiver to mitigate the feedback delay effect and geodesic CSI interpolation is performed at the transmitter to mitigate the clustering feedback effect. Since the performance gain assumed by the CSI prediction and interpolation is limited by the low-resolution CSI quantisation, an adaptive codebook scheme is proposed to be used to support the CSI prediction and interpolation. Simulation results show that the proposed scheme is effective in mitigating the performance loss due to quantisation, feedback delay and clustering feedback.