ZF-DFE transceiver for time-varying MIMO channels with channel-independent temporal precoder

This paper considers the DFE transceiver optimization for time-varying memoryless MIMO channels under zero-forcing (ZF) constraint. For time-varying channels, the uncoded average BER of the conventional geometric mean decomposition (GMD) based systems is not minimized because of the diverse arithmetic MSEs at different block times. To minimize the BER, a new GMD transceiver is proposed, in which the data vectors are grouped into space-time blocks (ST-blocks). A channel independent-temporal precoder is superimposed on the conventional blockwise GMD for the equalization of arithmetic MSEs across different blocks. So, the proposed system can take advantage of both the temporal and spatial diversity offered by time-varying MIMO channels. At moderate high SNR, corresponding to reasonable BER, there exists a class of optimal channel-independent temporal precoders, e.g., DFT and Hadamard matrices, for the minimization of average BER. Furthermore, simulation results show that the average BER performance of the proposed system improves with ST-block size and converges at moderate ST-block size.