Transceiver Designs Using Non-Linear Precoding for Multiuser MIMO Systems with Limited Feedback

For multiuser multiple-input multiple-output (MU-MIMO) systems with limited feedback in the downlink scenario, an end-to-end robust Tomlinson-Harashima Precoding (THP) transceiver design that incorporates receiver combining and transmit precoder is proposed based on sum mean squared error (SMSE) minimization. The channel state information (CSI) available at the transmitter for precoding is the quantized channel direction information (CDI) relayed back from each receiver using feedback bits in such system. The proposed transceiver design method is robust to the channel uncertainties arising from the quantization error and the lack of channel magnitude information (CMI). As an aside, the authors analyse the SMSE performance of the proposed algorithm. Our simulation results show that the new THP scheme outperforms the conventional precoding in limited feedback systems with respect to Bit Error Ratio (BER).