Robust THP Transceiver Design with Partial CSI in TDD MU-MIMO Systems

In this paper, a partial channel state information (CSI) based robust Tomlinson-Harashima precoding (THP) transceiver is proposed in downlink time division duplexing (TDD) multi-user multiple-input multiple-output (MU-MIMO) systems. Partial CSI is obtained only based on the observations of uplink pilot training. Our robust THP transceiver includes THP matrices and a Demodulation Reference Signal (DMRS) precoding matrix. By minimizing the mean square error of the received signal at the user equipment (UE) side, robust THP matrices can be optimized at the BS. The optimized robust THP receiving matrices are transmitted to the UEs by DMRS. Based on the optimized THP matrices, DMRS precoder is also designed with partial CSI to make sure that the UEs can recover the receiving matrices as precise as possible. Simulation results show that our proposed THP transceiver is robust to both the partial CSI and the imperfect receiving matrices.