Robust Tomlinson-Harashima precoding with Kalman channel tracking in MIMO systems

The multiple-input multiple-output (MIMO) Tomlinson-Harashima precoder (THP) is an equalization structure for mitigating inter-stream interference in fading MIMO systems. It is well known that THP is optimal with perfect channel state information (CSI) at both transmitter and receiver. However, this assumption is not achievable in real world. In this work, under the assumption of partial channel state information (P-CSI), we show that the THP precoded MIMO system with Kalman (THP-Kalman) channel tracking outperforms that with linear minimum mean-square-error (LMMSE) estimator (THP-LMMSE) when operating in time-division-duplex (TDD) mode. Also, THP-Kalman exhibits robust error performance in fast fading, while THP-LMMSE is more sensitive to the varying rate of channel.