Evaluation of Tomlinson-Harashima Precoding for Cellular System

Non-linear precoding outperforms linear precoding in a multi-user multi-input multi-output (MU-MIMO) system. The actual gain depends on multiple factors, including number of users, user distribution in the system, etc. Furthermore, to achieve the promised gain, non-linear precoding requires a higher implementation complexity which has prevented its adoption into the 3rd Generation Partnership Project (3GPP) standards. In many practical scenarios, the number of paired users for MU-MIMO remains low. When the number of paired scheduled users for MU-MIMO systems is low, the complexity of non-linear precoding becomes less significant. In this paper, we show that, even when, the number of paired users for MU-MIMO is not more than two, non-linear precoding can still offer a meaningful performance improvement over the linear precoding. For our study, under 3GPP new radio framework, we have evaluated and compared the performance of Tomlinson-Harashima non-linear precoding against a block diagonalized linear precoding.