Effectiveness Evaluation of Multi-user MIMO Tomlinson-Harashima Precoding in LEO Satellite Communication Systems

This study investigates the effectiveness of multi-user multiple-input and multiple-output (MU-MIMO) Tomlinson-Harashima precoding (THP) in low Earth orbit (LEO) satellite communication (SATCOM) systems. The objective is to explore the potential of complementing terrestrial networks with LEO SATCOMs for coverage enhancement in sixth-generation mobile communication systems (6G). In particular, we focused on line-of-sight environments unique to LEO SATCOMs and adopted THP as a spatial-correlation-tolerant MU-MIMO precoding scheme. To evaluate the performance of THP, we utilized a channel model based on 3GPP technical report 38.811, which represents the communication between the LEO satellite equipped with a uniform planner array antenna and terrestrial user terminals. The system capacity of THP was derived from a mod-Λ-channel-based analysis. To provide a comprehensive comparison, we conducted computer simulations to contrast the performance of THP and that of the traditional linear precoding (LP). The numerical results obtained from this study shed light on the applicability of THP in LEO SATCOM systems.