Tomlinson-Harashima Precoding with Stream Combiners for MU-MIMO with Rate-Splitting

TL;DR

This paper proposes a novel MU-MIMO architecture using rate-splitting, non-linear precoding, and stream combining with multiple antennas, achieving improved sum-rate performance under partial CSI knowledge.

Contribution

It introduces a new MU-MIMO scheme combining rate-splitting, Tomlinson-Harashima precoding, and multi-branch architecture with closed-form performance expressions.

Findings

Proposed schemes outperform conventional linear and THP precoders.

Incorporating multi-branch architecture enhances sum-rate performance.

Analytical expressions for SNR and sum-rate are derived.

Abstract

This paper introduces multiuser multiple-input multiple-output (MU-MIMO) architectures based on non-linear precoding and stream combining techniques using rate-splitting (RS), where the transmitter often has only partial knowledge of the channel state information (CSI). In contrast to existing works, we consider deployments where the receivers may be equipped with multiple antennas. This allows us to employ linear combining techniques based on the Min-Max, the maximum ratio and the minimum mean-square error criteria along with Tomlinson-Harashima precoders (THP) for RS-based MU-MIMO systems to enhance the sum-rate performance. Moreover, we incorporate the Multi-Branch (MB) concept into the RS architecture to further improve the sum-rate performance. Closed-form expressions for the signal-to-interference-plus-noise ratio and the sum-rate at the receiver end are devised through statistical analysis. Simulation results show that the proposed RS-THP schemes achieve better performance than conventional linear and THP precoders.