Improved Achievable Rates for Regularized Tomlinson-Harashima Precoding in Multiuser MIMO Downlink

TL;DR

This paper introduces a tighter lower bound on the achievable information rate for regularized Tomlinson-Harashima precoding in multiuser MIMO downlink channels, especially effective at low SNRs, enhancing understanding of its performance.

Contribution

A new, more accurate lower bound on the achievable rate for regularized THP under AWGN with multiuser interference is derived, improving upon previous bounds.

Findings

Lower bound is tighter at low SNR

All bounds converge at high SNR to a specific value

Analytical results confirm improved rate estimates

Abstract

Tomlinson-Harashima precoding (THP) is considered as a prominent precoding scheme due to its capability to efficiently cancel out the known interference at the transmitter side. Therefore, the information rates achieved by THP are superior to those achieved by conventional linear precoding schemes. In this paper, a new lower bound on the achievable information rate for the regularized THP scheme under additive white Gaussian noise (AWGN) channel with multiuser interference is derived. Analytical results show that the lower bound derived in this paper is tighter than the original lower bound particularly for a low SNR range, while all lower bounds converge to 0.5xlog2(6SNR/{\pi}e) as SNR approaches infinity.