Study of Tomlinson-Harashima Precoding Strategies for Physical-Layer Security in Wireless Networks

TL;DR

This paper introduces novel non-linear precoding strategies for multi-user MIMO wireless systems to enhance physical-layer security against eavesdroppers, demonstrating superior secrecy rates and BER performance through simulations.

Contribution

It proposes a combined SO-THP and GMI precoding method for improved secrecy, and analyzes simplified GMI, LR techniques, and artificial noise strategies for security enhancement.

Findings

Proposed precoders outperform traditional methods in secrecy rate.

Non-linear precoders improve BER performance.

Artificial noise further enhances security without CSI.

Abstract

In this paper, we propose novel non-linear precoders for the downlink of a multi-user MIMO system with the existence of multiple eavesdroppers. The proposed non-linear precoders are designed to improve the physical-layer secrecy rate. Specifically, we combine the non-linear successive optimization Tomlinson-Harashima precoding (SO-THP) with generalized matrix inversion (GMI) technique to maximize the physical-layer secrecy rate. For the purpose of comparison, we examine different traditional precoders with the proposed algorithm in terms of secrecy rate as well as BER performance. We also investigate simplified generalized matrix inversion (S-GMI) and lattice-reduction (LR) techniques in order to efficiently compute the parameters of the precoders. We further conduct computational complexity and secrecy rate analysis of the proposed and existing algorithms. In addition, in the scenario without knowledge of channel state information (CSI) to the eavesdroppers, a strategy of injecting artificial noise (AN) prior to the transmission is employed to enhance the physical-layer secrecy rate. Simulation results show that the proposed non-linear precoders outperform existing precoders in terms of BER and secrecy rate performance.