Rethinking Secure Precoding via Interference Exploitation: A Smart Eavesdropper Perspective

TL;DR

This paper investigates secure precoding using constructive interference, addressing smart eavesdroppers exploiting statistical info, and proposes new design principles to enhance secrecy performance in wireless communication systems.

Contribution

It introduces a general principle for CI-based precoder design considering smart eavesdroppers and channel correlation, improving secrecy trade-offs over existing methods.

Findings

Modified CI-based precoder improves energy-secrecy trade-off.

New CI-design-based precoders significantly degrade eavesdropper's performance.

Precoders with the new design principle outperform existing approaches.

Abstract

Based on the concept of constructive interference (CI), multiuser interference (MUI) has recently been shown to be beneficial for communication secrecy. A few CI-based secure precoding algorithms have been proposed that use both the channel state information (CSI) and knowledge of the instantaneous transmit symbols. In this paper, we examine the CI-based secure precoding problem with a focus on smart eavesdroppers that exploit statistical information gleaned from the precoded data for symbol detection. Moreover, the impact of correlation between the main and eavesdropper channels is taken into account. We first modify an existing CI-based preocding scheme to better utilize the destructive impact of the interference. Then, we point out the drawback of both the existing and the new modified CI-based precoders when faced with a smart eavesdropper. To address this deficiency, we provide a general principle for precoder design and then give two specific design examples. Finally, the scenario where the eavesdropper's CSI is unavailable is studied. Numerical results show that although our modified CI-based precoder can achieve a better energy-secrecy trade-off than the existing approach, both have a limited secrecy benefit. On the contrary, the precoders developed using the new CI-design principle can achieve a much improved trade-off and significantly degrade the eavesdropper's performance.