On the Detection of Passive Eavesdroppers in the MIMO Wiretap Channel

TL;DR

This paper proposes methods for legitimate nodes to detect passive eavesdroppers in MIMO wiretap channels by analyzing leaked RF signals, enabling enhanced secrecy rate in dynamic networks.

Contribution

It introduces detection techniques based on local oscillator leakage for passive eavesdropper identification in MIMO systems, a novel approach in physical layer security.

Findings

Non-coherent energy detection improves detection performance.

Optimal coherent detection enhances eavesdropper detection accuracy.

Proposed methods increase the secrecy rate of the MIMO wiretap channel.

Abstract

The classic MIMO wiretap channel comprises a passive eavesdropper that attempts to intercept communications between an authorized transmitter-receiver pair, each node being equipped with multiple antennas. In a dynamic network, it is imperative that the presence of an eavesdropper be determined before the transmitter can deploy robust secrecyencoding schemes as a countermeasure. This is a difficult task in general, since by definition the eavesdropper is passive and never transmits. In this work we adopt a method that allows the legitimate nodes to detect the passive eavesdropper from the local oscillator power that is inadvertently leaked from its RF front end. We examine the performance of non-coherent energy detection and optimal coherent detection, followed by composite GLRT detection methods that account for unknown parameters. Numerical experiments demonstrate that the proposed detectors allow the legitimate nodes to increase the secrecy rate of the MIMO wiretap channel.