On the Security Analysis of a Cooperative Incremental Relaying Protocol in the Presence of an Active Eavesdropper

TL;DR

This paper analyzes the physical-layer security of a cooperative wireless network with active eavesdroppers using artificial noise, proposing relay selection schemes to enhance secrecy capacity and demonstrating their effectiveness through analytical and simulation results.

Contribution

It introduces a decode-and-forward incremental relaying protocol with relay selection schemes tailored for active eavesdroppers transmitting artificial noise, providing exact closed-form expressions for security metrics.

Findings

Proposed IR-based relay selection schemes outperform existing methods.

Artificial noise creates a secrecy outage floor without relay assistance.

Analytical expressions accurately predict the schemes' performance.

Abstract

Physical layer security offers an efficient means to decrease the risk of confidential information leakage through wiretap links. In this paper, we address the physical-layer security in a cooperative wireless subnetwork that includes a source-destination pair and multiple relays, exchanging information in the presence of a malevolent eavesdropper. Specifically, the eavesdropper is active in the network and transmits artificial noise (AN) with a multiple-antenna transmitter to confound both the relays and the destination. We first analyse the secrecy capacity of the direct source-to-destination transmission in terms of intercept probability (IP) and secrecy outage probability (SOP). A decode-and-forward incremental relaying (IR) protocol is then introduced to improve reliability and security of communications in the presence of the active eavesdropper. Within this context, and depending on the availability of channel state information, three different schemes (one optimal and two sub-optimal) are proposed to select a trusted relay to improve the achievable secrecy rate. For each one of these schemes, and for both selection and maximum ratio combining at the destination and eavesdropper, we derive new and exact closed-form expressions for the IP and SOP. Our analysis and simulation results demonstrate the superior performance of the proposed IR-based selection schemes for secure communication. They also confirm the existence of a floor phenomenon for the SOP in the absence of AN.