Improving Wireless Physical Layer Security via Exploiting Co-Channel Interference

TL;DR

This paper investigates how co-channel interference can be exploited to enhance physical layer security in MIMO wireless networks by characterizing the maximum secrecy degrees of freedom region and proposing an optimal cooperative transmission scheme.

Contribution

It introduces a cooperative secrecy transmission scheme that achieves the boundary of the S.D.o.F. region and derives closed-form expressions for maximum S.D.o.F. boundary points.

Findings

Maximum S.D.o.F. region boundary points are obtained in closed form.

The scheme achieves all S.D.o.F. pairs on the boundary.

Analytical expressions relate S.D.o.F. to antenna configurations.

Abstract

This paper considers a scenario in which a source-destination pair needs to establish a confidential connection against an external eavesdropper, aided by the interference generated by another source-destination pair that exchanges public messages. The goal is to compute the maximum achievable secrecy degrees of freedom (S.D.o.F) region of a MIMO two-user wiretap network. First, a cooperative secrecy transmission scheme is proposed, whose feasible set is shown to achieve all S.D.o.F. pairs on the S.D.o.F. region boundary. In this way, the determination of the S.D.o.F. region is reduced to a problem of maximizing the S.D.o.F. pair over the proposed transmission scheme. The maximum achievable S.D.o.F. region boundary points are obtained in closed form, and the construction of the precoding matrices achieving the maximum S.D.o.F. region boundary is provided. The obtained analytical expressions clearly show the relation between the maximum achievable S.D.o.F. region and the number of antennas at each terminal.