Physical Layer Location Privacy in SIMO Communication Using Fake Path Injection

TL;DR

This paper proposes a novel fake path injection method in SIMO channels to enhance physical location privacy by increasing the difficulty for eavesdroppers to accurately locate the transmitter.

Contribution

It introduces a new privacy metric based on eigenvalues of CRB matrices and derives bounds showing quadratic privacy margin growth with angular separation.

Findings

Privacy margin increases quadratically with inverse angular separation.

Numerical simulations confirm theoretical CRB bounds.

The approach improves bit error rate differences between Bob and Eve.

Abstract

Fake path injection is an emerging paradigm for inducing privacy over wireless networks. In this paper, fake paths are injected by the transmitters into a single-input multiple-output (SIMO) communication channel to obscure their physical location from an eavesdropper. The case where the receiver (Bob) and the eavesdropper (Eve) use a linear uniform array to locate the transmitter's (Alice) position is considered. A novel statistical privacy metric is defined as the ratio between the smallest (resp. largest) eigenvalues of Eve's (resp. Bob's) Cram\'er-Rao lower bound (CRB) on the SIMO channel parameters to assess the privacy enhancements. Leveraging the spectral properties of generalized Vandermonde matrices, bounds on the privacy margin of the proposed scheme are derived. Specifically, it is shown that the privacy margin increases quadratically in the inverse of the angular separation between the true and the fake paths under Eve's perspective. Numerical simulations validate the theoretical findings on CRBs and showcase the approach's benefit in terms of bit error rates achievable by Bob and Eve.