Secret Key Generation Rates for Line of Sight Multipath Channels in the Presence of Eavesdroppers

TL;DR

This paper investigates secret key generation using physical layer security in line-of-sight multipath channels, analyzing how channel parameters affect the mutual information and potential key rates.

Contribution

It derives RSS-based signal distributions and evaluates mutual information in LoS multipath channels, providing bounds for secret key rates under various channel conditions.

Findings

Mutual information varies with bandwidth, delay spread, and Rician K-factor.

RSS-based SKG rates are bounded by mutual information estimates.

Channel parameters significantly influence secret key generation potential.

Abstract

In this paper, the feasibility of implementing a lightweight key distribution scheme using physical layer security for secret key generation (SKG) is explored. Specifically, we focus on examining SKG with the received signal strength (RSS) serving as the primary source of shared randomness. Our investigation centers on a frequency-selective line-of-sight (LoS) multipath channel, with a particular emphasis on assessing SKG rates derived from the distributions of RSS. We derive the received signal distributions based on how the multipath components resolve at the receiver. The mutual information (MI) is evaluated based on LoS 3GPP channel models using a numerical estimator. We study how the bandwidth, delay spread, and Rician K-factor impact the estimated MI. This MI then serves as a benchmark setting bounds for the SKG rates in our exploration.