Hybrid Digital/Analog Schemes for Secure Transmission with Side Information

TL;DR

This paper introduces a hybrid digital/analog scheme for secure transmission with side information, demonstrating optimality and superiority over pure digital or analog methods in certain Gaussian scenarios.

Contribution

It proposes a novel hybrid scheme that combines digital and analog approaches, achieving optimal secure transmission when side information is at the eavesdropper.

Findings

The hybrid scheme is optimal in the quadratic Gaussian case with side information at the eavesdropper.

It outperforms pure digital and analog schemes and cannot be replicated by time-sharing.

Application to binary symmetric sources with side information is also explored.

Abstract

Recent results on source-channel coding for secure transmission show that separation holds in several cases under some less-noisy conditions. However, it has also been proved through a simple counterexample that pure analog schemes can be optimal and hence outperform digital ones. According to these observations and assuming matched-bandwidth, we present a novel hybrid digital/analog scheme that aims to gather the advantages of both digital and analog ones. In the quadratic Gaussian setup when side information is only present at the eavesdropper, this strategy is proved to be optimal. Furthermore, it outperforms both digital and analog schemes and cannot be achieved via time-sharing. An application example to binary symmetric sources with side information is also investigated.