Secure Communication over Interference Channel: To Jam or Not to Jam?

TL;DR

This paper analyzes secure communication over a two-user Gaussian interference channel, identifying when simple schemes suffice and proposing cooperative jamming strategies to achieve optimal secure sum capacity in more interference-heavy regimes.

Contribution

It characterizes the regimes where simple Gaussian wiretap coding is optimal and develops cooperative jamming schemes for higher interference levels, completing the secure sum GDoF characterization.

Findings

Simple scheme is optimal when interference-to-signal ratio ≤ 2/3.

Cooperative jamming improves secure sum GDoF for higher interference.

Complete characterization of secure sum GDoF across all regimes.

Abstract

We consider a secure communication over a two-user Gaussian interference channel, where each transmitter sends a confidential message to its legitimate receiver. For this setting, we identify a regime where the simple scheme of using Gaussian wiretap codebook at each transmitter (without cooperative jamming) and treating interference as noise at each intended receiver (in short, GWC-TIN scheme) achieves the optimal secure sum capacity to within a constant gap. For the symmetric case, this simple scheme is optimal when the interference-to-signal ratio (all link strengths in decibel scale) is no more than 2/3. However, when the ratio is more than 2/3, we show that this simple scheme is not optimal anymore and a scheme with cooperative jamming is proposed to achieve the optimal secure sum generalized degrees-of-freedom (GDoF). Specifically, for the symmetric case, we complete the optimal secure sum GDoF characterization for all the interference regimes.