Covert Single-hop Communication in a Wireless Network with Distributed Artificial Noise Generation

TL;DR

This paper explores how adding friendly nodes that generate artificial noise can significantly improve covert communication rates in wireless networks, especially against multiple collaborating wardens, without requiring tight coordination.

Contribution

It introduces a novel approach where nearby nodes produce artificial noise to enhance covert throughput, extending the three-party model to more complex network scenarios.

Findings

Artificial noise from close nodes improves covert throughput.

No significant gain in covert throughput under certain restrictions.

Multiple wardens collaborating reduces achievable covert communication rates.

Abstract

Covert communication, also known as low probability of detection (LPD) communication, prevents the adversary from knowing that a communication is taking place. Recent work has demonstrated that, in a three-party scenario with a transmitter (Alice), intended recipient (Bob), and adversary (Warden Willie), the maximum number of bits that can be transmitted reliably from Alice to Bob without detection by Willie, when additive white Gaussian noise (AWGN) channels exist between all parties, is on the order of the square root of the number of channel uses. In this paper, we begin consideration of network scenarios by studying the case where there are additional "friendly" nodes present in the environment that can produce artificial noise to aid in hiding the communication. We establish achievability results by considering constructions where the system node closest to the warden produces artificial noise and demonstrate a significant improvement in the throughput achieved covertly, without requiring close coordination between Alice and the noise-generating node. Conversely, under mild restrictions on the communication strategy, we demonstrate no higher covert throughput is possible. Extensions to the consideration of the achievable covert throughput when multiple wardens randomly located in the environment collaborate to attempt detection of the transmitter are also considered.