Aerial Relay to Achieve Covertness and Security

TL;DR

This paper proposes a UAV-based relay system that enhances covert and secure communication by optimizing trajectory and power, using advanced optimization techniques to maximize energy efficiency under uncertain malicious node positions.

Contribution

It introduces a robust fractional programming framework with novel optimization algorithms for UAV relay trajectory and power control in covert communication scenarios.

Findings

The proposed algorithms effectively optimize UAV trajectory and power.

Numerical results demonstrate improved energy efficiency and security.

The framework handles uncertainty in malicious node locations.

Abstract

In this work, a delay-tolerant unmanned aerial vehicle (UAV) relayed covert and secure communication framework is investigated. In this framework, a legitimate UAV serves as an aerial relay to realize communication when the direct link between the terrestrial transmitter and receiver is blocked and also acts as a friendly jammer to suppress the malicious nodes presented on the ground. Subsequently, considering the uncertainty of malicious nodes' positions, a robust fractional programming optimization problem is built to maximize energy efficiency by jointly optimizing the trajectory of the UAV, the transmit power of the transmitter, and the time-switching factor. For the extremely complicated covert constraint, Pinsker's inequality, Jensen's inequality, and the bisection search method are employed to construct a tractable shrunken one. After this, an alternate optimization-based algorithm is proposed to solve the fractional programming optimization problem. To achieve low complexity, we design the primal-dual search-based algorithm and the successive convex approximation-based algorithm, respectively, for each sub-problem. Numerical results show the effectiveness of our proposed algorithm.