Aerial Relay to Achieve Covertness and Secrecy

2024-06-10

IEEE Transactions on Vehicular Technology

AI Summary

This work addresses secure and energy-efficient UAV-relayed communication under challenging conditions: obstructed direct links and uncertain locations of malicious eavesdroppers. Method: We propose a joint optimization framework that synergistically enhances covertness, security, and energy efficiency. A dual-role UAV serves both as a relay and a friendly jammer—forwarding legitimate traffic while actively suppressing eavesdropping. We jointly optimize the UAV’s 3D trajectory, ground transmitter’s power allocation, and time-division switching factor. To handle the non-convex covertness constraint induced by location uncertainty, we innovatively reformulate it using Pinsker’s and Jensen’s inequalities. The resulting problem is solved via robust fractional programming, successive convex approximation, and alternating optimization. Results: Simulations demonstrate that the proposed method significantly improves system energy efficiency under worst-case eavesdropper location uncertainty, while rigorously satisfying covertness, security, and robustness requirements.

Technology Category

• Planning, Routing, and Scheduling: Scheduling under Uncertainty
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Search and Optimization: Mixed Discrete/Continuous Search

Application Category

• Security and Privacy: Applications of cryptography
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments

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.

Problem

• UAV relay ensures covert secure communication when direct links fail
• Optimizes energy efficiency via trajectory power and time-switching factors
• Develops low-complexity algorithms to handle complex covert constraints

Innovation

• UAV relay for covert secure communication
• Robust optimization for energy efficiency
• Low-complexity primal-dual search algorithm