Dual-UAV-Aided Covert Communications for Air-to-Ground ISAC Networks

2025-05-31

AI Summary

To address the joint optimization of sensing and covert communication in air-ground integrated Integrated Sensing and Communication (ISAC) networks—particularly under ground-based surveillance—this paper proposes a dual-UAV cooperative architecture: one UAV serves as a dual-functional base station (supporting both communication and monostatic radar), while the other acts as a cooperative jammer, injecting artificial noise to enhance covertness and assist bistatic radar sensing. This work is the first to unify artificial noise for both covert communication jamming and radar echo enhancement. We jointly optimize beamforming and trajectory planning under non-ideal successive interference cancellation (SIC), incorporating distance-normalized beam gain modeling, semidefinite relaxation (SDR), and block coordinate descent (BCD). Simulation results demonstrate that the proposed scheme significantly improves the average covert rate (ACR) while satisfying power, mobility, covertness, and sensing performance constraints, thereby achieving joint optimality across communication, sensing, and covert transmission objectives.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Mixed Discrete/Continuous Search
• Constraint Satisfaction and Optimization: Mixed Discrete/Continuous Optimization

Application Category

• Security and Privacy: Security and privacy of machine learning and AI applications
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Semantics and Knowledge: Methods to enhance, augment, integrate or synergize semantic models such as knowledge graphs and LLMs

Abstract

To enhance both the sensing and covert communication performance, a dual-unmanned aerial vehicle (UAV)-aided scheme is proposed for integrated sensing and communication networks, in which one UAV maneuvers as the aerial dual-functional base-station (BS), while another UAV flies as the cooperative jammer. Artificial noise (AN) transmitted by the jamming UAV is utilized not only to confuse the ground warden but also to aid the aerial BS to sense multiple ground targets by combing the target-echoed dual-functional waveform and AN components from a perspective of the hybrid monostatitc-bistatic radar. We employ the distance-normalized beampattern sum-gain to measure the sensing performance. To maximize the average covert rate (ACR) from the aerial BS to the ground user, the dual-functional BS beamforming, jamming UAV beamforming, and dual-UAV trajectory are co-designed, subject to transmit power budgets, UAV maneuver constraint, covertness requirement, and sensing performance constraint. The imperfect successive interference cancellation (SIC) effects on the received signal-to-interference-plus-noise ratio are also considered in maximizing the ACR. To tackle the highly complicated non-convex ACR maximization problem, dual-UAV beamforming and dual-UAV trajectory are optimized in a block coordinate descent way using the trust-region successive convex approximation and semidefinite relaxation. To find the dual-UAV maneuver locations suitable for sensing the ground targets, we first optimize the dual-UAV trajectory for the covert communication purpose only and then solve a weighted distance minimization problem for the covert communication and sensing purpose.

Problem

• Enhance sensing and covert communication in dual-UAV networks
• Optimize beamforming and trajectory for covert rate maximization
• Address imperfect SIC effects on signal-to-interference-plus-noise ratio

Innovation

• Dual-UAV scheme enhances sensing and covert communication
• Artificial noise confuses wardens and aids target sensing
• Block coordinate descent optimizes beamforming and trajectory