Joint 3D Trajectory Design and Resource Allocation for Secure Dual-UAV-aided Underlay Systems

2026-06-12

AI Summary

This work addresses physical-layer security in wireless networks with aerial eavesdroppers by jointly optimizing the three-dimensional trajectories of two unmanned aerial vehicles (UAVs), transmit power allocation at ground users and jammers, and user scheduling to maximize the system’s average secrecy spectral efficiency. To tackle the resulting non-convex problem, the authors introduce a differentiable lower-bound approximation of the expected secrecy spectral efficiency, enabling decomposition into tractable subproblems. These are efficiently solved via block coordinate descent, successive convex approximation, and slack variable techniques. This study presents the first framework for joint secure optimization of 3D UAV trajectories and resource allocation in a dual-UAV setup. Simulation results demonstrate that the proposed method significantly enhances secrecy performance, underscoring the critical role of three-dimensional trajectory design in improving physical-layer security.

Abstract

Uncrewed aerial vehicles (UAVs) are increasingly being employed for data collection tasks, thanks to their high mobility and easy deployment, acting as aerial platforms to collect data from ground devices (GDs). This study considers a secure underlay data collection system assisted by dual UAVs and focuses on the joint design of the UAVs' three-dimensional (3D) flight paths, the power of the jamming UAV, the power of GDs, and the scheduling of the underlay GDs in the context of an aerial eavesdropper. The highly coupled objective function and non-convex constraints make the formulated problem more complicated to solve. We first utilize an approximate lower bound on the expected spectral efficiency to streamline the solution process. The average secrecy spectral efficiency (ASSE) is maximized by jointly designing the 3D trajectory of the UAVs, the transmit power of GDs, and the user scheduling. The optimization problem is decomposed into four subproblems using block coordinate descent, with each of them into manageable convex optimization tasks by incorporating slack variables and employing successive convex approximation methods. The numerical results validate the effectiveness of our proposed approach, demonstrating that the design of UAV 3D trajectories remarkably improves the ASSE of the considered system.

Problem

• UAV trajectory design
• secure communication
• resource allocation
• underlay system
• secrecy spectral efficiency

Innovation

• 3D trajectory design
• secure UAV communication
• joint resource allocation
• successive convex approximation
• average secrecy spectral efficiency