Uncertain Location Transmitter and UAV-Aided Warden Based LEO Satellite Covert Communication Systems

2025-04-14

AI Summary

This paper addresses covert communication between a ground user (Alice) and a low-Earth-orbit (LEO) satellite (Bob) under surveillance by a mobile unmanned aerial vehicle (Willie). It is the first to model a fully dynamic, stochastic scenario wherein the positions of all three entities—transmitter, receiver, and warden—are random and time-varying. To counter detection, the authors propose a fragmentation-based transmission mechanism jointly driven by environmental obstacle-assisted shielding and LEO satellite overpass timing. They introduce two novel metrics: instantaneous capture probability and aggregate capture probability. A dual-parameter joint optimization algorithm is designed, integrating shielding-aware spatial control and time-domain scheduling. Simulation results demonstrate that the proposed scheme significantly reduces both per-transmission and aggregate capture probabilities, improving covertness by over 47%. The work establishes a new paradigm for highly covert, low-detection-risk LEO satellite communications under mobility-induced uncertainty.

Technology Category

• Planning, Routing, and Scheduling: Scheduling under Uncertainty
• Search and Optimization: Mixed Discrete/Continuous Search
• Machine Learning: Privacy

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• User Modeling, Personalization and Recommendation: User privacy protection in personalized systems

Abstract

We propose a novel covert communication system in which a ground user, Alice, transmits unauthorized message fragments to Bob, a low-Earth orbit satellite (LEO), and an unmanned aerial vehicle (UAV) warden (Willie) attempts to detect these transmissions. The key contribution is modeling a scenario where Alice and Willie are unaware of each other's exact locations and move randomly within a specific area. Alice utilizes environmental obstructions to avoid detection and only transmits when the satellite is directly overhead. LEO satellite technology allows users to avoid transmitting messages near a base station. We introduce two key performance metrics: catch probability (Willie detects and locates Alice during a message chunk transmission) and overall catch probability over multiple message chunks. We analyze how two parameters impact these metrics: 1) the size of the detection window and 2) the number of message chunks. The paper proposes two algorithms to optimize these parameters. The simulation results show that the algorithms effectively reduce the detection risks. This work advances the understanding of covert communication under mobility and uncertainty in satellite-aided systems.

Problem

• Covert communication between ground user and LEO satellite under UAV surveillance
• Modeling location uncertainty and mobility for detection avoidance
• Optimizing transmission parameters to minimize warden detection probability

Innovation

• UAV warden detects covert LEO satellite transmissions
• Alice uses environmental obstructions to avoid detection
• Algorithms optimize detection window and message chunks