A Review of Space-Based GNSS Interference Monitoring Technology: Development, Methods, Architectures, and Challenges

With the widespread application of Global Navigation Satellite Systems (GNSS) in critical industries such as transportation, aviation, maritime, communications, and finance, the increasing incidence of GNSS interference has become a global threat to the security of Positioning, Navigation, and Timing (PNT) services. Constrained by limited coverage and deployment density, traditional ground-based interference monitoring systems cannot provide continuous global-scale monitoring capability. Low Earth Orbit (LEO) satellite constellations offer the advantages of global coverage, wide-area monitoring capability, and continuous monitoring, providing a new solution for global GNSS interference monitoring. This paper provides a comprehensive review of the development history, key methods, system architectures, and future challenges of GNSS interference monitoring technology using LEO satellite constellations. First, the paper traces the evolution of space-based GNSS interference monitoring from scientific exploration and technical validation to commercial operation. Second, it presents interference detection technologies based on the observation-domain, frequency-domain, and correlation-domain methods, with increasing integration of artificial intelligence (AI)-based approaches. Furthermore, it analyzes interference source localization methods based on time-difference-of-arrival (TDOA), frequency-difference-of-arrival (FDOA), Doppler-based localization, GNSS radio occultation (GNSS-RO), and GNSS reflectometry (GNSS-R). Finally, the paper proposes a space-based GNSS interference monitoring architecture, comprising the space sensing layer, intelligent processing layer, and application service layer. It also analyzes key technical challenges and future development directions, providing support for the construction of an intelligent space-based monitoring system for global PNT security assurance.