Doppler-Based Positioning with LEO Satellites: A Survey of Techniques, Challenges, and Opportunities

The advent of Low Earth Orbit (LEO) satellite constellations, such as Starlink and OneWeb, has introduced new possibilities for global positioning, navigation, and timing (PNT) services. LEO satellites, operating at altitudes between 500 km and 2,000 km, offer advantages such as reduced signal latency, stronger signal strength, and more frequent satellite visibility compared to traditional Global Navigation Satellite Systems (GNSS). Among the various positioning techniques, Dopplerbased positioning has emerged as a promising alternative or complement to GNSS, leveraging the Doppler shift caused by the relative motion between the satellite and receiver. This survey provides a comprehensive review of Doppler-based positioning techniques using LEO satellites, tracing their historical development and examining both single-satellite and multi-satellite methods. Additionally, it explores the challenges and opportunities inherent in using LEO signals for Doppler-based positioning. The paper also highlights recent advancements in the field, including innovative algorithms and the potential for real-time applications.