Positioning With LEO Satellites as Signals of Opportunity (SoOP): A Survey

Positioning is a critical service for modern societies, supporting many sectors including transportation, logistics, and agriculture. As reliance on accurate positioning continues to grow, the vulnerabilities of Global Navigation Satellite Systems (GNSSs) to jamming and spoofing pose significant concerns. The low Earth orbit (LEO) satellite with high velocity and signal power is a robust and independent alternative. LEO communication signals are regarded as Signals of OPportunity (SoOP) for positioning. LEO SoOP positioning has flourished recently. This survey offers a comprehensive overview of the LEO SoOP positioning, presenting an in-depth review of the current literature. It evaluates the whole process of LEO SoOP positioning, including LEO constellations, instruments, signal processing, measurement sources, error corrections, positioning algorithms, and performance analysis. Furthermore, the survey explores the state-of-the-art strategies to improve positioning performance, such as multiepoch Integration, multiconstellation combination, base station auxiliary, and multisensor fusion. Finally, it outlines challenges and future research.