LEO Enhanced Global Navigation Satellite System (LeGNSS): progress, opportunities, and challenges

With the completion of Chinese BeiDou Navigation Satellite System (BDS), world has begun to enjoy Positioning, Navigation, and Timing (PNT) services four Global Systems (GNSS). In order improve GNSS performance expand its applications, Low Earth Orbit (LEO) Enhanced (LeGNSS) is being vigorously advocated. Combined with high-, medium-, low- earth orbit satellites, it can in terms determination, Precise Point Positioning (PPP) convergence time, etc. This paper comprehensively reviews current status LeGNSS, focusing on analyzing advantages challenges for precise clock PPP convergence, rotation parameter estimation, global ionosphere modeling. Thanks fast geometric change brought by LEO LeGNSS expected fundamentally solve problem long time without any augmentation. The be shortened within 1 minute if appropriate constellations are deployed. However, there still some issues overcome, such as optimization constellation well real determination.