LEO enhanced GPS, Galileo, and BDS-3 based on regional augmented undifferenced and uncombined PPP-AR

Abstract This study developed a low-Earth orbit (LEO) enhanced GPS, Galileo, and Beidou-3 navigation satellite system positioning using an undifferenced and uncombined (UDUC) precise point positioning-ambiguity resolution (PPP-AR) model, evaluating its performance over 7575 km and 145 km reference networks. Atmospheric delays were interpolated from reference stations to users via the modified linear combined model (MLCM) to constrain the UDUC PPP. The results demonstrate that, in both static and kinematic positioning, LEO satellites significantly enhance positioning and AR performance, notably improving convergence speed. While regional atmospheric delay augmentation also yields significant gains, its efficacy decreases with larger network scales, leading the 145 km network to underperform the 75 km network. The study concludes that LEO enhancement combined with atmospheric delay constraints is a powerful tool for high-precision positioning, with network scale being also a factor for optimal performance This study presents the first comprehensive evaluation of the synergistic effects between LEO fixed solutions enhancement and regional atmospheric delay constraints in UDUC static and kinematic PPP-AR, providing novel insights for network scale optimization.