Enhancing PPP Convergence Performance with LEO Augmentation: Scenario-Based Analysis with Real GNSS Data

Hyunwoo Kim, Yongrae Jo, Hyunjin Joo, Byungwoon Park

Abstract:	Low Earth Orbit (LEO) satellites have recently gained attention as a promising complement to Global Navigation Satellites System (GNSS) for Positioning, Navigation, and Timing (PNT) applications. Unlike traditional Medium Earth Orbit (MEO) GNSS satellites, LEO satellites operate at much lower altitudes, typically between 500 and 2,000 km. This lower altitude enables stronger signal power at the receiver, reduced propagation delays, and faster variations in satellite-receiver geometry. These characteristics, when integrated with GNSS, can increase satellite visibility, improve positioning accuracy, and notably shorten convergence times in high-precision positioning. Among existing positioning techniques, Precise Point Positioning (PPP), which achieves centimeter-level accuracy using a single receiver, is expected to benefit most from LEO augmentation. PPP is an absolute positioning technique in which a user combines raw GNSS measurements with precise satellite orbit and clock information obtained from an external augmentation service. By forming ionosphere-free linear combinations of dual-frequency code and carrier-phase observations, ionospheric errors are effectively mitigated. Additional parameters, including tropospheric delays, receiver clock offsets, carrier-phase ambiguities, and three-dimensional user position, are then estimated simultaneously using Kalman filter framework. Due to the large number of correlated parameters and the relatively slow temporal evolution of satellite-receiver geometry in GNSS-only PPP, convergence typically requires 20-30 minutes or more, which limits its practical real-time application. This study investigates the impact of integrating LEO satellites on PPP convergence by leveraging their rapidly changing orbital geometry. Unlike previous studies that often relied on fully simulated GNSS and LEO measurements, our approach utilized actual GNSS observation data to capture realistic tropospheric and receiver clock characteristics. Tropospheric delays and receiver clock errors were first estimated through preliminary PPP processing of real GNSS measurements. These estimates were applied when generating simulated LEO measurements, ensuring that the hybrid dataset preserved realistic atmospheric effects, clock behaviors, and observation noise. By combining actual GNSS data with these simulated LEO measurements, we constructed a dataset that realistically represents the integrated GNSS/LEO observation environment. To systematically evaluate the effect of individual LEO satellites on PPP performance, satellites were introduced one at a time based on their orbital parameters, rather than adding a full constellation simultaneously. PPP performance was assessed using convergence criteria consistent with the Galileo High Accuracy Service (HAS) standard, satisfying horizontal positioning errors below 20 cm and vertical errors below 30 cm; for this study, a criterion of maintaining this continuously for at least one hour was used. Convergence behavior was analyzed separately along the east, north, and up components to account for directional variations in satellite geometry influence. Results demonstrate that adding LEO satellites substantially reduces PPP convergence time, with an observed improvement of approximately 70% relative to GNSS-only solutions. Convergence rates also varied along the east, north, and up directions depending on the orbital characteristics of each LEO satellite. These results indicate that even a small number of strategically deployed LEO satellites can provide significant augmentation benefits, accelerating real-time high-precision positioning before a full LEO constellation is deployed. This study highlights the practical potential of GNSS/LEO integration and provides a methodology for realistically simulating LEO measurements using actual GNSS data for future PPP performance assessments.
Published in:	Proceedings of the ION 2026 Pacific PNT Meeting April 13 - 16, 2026 Hilton Waikiki Beach Honolulu, Hawaii
Pages:	694 - 699
Cite this article:	Kim, Hyunwoo, Jo, Yongrae, Joo, Hyunjin, Park, Byungwoon, "Enhancing PPP Convergence Performance with LEO Augmentation: Scenario-Based Analysis with Real GNSS Data," Proceedings of the ION 2026 Pacific PNT Meeting, Honolulu, Hawaii, April 2026, pp. 694-699. https://doi.org/10.33012/2026.20574
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