Enhanced Protection Level Based on Non-Gaussian Models with an Application to RTK Precise Positioning

Yuting Gao, Jiakun Li, Baoyu Liu, Yang Jiang, and Yang Gao

Peer Reviewed

Abstract:	With the deepening application of Global Navigation Satellite Systems (GNSS) in safety-critical domains, the importance of integrity monitoring has become increasingly prominent. Lack of integrity compromises the availability and reliability of GNSS systems, and can even affect safety in areas such as aviation and autonomous driving. This research focuses on Real-Time Kinematic (RTK) carrier-phase differential positioning technology and proposes a protection level calculation method based on the Student's t-distribution. By analyzing the characteristics of GNSS positioning errors, we point out that the traditional Gaussian distribution model has idealized limitations due to its neglect of tail risks. To address this limitation, this study employs the Student's t-distribution, characterized by its heavy-tailed properties, for error modeling to more accurately characterize the occurrence probability of extreme error events. Building on this model, we utilize the Student's t-distribution based protection level calculation method, specifically investigating the selection of the degrees of freedom(DOF) parameter for protection level (PL) in both the RTK fixed solution and RTK float solution scenarios. The study demonstrates that within the Student's t-distribution based protection level framework, the degrees of freedom parameter influences the magnitude of the protection level value. Under a given target integrity risk condition, the selection strategy for degrees of freedom exhibits consistent characteristics for both RTK fixed and float solutions.
Published in:	Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025) September 8 - 12, 2025 Hilton Baltimore Inner Harbor Baltimore, Maryland
Pages:	2513 - 2523
Cite this article:	Gao, Yuting, Li, Jiakun, Liu, Baoyu, Jiang, Yang, Gao, Yang, "Enhanced Protection Level Based on Non-Gaussian Models with an Application to RTK Precise Positioning," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 2513-2523. https://doi.org/10.33012/2025.20337
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