Galileo Integrity Support Message Bounding Methodology Using Extreme Value Theory

Julie Antic, Santiato Perea, Miguel Odriozola, Stefan Wallner Matteo Sgammini, Juan Pablo Boyero

Peer Reviewed

Abstract:	The on-going evolutions of GPS and Galileo constellations will improve the performance of Advanced Receiver Autonomous Integrity Monitoring (ARAIM). Even if ARAIM users have the capabilities to detect and exclude faulty satellites at airbone level, they rely on the GNSS service providers for the generation and broadcasting of the Integrity Support Message (ISM) that provides the parameters to conservatively model the Signal In Space Error (SISE) in the ARAIM algorithm. For Galileo, the service facility in charge of this function is the ISM Generator (ISMG). One of the challenges faced by the ISMG is the determination of Psat, that is the probability for a satellite fault, because a fault is so rare that several years are generally necessary to observe it. Previous works circumvent this lack of observability by the aggregation of service history over all satellites. Such aggregation assumes that the SISE distribution is similar for all satellites. While this assumption is valid for all Galileo First Generation (G1G) satellites, it may be difficult to guarantee that the satellites from the Galileo Second Generation (G2G) will have the same distribution as G1G satellites. Consequently, it seems relevant to broadcast different Psat for G1G and G2G satellites, as permitted by the grouping capability of the Galileo ISM format. For this purpose, the ISMG shall be able to derive Psat with the limited G2G service history that will be acquired progressively after the first launches. This is where the challenge arises and is the topic of the article. More precisely, the article proposes a new method for Psat determination that copes with the limited availability of historical data thanks to extreme value theory and a Bayesian prior based on past performances. The method is precisely justified and illustrated on real G1G data.
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:	1451 - 1464
Cite this article:	Antic, Julie, Perea, Santiato, Odriozola, Miguel, Sgammini, Stefan Wallner Matteo, Boyero, Juan Pablo, "Galileo Integrity Support Message Bounding Methodology Using Extreme Value Theory," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 1451-1464. https://doi.org/10.33012/2025.20242
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