Improved Integrity Concept for Future GNSS Evolutions

C. Catalán, C. Hernández, A. Mozo, L. Fernández, F. Amarill

Abstract:	This paper presents an evolution of the Galileo Integrity Concept, GIC, in which the SISA and SISMA concepts are evolved from scalar to matrix magnitudes. Currently, both SISA and SISMA are scalar quantities that have to be valid for all users within the satellite coverage area. Therefore, they are computed for the socalled worst user location, WUL. In fact, the WUL for SISA may not be the same one as for the SISMA. Furthermore, there is no user at the WUL for all satellites at the same time. This approach implies that real users are bound to use SISA and SISMA values greater than needed. In the end, an integrity service may not be available at one particular moment due to the fact of using too pessimistic SISA and SISMA values. This paper presents a formulation of the GIC in which SISA and SISMA evolve toward 3x3 matrices so that every user can project the equivalent SISA and SISMA to his own position. The paper also presents the algorithms that Ground Segment facilities would use to compute these matrices.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	2547 - 2557
Cite this article:	Catalán, C., Hernández, C., Mozo, A., Fernández, L., Amarill, F., "Improved Integrity Concept for Future GNSS Evolutions," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 2547-2557.
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