SBAS Equations with Complementary Conditions in Galileo

F. Amarillo, P. D'Angelo

Abstract:	This paper describes a simplified methodology for the evaluation of integrity risk for a Galileo user based on the usage of the conventional SBAS protection level equations complemented with a number of additional conditions. The equations for the computation of overall integrity risk are not directly implemented but only used to define “a priori” the conditions that guarantee integrity requirements for specific applications. In this paper it is demonstrated that a very limited set of conditions on the user geometry and on the magnitude of the navigation and integrity data qualifiers is sufficient to confirm whether the user is in a safe situation when replacing the SBAS Signal-In-Space integrity indicators (UDRE + IF) by the Galileo Signal-In-Space integrity indicators (SISA + IF) in the SBAS equations. Due to the simplifications introduced in the definition of the method, there could be safe situations that the equivalent conditions are not able to confirm, and therefore the presented method penalizes the maximum achievable service availability for the applications. The severity and relevance of this penalization depends on the application and can be evaluated through numerical simulations. Test results demonstrate that the penalization of the proposed simplified methodology is very small for a number of civil aviation approach operations (e.g. APVI). The paper will explain extensively: • The logical steps to define the complementary conditions, which together with the SBAS protection levels equations guarantee the fulfillment of the overall integrity risk specification when using Galileo. • The characteristics of the specifications of the possible application domains for the proposed methodology. • The results of all the extensive numerical analyses performed to evaluate the availability for a number of civil aviation approach operations (e.g. APV-I) based on the computed protection limits and on the fulfillment of the complementary conditions.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	2832 - 2838
Cite this article:	Amarillo, F., D'Angelo, P., "SBAS Equations with Complementary Conditions in Galileo," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 2832-2838.
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