On EGNOS and WAAS Performance

I. Alcantarilla, N. Zarraoa, J. Caro

Abstract:	"GPS and GLONASS have revolutionised the navigation world. They have opened new opportunities for all activities requiring a high precision positioning. It was as early as 1991, during the 10th Air Navigation Conference, that ICAO recognised the capabilities of this new navigation technology for the Civil Aviation world. The Global Navigation Satellite System (GNSS) was then launched as a cornerstone for the future development of the civil aviation. Being the navigation inside the civil aviation a safety of life application, not only the positioning accuracy was requested by ICAO but also other essential performances as integrity, availability and continuity. USA answered the GNSS initiative by starting the Wide Area Augmentation System (WAAS). WAAS looks for broadcasting information that complements the GPS to achieve the GNSS required performance. Europe, realising the cornerstone character of the positioning technology in the future, has started a two-folded program. First, the European Geostationary Navigation Overlay Service (EGNOS), an augmentation system for GPS and GLONASS to achieve the GNSS performances, started as early as 1996 and is currently in its final System Validation Phase. Second, a new navigation constellation, Galileo, will be deployed by 2008. Galileo will provide the independence of Europe in satellite navigation. This paper will present the current EGNOS Signal In Space (SIS) performances measured both at the level of the broadcast information and at user level. The results will also include a comparative between the EGNOS SIS and the already operational WAAS. The proposed analyses will be based on the tools that are currently being used for the validation of the EGNOS system and will be focused mainly on two different subjects: 1. Integrity, availability, continuity and accuracy of the broadcast EGNOS/WAAS signals (measurement domain). 2. User position solution performance in terms of protection levels vs. navigation errors (position domain). Results will show that both EGNOS and WAAS will provide similar navigation performances with slight differences between both systems. EGNOS currently provides a better availability due to lower UDREs and GIVEs (boundings of the SV and ionospheric errors) while WAAS provides a higher integrity margin. Accuracy in both systems are similar."
Published in:	Proceedings of the 61st Annual Meeting of The Institute of Navigation (2005) June 27 - 29, 2005 Royal Sonesta Hotel Cambridge, MA
Pages:	774 - 782
Cite this article:	Alcantarilla, I., Zarraoa, N., Caro, J., "On EGNOS and WAAS Performance," Proceedings of the 61st Annual Meeting of The Institute of Navigation (2005), Cambridge, MA, June 2005, pp. 774-782.
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