User Level Integrity as an Enabler of GNSS Applications

A.L. Mark, J. Autran, and S. Golmayo

Abstract:	Satellite navigation technology is continually advancing new possibilities in an increasing number of sectors. Applications that were just a dream a few years ago are becoming reality today and the spectrum of potential applications has grown significantly over the last few years. The unprecedented social, economic, technological and environmental benefits to be gained through these applications are becoming very clear. Some of these applications, though theoretically technically possible with the current GPS system, suffer from a number of limitations. The most basic limitation is that some kind of guarantee in two key aspects, service availability and service integrity, is indispensable in many cases. Lack of these guarantees would nullify any confidence in the results and thus jeopardise the validity of these applications. Service integrity is an essential component for the implementation of GNSS safety critical applications such as in civil aviation. However, integrity can also play a fundamental role in the implementation of so-called 'liability critical' applications – applications where GNSS performance problems can generate significant legal or economic consequences (or liabilities) when not properly identified. Galileo will provide a guaranteed level of service to its users, in particular the integrity of the navigation signal - the capability to warn users when navigation errors are larger than pre-specified limits. Similar capabilities are already provided by SBAS like WAAS and EGNOS. Unfortunately, the SBAS and Galileo integrity services do not cover all the links in the integrity chain required to successfully implement liability-critical applications [2]. Particularly, the guarantee of position integrity at the mobile unit level in non-controlled, e.g., urban environments. This is one of the key questions that must be resolved in order to successfully institute liability critical applications. The objective of the ADvantis project was to define a GNSS based system that guarantees service integrity at the client level as applied to road charging applications. This paper presents the results of this project with particular emphasis on the performance in different environments of the ADvantis integrity provision chain. It will be shown how position integrity and availability leads to service (charging) integrity and availability, paving the way for liability critical applications.
Published in:	Proceedings of the 2006 National Technical Meeting of The Institute of Navigation January 18 - 20, 2006 Hyatt Regency Hotel Monterey, CA
Pages:	129 - 140
Cite this article:	Mark, A.L., Autran, J., Golmayo, S., "User Level Integrity as an Enabler of GNSS Applications," Proceedings of the 2006 National Technical Meeting of The Institute of Navigation, Monterey, CA, January 2006, pp. 129-140.
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