Galileo and GPS Differential Integrity Performance for Area Terrestrial Networks

Andreas Schmitz-Peiffer, Marcel Abele, Charles S. Dixon and Russell Morrison

Abstract:	Differential GNSS systems exist since the late 1980s. Depending on the number and density of differential reference stations they allow for the provision of augmented positioning over areas which extend from local to continental size. Wide Area Systems like WAAS and EGNOS monitor the GNSS Signal In Space by ground based reference stations. These systems provide integrity information of the satellite signals and ionosphere corrections to the user receiver. Such information is very important for several applications which have medium integrity requirements. However for several safety of life relevant applications the required integrity performance is so high that local integrity concepts are required. Local integrity means that in addition to satellite clock and ephemeris, also local atmospheric effects can be taken into account. In this paper a concept for the provision of augmented positioning plus local integrity for that positioning accuracy is presented. Integrity is calculated for a larger area based on network information of several reference stations. This is new compared to LAAS integrity, where single reference stations are used. We call it Network Integrity or High Integrity with Area Coverage (HIAC). The work starts with a short review of existing differential GNSS systems followed by an overview of applications, which require high level integrity over a areas, which extend from 60 km to country size. A system architecture is presented. It consists of building blocks for network interpolation, for calculating network integrity and for calculating the integrity risk at the user level. The size of the network and the data being generated, have a strong impact on the selection of the communication technique and on the other integrity parameter the Time To Alert. These aspects are presented. Finally the next steps for the design, implementation and testing of HIAC are outlined.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	1663 - 1673
Cite this article:	Schmitz-Peiffer, Andreas, Abele, Marcel, Dixon, Charles S., Morrison, Russell, "Galileo and GPS Differential Integrity Performance for Area Terrestrial Networks," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 1663-1673.
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