Operational Performances Of An Innovative European Navigation System (INES)

V. Thiebolt, F. Zwolska, J.P. Provenzano

Abstract:	The GNSS Program has been initiated to create a global navigation system fulfilling all the needs of the civil aviation community. GNSS1 is already under implementation and consists in an integration between the existing systems (GPS, GLONASS) and a set of geostationary satellites broadcasting a navigation signal with integrity and wide area differential correction data. GNSS2 is intended to be a satellite navigation system controled by civilian organisms, fulfilling in particular ICAO Navigation requirements, with the capability of being certified as a sole means system. GNSS2 will also apply to all kind of users, for transport applications (air, land, maritime) as well as for scientific applications. ALCATEL is presently working on a new navigation satellite concept INES (Innovative European Navigation System) based on the utilization of a LEO constellation completed by the geostationary component of GNSS1. The objective of INES is to achieve users requirements by a progressive implementation : the SIS will provide a basic level of performance (at least equivalent to Civil Aviation NPA requirements with the objective of fulfilling CAT 1 accuracy) and more demanding applications will be reached thanks to ground augmentations and/or specific signal processing techniques. An Innovative aspect of INES is to propose a low cost system with low mass and consumption satellites. This is possible by the use of a localization ground network enabling on board real time orbit determination and synchronization. After a recall of the economical and strategical issues of the new navigation satellite system INES, a survey is made of the main requirements (accuracy, availability) for air transport organizations, which were first used to determine the system. Basic requirements such as precision accuracy performances will first be discussed by taking into account the UERE variation with the elevation of each satellite and the type of constellation. The UERE definition will depend on the propagation delays, ephemeris errors, receiver noise, clock error and multipath errors modeling. We will then discuss the impact of the operational availability on the optimization of navigation constellations and particularly on LEO and GEO satellites constellations, by taking into account single and multiple satellite failures. Operational availability is particularly essential in the choice of the philosophy of redundancy at satellite level and at constellation level and has a great influence on design parameters such as the total number of satellites to produce over the lifetime of the system (nominal and spares satellites) and hence on the space segment definition and launch cost (satellite duration of life and reliability, production rate,..., launcher capability and availability, risk management...). Simulation results will be provided to illustrate the need for operational availability analysis.
Published in:	Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998) June 1 - 3, 1998 The Adams Mark Hotel Denver, CO
Pages:	95 - 102
Cite this article:	Thiebolt, V., Zwolska, F., Provenzano, J.P., "Operational Performances Of An Innovative European Navigation System (INES)," Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998), Denver, CO, June 1998, pp. 95-102.
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