Transition Phase for a New Navigation System Based on a Constellation of LEO Satellites

Abstract

The Global Navigation Satellite System (GNSS) is strongly dependent on the choice of the satellite constellation. At the present time, the GNSS space segment is made by the following satellite constellations: GPS, GLONASS and a set of geostationary satellites. In a medium-long term future, a new GNSS could substitute the existing satellite navigation system, or, in any way, there will be an overlapping and an integration between the current system and the next one.Alenia Aerospazio, is studying, since 1990, the possibility to identify new navigation satellite constellations able to verify the Required Navigation Performance (RNP) for all users. Particular attention has been focused on airspace users, due to the fact that the accuracy requirements during the aircraft landing phases are very stringent, and the existing GPS system is not able to guarantee the desired RNP.In this paper a new satellite constellation with 75 satellites in Low Earth Orbit (LEO) at a common altitude of 2700 Km, and a common inclination of about 66°, has been identified. It is able to comply with the RNP (i.e. accuracy, availability, continuity, and integrity) up to CAT I landing.The transition phase between the co-existence of the current GNSS space segment and the evolving LEO constellation is discussed and analysed in this paper, outlining the advantages, with respect to the previous system, coming from the progressive implementation, in a step-wise fashion, of this LEO space segment, until its completion.KeywordsGlobal Navigation Satellite SystemGlobal Navigation Satellite SystemOrbital PlaneTime PercentageSatellite ConstellationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.