Comparative analysis of GNSS reliability: GPS, GALILEO and combined GPS-GALILEO

Global navigation satellite systems (GNSS) is the collective term for those navigation systems that provide the user with a three-dimensional positioning solution by passive ranging using radio signals transmitted by satellites. The most well known is the Navigation by Satellite Ranging and Timing (NAVSTAR) Global Positioning System (GPS). It is the most advanced but still not free from erroneous positioning and needs better accuracy. Now European GALILEO is under development, which is interoperable with GPS. In this paper performance of GPS and GALILEO alone and combined GPS-GALILEO system has been analyzed. Simulation has also done using duel and triple frequency. This paper has also presented which system and combination gives better precision and reliability. Also a time analysis of getting highest availability is studied. Results show that the improvement of the combined system is as high as 50% as present GPS alone system.