GPS and GALILEO Interoperability and Synergies

Arian Leonard, Helmut Blomenhofer and Isabel Izquierdo

Abstract:	This paper is based upon work conducted within the EC and ESA funded Galileo Studies. The views expressed are the opinions of the authors and do not reflect EC/ESA policy. The co-existence of Galileo with GPS and other systems without interference is the minimum requirement that has to be realised in the Galileo design. However, the full range of user benefits can be achieved, once Galileo is used either alternatively or in combination with GPS and/or other systems. This paper reflects the current status and results of the Interoperability study within the EC Galilei contract. Considering the different needs for "Interoperability" and "Compatibility" of GNSS systems, a wide variety of definitions and interpretations are encountered within different communities and applications. Coherent identification and consistent analysis of interoperability issues hence require a common denominator, serving as platform for in-depth assessments independently of the differences between definitions and applications. Hence, a common reference frame was created, which has facilitated the analysis of interoperability issues to address specific needs of the different areas of application. The alternative use of GPS and GALILEO is considered to address the advantages of having redundant systems. In addition, expected synergies and user benefits are demonstrated taking advantage of both satellite constellations in combination. Regarding personal user and land mobile applications, the potential combination of data from different signal sources represents a major opportunity for assistance and enhancement of positioning solutions, e.g. in case of satellite masking in urban environments. The benefits in terms of accuracy and availability improvements, especially in urban areas, using simultaneously Galileo and GPS represent a major advantage. In addition to accuracy and availability, the integrity and continuity of service are major design drivers in Safety of Life Applications. The provision of autonomous signals by the two independent satellite constellations as well as their potential combination at receiver level will largely benefit redundancy, e.g. in applications requiring fail safe or safe operational systems. The integrity monitoring of the satellite signals using RAIM techniques is strongly improved using both constellations. Therefore, RAIM availability and outages of combined GPS and Galileo are compared with GPS or Galileo only. A further major study topic is the investigation of the Galileo interoperability and complementary use with telecommunication systems. The rapid evolution of these telecommunication systems will possibly allow both positioning and dissemination of large data streams. The interoperability and complementary use of these telecommunication systems with both GPS and GALILEO is investigated with respect to common synergy objectives.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	330 - 341
Cite this article:	Leonard, Arian, Blomenhofer, Helmut, Izquierdo, Isabel, "GPS and GALILEO Interoperability and Synergies," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 330-341.
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