The ESA SISNeT Project: Current Status and Future Plans

Likewise other Satellite Based Augmentation Systems (SBAS), EGNOS– the European SBAS – will broadcast augmentation signals for GPS through Geostationary Earth Orbit (GEO) satellites. GEO broadcasting is proved to be an efficient strategy for avionic applications and other modes of transport. For some applications, though, it may be of interest to complement GEO broadcasting through other transmission means. For instance, building obstacles in cities or rural canyons may difficult the GEO reception. In those situations, complementary real-time Internet-based broadcasting of the EGNOS signal is of major interest as a way to continue taking the most of the EGNOS potential, irrespectively of the user environment. This is a well known problem for which the ESA SISNeT technology has proved to be an excellent solution. SISNeT is a service developed by the European Space Agency (ESA) (a work led by the authors of this paper) in 2001, which allows retrieving the EGNOS messages across the Internet in realtime, usually employing wireless networks like GSM or GPRS. In case of low visibility of the GEO satellites, users can continue taking the most of the EGNOS potential, via SISNeT. In the early days of SISNeT, advanced simulation activities revealed that the combination of EGNOS and the almost unlimited capabilities of the Internet could open the door to a lot of innovative applications for Satellite Navigation. The evolution of SISNeT and related applications in 2001 – 2006 has demonstrated and justified what simulations were anticipating. To the authors and ESA satisfaction, SISNeT is today a consolidated technology, used widely in Europe and outside as the SBAS Internet service provision standard protocol. This has been achieved mainly thanks to: • The internal ESA work on SISNeT. • The launch of a number of ESA contracts with European industry, on SISNeT developments. • The consideration of the SISNeT technology in numerous ESA and GJU projects. • The consideration of the SISNeT technology in state-of-the-art commercial simulation tools. • The interest of worldwide companies, organisations and universities on applying SISNeT to a large variety of applications, research and development projects. • The implementation of SISNeT technology in commercial SBAS receivers. • The excellent performances obtained with the pair EGNOS/SISNeT. • The pragmatic conception of the SISNeT technology concept that allows an easy adaptation of general SBAS receivers to use SISNeT. • The International recognition of the SISNeT concept with several International prestigious awards. Several new application fields based on SISNeT have been identified, like educational applications, help to impaired people, support to tourism, quick initialisation of SBAS receivers, etc. The possibilities of SISNET have indeed revealed to be beyond ESA initial expectations. This paper will present the most updated status of the SISNeT Project, introducing the new version 3.1 of the SISNeT platform (to be available in May / June 2006), which includes several new features, based on feedback from users and developed applications. The EGNOS Message Server (EMS), a non-real time complement to the SISNeT concept, will be shortly presented in this paper. In addition, the paper will include an outlook to the future of this ESA technology and its link with the EGNOS Data Access System (EDAS), which will allow the provision of EGNOS commercial services in 2006. The Authors firmly believe that SISNeT, as a solid synergy between SBAS systems and the Internet will continue opening new doors to innovative developments and will become a mature technology as an integral part of the EGNOS system, through the EGNOS Data Access System concept.