SISNET

EGNOS
Title	SISNET
Author(s)	GMV.
Level	Basic
Year of Publication	2011

EGNOS broadcasts 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.

Responding to that need, ESA developed and launched the SISNeT service in 2002. SISNeT allows retrieving the EGNOS messages across the Internet in real-time, usually through wireless networks, like GSM or GPRS. Thanks to SISNeT, any user with access to the Internet (e.g. through wireless networks – GSM or GPRS –) may access the EGNOS product, irrespectively of the GEO visibility conditions.

SISNeT Advantages

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 to the date has demonstrated and justified what simulations were anticipating, mainly thanks to:

• The launch of a number of ESA contracts with European industry, on SISNeT developments.
• The interest of worldwide companies, organisations and universities on applying SISNeT to a large variety of applications, research and development projects.
• The ESA internal work on SISNeT.

In fact, new application fields based on SISNeT have been identified, like educational applications, help to impaired people, quick initialisation of SBAS receivers, etc. The possibilities of SISNeT have revealed to be beyond ESA initial expectations.

Current SISNeT Status

For a wide range of EGNOS applications 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 means of broadcasting (e.g. FM, Digital Audio Broadcasting – DAB – and the Internet) have a remarkable interest. In this context, the European Space Agency (ESA) launched an internal project to provide access to the EGNOS messages in real time through the Internet. The product of this project has been a new technology, called SISNeT (Signal in Space through the Internet), whose interest has greatly grown since the initial SISNet service was put in place by ESA in 2001.