True broadband access for Thalys high-speed train passengers travelling between Paris, Brussels, Amsterdam and Cologne is now available, representing a great technological achievement - establishing a continuous, two-way link between a train travelling at 300 km/h and a satellite at an altitude of 36 000 km. This is a commercial application of work begun by ESA's Broadband to Trains initiative.

'Thalysnet' is the commercial name of this application, officially launched on 14 May. It was developed by a consortium lead by Nokia Siemens Networks, which combines satellite communications with conventional wireless data technologies to provide a continuous Internet connection on board trains travelling across national borders at 300 km/h. One of the companies in the consortium is the UK-based 21Net, which carried out a pilot project in 2005 under the European Space Agency's Broadband to Trains initiative.
 
21Net worked with leading railway operators such as RENFE (Spain) and SNCF (France), along with Thalys, to develop a solution combining bi-directional satellite communications with terrestrial wireless technologies. Its Broadband to Trains system is a robust and technically mature system that complies with railway standards. Tests were conducted by Thalys, which provided an experimental Internet service on trains between Paris, Brussels and Amsterdam. These tests proved the system designed by 21Net was workable, and passengers showed considerable interest in the service.

The 21Net system architecture is based on two-way Ku-band satellite system to provide connectivity between the Internet backbone and a master server on the train. A hub station provides the connection from the Internet backbone (and from the network operations centre) via the satellite directly to a low-profile tracking antenna on the train.
 
Terrestrial wireless access between the train and available networks is also provided when the satellite connection may be obstructed, such as when travelling through tunnels.
 
21Net has mastered the use of a unique mobile satellite modem to share the satellite bandwidth across all the trains in the fleet, allocating bandwidth on demand according to the usage level on the train. With the 21Net system, satellite bandwidth scales linearly with Internet use.
 
The use of two-way Ku-band satellite transmission enables 21Net to deliver high bandwidth (2 Mbit/s by 512 kbit/s) connectivity to the train, which can be shared by multiple, simultaneous users.
 
Currently six trains in the Thalys fleet are equipped with Thalysnet. The complete fleet, 26 trains in total, will be equipped by October 2008.