PAGE CONTENTS
Objectives
This project is aimed at designing, implementing and validating a mobile VSAT system at Ku-band to provide passengers of high speed trains with broadband access to the Internet.
This satellite communications system is addressed at covering the growing need from people to be always ‘connected’ to the Internet, even when away from home or the office, by providing continuous mobile broadband services where terrestrial infrastructures are not available.
For this purpose, the project is intended to offer a system which:
- is available along most or all of the railway track,
- is adapted to the railway environment, covering specific norms and regulations, and stringent mechanical and EMC requirements,
- has enough bandwidth to deliver video contents, e-mail and internet browsing to passengers or to provide railway operators with reliable communications in remote areas, and
- is a system able to integrate with broadband terrestrial networks whenever they are available.
Challenges
The key issues to be addressed in the project will be focused on the more critical return link components, such as:
- The Mobile Terminal Station(MTS) low-profile antenna, to be allocated in a reduced space under a coach roof fulfilling train mechanical constraints.
- The stabilizer platform, to follow specific train movements reducing maximum satellite off-axis permitted EIRP.
- The CDMA VSAT base-band modem signal acquisition and synchronization algorithms adaptation for the feeder/mobile links, and review of MAC/DLC satellite protocols of to keep data traffic QoS in the severe electromagnetic wave propagation channel scenario experienced by trains.
Plan
The project started at the beginning of August 2005 with a first phase to be concluded in October 2005 with the Baseline Design Review. The Critical Design Review, the first milestone of the second phase, is foreseen in January 2006. Final trials on high speed trains are planned in January-February 2006. The Final Review of the project is expected in September 2006.
Current Status
In June 2006 the Mobile Terminal Station (MTS) was installed in an S-100 Alstom AVE laboratory coach (see also picture below).
The MTS consisted of:
- an outdoor unit based on antenna, radome, azimuth and elevation motors, and RF equipment, and
- an indoor unit based on CDMA/DVB modems, a switching router and ACU equipment.
The results reached during the mobility tests campaign performed on 20th of June 2006 on the route Madrid – Sevilla were of great value: the behaviour of the propagation channel in the real railway environment was measured, the antenna tracking system behaviour in curves was improved even though it became necessary to enhance the tuning further, and the behaviour of the access control and synchronization of CDMA/DVB modems was evaluated.
Since September 2006, Indra is working to integrate a newly developed multi-waveform software-radio modem with the current project. This new modem platform incorporates mobility improvements as well as the results of the real trials performed in the past. A 2nd opportunity to validate this solution in a real train environment is planned for mid of September 2007 on the RENFE laboratory coach. The project conclusion is expected by end September 2007.
