In Europe and elsewhere an increasing number of Ku-band TV satellites are approaching the end of their lives. Limiting the station, keeping strategy to east-west control can significantly extend the operational life of the satellite. This will, however, result in an inclined orbit with an inclination angle rate of approximately 0.4 degrees per year. These satellites are obviously not very useful for general TV broadcasting, where millions of users are equipped with fixed pointing antennas.
Studies are ongoing about cost-effective solutions, how to track those satellites in inclined orbits to extend the commercial exploitation of satellites which are close to or even beyond their design life. One approach is to consider new transmission schemes and applications in a mobile environment, where antenna tracking is anyway necessary, because of the movement of a mobile terminal.
The objective of the study was to investigate the subject of land-mobile Ku-Band services via satellite and to develop a technically and economically feasible system concept. All areas from service aspects, transmission aspects for this specific channel and system implementation aspects had to be covered, in order to create a basis for a system implementation project.
Appropriate services, tailored to the users need and matching the technical parameters of the envisaged system, are one of the key issues for a successful implementation of a mobile Ku-band system. A careful market survey on type and technical characteristics of mobile services and the communications systems already available to the user community have been carried out.
Taken into account said services as well as transmission aspects regarding a mobile ku-band channel and system implementation aspects a both technically and economically feasible system concept has been developed.
The final result of the study is an outline of a development plan showing time and costs for realisation of a system demonstrator.
The main benefits of the study are:
- Provision of appropriate services
- Provision of in-vehicle architecture
- Provision of appropriate antenna design
- Provision of possible transmission scheme
- Outline of development plan for a demonstrator.
The envisaged system studied in the frame of this project is a car mounted mobile terminal, which is suitable to receive dedicated signals from standard Ku-band broadcast satellites. The antenna is a small flat patch antenna, which is electronically steerable and can track broadcasting satellites, even if they are at end of life and not fully stabilised anymore. The user terminal design will need specific signal spreading, coding and interleaving equipment, suitable to mitigate the effects of a mobile Ku-band channel, which is characterised by frequent signal interruptions of various lengths. Such a system can potentially provide several attractive services like radio broadcasting and data casting with local caching of relevant information for the user. These services could be provided on a European wide scale at very low transmission cost, because end of life satellites can be used. The study investigated the feasibility of such a system considering the service aspects, channel investigations and corresponding countermeasure equipment and ultimately a definition of critical items, which need to be developed.
It has been shown, that a service to land-mobile users with a 19 dBi antenna, roughly equivalent to a 10 x 10 cm antenna, is a viable option and a system can be designed, delivering reliably data rates in the region of 1 Mbit/s. The following figure gives an overview of the proposed system.
The study has been completed.
The study has been successfully completed end of 2002. The ITT for developing a demonstrator is expected to be issued in the first quarter of 2003.