Computer Networks and ISDN Systems
Multimedia systems based on satellite technology
Introduction
Satellite communications have a great advantage over any other communication network whenever the information is targeted to a large population of receivers or when they are spread over big areas. That is the reason why they are specially suitable for the provision of multimedia applications like Tele-education and Tele-conferencing.
In this work we present the architecture of multimedia systems based on satellite. We focus especially on architectures based on satellite broadcast and terrestrial return paths. The case of digital TV technology is studied in more detail.
The digital TV technology was designed to target a huge market. Therefore, its cost will benefit from economics of scale, allowing the use of low cost equipment (compared to the cost of traditional VSAT (Very Small Aperture Terminal) [1]equipment). Furthermore, the integration with other services available in the digital platform (sharing the satellite link) is an added value to this solution.
Section snippets
VSAT networks
The main characteristic of communication systems using satellite technology, compared with traditional terrestrial networks, is the ability of broadcasting, the capability to transmit a message to a large number of destinations that may be spread over a broad area. The transmission costs are independent from both the number of receivers and its geographical distribution [1].
Most of the satellite networks deployed through the past years are based on VSAT technology. VSAT networks are generally
VSAT-based multimedia systems
There are several examples of VSAT networks supporting multimedia applications that benefit from the broadcasting capabilities of satellite technology. As an example we will examine the CODE VSAT network [2].
The CODE network was a joint development of the Department of Telematic Systems Engineering of the Technical University of Madrid and Telefónica Sistemas de Satélites, under contract of the European Space Agency. It has been used to support many Tele-education projects, like TEN (Telematics
VSAT-based multimedia systems with terrestrial return channel
As we mentioned above, the use of terrestrial links (like the Integrated Services Digital Network, ISDN) instead of satellite inbound channels allows the design of receive-only VSAT stations. The return channel is provided through an ISDN basic access (two B-channels, 64+64 kbps) so a better quality can be provided in the communication from student to teacher. The only concern with this solution is the availability of an ISDN access due to geographic issues or underdeveloped regions.
In this
Multimedia systems based on satellite digital TV technology
The Hughes system proves that the key aspect in the development of a cost-effective satellite based multimedia service is the use of a low-cost mass-market production technology. Another technology that fits very well with that rule is the newly designed digital TV platforms, based on satellite broadcasting.
Digital TV via satellite allows the transmission of different programmes over a multiplexed transport stream. The stream is composed of several audio and video flows. Furthermore, other
Conclusions
In this paper we have studied different satellite architectures to support multimedia services. We focused on those services with strong requirements of broadcast or multicast, like Tele-education. A case study based on the TEN Tele-education system has been presented. Several architectures have been examined, each with lower cost and greater possibilities than the previous one. The final one, expected to play a major role in the near future, makes use of a low cost technology such as digital
Francisco Javier Ruiz Piñar received a degree in Telecommunication Engineering in 1990 and the Ph.D. degree in Telecommunication Engineering in 1994. He is Associate Professor of the Department of Telematic Systems Engineering (DIT) of the Madrid Technical University (UPM). Since 1990 he has been involved in R&D activities related to the following topics: software design, protocol design and satellite communications.
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Cited by (0)
Francisco Javier Ruiz Piñar received a degree in Telecommunication Engineering in 1990 and the Ph.D. degree in Telecommunication Engineering in 1994. He is Associate Professor of the Department of Telematic Systems Engineering (DIT) of the Madrid Technical University (UPM). Since 1990 he has been involved in R&D activities related to the following topics: software design, protocol design and satellite communications.
Angel Fernández del Campo received a degree in Telecommunication Engineering in 1979 and the Ph.D. degree in Telecommunication Engineering in 1987. He is Associate Professor of the Department of Telematic Systems Engineering (DIT) of the Madrid Technical University (UPM). Since 1979 he has been involved in R&D activities related to the following topics: software design, software engineering, digital transmission, data communication, local and metropolitan networks, formal description techniques and parallel architectures for communication equipments. He has given courses, conferences, authored about twenty publications on national and international magazines and congress, and one book.
Carlos Miguel Nieto received a degree in Telecommunication Engineering in 1986 and the Ph.D. degree in Telecommunication Engineering in 1991. He is an Associate Professor of the Department of Telematic Systems Engineering (DIT) of the of the Madrid Technical University (UPM). Since 1986 he has been involved in R&D activities related to the following topics: software design, software engineering, digital transmission, data communication, local and metropolitan networks, formal description techniques and parallel architectures for communication equipments.
León Vidaller Sisó received a degree in Telecommunication Engineering in 1974 and the Ph.D. degree in Telecommunication Engineering in 1977. He is Professor of the Department of Telematic Systems Engineering (DIT) of the Madrid Technical University (UPM). Since 1974 he has been involved in R&D activities related to the following topics: electronic design, analog and digital transmission, error correcting codes, data communication, local and metropolitan networks, criptography and security. He has been project leader of more than 16 industry and public supported contracts. He is an industry consultant on data communications systems, and book reviewer for IEEE Communication Magazine. He has given courses, conferences, authored about fifty publications on national and international magazines and congress, and four books.
Antonio Martı́nez Mas received a degree in Telecommunication Engineering in 1984 and the Ph.D degree in Telecommunication Engineering in 1989. He is an Associate Professor of the Department of Telematic Systems Engineering (DIT) of the Madrid Technical University (UPM). Since 1984 he has been involved in R&D activities related to the following topics: electronic design, analog and digital transmission, integrated communication, local and metropolitan area networks, performance of multiple access protocols. His current interest includes high speed data networks, multiple access and protocol simulation.
Juan Antonio Carral Pelayo received a degree in Telecommunication Engineering in 1993. He is a research assistant at the Department of Telematic Systems Engineering (DIT) of the Technical University of Madrid (UPM). Since 1992 he has been involved in R&D activities related to the following topics: high speed networking, multimedia systems and digital TV.