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Contenido archivado el 2022-12-23

INTEGRATED SPACE AND TERRESTRIAL NETWORKS

Objetivo

Summary of objectives

Carrying out research in the area of integration of terrestrial closed and public networks by transparent and future intelligent satellites (with on-board switching and processing), taking into account the relevant earth segment.

Study of problems of internetworking between heterogeneous networks, protocol aspects, network management and control, traffic management techniques and strategies for network evolution.

Study of new transmission and satellite access techniques making efficient use of the satellite capacity.

Definition of suitable gateways between terrestrial and satellite networks, especially for the integration of LANs and ISDN networks by satellite.

Elaboration of a pilot system for integrating terrestrial and satellite networks supporting mixed-media traffic (data, voice, video) and harmonisation with future terrestrial networks and the relevant techniques (e.g. ATM switching).

Demonstration of the advantages of satellites, particularly in areas with a poor telecommunications infrastructure.

Current status

COST 226 finished its work with the final symposium in Budapest in May 1995. The results of the work are summarised as follows : A comprehensive systems definition study for LAN interconnection by satellite, covering the areas of user requirements, protocol issues, local and wide area terrestrial and satellite networks, commercial aspects (e.g. competing systems and tariffs) was carried out. The user requirements study showed that the most important applications are file transfer, data base access and E- mail. Integrated voice and videoconference services are becoming increasingly important. These are applications which can be well supported by satellite systems.

Traffic measurements and analyses revealed the chaotic behaviour of LAN traffic. Multiplexing of different LAN traffic does not improve the situation. This has to be taken into account when designing the demand assignment access scheme.

Since the survey showed that the most widely used protocol is TCP/IP, detailed measurements of the performance of TCP/IP on real and simulated satellite links were carried out followed by a thorough analysis of the results. By optimisation of the protocol parameters (window and buffer size) good throughput can be achieved. Performance measurements were also carried out on a VSAT network in Spain ; these line up well with the theoretical investigations and simulations.

Reference models for LAN and ISDN interconnection by satellite were elaborated using formal description techniques. Case studies were conducted.

A novel TDMA transmission scheme stemming from the work in the area of on-board processing satellites was elaborated, operating on a symbol-synchronous basis. It minimises the overhead for synchronisation, normally necessary in conventional TDMA systems. Furthermore this new system can operate at low signal to noise ratios and is hence beneficial for satellite systems using small and inexpensive earth stations.

The design of a novel satellite gateway based on TDMA was completed and a prototype developed. Based on transputers which provide real parallel processing, it makes use of ATM cell switching and can be immediately interfaced to existing protocol routers or network hubs, providing interoperability between heterogeneous networks.

Several access schemes were studied in detail. The development of the FODA-IBEA access scheme, done in Italy, showed that the satellite link can be divided efficiently among many users (stream and datagram applications are mixed, reservation is based on different types of traffic).

Demonstration systems were set up, initially using existing facilities in the various laboratories. At the COST 226 workshop in Graz in 1993 three sites (Graz, Oberpfaffenhofen and Budapest) were interconnected via the OLYMPUS satellite using an experimental TDMA controller. LAN traffic and digital video and audio was supported at data rates of 2 Mbit/s. A tele-seminar applications was successfully shown : all presentations of the workshop were broadcast to the other sites, from where participants could ask questions to the referees via the return link. Access to remote image data bases via satellite was demonstrated as a LAN application. Researchers were using multi-media workstations for the display of the remote sensing images. Using in-window videoconferencing the specialists could interactively discuss the results. At the Final Symposium a demonstration of the satellite gateway was made showing remote access to the Internet at high speed and simultaneous video conferencing.

% Work planned

The MC of COST 226 elaborated the MoU for a follow-on Action, COST 253, dealing with integration of networks by low-orbiting satellites. This Action started in October 1996.

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Coordinador

Technical University Graz
Aportación de la UE
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Dirección
Inffeldgasse 12
8010 Graz
Austria

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Última actualización: 16 Enero 2000

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Permalink: https://cordis.europa.eu/project/id/226/es

European Union, 2024