The European Commission's Green Paper on satellite communications, issued in November 1990, sets forth an understanding that is important to high-data-rate (HDR) applications: future European telecommunications networks will be hybrids of terrestrial and satellite services.
EUTELSAT currently provides over 13,000 narrow-band digital telephony half-circuits, over 92 routes between 17 countries. Some broadband data transmissions, such as digital video, remote printing and data file transfers, are taking place. In addition to numerous 64 kbits/sec channels, a few high-speed data channels of 140 and 155 Mbits/sec are currently operational. An INTELSAT cable restoration service provides a number of 140 Mbits/sec channels from European gateway earth stations.
Satellite communications capabilities are thus a part of future Integrated Services Digital Network (ISDN) and especially broadband-ISDN (B-ISDN) services. This is reflected in the planning and preparation of standards for the eventual integration of voice, video and data services. EUTELSAT and other satellite interests are active in the European Telecommunications Standards Institute and International Telecommunications Union (ITU) working groups, especially those involved in B-ISDN. This is not necessarily the case in the U.S. where working groups defining future telecommunications and network standards have not always considered the role of satellites.
When our European hosts were asked for their plans on developing or using HDR applications via satellite, the response, with one or two exceptions, was that the market for such services was fairly limited. Our hosts often referred to a market survey that showed very little growth for HDR services. High-traffic telecommunications routes are being converted to optical fibers, and TV distribution is currently satisfied using analog transmission through conventional satellite transponders.
The question was raised about a network or effort comparable to the U.S. High Performance Computing and Communications initiative. The response was that Europe has not developed the scientific or research requirements to distribute high-speed computing over long distances. There are fewer requirements for links such as we see in the U.S., where, for example, scientists with supercomputers at MIT may want to share a scientific problem with their colleagues at Cal Tech.
There are some high data rate space links being planned for ISLs, especially on the Semiconductor Intersatellite Link Experiment (SILEX) project. This effort is discussed in much more detail in the projects section of this report.
EUTELSAT brochures describe future broadband, high data rate telecommunications and broadcast services. Digital direct broadcast satellite (DBS) services are being planned, along with High Definition TV (HDTV) services that could use channels operating up to 155 Mbits/sec.
A new broadcast service, FLASH TV (Flexible Advanced Satellite System for High Quality TV), is being sponsored by the Commission of European Communities. This service is somewhat different from the current proposed European HDTV standard, taking the 1.6 Gbits/sec output from a high definition digital camera and compressing the data rate to approximately 70 Mbits/sec. This data rate will be transmitted with an uplink EIRP of 74 dBW, via a 36 MHz satellite transponder, and downlinked to a two or three meter ground antenna. The primary outlet for FLASH TV will be movie houses. Market studies conducted in Europe and the U.S. show that future top-rated movies can be distributed far more inexpensively via satellite than using the current production and distribution of film reels.
The major exception to the European lack of interest in satellite HDR systems was Alenia Spazio. The NASA/NSF panel received a short briefing and supporting documentation on some excellent development work being done in HDR hybrid networks. This work is being sponsored by the Italian National Research Council on its "TLC" telecommunications project. This research and standardization effort is working towards the eventual use of B-ISDN and is funded at a level that supports more than 200 man-years of research effort in a number of Italian research and academic institutions. This effort is being conducted under the guidelines of the European Community (EC) RACE program. The TLC program has five main areas of research. One area is devoted exclusively to optical technologies, and satellite technologies and applications are being pursued in the remaining four areas. These four research areas, with sub-tasks, include the following:
Figures 3.5a, 3.5b, and Figures 3.6a, 3.5b, and 3.6c, were prepared by C. Mossotto of CSELT as part of a TLC research paper on the first research area noted above, the "Structure of Broadband Communication Network." Figure 3.5a and 3.5b show a scenario for broadband communications, with 3.5a, being a terrestrial approach and 3.5b, being a satellite approach. In fact, both 3.5a and 3.5b acknowledge the interconnection of hybrid networks and have two basic network guidelines: (1) a centralized approach for the introduction of nodes with ATM functional capabilities, and (2) a distributed approach for the introduction of MANs for gathering business traffic. The satellite network (b) uses on-board processing (OBP) technologies to serve both network and user-oriented applications.
Figure 3.6 and 3.6b, shows the evolutionary use of digital techniques for telecommunications and broadcasting networks. B-ISDN technologies will play a major role in all of the network configurations. Figure3.6a, shows a TLC telecommunications network with a satellite operating in the FSS spectrum and providing narrowband and broadband digital services for business or special events using transportable stations. The telecommunications satellite can also service TV production centers with 70 Mbits/sec HDTV signals. The hybrid network also connects traffic from terrestrial digital networks and high definition broadcast centers. Figures3.6b, and 3.6c, are DBS operating in the spectrum allocated to that service. Figure 3.6b, shows a digital TV signal being translated to an analog high definition (HD-MAC) channel that is currently the European supported high definition standard. Figure 3.6c, shows the evolution that is expected to full 140 Mbits/sec digital HDTV services, being interconnected with terrestrial digital networks.
This Italian TLC project is a well defined research and experimentation project that is preparing for the transition of telecommunications and broadcast networks to B-ISDN networks and services. The project involves the development of hardware and software, as well as work on standards committees. As hardware and systems move towards implementation, experiments and demonstrations are scheduled to test and validate the work. Experimentation has already taken place on the ITALSAT satellite with the testing of HDTV. This analog and digital experimentation using Ka-band ITALSAT transmissions is a few years ahead of the NASA ACTS satellite scheduled for launch in July 1993.
Figure 3.5a. Target Scenario for Broadband Communications: Terrestrial Network
Figure 3.5b. Target Scenario for Broadband Communications: Satellite Network
Figure 3.6. HDTV by Satellite
The Japanese response to the panel's question about the future use of HDR satellite links and networks was similar by both private industry and government officials. The current position is to use optical fibers for future HDR networks. Our hosts explained that Japan is a small land mass with a well established infrastructure to lay and maintain optical cables. Japan is planning to use high capacity optical fiber cables that would carry B-ISDN traffic for a large number of HDR applications. As noted in the Fujitsu site report, a large satellite-based broadcast network of low-data-rate (2 Mbits/sec) users is being initiated, but the Fujitsu executives stated they had no plans for an HDR network to be implemented via satellite.
In discussions with Russian officials, it was explained that future medium- and long-distance data links would use satellites as the transmission carrier-of-choice. The geographical distribution of industrial and research centers throughout this large country, and the present use of satellite networks for the dissemination of communications and information, calls for expansion of the present system. The government currently is implementing financial and research networks with digital satellite systems. While most of these systems are operating at low data rates, plans for higher data rates to support the country's digital network requirements are based on the use of satellites. A proposed Denmark-to-Japan trans-Siberian optical cable was explained as largely a financial scheme to connect Europe and the Far East with a point-to-point high capacity telecommunications link, with limited use planned by the Russian government for in-country communications.
In the EC, equipment and standards are being developed for HDR applications to be employed in future telecommunications and broadcast networks. These will be hybrid networks using both terrestrial and satellite transmissions. However, it is the consensus of our hosts that the growth of HDR satellite links will be slow, so the development of equipment, services or networks is not receiving a high priority.
The one exception to this is the Italian TLC plan, a well-defined and funded National Research Council program for the development of broadband hybrid networks. Research and experimentation conducted under the TLC plan has included the testing of high definition television over the Ka-band ITALSAT satellite. This work currently is ahead of similar experiments planned for the ACTS satellite.
The Japanese government is planning to service HDR requirements with optical cables, although it is implementing a large low-data-rate broadcast satellite network.
The Russian government plans to connect growing communications and information networks with satellite links. The large geographical area with a well established communications satellite infrastructure makes this choice understandable.