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A Strategy for the Future Use of the Radio
Spectrum in the UK
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A Strategy for the Future Use of the Radio
Spectrum in the UK
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The continuing development of small terminal applications in the fixed satellite bands (see 1.5 above) will continue to heavily influence the use of and congestion within certain Fixed Satellite Service (FSS) bands. Increasing use is also being made of Satellite News Gathering (SNG) applications, and the Agency has responded by initiating the development of a software tool to facilitate sharing in the 14.25 - 14.5 GHz band.
Demand for telecommunications satellites continues to grow steadily. The trend towards use of digital modulation techniques, use of more efficient systems and appropriate techniques to enable band sharing with other services should allow increased utilisation to be contained within the bandwidths currently available. This will be assisted by a more concentrated effort to transfer appropriate microwave fixed links onto cable.
The 1995 World Radiocommunications Conference (WRC-95) made good progress towards resolving spectrum allocations issues for non-GSO Mobile Satellite Service feeder links and for non-GSO FSS systems. A number of allocations were made in the 5/7, 15-16 and 20/30 GHz ranges but decisions were deferred to WRC-97 on some additional spectrum requirements. The detailed allocations are included in the tables in Appendix A of this document.
VSAT traffic is expected to be one of the key growth areas in the FSS over the next 10 to 15 years. Traditional gateway telephony traffic may continue to decline but this will be more than offset by growth in Direct-to-Home (DTH) and small-antenna customer oriented services.
Another significant growth market is in the use of the 20/30 GHz bands. A number of planned systems, utilising both geostationary and non-geostationary orbits have been notified to the International Telecommunications Union (ITU) over the last two years. The successful implementation of these systems would lead to the use of hundreds of thousands of terminals throughout Europe and the rest of the world. Studies have indicated that severe sharing difficulties are likely to arise if such high density FSS terminals were to operate co-frequency with fixed service video-on-demand services under consideration in the UK.
An unfortunate phenomenon associated with this growth is the large number of filings of speculative networks (paper satellites) with the ITU. Work is on-going in the ITU to address this issue which poses some difficult questions of both a technical and political nature. The Agency has recently put in place a procedure to ensure that UK filings are only submitted to the ITU Radiocommunications Bureau for planned UK satellite networks which can realistically be expected to become operational within a stated timescale. Applicants will be required to provide documentary evidence such as outline business plans and construction, launch and operational target dates.
Satellites operated within the Mobile-satellite service have been offering services on a world wide basis for many years. These satellites are being deployed in the geostationary satellite orbit (GSO). More recently, satellite networks are planned using non-geostationary satellite orbits (N-GSO) to offer global or regional voice and data services primarily to hand-held terminals for personal communications from around the year 2000. These N-GSO networks are also referred to as Satellite Personal Communications Services (S-PCS) systems.
It is expected that S-PCS system terminals will be designed with dual-mode satellite/cellular technology to provide access to terrestrial cellular services where necessary. The S-PCS systems are expected to provide for the satellite component of the Future Public Land Mobile Telecommunications Systems (FPLMTS/IMT-2000).
The frequency bands around 1.5/1.6 GHz are already being extensively used by GSO satellite systems. The service links of N-GSO S-PCS systems are planned for the 1.6/2.4 GHz, 1.9/2.2 GHz bands and possibly extending to the 2.5/2.6 GHz band. The Feeder links for communications between the N-GSO satellite systems and Earth stations are planned in a number of bands around 5/7 GHz, 15 GHz, 18/19 GHz and 28/29 GHz. The numerous proposals being made for further expansion of mobile satellite services are likely to lead to the consideration of further frequency allocations at future World Radiocommunications Conferences.
Mobile Satellite services providing low speed data systems are also planned in frequency bands below 1 GHz.
The science services compromise the Radioastronomy, Space Research, Earth Exploration-Satellite, Space Operations and Standard Frequency and Time services.
Trends in the future for the science services include:
· Space VLBI (Very Long Baseline Interferometry). VLBI involves the simultaneous observation of a radio source using antennas separated by large distances. The use of Earth based VLBI as a technique of radioastronomy is well established, in some cases giving an angular resolution of better than 1 milli-arcsecond. Within the next year or so, two orbiting radiostronomy antennas are expected to be launched. When incorporated into a VLBI system, these will result in an even greater improvement in angular resolution.
· Pushbroom sensors (a future high gain forward scanning sensor) for spaceborne microwave remote sensing. Data from microwave remote sensors are used by the UK Met. Office for weather prediction. Many existing sensors employ a mechanically scanning antenna to provide spatial separation of measurements. The next generation of sensors will employ a “pushbroom” scanning technique which employs an array of sensors in a fixed geometry. The technique allows improvements in both instrument resolution and sensitivity.
· The increasing use of Data Relay Satellites to send data between Earth Observation spacecraft and Earth stations. Many Earth observation spacecraft are in an orbit close to the earth. This means that for any point on the earth, the satellite is only visible for small proportion of its orbit. A data relay satellite placed in geostationary orbit can receive data from the Earth observation satellite during a much greater proportion of its orbit, and relay the data to an Earth station. This permits a reduction in the number of Earth stations necessary to ensure permanent reception of data.
The Space Science Services are currently enjoying a high profile with demand for high protection leading to challenging sharing situations. Several issues are being discussed in the context of WRCs ‘97 and ‘99
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