How WARC '92 will affect mobile services

The US proposals to, and the decisions of, the 1992 World Administrative Radio Conference (WARC '92) that relate to mobile and mobile-satellite services are described. Mobile-satellite service (MSS) issues addressed at WARC '92 include new allocations for low Earth-orbit (LEO) satellite operations, new MSS spectrum allocations, and modifications to current allocations used to support mobile-satellite operations. Allocation issues on the agenda of WARC '92 that related to the terrestrial mobile services include allocations for mobile services between 1 and 3 GHz, allocations for aeronautical public correspondence, and designation of frequency bands for future public land mobile telecommunications services. A number of proposals which were put forward by the US to support MSS allocations and operations that did not explicitly require allocations to the MSS are discussed     

Spectrum sharing considerations for the proposed ESA ‘archimedes’ satellite DAB service

At the 1992 World Administrative Radio Conference (WARC), spectrum was allocated, on a primary basis, to the broadcast satellite service (sound). The allocations were not, however, uniform worldwide, nor will the BSS(S) have sole use of these allocations. In addition, many countries have reserved primary use of the spectrum for existing services until 2007, with the BSS(S) permitted only on a noninterference basis. This situation will impose serious constraints on the proposed ESA S-DAB service, to be radiated from the ‘Archimedes’ constellation of satellites. The launch date for this service may be before the end of the century, and sharing with other spectrum users will therefore be necessary. Such users include fixed telephony links, broadcast links and mobile aeronautical telemetry. This paper reviews current spectrum usage in Europe and elsewhere, and investigates the restrictions thus imposed on the ESA S-DAB service. Numerical examples based on real-world systems are given, and demonstrate the feasibility, in many cases, of spectrum sharing.     

Summary of conclusions of the 1992 World Administrative RadioConference

The major decisions made at the conference are briefly described. Additional frequency bands for shortwave (HF) radio broadcasting were agreed upon. Frequency allocations were made to support a number of US proposals, to provide advanced mobile radio services using low Earth orbit satellites. Allocations for land based mobile services adopted at WARC '92, in the range 1700 to 2600 MHz, are meant to foster improved mobile services that can be used worldwide. An allocation was also made to support commercial telephone service between passengers flying on aircraft and individuals on the ground. Allocations were made for sound broadcasting from satellites, as well as for providing a means to accommodate a complementary terrestrial-based digital audio broadcasting service. New frequency allocations to support space activities were agreed upon, and an allocation was made to the fixed satellite service in the band 13.75 to 14.0 GHz     

Mobile communications

An important issue facing the 1992 World Administrative Radio Conference, namely, determining how to provide additional spectrum for both existing and entirely new mobile services, is examined. At least six types of mobile systems will be seeking new or expanded allocations; three involve satellites and three rely on primarily terrestrial techniques. All but one will be forced to compete for allocations in the same crowded 1-3 GHz frequency range. The various allocation proposals are discussed     

The maritime radio spectrum future

Future satisfaction of the electromagnetic spectrum needs of the maritime mobile service is dependent on the translation of those needs to frequency allocations. In September 1979, over 100 countries will consider all of the spectrum, and make changes to meet perceived needs of radio services, including maritime needs up to the year 2000. This conference, the World Administrative Radio Conference 1979, will have a significant impact on future maritime radio operations. Issues, procedures, competing requirements, are explored to enable a better understanding of the regulatory process for frequency allocations.     

Space communications

Six proposals for enhancing or expanding the electromagnetic spectrum allocated for communications supporting research in space, which will be heard by the 1992 World Administrative Radio Conference, are discussed. They will cover extravehicular activities, space operations, data relay links, deep space interplanetary probes, future planetary missions, and Earth exploration satellites. Of primary importance to most space agencies is the need to improve the status of the allocation of the space research, space operations, and Earth exploration satellite services in the bands 2.025-2.110 GHz and 2.20-2.29 GHz     

Satellite Access Services

Satellite systems are unique in that they can effectively provide access, trunk and international links through the same physical infrastructure due to their inherent wide-area coverage. Satellites are increasingly being seen as a flexible delivery mechanism which can meet a diverse set of needs, from Internet access to global packet-based private networks. This paper analyses the access capabilities of existing satellite systems in terms of capabilities and limitations and looks at future system proposals which aim to fully integrate satellite systems into terrestrial networks for the delivery of advanced services. The long-term objective is to give service providers an additional access technology option for both national mass markets and global connectivity.     

手机电视技术分析与比较

针对手机接收数字电视信号这一业务要求提出多种解决方案,并分别对欧洲数字视频广播、日本地面数字广播、卫星广播及3GPPR6版本提出的多媒体广播、组播业务进行了详细介绍与分析,着重阐述各种技术的优缺点,同时以表格形式比较了几种主要的手机电视承载技术,为网络运营选择组网技术提供参考.     

Euteltracs: the European mobile satellite service

Euteltracs is Europe's first commercially operated mobile satellite service. Under the overall network operation of Eutelsat, the European Telecommunications Satellite Organisation, Euteltracs provides an integrated message exchange and position-reporting service for the European transportation industry with the aim of increasing cost-effectiveness, radically improving efficiency and security and enhancing business flexibility. This paper describes the architecture of the system and the message exchange and position-reporting service, and gives an overview of the commercial deployment of Euteltracs and of the current regulatory situation for its operation within Europe. It also provides an insight into some new applications for Euteltracs outside of its original target market, including specialised aeronautical and maritime services     

关于发展我国卫星移动通信的看法

本文主要介绍了我国卫星移动通信的发展现状及市场需求，针对当前国内外具体情况，提出了发展我国国内，国际卫星移动通信业务的合理建议。文章认为国内移动通信业务应采取先租星过渡，然后再建设自主运营，功能完备的卫星移动系统的方针；国外业务则采取慎重选择加入国际性系统的策略。     

HEO or GEO?

The effectiveness of highly elliptical orbit (HEO) and geostationary orbit (GEO) in providing a satellite platform for the delivery of mobile multimedia content in Europe are discussed in this paper. ONDAS has conducted extensive studies comparing the merits of GEO and HEO-based systems for the delivery of satellite-based mobile multimedia in Europe, and finds that, for a European service, the economic model of the GEO-based solution is quite simply just not as cost-effective as a HEO-based system. In this paper the elevation angles that would be seen by a mobile user in London for a three satellite HEO constellation is presented. The benefits are illustrated, which shows typical satellite shadowing effects at European latitudes caused by urban development and foliage for both GEO- and HEO-based solutions, and illustrates that significant improvement in signal quality and reception achieved by the HEO satellites     

Space radio services and WARC-MOB-87

A recent conference of the ITU has agreed upon worldwide frequency allocations near 1600 MHz for communication by satellite with mobile stations on land, and has permitted the use of some aeronautical mobile-satellite frequency bands for passengers' in-flight telephone calls to the ground. Frequencies for systems for locating mobile stations by radio, using satellites, were allocated.     

Satellite spacing and frequency sharing for communication and broadcast services

Satellite relays complicate the problem of sharing a limited frequency spectrum that is in great demand. This paper reviews the problem and outlines a general approach for efficient use of orbits and spectrum. The protection of received signals, the equipment capabilities, and systems considerations pertinent to the problem are reviewed before systematically examining the principal direct and scatter modes of interference. Conclusions derived include the following. The full potential use of orbits and spectrum for satellite systems can provide enormous capacities greatly exceeding any current proposals, but it requires careful coordination of many system parameters. The use of spectrum for microwave or satellite relays to fixed terminals could evolve to intense full sharing by both types of service without seriously limiting either one or requiring unreasonable accommodation. The satellite down links for area coverage to small terminals (e.g., mobile and broadcast services) can share fully and intensively the spectrum above VHF that is used for terrestrial mobile and broadcast services without seriously limiting the potential of any of the services. Although the greatest potential capacity of the spectrum lies above 16 GHz, for most down-link applications propagation factors make it more attractive to share the spectrum below about 16 GHz much more intensively before making extensive use of the higher frequencies. Providing the satellite down-link spectrum for area coverage to small terminals deserves priority consideration. For this purpose the UHF band is most attractive; the merit of the spectrum rapidly diminishes for higher frequencies.     

Telecommunications

The telecommunications blueprint for a single Europe after 1992 is examined. This `green paper' is an ambitious three-year-old document in which the European Community's Commission calls for a Western-Europe-wide telecommunications infrastructure based on the integrated-services digital network (ISDN) and other digital communication links. The progress that has been made toward this goal is assessed, showing that progress toward opening national markets and establishing an infrastructure varies greatly from country to country. The highly variable quality of network services throughout Europe presents a further obstacle to unification. Nevertheless, the national segments of a trans-European ISDN system are beginning to emerge, and work on the specific technologies, standards, and regulations for cross-border telecommunications systems are advancing     

An Advanced Satellite UMTS Testbed for Laboratory and Over-the-Air Experiments of Third-Generation Mobile Services—Part II: Experimental Results

This paper complements its companion paper by reporting the key experimental results obtained both in the laboratory and via satellite, using the Satellite Universal Mobile Telecommunication Systems (S-UMTS) Advanced TestBed (ATB) - a comprehensive facility developed under a European Space Agency contract whose intention was to demonstrate a set of technical solutions for the efficient provision of the so-called S-UMTS services, i.e., third-generation (3G) point-to-point (i.e., interactive) and point-to-multipoint (i.e., multicasting/broadcasting) mobile services based on wideband code-division multiple access (W-CDMA). After addressing the architecture of the overall via satellite ATB demonstrator, the main test results obtained in the laboratory, as well as over the air, are summarized. Then, bit error rate and frame error rate measurement results that were taken from the forward and return links are shown for both the additive white Gaussian noise and the Ricean channels, with different orders of space diversity and different coding schemes, which were classified as either convolutional or turbo 3G partnership project coding. Finally, key results of via satellite L-band measurements are reported for both unicast and reliable multicast applications. Because of the extensive test campaign presented in this paper, the viability of adapting W-CDMA to support point-to-point (packet) and point-to-multipoint multicast services in the satellite environment, as standardized by the European Telecommunications Standards Institute, has been widely validated and experimentally confirmed. Reliable multicast techniques, exploiting a forward error correction that operates at the upper layer, were shown to be a powerful way of counteracting satellite channel impairments, thus allowing the multicast of multimedia contents in quasi-real time with good quality of service.     

Provisions for High Frequency Future Use

An area of widespread interest at the 1979 World Administrative Radio Conference (WARC-79) was concerned with allocation proposals related to the modification of the high-frequency (HF) (4-27.5 MHz) portion of the spectrum. From a wide range of proposals, the Conference adopted allocation provisions that reduced the exclusive fixed-service bands by two-thirds, made significant allocations to the broadcasting and maritime-mobile services, and provided somewhat lesser spectrum provisions for the amateur service. Shared use of fixed bands by the mobile service was greatly increased. Few changes were made to aeronautical service allocations. Provisions were planned to remove an unused fixed-service assignment from the International Telecommunication Union (ITU) Master Frequency Register, and to provide special assistance to Less Developed Countries (LDC's) to enable them to better meet their fixed requirements. A conservative schedule of changes, through 1994, was adopted, including several specialized planning conferences to assist in optimizing the use of HF bands. With continued national needs and improved technology being developed and adopted by the ITU member countries, systems in all authorized HF services will be widely used to meet requirements of the world community for a long time to come.     

Optical Communications in Space – a Challenge for Europe

The successful test of a laser communication link between an ESA data-relay satellite and an Earth observation satellite marks a milestone in the development of optical space communications. It is the right moment to look back on more than 20 years of R & D effort in Europe. The paper gives an overview of the optical space communication activities at the European Space Agency (ESA), which have started in summer 1977, when ESA placed the first technology study contract in the domain of intersatellite optical links, and reports on the most recent European systems andhardware technology efforts aimed at the development of small and compact laser terminals for global mobile communication systems and satellite-based data networks.     

3rdgeneration mobile systems umts/imt-2000

When International Telecommunication Union (itu) identified in 1992 new frequency bands for third generation mobile systems, few people were really convinced that there was a need for such systems because the first second generation systems (like gsm in Europe) were recently launched and nobody could imagine at that time that 8 years later penetrations rates for voice will exceed 50% in several countries. The development of multimedia services in fixed networks was the key factor to trigger standardisation activities in different organisations (ITU, etsi ) involved in mobile systems. But rapidly, the globalisation of this activity led to the birth of different standardisation forums with the objective to develop specifications for multimedia mobile systems called imt 2000 (International Mobile Telecommunication 2000). One of this system is UMTS (Universal Mobile Telecommunication System) which is supported by different Japanese and European companies; the first commercial launch of such a network is foreseen in October 2001 in Japan and at the beginning of 2002 in Europe, umts will offer higher data rates (up to 384 kbit/s in a first phase) and better spectral efficiency than existing mobile systems;     

Planning aspects of satellite and terrestrial digital sound broadcasting

DAB is one of the most promising sound broadcasting techniques for the future. It will soon start terrestrial operations, and later on will be used for satellite broadcasting. The Eureka 147 DAB system is based on a set of well-demonstrated techniques, in particular the MUSICAM coding, adopted by MPEG, and OFDM modulation. It allows great spectrum efficiency, profiting from the single frequency network concept, one of the most interesting characteristics of the system. However, frequency problems remain a difficulty, as DAB must either examine the possibility of entering existing heavily used frequency bands or wait until the new frequency bands allocated by WARC 92 become fully available. For terrestrial broadcasting, most interested operators, broadcasters and manufacturers are convinced that appropriate solutions will be found and that DAB will start operational services from about 1996. In Europe, a CEPT planning conference will address the matter in 1995. Satellite broadcasting may come later. Short wave broadcasters examine possibilities to replace short waves, the quality of which is so poor, by digital satellite broadcasting. From the frequency spectrum point of view, this raises the difficulty of sharing frequency allocations with terrestrial applications.     

WARC's last act?

The upcoming 1992 World Administrative Radio Conference is discussed. The reasons for its importance are given, and three new types of services that are high on the list for consideration are examined. They are universal personal telecommunications, digital audio broadcasting, and high-definition satellite TV. US preparations for the conference and important international alliances are discussed