A review of European communications.
Ironically, it looks like the technology will be at least as successful outside Europe, if not more so, in the many countries where analogue systems were unavailable or rudimentary. By definition, these countries constitute a massive marketplace for this technology. By contrast, the situation in the US as the marketplace moves into the digital domain, continues to appear patchy and confused to informed observers, unfortunately resulting in laissez-faire policies that have resulted in the appearance of fragmentary standards.
Meanwhile, competition within the GSM market is also becoming significant, which is likely to determine future success. There are already at least 10 GSM second operators, with more expected to receive licences in the foreseeable future. However, GSM also faces competition in its home market from an array of other technologies now actualized or actively contemplated. Primary competition comes from personal communications networks (PCN) and prospective mobile satellite services.
Personal Communications Networks
The concept of PCN originated in the UK with the aim of providing low cost, high capacity mobile communications. In 1989, three consortia, Mercury Personal Communications, Unitel and Hutchinson Microtel, were licenced to build and operate PCNs in the UK. However, by early 1992, Mercury and Unitel decided to consolidate their efforts and formed a full merger of their PCNs and services.
In 1990, the European Telecommunications Standards Institute (ETSI) adopted the PCN standard as an Interim European Telecom Standard (IETS), which was designated DCS 1800. This was followed by the formation of two groups by the Strategic Review Committee (SRC) for short and medium term planning. The first group included GSM projects for cellular transmission, digital European cordless telephony (DECT) for cordless systems and European radio messaging service (ERMES) for paging. The second of these groups was set up to respond to overall mobile communications, which included PCN.
The PCN standard operates within the 1.7 to 1.9 GHz band with micro cells ranging from 100 m to 1 km radius, allowing a high density of subscribers. The PCN technical standard is based on the GSM pan-European standard for digital cellular telephony. It uses time division multiple access/frequency division duplex technology. Optimization of the network lies in the use of radio beams between the radio base and switching stations. The system incorporates national roaming, which allows users of one PCN access to other PCNs.
For PCN, the powers associated with both the base stations and the pocket telephone transmitters are lower than those for GSM. PCN handsets' peak output power is specified at 1 W and 250 mW compared with 20 W, 8 W, 5 W, 2 W and 0.8 W of GSM. However, the British PCN has failed in its objectives of using microcells to achieve high subscriber densities while reducing cost, which is evident by the increase in cost per subscriber.
In Europe, apart from the UK, Germany has shown considerable interest in PCNs. In 1992, as part of Germany's telecommunications deregulation, a tender for PCN, E1, was issued. Earlier this year, Germany awarded the organization E-plus its E1 licence to run a PCN network. The E-Plus consortium consists of Vodafone, Thyssen, Veba, BellSouth and the French banking concern Caisse de Depots et Consignation with companies from the new Federal States holding the remaining shares. This network is based on the same principles as the British network, and is essentially GSM at 1.8 GHz. The system involves the use of small cell size, which increases the number of base station transceivers required, due to the employment of the 1800 MHz frequency. However, this system differs from traditional PCN in that the cell size is not restricted, producing a more flexible system. Apart from the higher frequency employed by E-Plus, the other main factor is that it does not allow roaming between the E-Plus system and GSM.
E-Plus is Germany's third operator after Deutsche Telekom and Mannesmann Mobilfunk, and as such both of these operators are prevented from offering a service in the 1800 MHz band for a period of four years. However, E-Plus needs to negotiate with Deutsche Telekom with regard to buying leased lines.
Initially, E-Plus intends to develop the network in the new Federal States, and it is estimated that the network will be operational in Berlin and Leipzig by the beginning of 1994. With this in mind, E-Plus will ultimately have to install its own transmission capabilities to achieve its estimated coverage levels. E-Plus projections for the next few years include a population coverage of 88 percent by the end of 1995, and a 98 percent total coverage across Germany by the end of 1997, which would result in E-Plus obtaining between 30 to 35 percent of the expected 10 million subscriber market.
Two vendors, Nokia and Siemens, have reached agreements with E-Plus for the supply of E-Plus' infrastructure of base stations, switches and hand-portable phones. Nokia has won a DM 150 M contract with the organization; and Siemens has signed a letter of intent with E-Plus, although a firm contract is yet to be signed.
Competition for GSM
The competition position of the two digital technologies of GSM and PCN remains complicated. Currently, UK operators are managing the introduction of PCN technology marketed as a solution to urban professionals. The network may be extended nationally as the market develops. However, the simultaneous presence of competing technologies in the British marketplace is an intriguing case study for providers and possibly a confusing one for the general public. In at least one case, an operator has been prepared to market its existing analogue services alongside its GSM pan-European service, and its city-based PCN service targeted at the professional and 'low-cost' consumer, respectively.
PCN could pose a potential threat to GSM because of the development of the DCS 1800 standard, which has resulted in interest within Europe from what was essentially a UK strategy. Now the distinction between PCN and GSM is gradually being reduced simply because of the decision to base the DCS 1800 standard on the GSM standard. The initial aim for the introduction of PCN for the provision of mobile communications at a lower cost has become less of an issue as a direct result of the realization that the costs of infrastructure for PCN implementation could be extremely expensive. However, PCN has one particular advantage over GSM in that it is able to offer greater system capacity. This advantage is probably going to be the most critical factor in determining the success of PCN and GSM.
However, as the technology develops, other strategies are becoming possible. PCN or DECT essentially in a cordless technology format could well be the technology format could well be the technology of choice for fixed, as opposed to mobile, network access. Terrestrial network operators with no formal mobile communications licences could arrange for fixed or semi-mobile users to make and receive calls as if they were wired. Public cordless services have so far not had a promising start with the CT2 common air interface technology, which offered residential and public services to handsets within 200 metres of a base station. A major limitation has been the need for such CT2 services to be publicly at least one-way only (only call origination is possible), although it is likely that services introduced in the future will be more flexible. Another key feature that is becoming possible under the DECT standard is the capability of providing on-premises networking using private branch exchanges (PBX). It seems the concept of a technology that could be used at home, while travelling and in the office remains an objective of most suppliers. However, inevitably, most commentators see even the boundaries of what constitutes cellular technology and what constitutes cordless technology blurring as developments take place.
Satellite-based personal communications services are also posing a potential threat to GSM. These low Earth orbit (LEO) systems rely on satellites orbiting the Earth at altitudes of around 1000 km. LEO systems aim to provide voice telephony and data services to hand-portable terminals internationally, which would offer some distinct advantages over GSM. It is expected that LEO services will be available by the end of the 1990s. These personal communications systems provide full global roaming with a common handset with total area coverage of a service area from launch. The systems include maritime, aeronautical and terrestrial coverage. However, the main limitations of such systems remain the relatively low system capacity and the high cost associated with the projects, including call costs in addition to a fixed monthly rental. Another issue is the doubts concerning in-building penetration. This is likely to result in these services being limited to particular niche markets, such as international professional travellers, and serving remote areas where a traditional terrestrial service is not economical. Consequently, LEO mobile services are likely to coexist with GSM services rather than replacing them entirely with even the possible introduction of dual mode LEO/GSM handsets.
One such personal communication system designed and developed by Motorola is Iridium. This system employs a portable unit for global communication. The system consists of 66 linked satellites orbiting at approximately 420 miles above the Earth and providing continuous line-of-sight coverage between all points on the globe. The Iridium phone units communicate with satellites and interface with the public switched telephone networks (PSTN) through gateways that store customer billing information, keep track of user locations and interconnect with terrestrial carriers. Iridium utilizes the 1610 to 1626.5 MHz spectrum and is designed to operate over spectrum shared by other mobile satellite systems. The system is designed to complement rather than compete with existing systems. Iridium does not conflict with Project 21, Inmarsat's programme for personal mobile communications, and in fact, offers to lease to Inmarsat members, providing service over existing Inmarsat facilities.
As part of Project 21, Inmarsat introduced Inmarsat-C for portable mobile data in 1991 and in 1992, Inmarsat-M, a briefcase telephone. Satellite paging facilities will be introduced in 1994, but what is seen as the culmination of the project is Inmarsat-P, a hand-held satellite phone for global use.
Inmarsat-P offers dual-mode operation, full duplex voice, Group 3 facsimile and data services at 2.4 kbps together with a high penetration paging facility. The unit permits global roaming. These services require a new generation of satellites, and a number of satellite systems and orbit configurations have been proposed to provide the required coverage and capacity. The options include geostationary Earth orbit (GEO), LEO and intermediate circular orbit (ICO) satellite systems. Each system has advantages and disadvantages and a final choice is yet to be made. Inmarsat-P is expected to be in service by the year 2000, and it is predicted that by the year 2005 there will be over one million users.
According to industry sources, the number of very small aperture terminals (VSATs) in the US is estimated to be in excess of 100,000. This compares with 3000 VSATs in Europe. However, Europe is now recognizing the benefits of VSAT technology, which provides clear advantages over terrestrial networks in terms of speed of deployment, bandwidth availability and reliability, and so providing an attractive cost effective solution. The European VSATs include over 2000 in Germany, over 300 in Italy, over 200 in Spain and over 100 in Portugal. VSAT networks also exist in the Netherlands, France, Belgium, Austria and Hungary.
Applications for two-way VSAT services include, in retailing, providing multimedia communications between the headquarters of a company and its retail stores; in the car industry, linking manufacturers, dealers and distributors; and in the hotel industry, providing customers with reservation details. However, due to regulatory restrictions in Europe, two-way VSAT services have remained underdeveloped. Deregulation could provide market growth.
Digital Microwave Technology
Microwave radio and satellite transmission represent complementary technologies. The onset of broadband technologies primarily relate to fibre-optic deployment, but recently the use of microwaves in synchronous digital hierarchy (SDH), the standard for large capacity traffic, is also seeing many applications. SDH transmission by microwave systems is possible in all parts of the SDH network, including the trunk, regional, local and customer access networks.
Microwave transmission provides a solution to many existing networks, for example, where fibre-optic transmission is not practical due to geographical features. In many cases, microwave systems already exist for analogue and digital plesiochronous networks, which provides an easy and cheap migration to SDH. In addition, with particular reference to the local and customer access networks, microwave systems provide fast and flexible implementation of SDH access to larger customer groups, loop closing, spurs and bridging functions.
The design of SDH microwave equipment involves the coexistence of new and existing equipment for which the available radio spectrum is limited. Technical requirements are related to the high traffic volume that is expected on SDH networks. The standardization of SDH has led to the definition of the STM-1 level as the basic synchronous level of the 155.520 Mbps and multiples of STM-1, such as STM-4 and STM-16. Due to the limited available spectrum and the need for compatibility between existing systems, microwave transmission at the basic STM-1 level requires a mono-carrier-based transmission system, which provides an easy migration path to STM-1 transmission systems from present ones. However, at higher STM levels, for example STM-4 and STM-16, transmission system multicarrier microwave systems are required. To ensure compatibility with existing systems, the combination of mono-carriers is preferred to transmit higher STN-n levels to multi-carrier operation, which although it might incur lower costs, is more difficult to introduce in the network.
Another consideration is the transition to the higher bit rate associated with SDH, as well as the synchronization of the entire transmission path. This transition is possible by changing the channel arrangement using present modulation schemes, which increases the bandwidth required for STM-1 systems. An alternative is to change the modulation schemes while keeping the present channel arrangement intact. An example of such a system has been selected by Deutsche Telekom for eastern Germany. The network installed as a turnkey contract by Alcatel SEL provides capacity for inter-regional transmission links. The existing copper-based system can be easily upgraded using microwaves to cater to the increased capacity. The intended network extends between Sachsen and Thuringe and also Erfurt, Leipzig and Chemnitz.
Approximately two-thirds of the 28 intermediate and local transmission centres have been connected to the main transmission centres using microwave links. Microwave transmission relays have also been installed on many of the sites. The local rural network, Rurtel, also supplied by Alcatel, has benefitted from the microwave network, where a digital microwave concentrator connects subscribers and public telephones over a distance of up to 40 km, without the use of relay stations, with an extension of up to 300 km with the use of relays.
For the future, microwave radio is set to play an important role to complement optical fibre because it allows present (plesiochronous) already installed systems to be upgraded to SDH cost effectively.
GSM is now well established, not just in Europe but in many parts of the world. Because it forms the basis of the DCS 1800 standard, manufacturers can investigate the possibilities of participating in wider markets, such as dual-mode terminal equipment. Therefore, GSM operators are in a good position to respond to any potential threats from competing technologies. As GSM networks grow, operators can look to new markets, such as paging and mobile data.
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||Special Report|
|Date:||Oct 1, 1993|
|Previous Article:||A low cost mm-wave cruise control system for automotive applications.|
|Next Article:||The status of microwave research, development and manufacturing in China.|