Technology : Europe sets cellphone agenda

2019-02-27 06:13:04

By Barry Fox THE next generation of mobile phones will be able to transmit data at least twice as fast as today’s fixed ISDN digital lines. As well as carrying voice messages, the new technology will allow a mobile office to be integrated into a company’s computer network. Several European cellphone companies are working together on the system, which is dubbed the Universal Mobile Telephone System (UMTS). “The only constraints are the frequency spectrum and our imagination,” says Mike Short, of Cellnet, who is coordinating a Europe-wide push to persuade governments to allocate the necessary frequencies to the new services. The high-speed system is much more than a gimmick, says Short. “This is not about delivering movies on demand to a car moving at 70 miles per hour. It’s about libraries on air and electronic commerce.” The first cellphone systems were launched more than a decade ago. They broadcast at 900 megahertz and use analogue technology. They were only designed to carry speech, and if someone wants to send other data they need a modem. Second generation systems, first deployed five years ago, are all-digital and use the Global Systems for Mobile communication standard (GSM) at 900 megahertz or 1800 megahertz. GSM was developed in Europe but has been adopted worldwide. It allocates separate channels for data and voice messages, but the speed is limited to 9.6 kilobits per second. This seemed adequate in 1986, when research on GSM was completed, but that was before the explosion of interest in electronic information. The only way to increase GSM data transmission speeds is to gang several channels together, wasting valuable space in the frequency spectrum. The International Telecommunications Union is now clearing a band of frequencies between 2.1 gigahertz and 2.3 gigahertz for use worldwide to create something called the Future Public Land Mobile Personal Telephone System, also known as IMT-2000. Much of the band is free of traffic because it was too expensive in the past to build consumer communications equipment for such high frequencies. At these short wavelengths, solid-state amplifiers do not deliver much power, and the positioning of components inside the equipment must be very precise. Cheap mass production is now feasible, however, thanks to recent advances in gallium arsenide transistor technology and the precision surface mounting of miniature components on printed circuit boards. The major European telecoms companies have got together, with funding from the European Union, to develop the latest system. At the same time, ETSI, the European Telecommunications Standards Institute, is drafting a European standard. The partners hope to repeat the success they had with GSM, which is now used in over a hundred countries by 30 million customers. UMTS is an all-digital system, which divides the service areas into cells, just like a conventional cellphone network. But it is designed with data in mind, and speech is treated as just one of many forms of code. When UMTS is used at full signal strength to carry calls over a wide area, the data rate is 150 kilobits per second. When the system is used at lower power in restricted areas such as financial centres, the rate rises to 2 megabits per second. Today’s standard ISDN lines operate at 64 kilobits per second, although faster versions are available. “R&D is now nearly complete,” says Short. “A service can begin by 2001, but all of us —Cellnet, Vodafone and the personal communications networks operators—need to know by early next year whether the government will license a service.” In Britain, the Department of Trade and Industry says it is now discussing the UMTS proposal with joint regulators Oftel and the Radiocommunications Agency. UMTS works at a frequency close to the 2.45 gigahertz used by microwave ovens. But Mike Tiplady, director of technology for Cellnet, dismisses possible health fears. “Powers will be very low,