Technology: Customers caught in the cellphone net

时间:2019-03-04 04:03:11166网络整理admin

By BARRY FOX WITHIN two years, Britain’s airwaves will be so badly congested by conversations on cellular phones that new subscribers will have to use a more expensive pan-European system, whether they want it or not. Cellnet, one of the companies running a cellular network in Britain, has warned its dealers to prepare for a change in the technology of their products. Unless the companies which operate the networks switch to the European system, they will have to choose between turning new subscribers away and offering a service where not all subscribers can make calls at peak times. The European cellular system uses similar frequencies to Britain’s existing, analogue, services, but it relies on digital technology to get more out of the frequencies. A disadvantage of the European system is that subscribers will have to buy new and more expensive phones to use it. The only way that the new service will be able to expand is by ‘stealing’ frequencies from the existing services, so subscribers to the British system will then have to switch to the more expensive European service. Vivienne Peters, the head of the Telecoms Users Association, doubts that the operators will subsidise the cost of the European system. ‘It will be the users who pay – it always is,’ she predicts. Britain’s existing cellular services use the Total Access Communications System (TACS). They are already congested and the Department of Trade and Industry has released frequencies used by the military, known as extended TACS, to provide a temporary solution to the problem. Being an analogue system, TACS does not make the best of the frequencies allocated to it. Nor can subscribers use their phones abroad. So a switch to the European system is therefore inevitable. Since 1982, European governments have been planning a system called GSM that would cover the continent, allowing people to make calls in any country. The standard for GSM will be set in January 1990, to allow manufacturers to produce phones ready for the launch of the scheduled service on 1 July 1991. GSM carries speech as heavily compressed digital code which is interleaved to allow one channel to carry at least twice as many calls as TACS. The sophistication of GSM means that the hardware for it will be more expensive. The price of a call on a cellular phone will also rise to pay for the cost of billing subscribers across national borders. The original idea was to offer GSM as an alternative to TACS for the relatively few business subscribers who were willing to pay extra for the privilege of making and taking calls anywhere in Europe. Now, cellular engineers working for both Britain’s operators, Cellnet and Vodafone, have had to rethink their plans. If the operators cannot offer someone a phone on TACS, they will in future offer them GSM instead. Both Cellnet and Vodafone agree that the frequencies allocated to GSM will not be enough for the service to work as an overflow from TACS. The companies also agree that the TACS frequencies will eventually be handed over to GSM, because it is more efficient. But the companies have not agreed when to switch existing customers to the pan-European system. Until recently, engineers believed that there could be a slow, orderly transfer of a few frequencies at a time, with all frequencies to be transferred by 2010, the year when the TACS operators’ licences expire. Now, research carried out by the TACS operators shows that the computers controlling the GSM system will need to work with large blocks of frequencies transferred from TACS. So a painless transfer is unlikely. The vital question is how long the existing systems can cope. Cellnet and Vodafone each have more than 300 000 subscribers already and 15 000 more are joining each month. Cellnet has coped by splitting cells into sectors to reuse the same frequencies many times in a crowded area. Vodafone has been reducing the size of its cells. Ted Beddoes, the technical director of Vodafone, believes that the company can accept up to 1.5 million subscribers in total and go on using TACS until at least 1992. Steve Hearndon at Cellnet prefers to work on a maximum of 1 million subscribers. He thinks Cellnet will reach that number by June 1991, when GSM becomes available. He warns that if the company takes on more subscribers, too many calls will fail, especially with one-third of the subscribers being in London. Whatever the companies do, consumers are likely to be inconvenienced. If GSM is late, subscribers to TACS will be turned away. If GSM is on time, people will be forced to pay for it. As GSM gains subscribers,