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Điện thoại di động mạng lưới Radio P15

UPT—Universal Personal Telecommunication∗ People are becoming more mobile. At the same time they have a greater need to be reachable and to be able to reach others. A variety of different systems that address all the different categories of mobility already exist: • Employees can be reached through a DECT terminal anywhere in their company. • Tradesmen can be called over a Digital Communication System (DCS) within a city. • Business people can be reached over the same telephone number via GSM anywhere in Europe, wherever they are located. . | Mobile Radio Networks Networking and Protocols. Bernhard H. Walke Copyright 1999 John Wiley Sons Ltd ISBNs 0-471-97595-8 Hardback 0-470-84193-1 Electronic 15 UPT Universal Personal Telecommunication People are becoming more mobile. At the same time they have a greater need to be reachable and to be able to reach others. A variety of different systems that address all the different categories of mobility already exist Employees can be reached through a DECT terminal anywhere in their company. Tradesmen can be called over a Digital Communication System DCS within a city. Business people can be reached over the same telephone number via GSM anywhere in Europe wherever they are located. Adventurous types are linked to civilization through the INMARSAT satellite system. For each of these communications systems the user requires a special terminal. In contrast to these radio-based systems wireline telecommunications systems capable of reaching almost every household in the industrialized countries are available. Fixed networks do not offer users mobility. To be reached at another terminal the user has to inform the caller of his new location area in the form of a telephone number. With Universal Personal Telecommunication UPT the telecommunications network assumes responsibility for establishing a user s location through an interrogation of databases based on a personal telephone number. This provides mobility in telecommunications networks to a larger number of users without the need for special new terminals. 15.1 Classification of Telecommunications Services The services of a telecommunications network first allow users to exchange information over the network in order to communicate. A service is what is With the collaboration of Matthias Frohlich 774 15 UPT Universal Personal Telecommunication Figure 15.1 Classification of telecommunications services made available to users by telecommunications authorities and private service providers for communication over public