Radio access: the key to global mobility
‘Mobiles’ have invaded the planet over the last few years, and the phenomenon that has so influenced telephony is now, with the advent of the new UMTS generation, spreading to other types of service, promising higher bit rates and almost limitless access
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............................................................... Radio access: the key to global mobility
'Mobiles' have invaded the planet over the last few years, and the phenomenon that has so influenced telephony is now, with the advent of the new UMTS generation, spreading to other types of service, promising higher bit rates and almost limitless access facil· ities. This chapter deals first with radio support, emphasizing the resource itself and the constant efforts made to optimize its usage. A description follows of the different domains in which radio plays its part in meeting one of the major objectives of the NGNs, i.e. generalized mobility. These include terrestrial networks with sec· ond or third generation mobiles, satellite communication networks and customer premises networks. The objective of generalized mobility is used here in its wider sense, as terrestrial audiovisual broadcasting and wireless local loop are also presented.
I. The support and its use 2. Land mobile radiocommunications 3. Terrestrial audiovisual broadcasting 4. Satellites 5. The Wireless Local Loop 6. Private radio systems D. Hardy et al. (eds.), Networks © Springer-Verlag Berlin Heidelberg 2002
Bibliography
Chapter 6 - Radio access: the key to global mobility
The support and its use 1.1
The frequency spectrum
I. I. I
The need for frequency allocation
In principle, all radio-communication systems make use of frequency transmission via a non-material support. The set of frequencies used constitutes the radio spectrum, the upper limit of which is by convention set at 300 GHz. Wave propagation takes place in an open environment common to all users, and the risk of mutual interference can only be avoided by the definition of and adherence to common rules. Dividing up the frequency band spectrum between users is one of the ways to ensure coexistence and compatibility of services. But because of propagation characteristics and technological constraints, frequency ranges are not equal and can only suit a given application in a general way. In view of the large economic stakes at hand, however, the trade-offs imposed by these technical elements still have to satisfy all requirements.
I. I .2
Regulation
Regulations concerning spectrum allocation are established by recognized bodies on several different levels: •
WRC
World Radiocommunication Conference
I. on a global/eve/, by the ITU-R, which organizes a WRC• every two or three years and is responsible for establishing the
Radiocommunication Regulations. Three world zones
have been defined corresponding approximately to the following geographic areas: -zone I: Europe, Africa, Middle East; - zone 2: North and South America; - zone 3: Indian Ocean, India, Iran, South East Asia, Pacific. On this level, spectral allocation is established per service: - fixed service communications between fixed stations via radio links and satellite communications; - mobile service communications by means of land, aeronautical or maritime mobile stations, and sometimes via sat
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