nments (in different service environments - residential, private domestic and different radio environments) provided that the terminal has the necessary capa- bilities; (e) to provide support of roaming users by enabling users to access services provided by their home environment in the same way even when roaming. (f) to provide audio, data, video and particularly multimedia services; (g) to provide for the flexible introduction of telecommunication services; (h) to provide the capability to support Universal Personal Telecommunications (UPT); (i) to provide within the residential environment the capability to enable a pedestrian user to access all services normally provided by fixed networks; (j) to provide within the office environment the capability to enable a pedestrian user to access all services normally provided by PBXs and LANs; (k) to provide a substitute for fixed networks in areas of diverse population densities, un- der conditions approved by the appropriate national or regional regulatory authority. The UMTS Network and Radio Access Technology (1) to provide support for interfaces which allow the use of terminals normally con- nected to fixed networks. In addition UMTS aims: to enable users to access a wide range of telecommunications services, including many that are today undefined as well as multi-media and high data rates. to facilitate the provision of small, easy to use, low cost terminals with long talk time and long standby operation; to provide an efficient means of using network resources (particularly radio spec- trum). Based on the above objectives, specific requirements related to services are outlined in the ETSI Specifications [15-17]. These requirements are primarily concerned with items such as Quality of Service, Security and Charging, Service Management, etc. 1.2.2 UMTS Terrestrial Radio Access Aspects The UMTS Terrestrial Radio Access (UTRA) system requirements are based on the service requirements. The latter sets the demands, which UTRA specification aims to meet. Table 1.2 sum