e of IMT-2000 systems. IMT-Advanced has provided a global framework for the development of the next generation of wireless radio access networks that enable low-delay, high-speed, bi-directional data access, unified messaging, and broadband wireless multimedia in the form of new service classes. Such systems provide access to a variety of mobile telecommunication services through entirely packet-based access/core networks. The IMT-Advanced systems support low to very high mobility applications and a wide range of data rates proportional to usage models and user density. The design and operational requirements concerning the 4th generation of radio interface technologies may vary from different perspectives with certain commonalities as follows: End User Ubiquitous mobile Internet access; Easy access to applications and services with high quality at reasonable cost; Easily understandable user interface; Long battery life; Large choice of access terminals; Enhanced service capabilities; User-friendly billing policies. Content Provider Flexible billing; Ability to adapt content to user requirements depending on terminal type, location, mobility, and user preferences; Access to a sizable market based on the similarity of application programming interfaces. Service Provider Fast, open service creation, validation, and provisioning; Quality of service and security management; Automatic service adaptation as a function of available data rate and type of terminal; Flexible billing. Network Operator Optimization of resources in terms of spectrum and equipment; Quality of service and security management; Ability to provide differentiated services; Flexible network configuration; Reduced cost of terminals and network equipment based on global economies of scale; Smooth transition from legacy systems to new systems; Maximizing commonalities among various radio access systems including sharing of mobile platforms, subscriber identity modules, network elements, radio sites; Introduction Single authentication process independen