ety of wireless devices. From the service provision perspective, the domains share some common characteristics. Wireless service provision is characterized by global mobile access (terminal and personal mobility), improved security and reliability, higher service quality, and access to personalized multimedia services, the Internet, and location-based services via one or multiple user terminals. Multi-radio operation requires seamless interaction of systems SO that the user can receive/transmit a variety of content via different delivery mechanisms depending on the device capabilities, location and mobility, as well as the user profile. Different radio access systems can be connected via flexible core networks and appropriate interworking functions. In this way, a user can be connected through different radio access systems to the network and can utilize the services. The interworking among different radio access systems in terms of horizontal or vertical handover and seamless connectivity with service negotiation, mobility, security, and QoS management are the key requirements of radio-agnostic networks. The similarity of services and applications across different radio access systems is beneficial not only to users, but also to network operators and content providers, stimulating the current trend towards convergence. Furthermore, similar user experience across different radio interface systems leads to large-scale adoption of products and services, common applications, and content. Access to a service or an application may be performed using one system or using multiple systems simulta- neously. The increasing prevalence of IP-based applications has been a key driver for this convergence, and has accelerated the convergence trend in the core network and radio air interface. The evolution of IMT-2000 baseline systems and the IMT-Advanced systems has employed several new concepts and functionalities, including adaptive modulation and coding and link adaptation, OFDM-based multiple access schemes, single-user/mul