说明：  What is an all-IP network? What difference will IP networking make to 3G services? Third Generation (3G) mobile offers access to broadband multimedia services - and in the future most of these, even voice and video, will be IP-based. However 3G networks are not based on IP technologies, rather they are an evolution from existing 2G networks. Much work needs to be done to IP QoS and mobility protocols and architectures for them to be able to provide the functionality 3G requires. IP for 3G gives a comprehensive overview of 3G networking functionality and examines how IP protocols can be developed to provide some of the basic building blocks of a mobile system (mobility, QoS and call control)