This book provides a comprehensive text on the current technologies for future generation mobile networks. It will cover both cellular systems and non-cellular standards required in next generation networks (NGNs) in a single book. Technological requirements of the NGNs to support the wireless IP including mobility management, resource management, and quality of service management will be outlined. The most profound requirement of the future wireless IP network, i.e., the network architecture, will be explained with emphasis on future services and applications that must be supported within the wireless networks, consisting of both data and voice-type real time traffics. The text will also compare the two deployment directions of the wireless IP using cellular versus IEEE standards.