This book reviews the history of the development of mobile communication technology and the challenges faced by 4G communication networks. It introduces the vision and requirements, standardization and performance requirements of 5G, as well as the wireless, network and supporting technologies needed to meet the performance requirements of 5G. The book analyzes the frequency spectrum of 5G and the security requirements of the 5G network, and discusses the problems relating to the planning and deployment of 5G networks. It also analyzes the transformation of the business through the structure, key technologies and implementation cases of 5G based on the author's solid theoretical foundation and abundant practical experience in long-term engagement in large-scale engineering projects.This book can serve as a reference for persons specializing in technical research or standard setting for mobile communication networks or in the research and development of related products and businesses, such as future network planners, designers and network constructors. It may also be used for university courses on mobile communications.