This book provides a comprehensive description of Radio Access Networks for UMTS. The main content is based upon the release 6 version of the 3GPP specifications. Changes since the release 99 version are described while some of the new features from the release 7 version are introduced. Starting from the high-level network architecture, the first sections describe the flow of data between the network and end-user. This includes a dedicated chapter describing the Iub transport network. Detailed