This book describes the physical layer of UMTS (Universal Mobile Telecommunication System) which is one of the five members of the IMT-2000 family of standards. It compiles in a clear fashion the main technical features of the physical layer standard together with a description of the basics of digital communications and spread spectrum technology on which UMTS relies. In addition the test cases specified in the standard are described together with their implications on any practical front-end design. The reader will benefit from the standard description which frees him from studying lots of standardization documents. Additional explanations of the standard and especially the test cases will help to better understand the effects on any front-end system design. Many references are provided for readers interested in in-depth treatments of certain topics.