scussions and consensus behind the choices or equivalent solutions have not always been retained in the final specifications. Therefore, in some ways this book tries to present an objective unified view of the key aspects of UMTS. On the other hand, the area of UMTS is vast in content and detail, and not all within the scope of these writings. As a result, the book will allow us to un- derstand the UMTS specifications and get a good grasp of its design, but the technical documents of formerly SMG, and now 3GPP, remain the official specifications with all their appropriate ownership and origin of contribution. Since this book has been introduced in good faith as a useful reference for UMTS tech- nology, the author does not take responsibility for any misuse or error while dealing Preface with the information provided. If for some reason some representations have been omit- ted due to time constraints or the dynamic changing process of the specifications, they will be revised and corrected for later reprints. Thus, the author welcomes any com- ments and suggestions for improvements or changes that could enhance further this contribution to UMTS. The chapters in this book cover specific design details of the building blocks in the UMTS air interface, in particular the physical layer. It addresses the technical part of the specification for both the FDD and TDD modes. On the other hand, it also introduces the key criteria for network dimensioning and deployment of 3G systems assuming an evolution from 2G mobile networks from the providers' point of view. To illustrate the progressive steps of UMTS standards such as the evolution towards predominant packet switching oriented communications, this book also introduces the 'All IP Core Net- work' architecture concept for mobile multimedia. Chapter 1 deals with concrete requirements for 3G mobile systems after summarizing the rapid growth of wireless communications and the Internet. It also outlines briefly enhancing technologies such as capacity increasing antennas, mult