With advances in technology, a mobile device today is like a mini PC that provides voice and data services in the form of smart-phones. Phenomenal increase in data services which enable mobile communication access to critical aspects of human society/life has led to standardization of SAE/LTE (System Architecture Evolution/Long Term Evolution) by 3GPP and IEEE 802.16e/WiMAX. SAE/LTE is also known as Evolved Packet System (EPS). This book addresses the newer security issues that have arisen as a result of penetration of mobile communications and standardization. In particular, the book focuses on the latest security developments in 3GPP SAE/LTE and WiMAX. The intended audience for this book are mobile network and device architects, designers, researchers and students. The goal of the authors, who have a combined experience of more than 25 years in mobile security standardization, architecture, research, andeducation, is to provide the book's readers with up-to-date information about the architecture and challenges of EPS and WiMAX security.The book has six chapters; the first three chapters are intended to be introductory ones, and the remaining three chapters provide an in-depth assessment of security provisions. Chapter 1 provides a background to the Next Generation Mobile Networks (NGMN) activity and requirements. Chapter 2 provides an overview of security, telecommunication systems and their requirements.Chapter 3 provides some background information on standardization. Chapter 4 discusses the EPS (or SAE/LTE) security architecture developed by 3GPP, in particular, the authentication and key agreement method for SAE/LTE together with newly defined key hierarchy. This chapter also addresses the challenging aspects of SAE/LTE interworking and mobility with UMTS together withthe necessary key-exchange technologies. The focus of Chapter 5 is WiMAX (IEEE 802.16) security and provides an in-depth discussion of the WiMAX security requirements, the authentication aspects of PKMv2, and the overall WiMAX network security aspects. Chapter 6 briefly covers security for (i) Home(evolved)NodeB [H(e)NB is the Femto solution from 3GPP], (ii) Machine-to-Machine (M2M) security and (iii) Multimedia Broadcast and Multicast Service (MBMS) and Group Key Management.