Over the last decade, wireless networks have experienced significant growth due to the proliferation of mobile devices and new development of radio technologies. Since the very beginning, security for wireless communication networks has always been regarded as a critical issue. In recent research frenzy on 5G and V2X communications, security plays a pivotal role as wireless Internet access serves as critical infrastructures to facilitate the digital transcations. This book timely provides a comprehensive introduction to the security in wireless communication networks, with respect to not only general concepts, but also practical principles and cases in specific wireless communication systems. This book covers a wide range starting from the general wireless communication network architecture and basic concepts of network security to the mathematical background and practical techniques, and further to the specific security issues in different wireless networks, such as WLAN, LTE, 5G, etc. Comprehensively covering the security issues, security mechanisms, design principles, and techniques in wireless communication networks. The book intends to be a self-contained and one semester textbook on wireless security for either undergraduate senior level or graduate level courses. This book can also serve as a reference for practitioners and researchers in the field to get an idea of the current and future research focus in the emerging wireless security area.