Wireless security is a very important topic and attracting more and more attention from industry, research, and academia. There is a need for a comprehensive book to investigate and to summarize the recent advances in wireless communication network security. This book will serve the purpose to thoroughly investigate security issues in emerging wireless access communication networks. This book addresses the security for wireless communication networks. Unlike wired communication networks that have some degree of physical security, physical security in wireless communication networks is impossible to achieve on wireless links (because of the broadcast nature) and therefore security attacks on information flow are the most widespread. Modification of information is possible because of the nature of the channel and the mobility of nodes. The radio channel is harsh and subject to interference, fading, multipath, and high error rates. As a result, packet losses are common even without security threats. An opponent can make use of these natural impairments to modify information and also render the information unavailable. This book will address all these issues. Special attention will be paid to wireless specific issues, e.g., trade-offs between security and power consumption, adaptively changing security protocols in response to the radio channel, etc. The book can be used as a supporting textbook for students on Wireless Security courses, offering the fundamentals of tele-communication and mathematics and cryptographic techniques. This allows the reader to select one specific wireless network of interest after going through the basics of mathematics and cryptographic techniques.