Recently, a substantial body of work on security access in WLAN has appeared in the literature of security. This has provided impetus for the deployment of WLAN. As the investigators of many scientific research projects of the WLAN security, the authors realize that it is a difficult job to design and analyze security access protocols or systems in WLAN. This book is born under such a background. The aim of this book is to deal with the various aspects of the security access in WLAN, among which, the security access architecture, security protocols, security management and evaluation, etc., are studied in detail.