With the advance of wireless networks, building reliable and secured network connections is becoming extremely important. On the other hand, ad hoc networks become especially important and have many useful applications. The primary focus of this book is to present these two hot and rapidly evolving areas in wireless networks. Security and scheduling/routing in wireless networks remain challenging research problems due to the complexity involved. How to develop more efficient and reliable wireless networks remains a hot research area. It is this realisation that has motivated the editing of this book. The goal of the book is to serve as a reference for both security in wireless networks and channel access, scheduling, and routing in ad hoc networks. In this book, the authors review important developments and new strategies for these topics. Important features and limitations of methods and models are identified. Consequently, this book can serve as a useful reference for researchers, educators, graduate students, and practitioners in the field of wireless networks. This book contains 14 invited chapters from prominent researchers working in this area around the world. All of the chapters not only provide novel ideas, new analytical models, simulation and experimental results and handful experience in this field, but also stimulate the future research activities in the area of design and analysis of wireless networks.