**Meet the editor**

Dr Song Guo received the Ph.D. degree in computer science from the University of Ottawa, Canada in 2005. He is currently a Senior Associate Professor at School of Computer Science and Engineering, the University of Aizu, Japan. His research interests are mainly in the areas of protocol design and performance analysis for computer and telecommunication networks, presently

focusing on network modeling, security analysis, cross-layer optimization, and performance evaluation of wireless ad hoc and sensor networks for reliable, energy-efficient, and cost effective communications.

Dr Guo is a senior member of IEEE and a member of ACM. He serves in many international journal editorial boards, including the prestigious IEEE Transactions on Parallel and Distributed Systems and Wireless Communications and Mobile Computing.

## Contents

#### **Preface XI**



## Preface

A wireless local area network (LAN) is a data transmission system designed to provide network access between computing devices by using radio waves rather than a cable infrastructure. Wireless LANs are designed to operate in a small area such as a building or office complex. The past two decades have witnessed starling advances in wireless LAN technologies that were stimulated by its increasing popularity in the home due to ease of installation, and in commercial complexes offering wireless access to their customers. This book presents some of the latest development status of wireless LAN and provides an opportunity for readers to explore the problems that arise in the rapidly developed technologies in wireless LAN.

This book consists of a number of self-contained chapters. Chapter 1 proposes various sum-product decoding methods for the punctured convolutional codes for the IEEE802.11n wireless LAN. It aims at providing high speed decoder by exploiting the higher degree parity check polynomial. The proposed sum-product decoding schemes achieve better performance than the conventional method with much reduced complexity. Chapter 2 theoretically analyzes the medium access control (MAC) layer throughput with distributed coordination function (DCF) protocol in the IEEE 802.11b/a/g/n-based wireless LANs under a fading channel model. Chapter 3 studies the stability region of the enhanced DCF (EDCF) MAC protocol under various mobility levels. Chapter 4 provides a survey of the main techniques introduced to improve quality-of-service (QoS) performance in wireless LANs. It represents the state of the art about current studies on how to preserve QoS in contention-based EDCA IEEE 802.11e networks under heavy loads. Chapter 5 proposes a framework for interaction between real and virtual users in hybrid shared space, in which a QoS adaptation mechanism is implemented for networks with bandwidth limitation. Finally, Chapter 6 proposes an indoor optical wireless LAN system using spacedivision-multiplexing (SDM) and wavelength-division-multiplexing (WDM) techniques. It presents the fabrication details of a dedicated complimentary-metaloxide-semiconductor (CMOS) image sensor to realize a compact, high-speed, and intelligent optical wireless LAN.

In summary, the topics on physical layer, MAC layer, QoS and systems included in this book are expected to benefit both practitioners working in wireless LAN systems

#### XII Preface

and researchers as well as graduate students with interest in this area. The editor is grateful to all authors for their contributions to the quality of this book. The assistance of reviewers for all chapters is also greatly appreciated. The University of Aizu provided an ideal working environment for the preparation of this book. The editor also appreciates the support of publishing process managers of InTech.

**Song Guo** 

Senior Associate Professor, School of Computer Science and Engineering, The University of Aizu, Japan
