LaNWiFi.NeTWorld's Wireless Technology Center // Wireless For Freedom.

          Wireless Mesh Networks (WMNs) are one of the key technologies which will dominate wireless networking in the next decade. They will help to realize the long-lasting dream of network connectivity anywhere anytime with simplicity and low cost. Accordingly they will play a major role within the next generation Internet. Their capability for self-organization significantly reduces the complexity of network deployment and maintenance, and thus, requires minimal upfront investment.

          These networks consist of simple mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. The integration of WMNs with other networks such as the Internet, cellular, IEEE 802.11, IEEE 802.15, IEEE 802.16, sensor networks, etc., can be accomplished through the gateway and bridging functions in the mesh routers. Mesh clients can be either stationary or mobile, and can form a client mesh network among themselves and with mesh routers. WMNs are anticipated to resolve the limitations and to significantly improve the performance of ad hoc networks, wireless local area networks (WLANs) wireless personal area networks, (WPANs), and wireless metropolitan area networks (WMANs). These networks deliver wireless services to a large variety of applications in personal, local, campus, and metropolitan areas.

          In the fall of 2003 we started to work on our survey paper “A Survey on Wireless Mesh Networks” which appeared in March 2005 issue of the Computer Networks (Elsevier) journal with a much shorter and more concise version appearing in the IEEE Communication magazine in September 2005. Note that, over the years, both of these papers were among the top ten downloaded papers within Elsevier and IEEE Communication journals. As we were writing the survey paperwe realized that the paper could be converted into a textbook because of the future promise of this technology. However, the field was not mature and there was not enough material to create a textbook at that stage. This, of course, has changed over the past five years. These networks have undergone very rapid progress and have inspired numerous deployments. Research has been accelerated all around the world and several companies have already been offering products to the market, while other companies have started to deploy these networks in various application scenarios. Despite several advances in wireless mesh networking in recent years, many research challenges still remain. The research is being conducted in a very speedy way worldwide and a very large number of papers already exist in the literature and the race is still on to advance this technology. In close interaction with students, researchers, and engineers, we realized that the time had come to publish this book which is targeted at teaching graduate students, stimulating them for new research ideas, and providing academic and industry professionals with a thorough overview and in-depth understanding of the state-of-the-art in wireless mesh networking and to indicate how they can develop new ideas to advance this technology as well as support emerging applications and services. The book will fill the gap for a comprehensive coverage of all research results on this topic published these past few years. The book covers many published research results including the authors’ own contributions as well as all the standardization committee decisions in a cohesive and unified form. The contents of the book follows the TCP/IP protocol stack starting from the physical layer and covering each protocol layer in detail. Functionalities and existing protocols and algorithms for each layer are covered in depth. The aim is to teach the readers what is already available and how these networks can be further improved and advanced by pointing out open research challenges in each chapter.

          Chapter 1 gives a comprehensive introduction toWMNs, including network architectures, characteristics, critical design factors, and typical application scenarios. Chapter 2 studies advanced physical techniques for WMNs, such as adaptive modulation and coding, multiantenna systems, multi-channel systems, multi-radio systems, and software radios. Chapter 3 presents and compares various medium access control (MAC) protocols forWMNs, ranging from carrier-sense multi-access with collision avoidance (CDMA/CA) variants, TDMA based MAC, CDMA based MAC, to multiple multi-channel MAC protocols. Chapter 4 is dedicated to routing protocols forWMNs. Various routingmetrics forWMNs are investigated and compared. Different categories of routing protocols are also presented. Chapter 5 introduces the principles of different basic transport protocols and then investigates various transport protocols proposed for multi-hop wireless networks including WMNs. Chapter 6 looks into the security issues. Security mechanisms specified in IEEE 802.11 and 802.16 are first presented, followed by a detailed study of security protocols for ad hoc networks and WMNs. Chapter 7 discusses different protocols that control and manage WMNs, which include topology management, power management, mobility management, and network synchronization. Chapter 8 is focused on capacity analysis. Different analytical methods proposed to derive wireless network capacity are presented, and different capacity bounds are compared. The results and limitations of existing capacity bounds for WMNs are also discussed. Chapter 9 studies cross-design mechanisms across different protocol layers of WMNs. Limitations and strategies for cross-layer design are also pointed out. Chapter 10 surveys standards that have been specified or standards drafts that are being specified for WMNs. In particular, the latest standardization results in IEEE 802.11s, 802.15.5, 802.16 mesh mode, and 802.16 relay mode are presented. In all these chapters, open research problems have been pointed out and some potential solutions have also been discussed. It is a major task and challenge to produce a textbook. Although the authors usually have the major burden, there are several other key people who help to publish a book. The foremost thanks go to Birgit Gruber from John Wiley and Sons who initiated the entire idea of writing this book. Her incredible persistence, patience and passion helped to achieve our objective. Several other colleagues, Sarah Tilley, Anna Smart, Sarah Hinton, Rowan January, Joanna Toothill, and finally Tiina Ruonamaa at John Wiley and Sons, have been incredibly helpful and patient. Their assistance, ideas, dedication, and support for the creation of this book will always be greatly appreciated. We also thank several individuals who directly or indirectly contributed to our book. In particular, our sincere thanks go to Cagri Gungor, Stefano Avallone, Claudio Cicconetti, Marco di Felice and Guomei Zhou for their help. Our families sacrificed the most during the creation of this book. No words can express our appreciation and love for their enormous support.