The Internet Protocol Journal - Volume 9, Number 2

Book Review

Wireless Networking

Wireless Networking in the Developing World: A practical guide to planning and building low-cost telecommunications infrastructure, by Rob Flickenger et al., ISBN 1-4116-7837-0, 234 pages, Limehouse Book Sprint Team, January 2006. http://wndw.net

To quote from the book’s Website:

“This book was created by a team of individuals who each, in their own field, are actively participating in the ever-expanding Internet by pushing its reach farther than ever before. Over a period of a few months, we have produced a complete book that documents our efforts to build wireless networks in the developing world.”

Even though I don’t live and work in what is commonly regarded as part of the developing world, I found this to be a unique and informative book, as its practical descriptions of wireless networking have application in many environments.

Given the widespread availability of the raw materials of computers, open-source software, Wi-Fi equipment, various pieces of recycled kitchenware, scrap metal, and plastic, and a wealth of online information resources, it is possible to construct inexpensive high-speed wireless network systems almost anywhere these days. However, perhaps the most visible missing component of the overall picture, but also the most valuable, is a practical path through this wealth of information on how to construct wireless networks, and a path that is based on the recent experiences of others who have constructed cost-effective and practical wireless networks in communities in the developing world. This book sets out to meet that goal.

Organization

The book starts with a description of radio physics covering the basics of the topic. It builds upon this a description of the typical radio design trade-offs between information capacity and radio penetration, and describes the commonly encountered factors of absorption, reflection, diffraction, and interference. I found the practical approach to Fresnel zone calculation and the description of the relationship between distance and antenna height so well done that I was tempted to embark on the design of a neighborhood Wi-Fi straightaway!

The chapter on network design is somewhat of a hybrid section, covering a mix of physical layout of a wireless network and TCP/IP considerations. There were the usual summaries of IP address structure and an introduction to routing.

Study of the deployment of the Optimized Link State Routing (OLSR) protocol is, however, more detailed. This is a link state routing protocol that is open-source, supportable by Linux-based access points, and accommodates link quality metrics into the routing protocol metric. I found the consideration of the link budget in this section a useful practical description of the considerations that are unique to the wireless world, and the worked examples are excellent, together with some useful references to online tools. This chapter is relatively dense, and many topics are covered in a relatively short space. I suspect that an interested reader would want to drill down further before feeling confident enough to manage a service network, but some carefully chosen references to further reading are there, so that the reader can follow up this introductory material with more specialized references.

The section on antennas and transmission lines was also well-structured. I had heard of using cylindrical cans as Wi-Fi antennas, but knew little of the detail of how to actually do it. This book not only explains their design, but provides a step-by-step illustrated guide to their construction. It also provides a good description of what is involved in outdoor installation of wireless equipment. The consideration of commercial solutions as compared to the do-it-yourself approach was carefully presented, as was the section devoted to security considerations.

Aside from the technical considerations, the book also has some very interesting case studies of wireless networking projects, and was careful to include both success and failure stories. The issues in the developing world about combining technical capability with practical business solutions for communities that can be financially self-sustaining are indeed challenging, as the case studies show. They provide not only useful information about related experiences in setting up such network services, but also show how such projects can be assessed in a constructive manner.

Thoughtfully Written

Having spent some time working in this area myself as part of the ISOC Developing Countries Workshop training team, I have developed an appreciation of what constitutes truly useful and valuable training material, and this book is perhaps the best example I’ve seen yet. It is practical, helpful, technically accurate, and relatively complete in terms of coverage of material. Where the book does not dive into fine detail it provides useful references for further reading. The book is thoughtfully written in a simple non-nonsense style and does not hide behind technical jargon. Above all, it is material that can instill confidence that these networks can readily be built and operated by people like you and me.

I certainly would not call myself an expert after reading this book, but the next time a radio technician arrives in the office and starts talking about radiation patterns, front-to-back ratios, and the relative merits of omnis and yagis, at least I’ll have an idea of what he is talking about. Even better, I might even be able to show him my own modest efforts in do-it-yourself Wi-Fi networking by then!

Rectangular plot of a Yagi Radiation Pattern from Chapter 4 of the book

Publishing Model

This is not a conventional technical book in the sense that it does not come with a conventional technical book price tag. The book is published in a manner as to be readily available in the developing world, so an online publication model has been used here. The PDF is freely available under a Creative Commons Attribution-Share-Alike 2.5 license at http://wndw.net, and they have managed to squeeze all 254 pages into an impressively small 1.92-MB file. You can find related resources and ways that you can assist in this project at http://wndw.net.

—Geoff Huston, APNIC gih@apnic.net

Read Any Good Books Lately?

Then why not share your thoughts with the readers of IPJ? We accept reviews of new titles, as well as some of the “networking classics.” In some cases, we may be able to get a publisher to send you a book for review if you don’t have access to it. Contact us at ipj@cisco.com for more information.