wndw-ebook.pdf

Wireless Networking in

the Developing World

A practical guide to planning and building low-cost

telecommunications infrastructure

Wireless Networking in the Developing World

For more information about this project, visit us online at http://wndw.net/

First edition, January 2006

Many designations used by manufacturers and vendors to distinguish their

products are claimed as trademarks. Where those designations appear in

this book, and the authors were aware of a trademark claim, the designations

have been printed in all caps or initial caps. All other trademarks are prop-

erty of their respective owners.

The authors and publisher have taken due care in preparation of this book,

but make no expressed or implied warranty of any kind and assume no re-

sponsibility for errors or omissions. No liability is assumed for incidental or

consequential damages in connection with or arising out of the use of the

information contained herein.

This work is released under the Creative Commons Attribution-ShareAlike

2.5 license. For more details regarding your rights to use and redistribute

this work, see http://creativecommons.org/licenses/by-sa/2.5/

Contents

About This Book

Where to Begin

....................................................................................................................

Fitting wireless into your existing network

....................................................................................

Wireless networking protocols

......................................................................................................

Question & Answer

......................................................................................................................

A Practical Introduction to Radio Physics

...........................................................................................................................

Polarization

.................................................................................................................................

The electromagnetic spectrum

......................................................................................................

Bandwidth

...................................................................................................................................

Frequencies and channels

............................................................................................................

Behaviour of radio waves

.............................................................................................................

Line of sight

.................................................................................................................................

Power

..........................................................................................................................................

Physics in the real world

..............................................................................................................

Network Design

Designing the physical network

....................................................................................................

The logical network

......................................................................................................................

802.11 wireless networks

.............................................................................................................

Mesh networking with OLSR

.........................................................................................................

Estimating capacity

......................................................................................................................

Trafﬁc optimization

......................................................................................................................

Internet link optimization

.............................................................................................................

Antennas & Transmission Lines

..........................................................................................................................................

Waveguides

.................................................................................................................................

Connectors and adapters

..............................................................................................................

Antennas & radiation patterns

.....................................................................................................

Reﬂector theory

...........................................................................................................................

Ampliﬁers

....................................................................................................................................

Purpose of this book

What is a wave?

Cables

Practical antenna designs

.............................................................................................................

101

Networking Hardware

.............................................................................................................................

121

Choosing wireless components

.....................................................................................................

123

Commercial vs. DIY solutions

........................................................................................................

125

Professional wireless products

......................................................................................................

127

Building an AP from a PC

.............................................................................................................

133

Security

Physical security

..........................................................................................................................

146

Threats to the network

.................................................................................................................

148

Authentication

..............................................................................................................................

150

Privacy

........................................................................................................................................

156

Monitoring

...................................................................................................................................

163

Building an Outdoor Node

.................................................................................................................

171

Providing power

...........................................................................................................................

172

Mounting considerations

..............................................................................................................

173

Safety

..........................................................................................................................................

179

Aligning antennas on a long distance link

....................................................................................

180

Surge and lightning protection

.....................................................................................................

182

Solar and wind power

..................................................................................................................

184

Troubleshooting

......................................................................................................................

195

Proper troubleshooting technique

.................................................................................................

198

Common network problems

.........................................................................................................

199

Case Studies

.............................................................................................................................

209

Case study: Crossing the divide with a simple bridge in Timbuktu

.................................................

212

Case study: Finding solid ground in Gao

.......................................................................................

215

Case Study: Spectropolis, New York

..............................................................................................

218

Case study: The quest for affordable Internet in rural Mali

...........................................................

223

Case study: Commercial deployments in East Africa

......................................................................

230

Appendix A: Resources

.................................................................................................................

237

Appendix B: Channel Allocations

...................................................................................................

243

Wired wireless

Waterproof enclosures

Building your team

General advice

About This Book

This book is part of a set of related materials about the same topic: Wireless

Networking in the Developing World. While not all materials are available at

thetimeofﬁrst printing, these will include:

• Printed books

• A DRM-free PDF version of the book

• An archived mailing list for discussion of the concepts and techniques de-

scribed in the book

• Additional case studies, training course material and related information

For all of this material and more, see our website at http://wndw.net/

The book and PDF ﬁle are published under a Creative Commons

Attribution-ShareAlike 2.5 license. This allows anyone to make copies, and

even sell them for a proﬁt, as long as proper attribution is given to the

authors and any derivative works are made available under the same terms.

Any copies or derivative works must include a prominent link to our website,

http://wndw.net/. See http://creativecommons.org/licenses/by-sa/2.5/ for

more information about these terms. Printed copies may be ordered from

Lulu.com, a print-on-demand service. Consult the website ( http://wndw.net/ )

for details on ordering a printed copy. The PDF will be updated periodically,

and ordering from the print-on-demand service ensures that you will always

receive the latest revision.

The website will include additional case studies, currently available equip-

ment, and more external website references. Volunteers and ideas are wel-

come. Please join the mailing list and send ideas.

The training course material was written for courses given by the Association

for Progressive Communications and the Abdus Salam International Center

for Theoretical Physics. See http://www.apc.org/wireless/ and

http://wireless.ictp.trieste.it/ for more details on those courses and their ma-

terial. Additional information was provided by the International Network for

the Availability of Scientiﬁc Publications, http://www.inasp.info/ . Some of this

material has been incorporated directly into this book.

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