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Wireless Networking in the Developing World

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Wireless Networking in
the Developing World
Second Edition
A practical guide to planning and building low-cost
telecommunications infrastructure
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Wireless Networking in the Developing World
For more information about this project, visit us online at http://wndw.net/
First edition, January 2006
Second edition, December 2007
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 property
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
responsibility 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.
© 2007 Hacker Friendly LLC, http://hackerfriendly.com/
This work is released under the Creative Commons Attribution-ShareAlike
3.0 license. For more details regarding your rights to use and redistribute
this work, see http://creativecommons.org/licenses/by-sa/3.0/
Contents
Where to Begin
1
Purpose of this book...........................................................................................................................2
Fitting wireless into your existing network.......................................................................................... 3
Wireless networking protocols.............................................................................................................3
Question & Answer............................................................................................................................. 5
A Practical Introduction to Radio Physics
9
What is a wave?................................................................................................................................. 9
Polarization......................................................................................................................................13
The electromagnetic spectrum........................................................................................................... 13
Bandwidth........................................................................................................................................ 15
Frequencies and channels................................................................................................................. 15
Behavior of radio waves................................................................................................................... 15
Line of sight......................................................................................................................................22
Power............................................................................................................................................... 24
Physics in the real world................................................................................................................... 26
Network Design
27
Designing the physical network......................................................................................................... 51
802.11 wireless networks.................................................................................................................. 54
Mesh networking with OLSR.............................................................................................................. 56
Estimating capacity...........................................................................................................................65
Traffic optimization...........................................................................................................................79
Internet link optimization................................................................................................................. 89
More information..............................................................................................................................93
Antennas & Transmission Lines
95
Cables.............................................................................................................................................. 95
Waveguides...................................................................................................................................... 97
Connectors and adapters.................................................................................................................100
Antennas & radiation patterns........................................................................................................ 102
Reflector theory.............................................................................................................................. 114
Amplifiers.......................................................................................................................................115
Practical antenna designs................................................................................................................116
Networking Hardware
135
Wired wireless................................................................................................................................ 135
Choosing wireless components........................................................................................................ 137
Commercial vs. DIY solutions...........................................................................................................139
Building an access point from a PC..................................................................................................143
Security & Monitoring
157
Physical security............................................................................................................................. 158
Threats to the network.................................................................................................................... 160
Authentication................................................................................................................................ 162
Privacy........................................................................................................................................... 167
Network Monitoring........................................................................................................................ 174
What is normal?............................................................................................................................. 203
Solar Power
211
Solar energy................................................................................................................................... 211
Photovoltaic system components..................................................................................................... 212
The solar panel............................................................................................................................... 217
The battery..................................................................................................................................... 222
The power charge regulator............................................................................................................ 229
Converters...................................................................................................................................... 231
Equipment or load.......................................................................................................................... 232
How to size your photovoltaic system.............................................................................................. 238
Cost of a solar installation...............................................................................................................246
Building an Outdoor Node
249
Waterproof enclosures.................................................................................................................... 249
Providing power..............................................................................................................................250
Mounting considerations................................................................................................................. 251
Safety.............................................................................................................................................257
Aligning antennas on a long distance link....................................................................................... 258
Surge and lightning protection........................................................................................................ 263
Troubleshooting
267
Building your team......................................................................................................................... 267
Proper troubleshooting technique................................................................................................... 270
Common network problems............................................................................................................ 271
Economic Sustainability
281
Create a Mission Statement............................................................................................................. 282
Evaluate the Demand for Potential Offerings...................................................................................283
Establish Appropriate Incentives...................................................................................................... 284
Research the Regulatory Environment for Wireless.......................................................................... 286
Analyze the Competition................................................................................................................. 286
Determine Initial and Recurring Costs and Pricing........................................................................... 287
Secure the Financing....................................................................................................................... 291
Evaluate the Strengths and Weaknesses of the Internal Situation..................................................... 293
Putting it All Together..................................................................................................................... 294
Conclusion...................................................................................................................................... 297
Case Studies
299
General advice................................................................................................................................299
Case study: Crossing the divide with a simple bridge in Timbuktu.................................................... 302
Case study: Finding solid ground in Gao.......................................................................................... 305
Case Study: Fantsuam Foundation's Community Wireless Network...................................................308
Case study: The quest for affordable Internet in rural Mali.............................................................. 319
Case study: Commercial deployments in East Africa......................................................................... 325
Case study: Dharamsala Community Wireless Mesh Network........................................................... 332
Case study: Networking Mérida State.............................................................................................. 334
Case study: Chilesincables.org......................................................................................................... 345
Case study: Long Distance 802.11.................................................................................................... 355
Appendix A: Resources
371
Appendix B: Channel Allocations
379
Appendix C: Path Loss
381
Appendix D: Cable Sizes
382
Appendix E: Solar Dimensioning
383
About This Book
This book is part of a set of related materials about the same topic: Wireless
Networking in the Developing World. The WNDW project includes:
· Printed books, available on demand
· Several translations, including French, Spanish, Portuguese, Italian, Arabic,
and others
· A DRM-free PDF and HTML version of the book
· An archived mailing list for discussion of the concepts and techniques
described 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 3.0 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 deriva-
tive 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/3.0/ 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 Associa-
tion for Progressive Communications and the Abdus Salam International
See http://www.apc.org/wireless/ and
Center for Theoretical Physics.
http://wireless.ictp.trieste.it/ for more details on those courses and their
material. 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. Additional ma-
terial was adapted from How To Accelerate Your Internet, http://bwmo.net/.
Credits
This book was started as the BookSprint project at the 2005 session of
WSFII, in London, England (http://www.wsfii.org/). A core team of seven
people built the initial outline over the course of the event, presented the
results at the conference, and wrote the book over the course of a few
months. Throughout the project, the core group has actively solicited con-
tributions and feedback from the wireless networking community. Add your
own feedback and updates to the WNDW wiki at http://wiki.wndw.net/.
· Rob Flickenger was the lead author and editor of this book. Rob has written
and edited several books about wireless networking and Linux, including
Wireless Hacks (O Reilly Media) and How To Accelerate Your Internet
(http://bwmo.net/). He is proud to be a hacker, amateur mad scientist, and
proponent of free networks everywhere.
· Corinna "Elektra" Aichele. Elektra s main interests include autonomous
power systems and wireless communication (antennas, wireless long
shots, mesh networking). She made a small linux distro based on slack-
ware geared to wireless mesh networking. This information is of course
redundant if one reads the book... http://www.scii.nl/~elektra
· Sebastian Büttrich (http://wire.less.dk/) is a generalist in technology with
a background in scientific programming and physics. Originally from Ber-
lin, Germany, he worked with IconMedialab in Copenhagen from 1997 until
2002. He holds a Ph.D. in quantum physics from the Technical University
of Berlin. His physics background includes fields like RF and microwave
spectroscopy, photovoltaic systems, and advanced maths.
He is also a performing and recording musician.
· Laura M. Drewett is a Co-Founder of Adapted Consulting Inc., a social en-
terprise that specializes in adapting technology and business solutions for
the developing world. Since Laura first lived in Mali in the 1990s and wrote
her thesis on girls education programs, she has strived to find sustainable
solutions for development. An expert in sustainability for ICT projects in de-
veloping world environments, she has designed and managed projects for a
diversity of clients in Africa, the Middle East and Eastern Europe. Laura
holds a Bachelors of Arts with Distinction in Foreign Affairs and French from
the University of Virginia and a Master s Certificate in Project Management
from the George Washington University School of Business.
· Alberto Escudero-Pascual and Louise Berthilson are the founders of
IT +46, a Swedish consultancy company with focus on information technol-
ogy in developing regions. IT +46 is internationally known for promoting and
implementing wireless Internet infrastructure in rural areas of Africa and Lati-
noamerica. Since 2004, the company has trained over 350 people in 14
countries and released over 600 pages of documentation under Creative
Commons License. More information can be found at http://www.it46.se/
· Carlo Fonda is a member of the Radio Communications Unit at the Abdus
Salam International Center for Theoretical Physics in Trieste, Italy.
· Jim Forster has spent his career in software development, mostly work-
ing on operating systems and networking in product companies.  He has
experience with several failed startup companies in Silicon Valley, and
one successful one, Cisco Systems.  After a lot of product development
work there, his more recent activities involve projects and policies for im-
proving Internet access in developing countries. He can be reached at
jrforster@mac.com.
· Ian Howard. After flying around the world for seven years as a paratrooper
in the Canadian military, Ian Howard decided to trade his gun for a computer.
After finishing a degree in environmental sciences at the University of Wa-
terloo he wrote in a proposal, "Wireless technology has the opportunity to
bridge the digital divide. Poor nations, who do not have the infrastructure
for interconnectivity as we do, will now be able to create a wireless infra-
structure." As a reward, Geekcorps sent him to Mali as the Geekcorps Mali
Program Manager, where he led a team equipping radio stations with wire-
less interconnections and designed content sharing systems.
He is now a consultant on various Geekcorps programs.
· Kyle Johnston, http://www.schoolnet.na/
· Tomas Krag spends his days working with wire.less.dk, a registered non-
profit, based in Copenhagen, which he founded with his friend and col-
league Sebastian Büttrich in early 2002. wire.less.dk specialises in com-
munity wireless networking solutions, and has a special focus on low-cost
wireless networks for the developing world.
Tomas is also an associate of the Tactical Technology Collective
http://www.tacticaltech.org/, an Amsterdam-based non-profit "to
strengthen social technology movements and networks in developing and
transition countries, as well as promote civil society s effective, conscious
and creative use of new technologies." Currently most of his energy goes
into the Wireless Roadshow (http://www.thewirelessroadshow.org/), a pro-
ject that supports civil society partners in the developing world in planning,
building and sustaining connectivity solutions based on license-exempt
spectrum, open technology and open knowledge.
· Gina Kupfermann is graduate engineer in energy management and holds a
degree in engineering and business. Besides her profession as financial con-
troller she has worked for various self-organised community projects and non-
profit organisations. Since 2005 she is member of the executive board of the
development association for free networks, the legal entity of freifunk.net.
· Adam Messer.  Originally trained as an insect scientist, Adam Messer
metamorphosed into a telecommunications professional after a chance
conversation in 1995 led him to start one of Africa's first ISPs. Pioneering
wireless data services in Tanzania, Messer worked for 11 years in eastern
and southern Africa in voice and data communications for startups and
multinational cellular carriers. He now resides in Amman, Jordan.
· Juergen Neumann (http://www.ergomedia.de/) started working with in-
formation technology in 1984 and since then has been looking for ways to
deploy ICT in useful ways for organizations and society. As a consultant for
ICT strategy and implementation, he has worked for major German and
international companies and many non-profit projects.  In 2002 he co-
founded www.freifunk.net, a campaign for spreading knowledge and social
networking about free and open networks. Freifunk is globally regarded as
one of the most successful community-projects in this field.
· Ermanno Pietrosemoli has been involved in planning and building com-
puter networks for the last twenty years. As president of the Latin American
Networking School, Escuela Latinoamericana de Redes "EsLaRed",
www.eslared.org.ve, he has been teaching wireless data communications
in several countries while keeping his base at Mérida, Venezuela.
· Frédéric Renet is a co-founder of Technical Solutions at Adapted Consulting,
Inc. Frédéric has been involved in ICT for more than 10 years and has worked
with computers since his childhood. He began his ICT career in the early
1990s with a bulletin board system (BBS) on an analog modem and has since
continued to create systems that enhance communication. Most recently,
Frédéric spent more than a year at IESC/Geekcorps Mali as a consultant. In
this capacity, he designed many innovative solutions for FM radio broadcast-
ing, school computer labs and lighting systems for rural communities.
· Marco Zennaro, aka marcusgennaroz, is an electronic engineer working at
the ICTP in Trieste, Italy. He has been using BBSes and ham radios since
he was a teenager, and he is happy to have merged the two together work-
ing in the field of wireless networking. He still carries his Apple Newton.
Support
· Lisa Chan (http://www.cowinanorange.com/) was the lead copy editor.
· Casey Halverson (http://seattlewireless.net/~casey/) provided technical
review and suggestions.
· Jessie Heaven Lotz (http://jessieheavenlotz.com/) provided several updated
illustrations for this edition.
· Richard Lotz (http://greenbits.net/~rlotz/) provided technical review and
suggestions. He works on SeattleWireless projects and would like to take
his node (and his house) off the grid.
· Catherine Sharp (http://odessablue.com/) provided copy edit support.
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· Lara Sobel designed the cover for WNDW 2nd Edition. She is an artist
currently living in Seattle, WA.
· Matt Westervelt (http://seattlewireless.net/~mattw/) provided technical re-
view and copy edit support.
Matt is the founder of SeattleWireless
(http://seattlewireless.net/) and is an evangelist for FreeNetworks worldwide.
About the solar power guide
The source material for the Solar Power chapter was translated and
developed by Alberto Escudero-Pascual. In 1998, the organization
Engineering without Borders (Spanish Federation) published the first version
of a handbook titled "Manual de Energía Solar Fotovoltaica y Cooperación al
Desarrollo". The handbook was written and published by members of the
NGO and experts of the Institute of Energy Solar of the Polytechnical
University of Madrid. By curiosities of life, none of the members of the
editorial team kept the document in electronic format and more editions were
never made. They have passed almost ten years from that very first edition
and this document is an effort to rescue and to extend the handbook.
As part of this rescue operation Alberto would like to thank the coordinators
of the first original edition and his mentors in his years at University: Miguel
Ángel Eguido Aguilera, Mercedes Montero Bartolomé y Julio Amador. This
new work is licensed under Creative Commons Attribution-ShareAlike 3.0.
We hope that this material becomes a new departure point for new editions
including new contributions by the community.
This second and extended edition of the solar power guide has received
valuable input from Frédéric Renet and Louise Berthilson.
Special thanks
The core team would like to thank the organizers of WSFII for providing the
space, support, and occasional bandwidth that served as the incubator for this
project. We would especially like to thank community networkers everywhere,
who devote so much of their time and energy towards fulfilling the promise of
the global Internet. Without you, community networks could not exist.
The publication of this work has been supported by Canada s International
Development Research Centre, http://www.idrc.ca/. Additional support was
provided by NetworktheWorld.org.