Wireless Networking in the Developing World Computer Science Networking Wireless Networking

Where to Begin:Purpose of this book, Fitting wireless into your existing network, Wireless networking protocols >>

Wireless Networking in

the Developing World

Second Edition

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

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.

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

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

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

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

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.

· 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.

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