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WirelessNetworkingin
theDevelopingWorld
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/
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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
Traf fi c 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
Re fl ector theory
..............................................................................................................................
114
Ampli fi ers
.......................................................................................................................................
115
Practical antenna designs
................................................................................................................
116
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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
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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
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