Extending WiFi

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Extending WiFi

• By Daniel Johnson

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IEEE 802.11

• Standards
• 802.11 - 2Mbps, 2.4GHz
• 802.11B - 11Mbps, 2.4GHz
• 802.11G - 54Mbps, 2.4GHz
• 802.11A - 54Mbps, 5GHz

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How to extend range

• High gain antenna on an Access Point
• High gain antenna on a WiFi adaptor
• Signal Amplifiers

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Types of antennas

• Omidirectional
• Vertical Omni
• Ceiling Mount
• Directional
• Backfire
• Yagi
• Panel
• dish type

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Why

• Bridge 2 buildings with a high speed link
• Connecting to distant APs
• Improving signal quality of a link
• Improving throughput of a link

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Things to know

• 3dB increase 100 increase in signal
• FCC limitations
• Indoor - 2 watts EIRP
• Outdoor - 1 watt EIRP
• Point to point systems - 4 watts EIRP
• EIRP - Equivalent Isotropically Radiated Power
• From my understanding
• With a 4 watt EIRP on a 6dBi antenna(1w before
  dish.) FCC allows a 3 dBi increase on the dish
  with a 1dBi decrease on the amplifier

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WRT54G

• Cheap 40
• 54Mbps 802.11G
• WEP, WPA, WPA2, QoS
• Removable 2.5dBi Antennas
• Hacked firmware
• Variable transmission power (21mw to 84mw)
• Improved firewall
• Telnet
• 13 wireless channels
• Bridge mode

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Unamplified 125 Mile shot

• Defcon WiFi shootout 2005
• 125 Miles
• Full 11Mbps on 802.11b for 3 hours
• 12 Satellite dishes

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Base Camp to IFiber
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Dishes used
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Sources

• http//www.wifi-shootout.com
• http//earth.google.com
• http//www.wwc.edu/frohro/Airport/Primestar/Prime
  star.html
• http//www.netstumbler.org
• http//www.linksysinfo.org
• http//www.zytrax.com/tech/wireless/calc.htm
• http//maisonbisson.com/blog/post/10296
• http//www.wi-fiplanet.com/tutorials/article.php/1
  428941
• http//www.usbwifi.orcon.net.nz
• http//www.radiolabs.com/Articles/wifi-antenna.htm
  l