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Comparative Use of Unlicensed Spectrum Training materials for wireless trainers.

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Presentation on theme: "Comparative Use of Unlicensed Spectrum Training materials for wireless trainers."— Presentation transcript:

1 Comparative Use of Unlicensed Spectrum Training materials for wireless trainers

2 2 Goals ‣ To see the issues related with the use of a shared medium, like the unlicensed radio spectrum (specifically the 2.4 GHz ISM band). ‣ To identify the most common sources of interference when operating a WiFi network. ‣ To introduce software and hardware tools that can help identify sources of interference.

3 3 These considerations are important to keep in mind when using devices that operate using unlicensed spectrum. Sharing the air ‣ All devices must share the available radio bandwidth.Devices that use different protocols are typically unaware of each other.This competition leads to contention, retries, noise, dropped packets, delays, or static.The effect and amount of interference depends on how the devices make use of the spectrum.

4 4 Electromagnetic Spectrum Approximate range for WiFi

5 5 802.11 Channels

6 6 Non-overlapping channels: 1, 6, 11

7 7 Non-overlapping channels: others

8 8 Adjacent channel interference

9 9 Non-adjacent channel interference

10 10 802.11 b/g networks Bluetooth devices Cordless phones Video senders Baby monitors Which common communication devices operate at 2.4 GHz? Other 2.4 GHz communications devices 10

11 11 Bluetooth: frequency hopping

12 12 Cordless phones: wide channels

13 13 Video senders: extreme interference

14 14 Other sources of interference 14

15 15 Microwave Ovens

16 16 Power Supplies

17 17 Radar stations

18 18 Other high-power radio sources

19 19 Seeing the noise 19

20 20 http://www.metageek.nethttp://www.metageek.net/ Wi-Spy spectrum analyzer

21 21 Chanalyzer

22 22 Spectools

23 23 EaKiu

24 24 http://www.ubnt.com/ Ubiquiti AirView

25 25 Spectrum Analyzer A good spectrum analyzer is usually the best (and most expensive) tool for detecting sources of interference.

26 26 Using a spectrum analyzer

27 For more details about the topics presented in this lecture, please see the book Wireless Networking in the Developing World, available as free download in many languages at: http://wndw.net/ For more details about the topics presented in this lecture, please see the book Wireless Networking in the Developing World, available as free download in many languages at: http://wndw.net/ Thank you for your attention


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