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Performance Enhancementfor

Wi-Fi Communications

Presented byTanim M. Taher

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Study of Interference by MicroWave Ovens (MWO)

Why can I never connect to the internet during lunch time everyday?

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Experimental Analysis of MWO Signal

• The Residential MWO signal is synchronized with the 60 Hz AC line cycle, and it radiates in the positive half cycle only.

• The MWO signal has the main characteristics:

1. An AM-FM signal that is radiated for about 5-6 ms.

2. Transient signals before and after FM signal (~1ms).

“On” cycle of MWO

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Power Spectral Density of MWO Signal

•Most power is concentrated over the narrow frequency range (15 MHz) swept by AM-FM signal.

•There is power scattered over entire ISM band.

•The wideband power is due to transients.

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MWO Signal Model

“On” cycle of MWO

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MWO Signal Spectrogram

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Interference Spectrogram

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Interference Mitigated

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Experimental BER ResultsMWOMWO CaseCase BERBER

11 NO MITIGATIONNO MITIGATION 11.29%11.29%

22 NO MITIGATIONNO MITIGATION 1.661%1.661%

33 NO MITIGATIONNO MITIGATION 0.7315%0.7315%

11 MITIGATIONMITIGATION 00

22 MITIGATIONMITIGATION 00

33 MITIGATIONMITIGATION 00

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Interference Mitigation Technique

• Data transmission using 802.11 channel 1 (shaded areas are transient locations)

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Thank you!

Questions?

Tanim Taher (tahetan@iit.edu)