Channel bandwidth

[Anwar Safian]

Hi expert

1) I would like to know, why DSSS consist 22MHz wide? Why not 30, 50MHz and so on?

2) Channel 1 consist 2.401–2.423 GHz (2.412 +- 11MHz). Is that mean AP will send data using 2.401, 2.402, 2.403.......2.423 GHz simultaneously?

[JPavonM]

1) Original 802.11 standard used an 11 chip Barker code modulation, and for each data symbol, an 11 chip sequence is transmitted. The symbol rate is 1 Ms/sec, so the chip rate is 11 Million chips per second. This yields the resulting spectrum is +/- 11 MHz around the center frequency. See IEEE 802.11-2012 standard document for further information.

2) Use of sub-channels is only supported using OFDM transmissions.

HTH
-Jesus
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[Anwar Safian]

Hi Jesus

Thanks for you reply. One things I would like to clarify.

If channel 1 use 2.412 GHz, why it wont be 2412 Million chip per second?

[JPavonM]

Do not confuse chip bit rate with the modulated carrier frequency, which is 2.4 GHz.

HTH
-Jesus
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[Anwar Safian]

Hi Jesus

If I transmit a data using channel 1, what frequency that I will use? 

 2.401, 2.402, 2.403.......or 2.423 GHz?