Clear Channel Assessment (CCA) - RF Cafe Forums

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jkhoo2989

Post subject: Clear Channel Assessment (CCA)-

Posted: Thu Mar 24, 2005 9:50 pm

Captain

Joined: Tue Mar 22, 2005 5:29 pm
Posts: 5

I found this in IEEE 802.11A Spec -
The start of a valid OFDM transmission at a receive level equal to or greater than the minimum 6 Mbit/s sensitivity (-82 dBm) shall cause CCA to indicate busy with a probability >90% within 4 µs. If the preamble portion was missed, the receiver shall hold the carrier sense (CS) signal busy for any signal 20 dB above the minimum 6 Mbit/s sensitivity (-62 dBm).

How do i intepreated "6 Mbit/s sensitivity (-82 dBm)". Does 6 Mbit/s means the data-rate? and what is this -82dBm.

How do i intepreted "any signal 20 dB above the minimum 6 Mbit/s sensitivity (-62 dBm)"?

Guest

Post subject: Re: Clear Channel Assessment (CCA)-

Posted: Mon Oct 24, 2005 11:29 am

6 Mbit/s means the phy layer transmission data rate... and -82 dBm means the recieved power level in dBm...so the receiver will be busy for a valid OFDM transmission at a receive level equal to or greater than -82 dBm.

If the preamble part of the packet has not been received due to some reason , say collision, in that case the sensitivity level is increased to -62 dBm...so the receiver will be busy for a valid OFDM transmission at a receive level equal to or greater than -62 dBm.

--
MohaMMad MuTTakin SiDDique, MSc. Engr
Communication Networks
University of Bremen, FB1
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jkhoo2989 wrote:

Posted 11/12/2012

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