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Co-channel interference vs SNR


1) If a wireless client can see AP "A", to which it is associated, at -40dBm and AP "B" on the same Chan. at -70dBm, is "B" seen as co-channel interference by the client and so CCA (Clear Channel Assessment) concludes that the chan. is not free for it to Tx to AP "A" if AP "B" is Tx'ing?

2) Is it correct to say that the client will work smoothly with AP "A" because the SNR is 30dB? I think this is false - right, because the 'noise' in this case is not random noise but 802.11 traffic which CCA responds to - right?

The reason for choosing -70dBm is that this is a typical Rx'er sensitivity for 54Mbps data rate for various WiFi interfaces.

3) Similarly, if AP "A" can hear AP "B" at -70 (still assuming they are on the same channel) will this be seen as co-channel interference and neither AP will Tx while the other one is Tx'ing - right?

4) would you think that the AP Tx powers are too high in the above scenario?

Any clarification would be much appreciated.


Re: Co-channel interference vs SNR

1. The CCA mechanism reports that the channel is busy, based on the default value of the client adapter firmware.REfer URL SNR always corresponds to Signal to background RF noise. Typically right from 20 DB is a good SNR for the link to be Stable.

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