Forum

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?

I'm assuming AP "B" is passing data to another client (client x). And we are talking not just beacons, as the beacons are so short they probably would never interfere much with AP "A".
That begs the question, where is the client x that "B" is talking to? Is it at the maximum range of "B", far from client a? which may cause AP "A" to get a weak signal from client x. Is client X recieving data or sending data? If sending data, AP B will be transmitting less than client x, as it will only be doing acks to the data as it recieves data. :)