Can someone explain or reference documentation that explains in detail what happens when APs have the same channel overlap? I realize there will be collisions, but how determental is it to performance if part of the coverage area overlaps on the same channel?
Signals on the same channel (no matter what the origin) will look like noise to the AP and client. Since the useable signal strength is signal minus noise, a second AP on the same frequency will decrease effective range for all devices.
You could easily determine the quantitative impact (at least for line of sight signals) by plotting the signal strength in dBm.