Fun Facts About Wi-Fi - 2.4 GHz and 5 GHz
Fun Fact 1:
Signals don't actually interfere with each other
If you have 2 signals on the same frequency and they hit each other they don't actually interfere with each other. The "Interference" that is referred to is actually the result of a receiving radio hearing multiple signals at the same time which of course can confuse it, but is not the result of the signals effecting each other. A great example is the point to point links where you can have 2 links crossing each other, but not causing problems as although they cross paths, the receiving radios will not receive both signals.
Fun Fact 2:
If 2 signals are received at once, they cause a collision
This is not always the case. If there is enough of a Signal Strength difference than the lower strength signal can be viewed as noise by some vendors so that it doesn't effect the hight strength signal. This is no different to designing a network and inspecting the background noise and allowing for a reasonable SNR (Signal to noise ratio).
If you want to check out the video yourself then head over to: http://www.youtube.com/watch?v=V7M3ZLQIhOk