On OBSS Interference

Consider the following scenario:

Two APs can hear each other. AP1 is set to use channel 36+40+44+48 (primary channel 36+40) while AP2 is set to use channel 44+48. Due to the nature of 802.11 and co-channel interference, AP1 cannot transmit while AP2 is transmitting.

In this scenario, the APs will forever dance the dance of CCI, waiting for the other to finish transmitting before taking over the medium itself. Wouldn’t it be better if instead of waiting, they could both transmit at the same time?

This is a scenario brought to you by 802.11ac, an infrequently discussed issue known as: Overlapping BSS (OBSS). OBSS is defines as two BSSs that, well, overlap, because their channel configurations occupy some of the same space.