I'd be interested to know how 802.11ac is affected by DFS.
If you have an 80MHz channel and one channel out of four is hit by a radar blast, does the whole bonded channel go down and then maybe re-form as a 40MHz channel (avoiding just the single channel that was hit) ?
In 802.11ac, the channel map is well-defined. Unlike 11n, where you had to choose between 40-above and 40-below settings, the channels are always the same. 36 & 40 are always put together for a 40 MHz channel.
That's illustrated in this figure, where you can see 20/40/80/160 MHz channels on the map:
So, if you are using an 80 MHz channel, say 100 to 112, and you have a radar detection event on 108, then channel 108 is not usable. The best you can do is fall back to 40 MHz on 110 and 104, at least until you no longer detect radar on 108.
And this is the behavior you want! One of the main requirements for DFS was driven by the development of weather radar at airports. For more background, see this: http://blogs.aerohive.com/blog/the-wi... (one of my co-workers lived a few miles from one of the planes that crashed due to the lack of wind-shear detection!).
Matthew, I have seen the figure that you referenced in various IEEE documents and presentations and it usually says it illustrates the non-overlapping channels available for 802.11ac. However, it's not clear to me that it means you cannot have different combinations of channels other than those shown. For example, it may be possible to have a 40 MHz channel being formed using channels 40 and 44 instead of 36 and 40. Have you seen some document that indicates these are the only allowed channels? It would be helpful to have a reference.