The two standards seem to compete for the TV White Space (TVWS) because they are different at nearly whole protocol stack. For example the transmission power for IEEE 802.22 is 4W (36dBm) that is almost 80% greater than transmission power cap for IEEE 802.11af which is 100mW (20dBm). Additionally, there are also differences in reception sensitivity which is -97dBm for the former and -64dBm for the latter as well as differences at MAC. This heterogeneity could be problematic if the two standard want to compete for the TVWS.
I didn't come across any website/paper which discusses their co-existence yet. I will keep you updated if I find anything.
Interesting question though.
Interesting question. The two are targeting different use scenarios, though. IEEE 802.22 is to provide wireless broadband over a metro area (so-called "regional area nets"), whereas IEEE 802.11 nets are local, shared LAN hotspots, hopefully much shorter range.
So, my thinking is, to the extent that any of these white space schemes can be shown to work well, there's no reason to believe that 802.11af and 802.22 cannot coexist peacefully. I would think that you can pack more 802.11af nets than 802.22 nets over the same RF channel, in a given area, because co-channel interference will be less pronounced with the lower power WiFi than with the RANs. In either case, it will be a combination of spectrum sensing and geo-location database that will determine whether or not the space is "white." And the presence of an 802.22 RAN will be felt much further away, for other systems wanting to use that channel.
To me, 802.22 is more of a tall stick, long(ish) range, TV-like standard than 802.11af.
IEEE 802.22 is expected to operate at ranges up to about 30 Km, or even as far as 100 Km if special scheduling techniques are used at the MAC layer. And the main interference concern of 802.22 is TV stations and low-powered TV-related equipment, such as wireless microphones. Both 802.22 and 802.11af are meant to use geo database dependent info as one of their sources to determine whether or not they would interfere with a TV station.
But 802.11af is a short range scheme, like all 802.11, limited to 100 mW max transmit power. The big difference in range, between 802.22 and 802.11af, suggests to me that any "cooperative transmission" to be expected between the two will involve 802.11af backing off, and 802.22 only being capable of worrying about TV stations and TV microphones. An 802.22 base station having to transmit cannot be expected to worry about a potentially large number of 802.11af WLANs inside customer premises, throughout the 802.22 local region.
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