On Thu, 2018-09-20 at 12:27 +0200, Simon Wunderlich wrote: > On Thursday, September 20, 2018 11:21:16 AM CEST Johannes Berg wrote: > > On Tue, 2018-09-18 at 16:16 +0200, Simon Wunderlich wrote: > > > Operating on a DFS channel doesn't mean we can't leave it for a short > > > time - actually, some features like off-channel CAC work by leaving the > > > operation channel to check other channels for availability (although > > > off-channel CAC isn't implemented in mac80211). In our case, we want to > > > use mesh while doing background surveys on other channels from time to > > > time. > > > > Actually ... as far as I can tell it *does* mean that, at least > > currently for FCC. > > > Mhm. I remember you said that before. But I can't find references for it. I > checked the FCC 15.407 document [1] but couldn't find anything in favor or > against that. Same for the measurement procedures [2]. I also couldn't find > off-channel CAC in FCC, which I used for my argument in ETSI: > > In ETSI 301 893 [3] they talk about non-continuous checks for off-channel CAC > (in 4.2.6.2.3, second paragraph) and continuous period for CAC (4.2.6.2.2.2, > first paragraph). Continuity is not mentioned for in-service monitoring > (4.2.6.2.4), but off-channel CAC could only work when continuity is not > required. > > I'd appreciate if you (or someone else) can point me to where it's stated that > we can't leave the channel for the a short time. I'm assuming that we are back > fast enough to ensure the required detection probability. I still don't have a document, but we spoke about it at the wireless workshop and Jouni agrees that this is an absolute no-go for FCC, while allowed for ETSI. I guess you can make it depend on the radar domain information. johannes
