Le 26/08/2025 à 21:39, Johannes Berg a écrit :
On Tue, 2025-08-26 at 21:02 +0200, Pablo MARTIN-GOMEZ wrote:
This is wrong one way or another.
If we follow the 802.11 standard strictly [I'm going to use annex B's items so it is easier to follow], we are implementing EHTP3.3, so a non I ... don't think that's a good (correct?) way to phrase it. "Implement EHTP3.3" means you have 80 MHz support, which is required unless it's 20 MHz only STA. Here we're not really implementing 80 MHz support but saying that this is a requirement ...
Yes, I admit my email didn't have the proper phrasing and the use of Annex B items might have been inadequate and confusing. I was just trying to make a point by mail that was somewhat comprehensible. From your response, I get that you understood the point I was trying to get across, that is all that matters to me.
So that means that the strictly compliant approach would be to disallow a 40 MHz STA in the 6 GHz band and downgrade a 40 MHz STA to HT in the 5GHz band.
Looks like, yes. We should probably do that. These are corner cases anyway though, I don't think I've ever actually seen it happen.
For an AP working on the 5 GHz upper band, with DFS, it could end up with only 40 MHz bandwidth available after two radar detection. So yes, a corner case but still a case.
If we follow the 802.11 standard more liberally, we never enforced VHTP3.3 nor HEP3.3, so why begin now with EHTP3.3?
Nobody found bugs with the other ones? ;-)
Here it comes down to this actually _happening_ due some devices not allowing puncturing, and then we can't connect in the right way.
And this doesn't matter to HE, if we connect to an AP with puncturing in the 80 MHz as an 80 MHz HE station, then it _must_ have HE not punctured so only 40 MHz. Then if the HE actually moves to 80 MHz the puncturing in EHT must go away, and the HE is 80 MHz unpunctured which is fine for the HE STA, so there isn't even a bug.
The only bug would be if the downgrade happens for reasons other than puncturing (e.g. regulatory bands) but this is very unlikely in the first place.
So practically, the only issue we had with this is that for EHT and puncturing, and then the downgrade to HE basically fixes that issue and we can connect with HE even if we pretend we can do 80 MHz because as long as the puncturing is there, the AP has to use 20 or 40 MHz operation for HE (and lower of course.)
I agree though that this isn't really completely correct for HE/VHT if the downgrade were to happen for other reasons.
I made purely my remark regarding the standard compliance. If this change is the best course of action to fix the issue you describe, don't mind me. We'll discuss the compliance at another occasion.
However, I also don't think this is an argument _against_ fixing this issue for EHT. Clearly, for EHT there's the additional practical puncturing issue that matters. Yes, the APs rate scaling might be able to cope with it eventually, but if we remain connected with EHT and pretend we're 80 MHz when we're not, then we could get RUs in the unavailable part etc. and I think rate scaling would probably not deal with that well. This is true for HE as well, of course, but see above?
johannes
Best regards,
Pablo MG