Thanks for the research, Mark.
> Thus, I think the comment is correct in that Supported Channels
subelement should be included in the sentence at (REVme D4.0) P2501.35, which currently only references a Supported Channels element. However, the comment suggests _replacing_ “Supported Channels
element” with “Supported Channels subelement”. I think that is incorrect, as non-EDMG APs and PCPs (and EDMG APs and PCPs, too, for that matter) may receive such information in Supported Channels elements (not
subelements) in an Association Request.
When you say "non-EDMG APs" do you mean DMG APs (with the current wacky
definition of "non-EDMG"), or do you mean any AP that is not an EDMG AP?
Note 2501.35 is in (my emphasis):
11.8.8.6 Selecting and advertising a new channel
in a DMG BSS
The decision to switch to a new operating channel in a DMG BSS shall be made only by an AP or PCP. An AP
or PCP may make use of the information in received Supported Channels(#3510) elements and the results of
measurements undertaken by the AP or PCP and other STAs in the BSS to assist the selection of the new
channel. The algorithm to choose a new channel is beyond the scope of this standard.
The rules for non-DMG APs are in
11.8.8.2 Selecting and advertising a new channel in a
non-DMG infrastructure BSS
So your reference does not apply to all APs that are not EDMG APs.
At most, it applies to DMG APs that are not EDMG APs.
However, are
we sure such APs (potentially) use both Supported Channels elements
and Supported Channels
subelements?
Note for instance that the definition of the elements includes:
The First Channel Number field is set to the first channel (as defined in 17.3.8.4.3 (Channelization)) in a
subband of supported channels.
which cannot apply to DMG since the
channelisation is completely
different.
I do grant you that (Re)Assoc
Req does not have anything prohibiting
a Supported Channels element for a DMG STA (ditto for various TDLS
frames and mesh frames, but I can't remember whether DMG can be used
with TDLS or mesh).
I also see:
11.8.2.2 Providing supported channels upon association in a DMG BSS
An AP or PCP may advertise the regulatory domain in which it is located via a Country element in the DMG
Beacon, Announce, or Information Response frames if dot11MultiDomainCapabilityActivated is true.
When it (re)associates, the STA shall provide to the AP or PCP a list of channels in which the STA can operate.
The STA does this by including a Supported Channels element in the Information Request or (Re)Association
Request frames that it transmits. An AP or PCP can use the
supported channels list for associated STAs as an
input into an algorithm used to select a new channel for the BSS. The specification of this algorithm is beyond
the scope of this standard.
but also:
11.9.3.2 Selecting and advertising a new channel in an infrastructure
BSS
The decision to switch to a new operating channel and/or operating class in an infrastructure BSS is made
by
the AP when dot11DSERequired is false. An AP may make use of the information in the Supported Channels
element, Supported Operating Classes element, and the results of measurements undertaken by the AP and
other STAs in the BSS to assist the selection of the new channel and/or operating class. A method to make
the
decision and to select a new channel is defined in 11.8.8.2 (Selecting and advertising a new channel in a
non-
DMG
infrastructure BSS).
In summary, I'm still not sure!
Maybe we need to both add "or subelements"
and extend the definition of the element First Channel Number field not
to refer to OFDM PHY
channelisation?
And maybe also refer to DMG infra
BSSes in 11.9.3.2 and maybe other locations?
Thanks,
Mark
--
Mark RISON, Standards Architect, WLAN English/Esperanto/Français
Samsung Cambridge Solution Centre Tel: +44 1223 434600
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From: Mark Hamilton <mark.hamilton2152@xxxxxxxxx>
Sent: Monday, 11 September 2023 22:42
To: STDS-802-11-TGM@xxxxxxxxxxxxxxxxx
Subject: [STDS-802-11-TGM] Question on Supported Channels [sub]element, in REVme today (CID 4151)
--- This message came from the IEEE 802.11 Task Group M Technical Reflector ---
Mark/all,
From what I can find, an EDMG STA can send a Supported Channels subelement within the EDMG Capabilities in an Association Request. I think/assume that can be sent to an EDMG AP or PCP.
And, EDMG APs and PCPs operate in DMG BSSs (a special case of DMG BSS, which is “enhanced” (EDMG) but is a DMG BSS nonetheless). So, yes, I think an “AP or PCP” in a DMG BSS might use information it received in a Supported Channels subelement, as part of
its selection of a new channel to use.
Thus, I think the comment is correct in that Supported Channels subelement should be included in the sentence at (REVme D4.0) P2501.35, which currently only references a Supported Channels
element. However, the comment suggests _replacing_ “Supported Channels element” with “Supported Channels subelement”. I think that is incorrect, as non-EDMG APs and PCPs (and EDMG APs and PCPs, too, for that matter) may receive such information in
Supported Channels elements (not subelements) in an Association Request.
So, bottom line, subelements should be _added_, not _replacing_ elements, in that sentence.
If anyone disagrees, let me know, I could have missed some detail.
Mark
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