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Hi Vishnu, Thanks for the contribution. I have some questions regarding the CIDs [10008][11594][13589]. I was trying to understand the motivation of the group link and how it works with the existing scheme. I assume you are saying that when a group link is notified,
the AP MLD still schedules the group addressed frames on all the links as in the current spec, but the non-AP MLD is only required to receive the group frames on the group link? Please correct me if my understanding is wrong. My question is - first, the AP MLD knows exactly whether the non-AP MLD is receiving group frames on one link or not. And the AP MLD’s behaviors are not changed with
a group link since it still schedules group frames on all the enabled links. So there is no need for non-AP MLD to tell AP MLD beforehand which link will be used to receive group frames.
Second, since currently the group addressed frames are buffered on all the links, if the non-AP MLD finds a better link to receive group frames based on different
situations, it is not helpful for it to use a predetermined group link. For example, when the non-AP MLD in EMLSR mode is operating on one link right before the DTIM beacon on this link, there is no need for it to switch to other links. Or like cases where
other links have better link condition than the group link. So why does the non-AP MLD need a group link to limit its flexibility which could possibly reduce its efficiency? Best regards, Yousi 发件人: Vishnu Ratnam <vishnu.r@xxxxxxxxxxx>
Hi Frank, Thank you for the question. In my opinion, it will not cause a failure of group addressed frame delivery or reception. Let us take an example. Say the previous
group link was link 1 and the new indicated group link is link 2, and say there is some delay at AP MLD in processing the group link change. The worst that can happen due to the processing delay is that an AP MLD will initiate a frame exchange sequence on
link 1 that overlaps with the beacon transmission time on link 2. Note that the spec text allows a non-AP MLD to not respond to the initial control frame in this case:
Thus this may cause a failure of the frame exchange initiated by the AP MLD on link 1 (since non-AP MLD may not respond to the initial control frame), but it will
not cause failure of reception of group addressed frames. Also given that these group addressed frames are transmitted at most once every TBTT, the likelihood of a processing delay at the AP (which is much smaller than a TBTT) to cause this issue is very unlikely.
Added to that, the group link is not expected to be changed very often. So in my opinion it is not a significant issue to warrant the need for a response frame. Please let me know if I missed anything. Regards, Vishnu From: Frank Hsu (徐建芳)
<frank.hsu@xxxxxxxxxxxx> Hi, Vishnu, Thanks for the feedback. Under the condition that group addressed frames are buffered in AP MLD, when AP MLD needs some processing time to update the group link indication (either
link change or termination), and during that period, the protection mechanism may still use previous information to proceed. Do you expect it will cause the group addressed frame delivery failure? BRs, Frank From: Vishnu Ratnam
<vishnu.r@xxxxxxxxxxx> Hi Frank,
As per the current CR document, the group link indication has no impact on the buffering of group addressed frames at the AP. The AP
still buffers group addressed frames on all the links (as in baseline spec). The indication of group link is to help minimize the number of links on which the AP needs to provide the “protection mechanism” of receiving group-addressed frames, by terminating
frame exchanges with an EMLSR or NSTR non-AP MLD. If I am not wrong, there was significant discussion in last round CC36 on the topic of whether group addressed frames need to be buffered
on all links (in the context of assigning sequence numbers) and I think the consensus was yes they should. Regards, Vishnu From: Frank Hsu
(徐建芳) <frank.hsu@xxxxxxxxxxxx>
Hi, Vishnu, Thanks for the document. I have a comment regarding the group link indication. You mentioned that
“this feature we don’t require a response frame from AP MLD”. I am considering a scenario where AP MLD buffers group addressed frames for a non-AP MLD based on the previous group link indication, say on link 1,
but before transmission, the AP MLD receives new group link indication which has different link indication from the previous one, say link 2. Depending on the design, AP MLD may not transmit those frames on link 2. It looks in this scenario, AP MLD needs to notify the non-AP MLD when the latest group link indication is going to be executed by the AP MLD. That means, a response from AP MLD is necessary, especially when the group link indication is changed. How do you think? BRs, Frank From: Vishnu Ratnam
<vishnu.r@xxxxxxxxxxx>
Dear all, Thank you for discussion during the meeting on CR doc 1335 (Group addressed frame reception in EMLSR/NSTR). I summarize below the comments
discussed on the call, and I look forward to additional feedback which was not discussed during the meeting:
Kindly let me know if I missed any of the comments on call. I would also appreciate if you can share feedback on CIDs which were not
discussed during the meeting: [10039][10863][12726][12728][12892][13588][13813]
and [10008][11594][13589]. Regards, Vishnu From: Vishnu Vardhan
Ratnam <vishnu.r@xxxxxxxxxxx>
Hi Xiangxin, Please find my responses inline. Regards, Vishnu From:
顾祥新 (Xiangxin Gu) <Xiangxin.Gu@xxxxxxxxxx>
Hi Vishnu, Thanks for your response. I make inline reply. From: Vishnu Ratnam
<vishnu.r@xxxxxxxxxxx>
Hi Xiangxin, Thank you for your comments and initiating the discussion.
[// Xiangxin Gu] If this mechanism is incorporated, there is no reason for
an AP MLD not to support this because it make the AP MLD easier to operating with EMLSR/EMLMR mode. So I don’t
understand why the capability indication is needed. [VR] Since there are conflicting opinions on this, let us discuss this during the call
to see what the group generally prefers. I would be happy to also collect other opinions of this as a response here to see which approach is more preferred.
[// Xiangxin Gu] Agree.
Further, an indication on whether there is services over group addressed frames
other than Beacon frames at non-AP MLD side is suggested. Because it is gainful that the duration of transmission of these frames doesn’t
need to be kept away from EML frame exchanges if no such services at non-AP MLD side. These frames occupy much more time than Beacon frame. Moreover, for EMLMR, in case some RF chains are kept at the STAs on other
links during the EML frame exchange, there is no need for EML frame exchanges to be away from the duration of transmission of group addressed frames on any links. For example, a multi-radio non-AP MLD with 3 affiliated STA1 and STA 2 and STA 3 setups link
1 and 2 and link 3 respectively with AP 1 and AP2 and AP3 affiliated with an AP MLD. All STAs support 2 SS. The non-AP MLD supports EMLMR mode, and has enabled EMLMR mode with 4 SS on link 1 and link 2 and link 3. The EMLMR mode does not use all RF chains
of the non-AP MLD. [VR] Regarding the indication of group addressed frame services, I see your point, But
I think the issue may be that group addressed management frames are also buffered and transmitted after the DTIM beacon, and they can be meant for all non-AP MLDs. So even if a non-AP MLD is not subscribed to a group addressed service, it may want to decode
the group addressed frames. Note that as of now there is no indication in TIM regarding whether the buffered group-addressed frames are data frames or management frames (there are some CIDs on that topic), so the non-AP MLD may not know if it can stop decoding.
Since many things regarding EMLMR are yet unclear, I removed the clause corresponding
to EMLMR from the document. There are other CIDs for EMLMR section that can be used to extend this procedure for EMLMR. I encourage you to bring this idea up during the resolution of those CIDs.
[// Xiangxin Gu] Yes, we have to make decision for the tradeoff. Actually
I doubt such flexibility make sense in practice. [VR] Since there are conflicting opinions on this, let us discuss this during the call
to see what the group generally prefers, I would be happy to also collect other opinions of this as a response here to preemptively see which option is more preferred. Regards, Vishnu From:
顾祥新 (Xiangxin Gu) <Xiangxin.Gu@xxxxxxxxxx>
Hi Vishnu, Thanks for the contribution document 22/1335r0, I have concerns:
From: Vishnu Ratnam
<vishnu.r@xxxxxxxxxxx>
Hi Alfred, Could you kindly add the following document to the MAC queue. It resolves 13 CIDs.
In addition, I have uploaded the 1201r1 which is a PDT (in place of 1201r0 which was a ppt). As discussed, could you kindly
move that document to the MAC Comment Resolution queue from the contribution queue? It resolves 1 CID.
Thanking you, Vishnu From: Edward Au
<edward.ks.au@xxxxxxxxx>
Dear Alfred and all, Revision 16 of the comment spreadsheet is posted: This version updated the status of selected CIDs after the motions on Wednesday, together with a few TTT assignments and PoC reassignment. Regards, To unsubscribe from the STDS-802-11-TGBE list, click the following link:
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