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Re: [STDS-802-11-TGBE] 11-20-0066-03-00be-multi-link-tim



Hi Yunbo,

 

Thank you very much for your comments.

Please see my answers in line below.

 

BR,

Young Hoon

 

From: Liyunbo <liyunbo@xxxxxxxxxx>
Sent: Sunday, May 24, 2020 7:48 PM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: [STDS-802-11-TGBE] 11-20-0066-03-00be-multi-link-tim

 

Hi Young Hoon,

 

Thanks for sharing the presentation 0066. Since we didn’t have time to fully discussion, I use this e-mail thread to continue the discussion. I have two questions, would you please clarify, thanks.

 

1)       In side 3, you mentioned “The AP MLD needs to indicate which link the AP MLD has buffered BU to transmit, especially when different TIDs are mapped to different links”. In MLD, when the BU of one TID is mapping to multiple links, how AP decide which links to indicated in LMB? When the STA MLD receive the signaling, it still doesn’t know what TID the BU belongs to, so how the STA MLD decide to wake up on which links? I think may be a better way is to indicate the TID, so the STA MLD can clearly know it should wakeup on which links (base on the Traffic requirement, battery level, and other internal conditions). Because power save is an issue for at STA MLD side, not at AP MLD side, so it may be better to STA MLD to do the decision. During the teleconference, many people asked the similar questions in the chat window.

[YKWON] As I mentioned during the call, indicating TID instead of link can also be another option. But, the issue is that overhead. Due to overhead limit I would expect that one bit indication for each TID is too much, and thus, a set of TIDs may need to be grouped together for the indication. In this case, as there’s still uncertainty which TID to be used, similar issues are still there. We can certainly have further discussion on how to indicate TID/link when we first agree on the first step of having per-MLD level AID.

 

2)       In your design, each legacy STA  also needs to use 3 bit in LMB subfield. So in a scenario that only a small percent of STAs are EHT MLD, AP needs to still need to allocate 3 bits for each legacy STA in LMB subfield. It will be a large overhead. It has similar issue for STA MLD that only mapping on one or two links.

[YKWON] The way I showed in this slides deck is just an example of doing TID to link mapping, and there’s other ways of improving/optimizing the overall performance on link indication side. For example, an AP MLD can assign AIDs greater than a threshold for non-AP MLDs (AID for legacy STAs can be assigned to be less than the threshold in this case), and the AP MLD indicate the LMB only for those STAs that AID is greater than the threshold. I didn’t elaborate on the link mapping side a lot as we think at least in R1 the most common operation scenario is the case that all TIDs are mapped to all links.

 

 

Regards,

Yunbo


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