[STDS-802-11-TGBE] 答复: [STDS-802-11-TGBE] 22/552r2 Individual TWT

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Thanks Rubayet, it is correct. It works well as long as the TSF offset compensation is done.

发件人: Rubayet Shafin [mailto:r.shafin@xxxxxxxxxxx]
发送时间: 2022年5月6日 13:57
收件人: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
主题: Re: [STDS-802-11-TGBE] 22/552r2 Individual TWT

Hi Abhi,

Sure, no problem. I can share my understanding. Please see the below figures corresponding to the two cases you depicted.

Case-1 (TSF Offset = -20):

Case-2 (TSF Offset = +35):

Basically, TSF offset information will be used to adjust the timing reference for SP on link 2 with respect to that on link 1 (see 11-22/305). I really hope it clarifies things a bit.

@Ming, sorry to jump in here. Please feel free to share your thoughts if the pictures you have in mind is different than the ones I illustrated above.

Best

Rubayet

From: Abhishek Patil <appatil@xxxxxxxxxxxxxxxx>
Sent: Saturday, April 30, 2022 11:26 AM
To: Rubayet Shafin <r.shafin@xxxxxxxxxxx>; STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: RE: [STDS-802-11-TGBE] 22/552r2 Individual TWT

Hi Rubayet, Ming,

As requested, could you please draw the figures and provide an explanation for the timing/TSF on each link for the two scenarios that I described?

Regards,

Abhi

From: Rubayet Shafin <r.shafin@xxxxxxxxxxx>
Sent: Friday, April 29, 2022 8:07 PM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBE] 22/552r2 Individual TWT

WARNING: This email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.

Hi Ming,

Thank you for your contribution. I think the aligned SP is, in general, a good direction, and I don't see any technical difficulty in realizing it, especially since the group has already agreed on the TSF synchronization across multiple links. As Minyoung suggested, we can work on refining the text for better clarity.

Best

Rubayet

From: Abhishek Patil <appatil@xxxxxxxxxxxxxxxx>
Sent: Wednesday, April 27, 2022 11:32:05 AM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBE] 22/552r2 Individual TWT

Hi Ming,

Thank you for your email.

Could you please provide figures that show the timing information (i.e., the TSF values) at the start of each SP on that link. You need to consider two cases:

? Case 1 - TSF on transmitting link (L1) is greater than TSF on the other link (L2) - let's say TSF for L1 is 115 and TSF for L2 is 95 and Target Wake Time field along w/ other fields in the TWT parameter set indicates start of first SP at TSF=125, periodicity of 15ms and the SP duration is 5ms

? Case 2 - TSF on transmitting link (L1) is less than TSF on the other link (L2) - let's say TSF for L1 is 115 and TSF for L2 is 150 and fields in the TWT parameter set indicates start of first SP at TSF=125, periodicity of 15ms and the SP duration is 5ms

Regards,

Abhi

From: Ganming(Ming Gan) <000017d5b1a95115-dmarc-request@xxxxxxxxxxxxxxxxx>
Sent: Tuesday, April 26, 2022 2:19 AM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: [STDS-802-11-TGBE] 答复: [STDS-802-11-TGBE] 22/552r2 Individual TWT

Correct the following example

Taking the following fig for example, an AP MLD and a non-AP MLD setup two TWT agreements through one TWT element on link 1, the target wake up time is in reference to the TSF of link 1. If the target wake up time for link 1 is T, then target wake up time for link 2 is T-Delta, right? Here clock drift is ignored.

发件人: Ganming(Ming Gan) [mailto:000017d5b1a95115-dmarc-request@xxxxxxxxxxxxxxxxx]
发送时间: 2022年4月26日 17:13
收件人: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
主题: [STDS-802-11-TGBE] 答复: [STDS-802-11-TGBE] 22/552r2 Individual TWT

Hello Abhi

Could you elaborate why the case you mentioned can’t work. For the TSF topic, it is right, we discussed it several times. Fortunately, the group reached consensus on it. Each affiliated AP shall do synchronization on TSF, and can ensure the clock drift to be within +-30us. Moreover TSF offset is also provided. In this case, there is no issue to reference the TSF of any link .

Taking the following fig for example, an AP MLD and non-AP MLD setup two TWT agreements through one TWT element on link 1, the target wake up time is in reference to the TSF of link 1. If the target wake up time for link 1 is T, then target wake up time for link 1 is T-Delta, right? Here clock drift is ignored.

Best wishes

Ming Gan

发件人: Abhishek Patil [mailto:appatil@xxxxxxxxxxxxxxxx]
发送时间: 2022年4月26日 8:48
收件人: Ganming(Ming Gan) <ming.gan@xxxxxxxxxx>; STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
主题: RE: [STDS-802-11-TGBE] 22/552r2 Individual TWT

Hi Ming,

As I explained during the TGbe MAC call, the TWT element carries TWT Parameter set which contains fields whose values apply to the link for which the TWT is being setup. The parameter set includes the Target Wake Time field which provides timing information. This timing information is absolute time (and is expressed in TSF). Therefore, unless the TSF on all the links is identical (i.e., offset is 0), the proposal in doc 552 (to allow more than one bit in the Link ID bitmap set to 1) will not work. TGbe group has discussed TSF topic multiple times and has agreed that each AP of an AP MLD can have different TSFs.

If you are looking to setup overlapping individual TWTs, the existing spec (D1.5) allows you to do that by including more than one TWT element in the TWT setup frames. In this case, each TWT element carries a TWT parameter set with only one bit in the Link ID bitmap is set to 1 and the value in the Target Wake Time subfield is with respect to the TSF of the link matching the bit set to 1 in the Link ID bitmap. Relevant text can be found in 35.8.2 (Individual TWT agreements)

Hope this helps!

Regards,
Abhi

From: Ganming(Ming Gan) <000017d5b1a95115-dmarc-request@xxxxxxxxxxxxxxxxx>
Sent: Monday, April 25, 2022 12:42 AM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: [STDS-802-11-TGBE] 22/552r2 Individual TWT

Hello all

This email is for the discussion of Individual TWT issue. If you have comments, please let me know.

Best wishes

Ming Gan

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