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Re: [STDS-802-11-TGBN] [External Mail]Re: [STDS-802-11-TGBN] Discussion on CID4434

Hi Yajun,

Thanks for the questions. Please see inline.

Best,
Sanket
From: 程亚军 <000038d07d12e9a7-dmarc-request@xxxxxxxxxxxxxxxxx>
Sent: Tuesday, April 7, 2026 11:22 PM
To: STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx <STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx>
Subject: [STDS-802-11-TGBN] 回复: [External Mail]Re: [STDS-802-11-TGBN] Discussion on CID4434

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Hi, Yanjun

 

I’m sorry, I don’t quite follow your question regarding the first PPDU and its type.

 

To clarify: once AP2 is granted the shared TXOP (or allocated time) from AP1, it is allowed to initiate transmissions within its own BSS. For instance, AP2 may transmit an SU PPDU to STA2, or an MU PPDU to multiple STAs (including STA2) simultaneously, depending on its buffer status.

 

 

 

Could you please clarify your concern regarding the specific PPDU type? I'm interested to know if you believe this would impact the behavior of AP2 or STA2.

 

Thanks

Yajun

发件人: Yanjun Sun <yanjunsunstd@xxxxxxxxx>
发送时间: 2026年4月7日 23:01
收件人: 程亚军 <chengyajun@xxxxxxxxxx>
抄送: STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx
主题: [External Mail]Re: [STDS-802-11-TGBN] Discussion on CID4434

 

[外部邮件] 此邮件来源于小米公司外部，请谨慎处理。若对邮件安全性存疑，请将邮件转发给misec@xxxxxxxxxx进行反馈

Hi Yajun,

 

In your example, what will be the type of the first PPDU from AP2 to STA2? What would be in the PPDU?

 

Thanks,

Yanjun



On Apr 6, 2026, at 6:53 PM, 程亚军 <000038d07d12e9a7-dmarc-request@xxxxxxxxxxxxxxxxx> wrote:

 

Hi Sanket，

 

CID4434 raised the interoperability issue between Co-TDMA and NPCA.

 

According to the current Resolution, I have the following concerns:

1.      To my knowledge, the current draft does not stipulate that the NPCA Minimum Duration Threshold must be greater than the Duration field in the Co-TDMA ICF. Is it your intention to introduce such restriction?

[Sanket] As I understand it, the NPCA Minimum Duration Threshold is at least 512 us. However, the NAV set by the Co-TDMA ICF expires at the end of the PPDU carrying the ICR frame. The duration of the PPDU carrying the ICR frame is small (less than 100 us), which is below the NPCA Minimum Duration Threshold.

 2.      Downlink transmission failure due to NPCA operation.

As illustrated in the following figure, once STA2 has enabled NPCA operations, it switches the NPCA primary channel at the beginning of the allocation phase. Consequently, if AP2 attempts to deliver DL PPDUs to STA2 during the allocation phase, the transmission will inevitably fail as STA2 is no longer operating on the BSS primary channel.

How can we ensure that NPCA STAs (such as STA2) remain on the primary channel until the end of the CO-TDMA allocation phase to avoid this transmission failure?

<image002.png>

[Sanket] In CID 4434, you describe a scenario in which a STA of a polled AP performs an NPCA switch following the Co‑TDMA ICF/ICR exchange and the third PPDU transmitted by the coordinating AP. It is unclear why STA2 would switch at the beginning of the allocation phase. An MOPLEN‑based NPCA STA would not switch due to the short NAV during the polling phase, while a PHYLEN‑based NPCA STA would have already returned to the BSS primary channel, since the coordinating AP sets the NAV to expire before the start of the MU‑RTS TXS Trigger frame.

Thanks

Yajun

发件人: Sanket Kalamkar <000033b8f79f2eb4-dmarc-request@xxxxxxxxxxxxxxxxx>
发送时间: 2026年4月5日 9:56
收件人: STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx
主题: [External Mail][STDS-802-11-TGBN] 11-26/316r0 uploaded

 

[外部邮件] 此邮件来源于小米公司外部，请谨慎处理。若对邮件安全性存疑，请将邮件转发给misec@xxxxxxxxxx进行反馈

Hi Alfred,

 

The document 11-26/316r0 is uploaded on the server. The document resolves 20 CIDs.

 

https://mentor.ieee.org/802.11/dcn/26/11-26-0316-00-00bn-lb291-cr-for-co-tdma-cids-part-5.docx

 

Co-TDMA TTT: Please let me know if you have any feedback on the document.

 

Best,

Sanket

 

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