Hi, Kaiying
Thanks for your comments.
Please see my response in
Red.
Thanks,
Yajun
发件人: Kaiying Lu <Kaiying.Lu@xxxxxxxxxxxx>
发送时间: 2026年1月9日 14:57
收件人: 程亚军 <chengyajun@xxxxxxxxxx>; STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx
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主题: [External Mail]RE: Discussion on 25/1924: Backoff Procedure after Switching Back to BSS PCH
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Hi Yajun,
Thanks for continuing the discussion.
I got your use case. But in this case, if the STA did not initiate a backoff before switching to the NPCA PCH, it has no suspending backoff to
resume after switching back to BSS PCH.
YC：Sure, I agree with this case.
“Resume” means there is already backoff on BSS PCH before performing NPCA operation.
As you mentioned the baseline rule, we only need to discuss whether the STA needs to perform/initiate
a new backoff procedure when switching back to BSS PCH immediately after performing a frame exchange on NPCA PCH.
YC: According to bn draft 1.0, the STA may resume backoff procedure when switching back to BSS PCH rather than
performing/initiating a new backoff. Additionally, I am confused about the case you mentioned that the STA switches back to BSS PCH
immediately after performing a frame exchange on NPCA PCH. The NPCA STA will switch back to BSS PC when the NPCA_TIMER expires instead of completing the transmission on NPCA PCH.
As you also mentioned the case that the STA has entered doze state before switching back to BSS PCH, since the STA has only one doze state no matter it is on BSS
PCH or NPCA PCH, it will not transmit anyway.
I think we can leave it to implementation.
YC：According to bn draft 1.0, the NPCA STA
SHALL RESUME the backoff procedure, which means the NPCA STA MUST do that. What I am concerned about is: what should the STA do when the STA switches to the BSS PCH and is in Doze state? This is the reason why I propose to include this exception.
Thanks,
Kaiying
From:
程亚军 <chengyajun@xxxxxxxxxx>
Sent: Thursday, January 8, 2026 10:54 AM
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Cc: shubhodeep.adhikari@xxxxxxxxxxxx；
<shubhodeep.adhikari@xxxxxxxxxxxx>;
Kaiying Lu <Kaiying.Lu@xxxxxxxxxxxx>;
kiseon.ryu@xxxxxxxxxxxxxx; Binita
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Yongho Seok <yongho.seok@xxxxxxxxx>
Subject: Discussion on 25/1924: Backoff Procedure after Switching Back to BSS PCH
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Hi, all
Let's consider the scenario shown in the image below.
When the STA and AP perform backoff on the BSS PC, if OBSS activity is detected, they switch to the NPCA PC. Then, the STA obtains TXOP and exchanges data with
the AP on the NPCA PC. After the date transmission is complete, the STA sends a frame with Power management subfield set to 1 to change its power mode. Upon receiving the ACK from the AP, the STA enters Doze state and can remain in Doze state after switching
back to the BSS PC.
In this case, if the STA is in Doze state when it switches back to the BSS PC, the STA will not resume
the backoff procedure that was in place before switching to the NPCA PC.
@Shubhodeep: I'm not sure if I've correctly remembered your question. In the case described above, the AP will resume
the backoff procedure, but the STA will not, because it is in Doze state.
@kaiying, please see the following description in the baseline
(P2173L51-Revmf1.2).
Based on this rule, the NPCA STA will resume backoff procedure when switching back to the BSS primarily channel even it have no data to transmit.
@Kiseon&Binita, I got your points, but the baseline didn’t take the NPCA operation which is a new
feature into account. In the baseline, if the STA successfully exchanges frames with its associated AP to change its power mode and then enters Doze state, it means the STA has accessed the channel and the backoff counter is zero.
However, the issue we are discussing is
whether the STA, when switching back to the BSS PC,
resumes the backoff procedure that was being performed on the BSS PC before switching to NPCA PC. This is a problem not encountered in the baseline. Therefore, we cannot simply refer to the baseline.
@Yongho,
for CID 4570, the comment is to add "if needed" at the end of this sentence. But in the baseline, A backoff procedure shall be performed immediately after the end of every transmission even
if no additional transmissions are currently queued. This means that even if there is no additional data to be transmitted, performing a backoff operation after each transmission is a mandatory procedure. Therefore, I chose to reject this comment rather than
revise it.
Please feel free to contact me if you have any comments.
BRs，
Yajun
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