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Hi Matthew,
Thank you for the work on this this CR document.
After reviewing the document, I have few comments.
4488
260.34
37.18.5
As the current d1.0 has no strict rule to require all the frame/PPDU exchange completed before NPCA_timer expires, so what if the STA is still undergoing PPDU reception/transmission when NPCA_timer expires? The current rule requires the STA to switch channel as long as the NPCA_timer expires, which indicates the termination the ongoing tx/rx PPDU if there is one. There should be additional rules to allow the ongoing PPDU to be completed when the NPCA_timer expires.
As comments, for the switching back to BSS primary rule, there should be additional rule to allow the behavior of such switching to be delayed until the ongoing PPDU is completed when the NPCA_timer expires.
Rejected – the existing NPCA_TIMER contains a value that will allow an NPCA STA to return to the BSS channel at the moment of the expiration of the BUSY medium on that channel. This allows the STA to be in the right place at the right time to resume accurate medium state tracking. If the STA is late in returning to the BSS channel, then it will lose synch with the BSS channel medium state. It is implicit that a STA that is performing a transmission/exchange on the NPCA channel must ensure that its TXOP/TX/RX is completed before the NPCA_TIMER runs out in order to ensure that all participants in the exchange will not be switching back to the BSS channel.
I believe that this comment should not be rejected, or a different rejection reason should be given.
- If a STA can implicitly insure the following: “It is implicit that a STA that is performing a transmission/exchange on the NPCA channel must ensure that its TXOP/TX/RX is completed before the NPCA_TIMER runs out in order to ensure that all participants in the exchange will not be switching back to the BSS channel.”, then it is preferred to have it explicitly defines as explained below.
- If a STA cannot implicitly insure it, then the resolution should be modified
While the transmitter is responsible for completing the TXOP before its own NPCA_TIMER expires, according to the current text, the transmitter is NOT responsible for completing the TXOP before the recipient’s NPCA_TIMER expires. As the recipient needs to switch back in time, it may be forced to terminate the ongoing TXOP prematurely. From an implementation and validation perspective, abnormal termination of active reception is highly complex, especially at varying stages (e.g., PPDU reception, SIFS or BACK transmission). It is preferable to explicitly require the transmitter to account for the recipient’s switching back delay , thereby simplifying the recipient implementation. This is also relevant for 6191 6192 (and for 4461 that was already passed SP)
5695
258.14
37.18.4
If a non-AP STA with a long NPCA switching delay becomes ready late on the NPCA primary channel, it may lose the carrier of previous transmissions (e.g., NPCA ICF, ICR, and/or PPDUs). In this case, a non-AP STA operating based on energy detection may attempt to transmit the uplink PPDU, potentially degrading overall performance. Therefore, it is necessary for the AP to determine the time at which non-AP STAs can start access simultaneously after NPCA switching and enforce this timing.
If a non-AP STA with a longer switching delay than the designated period attempts to operate the NPCA, it is advisable to block uplink transmissions.
As in the comment
Rejected – this sounds like ordinary contention, albeit the contention window for some STAs might be increased due to recipient unreadiness. Similar things can happen, for example, when a transmitter has a frame queued for a STA that has entered a DUO period of unavailability and must wait for it to exit the state, thereby losing the opportunity to transmit. This is not a problem, but is an observation that incentivizes implementers to make their switching delays as small as possible, as it is the devices with longer switching delays that will generally experience lower throughput as a result of being outcompeted by the faster devices .
The rejection reason does not address the specific issue raised in the comment. The comment raises the issue of a late switching STA interfering with an ongoing transmission on the NPCA channel due to CCA relying solely on energy detection. The rejection reason does not address this issue.
Best regards,
Rony
From: Matthew Fischer <matthew.fischer@xxxxxxxxx>
Sent: Friday, March 6, 2026 3:03 AM
To: STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx
Subject: [STDS-802-11-TGBN] 11-26-0328-06 NPCA DIFFICULT has been uploaded to the server, link inside
Alfred,
--
Matthew Fischer
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