Hello Alfred and all,
Thank you very much for your comments and
questions on this (CF-end for an overlapping quiet interval) during the last
call.
I summarized our discussions
as follows:
- Q1: Does the current spec
already cover that operation?
- A1: I don’t think the spec clearly describes the operation. According to
the current spec, the TXOP holder can transmit CF-End in its own TXOP and
AP may further transmit CF-End after receiving CF-End. The related spec
text says “When a STA gains access to the
channel using EDCA and empties its
transmission queue, it may transmit a CF-End frame provided that the
remaining duration is long enough to transmit this frame.”. I don't think that the NAV set by quiet interval is its
own TXOP by EDCA.
-
- Q2: How does the AP know the
non-AP STA’s buffer status?
- A2: One option is AP can
transmit BSRP to the STA. AP can know no buffered traffic of the STA based
on the received BSR.
-
- Q3: What if the STA enters
the doze state for the quiet interval? In that case, the STA will not
receive CF-End.
- A3: In the baseline spec, I
did not see any description that the STA receiving quiet element
should enter the doze state for quiet intervals. The current spec just says
that the STA shall set its NAV based on the quiet interval. Although it’s possible by implementation, I don’t
think all STAs receiving quiet element will enter the doze state.
-
- Q4: Why do we need this
operation for overlapping quiet interval?
- A4: As I mentioned in above
A3, in the baseline spec, the STA receiving quiet element shall set its
NAV based on the quiet interval. It’s the purpose
of this operation. In 11.8.3 of REVme, “The NAV
shall be set by a non-VHT STA in the BSS for the length of the quiet
interval established by a Quiet element.”
-
- Q5: Do we need this
operation for 1TU overlapping quiet interval?
- A5: I agree that the
overlapping quiet interval is smaller than the normal quiet interval.
Basically, I think the spec should provide a mechanism that 11be AP can
transmit a CF-END during the overlapping quiet interval for resource
efficiency. Anyway, non-AP STAs will be able to have more transmission
opportunities through this operation. I expect CF-end procedure will be less than
200us. Then, we have 800us room. Note that whether(/when) AP transmits
CF-End depends on AP’s implementation.
- Q6: How about STA operation
for this?
- A6: The STA will follow the
baseline rule in 10.23.2.10. “In a non-DMG BSS,
a non-S1G non-HE STA(11ax) shall interpret the reception of a CF-End frame
as a NAV reset.”
Please let me know if I’m missing something. Any comments are welcome.
Thanks,
Jeongki
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