Hi Chunyu,
For me, the behaviors described in your examples are unfair for all other STAs that want to make UL and/or P2P transmissions but are not registered to this rTWT. The AP uses a reserved
time period for latency sensitive data flows (rTWT SP) for other goals. The rTWT SP is reserved for registered STAs to transmit their latency sensitive data flows first and secondly others flows if some bandwidth remains. If you don’t apply these rules, you
break the main goal of the restricted TWT and the restricted TWT will become a TDM for a short number of STAs with no constraints.
In your example 1, if the AP wants to solicit STA1 & 2, it must reserve some bandwidth only on the appropriate bands. The other bands must remain free (i.e standard EDCA medium access).
That’s the reason why the rTWT SP doesn’t have to be too long to avoid abuses from registered rTWT STAs or the AP and to ensure global fairness for all STAs of the cell.
Regards.
Patrice
From: Chunyu Hu <chunyuhu07@xxxxxxxxx>
Sent: mardi 7 décembre 2021 16:59
To: NEZOU Patrice <Patrice.Nezou@xxxxxxxxxxxx>
Cc: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBE] Call for review of restricted TWT CR doc 11-21/1802
Thanks for your suggestion. I want to align with our understanding and revise accordingly.
In a setup with one AP and three STAs: STA1, STA2 and STA3 (they are of different devices). AP and STA1 operate at bw 160MHz, STA2 and STA3 operate at bw 80MHz.
STA2 and STA3 are members of a r-TWT schedule. STA1 is not. During a SP of the schedule, in the first DL PPDU, AP transmits to STA2+STA3 in an OFDMA PPDU and there are still more packets for STA2 and STA3. But AP also has packets for STA1.
In the same, first PPDU, do you think AP can also allocate the RU in secondary 80MHz to STA1 and transmit to STA1?
Similar to above, one AP and three STAs: STA1, STA2 and STA3. AP operates with TX/RX NSS=4. STA1 operates with TX/RX NSS=4, STA2 and STA3 operate with TX/RX NSS=1. STA2 and STA3 are r-TWT members, STA1 is not. In the first DL PPDU that
AP transmits in a r-TWT schedule, AP uses MU-MIMO and includes packets to STA2 and STA3, and there are still 2 SS unused. In this MU-MIMO PPDU, do you think AP can allocate the rest 2 SS resources to STA1 and include packets to it?
Hi Chunyu,
Thanks for your additional explanation. Please see my response below.
[Quote start] Copy from previous emails echanged:
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On p.5 l.28, a NOTE enables the scheduling AP to solicit any STAs that is not registered to the corresponding rTWT. To ensure fairness among all STAs, it is preferable to tear down the rTWT SP if no data from registered
STAs remain to be transmitted.
I agree to the suggested preference and we can continue that discussion in resolving CIDs on SP terminations. But I hope you would agree, as we discussed
in doc 11-21/1147 and many feedbacks received offline and via CIDs (e.g. 5775, 7471), it’s impossible to forbid any traffic (not originated from r-TWT STAs, or other TIDs), nor desired in some cases (where extra resources in frequency/spatial domain can be
allocated for non r-TWT STAs. e.g.). The NOTE is to point it out but not adding any new restriction or enabling new behaviors.
[Patrice NEZOU] I am not fully agree with your interpretation. I don’t want to forbid any traffics from non-registered r-TWT STAs during the rTWT SP. But,
as I asked in my doc1718, I would like to protect the rTWT SP and prioritize LL traffics during the rTWT SP. The rTWT SP must be firstly used for the transmission of latency sensitive traffic. To ensure fairness against any other STAs, we may think about some
constrainsts for registered rTWT STAs outside the rTWT SP as it is standardized for a MU transmission.
Could you modify your NOTE as following:
“Note: the r-TWT scheduling AP
can still may
include the AID of a STA that is not an r-TWT scheduled registered
STA in the Trigger frame(s) transmitted in the trigger-enabled TWT SP
if no more latency sensitive traffics is available for transmission. “
Regards.
Patrice
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