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[STDS-802-11-TGBE] Questions on 363r1 (Proposals on unused bandwidth utilizations)

Hi all,

 

I am writing this email to clarify some of the questions that were asked on the contribution “363r1 Proposals on unused bandwidth utilizations”. It is noted that some of the motivations in the presentation are similar to the ones in “429r0 Partial Bandwidth Transmission Opportunities in EHT”.

 

Below are the questions I recollect and the corresponding responses. Please add any questions that have got missed.

  • Scenario 1: In case of channels unused by ongoing non-triggered transmission,
    • What is the use case for utilizing unused channels 
      • If the original non-triggered transmission was OBSS, the gain is clear. Both APs and non-APs can utilize the unused channels for DL or UL . Aligning the duration with that of ongoing transmissions, ensures there is mutual coexistence between BSSs when such a scheme is used i.e. collisions due to missing NAV are avoided
      • If the original non-triggered transmission was myBSS, the feature could be used for TDLS type transmissions by non-APs or for simultaneous DL/UL by the AP provided there is sufficient frequency separation between the channels and the AP has the capability to support it
    • What are the additional requirements imposed on AP capabilities
      • There is no imposition of requirements. If the AP cannot support simultaneous DL/UL for a set of channels, it can only try to utilize unused bandwidth from OBSS transmission or by ED-only busy detection
  • Scenario 2: In case of channels used by ongoing triggered transmission,
    • What is the use case for utilizing unused channels
      • This is the case when the AP knows it has transmitted the trigger. Also non-APs associated with it know the same. The unused channels can be utilized for further DL UL transmissions by the AP  (if it can support simultaneous DL UL and for sufficient frequency separation between channels) or for  TDLS type transmissions 
    • What are the requirements imposed on AP capabilities
      • There is no imposition of requirements. If the AP cannot support simultaneous DL/UL for a set of channels, only non-APs can utilize the bandwidth for TDLS type transmissions
  • For the case where full CCA can be done in parallel on multiple channels
    • Does it impose the capability to decode preamble on multiple channels in parallel
      • We propose both kinds of capabilities, one where the CCA can be done in parallel on all channels and the one where CCA can be done only one channel at a time. For the first case, the device is capable of decoding preamble multiple channels in parallel.
    • How does the receiver handle the transmitter’s using this feature
      • If the transmitter can start transmitting on any channel, the receiver too has the capability of decoding preamble in parallel on multiple channels. 
  • For the case where full CCA is done one channel at a time, 
    • How to handle the possibility of missing NAV on the newly selected channel for full CCA and colliding
      • The effect of this can be mitigated by suitably lowering the ED threshold of the channel newly selected for full CCA. Also, with ETSI considering ED-only at -72 dBm for 6GHz, if the CCA mechanism is ED-only on all channels, this problem doesn’t exist.
    • How does the receiver handle the transmitter’s using this feature
      • In this case, the transmitter will choose the channel to perform full CCA by following a predetermined pattern. As an example, assume that a link consists of multiple 20 MHz channels from channel 1 to channel N. The predetermined pattern could be that if channel 1 is busy, full CCA is performed on channel (x+1); if channel (x+1) is busy, it is performed on channel (2x+1); and so on.  
        • If the receiver can decode preamble only one channel at a time, it can be confined to one particular channel for PD while multiple receivers (non-APs) associated with the same AP can perform PD on different channels. 
        • Alternatively, the receiver can also move its preamble detection logic from one channel to the other in the same predetermined fashion. This scheme however can result in errors when the receiver does not see a preamble but the transmitter does.
        • If the receiver is capable of decoding preamble in parallel on multiple channels, there is no issue 

 

Regards,

Sindhu

 

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