Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

[STDS-802-11-TGBE] Discussion on 11-21/671r1 "CR-10-3-2-9-CTS-procedure-NSTR-limited"

Hi Matt and All,

 

As discussed during the 17 June TGbe MAC ad hoc:

 

The proposed resolution and text, basically changes the current “shall” requirement for all STAs to respond to a received RTS, to may respond to an RTS for NSTR STAs.

 

While it is true that due to the capabilities of an NSTR STA, requiring an NSTR STA to responding to an RTS may interrupt the reception of “data” on an another “link” and the interruption of the reception of such “data” is something that should be avoided, changing the requirement to respond to an RTS to be “may” respond for an NSTR STA does not clearly specify the desired behavior.

 

Desired behavior:  An NSTR STA that receives an RTS shall respond as any other STA shall, unless the NSTR STA is currently “NSTR limited” (the transmission of the CTS will cause the NSTR STA to not be able to receive a “useful” transmission on another “link”). 

 

My understanding is that not responding to a received CTS for any other reason is not acceptable behavior.  Hence, the use of “may” does not correctly specify the desired behavior that an NSTR STA should respond unless it will cause harmful interference to the NSTR STA’s ability to receive ongoing transmission on other “links”.

 

Assuming the above desired behavior is what most TGbe participants agree is the desired behavior, I have the following observations:

 

  1. If the NSTR STA is currently only receiving on its MLO “links” transmissions from the AP MLD (all DL traffic), the AP MLD should be aware the transmissions and the NSTR limits of the NSTR STA.  Therefore, the AP MLD should be required to manage it transmissions to the NSTR STA (i.e., the AP MLD should only transmit a RTS to an NSTR STA if it knows that the transmission of the CTS will not impact reception of useful data by the NSTR STA).  This behavior should be a requirement on the AP MLD.  Note: that if the AP MLD is managing these transmissions to the NSTR STA, the NSTR STA simply follow “normal” RTS/CTS behavior, as the NSTR STA should assume the AP MLD is aware of what is being transmitted to it on all “links”, for this case of DL traffic only.  Hence, for the AP MLO DL traffic only case, the requirement for response to a RTS, should be the same a typical STA.
  2. For the case where the NSTR STA is not receiving only DL traffic from the AP MLD it is associated with:  If the NSTR STA is currently receiving on one of its MLO “links” and it receives a RTS on another MLO “link” it shall respond with a CTS if the criteria for sending a CTS is met and sending the CTS will not interrupt the reception of a “useful data” on another MLO “link”.  This is a requirement on the NSTR STA as only the NSTR STA will be aware of the state of all its “links” for this case.

 

Therefore, there should be two requirements in the 802.11be to address RTS/CTS behavior:

  1. A requirement on an AP MLO to not send an RTS to an NSTR STA that will cause “harmful interference” to data it is transmitting to the NSTR STA on other links.
  2. A requirement for an NSTR STA to reply to a received RTS as any other STA would, unless the reply would cause harmful interference.  This should be a shall requirement with an exception.

 

 

Regards,

Joseph Levy

New York

o: +1.631.622.4139

m: +1.516.835.9353

 

 

         

To unsubscribe from the STDS-802-11-TGBE list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGBE&A=1