1. Explanations on CID #10076 Date: 2006-05-15 Authors: May 2006 May 2006
doc.: IEEE yy/xxxxr0
May 2006
Explanations on CID #10076
Date:
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Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

2. May 2006
doc.: IEEE yy/xxxxr0
May 2006
Abstract
I submitted a comments to improve description of D1.0 for Fast link adaptation
CID#10076
During ad hoc at Jacksonville, this was deferred, and I should prepare submission.
I would explain potential problems here and proposed solutions.
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

3. CID #10076 : Current text and its potential problem
May 2006
doc.: IEEE yy/xxxxr0
May 2006
CID #10076 : Current text and its potential problem
Now, clause (on page 118) says
“If the responder discards or abandons computation for an MRQ, it should indicate this to the sender by setting the MFB to “all-ones” in the next transmission of a frame addressed to the sender that includes the HT Control field. The value of the MFS is set to the MRS value to indicate to the sender the correspondence to the MRQ that was discarded.”
But, there is no guarantee that the number of HTC in one direction is identical or close to the number of HTC in another direction.
Extreme case would be SIFS/RIFS bursting, shown in the next slide.
In such case, the responder cannot send MFB of “all-ones” and the initiator should not expect MFB response indicating discard/abandon.
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

4. CID #10076 : Current text and its potential problem (cont’d)
May 2006
doc.: IEEE yy/xxxxr0
May 2006
CID #10076 : Current text and its potential problem (cont’d)
Example;
using SIFS/RIFS bursting
single-address, and each MPDU from STA_A to STA-B has with HTC including MRQ
Each MRQ would be sent with different MRS (Sequence number)
There are three MRQs, but only one MFB would be sent as a response. How to signal MFB=‘111’ for the rest two ? SHOULD we send MFBs, even if they would be too aged to track MRS/MFS?
SIFS/RIFS Bursting
Data MPDU
Data MPDU
Data MPDU
Data MPDU
STA-A
MRQ in HTC
MRQ in HTC
MRQ in HTC
MRQ in HTC BA
STA-B
MFB in HTC
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

5. CID #10076 : Current text and its potential problem (cont’d)
May 2006
doc.: IEEE yy/xxxxr0
May 2006
CID #10076 : Current text and its potential problem (cont’d)
Other related issue
In clause , there is a description;
“If the MCS estimate is not available in time and if the HT Control field is included in the immediate response frame, the responder may set MFB to the default value “all-ones” following the MFS/MRS rules.”
There is no way to distinguish “delay (means MFB would be available later)” and “discard/abandon”
It would not be so useful to check MRS/MFS matching for all of MFB=“111” cases, especially for example shown in the previous slide.
In these cases, using the latest MFB would be a good choice.
So, using MFB=“111” to indicate discard/abandon in clause would not be a relatively strong recommendation, such as using “should”.
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

6. May 2006
doc.: IEEE yy/xxxxr0
May 2006
CID #10076 : proposed change
Change “should” at line-26 on page-119 (clause ) to “may”
As a result, text would become;
“If the responder discards or abandons computation for an MRQ, it may indicate this to the sender by setting the MFB to “all-ones” in the next transmission of a frame addressed to the sender that includes the HT Control field. The value of the MFS is set to the MRS value to indicate to the sender the correspondence to the MRQ that was discarded.”
Any comments/feedbacks/questions ?
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)