Hi Christian,
Do you mean it’s not practical to further tune the AGC gain based on the fading information obtained from L-LTF? What is the limitation for processing delay and
timing?
Also for the less bits ADC, how many bits do you assume? How much the SNR/ranging accuracy will be lost for such a less bit ADC? Thanks.
From: Christian Berger [mailto:crberger@xxxxxxxxxxx]
Sent: Wednesday, October 16, 2019 6:41 PM
To: Jiang, Feng1 <feng1.jiang@xxxxxxxxx>; STDS-802-11-TGAZ@xxxxxxxxxxxxxxxxx
Cc: Li, Qinghua <qinghua.li@xxxxxxxxx>; Segev, Jonathan <jonathan.segev@xxxxxxxxx>
Subject: RE: IEEE submission 11-19/1572r4
Estimating the channel on the legacy-LTF and adjusting the ADC setting on the HE preamble accordingly is unfortunately not practical at all, if you are familiar with processing
delays and timing.
Furthermore receiving 1024 QAM is not necessarily a standard feature available on all devices that might provide secure ranging, like a car key fob. Same devices will potentially
have a lower performance (less bits) ADC. With such design choices, we are potentially precluding a lot of devices from using secure ranging or alternatively providing such poor receiver SNR that will not make the next generation of ranging accuracy possible.
Christian
External Email
Hi Christian,
Thanks for your comments. In the ADC dynamic range design some margin need to be allowed to cover the PAPR of the received signal. For example, for 1024QAM the
PAPR can be up to 10dB, and if the data packet can be received successfully with no saturation, then using the same AGC setting, the secured NDP frame should also be received correctly with no saturation. Additionally, the PAPR of the secured NDP frame is
already optimized by several dB and this will be helpful for relaxing the dynamic range of ADC.
It seems not true that “The
channel conditions will *not* be known a priori,”
since the legacy preamble in the L-LTF field of NDPA or secured NDP frame can indicate whether it’s heavy fading or AWGN.
As shown in the submission 11-19/1572r4, the max SNR degradation of channel estimation due to this unintentional beamforming is 1.2494dB, and it may not hurt
ranging performance too much. Unless we see significant ranging performance degradation, it’s better to keep the current secured NDP design unchanged for simplicity.
Hi Feng,
There was a claim in the discussion today that the increased dynamic range will not be an issue since:
- For line-of-sight channels the increased dynamic range requirements for the ADC will be 3/6/9 dB for 2/4/8 streams, but line-of-sight channels
have good SNR
- For heavy fading/ non-line-of-sight channels the increase in dynamic range will be much less, since intentional beamforming will be mitigated
by the multipath
This is not true in practice, as to avoid saturation the ADC will have to back off an extra 3/6/9 dB after decoding the NDP-A /NPD SIGA and determining the number of streams/LTF.
The channel conditions will *not* be known a priori, so for *any* secure NDP with multiple streams, including for heavy fading channels the ADC will have to back off sufficiently to avoid saturation.
So we are increasing the required dynamic range of the ADCs used in secure Ranging by 3/6/9 dB. This will carry through to baseband processing and FFT cores which usually rely
on gain targets.
Christian
External Email
Hi Rethna,
Thanks for the good discussions in today’s TGaz telecon.
A few more questions/comments regarding 11-19/1572r4 are listed below for your review. Thanks.
- In slide 7, it stated the max SNR degradation for channel estimation due to unintentional beamforming is 1.2494 dB, and could
you please show more details how this number is derived? Also, have you evaluated how much ranging performance will be degraded by this 1.2494dB SNR loss? If the ranging performance doesn’t suffer too much, then maybe we don’t need to worry about this unintentional
beamforming issue in secured ranging.
- In secured NDP frame for ranging, the HE-LTF field is always repeated (at least two HE-LTF fields), and one repetition will provide
3dB additional gain after combining the channel estimation results. Even if there is 1.2494dB degradation for channel estimation of a single HE-LTF field, the 3dB gain of the repeated HE-LTF field will compensate it.
- In slide 27, a minus sign is missed before “h11_k“ in the equation “ y1[n+1] / A2k = h11_k +
h12_k’ ”
Best regards,
Feng Jiang
From: *** 802.11 TGaz - NGP - Next Generation Positioning *** [mailto:STDS-802-11-TGAZ@xxxxxxxx]
On Behalf Of Rethna Pulikkoonattu
Sent: Thursday, September 26, 2019 10:59 AM
To: STDS-802-11-TGAZ@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGAZ] TGaz Oct. 2nd telecon
Hi Jonathan,
Could you also allocate a slot at the Oct 2nd, 2019 TGaz Telecon for the following submission?
11-19/1572r4, Secure-LTF: Unintentional Beamforming Problem and A Solution Proposal
Thank you both,
I will add this to the submission pipeline.
Best,
Jonathan
Hello Jonathan:
Could you please add the following submissions to the agenda pipeline:
11-19-1686r0 – resolutions to a set of LB240 CIDs (part-7)
11-19-1368r2 -- resolutions to a set of LB240 CIDs (part-8)
Cheers --
ganesh
“It is amazing what you can accomplish if you don’t care who gets the credit.” – Harry Truman
Hi Jonathan,
Could you please add the following submission to Oct. 2nd TGaz telecon? Part of this submission
was presented in Hanoi meeting, but due to agenda time limitation, it was not completed.
We would like to finish the CR to the remaining 5 CIDs in the coming telecon. Thanks.
-
11-19/1563R1 CR for Miscellaneous CIDs in LB240_part 2
Thank you Ali, added to the submission queue.
Hi Jonathan,
Would you please add the document “11-19-1460-00” to the presentation queue? It proposes resolutions to a few LB240 CIDs on DMG/EDMG ranging.
I want to postpone discussion on “11-19-678
CR for CID 1115” till the FTF based on offline request.
Please add document 11-19-1455-01 CR for 1118, 1129 and 1324 in the agenda queue in case we have time for me to present
it.
CAUTION:
This email originated from outside of the organization.
Agenda topics for tomorrow’s telecon is as follows:
• 11-19-678
CR for CID 1115 (Dibakar)
• 11-19-1422
Clause 11 PXDMG CIDs (Assaf)
Agenda document is submission 11-19-1362, be sure to use latest version.
Please let me know of any additional agenda topic you may have.
Thank you Assaf, added to the queue.
Please add 11-19-1422-00-00az-Clause-11-PXDMG-CIDs to the queue.
I will need about 40 minutes to review it.
CAUTION:
This email originated from outside of the organization.
thank you Dibakar I will add this to the Wed. telecon agenda for this week.
Can you please add the following submission to the agenda:
“11-19-678r0- CR
for CID 1115” ?
I will need about 30 minutes for discussion.
Could you please add the following contribution to agenda? Thanks.
-
DCN 1438 CR for PHY related comments for LB240-part3
-
TGaz telecon scheduled for Wed. Aug. 21st 13:00 ET/10:00AM PT for 1:30 hrs.
-
Telecon agenda slide deck is submission 11-19-1362, be sure to use latest revision.
-
If you’re planning a submission and would like to allocate agenda time please let me know.
-
Note that teleconferences are bounded by the conditions stipulated by the documentation below.
Please review and bring up any questions/concerns you may have before proceeding with the teleconference:
Cell (WhatsApp): +1-408-203-3337 (note # change)
To unsubscribe from the STDS-802-11-TGAZ list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
To unsubscribe from the STDS-802-11-TGAZ list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGAZ&A=1
|