[802.19] Fwd: Screen shots showing 5 GHz Wi-FI RSSI in 802.18 room

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Dear 802-19 members,

I am re-sending to this list since my earlier email bounced, as I was not a member of this list, at that time.

Regards,

Billy.

---------- Forwarded message ----------
From: Billy Verso <billy.verso@xxxxxxxxxxxx>
Date: 16 April 2018 at 15:05
Subject: Re: Screen shots showing 5 GHz Wi-FI RSSI in 802.18 room
To: John H Notor <gnu@xxxxxxxxx>
Cc: STDS-802-18@xxxxxxxxxxxxxxxxx, stds-802-19@xxxxxxxxxxxxxxxxx, Michael Mc Laughlin <michael.mclaughlin@xxxxxxxxxxxx>

Hi John,

I understand your view about coexistence, but I fear that achieving a workable coexistence will be very difficult boarding on impossible and/or prohibitively expensive because UWB transmissions have such a low power density that an 802.11 type receiver won't see them, and since the UWB radios operating in this band have nowhere to go to avoid an interferer. If we are reduced to talking about coexistence then the fight may be already lost for UWB, unless the coexistence requirements can keep 802.11 silent in this band?

For now, the 6 to 7 GHz band is not open to higher powered unlicensed users (like 802.11ax is aspiring to be) so coexistence is actually not yet the problem. The issue for the UWB industry, and the success of the existing 802.15 UWB standards based applications already using this band, is actually one of regulations. It will be a very bad thing for this industry if the regulations are changed so that 6 to 7 GHz band is opened to a proliferation of higher powered unlicensed users (like 802.11). Since 802.18 deals with regulations, this is actually the correct forum in which to advocate on this issue. This group cannot say that it is generally a good thing to open up the 6 GHz band, it is definitely not good for 802.15 UWB deployments in this band. We need to use strong words to say that this would be very bad for 802.15 UWB deployments. It is disingenuous for us to ignore the problem muttering platitudes about coexistence as if there is some magic that can be done there.

In my view 802.11 should be proving how it will coexist and not disrupt the 802.15 UWB deployments before 802.18 should even consider advocating a change to the 6 to 7 GHz band regulations.

While I have begun 802.19 WG participation, I would consider myself a novice there, and as such I am not sure how such coexistence is actually assured. In an ideal world 802.11ax would need to prove it does not disrupt 802.15 UWB operation in the 6 to 7 GHz band before it could be ratified to operate in this band. I am copying 802.19 on this reply and re-attaching your original screenshots that are referred to earlier in the thread so that the 802.19 folks can follow the conversation. I actually presented to the 802.19 WG at the Rosemont meeting in March (doc 19-18-0017-00) to draw this matter to the groups attention.

Thanks again.

Regards,

Billy.

On 12 April 2018 at 17:27, John H Notor <gnu@xxxxxxxxx> wrote:

Billy,

Thanks for your comments.

While 802.18 should be kept in the loop on this, the coexistence criteria and other issues need to be worked out in 802.19 in my view.

Take care,

John

John Notor
President/Chief Technologist
Notor Research
Mobile: 1.408.316.8312
Web: www.notor.com
From: Billy Verso <billy.verso@xxxxxxxxxxxx>
Date: Thursday, April 12, 2018 at 2:44 AM
To: John H Notor <gnu@xxxxxxxxx>
Cc: RR-TAG <STDS-802-18@xxxxxxxxxxxxxxxxx>, Michael Mc Laughlin <michael.mclaughlin@decawave.com>
Subject: Re: Screen shots showing 5 GHz Wi-FI RSSI in 802.18 room

Hi John,

Sorry for not acknowledging your email sooner. Thanks for your comment (made during the 802.18 meeting) about the Friis propagation model not being appropriate for real world situations. I will rework the numbers using the 802.11n signal propagation model.

Thanks also for these screen shots showing AP power levels in the meeting room. The RX power you observed at ~6ft and ~25ft from the Verilan access point does seem to show that the AP output power level was turned down to perhaps +5 or +6 dBm rather than the +20 dBm max level setting that could have been used. I believe this is done allow a higher density of access points to be installed to support the large number of attendees needing access. I had some communication with Rick Alfvin who said this is not inconsistent with the practice adopted when he was working with Verilan. I guess this means that all AP will not be at max power, which was one of the points you made, however it is likely that this will only be in situations where they are closely spaced, so that as you move away from one you are actually getting closer to another.

Interestingly, your screenshots also show the thing that worries me -- that is, the proliferation of (high power) Wi-Fi transmitters... While 11 APs are listed, the graphic seems to show that 115 and 122 APs respectively (number at the bottom) were found in range. The split seems to be about 20% in the 5.8 GHz band and 80% in the 2.4 GHz band. All 11 listed APs have power levels way in excess of the levels I identified in my presentation (18-18-0023-00-0000) that would cause problems for UWB receivers if these were transposed into the 6 GHz to 7 GHz band where UWB operates. I expect that no matter where you went in the building you would probably find similar RX levels. The true air-occupancy is worse of course, since your diagnostic monitor application is only reporting the AP and not the transmissions from all the connected users.

I have copied the 802-18 group on this since I believe it gives a very good illustration of the issue.

I think everyone should now be able to appreciate and understand the concern for 802.15 UWB applications in the 6 GHz to 7 GHz band should this sort of Wi-Fi use be translated into that band.

Thanks again.

Best regards,
Billy.

On 6 March 2018 at 18:50, John H Notor <gnu@xxxxxxxxx> wrote:
Billy,

Here are a couple of screen shots of spectrum scans using Wi-Fi Explorer. The signal level numbers are in dBm. I was associated with the Verilan-secure router in the room with BSSID starting with 40:F4, the one shown in bold text on the list, in the scan. One scan I was about 6 ft away, LOS, the other I was about 25 ft away on the other side of the room. I check the scan function on my iPhone at 6ft away, the iPhone Airport Utility app reported -50 dBm, which is close to the number reported by Wi-Fi Explorer on my Macbook Pro.

Take care,

John

John Notor
President/Chief Technologist
Notor Research
Mobile: 1.408.316.8312
Web: www.notor.com

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