<div dir="auto"><div dir="auto"></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"></blockquote></div><div dir="auto">Meant to comment on this earlier, the AREDN amateur radio emergency mesh group ( <a href="https://www.arednmesh.org">https://www.arednmesh.org</a> ) seems to be using 5mhz channels as an option, for a few of the previously mentioned reasons. </div><div dir="auto"><br></div><div dir="auto">Interestingly, their code is based out of OpenWRT, and they just recently caught everything up to the 18.06.1 release, from the pre LEDE era. What it is, is a long distance backhaul/local area mesh comm system using commercial equipment on amateur bands, for emergency use. Video, text, audio, net access, etc. They have pretty extensive networks in several areas.</div><div dir="auto"><br></div><div dir="auto">So, there's another user of the narrower channels. I'd guess anyone setting up homegrown mini ISP like systems similar to this would like the option, to trade peak bandwidth for extended s/n and longer range.</div><div dir="auto"><br></div><div dir="auto"><br></div><div class="gmail_quote" dir="auto"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">--------- Forwarded message ----------<br>From: Dave Taht <<a href="mailto:dave.taht@gmail.com" rel="noreferrer noreferrer noreferrer" target="_blank">dave.taht@gmail.com</a>><br>To: <a href="http://bkil.hu" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">bkil.hu</a>+<a href="mailto:Aq@gmail.com" rel="noreferrer noreferrer noreferrer" target="_blank">Aq@gmail.com</a>, Make-Wifi-fast <<a href="mailto:make-wifi-fast@lists.bufferbloat.net" rel="noreferrer noreferrer noreferrer" target="_blank">make-wifi-fast@lists.bufferbloat.net</a>>, Ben Greear <<a href="mailto:greearb@candelatech.com" rel="noreferrer noreferrer noreferrer" target="_blank">greearb@candelatech.com</a>><br>Cc: <br>Bcc: <br>Date: Mon, 8 Oct 2018 13:32:33 -0700<br>Subject: Re: [Make-wifi-fast] [Bloat] Is 5/10MHz wifi bandwidth legal in 2.4GHz (half/quarter-clocking)?<br>make-wifi-fast is better here.<br>
<br>
anyway there was a long debate about making the public access channels<br>
available to folk that needed it in the ath10k patchset, I think in<br>
the end ben greer decided to leave it out lacking getting anyone at<br>
the FCC to pay attention.<br>
<br>
the second question, regarding 5Mhz channels in general - I had tried<br>
that a lot (it has worked multiple times in ath9k's lifecycle) and I<br>
*liked it*, but as it was non standard never got around to depending<br>
on it existing on anything.<br>
<br>
We definitely need more channels, not less<br>
<br>
On Mon, Oct 8, 2018 at 1:18 PM bkil <<a href="http://bkil.hu" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">bkil.hu</a>+<a href="mailto:Aq@gmail.com" rel="noreferrer noreferrer noreferrer" target="_blank">Aq@gmail.com</a>> wrote:<br>
><br>
> If this is not the right forum to discuss, could you please point me<br>
> in the right direction?<br>
><br>
> After all, channel spacing is indeed 5MHz here. Although using a new<br>
> raster instead of the 20MHz channel center frequencies would allow<br>
> full utilization of the band (16 or 8 channels respectively), using<br>
> the standard set of 11 (13) channels is better than nothing.<br>
><br>
> Is it a good idea to use HT instead of g for such links?<br>
><br>
> =<br>
> Some background and links for those who do not know this mode:<br>
><br>
> "the 2007 version of the IEEE 802.11 standard [1] specifies 5 and 10<br>
> MHz wide channels for use in the 4.9 GHz public safety bands"<br>
><br>
> Although according to my reading of section 17.1, it applies to the<br>
> 5GHz bands as well:<br>
><br>
> >> 17. Orthogonal frequency division multiplexing (OFDM) PHY specification<br>
> for the 5 GHz band<br>
> [...]<br>
> The OFDM system also provides a “half-clocked” operation using 10 MHz<br>
> channel spacings with data<br>
> communications capabilities of 3, 4.5, 6, 9, 12, 18, 24, and 27 Mb/s.<br>
> The support of transmitting and<br>
> receiving at data rates of 3, 6, and 12 Mb/s is mandatory when using<br>
> 10 MHz channel spacing. The half-<br>
> clocked operation doubles symbol times and clear channel assessment<br>
> (CCA) times when using 10 MHz<br>
> channel spacing. The regulatory requirements and information regarding<br>
> use of this OFDM system in<br>
> 4.9 GHz and 5 GHz bands is in Annex I and Annex J.<<<br>
><br>
> They probably did not highlight 2.4GHz usage because of mixed-mode<br>
> (non-OFDM) crowding, although nowadays we could actually move this<br>
> band to OFDM-only as well.<br>
><br>
> It is unfortunate that this allowance has disappeared in newer<br>
> versions of the standard. Was that intentional?<br>
><br>
> Reasons why downclocking is advantageous (up to +9dB link budget):<br>
><br>
> * longer GI = better protection against multipath fading;<br>
> * higher power density allowed (2x here) = better SNR;<br>
> * less chance for (adjacent-channel) interference;<br>
> * reduced TX & RX power consumption for idling and low load.<br>
><br>
> I know that 802.11ah/af are here, but there exist literally millions<br>
> of devices potentially supporting this old and trusty mode, software<br>
> permit.<br>
><br>
> Many Atheros chipsets support it, both old and new. OpenWrt has<br>
> debugfs patches applied to enable this, while Linux has some other<br>
> patches as well, although it is not user visible.<br>
><br>
> If this is a legal and preferred mode, it would be nice if we could<br>
> unify access.<br>
><br>
> <a href="https://openwrt.org/docs/guide-user/network/wifi/basic?s[]=chanbw" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://openwrt.org/docs/guide-user/network/wifi/basic?s[]=chanbw</a><br>
> <a href="http://ccr.sigcomm.org/online/files/p135-chandra.pdf" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">http://ccr.sigcomm.org/online/files/p135-chandra.pdf</a><br>
> <a href="https://kabru.eecs.umich.edu/papers/publications/2011/xyzhang_kgshin_mobicom11.pdf" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://kabru.eecs.umich.edu/papers/publications/2011/xyzhang_kgshin_mobicom11.pdf</a><br>
> <a href="https://www.etsi.org/deliver/etsi_en/300300_300399/300328/01.08.01_60/en_300328v010801p.pdf" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://www.etsi.org/deliver/etsi_en/300300_300399/300328/01.08.01_60/en_300328v010801p.pdf</a><br>
> <a href="https://www.cwnp.com/forums/posts?postNum=305220" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://www.cwnp.com/forums/posts?postNum=305220</a><br>
> <a href="https://forum.archive.openwrt.org/viewtopic.php?id=38590" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://forum.archive.openwrt.org/viewtopic.php?id=38590</a><br>
> <a href="https://forum.openwrt.org/t/5-mhz-bandwith-option/3615" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://forum.openwrt.org/t/5-mhz-bandwith-option/3615</a><br>
> _______________________________________________<br>
> Bloat mailing list<br>
> <a href="mailto:Bloat@lists.bufferbloat.net" rel="noreferrer noreferrer noreferrer" target="_blank">Bloat@lists.bufferbloat.net</a><br>
> <a href="https://lists.bufferbloat.net/listinfo/bloat" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://lists.bufferbloat.net/listinfo/bloat</a><br>
<br>
<br>
<br>
-- <br>
<br>
Dave Täht<br>
CTO, TekLibre, LLC<br>
<a href="http://www.teklibre.com" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">http://www.teklibre.com</a><br>
Tel: 1-831-205-9740<br>
<br>
<br><br><br>---------- Forwarded message ----------<br>From: bkil <<a href="http://bkil.hu" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">bkil.hu</a>+<a href="mailto:Aq@gmail.com" rel="noreferrer noreferrer noreferrer" target="_blank">Aq@gmail.com</a>><br>To: <a href="mailto:ryan@mounce.com.au" rel="noreferrer noreferrer noreferrer" target="_blank">ryan@mounce.com.au</a><br>Cc: bloat <<a href="mailto:bloat@lists.bufferbloat.net" rel="noreferrer noreferrer noreferrer" target="_blank">bloat@lists.bufferbloat.net</a>>, Make-Wifi-fast <<a href="mailto:make-wifi-fast@lists.bufferbloat.net" rel="noreferrer noreferrer noreferrer" target="_blank">make-wifi-fast@lists.bufferbloat.net</a>><br>Bcc: <br>Date: Tue, 9 Oct 2018 07:44:40 +0200<br>Subject: Re: [Make-wifi-fast] [Bloat] Is 5/10MHz wifi bandwidth legal in 2.4GHz (half/quarter-clocking)?<br>Yes, that was my conclusion as well. There exist spectral masks of<br>
maximal allowed side lobes, but if you are transmitting signals<br>
narrower than that, the side lobes will be much below the limit.<br>
<br>
Spectral density in Hungary and some other countries allows for<br>
10mW/MHz, meaning twice the power density for narrow channels.<br>
<br>
There can exist a possibility for starvation if two narrow channels<br>
use the two sides of a wider channel in turn, similar to HT40, so a<br>
neighborly mechanism would be nice.<br>
<br>
On Tue, Oct 9, 2018 at 5:53 AM Ryan Mounce <<a href="mailto:ryan@mounce.com.au" rel="noreferrer noreferrer noreferrer" target="_blank">ryan@mounce.com.au</a>> wrote:<br>
><br>
> I'm not aware of anywhere this would be illegal. Worst case you will<br>
> need to reduce power by 3/6dB (10/5MHz) if there is a power spectral<br>
> density limit in a given jurisdiction and max EIRP @ 20MHz is already<br>
> at that limit.<br>
><br>
> On Tue, 9 Oct 2018 at 06:48, bkil <<a href="http://bkil.hu" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">bkil.hu</a>+<a href="mailto:Aq@gmail.com" rel="noreferrer noreferrer noreferrer" target="_blank">Aq@gmail.com</a>> wrote:<br>
> ><br>
> > If this is not the right forum to discuss, could you please point me<br>
> > in the right direction?<br>
> ><br>
> > After all, channel spacing is indeed 5MHz here. Although using a new<br>
> > raster instead of the 20MHz channel center frequencies would allow<br>
> > full utilization of the band (16 or 8 channels respectively), using<br>
> > the standard set of 11 (13) channels is better than nothing.<br>
> ><br>
> > Is it a good idea to use HT instead of g for such links?<br>
> ><br>
> > =<br>
> > Some background and links for those who do not know this mode:<br>
> ><br>
> > "the 2007 version of the IEEE 802.11 standard [1] specifies 5 and 10<br>
> > MHz wide channels for use in the 4.9 GHz public safety bands"<br>
> ><br>
> > Although according to my reading of section 17.1, it applies to the<br>
> > 5GHz bands as well:<br>
> ><br>
> > >> 17. Orthogonal frequency division multiplexing (OFDM) PHY specification<br>
> > for the 5 GHz band<br>
> > [...]<br>
> > The OFDM system also provides a “half-clocked” operation using 10 MHz<br>
> > channel spacings with data<br>
> > communications capabilities of 3, 4.5, 6, 9, 12, 18, 24, and 27 Mb/s.<br>
> > The support of transmitting and<br>
> > receiving at data rates of 3, 6, and 12 Mb/s is mandatory when using<br>
> > 10 MHz channel spacing. The half-<br>
> > clocked operation doubles symbol times and clear channel assessment<br>
> > (CCA) times when using 10 MHz<br>
> > channel spacing. The regulatory requirements and information regarding<br>
> > use of this OFDM system in<br>
> > 4.9 GHz and 5 GHz bands is in Annex I and Annex J.<<<br>
> ><br>
> > They probably did not highlight 2.4GHz usage because of mixed-mode<br>
> > (non-OFDM) crowding, although nowadays we could actually move this<br>
> > band to OFDM-only as well.<br>
> ><br>
> > It is unfortunate that this allowance has disappeared in newer<br>
> > versions of the standard. Was that intentional?<br>
> ><br>
> > Reasons why downclocking is advantageous (up to +9dB link budget):<br>
> ><br>
> > * longer GI = better protection against multipath fading;<br>
> > * higher power density allowed (2x here) = better SNR;<br>
> > * less chance for (adjacent-channel) interference;<br>
> > * reduced TX & RX power consumption for idling and low load.<br>
> ><br>
> > I know that 802.11ah/af are here, but there exist literally millions<br>
> > of devices potentially supporting this old and trusty mode, software<br>
> > permit.<br>
> ><br>
> > Many Atheros chipsets support it, both old and new. OpenWrt has<br>
> > debugfs patches applied to enable this, while Linux has some other<br>
> > patches as well, although it is not user visible.<br>
> ><br>
> > If this is a legal and preferred mode, it would be nice if we could<br>
> > unify access.<br>
> ><br>
> > <a href="https://openwrt.org/docs/guide-user/network/wifi/basic?s[]=chanbw" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://openwrt.org/docs/guide-user/network/wifi/basic?s[]=chanbw</a><br>
> > <a href="http://ccr.sigcomm.org/online/files/p135-chandra.pdf" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">http://ccr.sigcomm.org/online/files/p135-chandra.pdf</a><br>
> > <a href="https://kabru.eecs.umich.edu/papers/publications/2011/xyzhang_kgshin_mobicom11.pdf" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://kabru.eecs.umich.edu/papers/publications/2011/xyzhang_kgshin_mobicom11.pdf</a><br>
> > <a href="https://www.etsi.org/deliver/etsi_en/300300_300399/300328/01.08.01_60/en_300328v010801p.pdf" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://www.etsi.org/deliver/etsi_en/300300_300399/300328/01.08.01_60/en_300328v010801p.pdf</a><br>
> > <a href="https://www.cwnp.com/forums/posts?postNum=305220" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://www.cwnp.com/forums/posts?postNum=305220</a><br>
> > <a href="https://forum.archive.openwrt.org/viewtopic.php?id=38590" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://forum.archive.openwrt.org/viewtopic.php?id=38590</a><br>
> > <a href="https://forum.openwrt.org/t/5-mhz-bandwith-option/3615" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://forum.openwrt.org/t/5-mhz-bandwith-option/3615</a><br>
> > _______________________________________________<br>
> > Bloat mailing list<br>
> > <a href="mailto:Bloat@lists.bufferbloat.net" rel="noreferrer noreferrer noreferrer" target="_blank">Bloat@lists.bufferbloat.net</a><br>
> > <a href="https://lists.bufferbloat.net/listinfo/bloat" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">https://lists.bufferbloat.net/listinfo/bloat</a><br>
<br>
<br><br><br>---------- Forwarded message ----------<br>From: bkil <<a href="http://bkil.hu" rel="noreferrer noreferrer noreferrer noreferrer" target="_blank">bkil.hu</a>+<a href="mailto:Aq@gmail.com" rel="noreferrer noreferrer noreferrer" target="_blank">Aq@gmail.com</a>><br>To: Dave Taht <<a href="mailto:dave.taht@gmail.com" rel="noreferrer noreferrer noreferrer" target="_blank">dave.taht@gmail.com</a>>, bloat <<a href="mailto:bloat@lists.bufferbloat.net" rel="noreferrer noreferrer noreferrer" target="_blank">bloat@lists.bufferbloat.net</a>><br>Cc: Make-Wifi-fast <<a href="mailto:make-wifi-fast@lists.bufferbloat.net" rel="noreferrer noreferrer noreferrer" target="_blank">make-wifi-fast@lists.bufferbloat.net</a>>, <a href="mailto:greearb@candelatech.com" rel="noreferrer noreferrer noreferrer" target="_blank">greearb@candelatech.com</a><br>Bcc: <br>Date: Tue, 9 Oct 2018 07:52:28 +0200<br>Subject: Re: [Make-wifi-fast] [Bloat] Is 5/10MHz wifi bandwidth legal in 2.4GHz (half/quarter-clocking)?<br>I wouldn't be surprised if we could patch this mode to another common<br>
chipset other than Atheros.<br>
<br>
I understand that this is not a standard mode in 2.4GHz if reading the<br>
standard to the letter, but it is close enough. If it is legal to use<br>
it, as lots of devices support it, it would still be a great choice<br>
for certain point to (mult-)point links or mesh/IoT deployments and we<br>
should "advertise" this capability better.<br>
<br>
We could get 16 orthogonal channels instead of 4 (or 13 overlapping) -<br>
so we do get more channels in the end.<br>
<br>
Also we have lots of underutilized spectrum in 5GHz, we would need to<br>
update regdb in most countries and handle additional channel numbers<br>
to use this.<br> <br>
<br>
<br>
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