wireless-regdb: Update regulatory rules for the US on 6 GHz band

wireless-regdb: Update regulatory rules for the US on 6 GHz band

[Asura Liu (asuliu)]

From 3db25ea674232fea6a5efca292f6ed3fd8eba7a2 Mon Sep 17 00:00:00 2001
From: Asura Liu <asuliu@cisco.com>
Date: Mon, 13 Dec 2021 16:46:28 +0800
Subject: [PATCH] wireless-regdb: Update regulatory rules for the US on 6 GHz
band
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

According to FCC 20-51, FCC adopts rules to unlicensed use of the 6 GHz band:
"59. Third, the Commission limits the low-power indoor access points to lower power levels than the standard-power access points that operate under the control of an AFC. Consistent with the Commission's approach for the existing U-NII bands, the Commission specifies both a maximum power spectral density and an absolute maximum transmit power, both in terms of EIRP. Specifically, the Commission allows a maximum radiated power spectral density of 5 dBm per 1 megahertz and an absolute maximum radiated channel power of 30 dBm for the maximum permitted 320-megahertz channel (or 27 dBm for a 160-megahertz channel). In addition, to ensure that client devices remain in close proximity to the indoor access points, the Commission limits their PSD and maximum transmit power to 6 dB below the power permitted for the access points."
See https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band

And 47 CFR § 15.407 describe this as following:
(a) (5) For an indoor access point operating in the 5.925-7.125 GHz band, the maximum power spectral density must not exceed 5 dBm e.i.r.p. in any 1-megahertz band. In addition, the maximum e.i.r.p. over the frequency band of operation must not exceed 30 dBm.
(a) (8) For client devices operating under the control of an indoor access point in the 5.925-7.125 GHz bands, the maximum power spectral density must not exceed −1 dBm e.i.r.p. in any 1-megahertz band, and the maximum e.i.r.p. over the frequency band of operation must not exceed 24 dBm.
---
db.txt | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/db.txt b/db.txt
index b898799..c6ef9b6 100644
--- a/db.txt
+++ b/db.txt
@@ -1606,6 +1606,12 @@ country US: DFS-FCC
	# https://www.federalregister.gov/documents/2021/05/03/2021-08802/use-of-the-5850-5925-ghz-band
	# max. 33 dBm AP @ 20MHz, 36 dBm AP @ 40Mhz+, 6 dB less for clients
	(5850 - 5895 @ 40), (27), NO-OUTDOOR, AUTO-BW, NO-IR
+	# 6ghz band
+	# https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
+	# https://docs.fcc.gov/public/attachments/FCC-20-51A1_Rcd.pdf
+	# max. 30 dBm AP @ 320MHz, 27 dBm AP @ 160MHz, 6 dB less for clients
+	(5925 - 7125 @ 320), (30), NO-OUTDOOR, AUTO-BW
+	(5925 - 7125 @ 320), (24), NO-OUTDOOR, AUTO-BW, NO-IR
	# 60g band
	# reference: section IV-D https://docs.fcc.gov/public/attachments/FCC-16-89A1.pdf
	# channels 1-6 EIRP=40dBm(43dBm peak)
-- 
2.30.1 (Apple Git-130)

Re: wireless-regdb: Update regulatory rules for the US on 6 GHz band

[sforshee]

On Mon, Dec 13, 2021 at 09:19:50AM +0000, Asura Liu (asuliu) wrote:
> From 3db25ea674232fea6a5efca292f6ed3fd8eba7a2 Mon Sep 17 00:00:00 2001
> From: Asura Liu <asuliu@cisco.com>
> Date: Mon, 13 Dec 2021 16:46:28 +0800
> Subject: [PATCH] wireless-regdb: Update regulatory rules for the US on 6 GHz
> band
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
> 
> According to FCC 20-51, FCC adopts rules to unlicensed use of the 6 GHz band:
> "59. Third, the Commission limits the low-power indoor access points to lower power levels than the standard-power access points that operate under the control of an AFC. Consistent with the Commission's approach for the existing U-NII bands, the Commission specifies both a maximum power spectral density and an absolute maximum transmit power, both in terms of EIRP. Specifically, the Commission allows a maximum radiated power spectral density of 5 dBm per 1 megahertz and an absolute maximum radiated channel power of 30 dBm for the maximum permitted 320-megahertz channel (or 27 dBm for a 160-megahertz channel). In addition, to ensure that client devices remain in close proximity to the indoor access points, the Commission limits their PSD and maximum transmit power to 6 dB below the power permitted for the access points."
> See https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
> 
> And 47 CFR § 15.407 describe this as following:
> (a) (5) For an indoor access point operating in the 5.925-7.125 GHz band, the maximum power spectral density must not exceed 5 dBm e.i.r.p. in any 1-megahertz band. In addition, the maximum e.i.r.p. over the frequency band of operation must not exceed 30 dBm.
> (a) (8) For client devices operating under the control of an indoor access point in the 5.925-7.125 GHz bands, the maximum power spectral density must not exceed −1 dBm e.i.r.p. in any 1-megahertz band, and the maximum e.i.r.p. over the frequency band of operation must not exceed 24 dBm.

Thanks for the patch. A couple of quick notes about the patch
description. It's preferred to wrap lines in the body at around 75
characters, and it's required that you include a Signed-off-by tag
indicating your agreement to the DCO for your contribution (see
CONTRIBUTING).

Additional comments below.

> ---
> db.txt | 6 ++++++
> 1 file changed, 6 insertions(+)
> 
> diff --git a/db.txt b/db.txt
> index b898799..c6ef9b6 100644
> --- a/db.txt
> +++ b/db.txt
> @@ -1606,6 +1606,12 @@ country US: DFS-FCC
> 	# https://www.federalregister.gov/documents/2021/05/03/2021-08802/use-of-the-5850-5925-ghz-band
> 	# max. 33 dBm AP @ 20MHz, 36 dBm AP @ 40Mhz+, 6 dB less for clients
> 	(5850 - 5895 @ 40), (27), NO-OUTDOOR, AUTO-BW, NO-IR
> +	# 6ghz band
> +	# https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
> +	# https://docs.fcc.gov/public/attachments/FCC-20-51A1_Rcd.pdf
> +	# max. 30 dBm AP @ 320MHz, 27 dBm AP @ 160MHz, 6 dB less for clients
> +	(5925 - 7125 @ 320), (30), NO-OUTDOOR, AUTO-BW
> +	(5925 - 7125 @ 320), (24), NO-OUTDOOR, AUTO-BW, NO-IR

The kernel doesn't currently support multiple rules with different flags
for the same range. This is an issue that's come up several times, but
so far nothing has been done about it.

Even ingoring that, I don't think these rules accomplish the intended
purpose. There's nothing that would require a client device to use the
NO-IR rule, so they could end up using the higher power limit and
transmitting before detecting transmission from an AP.

I also suspect that we should be able to express the AFC requirement in
the database before permitting AP operation in this range.

Currently I think the best we're able to do is to use the lowest common
denominator, which is the 24 dBm rule with NO-IR.

Thanks,
Seth

Re: [wireless-regdb] wireless-regdb: Update regulatory rules for the US on 6 GHz band

[Sungbo Eo]

On 2021-12-18 06:55, sforshee@kernel.org wrote:
> On Mon, Dec 13, 2021 at 09:19:50AM +0000, Asura Liu (asuliu) wrote:
>>  From 3db25ea674232fea6a5efca292f6ed3fd8eba7a2 Mon Sep 17 00:00:00 2001
>> From: Asura Liu <asuliu@cisco.com>
>> Date: Mon, 13 Dec 2021 16:46:28 +0800
>> Subject: [PATCH] wireless-regdb: Update regulatory rules for the US on 6 GHz
>> band
>> MIME-Version: 1.0
>> Content-Type: text/plain; charset=UTF-8
>> Content-Transfer-Encoding: 8bit
>>
>> According to FCC 20-51, FCC adopts rules to unlicensed use of the 6 GHz band:
>> "59. Third, the Commission limits the low-power indoor access points to lower power levels than the standard-power access points that operate under the control of an AFC. Consistent with the Commission's approach for the existing U-NII bands, the Commission specifies both a maximum power spectral density and an absolute maximum transmit power, both in terms of EIRP. Specifically, the Commission allows a maximum radiated power spectral density of 5 dBm per 1 megahertz and an absolute maximum radiated channel power of 30 dBm for the maximum permitted 320-megahertz channel (or 27 dBm for a 160-megahertz channel). In addition, to ensure that client devices remain in close proximity to the indoor access points, the Commission limits their PSD and maximum transmit power to 6 dB below the power permitted for the access points."
>> See https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
>>
>> And 47 CFR § 15.407 describe this as following:
>> (a) (5) For an indoor access point operating in the 5.925-7.125 GHz band, the maximum power spectral density must not exceed 5 dBm e.i.r.p. in any 1-megahertz band. In addition, the maximum e.i.r.p. over the frequency band of operation must not exceed 30 dBm.
>> (a) (8) For client devices operating under the control of an indoor access point in the 5.925-7.125 GHz bands, the maximum power spectral density must not exceed −1 dBm e.i.r.p. in any 1-megahertz band, and the maximum e.i.r.p. over the frequency band of operation must not exceed 24 dBm.
> 
> Thanks for the patch. A couple of quick notes about the patch
> description. It's preferred to wrap lines in the body at around 75
> characters, and it's required that you include a Signed-off-by tag
> indicating your agreement to the DCO for your contribution (see
> CONTRIBUTING).
> 
> Additional comments below.
> 
>> ---
>> db.txt | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/db.txt b/db.txt
>> index b898799..c6ef9b6 100644
>> --- a/db.txt
>> +++ b/db.txt
>> @@ -1606,6 +1606,12 @@ country US: DFS-FCC
>> 	# https://www.federalregister.gov/documents/2021/05/03/2021-08802/use-of-the-5850-5925-ghz-band
>> 	# max. 33 dBm AP @ 20MHz, 36 dBm AP @ 40Mhz+, 6 dB less for clients
>> 	(5850 - 5895 @ 40), (27), NO-OUTDOOR, AUTO-BW, NO-IR
>> +	# 6ghz band
>> +	# https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
>> +	# https://docs.fcc.gov/public/attachments/FCC-20-51A1_Rcd.pdf
>> +	# max. 30 dBm AP @ 320MHz, 27 dBm AP @ 160MHz, 6 dB less for clients
>> +	(5925 - 7125 @ 320), (30), NO-OUTDOOR, AUTO-BW
>> +	(5925 - 7125 @ 320), (24), NO-OUTDOOR, AUTO-BW, NO-IR
> 
> The kernel doesn't currently support multiple rules with different flags
> for the same range. This is an issue that's come up several times, but
> so far nothing has been done about it.
> 
> Even ingoring that, I don't think these rules accomplish the intended
> purpose. There's nothing that would require a client device to use the
> NO-IR rule, so they could end up using the higher power limit and
> transmitting before detecting transmission from an AP.
> 
> I also suspect that we should be able to express the AFC requirement in
> the database before permitting AP operation in this range.
> 
> Currently I think the best we're able to do is to use the lowest common
> denominator, which is the 24 dBm rule with NO-IR.
> 
> Thanks,
> Seth

Hi, sorry for intruding.

I thought max EIRP rule for larger bandwidth also applies to smaller 
bandwidth, that means we would use 24 dBm tx power with 20 MHz channel 
as well. But the regulation limits PSD to -1 dBm/MHz and it leads to 12 
dBm for 20 MHz. Shouldn't we use 12 dBm rule to fit the smallest bandwidth?

I still don't understand exactly how the rules work, my apologies if I 
am mistaken.

Regards,
Sungbo

Re: [wireless-regdb] wireless-regdb: Update regulatory rules for the US on 6 GHz band

[Seth Forshee]

On Sat, Dec 18, 2021 at 04:34:13PM +0900, Sungbo Eo wrote:
> On 2021-12-18 06:55, sforshee@kernel.org wrote:
> > On Mon, Dec 13, 2021 at 09:19:50AM +0000, Asura Liu (asuliu) wrote:
> > >  From 3db25ea674232fea6a5efca292f6ed3fd8eba7a2 Mon Sep 17 00:00:00 2001
> > > From: Asura Liu <asuliu@cisco.com>
> > > Date: Mon, 13 Dec 2021 16:46:28 +0800
> > > Subject: [PATCH] wireless-regdb: Update regulatory rules for the US on 6 GHz
> > > band
> > > MIME-Version: 1.0
> > > Content-Type: text/plain; charset=UTF-8
> > > Content-Transfer-Encoding: 8bit
> > > 
> > > According to FCC 20-51, FCC adopts rules to unlicensed use of the 6 GHz band:
> > > "59. Third, the Commission limits the low-power indoor access points to lower power levels than the standard-power access points that operate under the control of an AFC. Consistent with the Commission's approach for the existing U-NII bands, the Commission specifies both a maximum power spectral density and an absolute maximum transmit power, both in terms of EIRP. Specifically, the Commission allows a maximum radiated power spectral density of 5 dBm per 1 megahertz and an absolute maximum radiated channel power of 30 dBm for the maximum permitted 320-megahertz channel (or 27 dBm for a 160-megahertz channel). In addition, to ensure that client devices remain in close proximity to the indoor access points, the Commission limits their PSD and maximum transmit power to 6 dB below the power permitted for the access points."
> > > See https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
> > > 
> > > And 47 CFR § 15.407 describe this as following:
> > > (a) (5) For an indoor access point operating in the 5.925-7.125 GHz band, the maximum power spectral density must not exceed 5 dBm e.i.r.p. in any 1-megahertz band. In addition, the maximum e.i.r.p. over the frequency band of operation must not exceed 30 dBm.
> > > (a) (8) For client devices operating under the control of an indoor access point in the 5.925-7.125 GHz bands, the maximum power spectral density must not exceed −1 dBm e.i.r.p. in any 1-megahertz band, and the maximum e.i.r.p. over the frequency band of operation must not exceed 24 dBm.
> > 
> > Thanks for the patch. A couple of quick notes about the patch
> > description. It's preferred to wrap lines in the body at around 75
> > characters, and it's required that you include a Signed-off-by tag
> > indicating your agreement to the DCO for your contribution (see
> > CONTRIBUTING).
> > 
> > Additional comments below.
> > 
> > > ---
> > > db.txt | 6 ++++++
> > > 1 file changed, 6 insertions(+)
> > > 
> > > diff --git a/db.txt b/db.txt
> > > index b898799..c6ef9b6 100644
> > > --- a/db.txt
> > > +++ b/db.txt
> > > @@ -1606,6 +1606,12 @@ country US: DFS-FCC
> > > 	# https://www.federalregister.gov/documents/2021/05/03/2021-08802/use-of-the-5850-5925-ghz-band
> > > 	# max. 33 dBm AP @ 20MHz, 36 dBm AP @ 40Mhz+, 6 dB less for clients
> > > 	(5850 - 5895 @ 40), (27), NO-OUTDOOR, AUTO-BW, NO-IR
> > > +	# 6ghz band
> > > +	# https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
> > > +	# https://docs.fcc.gov/public/attachments/FCC-20-51A1_Rcd.pdf
> > > +	# max. 30 dBm AP @ 320MHz, 27 dBm AP @ 160MHz, 6 dB less for clients
> > > +	(5925 - 7125 @ 320), (30), NO-OUTDOOR, AUTO-BW
> > > +	(5925 - 7125 @ 320), (24), NO-OUTDOOR, AUTO-BW, NO-IR
> > 
> > The kernel doesn't currently support multiple rules with different flags
> > for the same range. This is an issue that's come up several times, but
> > so far nothing has been done about it.
> > 
> > Even ingoring that, I don't think these rules accomplish the intended
> > purpose. There's nothing that would require a client device to use the
> > NO-IR rule, so they could end up using the higher power limit and
> > transmitting before detecting transmission from an AP.
> > 
> > I also suspect that we should be able to express the AFC requirement in
> > the database before permitting AP operation in this range.
> > 
> > Currently I think the best we're able to do is to use the lowest common
> > denominator, which is the 24 dBm rule with NO-IR.
> > 
> > Thanks,
> > Seth
> 
> Hi, sorry for intruding.
> 
> I thought max EIRP rule for larger bandwidth also applies to smaller
> bandwidth, that means we would use 24 dBm tx power with 20 MHz channel as
> well. But the regulation limits PSD to -1 dBm/MHz and it leads to 12 dBm for
> 20 MHz. Shouldn't we use 12 dBm rule to fit the smallest bandwidth?
> 
> I still don't understand exactly how the rules work, my apologies if I am
> mistaken.

Before I respond, let me be upfront about my limitations. I'm not an RF
engineer. My day job no longer has anything to do with wireless and has
not for a number of years now. I haven't had time to really keep up with
recent developments either, so my impressions are based on some light
research and what I remember of information I rarely use nowadays.

After doing a little bit of reading, I suspect that you are probably
right (in principle at least, I didn't check the math). It seems there's
been a movement towards specifying PSD so that larger bandwidths can
effectively have a higher max EIRP than lower bandwitdths to overcome
diminishing SNR with increasing bandwidth.

That leaves us in the unfortunate position of needing to specify an EIRP
suitable for a bandwidth of 20 MHz when larger bandwidths could be using
a higher power limit. It seems like the Linux regulatory framework needs
to evolve to support PSD limits. I don't currently have the time or the
inclination to do this work though, and until someone does we're stuck
with the status quo.

Thanks,
Seth

Re: [wireless-regdb] wireless-regdb: Update regulatory rules for the US on 6 GHz band

[b.K.il.h.u+tigbuh]

Sorry to chime in like this. I haven't even read the linked
documentation, but whatever the final solution will be, I would prefer
if we committed the lowest, safe power levels while we are actively
researching, deciding and implementing a final solution. We can always
raise limits later on.

On Mon, Dec 20, 2021 at 10:02 PM Seth Forshee <sforshee@kernel.org> wrote:
>
> On Sat, Dec 18, 2021 at 04:34:13PM +0900, Sungbo Eo wrote:
> > On 2021-12-18 06:55, sforshee@kernel.org wrote:
> > > On Mon, Dec 13, 2021 at 09:19:50AM +0000, Asura Liu (asuliu) wrote:
> > > >  From 3db25ea674232fea6a5efca292f6ed3fd8eba7a2 Mon Sep 17 00:00:00 2001
> > > > From: Asura Liu <asuliu@cisco.com>
> > > > Date: Mon, 13 Dec 2021 16:46:28 +0800
> > > > Subject: [PATCH] wireless-regdb: Update regulatory rules for the US on 6 GHz
> > > > band
> > > > MIME-Version: 1.0
> > > > Content-Type: text/plain; charset=UTF-8
> > > > Content-Transfer-Encoding: 8bit
> > > >
> > > > According to FCC 20-51, FCC adopts rules to unlicensed use of the 6 GHz band:
> > > > "59. Third, the Commission limits the low-power indoor access points to lower power levels than the standard-power access points that operate under the control of an AFC. Consistent with the Commission's approach for the existing U-NII bands, the Commission specifies both a maximum power spectral density and an absolute maximum transmit power, both in terms of EIRP. Specifically, the Commission allows a maximum radiated power spectral density of 5 dBm per 1 megahertz and an absolute maximum radiated channel power of 30 dBm for the maximum permitted 320-megahertz channel (or 27 dBm for a 160-megahertz channel). In addition, to ensure that client devices remain in close proximity to the indoor access points, the Commission limits their PSD and maximum transmit power to 6 dB below the power permitted for the access points."
> > > > See https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
> > > >
> > > > And 47 CFR § 15.407 describe this as following:
> > > > (a) (5) For an indoor access point operating in the 5.925-7.125 GHz band, the maximum power spectral density must not exceed 5 dBm e.i.r.p. in any 1-megahertz band. In addition, the maximum e.i.r.p. over the frequency band of operation must not exceed 30 dBm.
> > > > (a) (8) For client devices operating under the control of an indoor access point in the 5.925-7.125 GHz bands, the maximum power spectral density must not exceed −1 dBm e.i.r.p. in any 1-megahertz band, and the maximum e.i.r.p. over the frequency band of operation must not exceed 24 dBm.
> > >
> > > Thanks for the patch. A couple of quick notes about the patch
> > > description. It's preferred to wrap lines in the body at around 75
> > > characters, and it's required that you include a Signed-off-by tag
> > > indicating your agreement to the DCO for your contribution (see
> > > CONTRIBUTING).
> > >
> > > Additional comments below.
> > >
> > > > ---
> > > > db.txt | 6 ++++++
> > > > 1 file changed, 6 insertions(+)
> > > >
> > > > diff --git a/db.txt b/db.txt
> > > > index b898799..c6ef9b6 100644
> > > > --- a/db.txt
> > > > +++ b/db.txt
> > > > @@ -1606,6 +1606,12 @@ country US: DFS-FCC
> > > >   # https://www.federalregister.gov/documents/2021/05/03/2021-08802/use-of-the-5850-5925-ghz-band
> > > >   # max. 33 dBm AP @ 20MHz, 36 dBm AP @ 40Mhz+, 6 dB less for clients
> > > >   (5850 - 5895 @ 40), (27), NO-OUTDOOR, AUTO-BW, NO-IR
> > > > + # 6ghz band
> > > > + # https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
> > > > + # https://docs.fcc.gov/public/attachments/FCC-20-51A1_Rcd.pdf
> > > > + # max. 30 dBm AP @ 320MHz, 27 dBm AP @ 160MHz, 6 dB less for clients
> > > > + (5925 - 7125 @ 320), (30), NO-OUTDOOR, AUTO-BW
> > > > + (5925 - 7125 @ 320), (24), NO-OUTDOOR, AUTO-BW, NO-IR
> > >
> > > The kernel doesn't currently support multiple rules with different flags
> > > for the same range. This is an issue that's come up several times, but
> > > so far nothing has been done about it.
> > >
> > > Even ingoring that, I don't think these rules accomplish the intended
> > > purpose. There's nothing that would require a client device to use the
> > > NO-IR rule, so they could end up using the higher power limit and
> > > transmitting before detecting transmission from an AP.
> > >
> > > I also suspect that we should be able to express the AFC requirement in
> > > the database before permitting AP operation in this range.
> > >
> > > Currently I think the best we're able to do is to use the lowest common
> > > denominator, which is the 24 dBm rule with NO-IR.
> > >
> > > Thanks,
> > > Seth
> >
> > Hi, sorry for intruding.
> >
> > I thought max EIRP rule for larger bandwidth also applies to smaller
> > bandwidth, that means we would use 24 dBm tx power with 20 MHz channel as
> > well. But the regulation limits PSD to -1 dBm/MHz and it leads to 12 dBm for
> > 20 MHz. Shouldn't we use 12 dBm rule to fit the smallest bandwidth?
> >
> > I still don't understand exactly how the rules work, my apologies if I am
> > mistaken.
>
> Before I respond, let me be upfront about my limitations. I'm not an RF
> engineer. My day job no longer has anything to do with wireless and has
> not for a number of years now. I haven't had time to really keep up with
> recent developments either, so my impressions are based on some light
> research and what I remember of information I rarely use nowadays.
>
> After doing a little bit of reading, I suspect that you are probably
> right (in principle at least, I didn't check the math). It seems there's
> been a movement towards specifying PSD so that larger bandwidths can
> effectively have a higher max EIRP than lower bandwitdths to overcome
> diminishing SNR with increasing bandwidth.
>
> That leaves us in the unfortunate position of needing to specify an EIRP
> suitable for a bandwidth of 20 MHz when larger bandwidths could be using
> a higher power limit. It seems like the Linux regulatory framework needs
> to evolve to support PSD limits. I don't currently have the time or the
> inclination to do this work though, and until someone does we're stuck
> with the status quo.
>
> Thanks,
> Seth
>
> _______________________________________________
> wireless-regdb mailing list
> wireless-regdb@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/wireless-regdb

Re: [wireless-regdb] wireless-regdb: Update regulatory rules for the US on 6 GHz band

[Seth Forshee]

(Adding patch author back to Cc)

On Tue, Feb 08, 2022 at 07:12:33PM +0100, b.K.il.h.u+tigbuh@gmail.com wrote:
> Sorry to chime in like this. I haven't even read the linked
> documentation, but whatever the final solution will be, I would prefer
> if we committed the lowest, safe power levels while we are actively
> researching, deciding and implementing a final solution. We can always
> raise limits later on.

Yes, I will not be applying the patch as-is. In addition to my other
comments, the power limits will need to be adjusted to meet the PSD
limits on a 20 MHz channel.

Seth

> On Mon, Dec 20, 2021 at 10:02 PM Seth Forshee <sforshee@kernel.org> wrote:
> >
> > On Sat, Dec 18, 2021 at 04:34:13PM +0900, Sungbo Eo wrote:
> > > On 2021-12-18 06:55, sforshee@kernel.org wrote:
> > > > On Mon, Dec 13, 2021 at 09:19:50AM +0000, Asura Liu (asuliu) wrote:
> > > > >  From 3db25ea674232fea6a5efca292f6ed3fd8eba7a2 Mon Sep 17 00:00:00 2001
> > > > > From: Asura Liu <asuliu@cisco.com>
> > > > > Date: Mon, 13 Dec 2021 16:46:28 +0800
> > > > > Subject: [PATCH] wireless-regdb: Update regulatory rules for the US on 6 GHz
> > > > > band
> > > > > MIME-Version: 1.0
> > > > > Content-Type: text/plain; charset=UTF-8
> > > > > Content-Transfer-Encoding: 8bit
> > > > >
> > > > > According to FCC 20-51, FCC adopts rules to unlicensed use of the 6 GHz band:
> > > > > "59. Third, the Commission limits the low-power indoor access points to lower power levels than the standard-power access points that operate under the control of an AFC. Consistent with the Commission's approach for the existing U-NII bands, the Commission specifies both a maximum power spectral density and an absolute maximum transmit power, both in terms of EIRP. Specifically, the Commission allows a maximum radiated power spectral density of 5 dBm per 1 megahertz and an absolute maximum radiated channel power of 30 dBm for the maximum permitted 320-megahertz channel (or 27 dBm for a 160-megahertz channel). In addition, to ensure that client devices remain in close proximity to the indoor access points, the Commission limits their PSD and maximum transmit power to 6 dB below the power permitted for the access points."
> > > > > See https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
> > > > >
> > > > > And 47 CFR § 15.407 describe this as following:
> > > > > (a) (5) For an indoor access point operating in the 5.925-7.125 GHz band, the maximum power spectral density must not exceed 5 dBm e.i.r.p. in any 1-megahertz band. In addition, the maximum e.i.r.p. over the frequency band of operation must not exceed 30 dBm.
> > > > > (a) (8) For client devices operating under the control of an indoor access point in the 5.925-7.125 GHz bands, the maximum power spectral density must not exceed −1 dBm e.i.r.p. in any 1-megahertz band, and the maximum e.i.r.p. over the frequency band of operation must not exceed 24 dBm.
> > > >
> > > > Thanks for the patch. A couple of quick notes about the patch
> > > > description. It's preferred to wrap lines in the body at around 75
> > > > characters, and it's required that you include a Signed-off-by tag
> > > > indicating your agreement to the DCO for your contribution (see
> > > > CONTRIBUTING).
> > > >
> > > > Additional comments below.
> > > >
> > > > > ---
> > > > > db.txt | 6 ++++++
> > > > > 1 file changed, 6 insertions(+)
> > > > >
> > > > > diff --git a/db.txt b/db.txt
> > > > > index b898799..c6ef9b6 100644
> > > > > --- a/db.txt
> > > > > +++ b/db.txt
> > > > > @@ -1606,6 +1606,12 @@ country US: DFS-FCC
> > > > >   # https://www.federalregister.gov/documents/2021/05/03/2021-08802/use-of-the-5850-5925-ghz-band
> > > > >   # max. 33 dBm AP @ 20MHz, 36 dBm AP @ 40Mhz+, 6 dB less for clients
> > > > >   (5850 - 5895 @ 40), (27), NO-OUTDOOR, AUTO-BW, NO-IR
> > > > > + # 6ghz band
> > > > > + # https://www.federalregister.gov/documents/2020/05/26/2020-11236/unlicensed-use-of-the-6-ghz-band
> > > > > + # https://docs.fcc.gov/public/attachments/FCC-20-51A1_Rcd.pdf
> > > > > + # max. 30 dBm AP @ 320MHz, 27 dBm AP @ 160MHz, 6 dB less for clients
> > > > > + (5925 - 7125 @ 320), (30), NO-OUTDOOR, AUTO-BW
> > > > > + (5925 - 7125 @ 320), (24), NO-OUTDOOR, AUTO-BW, NO-IR
> > > >
> > > > The kernel doesn't currently support multiple rules with different flags
> > > > for the same range. This is an issue that's come up several times, but
> > > > so far nothing has been done about it.
> > > >
> > > > Even ingoring that, I don't think these rules accomplish the intended
> > > > purpose. There's nothing that would require a client device to use the
> > > > NO-IR rule, so they could end up using the higher power limit and
> > > > transmitting before detecting transmission from an AP.
> > > >
> > > > I also suspect that we should be able to express the AFC requirement in
> > > > the database before permitting AP operation in this range.
> > > >
> > > > Currently I think the best we're able to do is to use the lowest common
> > > > denominator, which is the 24 dBm rule with NO-IR.
> > > >
> > > > Thanks,
> > > > Seth
> > >
> > > Hi, sorry for intruding.
> > >
> > > I thought max EIRP rule for larger bandwidth also applies to smaller
> > > bandwidth, that means we would use 24 dBm tx power with 20 MHz channel as
> > > well. But the regulation limits PSD to -1 dBm/MHz and it leads to 12 dBm for
> > > 20 MHz. Shouldn't we use 12 dBm rule to fit the smallest bandwidth?
> > >
> > > I still don't understand exactly how the rules work, my apologies if I am
> > > mistaken.
> >
> > Before I respond, let me be upfront about my limitations. I'm not an RF
> > engineer. My day job no longer has anything to do with wireless and has
> > not for a number of years now. I haven't had time to really keep up with
> > recent developments either, so my impressions are based on some light
> > research and what I remember of information I rarely use nowadays.
> >
> > After doing a little bit of reading, I suspect that you are probably
> > right (in principle at least, I didn't check the math). It seems there's
> > been a movement towards specifying PSD so that larger bandwidths can
> > effectively have a higher max EIRP than lower bandwitdths to overcome
> > diminishing SNR with increasing bandwidth.
> >
> > That leaves us in the unfortunate position of needing to specify an EIRP
> > suitable for a bandwidth of 20 MHz when larger bandwidths could be using
> > a higher power limit. It seems like the Linux regulatory framework needs
> > to evolve to support PSD limits. I don't currently have the time or the
> > inclination to do this work though, and until someone does we're stuck
> > with the status quo.
> >
> > Thanks,
> > Seth
> >
> > _______________________________________________
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> > wireless-regdb@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/wireless-regdb
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