Re: wireless-regdb: Please correct the regulatory rules for India (IN) on 2.4 GHz

[Seth Forshee <sforshee@kernel.org>]

On Sat, Mar 04, 2023 at 05:13:44PM -0600, Keshav wrote:
> Hello,
> 
> I noticed that wireless-regdb db.txt [1] has restricted India's 2.4
> GHz maximum power to only 20 dBm:
> 
> country IN:
>         (2402 - 2482 @ 40), (20)
> 
> However the Official Gazette of Government of India (PDF [3] linked in
> URL [2]) mentions that upto 30 dBm is allowed in the 2.4 GHz band.
> 
> 2.4 GHz Rules for India (IN): Pages 87 to 88 of PDF [3]
> 
> I would like to mention that I am not an expert in this topic. I am
> not sure if there's any other reason to restrict 2.4 GHz for India to
> 20 dBm in the db.txt. I also couldn't find any other official
> Government of India document that restricts the maximum power to 20
> dBm (due to some other reason). Please look into this and correct the
> regulatory rules for India if needed. Thank you.
> 
> Although not the topic of this email, you can also find the 5 GHz
> Rules for India in the same PDF [3] (pages 94 to 97) if interested.
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/sforshee/wireless-regdb.git/tree/db.txt?id=7f7a9f7bc6011b072b5427eced1ff19261764e95#n853
> 
> [2] https://dot.gov.in/spectrummanagement/gazette-notifications-delicensed-band
> 
> [3] https://dot.gov.in/sites/default/files/Gazette_Notifications.pdf

Sorry for the slow response. I've been attempting to research this as
time allows, but I haven't had a lot of time for it, and the information
is not well organized.

[1] was the most complete summary I found for spectrum use in India. In
particular Annex 1 has a table of GSR numbers relevant for unlicensed
spectrum, which for 2.4 GHz is GSR No. 45(E) [2] and for 5 GHz is GSR
No. 1048(E) [3]. It looks like the document you linked to just bundles
these and other GSRs together, so as far as I can tell the information
you provided looks accurate.

The database stores maximum EIRP, not transmitter output power, so I
think that 36 dBm is the correct value for 2.4 GHz (GSR No. 45(E) shows
an ERP of 36dBm, but based on the maximum transmitter power of 30 dBm I
think this is probably meant to be the EIRP).

The 5 GHz rules look mostly right, except that it looks like 5250-5350
and 5470-5725 MHz both require DFS. They also require TPC, which Linux
doesn't support, but the PSD limit restricts our max EIRP to below the
threshold where TPC is required.

So I think these are the correct rules for India:

country IN:
	(2400 - 2482 @ 40), (36)
	(5150 - 5250 @ 80), (30)
	(5250 - 5350 @ 80), (24), DFS
	(5470 - 5725 @ 160), (24), DFS
	(5725 - 5875 @ 80), (30)

If this looks right to you, I can send the patch to update the rules.

Thanks,
Seth

[1] https://dot.gov.in/sites/default/files/NFAP%202018.pdf
[2] https://dot.gov.in/spectrummanagement/delicensing-24-24835-ghz-band-gsr-45-e-5150-5350-ghz-gsr-46-e-and-5725-5875-ghz
[3] https://dot.gov.in/spectrummanagement/license-exemption-5-ghz-gsr-1048e-dated-22102018