wireless-regdb: Permit 320 MHz bandwidth in 6 GHz band in ETSI/CEPT

[rmandrad]

Patch taken from https://patchwork.kernel.org/project/linux-wireless/patch/20250125011210.56371-1-rj@quartiq.de/ this fixes a number of issues for users in EU that want to use 802.11be on 320MHz band.

This increases the allowed bandwidth from 160 to 320 MHz for the 5945-6425 MHz band to support 802.11be (Wi-Fi 7) EHT-320 for the ETSI/CEPT harmonized countries (EU + CH/LI/NO and TR).

Previously the bandwidth limit was set to 160 MHz to match 802.11ax (including the 6 GHz extension called Wi-Fi 6e). This limit is not supported by the current regulatory documents and should be relaxed to 320 MHz.

The 802.11be (Wi-Fi 7) standard defines EHT-OFDMA for a 320 MHz bandwidth. Devices (both AP and STA) supporting and using this are widely available now. The "6 GHz" band starting at 5945 MHz is the prime target for these wide channels. In the ETSI/CEPT harmonized countries the 5945-6425 MHz range has been allocated to WLAN. It can contain one 320 MHz channel centered at channel 31 (6105 MHz) and one overlapping channel at centered at 63 (6265 MHz).

Note that the supporting documents quoted currently do not have an upper bandwidth limit:

EU: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32021D1067&from=EN
and https://docdb.cept.org/download/4577

Adoption by e.g.
DE: https://www.bundesnetzagentur.de/SharedDocs/Downloads/DE/Sachgebiete/Telekommunikation/Unternehmen_Institutionen/Frequenzen/Allgemeinzuteilungen/MobilfunkDectWlanCBFunk/vfg552021WLAN6GHz.pdf

CH and LI: https://www.ofcomnet.ch/api/rir/1010/11 (note the explicit empty bandwidth limit)
NO: https://lovdata.no/dokument/SF/forskrift/2012-01-19-77
TR: https://www.btk.gov.tr/uploads/pages/ftm-teknik-olcutler-ek-5.pdf

Note also that the EC mandate to the CEPT to investigate the upper 6425-7125 MHz band for future use explicitly confirms that there is now (2024-12) one non-overlapping 320 MHz channel for 802.11be available in the existing "mid-band" (i.e. 2.4, 5, and 6 GHz) allocations: https://cept.org/files/6813/Mandate%20to%20CEPT%20upper%206%20GHz%20band.pdf (page 3).

The 160 MHz limits for the 5 GHz and 2.4 GHz bands can remain since there is no possible configuration for a 320 MHz channel there.

[hauke]

When these changes are accepted by upstream wireless-regdb we can apply them here too.

[rmandrad]

closing this pull and creating a new one to propose to align wireless-regdb to latest commit that includes this pull

[rmandrad]

for reference this is the new pull - #17951