US 6GHz: How to proceed

For Developers
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Hi, I’m starting this thread to figure out how to deal with the (IMO ludicrous) US regulatory restrictions for 6GHz emissions. 6GHz devices are growing in popularity, and those that do not use an internal (Qualcomm) regulatory database, such as Mediatek, Airoha, etc., are unable to bring up an access point on the 6GHz band with OpenWrt’s standard regdb. This will become a larger issue as right now, 6GHz is disabled on vanilla OpenWrt builds and can only be re-enabled with regdb patches, which may end up violating emission laws as they currently stand. There are 2 issues that seem to be present:

  1. Different channel widths are limited to different Power Spectral Densities (PSD). See https://lore.kernel.org/wireless-regdb/CAPRryQp6j4UKvLZCkMAuQdaxepMBETQUJ1eNULJSh3ZWXC0f5Q@mail.gmail.com/ for more details.
  2. 6GHz does not require a license and does not require use of an Automatic Frequency Coordinator (AFC) only when used indoors. https://www.federalregister.gov/d/2020-11236/p-61. Outdoor use is subject to communicating with an AFC, and is outside the scope of this discussion.

It appears that the upstream regdb maintainers have no interest in solving this problem, so I think it must be in the hands of OpenWrt. The path forward I see is adding an intermediate state for configuring/enabling 6GHz access points and clients in the US.

  1. Apply a patch to the regdb that removes NO-IR from 6GHz in US.
  2. Add an indoor-use-only option to uci/luci that must be manually selected, to ensure that the responsibility lives with the device operator. If this option is not present, the AP should not come up (and appropriate logging/warnings should be made to the user)
  3. Add a check that verifies PSD requirements are met for both AP and client mode (since they’re different). I expect that AP+STA would be subject to STA regulations

Other references:

Thoughts?

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Upstream hasn't looked at this much due to having to support old kernels. Openwrt could patch regdb; however, if they mess this up the FCC may fine them.

The only solution I see is to have an optional patched wireless-regdb-6Ghz.apk in the repo. US users would install openwrt and then have to install it. That should be enough to cover openwrt legally as it would not be included in the default install.

Short term solution is to apply stangri's patch to wireless-regdb found here:

Just build wireless-regdb. Every single update, you must reinstall your patched wireless-regdb apk.

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The "easy way" would limit performance:

  • Enabling 6GHz... limited to an EIRP of 12dBm to respect PSD limits in 20MHz operation (since currently, frequency-dependent PSD can't be specified in regdb)
(5925 - 7125 @ 320), (12), NO-OUTDOOR

The proper solution would require significant patching:

  • splitting up NO-IR back into PASSIVE-SCAN (for STA mode) and NO-IBSS
  • adding a new property into wireless-regdb to mark LPI ranges
  • cfg80211 supporting said changes
  • mac80211 and the rest of the other wireless drivers properly reporting their PSD (it has been broken in the past)
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"Why doesn't 6Ghz work?!?" "Why does 6Ghz suck with openwrt?!?" + "Why does MLO suck with openwrt?!?"