802.11ax has been code-named Wi-Fi6 and its usage in the 6GHz band which has been opened by FCC (and others following the suite) has been code-named Wi-Fi 6E :).Let us discuss the details of the channels and rules along with how we coordinate with incumbent services meeting the I/N ratio of -6dB to avoid interference to the incumbents.
6GHz spectrum (Wi-Fi6E: 5.925-7.125 GHz) is already in use by incumbent services, so, the unlicensed operation in this band is divided into two categories based on power usage derived from UNII-3 rules, with additional protection offered by AFC (Automated Frequency coordination). See below power limits (#8)
A: 5.925-6.425 GHz (UNII-5) and 6.525-6.875 GHz (UNII-7) = 850MHz of Spectrum + (Standard power + AFC (or) Low power-Indoor + No-AFC)
Incumbent Services: Fixed services, like PTP Microware links and FS (Fixed Satellite) Receivers which tend to be directed.
As these services are fixed, we don't need to use a dynamic scheme like DFS in UNII-2A, instead simply knowing the range of their operation a.k.a. 'contours', should suffice to stay away from them.
AFC is nothing but a simple database (Maintained by AFC Registrars and AFC Operators) to determine the contours of incumbents and make sure unlicensed elements do not disturb them (enforced by AFC masters which control AFC Clients) (#3). FCC databases show 47,695 call signs in the 6GHz, so, operators need to define the contours of their links and publish them to masters viz AFC. Below picture summarizes this (#7)
At the bottom of the below pic, you can see available channels in green generated using AFC, that's a lot of free channels, though only 1X160MHz channel, that's SFO :-). (Using FCC and COALS database (#7) and using the RLAN Group propagation model (#8))
data
B: 6.425-6.525 GHz (UNII-6) and 6.875-7.125 GHz (UNII-8) = 350MHz of Spectrum + Low power-Indoor + No-AFC
Incumbent Services: Mobile Services: Broadcast Auxiliary Service, Cable Television Relay Service, etc.
Even though these are dynamic but are more actively present using DFS is unsuitable (it's mainly for avoiding interference with intermittent signals like radars), hence a reduced power is proposed instead (at this power levels they don't interfere with incumbents) (#6)
Summary: This gives us a total of 7X160MHz channels in the US and 3X160MHz in Europe (only UNII-5) (#5), which is quite a big win for Wi-Fi.
What do you think about gaining a 1.2GHz of the new spectrum? How can this be used by new applications using 11ax/wifi6E, please share your thoughts?
References:
- https://www.fcc.gov/document/chairman-pai-proposes-new-6-ghz-band-rules-unleash-unlicensed-use
- https://wifinowglobal.com/news-and-blog/wi-fi-in-6-ghz-tech-giants-posit-new-scheme-for-protection-of-6-ghz-incumbents/
- https://ecfsapi.fcc.gov/file/1080236093470/Ex%20Parte%20(Aug.%202%202018)%20(FINAL).pdf
- https://docs.fcc.gov/public/attachments/DOC-354364A1.pdf
- http://www.cdot.in/cdotweb/assets/docs/events/gbmls19/WiFi_6_and_beyond(Dorothy).pdf (Slides #22/23)
- https://ecfsapi.fcc.gov/file/108080219920074/WFA%20Ex%20Parte%20Letter.pdf
- https://ecfsapi.fcc.gov/file/100302586574/2019-10-01%20OET%20AFC%20Demo%20Ex%20Parte.pdf
- https://docs.fcc.gov/public/attachments/DOC-363490A1.pdf
- https://ecfsapi.fcc.gov/file/10216633127609/6%20GHz%20RLAN%20Group%20Comments%20(Feb%2015%202019).pdf pages 43-44
