By Claus Hetting, WiFi NOW CEO & Chairman
The US is arguably leading the world in enabling favourable regulation for 6 GHz Wi-Fi – but that doesn’t mean that current rules cannot be improved. Two rules in particular would boost Wi-Fi performance: Incorporating building entry loss (BEL) into AFC calculations for indoor standard power 6 GHz Wi-Fi and permitting higher power density for 6 GHz low power indoor (LPI) Wi-Fi. Here’s what all of that means.
The process to enable more and better Wi-Fi everywhere through more favourable 6 GHz Wi-Fi rule making by regulators is never ending – and now it looks like there’s a real chance that the FCC may adopt (at least) two more rule changes that could dramatically improve indoor Wi-Fi. The broad Wi-Fi industry – including special interest groups such as WiFiForward and a coalition of tech vendors – are largely united behind efforts to secure at least these two changes. The FCC issued its Notice of Proposed Rulemaking on 6 GHz rule improvements in February (the document can be found here).
“Allowing combined LPI and standard power APs – the FCC calls these ‘composite APs’ – to transmit indoor with greater power makes a lot of sense because of the building entry loss for Wi-Fi signals. Clearly, buildings attenuate Wi-Fi signals by a significant amount. This amount should be incorporated into AFC calculations and hence impact what 6 GHz transmissions are permitted, at what power levels, and where. The question then becomes how much higher power should be permitted,” says Michael Calabrese, Director Wireless Future Program & Senior Research Fellow OTI at New America Foundation.
AFC systems coordinate 6 GHz spectrum use to prevent interference with incumbent users while LPI refers to low-power indoor Wi-Fi operation.
While some AFC services have been granted a waiver to raise indoor standard power by 6 dB to account for BEL, the real and final number could and probably should be a lot higher, Michael Calabrese says. “Most Wi-Fi advocates agree the correct value should be at least 20.5 dB, which is the median established by the ITU years ago. Some others, including Wi-Fi Alliance and consumer advocates contend it should be closer to 30 dB to account for new construction that uses e-glass and better insulation to save energy. It of course remains to be seen what the FCC will accept. But there are good arguments in favour of a much higher value than 6 dB. This would be a huge boost to indoor Wi-Fi speed and coverage with 6 GHz standard power,” he says.
Raising LPI spectral power density for 6 GHz
The second FCC rule change that the Wi-Fi industry is pushing for hasn’t been specifically mentioned by the FCC although the FCC did encourage interested parties to submit suggestions on anything else that should reasonably be considered. This change involves raising the low power indoor (LPI) 6 GHz power spectral density from 5 dBm/MHz to 8 dBm/MHz.
“This suggestion has an interesting history in that the FCC has stated that the original 5 dBm/MHz value was selected based on extreme caution. A study by CableLabs from 2020 verified that 8 dBm/MHz would have no discernible adverse effect on incumbent users of the band. Meanwhile, a new study by a coalition of tech vendors has since verified that conclusion. This means there are now very good technical arguments in support of raising the LPI power spectral density level,” Michael Calabrese says.
Finally, it is generally expected that the FCC will allow 6 GHz LPI Wi-Fi to operate on cruise ships (we covered it here). Michael Calabrese says it is not clear when the changes could come into effect but that before the end of the year is a good guess, as it is unlikely that an increase in power levels for 6 GHz Wi-Fi is a controversial issue among FCC commissioners.
/Claus.
