4 ms·

I can't say that AFC excites me: https://docs.fcc.gov/public/attachments/DOC-354364A1.pdf https://docs.fcc.gov/public/attachments/DOC-354364A1.pdf Devices will

I can't say that AFC excites me: https://docs.fcc.gov/public/attachments/DOC-354364A1.pdf https://docs.fcc.gov/public/attachments/DOC-354364A1.pdf Devices will be sending their GPS coordinates and serial numbers to the FCC to verify what frequencies they can use. It's unclear to me why the serial numbers need to be sent.

teruakohatu 6y ago
Surley the FCC could just publish a data file that clients download and lookup their frequencies.
- jrockway 6y ago
  They tried the honor system, it was called DFS. According to Wikipedia: "Prior to the introduction of Wi-Fi, one of the biggest applications of 5GHz band was the Terminal Doppler Weather Radar. The decision to use 5 GHz spectrum for Wi-Fi was finalized in World Radiocommunication Conference in 2003; however, meteorological community was not involved in the process. The subsequent lax implementation and misconfiguration of DFS had caused significant disruption in weather radar operations in a number of countries around the world. In Hungary, the weather radar system was declared non-operational for more than a month. Due to the severity of interference, South African weather services ended up abandoning C band operation, switching their radar network to S band." TWDR is a high-resolution doppler radar that measures winds on airport approach paths to detect wind shear and microbursts. It's a life-critical system. It would be nice to use the bandwidth for WiFi, and the FCC made every opportunity to allow it, but WiFi vendors didn't play nice.
  - teruakohatu 6y ago
    I don't disagree with you but I am not sure the FCC cares that much about weather sats. They happily auctioned off 24GHz spectrum. https://arstechnica.com/tech-policy/2019/05/5g-networks-will-likely-interfere-with-us-weather-satellites-navy-warns/ https://arstechnica.com/tech-policy/2019/05/5g-networks-will...
    - jrockway 6y ago
      I did some research and found a lot of quite a bit of conflicting information. One source [1] claims that 23.8GHz is the downlink frequency for the weather satellite, which I don't think is the case. It seems that water vapor emits radiation at that frequency, and the satellites detect it. Because radio signals at that frequency are also attenuated by water vapor, much of the signal from the lower levels of the atmosphere are blocked: all you can see are the tops of the clouds. [2] This leads me to believe that 5G signals are likely to be attenuated before they reach the satellite. It is also important to note that the interesting frequency is 23.8GHz, but the spectrum that was auctioned off is from 24.25 to 24.45 and 24.75 to 25.25GHz... so not overlapping. The Ars article links to a primary source [3] claiming that the Navy desires a guarantee that signals outside of the allocated range are attenuated by -57dB instead of -20dB. Typically, designers of RF equipment do not want to transmit power that their receivers cannot receive. Power is expensive to waste. So given the separation between the 5G band and water vapor, the attenuation intrinsic to 23.8GHz signals when travelling through the atmosphere, and a desire to produce efficient electronics (better battery life sells phones)... I'm betting this won't be a big problem. Obviously, the scientists that rely on the data are kind of obligated to say "never do anything with the RF spectrum, it interferes with our research", but it's up to the FCC to balance their concerns with the reality that someone other than weather researchers need to use the RF spectrum. Anyway, this is all theoretical, whereas DFS is not theoretical. You could watch it actively interfere with weather radar, so the next generation of WiFi is using something else. Obviously if 5G interferes with weather satellites, they'll probably ask the licencees to turn their equipment off until they can mitigate the degradation of another licensed user. [1] https://news.ucar.edu/132669/ucar-statement-opening-24-ghz-spectrum https://news.ucar.edu/132669/ucar-statement-opening-24-ghz-s... [2] https://www.theweatherprediction.com/habyhints2/523/ https://www.theweatherprediction.com/habyhints2/523/ [3] https://www.wyden.senate.gov/imo/media/doc/Navy%2024Hz%205G%20Spectrum%20Impacts.pdf https://www.wyden.senate.gov/imo/media/doc/Navy%2024Hz%205G%...
  - stefan_ 6y ago
    And yet here we are, lives still.. living? The FCC needs to do this much more, radio spectrum is a massively valuable limited resource and you either demonstrate technological excellence or you get out of the way of those who can. We can't have GHz worth of spectrum untouched because people don't want to upgrade their 1960s hardware and/or technology.
    - Steltek 6y ago
      And behind the scenes, engineers were working quickly to identify and fix problems on what was previously reserved spectrum for a life safety system. It's also a quintessential public good; saying that it should be taken for private use is absurd and extremely short sighted. Further, TDWR was developed in the 90's and has undergone upgrades since then. Don't dismiss it as some Apollo-era PDP-11 sitting in a closet somewhere just because you don't know what it is.
    - deleted 6y ago
      [deleted]
- verandaguy 6y ago
  Nitpick: the FTC is in charge of US consumer protection. You probably wanted to mention the FCC.
  - teruakohatu 6y ago
    Thanks!
karlshea 6y ago
To me it sounded like that was only for APs that would be used outdoors? The "for indoor use only" APs for home users I don't think would need to have AFC.
brokencode 6y ago
Perhaps to create more accurate databases for WiFi positioning? https://en.wikipedia.org/wiki/Wi-Fi_positioning_system https://en.wikipedia.org/wiki/Wi-Fi_positioning_system Or potentially to help make the spectrum allocation in an area more efficient? Maybe that information could be used to help position those point-to-point microwave networks mentioned in the article.
mjevans 6y ago
I agree that it's very unclear why that is required. The source IP (v4 or v6) address for the record update, along with the timestamp of update, is already sufficiently identifying, and would be obtained even offhand in a query process to check a given area for interference issues. The requirement to use GPS also practically mandates that these routers HAVE a GPS receiver inside. My biggest worries relate to the cost and probable barrier to projects like OpenWRT supporting these devices.
- ac29 6y ago
  Its required because there are existing, licensed users of that spectrum who have a legal right not to be interfered with. Its a compromise - it allows licensed users to continue to operate without interference, but also allows the spectrum to be used without a license in areas where doing so wouldnt create interference.
- tradertef 6y ago
  FCC rules do not require usage of GPS. It could be any technology, details TBD. Higher accuracy returns more available spectrum.
totetsu 6y ago
Will this lead to restriction on installing open-source firmwares on routers too?
verandaguy 6y ago
I'm concerned about what this means for hardware sold and used in parts of the world which aren't the US. What guarantees do I have, as someone in Canada, that my device won't be reporting this data to the US federal government for dubious-at-best reasons (especially in the context of international use)?
- rkagerer 6y ago
  Question: How hard would it be to block it via firewall?
  - milankragujevic 6y ago
    If you only have one device (all in one AP/Router/Switch), very. If you have a firewall in front of the APs, extremely easy. You can take a few minutes to check what DNS entries and IPs it's talking to and block that.
ggreer 6y ago
Note that AFC is only required for high power communications. Low power devices (<250mW & <11dBi in any 1MHz band) don't need AFC. It looks like the rules are meant to avoid AFC for consumer gear and require it for professional outdoor installations.
tradertef 6y ago
So much confusion in the comments. AFC will be operated by private 3rd party companies. FCC does not have the data unless they ask to private companies in the case of interference issues. Location information is needed to determine channel availability which is highly dependent on the location.

teruakohatu 6y ago

Surley the FCC could just publish a data file that clients download and lookup their frequencies.

jrockway 6y ago
They tried the honor system, it was called DFS. According to Wikipedia: "Prior to the introduction of Wi-Fi, one of the biggest applications of 5GHz band was the Terminal Doppler Weather Radar. The decision to use 5 GHz spectrum for Wi-Fi was finalized in World Radiocommunication Conference in 2003; however, meteorological community was not involved in the process. The subsequent lax implementation and misconfiguration of DFS had caused significant disruption in weather radar operations in a number of countries around the world. In Hungary, the weather radar system was declared non-operational for more than a month. Due to the severity of interference, South African weather services ended up abandoning C band operation, switching their radar network to S band." TWDR is a high-resolution doppler radar that measures winds on airport approach paths to detect wind shear and microbursts. It's a life-critical system. It would be nice to use the bandwidth for WiFi, and the FCC made every opportunity to allow it, but WiFi vendors didn't play nice.
- teruakohatu 6y ago
  I don't disagree with you but I am not sure the FCC cares that much about weather sats. They happily auctioned off 24GHz spectrum. https://arstechnica.com/tech-policy/2019/05/5g-networks-will-likely-interfere-with-us-weather-satellites-navy-warns/ https://arstechnica.com/tech-policy/2019/05/5g-networks-will...
  - jrockway 6y ago
    I did some research and found a lot of quite a bit of conflicting information. One source [1] claims that 23.8GHz is the downlink frequency for the weather satellite, which I don't think is the case. It seems that water vapor emits radiation at that frequency, and the satellites detect it. Because radio signals at that frequency are also attenuated by water vapor, much of the signal from the lower levels of the atmosphere are blocked: all you can see are the tops of the clouds. [2] This leads me to believe that 5G signals are likely to be attenuated before they reach the satellite. It is also important to note that the interesting frequency is 23.8GHz, but the spectrum that was auctioned off is from 24.25 to 24.45 and 24.75 to 25.25GHz... so not overlapping. The Ars article links to a primary source [3] claiming that the Navy desires a guarantee that signals outside of the allocated range are attenuated by -57dB instead of -20dB. Typically, designers of RF equipment do not want to transmit power that their receivers cannot receive. Power is expensive to waste. So given the separation between the 5G band and water vapor, the attenuation intrinsic to 23.8GHz signals when travelling through the atmosphere, and a desire to produce efficient electronics (better battery life sells phones)... I'm betting this won't be a big problem. Obviously, the scientists that rely on the data are kind of obligated to say "never do anything with the RF spectrum, it interferes with our research", but it's up to the FCC to balance their concerns with the reality that someone other than weather researchers need to use the RF spectrum. Anyway, this is all theoretical, whereas DFS is not theoretical. You could watch it actively interfere with weather radar, so the next generation of WiFi is using something else. Obviously if 5G interferes with weather satellites, they'll probably ask the licencees to turn their equipment off until they can mitigate the degradation of another licensed user. [1] https://news.ucar.edu/132669/ucar-statement-opening-24-ghz-spectrum https://news.ucar.edu/132669/ucar-statement-opening-24-ghz-s... [2] https://www.theweatherprediction.com/habyhints2/523/ https://www.theweatherprediction.com/habyhints2/523/ [3] https://www.wyden.senate.gov/imo/media/doc/Navy%2024Hz%205G%20Spectrum%20Impacts.pdf https://www.wyden.senate.gov/imo/media/doc/Navy%2024Hz%205G%...
- stefan_ 6y ago
  And yet here we are, lives still.. living? The FCC needs to do this much more, radio spectrum is a massively valuable limited resource and you either demonstrate technological excellence or you get out of the way of those who can. We can't have GHz worth of spectrum untouched because people don't want to upgrade their 1960s hardware and/or technology.
  - Steltek 6y ago
    And behind the scenes, engineers were working quickly to identify and fix problems on what was previously reserved spectrum for a life safety system. It's also a quintessential public good; saying that it should be taken for private use is absurd and extremely short sighted. Further, TDWR was developed in the 90's and has undergone upgrades since then. Don't dismiss it as some Apollo-era PDP-11 sitting in a closet somewhere just because you don't know what it is.
  - deleted 6y ago
    [deleted]
verandaguy 6y ago
Nitpick: the FTC is in charge of US consumer protection. You probably wanted to mention the FCC.
- teruakohatu 6y ago
  Thanks!

karlshea 6y ago

To me it sounded like that was only for APs that would be used outdoors? The "for indoor use only" APs for home users I don't think would need to have AFC.

brokencode 6y ago

Perhaps to create more accurate databases for WiFi positioning? https://en.wikipedia.org/wiki/Wi-Fi_positioning_system https://en.wikipedia.org/wiki/Wi-Fi_positioning_system Or potentially to help make the spectrum allocation in an area more efficient? Maybe that information could be used to help position those point-to-point microwave networks mentioned in the article.

mjevans 6y ago

I agree that it's very unclear why that is required. The source IP (v4 or v6) address for the record update, along with the timestamp of update, is already sufficiently identifying, and would be obtained even offhand in a query process to check a given area for interference issues. The requirement to use GPS also practically mandates that these routers HAVE a GPS receiver inside. My biggest worries relate to the cost and probable barrier to projects like OpenWRT supporting these devices.

ac29 6y ago
Its required because there are existing, licensed users of that spectrum who have a legal right not to be interfered with. Its a compromise - it allows licensed users to continue to operate without interference, but also allows the spectrum to be used without a license in areas where doing so wouldnt create interference.
tradertef 6y ago
FCC rules do not require usage of GPS. It could be any technology, details TBD. Higher accuracy returns more available spectrum.

totetsu 6y ago

Will this lead to restriction on installing open-source firmwares on routers too?

verandaguy 6y ago

I'm concerned about what this means for hardware sold and used in parts of the world which aren't the US. What guarantees do I have, as someone in Canada, that my device won't be reporting this data to the US federal government for dubious-at-best reasons (especially in the context of international use)?

rkagerer 6y ago
Question: How hard would it be to block it via firewall?
- milankragujevic 6y ago
  If you only have one device (all in one AP/Router/Switch), very. If you have a firewall in front of the APs, extremely easy. You can take a few minutes to check what DNS entries and IPs it's talking to and block that.

ggreer 6y ago

Note that AFC is only required for high power communications. Low power devices (<250mW & <11dBi in any 1MHz band) don't need AFC. It looks like the rules are meant to avoid AFC for consumer gear and require it for professional outdoor installations.

tradertef 6y ago

So much confusion in the comments. AFC will be operated by private 3rd party companies. FCC does not have the data unless they ask to private companies in the case of interference issues. Location information is needed to determine channel availability which is highly dependent on the location.