15 ms·

The FAA is objecting to the use of the 3.5GHz band, as it's supposedly too close to the 4400-4700MHz radar altimeter band. This band is the primary one for 5G

The FAA is objecting to the use of the 3.5GHz band, as it's supposedly too close to the 4400-4700MHz radar altimeter band. This band is the primary one for 5G deployment world wide and interestingly no planes have been dropping or crashing due to it's use. Strange how the same planes landing in European capitals with widespread 3.5GHz 5G deployments seem to do fine there, but will experience dangerous problems on USA soil. 3.5GHz is also exlusively 5G and not used for anything cellular before. Outside of some old wimax deployments here and there, but those ware usually for fixed users not mobiles. 3.5GHz is also firmly in the centimeter bands. :)

tzs 5y ago
Europe is only using 3.4-3.8 GHz. The US is going up to 4.2 GHz.
- RF_Savage 5y ago
  Ah! That certainly explains some of it. I even checked and sure enough, the highest allocated block here is 3670 - 3800 MHz.
gdavisson 5y ago
AIUI the European usage of this band only goes up to 3.8GHz (see https://www.everythingrf.com/community/5g-frequency-bands-in-europe https://www.everythingrf.com/community/5g-frequency-bands-in... for example), but the FCC auctioned off band space up to 3.98GHz. Aircraft altimeters use the 4.2-4.4GHz band, so the new US allocation nearly halves the band gap. That is what the FAA is worried about.
- gruez 5y ago
  >halves the band gap. That is what the FAA is worried about. It's worth noting that a band gap of 200mhz is ridiculously wide, at least according to the top comment from the last thread https://news.ycombinator.com/item?id=29642777 https://news.ycombinator.com/item?id=29642777
- g_p 5y ago
  The UK makes available shared access licences in the 3.8 to 4.2 GHz band. These are power limited and location constrained, to manage interference with satellite earth stations. You can get a license in this band and run your own private 5G network in it. There doesn't appear to be any concern from the UK aviation regulator (the CAA). Perhaps they're able to achieve sufficient spatial separation from airports and their final approach paths, or perhaps they've found there aren't issues with the reduced transmit power available on these shared access licences? Nonetheless, it will be interesting to see if this 200 MHz guard really is insufficient in the US - at a certain point you need to consider if existing equipment needs to be replaced (like with the swapping of 800 and 700 MHz from digital TV to mobile, and the need for some people to put a band-stop filter onto their TV antenna feed to avoid interference from mobile networks).
  - PostThisTooFast 5y ago
  - sgent 5y ago
    Using this band is only an aviation problem if you're in the middle of an approach (approximately 20 miles from a runway, but not a big circle). Hence the location and power limitations.
darksaints 5y ago
3.5 is fine, that's CBRS. This is about C-Band, which is 3.7ghz to 4.2ghz in the US.
fomine3 5y ago
NTT Docomo operates n79 (4.5GHz) for 5G in Japan. Maybe it's the only network use n79. (It's hard to find supported phones in open market rather than docomo model, except iPhone) https://en.wikipedia.org/wiki/List_of_5G_NR_networks https://en.wikipedia.org/wiki/List_of_5G_NR_networks According to assignment map, it uses 4500-4600MHz. https://www.tele.soumu.go.jp/resource/search/myuse/use/10000m.pdf https://www.tele.soumu.go.jp/resource/search/myuse/use/10000...

tzs 5y ago

Europe is only using 3.4-3.8 GHz. The US is going up to 4.2 GHz.

RF_Savage 5y ago
Ah! That certainly explains some of it. I even checked and sure enough, the highest allocated block here is 3670 - 3800 MHz.

gdavisson 5y ago

AIUI the European usage of this band only goes up to 3.8GHz (see https://www.everythingrf.com/community/5g-frequency-bands-in-europe https://www.everythingrf.com/community/5g-frequency-bands-in... for example), but the FCC auctioned off band space up to 3.98GHz. Aircraft altimeters use the 4.2-4.4GHz band, so the new US allocation nearly halves the band gap. That is what the FAA is worried about.

gruez 5y ago
>halves the band gap. That is what the FAA is worried about. It's worth noting that a band gap of 200mhz is ridiculously wide, at least according to the top comment from the last thread https://news.ycombinator.com/item?id=29642777 https://news.ycombinator.com/item?id=29642777
g_p 5y ago
The UK makes available shared access licences in the 3.8 to 4.2 GHz band. These are power limited and location constrained, to manage interference with satellite earth stations. You can get a license in this band and run your own private 5G network in it. There doesn't appear to be any concern from the UK aviation regulator (the CAA). Perhaps they're able to achieve sufficient spatial separation from airports and their final approach paths, or perhaps they've found there aren't issues with the reduced transmit power available on these shared access licences? Nonetheless, it will be interesting to see if this 200 MHz guard really is insufficient in the US - at a certain point you need to consider if existing equipment needs to be replaced (like with the swapping of 800 and 700 MHz from digital TV to mobile, and the need for some people to put a band-stop filter onto their TV antenna feed to avoid interference from mobile networks).
- PostThisTooFast 5y ago
- sgent 5y ago
  Using this band is only an aviation problem if you're in the middle of an approach (approximately 20 miles from a runway, but not a big circle). Hence the location and power limitations.

darksaints 5y ago

3.5 is fine, that's CBRS. This is about C-Band, which is 3.7ghz to 4.2ghz in the US.

fomine3 5y ago

NTT Docomo operates n79 (4.5GHz) for 5G in Japan. Maybe it's the only network use n79. (It's hard to find supported phones in open market rather than docomo model, except iPhone) https://en.wikipedia.org/wiki/List_of_5G_NR_networks https://en.wikipedia.org/wiki/List_of_5G_NR_networks According to assignment map, it uses 4500-4600MHz. https://www.tele.soumu.go.jp/resource/search/myuse/use/10000m.pdf https://www.tele.soumu.go.jp/resource/search/myuse/use/10000...