It's not clear to me but it sounds like it wasn't an upgrade from 3G but from wifi, and wifi was only accessible at the stations?
The Stockholm subway has had 4G since 2015, but that was replacing the 2G/3G networks.
It would be interesting to know how it works. Are there a lot of smaller base stations? Is there a station on each train that bridges traffic using some other technology that works better underground?
The Stockholm subway has had 4G since 2015, but that was replacing the 2G/3G networks.
It would be interesting to know how it works. Are there a lot of smaller base stations? Is there a station on each train that bridges traffic using some other technology that works better underground?
https://computersweden-idg-se.translate.goog/2.2683/1.611884...