They use a custom low power basestation. Cf :
"The prototype basestation uses an unlicensed frequency, limited to low-power transmissions. ... Real cell towers have a hundred times as much power, and would increase the range to perhaps a kilometer,"
"The prototype basestation uses an unlicensed frequency, limited to low-power transmissions. ... Real cell towers have a hundred times as much power, and would increase the range to perhaps a kilometer,"
To be fair, we used more sites closer together instead of a few larger ones, but the point stands. Cell sites biggest advantage is elevation and line of site, not massive transmit power.
Elevation and line of sight are important but power is too!
Ctrl-f "watts" on this page to see what I'm talking about:
https://www.ericsson.com/en/networks/offerings/connecting-th...
However because the base has multiple (hundreds) of low-power transmitters, it must cater for a very large instantaneous peak power when they momentarily add up.
And more importantly, excess Transmit power reduces the re-use ability of that frequency in nearby cells.
The what? The only thing I can find about reciprocity is that antennas have the same characteristics in either direction. That doesn't mean your noise levels are the same, and you very often have different bandwidth requirements in each direction.
Late response, but that assumes that the mobile RX is as good as the tower's RX, and I can assure you that's not the case.
The gear up on a tower has a way better low noise amplifier than a mobile phone, so it's able to "hear" the phone at a greater distance than you'd expect. That's why it's a-okay to have a base transmitter with a quite a bit more power than a mobile TX.
Any excess power prevents re-use of the frequency in adjacent cells.