120MHz is enough for 6 x 20MHz channels, a minimum for sensible LTE.
So they ALL need to pool the spectrum and have a single RAN
To avoid interference each mast needs 3 channels, each in a different direction so two neighbouring masts are on different frequencies.
In exposed rural areas the coverage may be too great so the mast beyond the neighbour mast needs the other 3 channels (increasingly so as you go 1800MHz and then 900MHz). In Urban areas on 2.1, or 2.5 you need all 6 channels to double the capacity..
The GSM 900MHz and Digital dividend 800MHz should be used as one band.
FDD is good. Far superior to TDD. Perhaps it doesn't need as much spectrum for uplink. But voip and skype video needs symmetric.