LTE/Cell

Long Term Evolution is a both a catch all phrase to some and to others a very particular set of technologies. Many marketing people speak of 3G, 4G and 5G networks. The Mobile Network is a heterogeneous (hetnet) integration of technologies.

Carrier	4G LTE Bands	Frequencies
AT&T	2, 4, 5, 17	1900, 1700 abcde, 700 bc
Verizon Wireless	2, 4, 13	1900, 1700 f, 700 c
T-Mobile	2, 4, 12	1900, 1700 def, 700 a
Sprint	25, 26, 41	1900 g, 850, 2500
Europe	3, 7, 20	1800, 2600, 800
China, India	40, 41	2300, 2500

Cellular Frequency Modulation types

TDMA: In the simplest case we can imagine, each call gets a time-share of the complete frequency band. It's a bit like callers waiting in line for a payphone. Each one waits until the phone is vacated by the previous caller, makes their call, and hands on to the next person.
FDMA: With the total frequency band split up into smaller bands, we can imagine sending multiple calls in parallel. This is a bit like having four payphones in a line; four callers can use them simultaneously. We could also run TDMA at the same time, dividing each of the smaller bands into time slots.
CDMA: We break each call into pieces, code them, and send them down any available channel. This makes much better use of our available frequency spectrum, because none of the channels is idle at any time. However, channels have to be kept separate to stop them from interfering, which means our total frequency band is used inefficiently.
OFDMA: We set up our system so that we can, effectively, superimpose channels on top of one another, packing in even more capacity to give even greater data speeds.