[acheron9383]

The satellite emulates a cell tower, just one that is hundreds of miles away and moving very fast. So some tricks with the timing will need to happen since LTE expects the tower to be close and not moving. How big a cell is depends on how powerful the phased array beam former is on the satellite. The achievable data rates aren't very high so this is more a network of last resort when you are out of range of a tower.

[acchow]

Transmitting with the power required to reach a satellite would surely drain my iPhone battery quickly, right?

[goodcanadian]

It really depends on the satellite's antenna. Another comment referred to a phased array (which seems likely). If so, they can can do very clever things that make it highly directional and able to pick up weak signals.