I haven't got exact figures, but the radio side of an LTE base station alone takes around 400w (that's the customer-side, ignoring backhaul). LTE cells aren't at FL 600, the Titan Aerospace UAV only generates 100w (and needs all of that to stay aloft) and has a payload of 32kg.
I have an LTE base station on my desk at work that draws...oh, around 25W total excluding only the RF power AMP, and weighs, oh, something less than 1KG. The comms aren't the tough part of this particular concept.