The AT&T has recently announced that they will use drones to help to improve their network quality. The carrier has already deployed drones as inspection tools to their cell towers. However, It comes up with the idea to use drones as an extension of their cell towers.
They also list the potential uses of drones to provide additional LTE coverage at significant events, or during a disaster where providing excellent communication tools.
The drone battery life is not exactly a stellar and can charge last few hours; Its means that this is obviously not a long-term solution, but rather it will be an interesting idea.