- In order for most cellular protocols to work successfully, it's necessary for the transmission power level (phone to tower and tower to phone) to be lowest possible.

- So that tx power has to be constantly modulated because the phone's distance is always changing as it moves, meaning the optimum power level is always changing.

- The tower is in control of this - it tells the phone how powerful to transmit, and this can be done for each device.

- So I would suppose a malicious party in control of the tower could simply tell the phone to transmit at max power, which will drain batteries quickly, especially if the connection is being actively used I guess. This may have interference considerations but if the tower is really a box on top of a car or truck it may not really matter.

- I don't know how the phone is prevented from connecting to closer non-malicious towers.