Inverse square law does not apply to this as usual (although it does if you fix the beam configuration) -- but you can take your tin foil hats off (I guess this would indeed make a good scenario for tin foil hats) since you need real time channel estimation and feedback.
Are you sure the inverse square law does not apply? I think you're just getting a bigger coefficient. You might be constructively interfering signals, but the signals are still diminishing over distance. It's not magic, or they wouldn't need to place the antennas all over the place.
