Thank you for that. This is quite interesting, I thought there were quite strict guidelines about who was allowed to broadcast on 2/3G frequencies? Or is this bandwidth not as controlled as others?
As "extrapickles" pointed out in another comment thread, the spectrum requirement for this is an even bigger hurdle than getting all of the expensive equipment together to pull it off. The tech requires an amount of frequency separation that spreads outside the bounds of the ISM spectrums, so you'd need licensing or would need to be running in a third-world country with no regulations (which is actually a viable use for the tech).
For the unaware, ISM = Industrial, Scientific and Medical. These are the shared unlicensed frequencies that the general public may use. Wifi falls inside of this range.
...or in a place where no one who cares can receive your unauthorised transmissions. If you're not interfering with anyone who has the "right of way" on those frequencies, then you might as well not exist to them.
For the unaware, ISM = Industrial, Scientific and Medical. These are the shared unlicensed frequencies that the general public may use. Wifi falls inside of this range.