That's really cool, Thankful -- the article links lead to the following:
>> In this same Trustworthy Wireless area, Anmol Sheth discussed his research project called GeoFencing. Instead of using password protected wireless networks, GeoFencing confines the wireless radio transmissions at the physical layer to a user specified region - like your apartment or coffee shop. Using overlapping transmissions from distributed beamforming antennas the wireless signal only works at the intersection of these beams. Geo-fencing can adapt to regions of varying shapes and sizes.
[emphasis added] ref: Trustworthy wireless research