Ryan Guerra, a grad student at Rice University, has been trying to figure out how to extend the range of a WiFi signal to over a mile. Thanks to empty TV channels and some fancy engineering, Ryan has successfully extended the range of a WiFi signal belonging to a resident of Houston. This resident lives just on the outskirts of a free WiFi network, and since traditional WiFi signals use the 2.4GHz and 5GHz frequencies the signal will not easily pass through the trees surrounding the resident's home. Ryan has figured out how to take the traditional WiFi signal and convert it into an empty TV channel. He calls this project "Super WiFi". Ryan starts off by using a typical 2.4Ghz WiFi card running on a Linux system and has the card's output sent through a frequency translator. The translator then shifts the 2.4GHz signal down to 563MHz which is sent to a small TV antenna on the resident's home. The signal is transmitted and eventually patched into the free WiFi connection using a local transmission tower. The reason behind the use of the empty TV channel is it uses a 563MHz signal, and that signal can easily be sent though the trees and walls surrounding the neighborhood.
The transmitter Ryan has created transmits in a 60 degree directional beam allowing anyone in its path to receive the WiFi signal. Since the transmitter is directional it also allows for a smaller more discreet TV antenna to be used on the resident's home. While the results so far have been excellent, Ryan does foresee problems in the future with existing WiFi protocols and his Super WiFi project. Fear not though, Ryan and companies like Microsoft are researching new protocols for empty TV channel use.