Microsoft Research is creating a WiFi-style system operating in the UHF TV band that allows multiple clients to connect to a local access point from a long distance. This is a direct result of a late 2008 decision by the FCC to allow “unlicensed broadcasting devices access to white spaces in the television spectrum” (from Ars).
Why is this important? The biggie, distance. This “WhiteFi” system can operate as far as one kilometer away! Can you say “wifi for rural areas”?
The engineering challenges have been non-trivial. For example:
A second (and related problem) is the variation of the data channels over time. Imagine an access point merrily transmitting data to five white space client devices in the neighborhood. Everything progresses swimmingly until someone at the church next door switches on a wireless microphone. The access point must immediately drop its signal on that channel and find a way to notify all of its clients about a move to some new (and clear) channel.
And although rural areas were a key target for the technology, there’s usefulness in urban areas, too:
Once seen largely as a way to offer fixed wireless connections to rural homes, white space devices will soon be able to create mesh networks and WiFi-like connections—that early promise of “WiFi on steroids” might turn out to be surprisingly accurate, after all.
