In a paper (PDF) presented at SIGCOMM 2009 this week, a research team outlined the network framework for utilizing whitespace. Matt Welsh, one of the authors of the paper, describes the back ground and their proposal in his post today.
Background: “By way of background, in 2008 the FCC issued a ruling allowing unlicensed devices to operate in the UHF white spaces, under certain restrictions. Opening up this spectrum for unlicensed wireless networks is a huge opportunity — for example, UHF devices would achieve much longer range than networks operating in the 2.4 GHz and 5 GHz ISM bands. There’s been a lot of recent research on establishing individual links in the UHF white spaces, but to our knowledge nobody has proposed a network design allowing multiple clients to communicate via an access point. That’s where WhiteFi comes in.”
WhiteFI: “In WhiteFi, the key idea is to use a software-defined radio to scan the physical RF channel and use an efficient algorithm for performing AP discovery without performing a full decode on the signal. The SIFT technique (described in the paper) is a simple time-series analysis of the raw samples from the SDR that quickly determines if there is an AP operating at the chosen center frequency, as well as its probable channel width. The SDR is also used to detect incumbents. WhiteFi also includes algorithms for assigning channels to APs based on spectrum availability, as well as for handling disconnections due to interference or station mobility.”
One of the biggest advantages of WhiteFi is the ability to conform to FCC regulations by quickly dropping and reacquiring channels.
From GigaOm: “White-Fi won’t yield as much bandwidth as WiMAX or LTE networks, and its speed will depend on how much spectrum is available in each particular area. (It could be comparable to Wi-Fi but with a much longer range.) But unlike WiMAX or LTE, which will be deployed in urban areas, the spectrum isn’t owned by major carriers, so it lets new providers get in the game, and because no one has to buy the spectrum, the network’s cost would be lower as well. Of course, whoever is providing the service will still have to pay for the backhaul to connect the White-Fi network back to the Internet.”
Dailywireless highlights the benefits: “The spectrum between 512 megahertz and 698 megahertz was originally allotted to analog TV channels from 21 to 51. It offers a longer range than conventional Wi-Fi, which operates at 2.4 gigahertz. “Imagine the potential if you could connect to your home [Internet] router from up to a mile,” says Ranveer Chandra, a member of the Networking Research Group at Microsoft Research behind the project.”
Good comment from an Engadget post: “What I’m getting at is that this will enable ubiquitous computing because of mobility…mobility is the key. This is enable us to possibly do away with cell technology all together, with VoIP running on a MAN (metropolitan area network). This will also increase the accessibility of the Internet to all. It will make the Internet just like TV and the cost would be incredibly low. IPv6 will enable us to enhance security (among many others) as DHCP goes away and it can be regulated like telephone numbers.”