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The white-space frequencies that are now available were used for the first time in rural Virginia recently to implement a broadband access network. The town of Claudville doesn’t have a suitable broadband connection to the Internet. If you want to browse the Web, send an e-mail, or conduct a search, you have to use a dial-up modem or an expensive satellite setup. The satellite access has a fast enough download, but the latency is so long it drives most users crazy. Now, Claudville has a new, faster wireless broadband connection thanks to white-space radio technology.

White spaces are those unused TV band frequencies that were freed up by the recent switchover to digital television in the U.S. These 6-MHz wide channels are ideal for transmitting fast data over long distances. The channels available are different in various parts of the country, but these frequencies can be used for broadband access and other wireless applications. The Federal Communications Commission (FCC) made these frequencies available on an unlicensed basis under its Part 15 rules last year.

The fixed master device or basestation connects to the Internet and communicates with Spectrum Bridge’s white-space database. It then connects with personal and portable devices or fixed device clients in homes and businesses. In all cases, each device negotiates for an available channel.

Along with Dell, Microsoft, and the TDF Foundation, Spectrum Bridge built the broadband network under an experimental license from the FCC. The radio modems used were originally designed for industrial telemetry and control and use frequency shift keying (FSK) in a 2-MHz bandwidth to achieve 1 to 2 Mbits/s, which is a common broadband speed range.

The radio modems use TV channel 10 (192 to 198 MHz), which was available in the Claudville area. One modem that’s used as a basestation is connected to the only high-speed fiber line in town and then talks to the local Wi-Fi hotspots that serve the town. Some users also get service directly from the basestation with radio modems connected to their PCs (see the figure).

Claudville, in the southwestern part of Virginia near the North Carolina border, has lots of mountains and trees. More common wireless technologies at microwave frequencies like 2.4 GHz have very limited range in such settings where a direct line of sight (LOS) path is needed for a reliable link. Lower frequencies have a greater range and are more forgiving under non-LOS conditions with trees and other obstacles. While antennas have to be longer at the lower frequencies, they still provide wireless access where the higher frequencies cannot.

The white-space frequencies available in a given area can be discovered at Spectrum Bridge’s Web site, www.ShowMyWhiteSpace.com. Most white-space radios will be frequency agile so they can seek out an acceptable and available channel automatically. This will ensure that they don’t interfere with the TV channels that may still use some of the frequencies and with wireless microphones that are protected under the new white-space rules. The radios will be able to communicate directly with Spectrum Bridge’s white-space database to find available channels on the fly.

The Claudville test has been very successful in bringing the worldwide online community to town. This experiment can serve as a model for delivering broadband connectivity to rural areas, small towns, and other locations that have a dearth of good high-speed Internet options. The FCC has not finalized the white-space rules but is expected to in the near future. While you’re waiting for that, now is the time to learn more about the white-space opportunity and create some great new innovative wireless products and services.