Software-defined radio moves toward milestone
White-space devices are closer to becoming a commercial reality as the final rules for their operation were cemented in the Federal Registry today. In addition, the Federal Communication Commission’s certification procedure and database provider choices are expected to become public this month.
Carlson Wireless CEO James Carlson said that if the federal timetables hold steady, his company will be ready with the first certified software-defined radio (SDR) for the white-space market by late January or early February.
White spaces are vacant frequencies located between broadcast TV channels in the VHF/UHF range. TV spectrum resides between 54 MHz and 698 MHz, but only a small portion of it is in use. The spectrum has excellent propagation characteristics that allow signals to reach farther and penetrate walls and other structures. Access to this spectrum could create super Wi-Fi hot spots with extended range, fewer dead spots, and improved data speeds for individual users as a result of reduced congestion on existing networks. White spaces also may be useful in bridging communications gaps for first responders in rural areas.
Carlson radios have been powering Spectrum Bridge’s white-space network trials across the U.S. Spectrum Bridge is aiming to be a designated database administrator; such entities would perform the essential function of keeping records of vacant and non-vacant channels so that white-space devices can smartly move from vacated channel to vacated channel.
Spectrum Bridge has built a network in Claudville, Va., a small rural community lacking broadband connectivity, to show how white spaces can bridge the “digital divide.”
In February 2009, the city of Wilmington, Del., and the county of New Hanover in North Carolina, launched a white-space network using an experimental license to create what Spectrum Bridge calls the nation's first smart-city network powered by the vendor's white-space database.
And in September, Google and Spectrum Bridge, together with the Hocking Valley Community Hospital, announced the deployment of the first white-space broadband trial network for healthcare providers in Logan, Ohio.
Last month Carlson unveiled the RuralConnect IP radio during the California Wireless Internet Service Providers Association (WISPA) meeting. Rural providers are keen on solutions that help them bridge the digital divide, but Carlson also sees more markets, including municipal applications for functions such as traffic control and the public-safety community.
“We’re just starting to get into the public-safety community,” said Carlson, whose company already caters to public safety on the microwave side. “There is a variety of different areas in rural markets where they can’t get communications between two points because of the terrain.”
Carlson Wireless may have a significant head start in the market given the fact that the FCC declined to relax its initial rules pertaining to out-of-band emissions. Wi-Fi manufacturers were hoping to easily convert Wi-Fi equipment and chips to accommodate white spaces, but the FCC kept the rules strict to placate broadcasters that long have been concerned about interference from white-space devices.
“Manufacturers have to use filtering equipment or use a software-defined radio and change the output mask,” Carlson explained. “We believe we’ll have a six months or greater lead in the marketplace.”
Carlson Wireless also has focused on making its radios low power so that they increasingly can be used in more heavily populated areas where spectrum traffic is higher. It also has set up the radios to run on solar power, which will be relevant for extremely rural markets. Its go-to market partner will continue to be Spectrum Bridge.
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