Unused Television Spectrum Could Deliver New Broadband Services

In September 2008, Wilmington, N.C., became the first major market to switch from analog to digital TV. Now the city is continuing the grand tradition, this time serving as a digital guinea pig for the nation's first "smart city."

Cameras, sensors and other devices have been installed throughout New Hanover County as part of a test that began in February and will last for several months. These devices will transmit real-time data for the city to analyze. Information travels through a new wireless network that utilizes unused broadcast television spectrum, called "white spaces" created by 2008's digital TV conversion. Because digital TV uses spectrum more efficiently, it's possible to use the leftover spectrum to provide broadband services.

For instance, Wilmington will use wireless traffic cameras at intersections for the transportation department to monitor traffic, travel time and fuel consumption, and to support local law enforcement. With water-level sensors, officials also can monitor and manage wetland areas in the coastal city without a boat trip.

"The possibilities of this technology, in my opinion, are endless," said Mayor Bill Saffo, estimating that using the white spaces could save the city 80 to 90 percent of the cost of creating a wired network. "So many possibilities that I feel will help local governments deliver services much more effectively and efficiently. You can literally cover your entire city in Wi-Fi without having to lay all these wires."

In a dozen cities across the country, broadcast TV channels 14 through 20 have already been allocated for public safety use, and the FCC reserved channel 37 for medical devices, said John Chapin, Massachusetts Institute of Technology researcher and a consultant for TV Band Services. Authorized by the FCC under an experimental license, Wilmington's network is a test bed for locally based TV Band Service and Spectrum Bridge, a Florida-based white space database provider.

But the idea of using TV white spaces to create a web of wireless extension cords for local governments has its hang-ups. For one, the FCC hasn't yet released official rules for how municipalities can use white spaces. And contrary to networks owned by cable and telecom companies, white spaces are unlicensed. That means, in theory, anybody can hop on one of the white space frequencies -- a critical concern for broadcasters because, without regulation, devices can potentially cause interference with regular broadcast channels.

"It's the unlicensed aspects that cause grave concerns," said David Donovan, president of the Association for Maximum Service Television (MSTV), "because if there is interference, there's no one to hold accountable. Who's responsible?"

Path Interference

A few months after the FCC published its first set of rules for white space use in November 2008, the floor was opened for concerns, Chapin said, which led to 17 petitions for reconsideration and three additional lawsuits.

The biggest problem, he said, was the issue of interference and how to accurately determine which frequencies are available in a given area and which ones aren't. Picture this: You're sitting at home trying to watch TV. Someone somewhere fires up a device on the same channel thinking it was an open white space frequency. The person may not know the device is causing interference, but all of a sudden you can't get a signal for that channel on your TV set. That is MSTV's concern.

"It's not that we have a problem with spectrum use per se," Donovan said. "We share with the police in major markets. We share with licensed LAN mobile operations. But sharing the band with millions of unlicensed entities will create significant hazardous interference to TV stations in the band."

To avoid the problem, MSTV supports the creation of a neutral database, which would be connected to devices built to FCC specs. This way, certified devices would only tune to available channels after getting the

green light from the database. But most existing database providers publish inaccurate information, Donovan said, and a database would have to be 100 percent accurate all the time, especially now because digital TV is more susceptible to interference.

"This has never been done before. And you're doing it in the same band that has millions of existing TV viewers who have just made a digital transition," he said. "You're experimenting with the American public."

Wilmington Mayor Bill Saffo said using a TV white space network costs 80 to 90 percent less than a traditional wired network.

'A Tool in a Toolkit'

Despite the ongoing debate, proponents and detractors share at least one position: TV white spaces don't replace existing wireless systems.

White spaces can't compete with the features and performance of a cellular system, especially with 3G and 4G technology, which offers high data rates, productivity while traveling at high speeds and a guaranteed connection.

Due to spectrum limitations, Chapin said, white spaces also can't compete with cable contracts or landline providers, which can provide 10 megabits or 100s megabits for businesses compared to one or two megabits from white spaces.

But white spaces can complement current wireless technologies because they are cheap to use and can penetrate better and extend farther than previous unlicensed wireless signals. For cities or counties, such range allows for fewer tower sites because the signal can shoot out to the middle of a park that may be hard to reach with fiber lines or dip into a valley on the city's edge.

"I'm not going to claim that white space is the only answer to solve wireless networking problems," said Rick Rotondo, chief marketing officer and co-founder of Spectrum Bridge. "It's another powerful tool in the toolkit."

Facing deadlines to deliver the National Broadband Plan to Congress, the FCC has delayed decisions on the matter. In coming months, the FCC will work on finalizing the white space rules, Chapin said, which means local governments might have radios available to use by the end of this year. Consumers, he predicts, would be able to buy them no earlier than December 2011.

Bridging the Digital Divide in Rural Areas

Typically rural communities have more TV white spaces available than the big metropolitan areas. That made Claudville, Va., a perfect place for a white space project. In a forested edge of southwestern Virginia, the community has about 900 people.

In October 2009, Claudville launched a project using TV white spaces to deliver rural broadband services. In this case, the white spaces were used as a middle mile, connecting a piece of fiber to new Wi-Fi hotspots, providing Internet access to the local high school, a fish hatchery, a café and a community center for the first time.

White spaces serve rural areas well because their signals travel miles and can go through trees, around mountains and survive in stormy weather. Unlike dial-up and satellite connections, Chapin said, white spaces provide a low-cost way to bring Internet access to the nation's unserved and underserved areas.

"This technology is an excellent fit for crossing the digital divide in extremely rural areas," he said.

Neither the Claudville project nor the Wilmington experiment has had any issues with interference so far, said William Seiz, test bed manager for TV Band Service. If any interference should happen, he added, the company is required to shut down the problem device immediately.

As Saffo hopes the Wilmington experiment influences other local governments to examine the use of white space, Claudville is already experiencing a domino effect. According to Rotondo, rural broadband is driving the adoption of other technology.

"I got e-mails from people who said, for the first time, kids going to school were getting laptops for Christmas," he said. "Just think how much better these kids' education and view of the world is going to be because of the laptops they're going to get."