With next year’s transition to digital television sparking fierce debate over how to use the newly vacant TV channels, Google has offered a plan that it says could vastly improve U.S. broadband service.
For several years, policy makers, technology companies, and broadcasters have been debating the best use for this newly available wireless real estate. This “white space” between operating TV channels is of particular interest to broadband companies, because wireless signals sent at these frequencies will have the ability to penetrate walls and other obstructions more easily than do cell-phone or Wi-Fi signals.
Google submitted its new proposal to federal regulators late last week, outlining a plan to utilize the unused channels for what the company calls Wi-Fi 2.0: a loosely regulated set of broadband services with the potential for gigabit data speeds. The company stopped short of saying that it would seek to operate a broadband network itself, but it clearly sees business potential, telling federal regulators that it would provide other companies with “the technical support necessary” to turn the TV frequencies into broadband data conduits, free of charge.
“The unique qualities of the TV white space–unused spectrum, large amounts of bandwidth, and excellent propagation characteristics–offer a once-in-a-lifetime opportunity to provide ubiquitous wireless broadband access,” wrote Google attorney Richard Whitt in the company’s proposal to the Federal Communications Commission (FCC).
Indeed, the soon-to-be-freed TV airwaves represent some of the last, and potentially most valuable, swathes of U.S. wireless spectrum still suitable for providing broadband services. Naturally, the debate over how they will be used–and who should use them–has been fierce.
Technology companies such as Google, Microsoft, and Motorola say that these frequencies are particularly well suited for providing rural areas with high-speed Internet service, as well as for short- or medium-range networking applications that might provide data transfer rates of gigabits per second, as opposed to the roughly 54 megabits per second of today’s 802.11g-based Wi-Fi networks.
Regulators have already approved the use of some fixed devices, but the tech companies want approval for mobile devices such as handhelds and laptops as well, and they’re seeking rules that would let companies offer services using the spectrum without having to get new licenses. Google has said that the TV white space would be ideal for mobile data devices using its open-source Android platform, for example.
However, TV broadcasters are worried that unlicensed devices sending data on unused TV channels–say, a vacant channel 29–might interfere with the program signals being broadcast on channel 28 or 30. Similarly, they’re concerned that mobile devices able to operate across a range of frequencies might accidently choose a channel being used locally for TV service and scramble nearby TV viewers’ signals.
Technology companies say that they can control for this problem. They’ve advocated a technique called spectrum sensing, in which the portable devices, transmitters, and receivers alike would scan channels before using them to make sure that they are indeed vacant. Detecting the presence of TV signals or other authorized users would keep a “white-space device” from using that channel.
However, FCC tests of spectrum-sensing prototype devices have been spotty at best. A first round of testing last year had disappointing results. Another round of FCC testing, with a new batch of prototype devices from four different companies, is now under way.
Google’s new proposal aims to deflect concerns about those tests. To this end, the company has adopted three alternative ideas that were previously advocated by Motorola and others for protecting against interference.
The first aspect of this protection would create a publicly accessible database listing all licensed TV stations and their geographic location. Any device attempting to use the TV spectrum would first have to establish its own geographic location, by using GPS readings or another means, and then check this database to avoid conflict with a licensed TV station in that area.
In its proposal, Google said that it would be willing to maintain “open geo-databases” to support this function, as well as provide intellectual property, reference designs, and technical support to other companies.
A second tool would be aimed at protecting the wireless microphones commonly used by news crews, conference speakers, and others, all of which today send signals over parts of the vacant TV spectrum.
Following earlier suggestions, Google is proposing the creation of an inexpensive “beacon” device, which would let microphone users broadcast the fact that a particular channel, in a particular area, is in use. White-space devices would be required to monitor and respect these active beacon signals, and to avoid broadcasting on the same channel.
Lastly, channels 36 through 38 would be set aside as a “safe harbor,” to be used only by wireless microphones.
“We think Google did a good job of recognizing the high level of protection provided through this approach,” says Steve Sharkey, senior director of regulatory and spectrum policy for Motorola, which submitted a proposal with similar features last year. “There is no question that this will be able to fully protect the [TV broadcast] incumbents and the devices that are supposed to be protected.”
Others are less convinced.
“There is nothing in [Google’s proposal] other than a laundry list of so-called protections that quite candidly have been debated for the last several years,” says David Donovan, president of Maximum Service Television, a lobbying group that works closely with broadcasters. “There is no new technical information. There is no evidence put forth by Google, nor is there evidence in the record that any of this actually works.”
At this date, with analysis of spectrum-sensing prototype devices still under way, and the alternative proposals still untested, there is no guarantee that the big technology companies, such as Google and Motorola, will have their way.
Indeed, this week the Cellular Telephone Industry Association (CTIA) offered an alternative proposal, under which the white-space channels would be used instead by licensed operators–much as cell-phone frequencies are used today–to offer broadband services. Broadcasters have said that they are more willing to accept this model, since any TV interference could be tracked immediately to a licensee, instead of to an unknown, unlicensed device.
However, the allure of spectrum-sensing devices hasn’t diminished, despite testing hiccups and Google’s new compromise proposal.
Google’s proposal itself envisions a transition system, in which new devices’ spectrum-sensing features could be continually checked against the information in the TV database, and any mismatches could be used to improve the technology.
Once spectrum sensing does mature, whole new generations of devices will be able to comb the airwaves looking for unused space, even beyond the TV channels now under discussion, the company says. Google has outlined a way of allocating this unused spectrum on the basis of “dynamic auctions,” in which network service providers would bid for and gain access to the unused spectrum on a real-time basis, using an online auction tool.
Any such system would face considerable regulatory and technical hurdles, and it would almost certainly inspire political opposition from other, more traditional wireless users. But the idea of broadband devices that can find and utilize virtually any vacant spectrum has inspired technologists who see a more efficient use of the airwaves as a way to eliminate bandwidth constraints.
“We soon could see a low-cost and open infrastructure, supporting a near-unlimited bandwidth Internet service, improving every year as computer and radio technologies continue to evolve,” wrote Google’s Whitt. “This would be akin to a faster, longer range, higher data rate Wi-Fi service–‘Wi-Fi 2.0’ if you will.”
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