June 8, 2011 – A sleeper in the jostling over new spectrum allocations for wireless is the emergence of an FCC-approved approach to building new business through use of unlicensed airwaves in the so-called white space of unused broadcast channels between 54 and 698 MHz.
By the end of this year entities who want to operate in what some view as a next-generation Wi-Fi arena will be able to tap into a new marketplace operated by a group of FCC-certified administrators and affiliated device manufacturers and network technology suppliers. The FCC at the end of last year issued a final rulemaking defining use of this valuable spectrum under Part 15 unlicensed spectrum rules, but the commission has not yet approved the various database plans of the nine designated administrative entities who are key to bringing this new market into place.
Nonetheless, much has been accomplished by various parties in real-world trial implementations of white space wireless applications in various communities around the country, leading many players to believe the usage could play a viable role in expanding the reach and variety of wireless services across the country. “We think this is a next-generation Wi-Fi,” says Darrin Mylet, business operations executive for Adaptrum, a wireless technology startup. “Only it goes farther and has better technological characteristics.”
Those characteristics are highly dependent on the “cognitive radio” technology Adaptrum and other entities are creating to allow devices to jump seamlessly from one spectrum zone to another in the unlicensed environment. Where TV white spaces are concerned, there’s no telling what channels may be open for use from one geographic location to the next, owing to the vagaries of local broadcast signal allocations, service area contours and the presence of other licensed operations on those bands, including public safety and microphone applications.
A random sampling of white space availabilities as shown by zip codes in a Web site app run by Spectrum Bridge, one of the tentatively endorsed white space administrators, shows a sparsely populated area of Wyoming can have 35 channels or 210 MHz of availability while an urban area like Kansas City, Mo. might have just three or four. Devices can work within or across these different configurations when they’re equipped with cognitive radio technology, which can sense the presence of other carriers, move to different channels as needed and use different modulation schemes and power levels.
In the evolving white space business model, these devices will be able to distinguish which channels are available by communicating with one of the data bases run by the administrators, depending on which data base provider the device manufacturer has contracted with. As shown by Adaptrum in a demonstration with Microsoft at the NAB Show in April, the white space-configured device, polling a database every 40 seconds to confirm channel availabilities, is able to maintain a strong signal in the face of changing spectrum conditions.
The promise of such benefits and new business opportunities swayed the FCC to finalize the white space ruling late last year following eight years of heavy lobbying against the idea on the part of vested wireless interests and the National Association of Broadcasters. Even now there is a lot of uncertainty as to how much white space will end up being available under Part 15 rules once the FCC decides whether to make unused licensed broadcast space available for mobile licensing under a proposed new auction (see March issue, p. 1).
But the only thing apparently standing in the way of getting services off the ground is the certification of the various database plans. Under rules promulgated last year:
- Fixed devices may operate on any channel between 2 and 51, except for channels 3,4 and 37 and at up to 4 Watts EIRP (Equivalent Isotropically Radiated Power)
- Personal portable devices may transmit up to 100 mW (or 40 mW for adjacent channel operation) and may operate on any channel between 21 and 51, except channel 37.
- Signal sensing capability is a built-in protection the FCC requires to ensure against interference with existing microphone systems and television stations,
- There is a dynamic registration system, whereby devices, excepting those devices that transmit a maximum of 50 mW EIRP, must register their locations with an online database.
The potential of white space services has drawn the attention of service providers. Rob Riordan, executive vice president and director of corporate development of Nsight, a Green Bay Wisconsin-based provider of wireless and wireline broadband communications, says he sees opportunities for white spaces in the last mile. Riordan, a long-time advocate and innovator in the deployment of femtocells, envisions fiber- or copper-fed low-power picocells that reside in the outside plant will substantially lower the costs of broadband deployment.
“It gives you (the landline operator) the opportunity to have spectrum.” Riordan says. “It is in the early stages, but within a couple of years it will be fully developed.”
The companies tentatively designated by the FCC as database administrators, pending certification of their databases, include Google, CommScope subsidiary Comsearch, Neustar, Telcordia Technologies and less well-known players Airity, Frequency Finder, Inc., KB Enterprises, Key Bridge Global and Spectrum Bridge. Each will be licensed for a five-year term commencing immediately.
Just what type of business models will emerge in this new marketplace remains to be seen. In their filings with the FCC, these entities proposed a variety of approaches ranging from one-time fees to device manufacturers to value-add fees for those wishing database access capabilities beyond a basic level.
Neustar, for example, suggested that its model will include fixed recurring fees and one-time fees to ISPs. At the other extreme, Google said it will not be charging any fees at first, though that could change.
Citing services such as Gmail, YouTube and Google Documents that it sustains without fees, the company said, “While Google has no current plans to rely on user fees, we will work with the Commission to develop an acceptable business model should it become necessary to do so.” Google suggested a clearinghouse function might be necessary to mediate between different databases and advocated for open interfaces to ensure data exchange.
In its demonstration at NAB, Adaptrum showed cognitive radio in action on white space spectrum over a .8-mile fixed link between a hotel and an antenna attached to an Xbox terminal at Microsoft’s booth. Using time division duplex (TDD) and orthogonal frequency division multiple access (OFDMA) technologies in the presence of simulated channel changes, the firm showed it was able to achieve 94 percent efficiency on a 6 MHz channel allocation with an aggregate data rate of 8.8 megabits per second.downstream and 2.3 mbps upstream. The firms detected no streaming interruptions in the video on the Xbox.
Mylet of Adaptrum suggests that rollout of white space technology will happen in one-third of the time that it took Wi-Fi to deploy at lower cost. He anticipates certifiable products will launch late this year with higher volume/lower cost products releasing in 2012. Eventually, he says, white space technology will be integrated into commonly available consumer devices such as smart phones.
Spectrum Bridge has designed and deployed four FCC-approved white space trial networks with outstanding results in all cases, according to CTO Peter Stanforth. “Due to its availability and range, TV white spaces have proved to be a very cost-effective way to distribute high-speed Internet in this heavily forested and hilly rural community,” Stanforth says, in reference to an 18-month-old trial delivering fixed Internet service to residents and schools in Claudville, Va.
“The non-line of sight conditions, coupled with long distances between radios, would have posed significant challenges to existing unlicensed alternatives,” he adds. “TV white spaces could prove to be invaluable to those striving to bring broadband access to under-served and unserved rural communities.”
Among the other white space trials is a “smart-city” project in Wilmington, N.C. and the surrounding county entailing applications such as real-time traffic monitoring, public safety monitoring, wetland usage management, medical telemetry and broadband access for schools. In Logan, Ohio the Hocking Valley Community Hospital has taken medical applications further with delivery of a wide range of telemedicine services over a new white space network.
The fourth trial, in the Sierra Nevada Mountains, entails extension of a wireless smart grid power usage management program to regions that were heretofore unreachable, attesting to the propagation power of RF signals in these low spectrum regions. “Plumas, Lassen and Sierra Counties present some very technical challenges with respect to wireless coverage, says Lori Rice, COO at Plumas-Sierra Rural Electric Cooperative & Telecommunications. “The ability to use white space has proven to be an effective option for dealing with difficult terrain and offers another option for wireless connectivity.”