Researchers study best use of 'whitespace' spectrum

September 11, 2012 by Mark Riechers, University of Wisconsin-Madison

(—The demand for faster, more mobile Internet access for smartphones, tablets and laptops does more than strain the available space we have in our pockets and bags. There's a finite amount of wireless spectrum available to those gadgets as well.

However, in November 2008, the changed its regulation to allow unlicensed devices to use TV "whitespace" spectrum—unused frequencies primarily designated for —as long as they do not interfere with incumbent and other licensed users such as wireless microphones.

Researchers, including Electrical and Computer Engineering Professor Parmesh Ramanathan, are now looking for the best way to utilize whitespace to increase the data rates of wireless communication.

The 180 megahertz offers the best potential for improved wireless communication, since it provides nearly five times the bandwidth of conventional Wi-Fi, with increased range to boot. " propagate through walls and so on much better than other bands," says Ramanathan. "The higher the frequency, the less they propagate."

But tapping into unused spectrum requires two things: reliable sensing to determine which parts of the airwaves are not being used at any given time; and spectrum-agile radios inside of devices that can reliably determine and switch to the clearest parts of the band for wireless communication.

Ramanathan and Associate Professor Suman Banerjee are refining that . They pair signal sensing with precise and easy-to-tune software radios as they work toward networks that eventually could provide higher speeds to more users over wider than traditional wireless networks could ever provide. "Eventually, people will be replacing traditional Wi-Fi with these kinds of radios," says Ramanathan.

He believes technology that makes more innovative use of spectra is the future of wireless communications. "This is part of a change of how spectrum is going to work," says Ramanathan.

Better technology for sensing spectrum use will enable licensed spectrum owners to buy and sell them in short time scales.

For instance, consider the frequent dropped calls that occur when a football stadium is full of texting, tweeting fans. Ramanathan suggests that someday, cellular service providers could lease extra spectrum to improve communication during game day, invisibly adapting their network to better handle the influx of mobile device use. Moreover, police and security organizations could lease that same spectrum once the game is over, giving them more reliable communications among officers on the ground should an emergency occur.

Until the hardware catches up to the regulatory possibilities, these are all hypothetical scenarios. "Now that the FCC allows for these types of things, it becomes mostly a technological challenge to find the right solutions," says Ramanathan.

Explore further: US Congress approves wireless spectrum auction

Related Stories

FCC opens up unused TV signals for broadband

September 23, 2010

(AP) -- The Federal Communications Commission is opening up unused airwaves between television channels for wireless broadband networks that will be more powerful and can reach farther than today's Wi-Fi hotspots.

FCC seeking more spectrum for wireless broadband

February 24, 2010

(AP) -- Federal regulators are hoping to find more wireless spectrum for mobile broadband services by reallocating some airwaves now in the hands of television broadcasters and other users.

New Wi-Fi Technology Using White Spaces

August 20, 2009

( -- A wireless internet network that uses portions of the old analog TV spectrum may one day become a reality. The plans for a computer network that uses "white spaces," which are empty fragments of the old analog ...

North Carolina becomes home of White Spaces network

January 29, 2012

( -- America’s first commercial “TV White Spaces Network” was launched this week in Wilmington, New Hanover County, North Carolina. Wilmington, as the first U.S. city to shift from analog to digital ...

Recommended for you

Sculpting stable structures in pure liquids

February 21, 2019

Oscillating flow and light pulses can be used to create reconfigurable architecture in liquid crystals. Materials scientists can carefully engineer concerted microfluidic flows and localized optothermal fields to achieve ...

Researchers make coldest quantum gas of molecules

February 21, 2019

JILA researchers have made a long-lived, record-cold gas of molecules that follow the wave patterns of quantum mechanics instead of the strictly particle nature of ordinary classical physics. The creation of this gas boosts ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Sep 12, 2012
I like the idea of leasing. It would make spectrum use more efficient than the fixed, unevenly used, allocations we have today.

Expecting white space bands to help relieve the "bandwidth" need is unrealistic. The propagation characteristics of those frequencies work against it in typical densely populated areas like cities.

Regarding ham radio (I am a ham): "emergency use" is old and a little tired. Not that it's not valid, but I wish there were more reasons to make ham radio an important use of its band allocations.

FCC regulations regarding non-commercial use and permitted modulation techniques hamper the use of ham radio in experimenting with new radio-related technology. I'd argue that rather than non-commercial, that it simply be the operator must make no money.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.