Researchers study best use of 'whitespace' spectrum

September 11, 2012 by Mark Riechers

(—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

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not rated yet Sep 11, 2012
I just hope these new systems don't interfere with existing amateur radio operations, while not sounding an important activity, they are the ones you go to for emergency communications and that could be compromised if the technology was not handled right.
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.

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