In late September, the FCC announced it would be freeing up spectrum from television broadcasters and opening it to public use to create "super Wi-Fi."

Tech industry groups and public interests groups hailed the new "white-space spectrum" as a way to expand upon the success of the open frequencies that allow anyone to set up a Wi-Fi radio hot spot in their house or coffee shop, without needing to buy spectrum or get a license.

But what will this super-Wi-Fi look like in practice? Will it replace the 3G service we pay for for our smartphones? How fast will it be? Will we need new equipment or can our current laptops and cellphones just be upgraded?

Wired.com asked the experts at smart Wi-Fi equipment maker Ruckus Wireless in Sunnyvale, California, to find out.

The short answer is that the new spectrum could be really great news for rural areas, won't be nearly as useful in dense urban areas, though the characteristics of the new spectrum could make for some very smart uses.

That's according to Bill Kish, the CTO and co-founder of Ruckus Wireless, which is known for its innovative Wi-Fi antennas.

"There is an interesting amount of hype around the new spectrum," Kish said. "But people don't know the best way to use this new spectrum at this point and it's going to be sometime before we figure it out."

Currently, Wi-Fi uses unlicensed spectrum in the 2.4-GHz and 5-GHz ranges (Wireless-N uses the latter in combination with the former). These ranges are available across the country and largely standardized across the world.

The new whitespaces are much lower — in the 700-MHz spectrum — and like the TV signals that use adjacent channels, the waves are very good at penetrating walls and obstacles. Wi-Fi is more easily absorbed by obstacles, including humans.

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As the whitespace name suggests, the new spectrum lives in the nooks between the bands reserved for television channels blasting digital TV signals at hundreds of Kilowatts of power. Since television channels vary from city to city, there has to be a master database to make clear what portions of the band are open in which metropolis.

"Unfortunately, the reality is that the new spectrum is inversely proportional to where you want it," Kish said. "Where are all the iPhones? They are in cities, where the whitespaces aren't available."

For rural areas, without many television stations, the availability of new spectrum could make it possible to create powerful Wi-Fi services, which Kish calls "one slam dunk."

The other challenge with the new spectrum is its width. The available channels are significantly smaller than those used in Wi-Fi, which uses 20 MHz of spectrum for each B/G channel and up to 40 MHz for each channel in Wireless N. The fatter "pipes" make it possible to pump a lot of data through each channel – you can get up to 300 Mbps of data going through a Wireless N channel.

By contrast, the new white space channels are only 6 MHz wide, which would top out at less than 40 Mbps per channel – not a lot when you have multiple people connecting, according to Kish.

Which all sounds like super-broadband isn't that super at all.

But Kish says there are some real possibilities using it as an extension of hot spots, given that the signals go further than current Wi-Fi. Perhaps more importantly, one of the properties of the lower frequency is that it takes significantly less battery power to receive the signals. So when a digital device is in sleep-mode or not using much data or wants Twitter, chat or e-mail notification updates, the device can switch over to the overlay, Kish suggested.

"You can match the radio tech to the actual demands of the moment," Kish said, comparing that to a driver or bike rider switching gears.

Other uses for the low power, low-data rate but longer distance spectrum?

Home automation could take off, so that it wouldn't be too energy-intensive to make more systems – your sprinkler system or your fireplace Wi-Fi connected.

So when will we see devices that use the new spectrum?

Kish doesn't expect prototypes until 2012, since the net's standards-setting body IEEE is just starting to work on the spec. Meanwhile chip makers still have much work to do catching up on the capabilities of Wireless N, which in theory allows routers to stream across 4 channels to the same user simultaneously (think Hi-Def movie streaming). But the chip makers aren't there yet.

The other impediment is that so far this band is limited to the United States, which reduces hardware makers' incentive to build out devices for this spectrum. If other parts of the world follow suit, expect the race to get more competitive.

Update: The post has been updated to note that Wireless N uses both 2.4-GHz and 5-Ghz spectrum, not just the latter. The post also incorrectly stated the width of some channels in Hz, rather than MHz.

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