The Black and White of White Spaces
by Leslie Ellis // June 22 2009
Here’s something to watch for: An influx of unlicensed wireless gadgetry that works in the gaps around the channels vacated by the broadcasters 10 days ago (June 12).
People call this real estate “white spaces.” But, like any other effort involving multiple industry sectors, this is “white” like that t-shirt you’ve washed 275 times since 1986. And not always with other whites.
White spaces matter to two groups: Those wishing to occupy the vacancies, and those wanting nothing to squirt out sideways from the occupiers.
Let’s start with the latter, which includes broadcasters and cable providers. Their concern: The new white space guys could accidentally or otherwise interfere with over-the-air digital TV transmissions. (This matters to cable at the headend, where off-air signals are brought in and re-transmitted.)
What wants to occupy the white spaces? It’s on page 2 of the FCC’s Nov. 2008 ruling: “This action will make a significant amount of spectrum available for new and innovative products and services, including broadband data.”
So we’re talking another wireless broadband zone, but unlicensed.
“White space devices,” synonymous with “TV Band Devices,” are envisioned to work on locally vacant TV channels. Maybe channel 25 isn’t used for TV broadcasts in Blissville. That 6 MHz channel is white space, usable by unlicensed gear.
White space gadgets can be fixed or portable. If fixed, they need to stay between channels 2 and 51, and off channels 3, 4, and 37. They can blast at up to 4 watts.
Portable devices need to stay within unoccupied territory between channels 21-51, and off channel 37.
Both types need to include geo-location capabilities (“here I am”), and to boot up to an Internet database of protected areas (so as not to transmit there.)
Any such gadgetry also needs to sniff and avoid nearby TV broadcast and wireless microphone signals. Concert venues are particularly wary of white space occupants: Twenty thousand screaming fans takes on a whole new meaning if the screams are about squawking mics.
Right now, the grayest corner of the white spaces conversation involves the database. The FCC says that it “will be established and administered by a third party, or parties.”
It’s a fear-of-the-dark concern: Who runs the database? This matters to how quickly and definitively a headend tech can identify and stop a spectral interloper, elbowing in from a nearby white space.
In closing: May your summer concert festivities be free of white space junk.
This column originally appeared in the Platforms section of Multichannel News.