Spectrum Sensing a Tested Technology, New America Foundation Says
Spectrum sensing, of the kind that is required to allow wireless devices to use TV white spaces to access the Internet without causing harmful interference, is a “proven and well-understood technology,” the New America Foundation said in a white paper released Monday. The group said the goal of the paper is to counter “the torrent of misinformation” in arguments made by broadcasters and others opposed to opening the spectrum for unlicensed use by portable devices. Sources said Monday the paper comes with the white spaces item -- once slated for an October vote -- still stalled at the FCC pending a second round of device tests.
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“The Pentagon has approved unlicensed sharing of military radar spectrum in the 5 GHz band by unlicensed devices using detect-and-avoid ’smart’ radio technologies,” the paper said. “In addition, in the FM radio bands, unlicensed transmitters have been in use for years -- products like the iTrip allow anyone to broadcast from their iPod to their car or home radio over vacant FM channels.”
The high-tech think tank said the devices pose no threat to wireless microphones, which are important to TV broadcasts, theatrical performances and others. “The vast majority of wireless microphones are themselves unlicensed devices and have been using vacant TV channels for many years (most of them illegally) yet without complaints of interference,” the group said.
The New America Foundation also argued that allowing just fixed use of the white spaces is a poor substitute for allowing personal portable devices to use the band. Broadcasters insist that, given current technology, only fixed devices should be allowed. “The benefits end users gain by having access to the Internet on a diversity of mobile devices is substantial; adding white space connectivity will generate entirely new services, applications, and innovations in communications technology and ’smart’ electronics,” the paper said. “Fixed wireless (e.g., towers, customer premises equipment) is no substitute for mobility.” The group also argued that the spectrum would have little value if auctioned rather than opened to unlicensed use. “TV white space is ’swiss cheese’ spectrum - - each of the nation’s 210 TV markets has a different set of channels in use, thus there are no nation-wide clear channels,” the paper said.
Meanwhile, in recent days other advocates of opening the whites spaces to unlicensed use have held various meetings at the FCC. Google met with officials from the FCC lab to present preliminary data on tests that it said show that “digital televisions and wireless microphones can be amply protected from harmful interference by unlicensed, personal/portable devices, using reasonable power levels and sensing thresholds.”
Motorola officials met with Office of Engineering and Technology staff to discuss a white spaces device the company submitted for tests last month. Former OET Chief Ed Thomas met with OET staff to discuss devices Microsoft and Philips Electronics North America plan to submit for testing. “In addition, the parties briefly discussed mechanisms for protecting wireless microphone operations identified in the white spaces proceeding, and whether these protection schemes could be tested by OET using the Microsoft and Philips devices,” Thomas said in a filing at the commission. Silicon Valley-based technology start-up Adaptrum has also submitted a device for testing.
“Down at the lab of our local communications commission there have been all sorts of visitors, like Magi at Xmas time, bearing gifts or promises of gifts,” former FCC official Michael Marcus said on his blog. “FCC staff reports that the ‘8th Floor’ has now said that all submitted devices will be tested in parallel and publicly with observers from the interested public… A problem appears to be how to find homes to test these in where an unlimited number of observers can wander in and out.”