Taking Waves: FCC Green Lights Unlicensed Use of Wireless "White Space" Frequencies [Slide Show]
But now comes the hard part: making phones, PCs and other mobile gadgets that can take advantage of the broadcast spectrum's strong signals
![Taking Waves: FCC Green Lights Unlicensed Use of Wireless "White Space" Frequencies [Slide Show]](/sciam/cache/file/5922E6F2-EA76-4E45-AFD528A59C3970C9.jpg?w=590&h=393)
Taking Waves: FCC Green Lights Unlicensed Use of Wireless "White Space" Frequencies [Slide Show]
- PESQ-Y The researchers analyze the quality of the recording using a set of standards known as perceptual evaluation of speech quality (PESQ), also used by phone-makers, network equipment vendors and telecom operators to assess voice quality. Their results show that vacating only a few 100 kilohertz of a six-meghertz TV channel is sufficient to avoid audible interference to wireless mics. The remaining spectrum can be simultaneously utilized for high-speed data communication. COURTESY OF MICROSOFT
- QUIET PLEASE The FCC prohibits a white space device from sharing channels with wireless mics, even if that mic does not use the entire channel. To ensure there is no interference, Microsoft Research's Ranveer Chandra and his team are testing white space transmissions in an anechoic chamber, whose walls absorb sound to prevent echos and reverberations. In the chamber they record sounds via a wireless mic, at the same time exposing it to white space transmissions (they also make recordings without any white space transmissions). COURTESY OF MICROSOFT
- ON THE MOVE Microsoft's WhiteFi network wants to give wireless users Internet access while they ride the 220 shuttle buses and cars used to transport employees and visitors around the company's city-size campus. The researchers installed a wi-fi access point in one such shuttle. COURTESY OF MICROSOFT
- WHITEFI ANTENNA Microsoft favors a database lookup function in lieu of a spectral-sensing capability that could probe white spaces to see if they are being used by an FCC-licensed user at any given time. As such, Microsoft Research set up a wi-fi–like network on its Redmond, Wash., campus to transmit high-speed data signals over white spaces using a technology the company refers to as "WhiteFi." COURTESY OF MICROSOFT
