Unlicensed cognitive sharing of TV spectrum: the controversy at the Federal Communications Commission

As societies become increasingly mobile and more dependent on information technologies, their radio spectrum also needs change. The basic spectrum management structure in all countries was developed over a long period, and much of the basic framework has remained stable for decades. The FCC is interested in making more spectrum available to unlicensed devices because of the explosive growth of IEEE 802.11/Wi-Fi unlicensed wireless LAN technology, and because the FCC recognizes that there is a great deal of "white space" that could be exploited by unlicensed devices. The FCC proposal selected the TV bands as an initial home for cognitive radio based on several factors. First, the frequencies used for TV can give greater range in rural areas than the microwave frequencies used for Wi-Fi, and can also give better building penetration than Wi-Fi in all areas. Second, TV broadcast systems usually use high antennas, and the intended receivers need greater than 10 dB signal-to-noise ratio (SNR) to function. A variety of controversial issues have emerged from public comments. One concern is that the confusion resulting from the proposal might discourage purchase of new digital televisions and hence delay the transition from analog to digital televisions. This would also delay the transfer of some current TV spectrum to new mobile uses, including public safety.