White space, in a communications context, refers to underutilized portions of the radio frequency (RF) spectrum. Large portions of the spectrum are currently unused, in particular the frequencies allocated for analog television and those used as buffers to prevent interference between channels.
In the United States, frequency allocations in the RF spectrum are made by the Federal Communications Commission (FCC). In November 2008, the FCC voted unanimously to make unlicensed portions of the spectrum available for use. At that time, at least three-quarters of the spectrum allocated for analog television was unused. These frequencies became available once the changeover to digital television was complete, by a unanimous decision of the FCC (Federal Communications Commission) in September 2010.
White space allocation has stimulated development of wireless technologies and services. According to Google co-founder Larry Page, white space operation will be like "Wi-Fi on steroids," because the signals in that portion of the spectrum have much longer ranges than those currently used for Wi-Fi. The increase in range means that fewer base stations will be required to give better coverage; that increased efficiency, in turn, should yield better service at lower costs. Signals in the white space range can also penetrate through solid objects better, which should yield more reliable service.
The IEEE (Institute of Electrical and Electronics Engineers) 802.11af and 802.22 working groups have developed White Space Wi-Fi and WRAN (wireless regional area network) (respectively) to operate in that range. WRAN is designed to enable high-speed pervasive wireless broadband in underserved areas. White Space Wi-Fi, also known as White-Fi, is expected to make mobile data more affordable.
According to the FCC, wireless microphones and other low-power auxiliary stations will be able to continue to operate in bands below 700MHz.
See a tutorial on white space networking: