White Spaces Spectrum 
When wireless spectrum was first allocated for television broadcast in the early part of the 20th century, broadcast and broadcast reception technology was crude by today’s standards. In essence, broadband transmitters had to “shout” because the reception devices were a bit deaf. In order to cope with these loud services, regulators decided that gaps should be left in spectrum assignments as “guard” bands to prevent television signals from interfering with each other. These “guard” bands are also known as television white spaces because of the “white” noise signal that appears on a television in these unused bands.
Things have changed. Wireless technology has evolved to the point where it can operate efficiently within these “guard” bands without interfering with television broadcast. The UK is considering the best way to implement it  and the United States Federal Communications Commission (FCC) has approved Television White Spaces (TVWS) spectrum for unlicensed use (subject to power restrictions to avoid interference with existing television services) saying:
“This particular spectrum has excellent propagation characteristics that allow signals to reach farther and penetrate walls and other structures. Access to this spectrum could enable more powerful public Internet connections - - super Wi-Fi hot spots - - with extended range, fewer dead spots, and improved individual speeds as a result of reduced congestion on existing networks. Many other applications are possible, such as broadband access to schools particularly in rural areas, campus networks that are better able to keep pace with user’s increasing demands for bandwidth, home networks that are better able to support real time streaming video applications, remote sensing of water supplies by municipalities and support for the smart grid. The potential uses of this spectrum are limited only by the imagination.” 
Some important benefits are:
1. More competition. TVWS technology is designed for unlicensed (but not unregulated) use. This means that TVWS technology can be deployed in a very similar manner to other unlicensed wireless technologies such as WiFi. This means lower barriers to market entry, more competition, and ultimately more service and better prices for consumers.
2. More innovation. When the 2.4GHz band was designated for unlicensed use, nobody predicted the wealth of new devices that would emerge from microwave ovens to baby monitors to the nearly ubiquitous WiFi. Creating another range of unlicensed spectrum will attract entrepreneurs and innovators to create new services that we haven’t dreamt of yet.
3. Less administrative overhead. Re-allocating spectrum involves moving existing spectrum holders from one band to another band. This process is notoriously painful and long-winded. TVWS spectrum can re-use unused television broadcast spectrum without moving or interfering with any existing spectrum holders.
4. More performance. Television spectrum is capable of penetrating obstacles such as trees and building much more easily than WiFi spectrum or WiMax for that matter. This means that it will be MUCH easier to deploy this technology and it can be deployed a lot more affordably.
 The first half of this note draws on http://www.openspectrum.org.za/background/
 Unlicensed Operation in the TV Broadcast Bands, ET Docket No. 04-186, Second Memorandum Opinion and Order, ¶2 FCC 10-174 (rel. Sep. 23, 2010) http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-174A1.doc