Introduction
Digital terrestrial television became a reality in the mid-1990s, when DVB-T and ATSC A/53, the two main standards to enable terrestrial transmission of digitized TV signals, were approved and adopted in Europe and the United States, respectively. Since then, various similar standards have been developed for use in other countries, mainly in China (DMB-T) and Japan (ISDB-T). Going a step further, in Europe, the second-generation terrestrial standard (DVB-T2), adopted by the European Telecommunications Standards Institute (ETSI) in 2009, is offering increased spectral efficiency, greater flexibility, and MIMO support. The transition to digital television not only presents benefits to broadcasters and TV viewers, but also introduces — as a by-product — unique opportunities for players of the wireless networking market via the careful and regulated exploitation of locally underused portions of the TV bands. This potential benefit is presented and quantified in the following sections.