creases effective coverage. This provides economic benefits in terms of rural coverage and urban in building penetration and a benefit to users in terms of reduced DC power drain when viewing digital TV content. However, this in turn depends on network density. Terrestrial Broadcast/Cellular Network Integration 15.8.1 Network Density and Cooperative Network Opportunities There is a trend in digital TV broadcasting towards implementing an increasing number of lower-power sites, particularly in urban areas. Many of these potential sites are owned by cellular operators or administered, owned and/or managed by common third parties such as Crown Castle. A faster than expected transition to high-definition TV including high-definition TV and an earlier than expected transition to super-high-definition TV strengthens the rationale for pro- viding TV broadcast bandwidth from smaller sites previously optimised for cellular. The same principle could apply for local digital TV and digital radio broadcasts that could potentially be supported on interleaved spectrum. Successful cosharing is, however, dependent on closer integration of broadcast and cellular technologies (DVB in Europe, ATSC in the US) and now LTE mobile broadband and legacy cellular networks and effective mitigation of shared spectrum interference. White-Space Devices This brings us to white-space devices. Terrestrial TV networks are either implemented as single-frequency networks or more usually multifrequency networks. The reason for implementing multifrequency networks is that these are or at least have been high-power networks and the signals from a dominant mast can travel tens of miles and in some propagation conditions hundreds of miles. Compared to cellular networks (relatively low powered with transmit antennas installed generally a much lower height than TV) TV networks are conservatively planned, which means that interleaved channels are often unoccupied in some places at some times. White-space devices are cognitive devices that are supposed to de