Reducing spectrum use in traditional and SFN-based television for uniform and non-uniform deployments

During the last few years, reclaiming TV spectrum for mobile broadband use has been a hotly debated topic in the telecommunications policy agenda. This paper evaluates two ways to improve spectrum efficiency to today's noise-limited single-transmitter broadcast television approach. One way is to increase the transmit power of each broadcaster's only transmitter. The other way is to replace that single transmitter with a multi-transmitter low-power low-tower (LPLT) single frequency network (SFN). In order to quantify their potential benefits, two different scenarios are considered. First, this paper presents the results obtained for a large region in which broadcasters are uniformly distributed, so that the number of TV broadcasts that can be received is roughly the same at any location. In this case, results suggest that increasing power of traditional single-transmitter broadcasters could reduce the amount of spectrum needed for TV by up to 30%, and would be cost-effective for population densities above 30 per square km. A switch to SFNs could reduce the amount of spectrum needed for TV by roughly 60%, but at a higher cost. Results suggest that the LPLT SFN approach could be cost-effective for regions with uniformly distributed broadcasters and population densities above 120 per square km. The study then quantifies spectrum efficiency gains in regions where broadcasters are not uniformly distributed. In particular, it considers the case where U.S. broadcasters in the UHF band continue to serve their coverage areas as of 2015. In this case, the amount of spectrum that can be freed from TV throughout the entire nation using these two approach is considerably smaller, but some additional bands can be freed from TV throughout much of the nation. Moreover, most of these spectrum gains can be obtained when only a minority of broadcasters change their technical approach.