Short Range White Space Utilization in Broadcast Systems for Indoor Environments

As Digital Television Broadcasting spreads over the world, existing (and more) TV channels can be distributed in less spectrum in the spectrum traditionally allocated to TV broadcasting. This freed spectrum is also referred to as the "Digital Dividend" and its use has been debated around the world. In addition, there is also a debate about the potential use of the "white space" within the TV-bands. This is due to the sparse frequency planning with large interference margins, which is typical in wide area broadcasting. Various technical approaches using Opportunistic Spectrum Access (OSA) have been proposed for unlicensed "white space" access to the TV bands. Most of previous studies have focused on spectrum sensing, i.e. detecting "free channels", where secondary users, utilizing White Space Devices (WSD) could avoid causing harmful interference to the TV receivers. However, interference caused by WSD is not only limited to co-channel interference. In particular, in short-range scenarios, the adjacent channel interference is an equally severe problem. Assessing the feasibility of WSDs in short-range indoor scenarios, taking more interference mechanisms into account is the objective of this paper. An Indoor home scenario with Cable, Rooftop antenna and Set-top antenna reception of DVB-T, has been analyzed. The spectrum reuse opportunities for WSDs have been determined, using the number of channels where it is possible to transmit without causing harmful interference to DVB-T receivers as performance measure. Simulation results show that the number of available channels for indoor unlicensed white space transmission appears to be significant in most of the studied scenarios.