  Recent FCC regulations on TV white spaces allow geo-location databases to be
the sole source of spectrum information for White Space Devices (WSDs).
Geo-location databases protect TV band incumbents by keeping track of TV
transmitters and their protected service areas based on their location,
transmission parameters and sophisticated propagation models. In this article,
we argue that keeping track of both TV transmitters and TV receivers (i.e. TV
sets) can achieve significant improvement in the availability of white spaces.
We first identify wasted spectrum opportunities, both temporal and spatial, due
to the current approach of white spaces detection. We then propose DynaWhite, a
cloud-based architecture that orchestrates the detection and dissemination of
highly-dynamic, real-time, and fine-grained TV white space information.
DynaWhite introduces the next generation of geo-location databases by combining
traditional sensing techniques with a novel unconventional sensing approach
based on the detection of the passive TV receivers using standard cell phones.
We present a quantitative evaluation of the potential gains in white space
availability for large scale deployments of DynaWhite. We finally identify
challenges that need to be addressed in the research community in order to
exploit this potential for leveraging dynamic real-time fine-grained TV white
spaces.
