To learn the white space availability at a given location,
the database could use one of two schemes: use spectrum
measurements for that location, or compute spectrum availabil-
ity using RF propagation models. The former, a data-driven
approach, requires extensive wardriving measurements at low
sensitivity thresholds and may take a long time to be complete.
Furthermore, the measurements will have to be repeated when-
ever the primary user’s transmission characteristics, such as
transmit power, antenna height, license terms, etc., change.