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. In our experience, these changes are not uncommon. The latter, a model-driven approach does not suffer from these drawbacks, and our SenseLess system takes this approach. However, the key question of any.
