Error distribution in maximum likelihood estimation of radio propagation model parameters

A growing demand for bandwidth in wireless data networks has motivated policy makers to consider opening underused frequencies, e.g. in the TV broadcasting bands, to opportunistic secondary access. To support secondary network operations in these TV whitespaces (TVWS), centralized databases are envisioned that employ radio propagation models to derive the spectrum usage of the primary system. Precise estimation of the actual spectrum usage is highly important in this scenario, because maladjusted models can cause primary outage or hamper secondary capacity. The requirements for accurate propagation estimation have hence further increased. Using the example of a single TV transmitter, we study in this poster the prospects of maximum likelihood estimation for generic power law propagation models. Transmitter characteristics are considered known, but environment-specific parameters of the model are derived through fitting measurement results, obtained, e.g., through drive tests. We derive for the case of uncorrelated shadow fading the error distributions and their parameters for two parameters, namely pathloss coefficient and shadow variance. Our results are applicable to other large-scale scenarios where precise signal strength estimation is required. They can help to minimize the number of required measurements and to determine necessary protection policies.