A Fully-Distributed Radio Source Detector for Fast Fading Rayleigh Channels

In this article, we consider the problem of fully-distributed detection of a source emitting a radio signal in a fast fading scenario. We consider that geographically distributed sensor nodes obtain energy measurements and compute cooperatively and in a distributed fashion a decision metric for detecting if the source is present or absent without the need of a fusion center. Since we assume that the sensing channels -from the source to the nodes-vary rapidly due to the nodes and/or the source mobility, we design an algorithm based on the statistical channel state information (S-CSI), instead of the instantaneous channel state information (I-CSI). Nevertheless, even in this scenario, the derived model has some unknown parameters (such as the source transmitted energy or the channel mean attenuation). Therefore, we follow the philosophy of the Generalized Likelihood Ratio Test (GLRT) theory and obtain a test statistic suitable for scenarios without a fusion center: the S-GLRT statistic. We compute its performance through Monte Carlo simulations, and find that S-GLRT overcomes other algorithms available in the literature which are frequently used in similar scenarios.