In this paper, we consider the problem of using three sensors to detect whether a certain spectrum is occupied or not. Each sensor sends its binary decision to the data fusion center through a wireless fading channel. The data fusion center combines the outcomes for an overall decision. Our analysis shows that a basic sensor network does not result in a high enough correct probability of the overall decision when the wireless fading channels experience low SNR. Then, we observe that this probability could be significantly increased with the deployment of relays in the network. However, a sensor network with relays still suffers from energy and spectral inefficiency. The sensor network with an intermediate fusion helper was recently proposed to reduce the traffic load at the data fusion center. We examine the correct probability of the overall decision resulting from a sensor network with an intermediate fusion helper. Our evaluation establishes that a sensor network with an intermediate fusion helper performs almost as good as the sensor network with relays, but with energy and spectral advantages.
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