Cooperative spectrum sensing for positioning in cognitive radios

The cognitive radio technology promises to become the solution to the spectrum scarcity problem, allowing secondary (unlicensed) users to opportunistically access vacant frequency bands licensed to primary users. Cooperative spectrum sensing is the technique used to discover the unoccupied frequency bands, in the presence of strong fading and shadowing effects. In addition, cooperative spectrum sensing allows to exploit positioning information as well as location awareness. The cooperative sensors are usually assumed independent each other, in order to simplify the analysis. Conversely, here we consider the case of correlated observations and propose a new double threshold test, in order to improve the detection performance, while reducing the time requested to detect a primary user. Our test combines two different fusion rules at once (i.e. the OR and the Majority voting rules), recovering all those unlucky detection cases that are not sensed due to strong shadowing. Finally, our simulation results show the effectiveness of the proposed method for application to cooperative sensing for positioning in the presence of correlated observations.