Double threshold energy detection using sequential cooperative spectrum sensing in Rayleigh fading

Spectrum sensing is the primary essentiality to monitor the presence of primary user in cognitive radios. Among all the spectrum sensing techniques energy detection is preferable because it is simple and prior knowledge of primary user is not required, but conventional energy detection is not preferable in low SNR regions. In this paper we discuss a cooperative double threshold method with two thresholds which are decided by an uncertainty parameter. In the confusion region we use a weighted sequential energy detection (WSED) method which considers a fixed number of past observations. For making a decision in confusion region, both the current and past observations are weighted and aggregated. Equations for probability of detection and probability of false alarm in Rayleigh channel are derived for the discussed scheme. Numerical results shows that the scheme gives better performance as compared to the conventional method.