Energy and Eigenvalue Based Combined Fully Blind Self Adapted Spectrum Sensing Algorithm

In this paper, a comparison between energy and maximum-minimum eigenvalue (MME) detectors is performed. The comparison has been made concerning the sensing complexity and the sensing accuracy in terms of the receiver operating characteristic (ROC) curves. The impact of the signal bandwidth compared with the observation bandwidth is studied for each detector. For the energy detector, the probability of detection increases monotonically with the increase in the signal bandwidth. For the MME detector, an optimal value of the ratio between the signal bandwidth and the observation bandwidth is found to be 0.5 when reasonable values of the system dimensionality are used. Based on the comparison findings, a combined two-stage detector is proposed. The combined detector performance is evaluated based on simulations and measurements. The combined detector achieves better sensing accuracy than the two individual detectors with complexity that lies in between the two individual complexities. The combined detector is fully blind and self-adapted as the MME detector estimates the noise and feeds it back to the energy detector. The performance of the noise estimation process is evaluated in terms of the normalized mean square error (NMSE).