Blind multiband spectrum sensing for cognitive radio systems with smart antennas

Abstract

Energy detection is a widely used method for spectrum sensing in cognitive radios because of its simplicity and accuracy. However, it is severely affected by noise uncertainty. To solve this problem, this study raises a blind multiband spectrum sensing method with smart antennas which is robust to noise uncertainty. The proposed method performs spectrum sensing simultaneously over the total frequency channels rather than a single channel each time. Owing to the fact that the noise eigenvectors of the sample covariance matrix are orthogonal to the direction matrix whereas the signal eigenvectors are not, the proposal utilises the Gerschgorin radii of the unitary transformed covariance matrix to distinguish the noise from the signal. Unlike the conventional sensing methods, the authors' approach does not need any prior knowledge of the noise power or the primary user signals, which makes it suitable for blind spectrum sensing. This study presents simulations in various conditions to validate the performance of the proposed scheme and shows that their proposal outperforms the other existing methods.