Cooperative Spectrum Sensing Techniques with Temporal Dispersive Reporting Channels

Cooperative approaches have been proposed as an effective way to improve the spectrum sensing accuracy. Generally, cooperative spectrum sensing techniques require two successive stages: sensing and reporting. The reporting channels are usually assumed ideal. In this paper, we remove this assumption and we investigate the effects of reporting channels affected by temporal dispersion on cooperative spectrum sensing. To this aim, we propose two fusion schemes: a Widely Linear scheme and a Linear one. For both the schemes, closed-form expressions of the detection and the false alarm probabilities are derived. The performance are also evaluated numerically, and the results show that the Widely Linear detector outperforms the Linear one in operative conditions of practical interest. Moreover, for the sake of completeness, a theoretical comparison of the proposed detectors is carried out for reporting channels affected by multipath frequency non-selective fading. Surprisingly, the analysis proves that the two detectors perform exactly the same under this assumption. Therefore, there is not anymore advantage in using the Widely Linear scheme, which exhibits higher, although limited, computational complexity. The theoretical analysis is validated numerically.