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Performance limits of cooperative eigenvalue-based spectrum sensing under noise calibration uncertainty

A collaborative spectrum sensing system with a fusion center, which utilizes the eigenvalues of the sample covariance matrix for detection, is investigated. On the example of two widely known detectors, we show that imperfect calibration with respect to the noise powers of the receivers leads to a so-called SNR wall in eigenvalue-based detectors. The SNR wall manifests itself as an SNR threshold below which detection becomes impossible even if the number of samples tends to infinity. We quantify the performance limits of the detectors in question by deriving lower bounds on the SNR wall and verify them by numerical evaluation. The results show that a very large number of cooperating receivers is needed to enable detection at very low SNRs, which are customary in spectrum sensing.