Impact of Noise Power Uncertainty on Cooperative Spectrum Sensing in Cognitive Radio Systems

One of the main challenges in Cognitive Radio (CR) communications lies in the system robustness to uncertainties. In this paper, the authors examine the impact of the noise power uncertainty on the performance of various detectors in CR networks. They consider both single and multiple CR nodes. For the single CR case, they compare the performance of the energy and Likelihood Ratio Test (LRT) detectors in the presence of noise uncertainties. It is shown that both detectors perform about the same. They shall also investigate cooperative spectrum sensing based on soft-information combining, where the cooperating CR nodes experience different noise power uncertainties. They, then propose a simple detection scheme that is more robust to noise variations and uncertainties than the conventional detection schemes.