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Cooperative spectrum sensing by improved energy detector for heterogeneous environments in cognitive radio networks

Cognitive radio networks can improve the efficient use of spectrum through opportunistic access to the licensed bands without interfering with the primary users. Spectrum sensing, as an important functionality in cognitive radios (CRs), needs to reliably detect the signals from licensed primary radios. To achieve this, improved energy detector is proposed. By using optimum norm of the received signal samples in improved energy detector, the detection performance is improved as compared to the conventional detector. In the literature, Cooperation between CRs is proposed to avoid interference in primary users and increase the utilization of spectrum. In this paper, we assume a cooperative scheme where each CR senses a common frequency band with a different average SNR. According to Neyman-Pearson theorem, optimum norm of the received samples are compared to a predetermined threshold. Then, binary decision of each CR is sent to a fusion center (FC) to make final decision about presence or absence of primary users. The numerical results show that the performance of cooperative spectrum sensing with improved energy detector is increased considerably as compared to the conventional ones. The results also show that the OR rule outperforms the AND and the majority rules in both energy detectors.