Energy-Based Maximum Likelihood Spectrum Sensing Method for the Cognitive Radio

In the rapid development of current wireless communication systems, how to effectively utilize the limited system spectrum to provide the high-speed data rate service becomes a very critical issue for the system operators. To improve the utilization efficiency of the wireless spectrum, the cognitive radio (CR) had been proposed currently. The key issue of applying the CR technique successfully is how to sense exactly and quickly whether or not the primary user exists, and looking for the spectrum holes to provide the secondary user. In this paper, an energy-based maximum likelihood (ML) spectrum sensing method for the CR is proposed. The proposed method avoids the troublesome calculation of the required threshold and has almost the optimal performance for the conventional energy-based method. Besides, incorporated with the double threshold, an extension of the proposed ML method is also provided to speed up the sensing period without degrading the detection performance.