Frequency Domain Energy Detection for Multiband Spectrum Sensing in Cognitive Radio System

The rapid development of wireless technology compels to efficient use of frequency bands. One possible way to achieve this goal is the cognitive radio (CR) systems, which allow a frequency band, possessed by a primary user (PU), to be borrowed by the secondary users (SUs) who can dynamically access the frequency band. Spectrum sensing process plays a key part in the CR system as SU has to gauge multiple frequency bands to decide if a band is occupied or not. This paper proposed a spectrum sensing approach for a multiband channel scenario. First, the power spectral density (PSD) of the received signal is computed and then the detection process is carried out separately in each subband in the frequency domain. By analyzing the estimated PSD and the noise power, a threshold is applied on the received signal to conclude the existence of PU. The performance of this method was evaluated and compared with the existing energy detection and k-means clustering methods. The result shows that the proposed method has a better performance compared to the other two existing methods. The method can detect the presence of PU in a lower signal-to-noise ratio while maintaining the acceptable detection performance.