Performance of Spectrum Sensing Schemes in Cognitive Radio for Static and Dynamic Primary Users in Additive Laplacian Noise

Abstract

Due to the evolution in wireless communications, the RF spectrum is overcrowded as it is scarce and newlineexpensive. However, it has been observed that the licensed spectrum remains underutilized. In the newlineliterature, various spectrum sensing schemes have been proposed for efficient spectrum utilization. In newlinethis case, the cognitive radio (CR) terminal senses the licensed spectrum of the primary user (PU). If newlinethe spectrum is found vacant, then the unlicensed user or secondary user (SU) can utilize the spectrum newlinewithout interfering with the PU. The performance of the spectrum sensing techniques is presented newlineand evaluated using receiver operating characteristics (ROC). The ROC for different spectrum sensing newlinetechniques is presented and compared with the literature assuming different scenarios such as coherent newlineand non-coherent detections, different channel environments, PU with different waveforms, and various newlinediversity schemes. A majority of the papers have assumed additive white Gaussian noise (AWGN) newlineand static behavior of PU in the sensing interval. However, in a real-time scenario, these assumptions newlineare difficult to follow. For example, in the multi-user environment, the interference from different newlinesources such as multiple access interference (MAI) can be well approximated by additive Laplacian newlinenoise instead of AWGN. Further, due to the large density of PU and their frequent transitions, the newlinestatic nature of PU in the sensing interval may not be followed. The dynamic behavior of the PU newlinedegrades the ROC performance of detection schemes, which assumed static behavior. newlineIn this thesis, we assume additive Laplacian noise (ALN) channel instead of AWGN channel. We newlineassume static PU and use a modified correlation detector (MCD) with cooperative spectrum sensing newline(CSS) scheme. We compare our proposed correlation detection scheme with the other state-of-the art newlineof the correlation detection schemes. Dynamic behavior of the PU, where PU may randomly change newlineits states within sensing period, has not been analyzed with ALN in the literatur