Abstract
Cognitive radio based network enables oppor- tunistic dynamic spectrum access by sensing, adopting and utilizing the unused portion of licensed spectrum bands. Cognitive radio is intelligent enough to adapt the commu- nication parameters of the unused licensed spectrum. Spec- trum sensing is one of the most important tasks of the cogni- tive radio cycle. In this paper, the auto-correlation function kernel based Support Vector Machine (SVM) classifier along with Welch's Periodogram detector is successfully imple- mented for the detection of four QPSK (Quadrature Phase Shift Keying) based signals propagating through an AWGN (Additive White Gaussian Noise) channel. It is shown that the combination of statistical signal processing and machine learning concepts improve the spectrum sensing process and spectrum sensing is possible even at low Signal to Noise Ra- tio (SNR) values up to 50 dB.
Highlights
The concept of cognitive radio raised a question on the effectiveness of fixed spectrum access and indicate the need to change the spectrum assignment policy
The results show that the proposed detector detects the spectrum holes up to 89% accuracy for communication signals at very low Signal to Noise Ratio (SNR) values in AWGN Channel for QPSK based four signals
The auto-correlation function kernel based Support Vector Machine (SVM) classifier along with Welch’s periodogram detector is successfully implemented for the detection of four QPSK based signals propagating through an AWGN channel
Summary
The concept of cognitive radio raised a question on the effectiveness of fixed spectrum access and indicate the need to change the spectrum assignment policy. Various studies show under-utilization of licensed spectrum [2, 3, 4] that leads to wastage of precious radio resources. The report stated that the average utilization of licensed bands is 15–85% [2]. The temporarily unused band is known as spectrum hole. Mitola [6] is to utilize these spectrum holes without affecting the communication priority of primary (licensed) users. SDR allows cognitive user to intelligently adapt communication parameters (carrier frequency, bandwidth, power, coding schemes, modulation scheme etc.) for the unused licensed spectrum, making dynamic spectrum access possible [7]. In the United States FCC allowed the dynamic access of the UHF-TV bands by the cognitive radio devices [8]
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