# Fast Spectrum Sensing Method for Cognitive Radio

## DOI:

https://doi.org/10.20535/RADAP.2020.83.41-46## Keywords:

coefficient of variation, iterative method, cognitive radio, golden ratio, spectrum occupancy, threshold## Abstract

A key aspect of the functioning of cognitive radio systems is fast and reliable detection of unoccupied channels in cases of dynamic changes of electronic environment. To solve this problem, a fast iterative method based on the coefficient of variation as decisive statistic of the power spectral density (PSD) is proposed. The essence of the method is in comparing the values of the coefficient of variation with the threshold value using the predicted value of the number of signal samples and the method of the golden ratio. The threshold values of the decision statistics were obtained by calculating the vector of PSD, sorting and normalizing it to energy, and calculating the vector of values of the coefficients of variation by sequential removing from the normalized PSD samples with the maximum value. To reduce the number of iterations when calculating the decisive statistics, the predicted value of spectrum occupancy is used. This value is calculated using an empirical formula with the coefficient of variation for the zero iteration as an argument. In practice, the presence of several signals with different powers in the analyzed bandwidth leads to errors in the predicted value of spectrum occupancy. Moreover, the larger the dynamic range and the lower the signal-to-noise ratio, the greater this error will be. The predicted value of the spectrum occupancy is a rough estimate of the number of signal samples in the spectrum, and the golden ratio method was applied to find its true value in fast way. Processing gain in reducing the number of iterations for calculating the decisive statistics depends on the spectrum occupancy prediction error and can reach several tens of times. The proposed method can be used to improve existing and develop new cognitive radio systems based on Software Defined Radio (SDR) technology.

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*Visnyk NTUU KPI Seriia - Radiotekhnika Radioaparatobuduvannia*, (83), pp. 41-46. doi: 10.20535/RADAP.2020.83.41-46.

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Copyright (c) 2020 Микола Вікторович Бугайов

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