06-09-2017, 01:06 PM
Cognitive Radio is a new technology in today's radio environment to improve the efficiency of radio spectrum use. In this article we will use orthogonal frequency division multiplexing (OFDM) based on the detection spectrum of the cognitive radio system is addressed. The main objective is to identify the underused spectrum or the blank space without inferring the PU signal, called the Existing Users System (EU). To use the unused spectrum, the spectrum detection is necessary to know if the PU is present or not. The performance of the cooperation based on the spectrum detection scheme will be studied for OFDM based on the cognitive user using the energy detector method and wavelet-based spectrum detection scheme. Several factors such as fading and shadow affect cognitive radio ability to detect PU. Here AWGN as well as Rayleigh fading channel are considered. Wavelet edge detection is one of the most widely used spectrum detection techniques. This technique observes a spatial distribution of spectral data at multiple resolutions. The slope of the power spectral density is used as an index to differentiate between sharp and fuzzy peaks. The power spectra with attractive peaks use the Haar wavelet transform, whereas for the subtle peaks they use the Gaussian wavelet transform, and also explain how the wavelet transform is advantageous, then the energy detection.