Spectrum sensing in wideband OFDM based Cognitive Radio

Cognitive Radio is a novel technology in today´s radio environment to improve the utilization efficiency of radio spectrum. In this paper we are going to use Orthogonal Frequency Division Multiplexing (OFDM) based spectrum sensing cognitive radio system is addressed. The main purpose is to identify the underutilized spectrum or white space without inferring the PU signal, called Existing Users (EUs) system altogether. To use the unused spectrum, spectrum sensing is needed to know whether the PU is present or not. The performance of cooperation based spectrum sensing scheme will be studied for OFDM based cognitive user using the energy detector method and wavelet based spectrum sensing scheme. Several factors like fading and shadowing affects the ability of cognitive radio to detect the PU. Here AWGN as well as Rayleigh fading channel are considered. Wavelet edge detection is one of the most widely used spectrum sensing 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 blurred peaks. Power spectra with conspicuous peaks utilize Haar wavelet transform, while for subtle peaks use Gaussian wavelet transform, and also explain how wavelet transform is advantageous then Energy detection.