Estimation of Spectrum Holes in Cognitive Radio using PSD

As frequency is a scarce resource, so efforts are being made to use the allotted frequency spectrum as competently as possible. The concept of Frequency Reuse efficiently serves this purpose by reusing the frequencies and channels in a communication system to improve its capacity and spectral efficiency. Cognitive Radio is one of the emerging technologies that apply frequency reuse method as its working principle. Cognitive Radio is an intelligent transceiver system that continuously monitors its Radio Frequency environment in search of the unused frequency slots (known as spectrum holes) that had been provided to the primary user and supply it to another user (known as secondary user) for its use. The process of searching of these empty slots by cognitive radio is called Spectrum sensing. Out of many available processes the least complex process of Spectrum sensing is energy detection of the channels. Energy Detection technique is the method in which energy in the channel is sensed to search for the presence of primary user in the channel. In this paper Power Spectral Density (PSD) of the channel is obtained to examine the existence of user in the channel.