Cooperative Spectrum Sensing for Cognitive Radio ( B . Tech

With today’s increase in the usage of wireless devices and the consequent spectrum allocation, radio spectrum is becoming scarce. However studies have shown that most of the allotted spectrum is not used for large periods of time. Cognitive radio has been proposed to exploit the presence of these spectrum holes. Spectrum sensing which is one of the most important operations of cognitive radio, determines the efficiency with which the secondary users can use the primary spectrum, without causing appreciable interference to the primary users. Several factors like fading and shadowing affect the ability of the cognitive radio to detect the primary user. Previous work has shown that cooperation among the cognitive users can increase the detection probability for a given probability of false alarm. The aim of our project is to develop a spectrum sensing scheme for cognitive radio based on a model that is realistic and takes into account all the factors that would affect the system in practice. In this work, we first investigate the effect of variable channel gain on the cooperation between secondary users, as an extension of [13]. Then we go on to propose a linear cooperation based spectrum sensing scheme for OFDM based cognitive users using the energy detector method. The results of the simulations, done based on the analytical results, are then presented which show the extent of advantage cooperation between the secondary radios and the effect of the channel gain between the secondary user and the fusion centre. Finally we outline the future extensions on this work.