DETECTION OF VACANT FREQUENCY BANDS IN COGNITIVE RADIO

Abstract: Cognitive radio is an exciting promising technology which not only has the potential of dealing with the inflexible prerequisites but also the scarcity of the radio spectrum usage. Such an innovative and transforming technology presents an exemplar change in the design of wireless communication systems, as it allows the efficient utilization of the radio spectrum by transforming the capability to dispersed terminals or radio cells of radio sensing, active spectrum sharing and self-adaptation procedure. Cooperative communications and networking is one more new communication skill prototype that permits the distributed terminals in a wireless network to cooperate with each other through some distributed transmission or signal processing in order to comprehend a new appearance of space diversity to contest the detrimental effects of fading channels. In this thesis, we regard the relevance of these technologies to spectrum sensing and spectrum sharing. One of the most vital challenges for cognitive radio systems is to diagnose the existence of primary (licensed) users over an extensive range of spectrum at a particular time and explicit geographic locality. We consider the utilization of cooperative spectrum sensing in cognitive radio systems to increase the consistency of detecting of primary users. We describe spectrum sensing for cognitive radios (CRs) and project a vigorous cooperative spectrum sensing procedure for a practical framework employing cognitive radios. Cooperative sensing can formulate excellent use of network assets, attain higher gain and make the network smooth. In this thesis we give a concise introduction of the principle of cooperative sensing and discuss the cooperative sensing techniques in CRs. Simulation results confirm that cooperative sensing can get better detection probability, can advance the agility gain and as a result finally help with more efficient utilization of spectrum.