In this paper one of the most important cognitive radiotask i.e. spectrum sensing is explained in detail. Cognitive radio isan intelligent wireless communication technology in order toincrease the spectrum efficiency. Increasing efficiency of thespectrum usage is an urgent need as an intrinsic result of theincreasing demand for higher data rates, better quality of servicesand higher capacity. There are several spectrum sensingtechniques proposed in literature for cognitive radio basedsystems like Non cooperative and cooperative spectrum sensing.But there are some practical challenges and limitations in thesetechniques. So this paper provides the idea behind the MIMOconcept in cognitive radio where multiple antennas can be placedboth on primary user and secondary user and results evaluate theperformance of its implementation. With the emergence of MIMOsystem, multipath were effectively converted into benefit forcommunication system. The probability of detection increases andthe probability of false alarm decreases as given below in thesimulation section.