Efficient Spectrum Sensing Via Multiple Primary Users Cooperation In Cognitive Radio Networks

Recently, with the development of wireless communications, the demand for spectrum isincreasing. The spectrum resource is becoming a scarce resource. In this condition, thecognitive radio has become a hot spot, because it can detect the spectrum hole and use thespectrum hole properly. It increases the spectrum utilization and becomes one of the keytechnologies of the future wireless communications. The most important issues in cognitiveradio include sensing the spectrum environment, spectrum assignment and spectrumsharing. Hence, the spectrum sensing is a very important part in cognitive radio. In thispaper, we study some spectrum sensing technologies.First, we introduce some local spectrum sensing methods and make some comparisons ofthem. In traditional spectrum detection, the performance of spectrum sensing is not verywell because of the shadowing and fading effect as well as the hidden primary user problem.Then, we study the cooperative spectrum sensing. Some research has showed thatcooperating all secondary users in the network does not necessary achieve the optimumperformance, but instead, it is achieved by cooperating a certain number of users with thehighest primary user’s signal-to-noise ratio. In this paper, we study the cooperativespectrum sensing with multiple primary users. To minimize the probability of false alarmwhile keeping the probability of detection, we formulate the cooperation of secondary usersas an optimization problem. However, this optimization problem is hard to solve, wepropose two suboptimal schemes, which can improve the detection performanceconsiderably.Finally, we make some simulations. The results show that the proposed methods canreduce the probability of false alarm considerably while keeping the probability ofdetection.