Research On Spectrum Sensing Technology In Cognitive Radio Networks

Cognitive radio technology is one of the key technologies for the future green wireless network.It can solve the problem of spectrum scarcity through dynamic spectrum access(DSA),and spectrum sensing can identify underutilized spectrum with characteristic interference,thus achieving reliable and efficient operation.1)Problems such as random changes in the wireless channel and waste of resources in the spectrum sensing data transmission phase.In this paper,we use the mixed gamma distribution(MG)distribution to model the generalized and composite wireless sensing fading channels.Thus we can characterize the statistical characteristics of wireless fading,which in turn improves communication quality.Then in the data transmission phase,the censor-based scheme is used to send only valid values in the perceived results,so as to achieve the purpose of conserving system resources.Finally,we derive exact analytic expressions for the corresponding probability of detection,probability of false,probability of miss-detection and secondary throughput over composite sensing fading and imperfect reporting.And the relationship among the numbers of SU,detection threshold,the error rate and the presence probability of PU presence.Finally,the accuracy and applicability of the derived formula are verified by simulations.2)When in complex depth fading,single antenna spectrum sensing requires more secondary users to participate in sensing,which waste more bandwidth resources.To deal with this limitation,censor-based CSS with multiple antennas is proposed.And the probability of detection,probability of false,probability of miss-detection and secondary throughput over both the C-MA-CSS and the T-MA-CSS with multiple antennas is derived.Capitalizing on these results,we quantify the effect of critical measures such as the detection threshold,the number of SUs and the number of employed antennas on the overall system performance.The research results indicate the C-MA-CSS can reduce the tail sensing problem greatly compared the T-MA-CSS.Besides,it is shown that theoptimal number of antennas varies depending closely on the number of SUs and the corresponding channel conditions,and optimal secondary throughput can be achieved with smaller number of antennas by the proposed algorithm.3)Both the T-SSDF attack and reporting error probabilities influence the performance of CSS detection,which results the decline of the system performance reporting error probabilities over Rayleigh sensing fading channel.Firstly,the closed-form expressions for the probability of detection,probability of false alarm and probability of miss-detection are derived in a probabilistic way.Then the relationships among them with the detection threshold are analyzed and the optimal algorithm for minimizing the probability of false is also given under optimal decision rule while assuring object detection probability.Finally,the simulations validate the optimal algorithm and shows that the optimal decision can resist the T-SSDF attack and the reporting error probabilities,thus the security of system can be improved.