Research On Technologies Of Opportunistic Cooperation And Anti-tamper Attack In Cognitive Spectrum Sensing

The limited spectrum resources are becoming more and more scarce in the face of growing wireless communication equipment.Cooperative spectrum sensing(CSS)is one of the key technologies of cognitive radio.Through the cooperation of multi-sensing user,the target frequency band can be allocated to other secondary users under the premise that the primary user does not use the target frequency band,so as to make full use of Spectrum resources and become an effective way to solve the shortage of Spectrum resources..If the malicious user(MU)exists in the cooperative sensing system and the malicious users sends false information to the fusion center,which will cause misjudgment of the fusion center and ultimately affect the user security of the primary user.Therefore,in the case of low SNR,improving detection probability and preventing malicious user attacks have become a hot topic of cooperative spectrum sensing.In this paper,we have carried out the research on cognitive spectrum sensing opportunistic cooperation and tamper-resistant attack technology.The main work completed is as follows:Firstly,the existing spectrum sensing technology is introduced.This paper introduces three classical spectrum sensing algorithms: traditional matched filter detection,energy detection and cyclostationary detection,and their advantages and disadvantages are analyzed.Secondly,the random matrix theory is introduced,and the spectrum sensing algorithm based on the maximum minimum eigenvalue(MME)of random matrix is analyzed.Then,centralized and distributed cooperative spectrum sensing and five common spectrum sensing fusion strategies are analyzed.Finally,for the security problem of spectrum sensing,this paper analyzes the spectrum sensing data falsification(SSDF)and the corresponding defense strategies in detail.Aiming at the defects of low detection probability and high detection energy consumption of traditional spectrum sensing with low SNR,an opportunistic cooperative spectrum sensing algorithm based on eigenvalue ratio of random matrix is proposed.By improving the MME algorithm,the advantages of low complexity and blind detection of energy detection are retained.According to the difference of odd-even time slot,the sensing user uses hard decision in odd time slot,and uses double thresholds and data fusion soft combination in even time slot,which effectively realize opportunistic cooperation and reduce the impact of soft fusion on computing efficiency.The simulation results show that the proposed algorithm has better performance than the existing MME algorithm in detection probability under low SNR and different false alarm probability.When the SNR is-13 d B,the detection probability of the proposed algorithm is 0.70 higher than that of MME algorithm,and the detection performance is significantly improved.To solve the problem of malicious user attack in multi-user cooperative spectrum sensing,an anti-SSDF spectrum sensing algorithm is proposed.Taking the eigenvalue ratio of the received signal as the decision value,the reputation of the sensing user is dynamically updated by the improved fusion strategy,which solves the problem that malicious users cheat the fusion center by accumulating reputation and thus affect the decision result.This algorithm can force malicious users to submit correct sensing results to reduce the interference of malicious users to the system,and retain the advantages of energy detection algorithm such as low complexity and blind detection.The simulation results show that: compared with the traditional equal-gain algorithm,the anti-SSDF spectrum sensing algorithm has higher detection and malicious user identification probability in the harsh communication environment such as low SNR and high proportion of malicious users.when the false alarm probability is 0.01,the signal-to-noise ratio is-14 d B,and the malicious user attack environment,the detection probability value of the proposed algorithm is higher than that of equal gain algorithm by 0.72,which reduces the system security risk.This paper focuses on the research of cognitive spectrum sensing opportunistic cooperation and tamper-resistant attack technology.The proposed algorithm can improve the detection probability of primary user signal in low SNR and multi-malicious user scenarios,so as to improve the robustness of spectrum sensing algorithm and make it suitable for application in cognitive wireless communication systems with bad transmission channels and malicious users.