A Scheme Against SSDF Attack Based On Variable Threshold And Optimal Threshold Strategy

Wireless communication technologies are springing up.Of course,its development will inevitably be accompanied by a variety of problems,among which the problem of low utilization of spectrum resources is one of the most urgent problems to be solved.The emergence of CR technology effectively solves this problem,mainly by sensing the surrounding environment in real time,looking for free spectrum that is not being used,and intelligently adjusting the transmission parameters of the communication to access the spectrum without affecting the normal working of the PU,effectively solving the problem.Spectrum Sensing Data Falsification(SSDF)attacks are a typical form of attack.At present,many research scholars at home and abroad have put forward some solutions,but there are still some unsolved problems: There are few studies on random SSDF attacks with a certain probability of attack,and most of them are currently not considered different signal to noise ratio and low signal to noise ratio issues against SSDF attacks.This paper proposes a combination of the fusion center variable threshold strategy and the local optimal threshold and degree of trust to defend against the SSDF attack.This article first introduces the concept,development history,research background,research significance of CR technology and security issues that scholars are more concerned about.In CRN,there are key technologies that are different from traditional networks,and the security attacks in each technical link and transmission process are described.Some unresolved issues are also introduced,focusing on the security issues in the CR spectrum sensing process.Describes how to solve T-SSDF attack methods and strategies,such as game theory,fuzzy theory,and trust-based degree.Secondly,based on the random probability T-SSDF attack,a variable threshold cooperative detection algorithm based on trust degree is proposed.The threshold of the algorithm changes with the attack condition of the MU.The variable threshold is updated by comparing the true value of the FC with the value of the upper and lower boundary values.Then the actual fusion center value is compared with the updatedthreshold to obtain the final decision.The upper and lower boundary value is determined by the given false alarm probability and missed detection probability.The degree of trust is updated based on the proportion of correct perceptions,and weights are assigned appropriately.The algorithm can not only effectively defend against SSDF attacks,but also improve the detection probability of the system while reducing the probability of missed detection and false alarm.Finally,the random probabilistic SSDF attacks are studied.Considering that SU is in a severe fading environment and the SNR is low and different,a sensing scheme based on the combination of the local optimal threshold strategy and trust is proposed to defend against SSDF attacks.In the local detection,error detection probability function is constructed to calculate the optimal threshold,the local optimal decision is made,and the difference update trust degree of the local decision and fusion center judgment result is compared,and the fusion center makes a global judgment.This algorithm improves the probability of detection that there are SSDF attacks and each SU has low and different SNR.