Research On Algorithm Of Cooperative Spectrum Sensing In Malicious Environment

With the rapid development of wireless communication technologies and the rapid increase of spectrum demand,the current static spectrum allocation policy already cannot meet the radio users' demands.Meanwhile,the allocated spectrum is not utilized efficiently,and the spectrum scarcity coexists with low utilization.The dynamic spectrum access technology proposed by cognitive radio enables the secondary users to communicate in the authorized frequency band without affecting the primary users.The technology not only improves the spectrum utilization but become an important technique to solve the spectrum scarcity.Spectrum sensing is the premise of dynamic spectrum access technology.Cooperative spectrum sensing technology can solve the problem of shadowing and multi-path fading compared with the single node,but the security problem becomes an important issue for cooperative spectrum sensing technology.The thesis studies the cooperative spectrum sensing in malicious environment in cognitive radio.We can improve the performance of the system by optimizing algorithm against attacks and adjusting the network parameters.Finally,we also study the security mechanism in M2 M system.The main work of this paper is as follows:1.The security issues for cooperative spectrum sensing in the hostile environment are summarized and analyzed.The models of the primary user emulation(PUE)attack and the spectrum sensing data falsification(SSDF)attack are established.The influences on sensing results are presented,which demonstrate the severe performance degradation for a CR(Cognitive Radio)system under these two kinds of attacks.2.According to the primary user emulation attack(PUEA),the algorithm of cooperative spectrum sensing based on energy detection was optimized.Based on this optimization algorithm,the fusion criterion and the detection threshold are optimized.Through the optimization,the total error probability is reduced and the performance of the system is improved.The optimization problem based on average throughput is studied.The simulation results show that the average throughput can be improved effectively by optimization.3.According to the spectrum sensing data falsification(SSDF)attack,the independent attack and the cooperative attack are studied,and the encryption mechanism based on message authentication code was discussed.Then the number of malicious users,the number of secondary users and the amount of encrypted information are optimized to maximize energy efficiency.The simulation results show that the system performance can be improved effectively by optimization.4.The security detection mechanism in the M2 M system is studied.CR technology which enables network nodes to sense the spectrum environment is introduced to construct the CR.Then a smart home network is constructed as a typical application model for CR.And a cooperative spectrum sensing scheme is proposed to solve its security problems deriving from the CR function.The scheme is designed with high detection rate in spectrum sensing and the ability to resist malicious attacks.Simulation results show that the proposed scheme has a satisfactory performance in spectrum detecting accuracy and security.