Research On Blockchain-based Cooperative Spectrum Sensing Algorithm

With the vigorous development of the mobile Internet and the Internet of Things,limited spectrum resources cannot meet people’s needs for mobile services.Cognitive radio technology improves the utilization of spectrum by spectrum sharing.Spectrum sensing is the key technology of cognitive radio.In spectrum sensing technology,cooperative spectrum sensing can break through the limitations of single-user spectrum sensing so as to improve the accuracy of spectrum sensing results.Crowd sensing recruits more users to participate in sensing with incentive mechanisms.Applying the incentive mechanisms of crowd sensing into spectrum sensing can make the collection the spectrum data more flexible.Blockchain technology is a distributed database which has the characteristics of decentralization,non-tampering,transparency and traceability.The application of blockchain technology into cooperative spectrum sensing can improve the security of spectrum sensing and prevent malicious users from interfering with spectrum sensing effectively.This thesis studies the cooperative spectrum sensing algorithm based on blockchain.Aiming at the problem that there may be malicious users in spectrum sensing,a non-ideal channel cooperative spectrum sensing algorithm based on blockchain is proposed.Aiming at the privacy problem of secondary users participating in sensing,a clustering cooperative spectrum sensing algorithm based on blockchain is proposed;A cooperative spectrum sensing algorithm based on game theory is proposed for multi-task spectrum sensing.The main research contents and achievements of this thesis are as follows:(1)Aiming at the problem of malicious users in cooperative sensing,a cooperative spectrum sensing algorithm based on smart contract is proposed.The algorithm builds a system model based on smart contract in blockchain and applies blockchain asymmetric encryption algorithm and digital signature technology in the process of secondary users’ transmitting local judgments to the platform.The algorithm can resist spectrum sensing data falsification(SSDF)attack by malicious users.This paper comprehensively considers the channel error rate,detection probability,secondary user base station budget and remaining energy of the secondary users and then establishes the SU’s utility function as well as the game model.By solving the Nash equilibrium,the SU determines whether it uploads sensing data.Finally,the SU base station selects registered SUs by calculating and updating their reputation,obtaining the final judgment in voting fusion.The simulation results show that the algorithm can improve the accuracy and security of spectrum sensing,and can resist SSDF attack effectively.(2)Aiming at the problem of user privacy in cooperative spectrum sensing,a cooperative spectrum sensing algorithm based on the highest node degree clustering is proposed.The algorithm constructs a spectrum sensing system model based on blockchain which divides the secondary users who sign up to participate in the sensing task into several clusters according to their geographical location.The members in the cluster only need to send the sensing data to the cluster head.In this paper,the cluster utility function is defined based on the detection probability of secondary users,sensing time and the distance between the cluster head and the primary user.The service platform and each cluster form a Stackelberg game.After each sensing task is executed,the cluster head updates the reputation value of the members in the cluster according to the decision result of the fusion center.Then,each cluster head acts as a miner and tries to publish the block which contains execution information of the spectrum sensing task and the update of the reputation value to the blockchain.Simulation results show that the algorithm proposed in this paper can improve the security of spectrum sensing and protect personal privacy effectively.(3)A cooperative spectrum sensing algorithm based on game theory is proposed for the scenario of multiple tasks.The algorithm constructs a multi-task spectrum sensing model.Relying on the non-tampering and traceability characteristics of blockchain technology,the sensing quality of each secondary user is evaluated according to their historical sensing behavior.Greedy algorithm is applied to select secondary users.Considering the task requirements proposed by the service requester and the spectrum sensing behavior of secondary users,the utility function of secondary users is established based on the task budget,detection probability,sensing time and remaining energy.The optimal sensing time is obtained by game between secondary users to maximize their utility.After the secondary user completes the sensing task,the platform pays the reward according to the difficulty of the tasks and the sensing quality of the secondary user.Then the platform records the sensing behavior of each secondary user and updates it to the blockchain.Simulation results show that the algorithm encourages secondary users to participate in spectrum sensing tasks and improves the performance of spectrum sensing system.