Research On Physical Layer Security Strategy In Cooperative Cognitive Radio Network

With the development of wireless communication technology,wireless terminal equipment and data volume have shown rapid growth,and the demand for radio frequency spectrum is also increasing.Cooperative cognitive radio network(CCRN)is a new type of intelligent wireless network,which can not only solve the problem of scarce spectrum resources,but also improve the transmission performance of the system through cooperative relay technology.Simultaneous wireless information and power transfer(SWIPT)is a new combination of wireless communication technology and wireless power transmission technology.It is a new technology that uses radio frequency signals to simultaneously transmit signals and energy.It has a wide range of applications in energy-constrained networks.However,as a new type of wireless network,due to the unauthorized nature of secondary users in the cognitive network and the openness of the wireless network,the secure communication of the network has attracted widespread attention in academia and industry.Traditional secure communications use encryption algorithms to encrypt the transmitted information to ensure the security of the information.The development of random computers,traditional encryption algorithms have more and more flaws.The existing research in this thesis mainly focuses on the performance of the primary network.There are relatively few studies,especially on the issue of secondary network resource allocation and secure communication.This thesis mainly studies the problem of resource allocation in the secondary network in CCRN and considers the problem of secure transmission of the secondary network when eavesdropping nodes are present.Physical layer security technology of wireless channels is used to ensure the safe transmission of signals.Therefore,the specific research work of the thesis is as follows:1)Research on resource allocation in a CCRN based on SWIPT.In the CCRN,the signal transmission of the secondary user will cause interference to the primary user,and the signal of the secondary network must be controlled below a certain threshold.Considering the total transmit power and signal interference constraints,an optimization problem to maximize the channel capacity of the secondary network is established.Among multiple relay nodes,an optimal relay is selected through a relay selection algorithm.Aiming at the non-convexity of the original problem,the original problem is transformed into a convex optimization problem by means of variable substitution,and solved using KKT conditions and gradient descent algorithm.Finally,a large number of simulation experiments verify the performance of the algorithm.2)To study the problem of secure communication in a CCRN based on energy-carrying communication.In the above CCRN,consider the existence of eavesdropping nodes,combine the constraints of total transmit power and signal interference,and establish a maximized secondary network Safe rate model.In view of the complexity of the target problem,the original problem is decomposed into two sub-problems of total power allocation and power splitting,and the two sub-problems are solved using difference approximate programming and genetic algorithm respectively.Then,the two algorithms are combined to obtain a joint optimization algorithm that can obtain the optimal safety rate.Aiming at the selection of multiple relays,a dual-relay selection strategy is proposed.Finally,the performance of the algorithm is demonstrated through a large number of simulation experiments.