Secure Relay Selection And Power Allocation In Cognitive Radio Nerworks

Cognitive radio technology can effectively solve the low utilization of spectrum in the traditional fixed spectrum allocation policy. Meanwhile, Cooperative relay technology combined with cognitive radio technology, can greatly improve the overall performance of the cognitive network to meet the user demand for high-speed communication. But the combination of the two technologies makes the network more complex, introduce specific security threat. For the relay selection and power allocation problem in cooperative cognitive radio network, each node needs to consider the interference to the primary user, bring new challenges to the resources allocation. Based on the above challenges, this paper discussed the physical layer security issues in cooperation cognitive radio network. For collaborative communication, how to choose a suitable relay node will have a significant impact on the system security performance. Therefore ensure that under the premise of the main users are not affected, we need to raise communication quality of the cognitive users as much as possible. Based on previous studies, this paper based on physical layer security in collaborative cognitive radio networks, investigates the optimal relay selection algorithm and performed optimal power allocation scheme for maximizing safety rate when the total system power between the nodes is limited.The paper firstly designed an optimal relay selection scheme based on maximizing the security capacity in cognitive radio system, the interference of the cognitive nodes to primary user were also taken into account. Then from a point of the secure outage probability, compared and analyzed the performance with traditional relay selection scheme. Then for the system based on safety and non-safety scenarios, taking into account the cognitive interference to the primary user and the total power is limited, designed the optimal transmit power allocation scheme and designed a power iterative adjustment algorithm to reduce computational complexity. Through simulation compared with equal power allocation scheme, the results proved that the proposed power allocation scheme can enhance the system performance while meet the system interference limits of the cognitive radio network at the same time.