Research On Physical Layer Secrecy Technology Based Cooperative NOMA

With the rapid development of wireless communication technology,the security of information transmission has become an urgent problem to be solved.The security mechanism of traditional wireless communication network has high computational complexity,and due to the broadcast nature of information transmission,the confidentiality of the mechanism is very weak.In this context,physical layer security(PLS)technology provides a new approach to wireless transmission security from the perspective of information theory,which can be applied to authentication,radio frequency fingerprint of satellite communication and data encryption transmission.In addition,the combination of cooperative communication and non-orthogonal multiple access(NOMA)can expand network coverage,improve spectrum and energy efficiency,and lay the foundation for green secure communication.Cooperative NOMA often communicates by introducing relays.In one-way multi-relay system,relay selection is used to solve the problem of resource waste caused by multiple relays participating in cooperation at the same time,so as to improve the system security performance.Two-way single relay and simultaneous wireless information and power transfer(SWIPT)play an important role in solving the problem of limited spectrum resources and energy shortage.In view of this,based on cooperative NOMA,this paper analyzes PLS performance of wireless communication network,and studies the influence of relay selection on system security performance in multi-relay scenario and the security performance of two-way single relay system using SWIPT technology,providing technical reference for security optimization of wireless communication network.The main contents are as follows:(1)The system security performances of cooperative NOMA under different relay selections are analyzed.Firstly,the multi-relay Wyner model with direct link between the base station and eavesdropper is considered.Then,two relay selection schemes,namely single-phase relay selection and two-phase relay selection scheme are proposed based on this model,and the closed form of secrecy outage probability(SOP)is given.As a reference for comparison,the exact expression for SOP of random relay selection is also derived.In order to further study the security performance of this system,the asymptotic SOP and diversity order under high SNR are analyzed.(2)The security performance of cooperative NOMA system under two-way relay is analyzed.Based on the problem of energy scarcity,a two-way relay NOMA system with energy harvesting is proposed,and power splitting is considered at the relay.Then,two merging methods,namely selection combining(SC)and maximal ratio combining(MRC),are used to process the two signals received in the eavesdropper,and the security performance is compared.In order to further study the security behavior of this system,the end-to-end throughput and asymptotic SOP are derived.There are 22 figures,3 tables and 90 references.