Research On Physical Layer Security In Multiple-input Single-output Simultaneous Wireless Information And Power Transfer Communication System

With the rapid development of wireless communication technology,security caused by wireless channels broadcasting cannot be ignored.Physical layer security is a secret mechanism which uses wireless channel's physical characteristics to realize the secure information transmission and overcoming the disadvantages of traditional encryption algorithm which assume eavesdroppers have limit computing power.In addition,the rapid development of Internet of Things(IoT)requires low power consumption and large connection.In IoT applications,network nodes are large-scale and most of them are battery-powered,so energy supply becomes a key factor that restricts the network lifetime.IoT network mainly adopts orthogonal multiple access(OMA),which attributes orthogonal wireless resources to different users.Due to finite resources,the maximum subscriber numbers supported by OMA scheme are limited,which is difficult to meet the demand of massive connections..Therefore,extending the service life of wireless network and finding a new access to support massive connection is becoming important,which is based on network secure communication.Studies have shown that Simultaneous Wireless Information and Power Transfer(SWIPT)can harvest power to extend the duration of wireless communication nodes,and Non-orthogonal Multiple Access(NOMA)allows multiple users to share the same spectrum to improve the spectrum efficiency and support large-scale connections..Firstly we study the physical layer security in the multi-input single-output(MISO)SWIPT wireless communication system,and propose a design scheme to maximize the system capacity.Further extended to MISO SWIPT NOMA wireless communication system,an optimal beamforming design is present.The main contents of this article are as follows1.An artificial noise redistribution scheme is proposed in MISO SWIPT wireless communication system.Aiming at the maximization of secure communication capacity,the scheme jointly optimizes beamforming vector,artificial noise vector and power splitting ratio,to satisfies constraints of the security transmission rate and energy acquisition.The problem is non-convex and different to solve directly.By using matrix inequality(Schur complement,first-order Taylor expansion,etc.),the complex logarithmic expression is transformed into linear matrix inequality and second-order cone form,and an iterative algorithm for solving the problem is proposed based on the successive convex approximation algorithm.Simulation results show that proposed scheme of artificial noise redistribution can effectively improve the security performance of the MISO SWIPT communication system.2.An optimal beamforming precoding transmission scheme is proposed for MISO SWIPT NOMA communication system.To maximize the sum secrecy rate,we optimizes the transmission covariance under the constraints of the minimum energy collection at the energy receiver,the maximum power at transmiter and the successful decoding of SIC..Multi-variable coupling leads to the non-convexity in objective function,we propose to use semi-definite relaxation(SDR)techniques to transform the original non-convex quadratic programming quadratic constraint optimization problem into a semi-definite programming(SDP),and use convex optimization toolbox to acquire the optimal beamforming covariance matrix.Simulation results show that show that the proposed scheme can maximize the security capacity and verify that the non-orthogonal multiple access technology can improve the security performance of the system.