Research On The Physical Layer Security Technology In Large Scale Antenna SWIPT System

Currently,the application of wireless communication technology is becoming more and more widely.However,some wireless devices cannot replace batteries or connect to the power conveniently in some specific scenarios,resulting in limited operation time and reduced communication quality.Simultaneous wireless information and power transfer(SWIPT)technology can effectively solve the problem of wireless device power supply,and its related signal processing technology has attracted much attention as a new research direction.Large scale antenna technology can make full use of spatial degree of freedom,improve the spectrum utilization of the system,and have high efficiency of energy utilization.While,due to the openness and fading of the wireless channel,there are some problems,such as information eavesdropped,the lower energy harvesting efficiency of wireless devices,etc.Therefore,it is very important to enhance the communication security of the system under energy harvesting constraints.Compared with the traditional encryption technology,the large-scale antenna SWIPT system realizes the secure transmission of physical layer information and the efficient harvesting of energy with its high spatial resolution and strong anti-interference characteristics.In this paper,we use the beamforming technology of large-scale antenna in SWIPT multi-user system to improve the physical layer secure transmission performance of the system while ensuring the harvesting of energy.First,the physical layer security problem of a two-dimensional channel SWIPT system corresponding to a large-scale linear array is studied.In the multi-user scene of large scale antenna,this paper analyzes the security rate of SWIPT system under imperfect channel state information.Considering channel estimation errors,this paper proposes a robust beamforming scheme,using artificial noise technology to reduce the interference.Next,we aim to maximize the system physical layer security rate under energy harvesting constraints,by adopting the improved PSO algorithm to jointly optimize the transmit beamforming vector,artificial noise covariance and power split ratio.Finally,numerical results validate the advantages of the proposed scheme in the physical layer security performance and energy harvesting.Secondly,the physical layer security of the full dimension multi user SWIPT system is studied.In multi-user downlink transmission network,deploying large scale planar antenna array in the base station,this paper analyzes the physical layer security rate of system under energy harvesting constraints by using the optimal three dimensional beamforming scheme that maximizes the ergodic rate of each user.Then,the Lagrange relaxation optimization algorithm is used to jointly optimize the base station transmitting power and the power split ratio of the receiver,while devising the optimal closed expression of the base station transmitting power and the power split ratio of the receiver,making the maximum physical layer security rate of the system.The simulation results show that the three dimensional beamforming transmission scheme can effectively improve the security performance of the physical layer of the system.