Research On Physical Layer Security Technology In Energy Harvesting Wireless Network

The large-scale use of the 5G network will lead to the rapid increase of wireless network energy consumption.The rapid growth of energy consumption not only increases the operating cost of the system but also causes pollution to the environment.At the same time,it seriously restricts the life of the energy-limited network.To extend the continuity of wireless network,it needs to change the battery or charge frequently,which leads to the design of the system is more complex,especially in some scenarios that are not possible to change the battery or change frequently.Therefore,green radio communication has attracted more and more attention.Radio frequency(RF)signals can transmit information and energy at the same time and can provide a sustainable power supply.Therefore,wireless energy-carrying communication based on RF signals can replace battery power supply to extend the network lifetime.Because the broadcast nature of wireless communication makes information easy to be stolen by eavesdropping,the security problem of the wireless network is particularly important.In recent years,how to improve the security of information transmission on the physical layer has attracted more and more scholars' attention.But generally speaking,the research on the physical layer security technology of the energy harvesting network is still in its infancy,and there are still many problems to be solved in the aspects of system design and communication security.This thesis proposes the following two solutions to the security problem in the energy harvesting wireless network.(1)For the full-duplex(FD)relay system with multiple eavesdroppingnodes,an artificial noise(AN)assisted safe beamforming method based on the simultaneous wireless information and power transfer(SWIPT)is proposed.Under the constraints of transmitting power and harvesting energy of relay nodes,the method maximizes the safety rate of the system by jointly optimizing the parameters of the beamforming matrix,AN covariance matrix,and power allocation factor.In the end,simulation results show that the proposed method significantly improves the security performance of the system.(2)On the basis of the above research results,this thesis further studies the security rate optimization problem in the case of multiple eavesdropping nodes and one energy harvesting node in the energy-limited FD relay network.An energy signal assisted security beamforming method based on SWIPT was proposed to ensure the security of energy-limited FD relay network transmitting confidential information,the multi-antenna relay transmits the energy signal(ES)to interfere with the eavesdropping nodes when amplifying and forwarding the information.Under the constraint of energy harvesting by relay and energy harvesting nodes,the rate of the system is maximized by joint optimization of energy signal,beamforming matrix and power allocation factor.The numerical simulation results verify the effectiveness of the proposed method,and the comparative experiment also shows that the proposed method further improves the security of the system.In conclusion,from the perspective of improving the security of physical layer information transmission in energy harvesting wireless network,this thesis proposes two kinds of security beamforming methods based on the joint transmission of information and energy,which improves the security performance of the system and provides a feasible and effective solution for the reliable operation of the system.The research of this thesis has certain scientific significance,academic,and application value.