Research On Key Technologies Of Physical Layer Security In Energy-harvesting Multiuser Networks

In recent years,the rapid rise of wireless communication has led to innovation of network architecture.The increase in the number of device interfaces,the types of mobile phone applications,and the network speed have significantly increased the power consumption of the terminal.However,the size design of mobile devices restricts battery capacity,so how to provide sufficient power for mobile devices has become one of the hotspots,and simultaneous wireless information and power transfer(SWIPT)has emerged.In addition,the wireless communication technology not only brings convenience to life,but also brings transmission security issues.Physical layer security technology has attracted the attention of academia as a supplement to network layer encryption.On this basis,this thesis studies the physical layer security issues in energy harvesting multi-user networks.The main research contents and innovations are as follows:Firstly,this thesis considers energy harvesting multiuser network with an eavesdropping node.In this scenario,this thesis proposes an optimal user scheduling(OUS)scheme,uses outage probability and intercept probability as indicators to measure the reliability and security of the communication transmission,compared with the traditional round-robin scheduling(RRS)scheme,and derives closed-form expressions of outage probability and intercept probability of OUS and RRS scheme.The simulation results show that the security-reliability tradeoff of the proposed OUS scheme is significantly better than the RRS scheme.Secondly,this thesis studies physical layer security enhancement of the energy harvesting networks in multiuser communication scenario,combining multiuser scheduling with friendly jammer selection methods to improve the security performance.This thesis proposes optimal user random jammer(OU-RJ)scheme and random user optimal jammer(RU-OJ)scheme,then derives closed-form expressions of intercept probability for the two schemes in the Rayleigh fading channel.The simulation results show that with the increase of the number of users,signal-to-noise ratio and energy conversion efficiency,the intercept probability of the two schemes are reduced,and the intercept probability of OU-RJ scheme decreases faster than that of RU-OJ scheme,which shows superiority of OU-RJ scheme in terms of security performance.Finally,the physical layer security optimization problem of energy harvesting multiuser networks is studied,an optimal time splitting(OTS)scheme based on minimizing the intercept probability is proposed,and equal time splitting(ETS)scheme is also proposed as a comparison.The closed expressions of intercept probability of the two schemes are derived.This thesis uses the golden ratio method to obtain the optimal time allocation factor to reduce the intercept probability and improve the security performance of the communication system.The simulation results show that the OTS scheme can make energy more reasonable in the system,significantly reduce the intercept probability and achieve the best transmission security.