Research On Physical Layer Security In Simultaneous Wireless Information And Power Transfer Cooperative Networks

Simultaneous wireless information and power transfer(SWIPT)technology has received much attention in the field of wireless communication because of its ability to accommodate both information and energy needs of wireless users.However,the open nature of wireless signals makes SWIPT networks vulnerable to eavesdropping,so the use of cooperative communication technology to improve the physical layer security of SWIPT networks is a hot research topic today.However,there are many problems in applying collaborative communication techniques in SWIPT networks,such as in multi-relay cooperative SWIPT networks,the use of multi-relay cooperative single-user communication brings about resource wastage and physical layer security problems due to the randomness of user and eavesdropper locations.At the same time,since physical layer security techniques are based on the statistical properties of the wireless channel to achieve secure communication,the channel estimation errors due to the non-cooperative nature of eavesdroppers and the lead time synchronization and signal delay in real scenarios can seriously affect the secrecy performance that can be achieved by physical layer security algorithms.In addition,in the intelligent reflecting surface(IRS)cooperative SWIPT network,the relay cooperative interference algorithm used in traditional relay networks is no longer applicable due to the passive property of IRS,and the artificial noise(AN)signal transmitted by external devices will simultaneously reduce the signal to interference plus noise ratio of the received signal by the user,which makes it more difficult to decode by the legitimate user and leads to the reduction of the physical layer security of the network.In the above context,this paper proposes secure communication algorithms applicable in SWIPT networks based on various cooperative communication techniques,with the following main contributions.1.A secure beamforming algorithm based on relay selection is proposed for energy efficiency and information security in multi-relay cooperative SWIPT networks to achieve secure communication with minimum network resource cost by jointly optimizing the optimal relay selection and relay beamforming vectors under relay energy harvesting constraints.The multivariate coupling as well as the integer constraint form in the above problem leads to its non-convex and difficult solution.We solve it jointly by decomposing it into the optimal relay selection subproblem and the optimal relay beam formation subproblem.For the optimal relay beamforming subproblem,we solve it efficiently using algorithms such as semi-positive definite relaxation and Charnes-Cooper transform.Once the optimal solution of the optimal relay beamforming subproblem is obtained,the optimal relay selection subproblem can be solved by a onedimensional search algorithm.A large number of simulation results are provided to demonstrate that our proposed algorithm can effectively improve the energy efficiency and PLS in multi-relay networks.2.Motivated by the scenario of channel disturbance,we model the channel disturbance between relay and eavesdropper dynamically by elliptic model and propose a secure beamforming algorithm based on Sprocedure under the relay energy harvesting constraint,which effectively solves the performance degradation of the conventional algorithm under channel disturbance.Since the problem has multivariate coupling,we transform it into a joint solution of the upper and lower level problems by introducing relaxation variables,and propose an iterative algorithm based on semi-positive definite relaxation,S-procedure and bisection algorithms to obtain the optimal solution of the original problem.We also present extensive numerical simulation results to demonstrate that our proposed algorithm can effectively improve the PLS of relayed cooperative SWIPT networks.3.Addressing the problem of unsuitable traditional relay cooperative interference algorithm and PLS in IRS-assisted SWIPT networks,we propose a secure beamforming algorithm based on full-duplex user cooperative jamming,which jointly optimizes the AP transmit beamformer,IRS phase shift matrix and user artificial noise power under IRS phase shift constraint and AP transmit power constraint to achieve secure physical layer communication in IRS-assisted SWIPT networks.As the three variables in the above problem are coupled and non-convex constrained,we propose an efficient iterative algorithm to solve the original problem jointly by decomposing it into three sub-problems based on alternating optimization.Experimental results show that our proposed algorithm can effectively improve the PLS of wireless energy-carrying networks with IRS-assisted.