Research On Secure Communication And Energy Efficiency Of Multi-antenna System Based On SWIPT

Simultaneous wireless information and power transfer(SWIPT)technology is a new green communication technology in recent years,which can fully tap the energy hidden in RF signals.Without affecting the users' normal decoding information,the technology can effectively convert the RF signal into DC power and supply power to the energy-limited equipment,which has become one of the hot research directions.However,the scarcity of spectrum resources and the existence of channel fading limit the development of simultaneous wireless information and power transfer technology.In addition,users' privacy information is also easy to be stolen by eavesdroppers because of the broadcast characteristics of wireless channels,so ensuring information security has become one of the challenges faced by simultaneous wireless information and power transfer technology.In recent years,the rapid development of multi-antenna technology and physical layer security technology has provided a new solution for simultaneous wireless information and power transfer technology to overcome the above difficulties.Based on this,it becomes very meaningful to study the physical layer security on SWIPT multi-antenna networks.This paper focuses on SWIPT MISO and MIMO networks,and proposes resource allocation algorithm to maximize energy efficiency under the premise of ensuring information security transmission.The specific research contents of this paper are mainly divided into the following parts:(1)In the downlink SWIPT MISO broadcast network,the problem of maximizing energy efficiency for multiple users is investigated.Due to the existence of eavesdropping users,anti-theft mechanism is introduced to ensure the information security of authorized users.At the energy harvesting level,in order to prevent the problem of insufficient energy supply and low energy conversion efficiency of authorized users,a new EH model is introduced.Based on this model,an iterative optimization method based on successive convex approximation algorithm is established to obtain the minimum transmission power needed to meet the needs of user energy harvest.On this basis,the energy efficiency maximization problem is established by jointly optimizing the precoding matrix,the artificial auxiliary noise covariance matrix and the power splitting factor.Due to the non-convexity of the optimizationproblem,this paper uses the first-order Taylor series expansion method and semi-determining programming to resolve the problem in a solvable form,and designs a two-level iterative algorithm based on Dinkelbach.Simulation experiments verify the validity and reliability of the proposed algorithm.(2)Global security energy efficiency maximization is studied in the downlink SWIPT MIMO communication network.In this paper,the information security transmission mechanism is introduced into the objective function to make it more intuitively reflect the network security performance and resource utilization.Because of the non-convexity of the original optimization problem,the fractional programming problem is first transformed into subtraction equivalent form,and then some non-convex constraints are transformed by the first order Taylor technique expansion method.According to the transformed problem structure,a two-level iterative optimization algorithm is designed.Then,for the constraint conditions containing the radius of the uncertainty region of the eavesdropping channel,this paper uses the linear matrix inequality theory and the S-procedure for its equivalent transformation.The simulation experiment finally proves the effectiveness and reliability of the proposed algorithm,which can achieve the best global secrecy energy efficiency compared with other baseline algorithms.