Secrecy Performance Analysis And Improvement Of FSO Over F-distribution Turbulence Channel

Free Space Optical Communication(FSO)refers to the communication between two or more terminals using the optical carriers to transmit information in space,also known as wireless laser communication.FSO has attracted widespread attention for its advantages such as very high usable bandwidth,fast data rate,large multiplexing coefficient,security,high anti-electromagnetic interference ability,and free from the frequency band license fees.However,the laser is subject to the characteristics of line-ofsight transmission,and is easily affected by atmospheric loss,atmospheric turbulence,pointing error and other factors,which reduces the performance of the FSO communication system;at the same time,the security performance of the FSO system may also affected by eavesdropper,etc.In this paper,considering the influence of atmospheric turbulence,atmospheric loss and pointing error,a composite channel model of FSO system is constructed.The performance and security performance of the FSO system are analyzed.To improve the secrecy performance of FSO system,the artificial noise injection method is applied to the FSO security communication system,and the influence of artificial noise on the physical layer security of FSO system under different channel conditions is analyzed.The main research contents of this paper are as follows:Firstly,the basic composition and channel characteristics of the FSO system are introduced,and the generation mechanism of atmospheric turbulence,atmospheric loss and pointing error are analyzed in detail.The F-distribution model is used to simulate the atmosphere turbulence channel of FSO system,combine with the influence of atmosphere loss and pointing error,a composite channel model of the system is established.The performance index of FSO system is derived,and the influence of atmospheric turbulence,pointing error and detection mode on the performance of FSO system is simulated and analyzed.Secondly,through the F channel distribution,the secrecy communication model of FSO system is established,the security performance indicators of FSO system are derived,and the influence of atmospheric turbulence,pointing error,detection mode and system security threshold on the security performance of FSO system is simulated and analyzed.Finally,in order to improve the secrecy performance of FSO system,the FSO system transmission scheme based on artificial noise injection is constructed.The probabilistic and statistical model of FSO system under the influence of artificial noise is established.The secrecy performance of FSO system based on artificial noise injection technology is derived.The optimization of artificial noise injection technology on secrecy performance in FSO system is simulated and analyzed.It is concluded that the FSO system uses artificial noise injection technology to change the artificial noise ratio in the transmitted signal,which significantly improves the physical layer security performance of the FSO system in different channel states.