Modeling And Performance Analysis Of Terahertz Wireless Communication System Under Atmospheric Turbulence And Pointing Error Composite Channel

As 6G work advances in various countries,terahertz communications are receiving attention from many countries as an important support technology option for 6G high rate communications.Terahertz wireless communication technology has the advantages of ultrawide bandwidth,large capacity and high-speed rate transmission,so it has a broad application prospect in high-speed communication.Terahertz beams are affected by atmospheric turbulence when transmitted through the atmosphere,resulting in a degradation of the beam quality and thus the quality of the communication.Different atmospheric turbulence models lead to different communication quality.To address this problem,this paper conducts a study of the performance of wireless terahertz communication systems under different channel models,and the experimental results provide some theoretical guidance for practical application engineering.The main work is as follows:(1)Firstly,the system model is established,and the atmospheric propagation attenuation characteristics of terahertz beam between 50 GHz and 350 GHz are simulated.Then the pointing errors and terahertz channel characteristics under different distributions are studied and analyzed.Finally,the transmission characteristics of terahertz channels are summarized,and three atmospheric turbulence models based on terahertz wireless communication systems are introduced: lognormal,Gamma-Gamma and Beaulieu-Xie.(2)Aiming at the communication requirements and application scenarios of point-to-point stationary or uniform speed short-distance wireless communication,a system framework based on subcarrier intensity modulation mode is designed for wireless terahertz communication.The log-normal(LN)and Gamma-Gamma(GG)turbulence distributions were used to simulate the changes of system performance when the system was in weak turbulence and medium to strong gas turbulence,respectively,and the fading of two composite atmospheric turbulence under atmospheric propagation attenuation was derived according to the terahertz transmission characteristics,and then the average bit error rate,outage probability and average channel capacity under the BPSK modulation of the system based on the two atmospheric turbulence were derived.Through MATLAB simulation,the curve variation law of the average bit error rate,outage probability and average channel capacity of the system based on the composite GG fading channel and the composite LN fading channel was summarized,and the influence of channel parameters such as atmospheric turbulence,propagation path and beam width on the system performance was analyzed.In special cases,the system performance of composite GG distribution and composite K distribution under the same system parameters is compared(3)In order to further enrich the atmospheric turbulence model,a new fading model,Beaulieu-Xie,is introduced,which has a flexible fading parameter that allows it to adapt to different severity of signal fading,and has both line-of-sight components and non-line-of-sight components.Then,the non-zero line-of-sight pointing error is used in the new fading model,and the second-order joint distribution of pointing error,atmospheric turbulence and atmospheric propagation attenuation is derived by using second-order statistics,and the level crossing rate and average outage duration are derived from the multi-hop case than the outage probability and average bit error rate.Finally,the MATLAB simulation is used to verify the curve variation of the level crossing rate and average outage duration of the new fading model in the communication system,and the influence of channel parameters such as attenuation parameters,line-of-sight components and non-line-of-sight components on system performance is analyzed.