Performance Analysis Of Free-space Optical Communication System

Free Space Optical Communication(FSO)is an communication technology that transmits data wirelessly in free space using light.FSO communication technology not only has abundant spectrum and provides super-large capacity services,but also has the unique advantages of anti-electromagnetic interference,mutual interference and confidentiality,which makes it a hot research topic in the world.However,the development of FSO communication technology is constrained by the diversity of atmospheric channels,such as fog,snow and atmospheric turbulence caused by atmospheric motion.Based on the theory of FSO channel,this paper aims to establish and improve the stability and main technical indicators detection system of wireless optical signal transmission in atmospheric channel.The research content of this paper is mainly divided into the following three parts:(1)Aiming at the existing modulation technology,the performance of FSO communication system is studied in detail by combining simulation with experiment.In the simulation part,Gamma-Gamma(GG)channel suitable for weak,moderate and strong turbulent environment is selected as the communication link of FSO system.On-off keying(OOK),binary phase shift keying(BPSK)and differential phase shift keying(DPSK)channel modes of different modulation technologies are established.In the experimental part,the Log-normal(LN)model,which is the easiest to implement and suitable for weak turbulence,is selected.Based on this model,a complete FSO communication system is built.The BER performance of OOK and BPSK modulation technologies is further demonstrated from the experimental point of view.(2)For the first time,a real-time data acquisition system is built by combining Labview with FSO technology.Unlike the previous offline acquisition system,the system can realize waveform storage,waveform display and spectrum analysis.In a real sense,it can achieve data acquisition and processing while greatly reducing errors caused by human operation.(3)WDM technology is applied to FSO communication system.The high-speed communication of FSO is studied theoretically,and the communication capacity and speed of FSO communication system are improved.As WDM technology increases the communication capacity,it will lead to the non-linear effect caused by cross-channel interference,thus inhibiting the performance of the communication system.Therefore,introduce PI technology,which can not only effectively reduce the non-linear effect between adjacent channels,but also improve the communication capacity and speed of FSO communication system.