Wireless Light Communication Link Digital Blind Equilibrium Technology And Implementation

Wireless optical communication is currently a popular direction of research during the world,which uses laser as an information carrier.It has many advantages,such as fast transmission speed,good confidentiality performance,high bandwidth,low power consumption and etc.However,laser light will always be affected by the characteristics of the atmospheric channel when transmitting in the atmospheric channel,such as atmospheric attenuation and atmospheric turbulence,which will cause the width of the pulse exhibition and inter symbol interference and then decrease the transmission performance of the wireless optical communication.This thesis focuses on the goal of improving the transmission performance of the WOC and makes the research by theoretical analysis,simulation analysis and experimental analysis,aiming to relieve or suppress the width of the pulse exhibition and inter symbol interference which caused by the atmospheric scatteringBased on the analysis of the basic theory of atmospheric laser communication and the analysis of the transmission model under turbulent channel conditions,the thesis analyzes the causes of pulse exhibition width and inter symbol interference,and the effects of link transmission performance.Because balanced technology can effectively improve the code between the signal,based on the analysis of equilibrium theory and technology,this thesis completes the design of the equilibrium scheme.Due to the poor real-time optimization performance of the MCMA(Momentum Constant Modulus Algorithm)algorithm on the signal,combined with the variable-step thinking,the thesis designs the variable-step MCMA.Considering the surplus error of the steady-state,the thesis designs the variable-step MCMA+DDLMS(Decision Directed Least Mean Square)based on dual-mode ideas.The thesis makes the simulation verification of the variable-step MCMA+DDLMS algorithm from the three aspects of the code meta-metaphysis,the remaining error of the steady-state surplus and the error rate through the Matlab simulation software The simulation results show that the variable step MCMA designed by the paper is better than the traditional MCMA,and the variable-step MCMA+DDLMS algorithm is better than the long MCMA.The thesis completes the implementation of the variable-step MCMA+DDLMS blind balance module based on the FPGA.Write the Verilog language,make the simulation test combined with Matlab,the results show that the steady-state leftover error of the signal after equilibrium is lower than-20 d B,verify the feasibility and effectiveness of the blind balanor.The thesis carries out link-level test verification work.The experimental results verify the feasibility and effectiveness of the blind balanor.