Research On Multipath Measurement And Data Analysis Algorithms Of Maritime Radio Channels

In recent years,with the increasing maritime activities,it is indispensable to establish a safe and reliable radio communication network in the relevant sea area.On the basis of channel measurement,achieving the optimal estimation of the state of maritime radio channels is of great significance for improving the quality of maritime radio communication services and ensuring the safety of ship navigation.Based on the spread spectrum correlation detection method,this subject designed a multipath measurement.system for maritime radio channels,and proposed a multipath identification algorithm based on Dempster-Shafer(D-S)evidence theory.According to the requirements of multipath measurement of maritime radio channels,this subject established a multipath measurement scheme based on linear frequency modulation(Chirp)waveform by analyzing the advantages and disadvantages of typical radio channel measurement methods.The multipath detection algorithm based on Channel Impulse Response(CIR)and Fractional Fourier Transform(FRFT)were mainly studied.Through simulation analysis,the effectiveness of the two algorithms was verified.Based on the comprehensive consideration of multipath recognition accuracy and time complexity,the data processing algorithm adopted was determined.By analyzing the influence of factors such as signal bandwidth,sampling frequency,sampling duration,phase difference and other factors on the accuracy of the multipath detection algorithm,it provides a theoretical basis for setting the corresponding parameters in the measurement system.Based on the results of theoretical research,this paper proposed a channel measurement system suitable for maritime radio communication.This system combined the transmission characteristics of maritime signals and the fading characteristics of maritime radio channels,set Chirp signals as sample signals,and designed detailed channel measurement process.In order to verify the feasibility of the system,this paper built an actual maritime radio channel multipath measurement system in the Lingshui Bay of Dalian to conduct related static and dynamic tests,and collected a large amount of measured data under real environment.Through the algorithm analysis of the measured data,the results show that within a limited time range,the multipath transmission environment of the maritime radio channel is reproducible.Based on the conclusion that the maritime radio channel obtained from the above measured data analysis has short-term stability,this subject proposed a new radio channel multipath identification algorithm based on D-S evidence theory,which is used to analyze and extract weak high-order multipath signals.The algorithm built a basic probability assignment function model of signal and noise based on the statistical characteristics of the CIR analysis results,and used the evidence weight calculation method to fuse evidence from multiple measurement results,and then obtained the final decision result in the evidence decision process.Throtigh comparison of measured data analysis and algorithm simulation results,it is found that the proposed algorithm can improve the recognition ability of weak multipath signals and obtain more accurate multipath signal judgment results.