Research On Filtered Multi-tone And Frequency Synchronization Technology In VDE-TER

The Maritime VHF Data Exchange System(VDES)will be a basic method of data exchange in the e-Navigation strategy,which has been developed by the International Maritime Organization(IMO).The International Telecommunication Union(ITU)is in the process of developing formal VDES technical standards and plans to publish them in 2020-2021.VDES provides three kinds of communication services:AIS,ASM and VDE.VDE channels include VDE-terrestrial and VDE-satellite.Based on VDE-TER channel,this paper focuses on filtered multitone modulation and carrier frequency offset algorithm in VDE-TER.Firstly,this paper studied the architecture of VDES,focusing on the technical characteristics of VDE-TER channel,and builds VDE-TER simulation platform based on MATLAB and software defined radio.In this platform,the basic theory of filtered multi-tone(FMT)is studied,the thesis systematically analyzed the effects of the roll-off factor and filter order on communication performance in FMT modulation;the thesis simulated the influence curve of the roll-off factor and filter order with regard to the communication quality in VDE-TER FMT modulation;moreover,the thesis performed an experiment using a software-defined radio platform in a real-world scenario.Based on the simulated and real-world results,the thesis recommend performance specifications for the roll-off factor and filter order for FMT modulation in the VDES.The paper studies the carrier frequency synchronization technology of VDE-TER communication and ITU-R P.1546-3 marine prediction model.The frequency offset estimation performances of the double Barker code frequency offset estimation algorithm,Fitz algorithm,L&R algorithm and M&M algorithms in gauss channel,maritime channel,rayleigh channel and Rician channel are analyzed and compared.The influence of the length of the Barker code on the estimation performance in the frequency offset estimation algorithm of the double Barker code is verified.In addition,software-defined radio is used to verify the results in real scenarios.The results show that the frequency offset estimation algorithm of double Barker codes has the best estimation performance.