| At present, with the growing demand for global roaming and high-speed broadband, mobile satellite communication system combined with OFDM transmission technology has great advantages. Broadband mobile satellite channel has multipath effects, Doppler shift, shadowing etc., which has; serious effect on reliability and efficiency of signal transmission. In order to carry out the correct data demodulation, the receiver has to accurately estimate the channel information. Therefore, for the purpose of efficient transmission of mobile satellite communication, this paper focuses on study of channel estimation and related technologies for OFDM-based broadband mobile satellite communication system. The main work includes the following aspects.Firstly, the transmission characteristics and statistical properties of mobile satellite channel are analyzed to simulate the frequency-selective broadband mobile satellite channel model by using the tapped delay line structure. Secondly, the basic principle of OFDM technology is summarized to establish an OFDM-based satellite mobile communication system frame. Thirdly, it focuses on the system established above and discusses several classical pilot-based channel estimation methods both on the basis of theoretical analysis and simulation experiments. Fourthly, an improved power judgement-based LS algorithm named PLS and a PLS with zero padding interpolation algorithm named PLS_ZP were proposed in order to improve the transmission performance of traditional channel estimation algorithm. Based on DFT estimation algorithm, PLS algorithm utilized the fading characteristics of broadband mobile satellite channel, got the power threshold by limiting the number of the effective taps and removed the noise outside the taps effectively. Finally, it focuses on the fast time-varing mobile satellite channel estimation on lack of quasi-static channel assumption of traditional algorithms, which improve the performance of mobile satellite communication systems overall. |
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