水声通信中传统宽带多普勒估计方法难以准确跟踪时变多普勒因子,从而导致正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)在变速运动通信场景中补偿性能不佳。针对该问题,文章提出了一种基于空载波的多普勒估计与跟踪...水声通信中传统宽带多普勒估计方法难以准确跟踪时变多普勒因子,从而导致正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)在变速运动通信场景中补偿性能不佳。针对该问题,文章提出了一种基于空载波的多普勒估计与跟踪算法。首先对三频信号做线性调频Z变换(Chirp-Z Transform,CZT)得到多普勒先验值,然后利用OFDM符号中的空载波结合载波频偏(Carrier Frequency Offset,CFO)搜索补偿技术,把估计的最优CFO值转换为宽带多普勒因子,进而计算当前符号的加速度并预测下一符号的速度。通过更新加速度对预测值进行修正,实现每个OFDM符号的多普勒估计。数值仿真和湖试结果表明,文中算法不仅能有效跟踪多普勒的变化,在匀速和变速条件下都有较好的补偿性能,而且对帧结构设计要求低,对先验误差不敏感,有利于水声通信系统的工程实现。展开更多
The major constraint on the performance of orthogonal frequency division multiplexing （OFDM） based underwater acoustic （UWA） communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and t...The major constraint on the performance of orthogonal frequency division multiplexing （OFDM） based underwater acoustic （UWA） communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange. In practice, for mobile communication, adjustment and tuning of transducers in order to get spatial diversity is extremely difficult. Considering the relatively low coherence bandwidth in UWA, the frequency diversity design with the Doppler compensation function was elaborated here. The outfield experiments of mobile underwater acoustic communication （UWAC） based on OFDM were carried out with 0.17 bit/（s-Hz） spectral efficiency. The validity and the dependability of the scheme were also analyzed.展开更多
文摘水声通信中传统宽带多普勒估计方法难以准确跟踪时变多普勒因子,从而导致正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)在变速运动通信场景中补偿性能不佳。针对该问题,文章提出了一种基于空载波的多普勒估计与跟踪算法。首先对三频信号做线性调频Z变换(Chirp-Z Transform,CZT)得到多普勒先验值,然后利用OFDM符号中的空载波结合载波频偏(Carrier Frequency Offset,CFO)搜索补偿技术,把估计的最优CFO值转换为宽带多普勒因子,进而计算当前符号的加速度并预测下一符号的速度。通过更新加速度对预测值进行修正,实现每个OFDM符号的多普勒估计。数值仿真和湖试结果表明,文中算法不仅能有效跟踪多普勒的变化,在匀速和变速条件下都有较好的补偿性能,而且对帧结构设计要求低,对先验误差不敏感,有利于水声通信系统的工程实现。
基金Supported by the National High Technology Research and Development Program of China (2009AA093601-2)the National Defense Foundation Research (B2420110007)
文摘The major constraint on the performance of orthogonal frequency division multiplexing （OFDM） based underwater acoustic （UWA） communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange. In practice, for mobile communication, adjustment and tuning of transducers in order to get spatial diversity is extremely difficult. Considering the relatively low coherence bandwidth in UWA, the frequency diversity design with the Doppler compensation function was elaborated here. The outfield experiments of mobile underwater acoustic communication （UWAC） based on OFDM were carried out with 0.17 bit/（s-Hz） spectral efficiency. The validity and the dependability of the scheme were also analyzed.
