Li Dong, Wu Yanbo, Zhu Min, Tao Jun
Ocean Acoustic Technology Center, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
Key Laboratory of Underwater Acoustic Signal Processing of the Ministry of Education, School of Information Science and Engineering, Southeast University, Nanjing 210096, China.
J Acoust Soc Am. 2021 Mar;149(3):1549. doi: 10.1121/10.0003625.
Vertical underwater acoustic (UWA) communications play a crucial role in deep-sea applications. A vertical UWA channel generally features a moderate multipath but with time-varying Doppler shifts as well as loud impulsive noise. To achieve a robust vertical single-carrier UWA communication, this paper proposes an enhanced iterative receiver. First, a spline interpolation-based timing estimation approach is proposed to compensate for the time-varying Doppler effects efficiently. Then, the residual timing errors and the multipath interference are tackled by a fractionally spaced self-iterative soft equalizer (SISE) based on the vector approximate message passing (VAMP) algorithm. The VAMP-SISE consists of four parts: an inner soft slicer and an inner soft equalizer for symbol detection as well as a denoiser and a minimum mean-squared error estimator for impulsive noise suppression. Different parts iteratively exchange extrinsic information to improve the equalization performance. Last, a channel-fitting irregular convolutional code and a unity-rate code are employed at the transmitter to lower the signal-to-noise ratio threshold for reliable communications. Deep-sea experiments verify the performance superiority of the proposed receiver over existing schemes.
垂直水下声学（UWA）通信在深海应用中起着至关重要的作用。垂直UWA信道通常具有适度的多径，但也存在时变多普勒频移以及强烈的脉冲噪声。为了实现稳健的垂直单载波UWA通信，本文提出了一种增强型迭代接收机。首先，提出了一种基于样条插值的定时估计方法，以有效补偿时变多普勒效应。然后，基于矢量近似消息传递（VAMP）算法的分数间隔自迭代软均衡器（SISE）来处理残留定时误差和多径干扰。VAMP-SISE由四部分组成：一个内部软限幅器和一个用于符号检测的内部软均衡器，以及一个去噪器和一个用于脉冲噪声抑制的最小均方误差估计器。不同部分迭代地交换外部信息以提高均衡性能。最后，在发射机处采用信道拟合不规则卷积码和单位速率码，以降低可靠通信的信噪比阈值。深海实验验证了所提出接收机相对于现有方案的性能优越性。
