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中文核心期刊

模式耦合期望最大向量近似消息传递频域迭代均衡

Frequency domain iterative equalization combining pattern-coupled expectation-maximization with vector approximate message passing

  • 摘要: 在未知水声信道结构的条件下, 为消除接收信号的符号间干扰, 提出了一种模式耦合期望最大向量近似消息传递频域迭代接收方案。模式耦合先验假设可以自动识别水声信道的单簇或多簇信道抽头系数, 期望最大算法可以更新控制信道稀疏结构的先验信息和噪声方差。根据信道和噪声估计结果对接收信号进行线性估计, 根据来自译码器的先验信息对接收信号进行非线性估计, 并在两种估计方式之间进行外部信息传递, 挖掘待估计符号的约束增益。仿真和海试结果验证了所提方案的优势, 在非稀疏且时变的深海垂直通信海试中, 结合多普勒估计和补偿, 可实现传输距离为3832 m、速率为27.32 kbit/s的高阶调制水声通信; 在簇稀疏且信噪比低的浅海海底跨介质通信海试中, 可自动识别不同信道簇稀疏结构, 实现传输距离为4505 m、速率为3.84 kbit/s的相干水声通信。

     

    Abstract: In scenarios where the underwater acoustic channel structure is unknown, a novel iterative reception scheme, referred to as pattern-coupled expectation-maximization vector approximate message passing in the frequency domain, is proposed to eliminate inter-symbol interference in received signals. The pattern-coupled prior assumption facilitates the automatic identification of single-cluster or multi-cluster underwater acoustic channel tap coefficients. The expectation-maximization algorithm updates prior information that controls the sparse structure of the channel and the noise variance. Linear estimation of the received signal is performed based on the estimates of the channel and noise, while nonlinear estimation is conducted using prior information from the decoder. External information exchange is facilitated between the two estimation modes to exploit the constrained gains of the symbols to be estimated. The simulation and sea trial results confirm the advantages of the proposed scheme. In a non-sparse and time-varying deep-sea vertical communication experiment, the proposed method, combined with Doppler estimation and compensation, enabled high-order modulation underwater communication at a transmission distance of 3832 m with a rate of 27.32 kbit/s. In a cluster-sparse and low signal-to-noise ratio shallow-water seabed cross-medium communication experiment, the proposed method automatically identified various channel cluster-sparse structures, enabling coherent underwater communication at a transmission distance of 4505 m with a rate of 3.84 kbit/s.

     

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