Correlation-based decision-feedback equalizer for underwater acoustic communications
Correlation-based decision-feedback equalizer for underwater acoustic communications
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DOI：
10.1109/joe.2005.862126
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发表时间：
2005-10-01
影响因子：
4.1
通讯作者：
Yang, TC
中科院分区：
文献类型：
--
作者：
Yang, TC
本文的目的是开发一种判决反馈均衡器(DFE)，该均衡器使用一组固定的参数，在最少的用户监督下适用于大多数浅海(即交钥匙系统)。这项工作的动机是由于与被动相位共轭(PPC)等其他方法相比，多通道DFE具有更好的性能[误码率(BER)]，同时注意到其对不同声学环境的敏感性。方法是将PPC与单通道DFE结合起来，利用其对不同环境的适应性。这种耦合在理论上形成了用于水声通信的最佳处理器，但它从未在实践中实现。通过与DFE耦合，该方法实现了与传统多信道DFE相同的空间分集，而不需要像PPC那样需要大量的接收器。根据在接收信道上求和的信道冲激响应的自相关函数(Q函数)，导出了基于相关的DFE。本文从波导物理的角度，通过实际数据的进一步支持，说明了Q函数的许多令人满意的特征，这些特征表明，如果水柱有足够的采样，基于相关的均衡器对于不同的环境具有普遍的适用性，而与声速分布、底部特性和声源-接收器的范围/深度无关。可以预期这一特性对于具有空间分集的少量接收器大致成立。本文证明了这种新的均衡器在移动源数据情况下的稳健性，而不考虑由于时变的多普勒而引起的距离变化(修正了脉冲响应)和符号相位变化。
The purpose of this paper is to develop a decision-feedback equalizer (DFE) using a fixed set of parameters applicable to most shallow oceans with minimal user supervision (i.e., a turn key system). This work is motivated by the superior performance [bit error rate (BER)] of the multichannel DFE compared, with other methods, such as passive-phase conjugation (PPC), at the same time noting its sensitivity to different acoustic environments. The approach is to couple PPC, utilizing its adaptability to different environments, with a single-channel DFE. This coupling, forms an optimal processor for acoustic communications in theory, but it has never been implemented in practice. By coupling with DFE, the method achieves the same spatial diversity as conventional multichannel DFE, without requiring a large number of receivers as does PPC. The correlation-based DFE in terms of the antocorrelation functions of the channel impulse responses summed over the receiver channels (the Q function) is derived. This paper shows in terms of waveguide physics, further supported by real data, the many desirable features of the Q function that suggest, given adequate sampling of the water column, a general applicability of the correlation-based equalizer to different environments, irrespective of the sound speed profiles, bottom properties, and source-receiver ranges/depths. This property can be expected to hold approximately for a small number of receivers with spatial diversity. This paper demonstrates the robustness of the new equalizer with moving source data despite the range change (which modifies the impulse response) and symbol phase change due to time-varying Doppler.