This paper proposes a novel non-orthogonal pilot pattern design method for underwater acoustic (UWA) multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems, leveraging compressive sensing (CS) channel estimation. This approach adopts the mutual incoherence property (MIP) and enhances pilot density without increasing pilot overhead. We conducted rigorous mathematical derivation to generate the explicit formula for the non-orthogonal pilot pattern with the mutual coherence of zero. In addition, we estimate multipath delay and amplitude by employing parallel orthogonal matching pursuit (OMP) channel estimation. The co-channel interference (CCI) is eliminated from the systems with the proposed non-orthogonal pilot pattern to estimate the channel coefficients from two transmitters without interference in a single iteration. Simulations and lake trial results demonstrate the superior performance of the proposed non-orthogonal pilot pattern over the orthogonal and existing non-orthogonal pilot patterns in terms of normalized mean square error (NMSE) of channel estimation and bit error rate (BER). The UWA MIMO-OFDM system achieves a data rate of 78.11 kbps with a BER of 1.42×10 in the lake trial over the communication distance of 773 m.

中文翻译：

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水声MIMO-OFDM系统的非正交导频模式设计和稀疏信道估计

本文提出了一种利用压缩感知（CS）信道估计的水声（UWA）多输入多输出正交频分复用（MIMO-OFDM）系统的新型非正交导频模式设计方法。该方法采用互不相干特性(MIP)，在不增加导频开销的情况下提高导频密度。我们进行了严格的数学推导，生成了相互相干性为零的非正交导频模式的显式公式。此外，我们通过采用并行正交匹配追踪（OMP）信道估计来估计多径延迟和幅度。使用所提出的非正交导频模式从系统中消除了同信道干扰（CCI），以在单次迭代中无干扰地估计来自两个发射机的信道系数。仿真和湖泊试验结果表明，在信道估计的归一化均方误差（NMSE）和误码率（BER）方面，所提出的非正交导频模式相对于正交和现有非正交导频模式具有优越的性能。 UWA MIMO-OFDM系统在湖泊试验中在773 m的通信距离上实现了78.11 kbps的数据速率和1.42×10的BER。