深海远程单阵元水声通信的逐多径簇联合均衡方法

Multipath-cluster-wise joint equalization method for long-range deep-sea single-element underwater acoustic communication

利用深海远程水声信道的稀疏多径簇具有簇间长时延、簇内结构简单的特性,提出一种用于深海远程单阵元水声通信的低复杂度逐多径簇联合均衡方法。首先,在数据帧中插入无保护间隔的m序列进行稀疏多径簇的检测和同步;然后,对选择的多径簇信号逐个进行基于比例快速后验误差技术的低复杂度均衡,并逐个对均衡器的输出根据对应多径簇的时延进行对齐;最后,将时延对齐的均衡器输出进行最大比合并,从而以并–串转换方式将逐个多径簇软解调信息合并后输入到译码器。相对于常规均衡方法,所提方法将对整体信道多径的均衡分解为对具有简单结构多径簇的逐个均衡,获得多径簇分集增益的同时结合Polar信道编码进一步改善解调性能。数值仿真和深海实验结果表明,所提方法的输出信噪比和误比特率性能明显优于单阵元及双阵元常规均衡,在30 km的通信距离中实现了通信速率为4000 bit/s的单阵元无误码通信,可有效应用于深海远程单阵元水声通信。

By exploiting the multipath characteristics of long inter-cluster time delay and simple intra-cluster structure in long-range deep-sea underwater acoustic(UWA)channels,a low-complexity multipath-cluster-wise(MCW)joint equalization method is proposed for long-range deep-sea single-element UWA communications.Firstly,an m sequence is inserted into the data frame without guard time to detect sparse multipath clusters and achieve frame synchronization.Secondly,a low-complexity sparse equalizer based on the proportionate fast a posteriori error sequential technique(PFAEST)is designed for each multipath cluster signal,soft demodulation output of which is then time delay-aligned for maximum ratio combining(MRC)combination according to the time delay of each multipath cluster.Finally,the channel decoder is adopted to further improve performance.Compared with the traditional equalization approaches,the proposed method decomposes the equalization process into several multi-path-cluster-wise joint equalizers corresponding to each multipath cluster.Multipath cluster diversity gain is exploited to enable low-complexity equalization that further incorporates Polar channel coding to enhance demodulation performance.Simulation and deep-sea experiment results show that the proposed method exhibits significantly improvement in terms of output and bit error rate compared to the single-element and two-element conventional equalization approaches.Specifically,the error-free communication performance with a data rate of 4000 bit/s at a distance of 30 km is achieved.The above results show that the proposed MCW joint equalization method is capable of being applied for long-range deep-sea single-element UWA communications.