基于分布式时间反转处理技术的水下节点网络物理层方案研究

时间反转处理技术可以在不需要传感器阵列结构等先验知识的条件下，在非均匀介质中实现声束的自适应聚焦，应用于水声通信时，可以减轻由多径传播所引起的码间干扰，提高通信速率。传统的时间反转技术均需要一个垂直线列阵作为时反镜，增加了节点复杂度及成本，本文所提出的基于分布式时间反转法通信的网络物理层方案，充分利用网络中多个独立节点的自身资源，组成分布式时间反转镜，在保留传统时间反转法通信优良特性的前提下，不需要再设置垂直线列阵，降低了节点复杂度及成本，兼顾了网络通信速率、节点复杂度以及信息传输保密性的需求。利用海洋环境实测数据得到的仿真试验结果表明，提出的基于分布式时反技术的水下节点网络物理层可聚焦多径信号，减轻多径传播带所引起的码间干扰，其性能与传统时反法相当，若联合判决反馈均衡器则可进一步提高系统性能。

Architecture of Physical Layer for Underwater Acoustic Network Based on Time Reversal

The application of time reversal technique in underwater acoustic communication can significantly reduce the intersymbol interference （ISI） caused by multi-path propagation, and increase the communication rate by using multi-path propagation feature in the ocean channel. However, a vertical linear array is required in the traditional time reversal communication, which results in high complexity and high power dissipation of multi-node communication networks. This paper proposes a distributed time reversal communication scheme by using the hardware resources of independent nodes of the underwater acoustic network instead of vertical linear array in traditional method. Simulation result reveals that the proposed distributed time reversal system can realize the focusing of multi-path signal, and reduce the ISI caused by multi-path propagation. Moreover, better system performance may be achieved by combining this technique with adaptive equalization.