时间反转技术对水声多输入多输出系统干扰抑制性能的研究

Study of the interference reducing capability of time reversal techniques in underwater acoustic MIMO systems

通过对TRM(时间反转镜)MIMO系统中码间干扰和同道干扰的分析,探讨了TRM技术在水声MIMO系统中的应用潜力。得到了一个通用的TRM MIMO系统的干扰构成表达式,对于典型的浅海水声信道,对TRM MIMO系统的干扰进行了计算;研究了TRM技术对MIMO系统自身的干扰抑制能力与收发阵形结构、信道结构以及发射信号形式等参数之间的关系。并将信干比的计算结果与室外无线信道TRM MIMO中的信干比结果进行了比较,在海底衰减系数较小的水声信道中有更丰富的多径,TRM可以获得更好的空间聚焦性,从而水声TRM MIMO信道中的信干比比室外无线信道中更大。可初步得到结论:TRM技术对水声MIMO系统干扰的抑制能力主要取决于多径的丰富程度,收、发阵元间距和时间反转的阵元数。

The intersymbol interference （ISI） and co-channel interference in a general TRM （time reversal mirror） MIMO （multiple-input-multiple-output） system was analyzed, the expression of interference was derived, and the interference reducing effects in terms of array configuration, channel, and transmitted signal were studied through an image source model in a typical shallow water channel. The computation result of signal to interference ratio was compared with the signal to interference ratio in an outdoor wireless channel, it can see that there is more rich multipath in the shallow water channel With small seabed attenuation coefficient, so the TRM can get a better spatial focusing and a better interference reduction capability. The interference reducing capability of TRM in MIMO systems is mainly decided by the richness of multipath, the element spacing and the number of TRM element.