浅海环境中的时间反转多用户水声通信

在无线电通信中,多用户通信可以采用时分多址(TDMA)、频分多址(FDMA)或者码分多址(CDMA)技术来实现,在水声通信中,信道的多途传播特性带来的空间差异,提供了另外的多用户通信手段。时间反转(或相位共轭)技术,能够实现对空间中指定点的聚焦接收和多途压缩,它为空间位置不同的多个用户提供了相互独立的通信通道,能够很好地克服用户之间的同道干扰(CI)。本文在垂直阵接收的基础上,利用时间反转技术来实现不同用户在同一信道中的同时通信,结合带锁相环的自适应判决反馈均衡技术来消除残余的多途码间干扰,并进行了初步的海上试验,实现了两个不同深度上用户的同时通信。

Time-reversal multi-user underwater acoustics communication in shallow water

In radio-communications,Multi-user communications can be realized by using Time Division Multiple Access(TDMA),Frequency Division Multiple Access(FDMA) or Code Division Multiple Access(CDMA).In the underwater acoustic channel,the complex spatial structure of the acoustic field resulted from multipath propagation necessitates alternative method to be used for multi-user communications in shallow-water.Time reversal(or phase conjugation) approach has good compressibility in both temporal and spatial domains;besides,its focal property can be taken advantage of to retrofocus on the source location no matter how complicated the environment is.So it provides parallel independent communication channels for the different users and reduces the co-channel interference.In this paper,based on the vertical receiver array,the time reversal technique is used to realize the different users’ communication in the same underwater channel.Additionally,an adaptive decision-feedback equalizer with Phase-Lock Loop is used to reduce the inter-symbol interference(ISI).A sea experiment was conducted to verify the related ~eory and the results show that the multi-user simultaneous communication can be realized.