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题名	基于时间反转的浅海多用户通信
作者	张涵
学位类别	博士
答辩日期	2007-05-31
授予单位	中国科学院声学研究所
授予地点	声学研究所
关键词	多用户通信 时间反转 判决反馈均衡
其他题名	Time-reversal Multiuser Underwater Acoustics Communications in Shallow water
学位专业	信号与信息处理
中文摘要	水声通信信道具有带宽受限的特点，导致了通信速率的降低。但水声信道富含多途散射效应，它自然带宽限制和丰富的空间传播结构这使得它成为典型的多用户通信应用环境。采用多用户发射，阵接收的通信方式，有利于提高水下声通信的速率和信道容量，同时也是一项水声网络通讯的关键技术。因此，多用户通信技术成为水声通信研究领域的一大热点。 随着用户数的增加，信道性能更加复杂，引起通信性能下降的主要原因是码间干扰和信道的同道干扰。为了克服这种干扰，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，比如空间调制/空分多址(SDMA)技术，它们利用阵发射和阵接收的形式，基于复杂的空间结构分布建立起多个不同的并行传播通道，来区分各个不同用户的发送信息并进行接收处理。 近年来，时间反转技术被广泛运用于水声通信当中。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，它可以为空间位置不同的多个用户提供相互独立的通信通道，能够很好的克服用户之间的同道干扰。本论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，并进行了海上试验，初步的实现了两个不同深度上用户的同时通信。
英文摘要	The narrow bandwidth of underwater acoustic communication channels leads to the limited transmission rate. The natural bandwidth limitations of the underwater acoustic channel combined with the potential for a rich spatial propagation structure suggests the ocean is another useful application area for multi-user communication techniques. Multi-user communication with array receiver can increase both the channel capacity and transmission rate simultaneously. Besides it is the most important technique in the underwater network communications. Multi-user communication has become an active research area in underwater communications. When the number of user is a little large, communication situation becomes very complicated. The main causes of the performance degradation are the inter-symbol interference (ISI) and the co-channel interference (CI). For solving this problem, 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 by the nature properties of multipath propagation suggests that there are some other methods used for multi-user communications in shallow-water, such as spatial modulation or in other words, space-division multiple-access (SDMA). Using the user and receiver array, they built many different parallel independent communication channels based on the complicated spatial structure to differentiate the information sent by different users and then a kind of receiver structure was followed to optimize the results. Recently, time reversal (TR) approach was used to realize the multi-user communication. Time reversal (or phase conjugation) approach has good compressibility in both temporal and spatial domain, besides, its focal properties can also be taken advantage well 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 interferences. In this dissertation, based on vertical receiver array, time reversal technique was used to realize the different users’ communication in the same underwater channel simultaneously. Additionally, an adaptive decision-feedback equalizer with PLL was used to reduce the inter-symbol interference (ISI). A sea experiment was conducted to verify the related theory and the results show that the different user simultaneous communications can be realized.
语种	中文
公开日期	2011-05-07
页码	72
内容类型	学位论文
源URL	[http://159.226.59.140/handle/311008/262]
专题	声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文
推荐引用方式 GB/T 7714	张涵. 基于时间反转的浅海多用户通信[D]. 声学研究所. 中国科学院声学研究所. 2007.

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