基于LS码的水声直接序列扩频通信研究

发布时间：2018-05-28 00:29

本文选题：多途干扰 + LS码　；参考：《电子科技大学》2014年硕士论文

【摘要】：在水声通信中,由于海底、海面、以及声速随海水深度和海域变化的影响,水声信号在海洋信道中的传播受到严重的多途干扰,多途效应引起的符号间干扰(ISI)严重地限制了信息的传输速率。此外,信道的环境噪声干扰、多普勒干扰、频率选择性衰落,也导致水声通信,尤其是远程水声通信变得非常困难。直接序列扩频(DSSS)技术不仅能克服频率选择性衰落,抑制噪声干扰和多途干扰,还能够联合RAKE接收技术,有效利用多途信号。但由于以m序列、Gold码和混沌序列为代表的有限长普通扩频序列,它们不能获得理想的相关函数,这使得基于这些扩频码的水声DSSS信号难以完全抑制多途干扰。LS(Loosely Synchronous)码属于互补序列对,在零相关窗(IFW)内构造出理想的相关函数,因而将LS码DSSS信号引入水声扩频通信,能够有效地抑制多途干扰,改善水声通信质量。本文提出将时分正交组合LS码(LS码)和载波相位正交组合LS码(CLS码)作为DSSS调制的扩频序列,引入水声扩频通信。论文首先分析了LS码和CLS码的相关特性,然后以BPSK载波调制为例,给出了基于这两种扩频码,且适用于水声通信的DSSS/BPSK信号的信号结构,调制和解调方法。其次在理论上详细分析了这两种信号的多途干扰抑制性能,以及解调同步偏差对多途干扰抑制性能的影响。最后将LS码和CLS码DSSS/BPSK信号与m序列DSSS/BPSK信号做对比,从统计仿真、湖试和海试数据分析的角度,论证了LS码和CLS码DSSS/BPSK信号在多途干扰抑制性能上的优势。多方面分析的结论均显示:LS码和CLS码DSSS信号比m序列DSSS信号能够具有更好的多途干扰抑制性能;RAKE接收技术能够增强LS码和CLS码DSSS信号的多途干扰抑制优势。
[Abstract]:In underwater acoustic communication, the propagation of underwater acoustic signals in the ocean channel is seriously multipath due to the influence of the depth of sea water and the change of sea area. The inter symbol interference (ISI) caused by the multipath effect seriously restricts the transmission rate of information. In addition, the environmental noise interference of the channel, Doppler interference, frequency selection. Selective fading also leads to underwater acoustic communication, especially long range underwater acoustic communication, which is very difficult. Direct sequence spread spectrum (DSSS) technology can not only overcome frequency selective fading, suppress noise interference and multipath interference, but also combine RAKE receiving technology to effectively use multipath signals. But because of the limited number of M sequences, Gold codes and chaotic sequences Long ordinary spread spectrum sequences, they can not obtain the ideal correlation function, which makes the underwater acoustic DSSS signal based on these spread spectrum codes difficult to completely restrain the multipath interference.LS (Loosely Synchronous) code to belong to the complementary sequence pair, construct the ideal correlation function in the zero correlation window (IFW), so the LS code DSSS signal is introduced into the underwater acoustic spread spectrum communication. In this paper, a spread spectrum sequence of time division orthogonal combinatorial LS code (LS code) and carrier phase orthogonal combination LS code (CLS code) is used as DSSS modulated spread spectrum sequence, which is introduced in this paper. The paper first analyzes the correlation between LS code and CLS code, and then takes BPSK carrier modulation as an example, and gives the two based on this two It is suitable for the signal structure, modulation and demodulation of DSSS/BPSK signals in underwater acoustic communication. Secondly, the multipath interference suppression performance of these two signals is analyzed in detail, and the influence of demodulation synchronization deviation on the performance of multipath interference suppression is analyzed. Finally, the LS code and the CLS code DSSS/BPSK signal are made with the m sequence DSSS/BPSK signal. From the point of view of statistical simulation, lake test and sea test data analysis, the advantages of LS code and CLS code DSSS/BPSK signal in multipath interference suppression are demonstrated. The conclusion of multiaspect analysis shows that LS and CLS code DSSS signals can have better multipath interference suppression performance than m DSSS signals; RAKE reception technology can enhance LS code and CLS. The multipath interference suppression advantage of the code DSSS signal.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.3

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