發(fā)布時(shí)間：2018-05-28 00:29

  本文選題：多途干擾 + LS碼　； 參考：《電子科技大學(xué)》2014年碩士論文

【摘要】：在水聲通信中,由于海底、海面、以及聲速隨海水深度和海域變化的影響,水聲信號(hào)在海洋信道中的傳播受到嚴(yán)重的多途干擾,多途效應(yīng)引起的符號(hào)間干擾(ISI)嚴(yán)重地限制了信息的傳輸速率。此外,信道的環(huán)境噪聲干擾、多普勒干擾、頻率選擇性衰落,也導(dǎo)致水聲通信,尤其是遠(yuǎn)程水聲通信變得非常困難。直接序列擴(kuò)頻(DSSS)技術(shù)不僅能克服頻率選擇性衰落,抑制噪聲干擾和多途干擾,還能夠聯(lián)合RAKE接收技術(shù),有效利用多途信號(hào)。但由于以m序列、Gold碼和混沌序列為代表的有限長(zhǎng)普通擴(kuò)頻序列,它們不能獲得理想的相關(guān)函數(shù),這使得基于這些擴(kuò)頻碼的水聲DSSS信號(hào)難以完全抑制多途干擾。LS(Loosely Synchronous)碼屬于互補(bǔ)序列對(duì),在零相關(guān)窗(IFW)內(nèi)構(gòu)造出理想的相關(guān)函數(shù),因而將LS碼DSSS信號(hào)引入水聲擴(kuò)頻通信,能夠有效地抑制多途干擾,改善水聲通信質(zhì)量。本文提出將時(shí)分正交組合LS碼(LS碼)和載波相位正交組合LS碼(CLS碼)作為DSSS調(diào)制的擴(kuò)頻序列,引入水聲擴(kuò)頻通信。論文首先分析了LS碼和CLS碼的相關(guān)特性,然后以BPSK載波調(diào)制為例,給出了基于這兩種擴(kuò)頻碼,且適用于水聲通信的DSSS/BPSK信號(hào)的信號(hào)結(jié)構(gòu),調(diào)制和解調(diào)方法。其次在理論上詳細(xì)分析了這兩種信號(hào)的多途干擾抑制性能,以及解調(diào)同步偏差對(duì)多途干擾抑制性能的影響。最后將LS碼和CLS碼DSSS/BPSK信號(hào)與m序列DSSS/BPSK信號(hào)做對(duì)比,從統(tǒng)計(jì)仿真、湖試和海試數(shù)據(jù)分析的角度,論證了LS碼和CLS碼DSSS/BPSK信號(hào)在多途干擾抑制性能上的優(yōu)勢(shì)。多方面分析的結(jié)論均顯示:LS碼和CLS碼DSSS信號(hào)比m序列DSSS信號(hào)能夠具有更好的多途干擾抑制性能;RAKE接收技術(shù)能夠增強(qiáng)LS碼和CLS碼DSSS信號(hào)的多途干擾抑制優(yōu)勢(shì)。
[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.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TN929.3

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本文編號(hào)：1944466