本文關(guān)鍵詞： 水聲通信 OFDM 信道估計 均衡器　出處：《電子科技大學》2014年碩士論文　論文類型：學位論文

【摘要】：隨著人們對海洋的開發(fā)和利用,水下通信成為人們在民用及軍事活動中必不可少的一項技術(shù)。不同于空氣等無線電傳播介質(zhì),海洋及湖泊環(huán)境中,聲波是目前唯一可以有效進行遠距離傳播的媒介,而OFDM技術(shù)可以有效適應(yīng)水聲信道多途干擾強、可利用帶寬少的特點。然而為了盡可能地提高水聲通信的性能,增強對頻率選擇性衰落的抵抗、避免碼間干擾,還必須設(shè)計良好的信道估計及均衡器。本文在通用的OFDM水聲通信系統(tǒng)模型的基礎(chǔ)上,對信道估計器和均衡器的算法及結(jié)構(gòu)進行了研究,結(jié)合不同的信道環(huán)境通過仿真對比不同算法結(jié)構(gòu)下接收機的性能。以此為基礎(chǔ),在考慮FPGA硬件資源的前提下設(shè)計出可以在硬件平臺上工作并具有較好效果的接收機均衡器,主要完成的工作包括:簡單介紹了OFDM水聲通信系統(tǒng)的基本原理及發(fā)展現(xiàn)狀,對目前國內(nèi)外在信道估計及均衡方面的研究現(xiàn)狀做了闡述和概括;分析了OFDM技術(shù)在水聲通信中的優(yōu)勢以及信道估計和均衡對于提高水聲通信性能的重要性;結(jié)合水聲信道的特點,針對其可利用帶寬窄、多途干擾大、頻率選擇性衰弱強的特點,研究了信道估計及均衡算法的原理,歸納了常用算法的優(yōu)點和缺陷,提出了適用于本OFDM水聲通信系統(tǒng)的信道估計器及均衡器的幾種算法和結(jié)構(gòu)作為重點研究對象。在Matlab中建立OFDM水聲通信系統(tǒng)接收機的整體模型,并在其中加入信道估計及均衡模塊,通過調(diào)整信道參數(shù)模擬不同的信道環(huán)境,將不同的算法及其經(jīng)過改良后的設(shè)計通過Matlab進行仿真,通過對比不同信噪比下的誤碼率提出最終適合在FPGA硬件系統(tǒng)上進行實現(xiàn)的算法。根據(jù)仿真結(jié)果,設(shè)計了可以在FPGA平臺上實現(xiàn)的均衡器以及相應(yīng)的信道估計和均衡算法,并將其加入接收機系統(tǒng)進行聯(lián)調(diào)。通過分析硬件資源使用情況驗證計算復(fù)雜度。開發(fā)了FPGA與上位機PC之間的數(shù)據(jù)緩沖器以便于進行實驗和應(yīng)用。最后將設(shè)計好的均衡器連同發(fā)射機接收機一起進行水桶及淺水實驗,并利用水聲發(fā)生陣列進行普通情況的水聲傳輸及定向傳輸,驗證了所設(shè)計的解決方案確實可以有效對抗多徑干擾及頻率選擇性衰落,保證良好的誤碼率。通過均衡器的加入,可以顯著改善水聲通信系統(tǒng)抵抗碼間干擾的表現(xiàn),在25dB信噪比環(huán)境下,誤碼率達到10-3以下,而FPGA平臺上的實現(xiàn)也增加了本均衡器的實際應(yīng)用價值。
[Abstract]:With the development and utilization of the ocean, underwater communication has become an indispensable technology in civil and military activities. At present, acoustic wave is the only medium that can effectively propagate over long distance, and OFDM technology can effectively adapt to the strong multi-path interference in underwater acoustic channel. However, in order to improve the performance of underwater acoustic communication as much as possible, enhance the resistance to frequency selective fading and avoid inter-symbol interference. It is also necessary to design a good channel estimator and equalizer. Based on the general model of OFDM underwater acoustic communication system, the algorithm and structure of channel estimator and equalizer are studied in this paper. Combined with different channel environment, the performance of receiver under different algorithm structure is compared by simulation. Based on the consideration of FPGA hardware resources, a receiver equalizer which can work on the hardware platform and has a better effect is designed. The main works are as follows: the basic principle and development status of OFDM underwater acoustic communication system are briefly introduced, and the current research status of channel estimation and equalization at home and abroad is described and summarized. The advantages of OFDM technology in underwater acoustic communication and the importance of channel estimation and equalization in improving the performance of underwater acoustic communication are analyzed. According to the characteristics of underwater acoustic channel, the principle of channel estimation and equalization algorithm is studied, and the advantages and disadvantages of common algorithms are summarized. Several algorithms and structures of channel estimator and equalizer suitable for this OFDM underwater acoustic communication system are proposed as the main research objects. The whole receiver of OFDM underwater acoustic communication system is established in Matlab. Model. The channel estimation and equalization module is added to simulate the different channel environment by adjusting the channel parameters. The different algorithms and their improved design are simulated by Matlab. By comparing the bit error rate under different SNR, the algorithm which is suitable for FPGA hardware system is put forward, and the simulation results are given. The equalizer and the corresponding channel estimation and equalization algorithm are designed on FPGA platform. The data buffer between FPGA and PC is developed to facilitate the experiment and application. Finally, by analyzing the use of hardware resources to verify the computational complexity, a data buffer between FPGA and PC is developed to facilitate the experiment and application. The designed equalizer and transmitter receiver are used for bucket and shallow water experiments. The underwater acoustic transmission and directional transmission are carried out by using underwater acoustic array, which proves that the proposed solution can effectively resist multipath interference and frequency selective fading. With the addition of equalizer, the performance of ISI resistance in underwater acoustic communication system can be significantly improved. Under 25dB SNR, the BER is below 10 ~ (-3). The realization of FPGA platform also increases the practical application value of this equalizer.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN929.3

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本文編號：1458099