寬帶水聲信道參數(shù)估計(jì)及應(yīng)用
發(fā)布時(shí)間：2018-10-20 09:26
【摘要】：從上世紀(jì)90年代至今,由于經(jīng)濟(jì)社會(huì)發(fā)展和國(guó)防安全的需求,水聲科學(xué)技術(shù)的研究受到了世界各國(guó)的關(guān)注,并取得了突飛猛進(jìn)的發(fā)展。相比陸地?zé)o線信道,水聲信道具有其特殊性和復(fù)雜性,表現(xiàn)在其嚴(yán)重的多途效應(yīng)、時(shí)變特性以及帶限特性等方面。近年來(lái)持續(xù)發(fā)展的水聲相干通信在提高頻帶利用率和信息傳輸速率上,較非相干通信有著較明顯的優(yōu)勢(shì),但同時(shí)對(duì)水聲信道的參數(shù)估計(jì)有著越來(lái)越高的要求。從信號(hào)處理角度上講,信道估計(jì)的精度與效率直接影響著整個(gè)水聲通信系統(tǒng)的性能,因此該問(wèn)題一直以來(lái)都是水聲領(lǐng)域研究的重中之重。本文從水聲信道的物理特性出發(fā),抓住其寬帶本質(zhì),對(duì)具有多尺度多時(shí)延特性的水聲信道參數(shù)估計(jì)問(wèn)題,及其在水聲通信上的應(yīng)用展開(kāi)了深入研究,在以下幾個(gè)方面具有創(chuàng)新性成果:1)結(jié)合對(duì)射線理論和水聲Doppler效應(yīng)的分析,系統(tǒng)地描述了寬帶水聲信道模型的多尺度多時(shí)延特性。對(duì)于不滿足窄帶近似條件的信道,以Doppler尺度因子來(lái)描述寬帶Doppler效應(yīng),接收信號(hào)表示為發(fā)送信號(hào)多個(gè)時(shí)延-尺度副本按照寬帶擴(kuò)散函數(shù)的加權(quán)疊加。通過(guò)對(duì)BELLHOP建模工具和Vir TEX算法加以修正和改進(jìn),模擬出平靜海面以及正弦起伏海面情況下具有多尺度多時(shí)延特性的信道。2)研究了現(xiàn)有的基于寬帶相關(guān)處理的信道估計(jì)方法,在此基礎(chǔ)上,采用一種基準(zhǔn)尺度為有理數(shù)的小波作為信道探針信號(hào),提出了寬帶解卷積信道估計(jì)方法和匹配追蹤信道估計(jì)方法的離散數(shù)值算法。仿真實(shí)驗(yàn)表明,當(dāng)信道具有充分稀疏性時(shí),兩種方法均能夠獲得較理想的寬帶擴(kuò)散函數(shù)估計(jì)。3)利用線性調(diào)頻信號(hào)在時(shí)域和分?jǐn)?shù)階Fourier變換域的脈沖壓縮特性,提出了一種基于分?jǐn)?shù)階Fourier變換的多尺度多時(shí)延水聲信道參數(shù)估計(jì)方法。該方法能夠以迭代的方式對(duì)多分量線性調(diào)頻信號(hào)按照能量大小順序進(jìn)行分離,在每次迭代中,通過(guò)一個(gè)可以校正最佳變換階數(shù)的子迭代過(guò)程來(lái)獲得尺度、時(shí)延等參數(shù)的精確估計(jì)。仿真實(shí)驗(yàn)表明,該方法對(duì)寬帶擴(kuò)散函數(shù)的估計(jì)誤差明顯優(yōu)于現(xiàn)有的其它方法。4)針對(duì)多尺度多時(shí)延水聲信道,提出一種雙曲調(diào)頻-擴(kuò)頻通信方案。通信幀以線性調(diào)頻信號(hào)作為幀頭,用于信道估計(jì),并采用一系列雙曲調(diào)頻信號(hào)對(duì)數(shù)據(jù)進(jìn)行擴(kuò)頻調(diào)制。接收機(jī)具有極其簡(jiǎn)單的系統(tǒng)結(jié)構(gòu),可直接利用信道參數(shù)估計(jì)結(jié)果將收發(fā)信號(hào)的相關(guān)輸出分成多條支路進(jìn)行分集處理,通過(guò)一定的合并技術(shù)可以獲得多徑-尺度分集增益。此外,容易將單帶傳輸系統(tǒng)擴(kuò)展到多帶傳輸,仿真結(jié)果證實(shí)了該方案的有效性。
[Abstract]:Since 1990s, due to the demand of economic and social development and national defense security, the research of underwater acoustic science and technology has been paid attention to by many countries all over the world, and has made great progress. Compared with terrestrial wireless channel, underwater acoustic channel has its particularity and complexity, which is manifested in its serious multipath effect, time-varying characteristic and band-limit characteristic. In recent years, the continuous development of underwater acoustic coherent communication has obvious advantages over non-coherent communication in improving the efficiency of frequency band and the rate of information transmission, but at the same time, the parameter estimation of underwater acoustic channel is required more and more. From the point of view of signal processing, the accuracy and efficiency of channel estimation directly affect the performance of the whole underwater acoustic communication system, so this problem has always been a top priority in the field of underwater acoustic research. Based on the physical characteristics of underwater acoustic channel and its wideband nature, the parameter estimation problem of underwater acoustic channel with multi-scale and multi-delay characteristics and its application in underwater acoustic communication are studied in this paper. The main contributions are as follows: 1) combining the analysis of ray theory and underwater acoustic Doppler effect, the multi-scale and multi-delay characteristics of broadband underwater acoustic channel model are systematically described. For the channel which does not satisfy the narrow band approximation condition, the Doppler scale factor is used to describe the wideband Doppler effect, and the received signal is expressed as the weighted superposition of multiple time-delay scale copies of the transmitted signal according to the wideband diffusion function. By modifying and improving the BELLHOP modeling tool and the Vir TEX algorithm, the channel with multi-scale and multi-time delay in the case of calm sea surface and sinusoidal fluctuation sea surface is simulated. 2) the existing channel estimation methods based on wideband correlation processing are studied. On this basis, a wavelet with a benchmark scale of rational number is used as the channel probe signal, and a discrete numerical algorithm for wideband deconvolution channel estimation and matching tracking channel estimation is proposed. Simulation results show that when the channel is sparse enough, both methods can obtain ideal wideband diffusion function estimation. 3) the pulse compression characteristics of LFM signals in time domain and fractional Fourier transform domain are utilized. A multi-scale and multi-delay channel parameter estimation method based on fractional order Fourier transform is proposed. The method can separate the multi-component LFM signals according to the order of energy magnitude in an iterative manner. In each iteration, the scale is obtained by a subiteration process which can correct the optimal order of transformation. Accurate estimation of delay and other parameters. Simulation results show that the estimation error of this method for wideband diffusion function is obviously better than that of other existing methods. 4) A hyperbolic frequency-spread spectrum communication scheme is proposed for multi-scale and multi-time delay underwater acoustic channels. The communication frame uses linear frequency modulation (LFM) signal as the frame head for channel estimation and uses a series of hyperbolic FM signals to modulate the data. The receiver has an extremely simple system structure and can directly use the channel parameter estimation results to divide the correlation output of the transceiver signal into multiple branches for diversity processing. The multipath scale diversity gain can be obtained by a certain combination technique. In addition, it is easy to extend the single band transmission system to multi-band transmission. The simulation results show that the proposed scheme is effective.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：TN929.3
[Abstract]:Since 1990s, due to the demand of economic and social development and national defense security, the research of underwater acoustic science and technology has been paid attention to by many countries all over the world, and has made great progress. Compared with terrestrial wireless channel, underwater acoustic channel has its particularity and complexity, which is manifested in its serious multipath effect, time-varying characteristic and band-limit characteristic. In recent years, the continuous development of underwater acoustic coherent communication has obvious advantages over non-coherent communication in improving the efficiency of frequency band and the rate of information transmission, but at the same time, the parameter estimation of underwater acoustic channel is required more and more. From the point of view of signal processing, the accuracy and efficiency of channel estimation directly affect the performance of the whole underwater acoustic communication system, so this problem has always been a top priority in the field of underwater acoustic research. Based on the physical characteristics of underwater acoustic channel and its wideband nature, the parameter estimation problem of underwater acoustic channel with multi-scale and multi-delay characteristics and its application in underwater acoustic communication are studied in this paper. The main contributions are as follows: 1) combining the analysis of ray theory and underwater acoustic Doppler effect, the multi-scale and multi-delay characteristics of broadband underwater acoustic channel model are systematically described. For the channel which does not satisfy the narrow band approximation condition, the Doppler scale factor is used to describe the wideband Doppler effect, and the received signal is expressed as the weighted superposition of multiple time-delay scale copies of the transmitted signal according to the wideband diffusion function. By modifying and improving the BELLHOP modeling tool and the Vir TEX algorithm, the channel with multi-scale and multi-time delay in the case of calm sea surface and sinusoidal fluctuation sea surface is simulated. 2) the existing channel estimation methods based on wideband correlation processing are studied. On this basis, a wavelet with a benchmark scale of rational number is used as the channel probe signal, and a discrete numerical algorithm for wideband deconvolution channel estimation and matching tracking channel estimation is proposed. Simulation results show that when the channel is sparse enough, both methods can obtain ideal wideband diffusion function estimation. 3) the pulse compression characteristics of LFM signals in time domain and fractional Fourier transform domain are utilized. A multi-scale and multi-delay channel parameter estimation method based on fractional order Fourier transform is proposed. The method can separate the multi-component LFM signals according to the order of energy magnitude in an iterative manner. In each iteration, the scale is obtained by a subiteration process which can correct the optimal order of transformation. Accurate estimation of delay and other parameters. Simulation results show that the estimation error of this method for wideband diffusion function is obviously better than that of other existing methods. 4) A hyperbolic frequency-spread spectrum communication scheme is proposed for multi-scale and multi-time delay underwater acoustic channels. The communication frame uses linear frequency modulation (LFM) signal as the frame head for channel estimation and uses a series of hyperbolic FM signals to modulate the data. The receiver has an extremely simple system structure and can directly use the channel parameter estimation results to divide the correlation output of the transceiver signal into multiple branches for diversity processing. The multipath scale diversity gain can be obtained by a certain combination technique. In addition, it is easy to extend the single band transmission system to multi-band transmission. The simulation results show that the proposed scheme is effective.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：TN929.3
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