【摘要】：正交頻分復(fù)用（Orthogonal Frequency Division Multiplexing，OFDM）技術(shù)是一種對抗頻率選擇性衰落的有效技術(shù)，且具有較高頻帶利用率，由于水聲信道頻譜資源極為有限，為提高通信速率和頻帶利用率，將具有較高通信速率和頻帶利用率的OFDM技術(shù)應(yīng)用于水下，具有現(xiàn)實(shí)意義。但其固有的缺點(diǎn)（例如大的峰值平均功率比（PAPR），相位噪聲以及子載波間干擾（ICI），易受多普勒頻偏和時(shí)變信道影響）又使得它在多普勒效應(yīng)比較嚴(yán)重同時(shí)又具有多徑效應(yīng)的水聲信道中性能急劇下降。因此尋求一種新的更好的水聲通信系統(tǒng)具有重要意義。 本文首先對水聲信道特性及其信道建模進(jìn)行了綜述，進(jìn)而分析了傳統(tǒng)的基于傅里葉變換的OFDM系統(tǒng)的基本原理與關(guān)鍵技術(shù)，總結(jié)了它的優(yōu)缺點(diǎn)，其中針對子載波的正交性容易遭到破壞而引起子載波間干擾的問題，研究了一種基于分?jǐn)?shù)階傅里葉變換的OFDM系統(tǒng)，該系統(tǒng)選用一組頻帶相互重疊的LFM信號代替原來的正弦信號作為子載波進(jìn)行信息調(diào)制，以分?jǐn)?shù)階傅里葉變換作為調(diào)制解調(diào)方法來傳輸信息，同時(shí)通過信道估計(jì)與分?jǐn)?shù)階傅里葉域的乘性濾波均衡器對輸出信號進(jìn)行濾波均衡，以對抗水聲信道的多徑效應(yīng)和多普勒效應(yīng)。仿真表明，在水聲通信中，基于分?jǐn)?shù)階傅里葉變換的OFDM系統(tǒng)性能優(yōu)于傳統(tǒng)的基于傅里葉變換的OFDM系統(tǒng)。
[Abstract]:Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division) is an effective technique to counter frequency selective fading and has a high frequency band efficiency. Because of the limited spectrum resources of underwater acoustic channel, in order to improve the communication rate and frequency band efficiency, the orthogonal Frequency Division Multiplexing (OFDM) is an effective technique to combat frequency selective fading. It is of practical significance to apply OFDM technology with high communication rate and band efficiency to underwater. However, its inherent disadvantages (such as large peak-to-average power ratio (PAPR), phase noise and inter-carrier interference (ICI), are susceptible to Doppler frequency offset and time-varying channels) make it have more serious Doppler effect and multipath effect at the same time. The performance of the underwater acoustic channel drops sharply. Therefore, it is of great significance to seek a new and better underwater acoustic communication system. In this paper, the characteristics of underwater acoustic channel and its channel modeling are reviewed, and then the basic principles and key technologies of traditional OFDM system based on Fourier transform are analyzed, and its advantages and disadvantages are summarized. Aiming at the problem that the orthogonality of subcarriers is easy to be destroyed and the inter-subcarrier interference is caused, a OFDM system based on fractional Fourier transform is studied. Instead of the original sinusoidal signal, a group of overlapping LFM signals are used to modulate the information, and the fractional Fourier transform is used as the modulation and demodulation method to transmit the information. At the same time the output signal is equalized by channel estimation and multiplicative filter equalizer in fractional Fourier domain to counteract the multipath effect and Doppler effect of underwater acoustic channel. Simulation results show that the performance of OFDM system based on fractional Fourier transform is better than that of traditional OFDM system based on Fourier transform in underwater acoustic communication.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN929.3

【參考文獻(xiàn)】

相關(guān)期刊論文 前6條

1 陳恩慶;陶然;張衛(wèi)強(qiáng);;一種基于分?jǐn)?shù)階傅立葉變換的時(shí)變信道參數(shù)估計(jì)方法[J];電子學(xué)報(bào);2005年12期

2 陳恩慶;陶然;張衛(wèi)強(qiáng);孟祥意;;一種基于分?jǐn)?shù)階傅里葉變換的OFDM系統(tǒng)及其均衡算法[J];電子學(xué)報(bào);2007年03期

3 陳恩慶;陶然;張衛(wèi)強(qiáng);趙娟;孟祥意;;分?jǐn)?shù)階傅立葉變換OFDM系統(tǒng)自適應(yīng)均衡算法[J];電子學(xué)報(bào);2007年09期

4 許克平,許天增,許茹,程恩,王清池,粘寶卿;基于水聲的水下無線通信研究[J];廈門大學(xué)學(xué)報(bào)(自然科學(xué)版);2001年02期

5 賈宏;許茹;孫海信;梁春麗;;基于OFDM的水聲信道編碼技術(shù)研究[J];廈門大學(xué)學(xué)報(bào)(自然科學(xué)版);2008年04期

6 李啟虎;水聲學(xué)研究進(jìn)展[J];聲學(xué)學(xué)報(bào);2001年04期

，

本文編號：2178288