文章摘要
郑彩云,马雪飞,张可,章佳荣,乔钢.基于短时傅里叶变换的水声OFDM时间同步方法[J].声学技术,2013,32(3):233~237
基于短时傅里叶变换的水声OFDM时间同步方法
Research on underwater orthogonal frequency division multiplexing timing synchronization based on short time Fourier transform
投稿时间:2012-05-15  修订日期:2012-08-23
DOI:10.3969/j.issn1000-3630.2013.03.012
中文关键词: 水声通信  时间同步  短时傅里叶变换  正交频分复用  单频信号
英文关键词: Underwater communication  timing approach  short time Fourier transform  orthogonal frequency division multiplexing  cosine wave signal
基金项目:
作者单位E-mail
郑彩云 哈尔滨工程大学信息与通信工程学院, 哈尔滨 150001 caiyunzheng@126.com 
马雪飞 哈尔滨工程大学水声技术国家重点实验室, 哈尔滨 150001  
张可 哈尔滨工程大学水声技术国家重点实验室, 哈尔滨 150001  
章佳荣 哈尔滨工程大学水声技术国家重点实验室, 哈尔滨 150001  
乔钢 哈尔滨工程大学水声技术国家重点实验室, 哈尔滨 150001  
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中文摘要:
      正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM)技术具有抗多径、频带利用充分、传输数据率高的优点, 在水声通信中具有重要的发展前景。由于多普勒频移和多径时延的存在, 需对OFDM信号进行时间同步。同步不准会引起OFDM水声通信中符号间干扰和子载波间干扰, 提出了一种基于叠加单频序列的短时傅里叶变换(STFT)时间同步方法, 该方案首先提取叠加在OFDM符号上的单频信号, 对该信号进行短时傅里叶变换, 随后对其时频幅度谱进行分析, 利用平坦区域确定同步时刻。仿真和试验结果表明, 该方案有效可行。
英文摘要:
      Orthogonal Frequency Division Multiplexing (OFDM) is a method that can combat multipath, fully use the frequency band and have high data transmission rate. Consequently it has a promising future in underwater acoustic communication. Underwater channel is a Doppler-distorted, high noised and time-varying multipath channel. Due to the existence of multipath and Doppler shift, timing synchronization plays a key role in OFDM systems. In this paper, a timing synchronization method based on short time Fourier transform (STFT) is proposed. First, STFT is operated on the outcome of the received single frequency signal accompanying the OFDM symbol, and then the time-frequency spectrum is obtained for calculating the summation of the outcome after STFT and finding the edge which is the original point of the underwater acoustic OFDM symbol. The results of simulations show good performance of this method even under low ratio of signal to noise.
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