基于短时傅里叶变换的水声通信自适应OFDM均衡  

Adaptive OFDM equalization in underwater acoustic communication based on short time Fourier transform

作　　者：张玲玲[1] 黄建国[1] 韩晶[1] 唐成凯[2] 

机构地区：[1]西北工业大学航海学院,陕西西安710072 [2]西北工业大学电子信息学院,陕西西安710072

出　　处：《系统工程与电子技术》2015年第4期918-922,共5页Systems Engineering and Electronics

基　　金：国家自然科学基金(61001153;61271415);水下信息处理与控制国家重点实验室基金(9140C231002130C23085);西北工业大学博士论文创新基金(CX201230);西北工业大学基础研究基金-中央高校基本科研业务费专项基金(3102014JCQ01010)资助课题

摘　　要：由于水声环境时变特性,在水声信道中进行正交频分复用(orthogonal frequency division multiplexing,OFDM)信号传输,子载波间的正交性易受到破坏,从而产生载波间干扰,使得水声通信的误码率性能变差。针对这个问题,提出一种适用于水下时变信道的自适应OFDM均衡算法,该算法采用滑动窗口进行子块短时傅里叶变换获得接收信号的二维时频谱,进而对该二维时频谱进行自适应时-频域联合合并均衡。该自适应均衡算法中采用最小均方误差算法跟踪信道时变特性,并通过自适应判决反馈均衡更新二维时频谱的加权合并系数,提高了OFDM系统抗载波间干扰的性能。仿真分析表明,所提出的OFDM均衡算法可在时变信道下,有效降低水声通信的误码率。For orthogonal frequency division multiplexing （OFDM） signal transmission over underwater acoustic channel, the subcarrier orthogonatity is quite easily destroyed by the time varying characteristic of un derwater environment, which will cause great inter carrier interference, and increase the bit error ratio of the underwater acoustic communication system. An adaptive underwater acoustic OFDM equalization algorithm is proposed, which adopts adaptive joint time-frequency combination of the two-dimension spectrum of the received signal obtained by a sliding window based sub-block short time Fourier transform （STFT）. The adaptive equali- zation algorithm is implemented by adaptively tracking the time varying channel characteristic by least mean square （LMS） method, then adaptively combine the time-frequency sequences with the coefficients updated hy adaptive decision feedback equalization. Simulation results show that the proposed OFDM equalization method over time varying channel can decrease the bit error ratio of the underwater acoustic communication effectively.

关 键 词：水声通信 正交频分复用 载波间干扰 短时傅里叶变换 

分 类 号：TN929.3[电子电信—通信与信息系统]