直接序列扩频水声通信中的自适应多普勒补偿方法  

Adaptive Doppler Compensation for Direct-Sequence Spread-Spectrum Underwater Acoustic Communication

作　　者：雷开卓[1] 韩晶[1] 黄建国[1] 

机构地区：[1]西北工业大学航海学院,陕西西安710072

出　　处：《西北工业大学学报》2010年第6期829-833,共5页Journal of Northwestern Polytechnical University

基　　金：国家973(513060103);国家自然科学基金(60572098)资助

摘　　要：当直接序列扩频水声通信的收发机存在相对运动时必须对接收信号进行多普勒补偿,但现有补偿方法在频率扩展信道中存在多普勒残留,使系统性能下降。文章提出了一种针对直接序列扩频的每路径自适应多普勒补偿方法,此方法通过解算互模糊度函数获取信道中各路径的时延与多普勒因子,并采用多相滤波器内插方法分别对各路径到达信号实现符号级自适应多普勒补偿,同时借助RAKE接收机将各路径信号的解调结果作为时间分集进行合并。在双扩展水声信道中的仿真分析表明,该方法提高了输出信噪比和信号畸变比,具有更好的时变跟踪性能。In the direct-sequence spread-spectrum underwater acoustic communication,carrier tracking and symbol synchronization are adversely affected by the movement between the transmitter and the receiver.In this case,conventional RAKE receiver may fail to function and Doppler compensation must be adopted.However,the existing methods of Doppler compensation employ only one interpolator,this will lead to residual Doppler and performance degradation of the receiver in frequency-spread channel.So in this paper,an algorithm is presented for direct-sequence spread-spectrum communication,which is implemented as follows： First,by Fig.1 and Eq.（4）,the cross-ambiguity function is calculated and the path delay τk and Doppler Δk are initially estimated.Then,by Eq.（6） through（10）,polyphase filter interpolator is combined with RAKE receiver to perform Doppler compensation at symbol rate on each path of the channel.Finally,as shown in Fig.2-（b）,the demodulated symbols on each path are considered as time diversity and combined by RAKE receiver.By simulations in doubly-spread underwater acoustic channel,our method of Doppler compensation achieves error-free demodulation（Fig.6） and outperforms the existing method with higher signal-to-distortion ratio（Fig.5） and 5dB output SNR signal-to-noise ratio（Fig.7）,thus has better capability of tracking the time-varying channel.

关 键 词：水声通信 每路径多普勒补偿 直接序列扩频 双扩展信道 

分 类 号：TN911[电子电信—通信与信息系统] TB567[电子电信—信息与通信工程]