Abstract: A single carrier system with frequency domain equalization （SC-FDE） based on UW （Unique Word） is designed for underwater acoustic communication.The basic configuration and principle of the system are discussed.A correlation synchronization algorithm based on UW is proposed for correlation peak split caused by multi-path，which can improve frame synchronization precision significantly.Doppler frequency-shift estimation and emendation algorithm based on UW，and channel estimation and equalization algorithm based on UW are discussed .The performance of this system is analyzed.The results show that the single carrier system with frequency domain equalization（SC-FDE） using correlation synchronization algorithm based on UW can improve frame synchronization precision，exactly estimate the serious Doppler frequency-shift and multi-path，track channel time-variability.The system can produce low BER at high signal-noise ratio.The SC-FDE based on UW is promising in underwater acoustic communications.

Key words: UW, single carrier systems with frequency domain equalization, multi-path propagation, frame synchronization, Doppler frequency shift

摘要： 设计了一种基于UW（Unique Word）帧结构的单载波频域均衡（SC-FDE）水声通信系统框架，论述了系统的基本原理。为解决帧同步过程中出现由水声多径引起的相关峰峰值分裂现象，提出一种基于UW序列的相关同步算法，使系统的同步精度显著提高。同时给出了基于UW序列的多普勒频移的估计和校正、信道估计和频域均衡算法。最后对系统的性能进行了分析。结果表明：采用相关同步算法的基于UW帧结构的单载波频域均衡水声通信系统能够显著提高在较复杂的信道条件下的帧同步精度，对水声信道中严重的多普勒频移和多径信道进行有效的估计，并能够对时变信道进行跟踪，在高信噪比下系统有较低的误码率，对水声通信有良好的应用价值。

关键词: UW, 单载波频域均衡, 多径效应, 帧同步, 多普勒频移