Abstract: The technology of Orthogonal Frequency Division Multiplexing（OFDM），which is of high data rate，has been applied for underwater acoustic communication.However，it demands frequency orthogonality of sub-carriers.The Doppler-shift is too serious for underwater acoustic communication to prevent the application of OFDM.A new scheme called Combined Doppler Estimation and Compensation is given in this paper.The method，which combines cyclic prefix and training sequence，is used to estimate and compensate the Doppler-shift.From the experiment results，the method reduced the BER effectively with real channel.And its performance is much better than the traditional ones.

Key words: OFDM, Doppler-shift, cyclic prefix, training sequence

摘要： 正交频分复用（OFDM）技术已经应用于水声通信中，是一种高速传输的方法。但是OFDM的传输对于子载波正交性的要求很高，所以水声通信中存在的严重多普勒频率偏移限制了OFDM技术在水声通信中的应用。分析了适合于收发双方的多普勒估计与补偿技术，提出了综合多普勒补偿方法，即综合利用循环前缀法和利用训练序列进行多普勒估计与补偿。结合实际湖试水声信道进行实验，结果验证了该方法有效地降低了误码率，优于传统的多普勒估计与补偿方法。

关键词: OFDM, 多普勒频移, 循环前缀, 训练序列