正交频分复用水声通信子载波干扰抑制

在引入正交频分复用调制技术的水声通信中，发送端与接收端采样频率偏差及多普勒频移会引起子载波间的干扰，为了抑制信号产生幅度衰落和相位畸变并降低系统误码率，根据多载波水声通信的特点提出了一种抑制载波间干扰的方法.利用导频序列拟合出采样频偏，通过重采样滤波器进行补偿，对多普勒因子粗补后，利用各象限解调数据方差的极小值确定解调数据长度，通过高分辨率傅里叶变换实现多普勒干扰抑制.3次实验结果证明该方法有效可行，能够较好地抑制子载波干扰，可显著提高多载波水声通信的系统性能.

Sub-carrier interference suppression for underwater acoustic communication applied orthogonal frequency division multiplexing

In the underwater acoustic communication applied the orthogonal frequency division multiplexing modulation technology,the sampling frequency offset and Doppler frequency shift between transmitters and receivers would cause the interference between sub-carriers.In order to inhibit the amplitude fading and phase distortion of signals as well as decrease the bit error rate of system,a method for suppressing the interference between sub-carriers was proposed according to the characteristics of multi-carrier underwater acoustic communication.The sampling frequency offset was fitted with pilot sequence and compensated by resampling filter.After the rough compensation of Doppler factors,the length of demodulated data was determined with the minimum value of variance of demodulated data in different quadrants.Then the Doppler interference suppression was realized with high resolution Fourier transform.The results of three experiments show that the proposed method is effective and feasible,and can not only suppress the sub-carrier interference better,but also obviously enhance the performance of multi-carrier underwater acoustic communication system.