移动水声通信多径传输非一致多普勒估计方法研究

Study on Non-uniform Doppler Estimation for Underwater Acoustic Mobile Communications with Multipath Transmission

现有水声通信中的多普勒估计方法一般都假定多径信道每条路径的多普勒因子相等,当各路径多普勒因子存在差异时,该类方法往往无法正确估计出每径的多普勒因子,导致补偿后的信号存在较大误差。为此该文在分析水声信道稀疏特性的基础上,提出一种基于稀疏表示理论的非一致多普勒估计方法。该方法结合水声多径信道与非一致多普勒稀疏特性生成包含信道信息的超完备字典,将每径的非一致多普勒因子估计转化为基于超完备字典的稀疏重构求解,实现非一致多普勒因子的准确估计。仿真结果表明,所提方法不仅能估计出差异较大的非一致多普勒因子,而且对于大多普勒频偏的估计也相当有效,特别适合于高速移动水声通信中的多普勒估计。

The existing methods of Doppler estimation in UnderWater Acoustic （UWA） communication generally assume that the Doppler factor of each path is equal in multipath channel. But when the Doppler factors are different from each other, such methods can not estimate the Doppler factor correctly, resulting in significant compensation error. By analyzing the sparsity of the UWA channel, a novel method of non-uniform Doppler estimation is proposed, which is based on the sparse representation theory. By using the over-complete dictionary combining UWA multipath channel and non-uniform Doppler sparsity, the method transforms Doppler estimation of each path into sparse solution reconstruction, achieving accurate estimation of non-uniform Doppler factor. Simulation results show that the proposed method can estimate not onlythe quite different Doppler factors but also the large Doppler frequency offset. Therefore, it is especially important for Doppler estimation in high-speed mobile UWA communication.