UUV平台OFDM水声通信时变多普勒跟踪与补偿算法

Time-variant Doppler tracking and compensation in underwater acoustic OFDM communication for UUV platform

针对传统多普勒估计和补偿算法在基于无人水下航行器(UUV)的正交频分复用(OFDM)水声移动通信中难以准确跟踪时变多普勒因子并对其进行快速实时补偿的缺陷,提出了一种基于时频联合搜索的新的多普勒跟踪与快速补偿算法。利用梳状导频结合频域变采样技术搜索OFDM符号在不同多普勒因子下的信道频域响应,借助匹配追踪技术对信道估计结果进行稀疏度评估,选择稀疏度最佳的信道响应对应的多普勒估计对信号进行快速补偿。经蒙特卡洛仿真及海试试验证明,该方法能够有效实现对基于UUV平台的时变多普勒实时追踪和快速补偿,保证稳健的OFDM水声移动通信。

To overcome disadvantages of conventional Doppler estimation and compensation on UUV （ Unmanned Underwater Vehicle） platform, a joint time-frequency searching algorithm is proposed to track and rapidly compensate the time-variant Doppler in underwater acoustic OFDM （Orthogonal Frequency Division Multiplexing ） communication. The algorithm utilizes the comb pilots combined with frequency-domain resampling to calculate the channel impulse response with different Doppler factors. Then the correct Doppler factor is achieved and eliminated by seeking the sparsest channel impulse response, which is accessed using matching pursuit method. Experimental results, performed by Monte Carlo simulation and sea-trial test, demonstrate that the proposed algorithm can effectively track and rapidly compensate the time-variant Doppler factor, thus, ensure the stable underwater acoustic OFDM mobile communication for UUV.