基于误比特信息区间斜率的正交频分复用水声通信多普勒估计

Doppler estimation based on the interval slope of bit-error information for orthogonal frequency division multiplexing underwater acoustic communications

针对正交频分复用水声通信中直接误比特率搜索多普勒估计算法存在的高计算复杂度问题,提出了一种基于误比特信息区间斜率的多普勒估计算法,采用计算误比特信息区间斜率取代逐网格搜索最优误比特信息寻优过程,设计根据多普勒估计分辨率动态可变的斜率区间,在进一步提升寻优速率的同时有效减小陷入局部最优解的可能性,并有效降低算法的计算复杂度。仿真实验和海上试验结果表明:所提算法以较低的计算代价实现了与误比特率搜索多普勒估计算法近乎一致的估计性能,在本文试验条件下其相对块多普勒估计、基于互模糊度函数多普勒估计以及准梯度互相关多普勒估计算法可获得不低于14%的误比特率性能改善。

The Doppler estimation strategy based on the direct search of bit-error rate(BER)produces high computational complexity in orthogonal frequency division multiplexing(OFDM)underwater acoustic communications.To address this issue,a novel Doppler estimation algorithm based on the interval slope of bit-error information is proposed,which replaces the exhaustive grid-wise search of the optimal bit-error information by calculating the interval slope of bit-error information.Moreover,the dynamic variable slope interval is designed according to the Doppler estimation resolution to further accelerate the optimization process,to avoid being trapped at a local minimum as well as to reduce the computational complexity.The numerical simulation and sea trial experiments demonstrate that,compared to the BER search Doppler estimation algorithm,the proposed algorithm achieves almost the same performance with an obviously lower computational cost.Specifically,it yields a BER performance enhancement of not less than 14%compared with the block Doppler estimation,cross-ambiguity function based Doppler estimation and the cross-correlation quasi-gradient Doppler estimation algorithms under the experimental conditions in this paper.