基于四阶累积量的EM波达方向估计算法

针对低信噪比（signal-to-noise ratio，SNR）下，经典波达方向估计性能下降的问题，提出将信号的四阶累积量与期望最大化（expectation maximization，EM）算法相结合的波达方向估计算法.该方法引入隐含变量进行更新迭代，并求隐含变量的四阶累积量，构造关于待估波达方向的极大似然函数从而求解出信号的波达方向角.仿真结果表明:本文算法能有效地抑制高斯噪声对信号参数估计的影响，同时能利用迭代来提高估计精度.在低SNR时其估计性能优良，具有很好的稳定性和分辨率，有利于高分辨地估计信号的波达方向.

Expectation maximization DOA estimation algorithm based on four-order cumulant

Aiming at the problem of low estimation performance of classical direction of arrival (DOA) estimation under low signal-to-noise ratio (SNR), this paper proposes a DOA estimation algorithm which combines the fourth-order cumulant of signal with the expectation maximization algorithm. The method introduces an implicit variable to update and iterate, and finds the fourth-order cumulant of the implicit variable. The maximum likelihood function of the estimated direction of arrival is constructed so as to obtain the direction-of-arrival of the signal. The simulation results show that the proposed algorithm can effectively suppress the influence of Gaussian noise on the signal parameter estimation. Meanwhile, the algorithm using iterative updating can improve the estimation accuracy. It has good performance in low signal-to-noise ratio(SNR) estimation, good stability and resolution, which is beneficial to the high-resolution estimation of DOA.