Abstract: To solve the problem of the Orthogonal Frequency Division Multiplexing (OFDM) broadband signal processing, an algorithm for the Direction of Arrival (DOA) estimation of OFDM signal based on the broadband focused matrix and higher-order cumulant was introduced. In the former algorithm, broadband array data was broken down into several narrowband signals by Fourier transform, the direction matrices under different frequence bands were transformed to the same reference frequency by a focused matrix, and then with the Multiple Signal Classification (MUSIC) algorithm DOA was estimated. In the higher-order cumulant algorithm, through the focus operation, array output vectors at different frequency bins were transformed to focusing frequency and individual cumulant matrix was got. Each cumulant matrix was made weighted average and eigen-decomposition, and then the MUSIC algorithm was applied to estimate DOA. Theoretical analysis and simulation results show that the two methods are able to accurately estimate DOA of OFDM signal, the spatial resolution of four-order cumulant method is better than the focusing matrix method. The four-order cumulant expanded the array aperture, and it also has good adaptability when the Signal-to-Noise Ratio (SNR) is low.

Key words: Orthogonal Frequency Division Multiplexing (OFDM), wideband focused matrix, higher-order cumulant, Multiple Signal Classification (MUSIC) algorithm, Direction Of Arrival (DOA) estimation

摘要： 为了解决正交频分复用(OFDM)宽带信号处理的问题,研究了基于宽带聚焦矩阵和高阶累积量的波达方向(DOA)估计方法。前者是通过傅里叶变换将宽带阵列数据分解为若干窄带信号,再利用一种聚焦矩阵将不同频带下的方向矩阵变换到同一参考频率下,然后用多重信号分类(MUSIC)算法来估计DOA；高阶累积量算法是通过聚焦操作,把各个窄带频率处的阵列输出矢量变换到聚焦频率处,然后求其累积量矩阵。对各个累积量矩阵进行加权平均并特征值分解,再应用MUSIC算法估计DOA。理论分析和仿真结果表明，两种方法都能够精确地估计OFDM信号的DOA,四阶累积量方法的空间分辨率比聚焦矩阵方法有所提高。四阶累积量算法扩展了阵列孔径，信噪比(SNR)较低的时候也有很好的适应性。

关键词: 正交频分复用, 宽带聚焦矩阵, 高阶累积量, 多重信号分类算法, 波达方向估计