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针对正交频分复用技术(OFDM)系统的多音干扰,本文提出先通过增加频域分辨率进行多音干扰识别,再基于迭代运算逐个对多个单音干扰进行参数估计、重构和消除的方案。其中,在多音干扰识别阶段,使用Zoom FFT技术以提高频域分辨率并简化计算复杂度。然而,Zoom FFT后的降采样序列点数不一定满足2的整数次幂,对于单音干扰参数估计,此时可采用经典的基于离散傅里叶变换(DFT)的最大似然参数估计(DFT-MLE),但当采样点数太大时,DFT运算将带来很大的实现复杂度。本文在基于DFT-MLE算法基础上给出一种基于快速傅里叶变换(FFT)的单音参数估计法FFT-MLE,不仅简化了运算复杂度,而且相比DFT-MLE其估计性能有更好的鲁棒性。最后的仿真结果说明了该多音干扰消除方案的有效性。
For multi-tone interference in orthogonal frequency division multiplexing (OFDM) system, this paper proposed to identify multi-tone interference by increasing the resolution of the frequency domain first, and then to estimate the parameters of the single-tone interference one by one based on iterative calculation, Elimination of the program. Among them, in the polyphonic interference recognition stage, Zoom FFT technology is used to improve the frequency domain resolution and simplify the computational complexity. However, the points of down sampling sequence after Zoom FFT do not necessarily satisfy the integer power of 2. For the estimation of monophonic interference parameters, the classical DFT-based maximum likelihood parameter estimation (DFT- MLE), but when the sampling points are too large, DFT operation will bring a great deal of complexity. Based on the DFT-MLE algorithm, this paper presents a single-tone parameter estimation algorithm FFT-MLE based on Fast Fourier Transform (FFT), which not only simplifies the computational complexity, but also has more performance than DFT-MLE Good robustness. The final simulation results illustrate the effectiveness of this multitone interference cancellation scheme.