OFDM系统中的窄带干扰抑制

Narrowband Interference Suppression in OFDM System

摘要:

正交频分复用（Orthogonal Frequency Division Multiplexing, OFDM）技术由于其对频谱的利用率高、抵抗多径的能力好等优势，已经成为了最常用的多载波传输方案。但是OFDM系统易受窄带干扰的影响，导致其系统误码率显著上升。针对这一缺点，提出了一种有效的窄带干扰消除算法。在频域对窄带干扰的参数进行高精度估计并根据估计的参数重建干扰，从而实现对干扰的准确消除。采用了最大似然估计法结合零填充插值法进行初步估计，避免了由于频谱泄漏导致的误判。利用初步估计出的频率变换接收信号的频率，应用加权相位平均算法来获得干扰频率的精确估计。利用仿真平台进行仿真建模，测试了不同干扰强度下系统的误码率性能。实验表明所提算法可以有效提升系统误码率性能，且受干扰强度影响不大。

Abstract:

Orthogonal Frequency Division Multiplexing (OFDM) has become one of the most widely used multi carrier transmission schemes because of its advantages of high spectrum utilization, strong anti-multipath ability and low complexity. However, the OFDM system is vulnerable to narrowband interference, resulting in a significant reduction in Bit Error Rate (BER) performance. To solve this problem, an effective narrowband interference cancellation algorithm is proposed. By estimating and reconstructing the narrowband interference in frequency domain, the interference can be eliminated accurately. The Maximum Likelihood (ML) estimation method combined with zero fill interpolation method is used for preliminary estimation to avoid misjudgment caused by spectrum leakage. The frequency of the received signal is transformed by using the initial estimated frequency, the Weighted Phase Averaging (WPA) algorithm is applied to obtain the accurate estimation of the interference frequency. The simulation platform is used for simulation modeling, and the BER performance of the system under different jamming intensity is tested. Experiments show that the proposed algorithm can effectively improve the BER performance of the system, and is not affected by the interference intensity.