中压电力线通信自适应OFDM系统背景噪声抑制技术研究

Research on background noise suppression technology for adaptive OFDM system of medium voltage power line communication

针对中压电力线通信自适应OFDM系统缺乏抗噪声干扰措施的问题,介绍了一种低复杂度的子空间迭代算法用以抑制背景噪声。该方法基于子空间理论来分解含噪OFDM信号的特征空间,并在信号失真最小的约束条件下,应用拉格朗日最优极值法来获得理想信号的最佳估计。针对经典子空间方法求特征值分解时的高计算量,该方法采用重复一维子空间迭代的办法来降低计算复杂度。构建了结合信噪比门限与注水原理的自适应OFDM系统,并仿真比较背景噪声抑制前后的系统性能。结果表明,该方法能够进一步改善误比特率性能,提高信噪比。应用该方案可优化自适应OFDM系统在PLC中的应用。

In view of that there is a lack of anti-noise interference measures in adaptive OFDM system of medium voltage power line communication,a low complexity subspace iterative algorithm is proposed to suppress background noise.The feature space of the noisy OFDM signal is decomposed based on the subspace theory,and under the constraint of minimum signal distortion,the best estimate of the ideal signal is obtained by applying the Lagrangian optimal extremum value method.For the high computational complexity of eigenvalue decomposition of the classical subspace method,the repeated one-dimensional subspace iteration is used to reduce the computational complexity.An adaptive OFDM system which combines the signal-to-noise ratio threshold and water injection principle is constructed,and the system performances before and after background noise suppression are compared.The results show that the method can further improve the bit error rate performance and improve the signal-to-noise ratio,and the method proposed in this paper can be used to optimize the application of adaptive OFDM systems of PLC.