On Companding and Optimization of OFDM Signals for Mitigating Impulsive Noise in Power-Line Communication Systems
On Companding and Optimization of OFDM Signals for Mitigating Impulsive Noise in Power-Line Communication Systems
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DOI：
10.1109/access.2017.2747629
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发表时间：
2017-09
期刊：
影响因子：
3.9
通讯作者：
K. Anoh;B. Adebisi;Khaled Maaiuf Rabie;Mohammad Hammoudeh;H. Gačanin
中科院分区：
文献类型：
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作者：
K. Anoh;B. Adebisi;Khaled Maaiuf Rabie;Mohammad Hammoudeh;H. Gačanin
由于正交频分复用（OFDM）信号幅度的概率密度函数（PDF）一般服从瑞利分布，因此很难准确预测电力线通信（PLC）系统中脉冲噪声（IN）的存在。压缩和扩展这些OFDM信号中的一些的幅度（通常称为压扩）是峰均功率比降低技术，其使OFDM信号的幅度朝向均匀分布失真。我们建议将其应用于PLC系统，如IEEE 1901电力线标准（使用OFDM），以减少IN的影响。这是因为PLC信道拾取常规OFDM驱动器无法对抗的脉冲干扰。因此，我们探索五种广泛使用的压扩方案，将OFDM信号幅度分布转换为均匀分布，以通过消隐、削波及其混合（削波-消隐）来减轻PLC系统接收器中的IN。我们还采用非线性优化搜索，以找到最佳的缓解阈值和结果显示显着改善的输出信噪比（SNR）的所有压扩变换考虑高达4 dB的SNR增益。由此可见，传统的PDF导致错误的IN检测，当应用上述三种非线性无记忆缓解方案中的任何一种时，这减小了输出SNR。
Generally, the probability density function (PDF) of orthogonal frequency division multiplexing (OFDM) signal amplitudes follow the Rayleigh distribution, thus, it is difficult to correctly predict the existence of impulsive noise (IN) in powerline communication (PLC) systems. Compressing and expanding the amplitudes of some of these OFDM signals, usually referred to as companding, is a peak-to-average power ratio reduction technique that distorts the amplitudes of OFDM signals towards a uniform distribution. We suggest its application in PLC systems, such as IEEE 1901 powerline standard (which uses OFDM) to reduce the impacts of IN. This is because the PLC channel picks up impulsive interference that the conventional OFDM driver cannot combat. We explore, therefore, five widely used companding schemes that convert the OFDM signal amplitude distribution to uniform distribution to avail the mitigation of IN in PLC system receivers by blanking, clipping and their hybrid (clipping-blanking). We also apply nonlinear optimization search to find the optimal mitigation thresholds and results show significant improvement in the output signal-to-noise ratio (SNR) for all companding transforms considered of up to 4 dB SNR gain. It follows that the conventional PDF leads to false IN detection, which diminishes the output SNR when any of the above three nonlinear memoryless mitigation schemes is applied.