Threshold and scaling factor optimization for enhancing impulsive noise cancellation in PLC systems

Power-line communication (PLC) is considered as the backbone of smart grid. Impulsive noise (IN) over such channels, however, remains the main factor responsible for degrading communication signals. A simple method to mitigate IN over PLC channels is to precede the receiver with a nonlinear preprocessor to blank and/or clip the incoming signal when it exceeds a certain threshold. Applying a combination of blanking and clipping in a hybrid fashion was shown to provide the best performance. The hybrid scheme is characterized by two thresholds T₁ and T₂ (T₁ = α.T₂), where a is a scaling factor. Previous studies assume a fixed value for the scaling factor and found that optimizing the threshold T₂ is the key to enhance performance. In this paper, we show that the performance of this scheme is sensitive not only to the threshold, but also to the scaling factor. With this in mind, a mathematical expression for the output signal-to-noise ratio as a function of the threshold and scaling factor is formulated and used to optimize the hybrid scheme performance. Simulation results are also provided to validate our analysis. The results reveal that using an adaptive hybrid scheme with an optimally selected threshold and scaling factor always outperforms other nonlinear schemes.