Performance of Blanking/Clipping Selection Combining in OFDM-based PLC Systems

Abstract

Orthogonal frequency-division multiplexing (OFDM)-based power-line communications (PLC) has been considered as a popular last-mile technology for smart grid communications. However, using power-line as communication channel is challenging due to the occurrence of the impulsive noise. It has been studied that blanking and clipping techniques are efficient to detect and mitigate the impulsive noise at the receiver. As they use threshold to detect impulsive noise, the maximum output signal-to-noise ratio (SNR) of the blanker and clipper can be achieved by setting the optimum threshold. Moreover, we note that the optimum threshold and the maximum output SNR are determined by the signal-to-impulsive noise ratio (SINR), (input) SNR, and probability of impulsive noise occurrence. When the input SNR and the probability of impulsive noise occurrence are fixed, there exists an SINR range where the output SNR of the blanker is higher than that of the clipper, and vice versa. In the practical PLC environment, the SINR and $p$ may vary according to the network usage. Therefore, in this paper, we propose a PLC receiver with the selection combining module for two nonlinear pre-processors, i.e. blanker and clipper. The combiner selects the output of the nonlinear pre-processor with the highest output SNR to be passed to the demodulator. The proposed system will be evaluated under practical impulsive noise environment with varying SINR and probability of impulsive noise occurrence. Simulation results show that the proposed method can achieve better average output SNR and bit error rate (BER) performance.