This paper presents a novel approach to mitigate the periodic impulsive noise before the synchronization of the orthogonal frequency-division multiplexing (OFDM)-based power-line communications (PLC) system. The proposed algorithm is employed to detect the periodic impulsive noise and then suppresses the periodic impulsive noise with an adaptive infinite impulse response (IIR) notch filter before the synchronization of the system, finally compensating the distortion of received signals brought by the IIR notch filter. Subsequently, the periodic impulsive noise mitigation algorithm is simulated and implemented in the PLC receiver's physical layer. Finally, the proposed algorithm is verified in field-programmable gate array and tested in the indoor PLC network. The simulation and field trial results show that the proposed periodic impulsive noise mitigation technique is simple and effective for the narrowband OFDM-based PLC system, such as the application of automatic meter reading.Index Terms-Adaptive infinite impulse response (IIR) notch filter, compensation, detection, orthogonal frequency-division multiplexing (OFDM), periodic impulsive noise, power-line communications (PLC).

This paper presents a novel 128-point Fast Fourier Transform (FFT) processor for practical Ultra-wideband (UWB) applications. The pipeline FFT processor based on the proposed non-Cooley-Tukey radix-8 unit can provide high throughput rate and has low hardware complexity. The radix-8 unit's hardware cost can save up to 20% compared with Radix-2 Single path Delay Feedback (R2SDF) architecture. Furthermore, both the input and output are in nature order. A 128-point FFT processor has been designed and implemented with SMIC 0.18µm CMOS process based on the proposed architecture. The throughput rate of proposed FFT processor is up to 409.6 Msample/s, which can meet the specification of UWB systems.

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