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G3-powerline communication (G3-PLC) is a robust communication protocol originally developed for smart metering in low-voltage power distribution networks. Modeling G3-PLC modems is an essential task to investigate electromagnetic compatibility (EMC) issues related to the coexistence of the PLC signal with the high-frequency noise affecting low-voltage networks, mainly due to the presence of power converters and non-linear loads. Since detailed information on the modem internal architecture is usually not available to the end-user, this work investigates the possibility of developing behavioral (black-box) models of G3-PLC modems, whose parameters can be estimated starting from measurements carried out at the modem output ports. To this end, suitable test benches are set up and used for model-parameter extraction as well as for validation purposes. Experiments have proven that an equivalent representation involving non-ideal voltage sources (i.e., in terms of extended Thevenin/Norton equivalent circuits) is no longer feasible for the transmitting modem, since the presence of a closed-loop control system invalidates the linearity assumption. Hence, while the receiving modem is still modeled through an impedance matrix (since it behaves as a linear device), an alternative representation is proposed for the transmitting modem, which resorts to the use of two ideal voltage sources in accordance with the substitution theorem. Experimental results prove that the proposed modeling strategy leads to satisfactory predictions of the currents propagating on the PLC system in the frequency interval of interest. Hence, it could be used in combination with high-frequency models of the other components in the network to investigate EMC and the coexistence of the PLC signal with the high-frequency noise generated by power converters. [ABSTRACT FROM AUTHOR]

Channel impairments in powerline communication (PLC) and visible light communication (VLC) technologies are one of the causes of performance degradation in hybrid PLC and VLC (HPV) systems. In this study, we focus on one of the inherent noise types in PLC channels; impulse noise (IN), which is characterised by short bursts of rapidly modified amplitudes caused by random switching of electrical devices in a power network. Recently, a permutation coded orthogonal frequency division multiplexing (OFDM) with the $M$ -ary frequency shift keying ( $M$ FSK) scheme, in short, PC OFDM- $M$ FSK, was proposed for IN mitigation in PLC systems. It is conceived that the robustness of this scheme against IN in standalone PLC systems will enhance the error performance of the HPV system. Furthermore, since one of the disadvantages of the PC OFDM- $M$ FSK scheme compared to that using only the classical OFDM scheme, is degraded data rate, we propose a generalised PC OFDM- $M$ FSK scheme to improve the degraded data rate. This study shows that the use of OFDM- $M$ FSK improves the performance of an HPV system compared to that using only the classical OFDM modulation scheme by a signal-to-noise (SNR) ratio gain of 6 dB at a bit error rate (BER) of 10−4. Furthermore, an SNR gain of approximately 3 dB and reduction in the decoding complexity of the PC OFDM- $M$ FSK HPV system is achieved using a soft-decision Hungarian-Murty (HM) decoder. Moreover, the generalisation of the PC OFDM- $M$ FSK HPV system does not increase the decoding complexity when the SD HM decoder is used.

G3-powerline communication (G3-PLC) is a robust communication protocol originally developed for smart metering in low-voltage power distribution networks. Modeling G3-PLC modems is an essential task to investigate electromagnetic compatibility (EMC) issues related to the coexistence of the PLC signal with the high-frequency noise affecting low-voltage networks, mainly due to the presence of power converters and non-linear loads. Since detailed information on the modem internal architecture is usually not available to the end-user, this work investigates the possibility of developing behavioral (black-box) models of G3-PLC modems, whose parameters can be estimated starting from measurements carried out at the modem output ports. To this end, suitable test benches are set up and used for model-parameter extraction as well as for validation purposes. Experiments have proven that an equivalent representation involving non-ideal voltage sources (i.e., in terms of extended Thevenin/Norton equivalent circuits) is no longer feasible for the transmitting modem, since the presence of a closed-loop control system invalidates the linearity assumption. Hence, while the receiving modem is still modeled through an impedance matrix (since it behaves as a linear device), an alternative representation is proposed for the transmitting modem, which resorts to the use of two ideal voltage sources in accordance with the substitution theorem. Experimental results prove that the proposed modeling strategy leads to satisfactory predictions of the currents propagating on the PLC system in the frequency interval of interest. Hence, it could be used in combination with high-frequency models of the other components in the network to investigate EMC and the coexistence of the PLC signal with the high-frequency noise generated by power converters.

We propose a new sparsity-aware framework to model and mitigate the joint effects of narrow-band interference (NBI) and impulsive noise (IN) in hybrid powerline and unlicensed wireless communication systems. The proposed mitigation techniques, based on the principles of compressive sensing, exploit the inherent (non-contiguous or contiguous) sparse structures of NBI and IN in the frequency and time domains, respectively. For the non-contiguous NBI and IN, we develop a multi-level orthogonal matching pursuit recovery algorithm that exploits prior knowledge about the sparsity level at each receive antenna and powerline to further reduce computational complexity without performance loss. In addition, for the non-contiguous asynchronous NBI scenario, we investigate the application of time-domain windowing to enhance the NBI's sparsity and, hence, improve the NBI mitigation performance. For the contiguous NBI and IN scenario, we estimate the NBI and IN signals by modeling their burstiness as block-sparse vectors with and without prior knowledge of the bursts' boundaries. Moreover, we show how to exploit the spatial correlations of the NBI and IN across the receive antennas and powerlines to convert a non-contiguous NBI and IN problem to a block-sparse estimation problem with much lower complexity. Furthermore, we investigate a Bayesian linear minimum mean square error-based approach for estimating both non-contiguous and contiguous NBI and IN based on their second-order statistics to further improve the estimation performance. Finally, our numerical results illustrate the superiority of the joint processing of our proposed NBI and IN sparsity-based mitigation techniques compared to separate processing of the wireless and powerline received signals.

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.

This paper addresses the robust image transmission over powerline communication (PLC) channel in the presence of impulse noise. Under this framework, an adaptive noise clipping-based hybrid progressive median filter (ANC-HPMF), which is a combination of hybrid progressive median filter, noise clipping technique, image compression algorithm and coded OFDM modulation is designed to ensure image transmission over the PLC channel. For this purpose, image compression and turbo codes algorithms are inserted before image transmission in order to reduce the size of the transmitted data, and, therefore, save a significant amount of the PLC channel for forward error correction. The adaptive noise clipping method using neighboring coefficients is designed at the receiver side as a first stage. It is based on an improved estimation of noise threshold from the standard deviation of the noise and the peak value of the received noisy image. To enhance the performance of the proposed system, a new form of median filter is applied to the received image as a second stage of impulse noise reduction. By combining the noise clipping and the new median filtering, the proposed technique showed high robustness for the reduction of impulse noise even under high impulse level conditions while maintaining good visual quality of the images by preserving the edges. The performances of the proposed technique were compared with other well-known methods dedicated for impulse noise reduction, and showed much superior performance against the impulse noise generated over the PLC channel. [ABSTRACT FROM AUTHOR]

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