Quantized peak based impulsive noise blanking in powerline communications

Many IN mitigation techniques have been proposed to mitigate impulsive noise (IN) over powerlines, the most common of which is the blanking technique. The conventional way to implement this technique however requires prior knowledge about the IN characteristics to identify the optimal blanking threshold (OBT). When such knowledge cannot be obtained the performance deteriorates rapidly. To alleviate this, a look-up table (LUT) based algorithm with uniform quantization is deployed to utilize estimates of the peak to average power ratio at the receiver to determine the OBT. In this paper, we investigate the impact of quantization bits on the system performance as well as the performance loss due to the impact of IN on the side information. Two aspects of the achievable performance are considered namely, output signal-to-noise ratio (SNR) and symbol error rate under various IN scenarios. The results reveal that a 5 bit LUT is sufficient to achieve a gain of up to 3dB SNR improvement relative to the conventional blanking method. Furthermore, it will be shown that the loss due to the practical impact of IN on the side information is insignificant. © 2013 IEEE

Energy-Efficient Vector OFDM PLC Systems with Dynamic Peak-Based Threshold Estimation

© 2013 IEEE. Power line communication (PLC) has made remarkable strides to become a key enabler of smart grid and its applications. Existing PLC systems are based on orthogonal frequency division multiplexing (OFDM), which has a high peak-to-average power ratio (PAPR). This paper presents vector OFDM (VOFDM) with advanced signal processing at the receiver to improve the energy efficiency of the PLC system. Results show that, due to its low PAPR properties, VOFDM is less sensitive to impulsive noise and provides a reduction of 5.8 dB in transmit power requirement relative to conventional OFDM. Furthermore, unlike the existing impulsive noise cancellation methods, the adopted signal processing technique also improves the SNR at the receiver by 2.1 dB, which further reduces the power requirement of the PLC transceiver. Together, these can simplify design, reduce cost, and improve energy efficiency of future PLC transceivers

Improved DPTE technique for impulsive noise mitigation over power-line communication channels

© 2015 Elsevier GmbH. All rights reserved. Signal blanking is a simple and efficient method commonly used to reduce the impact of impulsive noise (IN) over power-lines. There are two main ways to implement this method, namely, (a) the unmodified scheme and (b) the dynamic peak-based threshold estimation (DPTE) technique. Concerning the first, in order to optimally blank IN the noise characteristics must be made available at the receiver otherwise the system performance will degrade dramatically. Whereas in the DPTE case, only estimates of the signal peaks are required to achieve best performance. In this paper, however, we propose to enhance the capability of the conventional DPTE technique by preprocessing the signal at the transmitter side. To evaluate system performance, we consider the probability of blanking error (Pb), probability of missed blanking (Pm) and probability of successful detection (Ps). In light of this, closed-form analytical expressions for the three probabilities are derived which are then validated with simulations. The results reveal that the proposed DPTE technique can significantly minimize both Pb and Pm and maximize Ps. It is also shown that the proposed system is able to attain up to 3.5 dB and 1 dB SNR enhancement relative to the unmodified and the conventional DPTE techniques, respectively, as well as improving the symbol error rate performance

Quantized peak-based impulsive noise blanking in power-line communications

Impulsive-noise (IN) over power-line channels can cause serious performance degradations. As such, many IN mitigation techniques have been proposed in the literature, the most common of which is the blanking technique. The conventional way to implement this technique, however, requires prior knowledge about the IN characteristics to identify the optimal blanking threshold (OBT). When such knowledge cannot be obtained, the performance deteriorates rapidly. To alleviate this, we propose a lookup table (LUT)-based algorithm with uniform quantization to utilize estimates of the peak-to-average power ratio at the receiver to determine the OBT. To fully evaluate the performance of the proposed method, we investigate the impact of quantization bits on the system performance in terms of signal-to-noise ratio (SNR) and symbol error rate under various IN scenarios. The results reveal that a 5-bit LUT is sufficient to achieve a gain of up to 3-dB SNR improvement relative to the conventional blanking method. It will also be shown that to maintain good performance, the resolution of quantization must be increased especially when the IN probability of occurrence is relatively high. © 1986-2012 IEEE

Cross-layer energy efficiency of plc systems for smart grid applications

Though opinions are still divided over the specific choices of technology for smart grid, there is a consensus that heterogeneous communications network is most appropriate. Power line communication (PLC) is promising because it is readily available and it aligns with the natural topology of power distribution network. One of the emerging realities is that the communication system enabling smart grid must be energy-efficient. This thesis employs a cross-layer approach to address energy efficiency of PLC networks in different smart grid scenarios. At network layer, this work exploits the topology of a PLC-enabled advanced metering infrastructure (AMI) to improve the probability of successful packet delivery across the network. The technique, termed AMI clustering, leverages the traditional structure of the low voltage (LV) network by organising the smart meters into clusters and locally aggregating their readings. Improvement in packet delivery inherently reduces energy wastage. Next, the adaptation layer exploits the low data rate transmission techniques to reduce the energy requirements of PLC nodes. To achieve that, this work developed a network model in NS-3 (an open-source network simulator) that considers PLC transceivers as resource-constrained devices and interconnects them to emulate home energy management system (HEMS). The model was validated with experimental results which showed that in the home area network (HAN), low-rate applications such as energy management can be supported over low-power PLC networks. Furthermore, at physical layer, this thesis proposes a more energy-efficient multi-carrier modulation scheme than the orthogonal frequency division multiplexing (OFDM) used in most of the current PLC systems. OFDM is widely known for its high peak-to-average-power ratio (PAPR) which degrades energy efficiency of the systems. This thesis found that by employing vector- OFDM (V-OFDM), power requirements of PLC transmitter can be reduced. The results also showed the energy efficiency can be further improved by using a dynamic noise cancellation technique such as dynamic peak-based threshold estimation (DPTE) at the receiver. By applying the proposed methods, packet delivery can be improved by 3% at network layer (which conserves energy) and reduced data rate can save about 2.6014 dB in transmit power. Finally, at physical layer, V-OFDM and DPTE can respectively provide 5.8 dB and 2.1 dB reduction in power requirements of the PLC transceivers. These signify that if V-OFDM is combined with DPTE, future PLC modems could benefit from energy-efficient power amplifiers at reduced cost

Coded-OFDM for PLC systems in non-Gaussian noise channels

PhD ThesisNowadays, power line communication (PLC) is a technology that uses the power line grid for communication purposes along with transmitting electrical energy, for providing broadband services to homes and offices such as high-speed data, audio, video and multimedia applications. The advantages of this technology are to eliminate the need for new wiring and AC outlet plugs by using an existing infrastructure, ease of installation and reduction of the network deployment cost. However, the power line grid is originally designed for the transmission of the electric power at low frequencies; i.e. 50/60 Hz. Therefore, the PLC channel appears as a harsh medium for low-power high-frequency communication signals. The development of PLC systems for providing high-speed communication needs precise knowledge of the channel characteristics such as the attenuation, non-Gaussian noise and selective fading. Non-Gaussian noise in PLC channels can classify into Nakagami-m background interference (BI) noise and asynchronous impulsive noise (IN) modelled by a Bernoulli-Gaussian mixture (BGM) model or Middleton class A (MCA) model. Besides the effects of the multipath PLC channel, asynchronous impulsive noise is the main reason causing performance degradation in PLC channels. Binary/non-binary low-density parity check B/NB-(LDPC) codes and turbo codes (TC) with soft iterative decoders have been proposed for Orthogonal Frequency Division Multiplexing (OFDM) system to improve the bit error rate (BER) performance degradation by exploiting frequency diversity. The performances are investigated utilizing high-order quadrature amplitude modulation (QAM) in the presence of non-Gaussian noise over multipath broadband power-line communication (BBPLC) channels. OFDM usually spreads the effect of IN over multiple sub-carriers after discrete Fourier transform (DFT) operation at the receiver, hence, it requires only a simple single-tap zero forcing (ZF) equalizer at the receiver. The thesis focuses on improving the performance of iterative decoders by deriving the effective, complex-valued, ratio distributions of the noise samples at the zeroforcing (ZF) equalizer output considering the frequency-selective multipath PLCs, background interference noise and impulsive noise, and utilizing the outcome for computing the apriori log likelihood ratios (LLRs) required for soft decoding algorithms. On the other hand, Physical-Layer Network Coding (PLNC) is introduced to help the PLC system to extend the range of operation for exchanging information between two users (devices) using an intermediate relay (hub) node in two-time slots in the presence of non-Gaussian noise over multipath PLC channels. A novel detection scheme is proposed to transform the transmit signal constellation based on the frequency-domain channel coefficients to optimize detection at the relay node with newly derived noise PDF at the relay and end nodes. Additionally, conditions for optimum detection utilizing a high-order constellation are derived. The closedform expressions of the BER and average BER upper-bound (AUB) are derived for a point-to-point system, and for a PLNC system at the end node to relay, relay to end node and at the end-to-end nodes. Moreover, the convergence behaviour of iterative decoders is evaluated using EXtrinsic Information Transfer (EXIT) chart analysis and upper bound analyses. Furthermore, an optimization of the threshold determination for clipping and blanking impulsive noise mitigation methods are derived. The proposed systems are compared in performance using simulation in MATLAB and analytical methods.Ministry of Higher Education in Ira