Power Line Channel Research Articles

Network Coding in the Link Layer for Reliable Narrowband Powerline Communications

The wide availability of power distribution cables provides an interesting no-new-wires communication channel. However, its electrical characteristics make it a harsh environment for the data transmission purpose and prevent the deployment of services with high reliability requirements. This paper proposes and implements an OSI-Layer2 network coding-based cooperative scheme with the aim of improving communication reliability in indoor narrowband powerline channels. The proposed scheme uses random linear network coding with a sliding window and relaying. We use network coding to replace the retransmissions triggered by legacy subsequent repeat request (ARQ) schemes. We evaluate the performance of our approach in terms of throughput and delay. Regarding the throughput achieved in harsh environments, we show that our scheme often more than doubles the throughput of existing legacy ARQ schemes. At the same time, and even under the large variation of traffic characteristics, it is shown that the delay is likely to be upper bounded by a few seconds, a bound that cannot be guaranteed in other existing transmission techniques.

OPTIMAL NARROWBAND AND BROADBAND DATA COMMUNICATION TRANSMISSION IN LOW-VOLTAGE POWER LINE

We investigate the usage of low-voltage electrical power supply network as a communication channel for the provision of data communication services. This is done through simulations and measurements of the power line channel transfer function in the frequency band of 0-30 MHz. A Parallel Resonant Circuit (PRC) channel model is then proposed to model the power line network and results compared to a Series Resonant Circuit (SRC) model. The model is simulated and validation done through measurements on a test bed for a cascaded network with three T-node branches. Transverse Electromagnetic (TEM) transmission line resonant circuit theory is employed to calculate and optimize the obtained parameters of the model. From the results obtained, the simulated models and measurement results are confirmed to compare very well with each other, and thus the proposed PRC model is considered appropriate for the characterization and modelling of the power line network channel.

A Wavelet OFDM receiver for baseband power line communications

Wavelet OFDM is one of the medium access techniques adopted by the IEEE P1901 working group for broadband power line communications (PLC). This paper reviews important aspects of baseband physical layer for broadband PLC, such as the scheme of modulation to obtain the transmitter and the characteristics of the recommended prototype filters. It further proposes a viable receiver system compatible with the transmitter and that provides perfect reconstruction characteristics in ideal environments. Furthermore, a procedure to perform the per-subcarrier frequency domain equalization, essential to deal with the power line channel effects at the receiver side, is also addressed. In order to greatly simplify the equalizer design, an efficient fast algorithm with reduced computational complexity is presented. Finally, this study is completed with several computer simulations, considering in-home PLC scenarios, to demonstrate the benefits of the proposed transceiver system.

Performance analysis of orthogonal frequency division multiplexing systems in dispersive indoor power line channels inflicting asynchronous impulsive noise

Hidden semi-Markov modelling of the asynchronous impulsive noise (IN) encountered in indoor broadband power line communications (PLCs) is investigated by considering the statistical distributions of both the inter-arrival time and the duration of asynchronous IN components. Then, the bit error ratio (BER) of orthogonal frequency division multiplexing systems using Q-ary quadrature amplitude modulation is analysed with the aid of the proposed noise model, when communicating over dispersive indoor power line channels inflicting asynchronous IN in addition to the background noise. The authors’ simulation results confirm the accuracy of the analysis and quantify the impact of various factors on the achievable BER performance. The grave impact of asynchronous IN on indoor broadband PLCs suggests that efficient techniques have to be designed for mitigating its effects.

Robust image transmission over powerline channel with impulse noise

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.

Analysis of Channel Transfer Functions in Power Line Communication System for Smart Metering and Home Area Network

The paper deals with simulations of power line channel transfer functions in Network Simulator version 3. Firstly, an empirical model and calculation of the channel transfer function a ...

Measurement and simulation framework for throughput evaluation of narrowband power line communication links in low-voltage grids

High-data-rate narrowband Power Line Communication (PLC) is a prominent candidate for smart grid communications in the low-voltage grid at low operational costs. However, the power-line channel is fairly harsh in terms of time-variance, frequency selectivity, and observable impulsive and narrowband noise sources. These unpredictable phenomena motivate selective measurement campaigns in addition to common channel modeling. While previously published measurement studies were fairly limited in duration, we report on a measurement setup for capturing power-line channels over weeks and show measurement results highlighting day-dependent channel effects on selected communication links. Furthermore, previous performance simulations are typically based on simplified channel models and limited in terms of the detail level at the physical layer or lack a consideration of higher-layer protocol overhead. We present a novel simulation methodology which is based on detailed physical-layer simulations exploiting measured, time-varying channel data, and incorporates protocol overhead models for transport-layer throughput estimation. Exemplary simulation results include the newest, commercially available narrowband PLC standards in their latest version, that is ITU-T G.9903 (G3) and G.9904 (PRIME), as well as IEEE 1901.2.

A temporal compressive resource allocation technique for complexity reduction in PLC transceivers

AbstractThis work introduces a novel resource allocation technique for dealing with linear and periodically time‐varying power line channels when an orthogonal frequency division multiplexing scheme is applied. By exploiting the correlations within one cycle of the mains signal, among cycles of mains signal and a combination of these connections, the proposed technique can offer three distinct trade‐offs between computational complexity reduction and data‐rate loss. Numerical results, which are based on measured data, are used to analyse these trade‐offs, when these inter‐cycle and intra‐cycle relationship are taken into account. Also, we verify that the use of the normalised signal‐to‐noise ratio incurs very low performance degradation, and because of computational complexity rationale, its use is strongly recommended. Additionally, we show that those cases, in which the correlations among the cycles of the mains signal is relevant, offer the best trade‐off between computational complexity reduction and data‐rate loss. Finally, we show that the proposed technique can achieve the optimal data‐rate and offers substantial improvements in terms of computational complexity when compared with existing approaches, including the Institute of Electrical and Electronics Engineers 1901 standard. Copyright © 2015 John Wiley & Sons, Ltd.

Image transmission using unequal error protected multi‐fold turbo codes over a two‐user power‐line binary adder channel

Impulsive noise is one of the major challenges for reliable transmission over power lines. Interleavers provide higher protection against the impulsive noise by dispersing information across the channel and spreading the burst of errors over multiple codewords. Multi-fold turbo (MFT) coding is a technique that improves the communication reliability using multiple interleavers. In the MFT codes, each data subsequence is equally protected. For applications in which data constitute information with various levels of importance, it is intuitive to offer the more important subsequence, a stronger protection. A modified form of the MFT codes capable of providing unequal error protection over a two-user power-line binary adder channel is proposed here. As a benchmark, two test images are transmitted across the channel. The trellis-based iterative algorithm is modified for the two-user scenario to decode the received signal. The simulation results show a gain of 1.5 dB for the modified MFT code over the conventional turbo codes for each of the transmitted images. A gain of 2 dB is also recorded for the most protected component of each image over the least protected components.

On the Capacity of Narrowband PLC Channels

Power line communications (PLC) is the central communications technology for the realization of smart power grids. As the designated band for smart grid communications is the narrowband (NB) power line channel, NB-PLC has been receiving substantial attention in recent years. Narrowband power line channels are characterized by cyclic short-term variations of the channel transfer function (CTF) and strong noise with periodic statistics. In this work, modeling the CTF as a linear periodically time-varying filter and the noise as an additive cyclostationary Gaussian process, we derive the capacity of discrete-time NB-PLC channels. As part of the capacity derivation, we characterize the capacity achieving transmission scheme, which leads to a practical code construction that approaches capacity. The capacity derived in this work is numerically evaluated for several NB-PLC channel configurations taken from previous works, and the results show that the optimal scheme achieves a substantial rate gain over a previously proposed ad-hoc scheme. This gain is due to optimally accounting for the periodic properties of the channel and the noise.

Analysis and Experimental Evaluation of Power Line Transmission Parameters for Power Line Communication

Abstract The article describes a way of evaluating the power line channel frequency response and input impedance by means of the linear time-invariant (LTI) power line generator. Two possible methods are introduced for the calculation of primary parameters: the first method depends on the physical realization and physical dimension of the cable, and the second method is derived from the data provided by typical electrical cable manufacturers. Based on these methods, a comparison of transfer functions was made. This is followed by measurement evaluation and numerical verification on a simple topology

Indoor Data Transmission Over Ubiquitous Infrastructure of Powerline Cables and LED Lighting

Ubiquitous powerline cables and visible light optical channel is utilized for data transmission in indoor applications. In this work, multipath and noisy powerline channel is integrated to indoor optical AWGN channel and besides experimentally measurement the radiated power from white LED the performance of integrated system in terms of OFDM signal power versus BER is also studied. The results shows the system has the data rate more than 28 Mbits/second with the bit error rates lower than 10-6 which outperforms the currently exist systems. So the new integrated system can be considered as a good alternative for other indoor wireless system counterparts

DEVELOPMENT AND TEST OF BLIMP-BASED COMPACT LIDAR POWEWR-LINE INSPECTION SYSTEM

Abstract. This paper introduces a compact LIDAR system designed to inspect overhead transmission line for maintenance purposes. This LIDAR system is carried by a small unmanned helium airship, which is guided by GPS and laser ranging to fly automatically along the power-line over a limited distance. The 3D coordinates of the power line, power tower and power line channel features are gathered by LIDAR. Test have been accomplished using this blimp-based compact LIDAR power-line inspection system. Its inspections of a 500kV power lines also shows the high efficient inspection, less risk to personnel and more inspections per day compared with manual inspection.

Structural Analysis of Efficient Error Control Scheme in PLC Environment

Turbo codes are attractive compared with Low Density Parity Check (LDPC) codes for Forward Error Correction (FEC) applications mainly due to their better performance, specially at low Signal-to-Noise Ratio (SNR) as are common in Powerline channels. Turbo Code is patented hence it is costlier for HomePlug device so it cannot be used. For small block length other code like LDPC which gives better performance as Turbo Code but at low SNR. Complexity of LDPC is increased when block length increase and it works well with low code rate. Complexity of Polar code is not increase even though its block length increases. The objective of this paper is to implement Polar code on PLC Channel to reduce the complexity and improve BER using specific Block Length.

Bit error rate of RS coded BFSK in broadband powerline channels with background Nakagami and impulsive noise

Power line communication (PLC) systems are being standardized over the globe and some of these standards recommended frequency shift keying (FSK) as their modulation choice. Broadband transmission over a PLC channel is mainly affected by the ever-present background noise and the occasional high-amplitude impulses. It has been recently found that the background noise in PLC can be suitably modelled with Nakagami-m distribution while a standard model for characterizing impulses is to assume Gaussian distributed amplitude and Poisson distributed arrivals. Considering such a model, at first, simple analytical bit error rate (BER) expressions of uncoded binary FSK (BFSK) signals are derived in the paper. The derived expressions are simple, involve only elementary functions, and the analytical BER values match perfectly with computer simulations. Next, a unified analytical framework is presented for evaluating BER when a Reed Solomon (RS) code is used to mitigate the noise effects. The results reveal that when the signal to background noise ratio (SBNR) is low, there is a clear impact of the noise parameter m and the choice of demodulation method (coherent/ non-coherent) on the error performance of the coded system. On the contrary, at higher SBNR, impulsive noise dominates over background noise, and these effects vanish as the BER curves become flat. Numerical evaluations dictated that by allowing a lower code rate (0.7) this error floor may be reduced significantly (up to 10−15). Further, the code gain of the system was found to be an inverse function of the code rate and codeword length.

The Impact of Statistical Noise Modeling on the Error-Rate Performance of OFDM Power-Line Communications

In this paper, the impact of statistical noise modelling on the error performance achieved by orthogonal frequency-division multiplexing (OFDM) over indoor broadband power-line channels is investigated. Different classes of statistical models suitable to represent power-line noise are illustrated and their impact on the error performance of a specific OFDM system is assessed via computer simulations. Numerical results are compared with the error performance provided by the same system in the presence of measured power-line noise; this is evidence that a realistic indication of error performance can be achieved only if the power spectral density of the adopted noise model exhibits a good match with that of the measured noise. In practice, this result can be achieved by modeling the power-line noise as a moving average random process of proper order; however, a satisfying match can be achieved as well if other simple noise models available in the technical literature are adopted.

Particle filtering based channel estimation in OFDM power line communication

Particle filtering (PF) algorithm has the powerful potential for coping with difficult non-linear and non-Gaussian problems. Aiming at non-linear, non-Gaussian and time-varying characteristics of power line channel, a time-varying channel estimation scheme combined PF algorithm with decision feedback method is proposed. In the proposed scheme, firstly the indoor power line channel is measured using the pseudo-noise (PN) correlation method, and a first-order dynamic autoregressive (AR) model is set up to describe the measured channel, then, the channel states are estimated dynamically from the received signals by exploiting the proposed scheme. Meanwhile, due to the complex noise distribution of power line channel, the performance of channel estimation based on the proposed scheme under the Middleton class A impulsive noise environment is analyzed. Comparisons are made with the channel estimation scheme respectively based on least square (LS), Kalman filtering (KF) and the proposed algorithm. Simulation indicates that PF algorithm dealing with this power line channel estimation difficult non-linear and non-Gaussian problems performance is superior to those of LS and KF respectively, so the proposed scheme achieves higher estimation accuracy. Therefore, it is confirmed that PF algorithm has its own unique advantage for power line channel estimation.

Effective Noise Cancellation Using Single-Carrier FDMA Transmission in Power-Line Channels

© 2014 IEEE. In power-line channels, impulsive noise (IN) is commonly reduced using a blanking technique in which the received signal is zeroed whenever it exceeds a certain threshold value. Determining an appropriate threshold, however, is critical to the performance of this technique as erroneously blanking unaffected parts of the signal will significantly degrade system performance. In this paper, we show that the performance of this technique is sensitive not only to the blanking threshold but also to the transmitted signal's peak-to-average power ratio (PAPR). With this in mind, we propose to implement single-carrier FDMA (SC-FDMA), which inherently has low PAPR, and address the issue of optimizing the blanking threshold for such a technique. The results reveal that significant improvements can be achieved with respect to the probability of blanking error, as well as achieving up to 4 dB signal-to-noise ratio (SNR) improvement relative to the conventional orthogonal frequency-division multiplexing case. Furthermore, it will be shown that in some cases of SC-FDMA, not only can a significant SNR enhancement be achieved but it is also possible to optimally blank IN irrespective of the noise characteristics.

The Channel Characteristic and AMR Field Trial Results in China Distribution Grid

Power line communication (PLC) has received much attention recently because of the need of reliable and automatic metering, In this paper we present a comprehensive study over the use of PLC in China. We begin with some background including the distribution grid topology, the power line channel environments, and the deployment of PLC network. Then we show some field test results of PLC-based meter-reading in a high frequency band. In addition, a suggestion how to improve G3-PLC is presented which can adapt China grid better.

A Methodology for Estimating Frequency Responses of Electric Power Grids

Currently, there is a lack of standard methodology to characterize frequency responses of electric power grids for power line communication purpose. As a result, fair comparisons among measurement campaigns carried out in different parts of the world are missing. Aiming at to deal with this issue, this contribution discusses a complete sounding-based methodology to estimate frequency responses of electric power grids combining sampling frequency offset error estimation and correction, timing synchronization, channel estimation, and channel estimation enhancement techniques. The effectiveness of this methodology is validated by using well-known power line channel models, as well as measured ones, covering the frequency band from \(1.7\) up to \(50\) MHz. The attained results show that the methodology provides estimates in shorten period of time in comparison with the network analyzer based methodology and because of that it is capable of characterizing the periodically and time-varying behavior of electric power grids. Additionally, it is shown that the methodology can be successfully applied to characterize frequency responses of electric equipment and, as a consequence, it is very useful for both power line communication and power system applications.