In-home Power Line Communication Research Articles

Physical-Layer Secret Key Generation in Power Line Communication Networks

Due to the inherent broadcast nature, power line communication (PLC) is vulnerable to eavesdropping. Traditionally, the secret keys are generated/distributed by pre-shared keys, adaptive tone mapping, or asymmetric encryption algorithm. All of these methods face problems such as high computational complexity, high cost, or less security. To solve the problem, a physical layer security (PLS)-based secret key generation (SKG) scheme aiming at the typical in-home broadband PLC network is proposed in this paper. However, the slowly time-varying characteristic and the serious noise interference in PLC channels will degrade the performance of the PLS-based SKG scheme. To break through the limitation of the randomness of PLC channels, two-way random signals are introduced. To make the SKG system more resistant to noise, the channel frequency response-based adaptive quantization (CFR-AQ) algorithm is designed, in which the amplitude threshold and the quantization level are adaptive to the noise power and the target key disagreement rate (KDR) to maximize the key generation rate (KGR). The performance is analyzed in two scenarios: single eavesdropper and multiple eavesdroppers. The simulation results demonstrate that the proposed scheme has a good overall performance in terms of KDR, KGR, and security with a lower complexity in the presence of single or multiple non-collusive eavesdroppers, and it can be regarded as an alternative solution to generate secret keys in PLC networks.

Performance Analysis of MIMO System over an In-home PLC Channel

Power line communication (PLC) system is an attractive technology for Smart Grid applications. One key benefit of PLC is its low installation cost because, in PLC technology, we do not need to install any extra cable to extend a network due to the accessibility to low voltage power network. Orthogonal frequency division multiplexing (OFDM) is widely used in PLC networks. Currently, Multiple Input Multiple Output (MIMO) technology is one of the processing techniques appropriate to PLC networks, allowing high data rate. In this work, the MIMO-OFDM system is established to provide better performance over the PLC system by providing communication links with substantial diversity and capacity. However, adapting MIMO to the PLC network involves solving several issues such as MIMO PLC channel modelling and optimisation of the modulation parameters. In this paper, we present measurements results of the transfer function and impulsive noise in the extended frequency range 2-100 MHz. In the simulation part, we evaluate the performance of the proposed receivers in 2×2 MIMO-PLC channels. It is shown that the minimum mean square error (MMSE) receiver can be one of the appropriate candidates for MIMO PLC channels due to its bite error rate (BER) characteristics under impulsive noise.

Physical Layer Security of In-Home PLC Systems: Analysis Based on a Measurement Campaign

This article investigates the physical layer security (PLS) of a broadband in-home power line communication (PLC) system when a malicious and passive PLC device tries to eavesdrop upon private information sent by a PLC transmitter to a legitimate PLC receiver. In this setting, the ergodic achievable secrecy rate, secrecy outage probability, effective secrecy throughput, and wiretap code rates are numerically evaluated with the use of a data set obtained from a measurement campaign carried out in several Brazilian houses. This data set comprises PLC channel estimates and measured additive noises considering four distinct sets of transmitter, legitimate receiver, and eavesdropper positions. Numerical results, covering three distinct frequency bands (1.7–30 MHz, 1.7–50 MHz, and 1.7–86 MHz), quantitatively show, in practice, the level of vulnerability of broadband in-home PLC systems in terms of PLS and offer some directions for an appropriate design of PLC modems to improve PLS.

Cache-Enabled Power Line Communication Networks: Caching Node Selection and Backhaul Energy Optimization

Power line communication (PLC) advances smart grid technology by offering a convenient and efficient data transmission service. However, due to the severe PLC channel condition and ever-growing traffic load in the PLC backhaul, reliable communications among widely distributed in-home PLC users is highly energy-consuming. In this paper, we put forth a cache-enabled PLC network comprising a single master base station (MBS) and mutiple slave base stations (SBSs) each bound with an in-home network to alleviate the backhaul traffic load and reduce the backhaul energy consumption. In the proposed scheme, the SBSs with the local caches pre-download the popular contents from the MBS through the PLC backhaul, and the in-home users request the contents from nearby caching nodes (CNs) or the MBS. Apart from the cache-enabled PLC design, our contributions also lie in the selection of CNs and optimal content placement algorithm. First, we propose a selection algorithm to activate the SBSs with high influence as the CNs, according to a directed graph that models the requesting relations among all SBSs. Second, we design an optimal content placement algorithm to minimize the backhaul energy consumption for the contents with different sizes and user preferences. Simulation results show that our cache-enabled PLC scheme with the caching node selection and optimal content placement can dramatically reduce the backhaul energy consumption, compared with the existing caching strategies.

PLC Systems Under the Presence of a Malicious Wireless Communication Device: Physical Layer Security Analyses

This paper investigates the physical layer security (PLS) of a broadband in-home power line communication (PLC) system when a malicious wireless device tries to eavesdrop private messages exchanged between two PLC devices. Such a security issue arises when electric power circuits, which are used for data communication, are constituted by unshielded power cables. In this regard, the hybrid wiretap channel model for formulating achievable secrecy rate and secrecy outage probability is considered. Additionally, a data set of channel estimates and measured additive noises obtained from a measurement campaign carried out in several in-home facilities is used for providing practical results, which can offer direction for dealing with the security aspects of broadband in-home PLC systems in the physical layer perspective. The attained results show high values of secrecy outage probability for all chosen values of target secrecy rate and total power transmission (practical and theoretical) when the PLC devices are far from each other and the eavesdropper is close to the PLC transmitter (i.e., the distance is shorter than 2 meters). Overall, the numerical results show that the vulnerability of broadband in-home PLC systems, in terms of PLS, is relevant when practical values of total transmission power apply. Therefore, a rethinking of the use of unshielded power cables or new designs of the broadband in-home PLC system deserves special attention for ensuring security at the physical layer.

Statistical modeling of magnitudes of Brazilian in-home PLC and hybrid PLC-wireless channels

This paper focuses on the statistical modeling of the magnitudes of frequency responses of Brazilian in-home power line and hybrid power line-wireless in the frequency band from 1.7 up to 100 MHz.122The present work is based on the master thesis (T.F. do A. Nogueira, 2018) [1].In this regard, a method to obtain statistical models is detailed. The statistical modelings of these channels are based on measured data sets, which were acquired through a measurement campaign carried out in Brazilian residences. Numerical results show that Beta and Log-Normal are the best statistical distributions for modeling magnitudes of the frequency responses of Brazilian in-home power line and hybrid power line-wireless communication channels, respectively. Also, these magnitudes are non-stationary random processes.

Performance evaluation for medium voltage MIMO-OFDM power line communication system

Power line communication (PLC) provides intelligent electrical functions such as power quality measurement, fault surveys, and remote control of electrical network. Most of research works have been done in low voltage (LV) scenario due to the fast development of in-home PLC. The aim of this paper is to evaluate the link-level performance of a medium voltage (MV) MIMO-OFDM communication system based on transmission link under underground power line channel. The MIMO channel is modeled as a modified multipath model in the presence of impulsive noise and background noise. We first perform a measurement on the practical MV MIMO channel parameters for a section of buried cable of 1 km long in Ganzhou city, Jiangxi province, China. Based on the measured channel, we design the frame structure based on an IEEE standard for broadband over power line networks [1] to support MV MIMO-OFDM transmission. According to designed frame structure, we design an encoder and a decoder for a dual binary tail-biting turbo code and optimize some key decoder parameters for low bit error rate performance. Finally, the link-level performance for both spatial multiplexing and spatial diversity are evaluated. Numeral results show that MV MIMO-OFDM is a promising approach to provide both high data rate and link reliability for PLC.

A Novel Precoding and Impulsive Noise Mitigation Scheme for MIMO Power Line Communication Systems

Power line communications (PLCs) enable new and flexible networking functions in smart grids. However, due to the high attenuation and interference, it is a great challenge for PLC to achieve reliable and high data rate transmissions. Thus, we propose a multiple-input multiple-output (MIMO) architecture to improve the reliability and data rate for PLC networks. In viewing the data rate requirements of in-home PLC network systems, we develop a precoding scheme to maximize the system throughput. In harmonizing to the proposed precoding scheme, the closed-form of the sum data rate of the PLC-MIMO channel is derived. To improve the communication reliability, we propose a partial transmission sequence (PTS) based algorithm to mitigate the noise in PLC channels. The closed-form of the symbol error rate (SER) is derived according to the probability density function of the impulsive noise in PLC channels. Simulation results demonstrate that the proposed precoding scheme achieves a better throughput when compared to the conventional precoding schemes. Furthermore, the PTS-based noise mitigation algorithm significantly improves the SER performance of PLC links.

Statistical Modeling of Brazilian In-Home PLC Channel Features

This paper deals with the statistical modeling of key features of power line communication (PLC) channels that are necessary for designing data communication systems that operate over theses channels. The key features are average channel attenuation, root mean squared delay spread, coherence bandwidth and coherence time. All these features were estimated from in-home PLC channels measured in seven distinct and typical Brazilian residences. Assuming that each feature is a random variable, four criteria (i.e., maximum likelihood estimate and three different information criteria) are used to select the statistical distribution that offers the best fits for each attribute. During this process, the symmetry and asymmetry of the histogram associated with each feature is pointed out. The reported results focus on three frequency bands, namely: from 1.7 MHz up to 30 MHz, from 1.7 MHz up to 50 MHz and from 1.7 MHz up to 100 MHz, which are useful for with Europe, North America and Brazil. The findings report similarities and discrepancies with previous statistical models related to US and Europe and enables one to better design practical PLC devices.

First and Second-Order Semi-Hidden Fritchman Markov models for a multi-carrier based indoor narrowband power line communication system

The realization of a Semi-Hidden Fritchman Markov models (SHFMMs) for power line communication (PLC) channel is only practicable if combined with efficient algorithms for learning and inference. This article thus reports First and Second-Order SHFMMs for the bit error pattern at the output of an Orthogonal Frequency Division Multiplexing based system for in-home narrowband PLC applications. Accurate SHFMMs have been derived for a residential and laboratory environment using the efficient iterative Baum–Welch algorithm. The log-likelihood ratio plots, the error-free run distribution plots, the mean square error and Chi-Square (χ2) test validates the accuracy of the derived models. The reliability and accuracy of resulting models are confirmed by a close match between the measured bit error sequences and the model generated bit error sequences. The estimated Second-Order SHFMMs have been validated to be superior to the First-Order models, although at the expense of more computational complexity. Resulting models assist designers to speed up and facilitate the process of designing and evaluating novelties for PLC systems.

Throughput Analysis of Wavelet OFDM in Broadband Power Line Communications

Windowed orthogonal frequency-division multiplexing (OFDM) and wavelet OFDM have been proposed as multicarrier techniques for broadband communications over the power line network by the standard IEEE 1901. The windowed OFDM has been extensively researched and employed in different fields of communication, while the wavelet OFDM has been recently recommended for the first time in a standard. This paper is aimed to show that the wavelet OFDM, which basically is an extended lapped transform-based multicarrier modulation (ELT-MCM), is a viable and attractive alternative for data transmission in hostile scenarios, such as in-home power line communications (PLC). To this end, we obtain theoretical expressions for ELT-MCM of: 1) the desired signal power; 2) the inter-symbol interference power; 3) the inter-carrier interference power; and 4) the noise power at the receiver side. These expressions are used to derive the throughput. This paper includes several computer simulations that show that ELT-MCM is an efficient alternative to improve data rates in the PLC systems.

A cooperative modulation recognition: New paradigm for power line networks in smart grid

Power Line communication (PLC) is an attractive approach to provide information transfer services for future smart grids. However, since various modulations are adopted, it is a great challenge to add new nodes to collect the data from the devices or sensors in in-home PLC networks. In this paper, we propose an approach to automatically access to the PLC network by identifying the modulation of signals. To improve the correct recognition rate on identification of modulations, we propose a multiple input and multiple output (MIMO) based cooperative modulation identification scheme. After receiving the recognition results from accessing nodes, the central server makes the comprehensive and accurate recognition decision on the modulation of the PLC network. Furthermore, the fourth-order cumulants for multiple users are adopted as the feature for this modulation classifier. With the feature, we propose an improved modulation classification algorithm based on the maximum likelihood. Simulations show that a high detection rate and low false positive rate can be achieved as we employ the cooperative modulation identifying scheme and the improved recognition algorithm.

Sub‐channel assignment and link schedule for In‐Home power line communication network

To offer communication capability in an easy and simple deployment, power line communications (PLCs) have recently attracted interest from the smart grid. The effective sub-channel assignment can increase throughput of In-Home (IH) PLC networks with orthogonal frequency division multiplexing scheme distributed over low-voltage areas. Given a logical topology of an IH PLC network, the authors present a formulation to optimise the sub-channel assignment problem as a linear programming with an objective function of maximising the network throughput. It takes into account constraints of the network topology, interference and traffic fairness. According to the solution of the optimising sub-channel assignment problem, the scheduling algorithm of links to obtain channels is developed for every time slot. Evaluation demonstrates that the proposed approach performs much better in improving overall network throughput and ensuring the traffic fairness of network users than conventional ones.

Structured compressed sensing based narrowband interference elimination for in-home power line communications

The structured compressed sensing based framework for the estimation of NarrowBand Interference (NBI) in power line communication is proposed, which facilitates in-home interconnection and prevents the wired consumer electronics devices from contamination of NBI. To recover the NBI accurately, the Structured Compressed Sensing (SCS) theory is introduced, and the method of SCS based Temporal Differential Measuring (SCS-TDM) is proposed, which fully exploits the temporal correlation of NBI. By exploiting the repeated training sequences, the NBI measurements matrix is acquired. With the exploitation of the prior partial support information, a more effective greedy algorithm, structured prior aided sparsity adaptive matching pursuit, is proposed. The performance of the proposed algorithm is theoretically guaranteed, and simulation results validate that the proposed method significantly outperforms existing counterparts.

A Statistical Model of the In-Home MIMO PLC Channel Based on European Field Measurements

The multiple-input multiple-output (MIMO) technique is well known in the field of wireless communications, and has recently been proposed to increase the capacity of in-home power line communication (PLC) networks. MIMO PLC employs the protective earth in addition to the classical line and neutral wires to form a multi-sensor transmission channel. By considering the additional reception of common-mode signals, up to two simultaneous transmit ports and four receive ports can be considered. In order to develop new signal processing strategies optimally exploiting the MIMO propagation characteristics and to evaluate their performance, the accurate modeling of the transmission channel is necessary. This paper presents a comprehensive statistical model of the in-home MIMO PLC channel based on an extensive measurement data base collected in six European countries. The paper first analyzes the main MIMO PLC channel parameters, including path loss parameters and wideband parameters, such as the delay spread, coherence bandwidth, and small-scale statistics. A focus is then made on the MIMO correlation matrix, and its modeling using empirical statistical distributions. A fully parameterized channel model is then developed, with a particular emphasis on both the frequency fading structure of the transfer function and the correlation matrix between sub-channels. As a result, the proposed model generates random MIMO PLC channel realizations, statistically representative of the experimental observations.

A reliable opportunistic routing for smart grid with in-home power line communication networks

The topology of in-home power line communication (PLC) networks varies frequently, which makes traditional routing algorithms failure. To solve this problem, an end-to-end transmission time for remaining path (TTRP) metric-based opportunistic routing (TTRPOR) is proposed. Since a local broadcasting scheme is adopted, the algorithm can find the optimal path for forwarding packets in a dynamic PLC network. The closed-form of the outage probability for a PLC channel is derived to estimate the TTRP. It is proved that the average throughput can achieve maximum as the metric TTRP is utilized to sort candidate forwarding nodes. Numerical results show that the end-to-end throughput of networks with TTRPOR, outperforms that of the network adopting DSR and EXOR, especially for the case of varying-topology in-home PLC networks.

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.

Cooperative In-Home Power Line Communication: Analyses Based on a Measurement Campaign

This work focuses on analyses of cooperative protocols to enhance the performance of power line communication systems. Based on a measurement campaign and considering a sum power constraint, achievable data rates for amplify-and-forward (AF) and decode-and-forward (DF) protocols are analyzed. Similar investigations are performed for the maximum data rates attained using Hermitian-symmetric orthogonal frequency division multiplexing (HS-OFDM) together with equal gain combining (EGC), selection combining (SC) and maximal ratio combining (MRC) techniques. The influences of optimally and uniformly allocated transmission power and frequency bandwidth are are also analyzed and the efficiency of combination before and after equalization is compared. Results show that the relative distances among source, relay and destination nodes significantly impact system performance. Also, they reveal a range of total transmission power and bandwidth in which benefits can be verified. Among combining techniques, MRC and SC present similar results, but MRC offers a slightly better performance. In relation to computational complexity, SC is the most favorable. Maximum data rate analyses of HS-OFDM with frequency domain equalization based on zero forcing and minimum mean square error criteria show that the former scheme offers almost the same performance as the latter. Furthermore, it is shown that equalization after combination is more advantageous.

Performance evaluation of in-home broadband PLC systems using a cooperative MAC protocol

In this article, we present an in-depth analysis of cooperation benefits in power line communication (PLC) networks. In order to conduct our evaluation, we present a new, yet simple, cooperative medium access control protocol (CMAC). Our new CMAC protocol uses system nodes as relays adaptively, according to these nodes idleness or busyness. Moreover, the new protocol also explores path diversity offered by an in-home broadband PLC. We have conducted simulations, based on real packet error ratios of in-home networks, using a wide range of configurations. In sum, our results show that cooperation reduces packet loss ratio and improves goodput. For instance, in some scenarios, the protocol we proposed is able to enhance goodput up to 36% and reduce packet loss ratio up to 43% in comparison to a system without cooperative protocols. Moreover, our simulations allow us to delimit the most suitable scenarios to use cooperation. Based on our analyses, we can state the following: (i) improvements increase when frequency bandwidth increases; (ii) irrelevant improvement occurs if total transmission power is too high or too low; (iii) gains offered by cooperation are more relevant depending on relative node relay position in relation to nodes source and destination; (iv) the proposed protocol show improvements regardless of the choice between OFDMA-TDMA and TDMA-OFDM schemes, but improvements are higher when it is used together with the OFDMA-TDMA scheme.

In-Home Power Line Communication Channel: Statistical Characterization

A statistical characterization of the in-home power line communication channel is performed from the study of a wide set of measured channels in the 1.8–100 MHz frequency band. The study provides new insights on (a) the relation between the line impedance and the channel frequency response (CFR), and (b) on the spatial relation between the channels that share either the transmitter or the receiver outlet. Furthermore, it confirms the validity of some results presented in the literature that are limited to the 30 MHz band. The study comprises the analysis of the average channel gain, the root-mean-square delay spread and the coherence bandwidth, as well as the relation between such quantities and the phase of the CFR. Closed-form expressions are provided to model the quantities and their relations. Finally, the coverage, i.e., the relation between the maximum achievable rate and the distance, as well as the achievable rate gain offered by the use of the frequency band up to 300 MHz, are studied.