In-band full-duplex (IBFD) draws significant attention in many communication systems since it can improve spectral efficiency and data rates. Recent research activities in broadband power line communication (BB-PLC) also considered IBFD. However, implementation of IBFD for BB-PLC is highly challenging due to the harsh nature of PLC channels. Besides the remote link estimation, the estimation and cancellation of self*interference (SI) signals are necessary. In many research works, the feasibility of IFBD was analyzed by comparing signal-to-interference plus noise ratio (SINR) in the half-duplex and the full-duplex modes. However, to enable sufficient SI cancellation, very accurate SI channel estimation is needed, which may require the transmission of additional training symbols. In such a case, there is a trade-off between time spent on training and time used for data transmission. In the IBFD case, it is unclear what the optimal number of training symbols should be and what the effective throughput is. This paper investigates this problem and estimates the achievable throughput for IBFD in SISO, SIMO, and MIMO scenarios. Firstly, we perform Monte Carlo simulations over a database of measured channels to analyze bit allocation and its dependence on the number of training symbols. Secondly, we look for the optimal proportion between the training period and payload transmission to achieve the best throughput. Finally, we compute the average bit error rates, throughput, and bidirectional throughput gain.
The wired channel model, including the power line communication (PLC) one, is often derived using the voltage gain, i.e., the ratio between its output and input voltages. Although this modelling approach offers information, it is often incomplete and can be dependent on the front-ends and connections used to measure such a channel. To overcome this limitation, this paper discusses how an invariant channel model can be defined and retrieved, i.e., a model that completely and intrinsically describes the transmission medium and that is not affected by the boundary conditions, e.g., the hardware blocks that are necessary to carry out measurements such as the couplers and cables used in PLC. In this paper, we firstly describe the theory that stands behind the problem, and then we validate it with numerical results in a real wired communication scenario.
This paper proposes a statistical channel model for indoor single-input single-output (SISO) power line communications (PLC) in the 2–80 MHz frequency band. The model follows a purely top-down strategy, since it makes no physical assumptions about the underlying power network. The frequency response is modeled as a multivariate random variable (RV) whose parameters are derived from the statistics of a set of 458 channels measured in different European countries. To this end, we firstly assess the log-normality of the amplitude response and discuss the difficulties associated to the estimation of the covariance matrix of the amplitude response at different frequencies, highlighting the need for using a regularization method. The parameters of the model are then derived by approximating the statistics of the measured channels by means of novel analytical expressions. Finally, the validity of the proposal is evaluated by comparing the average channel gain, the delay spread and the coherence bandwidth of the channels generated according to it with the ones of the measured channels and of channels generated using another top-down statistical model proposed in the literature.
This paper proposes a general methodology on the topic of diagnostic and localization of noise source within the area of one transformer station based on G3–PLC technology in the Cenelec–A band (36–91 kHz). Different noise types and noise sources common for Narrowband-Power Line Communication (NB–PLC) are described together with the character of the measured communication channel - the cable between the junction box and the transformer station. Description of various measurement and analysis approaches is included. Present noise was evaluated by the drop of signal-to-noise ratio (SNR), by the measurement of data loss during the file transfer and by the spectral analysis of the power line with the spectrum analyzer and with the PLC analyzer. This article reveals a significant noise source that prevented the communication of hundreds of smart meters with the data concentrator (DC) located at the transformer station. The authors also propose a set of 4 mitigation solutions for this non-standard situation ordered by the time difficulty of implementation to this PLC network.
The dynamic nature of power line channels, has made it difficult to effectively estimate power line link quality. Incorrect estimation can lead to data packet retransmissions and even unnecessarily to the creation of new routes consuming additional communication channel bandwidth or flooding the communication network. G3-PLC and Hybrid protocol standard is based on instantaneous Link Quality Indicator (LQI) estimation to determine the suitable modulation schemes (ROBO, BPSK, QPSK and 8PSK), but the instants estimation may not be able to foresee the impending channel state which may result to communication impairment. In this context, a promising approach to estimating channels is the data-based link quality classifier using machine learning (ML) algorithms. This article outlines a measurement campaign using a local network of smart meters, collecting link quality data, and implementing ML prediction models. Hence, we present models for classifying the PLC link quality in different modulation patterns. Accuracy performance is compared against various classification models such as LR (Logistic Regression), SVM (Support Vector Machine), RFC (Random Forest Classifier), and ANN (Artificial Neural Networks) algorithms. The link quality classifier shows a clear improvement in the modulation selection process as the classical approach in the G3-PLC protocol.
Existing setups to measure the attenuation and impedance behavior of EMC filters mostly work off line, without any load current flowing through the filter and with terminations either at 50 Ohms or using a standard LISN. With an ever increasing number of filters required on the network to keep larger PLC rollouts stable, their impedance and attenuation in realistic operating conditions becomes an increasingly important, but hard to measure specific. A measurement system design is presented to measure an EMC filter’s impedance and attenuation in the narrowband-PLC range up to 1 MHz while connected to mains, at high load currents and with realistic terminations. Through a comprehensive, system level design approach the measurement system’s dynamic, accuracy and repeatability are increased, while its handling is less error prone and the overall safety of the system’s usage is increased.
Outdoor-to-indoor radio penetration is the main bottleneck for indoor reception of mobile services. Nowadays, Wi-Fi is commonly used in wireless indoor networks but limited through interference from neighboring networks through walls and limited available spectrum. A possible new approach is to add optical wireless communication, also called light fidelity (LiFi), to modern indoor wireless networks. However, economic analysis indicates that the main cost driver for LiFi is the dense wired infrastructure. In this paper, we investigate a feasible solution to distribute data to LiFi access points through power line communication (PLC), reducing the required infrastructure cost. We describe the two most common approaches, based on decode and forward as well as amplify and forward. We then show a first proof-of-concept implementation and throughput measurements of the latter approach. The implemented proof-of-concept is based on existing chipsets and off-the-shelf components, theoretically allowing for mass production.
The characterization of EMI filters is mostly performed off-line, without a load and with 50Ω terminations or standard LISN. This leads to a different filters behavior as when connected to the mains. Due to growing PLC demand as part of the digitalization of the power grid, the impedance and attenuation behavior of the filter under realistic conditions becomes increasingly important.An on-line PLC filter characterization system requires a calibration to gain accuracy and minimize disturbance. In this paper, a calibration method of such a system to characterize EMI filters under realistic conditions in the narrowband-PLC range up to 1MHz is presented. Problems with former calibration approaches are discussed and the improvements are shown.Index Terms: Calibration, EMI filter, PLC filter
The performance of Broadband Powerline Communication is highly dependent on cable attenuation. Field trials in past research projects showed strong dependencies between Signal-to-Noise-Ratios and utilization of low voltage grids. In addition, seasonal Signal-to-Noise-Ratio fluctuations have been measured. To investigate if these observations are caused by the cable temperature, we developed a measurement setup for measuring the attenuation of different low voltage cables under variation of temperature. We used a DC-source to heat up the cables under test and measured the attenuation during the cooling process. The results show that cable attenuation has a significant monotonous dependency on temperature, increasing with frequency. Hence, calculations of channel transfer functions need to consider cable temperature as an independent influencing variable.
As a previous step before the rollout of a pilot Broadband Power Line Communications (BB-PLC) network, this paper describes the measurement campaign carried out for the characterization of the Low Voltage (LV) electrical grid as a transmission medium in terms of grid access impedance, attenuation, and Non-Intentional Emissions (NIEs). First, the main reasons why BB-PLC is the technology selected for the development of new Smart Grid (SG) applications over the LV distribution grid are discussed. Second, the pilot network to be rolled out is described. Then, the measurement systems designed for the assessment of the grid impedance, attenuation, and NIEs are presented, as well as a brief description of the selected locations that correspond to nine scenarios of the LV distribution grid in a town in the north of Spain. These locations represent several grid topologies and areas of different population densities. Finally, some results obtained in the field trials are shown, which demonstrate the importance of a prior characterization of the LV grid as a transmission medium for an efficient planning of a BB-PLC deployment. These results are only a representative selection of the data obtained in the measurement campaign and, thus, further analysis is required to draw accurate conclusions.
This paper reviews the main changes in the new version of the PRIME standard, especially its evolution towards a hybrid system combining Power Line Communications (PLC) and Radio Frequency (RF). In particular, the current simulation results are presented by comparing the system performance in three Advanced Metering Infrastructure (AMI) use cases with each other and with the results of a previous work analyzing the new version of the G3 standard. The first case is an environment where all nodes are PLC and the PLC noise level allows connectivity in all areas of the site. The second case is an environment where all nodes are PLC+RF, the PLC noise level does not allow connectivity in some areas, and the system needs to switch to RF. The third case is an environment where half of the nodes are PLC+RF and the others half are RF only. This would be the situation of a system with electricity meters, which are hybrid PLC+RF, and gas or water meters, which are RF only. To evaluate their performance, some Key Performance Indicators suitable for these applications are introduced.
Power Line Communications (PLC) are the communication technology at the base of Smart Grid operation. They rely on the preexisting infrastructure that enables power delivery. To evaluate performance of this technology, usually the main metric that is looked at is the SNR at the receiver in a link. In order to predict this performance, different approaches can be used: bottom-up approaches implement physical models to employ characteristics of the medium to understand its channel response, while top-down ones focus on data from measurements to identify patterns and create stochastic models.Due to a hard-to-model noise and channel, these approaches come up short. In this work, we consider measurement data from Low Voltage distribution networks, we show how the classic SNR value relates to the network topology; additionally, we discuss how coverage in terms of distance from the central element of the network can be used as a performance indicator and how it relates to a novel, easy-to-compute density factor.
ITU-T G.hn technology is a well-known standard in the field of home networking transmissions. For a long time, it has been used a high-quality link for video services (e.g., IPTV) and as a connectivity extender (cable replacement). However, the flexibility of the technology allows to use it in new heterogeneous approaches for home networking and in new contexts of application. These new uses of the technology are driving evolutions of the standard. This paper draws the general picture of the status of ITU-T G.hn technology and the future trends that are expected in the home distribution and that may impact the role of G.hn technology in the home networking. Different use cases, requirements and optimizations are discussed. This paper presents some of the technical challenges that the industry will face in the coming years. These technical challenges should be addressed by the relevant standardization groups with the help of academia.
In this paper, we will present the results of a field trial based on a PLC to xDSL Dynamic Interference Mitigation (DIM) mechanism. The DIM algorithm, which has been included into the firmware of commercial in-home PLC devices, aims to improve the ability of a peaceful coexistence between PLC and xDSL systems.Further, we will present a laboratory measurement test system, which has been set up to debug and proof the concept of the DIM feature. We will look to the laboratory measurement test results, which have been studied prior rolling out the DIM enabled firmware for the field trial.The results from field study will show that xDSL lines, which are suffering from PLC signal ingress, become more stable and better performing when implementing the DIM mechanism. It will also be shown that only a small percentage of xDSL connected end-users are affected by signal ingress from PLC devices into the phone-line.
Multiple codewords of non-binary permutation codes, selected with the maximum Hamming distance between them, are used to increase the spectral efficiency of the multicarrier orthogonal frequency division multiplexing (OFDM) with Mary frequency shift keying (M FSK) scheme. In addition, the codes can assist with the selection of a set of unique subcarrier permutations. The subcarrier combination makes the coded scheme suitable for a multicarrier, multi-user access technique. Over a powerline communication channel with impulsive noise, the peak-to-average power (PAPR) of the coded and uncoded schemes are compared. In addition, the symbol error rate (SER) performance of the single-user and multi-user schemes are shown for different threshold detection values and shared power allocation in the multi-user scheme. The SER performance is based on minimum distance, hard-decision, joint subcarrier decoding, with results showing a degradation in the multi-user, multiple permutation scheme. This performance is further improved using a soft-decision decoder, which uses the soft samples from the output of the channel.
To accurately determine and estimate the channel properties of Powerline Communication (PLC) structures in advance, e understanding the physical properties of the existing infrastructures individual components is required. By measuring the attenuation, impedances and noise levels within the power grid network, a deeper knowledge of the different components influences and the connection quality between PLC devices can be evaluated. This paper gives an overview about the challenges to measure these critical data. Designing a fully automatic multiport network analyzer with PLC capabilities and remote access allows creation of a measurement system enabling to gain long time data of the physical properties in low voltage power grid systems. Using standard commercial components, developing an analog front end (AFE) and programming of a pseudo real time environment for the firmware, an affordable and fast option to classical network analyzers is constructed. Finally, first results of a real network topology measured with this system are presented.
The re-use of channel estimation performed by power line communication (PLC) modems for monitoring of cable health conditions has recently been investigated in several works. In particular, cable diagnostics solutions based on machine learning techniques have been shown to process the PLC channel-estimation samples intelligently to differentiate fault conditions from the benevolent load changes. Previous studies have been based on synthetically generated training and test signals to optimize and validate the machine learning models. To deal with the mismatches between the purely synthetically generated signal samples and those encountered in a real implementation, in this paper, we propose S-parameter measurement aided generation of channel estimation samples. Specifically, we describe the behaviour of our device under test (DUT) through its S-parameter measurement and synthetically generate varying terminal load conditions. Then we train and use machine learning models to determine the health of the DUT. We describe the proposed approach and apply it to data obtained from laboratory measurements.
Orthogonal Frequency Division Multiplexing (OFDM) leads to a high Peak-to-Average Power Ratio of the signal. This requires high power reserves at the transmitter and reduces the capabilities of impulsive noise cancellation at the receiver. To overcome this drawback, several techniques exist to lower the Peak-to-Average Power Ratio of the signal. This paper compares nine different techniques regarding their results in Peak-to-Average Power Ratio reduction, bit error rate increase, notch depth, out-of-band distortion, signal power increase, loss in data rate and computational complexity. Five techniques provide good results, but each of them has a unique drawback, so it is still required to pick the best one during individual OFDM system design.
As the LED lamps are naturally connected to the powerline, the integration of powerline communication (PLC) and visible light communication (VLC) seems to be trivial. In fact, cascading VLC to PLC is not very simple especially because their channels are not designed for communication purposes. The PLC and VLC channels suffer from severe attenuation with increasing frequency. Thus, the cascading of these two channels will lead to a very limited bandwidth which can complicate the PLC-VLC integration. Few experimental studies are carried out to prove the feasibility of PLC-VLC integration, particularly those based on the amplify and forward (AF) relay. Therefore, PLC-VLC broadband transmission is demonstrated in this paper without making any changes to the transmitted PLC signal before traveling through the optical system. A theoretical study is also carried out to design LED luminaires capable of providing both lighting and communication. This study extrapolates the experimental results of the small-scale PLC-VLC testbed to design a PLC-VLC system for typical indoor applications.
We have already shown in earlier publications that reciprocity of power-line channels, expressed by, e.g., S12 = S21 using scattering parameters, can provide the desired common randomness for physical layer key generation. We had used minima or maxima of those transfer S-parameters to select possible keys. The tree-like power-line topology with bridge taps that are imperfectly terminated, possibly just left open, provide the means to create deep notches and, of course, local maxima in between. Using those positions, however, does not work well under noise conditions and power-line channels are known for their stationary and non-stationary disturbances. Minima will just be filled by noise, maxima that are wider than the minima experience a ripple thereby making it difficult to obtain identical positions under uncorrelated noise at the legitimate users’ ends. To solve this issue, in here, we propose to instead use the amplitude values at maxima positions. Disturbances there are directly related to the noise amplitudes. High maxima and corresponding key sequences resulting from amplitude quantization of the transfer characteristic are then less error-prone. Further improvements to reduce noise effects are obvious, just like averaging measurements, smoothing over frequency, or just only accepting measurements above certain thresholds. Quantization of amplitudes is carried out in log domain and mapping to bit patterns is realized in a cyclic fashion together with Gray coding. Key reconciliation is realized by shifting measurements into the middle of quantization intervals.
