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International audience; This paper deals with fault detection and isolation (FDI) in complex embedded wired communication networks. The considered faults are soft faults which do not prevent the communication, but may evolve into hard faults, i.e. short or open circuit. A novel FDI method based on power line communication (PLC) transmission systems is proposed. In these PLC systems, the transmission coefficients between the source and each receiver are estimated for communication purposes using orthogonal frequency division multiplexing (OFDM). Health indicators and residuals are computed by comparing the online estimated transmission coefficients with the reference coefficients. A methodology for dealing with complex networks, such as bus networks, is proposed. It is based on the decomposition of the network into several Y-shaped sub-networks. Each of these sub-networks is monitored to detect the presence of a fault. The FDI method is first validated using real data extracted from a Y-shaped network test bench. Then, the proposed approach is validated on a more complex network using realistic simulated data.

International audience; Vehicular electrical wires and communication systems can be affected by faults. Depending on their severity, faults can be divided into two families: hard and soft faults. Hard faults indicate open/short circuits that can lead to serious breakdowns because they prevent the flow of energy or information. Even though soft faults do not have such severe impacts on the system, they may develop into hard faults in the long term, hence the need to detect them. In this paper, an unshielded twisted pair cable that undergoes a water-tree degradation is considered. A soft fault, which may correspond to the effect of a mechanical constraint on the cable, is introduced as a series resistor. The studied network is a tree-shape network composed of one source and multiple receivers, one at each end of a branch. Assuming that these receivers operate in a healthy state, to detect the fault, the transfer function from each receiver are monitored and a detection index is used. Another index, based on the comparison of the effect of the fault at each endpoint, is proposed to locate the affected branch. To summarize the detection and localization algorithm, a signature matrix is generated. Simulation results are presented to illustrate our approach.

Real time detection of intermittent or permanent faults which could appear on wired networks becomes a critical issue. Fault detection and localization methods are often based on reflectometry techniques but they need the implementation of dedicated devices. Furthermore, since they often use a wide frequency band, problems related to their electromagnetic compatibility with the environment may occur. If a power line communication is already implemented in the network, the objective of this paper is to study the proof of concept of a fault detection only based on the statistical properties of the received signals. Even without precise information on fault location, results of this approach could be interesting to decide to carry out a maintenance operation.

International audience; Power Line Communication (or PLC) enables the construction of a computer network on the electrical network. This work aims to study the impact of the electrical network topology on the performance of the Power Line Communication link in terms of different parameters that are achieved by using a measurement test bed. This measurement test bed consists of assessing the frequency channel response over the electrical network for several scenarios. These channel's responses will be convolved to an OFDM frame in order to evaluate performances in term of Bit Error Rate (BER). These scenarios aim to study the influence of the relative distance between the transmitter and receiver, and the number of howsehold loads connected to the electrical network, for MIMO and SISO cases.

In the aerospace domain, more electrical aircraft will have to face a drastic issue in the future, in relation to an increase in the number of wires and connectors, which impact weight and system reliability. A possible solution could be using power-line communications (PLC). In this paper, we focus our attention on the feasibility of communication between a pulsewidth modulation inverter and a motor, using a three-phase cable as a physical support for the data transmission, with a transmitting frequency band extending from 1 to 30 MHz. The required raw bit rate is on the order of 5 to 20 Mbits/s. Noise measurements, in both the time and frequency domains, were performed to extract the main characteristics of the impulsive noise generated by the inverter. Channel transfer functions were measured for an inductive coupling to the motor cable. A software tool simulating the communication link was developed, which is based on recent signal specifications for PLC. Furthermore, noise processing techniques are also proposed, to decrease the impact of the impulsive noise on the received signals. By introducing both the measured transfer functions and noise in the simulation tool, performances of the link, in terms of bit error rate, are presented.

International audience; High voltage direct current networks are now being implemented in the new generation of civil aircrafts. If a short circuit occurs between wires of the power cable, an “arc tracking” may happen. Such an arc can sustain over a time which can reach one second or more and propagate along the cable. New kind of intelligent breakers have thus been developed based either on the time domain or the low frequency characteristics of the pulses associated with this arc. In this paper, the spectral components of the arc in the high frequency band, typically between 1 and 30 MHz are studied. A Thevenin generator equivalent to the arc is proposed allowing to determine the disturbing current and voltage spectral density at any point of the power network. Such an approach can be used to improve the efficiency of actual breakers and also to be able to predict interferences between the disturbing signals due to this arc and sensitive control-command systems.

International audience; In case of a short-circuit between two wires of a dc line, a sustained arc may occur and propagate along the wires through pyrolization of the insulation. This phenomenon, known as arc tracking, is quite critical from a safety point of view since it can cause fire or explosion, depending on its close environment. In addition, the arc generates conducted electromagnetic noise in a wide frequency range which can couple to other wires situated either in the same cable bundle or in its vicinity and disturb control/command devices. In this paper, only this last point is considered, the objective being to characterize the spectral density of the voltage and current generated by such an arc tracking in a high-frequency band extending from 300 kHz to 30 MHz. First, the measurement set up is described, emphasizing the key points to deduce the intrinsic characteristics of the arc from the measured values. A Thevenin generator equivalent to the arc is proposed in order to be able, in a further step, to predict disturbing noise at any point of the cable network.

International audience; In-home Power Line Communication (PLC) enables new and highly convenient networking functions without any additional cables to mains-powered devices. The development of PLC systems for internet, voice, and data services requires the knowledge of the channel in terms of attenuation, phase and noise. To characterize the channel propagation, channel transfer function can be measured or modelled. In this paper we propose a comparison between measurements and simulation results obtained with a deterministic propagation channel model, simulating in-home power network. The impedance of realistic households loads are also modelled and their impact on the transfer function of PLC channel and the communication capacity is analysed. The coherence bandwidth and the delay spread are calculated from simulation results of the various transfer functions.

In this paper, we address the problem of power line communication inside a vehicle, focusing on channel characterization and modeling. The statistical properties of the transfer function between two points in the power distribution system are deduced from a propagation model that takes into account the complicated structure of the cable bundles. Theoretical estimates are compared to experimental results. Later on, this theoretical model, together with an impulsive noise model, will be implemented in a software communication tool that is designed to optimize modulation schemes and channel coding.

International audience; This article provides an overview of the recent advances in the characterization and modeling of power-line communication (PLC) channels in transportation systems. The salient aspects of the topological and functional features of the data channels using power networks of motor vehicles, spacecraft, and aircraft are presented. This article is tutorial in nature and guides the reader through a selection of recent papers, collecting relevant results needed to assess the feasibility and strengths of PLC for this class of applications.

International audience; Power Line Communications (PLC) is used for information exchange over the lines installed for delivering the electrical power. In-home PLC is a technology which delivers telecom services to every corner of a household through already existing electrical wiring. The in-home PLC channel offers multiple signal feed ports as, usually, it comprises of three wires: Phase, Neutral and Protective Earth. The measurements and results presented in this paper shows the impact of load impedances connected to the electrical network on insertion gain and capacity for Multiple Input Multiple Output (MIMO) PLC channel.

In this paper, we discuss the dependence of the insertion gain between two modems upon the distribution of the loads on the network. The results are deduced from a propagation model applied to a three-wire line configuration and in the presence of one or two branches. The impedances presented by different classes of household appliances are modeled by equivalent electrical circuits, available in the literature. The insertion gain and the Shannon capacity of the link are studied both with and without the presence of the branches. The results of a statistical approach are also described; these are based on numerous observations by randomly choosing the distribution of the loads on the network and the length of one of the two branches. Lastly, the cumulative distribution functions of the coherence bandwidth and of the root mean square delay spread are given.

International audience; Advanced communication technologies have allowed power-line-communication (PLC) channel to be a transmission medium that enables the transfer of high-speed digital data over the classical indoor electrical wires. The development of PLC systems for Internet, voice, and data services requires measurement-based models of the transfer characteristics of the mains network suitable for performance analysis by simulation. This paper presents the impact of load impedances connected on the electrical network on insertion gain and capacity of the PLC link.

International audience; This paper gives an overview of the theoretical and experimental approach which has been carried out in order to study the feasibility of broadband power line communication in aircraft. The network which has been chosen corresponds to part of a cabin lighting system and whose tree shape architecture is complicated enough to be representative of many other aircraft cable harnesses. The transmitting frequency band extends from 1 to 30 MHz. The theoretical channel characteristics are obtained from a software based on the transmission line theory while performances of the link in terms of bit error rate and capacity are deduced from a numerical tool simulating an OFDM link. Measurements on a test bench have allowed to estimate the common mode to differential mode conversion factor and to validate the theoretical results.

Power line communication is envisaged for the future more electric aircraft and the scenario studied in this work deals with the cabin lighting system, since its tree-shaped architecture is sufficiently complicated to be representative of many other aircraft harness configurations. The statistical characteristics of the propagation channels are deduced from the measurements made on a representative test bench, the experimental values of the insertion gain being also compared with those obtained from a theoretical model based on the multiconductor transmission line theory. Field-programmable gate array-based modems have been designed and the performance of links are described and compared with predicted values deduced from a software tool simulating the link.

Currently, to ensure data transmission between an inverter and the sensors implemented on a motor, a dedicated cable is used. Since in an aircraft environment, weight is a critical issue, this cable may be avoided by using Power Line Communication technology (PLC), i.e. by transmitting the information on the 3-phase power cable connecting the inverter and the motor. This approach also presents advantages in terms of reliability and maintenance. However impulsive noise due to the inverter has a strong impact on the performances of the link. In order to optimize the communication scheme, it is important to characterize this noise both in the frequency domain and in the time domain. The objective of the work presented in this paper is first to extract the main impulsive noise characteristics and to study their variation as a function of the electrical configuration as the rotation speed of the motor. A noise model is then proposed to be used as an input in a software tool simulating the link in order to optimize the transmission scheme. Performances of PLC links are calculated in terms of bit error rate for different bit rates.

In the domain of aeronautics, the future more electric aircraft will have to face a difficult issue related to the increasing number of wires and connectors, impacting on the weight and system reliability. A possible solution for solving at least part of this problem is to introduce power-line communication for specific applications. In this paper, the cabin lighting and communication system has been chosen as an initial scenario. Indeed, the tree-shaped architecture of the cabling is complicated enough to be representative of many other aircraft harness configurations. Channel characteristics are first determined from a propagation model based on the multiwire transmission-line theory. A software tool simulating PLC communication has been developed. By introducing the predicted channel transfer functions of different links into this software, the throughputs that can be reached, taking into account the electromagnetic constraints related to aeronautic standards, are discussed.

The time reversal (TR) technique consists of transmitting in the channel a signal filtered by the time-reversed channel impulse response. To assess the performance of a TR system using impulse radio ultrawideband signals, one interesting parameter is the focusing gain defined as the ratio of the maxima in the time waveforms of the received signal with and without the time-reversal operation. We propose a heuristic approach to get an approximate analytical expression for the distribution function of this gain, as a function of the channel delay spread normalized to the pulse width and assuming a dense multipath environment. Predicted results are compared to experimental values obtained in reverberating chambers.

The work presented in this paper deals with the possibility of implementing a power line communication in aircraft. A tree-shaped architecture of a network has been simulated for determining the distribution of the transfer function between different points on the line. Comparison with results obtained on a real network has been performed. The performances of an OFDM link have been determined by introducing the channel transfer functions in a software tool simulating the communication.

Power Line Communication may be used to transmit information from the sensors distributed on a motor to the electronic command of the converter feeding this motor. The interest of using the three phase cable as a physical support for the transmission is that the additional line dedicated for data can be avoided. However, impulsive noise generated by the converter is of large amplitude and covers a wide frequency band. The main objective of this paper is to characterize and analyze this noise both in the time domain and in the frequency domain. Three different configurations of Inverter/Motor with different power supplies and switching frequencies are studied, and a comparison is carried out in terms of noise characteristic parameters as amplitude, frequency content, duration, and time interval between pulses. Lastly, the impact of such pulses on a high bit rate communication is outlined.

Data transmission between an inverter and a motor is usually ensured through dedicated cables. However, for many applications and especially in aircraft, the weight of the wiring is becoming critical. One possible technique to decrease the number of wires is to implement a power line communication (PLC) on the 3-phase power cable connecting the inverter and the motor. The objective of this paper is first to present experimental results on noise measurements, both in the frequency and in the time domain. Secondly, a software tool has been built to simulate a PLC communication based on the HomePlugAV specifications or on the OPERA specifications. A parametric study was performed to outline the influence of the impulsive noise on the link performances.

This contribution presents a preliminary investigation on the possibility of eavesdropping, i.e., of extracting information by exploiting the electromagnetic field radiated in the vicinity of a power line communication (PLC) network. This kind of problem is usually known in the electromagnetic compatibility area under the codename TEMPEST. Electromagnetic field measurements were carried out in a laboratory environment, both inside and outside a building, and the main statistical characteristics of the compromising channel are presented. A software tool simulating a PLC communication has been developed and used to draw apreliminary conclusion on whether the radiated emissions can be exploited or not.

To limit the electromagnetic interference due to in-house PLC communication, standards on the emission levels of mains cables are now under elaboration. However, another additional aspect, not yet taken into account, deals with the possibility of exploiting the compromising radiated field to extract some information on the transmitted data. This problem of eavesdropping is known in the Electromagnetic Compatibility community, under the code name Tempest. The compromising propagation channel thus corresponds to the transmission by a modem between two wires of the power line and a reception on a loop antenna placed in adjacent rooms, apartments or houses. To evaluate this risk, a number of configurations are studied to determine the statistical properties of this channel. The influence of either the distance between the transmitting modem and the receiving loop, or of the walls between them, is investigated.

In this paper, we present a comprehensive study of the performance of a new model of DFT-precoded OFDMA with block-interleaved subcarrier allocation: B-IFDMA. The impact of the phase and timing jitter on the performance degradation for the two variants of B-IFDMA, namely joint-DFT and added-signal B-IFDMA is studied. Theoretical expressions of the degradation are derived for the additive white Gaussian noise channel and are compared with classical multicarrier schemes (OFDMA, MC-CDMA). Numerical results with various jitter parameters are presented and discussed. For the maximum number of active users, which is the critical case, it is shown that the phase jitter affects the two B-IFDMA variants and the classical multicarrier schemes in a similar fashion. Also, our results demonstrate that the two B-IFDMA variants are more sensitive to timing jitter than classical multicarrier schemes for a small number of blocks. Additionally, the number of blocks allocated to each user is found critical to minimize the degradation that occurs when timing jitter is introduced, and, therefore, must be carefully chosen.

Low amplitude impulsive noise measurements have been carried out in the time domain on a vehicle power line network. These measurements were made on a stationary vehicle and the motor idling. The characteristics of the measured low amplitude pulses were studied in terms of amplitude, frequency, duration and time interval between successive pulses. Stochastic models based on mathematical distribution functions and fitting the experimental distribution of the various pulse characteristics are proposed.

Most of the studies on electromagnetic noise and the potential sources of interference were conducted to protect analog communications and have now appeared to be insufficient given the widespread development of digital communications. New approaches appropriate for digital communications are currently under development. We have chosen to illustrate these recent approaches by focusing on the particular application of intra-vehicle transmission. In this article, we consider two examples of data transmission: wire transmissions over a power line network, better known as power line communication, and wireless links inside the vehicle's passenger cell. We focus on characterizing the electromagnetic environment but we also highlight the potential of reverberation chambers for reproducibly simulating multi-path environments. To cite this article: F. Rouissi et al., C. R. Physique 10 (2009).

This paper presents a technique for maintaining good broadband transmission quality in the face of impulsive noise in OFDM- PLC systems. The proposed technique is based on adding one zero between two signal samples in order to estimate the noise power in every transmitted signal sample. Simulation results of complete PLC system highlight good improvement in BER and correction ability performances for low power noise pulses independently from its types and durations.

Recently, a new multiple access (MA) scheme called block-interleaved frequency division multiple access (B-IFDMA) is under consideration as an MA scheme candidate for 4G wireless applications. In this paper, the two variants of B-IFDMA are considered, the joint- DFT B-IFDMA and the added-signal B-IFDMA, and compared in terms of sensitivity to carrier frequency offsets (CFOs) for both uplink and downlink. CFO gives rise to multiuser interference and self-user interference. We derive analytical expressions for the power of these interferences, and we quantify their detrimental effect through the evaluation of the signal-to-interference-plus-noise ratio (SINR) degradation. We point out that both variants of B-IFDMA are not similarly affected by CFO. Hence, joint-DFT B-IFDMA provides a better robustness to multiuser interference than added-signal B-IFDMA, and so is better suited for the uplink. Then we show by means of numerical results that added-signal B-IFDMA is less sensitive to CFO in the downlink.

Impulsive noise can have a great influence on the performance of in-vehicle power line communication systems. Intensive noise measurements in the time domain were thus carried out on five different vehicles. Preliminary trials were first made on a stationary vehicle and the motor idling, but the characteristics of the measured low-amplitude pulses greatly vary from one car to another. We thus emphasize the characteristics of high-amplitude pulses, greater than 70 mV, observed when the vehicles were moving in traffic, during a 20-min trip. Noise is statistically characterized in terms of duration, frequency content, peak amplitude, and time interval between successive pulses. Stochastic models based on mathematical distribution functions and fitting the experimental distribution of the various pulse characteristics are proposed. It has been found that interarrival time, i.e., the time interval between two successive pulses, is rather short and would be thus the most critical parameter when optimizing the power line communication physical layer.

Different approaches are described for the characterisation of the low voltage mains network that is used for high-speed data transmission broadband over power line (BPL). Part 1 investigated the disturbance scenario of these BPL devices and importance will be given to develop a new measurement procedure in Comite Internationale Special des Perturbations Radioelectrotechnique (CISPR) to estimate the high-frequency characteristics of AC mains networks. The improvements of the measurement method that can also be applied to other wire-based telecommunication systems will also be presented. Part 2 shows the definitions and comparisons of different symmetry factors. The transfer of the results on the compliance test for BPL devices will also be depicted.

This paper presents a novel coding procedure to correct error bursts generated by impulsive noise corruption in broad-band PLC systems. The coding technique is based on a turbo code structure that uses RS coding and hard decision iterative decoding with erasure process in the decoder. The application of the new coding technique instead of simple RS in the HomePlug 1.0 FEC stage leads to significant improvement in terms of BER.

Different approaches for the characterisation of relevant parameters of the low-voltage mains network, used for high-speed data transmission (BPL, broadband over power line) are described. Part 1 of the paper depicts the disturbance scenario of these BPL devices and the motivation will be given for the development of a new measurement procedure in CISPR for the estimation of the high-frequency characteristics of AC mains network. The improvements of the measurement method is not restricted to BPL applications, but can also be applied to other wire-based telecommunication systems. Part 2 of the paper shows the definitions and comparisons of different symmetry factors. The transfer of the results on the compliance test for BPL devices will be shown.