Fabienne Nouvel

Cognitive detection method of radio frequencies on power line networks

In the [1.8–30] MHz frequency band, EMC standards prohibit power line communications (PLC) to emit on the frequencies which could be used by HAM radio in order to protect them. This implies an transmit power restriction in these radio frequencies and consequently a throughput limitation. With the aim to increase the data rates, the solutions envisaged today consist in limiting the number of notched frequencies as well as in increasing the used frequency band, which can henceforth overlap with the FM band [87.5–108] MHz for future PLC systems. With the current static notching solution, the whole frequencies of the FM band can be notched during PLC transmission. As in a given environment and at a given time, only a part of the FM radio frequencies are really received, a cognitive EMC approach is proposed in this paper. The power line network is demonstrated to be a good antenna that can detect all present radio frequencies and a cognitive detection method is proposed. By means of simulations, it is also shown that the use the cognitive technique improves the data rates of the PLC systems.

What is about future high speed power line communication systems for in-vehicles networks?

This paper deals with alternative automotive networks involved by the X-by-wire and X-tainment applications. New market demands like navigation, multimedia, security, safety and individualized options introduce more and more electronic control units. Furthermore, the automotive industry has to face a great challenge in its transition from mechanical engineering towards mechatronical products. In the last decades, the power line technology has received an increasing attention and spans several applications both in indoor, outdoor and in-vehicle data communications. To fulfil theses demands of intra-car communications, techniques based on power line communication (PLC) seem to be a good candidate. These techniques offer both high data rate and good adequacy with power line properties. This paper revisits the work carried out in using PLC within the automotive domain. Different solutions are discussed and results are given for different applications.

Multi-carrier CDMA over copper lines - comparison of performances with the ADSL system

This paper deals with the comparison of two multi carrier modulation techniques over existing copper twisted pairs: the Discrete Multi Tone (DMT) modulation and the Multi Carrier Code Division Multiple Access (MC-CDMA) modulation. The first form has been proposed for Asymmetrical Digital Subscriber Line (ADSL). However in ADSL, the wire pairs suffer from disturbances such as transients, radio-frequency noise. Among them, impulse noise is considered to be one of the most damaging impairments. Then, our proposal intends to limit the effects of such a noise thanks to the use of the latter form of modulation which combines multi carrier technique with spread spectrum. In order to improve the performances of the system proposed still further various detection techniques are studied. In this context, we show that the MC-CDMA technique presents better performances than the normalised ADSL technique under identical simulation parameters (data rate, bandwidth, transmitted power, coding, interleaver).

PLC coupling effect on VDSL2

The indoor PLC (Power Line Communications) and VDSL2 (Very high bit-rate Digital Subscriber Line) technologies share the same frequency band up to 30 MHz. Behind the VDSL2 access network, the power line network is envisaged to be used like an home network in order to transit TV flows from the VDSL2 modem to the set-top-box. In many customer premises, power line cables are nearby telephone cables and consequently unwanted couplings could occur generating hence VDSL2 QoS decrease. This paper describes an experimental study of PLC coupling effect on VDSL2. Two approaches are followed in order to highlight this coupling effect. The first one consists in studying the PLC coupling effect on VDSL2 relying in different coexistence scenarios made in laboratory. The second one is based on field test measurements into several houses: coupling noises are measured on phone plugs when PLC signals are transmitted in sockets.

Lattice Reduction-aided Minimum Mean Square Error K-Best detection for MIMO systems

The Multiple-Input Multiple-Output (MIMO) with a Spatial-Multiplexing scheme is a topic of high interest for the next generation of wireless communications systems. In this paper, we propose to approach the Maximum Likelihood (ML) performance through the combination of a neighbourhood study and a Lattice Reduction (LR)-aided solution. Moreover, by introducing a neighbourhood study in the reduced domain, we propose in this paper a novel equivalent metric that is based on the combination of the LR-aided Minimum-Mean Square Error solution. We show that the proposed metric presents a relevant complexity reduction while maintaining near-ML performance. In particular, the corresponding computational complexity is polynomial in the number of antennas while it is shown to be independent of the constellation size. For a 4×4 MIMO system with 16-QAM modulation on each layer, the proposed solution is simultaneously near-ML and ten times less complex than the classical neighbourhood-based K-Best solution.

Impulsive noise detection on masked carriers

Indoor powerline communications systems are widely used to provide services from the access point to every socket of any dwelling-house. Most of these services, like video or audio streaming, need to be transmitted with datarate, delay and QoS requirements. These requirements may be unsatisfied when the powerline channel is affected by interferences mainly including the wide band impulsive noise. To counter these impulses, powerline system use both error correction codes and retransmission request. The performance of these techniques may be greatly improved if the time of the impulse is precisely detected. This study presents an easy way to perform and efficient technique to carry out such a detection, based on the use of powerline masked carriers.

Characterization of Time Variation of the Powerline Channel Frequency Response Simultaneously with Impulsive Noise

Powerline communication systems are used to transmit audio and video transmissions with delay, datarate and QoS requirements. Consequently the knowledge of the channel frequency response has to be as accurate as possible. However, the powerline medium is shared with other devices connected to any socket. When switching, and even during normal operation, these devices can generate some noises (stationary, cyclo-stationary & impulsive), and may cause perceptible variation of channel frequency response. This study tries to establish a link between impulsive noise and a simultaneous variation of the channel frequency response. Indeed, an impulsive noise corresponds to a particular event which may be a sign of a change in the powerline characteristics, and the channel frequency response may be affected by this change. Afterwards, a statistical analysis of the noises linked with a variation of the channel frequency response is performed, and consequently incurred results may help any receiver to anticipate this variation.

Towards power line communication in vehicle

This paper is a review of studies dealing with Power Line Communication (PLC) in vehicle. The electronic control units (ECUs) that replace mechanical or hydraulic systems require specific buses in order to exchange information between sensors and actuators. Different networks as LIN, CAN, Flexray have been proposed, from low up to high data rate. Considering these networks, we can observe that each solution uses its specific wires and communication system. The growth of the complexity leads to the necessity to commit to a limited set of networks which answers to these multiple applications. An attractive solution to reduce the wires is the power line communication (PLC) using the power lines (12/42V) to transmit both the power and the messages without functional barriers domain. The channel characterizations of the PLC lines, the impact of the noise, and the resulting system parameters are presented. Taking into account the PLC channels, optimizations of the system parameters are carried out especially the CP length and the bandwidth, Numerical results show obtained significant improvements.

Microkernel dedicated for dynamic partial reconfiguration on ARM-FPGA platform

This paper describes the first implementation of a custom micro-kernel on a ARM-FPGA platform capable of managing reconfigurable hardware parts dynamically. After describing the structure of the proposed micro-kernel, we will focus on a custom specific system task dealing with the reconfiguration management, which is associated to a dedicated scheduling mechanism. We will describe the hardware platform on which the microkernel has been ported and provide a use case application in order to demonstrate the feasibility of the approach. At the end of this paper, we will provide quantitative results in terms of reconfiguration overhead and microkernel timing performances.

Evaluation of the overheads and latencies of a virtualized RTOS

The virtualization technique has become a popular trend in the domain of real-time embedded systems. For example, in the automotive industry, practitioners are currently considering the idea of using such technique to run simultaneously the AUTOSAR real-time operating system (RTOS) for real-time programming, and the Linux-GENIVI operating system to support in-vehicle infotainment applications on the same Electronic Control Unit. However, running a real-time operating system inside a virtual machine instead of a bare metal hardware may have a significant cost in terms of latencies and overheads. This raises the question of the order-of-magnitude of a virtualized RTOSs overheads and latencies in comparison to a single RTOS running on a real machine. In this paper, an evaluation of a virtualized RTOSs latencies and overheads is proposed in order to observe how virtualization impacts these timing characteristics. Our experiments demonstrate that the overheads and latencies of a virtualized RTOS compete with those obtained in the same RTOS running on bare-metal hardware.