Orange S.A.

About: Orange S.A. is a company organization based out in Paris, France. It is known for research contribution in the topics: Terminal (electronics) & Signal. The organization has 6735 authors who have published 9190 publications receiving 156440 citations. The organization is also known as: Orange SA & France Télécom.

Extending and unifying chronicle representation with event counters

Abstract: This paper is dedicated to the chronicle recognition approach used to design an evolution monitoring system for supervising dynamic systems for which time information is relevant. We propose to extend and also to unify the chronicle representation through event counters. The main motivation of such an extension of the chronicle representation arises from alarm processing: counting the occurrences of alarms can be useful to evaluate the severity of a problem and also to discriminate some kind of faults. The paper describes the representation and the corresponding algorithms for processing this extension according to the purpose of supervision in terms of performance.

Method for cancelling multi-channel acoustic echo and multi-channel acoustic echo canceller

Abstract: In order to cancel echo on several sound signal channels, the method consists in generating on each channel a synthetic signal having the spectral characteristics of a white noise; computing the frequency masking thresholds in several adjacent frequency bands using auditory perception properties; bringing in each frequency channel the synthetic signal level to the associated masking threshold value, so as to obtain an auxiliary signal, which is added to the signal associated with the loudspeaker of the channel concerned; supplying the resulting signal to an adaptive filter; adding the output signals of the associated adaptive filters to each microphone channel; subtracting the resulting signal received by the microphone of this channel; deducing an estimation error, on the basis of which the coefficients of the adaptive filters associated with this channel are corrected.

Analysis of Power Absorbed by Children's Head as a Result of New Usages of Mobile Phone

Abstract: This paper deals with the influence of new uses of mobile phones (such as short message service, multimedia messaging service, video, etc.) on the SAR induced in different heads models. In particular, the exposure of children will be analyzed. For this reason, three heterogeneous models have been used in this study, two children head models (9 and 15 years old) and one adult head model (“visible human”). The specific anthropomorphic mannequin (SAM) homogeneous head model has been also used to compare all the results and to confirm that the SAM model always overestimates adult and child head exposure. Two handset models have been used: the first model is a triband mobile phone having a patch antenna and the second model is a generic model (known as IEEE mobile phone) having a monopole antenna inside a metal box covered by plastic. A comparison on SAR between adult and child head is given using the finite-difference time-domain method. The results of new positions are compared with respect to the results obtained with the voice position. These studies have been performed at 900, 1800, and 2100 MHz for the triband mobile phone and at 835, 1900, and 2100 MHz for the IEEE mobile phone. The comparison of the maximum SAR over 10 g between the different heads models (9 and 15 year olds and adult) shows that results were nearly similar. It was also pointed out that the value of the maximum local peak SAR in the SAM was always higher than in the adult and children models.

Characterization and Modeling of Temporal Variations on an Ultrawideband Radio Link

Abstract: The development of efficient ultrawideband (UWB) systems for high-rate wireless links requires an accurate knowledge of the radio propagation mechanisms. Anticipated usage scenarios in office or residential environments predict a significant impact of mobile persons on the UWB radio link. However, the issue of temporal variations in the UWB propagation channel has been scarcely investigated so far. This paper presents a study of the time variance of a UWB channel induced by the motion of people, with a specific focus on the main path of a line-of-sight radio link. A real-time measurement campaign involving moving scatterers was performed in the 4-5 GHz band, in a hallway of a typical office building. The analysis of measured data, regarding the shadowing effect and fast signal fluctuations, provides a detailed description of the phenomena involved in a time varying UWB channel. As a result, a model is described for the temporal variations observed on the main propagation path in a fixed UWB link, accounting for both the nonstationary attenuation due to obstructing people and the small-scale signal variations due to scattered propagation paths

Resiliency of wireless sensor networks: Definitions and analyses

Abstract: This paper considers security in wireless sensor networks (WSNs), focusing at the routing layer. We propose to analyze the behavior of some routing protocols according to attacks stemming from compromised nodes. Such malicious nodes could disrupt the routing functionality (node replication, Sybil attacks or Black-Grey-Sink holes). For such adversary models traditional cryptographic solutions are not enough by themselves but need to be completed by algorithmic solutions considering “beyond cryptography” approaches. Emphasizing internal attacks, with security features of routing in mind, we define the resiliency as the ability of a network to continue to operate in presence of k compromised nodes, i.e. the capacity of a network to endure and overcome internal attacks. In this context, we analyze four particular routing protocols (DSR, Gradient based, Greedy forwarding and Random walk routing). Using intensive simulations, we test their resiliency in presence of several compromised nodes in several adversary models.