Advanced Coordinated Beamforming for the Downlink of Future LTE Cellular Networks

Modern cellular networks in traditional frequency bands are notoriously interference-limited especially in urban areas, where base stations are deployed in close proximity to one another. The latest releases of Long Term Evolution (LTE) incorporate features for coordinating downlink transmissions as an efficient means of managing interference. Recent field trial results and theoretical studies of the performance of joint transmission (JT) coordinated multi-point (CoMP) schemes revealed, however, that their gains are not as high as initially expected, despite the large coordination overhead. These schemes are known to be very sensitive to defects in synchronization or information exchange between coordinating bases stations as well as uncoordinated interference. In this article, we review recent advanced coordinated beamforming (CB) schemes as alternatives, requiring less overhead than JT CoMP while achieving good performance in realistic conditions. By stipulating that, in certain LTE scenarios of increasing interest, uncoordinated interference constitutes a major factor in the performance of CoMP techniques at large, we hereby assess the resilience of the state-of-the-art CB to uncoordinated interference. We also describe how these techniques can leverage the latest specifications of current cellular networks, and how they may perform when we consider standardized feedback and coordination. This allows us to identify some key roadblocks and research directions to address as LTE evolves towards the future of mobile communications.Comment: 16 pages, 6 figures, accepted to IEEE Communications Magazin

Analyse des critères d'évaluation de systèmes multi-agents adaptatifs

http://www.emse.fr/~picard/publications/kaddoum09jfsma.pdfInternational audienceLa complexité croissante des applications actuelles favorise le développement de systèmes multi-agents auto-organisateurs possédant des propriétés self-? . Ces systèmes autonomes présentent des capacités intéressantes permettant la gestion de la dynamique endogène et exogène des applications étudiées. De nouveaux critères doivent être étudiés afin de caractériser et évaluer l'apport de ces propriétés self-? et leur influence sur les performances du système. Dans cet article, différentes catégories regroupant les principaux critères d'évaluation sont décrites afin de guider l'évaluation de ce type de systèmes depuis les phases de conception jusqu'aux phases d'exécution : évaluation du système en cours de fonctionnement, caractéristiques intrinsèques et méthodologie de conception

Surveillance et contrôle des activités des navires en mer ScanMaris

Surveillance and Control of Maritime Vessel Activities - ScanMaris, publication disponible : http://www.irit.fr/scanmaris/uploads/files/Article%20SCANMARIS%20WISG10.pdfNational audiencePour garantir aujourd'hui des conditions sécuritaires de passage dans les eaux territoriales et exclusives économiques françaises, le dispositif de surveillance maritime s'est renforcé en utilisant de manière optimale la synergie de ses différentes composantes: CROSS (Centre Régionaux Opérationnels de Surveillance et de Sauvetage), sémaphores, moyens nautiques et aériens des administrations en mer. Toutefois, ils ne recueillent des informations que pour des zones maritimes ou des périodes limitées. C'est pourquoi il est envisagé dans les futurs systèmes de surveillance globale et permanente, un recueil massif de données permettant de mieux gérer les situations en mer et les interventions. Pour cette prise de contrôle global des espaces maritimes en tenant compte des nombreuses informations acquises et sans empêcher ou restreindre le libre échange, il est ainsi nécessaire de développer des outils d'analyse automatisée (SCANMARIS ; Surveillance et Contrôle des Activités des Navires en Mer) par croisements des données. Il devient alors possible de suivre dans le temps et l'espace la situation des activités en mer ou liées à la mer, les flux de marchandises transportées et détecter ainsi une part des activités criminelles et illicites, et les violations à la réglementation, ainsi que les conséquences (flux de produits illicites, l'immigration clandestine, la sur exploitation des ressources halieutiques, les pollutions par des matières dangereuses, la piraterie avec prise d'otage, les sinistres, etc.)

ScanMaris : automatic detection of abnormal vessel behaviours

International audienceThe ScanMaris project is a software workshop designed to develop and evaluate solutions for thread prevention and maritime border monitoring. It relies on enriched tactical picture exploitation tools resulting from the continuous treatment of important volumes of heterogeneous data gathered in real time and differed time. ScanMaris will enable the supervision of the permanent evolving traffic on a global maritime zone in order to follow the flow of transported goods (bulk, containers, energy, chemical....) according to various routes (corridor, coastal traffic...) and to automatically detect criminal traffic of illicit products. ScanMaris will use data treatment tools to merge ship's kinematic data and other information to establish and maintain a global enriched tactical picture compilation of the traffic, the training methods and the models which exploit the tactical picture. This produces a permanent knowledge of goods flows, improves its follow-up and the rules of investigation organised to detect irregularities like illicit products flows, disasters, regulation violations, etc. The ScanMaris project will involve functions that improve the effectiveness of a global surveillance of the contraveners. They will contribute to set up optimal answers and intervention means adequately fitting the struggle against illicit activities and maritime violations

High levels of circulating leukocyte microparticles are associated with better outcome in acute respiratory distress syndrome

International audienceINTRODUCTION: The current study has addressed the presence and the cellular origin of microparticles (MP) isolated from bronchoalveolar lavage (BAL) fluid and from blood samples from patients with acute respiratory distress syndrome (ARDS). Their prognostic interest was also investigated. METHODS: Fifty-two patients were included within the first 24 hours of ARDS. They were compared to spontaneous breathing (SB) and ventilated control (VC) groups. Bronchoalveolar lavage (BAL) and blood samples were obtained on Day 1 and Day 3 in an ARDS group. Leukocyte microparticles (LeuMP), neutrophil microparticles (NeuMP), endothelial microparticles (EMP), and platelet microparticles (PMP) were measured in arterial blood and in BAL samples by flow cytometry. Mortality from all causes was recorded at Day 28. RESULTS: All MP subpopulations were detected in BAL. However, only LeuMP and NeuMP were elevated in ARDS patients compared to the SB group (P = 0.002 for both). Among ARDS patients, higher levels of LeuMP were detected in blood (Day 1) and in BAL (Day 3) in survivors as compared with the non survivors. Circulating LeuMP >60 elements/microliter detectable on Day 1 of ARDS, was associated with a higher survival rate (odds ratio, 5.26; 95% confidence interval, 1.10 to 24.99; P = 0.037). CONCLUSIONS: The identification of the cellular origin of microparticles at the onset of ARDS has identified LeuMP as a biomarker of prognostic significance. The higher levels of LeuMP in survivors could be associated with a protective role of this MP subpopulation. This hypothesis needs further investigations

Trafic Maritime : détection des comportements anormaux des navires

International audiencePour garantir aujourd'hui des conditions sécuritaires de passage dans les eaux territoriales et exclusives économiques françaises, le dispositif de surveillance maritime s'est renforcé en utilisant de manière optimale la synergie de ses différentes composantes : CROSS (Centre Régionaux Opérationnels de Surveillance et de Sauvetage), sémaphores, moyens nautiques et aériens des administrations en mer. Toutefois, le nombre de mobiles circulant sur certaines zones maritimes est en constante augmentation et les demandes d'assistance en cas de difficultés ont changé ; les grosses unités commerciales tardent, pour des raisons économiques, à signaler une avarie et tendent à en minimiser l'importance. Les actes illicites suivent des protocoles de plus en plus perfectionnés pour échapper à la surveillance. Le développement des activités nautiques de loisirs engorge les centres de surveillance et de sauvetage ..

Strain-Control of the magnetic anisotropy in (Ga,Mn)(As,P) ferromagnetic semiconductor layers

A small fraction of phosphorus (up to 10 %) was incorporated in ferromagnetic (Ga,Mn)As epilayers grown on a GaAs substrate. P incorporation allows reducing the epitaxial strain or even change its sign, resulting in strong modifications of the magnetic anisotropy. In particular a reorientation of the easy axis toward the growth direction is observed for high P concentration. It offers an interesting alternative to the metamorphic approach, in particular for magnetization reversal experiments where epitaxial defects stongly affect the domain wall propagation