Software-Defined Real-Time Mesh Networking: Protocol and Experimentation Method

International audienceOur research address the problem of network resource allocation for real-time communications in mesh networks. We are studying the combination of online flow admission control and pathfinding algorithms in an SDN-like controller.We propose a Software-Defined Real-time Networking protocol that allows a dynamic and incremental allocation of network resource in a mixed-critical real-time m esh network context. We also propose a method to ensure the dependability of the network, considering that transmission errors and node failures can happen. Finally, our research includes the study of a new way of experimenting on embedded networks, by making use of both an in-silicon platform and a simulator. We designed an original framework to ease conducting such experiments

Réseaux maillés dynamiques pour applications temps réel à criticités multiples : problématiques et analyse

National audienceDans le cadre d'une thèse CIFRE chez Thales Research & Technology et au LORIA, débutée en 2015, nous étudions le chargement dynamique et la dégradation contrôlée d'un ensemble applicatif distribué, à criticités multiples, sur un réseau maillé. Il y a aujourd'hui une demande croissante en termes de systèmes temps réel distribués capables de supporter des ensembles applicatifs à criticités multiples. Dans les contextes de l'avionique ou du spatial par exemple, les contraintes de sûreté et de temps réel se superposent à celles liées aux coûts, à la consommation énergétique ou encore à l'espace disponible au sein du véhicule. Nous envisageons une nouvelle approche basée sur un réseau maillé de calculateurs, qui soit à la fois résilient et auto-reconfigurable de façon dynamique. Nos travaux s'intéressent au comportement de ce réseau ainsi qu'à sa modélisation, afin de démontrer sa viabilité pour supporter des ensembles applicatifs embarqués temps réel à criticité mixte. Dans ce document, nous proposons un aperçu des technologies d'interconnexion existantes et les confrontons a nos besoins, afin d'analyser les problématiques apportées par notre projet

A Symbiotic Approach to Designing Cross-Layer QoS in Embedded Real-Time Systems

International audienceNowadays there is an increasing need for embedded systems to support intensive computing while maintaining traditional hard real-time and fault-tolerant properties. Extending the principle of multi-core systems, we are exploring the use of distributed processing units interconnected via a high performance mesh network as a way of supporting distributed real-time applications. Fault-tolerance can then be ensured through dynamic allocation of both computing and communication resources. We postulate that enhancing QoS (Quality of Service) for real-time applications entails the development of a cross-layer support of high-level requirements, thus requiring a deep knowledge of the underlying networks. In this paper, we propose a new simulation/emulation/experimentation framework, ERICA, for designing such a feature. ERICA integrates both a network simulator and an actual hardware network to allow implementation and evaluation of different QoS-guaranteeing mechanisms. It also supports real-software-in-the-loop, i.e. running of real applications and middleware over these networks. Each component can evolve separately or together in a symbiotic manner, also making teamwork more flexible. We present in more detail our discrete-event simulation approach and the in-silicon implementation with which we cross-check our solutions in order to bring real performance aspects to our work. We also discuss the challenges of running real-software-in-the-loop in a real-time context, i.e. how to bridge it with a network simulator, and how to deal with time consistency

Prediction of second neurological attack in patients with clinically isolated syndrome using support vector machines

The aim of this study is to predict the conversion from clinically isolated syndrome to clinically definite multiple sclerosis using support vector machines. The two groups of converters and non-converters are classified using features that were calculated from baseline data of 73 patients. The data consists of standard magnetic resonance images, binary lesion masks, and clinical and demographic information. 15 features were calculated and all combinations of them were iteratively tested for their predictive capacity using polynomial kernels and radial basis functions with leave-one-out cross-validation. The accuracy of this prediction is up to 86.4% with a sensitivity and specificity in the same range indicating that this is a feasible approach for the prediction of a second clinical attack in patients with clinically isolated syndromes, and that the chosen features are appropriate. The two features gender and location of onset lesions have been used in all feature combinations leading to a high accuracy suggesting that they are highly predictive. However, it is necessary to add supporting features to maximise the accuracy. © 2013 IEEE

Combining Source and Destination-Tag Routing to Handle Fault Tolerance in Software-Defined Real-Time Mesh Networks

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A Dynamic Flow Allocation Method for the Design of a Software-Defined Real-Time Mesh Network

International audienceMesh networks provide natural link and node fault tolerance and load balancing characteristics. However, existing solutions for real-time flow allocation seldom utilize those advantages. This paper deals with the real-time flow allocation problem in mesh networks. The objective is to find the suitable path under delay constraint while allowing load balancing. For this purpose, combined online flow admission control and pathfinding algorithms have been developed on an SDN-like controller. At switch level, each output port is ruled by a credit-based weighted round robin, allowing isolation of flows. As a consequence, a freshly admitted flow will not influence existing flows, allowing incremental online admission of new flows. This approach has been applied to a RapidIO mesh network example and compared with the compositional performance analysis method. Numerical results clearly show the benefit of our proposal in terms of complexity and delay bound pessimism