Satellite diversity system emulator

Current satellite telecommunication systems are facing growing demand, in particular for broadband markets. In order to reach higher data rate and minimize the cost per Mbps, upcoming VHTS systems are targeting Terabit capacity. One of the most promising solution is to dedicate the whole Ka band to the user links to maximize the user link capacity whereas the feeder links operate in Q/V bands. However, the use of these higher frequencies (in the Q/V bands) raises new challenges, because of the increased sensitivity of these bands to meteorological events that may affect gateways link budget, making them unable to handle any traffic during a rain event. A simple solution to this shortcoming for ensuring constant service to users is to add additional gateways to the system and perform a handover to a redundancy gateway when a nominal gateway faces too strong fading 3,4. For example, a pan-european system with a dozen of operational gateways and a few redundancy gateways would be economically viable: the additional cost of the redundancy gateway is not offset by the benefits of increased system availability. Different design choices to realize diversity are possible 5: this work studies in particular geographical diversity, or (n+p) diversity. This (n+p) diversity scheme provides extremely high availability with very few redundant gateways. However, the impacts on services has still to be evaluated. This paper presents a diversity emulation test-bed developed to experiment different types of gateway handover scenarios to measure their impact on user’s experience. This emulator has been developed by IRT Saint-Exupéry in the framework of the ALBS project (Advanced Link for Broadband Satellite). The emulator is able to simulate both ground network and satellite links, up to the user’s terminals. It is designed to be representative of the network transit and switching losses and delays, as well as the satellite onboard switch behavior. The emulator is used to investigate the influence of the effects that switching mechanisms can have on the ongoing communications. It will also allow to investigate design optimization and provide recommendations to handle these ongoing communication during the gateway handover

The various manifestations of collisionless dissipation in wave propagation

The propagation of an electrostatic wave packet inside a collisionless and initially Maxwellian plasma is always dissipative because of the irreversible acceleration of the electrons by the wave. Then, in the linear regime, the wave packet is Landau damped, so that in the reference frame moving at the group velocity, the wave amplitude decays exponentially with time. In the nonlinear regime, once phase mixing has occurred and when the electron motion is nearly adiabatic, the damping rate is strongly reduced compared to the Landau one, so that the wave amplitude remains nearly constant along the characteristics. Yet, we show here that the electrons are still globally accelerated by the wave packet, and, in one dimension, this leads to a non local amplitude dependence of the group velocity. As a result, a freely propagating wave packet would shrink, and, therefore, so would its total energy. In more than one dimension, not only does the magnitude of the group velocity nonlinearly vary, but also its direction. In the weakly nonlinear regime, when the collisionless damping rate is still significant compared to its linear value, this leads to an effective defocussing effect which we quantify, and which we compare to the self-focussing induced by wave front bowing.Comment: 23 pages, 6 figure

Climate driven life histories: the case of the Mediterranean Storm petrel

Seabirds are affected by changes in the marine ecosystem. The influence of climatic factors on marine food webs can be reflected in long-term seabird population changes. We modelled the survival and recruitment of the Mediterranean storm petrel (Hydrobates pelagicus melitensis) using a 21-year mark-recapture dataset involving almost 5000 birds. We demonstrated a strong influence of prebreeding climatic conditions on recruitment age and of rainfall and breeding period conditions on juvenile survival. The results suggest that the juvenile survival rate of the Mediterranean subspecies may not be negatively affected by the predicted features of climate change, i.e., warmer summers and lower rainfall. Based on considerations of winter conditions in different parts of the Mediterranean, we were able to draw inferences about the wintering areas of the species for the first time

Prise en charge des troubles anxieux en pédo-psychiatrie

NANCY1-SCD Pharmacie-Odontologie (543952101) / SudocSudocFranceF

An Extensible Network Slicing Framework for Satellite Integration into 5G

International audienceWith the imminent deployment of the 5th generation mobile network (5G) in the nonstandalone version, some researches focus on network slicing to fully exploit the 5G infrastructure and achieve a highest level of flexibility in the network. This level of flexibility offered by the network slicing paradigm also fits the need of satellite networks in which Satellite Network Operators (SNOs) want to offer 5G connectivity services additionally to the traditional satellite connectivity. However, the work that has been done so far for network slicing in 5G does not directly apply to satellite networks due to satellite architecture specificities and thus needs to be extended. We extend the work on network slicing and this paper proposes a novel Satellite Slicing Framework in order to fully exploit the satellite infrastructure and to facilitate the integration of satellite services into 5G. Our framework includes defining, modeling, orchestrating and deploying multiple satellite network slices and their associated network services on top of mutualized satellite infrastructures

Smart Management of Virtualized Network Service Chains in 5G Infrastructure

International audienceFuture 5G infrastructures promise to deliver un- precedented Quality of Services (QoS) guarantees through ultra- low latency and high data rate specifications that lead to handle many critical applications and services. Network Function Virtualization (NFV) is the paradigm that enables the implementation of network functions and capabilities as software components executed in virtual entities provisioned in general-purpose hardware. This paradigm plays a pivotal role to achieve management flexibility of 5G services and reduce infrastructures’ investment and operational costs. Recent advances in artificial intelligence (AI) and the large amounts of data collected on orchestration platforms offer new perspectives. Many recent publications advocate the use of AI in the orchestration of virtualized networks and many algorithms are proposed. Though, today small amount of literature works implement or test these concepts in a real platform that considers network service chains data. In this work, we present a framework for Service Function Chains’ (SFCs) profiling and management through Machine- learning approaches. We propose an extended network orchestration platform based on Openstack, Kubernetes (K8s), and Open Source Mano (OSM) orchestrator. The benefits of this architecture are shown by an algorithm that realizes proactive auto-scaling procedure for service chains. It considers features’ importance per service type while achieving a trade-off between services’ stringent QoS requirements and the cost of resources usage

Smart Management of Virtualized Network Service Chains in 5G Infrastructure

International audienceFuture 5G infrastructures promise to deliver un- precedented Quality of Services (QoS) guarantees through ultra- low latency and high data rate specifications that lead to handle many critical applications and services. Network Function Virtualization (NFV) is the paradigm that enables the implementation of network functions and capabilities as software components executed in virtual entities provisioned in general-purpose hardware. This paradigm plays a pivotal role to achieve management flexibility of 5G services and reduce infrastructures’ investment and operational costs. Recent advances in artificial intelligence (AI) and the large amounts of data collected on orchestration platforms offer new perspectives. Many recent publications advocate the use of AI in the orchestration of virtualized networks and many algorithms are proposed. Though, today small amount of literature works implement or test these concepts in a real platform that considers network service chains data. In this work, we present a framework for Service Function Chains’ (SFCs) profiling and management through Machine- learning approaches. We propose an extended network orchestration platform based on Openstack, Kubernetes (K8s), and Open Source Mano (OSM) orchestrator. The benefits of this architecture are shown by an algorithm that realizes proactive auto-scaling procedure for service chains. It considers features’ importance per service type while achieving a trade-off between services’ stringent QoS requirements and the cost of resources usage