The Role of Satellite Systems in Future Aeronautical Communications

Materials scienc

Chapter The Role of Satellite Systems in Future Aeronautical Communications

Materials scienc

On the Impact of Link Layer Retransmissions on TCP for Aeronautical Communications

In this article, we evaluate the impact of link layer retransmissions on the performance of TCP in the context of aeronautical communications.We present the architecture of aeronautical networks, which is manly driven by an important channel access delay, and the various retransmission strategies that can be implemented at both link and transport layers. We consider a worst case scenario to illustrate the benefits provided by the ARQ scheme at the link layer in terms of transmission delay.We evaluate the trade-off between allowing a fast data transmission and a low usage of satellite capacity by adjusting link layer parameters

A cross-layer approach to enhance QoS for multimedia applications over satellite

The need for on-demand QoS support for communications over satellite is of primary importance for distributed multimedia applications. This is particularly true for the return link which is often a bottleneck due to the large set of end-users accessing a very limited uplink resource. Facing this need, Demand Assignment Multiple Access (DAMA) is a classical technique that allows satellite operators to offer various types of services, while managing the resources of the satellite system efficiently. Tackling the quality degradation and delay accumulation issues that can result from the use of these techniques, this paper proposes an instantiation of the Application Layer Framing (ALF) approach, using a cross-layer interpreter(xQoS-Interpreter). The information provided by this interpreter is used to manage the resource provided to a terminal by the satellite system in order to improve the quality of multimedia presentations from the end users point of view. Several experiments are carried out for different loads on the return link. Their impact on QoS is measured through different application as well as network level metrics

Une approche pour la composition autonome de services de communication orientés QoS. Application aux protocoles de transport configurables

The recent evolutions of the Internet have been materialized by the emergence of new distributed application as well as the rapid increase of the number of network technologies (wireless, mobile. . . ). These advances have allowed new services to be proposed by operators using a new type of terminals (laptop, PDA. . . ). The major socio economic stake that these advances represent is materialized by the future ambient Internet, which is both ubiquitous and intelligent, through which the user will be able, whatever his location or access point, benefit from the best possible Quality of Service (QoS) given its current applicative and network environment. In this context, the thesis presents an architecture as well as models and algorithms that allow for a dynamic self-adaptive composition of services provided by existing QoS mechanisms. The approach is based on the dynamic and coordinated adaptation of both the behaviour and the architecture of the protocols that compose the communication stack. The work finds its inspiration in the theory of artificial intelligence and learning and provides the specification, implementation and evaluation of a self-adaptive communication system taking into account both, the applicative requirements for the transported streams and the constraints of the environment on which communication takes place. Finally, the evaluation of the decision and learning models illustrates how the system allows to fulfil its objective and validates the concepts that are proposed in this thesis.Les dernières évolutions de l'Internet se sont traduites par l'émergence de nouvelles applications distribuées et par la multiplication des technologies réseaux (sans fils, mobiles. . . ) ainsi que des services offerts par les opérateurs sur de nouveaux types de terminaux (portable, PDA. . . ). L'enjeu socio économique majeur de ces avancées est le futur Internet ambiant, à la fois ubiquitaire et intelligent, au travers duquel l'utilisateur pourra, quelle que soit sa localisation et son point d'accès, bénéficier d'une qualité de service (QdS) maximale compatible avec l'environnement applicatif et réseau courant, hétérogène et dynamique. Dans cet horizon, la thèse présente une architecture ainsi que des modèles et algorithmes permettant de réaliser une composition dynamique et auto-adaptative des services fournis par les multiples mécanismes de QdS existants. L'approche proposée repose sur l'adaptabilité dynamique et coordonnée, à la fois du comportement et de l'architecture des protocoles composant la pile de communication. La démarche suivie se base sur la théorie de l'intelligence artificielle et l'apprentissage et propose la spécification, l'implémentation et l'évaluation d'un système de communication adaptatif en fonction à la fois, des exigences applicatives liées aux flux manipulés, et des contraintes de l'environnement de communication. Enfin, l'évaluation faite des modèles dedécision et d'apprentissage illustre comment le système permet de répondre à son objectif et valide ainsi les concepts qui sont proposés dans cette thèse

Extensible and Adaptive Architecture for an Evolutive Transport Layer

International audienceThe world of communications and networking knows and important evolution over the years. While this evolution is concretized by a deployment of many modern protocols at most of protocol layers, the Transport one continues to use old TCP and UDP protocols. This despite that an important number of modern protocols and mechanisms have been proposed. In this context, we study in this paper the obstacle of the deployment of new transport protocols and propose a new architecture to support the deployment and the adaptation of new Transport solutions. This was achieved by adding extensibility and adaptability capabilities using service-oriented and component-based paradigms. The architecture performances are studied at the end to measure the impact and the benefits of the new architecture comparing to classical Transport protocol

Transport protocols: limitations, evolution obstacles and solutions for an actual deployment in the Internet

International audienceThe Transport layer, designed for old networking contexts and now obsolete applications requirements, is inefficient. This paper discusses the reasons behind this inefficiency and the obstacles to the evolution of Transport protocols. The discussion is then extended to derive new requirements for the Transport layer, both functional and architectural, in order to ensure optimal performances in all current and future contexts. To meet these new requirements, a novel architectural design of the Inter-net Transport layer is proposed following a service-oriented and a component-based approach. The proposed solution allows for optimization of the Transport service performance, facilitation of its utilization, and is aimed at allowing the integration of new services as needed. 1. Introduction The Transport layer is one of the most important layers of the Internet communication protocol stack. Located between the application and the network layers, this layer is expected to take into account both the application feature/requirements and the underlying network capabilities/constraints in order to provide the best end-to-end communication service, matching as much as possible the application requirements, still taking into account the opportunities and limitations of the underlying network. In the last few decades, several new applications and networking technologies have emerged with very different requirements and characteristics, making initial Transport-level protocols (typically TCP and UDP in the Internet) no longer adapted. As a consequence , a lot of new Transport protocols and mechanisms have been proposed over the last 20 years in order to enhance both the Transport services offered to applications, and to optimize the usage of the different network technologies. Unfortunately, the factual observation is that all these new proposals are either not integrated in the actual operating systems (Windows, Linux, etc.), or hardly used in practice by the application developers, which in majority continue to use suboptimal TCP and UDP solutions. Since it is proved that these new propositions are widely more efficient than the actual used protocols, the main goals of this work are to identify the deploymen

A model based approach to communication protocol's self-adaptation

International audienceSelf-adaptiveness of communication protocols is a major issue in the conception of future services for the emergent networking technologies (wireless, mobiles, ad-hoc ...). After presenting the state of the various existing solutions for adaptation, we introduce a model of the decision process for the modular protocol architectures as a way to guide adaptability. This approach is further illustrated by a case study in the context of quality of service for IEEE 802.11e wireless networks

A model-based approach for self-adaptive Transport protocols

International audienceSelf-adaptation of communication protocols is a major issue in the conception of future services for the ambient Internet. These protocols will have to provide adequate services to complex, mobile, cooperative application with dynamic requirements distributed in highly heterogeneous environments, partially wireless and ad hoc with variable and evolutive constraints. In this highly dynamic context, providing efficient solutions requires handling adaptability not only at the behavioral level, but also at the architectural level. End-to-end modular architecture protocols are a promising solution to support architectural self-adaptation to the context. Following this approach, the contributions presented in this paper address the automated choice of internal architecture for configurable Transport level protocols. Tackling this need by means of informal models may lead to non generic and suboptimal solutions due to the complexity of the problem. We propose to guide adaptation by an analytical model which is then evaluated against simulation results

Un modèle de décision pour l'auto-adaptation des protocoles de communication

L'auto-adaptation des protocoles de communication est un enjeu majeur dans la conception des futurs services de l'Internet ambiant. Ceux-ci auront en effet à répondre aux besoins dynamiques d'applications complexes, mobiles et coopératives, distribuées dans des environnements réseaux hétérogènes, en partie sans fil et ad hoc, aux contraintes variables et évolutives. Dans ce nouveau contexte, dynamique à différents niveaux, les protocoles de bout en bout à architecture modulaire apparaissent comme un support privilégié pour l'auto-adaptation au contexte. Les contributions présentées dans cet article s'inscrivent dans cette approche et adressent le problème du choix d'architecture interne des protocoles auto configurables. Partant des propositions de protocoles à architecture modulaire issues des travaux de recherche actuels, nous proposons un modèle analytique pour guider le processus de décision, que nous confrontons ensuite, au travers d'un cas d'étude, à des mesures des performances réalisées sur une plateforme d'évaluation de protocoles à architecture configurable