Randomized rounding algorithms for large scale unsplittable flow problems

Unsplittable flow problems cover a wide range of telecommunication and transportation problems and their efficient resolution is key to a number of applications. In this work, we study algorithms that can scale up to large graphs and important numbers of commodities. We present and analyze in detail a heuristic based on the linear relaxation of the problem and randomized rounding. We provide empirical evidence that this approach is competitive with state-of-the-art resolution methods either by its scaling performance or by the quality of its solutions. We provide a variation of the heuristic which has the same approximation factor as the state-of-the-art approximation algorithm. We also derive a tighter analysis for the approximation factor of both the variation and the state-of-the-art algorithm. We introduce a new objective function for the unsplittable flow problem and discuss its differences with the classical congestion objective function. Finally, we discuss the gap in practical performance and theoretical guarantees between all the aforementioned algorithms

Randomized rounding algorithms for large scale unsplittable flow problems

Unsplittable flow problems cover a wide range of telecommunication and transporta- tion problems and their efficient resolution is key to a number of applications. In this work, we study algorithms that can scale up to large graphs and important num- bers of commodities. We present and analyze in detail a heuristic based on the linear relaxation of the problem and randomized rounding. We provide empirical evidence that this approach is competitive with state-of-the-art resolution methods either by its scaling performance or by the quality of its solutions. We provide a variation of the heuristic which has the same approximation factor as the state-of-the-art approxima- tion algorithm. We also derive a tighter analysis for the approximation factor of both the variation and the state-of-the-art algorithm. We introduce a new objective function for the unsplittable flow problem and discuss its differences with the classical con- gestion objective function. Finally, we discuss the gap in practical performance and theoretical guarantees between all the aforementioned algorithms

Protocol Stack Options in Heterogeneous Aeronautical Networks

In the future the amount of air traffic as well as the total data traffic volume of aeronautical communication will significantly increase. A single terrestrial technology alone will likely not be able to manage this challenge but satellite communication systems will serve as complement to direct air to ground data links. The future Air Traffic management (ATM) will thus consist of highly heterogeneous networks consisting of diverse technologies. It is highly important to design the network protocol stack in a way that allows interoperability of all involved networks while being transparent to the end users and providing the required levels of QoS performance, especially in the presence of transport layer protocols like TCP. This paper presents three different protocol stack alternatives dealing with the mentioned issues, investigates their advantages and disadvantages and proposes a protocol stack fitting the needs of ATM communications

Satellite and Terrestrial Hybrid Networks

International audienceThis book offers the reader the keys for a successful understanding, integration and usage of satellite systems in addition to next generation terrestrial networks. The DVB-S2/RCS system is used to illustrate the integration challenges. The presentation uses a system approach, i.e. it tackles the terrestrial and satellite telecommunication systems’ complexity with a high level approach, focusing on the systems’ components and on their interactions. Several scenarios present the different paths that can be followed for the integration of satellite systems in terrestrial networks. Quality of Service management techniques in terrestrial and satellite systems and the solutions to help them to interoperate are provided. Inter-system mobility solutions and performance problems are then addressed. The solutions proposed in this book have been developed within the framework of European and French funded research projects and tested with simulated or real testbeds

Les réseaux hybrides satellites et terrestres

International audienceCet ouvrage présente différentes approches permettant une intégration réussie des systèmes de communication par satellite dans les réseaux terrestres de prochaine génération. Les solutions proposées ont été développées et testées au cours de plusieurs projets de recherche européens et nationaux. Ces challenges techniques sont notamment illustrés par l’utilisation en exemple de systèmes de la famille DVB-S/RCS. S’appuyant sur l’étude des composants systèmes et leurs interactions, Les réseaux hybrides satellites et terrestres analyse la complexité des réseaux de télécommunication terrestres et satellites par une approche haut niveau. Plusieurs scénarios proposent différentes voies pour réaliser cette intégration avec succès. Les principes de gestion de la qualité de service dans les réseaux terrestres et satellites ainsi que les solutions pour les faire interopérer sont décrits. La gestion de la mobilité inter-systèmes et les problèmes de performance sont également détaillés

Satellite and Terrestrial Hybrid Networks

International audienceThis book offers the reader the keys for a successful understanding, integration and usage of satellite systems in addition to next generation terrestrial networks. The DVB-S2/RCS system is used to illustrate the integration challenges. The presentation uses a system approach, i.e. it tackles the terrestrial and satellite telecommunication systems’ complexity with a high level approach, focusing on the systems’ components and on their interactions. Several scenarios present the different paths that can be followed for the integration of satellite systems in terrestrial networks. Quality of Service management techniques in terrestrial and satellite systems and the solutions to help them to interoperate are provided. Inter-system mobility solutions and performance problems are then addressed. The solutions proposed in this book have been developed within the framework of European and French funded research projects and tested with simulated or real testbeds

Dynamic QoS Configuration of a DVB-RCS Satellite Terminal for SIPbased Applications

International audienceSatellite systems were long-dedicated mainly to broadcast services as television whereas Internet access was offered by terrestrial networks as DSL technologies. However, the democratization of DVB-S terminal, the standardization of a return channel via satellite (DVB-RCS) and the significant breakthroughs leading to DVB-S2 standard have allowed them to represent an interesting alternative to terrestrial networks in remote areas. But, to be competitive, DVB-S2/RCS systems have to offer an appropriate support to the variety of current and future multimedia applications (VoIP, videoconferencing) by providing QoS guarantees in spite of its specific characteristics: a long transmission delay and a limited bandwidth. In this context, this paper considers a DiffServ architecture, compliant with the SatLabs recommandations, in which three classes are considered at the IP layer to differentiate the traffic: EF, dedicated to real-time applications with strong time-constraints, AF used for non real-time applications and BE. Each Diffserv classe is mapped on a specific MAC queue to take benefit of the DAMA (Demand Assignment Multiple Access) mechanisms which allow the ST to dynamically request capacity to the NCC (Network Control Center). The goal of this work is to configure dynamically the DiffServ classes of service of the Linux-based ST for interactive applications, as VoIP, by using the session descriptors contained in SIP messages. For that, a complete QoS architecture based on the communication between an enhanced SIP proxy and a QoS Server and/or an ARC (Access Resource Controller) has been designed, developed and evaluated on a satellite network emulation testbed (PLATINE), implemented in the SatIP6 and SatSIX IST projects

Functional Building Blocks for an Integrated Aeronautical IP-Network

Within the next 10-15 years, air-traffic management (ATM) will be primarily based on data communications and voice communication will be mostly used as fallback solution. Furthermore, it is foreseen that IP-based networking solutions for A/G communication will be deployed for cost savings, high reliability and an optimal alignment with the evolution of communication and security technologies. Such an efficient and sustainable data network for aeronautical communications is required to enable the implementation of a range of operational improvements needed to support the expected growth in air transportation. An IP-based global aeronautical communication network is currently being developed within the NEWSKY project, co-funded by the European Commission and in close collaboration with Eurocontrol and ICAO ACP WG-I (Specification of ATN/IPS). NEWSKY pursues the vision of "Networking the Sky" by integrating different data link technologies (long range A/G links, airport links, satellite links) and different services (ATS, AOC/AAC, APC) in a single, seamless network. Key functionalities have been identified, namely resource management, mobility, security and end-to-end data transport. In this paper, the raw functional architecture and the ongoing activities towards the specification of the functional modules are investigated