Pascal Berthou

An energy-efficient clock synchronization protocol for Wireless Sensor Networks

The behavior of Wireless Sensor Networks (WSN) is nowadays widely analyzed. One of the most important issues is related to their energy consumption, as this has a major impact on the network lifetime. Another important application requirement is to ensure data sensing synchronization, which leads to additional energy consumption as a high number of messages is sent and received at each node. Our proposal consists in implementing a combined synchronization protocol based on the IEEE 1588 standard that was designed for wired networks and the PBS (Pairwise Broadcast Synchronization) protocol that was designed for sensor networks, as none of them is able to provide the needed synchronization accuracy for our application on its own. The main goals of our new synchronization protocol are: to ensure the accuracy of local clocks up to a tenth of a microsecond and to provide an important energy saving. Our results obtained using NS-2 (Network Simulator) show that the performance of our solution (IEEE 1588-PBS) matches our application requirements with regard to the synchronization, with a significant improvement in energy saving.

PLATINE: DVB-S2/RCS Enhanced Testbed for Next Generation Satellite Networks

Emulation is a cost effective and efficient tool to perform performances evaluation and innovative access and network techniques validation. Its ability to interconnect real equipments with real applications provides excellent demonstrations means. The main problem is to overcome the emulation weakness which is the accuracy of the model reproducing the systems to be evaluated. Owing to its modular design and implementation, the PLATINE satellite emulation platform, presented in this paper, is able to emulate a complete DVB-RCS (Digital Video Broadcasting – Return Channel via Satellite)- DVB-S2 (Digital Video Broadcasting – Second ) system in a realistic and flexible way. It is possible to configure the platform to emulate a transparent DVBRCS system dimensioned around a single Hub, or to emulate a system using a regenerative satellite with an on-board switching matrix. Different DVB-RCS protocol stacks are implemented, and the adaptive physical layer is emulated in real time thanks to pre-calculated DRA schemes and MODCOD files. A DiffServ-like QoS Architecture that couples MAC and IP-Layer QoS mechanisms and Layer 2 security framework are currently under development. At the network side, IPv4 and IPv6 are fully supported as well as IPv6 mobility and dynamic multicast. In this paper, we mainly focus on the emulation platform and the tools developed to help the performance analysis of the emulated system.

A QoS Architecture for DVB-RCS Next Generation Satellite Networks

The standardization of a return channel via satellite (DVB-RCS) and satellite community efforts in term of interoperability over the last few years leads to quite a positive outcome: geostationary satellite networks are intended to provide broadband access to interactive multimedia services in low-infrastructure areas. However, in order to take in account real-time multimedia traffic, an efficient resource management scheme is still necessary to maximize the scarce uplink capacities usage. To address this capacity issue, this paper proposes a complete DVB-RCS QoS architecture that is implemented, thanks to an emulation platform, and evaluated with real multimedia applications. This paper first gives an overview of the QoS architecture usually used in DVB-S/RCS satellite system, especially in layers 2 and 3. It then introduces the satellite system emulation used in the experimentation and its calibration. The main contribution of this work focuses on the signaling principle designed to allow applications to take benefit from the QoS features of the satellite system even if they are non-QoS aware. It is then shown how signaling in such QoS architecture allows the user to change dynamically the QoS of his application using QoS agent and QoS server applications even if the application is not QoS-aware. It is also given quantitative results related to such a dynamic QoS change in the experiments done on the satellite emulation system.

Miniaturized Wireless Sensor Networks

This paper addresses an overview of the wireless sensor networks. It is shown that MEMS/NEMS technologies and SIP concept are well suited for advanced architectures. It is also shown analog architectures have to be compatible with digital signal techniques to develop smart network of microsystem

A Reconfigurable IR-UWB Radio Interface, with Directional Antennas and Localization Capability, for Wireless Sensor Networks

This paper proposes an IR-UWB radio interface layer which is able to deal with WSN context. With this intention, we present a reconfigurable IR-UWB with directional antennas and localization capability at 60 GHz. We introduce the advantages of using the millimeter band, directional antennas, localization and the reconfigurability. We also propose some implementations on a FPGA receiver.

On designing sensor networks with smart antennas

Wireless sensor networks (WSN) is an active research area. The recent advances in the fields of antennae and transmission lets consider massive improvements in the energy and communication management of WSN. However, the new WSN architectures have to evolve to take it into account. This paper presents an extension of the IEEE 802.15.4 protocol to take benefits of smart antennas technology. NS-2 simulations show the feasibility and the benefits of such architecture.

Towards application driven networking

In order to address the performance problems that many business applications are experiencing, network vendors and Network Service Providers are reconsidering the integration of some form of application awareness in the way their networks forward user traffic. Their ultimate goal is to devise new network service models that are dedicated and customized to applications. This trend is mainly enabled by the emergence of software-Defined networking (SDN), which allows for flexible flow-based forwarding. This paper proposes an SDN-based Application Driven Network (ADN) that deploys customized data paths on an application basis, that the ADN is able to adapt to meet the, potentially, varying Quality of Service (QoS) needs of applications. These needs are, either, explicitly expressed and submitted by the middleware or by an application agent, or inferred by the proposed ADN with DPI (Deep Packet Inspection) based traffic classification techniques. This paper presents the general architecture of our proposed ADN by describing its main components, their requirements as well as their main algorithms. The proposed ADN has been implemented, evaluated and applied to the OMG Data Distribution Service (DDS) based distributed applications in an enterprise network context.

A Web Services Based Resource Signaling Scheme in Multimedia Satellite Systems

This paper introduces a Web services based approach that extends resource reservation mechanism for interactive multimedia applications over multimedia satellite systems. It proposes a flexible and extensible scheme for the discovery of services in the network and the configuration of the satellite terminal when resources are requested. It finally presents experimental results of the proposed scheme over a realistic DVB-S2/RCS emulation platform.

A Generic and Configurable Topology Discovery Service for Software Defined Wireless Multi-Hop Network

We present a topology discovery service for software-defined wireless multi-hop networks, which is capable of capturing rich information about the network topology, such as link quality, interference and node characteristics etc., to effectively support the requirements of higher-layer SDN applications such as routing, channel allocation and transmission power control with enhanced flexibility. We analyse the general topology representation required by such SDN applications and specify the procedure and mechanism required at the controller and nodes to maintain this representation. A proof-of-concept implementation of our service on an SDN enabled multi-channel multi-interface wireless multi-hop network testbed shows the feasibility of our proposal.

Which Transport Protocol for Hybrid Terrestrial and Satellite Systems

Satellite systems complement terrestrial networks where the network could not be deployed for technical or economical reasons. Moreover, the natural broadcasting capacity of satellite networks makes it a good companion to terrestrial networks. In this context, future services will be deployed over networks that combine terrestrial and satellite systems. The infrastructure heterogeneity could be problematic, especially because of the delays variation. This article presents the problem from the point of view of the transport layer, the layer directly connected to the application, and compares several solutions to help future service developers using such network configuration.