Damien Charlet

Energetic performance of service-oriented multi-radio networks: issues and perspectives

Wireless devices now hold multiple radio interfaces, allowing to switch from one network to another according to required connectivity and related quality. Still, the selection of the best radio interface for a specific connection is under the responsibility of the end-user in most cases. Integrated multi-radio network management so as to improve the overall performance of the network(s) up to the software application layer, has led to a number of research efforts over the last few years. However, several challenges remain due to the inherent complexity of the problem. This paper specifically concentrates on the comprehensive analysis of energy-efficient multi-radio networking for pervasive computing. Building upon the service oriented architectural style, we consider pervasive networks of software services, which are deployed on the various networked nodes. The issue is then to optimize the energetic performance of the pervasive network through careful selection of the radio link over which service access should be realized for each such access. By considering the most common wireless interfaces in use today (Bluetooth, WiFi and GPRS), we introduce a formal model of service-oriented multi-radio networks. The proposed model enables characterizing the optimal network configuration in terms of energetic performance, which is shown to be a NP-hard problem and thus requires adequate approximation.

Refining WiFi Indoor Positioning Renders Pertinent Deploying Location-Based Multimedia Guide

If outdoor positioning is widely treated and quite precise, indoor or more generally in heterogeneous environment, the positioning (and also mobility prediction) requires consequent devices. The WiFi solution, easy to deploy and cheaper becomes today an alternative. Our refinement approach, which is based on, both a friis calibrated model and the referenced points, makes it competitive. The targeted applications require not only deployment and precision, but also diffusion of rich and interactive media flow

Energy-efficient middleware-layer multi-radio networking: An assessment in the area of service discovery

The massive deployment of mobile networks together with the emergence of powerful portable devices has given rise to pervasive computing environments. In such environments, mobile users may discover and access services offered in surrounding networks using Service Discovery Protocols (SDPs). However, several SDPs are currently in use, each one designed for a specific target network architecture and setting. As a result, in todays multi-radio networking environment, SDPs do not equally suit each radio interface. In order to provide effective service discovery in multi-radio networks, the most resource-efficient radio interface should be chosen with respect to two main criteria: the adequacy of the interface against the SDP to be used, and energy saving, which is crucial for battery-powered devices. Toward this goal, this article assesses how to effectively take advantage of the multiple radio interfaces now embedded within wireless devices with respect to energy consumption, from the standpoint of service discovery and access. It further investigates the adequacy of legacy SDPs with the various networks, so as to classify the most appropriate networks for each SDP. Exploitation of these results is finally investigated with the description of an energy-efficient algorithm for SDP-based context sensing in a multi-radio pervasive environment.

Friis and iterative trilateration based WiFi devices tracking

The spreading of the WiFi networks allows new applications. New problems bound to the mobility of the terminals arise. This article addresses the service continuity in mobility which requires terminal positioning. The solution proposed is iterative trilateration for which the distances are computed according to the signal strength. This solution is implemented in GeoMoVie, the mobility component in a multimedia content streaming platform. It is tested and validated with a heterogeneous indoor test bed. It is also advantageously compared with related work approaches.

A peer-to-peer approach for cache sibling

Nowadays, the data search concept on a peer-to-peer (P2P) network is more and more widely used. A new approach of this technique is the use of peer-to-peer technology for streaming video multimedia applications. The mobility of multimedia clients, and even the network architecture in some cases, must be integrated to every level of platform conception models so that efficiency, adaptability and extensibility may be optimal. The throughput on future-generation wireless networks allows the dispatching of several simultaneous multimedia streams. Moreover, the ability for those networks to handle download and upload throughputs provided real interactivity in future multimedia applications. We have developed a cache sibling architecture called PACS which aims at increasing data exchange between caches. This article deals with document exchanges between caches thanks to a P2P platform.

Service discovery in multi-radio networks: an assessment of existing protocols

The wide deployment of mobile networks and the emergence of powerful portable devices has given core to pervasive computing. As particularly addressed by Beyond 3G (B3G) networks, the recent evolution of mobile networks introduces the convergence of wireless technologies, where several radio interfaces are to be used concurrently. Thus, B3G-aware applications shall make the most effective use of this connectivity. In pervasive environments, mobile users may discover and access services offered on the networks using Service Discovery Protocols (SDPs). Several SDPs are currently in use, each one designed for specific target network architecture and setting. Thus, in a multi-radio environment, each SDP does not equally suit each radio interface. In order to provide effective service discovery in multi-radio networks, the most resource efficient interface shall be chosen with respect to two main criteria: the adequacy of the radio interface against the SDP to be used, and energy saving, which is crucial for battery-powered devices. Toward this goal, this paper assesses how to exploit multiple radio interfaces from the standpoint of service discovery and access with respect to energy consumption, and the adequacy of the legacy SDPs with the various networks, so as to classify the most appropriate networks for each SDP.

Positioning Awareness: an Essential Component for Mobile Multimedia Applications

The spreading of the WiFi networks allows new applications. New problems bound to the mobility of the terminals arise. In this article, we deal with the requirements and the solutions to address the service continuity in mobility. These requirements are integrated in mobility management middleware. It requires terminal positioning. The solution proposed is trilateration for which the distances are computed according to the signal strength. To provide the service continuity, the mechanism called handover is used. It requires an anticipation which is realized through mobility prediction. The handover is done transparently by an adapted protocol. All of these functions are implemented in GeoMoVie, the mobility component in a multimedia content streaming platform

Optimisation du cache sibling à l'aide d'une architecture pair à pair

Nowadays, the data search concept on a peer to peer (P2P) network is more and more widely used. A new approach of this technique is the use of peer to peer technology for streaming video multimedia applications.The throughputs on future-generation wireless networks will be able to dispatch several multimedia streams simultaneously and their capabilities to handle download and upload throughputs will provide real interactivity in future multimedia applications. We have developed a cache sibling architecture called PACS whose issue is to increase the data exchange between caches. In this article, we intend to deal with document exchanges between caches thanks to a P2P platform.