Orange S.A.

About: Orange S.A. is a company organization based out in Paris, France. It is known for research contribution in the topics: Terminal (electronics) & Signal. The organization has 6735 authors who have published 9190 publications receiving 156440 citations. The organization is also known as: Orange SA & France Télécom.

Modeling and verification of a telecommunication application using live sequence charts and the play-engine tool

Abstract: We apply the language of live sequence charts (LSCs) and the Play-Engine tool to a real-world complex telecommunication service. The service, called Depannage, allows a user to make a phone call and ask for help from a doctor, the fire brigade, a car maintenance service, etc. This kind of service is built on top of an embedded platform, using both new and existing service components. The complexity of such applications stems from their distributed architecture, the various time constraints they entail, and the fact the underlying systems are rapidly evolving, introducing new components, protocols and associated hardware constraints, all of which must be taken into account. We present the results of our work on the specification, animation and formal verification of the Depannage service, and draw some initial conclusions as to an appropriate methodology for using a scenario-based approach in the telecommunication domain. The complete specification of the Depannage application in LSCs and some animations showing simulation and verification results are made available as supplementary material.

Dimensioning high speed IP access networks

Abstract: This paper discusses the definition of simple dimensioning rules for high speed IP access networks carrying data traffic. We notably provide formulas relating capacity, demand and performance allowing dimensioning for a target quality of service expressed in terms of useful per-flow throughput. These formulas derive from a data traffic model equivalent of the Engset model for telephone access networks. Performance is shown to be largely independent of precise traffic characteristics. The key dimensioning parameter is offered traffic defined as the average data rate a user would generate in the absence of congestion.

Modular System Verification by Inference, Testing and Reachability Analysis

Abstract: Verification of a modular system composed of communicating components is a difficult problem, especially when the models of the components are not available. Conventional testing techniques are not efficient in detecting erroneous interactions of components because such interactions often occur as interleavings of events that are difficult to reproduce in a modular system. The problem of detecting intermittent errors in the absence of models of components is addressed in this paper. A method to infer a controllable approximation of components through testing is elaborated. The inferred finite state models of components are used to detect intermittent errors and other compositional problems in the system through reachability analysis. The models are refined at each analysis step thus making the approach iterative.

Ultraviolet-induced permanent Bragg gratings in cerium-doped ZBLAN glasses or optical fibers.

Abstract: A holographic method was used to write refractive-index gratings in ZBLAN fluoroziroconate glasses or fibers doped by a Ce concentration of 5000 or 10,000 parts-in-10(6) weight. Direct pumping of the (2)F(5/2)-5d transitions of Ce(3+) ions near 245 nm resulted in a change in the refractive index. The photoinduced change partly recovered on a time scale of several hours at room temperature. The remaining change in the refractive index looked stable on a time scale of a month. This permanent change reaches 2 x 10(-5) at 1560 nm.

Performance evaluation of admission control and adaptive modulation in OFDMA WiMax systems

Abstract: In this paper, we study the performance of multi-cell OFDMA WiMAX systems, in both downlink and uplink. We calculate analytically the number of collisions when the number of users in each cell is known. We then calculate the QoS indicators (e.g., blocking rates, download time and bit error rates) taking into account the physical layer conditions (modulation, propagation and MIMO), the MAC layer techniques (HARQ and radio resource management algorithms) and the traffic characteristics, in a cross-layer approach. We finally evaluate the impact of using adaptive modulation and coding on the overall performance of the system. This analysis allows us to calculate the Erlang capacity of a WiMAX system. Our numerical applications then show how to choose the best admission control and modulation schemes that extend the Erlang capacity region.