Un s\u00e9minaire du p\u00f4le T\u00e9l\u00e9coms et R\u00e9seaux pr\u00e9vu le mardi 3 novembre \u00e0 14h (salle de conseil, LSS, SUPELEC). Ce s\u00e9minaire s’inscrit dans le cadre des s\u00e9minaires DigiCosme, il est donc ouvert \u00e0 toutes les \u00e9quipes du Labex travaillant sur ce th\u00e8me. <\/p>\n
Deux expos\u00e9s sont pr\u00e9vus :<\/strong><\/p>\n \n1) \u00ab\u00a0Communications A\/V de qualit\u00e9 sans (?) infrastructure\u00a0\u00bb, par Mr Jean-Charles Gr\u00e9goire (INRS, Canada)<\/p>\n R\u00e9sum\u00e9 : Nous assistons depuis quelques ann\u00e9es \u00e0 une transformation dans la nature de certaines communications audio-visuelles sur l’Internet: leur imbrication au sein d’environnements comme des plateformes sociales. Cette transition d’environnement d\u00e9di\u00e9 vers composante imbriqu\u00e9e a eu des effets notables sur la mani\u00e8re dont la qualit\u00e9 de service est appr\u00e9hend\u00e9e et g\u00e9r\u00e9e dans ces environnements, principalement dans des mod\u00e8les \u00ab over the top \u00bb, et soul\u00e8ve d’autres questions sur le lien avec les infrastructures de communication traditionnelles.<\/p>\n Nous pr\u00e9sentons ici la probl\u00e9matique des communications A\/V OTT et discutons plus en profondeur deux \u00e9l\u00e9ments cl\u00e9s, \u00e0 savoir les nouvelles architectures de service dans lesquelles elles sont d\u00e9ploy\u00e9es, et les approches de gestion et de substitution \u00e0 la qualit\u00e9 de service. Nous ferons le point sur l’\u00e9tat de l’art en la mati\u00e8re ainsi que sur des travaux en cours \u00e0 l’INRS.<\/p>\n Bio: Le professeur Gr\u00e9goire est dipl\u00f4m\u00e9 de la Facult\u00e9 polytechnique de Mons (Belgique). Il d\u00e9tient une Ma\u00eetrise en math\u00e9matiques de l’University of Waterloo (Canada) et un Doctorat en g\u00e9nie de l’Ecole polytechnique f\u00e9d\u00e9rale de Lausanne (Suisse). Il est pr\u00e9sentement professeur \u00e0 l’Institut national de la recherche scientifique (INRS), dans le secteur des t\u00e9l\u00e9communications.<\/p>\n Le professeur Gr\u00e9goire poursuit des travaux de recherche sur les syst\u00e8mes de communication r\u00e9partis et leur implantation dans le contexte de l’Internet. Il a de nombreuses publications sur des sujets divers qui touchent \u00e0 la s\u00e9curit\u00e9, \u00e0 la qualit\u00e9 des applications multim\u00e9dia, aux r\u00e9seaux d’acc\u00e8s et aux architectures de service sur l’Internet. A travers sa carri\u00e8re, il a \u00e9galement entretenu des collaborations fructueuses avec diverses compagnies du secteur des t\u00e9l\u00e9communications. <\/p>\n 2) \u00ab\u00a0Modulated Erlang loss models: How traffic correlation affects the square-root staffing rule\u00a0\u00bb, par KOEN DE TURCK, O2MR, LSS. <\/p>\n Abstract: In this talk, we revisit the classical question of how many servers must one provision in order to guarantee on the one hand a good quality of service to the customer (that is, a limited amount of blocked calls), while on the other hand ensuring an efficient operation of the system, with few idle servers. Since the celebrated work of Halfin and Whitt, we know that for a Poisson arrival stream and a large load \\rho, the ideal number of servers must be around $\\rho + \\beta \\sqrt\\rho<\/em>$, where $\\beta$ is some hedge factor. This is the square-root staffing rule and the intuition behind it is that one must cater for at least the expected system contents $\\rho$, but also provide some ‘wiggle room’ for common fluctuations around the mean. The hedge factor \\beta represents the aforementioned tradeoff: the larger $\\beta$, the better the quality of service but also the more expensive to the service provider.<\/p>\n As we know, real world traffic often exhibits a large degree of correlation and hence the Poisson assumption is not really valid. Hence, we look at Markov modulated arrival streams, and speed them up at a different rate than we scale the load. We find three different regimes depending on the speed of the modulated chaiin, and a considerably altered staffing rule when said speed is slow.<\/p>\n Short bio: Koen De Turck obtained a master and a PhD in engineering from Ghent University, Belgium. Since July 2015, he is an assistant professor at CentraleSup\u00e9lec, where he is a member of the lab Signaux et Syst\u00e8mes (L2S).<\/p>\n He develops and studies stochastic models for telecommunication networks in general and wireless networks in particular. His favorite tools include queuing theory, scaling techniques, large deviations and evolutionary game theory.<\/p>\n","protected":false},"excerpt":{"rendered":" Un s\u00e9minaire du p\u00f4le T\u00e9l\u00e9coms et R\u00e9seaux pr\u00e9vu le mardi 3 novembre \u00e0 14h (salle de conseil, LSS, SUPELEC). Ce s\u00e9minaire s’inscrit dans le cadre des s\u00e9minaires DigiCosme, il est donc ouvert \u00e0 toutes les \u00e9quipes du Labex travaillant sur ce th\u00e8me. Deux expos\u00e9s sont pr\u00e9vus : 1) \u00ab\u00a0Communications A\/V de qualit\u00e9 sans (?) infrastructure\u00a0\u00bb, 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