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A wireless sensor network is a wireless network of sensors aimed at monitoring physical events. It has ingratiated itself into almost all areas of human endeavors. Data dissemination in these networks is quite challenging and is generally accomplished by flooding. But flooding introduces broadcast storm problem due from implosion and overlap. To overcome this, topology management can prescribe a virtual backbone network to which routing is confined. In this paper we propose an algorithm that constructs multiple disjoint virtual backbone networks, using only nodes' locations. The disjointedness makes routing more robust and the network exploitation energy efficient. Simulations show our algorithm quite efficient, especially when applied to a network with density exceeding a certain limit. A rough estimate shows that our solution has an approximation ratio of 3.7. This is amongst the best we have seen so far.

We consider the following list coloring with separation problem of graphs: Given a graph $G$ and integers $a,b$, find the largest integer $c$ such that for any list assignment $L$ of $G$ with $|L(v)|\le a$ for any vertex $v$ and $|L(u)\cap L(v)|\le c$ for any edge $uv$ of $G$, there exists an assignment $\varphi$ of sets of integers to the vertices of $G$ such that $\varphi(u)\subset L(u)$ and $|\varphi(v)|=b$ for any vertex $v$ and $\varphi(u)\cap \varphi(v)=\emptyset$ for any edge $uv$. Such a value of $c$ is called the separation number of $(G,a,b)$. We also study the variant called the free-separation number which is defined analogously but assuming that one arbitrary vertex is precolored. We determine the separation number and free-separation number of the cycle and derive from them the free-separation number of a cactus. We also present a lower bound for the separation and free-separation numbers of outerplanar graphs of girth $g\ge 5$.

Access Control is an important security service that should be considered in IoT environments in order to offer reliable IoT services. Access control in IoT environments concerns not only the access of IoT users to IoT services and objects, but also the access of IoT objects to IoT gateways. In this paper, we specify an access control mechanism that considers the access of IoT objects to IoT gateways in order to enhance the reliability of IoT data provided by the IoT objects. Our proposed access control mechanism, called IoT-MAAC (Multi Attribute Access Control), allows retrieving requested data from the most reliable and secured IoT objects among the available objects in the IoT environments.

Although it has recently been proved that the packing chromatic number is unbounded on the class of subcubic graphs, there exist subclasses in which the packing chromatic number is finite (and small). These subclasses include subcubic trees, base-3 Sierpiński graphs and hexagonal lattices. In this paper we are interested in the packing chromatic number of subcubic outerplanar graphs. We provide asymptotic bounds depending on structural properties of the outerplanar graphs and determine sharper bounds for some classes of subcubic outerplanar graphs. Přestože bylo nedávno ukázáno, že na třídě subkubických grafů není pakovací chromatické číslo obecně omezené, existují třídy subkubických grafů s konečným pakovacím chromatickým číslem. Mezi tyto třídy patří např. subkubické stromy, 3-Sierpińského grafy a hexagonální mřížky. V tomto článku se autoři zabývají pakovacím chromatickým číslem subkubických vnějškově rovinných grafů. Jsou zde dokázány meze tohoto čísla pomocí strukturálních vlastností těchto grafů a pro některé jejich podtřídy jsou stanoveny přesnější horní odhady tohoto čísla.

Given a graph $G$, the exact distance-$p$ graph $G^{[\natural p]}$ has $V(G)$ as its vertex set, and two vertices are adjacent whenever the distance between them in $G$ equals $p$. We present formulas describing the structure of exact distance-$p$ graphs of the Cartesian, the strong, and the lexicographic product. We prove such formulas for the exact distance-$2$ graphs of direct products of graphs. We also consider infinite grids and some other product structures. We characterize the products of graphs of which exact distance graphs are connected. The exact distance-$p$ graphs of hypercubes $Q_n$ are also studied. As these graphs contain generalized Johnson graphs as induced subgraphs, we use some known and find some new constructions of their colorings. These constructions are applied for colorings of the exact distance-$p$ graphs of hypercubes with the focus on the chromatic number of $Q_{n}^{[\natural p]}$ for $p\in \{n-2,n-3,n-4\}$.

Given a non-decreasing sequence S = ( s 1 , s 2 , … , s k ) of positive integers, an S -packing edge-coloring of a graph G is a partition of the edge set of G into k subsets { X 1 , X 2 , … , X k } such that for each 1 ≤ i ≤ k , the distance between two distinct edges e , e ′ ∈ X i is at least s i + 1 (where the edge-distance in G is defined as the vertex-distance in the line-graph of G ). This paper studies S -packing edge-colorings of cubic graphs. Among other results, we prove that cubic graphs having a 2-factor are ( 1 , 1 , 1 , 3 , 3 ) -packing edge-colorable, ( 1 , 1 , 1 , 4 , 4 , 4 , 4 , 4 ) -packing edge-colorable and ( 1 , 1 , 2 , 2 , 2 , 2 , 2 ) -packing edge-colorable. We determine sharper results for cubic graphs of bounded oddness and 3-edge-colorable cubic graphs and we propose many open problems.

International audience; Let k >= 2 be an integer and T-1,..., T-k be spanning trees of a graph G. If for any pair of vertices {u, v} of V(G), the paths between u and v in every T-i, 1

International audience; Multi-path routing concept was largely exploited in wireless networks to provide benefits such as fault tolerance, load balancing, performance improvement in terms of latency, etc. In this paper, we propose a multi-path routing based protocol named MP-IMRR (Multi-path Intra-Mesh infrastructure Routing protocol) to improve our previously defined QoS based routing protocol for wireless mesh networks (i.e. IMRR). MP-IMRR is defined in order to achieve better reactivity and faster recovery from eventual route failures than the IMRR protocol by adopting the backup routes concept. Besides, given the complexity increase while considering network management systems, we adopt the autonomic computing paradigm to provide the IMRR routing protocol with self-configuring capabilities. We describe and analyze the simulation results of different scenarios conducted on the network simulator ns-3 to demonstrate the effectiveness of IMRR self-configuring scheme and MP-IMRR routing protocol in case of route failures.

International audience; Quality of service (QoS) in wireless mesh networks is an active area of research, which is driven by the increasing demand for real-time and multimedia applications, such as Voice over IP and Video on Demand. In this paper, we propose a novel QoS based routing protocol for wireless mesh infrastructure, called Hybrid QoS Mesh Routing (HQMR). It is composed of two QoS based routing sub-protocols: a reactive multi-metric routing protocol for intra-infrastructure communications and a proactive multi-tree based routing protocol for communications with external networks. The proposed routing protocol enables forwarding real-time and streaming applications with QoS guarantee in a mesh wireless environment, by assigning a specific routing path for each defined service class. To this end, three different QoS service classes are defined, depending on the applications requirements. We analyze in this paper the simulation results of different scenarios conducted on the network simulator ns-3 to demonstrate the effectiveness of the HQMR protocol and to compare it to other routing protocols while forwarding real-time applications with QoS guarantee.

International audience; Gyarfas et al. and Zaker have proven that the Grundy number of a graph G satisfies Gamma(G) >= t if and only if G contains an induced subgraph called a t-atom. The family of t-atoms has bounded order and contains a finite number of graphs. In this article, we introduce equivalents of t-atoms for b-coloring and partial Grundy coloring. This concept is used to prove that determining if phi(G) >= t and partial derivative Gamma(G) >= t (under conditions for the b-coloring), for a graph G, is in XP with parameter t. We illustrate the utility of the concept of t-atoms by giving results on b-critical vertices and edges, on b-perfect graphs and on graphs of girth at least 7. (C) 2016 Elsevier B.V. All rights reserved.

Part 5: Network Protocols; International audience; Quality of service (QoS) in wireless mesh networks (WMN) is an active area of research, which is driven by the increasing demand for real-time and multimedia applications, such as VoIP (Voice over IP) and VoD (Video on Demand). In this paper, we propose a QoS multi-tree based routing protocol for wireless mesh environments, named Inter-Mesh Infrastructure Proactive Routing (IMPR). It is a proactive multi-tree routing protocol enabling QoS guarantee for communications from/towards the Internet network through the Mesh Gateway (MG) of the mesh infrastructure. We describe and analyze the simulation results of different scenarios conducted on the network simulator ns-3 to demonstrate the effectiveness of our IMPR routing protocol in forwarding real-time applications with QoS guarantee.

International audience; A graph $G$ is free $(a,b)$-choosable if for any vertex $v$ with $b$ colors assigned and for any list of colors of size $a$ associated with each vertex $u\ne v$, the coloring can be completed by choosing for $u$ a subset of $b$ colors such that adjacent vertices are colored with disjoint color sets. In this note, a necessary and sufficient condition for a cycle to be free $(a,b)$-choosable is given. As a corollary, some choosability results are derived for graphs in which cycles are connected by a tree structure.

International audience; Today, the Cloud networking aspect is a critical factor for adopting the Cloud computing approach. The main drawback of Cloud networking consists in the lack of Quality of Service (QoS) guarantee and management in conformance with a corresponding Service Level Agreement (SLA). This paper presents a framework for resource allocation according to an end-to-end SLA established between a Cloud Service User (CSU) and several Cloud Service Providers (CSPs) in a Cloud networking environment. We focus on QoS parameters for Network as a Service (NaaS) and Infrastructure as a Service (IaaS) services. In addition, we propose algorithms for the best CSPs selection to allocate Virtual Machines (VMs) and network resources in inter-cloud broker and federation scenarios. Our objective is to minimize the cost while satisfying NaaS and IaaS QoS constraints. Moreover, we simulate our proposed Cloud networking architecture to provide videoconferencing and intensive computing applications with QoS guarantee. We observe that the broker architecture is the most interesting while ensuring QoS requirements.

An ?$i$?-packing in a graph ?$G$? is a set of vertices at pairwise distance greater than ?$i$?. For a nondecreasing sequence of integers ?$S=(s_1,s_2,\ldots)$?, the?$S$?-packing chromatic number of a graph ?$G$? is the least integer ?$k$? such that there exists a coloring of ?$G$? into ?$k$? colors where each set of vertices colored ?$i$?, ?$i=1,\ldots,k$?, is an ?$s_i$?-packing. This paper describes various subdivisions of an ?$i$?-packing into ?$j$?-packings ?$(j>i)$? for the hexagonal, square and triangular lattices. These results allow us to bound the ?$S$?-packing chromatic number for these graphs, with more precise bounds and exact values for sequences ?$S=(s_i,i \in \mathbb{N}^*)$?, ?$s_i = d+ \lfloor (i-1)/n \rfloor$?. Množici vozlišč grafa ?$G$?, paroma oddaljenih za več kot ?$i$?, pravimo ?$i$?-pakiranje. Če je ?$S=(s_1,s_2,\ldots)$? nepadajoče zaporedje celih števil, potem je ?$S$?-pakirno kromatsko število grafa ?$G$? najmanjše celo število ?$k$?, pri katerem obstaja barvanje grafa ?$G$? s ?$k$? barvami, v katerem vsaka množica vozlišč, pobarvanih z barvo ?$i$?, ?$i=1,\ldots,k$?, predstavlja ?$s_i$?-pakiranje. Članek opisuje različne podrazdelitve ?$i$?-pakiranj na ?$j$?-pakiranja ?$(j>i)$? za šestkotniške, kvadratne in trikotniške mreže. Ti rezultati nam omogočajo omejiti ?$S$?-pakirno kromatsko število teh grafov in določiti natančnejše meje in natančne vrednosti za zaporedja ?$S=(s_i,i \in \mathbb{N}^*)$?, ?$s_i = d+ \lfloor (i-1)/n \rfloor$?.

The radio antipodal number of a graph $G$ is the smallest integer $c$ such that there exists an assignment $f\: V(G)\rightarrow \lbrace 1,2,\ldots ,c\rbrace $ satisfying $|f(u)-f(v)|\ge D-d(u,v)$ for every two distinct vertices $u$ and $v$ of $G$, where $D$ is the diameter of $G$. In this note we determine the exact value of the antipodal number of the path, thus answering the conjecture given in [G. Chartrand, D. Erwin and P. Zhang, Math. Bohem. 127 (2002), 57–69]. We also show the connections between this colouring and radio labelings.

Given the evolution of wireless technologies, Wireless Mesh Networks (WMN) have appeared as an emerging low-cost solution to ensure last-mile connectivity to the Internet network. However, providing real-time and streaming applications, such as VoIP (Voice over IP) and VoD (Video on Demand), with a satisfying QoS level is considered as an important challenge within these networks. In this paper, we propose a QoS based routing protocol, called Hybrid QoS Mesh Routing (HQMR), jointly with a clustering algorithm to improve the scalability of mesh networks. HQMR is composed of two routing sub- protocols: a reactive QoS based routing protocol for intra-mesh infrastructure communications and a proactive QoS based multi- tree routing protocol for communications with external networks. We analyze in this paper the simulation results of different scenarios conducted on the network simulator ns-3 to demonstrate the effectiveness of the reactive routing sub-protocol while forwarding real-time applications with a QoS guarantee.

Award of Appreciation; International audience; A key requirement to provide seamless mobility and guaranteeing Quality of Service in heterogeneous environment is to select the best destination network during handover. In this paper, we propose a new schema for network selection based on Multiple Linear Regression Model (MLRM). A horough investigation, on a huge live data collected from GPRS/UMTS networks led to identify the Key Performance Indicators (KPIs) that play the most important role in the handover process. These KPIs are: Received Signal Code Power (RSCP), received energy per chip (Ec/No) and Available Bandwidth (ABW) of the destination network. To extract a handover model from collected data, we study the correlation among values of identified KPIs parameters, before, during and after handover, thanks to a statistical learning approach, using the predictive analytics software SPSS. For model assessment, Pearson Correlation Coefficient and determination coefficient R-squared (R2) are used. Media Independent Handover (MIH) IEEE 802.21 standard is used in this work to retrieve the lower layer information of available networks and announce the handover needs (handover initiation). The proposed model will help to select the most appropriate network between many existing ones in the vicinity of the mobile node.

The packing chromatic number $\chi_{\rho}(G)$ of a graph $G$ is the smallest integer $p$ such that vertices of $G$ can be partitioned into disjoint classes $X_{1}, ..., X_{p}$ where vertices in $X_{i}$ have pairwise distance greater than $i$. For $k < t$ we study the packing chromatic number of infinite distance graphs $D(k, t)$, i.e. graphs with the set $\Z$ of integers as vertex set and in which two distinct vertices $i, j \in \Z$ are adjacent if and only if $|i - j| \in \{k, t\}$. We generalize results by Ekstein et al. for graphs $D (1, t)$. For sufficiently large $t$ we prove that $\chi_{\rho}(D(k, t)) \leq 30$ for both $k$, $t$ odd, and that $\chi_{\rho}(D(k, t)) \leq 56$ for exactly one of $k$, $t$ odd. We also give some upper and lower bounds for $\chi_{\rho}(D(k, t))$ with small $k$ and $t$. Keywords: distance graph; packing coloring; packing chromatic number, Comment: 15 pages

A radio $k$-labeling of a connected graph $G$ is an assignment $c$ of non negative integers to the vertices of $G$ such that $$|c(x) - c(y)| \geq k+1 - d(x,y),$$ for any two vertices $x$ and $y$, $x\ne y$, where $d(x,y)$ is the distance between $x$ and $y$ in $G$. In this paper, we study radio labelings of distance graphs, i.e., graphs with the set $\Z$ of integers as vertex set and in which two distinct vertices $i, j \in \Z$ are adjacent if and only if $|i - j| \in D$., 14 pages

A graph $G$ is $(a,b)$-choosable if for any color list of size $a$ associated with each vertices, one can choose a subset of $b$ colors such that adjacent vertices are colored with disjoint color sets. This paper shows an equivalence between the $(a,b)$-choosability of a graph and the $(a,b)$-choosability of one of its subgraphs called the extended core. As an application, this result allows to prove the $(5,2)$-choosability and $(7,3)$-colorability of triangle-free induced subgraphs of the triangular lattice., 10 pages

Graphs and Algorithms, For a set D ⊂ Zn, the distance graph Pn(D) has Zn as its vertex set and the edges are between vertices i and j with |i − j| ∈ D. The circulant graph Cn(D) is defined analogously by considering operations modulo n. The minimum feedback vertex set problem consists in finding the smallest number of vertices to be removed in order to cut all cycles in the graph. This paper studies the minimum feedback vertex set problem for some families of distance graphs and circulant graphs depending on the value of D.

International audience; Frequency planning consists in allocating frequencies to the transmitters of a cellular network so as to ensure that no pair of transmitters interfere. We study the problem of reducing interference by modeling this by a radio k-labeling problem on graphs: For a graph G and an integer k ≥ 1, a radio k-labeling of G is an assignment f of non negative integers to the vertices of G such that |f(x)−f(y)| ≥ k+1−dG(x,y), for any two vertices x and y, where dG(x,y) is the distance between x and y in G. The radio k-chromatic number is the minimum of max{f(x)−f(y):x,y ∈ V(G)} over all radio k-labelings f of G. In this paper we present the radio k-labeling for the Cartesian product of two graphs, providing upper bounds on the radio k-chromatic number for this product. These results help to determine upper and lower bounds for radio k-chromatic numbers of hypercubes and grids. In particular, we show that the ratio of upper and lower bounds of the radio number and the radio antipodal number of the square grid is asymptotically [3/2].

International audience; Motivated by problems in radio channel assignments, we consider radio k-labelings of graphs. For a connected graph G and an integer k ≥ 1, a linear radio k-labeling of G is an assignment f of nonnegative integers to the vertices of G such that |f(x)−f(y)| ≥ k+1−dG(x,y), for any two distinct vertices x and y, where dG(x,y) is the distance between x and y in G. A cyclic k-labeling of G is defined analogously by using the cyclic metric on the labels. In both cases, we are interested in minimizing the span of the labeling. The linear (cyclic, respectively) radio k-labeling number of G is the minimum span of a linear (cyclic, respectively) radio k-labeling of G. In this paper, linear and cyclic radio k-labeling numbers of paths, stars and trees are studied. For the path Pn of order n ≤ k+1, we completely determine the cyclic and linear radio k-labeling numbers. For 1 ≤ k ≤ n−2, a new improved lower bound for the linear radio k-labeling number is presented. Moreover, we give the exact value of the linear radio k-labeling number of stars and we present an upper bound for the linear radio k-labeling number of trees.

We give theoretical results obtained for wavelength routings in certain all-optical networks. In all-optical networks a single physical optical link can carry several logical signals provided that they are transmitted on different wavelengths. An all-to-all routing in a n -node network is a set of n(n−1) simple paths specified for every ordered pair (x,y) of nodes. The routing will be feasible if an assignment of wavelengths to the paths can be given such that no link will carry in the same direction two different paths of the routing on the same wavelength. With such a routing, it is possible to perform the gossiping in one round. The cost of the routing depends on the number of wavelengths it handles. We give the smallest necessary number of wavelength over all possible routings for networks based on certain compound graphs.

Wireless sensor networking is ingratiating itself into almost every area of human endeavors. Its drivers include its usages, improvements in microelectronics and manufacturing techniques. The network is made up of multiple tiny sensor nodes deployed in the area to be sensed, with nodes having processing, communicating, and sensing capabilities that enable them to perform their function collaboratively. Nodes sense events and transmit their data to the sink directly or through intermediate nodes acting as relay.Despite all the tremendous advances that have been made on this technology over the past few years, energy has not kept pace. This is based mostly on the fact that battery is its main source of energy. Furthermore, some applications of the network may preclude batteries from either being recharged or changed after deployment.A renowned solution to energy efficiency is duty cycling. This is the periodic or aperiodic placing of a node in an active and an inactive state. This introduces network performance issues of availability, latency, and packet delivery ratio, all linked to the fact that once a node is inactive or off, it is unavailable to communicate. It is therefore important to look for means of still applying duty cycling yet not losing out in availability, latency, and packet delivery ratio.In this dissertation we employ duty cycle on topology management to extend the network lifetime. We propose five algorithms to build various topologies that we divide into two classes. The first class enables nodes to arrange themselves into repetitive and interleaving sets. That is, nodes in the same set repeat themselves on the ground such that a set spans the entire area to be sensed. The second class of algorithms arranges nodes in continuous successive sets with members of a set covering a transmission range. We demonstrate the set formation experimentally.Building on the continuous set formation we propose two algorithms that build disjoint virtual backbone networks, with the disjointedness used for activity scheduling. We then measure the performances of the algorithms notably the approximation ratio and find it quite low (in the order of 3.5) compared to what is obtained in the literature.Finally, we propose a sleep and relay protocol that works on these topologies. Nodes sleep in sets and the activeness is relayed between sets. We evaluate the performance of this protocol and confirm that it actually leads to increase energy savings while not deteriorating other network performance metrics, like latency and packet delivery ratio., La mise en réseau de capteurs sans fil s'intègre dans presque tous les domaines des activités humaines. Les moteurs de cette technologie comprennent ses domaines d'application et les améliorations des techniques de fabrication microélectroniques. Le réseau est constitué de plusieurs nœuds de capteurs de petite taille déployés dans la zone à détecter. Les nœuds ont des capacités de traitement, de communication et de détection qui leur permettent d'exécuter leur fonction de manière collaborative. Ils détectent les événements et transmettent les informations à un puits directement ou via des nœuds intermédiaires servant de relais.Des progrès considérables ont été réalisés sur cette technologie au cours des dernières années, cependant la gestion de l’énergie n’a pas connu la même évolution. Ceci est principalement dû au fait que la batterie est la principale source d'énergie. De plus, l’environnement du réseau peut empêcher les batteries d'être rechargées ou changées après le déploiement.Une solution classique à ce problème d'efficacité énergétique réside dans la gestion des cycles d’activation. Il s'agit d’alterner, de façon périodique ou non, les états actif et inactif des nœuds. Cela introduit des problèmes de performances réseaux en termes de disponibilité, de latence et de taux d’acheminement des paquets, car les nœuds inactifs ne participent pas aux communications. Il est donc important de trouver des solutions permettant d’utiliser les cycles d’activation tout en garantissant la disponibilité et en réduisant la latence et le taux de perte de paquets.Dans cette thèse, nous utilisons le cycle d’activation en combinaison avec la gestion de la topologie pour prolonger la durée de vie du réseau. Nous proposons cinq algorithmes pour construire différentes topologies que nous divisons en deux classes. La première classe organise les nœuds en ensembles de manière répétitive et entrelacée. C'est-à-dire que les nœuds appartenant à différents ensembles sont intercalés de manière à assurer la continuité des communications. La seconde classe d'algorithmes organise les nœuds en ensembles successifs en couronne. Nous avons montré expérimentalement la construction des différents ensembles.En utilisant la construction successive d’ensembles, nous proposons deux algorithmes qui construisent des réseaux dorsaux (backbones) virtuels disjoints pouvant être activés alternativement. Une évaluation des algorithmes fait ressortir leur efficacité, avec notamment un facteur d’approximation faible (de l’ordre de 3.5) en comparaison avec ceux des travaux de la littérature.Nous proposons ensuite un protocole basé sur les mécanismes de sommeil et relais sur ces topologies. Les périodes d’activité/inactivité sont définies par ensemble. Les résultats expérimentaux montrent que ce protocole permet une économie d’énergie sans dégrader les critères de performance tels que la latence et le taux d’acheminement des paquets.

Today, Cloud Networking is one of the recent research areas within the Cloud Computing research communities. The main challenges of Cloud Networking concern Quality of Service (QoS) and security guarantee as well as its management in conformance with a corresponding Service Level Agreement (SLA). In this thesis, we propose a framework for resource allocation according to an end-to-end SLA established between a Cloud Service User (CSU) and several Cloud Service Providers (CSPs) within a Cloud Networking environment (Inter-Cloud Broker and Federation architectures). We focus on NaaS and IaaS Cloud services. Then, we propose the self-establishing of several kinds of SLAs and the self-management of the corresponding Cloud resources in conformance with these SLAs using specific autonomic cloud managers. In addition, we extend the proposed architectures and the corresponding SLAs in order to deliver a service level taking into account security guarantee. Moreover, we allow autonomic cloud managers to expand the self-management objectives to security functions (self-protection) while studying the impact of the proposed security on QoS guarantee. Finally, our proposed architecture is validated by different simulation scenarios. We consider, within these simulations, videoconferencing and intensive computing applications in order to provide them with QoS and security guarantee in a Cloud self-management environment. The obtained results show that our contributions enable good performances for these applications. In particular, we observe that the Broker architecture is the most economical while ensuring QoS and security requirements. In addition, we observe that Cloud self-management enables violations and penalties’ reduction as well as limiting security impact on QoS guarantee.; De nos jours, le Cloud Networking est considéré comme étant l'un des domaines de recherche innovants au sein de la communauté de recherche du Cloud Computing. Les principaux défis dans un environnement de Cloud Networking concernent non seulement la garantie de qualité de service (QoS) et de sécurité mais aussi sa gestion en conformité avec un accord de niveau de service (SLA) correspondant. Dans cette thèse, nous proposons un Framework pour l'allocation des ressources conformément à un SLA établi de bout en bout entre un utilisateur de services Cloud (CSU) et plusieurs fournisseurs de services Cloud (CSP) dans un environnement de Cloud Networking (architectures d’inter-Cloud Broker et Fédération). Nos travaux se concentrent sur les services Cloud de types NaaS et IaaS. Ainsi, nous proposons l'auto-établissement de plusieurs types de SLA ainsi que la gestion autonome des ressources de Cloud correspondantes en conformité avec ces SLA en utilisant des gestionnaires autonomes spécifiques de Cloud. De plus, nous étendons les architectures et les SLA proposés pour offrir un niveau de service intégrant une garantie de sécurité. Ainsi, nous permettons aux gestionnaires autonomes de Cloud d'élargir leurs objectifs de gestion autonome aux fonctions de sécurité (auto-protection) tout en étudiant l'impact de la sécurité proposée sur la garantie de QoS. Enfin, nous validons notre architecture avec différents scénarios de simulation. Nous considérons dans le cadre de ces simulations des applications de vidéoconférence et de calcul intensif afin de leur fournir une garantie de QoS et de sécurité dans un environnement de gestion autonome des ressources du Cloud. Les résultats obtenus montrent que nos contributions permettent de bonnes performances pour ce type d’applications. En particulier, nous observons que l'architecture de type Broker est la plus économique, tout en assurant les exigences de QoS et de sécurité. De plus, nous observons que la gestion autonome des ressources du Cloud permet la réduction des violations, des pénalités et limite l'impact de la sécurité sur la garantie de la QoS.

Since 1990, networking and mobile technologies have made a phenomenal unprecedented progress. This progress has been experienced on multiple fronts in parallel; especially on the application level and the user's needs one. This rapid evolution of the technology imposed a need for the existence of heterogeneous environments where the coverage is ensured throughout the different available networks. The challenge with such architecture would be to provide the user with the ability to navigate through the different available networks in a transparent and seamless fashion. However, the navigation among different types of networks is commonly referred to as vertical Handover. The IEEE 802.21 standard offers a component that is called Media Independent Handover (MIH) which has a function that provides the capability of transmitting the state of the connection of the mobile nodes from the lower to upper layers. This layer would exist between layer 2 and layer 3 within the protocol architecture. The main role of MIH is to help the mobile node transfer without interrupt among different types of networks, but the logic of selection is left without implementation. In this context, we worked on the improvement of the Handover management by proposing a new architecture, called VHMC and based on MIH by offering new methods for selecting the destination network. The first solution is a new algorithm called Multiple Criteria Selection Algorithm (MCSA) based on multiple parameters of the quality of service. We used Network Simulator (NS2) for testing our approach and study the number of lost packets and lost time during Handover. The second solution is a new model for selecting the destination network based on fuzzy logic techniques. The distinctive characteristic of this model lies in the study of genuine Handover records taken from a Lebanese mobile operator called "Alfa". A third proposed solution for network selection is based on multiple linear regression theory.; Depuis les années 90, la technologie réseau et radio mobile a fait l'objet de progrès phénoménaux. Cette avancée technologique s'est faite en parallèle du côté réseau, du côté application et du coté besoin de l’utilisateur. L’évolution rapide de la technologie a eu pour conséquence l’existence d’un environnement hétérogène où la couverture est assurée par la coexistence de plusieurs types de réseaux. Le défi soulevé par cette architecture est de pouvoir naviguer entre plusieurs réseaux d’une façon transparente. La navigation entre réseaux de types différents est connue sous le nom du Handover vertical. Le standard IEEE 802.21 offre une composante appelée Media Independent Handover (MIH) qui contient une fonction capable de transmettre l’état des liens du nœud mobile depuis les couches inférieures vers les couches supérieures. MIH s’intercale entre le niveau 2 et le niveau 3 dans la pile protocolaire. Le rôle principal de MIH est d’aider le nœud mobile à faire un transfert sans coupure entre des réseaux de types différents, mais la logique de sélection est laissée sans implémentation.Dans ce contexte nous avons travaillé sur l’amélioration de la gestion du Handover en proposant une nouvelle architecture appelée VHMC et basée sur MIH offrant des nouvelles méthodes de sélection du réseau destination. La première proposition est un nouvel algorithme nommé Multiple Criteria Selection Algorithm (MCSA) basé sur plusieurs paramètres de qualité du service. Nous avons utilisé le simulateur Network Simulator (NS2) pour évaluer nos propositions en étudiant le nombre de paquets perdus et le temps de latence du Handover durant la période du transfert. La deuxième contribution est un nouveau modèle de sélection du réseau destination basé sur la technique de la logique floue. La base d’inférence, qui est l’élément central de la décision de ce modèle, est déduit grâce à une étude basée sur un nombre élevé de cas de Handover réels collectés des serveurs de la compagnie de télécommunication libanaise "Alfa". Une troisième solution est proposée à travers un nouveau modèle de sélection du réseau destination basé sur la théorie de la régression linéaire multiple.

Our research are about graph coloring with distance constraints (packing coloring) or neighborhood constraints (Grundy coloring). Let S={si| i in N*} be a non decreasing sequence of integers. An S-packing coloring is a proper coloring such that every set of color i is an si-packing (a set of vertices at pairwise distance greater than si). A graph G is (s1,... ,sk)-colorable if there exists a packing coloring of G with colors 1,... ,k. A Grundy coloring is a proper vertex coloring such that for every vertex of color i, u is adjacent to a vertex of color j, for each ji. These results allow us to determine S-packing coloring of these lattices for several sequences of integers. We examine a class of graph that has never been studied for S-packing coloring: the subcubic graphs. We determine that every subcubic graph is (1,2,2,2,2,2,2)-colorable and (1,1,2,2,3)-colorable. Few results are proven about some subclasses. Finally, we study the Grundy number of regular graphs. We determine a characterization of the cubic graphs with Grundy number 4. Moreover, we prove that every r-regular graph without induced square has Grundy number r+1, for ri. Ces résultats nous permettent de déterminer des S-colorations de packings de ces grilles pour plusieurs séries d’entiers. Nous examinons une classe de graphe jamais étudiée en ce qui concerne la S -coloration de packing: les graphes subcubiques. Nous déterminons que tous les graphes subcubiques sont (1,2,2,2,2,2,2)-colorables et (1,1,2,2,3)-colorables. Un certain nombre de résultats sont prouvés pour certaines sous-classes des graphes subcubiques. Pour finir, nous nous intéressons au nombre de Grundy des graphes réguliers. Nous déterminons une caractérisation des graphes cubiques avec un nombre de Grundy de 4. De plus, nous prouvons que tous les graphes r-réguliers sans carré induit ont pour nombre de Grundy de r+1, pour r