Constructing Reliable Virtual Backbones in Probabilistic Wireless Sensor Networks

Most existing algorithms used for constructing virtual backbones are based on the ideal deterministic network model (DNM) in which any pair of nodes is either fully connected or completely disconnected. Different from DNM, the probabilistic network model (PNM), which presumes that there is a probability to connect and communicate between any pair of nodes, is more suitable to the practice in many real applications. In this paper, we propose a new algorithm to construct reliable virtual backbone in probabilistic wireless sensor networks. In the algorithm, we firstly introduce Effective Degree of Delivery Probability (EDDP) to indicate the reliable degree of nodes to transfer data successfully, and then exclude those nodes with zero EDDP from the candidate dominator set to construct a reliable connected dominating set (CDS). Moreover, each dominatee selects the neighbor dominator with the maximum delivery probability to transfer data. Through simulations, we demonstrate that our proposed algorithm can remarkably prolong the network lifetime compared with existing typical algorithms

A LOAD-BASED APPROACH TO FORMING A CONNECTED DOMINATING SET FOR AN AD HOC NETWORK

Efficient routing in mobile ad hoc networks (MANETs) is highly desired and connected dominating sets (CDS) have been gaining significant popularity in this regard. The CDS based approach reduces the search for a minimum cost path between a pair of source and destination terminals to the set of terminals forming the backbone network. Researchers over the years have developed numerous distributed and localized algorithms for constructing CDSs which minimize the number of terminals forming the backbone or which provide multiple node-disjoint paths between each pair of terminals. However none of this research focuses on minimizing the load at the bottleneck terminal of the backbone network constructed by the CDS algorithms. A terminal becomes a bottleneck if the offered traffic load is greater than its effective transmission rate. In this thesis we analyze the load-based performance of a popular CDS algorithm which has been employed in MANET routing and a k-connected k-dominating set (k-CDS) algorithm and compare it with our new centralized algorithm which has been designed to minimize the load at the bottleneck terminal of the backbone network. We verify the effectiveness of our algorithm by simulating over a large number of random test networks

Robustness and Reliability for Virtual Topologies in Wireless Multihop Access Networks

International audienceMobile ad hoc networks (MANet) are a spontaneous collection of mobile terminals. Each node must collaborate in order to structure information exchange. An hybrid network is a MANet connected to Internet via an Access Point (AP). We propose to organize MANet and hybrid networks through a virtual topology. We consider a virtual topology as a hierarchical organization based on the integration of both backbone and clusters. Construction and maintenance procedures of such a virtual topology are detailed and deal with robustness and reliability issues. We present a proactive gratuitous maintenance for our backbone and a new maintenance algorithm for clusters presenting a reduced overhead. Moreover, this improved solution allows to integrate multiple APs in hybrid networks , deleting the previous single point of failure. A method to interconnect backbones is described, which is useful for many applications

Visualized Algorithm Engineering on Two Graph Partitioning Problems

Concepts of graph theory are frequently used by computer scientists as abstractions when modeling a problem. Partitioning a graph (or a network) into smaller parts is one of the fundamental algorithmic operations that plays a key role in classifying and clustering. Since the early 1970s, graph partitioning rapidly expanded for applications in wide areas. It applies in both engineering applications, as well as research. Current technology generates massive data (“Big Data”) from business interactions and social exchanges, so high-performance algorithms of partitioning graphs are a critical need. This dissertation presents engineering models for two graph partitioning problems arising from completely different applications, computer networks and arithmetic. The design, analysis, implementation, optimization, and experimental evaluation of these models employ visualization in all aspects. Visualization indicates the performance of the implementation of each Algorithm Engineering work, and also helps to analyze and explore new algorithms to solve the problems. We term this research method as “Visualized Algorithm Engineering (VAE)” to emphasize the contribution of the visualizations in these works. The techniques discussed here apply to a broad area of problems: computer networks, social networks, arithmetic, computer graphics and software engineering. Common terminologies accepted across these disciplines have been used in this dissertation to guarantee practitioners from all fields can understand the concepts we introduce

A self-organization structure for Hybrid Networks

International audienceThis paper focuses on the self-organization of ad hoc and hybrid networks. We propose to organize networks with two integrated virtual structures: a backbone and clusters. The backbone helps to optimize the flooding of control packets, and to offer a natural prolongation of the backbone of wired networks. Clusters help to hierarchize the network, each of which is managed logically by its clusterhead. Since MANETs are mobile, we propose distributed algorithms for both the construction and the maintenance to preserve an efficient virtual structure despite topology changes. Simulations results exhibit the robustness and persistence of the proposed virtual structure

Enhancing infotainment applications quality of service in vehicular ad hoc networks

Les réseaux ad hoc de véhicules accueillent une multitude d’applications intéressantes. Parmi celles-ci, les applications d’info-divertissement visent à améliorer l’expérience des passagers. Ces applications ont des exigences rigides en termes de délai de livraison et de débit. De nombreuses approches ont été proposées pour assurer la qualité du service des dites applications. Elles sont réparties en deux couches : réseau et contrôle d’accès. Toutefois, ces méthodes présentent plusieurs lacunes. Cette thèse a trois volets. Le premier aborde la question du routage dans le milieu urbain. A cet égard, un nouveau protocole, appelé SCRP, a été proposé. Il exploite l’information sur la circulation des véhicules en temps réel pour créer des épines dorsales sur les routes et les connecter aux intersections à l’aide des nœuds de pont. Ces derniers collectent des informations concernant la connectivité et le délai, utilisées pour choisir les chemins de routage ayant un délai de bout-en-bout faible. Le deuxième s’attaque au problème d’affectation des canaux de services afin d’augmenter le débit. A cet effet, un nouveau mécanisme, appelé ASSCH, a été conçu. ASSCH collecte des informations sur les canaux en temps réel et les donne à un modèle stochastique afin de prédire leurs états dans l’avenir. Les canaux les moins encombrés sont sélectionnés pour être utilisés. Le dernier volet vise à proposer un modèle analytique pour examiner la performance du mécanisme EDCA de la norme IEEE 802.11p. Ce modèle tient en compte plusieurs facteurs, dont l’opportunité de transmission, non exploitée dans IEEE 802.11p.The fact that vehicular ad hoc network accommodates two types of communications, Vehicle-to-Vehicle and Vehicle-to-Infrastructure, has opened the door for a plethora of interesting applications to thrive. Some of these applications, known as infotainment applications, focus on enhancing the passengers' experience. They have rigid requirements in terms of delivery delay and throughput. Numerous approaches have been proposed, at medium access control and routing layers, to enhance the quality of service of such applications. However, existing schemes have several shortcomings. Subsequently, the design of new and efficient approaches is vital for the proper functioning of infotainment applications. This work proposes three schemes. The first is a novel routing protocol, labeled SCRP. It leverages real-time vehicular traffic information to create backbones over road segments and connect them at intersections using bridge nodes. These nodes are responsible for collecting connectivity and delay information, which are used to select routing paths with low end-to-end delay. The second is an altruistic service channel selection scheme, labeled ASSCH. It first collects real-time service channels information and feeds it to a stochastic model that predicts the state of these channels in the near future. The least congested channels are then selected to be used. The third is an analytical model for the performance of the IEEE 802.11p Enhanced Distributed Channel Access mechanism that considers various factors, including the transmission opportunity (TXOP), unexploited by IEEE 802.11p