Jumps: Enhancing hop-count positioning in sensor networks using multiple coordinates

Positioning systems in self-organizing networks generally rely on measurements such as delay and received signal strength, which may be difficult to obtain and often require dedicated equipment. An alternative to such approaches is to use simple connectivity information, that is, the presence or absence of a link between any pair of nodes, and to extend it to hop-counts, in order to obtain an approximate coordinate system. Such an approximation is sufficient for a large number of applications, such as routing. In this paper, we propose Jumps, a positioning system for those self-organizing networks in which other types of (exact) positioning systems cannot be used or are deemed to be too costly. Jumps builds a multiple coordinate system based solely on nodes neighborhood knowledge. Jumps is interesting in the context of wireless sensor networks, as it neither requires additional embedded equipment nor relies on any nodes capabilities. While other approaches use only three hop-count measurements to infer the position of a node, Jumps uses an arbitrary number. We observe that an increase in the number of measurements leads to an improvement in the localization process, without requiring a high dense environment. We show through simulations that Jumps, when compared with existing approaches, reduces the number of nodes sharing the same coordinates, which paves the way for functions such as position-based routing

Dis moi où tu es, je te dirai ce que tu vaux

International audiencePeut-on avoir une idée de la centralité d'un noeud uniquement à partir de sa localisation et indépendamment de son identité ? Nous étudions la centralité d'intermédiarité (betweenness-centrality) dans un contexte véhiculaire, en liant la valeur de la centralité à sa localisation via un découpage de l'espace. Nos résultats montrent que même si la valeur d'intermédiarité des noeuds est compliquée à estimer, notamment à cause de la mobilité des noeuds et de l'influence de son voisinage, grâce au découpage spatial il est en effet possible d'anticiper le rang futur d'un noeud grâce à sa localisa-tion. Nous montrons que cette solution permet de trouver les endroits spécifiques possédants un rang d'intermédiarité prévisible, et donc de prévoir le rang des noeuds s'y trouvant même quand ceux-ci ont tendance à transiter fréquemment dans l'espace

Positionnement topologique et dissémination passive dans les réseaux ad hoc

Le routage dans les réseaux sans fil auto-organisables est un défi et nécessite une restructuration. Durant cette thèse, nous nous sommes intéressés au positionnement et à la dissémination. Nous avons proposé JuMPS, un algorithme qui permet la construction d'un système de coordonnées virtuel multidimensionnel. JuMPS utilise les distances en nombre de sauts entre chaque nœud et un ensemble d'ancres afin de leur attribuer des coordonnées virtuelles. Dans la seconde partie de cette thèse, nous avons proposé, pour la dissémination des coordonnées dans un réseau ad hoc mobile d'utiliser la mobilité des paquets de données pour diffuser des informations utiles au routage. ELIP, notre solution, crée une nouvelle structure des paquets de données et y consacre un champ pour l'insertion de coordonnées. L'utilisation de ELIP au sein d'un protocole de routage basé sur les âges permet de réduire l'occupation du canal radio ainsi que le nombre de sauts moyen nécessaires à l'acheminement des messages.PARIS-BIUSJ-Mathématiques rech (751052111) / SudocSudocFranceF

Simulation of Mobile Ad hoc Network Protocols in ReactiveML

This paper presents a programming experiment of a complex network routing protocol for mobile ad hoc networks within the ReactiveML language. Mobile ad hoc networks are highly dynamic networks characterized by the absence of physical infrastructure. In such networks, nodes are able to move, evolve concurrently and synchronize continuously with their neighbors. Due to mobility, connections in the network can change dynamically and nodes can be added or removed at any time. All these characteristics — concurrency with many communications and the need of complex data-structure — combined to our routing protocol specifications make the use of standard simulation tools (e.g., NS, OPNET) inadequate and network protocols appear to be very hard to program efficiently in conventional programming languages. In this paper, we show that the synchronous reactive model, as introduced in the pioneering work of Boussinot, matters for programming such systems. This model provides adequate programming constructs — namely synchronous parallel composition, broadcast communication and dynamic creation — which allow for a natural implementation of the hard part of the simulation. The implementation has been done in ReactiveML, an embedding of the reactive model inside a statically typed, strict functional language. ReactiveML provides reactive programming constructions with most of the features of Ocaml. Moreover, it provides an efficient execution scheme for reactive constructs which made the simulation of real-size examples feasible. Experimental results show that the ReactiveML implementation is two orders of magnitude faster than the original C version; it was able to simulate more than 1000 nodes where the original C version failed (after 200 nodes) and is twice faster than the version programmed in NAB

doi:10.1155/2008/275658 Research Article Exploring Landmark Placement Strategies for Topology-Based Localization in Wireless Sensor Networks

In topology-based localization, each node in a network computes its hop-count distance to a finite number of reference nodes, or “landmarks”. This paper studies the impact of landmark placement on the accuracy of the resulting coordinate systems. The coordinates of each node are given by the hop-count distance to the landmarks. We show analytically that placing landmarks on the boundary of the topology yields more accurate coordinate systems than when landmarks are placed in the interior. Moreover, under some conditions, we show that uniform landmark deployment on the boundary is optimal. This work is also the first empirical study to consider not only uniform, synthetic topologies, but also nonuniform topologies resembling more concrete deployments. Our simulation results show that, in general, if enough landmarks are used, random landmark placement yields comparative performance to placing landmarks on the boundary randomly or equally spaced. This is an important result since boundary placement, especially at equal distances, may turn out to be infeasible and/or prohibitively expensive (in terms of communication, processing overhead, and power consumption) in networks of nodes with limited capabilities. Copyright © 2008 Farid Benbadis et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1

Exploring landmark placement strategies for self-organization in wireless sensor networks

International audienceIn this paper, we explore the impact of reference node, or "landmark", placement on the accuracy of the coordinate systems built using topology-based localization techniques. Such techniques employ landmarks to which each node computes its hop-count distance. A node's coordinates is given by the hop-count distance to all landmarks. To our knowledge, our paper is the first to study the impact of landmark placement on the accuracy of the resulting coordinate system. We show that placing landmarks on the periphery of the topology yields more accurate coordinate systems when compared to placing landmarks in the interior of the topology. Nevertheless, our simulation results also show that, in general, if enough landmarks are used, random landmark placement yields comparative performance to placing landmarks on the boundary randomly or equally spaced. This is an important result since boundary placement (especially at equal distances) may turn out to be infeasible and/or prohibitively expensive (in terms of power consumption as well as processing and communication overhead). This is also the first study to consider not only uniform, synthetic topologies, but also, non-uniform topologies resembling more concrete deployments

Computing Realistic and Adaptive Capacity of D2D Contacts

International audienceAssessing the performance of opportunistic networks requires a subtle understanding of both contact and intercontact patterns. While the analysis of intercontacts has attracted significant attention from the research community, surprisingly only a few works have focused on explaining what happens during a contact. In this paper, we perform an in-depth analysis of contacts using both empirical measurements and reference models. We make several observations that allow us to better capture the adaptive nature of device-to-device (D2D)links. In particular, in the case of Wi-Fi 5, we show that a slight modification of the nominal modulation scheme is enough to achieve an accurate characterization of opportunistic contacts for some categories of propagation models. As a consequence, we confirm previous observations that the evaluation of protocols and algorithms for D2D networks based on links of fixed rate may lead to inaccurate results. We finally propose a tool that extends mobility traces with plausible values of per-link capacity