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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A Smooth-turn Mobility Model for Airborne Networks

He, Dayin 08 1900 (has links)
In this article, I introduce a novel airborne network mobility model, called the Smooth Turn Mobility Model, that captures the correlation of acceleration for airborne vehicles across time and spatial coordinates. E?ective routing in airborne networks (ANs) relies on suitable mobility models that capture the random movement pattern of airborne vehicles. As airborne vehicles cannot make sharp turns as easily as ground vehicles do, the widely used mobility models for Mobile Ad Hoc Networks such as Random Waypoint and Random Direction models fail. Our model is realistic in capturing the tendency of airborne vehicles toward making straight trajectory and smooth turns with large radius, and whereas is simple enough for tractable connectivity analysis and routing design.
2

A Comprehensive Modeling Framework for Airborne Mobility

Xie, Junfei 12 1900 (has links)
Mobility models serve as the foundation for evaluating and designing airborne networks. Due to the significant impact of mobility models on the network performance, mobility models for airborne networks (ANs) must realistically capture the attributes of ANs. In this paper, I develop a comprehensive modeling framework for ANs. The work I have done is concluded as the following three parts. First, I perform a comprehensive and comparative analysis of AN mobility models and evaluate the models based on several metrics: 1) networking performance, 2) ability to capture the mobility attributes of ANs, 3) randomness levels and 4) associated applications. Second, I develop two 3D mobility models and realistic boundary models. The mobility models follow physical laws behind aircraft maneuvering and therefore capture the characteristics of aircraft trajectories. Third, I suggest an estimation procedure to extract parameters in one of the models that I developed from real flight test data. The good match between the estimated trajectories and real flight trajectories also validate the suitability of the model. The mobility models and the estimation procedure lead to the creation of “realistic” simulation and evaluation environment for airborne networks.
3

City Mobility Model with Google Earth Visualization

Andersson, Henrik, Oreland, Peter January 2007 (has links)
<p>Mobile Ad Hoc Networks are flexible, self configuring networks that do not need a fixed infrastructure. When these nets are simulated, mobility models can be used to specify node movements. The work in this thesis focuses on designing an extension of the random trip</p><p>mobility model on a city section from EPFL (Swiss federal institute of technology). Road data is extracted from the census TIGER database, displayed in Google Earth and used as input for the model. This model produces output that can be used in the open source network simulator ns-2.</p><p>We created utilities that take output from a database of US counties, the TIGER database, and convert it to KML. KML is an XML based format used by Google Earth to store geographical data, so that it can be viewed in Google Earth. This data will then be used as input to the modified mobility model and finally run through the ns-2 simulator. We present some NAM traces, a network animator that will show node movements over time.</p><p>We managed to complete most of the goals we set out, apart from being able to modify node positions in Google Earth. This was skipped because the model we modified had an initialization phase that made node positions random regardless of initial position. We were also asked to add the ability to set stationary nodes in Google Earth; this was not added due to time constraints.</p>
4

Mobilité et gestion efficace des fréquences dans un réseau ad hoc à forte efficacité / Mobility model and resource allocation in high efficiency opportunistic networks

Pomportes, Stephane 12 December 2011 (has links)
En cas de catastrophes importantes, telles qu’un tremblement de terre ou un incendie, l’efficacité des forces de la sécurité civile nécessite une bonne coordination des différents groupes d’intervention. Suivant la nature et l’importance du sinistre, l’infrastructure des moyens de communications classique peut être détruite. Les forces d’intervention ont donc besoin de nouveaux outils de communication dits réseaux de circonstance. Ces réseaux posent de nouveaux problèmes de routage, pour maintenir la connectivité, mais aussi d’allocation de ressources, particulièrement importante dans un contexte de sécurité où les communications doivent être garanties. Dans une première partie, nous avons abordé la problématique de l’allocation de ressources dans les réseaux de circonstance utilisant le partage TDMA. Nos solutions visent une répartition équitable des canaux et prennent en compte une zone d’interférence double de celle de transmission.Evaluer de nouvelles politiques dans des réseaux déployés sur des scènes de catastrophe nécessite de nouveaux modèles de mobilité. Nous avons donc également développé un nouveau modèle de mobilité spécifique au déplacement des équipes de la sécurité civile. / When a major disaster occurs, such as an earthquake or fire, the efficiency of the rescue workers depends of the coordination between the different emergency teams. This coordination needs reliable communication equipments. In such a situation, however, the infrastructure for wireless communication is generally destroyed or unusable. It is therefore necessary to find adapted communication tools for the rescue workers known as opportunistic networks. These networks pose new challenging problems such as, for instance, resource allocation which is particularly important for the QoS satisfaction. In the first part of our thesis, we addressed the problem of resource allocation in ad hoc networks using the TDMA access mechanism. Our solutions aim to perform a fair distribution of channels and take into account an interference area twice as large as the transmission range. Evaluation of new policies for opportunistic networks deployed in disaster areas requires new mobility models. We developed a novel mobility model dedicated to the movement of rescue workers. Our model includes the group mobility and some characteristics of human mobility. It also incorporates a mechanism to circumvent obstacles presents in the simulation area.
5

A Study of Mobility Models in Mobile Surveillance Systems

Miao, Yun-Qian January 2010 (has links)
This thesis explores the role mobile sensor's mobility model and how it affects surveillance system performance in term of area coverage and detection effectiveness. Several algorithms which are categorized into three types, namely, fully coordinated mobility, fully random mobility and emergent mobility models are discussed with their advantages and limitations. A multi-agent platform to organize mobile sensor nodes, control nodes and actor nodes was implemented. It demonstrated great flexibility and was favourable for its distributed, autonomous and cooperative problem-solving characters. Realistic scenarios which are based on three KheperaIII mobile robots and a model which mimics Waterloo regional airport were used to examine the implementation platform and evaluate performance of different mobility algorithms. Several practical issues related to software configurations and interface library were addressed as by-products. The experimental results from both simulation and real platform show that the area coverage and the detection effectiveness vary with applying different mobility models. Fully coordinated model's super efficiency comes with carefully task planning and high requirements of sensor navigational accuracy. Fully random model is the least efficient in area coverage and detection because of the repetitive searching of each sensor and among sensors. A self-organizing algorithm named anti-flocking which mimics solitary animal's social behaviour was first proposed. It works based on quite simple rules for achieving purposeful coordinated group action without explicit global control. Experimental results demonstrate its attractive target detection efficiency in term of both detection rate and detection time while providing desirable features such as scalability, robustness and adaptivity. From the simulation results, the detection rate of the anti-flocking model increases by 36.5% and average detection time decreases by 46.2% comparing with the fully random motion model. The real platform results also reflect the superior performance improvement.
6

A Study of Mobility Models in Mobile Surveillance Systems

Miao, Yun-Qian January 2010 (has links)
This thesis explores the role mobile sensor's mobility model and how it affects surveillance system performance in term of area coverage and detection effectiveness. Several algorithms which are categorized into three types, namely, fully coordinated mobility, fully random mobility and emergent mobility models are discussed with their advantages and limitations. A multi-agent platform to organize mobile sensor nodes, control nodes and actor nodes was implemented. It demonstrated great flexibility and was favourable for its distributed, autonomous and cooperative problem-solving characters. Realistic scenarios which are based on three KheperaIII mobile robots and a model which mimics Waterloo regional airport were used to examine the implementation platform and evaluate performance of different mobility algorithms. Several practical issues related to software configurations and interface library were addressed as by-products. The experimental results from both simulation and real platform show that the area coverage and the detection effectiveness vary with applying different mobility models. Fully coordinated model's super efficiency comes with carefully task planning and high requirements of sensor navigational accuracy. Fully random model is the least efficient in area coverage and detection because of the repetitive searching of each sensor and among sensors. A self-organizing algorithm named anti-flocking which mimics solitary animal's social behaviour was first proposed. It works based on quite simple rules for achieving purposeful coordinated group action without explicit global control. Experimental results demonstrate its attractive target detection efficiency in term of both detection rate and detection time while providing desirable features such as scalability, robustness and adaptivity. From the simulation results, the detection rate of the anti-flocking model increases by 36.5% and average detection time decreases by 46.2% comparing with the fully random motion model. The real platform results also reflect the superior performance improvement.
7

2d Correlated Diffusion Process For Mobility Modeling In Mobile Networks

Cakar, Tunc 01 December 2004 (has links) (PDF)
This thesis introduces a novel mobility model based on so called &ldquo / 2D correlated diffusion process&rdquo / . In this model, motion components over x and y axes are dependent. Joint density function of the process is derived. The expected exit time from an arbitrary domain is characterized by a boundary value problem. Analytical solution of this problem is given for a specific case. Numerical solution of the problem is presented by several examples. The results obtained in these examples are verified by simulations. The expected exit time computed by this method holds for any given 2D domain and any given starting position inside.
8

City Mobility Model with Google Earth Visualization

Andersson, Henrik, Oreland, Peter January 2007 (has links)
Mobile Ad Hoc Networks are flexible, self configuring networks that do not need a fixed infrastructure. When these nets are simulated, mobility models can be used to specify node movements. The work in this thesis focuses on designing an extension of the random trip mobility model on a city section from EPFL (Swiss federal institute of technology). Road data is extracted from the census TIGER database, displayed in Google Earth and used as input for the model. This model produces output that can be used in the open source network simulator ns-2. We created utilities that take output from a database of US counties, the TIGER database, and convert it to KML. KML is an XML based format used by Google Earth to store geographical data, so that it can be viewed in Google Earth. This data will then be used as input to the modified mobility model and finally run through the ns-2 simulator. We present some NAM traces, a network animator that will show node movements over time. We managed to complete most of the goals we set out, apart from being able to modify node positions in Google Earth. This was skipped because the model we modified had an initialization phase that made node positions random regardless of initial position. We were also asked to add the ability to set stationary nodes in Google Earth; this was not added due to time constraints.
9

Modélisation dynamique de la densité de population via les réseaux cellulaires et optimisation multiobjectif de l'auto-partage / Dynamic modeling of population density via cellular networks and car-sharing multiobjective optimization

Moalic, Laurent 12 December 2013 (has links)
De nombreux problèmes de décision issus du monde réel sont de nature NP-difficile. Il est également fréquent que de tels problèmes rassemblent plusieurs objectifs à optimiser simultanément, généralement contradictoires entre eux. Pour aborder cette classe de problèmes, les métaheuristiques multiobjectifs fournissent des outils particulièrement efficaces. Par ailleurs, pour traiter des problèmes de transport, l'élaboration de modèles permettant de caractériser l’évolution spatio-temporelle d’une population est un élément essentiel. Dans le cadre de ces travaux, nous nous intéressons à la chaine complète qui permet de guider une décision dans le domaine de l'aménagement du territoire et du transport. Nous considérons ainsi les deux principales phases impliquées dans le processus de décision : la modélisation des déplacements de la population d'une part, et l'élaboration d'une métaheuristique hybride pour résoudre des problèmes d'optimisation multiobjectif d'autre part. Afin de modéliser l’évolution de la présence de personnes sur un territoire, nous proposons dans cette thèse un nouveau modèle de mobilité. L'originalité de ce travail réside dans l'utilisation de données nouvelles issues de la téléphonie mobile, ainsi que dans l'exploitation d'informations géographiques et socio-économiques pour caractériser le pouvoir d'attraction du territoire. Nous proposons par ailleurs une heuristique pour résoudre des problèmes multiobjectifs. L’étude de l'influence de différents opérateurs sur la construction de l'ensemble Pareto, nous a amené à concevoir une heuristique hybride de type mémétique, qui se révèle être significativement plus efficace que des approches de référence. Les deux principales phases, modélisation et optimisation, ont été expérimentées et validées dans un contexte réel. Elles ont donné lieu au développement d’une plate-forme logicielle d’aide à la décision utilisée notamment pour proposer des emplacements de stations pour un service d'auto-partage électrique. / Many decision-making problems in the real world are NP-hard. These problems commonly feature several mutually-contradictory objectives to be optimized simultaneously. Multiobjective metaheuristics provide particularly effective means of addressing this class of problems. Moreover, for transportation problems, the development of models able to evaluate the spatiotemporal evolution of a population is essential. In our research, we are interested in the complete chain guiding a decision in the fields of transportation and territory planning. We consider the two main phases involved in the decision-making process: building a population mobility model and developing a hybrid metaheuristic to solve multiobjective optimization problems. In order to compute the evolution of population presence on a territory, in this thesis we propose a new mobility model; its originality lies in employing new data from mobile phone networks as well as geographic and socio-economic information to indicate the attractiveness of the territory. We have also developed a heuristic to solve multiobjective problems: following the study of the influence of several operators on the Pareto front, we have designed a hybrid memetic heuristic that is significantly more effective than reference approaches. The two main phases of modelling and optimizing have been tested and validated in a real context, allowing us to develop a decision-making software platform that can be used to provide station locations for an electric car-sharing service.
10

Vers une intégration des comportements communautaires dans les réseaux mobiles / Towards social behaviors integration in mobile networks

Harfouche, Leïla 27 September 2011 (has links)
À l'aire du Multimedia Mobile, l'essor des réseaux sans fil est fulgurant et la mobilité est devenue un sujet primordial exacerbé par l'augmentation significative du nombre d'usagers mobiles. Un nœud évoluant dans un réseau mobile de base se comporte de la même manière qu'un aveugle évoluant dans notre univers en en élaborant sa propre représentation à l'aide de son bâton, mécanisme dénommé dans la littérature : mobilité terminale. Pour réduire cet aveuglement, plusieurs méthodes ont été élaborées qui prennent appui sur les services de localisation ou les modèles de mobilité. Un modèle de mobilité est donc destiné à décrire en termes d'environnement, le mode de circulation des nœuds mobiles avec pour défi de trouver des modèles fidèles aux comportements des utilisateurs. Les modèles aléatoires sont biaisés car les appareils mobiles sont portés par des êtres sociaux. Cela nous a amené à inclure des éléments sociaux dans notre modélisation.Nous présentons les modèles de mobilité existants et les classifions. Nous définissons nos modèles, les implémentons et mesurons leur impact sur le test des réseaux. Enfin nous élargissons notre spectre en montrant comment le fait d'octroyer la perception de regroupement social à un protocole de routage réseau, peut en améliorer les performances. / In our area of Mobile Multimedia, the expansion of wireless networks is dazzling and mobility has become a major issue exacerbated by the significant increase in the number of mobile users.A node operating in a basic mobile network behaves the same way a blind person moving in our universe by developing its own representation with his stick, a mechanism known in the literature as terminal mobility. To reduce this blindness, several methods have been developed that are based on location services and mobility models.A mobility model is then intended to describe in terms of environment, the motion criteria of mobile nodes with the challenge to find models faithful to user behavior.Random models are biased because mobile devices are supported by social beings. This led us to include social elements in our models.We present the existing mobility models and classify them.We define our models, implement them and measure their impact on the network testing.Finally we expand our spectrum by showing that granting social grouping perception to a network routing protocol, can improve its performance.

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