Bibliografias temáticas / Communications opportunistes

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Literatura científica selecionada sobre o tema "Communications opportunistes"

Autor: Grafiati
Publicado: 21 de dezembro de 2024

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Artigos de revistas sobre o assunto "Communications opportunistes"

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Martín-Pascual, Miguel Ángel, e Celia Andreu-Sánchez. "Practical Application of Mesh Opportunistic Networks". Applied System Innovation 6, n.º 3 (16 de junho de 2023): 60. http://dx.doi.org/10.3390/asi6030060.

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Opportunistic networks allow for communication between nearby mobile devices through a radio connection, avoiding the need for cellular data coverage or a Wi-Fi connection. The limited spatial range of this type of communication can be overcome by using nodes in a mesh network. The purpose of this research was to examine a commercial application of electronic mesh communication without a mobile data plan, Wi-Fi, or satellite. A mixed study, with qualitative and quantitative strategies, was designed. An experimental session, in which participants tested opportunistic networks developing different tasks for performance, was carried out to examine the system. Different complementary approaches were adopted: a survey, a focus group, and an analysis of participants’ performance. We found that the main advantage of this type of communication is the lack of a need to use data networks for one-to-one and group communications. Opportunistic networks can be integrated into professional communication workflows. They can be used in situations where traditional telephones and the Internet are compromised, such as at mass events, emergency situations, or in the presence of frequency inhibitors.
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Carreras, Iacopo, Andrea Zanardi, Elio Salvadori e Daniele Miorandi. "A Distributed Monitoring Framework for Opportunistic Communication Systems An Experimental Approach". International Journal of Adaptive, Resilient and Autonomic Systems 2, n.º 3 (julho de 2011): 45–62. http://dx.doi.org/10.4018/jaras.2011070104.

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Opportunistic communication systems aim at producing and sharing digital resources by means of localized wireless data exchanges among mobile nodes. The design and evaluation of systems able to exploit this emerging communication paradigm is a challenging problem. This paper presents the authors’ experience in developing U-Hopper, a middleware running over widely diffused mobile handsets and supporting the development of context-aware services based on opportunistic communications. The authors present the design of the platform, and describe the distributed monitoring framework that was set up in order to monitor and dynamically reconfigure it at run time. The paper concludes with an experimental evaluation of the framework, showing its practical utilization when monitoring an operational opportunistic communication system.
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Pajevic, Ljubica, e Gunnar Karlsson. "Modeling opportunistic communication with churn". Computer Communications 96 (dezembro de 2016): 123–35. http://dx.doi.org/10.1016/j.comcom.2016.04.018.

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Helgason, Olafur, Sylvia T. Kouyoumdjieva e Gunnar Karlsson. "Opportunistic Communication and Human Mobility". IEEE Transactions on Mobile Computing 13, n.º 7 (julho de 2014): 1597–610. http://dx.doi.org/10.1109/tmc.2013.160.

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Amin, Osama, e Lutz Lampe. "Opportunistic Energy Efficient Cooperative Communication". IEEE Wireless Communications Letters 1, n.º 5 (outubro de 2012): 412–15. http://dx.doi.org/10.1109/wcl.2012.061212.120206.

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Gorbil, Gokce, e Erol Gelenbe. "Opportunistic Communications for Emergency Support Systems". Procedia Computer Science 5 (2011): 39–47. http://dx.doi.org/10.1016/j.procs.2011.07.008.

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Nagananda, K. G. "Secure communications over opportunistic-relay channels". Physical Communication 7 (junho de 2013): 105–21. http://dx.doi.org/10.1016/j.phycom.2012.11.002.

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Davoli, Luca, Emanuele Pagliari e Gianluigi Ferrari. "Hybrid LoRa-IEEE 802.11s Opportunistic Mesh Networking for Flexible UAV Swarming". Drones 5, n.º 2 (15 de abril de 2021): 26. http://dx.doi.org/10.3390/drones5020026.

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Unmanned Aerial Vehicles (UAVs) and small drones are nowadays being widely used in heterogeneous use cases: aerial photography, precise agriculture, inspections, environmental data collection, search-and-rescue operations, surveillance applications, and more. When designing UAV swarm-based applications, a key “ingredient” to make them effective is the communication system (possible involving multiple protocols) shared by flying drones and terrestrial base stations. When compared to ground communication systems for swarms of terrestrial vehicles, one of the main advantages of UAV-based communications is the presence of direct Line-of-Sight (LOS) links between flying UAVs operating at an altitude of tens of meters, often ensuring direct visibility among themselves and even with some ground Base Transceiver Stations (BTSs). Therefore, the adoption of proper networking strategies for UAV swarms allows users to exchange data at distances (significantly) longer than in ground applications. In this paper, we propose a hybrid communication architecture for UAV swarms, leveraging heterogeneous radio mesh networking based on long-range communication protocols—such as LoRa and LoRaWAN—and IEEE 802.11s protocols. We then discuss its strengths, constraints, viable implementation, and relevant reference use cases.
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Ciobanu, Radu Ioan, e Ciprian Dobre. "Opportunistic Networks". International Journal of Virtual Communities and Social Networking 5, n.º 2 (abril de 2013): 11–26. http://dx.doi.org/10.4018/jvcsn.2013040102.

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When mobile devices are unable to establish direct communication, or when communication should be offloaded to cope with large throughputs, mobile collaboration can be used to facilitate communication through opportunistic networks. These types of networks, formed when mobile devices communicate only using short-range transmission protocols, usually when users are close, can help applications still exchange data. Routes are built dynamically, since each mobile device is acting according to the store-carry-and-forward paradigm. Thus, contacts are seen as opportunities to move data towards the destination. In such networks data dissemination is usually based on a publish/subscribe model. Opportunistic data dissemination also raises questions concerning user privacy and incentives. In this the authors present a motivation of using opportunistic networks in various real life use cases, and then analyze existing relevant work in the area of data dissemination. The authors present the categories of a proposed taxonomy that captures the capabilities of data dissemination techniques used in opportunistic networks. Moreover, the authors survey relevant techniques and analyze them using the proposed taxonomy.
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Johnston, Matthew, Isaac Keslassy e Eytan Modiano. "Channel Probing in Opportunistic Communication Systems". IEEE Transactions on Information Theory 63, n.º 11 (novembro de 2017): 7535–52. http://dx.doi.org/10.1109/tit.2017.2717580.

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Teses / dissertações sobre o assunto "Communications opportunistes"

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Shikfa, Abdullatif. "Sécurité des communications opportunistes". Paris, Télécom ParisTech, 2010. http://www.theses.fr/2010ENST0045.

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Dans cette thèse, nous étudions la sécurité des communications opportunistes. Dans ce nouveau type de communication, la mobilité des nœuds implique que les solutions de sécurité doivent être dynamiques et locales. Par ailleurs l’absence de connectivité bout-en-bout compromet toute solution de sécurité interactive. En outre, contrairement au routage traditionnel basé sur des adresses, les nouvelles stratégies de transmission opportunistes utilisent des informations comme le contexte d'un nœud ou le contenu d'un message pour prendre les décisions de transfert. Contexte et contenu sont des informations sensibles que les utilisateurs pourraient ne pas vouloir révéler aux autres afin de préserver leur vie privée, par conséquent, ces informations doivent être manipulées avec soin pour assurer leur confidentialité. Le conflit entre les exigences de sécurité et de routage justifie la recherche de nouveaux mécanismes de sécurité qui permettent certaines opérations sur des données chiffrées. Après avoir analysé les problèmes de sécurité dans les communications opportunistes, nous proposons une solution de sécurité complète pour la communication basée sur le contexte. Cette solution garantit non seulement la confidentialité des données et le respect de la vie privée des utilisateurs, mais aussi la correction des opérations, ce qui procure une résistance face aux attaques visant à perturber ou à endiguer la communication. Nous proposons aussi un protocole de routage basé sur le contenu qui préserve la vie privée des utilisateurs via un système de chiffrement multicouches, et une solution associée de gestion de clés, qui est locale et dépendante de la topologie
In this thesis, we investigate security in opportunistic communications. This new communication paradigm involves storing and carrying messages in addition to forwarding and impacts all security aspects of communication. Indeed, nodes’ high mobility implies that security solutions should be dynamic and local. Furthermore, delay tolerance, which is one of the main characteristics of opportunistic networks, has a strong impact from a security perspective as it amounts to the infeasibility of interactive protocols. Moreover, radically new forwarding strategies have been proposed to enable communication in opportunistic networks: parting from traditional network addresses, these enriched forwarding strategies use information such as context of a node or content of a message to take forwarding decisions. Context or content are sensitive information that users might not want to reveal to others in order to preserve their privacy, hence these information should be carefully handled to ensure their secrecy. The conflicting requirements between security and forwarding motivate the need for new security mechanisms that enable computation on encrypted data. After analyzing the security challenges in opportunistic communications, we propose a complete security framework for context-based communication. This framework features not only data confidentiality and user privacy, but also computation assurance, which provides resilience against malicious entities aiming at disrupting or subverting the communication. We also propose a privacy-preserving content-based protocol which relies on multiple encryption layers, and an associated local and topology-dependent key management solution
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Koteich, Jana. "Routage opportuniste tenant compte du contexte dans les réseaux sans fil". Electronic Thesis or Diss., Université de Lille (2022-....), 2024. http://www.theses.fr/2024ULILB018.

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Aujourd'hui, le partage des données et du contenu numérique est essentiel dans diverses applications, notamment dans les domaines de la santé, de l'éducation et de l'agriculture. Les réseaux câblés traditionnels et les réseaux sans fil sont les deux principaux modes de communication, ces derniers présentant davantage de difficultés en raison de l'absence de chemin physique guidé. Le routage opportuniste apparaît comme une solution prometteuse dans les régions dépourvues d'infrastructures de communication, en particulier dans les pays les moins avancés.Dans cette thèse, nous proposons une solution alternative aux approches basées sur l'infrastructure pour fournir des données indépendamment de toute infrastructure existante. Cette solution repose sur des dispositifs de communication et de stockage peu coûteux qui peuvent intégrer différentes technologies de communication, ce qui permet de créer un système global de partage de données préservant la vie privée et basé sur la mobilité naturelle des foules. Pour ce faire, nous analysons les schémas de mobilité de la foule afin d'attribuer une probabilité de livraison à un message en fonction de son schéma de mobilité. Tout d'abord, nous avons généré l'ensemble de données PILOT, une collection de données préservant la confidentialité des technologies de communication sans fil. L'ensemble de données se compose de quatre types d'informations collectées conjointement dans différents contextes de mobilité. Il comprend trois technologies de communication sans fil : les réponses des sondes WiFi, les balises BLE (Bluetooth Low Energy) et les paquets LoRa (Long Range Radio), ainsi que des informations supplémentaires sur l'accélération, le roulis et le tangage, toutes collectées simultanément. L'ensemble des données a été collecté pendant environ 90 heures, avec une taille de 200 Mo, en utilisant les dispositifs FiPy de Pycom. Nous avons fourni les clés permettant de reproduire cette collecte de données et partagé les ensembles de données déjà collectés sur GitHub. Après avoir généré l'ensemble de données, nous avons traité les traces collectées de WiFi et de BLE pour générer un modèle de classification capable d'estimer la situation réelle d'un appareil. Le premier modèle créé, appelé modèle B, vise à identifier si un appareil est stationnaire ou mobile. Par la suite, un modèle complémentaire, le modèle M, a été créé pour déterminer une situation plus précise de l'appareil dans la vie réelle, comme à la maison, au bureau, dans un bus, un train, etc. Enfin, nous avons exploité l'ensemble des données collectées et les modèles d'apprentissage automatique entraînés pour concevoir un protocole de routage en établissant des probabilités de livraison conditionnées par le contexte déterminé de l'appareil. Nous testons et validons notre approche en utilisant le simulateur ONE, qui est conçu pour un environnement de réseau opportuniste
Today, sharing data and digital content is essential across various applications, particularly in health, education, and agriculture. Traditional wired networks and wireless networks are the two main modes of communication, with the latter presenting more challenges due to the absence of a guided physical path.Opportunistic routing emerges as a promising solution in regions lacking communication infrastructure, especially in Least Developed Countries.In this thesis, we propose an alternative solution to infrastructure-based approaches for delivering data independently of any existing operated infrastructure. This solution relies on low-cost communication and storage devices that can embed different communication technologies, resulting in a global privacy-preserving data-sharing system based on natural crowd mobility. To achieve this, we analyze crowd mobility patterns to assign a delivery probability for a message based on its mobility pattern. First, we generated the PILOT dataset, a privacy-preserving data collection of wireless communication Technologies. The dataset consists of four types of jointly collected information in different mobility contexts. It includes three wireless communication technologies: WiFi probe responses, BLE (Bluetooth Low Energy) beacons, and LoRa (Long Range Radio) packets, as well as additional information on acceleration, roll, and pitch, all collected simultaneously. The dataset was collected over approximately 90 hours, with a size of 200 MB, using FiPy devices from Pycom. We provided the keys to reproduce such data collection and shared the datasets already collected on GitHub. After generating the dataset, we processed the collected traces of WiFi and BLE to generate a classification model that can estimate the real-life situation of a device. The first created model, called the B-model, aims to identify whether a device is stationary or mobile. Subsequently, a complementary model, the M-model, was created to determine a more precise real-life situation of the device, such as being at home, in the office, on a bus, train, etc. Finally, we exploited the collected dataset and the trained machine learning models todesign a routing protocol by setting delivery probabilities conditioned by the determined context of the device. We are testing and validating our approach using the ONE simulator, which is designed for an opportunistic network environment
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Benchi, Abdulkader. "Middleware Systems for Opportunistic Computing in Challenged Wireless Networks". Thesis, Lorient, 2015. http://www.theses.fr/2015LORIS372/document.

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Les réseaux mobiles opportunistes (ou OppNets, pour Opportunistic Networks) constituent une solution séduisante pour compléter les réseaux fixes d’infrastructure, voire compenser leur absence dans des zones sinistrées ou défavorisées. Les recherches menées ces dernières années ont principalement visé à permettre les transmissions dans les OppNets, mais ceci ne peut être qu’un premier pas vers une réelle exploitation de tels environnements contraints. L’informatique opportuniste (Opportunistic Computing) dépasse le cadre des seules transmissions, et introduit un nouveau paradigme d’exécution de tâches collaboratives dans de tels environnements. Dans ce domaine qu’est l’informatique opportuniste, la conception, la mise en œuvre et le déploiement d’applications distribuées sont des objectifs majeurs. Une application pour OppNet doit pouvoir fonctionner et assurer un niveau de service satisfaisant, tout en supportant les diverses contraintes propres aux OppNets, telles qu’une connectivité fluctuante, un partitionnement chronique du réseau, de longs délais de transmissions, de fréquents échecs de transmission, et des équipements hétérogènes offrant des ressources limitées. La complexité et le coût du développement d’applications pour OppNets peuvent être réduits de manière significative en utilisant des modèles de programmation appropriés. De tels modèles peuvent être fournis par des systèmes intergiciels capables de supporter de manière transparente les contraintes évoquées plus haut. Le travail rapporté dans ce mémoire a porté sur l’étude des contraintes inhérentes aux OppNets, et sur la proposition de solutions appropriées. Parmi les modèles de programmation usuels, certains ont été identifiés comme pouvant être utilisés dans le cadre des OppNets. Sur la base de ces divers modèles de programmation, des systèmes intergiciels opportunistes ont été mis en oeuvre. Ces systèmes supportent respectivement le modèle de messagerie distribuée (sur la base de files d’attentes et de "topics"), le modèle du tuple-space, et la résolution de consensus. Des implémentations complètes ont été réalisées, et le code source est distribué sous licence GPL (GNU General Public License). Ces systèmes ont été évalués par le biais d’expérimentations menées en conditions réelles et par simulation
Opportunistic networks (OppNets) constitute an appealing solution to complement fixed network infrastructures –or make up for the lack thereof– in challenged areas. Researches in the last few years have mostly addressed the problem of supporting networking in OppNets, yet this can only be a first step towards getting real benefit from these networks. Opportunistic computing goes beyond the concept of opportunistic networking, and provides a new paradigm to enable collaborative computing tasks in such environments. In the realm of opportunistic computing, properly designing, implementing and deploying distributed applications are important tasks. An OppNet-dedicated application must be able to operate and maintain an acceptable level of service while addressing the many problems that can occur in these networks, such as disconnections, partitioning, long transmission delays, transmission failures, resource constraints, frequent changes in topology, and heterogeneous devices. Much of the complexity and cost of building OppNet-dedicated applications can be alleviated by the use of high-level programming models. Such models can be supported by middleware systems capable of transparently addressing all the above-mentioned problems. The work reported in this dissertation focused on providing insight into the fundamental problems posed by OppNets, so as to analyze and solve the problems faced by application developers while dealing with these environments. The research focused on identifying well-known high-level programming models that can be satisfactorily implemented for OppNets, and that can prove useful for application developers. In order to demonstrate the feasibility of application development for OppNets, while assessing the benefits brought about by carefully designed middleware systems, a couple of such systems have been designed, implemented, and evaluated as part of this work. These middleware systems respectively support distributed messaging (through message queues and topics), the tuple-space model, and consensus solving in OppNets. They are supplemented with fully-functional implementations, that can be used in real settings, and that are all distributed under the terms of the GNU General Public License (GPL). Real-life experiments and simulations have been realized so as to evaluate the effectiveness and efficiency of these systems in real conditions
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Belouanas, Salah-Eddine. "Dissémination de contenus populaires et tolérants au délai dans les réseaux cellulaires". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066230/document.

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Les ressources cellulaires sont précieuses et doivent être préservées dès que possible. Dans cette thèse, nous abordons le problème de la dissémination de contenus dans un réseau cellulaire surchargé. La première partie présente SCoD (Scheduled Content Delivery), une stratégie de dissémination purement cellulaire qui exploite la mobilité des utilisateurs ainsi que leur tolérance aux délais afin d’effectuer des transmissions différées. SCoD attend que les utilisateurs se rassemblent autour d’un minimum de points d’accès afin que le nombre total de transmissions soit réduit. Pour déclencher des transmissions, SCoD repose sur différentes fonctions de décision qui déclenchent aux instants opportuns une transmission en multicast. La deuxième partie de cette thèse traite également le problème d’économie de ressources cellulaires, mais en l’attaquant sous un autre angle. Nous exploitons des communications D2D que nous associons au multicast pour réduire la charge sur l’infrastructure. Nous analysons les avantages des communications opportunistes dans le contexte d’un service de diffusion de contenus basé sur les abonnements des utilisateurs. Nous présentons nos résultats pour deux cas de figure. Tout d’abord, nous illustrons le bénéfice des communications D2D dans le cadre d’un processus de diffusion, où le coût d’une transmission opportuniste est négligeable par rapport à celui d’une transmission cellulaire. Nous considérons ensuite le cas où les utilisateurs doivent être indemnisés pour leur participation au processus de diffusion, et où il y a donc un compromis à trouver. Nous fournissons des lignes directrices dans ce sens et nous montrons la variation d’un tel compromis en fonction de plusieurs paramètres du réseau
Cellular resources are valuable and must be saved whenever possible. In this thesis, we address the problem of content dissemination within an overloaded cellular network. Firstly, we propose SCoD (Scheduled Content Delivery), a purely cellular dissemination strategy that exploits the mobility of users and their delay tolerance in order to postpone transmissions. SCoD waits for users to gather around a minimum number of access points so that the total number of transmissions is reduced. To trigger transmissions, SCoD relies on different decision functions which launch, if necessary, a multicast transmission. The second part of this thesis deals with the same problem of saving cellular resources, but from another angle. We use D2D (Device-to-Device) communications with multicast to mitigate the traffic load on the infrastructure. We study the benefits of opportunistic communications in the context of a content distribution service based on user subscriptions. We present our results in two ways. First, we illustrate the benefits of D2D communications in a content dissemination process where the cost of opportunistic transmission is negligible compared to that of cellular transmission. Then, we consider the case where users must be compensated for their participation in the dissemination process. Therefore, there is a tradeoff to be found, we thus provide guidelines in this direction and show the variation of such a tradeoff as a function of several network parameters
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Belouanas, Salah-Eddine. "Dissémination de contenus populaires et tolérants au délai dans les réseaux cellulaires". Electronic Thesis or Diss., Paris 6, 2017. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2017PA066230.pdf.

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Les ressources cellulaires sont précieuses et doivent être préservées dès que possible. Dans cette thèse, nous abordons le problème de la dissémination de contenus dans un réseau cellulaire surchargé. La première partie présente SCoD (Scheduled Content Delivery), une stratégie de dissémination purement cellulaire qui exploite la mobilité des utilisateurs ainsi que leur tolérance aux délais afin d’effectuer des transmissions différées. SCoD attend que les utilisateurs se rassemblent autour d’un minimum de points d’accès afin que le nombre total de transmissions soit réduit. Pour déclencher des transmissions, SCoD repose sur différentes fonctions de décision qui déclenchent aux instants opportuns une transmission en multicast. La deuxième partie de cette thèse traite également le problème d’économie de ressources cellulaires, mais en l’attaquant sous un autre angle. Nous exploitons des communications D2D que nous associons au multicast pour réduire la charge sur l’infrastructure. Nous analysons les avantages des communications opportunistes dans le contexte d’un service de diffusion de contenus basé sur les abonnements des utilisateurs. Nous présentons nos résultats pour deux cas de figure. Tout d’abord, nous illustrons le bénéfice des communications D2D dans le cadre d’un processus de diffusion, où le coût d’une transmission opportuniste est négligeable par rapport à celui d’une transmission cellulaire. Nous considérons ensuite le cas où les utilisateurs doivent être indemnisés pour leur participation au processus de diffusion, et où il y a donc un compromis à trouver. Nous fournissons des lignes directrices dans ce sens et nous montrons la variation d’un tel compromis en fonction de plusieurs paramètres du réseau
Cellular resources are valuable and must be saved whenever possible. In this thesis, we address the problem of content dissemination within an overloaded cellular network. Firstly, we propose SCoD (Scheduled Content Delivery), a purely cellular dissemination strategy that exploits the mobility of users and their delay tolerance in order to postpone transmissions. SCoD waits for users to gather around a minimum number of access points so that the total number of transmissions is reduced. To trigger transmissions, SCoD relies on different decision functions which launch, if necessary, a multicast transmission. The second part of this thesis deals with the same problem of saving cellular resources, but from another angle. We use D2D (Device-to-Device) communications with multicast to mitigate the traffic load on the infrastructure. We study the benefits of opportunistic communications in the context of a content distribution service based on user subscriptions. We present our results in two ways. First, we illustrate the benefits of D2D communications in a content dissemination process where the cost of opportunistic transmission is negligible compared to that of cellular transmission. Then, we consider the case where users must be compensated for their participation in the dissemination process. Therefore, there is a tradeoff to be found, we thus provide guidelines in this direction and show the variation of such a tradeoff as a function of several network parameters
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Gorbil, Gokce. "Opportunistic communications for emergency support". Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14674.

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In this thesis, we consider the problem of providing emergency support when existing communication infrastructure is unavailable. We propose using opportunistic communications (oppcomms) among mobile devices carried by civilians for the dissemination of emergency information. With oppcomms, devices exchange mes- sages at a close range of a few to tens of meters with limited or no infrastructure and messages are carried over multiple hops in a "store-carry-forward" manner by exploiting human mobility. We specifically look at the evacuation component of emergency response and propose an emergency support system (ESS) based on oppcomms to provide evacuation guidance to civilians in small-scale and large-scale urban emergencies in the absence of other means of communication. We evaluate the evacuation performance of ESS and investigate the communication characteristics of oppcomms for emergency support by simulation experiments. Our evaluations show that ESS improves evacuation by up to 31% and 14% compared to shortest path evacuation in large and small scale emergencies, respectively, and by up to 9% compared to a static-node based building evacuation system. We also investigate the resilience and security of oppcomms for emergency support under node failures and network attacks. We consider insider attacks where some nodes participating in oppcomms are compromised and misbehave. We investigate three different types of misbehaviour, including dropping packets, signal jamming and a hybrid attack on routing and evacuation that uses data falsification. Our evaluations show that node failures up to 20% are well-tolerated, and that data falsification has the most significant effect on evacuation by decreasing performance by up to 54%. In order to improve resilience of the system to such attacks, we propose a collaborative defense mechanism that combines identity-based cryptography and content-based message verification, and show that our defense mechanism improves performance by up to 50% in the presence of attacks.
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To, Toan. "Distributed opportunistic scheduling algorithms for wireless communications". Thesis, Swansea University, 2012. https://cronfa.swan.ac.uk/Record/cronfa42588.

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In this thesis, we propose a number of distributed schemes for wireless communications in the cross layer design context, considering an uplink random access network in which multiple users communicate with a common base station. In addition, we perform a comprehensive study on a splitting based multiuser selection algorithm which is simple, effective, and scales with the network size. First, we investigate a reservation-type protocol in a channel aware ALOHA system. Various Markovian models are used to describe the system and to capture the temporal correlation of the channel evolution. The average throughput of the system is obtained using the Markov Analysis technique and we show that the reservation protocol can achieve better performance than the original channel-aware ALOHA by reducing the collision probability. Second, for better resource utilization in the Opportunistic Multichannel ALOHA scheme, we propose a simple extension to the transmission policy that exploits the idle channels. Performance analysis shows that, theoretically, the maximum system throughput can be improved by up to 63% in the asymptotic case. Through numerical results, it can be seen that a significant gain is achieved even when the system consists of a small number of users. Third, we consider a splitting based multiuser selection algorithm in a probabilistic view. Asymptotic analysis leads to a functional equation, similar to that encountered in the analysis of the collision resolution algorithm. Subject to some conditions, the solution of the functional equation can be obtained, which provides the approximations for the expected number of slots and the expected number of transmissions required by the algorithm in a large system. These results shed light on open design problems in choosing parameters for the algorithm when considering the delay and the overhead jointly. A typical example is to optimize the parameters that minimize the weighted sum of these measures of interest.
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Bjurefors, Fredrik. "Measurements in opportunistic networks". Licentiate thesis, Uppsala universitet, Avdelningen för datorteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227626.

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Opportunistic networks are a subset of delay tolerant networks where the contacts are unscheduled. Such networks can be formed ad hoc by wireless devices, such as mobile phones and laptops. In this work we use a data-centric architecture for opportunistic networks to evaluate data dissemination overhead, congestion in nodes' buffer, and the impact of transfer ordering. Dissemination brings an overhead since data is replicated to be spread in the network and overhead leads to congestion, i.e., overloaded buffers. We develop and implement an emulation testbed to experimentally evaluate properties of opportunistic networks. We evaluate the repeatability of experiments in the emulated testbed that is based on virtual computers. We show that the timing variations are on the order of milliseconds. The testbed was used to investigate overhead in data dissemination, congestion avoidance, and transfer ordering in opportunistic networks. We show that the overhead can be reduced by informing other nodes in the network about what data a node is carrying. Congestion avoidance was evaluated in terms of buffer management, since that is the available tool in an opportunistic network, to handle congestion. It was shown that replication information of data objects in the buffer yields the best results. We show that in a data-centric architecture were each data item is valued differently, transfer ordering is important to achieve delivery of the most valued data.
WISENET
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Kouyoumdjieva, Sylvia T. "System Design for Opportunistic Networks". Doctoral thesis, KTH, Kommunikationsnät, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176479.

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Device-to-device communication has been suggested as a complement to traditional cellular networks as a means of offloading cellular traffic. In this thesis we explore a solution for device-to-device communication based on opportunistic content distribution in a content-centric network. Communication opportunities arise as mobile nodes roam around in an area and occasionally enter in direct communication range with one another. We consider a node to be a pedestrian equipped with a mobile device and explore the properties of opportunistic communication in the context of content dissemination in urban areas. The contributions of this thesis lie in three areas. We first study human mobility as one of the main enablers of opportunistic communication. We introduce traces collected from a realistic pedestrian mobility simulator and demonstrate that the performance of opportunistic networks is not very sensitive to the accurate estimation of the probability distributions of mobility parameters. However, capturing the space in which mobility occurs may be of high importance. Secondly, we design and implement a middleware for opportunistic content-centric networking, and we evaluate it via a small-scale testbed, as well as through extensive simulations. We conclude that energy-saving mechanisms should be part of the middleware design, while caching should be considered only as an add-on feature. Thirdly, we present and evaluate three different energy-saving mechanisms in the context of opportunistic networking: a dual-radio architecture, an asynchronous duty-cycling scheme, and an energy-aware algorithm which takes into account node selfishness. We evaluate our proposals analytically and via simulations. We demonstrate that when a critical mass of participants is available, the performance of the opportunistic network is comparable to downloading contents directly via the cellular network in terms of energy consumption while offloading large traffic volumes from the operator.

QC 20151120

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Dillon, PJ. "Enabling tetherless care with context-awareness and opportunistic communication". Thesis, University of Pittsburgh, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3690742.

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Tetherless care is a novel healthcare delivery paradigm that enables an interaction between caregivers and patients beyond the confines of traditional points of care. This thesis presents a synthesis of recent advances in wearable, ubiquitous sensing; mobile computing; wireless networks; and health information technology into a cohesive framework that enables and supports the tetherless care concept. Tetherless care is formally defined and modeled in a higher order logical framework. The model distills three relations between several classes in the model’s domain of discourse. A prototype implementation is developed and evaluated to capture and represent the logical classes of tetherless care and provide the development infrastructure upon which the relational logic outlined by the model can be implemented. An algorithm is presented and evaluated to support the delivery of traffic between mobile devices and servers despite intermittent connectivity given the changing urgency of the patient’s situation. And an example tetherless care application is presented, developed for the framework, and compared with its deployment on a similar platform. Results show that contemporary mobile devices supply sufficient power to support 24 hours of operation and that, at least, some patient environments provide sufficient opportunities for connectivity to reliably meet the demands of some tetherless care applications, ultimately leading to a conclusion of proof-of-concept for tetherless care.

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Livros sobre o assunto "Communications opportunistes"

1

Woungang, Isaac. Routing in Opportunistic Networks. New York, NY: Springer New York, 2013.

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Cheng, Nan, e Xuemin Shen. Opportunistic Spectrum Utilization in Vehicular Communication Networks. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-20445-1.

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Machinery, Association for Computing, e International Conference on Mobile Systems, Applications and Services (5th : 2007 : San Juan, P.R.), eds. MobiOpp '07: Proceedings of the First International MobiSys Workshop on Mobile Opportunistic Networking : San Juan, Puerto Rico, June 11, 2007. New York, N.Y: Association for Computing Machinery, 2007.

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4

Woungang, Isaac, Athanasios V. Vasilakos, Sanjay Kumar Dhurandher e Alagan Anpalagan. Routing in Opportunistic Networks. Springer, 2015.

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5

Woungang, Isaac, Athanasios V. Vasilakos, Sanjay Kumar Dhurandher e Alagan Anpalagan. Routing in Opportunistic Networks. Springer, 2013.

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6

Denko, Mieso K. Mobile Opportunistic Networks. Taylor & Francis Group, 2011.

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7

Denko, Mieso K. Mobile Opportunistic Networks. Taylor & Francis Group, 2019.

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8

Medeisis, Arturas, Oliver Holland e Hanna Bogucka. Opportunistic Spectrum Sharing and White Space Access: The Practical Reality. Wiley & Sons, Limited, John, 2015.

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Medeisis, Arturas, Oliver Holland e Hanna Bogucka. Opportunistic Spectrum Sharing and White Space Access: The Practical Reality. Wiley & Sons, Incorporated, John, 2015.

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Medeisis, Arturas, Oliver Holland e Hanna Bogucka. Opportunistic Spectrum Sharing and White Space Access: The Practical Reality. Wiley & Sons, Incorporated, John, 2015.

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Capítulos de livros sobre o assunto "Communications opportunistes"

1

Weik, Martin H. "opportunistic planning". In Computer Science and Communications Dictionary, 1157. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_12917.

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Hasan, Syed Faraz. "Opportunistic Networking". In Emerging Trends in Communication Networks, 33–43. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07389-7_4.

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Cheng, Nan, e Xuemin Shen. "Opportunistic Communication Spectra Utilization". In SpringerBriefs in Electrical and Computer Engineering, 9–27. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-20445-1_2.

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Xin, ChunSheng, e Min Song. "Opportunistic Spectrum Access". In Spectrum Sharing for Wireless Communications, 7–16. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13803-9_2.

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Misra, Sudip, Barun Kumar Saha e Sujata Pal. "Opportunistic Mobile Networks: Toward Reality". In Computer Communications and Networks, 259–72. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-29031-7_9.

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Gorbil, Gokce, e Erol Gelenbe. "Resilient Emergency Evacuation Using Opportunistic Communications". In Computer and Information Sciences III, 249–57. London: Springer London, 2012. http://dx.doi.org/10.1007/978-1-4471-4594-3_26.

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Boldrini, Chiara, Marco Conti e Andrea Passarella. "Social-based autonomic routing in opportunistic networks". In Autonomic Communication, 31–67. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/978-0-387-09753-4_2.

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Hahm, Seong-il, Jongwon Lee e Chong-kwon Kim. "Distributed Opportunistic Scheduling in IEEE 802.11 WLANs". In Personal Wireless Communications, 263–74. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11872153_23.

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Dede, Jens, e Anna Förster. "Comparative Analysis of Opportunistic Communication Technologies". In Interoperability, Safety and Security in IoT, 3–10. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-52727-7_1.

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Mihaita, Alexandra-Elena, Ciprian Dobre, Florin Pop, Constandinos X. Mavromoustakis e George Mastorakis. "Secure Opportunistic Vehicle-to-Vehicle Communication". In Studies in Big Data, 229–68. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-45145-9_10.

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Trabalhos de conferências sobre o assunto "Communications opportunistes"

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Mox, Daniel, Kashish Garg, Alejandro Ribeiro e Vijay Kumar. "Opportunistic Communication in Robot Teams". In 2024 IEEE International Conference on Robotics and Automation (ICRA), 12090–96. IEEE, 2024. http://dx.doi.org/10.1109/icra57147.2024.10610971.

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Cladera, Fernando, Zachary Ravichandran, Ian D. Miller, M. Ani Hsieh, C. J. Taylor e Vijay Kumar. "Enabling Large-scale Heterogeneous Collaboration with Opportunistic Communications". In 2024 IEEE International Conference on Robotics and Automation (ICRA), 2610–16. IEEE, 2024. http://dx.doi.org/10.1109/icra57147.2024.10611469.

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Nikoletseas, Sotiris A. "Session details: Opportunistic communications". In MSWiM '13: 16th ACM International Conference on Modeling, Analysis and Simulation of Wireless and Mobile Systems. New York, NY, USA: ACM, 2013. http://dx.doi.org/10.1145/3254738.

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Budzik, Jay, Shannon Bradshaw, Xiaobin Fu e Kristian J. Hammond. "Clustering for opportunistic communication". In the eleventh international conference. New York, New York, USA: ACM Press, 2002. http://dx.doi.org/10.1145/511446.511541.

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Nam, Young-Han, Jianzhong Zhang, Hesham El-Gamal e Tony Reid. "Opportunistic Communications with Distorted CSIT". In 3rd International Symposium on Wireless Communication Systems. IEEE, 2006. http://dx.doi.org/10.1109/iswcs.2006.4362250.

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Shikfa, Abdullatif. "Security challenges in opportunistic communication". In 2011 IEEE GCC Conference and Exhibition (GCC). IEEE, 2011. http://dx.doi.org/10.1109/ieeegcc.2011.5752570.

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Sohail, Mohsin, e Mihaela Ulieru. "Opportunistic Communication for eNetworks Cyberengineering". In IECON 2007 - 33rd Annual Conference of the IEEE Industrial Electronics Society. IEEE, 2007. http://dx.doi.org/10.1109/iecon.2007.4460410.

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Pathak, Ranjana, Peizhao Hu, Jadwiga Indulska e Marius Portmann. "Protocol for efficient opportunistic communication". In 38th Annual IEEE Conference on Local Computer Networks (LCN 2013). IEEE, 2013. http://dx.doi.org/10.1109/lcn.2013.6761240.

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Hui, Pan, e Anders Lindgren. "Phase transitions of opportunistic communication". In the third ACM workshop. New York, New York, USA: ACM Press, 2008. http://dx.doi.org/10.1145/1409985.1409999.

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Ciobanu, Radu Ioan, Ciprian Dobre, Valentin Cristea e Dhiya Al-Jumeily. "Social Aspects for Opportunistic Communication". In 2012 11th International Symposium on Parallel and Distributed Computing (ISPDC). IEEE, 2012. http://dx.doi.org/10.1109/ispdc.2012.41.

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Relatórios de organizações sobre o assunto "Communications opportunistes"

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Zhang, Jianhua, S. M. Shafiul Alam, Anthony R. Florita, Adarsh Hasandka, Jin Wei-Kocsis, Dexin Wang, Liuqing Yang e Brian S. Hodge. Opportunistic Hybrid Communications Systems for Distributed PV Coordination. Office of Scientific and Technical Information (OSTI), março de 2020. http://dx.doi.org/10.2172/1606149.

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Tan, Sheu-Sheu, Dong Zheng, Junsham Zhang e James Zeidler. Distributed Opportunistic Scheduling For Ad-Hoc Communications Under Delay Constraint. Fort Belvoir, VA: Defense Technical Information Center, janeiro de 2010. http://dx.doi.org/10.21236/ada515840.

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Rao, Ramesh, B. S. Manoj e Michele Zorzi. A Research Proposal on Cognitive Opportunistic Communications and Cognitive Cross-layer Protocol Stack Design. Fort Belvoir, VA: Defense Technical Information Center, julho de 2012. http://dx.doi.org/10.21236/ada584715.

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