Dissertations / Theses on the topic 'Ad-hoc Collaboration'
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Jiang, Ning. "COLLABORATION ENFORCEMENT IN MOBILE AD HOC NETWORKS." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2718.
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Mobile Ad hoc NETworks (MANETs) have attracted great research interest in recent years. Among many issues, lack of motivation for participating nodes to collaborate forms a major obstacle to the adoption of MANETs. Many contemporary collaboration enforcement techniques employ reputation mechanisms for nodes to avoid and penalize malicious participants. Reputation information is propagated among participants and updated based on complicated trust relationships to thwart false accusation of benign nodes. The aforementioned strategy suffers from low scalability and is likely to be exploited by adversaries. To address these problems, we first propose a finite state model. With this technique, no reputation information is propagated in the network and malicious nodes cannot cause false penalty to benign hosts. Misbehaving node detection is performed on-demand; and malicious node punishment and avoidance are accomplished by only maintaining reputation information within neighboring nodes. This scheme, however, requires that each node equip with a tamper-proof hardware. In the second technique, no such restriction applies. Participating nodes classify their one-hop neighbors through direct observation and misbehaving nodes are penalized within their localities. Data packets are dynamically rerouted to circumvent selfish nodes. In both schemes, overall network performance is greatly enhanced. Our approach significantly simplifies the collaboration enforcement process, incurs low overhead, and is robust against various malicious behaviors. Simulation results based on different system configurations indicate that the proposed technique can significantly improve network performance with very low communication cost.Ph.D.
School of Computer Science
Engineering and Computer Science
Computer Science
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Chardin, Ivan Sergeyevich 1977. "Spatial aspects of mobile ad hoc collaboration." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/61140.
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Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2003.Includes bibliographical references (p. 72-76).
Traditionally, communication devices are designed to overcome distance in space or time. How can personal mobile tools augment local interaction and promote spontaneous collaboration between users in proximity? Mobile ad hoc collaboration is an emerging framework that attempts to answer this question. This thesis reviews current research in mobile ad hoc collaboration, explores its precedents in art, and examines the enabling wireless communication and location sensing technology. It then proceeds to consider location, proximity and spatial organization as major factors in the development of interfaces and applications within the framework. The importance of seamless transitions between face-to-face communication and mediated communication is emphasized, and the principle of ad hoc communication group formation on the basis of proximity is proposed. The principle is demonstrated in a prototype wearable system for synchronous voice messaging.
by Ivan Sergeyevich Chardin.
S.M.
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Citro, Sandy, and c1tro@yahoo com au. "A Framework for Real Time Collaborative Editing in a Mobile Replicated Architecture." RMIT University. Computer Science and Information Technology, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080424.113836.
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Mobile collaborative work is a developing sub-area of Computer Supported Collaborative Work (CSCW). The future of this field will be marked by a significant increase in mobile device usage as a tool for co-workers to cooperate, collaborate and work on a shared workspace in real-time to produce artefacts such as diagrams, text and graphics regardless of their geographical locations. A real-time collaboration editor can utilise a centralised or a replicated architecture. In a centralised architecture, a central server holds the shared document as well as manages the various aspects of the collaboration, such as the document consistency, ordering of updates, resolving conflicts and the session membership. Every user's action needs to be propagated to the central server, and the server will apply it to the document to ensure it results in the intended document state. Alternatively, a decentralised or replicated architecture can be used where there is no central server to store the shared document. Every participating site contains a copy of the shared document (replica) to work on separately. Using this architecture, every user's action needs to be broadcast to all participating sites so each site can update their replicas accordingly. The replicated architecture is attractive for such applications, especially in wireless and ad-hoc networks, since it does not rely on a central server and a user can continue to work on his or her own local document replica even during disconnection period. However, in the absence of a dedicated server, the collaboration is managed by individual devices. This presents challenges to implement collaborative editors in a replicated architecture, especially in a mobile network which is characterised by limited resource reliability and availability. This thesis addresses challenges and requirements to implement group editors in wireless ad-hoc network environments where resources are scarce and the network is significantly less stable and less robust than wired fixed networks. The major contribution of this thesis is a proposed framework that comprises the proposed algorithms and techniques to allow each device to manage the important aspects of collaboration such as document consistency, conflict handling and resolution, session membership and document partitioning. Firstly, the proposed document consistency algorithm ensures the document replicas held by each device are kept consistent despite the concurrent updates by the collaboration participants while taking into account the limited resource of mobile devices and mobile networks. Secondly, the proposed conflict management technique provides users with conflict status and information so that users can handle and resolve conflicts appropriately. Thirdly, the proposed membership management algorithm ensures all participants receive all necessary updates and allows users to join a currently active collaboration session. Fourthly, the proposed document partitioning algorithm provides flexibility for users to work on selected parts of the document and reduces the resource consumption. Finally, a basic implementation of the framework is presented to show how it can support a real time collaboration scenario.
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Perez, Priego Juan Gabriel. "Ad-Hoc Sharing for Palm Devices." ScholarWorks@UNO, 2005. http://scholarworks.uno.edu/td/239.
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The current generation of Palm PDA devices is designed to share information records primarily with a base desktop system, or a server. Therefore, their built- in features for sharing data during ad-hoc collaboration among groups of mobile users are inadequate. In this thesis, we describe a new framework that addresses this problem by allowing users to transparently share the record databases of common applications during spontaneous collaborative sessions. The framework also allows users to define custom sharing policies for each application/user pair. These policies determine the manner in which records are exchanged and update, thereby automating the process of handling conflicts and preserving user privacy preferences. We also present implementation results, in which we have used the framework to create shared versions of common applications, such as Calendar and Memo. Our experimental results show that the programming effort involved is minimal and the user interaction with the application is, essentially, the same as in the original application.
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Manescu, Corneliu. "Video and voice coding for mobile ad-hoc collaboration." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0000740.
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Lee, Wei-Hsing. "Decentralized ad-hoc groupware API and framework for mobile collaboration." [Florida] : State University System of Florida, 2000. http://etd.fcla.edu/etd/uf/2000/ane5959/master.pdf.
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Thesis (M.S.)--University of Florida, 2000.Title from first page of PDF file. Document formatted into pages; contains ix, 83 p.; also contains graphics. Vita. Includes bibliographical references (p. 81-82).
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Heinemann, Andreas. "Collaboration in Opportunistic Networks." Phd thesis, Saarbrücken VDM Verlag Dr. Müller, 2007. http://tuprints.ulb.tu-darmstadt.de/834/1/heinemann07-diss.pdf.
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Motivation. With the increasing integration of wireless short-range communication technologies (Bluetooth, 802.11b WiFi) into mobile devices, novel applications for spontaneous communication, interaction and collaboration are possible. We distinguish between active and passive collaboration. The devices help users become aware of each other and stimulate face-to-face conversation (active collaboration). Also, autonomous device communication for sharing information without user interaction is possible, i.e., devices pass information to other devices in their vicinity (passive collaboration). Both, active and passive collaboration requires a user to specify what kind of information he offers and what kind of information he is interested in. Object of Research: Opportunistic Networks. Spontaneous communication of mobile devices leads to so-called opportunistic networks, a new and promising evolution in mobile ad-hoc networking. They are formed by mobile devices which communicate with each other while users are in close proximity. There are two prominent characteristics present in opportunistic networks: 1) A user provides his personal device as a network node. 2) Users are a priori unknown to each other. Objectives. Due to the fact that a user dedicates his personal device as a node to the opportunistic network and interacts with other users unknown to him, collaboration raises questions concerning two important human aspects: user privacy and incentives. The users’ privacy is at risk, since passive collaboration applications may expose personal information about a user. Furthermore, some form of incentive is needed to encourage a user to share his personal device resources with others. Both issues, user privacy and incentives, need to be taken into account in order to increase the user acceptability of opportunistic network applications. These aspects have not been addressed together with the technical tasks in prior opportunistic network research. Scientific Contribution and Evaluation. This thesis investigates opportunistic networks in their entirety, i.e., our technical design decisions are appropriate for user privacy preservation and incentive schemes. In summary, the proposed concepts comprise system components, a node architecture, a system model and a simple one-hop communication paradigm for opportunistic network applications. One focus of this work is a profile-based data dissemination mechanism. A formal model for this mechanism will be presented. On top of that, we show how to preserve the privacy of a user by avoiding static and thus linkable data and an incentive scheme that is suitable for opportunistic network applications. The evaluation of this work is twofold. We implemented two prototypes on off-the-shelf hardware to show the technical feasibility of our opportunistic network concepts. Also, the prototypes were used to carry out a number of runtime measurements. Then, we developed a novel two-step simulation method for opportunistic data dissemination. The simulation combines real world user traces with artificial user mobility models, in order to model user movements more realistically. We investigate our opportunistic data dissemination process under various settings, including different communication ranges and user behavior patterns. Our results depict, within the limits of our model and assumptions, a good performance of the data dissemination process.
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Kedji, Komlan Akpédjé. "Modélisation et mise en œuvre de processus collaboratifs ad hoc." Phd thesis, Université Toulouse le Mirail - Toulouse II, 2013. http://tel.archives-ouvertes.fr/tel-00912975.
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Le développement logiciel est une activité intensément collaborative. Les problématiques habituelles de collaboration (organisation des tâches, utilisation des ressources, communication, etc.) y sont exacerbées par le rythme rapide des changements, la complexité et la grande interdépendance des artéfacts, le volume toujours croissant d'informations de contexte à traiter, la distribution géographique des participants, etc. Par conséquent, la question du support outillé de la collaboration se pose plus fortement que jamais en ingénierie logicielle. Dans cette thèse, nous abordons la question de la collaboration sous l'angle de la modélisation et de l'exploitation des processus de développement. Ces derniers sont traditionnellement considérés comme une structure imposée sur le développement d'un produit logiciel. Cependant, une part importante de la collaboration en génie logiciel est de nature ad hoc, faite d'activités non planifiées. Afin de faire contribuer les processus logiciels au support de la collaboration, en particulier celle non planifiée, nous nous intéressons à leur fonction de banques d'information sur les éléments clés de cette collaboration et les interactions entre ces derniers. Notre contribution est, d'une part, un modèle conceptuel du support au développement collaboratif, capable de rendre compte de la structure d'outils classiques comme ceux de gestion de versions ou de gestion de défauts logiciels. Ce modèle conceptuel est ensuite appliqué aux modèles de processus logiciels. Nous définissons ainsi une approche globale d'exploitation des informations de processus pour le support de la collaboration, basée sur les notions centrales de langage de requête d'information et de mécanisme de réaction aux événements. D'autre part, nous proposons un métamodèle, CMSPEM (Collaborative Model-Based Software & System Process Engineering Metamodel), qui enrichit le standard SPEM (Software & System Process Engineering Metamodel) avec des concepts et relations nécessaires au support de la collaboration. Ce métamodèle est outillé avec des outils de création de modèle (éditeurs graphiques et textuels), et un serveur de processus offrant un langage de requêtes basé sur HTTP/REST et un framework de souscription et de réaction aux événements de processus. Enfin, notre approche conceptuelle a été illustrée et validée, en premier lieu, par une analyse des pratiques inférées à partir des données de développement de 219 projets open source. En second lieu, des utilitaires de support à la collaboration (mise à disposition d'informations conceptuelles, automatisation d'actions, extraction d'information sur les contributions individuelles) ont été implémentés à travers le serveur de processus CMSPEM.
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Braconnot, Velloso Pedro. "Un modèle de confiance pour les réseaux ad hoc." Paris 6, 2008. http://www.theses.fr/2008PA066121.
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Cette thèse aborde le problème de l’evaluation et de la gestion de la confiance dans les réseaux ad hoc, où les noeuds accumulent le rôle de routeur, de serveur et de client, les obligeant coopérer pour un bon fonctionnement du réseau. Plusieurs protocoles et applications ont été proposés puisque les solutions conventionnelles ne sont pas adaptées aux réseaux ad hoc. Cependant, la plupart des ces travaux considèrent l’existence d’une parfaite coopération entre les noeuds supposant qu’ils se comportent tous selon les spécifications des applications et des protocoles précédemment déterminés pour le réseau. Néanmoins, cette condition peut être fausse, à cause de restrictions de ressource ou comportement malveillant. Par suite, les noeuds peuvent ne pas se comporter comme prévu et entraîner un mauvais fonctionnement du réseau. Par conséquent, un mécanisme permettant à un noeud d’avoir confiance en d’autres noeuds est nécessaire. Nous proposons un modèle de confiance où les noeuds d’un réseau ad hoc établissent un rapport de confiance basé sur des expériences et des recommandations préalables. Nous présentons également le Recommendation Exchange Protocol qui permet aux noeuds d’échanger des recommandations avec ses voisins. Le but est de rendre les noeuds d’un réseau capables de recueillir des informations pour raisonner, apprendre et prendre leur propre décision. Nous nous concentrons sur fournir aux noeuds le niveau de confiance de chaque voisin direct, c’est-à-dire, un voisin a portée radio. Différemment de la majorité des travaux sur le sujet, notre modèle s’applique bien à d’autres échelles, en limitant les interactions aux voisins directs, ce qui diminue le nombre de messages et, par conséquent, la consommation d’énergie. En outre, elle aide à atténuer les l’effet des fausses recommandations. Nous présentons le concept de maturité de rapport qui permet aux noeuds d’améliorer l’efficacité du modèle dans les réseaux mobiles. Nous montrons l’exactitude de notre modèle dans un réseau ad hoc de communication directe par des simulations en utilisant un simulateur développé pour notre modèle. L’analyse a, alors, été étendue aux réseaux mobiles ad hoc multisaut, montrant les avantages d’employer le concept de rapport de maturité. Finalement, nous évaluons l’impact des noeuds malveillants qui envoient de fausses recommandations afin de dégrader l’efficacité du modèle de confiance. Les résultats montrent que notre modèle tolère jusqu’à 40% de noeuds malveillants.
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Kwong, Mylène D. "Transmission efficace en temps réel de la voix sur réseaux ad hoc sans fil." Thèse, Université de Sherbrooke, 2008. http://savoirs.usherbrooke.ca/handle/11143/1827.
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La téléphonie mobile se démocratise et de nouveaux types de réseaux voient le jour, notamment les réseaux ad hoc. Sans focaliser exclusivement sur ces réseaux particuliers, le nombre de communications vocales effectuées chaque minute est en constante augmentation mais les réseaux sont encore souvent victimes d'erreurs de transmission. L'objectif de cette thèse porte sur l'utilisation de méthodes de codage en vue d'une transmission de la voix robuste face aux pertes de paquets, sur un réseau mobile et sans fil perturbé permettant le multichemin. La méthode envisagée prévoit l'utilisation d'un codage en descriptions multiples (MDC) appliqué à un flux de données issu d'un codec de parole bas débit, plus particulièrement l'AMR-WB (Adaptive Multi Rate - Wide Band). Parmi les paramètres encodés par l'AMR-WB, les coefficients de la prédiction linéaire sont calculés une fois par trame, contrairement aux autres paramètres qui sont calculés quatre fois. La problématique majeure réside dans la création adéquate de descriptions pour les paramètres de prédiction linéaire. La méthode retenue applique une quantification vectorielle conjuguée à quatre descriptions. Pour diminuer la complexité durant la recherche, le processus est épaulé d'un préclassificateur qui effectue une recherche localisée dans le dictionnaire complet selon la position d'un vecteur d'entrée. L'application du modèle de MDC à des signaux de parole montre que l'utilisation de quatre descriptions permet de meilleurs résultats lorsque le réseau est sujet à des pertes de paquets. Une optimisation de la communication entre le routage et le processus de création de descriptions mène à l'utilisation d'une méthode adaptative du codage en descriptions. Les travaux de cette thèse visaient la retranscription d'un signal de parole de qualité, avec une optimisation adéquate des ressources de stockage, de la complexité et des calculs. La méthode adaptative de MDC rencontre ces attentes et s'avère très robuste dans un contexte de perte de paquets.
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Boulkenafed, Malika. "Gestion de l'accès aux données dans les réseaux sans fil en mode ad hoc." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2003. http://tel.archives-ouvertes.fr/tel-00469416.
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Boulkaibet, Ilyes. "Modelling collaborative motion in mobile ad hoc networks." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5155.
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Thesis (MSc (Mathematical Sciences)--University of Stellenbosch, 2010.ENGLISH ABSTRACT: In this thesis, a pricing mechanism to stimulate cooperation between nodes in ad hoc networks is explored. The model incorporates incentives for users to act as transit nodes and carry the traffic between other nodes on multi-hop paths, and to be rewarded with their own ability to send traffic. The thesis investigates the consequences of this pricing model by means of simulation of a network and illustrates the way in which network resources are allocated to users according to their geographical position. Moreover, since modelling node movements is an important aspect in ad hoc network simulation, a collective mobility model, the adaptive mobility model, is used to maximise the area coverage of the nodes.
AFRIKAANSE OPSOMMING: In hierdie tesis word ’n koste meganisme gebruik om samewerking te stimuleer tussen nodusse in ad hoc netwerke. Die model inkorporeer trekpleisters deur gebruikers te beloon om verkeer te stuur deur op te tree as transito nodusse, en verkeer tussen nodusse op multi-skakel paaie te dra. Die tesis ondersoek die ge- volge van die koste model deur die simulering van ’n netwerk, en demonstreer die manier waarop die netwerk hulpbronne geallokeer word aan gebruikers gebaseer op hulle geografiese posisie. Siende dat die modellering van nodus bewegings ’n belangrike aspek is in ad hoc netwerk simulasie, word ’n kollek- tiewe mobiliteits model sowel as ’n veranderlike mobiliteits model gebruik om die dekkings areas van die nodusse te maksimeer.
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Baalaji, Venkateshwaraiyer S. "Collaborative services in an ad hoc wireless network." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FBaalaji%5FITM.pdf.
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Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, Sept. 2004.Thesis advisor(s): Alex Bordetsky, Gurminder Singh. Includes bibliographical references (p. 71). Also available online.
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Janson, Thomas [Verfasser], and Christian [Akademischer Betreuer] Schindelhauer. "Energy-efficient collaborative beamforming in wireless ad hoc networks." Freiburg : Universität, 2015. http://d-nb.info/1114996335/34.
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Buszko, Dominik. "A lightweight collaborative API for ad-hoc mobile computing." [Florida] : State University System of Florida, 2000. http://etd.fcla.edu/etd/uf/2000/ane5875/edt5.pdf.
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Thesis (M.S.)--University of Florida, 2000.Title from first page of PDF file. Document formatted into pages; contains x, 92 p.; also contains graphics. Vita. Includes bibliographical references (p. 88-91).
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Vu, Cong Hoan, and Adeyinka Soneye. "An Analysis of Collaborative Attacks on Mobile Ad hoc Networks." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2407.
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A Mobile Ad hoc Network (MANET) consists of a set of communicating wireless mobile nodes or devices that do not have any form of fixed infrastructure or centralized authority. The security in MANET has become a significant and active topic within the research community. This is because of high demand in sharing streaming video and audio in various applications, one MANET could be setup quickly to facilitate communications in a hostile environment such as battlefield or emergency situation likes disaster rescue operation. In spite of the several attacks aimed at specific nodes in MANET that have been uncovered, some attacks involving multiple nodes still receive little attention. A reason behind this is because people make use of security mechanisms applicable to wired networks in MANET and overlook the security measures that apply to MANET. Furthermore, it may also have to do with the fact that no survey or taxonomy has been done to clarify the characteristics of different multiple node attacks. This thesis addresses the aforementioned gap by providing a proper definition and categorization of collaborative attacks against MANET from the various multiple node attacks found. Simulation using OPNET Modeler was used to investigate the performance impact of a collaborative blackhole attack on a mobile ad hoc network. Network throughput, packet delivery ratio and end-to-end delay are the performance metrics used in our result analysis. Based on the analyses of performance metrics made, we realised the consequences of a collaborative blackhole attack on MANET. In order to prevent or reduce these consequences, we also discuss a number of mitigation plans to counteract the different kinds of collaborative attacks. Keywords: MANET, Collaborative Attacks, Multiple Node, Blackhole.Contact Information: Author(s): Cong Hoan Vu Address: Folkparksvägen 19:08, 372 40 Ronneby, Sweden. E-mail: vuconghoan@gmail.com Adeyinka Soneye Address: Polhemsgatan 27B, LGH 30, 371 40 Karlskrona, Sweden. E-mail: adso07@student.bth.se
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Riedel, Alexander. "Collaborative scheduling using context-awarenes." Thesis, KTH, Kommunikationssystem, CoS, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91110.
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Today most cellular phones, personal digital assistants, PCs, etc. offer an electronic calendar. Electronic calendars are especially useful for people who have many different meetings each day and who need to know when the meetings start and who is involved in each meeting. With the aid of a program a calendar can be published on web, shared with other people to enable collaboration, or synchronized between different devices. Current calendaring software offers an almost unlimited set of features and services. However, today such software does not utilize context-awareness, for example exploiting knowledge of the user's location. When people collaborate they often need to meet in order to do a task jointly or discuss something. It can be difficult to plan a meeting because people have booked their available time differently in their calendars. Because of this there is a need to automatically schedule certain types of meetings. In this thesis, a program that schedules meetings automatically is designed, implemented and evaluated. This program facilitates collaboration by finding a commonly available time and/or meeting place for a meeting, thus making it easier for the meeting people to agree. When meetings are scheduled without requiring too much attention from a user and the number of human errors can be reduced while planing a meeting, users do not need to expends as much effort as it goes into scheduling meetings today. Because today a company planing a collaboration task collectively spends a lot of time and effort searching for a commonly available time with this effort increasing non-linearly with increased numbers of participants companies can obviously benefit from automated scheduling systems. Testing with the application reveals that incorporating of user's location information into scheduling is a great tool to facilitate collaboration. The survey also shows the need for extensions to the developed application; with the new features utilizing location information. The evaluation also shows that the developed scheduling program has managed to reduce the time and effort spent while scheduling meetings.Idag finns det en elektronisk kalender i de flesta mobiltelefoner, datorer och PDA:n. Elektroniska kalendrar är användbara framför allt för människor som har flera möten varje dag och som behöver veta när mötena startar vilka som ska delta. Vissa elektroniska kalendrar kan publiceras på webben, delas med andra människor för att möjliggöra samarbete och synkroniseras mellan till exempel mobiltelefoner, datorer och PDA:n. Kalendermjukvara erbjuder idag ett nästan obegränsat antal funktioner och nyttiga tjänster. Denna typ av mjukvara är dock generellt sett inte medveten om information såsom användarens position, vilket i sammanhanget kalls context-awareness. När människor ska samarbeta krävs ofta att de träffas för att utföra uppgifter tillsammans eller diskutera viktiga ämnen. För att kunna ha möten krävs att möten först planeras, vilket kan vara svårt då de inbjudna är olika uppbokade i sina respektive kalendrar. Av den anledningen finns ett behov av att automatisera schemaläggningen för vissa typer av möten. I detta examensarbete skall ett program för automatisk schemaläggning designas, utvecklas och evalueras. Programmet skall underlätta samarbete mellan mötesdeltagare genom att ta över uppgiften att hitta en gemensam tid och/eller plats för ett möte. Programmet skall därmed också underlätta för mötesdeltagarna att komma överens. När möten kan schemaläggas utan att det kräver för mycket uppmärksamhet från användarna och antalet mänskliga fel kan reduceras när möten planeras, behöver man inte lägga lika mycket arbete, som idag, på att schemalägga möten. Eftersom det för tillfället krävs mycket tid och resurser för ett företag för att schemalägga ett möte, samtidigt som tiden för att planera ett möte inte ökar linjärt med antalet deltagare, kommer företag antagligen att dra nytta av ett automatiserat schemaläggningssystem. En undersökning genomförd av ett antal testpersoner som använt applikationen visade på att användarens position var en viktig parameter som kunde förbättra schemaläggningen av möten. Undersökningen visade också att applikationen hade ett stort behov av att vidareutvecklas genom nya potentiella funktioner som tar hänsyn till användarens position. Men viktigast av allt så visade undersökningen på att applikationen lyckats med att reducera tiden det tar för att planera möten.
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Patibandla, Siva Teja. "Development of Mobile Ad-Hoc Network for Collaborative Unmanned Aerial Vehicles." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3155.
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The purpose of this research was to develop a mobile ad-hoc network for collaborative Unmanned Aerial Vehicles (UAVs) based on a mesh networking standard called IEEE 802.11s. A low-cost, small form-factor, IEEE 802.11a based wireless modem was selected and integrated with the existing flight control system developed at Virginia Commonwealth University (VCU) UAV Laboratory. A self-configurable user-space application on the wireless modem was developed to provide functionality to collaborative algorithms, and to monitor the performance of the wireless network. The RAMS simulator, developed at VCU, was upgraded to support the simulation of advanced networking capabilities by integrating with a simulator called ns-3. The reconfigurability and performance of the IEEE 802.11s mesh network was validated and evaluated by conducting real-world flights. The results show that the IEEE 802.11s is a promising solution for collaborative UAV applications.
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Jingzhi, Guo, and n/a. "Integrating Ad Hoc Electronic Product Catalogues Through Collaborative Maintenance of Semantic Consistency." Griffith University. School of Computing and Information Technology, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050824.125257.
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Existing electronic markets are fragmented in the sense that each is an information island. The interoperation of product information between them is difficult especially in semantics communication. This prevents the formation of global electronic markets and the lowering distribution cost through market globalisation. The traditional and contemporary ap-proaches of product standardisation and ontology mediation could solve the problem only if all markets could adopt the same product standards, or mediation systems could mediate all heterogeneous standards and markets without semantic conflicts. However, problems generally exist in adopting a universal standard or mediating all markets through existing mediation systems. A reflection of the issue is that there are millions of ad hoc electronic product catalogues (EPCs) situated in small and medium sized enterprises (SMEs), where each EPC is a semantic community, often not aware of standards and mediation systems due to its ad hoc nature. This thesis focuses on the semantic integration of autonomous ad hoc EPCs, which are semantically inconsistent with each other. Firstly, a novel Collaborative Concept Exchange (CONEX) approach is developed for the se-mantic integration of ad hoc EPCs. Using this approach, a PRODUCT MAP is first built based on the theories of semiotic analysis and market segmentation. It functions as an analytical framework to articulate ad hoc EPCs, and answers the questions: what are the general char-acteristics of ad hoc EPCs, what are their heterogeneous relations, and how they are unevenly distributed in fragmented electronic markets. Within this framework, an abstract representa-tion of ad hoc EPCs is proposed using the articulated elements that are simple and manipu-lable. Major contributions of this framework include: the models of the abstract representa-tion of ad hoc EPCs on their structures, concepts and contexts; the semantic integration conditions of heterogeneous ad hoc EPCs; and a ConexNet of market network topology that captures the characteristics of ad hoc EPCs that are unevenly distributed in fragmented elec-tronic markets. Secondly, a three-layer CONEX information model is proposed to integrate ad hoc EPCs based on the PRODUCT MAP, which provides a trichotomy of systems, designers and users. The strategy behind the model is the separation of structure from concept and context, and hence they can be independently managed to resolve semantic conflicts between ad hoc EPCs. The major contributions of this model include the CONEX framework, collaboration mechanism and context transformation. The CONEX framework presents a formal characteri-sation and reconstruction of the structures of ad hoc EPCs based on a CONEX structure model and a CONEX grammar. It provides a formal specification for representing ad hoc EPCs including concept structure, classifier structure and mapping structure. The semantic conflicts in designing the concepts of ad hoc EPCs are resolved by a collaboration mecha-nism based on a semantic consistency model. The collaboration mechanism includes three key procedures: replicating unique concept identifiers and translating concept definitions be-tween common concepts of common EPCs; localising common concepts to local EPCs; and globalising local concepts to common EPCs. Users in the CONEX information model are not involved in any integration activities. They are provided with automatic and accurate concept exchange services through a mechanism of context transformation, which is designed based on an algorithm called Heterogeneous Concept Transformation. The separate integration of structures, concepts and contexts of ad hoc EPCs guarantees that the requirements of flexi-bility, evolvability and exactness of semantic integration have been met. Thirdly, the feasibility and features of the Collaborative Concept Exchange approach have been demonstrated in a prototype implementation that provides the services of collaborative concept design for semantic conflict resolution, and heterogeneous concept transformation for accurate and automatic concept exchange between ad hoc EPCs. A key contribution in the implementation level is the independent representation of the CONEX framework called XML PRODUCT MAP (XPM). XPM provides a feature of platform independence by con-forming to the standards of W3C XML, Simple Object Access Protocol and Web Services Description Language in both document specification and document transport. It is also a demonstration that the generic CONEX structure model and CONEX grammar can be imple-mented in any specific language such as XML for the particular scenarios of semantic integra-tion. With the aid of a collection of XPM document templates, two components called Con-cept Collaborator and Concept Transformer of the CONEX prototype are implemented to demonstrate how concepts are collaboratively designed to resolve semantic conflicts and how concepts are automatically and accurately exchanged between autonomous, heterogeneous and distributed ad hoc EPCs.
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Gao, Feng. "Improving communications with Bluetooth enabled collaborative middleware in mobile ad-hoc networks." Thesis, University of Salford, 2010. http://usir.salford.ac.uk/26686/.
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The main aim of the research presented in this Thesis was to investigate 'how can collaborative middleware based CWE (Collaborative Working Environment), combined \\ith Bluetooth technology, enhance the communications of mobile users.' The high level collaborative middleware is a RTD (Research and Technology Development) challenge and one of most desirable medium to long term research outputs for CWEs. This research activity outlines a collaborative middleware that has been developed on Smartphone technology and enables the creation of a multi-user collaborative \\orking environment via a Bluetooth wireless communications network. A Bluetooth network as a type of ad-hoc network works on the mobile devices that have the ability to dynamically form connections with each other to create a network, called MANET (Mobile Ad-hoc Network). To achieve this aim, it started \\ith discussing the ke\ design parameters, and then the design of collaborative middleware with collaborative functionality; followed by the development and iterative modification of the middleware and applications until fully mature; ended by completed a SWOT (Strengths. Weaknesses, Opportunities, and Threats) analysis and a comparison test with focus group to determine the collaborative middleware's potential impact to improve communications between users. The result of the evaluation conclude that Bluetooth enabled collaborative middleware can improve the communications of mobile ad-hoc networks. This research also provides two key areas of contribution. Firstly it provides an evolutionary step for the creation of new collaborative applications. Secondly, it has optimised the use of Bluetooth beyond the functionality for which it was originally designed.
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Subramanian, Ramanan. "Modeling and analysis of the performance of collaborative wireless ad-hoc networks: an information-theoretic perspective." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37083.
Full textAbstract:
This work focuses on the performance characterization of distributed collaborative ad-hoc networks, focusing on such metrics as the lifetime, latency, and throughput capacity of two such classes of networks. The first part concerns modeling and optimization of static Wireless Sensor Networks, specifically dealing with the issues of energy efficiency, lifetime, and latency. We analyze and characterize these performance measures and discuss various fundamental design tradeoffs. For example, energy efficiency in wireless sensor networks can only be improved at the cost of the latency (the delay incurred during communication). It has been clearly shown that improvement in energy efficiency through data aggregation increases the latency in the network. In addition, sleep-active duty cycling of nodes (devices constituting the network), a commonly employed mechanism to conserve battery lifetime in such networks, has adverse effects on their functionality and capacity. Hence these issues deserve a detailed study.
The second part of this work concerns performance modeling of Delay Tolerant Networks (DTNs) and Sparse Mobile Ad-Hoc Networks (SPMANETs) in general. We first investigate the effect of modern coding, such as the application of packet-level rateless codes, on the latency, reliability, and energy efficiency of the network. These codes provide us the means to break large messages into smaller packets thereby enabling efficient communication. The work then focuses on developing and formalizing an information-theoretic framework for Delay Tolerant- and other Sparse Mobile Networks. This is enabled by the use of an embedded-Markov-chain approach used for complex queuing-theoretic problems. An important goal of this work is to incorporate a wide range of mobility models into the analysis framework. Yet another important question will be the effect of changing the mobility on the comparative performance of networking protocols. Lastly, the framework will be extended to various communication paradigms such as two-hop vs multi-hop routing, unicast, and multicast.
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Guan, Wenyang. "Adaptive QoS control of DSRC vehicle networks for collaborative vehicle safety applications." Thesis, Swansea University, 2013. https://cronfa.swan.ac.uk/Record/cronfa42507.
Full textAbstract:
Road traffic safety has been a subject of worldwide concern. Dedicated short range communications (DSRC) is widely regarded as a promising enabling technology for collaborative safety applications (CSA), which can provide robust communication and affordable performance to build large scale CSA system. The main focus of this thesis is to develop solutions for DSRC QoS control in order to provide robust QoS support for CSA. The first design objective is to ensure robust and reliable message delivery services for safety applications from the DSRC networks. As the spectrum resources allocated to DSRC network are expected to be shared by both safety and non-safety applications, the second design objective is to make QoS control schemes bandwidth-efficient in order to leave as much as possible bandwidth for non-safety applications. The first part of the thesis investigates QoS control in infrastructure based DSRC networks, where roadside access points (AP) are available to control QoS control at road intersections. After analyse DSRC network capabilities on QoS provisioning without congestion control, we propose a two-phases adaptive QoS control method for DSRC vehicle networks. In the first phase an offline simulation based approach is used to and out the best possible system configurations (e.g. message rate and transmit power) with given numbers of vehicles and QoS requirements. It is noted that with different utility functions the values of optimal parameters proposed by the two phases centralized QoS control scheme will be different. The conclusions obtained with the proposed scheme are dependent on the chosen utility functions. But the proposed two phases centralized QoS control scheme is general and is applicable to different utility functions. In the second phase, these configurations are used online by roadside AP adaptively according to dynamic traffic loads. The second part of the thesis is focused on distributed QoS control for DSRC networks. A framework of collaborative QoS control is proposed, following which we utilize the local channel busy time as the indicator of network congestion and adaptively adjust safety message rate by a modified additive increase and multiplicative decrease (AIMD) method in a distributed way. Numerical results demonstrate the effectiveness of the proposed QoS control schemes.
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Tay, Chee Bin, and Whye Kee Mui. "An architecture for network centric operations in unconventional crisis: lessons learnt from Singapore's SARS experience." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1303.
Full textAbstract:
Approved for public release, distribution is unlimitedSingapore and many parts of Asia were hit with Severe Acute Respiratory Syndrome (SARS) in March 2003. The spread of SARS lead to a rapidly deteriorating and chaotic situation. Because SARS was a new infection, there was no prior knowledge that could be referenced to tackle such a complex, unknown and rapidly changing problem. Fortunately, through sound measures coupled with good leadership, quick action and inter-agency cooperation, the situation was quickly brought under control. This thesis uses the SARS incident as a case study to identify a set of network centric warfare methodologies and technologies that can be leveraged to facilitate the understanding and management of complex and rapidly changing situations. The same set of methodologies and technologies can also be selectively reused and extended to handle other situations in asymmetric and unconventional warfare.
Office of Force Transformation, DoD US Future Systems Directorate, MINDEF Singapore.
Lieutenant, Republic of Singapore Army
Civilian, Defence Science and Technology Agency, Singapore
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Huth, Carsten [Verfasser]. "Groupware-basiertes Ad-hoc-Workflow-Management: das GroupProcess-System : Konzeption und prototypische Implementierung einer "Collaboration on Demand"-Lösung zur Unterstützung von schwach strukturierten Prozessen in Unternehmen / vorgelegt von Carsten Huth." 2004. http://d-nb.info/987729381/34.
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Lin, Shan-Rung, and 林姍蓉. "Collaborative Data Transmission in Vehicular Ad-Hoc Network." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/69867748002524434827.
Full textAbstract:
碩士國立東華大學
資訊工程學系
101
With the advances in wireless communications technology and affordable hardware, wireless networks have already crept into our daily lives such that people can use wireless communication devices (e.g. mobile phones, tablet PCs and notebook computers) to connect to the Roadside Unit (RSU) at any time and place. Through the network for uploading and downloading data, convenience is greatly improved. In recent years, VANETs (Vehicular Ad-Hoc Networks) issues have gained attention. Many major automobile companies (BMW, Ford, etc.) have extended the concept of accessibility anytime and anywhere to VANETs, so that users on the road can also upload or download information from the Internet through wireless devices in the vehicle unit. In VANETs, the fast moving of vehicle results in topology changes and connection path break between the vehicle and the vehicle. Although the set up of RSUs can alleviate this problem, the installation and maintenance cost is very high. Furthermore, if only a small number of RSUs are built, this may result in a communication range not covering the entire road, Therefore, reducing expenses while lengthening communication time is substantial challenge. In this paper, we apply roadside parking cars and propose collaborative data transmission to solve this problem.
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Huang, Albert. "Ad-hoc Collaborative Document Annotation on a Tablet PC." 2003. http://hdl.handle.net/1721.1/3847.
Full textAbstract:
The use of technology as an effective educational tool has been an elusive goal in the past. Specifically, previous attempts at using small personal computers in the classroom to aid students as collaborative and note-taking tools have been met with lukewarm responses. Many of these past attempts were hampered by inferior hardware and the lack of an efficient and user-friendly interface. With the recent introduction of Tablet PC products on the market, however, the limitations imposed on software developers for mobile computing systems have been dramatically lowered. We present a collaborative annotation system that allows students equipped with tablet computers to work cooperatively in either an ad-hoc or a structured wireless classroom setting.Singapore-MIT Alliance (SMA)
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Hsu, Wei-Lun, and 徐偉倫. "A Collaborative and Distributed Mechanism for Secure Routing in Mobile Ad-Hoc Networks." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/34587621575084596581.
Full textAbstract:
碩士國立交通大學
電信工程系所
93
The routing algorithm for the mobile ad-hoc networks enables the ad-hoc networks to use hop-by-hop transmission. This type of the transmission depends on the trust between nodes. If attackers inside the network attempt to fail the routing, it always leads to a lot of damage in the mobile ad-hoc networks routing. Therefore, a mechanism, called “Trust Evaluation Based Security Solution in Ad Hoc Networks [7]”, is proposed. Its idea is that nodes in the network can turn down the transmission request for untrustworthy nodes. This method cooperates with the source routing for implementing the secure routing. In this way, the trusty path is decided by means of “Trust Evaluation Based Security Solution in Ad Hoc Networks” and then the source chooses the transmission path. If the node which is responsible for transmission can be ensured to be trusty in this method, the secure routing can be completed. However, it is not objective for the source to decide the transmission path. Thus, we propose a distributed mechanism for the secure routing. This mechanism divides a long path into many short paths and in each short path there is a node responsible for choosing the path. By this way, each node only needs to monitor nodes in the region and then the accuracy for trust evaluation can be raised. Besides, the security among the wireless network has to rely on several secure mechanisms and our mechanism proposed in this paper can easily cooperate with other protocols.
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Chien, Cheng-Chieh, and 簡正傑. "Improving Data Transmission for Collaborative Work Using Forwarding Nodes in Mobile Ad Hoc Environments." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/38425350043712922317.
Full textAbstract:
碩士國立成功大學
電腦與通信工程研究所
95
Mobile users are often involved in team activities and exhibit collaborative mobility in realistic ad-hoc network application scenarios. Due to diverse group mobility patterns, the network can remain partitioned for extended durations. This thesis describes an approach to reduce the communication disruptions by deploying forwarding nodes. The forwarding nodes explore periodically in order to gather network information for countering the influence from mobility and sparseness of node deployment. By selecting the rendezvous grids pair, the forwarding nodes can move to appropriate locations to recover communication. The mechanism has been implemented in the network simulator ns-2. The simulation results show that the mechanism can efficiently improve information availability and achieve the required communication quality.
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Yeh, Sheng-Wei, and 葉昇韋. "Simulation and Analysis of Collaborative Localization mechanism based on Distance Estimation between Nodes in Wireless Ad Hoc Networks." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/49976747161705826668.
Full textAbstract:
碩士國立臺北教育大學
資訊科學系碩士班
101
In recent years, the mobile device and wireless ad hoc network technique have been well developed. In addition, the applications of location technique also become mature. Therefore, under the wireless ad hoc network with enormous nodes, utilizing the received signal strength (RSS) between some fixed reference nodes and the collaborative localization mechanism to find the location of blind nodes is a popular issue in research. Regarding the related works, the algorithm which depends on the received signal strength indicator (RSSI) is the most intuitive way and doesn’t need to cooperate with other hardware devices. However, the accuracy of RSSI would be greatly affected by the outside interference. Besides, owing to the enormous number of nodes in massive ad hoc network, it is complicated to obtain the related parameters and datum which are required for simulation. In this thesis, the distance between any two nodes is estimated by utilizing RSSI and related distance model. And a collaborative localization mechanism is proposed. In this mechanism, a blind node’s location can be calculated by estimating the distance between more than three reference nodes and then using multilateration technique. Under the scenario that the distance between any two nodes is less than 150m, the simulation results demonstrate that the deviation distance between the practical location and the location obtained from proposed method can improve to be less than 6.09 meters.
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Buchanan, Kristopher Ryan. "A Study Of Aperiodic (Random) Arrays of Various Geometries." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9415.
Full textAbstract:
The use of wireless communication techniques and network centric topologies for portable communication networks and platforms makes it important to investigate new distributed beamforming techniques. Platforms such as micro air vehicles (MAVs), unattended ground sensors (UGSs), and unpiloted aerial vehicles (UAVs) can all benefit from advances in this area by enabling advantages in stealth, enhanced survivability, and maximum maneuverability. Collaborative beamforming is an example of a new technique to utilize these systems which uses a randomly distributed antenna array with a fitting phase coefficient for the elements. In this example, the radiated signal power of each element is coherently added in the far-field region of a specified target direction with net destructive interference occurring in all other regions to suppress sidelobe behavior.
A wide variety of topologies can be used to confine geometrically these mobile random arrays for analysis. The distribution function for these topologies must be able to generalize the randomness within the geometry. Gaussian and Uniform distributions are investigated in this analysis, since they provide a way to calculate the statistically averaged beampattern for linear, planar (square and circular), and volumetric (cubical, cylindrical, and spherical) geometries. They are also of practical interest since the impact of array topology on the beampattern can typically be described in closed form. A rigorous analysis is presented first for disc-shaped topologies to motivate the discussion on random array properties and provide several new insights into their behavior. The analyses of volumetric geometries which are of interest to this work are drawn from this planar topology to provide a tractable and coherent discussion on the properties of more complex geometries. This analysis considers Normal and Gaussian distributed array element populations to derive the average beampattern, sidelobe behavior, beamwidth, and directivity. The beampattern is also examined in a similar manor for circular and spherical arrays with a truncated Gaussian distribution. A summary of the random array analysis and its results concludes this thesis.
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Dao, Thanh-Son. "A Decentralized Approach to Dynamic Collaborative Driving Coordination." Thesis, 2008. http://hdl.handle.net/10012/3927.
Full textAbstract:
This thesis presents a novel approach to several problems in
intelligent transportation systems using collaborative driving
coordination. With inter-vehicle communication and intelligent
vehicle cooperation, important tasks in transportation such as lane
position determination, lane assignment and platoon formation can be
solved. Several topics in regard to inter-vehicle communication,
lane positioning, lane assignment and platoon formation are explored
in this thesis:
First, the design and experimental results of low-cost lane-level
positioning system that can support a large number of transportation
applications are discussed. Using a Markov-based approach based on
sharing information among a group of vehicles that are traveling
within the communication range of each other, the lane positions of
vehicles can be determined. The robustness effectiveness of the
system is shown in both simulations and real road tests.
Second, a decentralized approach to lane scheduling for vehicles
with an aim to increase traffic throughput while ensuring the
vehicles exit successfully at their destinations is presented. Most
of current traffic management systems do not consider lane
organization of vehicles and only regulate traffic flows by
controlling traffic signals or ramp meters. However, traffic
throughput and efficient use of highways can be increased by
coordinating driver behaviors intelligently. The lane optimization
problem is formulated as a linear programming problem that can be
solved using the Simplex method.
Finally, a direction for cooperative vehicle platoon formation is
proposed. To enhance traffic safety, increase lane capacities and
reduce fuel consumption, vehicles can be organized into platoons
with the objective of maximizing the travel distance that platoons
stay intact. Toward this end, this work evaluates a proposed
strategy which assigns vehicles to platoons by solving an
optimization problem. A linear model for assigning vehicles to
appropriate platoons when they enter the highway is formulated.
Simulation results demonstrate that lane capacity can be increased
effectively when platooning operation is used.