26 research outputs found
Recommended from our members
Dynamic wireless mobile framework for distributed collaborative real-time information generation and control systems
Intelligent Transportation Systems (ITS) have only recently discovered the exciting possibilities in the nomadic and ubiquitous computing space to build a new generation of information systems by allowing the vehicle to act both as a carrier and consumer of wireless (and thus omnipresent) information. Wide deployment of such ITS systems may eventually allow for more dynamic and efficient transportation systems, which can contribute in several ways towards greater economic growth whilst respecting environmental sustainability. A great number of researchers have dedicated considerable time and resources to tackling traffic related issues by utilising the new wireless capabilities enabled by ITS; such initiatives cover a wide range of applications such as safety, knowledge sharing and infotainment. Indicative of the extent of such efforts is the plethora of research projects initiated by many national and multi-national organisations such as the EU Framework Programme for Research and Technological Development. To achieve their goals, proposed solutions from such organisations depend on the development and deployment of intelligent wireless mobile communication systems, where data dissemination issues make the prospect of efficient and effective communication a challenging proposition. Presently, Car-to-Car and Car-to-Infrastructure communications are two distinct avenues that make possible efficient and reliable delivery of messages via direct radio links in traffic areas. In all cases, high quality of communication performance is desirable for a communication system composed mostly of roaming participants; such a system needs to be dynamic, flexible and infrastructure-less. Consequently, Mobile Ad hoc Network (MANET)-based networks are a natural fit to ITS
An investigation of mobile ad-hoc network performance with cognitive attributes applied
Mobile Ad-Hoc Networks (MANETs) are known for their versatility, which is they are capable of supporting many applications. In addition to this versatility MANETs are quick to deploy without need for an existing predefined communications infrastructure. However, although the lack of infrastructure allows for the quick deployment of the data communications network, it adds many factors that hinder packet delivery. Such hindrances occur because of the dynamic topology caused by the mobility of the nodes which results in link breakages. Routing protocols exist that attempt to refresh available routes; however, this is after link breakages have occurred. The nodes also usually have constrained resources (i.e. energy source and limited bandwidth).
This thesis presents a novel approach of network behaviour and management by implementing cognitive attributes into a MANET environment. This allows an application to better meet its mission objectives, decreases the end-to-end delay, and increases packet delivery ratio. The network is able to make observations, consider previous actions and consequences of the actions, and make changes based on the prior knowledge and experience. This work also shows how the network can better utilise limited resources such as bandwidth allocation by applying cognitive attributes.
Simulations conducted show promising results and prove that an increase in network performance is possible if adopting a cross-layered approach and allow the network to manage and to âthinkâ for itself. Various simulations were run with various scenarios and results are presented without cognition applied, with partial cognition applied and with full cognition applied. A total of 52 simulations were run and from this the results were compared and contrasted. The analysis shows that cognitive attributes does increase network performance in the majority of applications
Bandwidth reservation in mobile ad hoc networks for providing QoS : adaptation for voice support
Le support de qualitĂ© de service (QoS) dans les rĂ©seaux MANETs (Mobile Ad-Hoc NETworks) a attirĂ© une grande attention ces derniĂšres annĂ©es. Bien que beaucoup de travaux de recherche ont Ă©tĂ© consacrĂ© pour offrir la QoS dans les rĂ©seaux filaires et cellulaires, les solutions de QoS pour le support du trafic temps rĂ©el dans les MANET reste l'un des domaines de recherche les plus difficiles et les moins explorĂ©s. En fait, les applications temps rĂ©el telles que la voix et la vidĂ©o ne pourrait pas fonctionner correctement dans les MANET sans l'utilisation d'un protocole de contrĂŽle d'accĂšs au support (MAC) orientĂ© QoS. En effet, les trafics temps rĂ©el demandent des exigences strictes en termes de dĂ©lai de transmission et de taux de perte de paquets qui peuvent ĂȘtre remplies uniquement si la sous-couche MAC fournit un dĂ©lai d'accĂšs au canal bornĂ©, et un faible taux de collision.
Le but de cette thĂšse est la proposition et l'analyse d'un protocole MAC basĂ© sur la rĂ©servation pour garantir la QoS dans les MANETs. Tout d'abord, nous Ă©tudions un problĂšme majeur dans la rĂ©servation de ressources dans les MANETs qui est la cohĂ©rence des rĂ©servations. Notre analyse des protocoles de rĂ©servation existant pour les MANETs rĂ©vĂšle que de nombreux conflits de rĂ©servations entre les nĆuds voisins se produisent pendant la phase d'Ă©tablissement de rĂ©servation. Ces conflits, qui sont principalement dues Ă la collision des messages de contrĂŽle de rĂ©servation, ont un impact important sur les performances du protocole de rĂ©servation, et conduisent Ă un taux de collision et de perte de paquet importants pendant la durĂ©e de vie de la connexion, ce qui n'est pas acceptable pour les trafics temps rĂ©els. Nous proposons un nouveau protocole MAC basĂ© sur la rĂ©servation qui rĂ©sout ces conflits. Le principe de notre protocole est d'Ă©tablir une meilleure coordination entre les nĆuds voisins afin d'assurer la cohĂ©rence des rĂ©servations. Ainsi, avant de considĂ©rer qu'une rĂ©servation est rĂ©ussite, le protocole s'assure que chaque message de contrĂŽle envoyĂ© par un nĆud pour Ă©tablir une rĂ©servation est bien reçu par tous ses nĆuds voisins.
Dans la deuxiÚme partie de cette thÚse, nous appliquons le protocole de réservation proposé au trafic de type voix. Ainsi, nous étendons ce protocole afin de prendre en compte les caractéristiques du trafic voix, tout en permettant le transport de trafic de données. Nous nous focalisons sur l'utilisation efficace de la bande passante et les mécanismes pour réduire le gaspillage de bande passante.
La derniĂšre partie de cette thĂšse concerne l'extension du protocole proposĂ© en vue de rĂ©server la bande passante pour une connexion temps rĂ©el sur un chemin. Ainsi, le protocole MAC de rĂ©servation proposĂ© est couplĂ© avec un protocole de routage rĂ©actif. En outre, le protocole est Ă©tendu avec des mĂ©canismes de gestion de Ă mobilitĂ© afin de faire face Ă la dĂ©gradation des performances due Ă la mobilitĂ© des nĆuds.
Nous évaluons les performances du protocole proposé dans plusieurs scénarios dans lesquels nous montrons sa supériorité par rapport aux standards existants.QoS provisioning over Mobile Ad-Hoc Networks (MANETs) has attracted a great attention in recent years. While much research effort has been devoted to provide QoS over wired and cellular networks, QoS solutions for the support of real-time traffic over MANETs remains one of the most challenging and least explored areas. In fact, real-time applications such as voice and video could not function properly on MANETs without a QoS oriented medium access control (MAC) scheme. Indeed, real-time traffics claim strict requirements in terms of transmission delay and packet dropping that can be fulfilled only if the MAC sub-layer provides bounded channel access delay, and low collision rate.
The purpose of this thesis is the proposal and analysis of an efficient reservation MAC protocol to provide QoS support over MANETs. Firstly, we study one major issue in resource reservation for MANETs which is reservation consistency. Our analysis of existing reservation MAC protocols for MANETs reveals that many reservation conflicts between neighbor nodes occur during the reservation establishment phase. These conflicts which are mainly due to collisions of reservation control messages, have an important impact on the performance of the reservation protocol, and lead to a significant collision and loss of packets during the life-time of the connection, which is not acceptable for real-time traffics. We design a new reservation MAC protocol that resolves these conflicts. The main principle of our protocol is to achieve better coordination between neighbor nodes in order to ensure consistency of reservations. Thus, before considering a reservation as successful, the protocol tries to ensure that each reservation control message transmitted by a node is successfully received by all its neighbors.
In the second part of this thesis, we apply the proposed reservation protocol to voice traffic. Thus, we extend this protocol in order to take into account the characteristics of voice traffic, while enabling data traffic. We focus on efficient bandwidth utilization and mechanisms to reduce the waste of bandwidth.
The last part of this thesis relates to the extension of the proposed protocol in order to reserve resources for a real-time connection along a path. Thus, the proposed reservation MAC protocol is coupled with a reactive routing protocol. In addition, the protocol is extended with mobility handling mechanisms in order to cope with performance degradation due to mobility of nodes.
We evaluate the performance of the proposed scheme in several scenarios where we show its superiority compared to existing standards
H3N - Analysewerkzeuge fĂŒr hybride Wegewahl in heterogenen, unterbrechungstoleranten Ad-Hoc-Netzen fĂŒr RettungskrĂ€fte
RettungskrĂ€fte mĂŒssen unter widrigen Bedingungen zuverlĂ€ssig kommunizieren können, um in RettungseinsĂ€tzen effizient arbeiten zu können und somit Leben zu retten. Idealerweise ist dazu ein selbstorganisiertes Ad-Hoc-Netz notwendig, weil die Kommunikationsinfrastruktur ggf. beschĂ€digt oder ĂŒberlastet sein kann. Um die geforderte Robustheit der Kommunikation auch in Szenarien mit gröĂeren zu ĂŒberbrĂŒckenden Entfernungen zu gewĂ€hrleisten, werden zusĂ€tzlich Mechanismen benötigt, die eine Unterbrechungstoleranz ermöglichen. Verzögerungstolerante Netze (engl. Delay Tolerant Networks, kurz: DTN) stellen solche Mechanismen bereit, erfordern aber zusĂ€tzliche Verzögerungen, die fĂŒr Rettungskommunikation nachteilig sind. Deshalb werden intelligente hybride Wegewahlverfahren benötigt, um die Verzögerung durch DTN-Mechanismen zu begrenzen. AuĂerdem sollten entsprechende Verfahren heterogene Netze unterstĂŒtzen. Das ermöglicht zusĂ€tzlich eine effizientere Weiterleitung durch die Nutzung von GerĂ€ten mit unterschiedlichen Kommunikationstechnologien und damit auch Reichweiten. Um solche Systeme und die dafĂŒr benötigten Kommunikationsprotokolle zu entwickeln, werden verschiedene Analysewerkzeuge genutzt. Dazu gehören analytische Modelle, Simulationen und Experimente auf der Zielsystemhardware. FĂŒr jede Kategorie gibt es verschiedene Werkzeuge und Frameworks, die sich auf unterschiedliche Aspekte fokussieren. Dadurch unterstĂŒtzen diese herkömmlichen Analysemethoden jedoch meistens nur einen der oben genannten Punkte, wĂ€hrend die Untersuchung von hybriden und/oder heterogenen AnsĂ€tzen und Szenarien nicht ohne weiteres möglich ist. Im Falle von RettungskrĂ€ften kommt hinzu, dass die charakteristischen Merkmale hinsichtlich der Bewegung der Knoten und des erzeugten Datenverkehrs wĂ€hrend eines Einsatzes ebenfalls nicht modelliert werden können. In dieser Arbeit werden deshalb verschiedene Erweiterungen zu existierenden Analysewerkzeugen sowie neue Werkzeuge zur Analyse und Modelle zur Nachbildung realistischer Rettungsmissionen untersucht und entwickelt. Ziel ist es, die Vorteile existierender Werkzeuge miteinander zu kombinieren, um ganzheitliche, realitĂ€tsnahe Untersuchungen von hybriden Protokollen fĂŒr heterogene Netze zu ermöglichen. Die Kombination erfolgt in Form von gezielten Erweiterungen und der Entwicklung ergĂ€nzender komplementĂ€rer Werkzeuge unter Verwendung existierender Schnittstellen. Erste Ergebnisse unter Verwendung der entwickelten Werkzeuge zeigen Verbesserungspotentiale bei der Verwendung traditioneller Protokolle und erlauben die Bewertung zusĂ€tzlicher MaĂnahmen, um die Kommunikation zu verbessern. Szenarien zur Kommunikation von RettungskrĂ€ften werden dabei als ein Beispiel verwendet, die Tools sind jedoch nicht auf die Analyse dieses Anwendungsfalls beschrĂ€nkt. Ăber die reine Analyse verschiedener existierender AnsĂ€tze hinaus bildet die entwickelte Evaluationsumgebung eine Grundlage fĂŒr die Entwicklung und Verifikation von neuartigen hybriden Protokollen fĂŒr die entsprechenden Systeme.Communication between participating first responders is essential for efficient coordination of rescue missions and thus allowing to save human lives. Ideally, ad hoc-style communication networks are applied to this as the first responders cannot rely on infrastructure-based communication for two reasons. First, the infrastructure could be damaged by the disastrous event or not be available for economic reasons. Second, even if public infrastructure is available and functional, it might be overloaded by users. To guarantee the robustness and reliability requirements of first responders, the Mobile Ad Hoc Networks (MANETs) have to be combined with an approach to mitigate intermittent connectivity due to otherwise limited connectivity. Delay Tolerant Networks (DTNs) provide such a functionality but introduce additional delay which is problematic.
Therefore, intelligent hybrid routing approaches are required to limit the delay introduced by DTN mechanisms. Besides that, the approach should be applicable to heterogeneous networks in terms of communication technologies and device capabilities. This is required for cross multi-agency and volunteer communication but also enables the opportunistic exploitation of any given communication option.
To evaluate such systems and develop the corresponding communication protocols, various tools for the analysis are available. This includes analytical models, simulations and real-world experiments on target hardware. In each category a wide set of tools is available already. However, each tool is focused on specific aspects usually and thus does not provide methods to analyze hybrid approaches out of the box. Even if the tools are modular and allow an extension, there are often other tools that are better suited for partial aspects of hybrid systems.
In addition to this, few tools exist to model the characteristics of first responder networks. Especially the generalized movement during missions and the generated data traffic are difficult to model and integrate into analyses.
The focus of this project is therefore to develop selected extensions to existing analysis and simulation tools as well as additional tools and models to realistically capture the characteristics of first responder networks. The goal is to combine the advantages of existing specialized simulation tools to enable thorough evaluations of hybrid protocols for heterogeneous networks based on realistic assumptions. To achieve this, the tools are extended by specifically designing tools that enable the interaction between tools and new tools that complement the existing analysis capabilities. First results obtained via the resulting toolbox clearly indicate further research directions as well as a potential for protocol enhancements.
Besides that, the toolbox was used to evaluate various methods to enhance the connectivity between nodes in first responder networks.
First responder scenarios are used as an example here. The toolbox itself is however not limited to this use case.
In addition to the analysis of existing approaches for hybrid and heterogeneous networks, the developed toolbox provides a base framework for the development and verification of newly developed protocols for such use cases
Non-Hierarchical Networks for Censorship-Resistant Personal Communication.
The Internet promises widespread access to the worldâs collective information and fast communication among people, but common government censorship and spying undermines this potential. This censorship is facilitated by the Internetâs hierarchical structure. Most traffic flows through routers owned by a small number of ISPs, who can be secretly coerced into aiding such efforts. Traditional crypographic defenses are confusing to common users. This thesis advocates direct removal of the underlying heirarchical infrastructure instead, replacing it with non-hierarchical networks. These networks lack such chokepoints, instead requiring would-be censors to control a substantial fraction of the participating devicesâan expensive proposition. We take four steps towards the development of practical non-hierarchical networks. (1) We first describe Whisper, a non-hierarchical mobile ad hoc network (MANET) architecture for personal communication among friends and family
that resists censorship and surveillance. At its core are two novel techniques, an efficient routing scheme based on the predictability of human locations anda variant of onion-routing suitable for decentralized MANETs. (2) We describe the design and implementation of Shout, a MANET architecture for censorship-resistant, Twitter-like public microblogging. (3) We describe the Mason test, amethod used to detect Sybil attacks in ad hoc networks in which trusted authorities are not available. (4) We characterize and model the aggregate behavior of Twitter users to enable simulation-based study of systems like Shout. We use our characterization of the retweet graph to analyze a novel spammer detection technique for Shout.PhDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/107314/1/drbild_1.pd
A group-based architecture and protocol for wireless sensor networks
There are many works related to wireless sensor networks (WSNs) where
authors present new protocols with better or enhanced features, others just
compare their performance or present an application, but this work tries to provide
a different perspective. Why donÂżt we see the network as a whole and split it into
groups to give better network performance regardless of the routing protocol?
For this reason, in this thesis we demonstrate through simulations that
nodeÂżs grouping feature in WSN improves the networkÂżs behavior. We propose the
creation of a group-based architecture, where nodes have the same functionality
within the network. Each group has a head node, which defines the area in which
the nodes of such group are located. Each node has a unique node identifier
(nodeID). First groupÂżs node makes a group identifier (groupID).
New nodes will know their groupID and nodeID of their neighbors. End
nodes are, physically, the nodes that define a group. When there is an event on a
node, this event is sent to all nodes in its group in order to take an appropriate
action. End nodes have connections to other end nodes of neighboring groups and
they will be used to send data to other groups or to receive information from other
groups and to distribute it within their group. Links between end nodes of different
groups are established mainly depending on their position, but if there are multiple
possibilities, neighbor nodes could be selected based on their ability Âż, being Âż a
choice parameter taking into account several network and nodes parameters. In
order to set groupÂżs boundaries, we can consider two options, namely: i) limiting
the groupÂżs diameter of a maximum number of hops, and ii) establishing
boundaries of covered area.
In order to improve the proposed group-based architecture, we add
collaboration between groups. A collaborative group-based network gives better
performance to the group and to the whole system, thereby avoiding unnecessary
message forwarding and additional overheads while saving energy. Grouping
nodes also diminishes the average network delay while allowing scaling the
network considerably. In order to offer an optimized monitoring process, and in
order to offer the best reply in particular environments, group-based collaborative
systems are needed. They will simplify the monitoring needs while offering direct
control.
Finally, we propose a marine application where a variant of this groupbased architecture could be applied and deployed.GarcĂa Pineda, M. (2013). A group-based architecture and protocol for wireless sensor networks [Tesis doctoral]. Universitat PolitĂšcnica de ValĂšncia. https://doi.org/10.4995/Thesis/10251/27599TESISPremios Extraordinarios de tesis doctorale
Unified Role Assignment Framework For Wireless Sensor Networks
Wireless sensor networks are made possible by the continuing improvements in embedded sensor, VLSI, and wireless radio technologies. Currently, one of the important challenges in sensor networks is the design of a systematic network management framework that allows localized and collaborative resource control uniformly across all application services such as sensing, monitoring, tracking, data aggregation, and routing.
The research in wireless sensor networks is currently oriented toward a cross-layer network abstraction that supports appropriate fine or course grained resource controls for energy efficiency. In that regard, we have designed a unified role-based service paradigm for wireless sensor networks. We pursue this by first developing a Role-based Hierarchical Self-Organization (RBSHO) protocol that organizes a connected dominating set (CDS) of nodes called dominators. This is done by hierarchically selecting nodes that possess cumulatively high energy, connectivity, and sensing capabilities in their local neighborhood. The RBHSO protocol then assigns specific tasks such as sensing, coordination, and routing to appropriate dominators that end up playing a certain role in the network.
Roles, though abstract and implicit, expose role-specific resource controls by way of role assignment and scheduling. Based on this concept, we have designed a Unified Role-Assignment Framework (URAF) to model application services as roles played by local in-network sensor nodes with sensor capabilities used as rules for role identification. The URAF abstracts domain specific role attributes by three models: the role energy model, the role execution time model, and the role service utility model. The framework then generalizes resource management for services by providing abstractions for controlling the composition of a service in terms of roles, its assignment, reassignment, and scheduling. To the best of our knowledge, a generic role-based framework that provides a simple and unified network management solution for wireless sensor networks has not been proposed previously
Model-based provisioning and management of adaptive distributed communication in mobile cooperative systems
Adaptation of communication is required to maintain the reliable connection and to ensure the minimum quality in collaborative activities. Within the framework of wireless environment, how can host entities be handled in the event of a sudden unexpected change in communication and reliable sources? This challenging issue is addressed in the context of Emergency rescue system carried out by mobile devices and robots during calamities or disaster. For this kind of scenario, this book proposes an adaptive middleware to support reconfigurable, reliable group communications. Here, the system structure has been viewed at two different states, a control center with high processing power and uninterrupted energy level is responsible for global task and entities like autonomous robots and firemen owning smart devices act locally in the mission. Adaptation at control center is handled by semantic modeling whereas at local entities, it is managed by a software module called communication agent (CA). Modeling follows the well-known SWRL instructions which establish the degree of importance of each communication link or component. Providing generic and scalable solutions for automated self-configuration is driven by rule-based reconfiguration policies. To perform dynamically in changing environment, a trigger mechanism should force this model to take an adaptive action in order to accomplish a certain task, for example, the group chosen in the beginning of a mission need not be the same one during the whole mission. Local entity adaptive mechanisms are handled by CA that manages internal service APIs to configure, set up, and monitors communication services and manages the internal resources to satisfy telecom service requirements
Advances in Reinforcement Learning
Reinforcement Learning (RL) is a very dynamic area in terms of theory and application. This book brings together many different aspects of the current research on several fields associated to RL which has been growing rapidly, producing a wide variety of learning algorithms for different applications. Based on 24 Chapters, it covers a very broad variety of topics in RL and their application in autonomous systems. A set of chapters in this book provide a general overview of RL while other chapters focus mostly on the applications of RL paradigms: Game Theory, Multi-Agent Theory, Robotic, Networking Technologies, Vehicular Navigation, Medicine and Industrial Logistic