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Efficient real-time video delivery in vehicular networksTorres Cortés, Álvaro 18 April 2016 (has links)
Tesis por compendio / [EN] Vehicular Ad-hoc Networks (VANET) are a special type of networks where the nodes involved in the communication are vehicles. VANETs are created when several vehicles connect among themselves without the use of any infrastructure. In certain situations the absence of infrastructure is an advantage, but it also creates several challenges that should be overcome.
One of the main problems related with the absence of infrastructure is the lack of a coordinator that can ensure a certain level of quality in order to enable the correct transmission of video and audio. Video transmission can be extremely useful in this type of networks as it can be used for videoconferencing of by traffic authorities to monitor the scene of an accident.
In this thesis we focused on real time video transmission, providing solutions for both unicast and multicast environments. Specifically, we built a real-world testbed scenario and made a comparison with simulation results to validate the behavior of the simulation models.
Using that testbed we implemented and improved DACME, an admission control module able to provide Quality of Service (QoS) to unicast video transmissions. DACME proved to be a valid solution to obtain a certain level of QoS in multi-hop environments.
Concerning multicast video transmission, we developed and simulated several flooding schemes, focusing specifically on VANET environments. In this scope, the main contribution of this thesis is the Automatic Copies Distance Based (ACDB) flooding scheme. Thanks to the use of the perceived vehicular density, ACDB is a zeroconf scheme able to achieve good video quality in both urban and highway environments, being specially effective in highway environments. / [ES] Las redes vehiculares ad-hoc (VANET) son un tipo especial de redes en las que los nodos que participan de la comunicación son vehículos. Las VANETs se crean cuando diversos vehículos se conectan entre ellos sin el uso de ninguna infraestructura. En determinadas situaciones, la ausencia de infraestructura es una ventaja, pero también crea una gran cantidad de desafíos que se deben superar.
Uno de los principales problemas relacionados con la ausencia de infraestructura, es la ausencia de un coordinador que pueda asegurar un determinado nivel de calidad, para poder asegurar la correcta transmisión de audio y vídeo. La transmisión de vídeo puede ser de extrema utilidad en este tipo de redes ya que puede ser empleada para videoconferencias o por las autoridades de tráfico para monitorizar el estado de un accidente.
En esta tesis nos centramos en la transmisión de vídeo en tiempo real, proveyendo soluciones tanto para entornos unicast como multicast. En particular construimos un banco de pruebas real y comparamos los resultados obtenidos con resultados obtenidos en un entorno simulado para comprobar la fiabilidad de estos modelos.
Usando el mismo banco de pruebas, implementamos y mejoramos DACME, un módulo de control de admisión capaz de proveer de calidad de servicio a transmisiones de vídeo unicast. DACME probó ser una solución válida para obtener ciertos niveles de calidad de servicio en entornos multisalto.
En lo referente a la transmisión de vídeo multicast, desarrollamos y simulamos diversos esquemas de difusión diseñados específicamente para entornos VANET. En este campo, la principal contribución de esta tesis es el esquema de difusión "Automatic Copies Distance Based" (ACDB). Gracias al uso de la densidad vehicular percibida, ACDB es un esquema, que sin necesidad de configuración, permite alcanzar una buena calidad de vídeo tanto en entornos urbanos como en autopistas, siendo especialmente efectivo en este último entorno. / [CA] Les xarxes vehiculars ad-hoc (VANET) son un tipus de xarxes especials a les que els diferents nodes que formen part d'una comunicació son vehicles. Les VANETs es formen quan diversos vehicles es connecten sense fer ús de cap infraestructura. A certes situacions l'absència d'una infraestructura suposa un avantatge, encara que també genera una gran quantitat de desafiaments que s'han de superar.
U dels principals problemes relacionats amb l'absència d'infraestructura, és la manca d'un coordinador que puga garantir una correcta transmissió tant de video com d'àudio. La transmissió de video pot ser d'extrema utilitat a aquest tipus de xarxes, ja que es por emprar tant per a videoconferències com per part de les autoritats de trànsit per monitoritzar l'estat d'un accident.
A aquesta tesi ens centrem en transmissió de video en temps real, proporcionant solucions tant a entorns unicast como a entorns multicast. Particularment, vam construir un banc de proves i obtinguérem resultats que comparàrem amb resultats obtinguts mitjançant simulació. D'aquesta manera validarem la fiabilitat dels resultats simulats.
Fent ús del mateix banc de proves, vàrem implementar i millorar DACME, un mòdul de control d'admissió, capaç de proveir de qualitat de servici a transmissions de video unicast. DACME va provar ser una bona solució per obtindré un bon nivell de qualitat de servici en entorns de xarxes ad-hoc amb diversos salts.
Si ens centrem a la transmissió de video multicast, vàrem implementar i simular diferents esquemes de difusió, específicament dissenyats per al seu ús a entorns VANET. La principal contribució d'aquesta tesi es l'esquema de difusió ACDB (Automatic Copies Distance Based). Fent ús de la densitat vehicular, ACDB es capaç d'obtindre una bona qualitat de video tant a ciutats com a vies interurbanes, sent a especialment efectiu a aquestes últimes. A més a més no es necessària cap configuració per part de l'usuari. / Torres Cortés, Á. (2016). Efficient real-time video delivery in vehicular networks [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62685 / Compendio
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Extens?es ao Projeto LVWNet: mobilidade, intera??o com equipamentos reais, comunica??o direta, e registro din?mico de n?s / Extensions of LVWNet project: mobility, interaction with real hardware, direct communication and dynamic registration of nodesOliveira, Leonardo Dantas de 05 June 2014 (has links)
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Previous issue date: 2014-06-05 / Due to the constantly increasing use of wireless networks in domestic, business and industrial
environments, new challenges have emerged. The prototyping of new protocols
in these environments is typically restricted to simulation environments, where there is
the need of double implementation, one in the simulation environment where an initial
proof of concept is performed and the other one in a real environment. Also, if real environments
are used, it is not trivial to create a testbed for high density wireless networks
given the need to use various real equipment as well as attenuators and power reducers
to try to reduce the physical space required to create these laboratories. In this context,
LVWNet (Linux Virtual Wireless Network) project was originally designed to create completely
virtual testbeds for IEEE 802.11 networks on the Linux operating system. This
paper aims to extend the current project LVWNet, adding to it the features like the ability
to interact with real wireless hardware, provides a initial mobility ability using the
positioning of the nodes in a space coordinates environment based on meters, with loss
calculations due to attenuation in free space, enables some scalability increase by creating
an own protocol that allows the communication between nodes without an intermediate
host and dynamic registration of nodes, allowing new nodes to be inserted into in already
in operation network / Com o crescimento constante da utiliza??o de redes sem fio em ambientes dom?sticos,
empresariais e at? industriais, aparecem novos desafios. A prototipa??o de novos protocolos
nesses ambientes tipicamente ? restrita a ambientes de simula??o, onde existe a
necessidade de uma dupla implementa??o, uma no ambiente de simula??o, onde se realiza
uma prova de conceito inicial e outra em um ambiente real. Al?m disso, uma vez que se
parta para ambientes reais, n?o ? trivial a cria??o de um testbed para redes sem fio de
alta densidade, dada a necessidade de uso de v?rios equipamentos reais, e uso de atenuadores,
redutores de pot?ncia, para tentar reduzir o espa?o f?sico necess?rio para cria??o
desses laborat?rios. Nessa lacuna, o projeto LVWNet (Linux Virtual Wireless Network)
foi inicialmente concebido para cria??o de testbeds completamente virtuais para redes
IEEE 802.11 sobre o sistema operacional Linux. Este trabalho tem como objetivo extender
o atual projeto LVWNet adicionando a ele os recursos de possibilitar a intera??o com
hardwares wireless reais, dar um suporte inicial ? mobilidade atrav?s do posicionamento
dos n?s em um ambiente de coordenadas no espa?o baseado em metros, j? com c?lculos de
perda decorrente da atenua??o em espa?o livre, aumentar a escalabilidade com a cria??o
de um mecanismo que permita a comunica??o direta entre os n?s sem necessidade de um
host intermedi?rio al?m do registro din?mico de n?s, de modo que novos n?s podem ser
inseridos na rede com a mesma j? em opera??o
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Unified Cognitive Radio : Architectural Analysis, Design and ImplementationBudihal, Ramachandra January 2015 (has links) (PDF)
This thesis addresses the problem of building a Cognitive Radio that has the ability to interact with human users in a better way by making use of Quality of Experience (QoE) as its basis and marshalling its resources optimally around the user. Salient activities of this thesis include:
Analysis of CR leads to the definition of its basic functional blocks such as cognition, learning and adaptation of radio behaviour in a multi-disciplinary manner. CR tracts signal processing for radio and sensors, cognitive and behavioural psychology for user intelligence, machine learning and AI for decision systems and optimization etc. Therefore it provides a rich, fertile area to make lateral connections across diverse helds. This thesis proposes a broad definition for CR (called as Unifed Cognitive Radio) inspired by key foundation works described in literature. Besides, it also describes its functionality and its ecosystem.
Taking cue from the definition of UCR, this thesis proposes architectural frame-works for various sub-systems. Also their design and implementation is achieved with the aid of a comprehensive tested setup and is tested using realistic scenarios.
Builds a set of intelligent decision systems that help to achieve the set goal. This involves various design decisions with a set of diverse algorithms from the world of signal processing, machine learning and articial intelligence.
Transitioning disparate small functional entities (mostly built around experiments) into an integrated system that works in real-world environment is the key aspect of this thesis. It is definitely a challenging task. Therefore, starting from deterring the architectural reference frameworks for realizing various sub-systems of UCR to an evaluation based on integrated scenario, this being an important final step constitutes a sign cant amount of work. Analysis and implementation of the integrated system to meet the desired end functionality - QoE centricity of the CR system to satisfy the needs of the end user better is the contribution of this thesis
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When Decision Meets Estimation: Theory and ApplicationsYang, Ming 15 December 2007 (has links)
In many practical problems, both decision and estimation are involved. This dissertation intends to study the relationship between decision and estimation in these problems, so that more accurate inference methods can be developed. Hybrid estimation is an important formulation that deals with state estimation and model structure identification simultaneously. Multiple-model (MM) methods are the most widelyused tool for hybrid estimation. A novel approach to predict the Internet end-to-end delay using MM methods is proposed. Based on preliminary analysis of the collected end-to-end delay data, we propose an off-line model set design procedure using vector quantization (VQ) and short-term time series analysis so that MM methods can be applied to predict on-line measurement data. Experimental results show that the proposed MM predictor outperforms two widely used adaptive filters in terms of prediction accuracy and robustness. Although hybrid estimation can identify model structure, it mainly focuses on the estimation part. When decision and estimation are of (nearly) equal importance, a joint solution is preferred. By noticing the resemblance, a new Bayes risk is generalized from those of decision and estimation, respectively. Based on this generalized Bayes risk, a novel, integrated solution to decision and estimation is introduced. Our study tries to give a more systematic view on the joint decision and estimation (JDE) problem, which we believe the work in various fields, such as target tracking, communications, time series modeling, will benefit greatly from. We apply this integrated Bayes solution to joint target tracking and classification, a very important topic in target inference, with simplified measurement models. The results of this new approach are compared with two conventional strategies. At last, a surveillance testbed is being built for such purposes as algorithm development and performance evaluation. We try to use the testbed to bridge the gap between theory and practice. In the dissertation, an overview as well as the architecture of the testbed is given and one case study is presented. The testbed is capable to serve the tasks with decision and/or estimation aspects, and is helpful for the development of the JDE algorithms.
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A Foundation For Educational Research at Scale: Evolution and ApplicationOstrow, Korinn S. 24 April 2018 (has links)
The complexities of how people learn have plagued researchers for centuries. A range of experimental and non-experimental methodologies have been used to isolate and implement positive interventions for students' cognitive, meta-cognitive, behavioral, and socio-emotional successes in learning. But the face of learning is changing in the digital age. The value of accrued knowledge, popular throughout the industrial age, is being overpowered by the value of curiosity and the ability to ask critical questions. Most students can access the largest free collection of human knowledge (and cat videos) with ease using their phones or laptops and omnipresent cellular and Wi-Fi networks. Viewing this new-age capacity for connection as an opportunity, educational stakeholders have delegated many traditional learning tasks to online environments. With this influx of online learning, student errors can be corrected with immediacy, student data is more prevalent and actionable, and teachers can intervene with efficiency and efficacy. As such, endeavors in educational data mining, learning analytics, and authentic educational research at scale have grown popular in recent years; fields afforded by the luxuries of technology and driven by the age-old goal of understanding how people learn. This dissertation explores the evolution and application of ASSISTments Research, an approach to authentic educational research at scale that leverages ASSISTments, a popular online learning platform, to better understand how people learn. Part I details the evolution and advocacy of two tools that form the research arm of ASSISTments: the ASSISTments TestBed and the Assessment of Learning Infrastructure (ALI). An NSF funded Data Infrastructure Building Blocks grant (#1724889, $494,644 2017-2020), outlines goals for the new age of ASSISTments Research as a result of lessons learned in recent years. Part II details a personal application of these research tools with a focus on the framework of Self Determination Theory. The primary facets of this theory, thought to positively affect learning and intrinsic motivation, are investigated in depth through randomized controlled trials targeting Autonomy, Belonging, and Competence. Finally, a synthesis chapter highlights important connections between Parts I & II, offering lessons learned regarding ASSISTments Research and suggesting additional guidance for its future development, while broadly defining contributions to the Learning Sciences community.
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An RF-Isolated Real-Time Multipath Testbed for Performance Analysis of WLANsMetreaud, Leon T 22 August 2006 (has links)
"Real-time performance evaluation of wireless local area networks (WLANs) is an extremely challenging topic. The major drawback of real-time performance analysis in actual network installations is a lack of repeatability due to uncontrollable interference and propagation complexities. These are caused by unpredictable variations in the interference scenarios and statistical behavior of the wireless propagation channel. This underscores the need for a Radio Frequency (RF) test platform that provides isolation from interfering sources while simulating a real-time wireless channel, thereby creating a realistic and controllable radio propagation test environment. Such an RF-isolated testbed is necessary to enable an empirical yet repeatable evaluation of the effects of the wireless channel on WLAN performance. In this thesis, a testbed is developed that enables real-time laboratory performance evaluation of WLANs. This testbed utilizes an RF-isolated test system, Azimuthâ„¢ Systems 801W, for isolation from external interfering sources such as cordless phones and microwave ovens and a real-time multipath channel simulator, Elektrobit PROPSimâ„¢ C8, for wireless channel emulation. A software protocol analyzer, WildPackets Airopeek NX, is used to capture data packets in the testbed from which statistical data characterizing performance such as data rate and Received Signal Strength (RSS) are collected. The relationship between the wireless channel and WLAN performance, under controlled propagation and interference conditions, is analyzed using this RF-isolated multipath testbed. Average throughput and instantaneous throughput variation of IEEE 802.11b and 802.11g WLANs operating in four different channels - a constant channel and IEEE 802.11 Task Group n (TGn) Channel Models A, B, and C - are examined. Practical models describing the average throughput as a function of the average received power and throughput variation as a function of the average throughput under different propagation conditions are presented. Comprehensive throughput models that incorporate throughput variation are proposed for the four channels using Weibull and Gaussian probability distributions. These models provide a means for realistic simulation of throughput for a specific channel at an average received power. Also proposed is a metric to describe the normalized throughput capacity of WLANs for comparative performance evaluation."
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A Testbed for Real-Time Performance Evaluation of RSS-based Indoor Geolocation Systems in Laboratory EnvironmentHeidari, Mohammad 04 May 2005 (has links)
Recently, there has been an enormous growth of interests in geolocation applications that demand an accurate estimation of the user’s location in indoor areas. The traditional geolocation system, GPS, which was designed for being used in outdoor environments, does not perform well in indoor areas, causing frequent inaccuracies in location estimation. Therefore the need for more accurate positioning systems and even positioning techniques is a motivation for researchers to turn their attention into indoor positioning systems. In this thesis we present a unique testbed for indoor geolocation system’s real-time performance evaluation. Then we present a real-time performance evaluation of a sample indoor positioning system. We make a comparison between the simulated results of the performance evaluation of the positioning engine and the real-time performance evaluation of the positioning system. Finally, we perform a sensitivity analysis for Ekahauâ„¢ indoor positioning engine. We show that the simulation with the introduced testbed yields the same results as one would obtain by evaluating the performance of the positioning system by means of massive measurement campaigns. Running the testbed for several measurement campaigns for different scenarios enabled us to compare the results and study the effect of selected parameters on the performance of the positioning system. We also perform primitive error analysis in terms of distance error to verify the validity of the result obtained with the testbed. We show that under the same configuration both real-time performance evaluation and simulated performance evaluation will yield same result with respect to position error. We also use error modeling to determine which error model is best matched to the observed indoor positioning error. Amongst all of the possibilities of choosing methods of positioning, we focused on the Received Signal Strength (RSS) based method along with fingerprinting. Briefly said, profiles previously gathered by measurement or simulation will decide on the location of mobile terminal if a new profile comes in. It is worth mentioning that previous work similar to this testbed has been done for outdoor areas according to Ekahau's white paper. Their work is mainly focused on outdoor environment, in which multipath does not exist. In this research effort we tried to analyze the effect of different parameters on sensitivity of indoor positioning systems who suffer from multipath. Different setups for simulating real-time radio channels have been studied in literature, but still not focused on indoor areas.
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Estudo experimental do aprovisionamento dinâmico de caminhos ópticos com capacidade de restauração considerando restrições na camada físicaSilva, Dener Edson Ottolini Guedes da January 2013 (has links)
Orientador: Gustavo Sousa Pavani / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciências da Computação, 2013
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Model-based Diagnosis of a Satellite Electrical Power System with RODONIsaksson, Olle January 2009 (has links)
<p>As space exploration vehicles travel deeper into space, their distance to earth increases.The increased communication delays and ground personnel costs motivatea migration of the vehicle health management into space. A way to achieve thisis to use a diagnosis system. A diagnosis system uses sensor readings to automaticallydetect faults and possibly locate the cause of it. The diagnosis system usedin this thesis is a model-based reasoning tool called RODON developed by UptimeSolutions AB. RODON uses information of both nominal and faulty behavior ofthe target system mathematically formulated in a model.The advanced diagnostics and prognostics testbed (ADAPT) developed at theNASA Ames Research Center provides a stepping stone between pure researchand deployment of diagnosis and prognosis systems in aerospace systems. Thehardware of the testbed is an electrical power system (EPS) that represents theEPS of a space exploration vehicle. ADAPT consists of a controlled and monitoredenvironment where faults can be injected into a system in a controlled manner andthe performance of the diagnosis system carefully monitored. The main goal of thethesis project was to build a model of the ADAPT EPS that was used to diagnosethe testbed and to generate decision trees (or trouble-shooting trees).The results from the diagnostic analysis were good and all injected faults thataffected the actual function of the EPS were detected. All sensor faults weredetected except faults in temperature sensors. A less detailed model would haveisolated the correct faulty component(s) in the experiments. However, the goal wasto create a detailed model that can detect more than the faults currently injectedinto ADAPT. The created model is stationary but a dynamic model would havebeen able to detect faults in temperature sensors.Based on the presented results, RODON is very well suited for stationary analysisof large systems with a mixture of continuous and discrete signals. It is possibleto get very good results using RODON but in turn it requires an equally goodmodel. A full analysis of the dynamic capabilities of RODON was never conductedin the thesis which is why no conclusions can be drawn for that case.</p><p> </p>
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CMOS analog spectrum processing techniques for cognitive radio applicationsPark, Jongmin 13 November 2009 (has links)
The objective of the research is to develop analog spectrum processing techniques for cognitive radio (CR) applications in CMOS technology. CR systems aim to use the unoccupied spectrum allocations without any license when the primary users are not present. Therefore, the successful deployment of CR systems relies on their ability to accurately sense the spectrum usage status over a wide frequency range serving various wireless communication standards. Meanwhile, to maximize the utilization of the available spectrum segments, the bandwidth of the signal has to be highly flexible, so that even a small fraction of spectrum resources can be fully utilized by CR users. One of the key enabling technologies of variable bandwidth communication is a tunable baseband filter.
In this research, a reconfigurable CR testbed system is presented as groundwork for the researches related with CR systems. With the feasibility study on the multi-resolution spectrum sensing (MRSS) functionality, a method for determining sensing threshold for MRSS functionality is presented, and a fully integrated MRSS receiver in CMOS technology is demonstrated. On the other hand, a reconfigurable CMOS analog baseband filter which can change its bandwidth, type and order with high resolution for CR applications is presented. In sum, an analog spectrum sensing method as well as a highly flexible analog baseband filter architecture is established and implemented in CMOS technology. Both designs are targeting the utilization of the analog signal processing capability with the aid of the digital circuits.
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