Dissertationen: „Communication modeling“

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Spampinato, Daniele. „Modeling Communication on Multi-GPU Systems“. Thesis, Norwegian University of Science and Technology, Department of Computer and Information Science, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9068.

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Coupling commodity CPUs and modern GPUs give you heterogeneous systems that are cheap, high-performance with incredible FLOPS counts. Recent evolution of GPGPU models and technologies make these systems even more appealing as compute devices for a range of HPC applications including image processing, seismic processing and other physical modeling, as well as linear programming applications. In fact, graphics vendor such as NVIDIA and AMD are now targeting HPC with some of their products. Due to the power and frequency walls, the trend is now to use multiple GPUs on a given system, much like you will find multiple cores on CPU-based systems. However, increasing the hierarchy of resource wides the spectrum of factors that may impact on the performance of the system. The lack of good models for GPU-based, heterogeneous systems also makes it harder to understand which factors impact performance the most. The goal of this thesis is to analyze such factors by investigating and benchmarking NVIDIA's multi-GPU solution, their recent NVIDIA Tesla S1070 Computing System. This system combines four T10 GPUs making available up to 4 TFLOPS of computational power. Based on a comparative study of fundamental parallel computing models and on the specific heterogeneous features exposed by the system, we define a test space for performance analysis. As a case study, we develop a red-black, SOR PDE solver for Laplace equations with Dirichlet boundaries, well known for requiring constant communication in order to exchange neighboring data. To aid both design and analysis, we propose a model for multi-GPU systems targeting communication between the several GPUs. The main variables exposed by the benchmark application are: domain size and shape, kind of data partitioning, number of GPUs, width of the borders to exchange, kernels to use, and kind of synchronization between the GPU contexts. Among other results, the framework is able to point out the most critical bounds of the S1070 system when dealing with applications like the one in our case study. We show that the multi-GPU system greatly benefits from using all its four GPUs on very large data volumes. Our results show the four GPUs almost four times faster than a single GPU, and twice as fast as two. Our analysis outcomes also allow us to refine our static communication model, enriching it with regression-based predictions.

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Dani, Janak. „Transmission distortion modeling for wireless video communication“. Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5845.

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Thesis (M.S.)--University of Missouri-Columbia, 2005.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 22, 2007) Includes bibliographical references.

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Liu, Tuo. „Analytical modeling of HSUPA-enabled UMTS networks for capacity planning“. Connect to full text, 2008. http://ses.library.usyd.edu.au/handle/2123/4055.

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Thesis (Ph. D.)--University of Sydney, 2009.
Title from title screen (viewed February 20, 2009). Includes graphs and tables. Includes list of publications co-authored with others. Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Information Technologies, Faculty of Engineering and Information Technologies. Degree awarded 2009; thesis submitted 2008. Includes bibliographical references. Also available in print form.

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Leong, Sang-Yick. „Channel modeling, estimation and equalization in wireless communication“. Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4183.

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Thesis (Ph. D.)--University of Missouri-Columbia, 2005.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 25, 2006) Vita. Includes bibliographical references.

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Malafaia, Frederico Rafael Teixeira. „Modeling high bitrate communication interfaces with MatLab®“. Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14543.

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Mestrado em Engenharia Electrónica e Telecomunicações
Now-a-days, high-speed digital data transmission is under continuous development. The constant increasing on the bitrates has been lead to the need of more sophisticated and complex receivers, systems that provide the recovering of the transmitted data over a dispersive channel that degrades the transmitted signal quality. Therefore, the receiver shall compensate the distortion introduced by the channel as well as synchronize the received signal that in addition to distortion, is also affected by jitter. The distortion derived from the channel is attenuated by means of equalization circuits that offset the channel frequency response at the transmission rate, making it as flat as possible for the desired frequency. On the other hand, the synchronization of the received signal is achieved by means of clock and data recovery circuits that usually recover the clock signal through the data transitions for sampling the received data. The main focus of this thesis concerns the modeling of a data receiver for a high-speed interface. The simulation of the data receiver block implies the modeling of a transmission channel depending on its characteristics. The proposed transmission system, from the transmitter to the output of the data recovery block, includes equalization filters for signal conditioning, of which several distinct architectures are studied. It’s proposed two architectures for the clock and data recovery circuit. The first one is a 2x oversampling clock and data recovery circuit based on a Phase Tracking architecture. The second one, is a 3x oversampling clock and data recovery based on a Blind Sampling architecture. By modeling both of the architectures of the clock and data recovery circuit, it’s intended to analyze the respective jitter tolerance results. It is crucial to know the amount of jitter that can be tolerated by these circuits in order to recover the data with a satisfying bit error ratio. The obtained results show a very close match to the theoretical values, where the 2x and 3x oversampling architecture presents a jitter tolerance of, approximately, 12UI and 23UI respectively for low jitter frequencies.
Hoje em dia, a transmissão de dados digital de alto débito binário encontra-se em constante evolução. O contínuo aumento das taxas de transmissão tem vindo a exigir sistemas de receção cada vez mais sofisticados e complexos, que facultem a recuperação dos dados transmitidos ao longo de um canal dispersivo que degrada a qualidade do sinal transmitido. Consequentemente, cabe ao recetor compensar a distorção introduzida pelo canal bem como a sincronização do sinal recebido que, para além de sofrer distorção, vem também afetado por jitter. A distorção introduzida pelo canal é atenuada através de circuitos de igualização, que compensam a resposta em frequência do canal à frequência de transmissão, de maneira a tornar a mesma o mais plana possível para a frequência desejada. Por sua vez, a sincronização do sinal recebido é conseguida através de circuitos de recuperação de dados e relógio, que, geralmente, geram um sinal de relógio a partir das transições do sinal de dados que é posteriormente utilizado para fazer a amostragem dos dados recebidos. O principal foco desta tese incide na modelação de um sistema de receção de dados de uma interface de alta velocidade. A simulação do bloco de receção de dados implica a modelação de um canal de transmissão em função das características do mesmo. O sistema de transmissão proposto, desde o transmissor até à saída do bloco de recuperação de dados, inclui filtros de igualização para acondicionamento de sinal, dos quais várias arquiteturas distintas são estudadas. São propostas duas arquiteturas para o circuito de recuperação de dados e relógio. A primeira trata-se de um circuito de recuperação de dados e relógio com sobre-amostragem 2x, baseado numa arquitetura de Phase Tracking. A segunda arquitetura trata-se de um circuito de recuperação de dados e relógio com sobre-amostragem 3x, baseado num arquitetura Blind Sampling. A análise de resultados da modelação de ambas as arquiteturas do circuito de recuperação de dados e relógio é realizada através da aquisição das respetivas curvas de tolerância de jitter. É fundamental conhecer a quantidade de jitter tolerado por estes circuitos a fim de recuperar os dados com uma probabilidade de erro de bit satisfatória. Os resultados obtidos mostram uma correspondência bastante próxima dos valores teóricos, onde a arquitetura com sobre-amostragem 2x apresenta uma tolerância de jitter de, aproximadamente, 12UI e a arquitetura com sobre-amostragem 3x apresenta uma tolerância de, aproximadamente, 23UI para baixas frequências de jitter.

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Noel, Adam. „Modeling and analysis of diffusive molecular communication systems“. Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54906.

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Diffusive molecular communication (MC) is a promising strategy for the transfer of information in synthetic networks at the nanoscale. If such devices could communicate, then it would expand their cumulative capacity and potentially enable applications such as cooperative diagnostics in medicine, bottom-up fabrication in manufacturing, and sensitive environmental monitoring. Diffusion-based MC relies on the random motion of information molecules due to collisions with other molecules. This dissertation presents a novel system model for three-dimensional diffusive MC where molecules can also be carried by steady uniform flow or participate in chemical reactions. The expected channel impulse response due to a point source of molecules is derived and its statistics are studied. The mutual information between consecutive observations at the receiver is also derived. A simulation framework that accommodates the details of the system model is introduced. A joint estimation problem is formulated for the underlying system model parameters. The Cramer-Rao lower bound on the variance of estimation error is derived. Maximum likelihood estimation is considered and shown to be better than the Cramer-Rao lower bound when it is biased. Peak-based estimators are proposed for the low-complexity estimation of any single channel parameter. Optimal and suboptimal receiver design is considered for detecting the transmission of ON/OFF keying impulses. Optimal joint detection provides a bound on detector performance. The weighted sum detector is proposed as a suboptimal alternative that is more physically realizable. The performance of a weighted sum detector can become comparable to that of the optimal detector when the environment has a mechanism to reduce intersymbol interference. A model for noise sources that continuously release molecules is studied. The time-varying and asymptotic impact of such sources is derived. The model for asymptotic noise is used to approximate the impact of multiuser interference and also the impact of older bits of intersymbol interference.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

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Zajic, Alenka. „Space-time channel modeling, simulation, and coding“. Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26569.

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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Stuber,Gordon L.; Committee Member: Durgin, Gregory D.; Committee Member: Kim, Hyesoon; Committee Member: Li, Ye (Geoffrey); Committee Member: McLaughlin, Steven W.; Committee Member: Riley, George F.. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Dong, Lu. „MIMO Selection and Modeling Evaluations for Indoor Wireless Environments“. Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19767.

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Array-to-array, or multiple-input multiple-output (MIMO), links are known to provide extremely high spectral efficiencies in rich multipath environments, such as indoor wireless environments. The selection of a subset of receiver array antennas for a MIMO wireless link has been studied by many as a way to reduce cost and complexity in a MIMO system while providing diversity gain. Combined with a switched multi-beam beamformer, it becomes the beam selection system that can gain high signal-to-interference ratio (SIR) improvement in an interference-imited environment. The objective of this research is to evaluate the performance of low-complexity antenna or beam subset selection methods for small MIMO networks. The types of networks include (1) point-to-point MIMO links with out-of-system interference, (2)multi-user networks with a single, but possibly spatially distributed access point. We evaluate various selection techniques on measured indoor channels, which has not been done before. We propose a new practical selection metric, the peak-to-trough ratio of orthogonal frequency division multiplexing (OFDM) training symbols. We also compare antenna and beam selection on measured indoor channels under more general conditions than has previously been done. Finally, we consider some channel modeling issues associated with beamformers. We investigate the validity of three types of statistical MIMO channel models. A new beamformer is designed based on the ideal of the ``Weichselberger model.'

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Feng, Guangchao. „Indexing versus modeling intercoder reliability“. HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1452.

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10

Khalil, Hassan. „Stochastic Modeling for Wireless Communication Networks – Multiple Access Methods“. Thesis, Uppsala University, Department of Mathematics, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122031.

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11

Tam, Doan Thi Hong. „Collaboration-Oriented Modeling of an Offshore Group Communication System“. Thesis, KTH, Kommunikationssystem, CoS, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91501.

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This thesis studies the SPACE method by creating building blocks for a Push to Talk (PTT)service in WLAN environment. The structure and behavior of a PTT service is analyzed anddiscussed. We have modeled the behavior of a PTT service with the GUI of the PTT client.As a result, several of building blocks for a PTT service have been proposed. They can bestored in a library for a later reuse. We consider that the SPACE method well suited fordeveloping a PTT service.
Denna avhandling studerar SPACE metoden genom att skapa byggstenar för en PTT-tjänst iWLAN miljö. Struktur och beteende för en PTT-tjänst analyseras och diskuteras. Vi harutformat en model för beteendet av en PTT-tjänst med GUI av PTT klient. Som ett resultathar flera byggstenar för en PTT-tjänst föreslagits. Vi anser att SPACE metoden är väl lämpadför att utveckla ett PTT-tjänst.

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Doan-Thi-Hong, Tam. „Collaboration-Oriented Modeling Of An Offshore Group Communication System“. Thesis, Norwegian University of Science and Technology, Department of Telematics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9926.

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This thesis studies the SPACE method by creating building blocks for a Push to Talk (PTT) service in WLAN environment. The structure and behavior of a PTT service is analyzed and discussed. We have modeled the behavior of a PTT service with the GUI of the PTT client. As a result, several of building blocks for a PTT service have been proposed. They can be stored in a library for a later reuse. We consider that the SPACE method well suited for developing a PTT service.

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13

Meempat, Gopalakrishnan. „Modeling and adaptive resource management in integrated communication networks“. Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184843.

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The focus of this dissertation is the development of resource management schemes for integrated networks, with the major contributions being: (i) the development of an optimal adaptive buffer management scheme for the packet-switched subsystem, (ii) the integration of a moveable-boundary hybrid switching scheme with the time assigned speech interpolation technique for implementing a congestion control mechanism for the packet-switched subsystem, and (iii) the development of an adaptive hierarchical scheme for implementing the access control and routing functions within the circuit-switched subsystem. The problem of buffer management at an integrated network node is formulated as a nonlinear programming problem with a convex objective function and an interative solution technique with fast convergence is proposed for a real-time implementation of the buffer management scheme in practical environments. In order to exercise an additional degree of control over the packet-blocking probability at each hybrid-switched link within the network, a new multiplexing scheme based on the integration of the moveable-boundary hybrid switching scheme and the time assigned speech interpolation technique is presented in this dissertation. The tradeoff between the corresponding decrease in the packet blocking probability and the increase in the circuit freezeout fraction is demonstrated by a detailed queueing analysis of the multiplexer. Specific algorithms are also presented in this dissertation for the solution of the access control and routing problems within the circuit-switched subsystem. In particular, an access control scheme is developed by solving an integer programming problem formulated using the policy of complete partitioning of the available bandwidth among the competing user classes. As an alternative to the completely partitioned approach, the problem of traffic routing is considered in a network that supports homogeneous traffic classes based on the policy of complete sharing. Finally, for the general case of networks with heterogeneous traffic classes, a hierarchical scheme is developed for the implementation of the access control and the routing functions at two functional levels, where the access control is implemented by the network supervisor who solves an appropriate linear integer programming problem periodically, and the routing function is handled by the individual nodes of the network on a distributed basis. (Abstract shortened with permission of author.)

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FERNANDES, MARCUS VINICIUS DOS SANTOS. „MODELING OF DIGITAL COMMUNICATION CHANNELS UNDER BURST OF ERRORS“. PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=32818@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
INSTITUTO DE PESQUISA E DESENVOLVIMENTO
PROGRAMA DE EXCELENCIA ACADEMICA
A ocorrência de erros em surto é observada principalmente em canais sem fio. Para a análise e melhor entendimento deste tipo de erro, a fim de se melhorar os projetos de sistemas de comunicações digitais, uma modelagem mais precisa, de canais com esta característica, torna-se necessária. Uma diversidade de métodos de estimação de parâmetros tem sido estudada, principalmente aquelas baseadas nos Modelos Escondidos de Markov (HMM do ingês). Em geral cada método é focado em um sistema de comunicações específico, sobre uma camada específica. Neste trabalho é proposto um novo método baseado em um HMM com uma estrutura particular, que permite a dedução de expressões analíticas para todas as estatísticas de interesse. A estrutura do modelo proposto permite a geração de eventos que ocorrem numa sequência binária de dados sujeita a surtos de erro, de acordo com a definição de surtos de erro do CCITT. O modelo proposto possui um número fixo de apenas sete parâmetros, mas o seu número de estados cresce com um de seus parâmetros, que aumenta a precisão, mas não a complexidade. Este trabalho adotou técnicas de otimização, associadas aos métodos de Máxima Verossimilhança e Particle Swarm Optimization (PSO) a fim de realizar a estimação dos parâmetros do modelo proposto. Os resultados demonstram que o modelo proposto permite a caracterização precisa de canais com memória de diversas origens.
The occurrence of error busts is mainly observed in wireless channels. For analysis and a better understanding of such errors, in order to improve the design of communication systems, an accurate modeling of channels with this characteristic is necessary. A lot of parameter estimation methods have been studied, mainly the ones based on Hidden Markov Models (HMM). In general each method is focused in a specific communication system, on a specific layer. In this work it is proposed a new method based on a HMM with particular structure that allows the deduction of analytical expressions for all statistics of interest. The structure of the proposed model permits the generation of events that occur in a binary data sequence subject to bursts of error concerning CCITT error burst definition. The proposed model has a fixed number of only seven parameters but its number of states increase with one of those parameters that increase the accuracy but not the complexity. This work adopted techniques of optimization associated to Maximum Likelihood (ML) and Particle Swarm Optimization (PSO) to perform the parameter estimation to the proposed model. The results show that the proposed model achieves accurate characterization of channels with memory from many different sources.

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Carreno, Josua Daniel Pena. „Channel modeling for through-the-earth (TTE) communication systems“. reponame:Repositório Institucional da UnB, 2016. http://repositorio.unb.br/handle/10482/20092.

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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2016.
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Este trabalho apresenta modelagem de canal em ambientes de comunicação TTE a partir de modelos analíticos estabelecidos, medidas e simulações eletromagnéticas. Para estes cenários, apresenta-se como contribuição original os resultados estatísticos tanto para a condutividade elétrica efetiva quanto para a atenuação sofrida pelo campo magnético durante a propagação. Os resultados de simulação obtidos aqui, além de confirmarem o comportamento do canal empírico, extrapolam para frequências não estudadas via ferramentas estatísticas.
This dissertation presents channel modeling in TTE communication environments from well-established analytic models, measurements and electromagnetic simulations. For those scenarios, the main original contribution are the statistical results for the effective electric conductivity as well as the attenuation experimented by magnetic field while propagating Through-The-Earth. The simulation results present here, in addition to confirming the behavior of empirical models, extrapolate to frequencies not studied via statistical tools.

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Lima, Ferrer de Almeida André. „Tensor modeling and signal processing for wireless communication systems“. Nice, 2007. http://www.theses.fr/2007NICE4056.

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Dans plusieurs applications de traitement du signal pour les systèmes de communication sans fils, le signal reçu est de nature multidimensionnelle et possède une structure algébrique multilinéaire. Dans ce contexte, la décomposition tensorielle de type PARAFAC a fait l’objet de plusieurs travaux au cours des six dernières années. Il s’avère que des décompositions tensorielles plus générales sont nécessaires pour couvrir des classes plus larges de systèmes de communication faisant intervenir à la fois des modèles de transmission et de canal plus complexes et des méthodes de traitement plus efficaces. Cette thèse traite les problèmes de modélisation des systèmes multi-antennes, d’égalisation de canal, de séparation de signaux et d’estimation paramétrique de canal à l’aide d’approches tensorielles. Dans un premier temps, de nouvelles décompositions tensorielles (bloc-PARAFAC avec contraintes et CONFAC) ont été développées et étudiées en termes d’identifiabilité. Dans un deuxième temps, la décomposition bloc-PARAFAC avec contraintes a été appliquée tout d’abord pour mettre en évidence une modélisation tensorielle unifiée des systèmes suréchantillonnés, DS-CDMA et OFDM, avec application à l’égalisation multiutilisateur. Puis, cette décomposition a été utilisée pour modéliser des systèmes de transmission MIMO avec étalement spatio-temporel et détection aveugle. La décomposition CONFAC a ensuite été exploitée pour concevoir un nouveau schéma de transmission MIMO/CDMA combinant diversité et multiplexage spatial. Les propriétés d’unicité de cette décomposition ont permis de réaliser un traitement aveugle au niveau du récepteur pour la reconstruction du canal et des symboles transmis. Un troisième volet du travail concerne l’application de la décomposition PARAFAC pour la conception de nouveaux schémas de transmission spatio-temporel-fréquentiel pour des systèmes MIMO multiporteurs, et pour l’estimation paramétrique de canaux multitrajets
In several signal processing applications for wireless communications, the received signal is multidimensional in nature and may exhibit a multilinear algebraic structure. In this context, the PARAFAC tensor decomposition has been the subject of several works in the past six years. However, generalized tensor decompositions are necessary for covering a wider class of wireless communications systems with more complex transmission structures, more realistic channel models and more efficient receiver signal processing. This thesis investigates tensor modelling approaches for multiple-antenna systems, channel equalization, signal separation and parametric channel estimation? New tensor decompositions, namely, the block-constrained PARAFAC and CONFAC decompositions are developed and studied in terms of identifiability. Fist, the block-constrained PARAFAC decompositions applied for a unified tensor modelling of oversampled, DS-CDMA and OFDM systems applications to blind multiuser equalization. This decomposition is also used for modelling multiple-antenna (MIMO) transmission systems with block space-time spreading and blind detection, which generalizes previous tensor-based MIMO transmission models. The CONFAC decomposition is then exploited for designing new uniqueness properties of this decomposition? This thesis also studies new applications f third-order PARAFAC decomposition? A new space-time-frequency spreading system is proposed for multicarrier multiple-access systems, where this decomposition is used as a joint spreading and multiplexing tool at the transmitter using tridimensional spreading code with trilinear structure. Finally, we present a PARAC modelling approach for the parametric estimation of SIMO and MIMO multipath wireless channels with time-varying structure

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Rahman, Md Mizanur. „Modeling of compact antennas for wireless communication in complex environment“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ62523.pdf.

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Nåbo, Henning. „Automatic modeling and analysis of corporate communication through multiple mediums“. Thesis, Linköpings universitet, Programvara och system, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-152886.

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This thesis describes the process of modeling and analysis of corporate communication through chat and telephone with data taken from the Briteback enterprise communication application. Phone communication is measured by the number and duration of calls, and chat communication by the minimum number of messages sent from one person to another. The measurements are used to calculate a communication score, different methods are tested and a version using principal component analysis is chosen. Different centrality measurements are performed on the graph model that and each tested measure is found to be useful in some way; eigenvector centrality fits the data best, PageRank is easy to understand and can be adapted for dirfferent situations, and betweenness centrality points out users in critical positions in the communication graphs. Personalized PageRank ’focused’ on users or a group of users is tested and shows potential to be of use for social network service companies in many different ways such as when ordering search results or when suggesting new members to a chat channel.

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Quan, Chuanwen. „Integrated Modeling of Air Traffic, Aviation Weather, and Communication Systems“. Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27629.

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Aviation suffers many delays due to the lack of timely air traffic flow management. These delays are also caused by the uncertainty weather information; and the lack of efficient dissemination of weather products to pilots. It is clear that better models are needed to quantify air traffic flow in three flight regions - en-route, in the terminal, and on the ground, to determine aviation weather information requirements at each region, and to quantify their bandwidth requirements. Furthermore, the results from those models can be used to select alternative future aviation communication systems. In this research, the 'ITHINK' and 'MATLAB' software packages have been used to develop a lumped Air Traffic Flow Model (ATFM) and an Aviation Weather Information and Bandwidth Requirements Model (AWINBRM). The ATFM model is used to quantify the volume of air traffic in each phase of flight in three flight regions. This model can be used to study navigation, surveillance, and communication requirements. The AWINBRM model is used to study aviation weather information requirements in different flight phases of flight. Existing and potential communication systems used for transmitting aviation weather information are explored in this research. Finally, a usable and practical computer model - Aircraft Impacted and Detour Model (AIDM) around an aviation weather system is developed. This model is used to compare the costs between detoured flights around a weather system and delayed flights at the airports. The purpose of this research is to study air traffic flow and aviation weather information and bandwidth requirements through modeling. The ultimate goal of the models described here is to serve as a living laboratory where policies can be tried before implementing them into the real system. Moreover, these computer models can evolve dynamically through time allowing decision makers to exercise policies at various points in time to quantify results with ease. This research would be a first integrated model for combing air traffic flow and aviation weather requirements and determining the quantity of aviation weather information between pilot and ground service centers. This research would be a guideline for aviation industry to build an efficient and timely aviation weather information transmission system with minimum budget. Consequently, this research will reduce aviation delays and improve aviation safety.
Ph. D.

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Barritt, Brian James. „The Modeling, Simulation, and Operational Control of Aerospace Communication Networks“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1499348546519051.

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Wang, Zhiyuan. „Communication Modeling with Face-to-face Contacts-A Theoretical Perspective-“. 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142199.

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22

Case, Steven V. „Performance Modeling of Asynchronous Real-time Communication Within Bluetooth Networks“. NSUWorks, 2003. http://nsuworks.nova.edu/gscis_etd/446.

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This research provides an advance in the application of wireless, ad hoc networks to the domain of distributed, real-time applications. Traditionally, wireless communications are not deployed within real-time systems, the attributes of wireless protocols tend to run counter to the temporal requirements of real-time systems. When wireless protocols have been used in real-time systems, the application tends to be limited to systems for which there exists a priori knowledge of the network structure or the network communication. This research provides a model (or methodology) for evaluating the extent by which Bluetooth supports deterministic communication, thus allowing system engineers the ability to validate Bluetooth's ability to support real-time deadlines within software applications based on asynchronous communication. This research consisted primarily of an evaluation of the applicability of Bluetooth protocols to asynchronous real-time communication. The research methodology consisted of three distinct stages of research and development. The first stage of the study comprised the development of an analytical model describing the expected behavior of Bluetooth's ACL transmissions and the ability of ACL data packets to meet real-time deadlines. During the second stage of the study, the focus turned to the implementation of the Bluetooth HCI and L2CAP protocol layers. This implementation served as a test harness to gather actual performance data using commercial Bluetooth radios. The final stage of the study consisted of a comparative analysis of the predicted behavior established during the first stage of the study and the actual behavior experienced using the Bluetooth implementation from the second stage of the study. The analysis demonstrates the effectiveness of the model (from the first stage) by measuring the model's ability to accurately predict a piconet's ability to meet real-time deadlines for asynchronous communication when measured at the HCI-L2CAP protocol layer boundary.

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23

Phillips, Donovan D. „Mathematical modeling and optimal control of battlefield information flow“. Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://handle.dtic.mil/100.2/ADA483492.

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Dissertation (Ph.D. in Applied Mathematics)--Naval Postgraduate School, June 2008.
Dissertation Advisor(s): Kang, Wei ; Lin, Kyle. "June 2008." Description based on title screen as viewed on August 26, 2008. Includes bibliographical references (p.141-143). Also available in print.

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Patel, Chirag S. „Wireless channel modeling, simulation, and estimation“. Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-03282006-200818/.

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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006.
Andrew, Alfred, Committee Member ; Durgin, Gregory, Committee Member ; Li, Geoffrey, Committee Member ; Ingram, Mary Ann, Committee Member ; Stuber, Gordon, Committee Chair.

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Peters, Nia S. „Collaborative Communication Interruption Management System (C-CIMS): Modeling Interruption Timings via Prosodic and Topic Modelling for Human-Machine Teams“. Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1100.

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Human-machine teaming aims to meld human cognitive strengths and the unique capabilities of smart machines to create intelligent teams adaptive to rapidly changing circumstances. One major contributor to the problem of human-machine teaming is a lack of communication skills on the part of the machine. The primary objective of this research is focused on a machine’s interruption timings or when a machine should share and communicate information with human teammates within human-machine teaming interactions. Previous work addresses interruption timings from the perspective of single human, multitasking and multiple human, single task interactions. The primary aim of this dissertation is to augment this area by approaching the same problem from the perspective of a multiple human, multitasking interaction. The proposed machine is the Collaborative Communication Interruption Management System (C-CIMS) which is tasked with leveraging speech information from a human-human task and making inferences on when to interrupt with information related to an orthogonal human-machine task. This study and previous literature both suggest monitoring task boundaries and engagement as candidate moments of interruptibility within multiple human, multitasking interactions. The goal then becomes designing an intermediate step between human teammate communication and points of interruptibility within these interactions. The proposed intermediate step is the mapping of low-level speech information such as prosodic and lexical information onto higher constructs indicative of interruptibility. C-CIMS is composed of a Task Boundary Prosody Model, a Task Boundary Topic Model, and finally a Task Engagement Topic Model. Each of these components are evaluated separately in terms of how they perform within two different simulated human-machine teaming scenarios and the speed vs. accuracy tradeoffs as well as other limitations of each module. Overall the Task Boundary Prosody Model is tractable within a real-time system because of the low-latency in processing prosodic information, but is less accurate at predicting task boundaries even within human-machine interactions with simple dialogue. Conversely, the Task Boundary and Task Engagement Topic Models do well inferring task boundaries and engagement respectively, but are intractable in a real-time system because of the bottleneck in producing automatic speech recognition transcriptions to make interruption decisions. The overall contribution of this work is a novel approach to predicting interruptibility within human-machine teams by modeling higher constructs indicative of interruptibility using low-level speech information.

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Hodis, Georgeta M. „A longitudinal latent growth modeling perspective on communication apprehension, self-perceived communication competence, and willingness to communicate /“. Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1791777581&sid=5&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2009.
"Department of Speech Communication." Keywords: Communication apprehension, Latent growth modeling, Self-perceived communication competence, Willingness to communicate, Communication competence. Includes bibliographical references (p. 209-230). Also available online.

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Hodis, Georgeta Mioara. „A longitudinal latent growth modeling perspective on communication apprehension, self-perceived communication competence, and willingness to communicate“. OpenSIUC, 2009. https://opensiuc.lib.siu.edu/dissertations/302.

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This dissertation proposed and operationalized a theoretically meaningful and practically useful conceptualization of change for three well known communication constructs, namely willingness to communicate (WTC), self-perceived communication competence (SPCC), and communication apprehension (CA). Specifically, this research found that students' WTC and SPCC scores increased linearly during the semester and their CA scores decreased linearly. In addition, results from this dissertation indicated that for all three constructs considerable differences among students existed with respect to both initial levels and subsequent change in levels. These results are important and can advance the theoretical communication research centered around these constructs. In particular, knowledge that the hypothesis of linear change in the constructs received support from empirical data and that variations in students' trajectories of change were recorded, can prompt communication scholars to search for novel theoretical frameworks that can explicate these change processes. Moreover, the findings of this research are also salient for classroom instruction. Specifically, teachers of introductory communication classes can use the results of this study as broad benchmarks that can inform realistic expectations with respect to students' improvement in WTC, SPCC, and/or CA. In addition, this dissertation presented the benefits derived from properly conceptualizing and studying change by means of latent growth modeling, a powerful and versatile data analytic technique. Specifically, employing this methodology offered the opportunity to get detailed information about how changes in one construct are related to changes in the other two constructs and to gain a more in-depth knowledge of the intricate ways in which interlinkages among the constructs change across time. The benefits of this dynamic way to study WTC, SPCC, and CA are readily apparent as it facilitates teachers access to information that can be used to tailoring their activity for a more targeted, efficient, and beneficial instruction.

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Seidl, Cameron. „Modeling and Simulation of an RF Doppler Correction System“. University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo152536539799893.

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Khan, Noor Muhammad Electrical Engineering &amp Telecommunications Faculty of Engineering UNSW. „Modeling and characterization of multipath fading channels in cellular mobile communication systems“. Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/26999.

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Due to the enormous capacity and performance gains associated with the use of antenna arrays in wireless multi-input multi-output (MIMO) communication links, it is inevitable that these technologies will become an integral part of future systems. In order to assess the potential of such beam-oriented technologies, direct representation of the dispersion of multipath fading channel in angular and temporal domains is required. This representation can only be achieved with the use of spatial channel models. This thesis thus focuses on the issue of spatial channel modeling for cellular systems and on its use in the characteri- zation of multipath fading channels. The results of this thesis are presented mainly in five parts: a) modeling of scattering mechanisms, b) derivation of the closed-form expressions for the spatio-temporal characteristics, c) generalization of the quantitative measure of angular spread, d) investigation of the effect of mobile motion on the spatio-temporal characteris- tics, and e) characterization of fast fading channel and its use in the signature sequence adaptation for direct sequence code division multiple access (DS-CDMA) system. The thesis begins with an overview of the fundamentals of spatial channel modeling with regards to the specifics of cellular environments. Previous modeling approaches are dis- cussed intensively and a generalized spatial channel model, the 'Eccentro-Scattering Model' is proposed. Using this model, closed-form mathematical expressions for the distributions of angle and time of multipath arrival are derived. These theoretical results for the picocell, microcell and macrocell environments, when compared with previous models and available measurements, are found to be realistic and generic. In macrocell environment, the model incorporates the effect of distant scattering structures in addition to the local ones. Since the angular spread is a key factor of the second order statistics of fading processes in wireless communications, the thesis proposes a novel generalized method of quantifying the angular spread of the multipath power distribution. The proposed method provides almost all parameters about the angular spread, which can be further used for calculating more accurate spatial correlations and other statistics of multipath fading channels. The degree of accuracy in such correlation calculations can lead to the computation of exact separation distances among array elements required for maximizing capacity in MIMO systems or diversity antennas. The proposed method is also helpful in finding the exact standard deviation of the truncated angular distributions and angular data acquired in measurement campaigns. This thesis also indicates the significance of the effects of angular distribution truncation on the angular spread. Due to the importance of angular spread in the fading statistics, it is proposed as the goodness-of-fit measure in measurement campaigns. In this regard, comparisons of some notable azimuthal models with the measurement results are shown. The effect of mobile motion on the spatial and temporal characteristics of the channel is also discussed. Three mobile motion scenarios are presented, which can be considered to be responsible for the variations of the spatio-temporal statistical parameters of the multipath signals. Two different cases are also identified, when the terrain and clutter of the mobile surroundings have an additional effect on the temporal spread of the channel during mobile motion. The effect of increasing mobile-base separation on the angular and temporal spreads is elaborated in detail. The proposed theoretical results in spatial characteristics can be extended to characterizing and tracking transient behavior of Doppler spread in time-varying fast fading channels; likewise the proposed theoretical results in temporal characteristics can be utilized in designing efficient equalizers for combating inter-symbol interference (ISI) in time-varying frequency-selective fading channels. In the last part of the thesis, a linear state-space model is developed for signature sequence adaptation over time-varying fast fading channels in DS-CDMA systems. A decision directed adaptive algorithm, based on the proposed state-space model and Kalman filter, is presented. The algorithm outperforms the gradient-based algorithms in tracking the received distorted signature sequence over time-varying fast fading channels. Simulation results are presented which show that the performance of a linear adaptive receiver can be improved significantly with signature tracking on high Doppler spreads in DS-CDMA systems.

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Gaugel, Tristan [Verfasser], und H. [Akademischer Betreuer] Hartenstein. „Multiscale Modeling of Inter-Vehicle Communication / Tristan Gaugel. Betreuer: H. Hartenstein“. Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1093559284/34.

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31

Shao, Yongliang. „Object-based, distributed online real-time communication system modeling and development“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0017/MQ52661.pdf.

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32

Horner, Douglas. „A data-driven framework for rapid modeling of wireless communication channels“. Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/38947.

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Approved for public release; distribution is unlimited.
Accurate estimation and prediction of wireless signal strength holds the promise to improve a wide variety of applications in network-ing and unmanned systems. Current estimation approaches use either simplistic attenuation equations or detailed physical models that provide limited accuracy and may require a lengthy period of environmental assessment and computation. This dissertation presents a new, data-driven, stochastic framework for rapidly building accurate wireless connectivity maps. The framework advances the state of the art in three aspects. First, it augments the classic spatial interpolation procedure known as Kriging with a complementary additive approach to capture the typical anisotropic nature of wireless channels in cluttered environments. Second, it includes a technique for rapidly creating and maintaining a connectivity map in near real-time through the use of a spatial Bayesian recursive filter. Third, it introduces a novel methodology to adapt the resolution of a connectivity map based on the spatial characteristics and the quantity of available sample measurements. Detailed analyses, using several datasets collected recently in the Monterey Harbor, have confirmed the power and agility of the proposed approach.

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Tsui, Kenneth Kin Pun. „RF characterization and modeling of MOSFET power amplifier in wireless communication /“. View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202003%20TSUI.

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34

Hollis, Timothy M. „Circuit and modeling solutions for high-speed chip-to-chip communication /“. Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1721.pdf.

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Hollis, Timothy Mowry. „Circuit and Modeling Solutions for High-Speed Chip-to-Chip Communication“. BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1067.

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This dissertation presents methods for modeling and mitigating voltage noise and timing jitter across high-speed chip-to-chip interconnects. Channel equalization and associated tuning schemes have been developed to target the distinct characteristics and signal degradation exhibited in the clock and data signals of multi-Gigabit/second digital communication links. Multiple methods for generating realistically degraded signals for the purpose of simulation are also presented and used to verify the proposed equalization and filtering topologies. Specifically, a new technique for modeling high-speed jittery clocks in the frequency domain is presented and shown to reduce transient simulation time and memory requirements, while simultaneously improving the timing resolution and accuracy of the simulation by minimizing the dependence on the transient simulation time-step. The technique is further developed to provide unprecedented control over the timing characteristics of the generated signals, and is then extended to the generation of random data signals with definable jitter statistics. Through these techniques,realistic clock and data waveforms are constructible, providing for the visualization of the combined effects of voltage and timing degradation, while at the same time tracking the phase relationship between the clock and data signals as they pass across their respective channels and through the receiving circuitry of the communication link. New methods for the automated tuning of second-order continuous-time channel equalizers are proposed based on the simulated or measured single pulse and double pulse responses of the transmission channel. Using only one degree of freedom, the methods target the reduction of inter-symbol interference (ISI) as identified in the single and double pulses. Through tuning either the circuit quality factor (Q), the peaking frequency, or the frequency zero, the methods are shown to adapt to a variety of channel lengths and datarates from the same original equalizer transfer function, implying a good degree of generality, while offering a simple, yet effective, method for ISI reduction. Finally, the design of an active 5 Gigahertz (GHz) bandpass filter, employed for high-speed clock conditioning, is presented and shown to address both random and deterministic components of the clock signal degradation. The bandpass transfer function is achieved through a combination of AC coupling and a resonant LC tank consisting of on-chip interleaved spiral inductors and a tunable capacitor array. Through adjusting the load capacitance in parallel with the inductors, the center frequency of the filter is tunable over a range of nearly 5GHz. The design targets a supply voltage of 1.2 volts and draws approximately 5.7 milliamps of current.

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Wu, Yali. „A Domain Specific Modeling Approach for Coordinating User-Centric Communication Services“. FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/465.

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Rapid advances in electronic communication devices and technologies have resulted in a shift in the way communication applications are being developed. These new development strategies provide abstract views of the underlying communication technologies and lead to the so-called user-centric communication applications. One user-centric communication (UCC) initiative is the Communication Virtual Machine (CVM) technology, which uses the Communication Modeling Language (CML) for modeling communication services and the CVM for realizing these services. In communication-intensive domains such as telemedicine and disaster management, there is an increasing need for user-centric communication applications that are domain-specific and that support the dynamic coordination of communication services commonly found in collaborative communication scenarios. However, UCC approaches like the CVM offer little support for the dynamic coordination of communication services resulting from inherent dependencies between individual steps of a collaboration task. Users either have to manually coordinate communication services, or reply on a process modeling technique to build customized solutions for services in a specific domain that are usually costly, rigidly defined and technology specific. This dissertation proposes a domain-specific modeling approach to address this problem by extending the CVM technology with communication-specific abstractions of workflow concepts commonly found in business processes. The extension involves (1) the definition of the Workflow Communication Modeling Language (WF-CML), a superset of CML, and (2) the extension of the functionality of CVM to process communication-specific workflows. The definition of WF-CML includes the metamodel and the dynamic semantics for control constructs and concurrency. We also extended the CVM prototype to handle the modeling and realization of WF-CML models. A comparative study of the proposed approach with other workflow environments validates the claimed benefits of WF-CML and CVM.

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Erturk, Mustafa Cenk. „Tiered Networks: Modeling, Resource and Interference Management“. Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4316.

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The wireless networks of the future are likely to be tiered, i.e., a heterogeneous mixture of overlaid networks that have different power, spectrum, hardware, coverage, mobility, complexity, and technology requirements. The focus of this dissertation is to improve the performance and increase the throughput of tiered networks with resource/interference management methods, node densification schemes, and transceiver designs; with their applications to advanced tiered network structures such as heterogeneous networks (i.e., picocells, femtocells, relay nodes, and distributed antenna systems), device-to-device (D2D) networks, and aeronautical communication networks (ACN). Over the last few decades, there has been an incredible increase in the demand for wireless services in various applications in the entire world. This increase leads to the emergence of a number of advanced wireless systems and networks whose common goal is to provide a very high data rate to countless users and applications. With the traditional macrocellular network architectures, it will be extremely challenging to meet such demand for high data rates in the upcoming years. Therefore, a mixture of different capability networks has started being built in a tiered manner. While the number and capabilities of networks are increasing to satisfy higher requirements; Modeling, managing, and maintaining the entire structure has become more challenging. The capacity of wireless networks has increased with various different advanced technologies/methodologies between 1950-2000 which can be summarized under three main titles: spectrum increase (x25), spectrum efficiency increase (x25), and network density (spectrum reuse) increase (x1600). It is vital to note that among different schemes, the most important gain is explored with increasing the reuse and adding more nodes/cells into the system, which will be the focus of this dissertation. Increasing the reuse by adding nodes into the network in an uncoordinated (irregular in terms of power, spectrum, hardware, coverage, mobility, complexity, and technology) manner brought up heterogeneity to the traditional wireless networks: multi-tier resource management problems in uncoordinated interference environments. In this study, we present novel resource/interference management methods, node densification schemes, and transceiver designs to improve the performance of tiered networks; and apply our methodologies to heterogeneous networks, D2D networks, and ACN. The focus and the contributions of this research involve the following perspectives: 1. Resource Management in Tiered Networks: Providing a fairness metric for tiered networks and developing spectrum allocation models for heterogeneous network structures. 2. Network Densification in Tiered Networks: Providing the signal to interference plus noise ratio (SINR) and transmit power distributions of D2D networks for network density selection criteria, and developing gateway scheduling algorithms for dense tiered networks. 3. Mobility in Tiered Networks: Investigation of mobility in a two-tier ACN, and providing novel transceiver structures for high data rate, high mobility ACN to mitigate the effect of Doppler.

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Babaei, Alireza. „Statistical interference modeling and coexistence strategies in cognitive wireless networks“. Fairfax, VA : George Mason University, 2009. http://hdl.handle.net/1920/4596.

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Thesis (Ph.D.)--George Mason University, 2009.
Vita: p. 83. Thesis director: Bijan Jabbari. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electrical and Computer Engineering. Title from PDF t.p. (viewed Oct. 12, 2009). Includes bibliographical references (p. 79-82). Also issued in print.

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Bradley, W. Scott. „Propagation modeling for land mobile satellite communications“. Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/74511.

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Satellite systems are being planned for two-way communication with mobile vehicles using UHF and L-band frequencies. Of special concern in the system design are the characteristics of propagation in suburban and rural areas where fading occurs due to multipath effects and vegetative shadowing. A review of the literature was performed to study these propagation impairments. Available experimental data are examined, compared, and summarized. Propagation through vegetation is studied in order to compare reported modeling efforts and to determine the parameter dependences of path loss. A simple deterministic path model is then presented to estimate vegetative path loss. An overall statistical model is also proposed to describe the signal level fading statistics. The statistical model is compared to data, and the deterministic path model is used to determine the mean of signal level distribution functions in the presence of shadowing.
Master of Science

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Qing, Li. „GIS Aided Radio Wave Propagation Modeling and Analysis“. Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/33287.

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The analysis of radio wave propagation is a crucial part in designing an efficient wireless communication system. The Geographic Information System (GIS) can be incorporated into this procedure because most of the factors in radio wave propagation are geographic features. In this research, a commercial wireless planning software is tested in a field driving test carried out in Montgomery County, VA. The performance of current wireless planning software is evaluated based on field measurement. The received signal strength data collected during this driving test are then analyzed in a GIS environment in a statistical approach. The effects of local geographic features are modeled in GIS by appropriate spatial analyses.
Master of Science

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Alparslan, Denizhan N. Sohraby Khosrow. „Modeling and analysis of generalized random mobility models for wireless ad hoc networks“. Diss., UMK access, 2005.

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Thesis (Ph. D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2005.
"A dissertation in telecommunication networking and computer networking." Advisor: Khosrow Sohraby. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed May 30, 2006. Includes bibliographical references (leaves 119-123). Online version of the print edition.

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Patel, Chirag S. „Channel modeling and estimation for mobile-to-mobile OFDM communications“. Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/13552.

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43

Erpek, Tugba. „Location-based propagation modeling for opportunistic spectrum access in wireless networks“. Fairfax, VA : George Mason University, 2007. http://hdl.handle.net/1920/2934.

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Thesis (M.S.)--George Mason University, 2007.
Title from PDF t.p. (viewed Jan. 17, 2008). Thesis director: Brian L. Mark Submitted in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering. Vita: p. 60. Includes bibliographical references (p. 58-59). Also available in print.

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Schmitz, Norbert [Verfasser]. „Dynamic Modeling of Communication Partners for Socially Interactive Humanoid Robots / Norbert Schmitz“. München : Verlag Dr. Hut, 2011. http://d-nb.info/1013526635/34.

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Irshad, Yasir. „On some continuous-time modeling and estimation problems for control and communication“. Doctoral thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-26129.

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The scope of the thesis is to estimate the parameters of continuous-time models used within control and communication from sampled data with high accuracy and in a computationally efficient way.In the thesis, continuous-time models of systems controlled in a networked environment, errors-in-variables systems, stochastic closed-loop systems, and wireless channels are considered. The parameters of a transfer function based model for the process in a networked control system are estimated by a covariance function based approach relying upon the second order statistical properties of input and output signals. Some other approaches for estimating the parameters of continuous-time models for processes in networked environments are also considered. The multiple input multiple output errors-in-variables problem is solved by means of a covariance matching algorithm. An analysis of a covariance matching method for single input single output errors-in-variables system identification is also presented. The parameters of continuous-time autoregressive exogenous models are estimated from closed-loop filtered data, where the controllers in the closed-loop are of proportional and proportional integral type, and where the closed-loop also contains a time-delay. A stochastic differential equation is derived for Jakes's wireless channel model, describing the dynamics of a scattered electric field with the moving receiver incorporating a Doppler shift.

The thesis consists of five main parts, where the first part is an introduction- Parts II-IV are based on the following articles:

Part II - Networked Control Systems

1. Y. Irshad, M. Mossberg and T. Söderström. System identification in a networkedenvironment using second order statistical properties.

A versionwithout all appendices is published as Y. Irshad, M. Mossberg and T. Söderström. System identification in a networked environment using second order statistical properties. Automatica, 49(2), pages 652–659, 2013.

Some preliminary results are also published as M. Mossberg, Y. Irshad and T. Söderström. A covariance function based approachto networked system identification. In Proc. 2nd IFAC Workshop on Distributed Estimation and Control in Networked Systems, pages 127–132, Annecy,France, September 13–14, 2010

2. Y. Irshad and M. Mossberg. Some parameters estimation methods applied tonetworked control systems.A journal submission is made. Some preliminary results are published as Y. Irshad and M. Mossberg. A comparison of estimation concepts applied to networked control systems. In Proc. 19th Int. Conf. on Systems, Signals andImage Processing, pages 120–123, Vienna, Austria, April 11–13, 2012.

Part III - Errors-in-variables Identification

3. Y. Irshad and M. Mossberg. Continuous-time covariance matching for MIMOEIV system identification. A journal submission is made.

4. T. Söderström, Y. Irshad, M. Mossberg and W. X. Zheng. On the accuracy of acovariance matching method for continuous-time EIV identification. Provisionally accepted for publication in Automatica.

Some preliminary results are published as T. Söderström, Y. Irshad, M. Mossberg, and W. X. Zheng. Accuracy analysis of a covariance matching method for continuous-time errors-in-variables system identification. In Proc. 16th IFAC Symp. System Identification, pages 1383–1388, Brussels, Belgium, July 11–13, 2012.

Part IV - Wireless Channel Modeling

5. Y. Irshad and M. Mossberg. Wireless channel modeling based on stochasticdifferential equations .Some results are published as M. Mossberg and Y. Irshad. A stochastic differential equation forwireless channelsbased on Jakes’s model with time-varying phases, In Proc. 13th IEEEDigitalSignal Processing Workshop, pages 602–605, Marco Island, FL, January4–7, 2009.

Part V - Closed-loop Identification

6. Y. Irshad and M. Mossberg. Closed-loop identification of P- and PI-controlledtime-delayed stochastic systems.Some results are published as M. Mossberg and Y. Irshad. Closed-loop identific ation of stochastic models from filtered data, In Proc. IEEE Multi-conference on Systems and Control,San Antonio, TX, September 3–5, 2008

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Fang, Ting-Kuo Sun Wei-Long. „Dataset simulation and RF path modeling of a QPSK radio communication system /“. Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FFang.pdf.

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Barbieri, Francesco. „Machine learning methods for understanding social media communication: modeling irony and emojis“. Doctoral thesis, Universitat Pompeu Fabra, 2018. http://hdl.handle.net/10803/461793.

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In this dissertation we propose algorithms for the analysis of social media texts, focusing on two particular aspects: irony and emojis. We propose novel automatic systems, based on machine learning methods, able to recognize and interpret these two phenomena. We also explore the problem of topic bias in sentiment analysis and irony detection, showing that traditional word based systems are not robust when they have to recognize irony on a new domain. We argue that our proposal is better suited for topic changes. We then use our approach to recognize another phenomena related to irony: satirical news in Twitter. By relying on distributional semantic models, we also introduce a novel method for the study of the meaning and use of emojis in social media texts. Moreover, we also propose an emoji prediction task that consists in predicting the emoji present in a text message using only the text. We have shown that this emoji prediction task can be performed by deep-learning systems with good accuracy, and that this accuracy can be improved by using images included in the post.
En esta tesis proponemos algoritmos para el análisis de textos de redes sociales, enfocándonos en dos aspectos particulares: el reconocimiento automático de la ironía y el análisis y predicción de emojis. Proponemos sistemas automáticos, basados en métodos de aprendizaje automático, capaces de reconocer e interpretar estos dos fenómenos. También exploramos el problema del sesgo en análisis del sentimiento y en la detección de la ironía, mostrando que los sistemas tradicionales, basados en palabras, no son robustos cuando los datos de entrenamiento y test pertenecen a dominios diferentes. El modelo que se propone en esta tesis para el reconocimiento de la ironía es más estable a los cambios de dominio que los sistemas basados en palabras. En una serie de experimentos demostramos que nuestro modelo es también capaz de distinguir entre noticias satíricas y no satíricas. Asimismo, exploramos con modelos semánticos distribucional, si y cómo el significado y el uso de emojis varía entre los idiomas, así como a través de las épocas del año. También nos preguntamos si es posible predecir el emoji que un mensaje contiene solo utilizando el texto del mensaje. Hemos demostrado que nuestro sistema basado en deep-learning es capaz de realizar esta tarea con buena precisión y que se pueden mejorar los resultados si además del texto se utiliza información sobre las imágenes que acompañan al texto.

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48

Parandehgheibi, Marzieh. „Modeling and mitigating cascading failures in interdependent power grids and communication networks“. Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105558.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 139-146).
Many of today's critical infrastructures are organized in the form of networks, which are dependent on one another. A particular example is the power grid and the communication network used to control the grid. While this dependence is beneficial during normal operation, as it allows for more efficient operation, it can be harmful when the networks are under stress. Indeed, in such interdependent network infrastructures, a cascade of failures may occur where power failures can lead to communication failures, which, in turn, lead to cascading power failures. Therefore, it is necessary to develop proper models and analytical tools to asses the robustness of interdependent networks to failures. In this thesis, we develop such models with emphasis on interdependent power grids and communication networks. Initially, we focus on the abstract modeling of interdependent networks. In particular, we propose a new model for interdependent networks with known topologies, define and analyze metrics for assessing the robustness of such networks to cascading failures, and propose algorithms for robust design of interdependent networks. Next, we focus on the interactions between power grids and communication and control networks. We model the cascading failures in the power grid using the power flow equations, and use the communication network to implement a control policy in the power grid which mitigates cascading failures in interdependent networks. Using this model, we show that the interdependent power grids are more robust than isolated ones. Finally, we model the impact of communication loss on the performance of power grids under two different control scenarios. The first one is the emergency control mechanism where failures in the power grid should be monitored and mitigated by the control center. In this case, we investigate the impact of simultaneous communication failures on the performance of such control mechanisms. In particular, we propose new emergency control schemes for partial communication networks, and investigate the network parameters that are most effective in causing the cascade of failures from communication networks to the power grid. The second control mechanism is distributed frequency control in power grids. We show that the optimal solution will not be achieved under communication link failures. We propose a novel control mechanism that uses the power dynamics instead of direct information from the communication network, and show that it achieves the optimal solution and is globally asymptotically stable. We also analyze the impact of discrete-time communication on the performance of distributed frequency control. We show that the convergence time increases as the time interval between two messages increases, and propose a new algorithm that uses the dynamics of the power grid to decrease the convergence time.
by Marzieh Parandehgheibi.
Ph. D.

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49

Candeago, Lorenzo. „Modeling human and cities' behaviors: from communication synchronization to spatio-temporal networks“. Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/267995.

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Recent years have seen a huge increase in the amount of data collected from multiple sources: mobile phones are ubiquitous, social networks are widely used, cities are more and more connected and the mobility of people and goods has risen to a global scale. The Big Data Era has opened the doors to new kinds of studies that were unthinkable with previous qualitative methods: human behavior can now be analyzed with a fine-grained resolution, patterns of mobility and behavior can be extracted from the incredible amount of data collected every day. Modern large cities are becoming more and more interconnected and this phenomenon leads to an increasing communication and activities’ synchronization. Due to the amount of data available or for anonymization reasons, it is often necessary to aggregate data spatially and temporally. A natural representation of clustered mobility data is the temporal network representation. In this thesis we focus on these two aspects of spatial distance in human mobility: (i) we study the synchronization of 76 Italian cities, using mobile phone data, showing that both distance between cities and city size determine the synchronization in communication rhythms. Moreover, we show that the effect of the distance in synchronization decreases when the size of the city increases; (ii) we investigate how clustering continuous spatio-temporal data affects spatio-temporal network measures for real-life and synthetic datasets and analyze how spatio-temporal networks’ measures vary at different aggregation levels.

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PARK, SANG-EON. „MODELING PARAMETERIZED MOBILE ACTIONS IN A WIRELESS PERSONAL COMMUNICATION SERVICE (PCS) NETWORK“. University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1027944662.

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Dissertationen zum Thema „Communication modeling“

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