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1
Perup, Daniel. "VITA 49 Radio DF : Using coherent digital receiver set with VC++ and Octave". Thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-20015.
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The objective of this thesis was to evaluate radio receivers that had been previously acquired for other tasks by the Swedish Defence Materiel Administration, for additional service in a radio direction finding (DF) system. The antenna, calibration signal generator and DF algorithm were provided. As the receivers used the VITA 49 frame format, much of the work involved the interpretation of the frame structure and contents. The other main challenges were to put the receivers into the correct internal state, to compensate the analogue phase errors due to cabling, and to correlate the digital frames according to the time stamps. The work was performed partly as a literature study and, during implementation, by using an investigative trial and-error method. Collection of reference signals, for later offline analysis, was made at the Swedish Defence Research Agency. The findings of the evaluation was that the receivers were phase coherent and that the VITA 49 frame format was suitable for DF use. An apparently systematic error of unknown origin rendered the DF results inaccurate, even though the precision of the results was high. The automatic gain control (AGC) of the receivers did not perform according to norm. If the systematic error is compensated for, and the AGC problem is eliminated, the receivers will function as a DF system using the manufacturer's instructions, with the provided antenna. The performance of the receivers in this setting was not a primary concern for the thesis, but was deemed to be acceptable. Suggestions for further development include finding the source of the systematic error, an automatic calibration function, a more thorough performance analysis, and code optimizations using multiple threads.
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Sun, Wei-Long. "Data set simulation and RF path modeling of a QPSK radio communication system". Thesis, Monterey, California. Naval Postgraduate School, 2005. http://hdl.handle.net/10945/2112.
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This project simulates QPSK modulation signals and uses a laboratory environment to create deteriorating effects of real-world high frequency (HF) transmissions that may modify the ideal QPSK waveform. These modifications may be identifiable in order to "fingerprint" the source of the modifications. To simulate the transmission path in the real world a signal generator is used to create the QPSK I/Q signal at the HF operating frequencies and a digital sampling oscilloscope acts as a receiver and records the data for analysis. A computer with MATLAB Instrument-control Toolbox is used to generate a random-input data stream as an input to the signal generator, which modulates the RF signal. The RF signal was chosen to be at HF (5-15 MHz) and the QPSK modulation was at 9600 baud. The deterioration effects of a real-world transmitter site were chosen to be associated with the output amplifier linearity and with the transmission line condition between the transmitter and antenna.
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Nguyen, Thanh Chuyen. "Studies on Algorithms for Tag Identification and Tag Set Cardinality Estimation in Radio Frequency Identification Systems". 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174849.
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Youthed, Andrew David. "Designing and implementing a new pulsar timer for the Hartebeesthoek Radio Astronomy Observatory". Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1005243.
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This thesis outlines the design and implementation of a single channel, dual polarization pulsar timing instrument for the Hartebeesthoek Radio Astronomy Observatory (HartRAO). The new timer is designed to be an improved, temporary replacement for the existing device which has been in operation for over 20 years. The existing device is no longer reliable and is di±cult to maintain. The new pulsar timer is designed to provide improved functional- ity, higher sampling speed, greater pulse resolution, more °exibility and easier maintenance over the existing device. The new device is also designed to keeping changes to the observation system to a minimum until a full de-dispersion timer can be implemented at theobservatory. The design makes use of an 8-bit Reduced Instruction Set Computer (RISC) micro-processor with external Random Access Memory (RAM). The instrument includes an IEEE-488 subsystem for interfacing the pulsar timer to the observation computer system. The microcontroller software is written in assembler code to ensure optimal loop execution speed and deterministic code execution for the system. The design path is discussed and problems encountered during the design process are highlighted. Final testing of the new instrument indicates an improvement in the sam- pling rate of 13.6 times and a significant reduction in 60Hz interference over the existing instrument.
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Aslanian, Crystal. "Ondes Ren@rdes, SF radiophonique et artefacts de recherche-création chez r∆∆dio c∆∆rgo et leurs ami·es". Electronic Thesis or Diss., Université Gustave Eiffel, 2025. http://www.theses.fr/2025UEFL2012.
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Cette thèse de recherche-création s’appuie sur le travail de création mené par r∆∆dio c∆∆rgo , collectif de création radiophonique, autour de la notion de plateau-radio, en tant que dispositif de SF dans le sens que lui donne Donna Haraway, à savoir un espace de recherche-création dans lequel s’entremêlent Spéculation Féministe, Faits Scientifiques (Science Fact, Science-Fiction et jeu de ficelle (String Figure en anglais), c’est-à- dire une pratique collective qui produit autant un échange et une circulation de la pensée interdisciplinaire, qu’elle en cartographie son propre processus. La thèse tente de démontrer que le studio radiophonique tel qu’on le connaît aujourd’hui -avec ses micros, ses casques, ses animateur·ices qui reçoivent des invité·es et sa technicité qui canalise la parole et les sons au service d’une production adressée à des auditeur·ices - peut être appréhendé d’autres manières et à d’autres fins. La thèse se construit de manière polyphonique dans deux temporalités qui se superposent. Tout d’abord celle de comptes-rendus d’expériences artistiques réalisées entre 2017 et 2021, dans lesquels des collectifs vivent et expérimentent l’objet d’étude et dont l’écriture autorise une forme de style, celui d’un journal autoreflexif permettant de rendre compte des relations que les participant·es ont entre elles et eux et avec les dispositifs. En parallèle, une partie théorique, reposant elle sur une écriture scientifique, observera l’objet d’étude du plateau-radio avec le recul nécessaire pour produire une pensée théorique. Cette partie théorique propose une approche du plateau-radio en tant que dispositif de recherche-création artistique, scientifique et politique mais aussi en tant qu’espace relationnel de création aurale et émancipatrice. L’écriture polyphonique permet ainsi une friction entre spéculation artistique et écriture scientifique afin de faire émerger, dans l’entre-deux, une méthodologie de recherche-création. Une troisième voix apparaîtra donc peu à peu pour manifester une théorie-pratique à travers la méthodologie. Pour construire cette thèse il a ainsi été nécessaire de tresser au moins trois approches méthodologiques. La recherche débute par le concept de SF de Donna Haraway. Celui-ci découle des travaux d’Isabelle Stengers et Didier Debaise sur les gestes spéculatifs qui s’intéressent à comment la théorie peut-elle passer vers la pratique. Ce glissement de la théorie à la pratique par un arc à plusieurs cordes qu’offre le concept de SF se révèle nécessaire lorsqu’il n’y a pas encore assez de faits scientifiques pour poser une hypothèse et qu’il implique de passer par la pratique pour rendre manifeste un objet d’étude. Les deux autres approches sont mentionnées dans le plan résumé.Cette recherche débute donc avec la spéculation suivante :Et si,le plateau radio était un dispositif sorcier qui permet de tracer le cercle, dans le sens que lui donne Isabelle Stengers, à savoir un espace temporairement clos qui permet [aux sorcières éco-féministes] de récupérer les pouvoirs dont iels ont besoin ?This creative research thesis is based on the creative work carried out by r∆∆dio c∆∆rgo, a collective of radio creation, around the notion of the radio platform, understood as a science fiction device in the sense given by Donna Haraway, that is, a space of research-creation where Feminist Speculation, Scientific Facts (Science Fact, Science Fiction), and String Figures intertwine. This approach constitutes a collective practice that produces not only an exchange and circulation of interdisciplinary thought but also maps its own process. The thesis aims to demonstrate that the radio studio as we know it today—with its microphones, headsets, hosts who invite guests, and its technical apparatus that channels speech and sounds for the purpose of production aimed at an audience—can be approached in other ways and for other purposes.The thesis is constructed in a polyphonic manner, unfolding in two overlapping temporalities. First, through reports on artistic experiments conducted between 2017 and 2021, in which collectives live and experiment with the object of study, and where the writing adopts a particular style—a self-reflexive journal that reflects on the relationships between the participants and with the devices. In parallel, a theoretical part, written in a scientific style, observes the object of study—the radio platform—with enough distance to produce theoretical thought. This theoretical section proposes an approach to the radio platform as a device for artistic, scientific, and political research-creation, but also as a relational space for aural and emancipatory creation. The polyphonic writing thus allows for friction between artistic speculation and scientific writing, to bring forth, in the in-between, a research-creation methodology. A third voice will gradually emerge to manifest a theory-practice through the methodology. In constructing this thesis, it was necessary to weave together at least three methodological approaches. The research begins with Donna Haraway’s concept of SF (science fiction/speculative fabulation), drawing from the work of Isabelle Stengers and Didier Debaise on speculative gestures, which examine how theory can move into practice. This shift from theory to practice, through the multi-string arc offered by the concept of SF, becomes necessary when there are not yet enough scientific facts to formulate a hypothesis, requiring practice to make the object of study manifest. The other two approaches are outlined in the summarized plan.Thus, this research begins with the following speculation:What if the radio platform was a witch’s device, enabling the drawing of the circle, in the sense given by Isabelle Stengers—namely, a temporarily enclosed space that allows [eco-feminist witches] to reclaim the powers they need ?
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Bernard, Olivier Friboulet Denis. "Segmentation en imagerie échocardiographique par ensembles de niveaux paramétriques évoluant à partir des statistiques du signal radiofréquence gmentation in echocardiographic imaging using parametric level set model driving by the statistics of the radiofrequency signal /". Villeurbanne : Doc'INSA, 2007. http://docinsa.insa-lyon.fr/these/pont.php?id=bernard.
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Tell, Eric. "Design of Programmable Baseband Processors". Doctoral thesis, Linköping : Univ, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-4377.
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Kazanci, Onur Husnu. "Performance Of Pseudo-random And Quasi-cyclic Low Density Parity Check Codes". Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12609036/index.pdf.
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Low Density Parity Check (LDPC) codes are the parity check codes of long block length, whose parity check matrices have relatively few non-zero entries. To improve the performance at relatively short block lengths, LDPC codes are constructed by either pseudo-random or quasi-cyclic methods instead of random construction methods. In this thesis, pseudo-random code construction methods, the effects of closed loops and the graph connectivity on the performance of pseudo-random LDPC codes are investigated. Moreover, quasi-cyclic LDPC codes, which have encoding and storage advantages over pseudo-random LDPC codes, their construction methods and performances are reviewed. Finally, performance comparison between pseudo-random and quasi-cyclic LDPC codes is given for both regular and irregular cases.
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Voskakis, Konstantinos. "Modeling and simulation of a non-coherent frequency shift keying transceiver using a Field Programmable Gate Array (FPGA)". Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Sept/08Sep%5FVoskakis.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2008.Thesis Advisor(s): Kragh, Frank ; Ateshian, Peter. "September 2008." Description based on title screen as viewed on November 4, 2008. Includes bibliographical references (p. 97-103). Also available in print.
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Akyurek, Alper Sinan. "Swim: A New Multicast Routing Algorithm For Wireless Networks". Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613348/index.pdf.
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In this work, a new multicast routing algorithm for wireless networks is presented. The algorithm, called SWIM (Source-initiated WIreless Multicast), is a depth-optimal multicast tree formation algorithm. SWIM is fully distributed and has an average computational complexity of O(N 2 ). SWIM forms a shared tree from the source(s) to destinationsyet, as a by-product, it creates a multicast mesh structure by maintaining alternative paths at every tree node. This makes SWIM suitable for both ad hoc networks and access networks with multiple gateways. An extension to the main algorithm is presented for the use in dynamic networks with mobility and/or dynamic destination group. Performance of SWIM is studied with simulations and is compared to other algorithms in the literature. Due to depth optimality, SWIM achieves a lower average and maximum delay than the compared algorithms. The throughput performance is found to be high. Working capability with rateless codes are also studied.
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Maciel, Yuri Pontes. "Modulador 1-seg para SBTVD usando GNU Radio". Universidade Presbiteriana Mackenzie, 2015. http://tede.mackenzie.br/jspui/handle/tede/1457.
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Made available in DSpace on 2016-03-15T19:37:55Z (GMT). No. of bitstreams: 1
YURI PONTES MACIEL.pdf: 3993729 bytes, checksum: a06d968ea944e726fa6263339ad70976 (MD5)
Previous issue date: 2015-02-06This paper describes by theoretical conceptualization and pratical experiences two relevant themes of electrical engineering and communications: software defined radio and the Brazilian digital television standard. This paper develops a specific modulator aimed to the portable reception of this digital television system, many times denominated as oneseg reception, by means of computational algorithms developed in the C++ programming language. These algorithms are executed in a development environment named GNU Radio, a open-source tool. Computer simulations are made to prove the correct behaviour of the project. Finnaly the modulator is implemented by means of a development kit of software defined radio then chained to a real communication system, thus proving its practical operation. It is also possible to verify the versatility of the software defined radio, changing the modulator parameters in a fast and easy fashion.
Este trabalho aborda por meio de conceituação teórica e experiências práticas dois temas relevantes da engenharia elétrica e de comunicações: rádios definidos por software e o padrão de televisão digital usado no Brasil. Este trabalho desenvolve um modulador específico para recepção portátil deste sistema de televisão digital, muitas vezes chamada de recepção one-seg, por meio da elaboração de algoritmos computacionais feitos na linguagem de programação C++. Estes algoritmos por sua vez são executados em um ambiente de desenvolvimento chamado GNU Radio, uma ferramenta do tipo open-source. Simulações computacionais são feitas de modo a comprovar o funcionamento do projeto. Finalmente o modulador é implementado em um kit de desenvolvimento de rádio definido por software e então encadeado em um sistema de comunicação real, assim comprovando o seu funcionamento prático. É possível também verificar a versatilidade do rádio definido por software, alterando as configurações do modulador de maneira rápida e prática.
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Hopkins, Thomas A. "An Automated Approach to a 90-nm CMOS DRFM DSSM Circuit Design". Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1281645939.
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Sroka, Christopher J. "Extending Ranked Set Sampling to Survey Methodology". The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1218543909.
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Sönmezer, Volkan. "Cooperative wideband spectrum sensing and localization using radio frequency sensor networks". Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FSonmezer.pdf.
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Thesis (M.S. in Electronic Warfare Systems Engineering and M.S. in Electrical Engineering)--Naval Postgraduate School, September 2009.Thesis Advisor(s): Tummala, Murali ; Jenn, David. "September 2009." Description based on title screen as viewed on November 6, 2009. Author(s) subject terms: Cooperative Spectrum Sensing, Source Localization, Multi-Resolution Spectrum Sensing, Three-Bit Hard Combination, RSS-Based Localization, Cognitive Radio, Wireless Sensor Networks, Electronic Warfare. Includes bibliographical references (p. 87-90). Also available in print.
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Reth, Sarandeth. "Tracking working set sizes of virtual machines using miss ratio curves". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113767.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (page 75).
Working sets are sets of pages that have been most recently accessed by virtual machines (VMs). They are often used within the memory scheduler of a hypervisor to estimate the memory demands of VMs running on the hypervisor. In order to manage the memory resources of the hypervisor efficiently, it is essential that these working set sizes be estimated accurately at any given point in time. Currently, a statistical sampling strategy is used within VMware ESX hypervisors to estimate the working set sizes of VMs. Using this technique, a small number of random pages is selected to form a sample set. Access to these sampled pages is then tracked and the percentage of sampled pages that are accessed is used to estimate the working set size of a VM. This technique, though simple, does not provide a very accurate estimation of the working set size. A more promising tool that can be used to accurately estimate the working set size of a VM is a miss ratio curve (MRC). An MRC is a curve that plots the predicted miss ratio of a VM against the total available memory given to the VM. Even though MRCs can estimate working set sizes of VMs with much better accuracy, they are still not widely used in practice because building these curves incurs too much overhead, thus affecting the overall system performance. However, a recent study has found a way to reduce the cost of building these curves, making them a promising tool that can be used to estimate working set sizes. In this thesis, I propose that MRCs be used as an alternative to the statistical sampling strategy currently employed within VMware ESX. I will demonstrate how to apply the state of the art technique found in the recent study to construct accurate MRCs without incurring too much overhead, and use these curves to track working set sizes of VMs. I will also show that these curves can estimate working set sizes of VMs with much better accuracy than the statistical sampling strategy.
by Sarandeth Reth.
M. Eng.
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Lintz, William A. "Radio frequency signal reception via distributed wirelessly networked sensors under random motion". Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/dissert/2009/Sep/09Sep%5FLintz%5FPhD.pdf.
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Dissertation (Ph.D. in Electrical Engineering)--Naval Postgraduate School, September 2009.Dissertation supervisor: McEachen, John ; Tummala, Murali. "September 2009." Description based on title screen as viewed on November 5, 2009. Author(s) subject terms: Sensor Networks, Beamforming, Random Motion, Orientation Includes bibliographical references (p. 197-203). Also available in print.
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Frushour, John H. "Design considerations for a computationally-lightweight authentication mechanism for passive RFID tags". Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FFrushour.pdf.
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Thesis (M.S. in Computer Science)--Naval Postgraduate School, September 2009.Thesis Advisor(s): Fulp, J.D. ; Huffmire, Ted. "September 2009." Description based on title screen as viewed on November 6, 2009. Author(s) subject terms: Passive RFID Systems, Tags, Clock, Electro-magnetic induction, authentication, hash, SHA--1. Includes bibliographical references (p. 59-60). Also available in print.
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Sim, Chow Yen Desmond. "The propagation of VHF and UHF radio waves over sea paths". Thesis, University of Leicester, 2002. http://hdl.handle.net/2381/7444.
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This thesis is concerned with the statistical studies of VHF/UHF radio wave propagation over the sea path at the limits of line-of-sight range. The objective is to provide a set of data that leads to the understanding of the characteristic of VHF/UHF radio wave over the sea path. A series of experiments were conducted using two paths of around 33 and 48 km across the English Channel. These two paths are between fixed land-based locations that provide an unobstructed condition. This allows a prolonged period of data collection under several sea states and atmospheric conditions without the heavy expenses of ship borne trial. The statistic studies showed that the high signal strength variation observed at both receiving sites are the results due to ducting and super-refraction. It occurred around 43 to 76% and 31 to 48% of the total time (percentage of days) during summer 2001 and 2002 respectively. In comparison, the total time was below 10% during winter period. Across the Jersey-Alderney path (48 km), high fading phenomenon was observed which is a result due to interference fading between the diffracted and troposcattered signal. The statistics showed that it occurred at around 35 to 55% of the total times during summer with an average fading range of around 10 and 7 dB during autumn and summer respectively, with an average fading period of around 7 seconds. The results from simulation showed that when the VHF/UHF signal reaches the radio horizon, the dominant propagating mechanism is smooth earth diffraction. Beyond the radio horizon, the attenuation rate increases dramatically and at a certain distance (depending on the frequency, antenna height and seasonal condition), the diffracted signals will be weaken and the troposcatter effect will become the dominant propagating mechanism.
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Nilsson, Månz. "Radio-wave propagation modelling over rough sea surfaces and inhomogeneous atmosphere". Thesis, Karlstads universitet, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-84595.
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Abdullah, S. N. "Data transmission at 9600 bit/sec over an HF radio link". Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/7432.
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The thesis is concerned with serial data transmission at 9600 bit/sec over a voiceband channel, where the main impairments are additive noise and intersymbol interference, and the latter varles slowly with time. The thesis includes a brief description of the ionospheric propagation medium and presents an equivalent baseband model of the HF channel, suitable for computer simulation of quadrature amplitude modulation (QAM) systems. A study of 16-point QAM signals transmitted over voiceband HF channels is then carr-iod out usj-ng the given channel model. Several cost effective near-maximum-likelihood detection processes have been developed for HF modems. Each detector is here preceded by an adaptive linear filter that is adjusted to make the sampled impulse response of the channel and filter minimum phase. These detectors require an accurate knowledge of the sampled impulse response of the channel, if their full potential is to be achieved. The results of computer-simulation tests on the near-maximum-likelihood detectors are given, where these tests assume that other receiver operations such as channel estimation and adaptive linear filtering, together with element timing synchronisation and Doppler shift correction, are carried out perfectly. A recently developed HF channel estimator employing a simple feedforward transversal-filter and requiring knowledge of the number of skywaves is next investigated and a starting up procedure is developed for such an estimator. The technique is then made fully adaptive in the sense that it continues to operate correctly when the number of skywaves changes. Results of computer simulation tests are then presented showing the performance of the above detectors when operating with a channel estimator and adaptive linear filtering. Finally modem synchronisation is studied and various techniques of element timing and carrier frequency synchronisation are proposed.
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Escobar, Kenny E. "Photonic front-end and comparator processor for a sigma-delta modulator". Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Sept/08Sep%5FEscobar.pdf.
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Thesis (M.S. in Electrincal Engineering)--Naval Postgraduate School, September 2008.Thesis Advisor(s): Pace, Phillip E. "September 2008." Description based on title screen as viewed on November 4, 2008. Includes bibliographical references (p. 65-66). Also available in print.
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Valente, Pedro Brigas. "WiFi radio resource management". Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/23484.
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Mestrado em Engenharia Electrónica e TelecomunicaçõesPassive optical networks have been subject of research in recent years, standing out from the other distribution networks not only by the speed and distribution of multiple services, including video, data and voice, but also by the absence of active equipment between the central and terminal devices, not requiring the use of electricity. Also the progress made in mobile and "smart" equipment led to the increase of its popularity and personal use. The increase of mobile devices, as well as their features, were boosted by the evolution of WiFi technologies, mostly fueled by passive optical networks, favoring the connection of several devices through radio waves. There has been several improvements in wireless communications, especially in WiFi technology, in order to keep up with the speed increase in optical distribution networks. However the limitations in the frequency spectrum and the vast implementation of the technology itself became an obstacle to the development of WiFi networks. The main goal of this dissertation is the development of processes dedicated to the frequency spectrum management in WiFi networks within environments congestedbymultipleradiosignaltransmitters. Thisworkisdevelopedaround a gateway under development by Altice Labs combining optical network terminal and access point features, and presents a solution to the equipment transmission power management and the frequency channel selection.
As redes ópticas passivas têm sido alvo de grande investigação nos últimos anosdestacando-sedasoutrasredesdedistribuiçãonãosópelavelocidadee distribuição de multiplos serviços, incluindo video, dados e voz, mas também pela ausência de equipamentos activos entre a central local e o equipamento terminal, não sendo necessário o uso de energia eléctrica. Também o avanço que se tem verificado no desenvolvimento de equipamentos móveis e "inteligentes" tem levado a sua popularidade e utilização a crescer de forma constante. Por sua vez, este aumento do número de dispositivos móveis, bem como das respectivas características, foi impulsionado pela evolução da tecnologia WiFi, em grande parte alimentada pelas redes ópticas passivas, facilitando a conexão de múltiplos dispositivos através de ondas de rádio. Têm sido várias as melhorias nas comunicações sem fios, especialmente na tecnologia WiFi, no sentido de acompanhar o aumento da velocidade das redes de distribuição ópticas. No entanto as limitações ao nível do espectro de frequência e a vasta implementação da própria tecnologia têm-se revelado obstáculos ao desenvolvimento das redes WiFi. Esta dissertação tem como objectivo o desenvolvimento de soluções para a gestão do espectro de frequência das rede WiFi em ambientes congestionados pela presença de múltiplos transmissores de sinal rádio. Este trabalho é desenvolvido sob um gateway em desenvolvimento pela Altice Labs que combina as funcionalidades de um terminal de redes ópticas e de um access point, e apresenta uma solução para a gestão da potência de transmissão do equipamento e para a escolha do canal de frequência a utilizar.
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Fernandes, Rui Miguel Félix. "Object signature in radio frequency". Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/13708.
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Mestrado em Engenharia Eletrónica e TelecomunicaçõesThe RF signature can be consider as a fingerprint of an object when submitted to electromagnetic radiation. Based on this concept, the initial goal of this work was to elaborate a comparative analysis of the Radio Frequency signature of different materials. Through the design of a prototype based on an adapted Wi-Fi network was developed an innovative system capable of distinguishing materials with the analysis of their interference in the propagated channel. In order to refine this distinction was utilized a signal processing tool, the Wavelet Transform. This technique serve as support tool of the system for a better differentiation of the studied targets. The versatility of this concept was proved through the analysis of signatures of static targets like metal, wood and plastic, as well as moving targets, giving the example of a moving human. Due to the promising results obtained, the initial objective of the work was expanded being also presented in this document the concept of intruder detection through a Wi-Fi network by the analysis of the Wavelet coefficients.
A Assinatura em Rádio Frequência pode ser considerada como a impressão digital que um objeto manifesta quando submetido a radiação eletromagnética. O objetivo inicial deste trabalho era a elaboração de uma análise comparativa das assinaturas em Rádio Frequência de diferentes materiais. Tendo por base uma rede Wi-Fi adaptada, foi desenvolvido um sistema inovador capaz de distinguir materiais pela análise da interferência dos mesmos no canal de propagação. Com vista a melhorar o desempenho do protótipo inicial, o sinal recebido foi processado através da Transformada de Wavelet. Esta técnica serviu como ferramenta de suporte do sistema para a obtenção de uma diferenciação mais clara dos alvos estudados. Demonstrando a versatilidade deste conceito foram avaliadas as assinaturas de alvos estáticos como o metal, madeira e plástico bem como de alvos móveis dando, como exemplo, uma pessoa em movimento. Devido aos resultados promissores obtidos, o objetivo inicial do sistema foi alargado estando também presente neste documento o conceito de deteção de intrusos através de uma rede Wi-Fi pela análise dos coeficientes de Wavelet.
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Carvalho, Nefi Julião. "Impact of the nonlinear phenomenon on wireless radio telecommunications systems". Master's thesis, Universidade de Aveiro, 2008. http://hdl.handle.net/10773/1996.
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Mestrado em Engenharia InformáticaA dimensão e heterogeneidade de recentes sistemas de telecomunicações sem fios impossibilitam a previsão do comportamento do sistema completo quando operado nos limites das suas capacidades. Isto torna irrealista o estudo do impacto do fenómeno não linear no desempenho dos sistemas em especial devido a que os resultados são diferentes quando estudados em separado ou embebidos num sistema. Este trabalho ultrapassa estas problemáticas através do uso de técnicas de co-simulação e de modelação do actual estado da arte as quais tornam possível uma representação mais realista do desempenho de um sistema. ABSTRACT: The dimension and heterogeneity of recent wireless radio telecommunication systems makes impracticable the prediction of the full system behavior when pushed to its performance limits. This makes unrealistic the study of the impact of the nonlinear phenomenon on the systems performance, especially because the results are different when studied alone or embedded in a system. This work overcomes these difficulties by using state-of-the-art cosimulation and modeling techniques that made possible the presentation of more realistic system performance evaluations.
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Tawfik, Abdulkarim Naji. "Experimental and statistical studies of x-band transhorizon radio links over the sea". Thesis, University of Portsmouth, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281113.
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This thesis is concerned with the statistical studies of microwave signals received from beyond the radio horizon. A measurement campaign has been conducted in collaboration with Rutherford Appleton Laboratories and CNET (§) in France in order to collect propagation data across the English channel. The transmitter sites were located at Lannion and Cap d'Antifer in the North French coast and the receiver sites at HighcIiffe and Portsmouth in the South of England. Several original findings have been obtained by the research. For the two types of path considered of 155 and 250 km respectively, the cumulative distributions of transmission loss level L display two separate regions; one represents the troposcatter region and the other one represents the anomalous region. The separation between the two regions occurs between 10 and 20 dB below the free space path loss irrespective of the type of path considered. The two regions appear to be well modelled by two distinct normal distributions with their particular mean and standard deviation. The cumulative distributions of the transmission loss derived from measured data were also compared with prediction models available from Ii tera ture. The duration D of exceedance or enhancement above signal level threshold was investigated in terms of the joint statistics of transmission loss and duration of exceedances Prob (D' ~ DIL' s L). Two different distributions were analysed and modelled; the number distribution Pn and the time distribution PI. P,dDIL) represents the fractional number of cases where durations have been greater than D once the path loss is less than L, whereas PdDIL) 5ives the relative time with path loss less than L due to all durations greater than or equal to D. It is found that both Pn and PI are well modelled by log-normal distributions for all types of propagation conditions and these distributions are very skewed. For PI the (§) Centre Nationale D'Etudes des Tclecomunications, Paris and Lannion Laboratories mode computed can range from fractions to several minutes whereas the median can range from many tens of minutes towards the troposcatter levels down to a few minutes close to the free space loss threshold of L = 0 dBf. The logarithm of the median duration of Pt was found to be linearly related to L (dBt). As regards the standard deviation, an (lnD) and at(lnD) are very close in agreement with the theory and range from 1 to 4 when D is in minutes. They were also found to be linearly related to L (dBD. The research has shown that there is a strong seasonal dependence of the path loss and the monthly attenuation may vary over a wide range throughout the year, with variation being greatest on the longer path. The research has also shown that during a 24 hours period there is, in general, a rise in the probability of exceeding a given level at around 1000 GMT and this probability reaches its peak at around 1900 GMT to then begin to decrease at about 2000 GMT. This pattern is much more pronounced in the summer months than in the winter months. The daily variation is also more pronounced for the shorter paths than for the longer paths. The time between 11 no to 1900 GMT appears to be the strongest period of potential interference. The research has included a preliminary analysis of the correlation between signal level strength and the local surface meteorological parameters: temperature, water vapour pressure and atmospheric pressure. As expected good correlation with temperature was observed particularly with weekly averaged maximum daily values. However; atmospheric pressure is the most dominant parameter on signal enhancements. Finally, short term fading of clear air troposcatter signals was investigated and the power spectral density analyses show significant components up to about 5 Hz.
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Gunashekar, Salil David. "An investigation of the propagation of 2 GHz radio waves over sea paths". Thesis, University of Leicester, 2006. http://hdl.handle.net/2381/30235.
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Three long-range 2 GHz radio paths have been established in the British Channel Islands in order to investigate the characteristics of long-range propagation of UHF radio waves over the sea as part of a project supported by Ofcom, UK. The relationship between specific over-sea propagation mechanisms (such as evaporation ducting and super-refraction) in the lower troposphere and signal strength distribution patterns has been examined, modelled and correlated with meteorological parameters. A number of radio meteorological statistics specifically related to evaporation duct propagation in a temperate region such as the English Channel has been presented to confirm the capability of this key propagation mechanism to guide radio waves to distances well beyond the normal radio horizon. Evaporation ducting and diffraction appear to be the dominant propagation mechanisms at most times. Signal strength enhancements have been observed on all three radio paths, primarily in the late afternoon and evening periods, in the spring and summer months. During periods of enhanced propagation, which occur approximately 8% of the time of a 50 km path, the presence of additional higher-level ducting/super-refractive structures has been verified and their influence has been modelled with reasonable success. Additionally, the statistical variation of bulk meteorological parameters in the context of enhanced signal propagation has also been examined. The relatively long-term observations made during this study confirm the fact that the constantly changing weather patterns in the troposphere (e.g. the occurrence of anticyclonic weather) are directly responsible for the occurrence of enhanced signals at certain periods of time. The various issues under investigation are of direct relevance in the planning of radio communication systems operating in the UHF band (e.g. GSM and UMTS) in marine and coastal regions.
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Mello, Renata Valverde. "Contribuições ao dimensionamento de redes sem fio". [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259665.
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Orientador: Michel Daoud YacoubDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: Este trabalho aborda o dimensionamento de redes sem fio por meio da análise da probabilidade de outage visando contemplar sistemas com múltiplas classes de serviço. Esta é uma tarefa complexa, uma vez que deve considerar aspectos como o desvanecimento e a interferência do canal sem fio e o tráfego de diferentes classes de serviço. Inicialmente é analisada uma rede ad hoc com uma única classe de serviço a partir da probabilidade de outage conjunta. Em seguida, determina-se uma nova formulação analítica fechada para o cálculo da probabilidade de outage em sistemas com múltiplas classes de serviço. Esta foi prontamente validada por meio de simulações a eventos discretos. Desta maneira, a formulação proposta pode ser utilizada para o dimensionamento de redes sem fio multi-serviço sem a necessidade da realização de simulações. Este método apresenta vantagens como fácil implementação e baixo esforço computacional. Isto significa que foi obtida uma ferramenta de dimensionamento rápida e precisa.
Abstract: This work tackles with the problem of dimensioning wireless networks through the analysis of the outage probability aiming to contemplate multiservice traffic. This is an intrincate task, since it must consider aspects such as fading and interference in the wireless channel as well as multiservice traffic. First, an ad hoc network with only one class of service is analysed through the joint outage probability. Then, a novel closed formulation for the outage probability in multiservice systems is found. This formulation was promptly validated through discrete-event simulation. Therefore, the proposed formulation may be used for the dimensioning in multiservice wireless networks without the necessity of simulations. This method presents the advantages of easy implementation and low computational effort. This means that this tool enables a fast and precise dimensioning.
Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica
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Silva, Carlos Filipe Moreira e. "Common radio resource management in wireless heterogeneous networks". Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/3992.
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Mestrado em Electrónica e TelecomunicaçõesA tecnologia de sinais de rádio frequência sobre fibra óptica involve o uso de links ópticos para transportar os sinais desde a unidade central de processamento até aos sites remotos (e vice-versa). A centralização do processamento dos sinais de rádio frequência permite a partilha de equipamentos, alocação dinâmica de recursos e uma manutenção mais simplificada do sistema. Embora o conceito de gestão comum dos recursos rádio tenha despertado grande interesse na comunidade científica em termos da melhor utilização desses recursos e de novos modelos de negócio, a verdade é que a sua implementação não tem sido fácil. A interligação entre diferentes componentes de rede, normalmente localizados em locais diferentes, introduz um grande atraso nas comunicações; por outro lado as implementações proprietárias e a escassez de informação global não satisfazem os requisitos de um ambiente extremamente dinâmico, como é o ambiente wireless. Uma topologia centralizada permite ultrapassar estas contrariedades, disponibilizando uma interligação eficiente entre as entidades locais e comuns de gestão de recursos rádio. Nesta dissertação é apresentada uma nova arquitectura de gestão comum de recursos rádio, baseada no conceito de interligação entre diferentes tecnologias de acesso. Esta arquitectura faz a gestão dos recursos rádio de forma centralizada, onde os sinais rádio chegam sem qualquer pré-processamento. Essa arquitectura é avaliada com a implementação de um algoritmo simples de balanceamento da carga que segue a politica de minimização da interferência e aumento da capacidade. As simulações com duas tecnologias de acesso, quando consideradas separas ou em agregado, mostraram um aumento do débito de pelo menos 51% para o mesmo valor de interferência enquanto que o erro de simbolo decresce pelo menos 20%.
Radio over fibre technology involves the use of optical fibre links to distribute radio frequency signals from a central location to remote sites (and viceversa). The centralisation of radio frequency signals processing functions enables equipment sharing, dynamic allocation of resources, and simplified system operation and maintenance. Despite the unquestionable interest concept of common radio resource management from the point of view of resource usage and novel business models, its implementation has not been easy. The interworking between the different local radio resource management entities, usually located on different places will not satisfy the requirements of the wireless dynamic behaviour due to increase of delay in communication process, less information availability and proprietary implementations. A centralised topology can overcome the drawbacks of former wireless systems architecture interconnection by providing an efficient common radio communication flow with the local radio resource management entities. In this thesis a novel common radio resource management architecture is presented based on the concept of inter-working between different technologies. This is a centralised architecture where the radio frequency signals are delivered to the central location through the optical links. The new architecture is evaluated with a common policy that minimises interference while the overall system capacity is increased. The policy is implemented through the load balancing algorithm. The simulations of two radio access technologies when separately and jointly considered show that when the load balancing algorithm is applied the available throughput increases in at least 51% while the symbol error rate decreases at least 20%.
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Boaventura, Alírio de Jesus Soares. "Efficient wireless power transfer and radio frequency identification systems". Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17374.
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Doutoramento em Engenharia EletrotécnicaIn the IoT context, where billions of connected objects are expected to be ubiquitously deployed worldwide, the frequent battery maintenance of ubiquitous wireless nodes is undesirable or even impossible. In these scenarios, passive-backscatter radios will certainly play a crucial role due to their low cost, low complexity and battery-free operation. However, as passive-backscatter devices are chiefly limited by the WPT link, its efficiency optimization has been a major research concern over the years, gaining even more emphasis in the IoT context. Wireless power transfer has traditionally been carried out using CW signals, and the efficiency improvement has commonly been achieved through circuit design optimization. This thesis explores a fundamentally different approach, in which the optimization is focused on the powering waveforms, rather than the circuits. It is demonstrated through theoretical analysis, simulations and measurements that, given their greater ability to overcome the built-in voltage of rectifying devices, high PAPR multi-sine (MS) signals are capable of more efficiently exciting energy harvesting circuits when compared to CWs. By using optimal MS signals to excite rectifying devices, remarkable RF-DC conversion efficiency gains of up to 15 dB with respect to CW signals were obtained. In order to show the effectiveness of this approach to improve the communication range of passive-backscatter systems, a MS front-end was integrated in a commercial RFID reader and a significant range extension of 25% was observed. Furthermore, a software-defined radio RFID reader, compliant with ISO18000-6C standard and with MS capability, was constructed from scratch. By interrogating passive RFID transponders with MS waveforms, a transponder sensitivity improvement higher than 3 dB was obtained for optimal MS signals. Since the amplification and transmission of high PAPR signals is critical, this work also proposes efficient MS transmitting architectures based on space power combining techniques. This thesis also addresses other not less important issues, namely self-jamming in passive RFID readers, which is the second limiting factor of passive-backscatter systems. A suitable self-jamming suppression scheme was first used for CW signals and then extended to MS signals, yielding a CW isolation up to 50 dB and a MS isolation up 60 dB. Finally, a battery-less remote control system was developed and integrated in a commercial TV device with the purpose of demonstrating a practical application of wireless power transfer and passive-backscatter concepts. This allowed battery-free control of four basic functionalities of the TV (CH+,CH-,VOL+,VOL-).
No contexto da internet das coisas (IoT), onde são esperados bilhões de objetos conectados espalhados pelo planeta de forma ubíqua, torna-se impraticável uma frequente manutenção e troca de baterias dos dispositivos sem fios ubíquos. Nestes cenários, os sistemas radio backscatter passivos terão um papel preponderante dado o seu baixo custo, baixa complexidade e não necessidade de baterias nos nós móveis. Uma vez que a transmissão de energia sem fios é o principal aspeto limitativo nestes sistemas, a sua otimização tem sido um tema central de investigação, ganhando ainda mais ênfase no contexto IoT. Tradicionalmente, a transferência de energia sem-fios é feita através de sinais CW e a maximização da eficiência é conseguida através da otimização dos circuitos recetores. Neste trabalho explora-se uma abordagem fundamentalmente diferente, em que a otimização foca-se nas formas de onda em vez dos circuitos. Demonstra-se, teoricamente e através de simulações e medidas que, devido à sua maior capacidade em superar a barreira de potencial intrínseca dos dispositivos retificadores, os sinais multi-seno (MS) de elevado PAPR são capazes de excitar os circuitos de colheita de energia de forma mais eficiente quando comparados com o sinal CW tradicional. Usando sinais MS ótimos em circuitos retificadores, foram verificadas experimentalmente melhorias de eficiência de conversão RF-DC notáveis de até 15 dB relativamente ao sinal CW. A fim de mostrar a eficácia desta abordagem na melhoria da distância de comunicação de sistemas backscatter passivos, integrou-se um front-end MS num leitor RFID comercial e observou-se um aumento significativo de 25% na distância de leitura. Além disso, desenvolveu-se de raiz um leitor RFID baseado em software rádio, compatível com o protocolo ISO18000-6C e capaz de gerar sinais MS, com os quais interrogou-se transponders passivos, obtendo-se ganhos de sensibilidade dos transponders maiores que 3 dB. Uma vez que a amplificação de sinais de elevado PAPR é uma operação crítica, propôs-se também novas arquiteturas eficientes de transmissão baseadas na combinação de sinais em espaço livre. Esta tese aborda também outros aspetos não menos importantes, como o self-jamming em leitores RFID passivos, tido como o segundo fator limitativo neste tipo de sistemas. Estudou-se técnicas de cancelamento de self-jamming CW e estendeu-se o conceito a sinais MS, tendo-se obtido isolamentos entre o transmissor e o recetor de até 50 dB no primeiro caso e de até 60 dB no segundo. Finalmente, com o objetivo de demonstrar uma aplicação prática dos conceitos de transmissão de energia sem fios e comunicação backscatter, desenvolveu-se um sistema de controlo remoto sem pilhas, cujo protótipo foi integrado num televisor comercial a fim de controlar quatro funcionalidades básicas (CH+,CH-,VOL+,VOL-).
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Macalanda, Eduardo C. "Radio frequency identification (RFID) for Naval Medical Treatment Facilities (MTF)". Thesis, Monterey, California. Naval Postgraduate School, 2006. http://hdl.handle.net/10945/2578.
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The application of Radio Frequency Identification (RFID) technology in hospitals is modest primarily due to cost and policy issues. Similar to the evolution of other electronic technologies, unit costs for components have been dramatically reduced in the past few years. Despite the reduction in costs, RFID technology has not yet achieved the tipping point of economic rationality for adoption at most healthcare organizations. Although the technology has been primarily applied to asset management and supply chain applications, Navy Medicine stands to gain tremendous benefit if this technology could be successfully implemented for staff and patient tracking in addition to inventory management. The purpose of this thesis was to conduct a review of RFID technology and components that could fit into the Navy Medicine's structure. The study explored the implementation requirements associated with the deployment in other industries that could be used as benchmarks for Navy Medicine implementation. Different technological architectures were described to illustrate the various techniques that could be used for creating the opportunity to automate administration, reduce errors and improve security for both patients and staff.
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Fugagnoli, Alice. "The ratio of plastic to plankton in the Mediterranean Sea". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16962/.
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Plastic pollution is a huge problem that is affecting all the oceans of the Earth. Plastic items end into the sea, break into tiny pieces and pollute the marine environment. The aim of this research is to increase our knowledge on this problem by comparing microplastic and zooplankton distributions.
Samples from the Mediterranean Sea and Gibraltar Strait have been collected and analyzed. Plastic fragments have been extracted, weighted, photographed, measured and analyzed with a hyperspectral camera. The planktonic part of the samples has been analyzed identifying the main typology of organisms, taking pictures of the samples and analyzing them with ImageJ to take the measures. Data analysis was focused to the plastic to zooplankton ratio.
The results have highlighted that most of the plastic to plankton ratios occurred in the in 1mm-10mm size range, and half of the stations in the Mediterranean sea presented values higher than 1, meaning than there is more plastic than plankton in that size range, for 50% of the Mediterranean. The ratio was higher during the day, due to the ascent of zooplankton during night. The results clearly show that the rank of greater danger is between 1mm to 10mm, and for this reason future samplings should focus on a net for this specific size range, to make sampling more simple and effective. A pollution indicator was created, based on the data collected all around the Mediterranean Sea, which could help find out future danger classifications, and choose the best adoptable strategies to solve the problem. Furthermore, the fact that the higher ratio has been found during the day can help future plastic sampling to focus on this time lapse. Concluding, the data provided by this research will be useful to better understand the degree of plastic contamination of our oceans and give updates to develop quality guidelines according to the Marine Strategy Framework Directive.
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HAIDER, KAMRAN. "Peak to Average Ratio Reduction in Wireless OFDM Communication Systems". Thesis, Blekinge Tekniska Högskola, Avdelningen för signalbehandling, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5309.
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Future mobile communications systems reaching for ever increasing data rates require higher bandwidths than those typical used in today’s cellular systems. By going to higher bandwidth the (for low bandwidth) flat fading radio channel becomes frequency selective and time dispersive. Due to its inherent robustness against time dispersion Orthogonal Frequency Division Multiplex (OFDM) is an attractive candidate for such future mobile communication systems. OFDM partitions the available bandwidth into many subchannels with much lower bandwidth. Such a narrowband subchannel experiences now due to its low bandwidth an almost flat fading leading in addition to above mentioned robustness also to simple implementations. However, one potential drawback with OFDM modulation is the high Peak to Average Ratio (PAR) of the transmitted signal: The signal transmitted by the OFDM system is the superposition of all signals transmitted in the narrowband subchannels. The transmit signal has then due to the central limit theorem a Gaussian distribution leading to high peak values compared to the average power. A system design not taking this into account will have a high clip rate: Each signal sample that is beyond the saturation limit of the power amplifier suffers either clipping to this limit value or other non-linear distortion, both creating additional bit errors in the receiver. One possibility to avoid clipping is to design the system for very high signal peaks. However, this approach leads to very high power consumption (since the power amplifier must have high supply rails) and also complex power amplifiers. The preferred solution is therefore to apply digital signal processing that reduces such high peak values in the transmitted signal thus avoiding clipping. These methods are commonly referred to as PAR reduction. PAR reduction methods can be categorized into transparent methods – here the receiver is not aware of the reduction scheme applied by the transmitter – and non-transparent methods where the receiver needs to know the PAR algorithm applied by the transmitter. This master thesis would focus on transparent PAR reduction algorithms. The performance of PAR reduction method will be analysed both with and without the PSD constrained. The effect of error power on data tones due to clipping will be investigated in this report.
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Bhatia, Krishan. "USE OF NEAR INFRARED SPECTROSCOPY AND MULTIVARIATE CALIBRATION IN PREDICTING THE PROPERTIES OF TISSUE PAPER MADE OF RECYCLED FIBERS AND VIRGIN PULP". Miami University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=miami1077768497.
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Mary, Philippe. "Etude analytique des performances des systèmes radio-mobiles en présence d'évanouissements et d'effet de masque". Phd thesis, INSA de Lyon, 2008. http://tel.archives-ouvertes.fr/tel-00406310.
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Cette thèse a pour but l'analyse des performances d'une communication radio en présence d'évanouissements et d'effet de masque. Le masquage, du aux obstacles entre l'émetteur et le récepteur, fait varier la probabilité d'erreur moyenne ("Symbole Error Probability" SEP). L'étude de la probabilité de coupure symbole (SEO "Symbol error Outage") définie comme la probabilité que le SEP moyen excède une valeur seuil est donc plus pertinent. La difficulté de son étude réside dans le fait qu'une inversion du SEP moyen par rapport au SNR (Signal to Noise Ratio) est nécessaire. Par la méthode de Laplace nous donnons des approximations précises à tout SNR du SEP dans un canal de Nakagami-m et Rice dans le cas mono-antenne. Nous montrons ensuite que ces approximations sont inversibles par rapport au SNR et permettent d'exprimer analytiquement le SEO en fonction du SEP cible. Nous intégrons ensuite le codage canal et dérivons des expressions analytiques de la probabilité de coupure paquet pour un codage bloc puis un codage convolutif à entrée décidée. Nous étendons l'étude aux systèmes MIMO à codage bloc orthogonaux puis à multiplexage spatial où des formes exactes du SEO sont dérivées. Nous considérons le cas où des interférents sont présents. Nous dérivons une approximation précise et inversible de la probabilité d'erreur lorsque les signaux se propagent à travers un canal à évanouissements rapides de Rayleigh. Enfin parce que la prise en compte de l'interférence est un moyen avéré d'augmenter la capacité des réseaux, nous étudions les performances de la détection multiutilisateurs à maximum de vraisemblance (MUD-MLSE), dans un contexte WLAN à canaux recouvrant.
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Matos, Roberto de. "Arquitetura de canais para rádios definidos por software de múltiplas camadas". reponame:Repositório Institucional da UFSC, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/94601.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-graduação em Engenharia de Automação e Sistemas, Florianópolis, 2010Made available in DSpace on 2012-10-25T13:15:05Z (GMT). No. of bitstreams: 1 284640.pdf: 1721974 bytes, checksum: 02e748921e1618abe4e5bfea286f55ac (MD5)
Nos últimos anos, foram criados diversos padrões de redes sem fio para garantir o cumprimento de diferentes requisitos de alcance, vazão de dados, segurança e consumo de energia. Muitas vezes isso obriga a integração de componentes que suportam diversas redes sem fio para criação de equipamentos multipadrões. Essa solução tradicional, apesar de robusta, impõe uma série de limitações relacionadas com o espaço físico, consumo de energia e custo dos sistemas integrados, além da falta de flexibilidade para modificações. Uma alternativa a esse cenário tem sido o uso de Rádios Definidos por Software (SDR), os quais possuem a camada física completamente reconfigurável, permitindo flexibilidade em vários parâmetros de comunicação como faixa de freqüência, tipo de modulação e potência de transmissão. Atualmente, existem várias propostas para implementação de SDRs, destacando-se o GNU Radio em conjunto com a placa USRP como opção de baixo custo, que possibilita a criação de rádios funcionais a partir de modelos de alto nível utilizando computadores pessoais. Entretanto, existe uma lacuna no suporte nativo à implementação de múltiplas camadas físicas compartilhando a mesma interface física, o que causa um overhead maior que o desejado na criação de sistemas multipadrões. Para superar tal desafio, este trabalho apresenta a concepção de uma arquitetura de canais para múltiplas camadas físicas que se destaca por propor uma interface genérica que atende a todos os tipos de camadas físicas e pode ser suportada por diversos hardwares de SDR. Visando a melhor utilização dos recursos a arquitetura proposta permite o deslocamento do estágio de separação de múltiplos canais para o hardware sem a perda de flexibilidade. Para validar a arquitetura proposta foi desenvolvido um protótipo baseado no GNU Radio e USRP2, além das implementações de dois cenários de testes, com múltiplas camadas físicas iguais (IEEE802.15.4) e com múltiplas camadas diferentes (IEEE802.15.4 e IEEE802.11b). Os testes demonstraram uma melhora significativa no desempenho global do sistema e uma simplificação na interface com a camada física, uma vez que não há necessidade de configurar as variáveis relacionadas com os ajustes do próprio hardware.
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Teixeira, Diana Lúcia de Jesus. "Analysis on RF-DC converters for integration in radio receivers". Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/8717.
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Mestrado em Engenharia Eléctrónica e TelecomunicaçõesIn the current technological paradigm the electronic systems appliance is much wider than automation and control of industrial processes, and in the last years it has been directed for the satisfaction of the human needs and pleasures. As consequence of the personal usage of electronic devices it is at most interest to make them portable, thus avoiding constrains in the user mobility. However, the power supply strategy used to provide portability to the devices relies on storage elements, such as batteries or supercapacitors, whose periodical recharge can be uncomfortable or even impossible for their users. So, this project intends to avoid the manual recharge process by proposing an energy harvesting strategy capable to provide power autonomy to the device. Between many sources of energy available this work chooses to collect and convert the power of the electromagnetic waves which are crowding indoor and outdoor environments, and so it aims to study, analyse and test di erent circuits whose purpose is to convert radio-frequency signals into Direct Current (DC) power. The main focus of this circuits assessment is the power conversion e ciency and the maximum DC output voltage generation, always considering Radio Frequency (RF) signals with very low power and frequencies in the range of Ultra High Frequency (UHF). The main goal of this thesis is to make it a useful tool to be used as a support in the future project and design of Radio Frequency (RF) energy harvesting systems, as it o ers a deep evaluation in many di erent circuit topologies and its constituent elements.
No paradigma tecnol ogico actual a utiliza ção de sistemas electr onicos vai muito al em da automa ção e controlo de processos industriais rotineiros, tendo-se direccionado nas ultimas d ecadas para a satisfa ção das necessidades e prazeres do Homem. Em consequência da utiliza ção de car acter pessoal de muitos destes novos dispositivos electr onicos foi importante adapt alos de forma a não comprometerem a mobilidade do seu utilizador. Assim, uma das di culdades em desenvolver dipositivos portateis prende-se com o fornecimento de energia e, tipicamente, a solu ção encontrada passa por usar sistemas de armazenamento, baterias, pilhas ou supercondensadores, que necessitam de ser recarregados periodicamente. Eno sentido de evitar o processo de recarga manual que surge este trabalho cujo objectivo e estudar, analisar e testar uma estrat egia de capta ção de energia capaz de dotar um dispositivo port atil de autonomia energ etica. O mecanismo em causa pretende a recolha e conversão da potência dos sinais de radiofrequência (RF) e o foco deste estudo e a avalia ção, em e ciência e capacidade de multiplica ção de tensão, de v arios circuitos de recti ca ção, considerando sempre a sua utiliza c~ao a elevadas frequências, Ultra High Frequency (UHF), e muito baixas potências. Como resultado pretende-se tamb em que este documento constitua uma boa ferramenta de auxí lio a futuros projectos de sistemas de recolha e convers~ao da potência de sinais de RF j a que fornece uma avalia ção profunda das v arias topologias dispon veis.
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Nascimento, Alberto de Jesus. "Multilayer optimization in radio resource allocation for the packet transmission in wireless networks". Doctoral thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/2228.
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Doutoramento em Engenharia ElectrotécnicaNa última década tem-se assistido a um crescimento exponencial das redes de comunicações sem fios, nomeadamente no que se refere a taxa de penetração do serviço prestado e na implementação de novas infra-estruturas em todo o globo. É ponto assente neste momento que esta tendência irá não só continuar como se fortalecer devido à convergência que é esperada entre as redes móveis sem fio e a disponibilização de serviços de banda larga para a rede Internet fixa, numa evolução para um paradigma de uma arquitectura integrada e baseada em serviços e aplicações IP. Por este motivo, as comunicações móveis sem fios irão ter um papel fundamental no desenvolvimento da sociedade de informação a médio e longo prazos. A estratégia seguida no projecto e implementação das redes móveis celulares da actual geração (2G e 3G) foi a da estratificação da sua arquitectura protocolar numa estrutura modular em camadas estanques, onde cada camada do modelo é responsável pela implementação de um conjunto de funcionalidades. Neste modelo a comunicação dá-se apenas entre camadas adjacentes através de primitivas de comunicação pré-estabelecidas. Este modelo de arquitectura resulta numa mais fácil implementação e introdução de novas funcionalidades na rede. Entretanto, o facto das camadas inferiores do modelo protocolar não utilizarem informação disponibilizada pelas camadas superiores, e vice-versa acarreta uma degradação no desempenho do sistema. Este paradigma é particularmente importante quando sistemas de antenas múltiplas são implementados (sistemas MIMO). Sistemas de antenas múltiplas introduzem um grau adicional de liberdade no que respeita a atribuição de recursos rádio: o domínio espacial. Contrariamente a atribuição de recursos no domínio do tempo e da frequência, no domínio espacial os recursos rádio mapeados no domínio espacial não podem ser assumidos como sendo completamente ortogonais, devido a interferência resultante do facto de vários terminais transmitirem no mesmo canal e/ou slots temporais mas em feixes espaciais diferentes. Sendo assim, a disponibilidade de informação relativa ao estado dos recursos rádio às camadas superiores do modelo protocolar é de fundamental importância na satisfação dos critérios de qualidade de serviço exigidos. Uma forma eficiente de gestão dos recursos rádio exige a implementação de algoritmos de agendamento de pacotes de baixo grau de complexidade, que definem os níveis de prioridade no acesso a esses recursos por base dos utilizadores com base na informação disponibilizada quer pelas camadas inferiores quer pelas camadas superiores do modelo. Este novo paradigma de comunicação, designado por cross-layer resulta na maximização da capacidade de transporte de dados por parte do canal rádio móvel, bem como a satisfação dos requisitos de qualidade de serviço derivados a partir da camada de aplicação do modelo. Na sua elaboração, procurou-se que o standard IEEE 802.16e, conhecido por Mobile WiMAX respeitasse as especificações associadas aos sistemas móveis celulares de quarta geração. A arquitectura escalonável, o baixo custo de implementação e as elevadas taxas de transmissão de dados resultam num processo de multiplexagem de dados e valores baixos no atraso decorrente da transmissão de pacotes, os quais são atributos fundamentais para a disponibilização de serviços de banda larga. Da mesma forma a comunicação orientada à comutação de pacotes, inenente na camada de acesso ao meio, é totalmente compatível com as exigências em termos da qualidade de serviço dessas aplicações. Sendo assim, o Mobile WiMAX parece satisfazer os requisitos exigentes das redes móveis de quarta geração. Nesta tese procede-se à investigação, projecto e implementação de algoritmos de encaminhamento de pacotes tendo em vista a eficiente gestão do conjunto de recursos rádio nos domínios do tempo, frequência e espacial das redes móveis celulares, tendo como caso prático as redes móveis celulares suportadas no standard IEEE802.16e. Os algoritmos propostos combinam métricas provenientes da camada física bem como os requisitos de qualidade de serviço das camadas superiores, de acordo com a arquitectura de redes baseadas no paradigma do cross-layer. O desempenho desses algoritmos é analisado a partir de simulações efectuadas por um simulador de sistema, numa plataforma que implementa as camadas física e de acesso ao meio do standard IEEE802.16e.
In the last decade mobile wireless communications have witnessed an explosive growth in the user’s penetration rate and their widespread deployment around the globe. It is expected that this tendency will continue to increase with the convergence of fixed Internet wired networks with mobile ones and with the evolution to the full IP architecture paradigm. Therefore mobile wireless communications will be of paramount importance on the development of the information society of the near future. In particular a research topic of particular relevance in telecommunications nowadays is related to the design and implementation of mobile communication systems of 4th generation. 4G networks will be characterized by the support of multiple radio access technologies in a core network fully compliant with the Internet Protocol (all IP paradigm). Such networks will sustain the stringent quality of service (QoS) requirements and the expected high data rates from the type of multimedia applications to be available in the near future. The approach followed in the design and implementation of the mobile wireless networks of current generation (2G and 3G) has been the stratification of the architecture into a communication protocol model composed by a set of layers, in which each one encompasses some set of functionalities. In such protocol layered model, communications is only allowed between adjacent layers and through specific interface service points. This modular concept eases the implementation of new functionalities as the behaviour of each layer in the protocol stack is not affected by the others. However, the fact that lower layers in the protocol stack model do not utilize information available from upper layers, and vice versa, downgrades the performance achieved. This is particularly relevant if multiple antenna systems, in a MIMO (Multiple Input Multiple Output) configuration, are implemented. MIMO schemes introduce another degree of freedom for radio resource allocation: the space domain. Contrary to the time and frequency domains, radio resources mapped into the spatial domain cannot be assumed as completely orthogonal, due to the amount of interference resulting from users transmitting in the same frequency sub-channel and/or time slots but in different spatial beams. Therefore, the availability of information regarding the state of radio resources, from lower to upper layers, is of fundamental importance in the prosecution of the levels of QoS expected from those multimedia applications. In order to match applications requirements and the constraints of the mobile radio channel, in the last few years researches have proposed a new paradigm for the layered architecture for communications: the cross-layer design framework. In a general way, the cross-layer design paradigm refers to a protocol design in which the dependence between protocol layers is actively exploited, by breaking out the stringent rules which restrict the communication only between adjacent layers in the original reference model, and allowing direct interaction among different layers of the stack. An efficient management of the set of available radio resources demand for the implementation of efficient and low complexity packet schedulers which prioritize user’s transmissions according to inputs provided from lower as well as upper layers in the protocol stack, fully compliant with the cross-layer design paradigm. Specifically, efficiently designed packet schedulers for 4G networks should result in the maximization of the capacity available, through the consideration of the limitations imposed by the mobile radio channel and comply with the set of QoS requirements from the application layer. IEEE 802.16e standard, also named as Mobile WiMAX, seems to comply with the specifications of 4G mobile networks. The scalable architecture, low cost implementation and high data throughput, enable efficient data multiplexing and low data latency, which are attributes essential to enable broadband data services. Also, the connection oriented approach of Its medium access layer is fully compliant with the quality of service demands from such applications. Therefore, Mobile WiMAX seems to be a promising 4G mobile wireless networks candidate. In this thesis it is proposed the investigation, design and implementation of packet scheduling algorithms for the efficient management of the set of available radio resources, in time, frequency and spatial domains of the Mobile WiMAX networks. The proposed algorithms combine input metrics from physical layer and QoS requirements from upper layers, according to the crosslayer design paradigm. Proposed schedulers are evaluated by means of system level simulations, conducted in a system level simulation platform implementing the physical and medium access control layers of the IEEE802.16e standard.
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MacPherson, Douglass A. "Optical and radio frequency refractivity fluctuations from high resolution point sensors sea breezes and other observations". Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FMacPherson.pdf.
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Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 2007.Thesis Advisor(s): Donald L. Walters, Kenneth L. Davidson. "March 2007." Includes bibliographical references (p. 37-38). Also available in print.
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Pham, Edward Carleton University Dissertation Engineering Electrical. "SER prediction for transmission of PSAM 16-QAM in frequency selective fading channels". Ottawa, 1992.
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Gustafsson, Ebba y Rosanna Robersdottir. "Journalist och idealist : En jämförande kvalitativ studie om hur nyhets- respektive kulturjournalister ser på sitt demokratiska uppdrag". Thesis, Södertörns högskola, Journalistik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-32175.
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Syftet med denna studie är att undersöka hur kulturjournalister och nyhetsjournalister från Sveriges Radio ser på sitt demokratiska uppdrag och sin yrkesroll samt hur de upplever förutsättningarna för att uppfylla uppdraget och om dessa har förändrats. Vi är intresserade om nyhetsjournalisters och kulturjournalisters uppfattning i dessa frågor skiljer sig åt. Då vi har valt att göra en kvalitativ studie står de intervjuade journalisternas svar i centrum. I analysen kopplas resultatet till demokratimodeller, digitalisering, fältteori samt journalistikens logiker. Resultatet av studien visar att gemensamt för båda gruppers syn på det demokratiska uppdraget är viljan att förmedla information och kunskap, vara tillgänglig och pedagogisk, verka självständigt samt att ge plats åt lyssnarnas åsikter eller fungera som spegel. Vad som skiljer grupperna åt är att nyhetsjournalisterna betonar uppgiften att vara opartisk och saklig, kritiskt granska makten samt ge människor verktyg att påverka. Kulturjournalisterna betonar i högre grad vikten av att bredda världsbilden, delge nya perspektiv, reflektera och analysera samt ge lyssnarna verktyg för att väcka nya tankegångar. Journalister anser att de i stort kan uppfylla uppdraget, men att möjligheterna och förutsättningarna har förändrats. Tempot har ökat, det råder en ökad konkurrens och några av kulturjournalisterna belyser personalnedskärningar och besparingar inom bolaget. Vår undersökning visar att definitionen av det demokratiska uppdraget i hög mån är kopplat till synen på yrkesrollen. Den största divergensen mellan grupperna är förhållningssättet till subjektivitet.
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Muñoz, Gallego David Alfonso. "Estimação da capacidade de redes sem fio do tipo Mesh". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261829.
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Orientador: Paulo CardieriDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: Este trabalho apresenta uma estimação da capacidade das redes sem fio tipo Mesh. As redes deste tipo têm topologias e padrões de tráfego únicos que as diferenciam das redes sem fio convencionais. Nas redes sem fio tipo mesh os nós atuam como clientes e como servidores e o tráfego e encaminhado para uma ou várias gateways em um modo multi-salto. A estimação da capacidade é baseada em estudos da Camada Física e MAC. Efeitos da propagação do canal são avaliados
Abstract: This work addresses the capacity of wireless mesh networks (WMN). This kind of networks has unique topologies and traffic patterns that differentiate them from conventional wireless networks. In WMN, the nodes act as clients and hosts and the traffic is forwarded to one or more gateways in a multihop fashion. The capacity estimation presented in this work is based on the physical and link layer investigation, using computer simulation
Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica
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Dumas, Dylan. "Nouvelles techniques de traitement du signal en radio-océanographie". Electronic Thesis or Diss., Toulon, 2022. http://www.theses.fr/2022TOUL0008.
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La mesure des courants marins de surface par radar HF soulève plusieurs problématiques au niveau de la calibration des radars, de la résolution spatiale et des signaux parasites. Le traitement conventionnel fonctionnant par balayage azimutal appelé formation de voie a une résolution angulaire limitée pour la plupart des radars à réseau de phase et les méthodes de traitement à haute résolution pour la recherche des directions d'arrivées produisent généralement des cartes lacunaires. Dans cette thèse nous proposons : a) une technique de traitement à haute résolution angulaire permettant d'obtenir des cartes pleines et peu bruitées ; b) une méthode de calibration automatique des antennes ; c) des méthodes de suppression des artefacts liés aux interférences radio et aux échos parasites. Ces méthodes, initialement prévues pour les radars à réseau de phase, ont été adaptées aux radars compacts CODAR dont la principale difficulté est la calibration en raison de la nature des antennes. Les mesures de courant obtenues avec ces nouvelles techniques ont été validées par des campagnes in situ avec des erreurs dans la fourchette basse de la littérature scientifiqueThe measurement of sea surface currents by HF radar raises several issues in terms of radar calibration, spatial resolution and parasite signals. Conventional azimuth scanning processing called beam forming has limited angular resolution for most phased array radar and high angular resolution processing methods called direction finding generally produce lacunary maps. In this thesis we propose : a) a high angular resolution processing technique based on direction finding algorithm allowing to obtain full and low-noise maps ; b) an automatic antenna calibration method ; c) other methods to removing artifacts related to radio frequency interference and clutter echoes. These methods, initially planned for phased array radars, have been adapted to compact radars called CODAR where the main difficulty is the calibration due to the nature of the antennas. The measurements obtained with these new techniques have been validated with in situ campaigns with errors in the low range of the scientific literature
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Ribeiro, Diogo Carlos Alcobia. "Analog-digital neasurement system for software-defined radios". Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/8849.
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Mestrado em Engenharia Eléctrónica e TelecomunicaçõesEsta disserta c~ao insere-se na area de metrologia de r adio-frequ^encia, procurando colmatar a actual lacuna de instrumentos capazes de caracterizar r apida e e cazmente um componente anal ogico-digital, tal como uma ADC ou DAC. Estes componentes s~ao elementos chave da concep c~ao de arquitecturas Software-De ned Radio (SDR). O conceito de SDR de ne um r adio que seja totalmente adapt avel por software, atrav es da transi c~ao de blocos do dom nio anal ogico para o dom nio digital. Assim sendo, a adop c~ao destas arquitecturas r adio ir a ser cada vez mais utilizada de forma a responder a crescente necessidade de receber diversos tipos de comunica c~ao num unico terminal. Neste trabalho prop~oem-se a implementa c~ao de um instrumento que caracterize componentes anal ogico-digitais da mesma forma que o tradicional e popular Vector Network Analyzer (VNA) faz para componentes anal ogicos. Procura-se fornecer a um projectista de r adio, uma ferramenta que permita prever o desempenho de um componente anal ogico-digital do ponto de vista de r adio, de forma a facilitar o projecto de novos e mais complexos sistemas SDR. A implementa c~ao proposta pretende caracterizar componentes na banda de frequ^encias dos 40 aos 1000 MHz. Diversos ensaios foram realizados de forma a mostrar a comunidade cient ca a mais-valia deste instrumento.
This thesis is inserted into the Radio-Frequency metrology, it pursuits to ful l the current gap of instrumentation able to characterize analog-digital components, as ADC or DAC's, in a quickly and e ective form. These analog-digital components are the key to the conception of Software-De ned Radio (SDR) architectures. The SDR concept de nes a radio system totally implemented by means of software, where the of most the components operate in digital domain. Therefore, these architectures are becoming more and more used due to the growing need of receiving di erent kinds of communications in only one terminal. This paper tries to set up an instrument capable of characterize mixeddomain components as the tradicional and popular VNA can do with analog components. It is tried to built a new brand tool that can give to the radio designer, an easy form to create other SDR complex projects. The proposed instrument pretends to characterize components from 40 to 1000MHz bandwidth. Several tests were made in order to show its added value to the scienti c community.
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Drouart, Guillaume. "Relation noyau actif et histoire de la formation d'étoiles dans les radio galaxies distantes". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00923182.
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Les radio galaxies sont les candidats préférentiels pour comprendre la formation et l'évolution des galaxies sur une grande échelle de temps. Observées jusqu'à z>5 en raison de leur brillance, elles sont abritées par des galaxies elliptiques géantes. L'émission radio révèle la présence d'un trou noir supermassif. Un tore de poussière entourant le noyau actif de galaxie (AGN) agit comme un coronographe naturel permettant alors l'étude de la galaxie hôte. L'objectif de cette thèse est de déterminer l'évolution de la composante stellaire en présence d'un AGN. La décomposition est faite à partir de la distribution spectrale d'énergie (SED) de l'UV au submillimétrique en utilisant le code d'évolution de galaxies PEGASE.3 et un code d' AGN, les deux modélisant l'émission de la poussière par transfert radiatif.En premier lieu, nous présentons le projet HeRGE, 70 radio galaxies observées avec Herschel, qui permet de mesurer leurs luminosités totales infrarouges, comparables à celles des ULIRG. Une décomposition de la luminosité infrarouge entre l'émission AGN et un modèle de starburst est proposée pour l'ensemble de l'échantillon. Ces luminosités élevées sont interprétées en termes de taux d'accrétion et de formation d'étoiles, favorisant la croissance du trou noir par rapport à la galaxie hôte.En second lieu, l'orientation du jet par rapport au tore est contrainte à partir de l'infrarouge moyen et du rapport des émissions radio des lobes (isotrope, 500MHz) et du coeur (anisotrope, 20GHz). Ces observations en accord avec le modèle d'unification permettent d'évaluer le facteur d'absorption Av, l'inclinaison du tore et de contraindre le facteur de Lorentz.Une sélection de 12 radio galaxies observées de l'UV au sub-mm est analysée avec PEGASE.3 et un modèle d'AGN. Une seule composante stellaire est insuffisante. Seules deux composantes (une évoluée et massive, et une jeune issue d'un starburst) permettent un ajustement significatif de la SED complète. La composante évoluée est très massive (environ 10^12 msun) formée sur une courte période de temps (<10^9 ans). La composante jeune (<4.10^7 ans), moins massive (environ 10^11 msun), confirme un processus épisodique de croissance par sursauts. Ces résultats sont des contraintes fortes pour les modèles de formation de galaxies. La relation avec le noyau actif reste encore à préciser. Les projets d'observations complémentaires, optique et mm, permettront de confirmer ces résultats.
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Dalla'Rosa, Alexandre. "Modelagem e otimização da localização de transmissores em ambientes internos de comunicação sem fio". Florianópolis, SC, 2007. http://repositorio.ufsc.br/xmlui/handle/123456789/90268.
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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.Made available in DSpace on 2012-10-23T07:53:21Z (GMT). No. of bitstreams: 0
O foco principal desta tese está dirigido ao estudo e à aplicação do Método da Modelagem por Linhas de Transmissão (TLM) para a caracterização do canal de propagação em ambientes internos. O trabalho aborda também a localização ótima de transmissores, e para isto, é realizado o estudo de dois métodos matemáticos: o Método da Correlação Espacial (Método da Krigagem) e o Método dos Algoritmos Genéticos. São apresentados os detalhes fundamentais do TLM em sua versão bidimensional e tridimensional, para o uso em meios não-homogêneos e com perdas. São abordados os principais fenômenos da interação onda / estrutura, assim como são propostas soluções viáveis para a realização de cálculos de mapeamento eletromagnético e otimização da localização de transmissores em ambientes internos. O caráter inédito deste trabalho é centrado no desenvolvimento de uma técnica, baseada no uso do TLM e do Método da Krigagem, para o auto-planejamento de sistemas internos de radiocomunicação através de uma temática simples, prática, clara e eficiente. Nove exemplos de aplicação são apresentados para avaliação da capacidade da técnica desenvolvida, priorizando a análise de casos onde os métodos tradicionais são ineficientes. Os resultados das simulações foram altamente satisfatórios, mostrando assim a eficácia dos métodos como ferramenta de cálculo e solução destes tipos de problemas. The main focus of this dissertation is related to the applications of the Transmission Line Modeling Method (TLM) in order to characterize indoor radio propagation channels. This work also leads with the optimal transmitters locations in indoor environments, and for these analysis, two mathematical methods were applied: the Spatial Correlation Meta-Model (Kriging) and the Genetic Algorithms Method. The main aspects of TLM are presented for bi-dimensional and tri-dimensional evaluations applied to non-homogeneous media with losses. The main phenomena about the wave / structure interactions are illustrated and after that viable solutions are proposed for the success of electromagnetic mapping and optimal transmitter's location in indoor environments. The central point of this work is concerned with the development of a technique based on the use of the TLM and the Kriging Method for the auto-planning of indoor radio communication systems. Nine examples of applications are givem to show the developed technique potentialities, specially for cases where traditional methods are inefficient. The simulations results had been highly satisfactory showing the effectiveness of the methods as tools to provide solutions for these kinds of problems.
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Ben, slimen Yosra. "Knowledge extraction from huge volume of heterogeneous data for an automated radio network management". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE2046.
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En vue d’aider les opérateurs mobiles avec la gestion de leurs réseaux d’accès radio, trois modèles sont proposés. Le premier modèle est une approche supervisée pour une prévention des anomalies. Son objectif est de détecter les dysfonctionnements futurs d’un ensemble de cellules en observant les indicateurs clés de performance considérés comme des données fonctionnelles. Par conséquent, en alertant les ingénieurs et les réseaux auto-organisés, les opérateurs mobiles peuvent être sauvés d’une dégradation de performance de leurs réseaux. Le modèle a prouvé son efficacité avec une application sur données réelles qui vise à détecter la dégradation de capacité, les problèmes d’accessibilités et les coupures d’appel dans des réseaux LTE.A cause de la diversité des technologies mobiles, le volume de données qui doivent être quotidiennement observées par les opérateurs mobiles devient énorme. Ce grand volume a devenu un obstacle pour la gestion des réseaux mobiles. Le second modèle vise à fournir une représentation simplifiée des indicateurs clés de performance pour une analyse plus facile. Du coup, un modèle de classification croisée pour données fonctionnelles est proposé. L’algorithme est basé sur un modèle de blocs latents dont chaque courbe est identifiée par ses composantes principales fonctionnelles. Ces dernières sont modélisées par une distribution Gaussienne dont les paramètres sont spécifiques à chaque bloc. Les paramètres sont estimés par un algorithme EM stochastique avec un échantillonnage de Gibbs. Ce modèle est le premier modèle de classification croisée pour données fonctionnelles et il a prouvé son efficacité sur des données simulées et aussi sur une application réelle qui vise à aider dans l’optimisation de la topologie des réseaux mobiles 4G.Le troisième modèle vise à résumer l’information issue des indicateurs clés de performance et aussi des alarmes réseaux. Un modèle de classification croisée des données mixtes : fonctionnelles et binaires est alors proposé. L’approche est basé sur un modèle de blocs latents et trois algorithmes sont comparés pour son inférence : EM stochastique avec un échantillonneur de Gibbs, EM de classification et EM variationnelle. Le modèle proposé est le premier algorithme de classification croisée pour données fonctionnelles et binaires. Il a prouvé son efficacité sur des données simulées et sur des données réelles extraites à partir de plusieurs réseaux mobiles 4GIn order to help the mobile operators with the management of their radio access networks, three models are proposed. The first model is a supervised approach for mobile anomalies prevention. Its objective is to detect future malfunctions of a set of cells, by only observing key performance indicators (KPIs) that are considered as functional data. Thus, by alerting the engineers as well as self-organizing networks, mobile operators can be saved from a certain performance degradation. The model has proven its efficiency with an application on real data that aims to detect capacity degradation, accessibility and call drops anomalies for LTE networks.Due to the diversity of mobile network technologies, the volume of data that has to be observed by mobile operators in a daily basis became enormous. This huge volume became an obstacle to mobile networks management. The second model aims to provide a simplified representation of KPIs for an easier analysis. Hence, a model-based co-clustering algorithm for functional data is proposed. The algorithm relies on the latent block model in which each curve is identified by its functional principal components that are modeled by a multivariate Gaussian distribution whose parameters are block-specific. These latter are estimated by a stochastic EM algorithm embedding a Gibbs sampling. This model is the first co-clustering approach for functional data and it has proven its efficiency on simulated data and on a real data application that helps to optimize the topology of 4G mobile networks.The third model aims to resume the information of data issued from KPIs and also alarms. A model-based co-clustering algorithm for mixed data, functional and binary, is therefore proposed. The approach relies on the latent block model, and three algorithms are compared for its inference: stochastic EM within Gibbs sampling, classification EM and variational EM. The proposed model is the first co-clustering algorithm for mixed data that deals with functional and binary features. It has proven its efficiency on simulated data and on real data extracted from live 4G mobile networks
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Silva, Nelson José Valente da. "Reconfigurable transmitters for software-defined radios". Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11788.
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Doutoramento em Engenharia ElectrotécnicaFlexible radio transmitters based on the Software-Defined Radio (SDR) concept are gaining an increased research importance due to the unparalleled proliferation of new wireless standards operating at different frequencies, using dissimilar coding and modulation schemes, and targeted for different ends. In this new wireless communications paradigm, the physical layer of the radio transmitter must be able to support the simultaneous transmission of multi-band, multi-rate, multi-standard signals, which in practice is very hard or very inefficient to implement using conventional approaches. Nevertheless, the last developments in this field include novel all-digital transmitter architectures where the radio datapath is digital from the baseband up to the RF stage. Such concept has inherent high flexibility and poses an important step towards the development of SDR-based transmitters. However, the truth is that implementing such radio for a real world communications scenario is a challenging task, where a few key limitations are still preventing a wider adoption of this concept. This thesis aims exactly to address some of these limitations by proposing and implementing innovative all-digital transmitter architectures with inherent higher flexibility and integration, and where improving important figures of merit, such as coding efficiency, signal-to-noise ratio, usable bandwidth and in-band and out-of-band noise will also be addressed. In the first part of this thesis, the concept of transmitting RF data using an entirely digital approach based on pulsed modulation is introduced. A comparison between several implementation technologies is also presented, allowing to state that FPGAs provide an interesting compromise between performance, power efficiency and flexibility, thus making them an interesting choice as an enabling technology for pulse-based all-digital transmitters. Following this discussion, the fundamental concepts inherent to pulsed modulators, its key advantages, main limitations and typical enhancements suitable for all-digital transmitters are also presented. The recent advances regarding the two most common classes of pulse modulated transmitters, namely the RF and the baseband-level are introduced, along with several examples of state-of-the-art architectures found on the literature. The core of this dissertation containing the main developments achieved during this PhD work is then presented and discussed. The first key contribution to the state-of-the-art presented here consists in the development of a novel ΣΔ-based all-digital transmitter architecture capable of multiband and multi-standard data transmission in a very flexible and integrated way, where the pulsed RF output operating in the microwave frequency range is generated inside a single FPGA device. A fundamental contribution regarding the simultaneous transmission of multiple RF signals is then introduced by presenting and describing novel all-digital transmitter architectures that take advantage of multi-gigabit data serializers available on current high-end FPGAs in order to transmit in a time-interleaved approach multiple independent RF carriers. Further improvements in this design approach allowed to provide a two-stage up-conversion transmitter architecture enabling the fine frequency tuning of concurrent multichannel multi-standard signals. Finally, further improvements regarding two key limitations inherent to current all-digital transmitter approaches are then addressed, namely the poor coding efficiency and the combined high quality factor and tunability requirements of the RF output filter. The followed design approach based on poliphase multipath circuits allowed to create a new FPGA-embedded agile transmitter architecture that significantly improves important figures of merit, such as coding efficiency and SNR, while maintains the high flexibility that is required for supporting multichannel multimode data transmission.
Transmissores de rádio flexíveis baseados no conceito do Rádio Definido por Software (SDR) estão a receber uma crescente importância de investigação essencialmente devido à proliferação sem precedentes de novos standards de comunicações wireless que trabalham em frequências diferentes, usando esquemas de modulação e codificação dissimilares, estando direcionados para os mais diversos fins. Neste novo paradigma de comunicações wireless, a camada física do transmissor rádio tem de ser capaz de suportar a transmissão simultânea de sinais provenientes de diferentes standards, operando em diferentes bandas de frequências e com diferentes ritmos de transmissão, o que na prática é muito difícil ou muito ineficiente de implementar utilizando abordagens convencionais. Contudo, os últimos desenvolvimentos nesta área incluem novas arquiteturas de transmissão inteiramente digitais onde o datapath do rádio é digital desde a banda base até ao RF. Tal conceito tem uma elevada flexibilidade e representa um passo importante para o desenvolvimento de transmissores baseados em SDR. No entanto, a implementação de tal rádio para cenários de comunicação reais é uma tarefa desafiadora, onde algumas limitações chave estão ainda impedindo uma maior adopção deste conceito. Esta tese tem como principal objetivo o de investigar algumas destas limitações, propondo e implementando arquiteturas inovadoras de transmissão inteiramente digitais com inerente elevada flexibilidade e integração, e onde melhorar importantes figuras de mérito, tais como a eficiência de codificação, a relação sinal-ruído, a largura de banda utilizável e o ruído dentro e fora da banda também serão abordadas. Na primeira parte deste trabalho é introduzido o conceito de transmissão de dados RF utilizando uma abordagem totalmente digital, baseada em modulação por impulsos. Uma comparação entre diversas tecnologias de implementação é também apresentada, permitindo afirmar que as FPGAs actuais oferecem um compromisso interessante entre desempenho, eficiência de energia e flexibilidade, tornando-as uma escolha interessante como uma tecnologia de implementação com elevado potencial para transmissores completamente digitais baseados em moduladores pulsados. Após esta discussão são apresentados os conceitos fundamentais inerentes aos moduladores pulsados e introduzidos os avanços relativos a transmissores RF modulados por pulsos, juntamente com vários exemplos de arquiteturas do estado da arte encontrados na literatura. Em seguida, o núcleo desta tese contendo os principais desenvolvimentos alcançados durante este trabalho de doutoramento é apresentado e discutido. O primeiro contributo fundamental para o estado da arte aqui apresentado consiste no desenvolvimento e integração em FPGA de uma nova arquitetura de transmissão inteiramente digital, baseada em moduladores ΣΔ e dotada de uma elevada flexibilidade e integração, sendo capaz de transmitir dados de multiplos standards e em multiplas bandas de RF. Uma segunda contribuição chave relativa à transmissão simultânea de vários sinais RF é então introduzida, sendo apresentadas e descritas novas arquiteturas de transmissão de sinal RF inteiramente digitais, as quais tiram proveito de serializadores de dados multi-gigabit disponíveis em FPGAs atuais de alto desempenho. Melhorias adicionais a esta abordagem permitiram desenvolver uma arquitetura de transmissão com duas fases de conversão na frequência, a qual permite a transmissão concorrente de sinais multistandard e multicanal com ajuste fino na frequência. Por ultimo, foram ainda investigadas diversas técnicas que visam reduzir duas limitações fundamentais inerentes aos actuais transmissores completamente digitais, nomeadamente, a baixa eficiência de codificação dos moduladores pulsados e o elevado fator de qualidade combinado com elevados requisitos de adaptabilidade na frequencia do filtro de reconstrução do sinal RF a transmitir. A abordagem seguida baseada em multiplos caminhos polifásicos permitiu desenvolver uma nova arquitetura de transmissão integrada em FPGA que melhora de forma significativa importantes figuras de mérito, tais como a eficiência de codificação e SNR, enquanto mantém a elevada flexibilidade que é necessária para suportar a transmissão de dados multimodo e multicanal.
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Leonardo, Elvio João. "Produto e razão de variáveis generalizadas de desvanecimento e aplicações em desempenho de sistemas de comunicações = Product and ratio of generalized fading variables and applications in the performance of communication systems". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261025.
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Orientador: Michel Daoud YacoubTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica
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Nunes, Adailton Antônio Galiza 1988. "Projeto e análise de desempenho de simuladores para canais de desvanecimento alpha-mu". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259345.
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Orientador: José Cândido Silveira Santos FilhoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica
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Senol, Gokberk. "Performance Analysis Of A Digital Communication System On Sea Platforms". Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615134/index.pdf.
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The transmission rate and reliability are the most crucial elements of a communication system on sea platforms. In this thesis, the performance of a high speed and reliable communication system that can be used on ship to ship sea
platforms will be evaluated.
The two ray channel model is used in order to characterize the channel considering the refraction and reflection. Using the channel model, the path loss and the Shannon channel capacities are obtained for different systems.
In order to increase the system performance, frequency diversity technique is used and a detailed comparison of diversity combining techniques is provided.
As an alternative to Shannon channel capacity, cut off rate analysis is considered to get more realistic results about the rate of the communication system in that it takes modulation into account and the results are compared with the channel capacity. Block fading model and jamming effects on the achievable rate of the system is considered for different linear modulation techniques.
Finally, an OFDM system design is given as an example using the tools obtained in this work.