Orientadores: Michel Daoud Yacoub, Jose Candido Silveira Santos Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-12T20:13:16Z (GMT). No. of bitstreams: 1 BarrosTercius_Hermano_M.pdf: 3346341 bytes, checksum: 1398a699b8f875964e6bee207c3bf263 (MD5) Previous issue date: 2008 / Resumo: Esta dissertação provê uma comparação detalhada entre diversas distribuições de desvanecimento de curto prazo, que são trabalhadas de forma a propiciar seus melhores ajustes para dados obtidos a partir de medições de campo. Tais distribuições incluem aquelas já bem conhecidas na literatura - como Rayleigh, Rice, Nakagami, Hoyt e Weibull - bem como dois modelos propostos recentemente, especificamente k-µ e h-µ. Primeiramente, é apresentado um embasamento teórico sobre estas distribuições. Em seguida, são fornecidos todos os detalhes da construção e dos ajustes dos parâmetros do aparato de medições, bem como os procedimentos de coleta dos dados. Então, os diversos resultados das medições são analisados. As análises são baseadas em um vasto espaço amostral, englobando 300 ambientes investigados. Sob a óptica de uma de jornada de medição tão ampla, é possível recomendar o uso adequado destas distribuições recém-propostas, nomeadamente k-µ e h-µ. Pelos resultados obtidos, pode-se constatar que uma melhora significativa no processo de ajuste de curva é obtida com a utilização destas distribuições, as quais podem ser úteis para uma modelagem adequada do ambiente de propagação das comunicações sem fio / Abstract: This thesis provides a thorough comparison among the various short term fading distributions, which are handled so as to give their best fit over data obtained from field measurements. Such distributions include those already well known in the literature - namely Rayleigh, Rice, Nakagami, Hoyt e Weibull - as well as two recently proposed models, namely k-µ and h-µ. Firstly, some theoretical background concerning these distributions are given. Then, the details of the construction and required parameters adjustments of the measurement apparatus as well as the data collection procedures are shown. Then, the various results of the measurements are analysed. The analyses are based on an ample sample space, encompassing 300 surveying sites. In the view of such a vast measurement campaign, it may be possible to recommend the adequate use of those newly proposed distributions, namely k-µ e h-µ. From our results, it is possible to see that a significant improvement in the curve fitting process can be seen with the use of these distributions, which may be useful for the adequate modelling of the wireless communications propagation environement / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Orientadores: Raul Vinhas Ribeiro, Maria Silvina Medrano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-08T21:31:35Z (GMT). No. of bitstreams: 1 Giansante_Moacir_M.pdf: 31760626 bytes, checksum: 1c3f355aabddb68180939401b269973f (MD5) Previous issue date: 2007 / Resumo: Este estudo apresenta uma metodologia para calcular os custos decorrentes de projetos de universalização de serviços de telecomunicações, conforme estabelece a legislação brasileira, denominados como custos líquidos em outras legislações. Tal conceito é baseado na obtenção dos custos evitáveis e para seu cálculo, os custos atribuídos ao cumprimento das obrigações devem ser alocados de forma a guardar relação com a atividade que o gerou bem como com a quantidade de serviços/produtos produzidos. A metodologia também deve ser capaz de capturar economias de escala e de escopo decorrentes de compartilhamento de recursos e de otimização das capacidades instaladas. Por isso, propõe-se um modelo que combine os conceitos de custos incrementais e de custos prospectivos de longo prazo de forma flexível e que permita a análise de diferentes projetos de universalização / Abstract: This study presents a methodology to calculate the net costs resulting from telecommunications universal services, in accordance with Brazilian legislation. Such a concept is based on the estimation of the avoidable costs due to universal obligations. In order to proceed with the calculations, the costs attributed to these obligations should be allocated to guard relation with the activity that generated them as well as with the quantity of service/productsproduced. ,The methodology also should be capable of capture scale and scope economies due to shared resources or capacities optimization. Theproposed model combines the concepts of incremental costs andforward-looking costs in aflexible manner to enable the analysis of different projects regarding universal service / Mestrado / Automação / Mestre em Engenharia Elétrica

Speech separation has long been an active research topic in the signal processing community with its importance in a wide range of applications such as hearable devices and telecommunication systems. It not only serves as a fundamental problem for all higher-level speech processing tasks such as automatic speech recognition, natural language understanding, and smart personal assistants, but also plays an important role in smart earphones and augmented and virtual reality devices. With the recent progress in deep neural networks, the separation performance has been significantly advanced by various new problem definitions and model architectures. The most widely-used approach in the past years performs separation in time-frequency domain, where a spectrogram or a time-frequency representation is first calculated from the mixture signal and multiple time-frequency masks are then estimated for the target sources. The masks are applied on the mixture's time-frequency representation to extract the target representations, and then operations such as inverse short-time Fourier transform is utilized to convert them back to waveforms. However, such frequency-domain methods may have difficulties in modeling the phase spectrogram as the conventional time-frequency masks often only consider the magnitude spectrogram. Moreover, the training objectives for the frequency-domain methods are typically also in frequency-domain, which may not be inline with widely-used time-domain evaluation metrics such as signal-to-noise ratio and signal-to-distortion ratio. The problem formulation of time-domain, end-to-end speech separation naturally arises to tackle the disadvantages in the frequency-domain systems. The end-to-end speech separation networks take the mixture waveform as input and directly estimate the waveforms of the target sources. Following the general pipeline of conventional frequency-domain systems which contains a waveform encoder, a separator, and a waveform decoder, time-domain systems can be design in a similar way while significantly improves the separation performance. In this dissertation, I focus on multiple aspects in the general problem formulation of end-to-end separation networks including the system designs, model architectures, and training objectives. I start with a single-channel pipeline, which we refer to as the time-domain audio separation network (TasNet), to validate the advantage of end-to-end separation comparing with the conventional time-frequency domain pipelines. I then move to the multi-channel scenario and introduce the filter-and-sum network (FaSNet) for both fixed-geometry and ad-hoc geometry microphone arrays. Next I introduce methods for lightweight network architecture design that allows the models to maintain the separation performance while using only as small as 2.5% model size and 17.6% model complexity. After that, I look into the training objective functions for end-to-end speech separation and describe two training objectives for separating varying numbers of sources and improving the robustness under reverberant environments, respectively. Finally I take a step back and revisit several problem formulations in end-to-end separation pipeline and raise more questions in this framework to be further analyzed and investigated in future works.

Social regulation, as applied specifically to the telecommunications sector, is a new phenomenon in most countries. It was only in the 1960s, with the establishment of regulatory agencies, that social regulation became important. The regulators are mandated by their country’s legislative and regulatory frameworks to meet social objectives. This study examined the extent to which ICASA protects consumers as it is mandated to do by the Electronic Communications Act 36 of 2005. The study found that ICASA has adopted mechanisms of protecting consumers, namely by conducting awareness campaigns, road shows and workshops in all the nine provinces of South Africa in order to educate and inform consumers about the procedures of lodging complaints and to make them aware of their rights. However, despite ICASA’s endeavours to ensure consumer protection, most consumers are neither aware of their rights and how to efficiently exercise them nor the procedures of lodging complaints. ICASA protects consumers to a reasonable extent but it can do more when the enduser and subscriber service charter regulations are finalised. / Communication Science / M. A. (International Communication)

Thesis (MA)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: This assignment investigates the bargaining relationship between multinational corporations (MNCs) and developing countries. The units of analysis of this study in Global Political Economy are MNCs (non-state actors) and nation-states. In the contemporary global production structure the 'balance of power' between MNCs and developing countries has shifted in favour of MNCs. Descriptive secondary sources were used to illustrate the MNC-State bargaining relationship in telecommunications privatisation in Sub-Saharan Africa. In the contemporary global economy nation-states only rarely still compete for territory, but rather for wealth-creating activities to be located within their borders. Important changes in the global production structure have resulted in the increased mobility and economic power of MNCs. These developments have affected the strategic relationship between MNCs and nation-states and the former have used their advantage to gain preferential treatment in the bargaining process. The nation-states are also competing amongst themselves for the investment and technology and knowledge transfers from these firms. Privatisation programmes in Sub-Saharan Africa have substantially increased MNC participation on the continent, which has been historically marginalised from global foreign direct investment receipts. Research has shown that MNC participation in infrastructure service provision is more efficient than government ownership. However, this does not constitute a loss of sovereignty, but rather emphasises the changing role of nation-states as facilitators of global market relations. On examination, the distinct bargaining relationship in telecommunications privatisation clearly illustrates the dependence of Sub-Saharan African countries on technologically advanced MNCs. Thus, the 'balance of power' has shifted more to MNCs in the global political economy. / AFRIKAANSE OPSOMMING: Hierdie navorsingswerkstuk ondersoek die bedingingsverhouding tussen multinasionale korporasies (MNKs) en ontwikkelende lande. Die ondersoekeenhede in die studie van die Globale Politieke Ekonomie is MNKs (nie-staatrolspelers) en regeringstate. In die huidige globale produksiestruktuur het die mag tussen MNKs en ontwikkelende lande verander sodat die MNKs nou die magsoorwig het. Beskrywende sekondêre bronne is gebruik om die MNK-regeringstaat se bedingingsverhouding in telekommunikasie privatisering in Sub-Sahara Afrika te illustreer. In die teenswoordige globale ekonomie kompeteer regeringstate selde met mekaar om territoriale mag, maar oorwegend om welvaartskeppende bedrywe binne hul grense aan te moedig. Belangrike veranderings in die globale produksiestruktuur het MNKs se mobiliteit en ekonomiese mag verhoog. Hierdie ontwikkelinge het die strategiese verhouding tussen MNKs en regeringstate verander. MNKs gebruik hierdie invloed om voordeel te trek uit regeringstate wat kompeteer vir belegging en die tegnologie- en kennisoordrag van hierdie korporasies. Privatiseringsprogramme in Sub-Sahara Afrika het MNK-deelname op die kontinent verhoog, wat histories gemarginaliseer is van buitelandse direkte belegging. Navorsing dui daarop dat MNKs se deelname in infrastruktuurdienslewering meer doeltreffend is, as wanneer dit onder staatsbeheer is. Dit lei egter nie tot 'n verlies aan soeweriniteit nie, maar beklemtoon die regeringstaat se veranderde rol as fasiliteerder van globale markverhoudinge. Die ondersoek na die uitsonderlike bedingingsverhouding in die privatisering van telekommunikasie beklemtoon Sub-Sahara Afrika se afhanklikheid van tegnologies-ontwikkelde MNKs. Die magsbalans het gevolglik na die MNKs oorskuif in die globale politieke ekonomie.

The objective of this dissertation is to propose circuit architectures and techniques for built-in test and calibration of phase-locked loops. The design of phase-locked loops is first investigated to achieve a robust performance over process, temperature, voltage corners with minimum overhead. Different design techniques including adding loop programmability, increasing area efficiency, reducing noise immunity, and increasing frequency coverage are discussed. Secondly, built-in testing of phase-lock loops using sensors are proposed for loop dynamic parameters and reference spur. An integrator is designed to extract the subtle response from the system so that target parameters can be predicted. Different testing methodologies are applied different specification testing as well. Finally, an on chip phase-locked loop design is implemented for reference spur calibration. The phase-locked loop is designed with a programmable reference spur range. A static phase offset detector is included to identify the optimal setting of reference spur in the feedback system. The integrated jitter performance is improved by the calibration mechanism. The results of this thesis serve as an on-chip built-in self-test and self-calibration solution for embedded phase-locked loops in a high integration system.

Submitted in fulfillment of the requirements for the degree of Doctor of Technology: Information Technology, Durban University of Technology, Durban, South Africa, 2015. / This thesis focuses on the development of an enhanced innovative secure mobile Internet voting system architecture that offers desirable security requirements to theoretically mitigate some of the intrinsic administrative and logistical challenges of voting, inter alia lack of mobility support for voters, voter inconvenience, election misconduct, and possible voter coercion often associated with the conventional poll-site voting system. Systems in existence have tended to revolve around the need to provide ubiquitous voting, but lack adequate control mechanism to address, in particular, the important security requirement of controlling possible coercion in ubiquitous voting. The research work reported in this thesis improves upon a well-developed Sensus reference architecture. It does so by leveraging the auto-coupling capability of near field communication, as well as the intrinsic merits of global positioning system, voice biometric authentication, and computational intelligence techniques. The leveraging of the combination of these features provides a theoretical mitigation of some of the security challenges inherent in electoral systems previously alluded to. This leveraging also offers a more pragmatic approach to ensuring high level, secure, mobile Internet voting such as voter authentication. Experiments were performed using spectral features for realising the voice biometric based authentication of the system architecture developed. The spectral features investigated include Mel-frequency Cepstral Coefficients (MFCC), Mel-frequency Discrete Wavelet Coefficients (MFDWC), Linear Predictive Cepstral Coefficients (LPCC), and Spectral Histogram of Oriented Gradients (SHOG). The MFCC, MFDWC and LPCC usually have higher dimensions that oftentimes lead to high computational complexity of the pattern matching algorithms in automatic speaker authentication systems. In this study, higher dimensions of each of the features were reduced per speaker using Histogram of Oriented Gradients (HOG) algorithm, while neural network ensemble was utilised as the pattern-matching algorithm. Out of the four spectral features investigated, the LPCC-HOG gave the best statistical results with an R statistic of 0.9257 and Mean Square Error of 0.0361. These compact LPCC-HOG features are highly promising for implementing the authentication module of the secure mobile Internet voting system architecture reported in this thesis. / D

Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2017-02-01T12:51:11Z No. of bitstreams: 1 Ricardo FialhoTafas Junior.pdf: 1902411 bytes, checksum: fc7842d9f339a60c5d0842dad71af8e3 (MD5) / Made available in DSpace on 2017-02-01T12:51:11Z (GMT). No. of bitstreams: 1 Ricardo FialhoTafas Junior.pdf: 1902411 bytes, checksum: fc7842d9f339a60c5d0842dad71af8e3 (MD5) Previous issue date: 2016-12-16 / Pontif?cia Universidade Cat?lica de Campinas ? PUC Campinas / There is a growing need to ensure information security in telecommunications systems. However, currently, most cryptographic techniques protect only the message and do not prevent the capture of the transmitted symbols, which could compromise the security of the information. Therefore, a new cryptographic technique is proposed in this work which obfuscates the signal in the physical layer, making eavesdropping more difficult. First of all, prior to transmission, a change of basis operation is applied on the signal and, then, an obfuscation operation is performed on the base-changed signal. Afterwards, the obfuscated signal is returned to the initial base and it is ready for transmission. On the receiver side, a basis change is performed again and the de-obfuscation operation is applied, followed by an operation to return the signal to its original base. This work evaluated the bit error rate due to wrong key application and the maximum code breaking time to assess the technique. In addition, to the application in data communication and information security systems, the technique can be applied to data buses to prevent product cloning. / Existe uma necessidade crescente em garantir a seguran?a da informa??o em sistemas de telecomunica??es. Contudo, atualmente, a maioria das t?cnicas de criptografia protege apenas a mensagem, n?o impedindo a captura do sinal correspondente aos s?mbolos transmitidos, o que pode comprometer a seguran?a da informa??o. Em fun??o disso, neste trabalho, prop?e-se uma nova t?cnica criptogr?fica, que promove o ofuscamento dos sinais na camada f?sica, dificultando a??es de espionagem. Primeiramente, antes da transmiss?o, aplica-se uma opera??o de mudan?a de base sobre o sinal e, em seguida, uma opera??o de ofusca??o sobre o sinal modificado. Na sequ?ncia, retorna-se ? base inicial e o sinal ofuscado est? pronto para transmiss?o. Na detec??o, executa-se novamente a mudan?a de base, aplica-se a opera??o de desofusca??o, seguida da opera??o para retornar ? descri??o do sinal ? base original. Este trabalho estimou a taxa de erro de bit por uso de chave errada e o tempo m?ximo de quebra do c?digo para avaliar a t?cnica. Al?m da aplica??o em sistemas de telecomunica??es, a t?cnica pode ser aplicada em barramentos de dados, para evitar roubo de software ou firmware, prevenindo clonagem de produtos.

Les enjeux majeurs des dispositifs hyperfréquences utilisés dans les systèmes de télécommunication modernes sont la montée en fréquence de fonctionnement, la miniaturisation des circuits et l’intégrabilité des composants.Grâce à l’émergence des métamatériaux et à la maîtrise des propriétés des ferrites, il est possible de développer nouveaux dispositifs répondant à ces nouvelles exigences de l’électronique embarquée.Cette thèse développe, à partir d’une ligne métamatériau HIW coplanaire basée sur un substrat de ferrite, un nouveau dispositif hyperfréquence non réciproque de faible encombrement, opérant à des fréquences situées entre 13 et 15 GHz.Les prototypes fabriqués et caractérisés sous de faibles valeurs de champ magnétique, présentent les performances caractéristiques d’un isolateur bande étroite: isolation supérieure à 30 dB, pertes d’insertion inférieures à 1 dB. / The main challenges of microwave devices used in modern telecommunication systems are the increase of the operating frequency, the circuit’s miniaturization and the integration of components.Thanks to the emergence of metamaterials and the control of the properties of ferrites, it is possible to develop new circuits that meet these new requirements for embedded electronics.This thesis investigates, from a coplanar HIW metamaterial line based on a ferrite substrate, a new non-reciprocal microwave device, operating in frequency range between 13 and 15 GHz.Prototypes were fabricated and characterized under low magnetic field. They achieved the characteristic performances of a narrow band isolator: isolation over 30 dB and insertion losses of less than 1 dB.

The enabling technologies and the issues of next-generation millimeter-wave wireless access network and 100G long-haul optical transport network were developed and identified. To develop a simple and cost-effective millimeter-wave optical-wireless system, all-round research on the technical challenges of optical millimeter-wave generation, transmission impairments compensation, and simple base station design were discussed. Several radio-over-fiber systems were designed to simultaneously deliver multi-band wireless services on a single optical infrastructure, enabling converged system control and quality maintenance in central office. For the 100G optical transport network, the issues related to successful implementations of transmitter, fiber link, and receiver of a 112-Gb/s polarization-division multiplexing-quadrature phase shift keying (PDM-QPSK) system were comprehensively explored. The experimental results based on the constructed 112-Gb/s testbed indicated that careful dispersion management can effectively increase nonlinearity tolerance. Furthermore, the special emphasis on the two impairments of the 100G network with reconfigurable optical add-drop multiplexers: passband narrowing and in-band crosstalk, was studied. The results demonstrated that these impairments can be readily predicted with proper experimental and simulation efforts.