Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Gee-Kung Chang; Committee Co-Chair: Jianjun Yu; Committee Member: John A. Buck; Committee Member: Joy Laskar; Committee Member: Umakishore Ramachandran; Committee Member: Ye Li

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Orientador: Yuzo Iano / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-24T09:55:18Z (GMT). No. of bitstreams: 1 Mesquita_OdairdosSantos_M.pdf: 8376051 bytes, checksum: 11a0307915c4b7e7e94393ba4f65c532 (MD5) Previous issue date: 2013 / Resumo: Nos últimos anos houve uma evolução das redes de telecomunicações no Brasil. A implantação de redes de fibra óptica tornou-se uma realidade dos centros urbanos bem como nas áreas rurais. Com a expansão dessas redes observa-se o surgimento e a necessidade de normatização das redes ópticas passivas. Entre essas redes passivas destaca-se a EPON (Ethernet Passive Optical Network) e a GPON (Gigabit-Capable Passive Optical Network). Com a expansão de redes de banda larga e de novos serviços ligados a ela, torna-se necessário a realização de estudos detalhados sobre a viabilidade técnica econômica e de aplicabilidade dessas redes. É por isso que desenvolvemos nesse trabalho um modelamento econômico financeiro sobre essas novas tecnologias. Esse modelamento permite escolher a tecnologia economicamente mais viável na implantação de projetos envolvendo as tecnologias GPON e/ou EPON. Esse projeto é baseado em um estudo de caso para um município do interior de São Paulo, Brasil. Durante o estudo realizamos um planejamento técnico econômico detalhado visando uma eventual implantação de uma dessas redes. Foi feita uma apresentação completa dessas tecnologias baseada no estudo de caso. Foi discutida a possibilidade de implantar esse projeto na cidade escolhida do interior de São Paulo ou em qualquer outra cidade brasileira / Abstract: In recent years there has been an evolution of telecommunications networks in Brazil. The implementation of fiber-optic networks has become a reality of urban centers and rural areas. With the expansion of these networks, we observed the emergence and the need for standardization of these passive optical networks. Among these networks, there are the EPON (Ethernet Passive Optical Network) and GPON (Gigabit-Capable Passive Optical Network). With the expansion of broadband networks and new services linked to them, it becomes necessary to conduct detailed studies of the technical and economic applicability of these networks. We developed in this project a careful financial economic modeling on these new technologies. This modeling technique allows choosing the best of these technologies (GEPON/EPON) and the one that is economically feasible. This project is based on a case study for the city of São Paulo, Brazil. During the study, we performed a detailed techno-economic planning aimed an eventual implementation of any of these networks. A complete presentation of these technologies was done based on this case study. It was also discussed the possibility of implementing this project in the chosen city of São Paulo or any other Brazilian city / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

While the capacity of multiple-input multiple-output (MIMO) systems has been explored in considerable detail, virtually all literature on this topic ignores electromagnetic considerations. This dissertation explores electromagnetic effects on the capacity performance of these multi-antenna architectures. Specifically, it examines the impact of superdirectivity for compact antenna arrays, the effect of antenna mutual coupling, and MIMO performance of multi-mode optical fiber with non-linear detection. Superdirectivity can lead to abnormally large capacity bounds in a MIMO communication system, especially when the antennas are placed close together. Because superdirective behavior is difficult to achieve in practice, this work formulates an approach for limiting the impact of superdirectivity by introducing finite ohmic loss into the capacity expressions. Results show that even a small amount of ohmic loss significantly affects the achievable system capacity and suppresses superdirective solutions. This formulation allows a more detailed examination of the capacity of MIMO systems for compact arrays. For channels which do not vary in time, placing antennas closer together generally reduces the system capacity. However, recent work has demonstrated that for a MIMO system operating in a fast fading environment where the transmitter and receiver know the channel covariance information, the capacity increases as antennas are placed near each other due to an increase in spatial correlation. Analysis of this behavior illustrates that when these capacity gains (due to closely spaced antennas) are observed the radiated power is also increased. Constraining the radiated power leads to superdirective solutions in which the ohmic loss constraint developed must be used to properly determine the capacity behavior of this system. Application of this constraint then leads to an optimum antenna spacing in contrast to the findings of previous research which indicate that antennas should be as close together as possible. Additionally, this section provides an analysis regarding the number of spatial modes that can be used for various system configurations. Recent research has shown that it is possible for MIMO communication techniques to be used with multimode optical fibers to increase the available distance-bandwidth. However, implementation of traditional MIMO schemes requires the use of coherent optical detection which can lead to high system complexity and cost. This dissertation proposes a multimode fiber MIMO system architecture which allows simultaneous transmission of unique streams to different users on the same fiber while using incoherent detection with amplitude and phase modulation at the transmitter. The resulting capacity scales nearly linearly with the number of transmitters and receivers. Because the architecture requires channel state information at the transmitter, a training scheme appropriate for use with optical intensity detection is also discussed.

Optical packet switching (OPS) is one of the more promising solutions for meeting the diverse needs of broadband networking applications of the future. By virtue of its small data traffic granularity as well as its nanoseconds switching speed, OPS can be used to provide connection-oriented or connectionless services for different groups of users with very different networking requirements. The optical buffer and the switch fabric are two of the most important components in an OPS router. In this research, novel designs for the optical buffer and switch fabric are proposed and experimentally demonstrated. In particular, an optical buffer that is based on a folded-path delay-line tree architecture will be discussed. This buffer is the most compact non-recirculating optical delay line buffer to date, and it uses an array of high-speed ON-OFF optical reflectors to dynamically reconfigure its delay within several nanoseconds. A major part of this research is devoted to the design and performance optimization of these high-speed reflectors. Simulations and measurements are used to compare different reflector designs as well as to determine their optimal operating conditions. Another important component in the OPS router is the switch fabric, and it is used to perform space switching for the optical packets. Optical switch fabrics are used to overcome the limitations imposed by conventional electronic switch fabrics: high power consumption and dependency on the modulation format and bit-rate of the signals. Currently, only those fabrics that are based on the broadcast-and-select architecture can provide truly non-blocking multicast services to all input ports. However, a major drawback of these fabrics is that they are implemented using a large number of optical gates based on semiconductor optical amplifiers (SOA). This results in large component count and high energy consumption. In this research, a new multicast-capable switch fabric which does not require any SOA gates is proposed. This fabric relies on a passive all-optical gate that is based on the Four-wave mixing (FWM) wavelength conversion process in a highly-nonlinear fiber. By using this new switch architecture, a significant reduction in component count can be expected.

The central objective of this thesis is to suggest and develop one simple, unified method for communication over optical fiber networks, valid for all values of dispersion and nonlinearity parameters, and for a single-user channel or a multiple-user network. The method is based on the nonlinear Fourier transform (NFT), a powerful tool in soliton theory and exactly solvable models for solving integrable partial differential equations governing wave propagation in certain nonlinear media. The NFT decorrelates signal degrees of freedom in such models, in much the same way that the Fourier transform does for linear systems. In this thesis, this observation is exploited for data transmission over integrable channels such as optical fibers, where pulse propagation is governed by the nonlinear Schr\"odinger (NLS) equation. In this transmission scheme, which can be viewed as a nonlinear analogue of orthogonal frequency-division multiplexing commonly used in linear channels, information is encoded in the nonlinear spectrum of the signal. Just as the (ordinary) Fourier transform converts a linear convolutional channel into a number of parallel scalar channels, the nonlinear Fourier transform converts a nonlinear dispersive channel described by a \emph{Lax convolution} into a number of parallel scalar channels. Since, in the spectral coordinates the NLS equation is multiplicative, users of a network can operate in independent nonlinear frequency bands with no deterministic inter-channel interference. Unlike most other fiber-optic transmission schemes, this technique deals with both dispersion and nonlinearity directly and unconditionally without the need for dispersion or nonlinearity compensation methods. This thesis lays the foundations of such a nonlinear frequency-division multiplexing system.

The central objective of this thesis is to suggest and develop one simple, unified method for communication over optical fiber networks, valid for all values of dispersion and nonlinearity parameters, and for a single-user channel or a multiple-user network. The method is based on the nonlinear Fourier transform (NFT), a powerful tool in soliton theory and exactly solvable models for solving integrable partial differential equations governing wave propagation in certain nonlinear media. The NFT decorrelates signal degrees of freedom in such models, in much the same way that the Fourier transform does for linear systems. In this thesis, this observation is exploited for data transmission over integrable channels such as optical fibers, where pulse propagation is governed by the nonlinear Schr\"odinger (NLS) equation. In this transmission scheme, which can be viewed as a nonlinear analogue of orthogonal frequency-division multiplexing commonly used in linear channels, information is encoded in the nonlinear spectrum of the signal. Just as the (ordinary) Fourier transform converts a linear convolutional channel into a number of parallel scalar channels, the nonlinear Fourier transform converts a nonlinear dispersive channel described by a \emph{Lax convolution} into a number of parallel scalar channels. Since, in the spectral coordinates the NLS equation is multiplicative, users of a network can operate in independent nonlinear frequency bands with no deterministic inter-channel interference. Unlike most other fiber-optic transmission schemes, this technique deals with both dispersion and nonlinearity directly and unconditionally without the need for dispersion or nonlinearity compensation methods. This thesis lays the foundations of such a nonlinear frequency-division multiplexing system.

Three 40/60-GHz optical-wireless bidirectional architectures are designed with a centralized light source in the central office based on wavelength reuse. Three super-broadband access networks are proposed and experimentally demonstrated for simultaneously delivering wired and wireless services over an optical fiber and an air link in a single transport platform. The transport feasibility in metro and wide-area access networks with multiple reconfigurable optical add-drop multiplexers (ROADMs) nodes is explored for 40-GHz and 60-GHz optical millimeter-wave signals. Additionally, the optical-wireless systems using the orthogonal frequency division multiplexing (OFDM) modulation format are analytically and experimentally demonstrated to mitigate the chromatic dispersion in optical fiber. This thesis also successfully implements the testbed trial for the delivery of uncompressed 270-Mb/s standard-definition television (SDTV) and 1.485-Gb/s high-definition television (HDTV) video signals over optical fiber and air links. The demonstration represents the first ever reported real applications over hybrid wired and wireless access networks, showing that our developed up-conversion schemes and designed architectures are highly suitable for super-broadband applications in next-generation optical-wireless access networks.

Orientadores: Hugo Enrique Hernández Figueroa, Arismar Cerqueira Sodré Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-20T11:51:13Z (GMT). No. of bitstreams: 1 Lona_DanielGrandin_M.pdf: 5547359 bytes, checksum: 1dfde15018aecd3aee7c7be413e9c669 (MD5) Previous issue date: 2012 / Resumo: O objetivo deste trabalho é avaliar a aplicabilidade da tecnologia Radio sobre Fibra (Radio over Fiber - RoF) em redes de sensores sem-fio (Wireless Sensor Networks - WSNs) e Wi-Fi. Inicialmente, realizou-se uma detalhada análise analítica de desempenho dos sistemas em função dos parâmetros típicos de equipamentos RoF, tais como: freqüência de operação, figura de ruído, ruído de intensidade relativa do laser, ruído shot do fotodetector, ruído térmico e modulação óptica. Os sistemas analisados foram então implementados em laboratório nas faixas de freqüência de 915 MHz e 2,4 GHz para WSN e Wi-Fi, respectivamente. Os parâmetros de desempenho medidos foram a indicação de intensidade de sinal recebida (Received Signal Strength Indication - RSSI), taxa de perda de pacotes (Packet Error Rate - PER) e vazão (Throughput) / Abstract: This works aims to evaluate the applicability of Radio over Fiber (RoF) technology in Wireless Sensor Networks (WSNs) and Wi-Fi networks. Initially, the system performance has been analytically evaluated as a function of diverse parameters from RoF pieces of equipment, such as: operation frequency, noise figure, relative intensity noise, shot noise of photodetector, thermal noise and optical modulation. Furthermore, the proposed RoF systems were experimentally implemented in laboratory at 915 MHz and 2.4 GHz bands for WSN and Wi-Fi, respectively. The performance metrics were Received Signal Strength Indication (RSSI), Packet Error Rate (PER) and throughput / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

In this thesis we provide a model for a bufferless optical burst switching (OBS) and an optical packet switching (OPS) network. The thesis is divided in three parts. <p><p>In the first part we introduce the basic functionality and structure of OBS and OPS networks. We identify the blocking probability as the main performance parameter of interest. <p><p>In the second part we study the statistical properties of the traffic that will likely run through these networks. We use for this purpose a set of traffic traces obtained from the Universidad Politécnica de Catalunya. Our conclusion is that traffic entering the optical domain in future OBS/OPS networks will be long-range dependent (LRD). <p><p>In the third part we present the model for bufferless OBS/OPS networks. This model takes into account the results from the second part of the thesis concerning the LRD nature of traffic. It also takes into account specific issues concerning the functionality of a typical bufferless packet-switching network. The resulting model presents scalability problems, so we propose an approximative method to compute the blocking probability from it. We empirically evaluate the accuracy of this method, as well as its scalability. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished