John N. Tsitsiklis, Dimitri P. Bertsekas. / Bibliography: leaf 5. / "August 1984." / DARPA Contract No. ONR-N00014-75-C-1183

by M. Sidi, A. Segall. / Bibliography: p. 146-148. / Research supported by ARPA Contract N00014-75-C-1183, ONR Contract ONR-N)))14-77-C-0532.

by Dimitri P. Bertsekas. / Bibliography: p. 55-56. / "December 1981." / Defense Advanced Research Projects Agency contract No. ONR-N00014-75-C-1183

Robert G. Gallager. / Caption title. / Includes bibliographical references. / Supported in part by ARPA under Grant ONR/N00014-75-C-1183 National Science Foundation Grant NSF/ENG76-24447

Moshe Sidi, Adrian Segall. / Bibliography: leaf 8. / "Contract ONR/N00014-77-C-0532"

Thesis (MScEng)--Stellenbosch University, 2004. / Full text to be digitised and attached to bibliographic record. / ENGLISH ABSTRACT: The increase in the complexity and functionality of new satellites leads to a growing demand for a digital communication system operating at a much higher bit rate than before. The main purpose of this thesis is to address precisely this problem. The theory as well as a practical high speed system are custom-developed. The goal of this thesis is not to reinvent the wheel, but to use off-the-shelf products as far as possible. This system demonstrates that a very high data rate is not out of reach for a developer with limited funds. The secondary goal is to understand the operation of this communication system. The emphasis is on the inaccuracies in the system. A design tool is created to act as a vehicle for understanding the influence of a single variable on the performance of the entire system. / AFRIKAANSE OPSOMMING: Die toename in die kompleksiteit en funksionaliteit van nuwe satelliete lei tot die groeiende behoefte aan 'n digitale kommunikasiestelsel wat teen "n heelwat hoër bis spoed funksioneer. Die hoofdoel van hierdie tesis is om juis hierdie probleem aan te spreek. Die teorie en 'n praktiese hoëspoed stelsel is ontwikkel. Die doel van die tesis is nie om die wiel te herontdek nie maar om sover moontlik bestaande produkte in die ontwerp van die stelsel te gebruik. Die stelsel demonstreer dat 'n hoëspoed datatempo nie buite die bereik van 'n ontwikkelaar met beperkte fondse is nie. 'n Verdere doelwit is om die funksionering van die kommunikasie stelsel te begryp. Klem is gelê op die onakkuraathede in die kommunikasiestelsel. Ontwikkeling sagteware is geskep as "n metode om die invloed van "n enkele veranderlike op die werkverrigting van die stelsel as geheel te begryp.

Magister Scientiae - MSc / With the unprecedented growth of the communication industry that the world is experiencing, the demand from rural inhabitants for high quality communications at an economically affordable cost is growing. However, rural areas are rather restricted from deploying communication services due to the rough natural environment, and the shortage of rudimentary communication facilities and technical personnel. Appropriate models for building rural wireless networks and a concomitant simulation environment are, therefore, expected to enable the construction of technologically-optimal and economically-efficient networks in specified rural areas.The research has set up two independent models, one for the economic need and the other for the technical need of building networks in rural areas. One model was the Impact of Telecommunications Model, which disclosed the importance of building a wireless network in specified rural areas by choosing an economic parameter to forecast the profitability of the network. The other was the Service Model, which collected primitive data from given rural areas and abstracted these data by flowing them through four technical layers to form the predicted technical wireless network. Both of the models had been applied to real-world cases to demonstrate how to use them.A simulation environment was finally designed and implemented to realize the above two models for the sake of instantiation. This environment could simulate the specified rural network by constructing a wireless network on the invented areas and evaluating its quality and economic efficiency. It was written in Scilab simulation language, which was an open source. / South Africa

Orientador: José Antonio Siqueira Dias / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-19T07:47:20Z (GMT). No. of bitstreams: 1 Airoldi_Douglas_M.pdf: 6691455 bytes, checksum: c3353281e717bd0415dc9ce4a5762ba6 (MD5) Previous issue date: 2011 / Resumo: Este trabalho é parte de um projeto de pesquisa e desenvolvimento de uma rede de mini-medidores de energia, de baixíssimo custo, que se comunica com uma central, que armazena todas as informações relativas ao consumo de energia elétrica, de cada um dos pontos de consumo de uma residência. Ao fim de um período, fornece ao consumidor condições de analisar a distribuição do seu gasto com energia elétrica por ponto medido. Neste trabalho foi desenvolvido um sistema de comunicação de dados pela rede elétrica, também conhecida como Power Line Communication (PLC)). O hardware, de baixo custo, é composto por microcontrolador e um modem integrado que utiliza o processo Amplitude Shift Keying (ASK), com taxas de comunicação entre 600 e 1200 bps (bits por segundo). O firmware criado é composto de um protocolo que realiza a comunicação half-duplex entre duas estações de medição, permitindo ao transmissor da informação, saber se a mesma foi recebida com integridade / Abstract: This work is part of a research project and develops a network of mini-power meters, very low cost, which communicate with a central, which stores all information relating to the consumption of electricity, each of the points consumption of a residence. At one time, it gives the consumer the ability to analyze the distribution of its spending power by the measured point. We have developed a communication system for data grid, also known as Power Line Communication (PLC). The hardware, low cost, consists of microcontroller and an integrated modem that uses the process Amplitude Shift Keying (ASK), with communication rates between 600 and 1200 bps (bits per second). The firmware is created consisting of a protocol that performs half-duplex communication between two measuring stations, allowing the transmitter of information, whether it was received with integrity / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

[pt] A tendência de um rápido aumento nas taxas de transmissão utilizadas em sistemas de comunicações ópticas, impõe que sejam repensadas as tecnologias e princípios de fabricação dos diversos elementos de um sistema de transmissão ou de recepção. Em breve, sistemas operando em taxas superiores a 100Gbits/s serão uma realidade. Este trabalho propõe-se a analisar o problema da extração de relógio em receptores ópticos de alta capacidade. O processo, atualmente empregado, é completamente elétrico sendo dificultado devido a sensibilidade dos componentes eletrônicos à freqüência de operação. Apresenta-se neste trabalho um método de recuperação de relógio por processo óptico, utilizando-se como elemento fundamental um laser DFB multi- seção. Inicialmente será realizado um estudo teórico do fenômeno de auto-pulsação, pré-requisito para a extração de relógio por processo óptico. Em seguida serão apresentados e discutidos uma série de experimentos que demonstram a recuperação de relógio por processo óptico. A partir destas informações e das condições adequadas para a obtenção do fenômeno, implementa-se um set-up experimental utilizando-se um laser InGaAsP/InP DFB dupla-seção, a partir do qual obtém-se recuperação de relógio por processo óptico em 1,24Gbits/s e 2,48Gbits/s nos formatos RZ e NRZ. / [en] Today bit-rates increase quickly in optical communications sustems. New technologies and fabrication process discovers are fundamental to the development of several devices in the transmission and reception systems. Soon, optical communication systems working in 100Gbits/s will be a reality. This work intends to solve the problem of clock recovery in high capacitu optical receivers. The process employed nawadays is completely electrical. As it is known, electronics devices are limited in frequency, and won´t operate propely in such high bit-rates. In this work a optical clock recovery method is shown, using a multi-section laser, as main element. The first step will be the description of a theoretical study of the self- pulsation phenomenon, allowing the understanding of the mechanism of optical clock recovery. Afterwards a series of experiments that show optical clock recovery are preented and discussed. A experimental set-up is implemented, utilizing a InGsAsP/InP doublesection DFB laser, and optical clock recovery is obtained from 1,24Gbits/s and 2,48Gbits/s bit streams, in RZ and NRZ formats.

D.Ing. (Electrical And Electronic Engineering) / We address the issue of synchronization, using sync-words (or markers), for encoded data. We focus on data that is encoded using permutation codes or Reed-Solomon codes. For each type of code (permutation code and Reed-Solomon code) we give a synchronization procedure or algorithm such that synchronization is improved compared to when the procedure is not employed. The gure of merit for judging the performance is probability of synchronization (acquisition). The word acquisition is used to indicate that a sync-word is acquired or found in the right place in a frame. A new synchronization procedure for permutation codes is presented. This procedure is about nding sync-words that can be used speci cally with permutation codes, such that acceptable synchronization performance is possible even under channels with frequency selective fading/jamming, such as the power line communication channel. Our new procedure is tested with permutation codes known as distance-preserving mappings (DPMs). DPMs were chosen because they have de ned encoding and decoding procedures. Another new procedure for avoiding symbols in Reed-Solomon codes is presented. We call the procedure symbol avoidance. The symbol avoidance procedure is then used to improve the synchronization performance of Reed-Solomon codes, where known binary sync-words are used for synchronization. We give performance comparison results, in terms of probability of synchronization, where we compare Reed-Solomon with and without symbol avoidance applied.