Concurrent cooperative transmission (CCT) occurs when a collection of power-constrained single-antenna radios transmit simultaneously to form a distributed multi-input and multi-output (DMIMO) link. DMIMO can be a means for highly reliable and low-latency cooperative routing, when the MIMO channel is exploited for transmit and receive diversity; in this context, the range extension benefit is emphasized. Alternatively, DMIMO can be a means for high-throughput ad hoc networking, when the MIMO channel is used with spatial multiplexing. In both cases, concatenated DMIMO links are treated. The key contribution of this dissertation is a method of pre-synchronization of distributed single-antenna transmitters to form a virtual antenna array, in the absence of a global clock, such as a global positioning system (GPS) receiver or a network time protocol (NTP) to provide reference signals for the synchronization. Instead, the reference for synchronization comes from a packet, transmitted by the previous virtual array and simultaneously received by all the cooperative transmitters for the next hop. The method is realized for two types of modulation: narrowband non-coherent binary frequency-shift keying (NCBFSK) and wideband orthogonal frequency division multiplexing (OFDM). The pre-synchronization algorithms for transmission are designed to minimize the root-mean-square (RMS) transmit time, sampling and carrier frequency error between cooperative transmitters, with low implementation complexity. Since CCT is not supported by any existing standard or off-the-shelf radios, CT must be demonstrated by using software-defined radios (SDRs). Therefore, another contribution is a fully self-contained and real-time SDR testbed for CCT-based networking. The NCBFSK and OFDM systems have been designed and implemented in C++ and Python programming languages in the SDR testbed, providing practical performance of the CCT-based systems.

Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 2003. / "January 2003" Includes bibliographical references (leaves 120-129).

Thesis (M.Sc. (Computer Science)) - Rhodes University, 2008.

The control of modern audio studios is complex. Audio mixing desks have grown to the point where they contain thousands of parameters. The control surfaces of these devices do not reflect the routing and signal processing capabilities that the devices are capable of. Software audio mixing desk editors have been developed that allow for the remote control of these devices, but their graphical user interfaces retain the complexities of the audio mixing desk that they represent. In this thesis, we propose a grid approach to audio mixing. The developed grid audio mixing desk editor represents an audio mixing desk as a series of graphical routing matrices. These routing matrices expose the various signal processing points and signal flows that exist within an audio mixing desk. The routing matrices allow for audio signals to be routed within the device, and allow for the device’s parameters to be adjusted by selecting the appropriate signal processing points. With the use of the programming interfaces that are defined as part of the Studio Connections – Total Recall SDK, the audio mixing desk editor was integrated with compatible DAW applications to provide persistence of audio mixing desk parameter states. Many audio studios currently use digital networks to connect audio devices together. Audio and control signals are patched between devices through the use of software patchbays that run on computers. We propose a double grid-based FireWire patchbay aimed to simplify the patching of signals between audio devices on a FireWire network. The FireWire patchbay was implemented in such a way such that it can host software device editors that are Studio Connections compatible. This has allowed software device editors to be associated with the devices that are represented on the FireWire patchbay, thus allowing for studio wide control from a single application. The double grid-based patchbay was implemented such that it can be hosted by compatible DAW applications. Through this, the double grid-based patchbay application is able to provide the DAW application with the state of the parameters of the devices in a studio, as well as the connections between them. The DAW application may save this state data to its native song files. This state data may be passed back to the double grid-based patchbay when the song file is reloaded at a later stage. This state data may then be used by the patchbay to restore the parameters of the patchbay and its device editors to a previous state. This restored state may then be transferred to the hardware devices being represented by the patchbay.

Digital audio network technologies are becoming more prevalent in audio related environments. Yamaha Corporation has created a digital audio network solution, named mLAN (music Local Area Network), that uses IEEE 1394 as its underlying network technology. IEEE 1394 is a digital network technology that is specifically designed for real-time multimedia data transmission. The second generation of mLAN is based on the Plural Node Architecture, where the control of audio and MIDI routings between IEEE 1394 devices is split between two node types, namely an Enabler and a Transporter. The Transporter typically resides in an IEEE 1394 device and is solely responsible for transmission and reception of audio or MIDI data. The Enabler typically resides in a workstation and exposes an abstract representation of audio or MIDI plugs on each Transporter to routing control applications. The Enabler is responsible for configuring audio and MIDI routings between plugs on different Transporters. A Hardware Abstraction Layer (HAL) within the Enabler allows it to uniformly communicate with Transporters that are created by various vendors. A plug-in mechanism is used to provide this capability. When vendors create Transporters, they also create device-specific plug-ins for the Enabler. These plug-ins are created against a Transporter HAL Application Programming Interface (API) that defines methods to access the capabilities of Transporters. An Open Generic Transporter (OGT) guideline document which models all the capabilities of Transporters has been produced. These guidelines make it possible for manufacturers to create Transporters that make use of a common plug-in, although based on different hardware architectures. The introduction of the OGT concept has revealed additional Transporter capabilities that are not incorporated in the existing Transporter HAL API. This has led to the underutilisation of OGT capabilities. The main goals of this investigation have been to improve the Enabler’s plug-in mechanism, and to incorporate the additional capabilities that have been revealed by the OGT into the Transporter HAL API. We propose a new plug-in mechanism, and a new Transporter HAL API that fully utilises both the additional capabilities revealed by the OGT and the capabilities of existing Transporters.

[pt] Esta tese pode ser segmentada em duas partes distintas, porém complementares. A primeira parte trata do problema que tange ao desenvolvimento da maioria dos sistemas de marcação d água digital: a necessidade de primeiramente selecionar a técnica de modulação não codificada que fará parte de uma arquitetura codificada. Assim, para proceder adequada seleção, os limitantes de desempenho das técnicas não codificadas são ferramentas importantes para otimização de sistemas codificados, objetivando operação próximo à capacidade. Esta parte da tese introduz um novo limitante inferior para técnicas binárias de marcação d água digital, fundamentado em uma simples equivalência com um sistema de comunicação binário. A segunda parte desta tese introduz uma nova metodologia para o projeto e análise de sistemas de marcação d água digital que, sob o ponto de vista da teoria da informação, incorpora a fragilidade e a robustez. A metodologia proposta é desenvolvida com foco no comportamento da curva de desempenho em sistemas codificados, e considera não somente o ganho de codificação, mas também a robustez e a fragilidade do sistema. Este novo conceito introduz a necessidade de revisitar o projeto de sistemas codificados de marcação digital para incorporar também os requisitos de robustez e/ou de fragilidade. Neste contexto, o código turbo atende de imediato aos requisitos para implementação de um sistema de marcação d água digital robusto, e um sistema frágil pode também ser implementado através da introdução de um esquema de polarização. Este novo esquema de polarização, com o emprego da codificação turbo, também permite a implementação de técnicas semi-frágeis e híbridas, alcançando a robustez e a fragilidade do sistema com apenas uma marcação d água. Resultados de simulação experimental apóiam a metodologia proposta, e possibilita o aprofundamento da discussão do proposto esquema de polarização em sistemas de marcação d água digital. / [en] This thesis can be segmented in two distinct but complementary parts. The first part addresses the problem pertinent to coded digital watermarking systems development require namely the selection of a (uncoded) modulation technique to be part of a coded architecture. Therefore, performance bounds for uncoded techniques are an important tool for coded system optimization, aiming at operation close to capacity. This part introduces a new performance lower bound for uncoded binary watermarking modulation techniques, based on a simple equivalence with a binary communication system, considering an additive gaussian attack model. New M-ary unidimensional and multidimensional Spread Spectrum based modulation techniques are introduced, including their improved versions. The performances of the proposed techniques are determined, and the performance lower bounds for the corresponding techniques classes are determined as well. The second part of this thesis, introduces a new methodology for the design and analysis of digital watermarking systems which, from an information theoretic point of view, incorporates robustness and fragility. The proposed methodology is developed by focusing on the probability of error versus watermark-to-noise ratio curve, describing the technique performance, and a scenario for coded techniques which takes into account not only the coding gain, but also the robustness or fragility of the system. This new concept requires that coded digital watermarking systems design be revisited to also include the robustness and fragility requirements. Turbo codes, which appropriately meet these requirements, can be used straightforwardly to construct robust watermarking systems. Fragile systems can also be constructed by introducing the idea of polarization scheme. This new idea has allowed the implementation of hybrid techniques achieving fragility and robustness with a single watermark embedding. Simulation results supports the introduced methodology and allowed us to enhance the discussion on the polarization scheme.

Esta dissertação investigou os principais obstáculos que os professores de Ciências encontram no uso das Tecnologias de Informação e Comunicação (TIC), em especial da Internet como recurso pedagógico. Esta se delineou como pesquisa qualitativa e têm como objetivo geral elaborar um guia de sugestões metodológicas com o uso de recursos digitais virtuais para auxiliar nas dificuldades identificadas junto aos professores de Ciências do colégio investigado. Para subsidiar o guia para o uso das TIC no ensino de Ciências, escolheu-se o referencial teórico da Aprendizagem Significativa e o modelo TPACK (Technological Pedagogical Content Knowledge). Investigou-se o grupo de professores de Ciências de uma escola da Rede Pública de Educação. O instrumento de pesquisa foi um roteiro de entrevista, elaborado e previamente validado, com questões sobre o que eles conheciam do uso das tecnologias no contexto de sua disciplina de ensino, suas dificuldades, anseios, impressões e se utilizavam metodologias com a presença das TIC. O conteúdo das entrevistas foi transcrito e examinado sob a ótica da Análise do Conteúdo e relacionados com os pressupostos da Aprendizagem Significativa e da literatura sobre o uso das TIC no contexto educacional. Os resultados encontrados mostram que as dificuldades da integração das tecnologias digitais (em especial o uso da Internet) no ensino de Ciências dentro da Rede Pública de Educação continuam a existir. A falta de infraestrutura e apoio ao uso das tecnologias são obstáculos presentes no discurso dos professores. Outro problema observado foi a falta de formação continuada específica para um uso significativo das TIC no contexto da aprendizagem em Ciências. Entretanto, o grupo entrevistado utilizava a Internet para preparar aulas, pesquisar temas atuais e organizar o planejamento pedagógico. Os professores afirmaram não utilizar a Internet no ambiente escolar com os estudantes e justificavam esta conduta pelas condições apresentadas no estabelecimento. A partir destes dados e da literatura analisada confeccionou-se o guia de sugestões metodológicas para o uso das TIC nas aulas de Ciências, também produto deste mestrado profissional. Este poderá ser um material potencialmente significativo para a formação continuada destes professores nesta área. Concluiu-se que a alfabetização tecnológica dos professores de Ciências progrediu, mas, ainda existe um caminho a ser percorrido para a plena apropriação das tecnologias como recursos em uma Aprendizagem Significativa. / This thesis had investigated the main obstacles that science teachers have when using Information and Communication Technologies (ICT), especially Internet, as a teaching resource. This was composed as a qualitative research and has as the main objective to develop a guide with methodological suggestions for using virtual digital resources, in order to assist in the difficulties identified altogether with Science teachers of the investigated school. For subsidize the guide for the use of ICT in Science teaching, we chose as theoretical basis from Meaningful Learning and TPACK model (Technological Pedagogical Content Knowledge). The group of Science teachers of a public school was investigated. The research instrument was an interview script; it was developed and validated beforehand, it had questions about what teachers would know about the use of technologies in the context of teaching their subjects, their difficulties, anxieties, impressions and methodologies used in the presence of ICT. The content of the interviews were transcribed and examined from the perspective of Content Analysis and related with assumptions of Meaningful Learning and the literature on the use of ICT in educational context. The results obtained have shown that the difficulties still are with integrating digital technologies (in particular, the use of Internet) with Science teaching in Public School. The lack of infrastructure and support for the use of technologies are obstacles presented by the teachers. Another problem they have mentioned was the lack of Service-learning in Teacher Education for a meaningful use of ICT in the context of learning Science. At the same time, the group interviewed made use of Internet to prepare their classes, making researches for current themes and organize educational planning. The teachers said they did not use Internet at school with students and justified this choice due to the [lack of] conditions presented in the establishment. From these data and the literature reviewed, a guide of methodological suggestions for the use of ICT in Science classes was created and it is also the product of this Master’s thesis. This can be a potentially significant material for the Continuing Education for these teachers in this area. It was concluded that technological literacy of Science teachers had progressed, but there is still a long way to go in order to acquire full appropriation of technologies as resources in a Meaningful Learning.

CNPq / Nesta tese abordamos técnicas de diversidade espacial e cooperativa em dois tipos de sistemas de comunicação sem fio: sistemas digitais e sistemas analógicos. No âmbito dos sistemas digitais, consideramos a transmissão entre nós de uma rede de sensores sem fio. Uma vez que estas redes são caracterizadas por um grande número de nós, cuja quantidade de energia disponível é restrita, focamos em esquemas eficientes sob o ponto de vista do consumo de energia. Para tanto, analisamos protocolos cooperativos e técnicas com múltiplas antenas procurando delinear a real eficiência dessas técnicas em cenários práticos de redes de sensores sem fio, onde levamos em consideração questões como condição de linha de visada entre os nós, o consumo dos circuitos de transmissão e recepção, a presença ou não do canal de retorno, restrições de perda de pacotes e atraso, além de possíveis não linearidades no consumo das baterias dos dispositivos. Nossos resultados mostram que algumas das conclusões da literatura podem se inverter quando parâmetros mais adequados são levados em conta. Além disso, detalhamos as regiões mais eficientes de operação para cada método de transmissão nas referidas redes. Por outro lado, no âmbito dos sistemas analógicos, consideramos sistemas de codificação analógica conjunta fonte-canal que realizam uma compressão da largura de banda. Tais sistemas têm apelo em cenários nos quais a complexidade e atraso podem ser fatores limitantes. Nesse caso, procuramos primeiramente aplicar o que já existe na literatura no contexto de canais sem fio, para então focar em esquemas cooperativos e de múltiplas antenas que reduzam a distorção no receptor, buscando aproximar o desempenho desses sistemas ao seu limite teórico. Nossos resultados mostram uma melhoria de desempenho quando a diversidade espacial e cooperativa são utilizadas. Além disso, a solução analógica proposta se aproxima do limitante superior de desempenho de um sistema digital prático, com a vantagem de oferecer menor complexidade e atraso, além de maior flexibilidade no projeto do sistema. / In this thesis we discuss spatial diversity and cooperative diversity techniques for two types of wireless communication systems: digital systems and analog systems. In the context of digital systems, we consider the transmission between nodes of a wireless sensor network. Since these networks are characterized by a large number of nodes, with limited amount of energy, we focus on efficient schemes from the point of view of the energy consumption. For this purpose, we analyze cooperative protocols and multiple antenna techniques trying to delineate the real effectiveness of these techniques in practical wireless sensor networks scenarios, where we consider issues such as line of sight, the energy consumption of the transmit and receive circuits, the availability or not of a feedback channel, packet loss and delay constraints, and possible nonlinearities in the battery consumption. Our results show that some of the conclusions of the literature can change if some of these parameters are taken into account. Furthermore, we detail the most efficient operation regions for each transmission method in such networks. On the other hand, in the context of analog systems, we consider analog joint source-channel coding systems performing bandwidth compression. Such systems are suitable for scenarios in which the complexity and delay can be limiting factors. In this case, we first apply some of the already existing concepts of the literature to the context of wireless channels, and then focus on cooperative schemes and multiple antenna techniques to reduce the distortion at the receiver, while trying to approximate the performance of these systems to their theoretical limit. Our results show a performance improvement when spatial and cooperative diversity are used. Moreover, the proposed analog solution approaches the upper bound performance of a practical digital system, with the advantage of lower complexity and delay, and more flexibility in the system design.

Esta dissertação investigou os principais obstáculos que os professores de Ciências encontram no uso das Tecnologias de Informação e Comunicação (TIC), em especial da Internet como recurso pedagógico. Esta se delineou como pesquisa qualitativa e têm como objetivo geral elaborar um guia de sugestões metodológicas com o uso de recursos digitais virtuais para auxiliar nas dificuldades identificadas junto aos professores de Ciências do colégio investigado. Para subsidiar o guia para o uso das TIC no ensino de Ciências, escolheu-se o referencial teórico da Aprendizagem Significativa e o modelo TPACK (Technological Pedagogical Content Knowledge). Investigou-se o grupo de professores de Ciências de uma escola da Rede Pública de Educação. O instrumento de pesquisa foi um roteiro de entrevista, elaborado e previamente validado, com questões sobre o que eles conheciam do uso das tecnologias no contexto de sua disciplina de ensino, suas dificuldades, anseios, impressões e se utilizavam metodologias com a presença das TIC. O conteúdo das entrevistas foi transcrito e examinado sob a ótica da Análise do Conteúdo e relacionados com os pressupostos da Aprendizagem Significativa e da literatura sobre o uso das TIC no contexto educacional. Os resultados encontrados mostram que as dificuldades da integração das tecnologias digitais (em especial o uso da Internet) no ensino de Ciências dentro da Rede Pública de Educação continuam a existir. A falta de infraestrutura e apoio ao uso das tecnologias são obstáculos presentes no discurso dos professores. Outro problema observado foi a falta de formação continuada específica para um uso significativo das TIC no contexto da aprendizagem em Ciências. Entretanto, o grupo entrevistado utilizava a Internet para preparar aulas, pesquisar temas atuais e organizar o planejamento pedagógico. Os professores afirmaram não utilizar a Internet no ambiente escolar com os estudantes e justificavam esta conduta pelas condições apresentadas no estabelecimento. A partir destes dados e da literatura analisada confeccionou-se o guia de sugestões metodológicas para o uso das TIC nas aulas de Ciências, também produto deste mestrado profissional. Este poderá ser um material potencialmente significativo para a formação continuada destes professores nesta área. Concluiu-se que a alfabetização tecnológica dos professores de Ciências progrediu, mas, ainda existe um caminho a ser percorrido para a plena apropriação das tecnologias como recursos em uma Aprendizagem Significativa. / This thesis had investigated the main obstacles that science teachers have when using Information and Communication Technologies (ICT), especially Internet, as a teaching resource. This was composed as a qualitative research and has as the main objective to develop a guide with methodological suggestions for using virtual digital resources, in order to assist in the difficulties identified altogether with Science teachers of the investigated school. For subsidize the guide for the use of ICT in Science teaching, we chose as theoretical basis from Meaningful Learning and TPACK model (Technological Pedagogical Content Knowledge). The group of Science teachers of a public school was investigated. The research instrument was an interview script; it was developed and validated beforehand, it had questions about what teachers would know about the use of technologies in the context of teaching their subjects, their difficulties, anxieties, impressions and methodologies used in the presence of ICT. The content of the interviews were transcribed and examined from the perspective of Content Analysis and related with assumptions of Meaningful Learning and the literature on the use of ICT in educational context. The results obtained have shown that the difficulties still are with integrating digital technologies (in particular, the use of Internet) with Science teaching in Public School. The lack of infrastructure and support for the use of technologies are obstacles presented by the teachers. Another problem they have mentioned was the lack of Service-learning in Teacher Education for a meaningful use of ICT in the context of learning Science. At the same time, the group interviewed made use of Internet to prepare their classes, making researches for current themes and organize educational planning. The teachers said they did not use Internet at school with students and justified this choice due to the [lack of] conditions presented in the establishment. From these data and the literature reviewed, a guide of methodological suggestions for the use of ICT in Science classes was created and it is also the product of this Master’s thesis. This can be a potentially significant material for the Continuing Education for these teachers in this area. It was concluded that technological literacy of Science teachers had progressed, but there is still a long way to go in order to acquire full appropriation of technologies as resources in a Meaningful Learning.

CNPq / Nesta tese abordamos técnicas de diversidade espacial e cooperativa em dois tipos de sistemas de comunicação sem fio: sistemas digitais e sistemas analógicos. No âmbito dos sistemas digitais, consideramos a transmissão entre nós de uma rede de sensores sem fio. Uma vez que estas redes são caracterizadas por um grande número de nós, cuja quantidade de energia disponível é restrita, focamos em esquemas eficientes sob o ponto de vista do consumo de energia. Para tanto, analisamos protocolos cooperativos e técnicas com múltiplas antenas procurando delinear a real eficiência dessas técnicas em cenários práticos de redes de sensores sem fio, onde levamos em consideração questões como condição de linha de visada entre os nós, o consumo dos circuitos de transmissão e recepção, a presença ou não do canal de retorno, restrições de perda de pacotes e atraso, além de possíveis não linearidades no consumo das baterias dos dispositivos. Nossos resultados mostram que algumas das conclusões da literatura podem se inverter quando parâmetros mais adequados são levados em conta. Além disso, detalhamos as regiões mais eficientes de operação para cada método de transmissão nas referidas redes. Por outro lado, no âmbito dos sistemas analógicos, consideramos sistemas de codificação analógica conjunta fonte-canal que realizam uma compressão da largura de banda. Tais sistemas têm apelo em cenários nos quais a complexidade e atraso podem ser fatores limitantes. Nesse caso, procuramos primeiramente aplicar o que já existe na literatura no contexto de canais sem fio, para então focar em esquemas cooperativos e de múltiplas antenas que reduzam a distorção no receptor, buscando aproximar o desempenho desses sistemas ao seu limite teórico. Nossos resultados mostram uma melhoria de desempenho quando a diversidade espacial e cooperativa são utilizadas. Além disso, a solução analógica proposta se aproxima do limitante superior de desempenho de um sistema digital prático, com a vantagem de oferecer menor complexidade e atraso, além de maior flexibilidade no projeto do sistema. / In this thesis we discuss spatial diversity and cooperative diversity techniques for two types of wireless communication systems: digital systems and analog systems. In the context of digital systems, we consider the transmission between nodes of a wireless sensor network. Since these networks are characterized by a large number of nodes, with limited amount of energy, we focus on efficient schemes from the point of view of the energy consumption. For this purpose, we analyze cooperative protocols and multiple antenna techniques trying to delineate the real effectiveness of these techniques in practical wireless sensor networks scenarios, where we consider issues such as line of sight, the energy consumption of the transmit and receive circuits, the availability or not of a feedback channel, packet loss and delay constraints, and possible nonlinearities in the battery consumption. Our results show that some of the conclusions of the literature can change if some of these parameters are taken into account. Furthermore, we detail the most efficient operation regions for each transmission method in such networks. On the other hand, in the context of analog systems, we consider analog joint source-channel coding systems performing bandwidth compression. Such systems are suitable for scenarios in which the complexity and delay can be limiting factors. In this case, we first apply some of the already existing concepts of the literature to the context of wireless channels, and then focus on cooperative schemes and multiple antenna techniques to reduce the distortion at the receiver, while trying to approximate the performance of these systems to their theoretical limit. Our results show a performance improvement when spatial and cooperative diversity are used. Moreover, the proposed analog solution approaches the upper bound performance of a practical digital system, with the advantage of lower complexity and delay, and more flexibility in the system design.