Thesis (Ph. D.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 382-398).

Цель работы – создание Web-приложения для взаимодействия с серверной частью, на которой запущен Discord-бот для прослушивания музыки из разных источников, включая российские музыкальные сервисы. Объектом выпускной квалификационной работы является VoIP-мессенджер Discord. Предметом выпускной квалификационной работы является Frontend часть Discord-бота для прослушивания музыки с разных источников с поддержкой web-интерфейса. В работе рассматривается предметная область, аналоги. Производится оценка и выбор технологий, архитектуры приложения. Описывается процесс разработки, трудности и подходы к их решению. Описывается тестирование и перспективы развития. / The goal of the work is to create a Web application for interacting with the server part, which runs a Discord bot for listening to music from various sources, including Russian music services. The object of the final qualifying work is the VoIP messenger Discord. The subject of the final qualifying work is the Frontend part of a Discord bot for listening to music from different sources with support for a web interface. The work examines the subject area and analogues. Technologies and application architecture are assessed and selected. The development process, difficulties and approaches to solving them are described. Testing and development prospects are described.

published_or_final_version / Architecture / Master / Master of Architecture

[pt] Os recentes avanços em tecnologias de reconhecimento, como fala, toque e gesto, deram origem a uma nova classe de interfaces de usuário que não apenas explora múltiplas modalidades de interação, mas também permite múltiplos usuários interagindo. O desenvolvimento de aplicativos com interações multimodais e multiusuários trazem desafios para a sua especificação e execução. A especificação de uma aplicação multimodal é comumente o foco das pesquisas em interação multimodal, enquanto a especificação de sincronismos audiovisuais geralmente é o foco das pesquisas em multimídia. Nesta tese, com o objetivo de auxiliar a especificação de tais aplicações, buscamos integrar conceitos dessas duas pesquisas e propomos estender linguagens multimídia com entidades de primeira classe para suportar recursos multiusuário e multimodais. Essas entidades foram instanciadas nas linguagens NCL e HTML. Para avaliar nossa abordagem, realizamos uma avaliação com desenvolvedores NCL e HTML para capturar indícios de aceitação das entidades propostas e suas sintaxes nessas linguagens. / [en] Recent advances in recognition technologies, such as speech, touch and gesture, have given rise to a new class of user interfaces that does not only explore multiple modalities but also allows for multiple interacting users. The development of applications with both multimodal and multiuser interactions arise new specification and execution issues. The specification of multimodal application is commonly the focus of multimodal interaction research, while the specification of the synchronization of audiovisual media is usually the focus of multimedia research. In this thesis, aiming to assist the specification of such applications, we propose to integrate concepts from those two research areas and to extend multimedia languages with first-class entities to support multiuser and multimodal features. Those entities were instantiated in NCL and HTML. To evaluate our approach, we performed an evaluation with NCL and HTML developers to capture evidences of their acceptance of the proposed entities and instantiations in those languages.

published_or_final_version / Architecture / Master / Master of Architecture

No description available.

Die zunehmende Gewöhnung von Benutzern an neue Interaktionskonzepte und Endgeräte ermöglicht deren Einführung in industriellen Umgebungen. Daraus folgen Anwendungsszena-rien, in denen es, selbst während der Bearbeitung einer einzelnen Arbeitsaufgabe, zu häufigen Änderungen in der Zusammensetzung der verwendeten Geräte kommt. Dies motiviert die Entwicklung migrierbarer Benutzungsschnittstellen (MUI). In diesem Beitrag stellen wir zu-nächst die anerkannte Theorie der MUIs vor, inklusive verschiedener Klassifikationsmerkma-le und spiegeln diese an den Anforderungen der Automatisierungstechnik. Anhand dessen diskutieren wir anschließend zwei Anwendungsszenarien. Die Analyse verwandter Arbeiten zeigt auf, dass existierende Ansätze nur eingeschränkt in diesen Szenarien eingesetzt werden können. Am Ende stellen wir eine Fallstudie vor, die die Anwendbarkeit von MUIs in industriel-len Prozessvisualisierungen demonstriert.:1. Einleitung 2. Migratorische Benutzungsschnittstellen 2.1 Einführung 2.2 Klassifikationsmerkmale 3. Anforderungen industrieller Visualisierungen an ein migratorisches UI 3.1 Anforderungen an Software und Engineering 3.2 Struktur und Funktionalität 3.3 Diskussion 4. Beispielhafte Anwendungsszenarien 5. Fallstudie 5.1 Existierende Prototypen 5.2 Konzeption einer Migrationslösung 6. Zusammenfassung und Ausblick / Due to familiarization of users with modern interaction concepts and devices, they become interesting for industrial environments as well. These devices enable use cases where users change the set of applied devices, even during handling one single task. This fosters the de-sign of migratory user interfaces (MUI) which can be transferred freely between devices, in order to follow according to a user’s device changes. Hence, in this paper the generally ac-cepted theory, including a set of identified classifiers for MUIs, is being analyzed with respect to the demands of the domain of industrial process visualizations. Moreover, we discuss two use cases. Our review of the related work revealed only a limited applicability in those use cases. In order to demonstrate an MUI’s usefulness in industrial process visualizations, we finally present our own case study.:1. Einleitung 2. Migratorische Benutzungsschnittstellen 2.1 Einführung 2.2 Klassifikationsmerkmale 3. Anforderungen industrieller Visualisierungen an ein migratorisches UI 3.1 Anforderungen an Software und Engineering 3.2 Struktur und Funktionalität 3.3 Diskussion 4. Beispielhafte Anwendungsszenarien 5. Fallstudie 5.1 Existierende Prototypen 5.2 Konzeption einer Migrationslösung 6. Zusammenfassung und Ausblick

Since the mid 1990’s, the wireless communications industry has witnessed explosive growth. The worldwide cellular and personal communication subscriber base surpassed 600 million users by late 2001, and the number of individual subscribers surpassed 2 billion at the end of 2006 [1, 2]. In order to attract and accommodate these subscribers, modern communication systems, like the Third Generation (3G) and Fourth Generation (4G) cellular networks, will have to provide attractive new features such as increased data throughput rates, greater system capacity, and better speech quality. These modern communication systems promise to have advantages such as wireless access in ways that have never been possible before, providing, amongst others services such as live television (TV) broadcasting to Mobile Stations (MS)s, multi-megabit Internet access, communication using Voice over Internet Protocol (VoIP), unparalleled network capacity, seamless accessibility and many more. With specific, but not exclusive reference to the cellular environment, there are numerous ways to increase the data throughput rate and system capacity. From an economical perspective, it would be more efficient to add equipment to the Base Station (BS) rather than the MSs. To achieve these improvements the motivation to utilise transmit diversity’s capabilities have been identified as a key research issue in this study. Alamouti [3] proposed a transmit diversity technique using two transmit antennas and one receive antenna, providing the same diversity order than using one transmit antenna and two receive antennas. Since Alamouti’s publication in 1998, many papers in the field of Space-Time (ST) coding have been published. Current research in the field of ST coding consists of finding methods to extend the number of transmit antennas to more than four, while still achieving full rate, as well as full diversity which is the main motivation for this study. This study proposes a novel idea of breaching the limitations with ST coding theory by combining ST coding with Spread Spectrum (SS) modulation techniques in order to extend the number of transmit antennas to more than four and still achieve full rate as well as full diversity. An advantage of the proposed scheme, called Direct Sequence Space-Time Spreading (DSSTS) has over current Space-Time Spreading (STS) techniques is that it uses 50% less spreading codes. A performance evaluation platform for the DSSTS scheme was developed to simulate the performance of the scheme in a realistic mobile communication environment. A mobile communication channel that has the ability to simulate time-varying multipath fading was developed and used to evaluate the performance of the DSSTS scheme. From the simulation results obtained, it is evident that Walsh sequences that exhibit particularly good cross-correlation characteristics, cannot overcome the effect of the antenna self-noise in order to exploit the diversity gain by adding extra antennas, i.e. diversity extension. The research also showed that an optimal trade-off exists between antenna diversity and antenna created self-noise. Performance results of the DSSTS scheme in slow and fast fading channels for a different number of transmit antennas are also presented in this study. With the capacity analysis of the DSSTS scheme, it was shown that the addition of extra transmit antennas to the system indeed increased the system capacity. A further addition to this study is the investigation into the assumption that the channel should be quasi-static over the frame length of the ST code. A Space Sequence Transmit Diversity (SSTD) technique is consequently proposed that allows the transmission of the Alamouti symbols during one time interval instead of two. This relieves the ST code from the assumption that the channel should be quasi-static, allowing it to be used in a more realistic multi-user environment. A performance evaluation platform for the SSTD scheme was developed and used to obtain simulation results in a multipath fading channel. It was also shown that the proposed SSTD scheme is successful in combating the effects of multipath fading for small Code Division Multiple Access (CDMA) user loads. However, as a rule of thumb, the square root of the spreading sequence length divided by two depicts the user load at which the SSTD scheme was not capable of overcoming the combined effects of Multi-User Interference (MUI) and multipath fading. / Dissertation (MEng)--University of Pretoria, 2008. / Electrical, Electronic and Computer Engineering / unrestricted

In this thesis, we focus on interference cancelling (IC) detectors for advanced communication systems. The contents of this thesis is divided into the following four parts: 1. Multiuser interference (MUI) cancellation in uplink orthogonal frequency division multiple access (OFDMA). 2. Inter-carrier interference (ICI) and inter-symbol interference (ISI) cancellation in space-frequency block coded OFDM (SFBC-OFDM). 3. Single-symbol decodability (SSD) of distributed space-time block codes (DSTBC) in partially-coherent cooperative networks with amplify-and-forward protocol at the relays 4. Interference cancellation in cooperative SFBC-OFDM networks with amplify-and-forward (AF) and decode-and-forward (DF) protocols at the relays. In uplink OFDMA systems, MUI occurs due to different carrier frequency offsets of different users at the receiver. In the first part of the thesis, we present a weighted multistage linear parallel interference cancellation approach to mitigate the effect of this MUI in uplink OFDMA. We also present a minimum mean square error (MMSE) based approach to MUI cancellation in uplink OFDMA. We present a recursion to approach the MMSE solution and show structure-wise and performance-wise comparison with other detectors in the literature. Use of SFBC-OFDM signals is advantageous in high-mobility broadband wireless access, where the channel is highly time- as well as frequency-selective because of which the receiver experiences both ISI as well as ICI. In the second part of the thesis, we are concerned with the detection of SFBC-OFDM signals on time- and frequency-selective MIMO channels. Specifically, we propose and evaluate the performance of an interference cancelling receiver for SFBC-OFDM, which alleviates the effects of ISI and ICI in highly time- and frequency-selective channels The benefits of MIMO techniques can be made possible to user nodes having a single transmit antenna through cooperation among different nodes. In the third part of the thesis, we derive a new set of conditions for a distributed DSTBC to be SSD for a partially-coherent relay channel (PCRC), where the relays have only the phase information of the source-to-relay channels. We also establish several properties of SSD codes for PCRC. In the last part of the thesis, we consider cooperative SFBC-OFDM networks with AF and DF protocols at the relays. In cooperative SFBC-OFDM networks that employ DF protocol, i) ISI occurs at the destination due to violation of the `quasi-static' assumption because of the frequency selectivity of the relay-to-destination channels, and ii) ICI occurs due to imperfect carrier synchronization between the relay nodes and the destination, both of which result in error-floors in the bit error performance at the destination. We propose an interference cancellation algorithm for this system at the destination node, and show that the proposed algorithm effectively mitigates the ISI and ICI effects.

In this dissertation an in-depth study was conducted into the design, implementation and evaluation of a QPSK-based receiver structure for application in a UMTS WCDMA environment. The novelty of this work lies with the specific receiver architecture aimed to optimise the BER performance when possibly sparse data streams are transmitted. This scenario is a real possibility according to Verd´u et al [1] and Hagenauer et al [2–6]. A novel receiver structure was conceptualised, developed and evaluated in both narrowband and wideband scenarios, where it was found to outperform conventional receivers when a sparse data stream is transmitted. In order to reach the main conclusions of this study, it was necessary to develop a realistic simulation platform. The developed platform is capable of simulating a communication system meeting the physical layer requirements of the UMTS WCDMA standard. The platform can also perform narrowband simulations. A flexible channel emulator was developed that may be configured to simulate AWGN channel conditions, frequency non-selective fading (either Rayleigh or Rician with a configurable LOS component and Doppler spread), or a full multipath scenario where each path has a configurable LOS component, Doppler spread, path gain and path delay. It is therefore possible to even simulate a complex, yet realistic, COST207-TU channel model. The platform is also capable of simulating MUI. Each interfering user has a unique and independent multipath fading channel, while sharing the same bandwidth. Finally, the entire platform executes all simulations in baseband for improved simulation times. The research outputs of this work are summarised below: <ul> <li>A parameter, the sparseness measure, was defined in order to quantify the level by which a data stream differs from an equiprobable data stream.</li> <li>A novel source model was proposed and developed to simulate data streams with a specified amount of sparseness.</li> <li>An introductory investigation was undertaken to determine the effect of simple FEC techniques on the sparseness of an encoded data stream.</li> <li>Novel receiver structures for both narrowband and wideband systems were proposed, developed and evaluated for systems where possibly sparse data streams may be transmitted.</li> <li>Analytic expressions were derived to take the effect of sparseness into account in communication systems, including expressions for the joint PDF of a BPSK branch, the optimal decision region of a detector in AWGN conditions as well as the BER performance of a communication system employing the proposed optimal receiver in both AWGN channel conditions as well as in flat fading channel conditions.</li> <li>Numerous BER performance curves were obtained comparing the proposed receiver structure with conventional receivers in a variety of channel conditions, including AWGN, frequency non-selective fading and a multipath COST207-TU channel environment, as well as the effect of MUI</li></ul>. AFRIKAANS : In hierdie verhandeling word ’n in-diepte studie gedoen rakende die ontwerp, implementasie en evaluasie van ’n KPSK-gebaseerde ontvanger struktuur wat in ’n UMTS WKVVT omgewing gebruik kan word. Die bydrae van hierdie werk lˆe in die spesifieke ontvanger argitektuur wat daarop mik om die BFT werksverrigting te optimeer wanneer yl data strome versend word. Hierdie is ’n realistiese moontlikheid volgens Verd´u et al [1] en Hagenauer et al [2–6]. ’n Nuwe ontvanger struktuur is gekonsepsualiseer, ontwikkel en evalueer vir beide noueband en wyeband stelsels, waar dit gevind is dat dit beter werksverrigting lewer as tradisionele ontvangers wanneer yl data strome versend word. Dit was nodig om ’n realistiese simulasie platform te ontwikkel om die belangrikste gevolgtrekkings van hierdie studie te kan maak. Die ontwikkelde platform is in staat om ’n kommunikasie stelsel te simuleer wat aan die fisiese laag vereistes van die UMTS WKVVT standaard voldoen. Die platform kan ook noueband stelsels simuleer. ’n Aanpasbare kanaal simulator is ontwikkel wat opgestel kan word om SWGR kanaal toestande, plat duining (beide Rayleigh of Ricies met ’n verstelbare siglyn komponent en Doppler verspreiding), sowel as ’n veelvuldige pad omgewing (waar elke unieke pad ’n verstelbare siglyn komponent, Doppler verspreiding, pad wins en pad vertraging het) te emuleer. Dit is selfs moontlik om ’n komplekse, maar steeds realistiese COST207-TU kanaal model te simuleer. Die platform het ook die vermo¨e om VGS te simuleer. Elke steurende gebruiker het ’n unieke en onafhanklike veelvuldige pad deinende kanaal, terwyl dieselfde bandwydte gedeel word. Laastens, alle simulasies van die platvorm word in basisband uitgevoer wat verkorte simulasie periodes verseker. Die navorsingsuitsette van hierdie werk kan as volg opgesom word: <ul> <li>’n Parameter, die ylheidsmaatstaf, is gedefin¨ýeer om dit moontlik te maak om die vlak waarmee die ylheid van ’n datastroom verskil van ’n ewekansige stroom te versyfer.</li> <li>’n Nuwe bronmodel is voorgestel en ontwikkel om datastrome met ’n spesifieke ylheid te emuleer.</li> <li>’n Inleidende ondersoek is onderneem om vas te stel wat die effek van VFK tegnieke op die ylheid van ’n enkodeerde datastroom is.</li> <li>Nuwe ontvanger strukture is voorgestel, ontwikkel en evalueer vir beide noueband en wyeband stelsels waar yl datastrome moontlik versend kan word.</li> <li>Analitiese uitdrukkings is afgelei om die effek van ylheid in ag te neem in kommunikasie stelsels. Uitdrukkings vir onder andere die gedeelte WDF van ’n BFVK tak, die optimale beslissingspunt van ’n detektor in SWGR toestande, sowel as die BFT werksverrigting van ’n kommunikasie stelsel wat van die voorgestelde optimale ontvangers gebruik maak, hetsy in SWGR of in plat duinende kanaal toestande.</li> <li>Talryke BFT werksverrigting krommes is verkry wat die voorgestelde ontvanger struktuur vergelyk met die konvensionele ontvangers in ’n verskeidenheid kanaal toestande, insluitend SWGR, plat duinende kanale en ’n veelvuldige pad COST207-TU kanaal omgewing, sowel as in die teenwoordigheid van VGS.</li></ul></p Copyright / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / unrestricted