Made available in DSpace on 2014-06-12T16:01:27Z (GMT). No. of bitstreams: 2 arquivo8983_1.pdf: 2694145 bytes, checksum: eada2ca72336a7b81aacb802940a6312 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / A popularização do serviço de Internet e a redução de custo facilitaram o acesso de usuários a diversos provedores de conteúdo, sejam estes baseados em voz, vídeo ou qualquer outro recurso de multimídia. Consequentemente aumentam os benefícios de ter uma rede de comunicações de melhor resiliência, pois quando uma conexão falha os dados podem fluir por conexões alternativas, reduzindo a probabilidade de perdas de pacotes e falhas na transmissão. Dessa forma, abre-se um novo cenário de estudo que tem a intenção de verificar e propor melhoras em formas de uso dos protocolos de comunicação que tenham o objetivo de tornar confiável a escolha dos melhores caminhos de transmissão para cada tipo de conteúdo. Para a transmissão de stream de vídeo, a escolha do protocolo de transporte é tão importante quanto a escolha de algoritmos e estruturas de dados em relação à aplicação rede. O estudo do desempenho de protocolos de rede de transportes é essencial para o desenvolvimento de protocolos tolerantes a falhas. A avaliação de políticas combinado com o caminho de transmissão, e os limiares de detecção de falhas, largura de banda, atrasos e perda de vazão são avaliados através da simulação dos diferentes protocolos de transmissão utilizado. O comportamento dos protocolos são verificados, comparando o tráfego considerando caminhos alternativos simétricas e assimétricas. O protocolo escolhido para o estudo é o UDP, devido à sua popularidade e sua tolerância a perda. Mostramos neste estudo que a configuração do tamanho do GOP (Group Of Picture) e a utilização correta do tamanho do Frame do UDP podem contribuir para uma transmissão de Vídeo Stream com melhor qualidade utilizando-se dos recursos de conexões disponíveis (seleção de caminhos) na rede

Submitted by Pedro Barros (pedro.silvabarros@ufpe.br) on 2018-07-26T17:46:54Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Charles Bezerra Moreira.pdf: 2975171 bytes, checksum: 31d50bfafe433ead710488865a9ada1d (MD5) / Approved for entry into archive by Alice Araujo (alice.caraujo@ufpe.br) on 2018-07-31T20:18:04Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Charles Bezerra Moreira.pdf: 2975171 bytes, checksum: 31d50bfafe433ead710488865a9ada1d (MD5) / Made available in DSpace on 2018-07-31T20:18:04Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Charles Bezerra Moreira.pdf: 2975171 bytes, checksum: 31d50bfafe433ead710488865a9ada1d (MD5) Previous issue date: 2016-07-29 / FACEPE / A internet evoluiu consideravelmente em vários aspectos e atualmente desempenha um papel fundamental no cotidiano das pessoas, isso possibilitou a existência de vários tipos de serviços, como, por exemplo, o streaming multimídia. Neste contexto, foi desenvolvido o DASH, que é um padrão para entrega de streaming de mídia que está sendo largamente adotado em serviços com foco em multimídia. Serviços como o YouTube e Netflix já utilizam este padrão há algum tempo, uma vez que permite melhor qualidade de experiência, pois a taxa de bits e a resolução do vídeo se adaptam às condições do tráfego de rede e reduzem travamentos indesejados do vídeo durante a transmissão. Deste modo é possível diminuir a irritabilidade dos usuários ao se assistir um vídeo que fica parando repentinamente por causa da qualidade do serviço de rede (QoS). Os dispositivos móveis (smartphones e tablets) foram fatores que ajudaram na expansão do streaming de vídeo junto com a evolução das tecnologias de telefonia móvel, pois o número de usuários de smartphones tem crescido rapidamente em todo o mundo e são aparelhos cada vez mais utilizados para assistir vídeos. Apesar da viabilidade do DASH para aumentar a qualidade de experiência, os dispositivos móveis são limitados pela capacidade de armazenamento energético da bateria, e o streaming de vídeo pode ser uma importante fonte de consumo de energia. Este trabalho avalia o DASH para streaming de vídeo no dispositivo móvel, levando em consideração a qualidade de experiência (QoE) e o consumo de energia, investigando os seguintes fatores: (i) a tecnologia de rede; (ii) a largura de banda da rede; e (iii) o tipo de vídeo. Para esta avaliação foram feitos dois experimentos utilizando três tecnologias de rede, três larguras de banda e oito vídeos, em que quatro não utilizaram o DASH e quatro utilizaram o DASH com quatro segmentos de tempo diferentes. O primeiro experimento consiste em avaliar o consumo de energia, qualidade de experiência, tempo de buffering e bytes recebidos durante a transmissão do vídeo, bem como suas interações. O segundo experimento foi feito injetando falhas periódicas durante a transmissão do vídeo, com a intenção de avaliar o padrão DASH sobre a flutuação da largura de banda. Os resultados experimentais demonstram que esses fatores e suas interações podem ter grande influência sobre o consumo de energia e a qualidade de experiência do vídeo. Além disso, foi possível se ter uma ideia do comportamento do consumo de energia ocasionado pela transmissão do vídeo em diferentes tecnologias de redes e larguras de banda. / The internet has evolved considerably in many aspects and currently plays a key role in people’s daily lives, such evolution of the internet made possible the existence of various types of services, such as multimedia streaming. In this context, DASH was developed, which is a standard for media streaming. DASH is being widely adopted in services with a focus on multimedia. Services such as YouTube and Netflix already use that pattern, since that standard allows a better quality experience, as the bitrate and video resolution adapt to the network traffic conditions and reduces unwanted video interruptions during transmission, thus it is possible to reduce the irritability of users to watch a video that is suddenly stopped because of the network quality of service (QoS). Mobile devices (smartphones and tablets) were one of the factors that helped in the expansion of video streaming; Along with the evolution of mobile technologies, the number of users who use a smartphone has grown rapidly throughout the world and smartphones are increasingly used to watch videos. Although DASH’s feasibility to improve the quality of experience, the mobile devices are limited by the energy storage capacity of the battery, and the video streaming can be an important source of energy consumption. This study evaluates the DASH video streaming on mobiles, considering the quality of experience (QoE) and power consumption, by investigating the following factors: (i) network technology; (ii) the network bandwidth; and (iii) the type of video. For this evaluation, two experiments were performed using three network technologies, three bandwidths, and eight videos in which four non-using DASH and four using DASH, besides four different time segments. The first experiment consists in measuring the energy consumption, the quality of experience, the buffer time and the bytes received during the transmission of video, as well as their interactions. The second experiment was performed by injecting periodic failures during the transmission of the video, with the goal of evaluating the DASH standard on the fluctuation of the network bandwidth. Experimental results show that these factors and their interactions can have great influence on the energy consumption and quality of experience of the video. Moreover, it was possible to get an idea of the energy consumption behavior caused by the transmission and display of video in different network technologies and bandwidths.

The aim of this study is to understand how leaders in the Canadian radio industry perceive the nascent personalized music streaming service industry, and how those perceptions inform their current business decisions. Over the last few years, Internet-based music services like Deezer and Rdio have launched in Canada, providing listeners with the opportunity of an alternative music experience to conventional broadcast radio. Through five interviews with experts representing terrestrial radio, on-demand services and regulation, three scenarios are presented for the future of conventional radio. In addition, a conceptualized listener profile is created using Grounded Theory Method. This profile buttresses the central finding of this research: should key political, economic and social factors remain in place, conventional radio is likely to continue to dominate as the leading commercial audio platform for Canadians in the years to come.

The recent advances in mobile computing devices and wireless networking produced the technical platform for multimedia services over thin mobile devices. Nowadays, we are witnessing an important growth in applications using thin mobile devices, such as social networks, virtual walkthrough, media streaming, and augmented reality (AR), just to mention a few. Most of these applications are based on the client-server architecture, however several studies showed that the client-server architecture suffers from various issues, such as the server bottleneck, latency and the lack of scalability. This led most of the systems to switch to the peer-to-peer (P2P)-like environment for its scalability and potential cost saving. P2P multimedia streaming over thin mobile devices-based classes of applications has known a significant growth during the last years. Although P2P video streaming over thin mobile devices received a great deal of attention, the application of 3D streaming over mobile devices was challenging mainly due to the limited mobile resources and capabilities, as well as the wireless medium limitations. Having 3D streaming over Mobile Ad hoc Networks (MANET) is considered more challenging given that the 3D streaming-based system has to deal with a dynamic environment resulting from nodes mobility, which may lead to route breakages and connection loss. Therefore, one of the major difficulties in 3D streaming over MANET is related to the supplying partner's strategy that aims at determining the most suitable source holding the required 3D data to stream it quickly and efficiently to the requesters. In this thesis, we propose our P2P based 3D streaming system which we refer to as MOSAIC as well as a suite of supplying partner strategy protocols for P2P 3D streaming over thin mobile devices. Our proposed suite of protocols selects the potential sources that have the relevant 3D data, based on a set of criteria such as the source location, the mobile device's available resources as well as its residual energy. We also proposed a multihop supplying partner selection protocol that takes into account the signal strength and the nodes mobility when streaming the relevant 3D data. The performance evaluation obtained to evaluate our MOSAIC system as well as our suite of protocols using an extensive set of NS2 simulation experiments, is then reported.

Because Vehicular Ad Hoc Networks (VANETs) often have a high packet loss rate, the formerly used protocol for video streaming, Real-time Transport Protocol (RTP), is no longer suitable for this specific environment. Previous conducted research has offered many new protocols to solve this problem; however, most of them cannot make full use of the existing Internet video streaming resources like RTP servers. Our work proposes two models to solve this compatibility issue. The first model is called the converter model. Based on this model, we first modify RTP using Erasure Coding (EC) technique in order to adapt it to the high packet loss rate of VANETs. This newly developed protocol is called EC-RTP. And, we then developed two converters. The first converter stands on the boundary between the Internet and VANETs. It receives the RTP packets which sent from Internet. And then it translates them to the EC-RTP packets. These packets are transported over the VANETs. The second converter receives these EC-RTP packets, translates them back to the RTP packets. It then sends them to the RTP player, so that the RTP player can play these packets. To make EC-RTP can carry more kinds of video streams other than RTP, we proposed a second model. The second model is called the redundancy tunnel. Based on this model, we let the protocol between the two converters carry RTP protocol as its payload. We use the same technique as we have used to modify RTP. At last, we did some experiments with Android tablets. The experiment results show our solution can use the same player to play the same video resources as RTP does. However, unlike RTP, it can reduce packet loss rate.

Accompanying the increasing interest on Vehicle Ad-hoc Network (VANET), there is a request for high quality and real-time video streaming on VANET, for safety and infotainment applications. Video Streaming on VANET faces extra issues, comparing to the Mobile Ad-hoc Network (MANET), like the high dynamic topology. However, there are also benefits in VANET, like large buffer and battery capacity, predictable motion of vehicles and powerful CPU and GPU. Video streaming on VANET can be highly improved by these features. However the poor performance of wireless networks is an critical issue for video streaming in VANET. The high packet loss probability of wireless networks significantly reduces the quality of the transmitted video. An error recovery process is proposed in our research for high quality and real-time video streaming in VANET, which is call Multi-path Error Recovery Video Streaming (MERVS). The performance improvement of wireless networks is also considered in our research. The cross layer technique is adopted in our research, in order to increase the accuracy on the network condition monitoring and to guarantee the fairness on network resource distribution. Cross layer protocols on both the Media Access Control (MAC) layer and the Network layer are proposed to improve the performance collaboratively. The contribution of my researches are: 1) I proposed a MERVS, which provides high quality and real-time video streaming; 2) several improvement techniques are also designed to improve the performance of MERVS; 3) simulation results verifies that MERVS can have a higher quality on transmitted video comparing to the existing protocols in an acceptable delay.

Video streaming over the best-effort networks is a challenging problem due to the time-varying and uncertain characteristics of the links. When multiple video streams are present in a network, they share and compete for the common bandwidth. In such a setting, a bandwidth allocation algorithm is required to distribute the available resources among the streams in a fair and efficient way. Specifically, it is desired to establish fairness across end-users' Quality of Experience (QoE). In this research, we propose three novel methods to provide QoE-fair network bandwidth allocation among multiple video streaming sessions. First, we formulate the problem of bandwidth allocation for video flows in the context of Network Utility Maximization (NUM) framework, using sigmoidal utility functions, rather than conventional but unrealistic concave functions. An approximation algorithm for Sigmoidal Programming (SP) is utilized to solve the resulting nonconvex optimization problem, called NUM-SP. Simulation results indicate improvements of at least 60% in average utility/QoE and 45% in fairness, while using slightly less network resources, compared to two representative methods. Subsequently, we take a collaborative decision-theoretic approach to the problem of rate adaptation among multiple video streaming sessions, and design a multi-objective foresighted optimization model for network resource allocation. A social welfare function is constructed to capture both fairness and efficiency objectives at the same time. Then, assuming a common altruistic goal for all network users, we use multi-agent decision processes to find the optimal policies for all players. We propose a Decentralized Partially Observable Markov Decision Process (Dec-POMDP) model for the conventional IP networks and a Multi-agent Markov Decision Process (MMDP) model for the SDN-enabled wireless networks. By planning these cooperative decision process models, we find the optimal network bandwidth allocation that leads to social welfare maximization. Distributed multi-agent reinforcement learning algorithms are also designed and proposed as a low-complexity model-free solution to these optimization problems. Simulations of the proposed methods show that the resulting optimal policies of the novel Social Utility Maximization (SUM) framework outperform existing approaches in terms of both efficiency and fairness. The Dec-POMDP model applied to a server-side rate adaptation results in 25% improvement in efficiency and 13% improvement in fairness, compared to one popular protocol of congestion control for multimedia streaming. Our performance evaluations also show that the MMDP model applied to a client-side rate adaptation like DASH improves efficiency, fairness, and social welfare by as much as 18%, 24%, and 25%, respectively compared to current state-of-the-art.

Vehicular Ad Hoc Networks (VANETs) are no longer a futuristic promise but rather an attainable technology. Vehicles are already equipped with a variety of computational devices that control or assist drivers in many tasks such as localization, safely breaking, parking and passengers entertainment. The majority of services envisioned for VANETs either require the provision of multimedia support or have it as an extremely beneficial additional feature. In particular, video streaming capabilities over VANETs are crucial to the development of interesting and valuable services. However,VANETs’ highly dynamic topology poses as a demanding challenge to the fulfillment of video streaming’s stringent requirements. The main goal on this thesis is the development of feasible solutions that support the streaming of video content over VANETs. Initially, the main issues of VANETs are explained through both a discussion of its characteristics and the results of some preliminary conclusions. Based on this understanding of VANETs’ peculiarities, three distinguishing solutions are designed REACT-DIS, REDEC and VIRTUS; the two first for video dissemination and the later for video unicast. These solutions offer a great advancement towards the provision of video streaming capabilities but packet loss is still an issue at high data rates. In order to improve the delivery ratios reached by the previous solutions, redundancy is used as an error correction mechanism. The use of redundancy is ideal for VANETs in handling packet loss as they do not require any interaction between source and receivers nodes. Sophisticated coding techniques were used for an efficient use of the increase on entropy of the information sent by the source node. It was also evaluated the selective use of redundancy solely on packets carrying the crucial information of I-frames. Although this selective approach obtained lower overall delivery ratios than when redundancy is used for all packets, the video quality obtained similar improvements under a much lower cost. The evaluation on the use of redundancy has considered the impact on the rate by which unique video content is received at end-users which is fundamental to understand the resolution of videos that can be displayed. This thesis provides several contributions as it advances the knowledge in the peculiarities of VANETs, solutions for video streaming over VANETs and the use of redundancy as an error correction mechanism for video streaming over VANETs.

The principle of operation of a novel rotating disk ultrasonic intensity meter is studied. Its characteristics are explained by a competition between acoustic radiation pressure and viscous drag on the disk. Acoustic streaming does not play a significant role in the operation of this meter as it is now configured. Experiments are described which were done to find the optimum dimensions and position for a nylon disk. In this optimum configuration, the rotation rate of the disk is related to the ultrasonic intensity by a power law. This relationship is theoretically predicted and found to hold as the ultrasonic intensity varies by a factor of at least ten. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

To broadcast live media to the viewer, more known as streaming, has grown in popularity a tremendous amount the last few years. Despite the large viewerbase and people’s dreams to share their creation with the world it’s still quite difficult to get started as a streamer. How can we make it easier for people to start streaming? This project includes the thought and design process of the development of a new product linefor streamers. The product’s purpose is to offer the correct functions that makes it possible, but also easy for anyone to share their passion with the entire world. Letting anyone in the world not just watch you, but also be a part of the experience. The project resulted in a conceptual starter kit for streaming. The kit includes products that cooperate with each other, giving the user a personal and positive experience when starting out with streaming.