139 research outputs found
Sustainable Paths for Data-Intensive Research Communities at the University of Melbourne: A Report for the Australian Partnership for Sustainable Repositories
This report presents the local project findings with a view to identifying how these findings may add to the knowledge base for informing an e-research strategy for the University of Melbourne. It also provides important considerations for how major Government initiatives in research policy and funding might impact on research data and records management requirements. Eleven research communities from diverse disciplines were consulted for an audit of their data management practices. Researchers from these communities represent a number of diverse disciplines: Applied Economics; Astrophysics; Computer Science and Software Engineering; Education; Ethnography; Experimental Particle Physics; Humanities informatics; Hydrology and Environmental Engineering; Linguistics; Medical informatics; Neuroscience and the Performing Arts. In addition to the specific findings for each group audited, the project findings also provide information about sustainability issues around research data management practices at the university
A graphics software architecture for high-end interactive TV terminals
This thesis proposes a graphics architecture for next-generation digital television receivers. The starting assumption is that in the future, a number of multimedia terminals will have access through a number of networks to a variety of content and services. One example of such a device is a media station capable of integrating different kinds of multimedia objects such as 2D/3D graphics and video, reacting to user interaction, and supporting the temporal dimension of applications. Some of the services intended for these devices include, for example, games and enhanced information over broadcasted video.
First, this thesis provides an overview of the digital television environment, focusing on the limitations of current receivers and hints at future directions. In addition, this thesis compares different solutions from regional standardisation bodies such as DVB, CableLabs, and ARIB. It proposes the adoption of the most relevant initiative, GEM by DVB. Unfortunately, GEM software middleware only considers Java language as an authoring format, meaning that the declarative environment and advanced functionalities (e.g., 3D graphics support) remain to be standardised.
Because in the future different user groups will have different demands with regard to television, this thesis identifies two major extensions to the GEM standard. First, it proposes a declarative environment for GEM that takes into account W3C standardisation efforts. This environment is divided into two configurations: one capable of rendering limited interactive applications such as information services, and another intended for more demanding applications, for example a distance learning portal that synchronises videos of lecturers and slides. Second, this thesis proposes to extend the procedural environment of GEM with 3D graphics support. The potential services of this new profile, High-End Interactive, include games and commercials.
Then, based on the requirements the proposed profiles should meet, this thesis defines a graphics architecture model composed of five layers. The hardware abstraction layer is in charge of rendering the final graphics output. The graphical context is a cross-platform abstraction of the rendering region and provides graphics primitives (e.g., rectangles and images). The graphical environment provides the means to control different graphical contexts. The GUI toolkit is a set of ready-made user interface widgets and layout schemes. Finally, high-level languages are easy-to-use tools for developing simple services.
The thesis concludes with a report of my experience implementing a digital television receiver based on the proposals described. In addition to testing the application of the proposed graphics architecture to the design and implementation of a next-generation digital television receiver, the implementation permits the analysis of the requirements of such receivers and of the services they can provide.reviewe
Architectural support for ubiquitous access to multimedia content
Tese de doutoramento. Engenharia Electrotécnica e de Computadores (Telecomunicações). Faculdade de Engenharia. Universidade do Porto. 200
MedLAN: Compact mobile computing system for wireless information access in emergency hospital wards
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.As the need for faster, safer and more efficient healthcare delivery increases, medical consultants seek new ways of implementing a high quality telemedical system, using innovative technology. Until today, teleconsultation (the most common application of Telemedicine) was performed by transferring the patient from the Accidents and Emergency ward, to a specially equipped room, or by moving large and heavy machinery to the place where the patient resided. Both these solutions were unpractical, uneconomical and potentially dangerous. At the same time wireless networks became increasingly useful in point-of-care areas such as hospitals, because of their ease of use, low cost of installation and increased flexibility.
This thesis presents an integrated system called MedLAN dedicated for use inside the A&E hospital wards. Its purpose is to wirelessly support high-quality live video, audio, high-resolution still images and networks support from anywhere there is WLAN coverage. It is capable of transmitting all of the above to a consultant residing either inside or outside the hospital, or even to an external place, thorough the use of the Internet. To implement that, it makes use of the existing IEEE 802.11b wireless technology.
Initially, this thesis demonstrates that for specific scenarios (such as when using WLANs), DICOM specifications should be adjusted to accommodate for the reduced WLAN bandwidth. Near lossless compression has been used to send still images through the WLANs and the results have been evaluated by a number of consultants to decide whether they retain their diagnostic value.
The thesis further suggests improvements on the existing 802.11b protocol. In particular, as the typical hospital environment suffers from heavy RF reflections, it suggests that an alternative method of modulation (OFDM) can be embedded in the 802.11b hardware to reduce the multipath effect, increase the throughput and thus the video quality sent by the MedLAN system.
Finally, realising that the trust between a patient and a doctor is fundamental this thesis proposes a series of simple actions aiming at securing the MedLAN system. Additionally, a concrete security system is suggested, that encapsulates the existing WEP security protocol, over IPSec
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Interoperability of wireless communication technologies in hybrid networks: Evaluation of end-to-end interoperability issues and quality of service requirements
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Hybrid Networks employing wireless communication technologies have nowadays brought closer the vision of communication “anywhere, any time with anyone”. Such communication technologies consist of various standards, protocols, architectures, characteristics, models, devices, modulation and coding techniques. All these different technologies naturally may share some common characteristics, but there are also many important differences. New advances in these technologies are emerging very rapidly, with the advent of new models, characteristics, protocols and architectures. This rapid evolution imposes many challenges and issues to be addressed, and of particular importance are the interoperability issues of the following wireless technologies: Wireless Fidelity (Wi-Fi) IEEE802.11, Worldwide Interoperability for Microwave Access (WiMAX) IEEE 802.16, Single Channel per Carrier (SCPC), Digital Video Broadcasting of Satellite (DVB-S/DVB-S2), and Digital Video Broadcasting Return Channel through Satellite (DVB-RCS). Due to the differences amongst wireless technologies, these technologies do not generally interoperate easily with each other because of various interoperability and Quality of Service (QoS) issues.
The aim of this study is to assess and investigate end-to-end interoperability issues and QoS requirements, such as bandwidth, delays, jitter, latency, packet loss, throughput, TCP performance, UDP performance, unicast and multicast services and availability, on hybrid wireless communication networks (employing both satellite broadband and terrestrial wireless technologies).
The thesis provides an introduction to wireless communication technologies followed by a review of previous research studies on Hybrid Networks (both satellite and terrestrial wireless technologies, particularly Wi-Fi, WiMAX, DVB-RCS, and SCPC). Previous studies have discussed Wi-Fi, WiMAX, DVB-RCS, SCPC and 3G technologies and their standards as well as their properties and characteristics, such as operating frequency, bandwidth, data rate, basic configuration, coverage, power, interference, social issues, security problems, physical and MAC layer design and development issues. Although some previous studies provide valuable contributions to this area of research, they are limited to link layer characteristics, TCP performance, delay, bandwidth, capacity, data rate, and throughput. None of the studies cover all aspects of end-to-end interoperability issues and QoS requirements; such as bandwidth, delay, jitter, latency, packet loss, link performance, TCP and UDP performance, unicast and multicast performance, at end-to-end level, on Hybrid wireless networks.
Interoperability issues are discussed in detail and a comparison of the different technologies and protocols was done using appropriate testing tools, assessing various performance measures including: bandwidth, delay, jitter, latency, packet loss, throughput and availability testing. The standards, protocol suite/ models and architectures for Wi-Fi, WiMAX, DVB-RCS, SCPC, alongside with different platforms and applications, are discussed and compared. Using a robust approach, which includes a new testing methodology and a generic test plan, the testing was conducted using various realistic test scenarios on real networks, comprising variable numbers and types of nodes. The data, traces, packets, and files were captured from various live scenarios and sites. The test results were analysed in order to measure and compare the characteristics of wireless technologies, devices, protocols and applications.
The motivation of this research is to study all the end-to-end interoperability issues and Quality of Service requirements for rapidly growing Hybrid Networks in a comprehensive and systematic way.
The significance of this research is that it is based on a comprehensive and systematic investigation of issues and facts, instead of hypothetical ideas/scenarios or simulations, which informed the design of a test methodology for empirical data gathering by real network testing, suitable for the measurement of hybrid network single-link or end-to-end issues using proven test tools.
This systematic investigation of the issues encompasses an extensive series of tests measuring delay, jitter, packet loss, bandwidth, throughput, availability, performance of audio and video session, multicast and unicast performance, and stress testing. This testing covers most common test scenarios in hybrid networks and gives recommendations in achieving good end-to-end interoperability and QoS in hybrid networks.
Contributions of study include the identification of gaps in the research, a description of interoperability issues, a comparison of most common test tools, the development of a generic test plan, a new testing process and methodology, analysis and network design recommendations for end-to-end interoperability issues and QoS requirements. This covers the complete cycle of this research.
It is found that UDP is more suitable for hybrid wireless network as compared to TCP, particularly for the demanding applications considered, since TCP presents significant problems for multimedia and live traffic which requires strict QoS requirements on delay, jitter, packet loss and bandwidth. The main bottleneck for satellite communication is the delay of approximately 600 to 680 ms due to the long distance factor (and the finite speed of light) when communicating over geostationary satellites.
The delay and packet loss can be controlled using various methods, such as traffic classification, traffic prioritization, congestion control, buffer management, using delay compensator, protocol compensator, developing automatic request technique, flow scheduling, and bandwidth allocation
EXPERIMENTS ON VIDEO STREAMING OVER COMPUTER NETWORKS
Video traffic (including streaming video service) is dominating the Internet traffic today. Video can be streamed using a dedicated server, a content delivery network (CDN), or peer-to-peer (P2P) overlays across a network. Video can be transmitted in multiple formats and at different resolutions. Video is also being distributed to a variety of devices (fixed and mobile)
Economically sustainable public security and emergency network exploiting a broadband communications satellite
The research contributes to work in Rapid Deployment of a National Public Security and Emergency Communications Network using Communication Satellite Broadband. Although studies in Public Security Communication networks have examined the use of communications satellite as an integral part of the Communication Infrastructure, there has not been an in-depth design analysis of an optimized regional broadband-based communication satellite in relation to the envisaged service coverage area, with little or no terrestrial last-mile telecommunications infrastructure for delivery of satellite solutions, applications and services.
As such, the research provides a case study of a Nigerian Public Safety Security Communications Pilot project deployed in regions of the African continent with inadequate terrestrial last mile infrastructure and thus requiring a robust regional Communications Satellite complemented with variants of terrestrial wireless technologies to bridge the digital hiatus as a short and medium term measure apart from other strategic needs.
The research not only addresses the pivotal role of a secured integrated communications Public safety network for security agencies and emergency service organizations with its potential to foster efficient information symmetry amongst their operations including during emergency and crisis management in a timely manner but demonstrates a working model of how analogue spectrum meant for Push-to-Talk (PTT) services can be re-farmed and digitalized as a “dedicated” broadband-based public communications system. The network’s sustainability can be secured by using excess capacity for the strategic commercial telecommunication needs of the state and its citizens. Utilization of scarce spectrum has been deployed for Nigeria’s Cashless policy pilot project for financial and digital inclusion. This effectively drives the universal access goals, without exclusivity, in a continent, which still remains the least wired in the world
Multimedia data capture with multicast dissemination for online distance learning
Distance Learning Environments (DLEs) are elusive to define, difficult to successfully implement and costly due to their proprietary nature. With few open-source solutions, organizations are forced to invest large amounts of their resources in the procurement and support of proprietary products. Once an organization has chosen a particular solution, it becomes prohibitively expensive to choose another path later in the development process. The resolution to these challenges is realized in the use of open-standards, non-proprietary solutions. This thesis explores the multiple definitions of DLEs, defines metrics of successful implementation and develops open-source solutions for the delivery of multimedia in the Distance Learning Environment. Through the use of the Java Media Framework API, multiple tools are created to increase the transmission, capture and availability of multimedia content. Development of this technology, through the use of case studies, leaves a legacy of lectures and knowledge on the Internet to entertain and enlighten future generations.http://archive.org/details/multimedidatcapt109456185US Navy (USN) autho
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