77 research outputs found
A Seamless Vertical Handoff Protocol for Enhancing the Performance of Data Services in Integrated UMTS/WLAN Network
The Next Generation Wireless Network (NGWN) is speculated to be a unified network composed of several existing wireless access networks such as Wireless Local Area Network (WLAN), Global System for Mobile (GSM), Universal Mobile Telecommunications System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX), and satellite network etc
EVEREST IST - 2002 - 00185 : D23 : final report
Deliverable públic del projecte europeu EVERESTThis deliverable constitutes the final report of the project IST-2002-001858 EVEREST. After its successful completion, the project presents this document that firstly summarizes the context, goal and the approach objective of the project. Then it presents a concise summary of the major goals and results, as well as highlights the most valuable lessons derived form the project work. A list of deliverables and publications is included in the annex.Postprint (published version
A Seamless Vertical Handoff Protocol for Enhancing the Performance of Data Services in Integrated UMTS/WLAN Network
The Next Generation Wireless Network (NGWN) is speculated to be a unified network composed of several existing wireless access networks such as Wireless Local Area Network (WLAN), Global System for Mobile (GSM), Universal Mobile Telecommunications System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX), and satellite network etc
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3D multiple description coding for error resilience over wireless networks
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Mobile communications has gained a growing interest from both customers and service providers alike in the last 1-2 decades. Visual information is used in many application domains such as remote health care, video –on demand, broadcasting, video surveillance etc. In order to enhance the visual effects of digital video content, the depth perception needs to be provided with the actual visual content. 3D video has earned a significant interest from the research community in recent years, due to the tremendous impact it leaves on viewers and its enhancement of the user’s quality of experience (QoE). In the near future, 3D video is likely to be used in most video applications, as it offers a greater sense of immersion and perceptual experience. When 3D video is compressed and transmitted over error prone channels, the associated packet loss leads to visual quality degradation. When a picture is lost or corrupted so severely that the concealment result is not acceptable, the receiver typically pauses video playback and waits for the next INTRA picture to resume decoding. Error propagation caused by employing predictive coding may degrade the video quality severely. There are several ways used to mitigate the effects of such transmission errors. One widely used technique in International Video Coding Standards is error resilience.
The motivation behind this research work is that, existing schemes for 2D colour video compression such as MPEG, JPEG and H.263 cannot be applied to 3D video content. 3D video signals contain depth as well as colour information and are bandwidth demanding, as they require the transmission of multiple high-bandwidth 3D video streams. On the other hand, the capacity of wireless channels is limited and wireless links are prone to various types of errors caused by noise, interference, fading, handoff, error burst and network congestion. Given the maximum bit rate budget to represent the 3D scene, optimal bit-rate allocation between texture and depth information rendering distortion/losses should be minimised. To mitigate the effect of these errors on the perceptual 3D video quality, error resilience video coding needs to be investigated further to offer better quality of experience (QoE) to end users.
This research work aims at enhancing the error resilience capability of compressed 3D video, when transmitted over mobile channels, using Multiple Description Coding (MDC) in order to improve better user’s quality of experience (QoE).
Furthermore, this thesis examines the sensitivity of the human visual system (HVS) when employed to view 3D video scenes. The approach used in this study is to use subjective testing in order to rate people’s perception of 3D video under error free and error prone conditions through the use of a carefully designed bespoke questionnaire.Petroleum Technology Development Fund (PTDF
Análise de desempenho e do comportamento do utilizador em redes 3G
Mestrado em Electrónica e TelecomunicaçõesA Qualidade de Serviço (QoS) é uma preocupação para os operadores,
mas devido à evolução da rede para um enorme número de serviços
com requisistos diferentes, garantir uma boa QoS não é exatcamente
sinónimo de utilizadores satisfeitos. A percepção da qualidade de
serviço por parte dos utilizadores (QoE) garante aos operadores uma
visão do grau de satisfação do utilizador final. O objectivo de uma boa
QoS deve ser promover uma melhor QoE nos utilizadores. A QoE
permite aos operadores saberem de que forma é que as condições da
rede satisfazem as expectativas dos seus utilizadores em termos de
confiança, disponibilidade, escalabilidade, velocidade, desempenho e
eficiência.
O objectivo deste trabalho é o desenvolvimento de mecanismos que
permitam aos operadores analisarem ao mesmo tempo o
comportamento dos utilizadores e o estado da rede em termos de
qualidade numa determinada região. Com este tipo de informação
disponível os operadores podem adaptar os mecanismos de QoS da
rede de modo a prencherem na totalidade as expectativas do utilizador
final numa determinada região.The Quality of Service (QoS) is already a major concern for operators,
but things are changing and, although in many cases better QoS results
in better Quality of Experience (QoE), fulfilling the required performance
parameters is not a synonym of satisfied users. QoE conditions can
immediate response on the user satisfaction and thus the goal of QoS
assurance should be to promote a better QoE. This will give the
operator a deeper sense of the contribution of network’s performance to
the overall level of customer satisfaction in terms of reliability,
availability, scalability, speed, accuracy and efficiency. The main goal of
this work is to provide operators with mechanisms for end user
behaviour analysis and at the same instant detailed network status. With
this information operators know the end users behaviour in a certain
region, know in detail network performance metrics and can adapt QoS
mechanisms to fulfil end users expectations
Intelligent adaptive bandwidth provisioning for quality of service in umts core networks
Master'sMASTER OF ENGINEERIN
A framework for secure mobility in wireless overlay networks
Various wireless networks are widely deployed world wide. Current technologies employed in these networks vary widely in terms of bandwidths, latencies, frequencies, and media access methods. Most existing wireless network technologies can be divided into two categories: those that provide a low-bandwidth service over a wide geographic area, for example UMTS, and those that provide a high bandwidth service over a narrow geographic area, for example 802.11. Although it would be desirable to provide a high- bandwidth service over a wide coverage region to mobile users all the time, no single wireless network technology simultaneously satisfies these require- ments. Wireless Overlay Networks, a hierarchical structure of wireless personal area, local area, and wide area data networks, is considered as an efficient and scalable way to solve this problem. Due to the wide deployment of UMTS and 802.11 WLAN, this study attempts to combine them to implement the concept of Wireless Overlay Net- works. Furthermore, the information transmitted over this Wireless Overlay Networks is protected in terms of authentication, integrity and confidentiality. To achieve this goal, this study aims to combine GPRS, Mobile IP and IPSec to propose a framework for secure mobility in Wireless Overlay Networks. The framework is developed in three steps: Firstly, this study addresses the problem of combining GPRS and Mo- bile IP, so that GPRS users are provided with Mobile IP service. This results in presenting a uniform Mobile IP interface to peers regardless of whether mobile users use UMTS or 802.11 WLAN. Secondly, this study discovers the existing problem when combining Mobile IP and IPSec, and proposes a Dual Home Agent Architecture to achieve secure mobility. Finally, based on the output of the previous two steps, a complete framework is proposed, which achieves secure mobility in Wireless Overlay Networks, specifically, in UMTS and 802.11 WLAN. The framework also implements seamless handover when mobile users switch between UMTS and 802.11. This results in UMTS and 802.11 WLAN looking like a single network when participating in this framework, and presents seamless and secure mobility
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