15 research outputs found
Quality-Oriented Mobility Management for Multimedia Content Delivery to Mobile Users
The heterogeneous wireless networking environment determined by the latest developments in wireless access technologies promises a high level of communication resources for mobile
computational devices. Although the communication resources provided, especially referring to bandwidth, enable multimedia streaming to mobile users, maintaining a high user perceived quality is still a challenging task. The main factors which affect quality in multimedia streaming over wireless networks are mainly the error-prone nature of the wireless channels and the user mobility. These factors determine a high level of dynamics of wireless communication resources, namely variations in throughput and packet loss as well as network availability and delays in delivering the data packets. Under these conditions maintaining a high level of quality, as perceived by the user, requires a quality oriented mobility management scheme. Consequently we propose the Smooth Adaptive Soft-Handover Algorithm, a novel quality oriented handover management scheme which unlike other similar solutions, smoothly transfer the data traffic from one network to another using multiple simultaneous connections. To estimate the capacity of each connection the novel Quality of Multimedia Streaming (QMS) metric is proposed. The QMS metric aims at offering maximum flexibility and efficiency allowing the applications to fine tune the behavior of the handover algorithm. The current simulation-based performance evaluation clearly shows the better
performance of the proposed Smooth Adaptive Soft-Handover Algorithm as compared with other handover solutions. The evaluation was performed in various scenarios including
multiple mobile hosts performing handover simultaneously, wireless networks with variable overlapping areas, and various network congestion levels
Quality aspects of Internet telephony
Internet telephony has had a tremendous impact on how people communicate.
Many now maintain contact using some form of Internet telephony.
Therefore the motivation for this work has been to address the quality aspects
of real-world Internet telephony for both fixed and wireless telecommunication.
The focus has been on the quality aspects of voice communication,
since poor quality leads often to user dissatisfaction. The scope of the work
has been broad in order to address the main factors within IP-based voice
communication.
The first four chapters of this dissertation constitute the background
material. The first chapter outlines where Internet telephony is deployed
today. It also motivates the topics and techniques used in this research.
The second chapter provides the background on Internet telephony including
signalling, speech coding and voice Internetworking. The third chapter
focuses solely on quality measures for packetised voice systems and finally
the fourth chapter is devoted to the history of voice research.
The appendix of this dissertation constitutes the research contributions.
It includes an examination of the access network, focusing on how calls are
multiplexed in wired and wireless systems. Subsequently in the wireless
case, we consider how to handover calls from 802.11 networks to the cellular
infrastructure. We then consider the Internet backbone where most of our
work is devoted to measurements specifically for Internet telephony. The
applications of these measurements have been estimating telephony arrival
processes, measuring call quality, and quantifying the trend in Internet telephony
quality over several years. We also consider the end systems, since
they are responsible for reconstructing a voice stream given loss and delay
constraints. Finally we estimate voice quality using the ITU proposal PESQ
and the packet loss process.
The main contribution of this work is a systematic examination of Internet
telephony. We describe several methods to enable adaptable solutions
for maintaining consistent voice quality. We have also found that relatively
small technical changes can lead to substantial user quality improvements.
A second contribution of this work is a suite of software tools designed to
ascertain voice quality in IP networks. Some of these tools are in use within
commercial systems today
ACUTA Journal of Telecommunications in Higher Education
In This Issue
New Bandwidth Boosts Opportunities at the University of ldaho
Colleges Meld Data Functionality to Afford Larger, Better Facilities
Focusing on Video Demands
Wireless Optical Mesh Networking
Wireless LANs for Voice
Delivering Broadband over Power Lines
The Real lmpact of Napster
ACUTA Awards Presentations
Interview
President\u27s Message
From the Executive Director
Here\u27s My Advic
Wi-Fi Enabled Healthcare
Focusing on its recent proliferation in hospital systems, Wi-Fi Enabled Healthcare explains how Wi-Fi is transforming clinical work flows and infusing new life into the types of mobile devices being implemented in hospitals. Drawing on first-hand experiences from one of the largest healthcare systems in the United States, it covers the key areas associated with wireless network design, security, and support. Reporting on cutting-edge developments and emerging standards in Wi-Fi technologies, the book explores security implications for each device type. It covers real-time location services and emerging trends in cloud-based wireless architecture. It also outlines several options and design consideration for employee wireless coverage, voice over wireless (including smart phones), mobile medical devices, and wireless guest services. This book presents authoritative insight into the challenges that exist in adding Wi-Fi within a healthcare setting. It explores several solutions in each space along with design considerations and pros and cons. It also supplies an in-depth look at voice over wireless, mobile medical devices, and wireless guest services. The authors provide readers with the technical knowhow required to ensure their systems provide the reliable, end-to-end communications necessary to surmount todayâs challenges and capitalize on new opportunities. The shared experience and lessons learned provide essential guidance for large and small healthcare organizations in the United States and around the world. This book is an ideal reference for network design engineers and high-level hospital executives that are thinking about adding or improving upon Wi-Fi in their hospitals or hospital systems
Recent Advances in Wireless Communications and Networks
This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters
Improving the Performance of Wireless LANs
This book quantifies the key factors of WLAN performance and describes methods for improvement. It provides theoretical background and empirical results for the optimum planning and deployment of indoor WLAN systems, explaining the fundamentals while supplying guidelines for design, modeling, and performance evaluation. It discusses environmental effects on WLAN systems, protocol redesign for routing and MAC, and traffic distribution; examines emerging and future network technologies; and includes radio propagation and site measurements, simulations for various network design scenarios, numerous illustrations, practical examples, and learning aids
Telecommunications Networks
This book guides readers through the basics of rapidly emerging networks to more advanced concepts and future expectations of Telecommunications Networks. It identifies and examines the most pressing research issues in Telecommunications and it contains chapters written by leading researchers, academics and industry professionals. Telecommunications Networks - Current Status and Future Trends covers surveys of recent publications that investigate key areas of interest such as: IMS, eTOM, 3G/4G, optimization problems, modeling, simulation, quality of service, etc. This book, that is suitable for both PhD and master students, is organized into six sections: New Generation Networks, Quality of Services, Sensor Networks, Telecommunications, Traffic Engineering and Routing
Gestion des ressources dans les réseaux cellulaires sans fil
LâĂ©mergence de nouvelles applications et de nouveaux services (tels que les applications multimĂ©dias, la voix-sur-IP, la tĂ©lĂ©vision-sur-IP, la vidĂ©o-sur-demande, etc.) et le besoin croissant de mobilitĂ© des utilisateurs entrainent une demande de bande passante de plus en plus croissante et une difficultĂ© dans sa gestion dans les rĂ©seaux cellulaires sans fil (WCNs), causant une dĂ©gradation de la qualitĂ© de service. Ainsi, dans cette thĂšse, nous nous intĂ©ressons Ă la gestion des ressources, plus prĂ©cisĂ©ment Ă la bande passante, dans les WCNs.
Dans une premiĂšre partie de la thĂšse, nous nous concentrons sur la prĂ©diction de la mobilitĂ© des utilisateurs des WCNs. Dans ce contexte, nous proposons un modĂšle de prĂ©diction de la mobilitĂ©, relativement prĂ©cis qui permet de prĂ©dire la destination finale ou intermĂ©diaire et, par la suite, les chemins des utilisateurs mobiles vers leur destination prĂ©dite. Ce modĂšle se base sur : (a) les habitudes de lâutilisateur en terme de dĂ©placements (filtrĂ©es selon le type de jour et le moment de la journĂ©e) ; (b) le dĂ©placement courant de lâutilisateur ; (c) la connaissance de lâutilisateur ; (d) la direction vers une destination estimĂ©e ; et (e) la structure spatiale de la zone de dĂ©placement. Les rĂ©sultats de simulation montrent que ce modĂšle donne une prĂ©cision largement meilleure aux approches existantes.
Dans la deuxiĂšme partie de cette thĂšse, nous nous intĂ©ressons au contrĂŽle dâadmission et Ă la gestion de la bande passante dans les WCNs. En effet, nous proposons une approche de gestion de la bande passante comprenant : (1) une approche dâestimation du temps de transfert intercellulaire prenant en compte la densitĂ© de la zone de dĂ©placement en terme dâutilisateurs, les caractĂ©ristiques de mobilitĂ© des utilisateurs et les feux tricolores ; (2) une approche dâestimation de la bande passante disponible Ă lâavance dans les cellules prenant en compte les exigences en bande passante et la durĂ©e de vie des sessions en cours ; et (3) une approche de rĂ©servation passive de bande passante dans les cellules qui seront visitĂ©es pour les sessions en cours et de contrĂŽle dâadmission des demandes de nouvelles sessions prenant en compte la mobilitĂ© des utilisateurs et le comportement des cellules. Les rĂ©sultats de simulation indiquent que cette approche rĂ©duit largement les ruptures abruptes de sessions en cours, offre un taux de refus de nouvelles demandes de connexion acceptable et un taux Ă©levĂ© dâutilisation de la bande passante.
Dans la troisiĂšme partie de la thĂšse, nous nous penchons sur la principale limite de la premiĂšre et deuxiĂšme parties de la thĂšse, Ă savoir lâĂ©volutivitĂ© (selon le nombre dâutilisateurs) et proposons une plateforme qui intĂšgre des modĂšles de prĂ©diction de mobilitĂ© avec des modĂšles de prĂ©diction de la bande passante disponible. En effet, dans les deux parties prĂ©cĂ©dentes de la thĂšse, les prĂ©dictions de la mobilitĂ© sont effectuĂ©es pour chaque utilisateur. Ainsi, pour rendre notre proposition de plateforme Ă©volutive, nous proposons des modĂšles de prĂ©diction de mobilitĂ© par groupe dâutilisateurs en nous basant sur : (a) les profils des utilisateurs (câest-Ă -dire leur prĂ©fĂ©rence en termes de caractĂ©ristiques de route) ; (b) lâĂ©tat du trafic routier et le comportement des utilisateurs ; et (c) la structure spatiale de la zone de dĂ©placement. Les rĂ©sultats de simulation montrent que la plateforme proposĂ©e amĂ©liore la performance du rĂ©seau comparĂ©e aux plateformes existantes qui proposent des modĂšles de prĂ©diction de la mobilitĂ© par groupe dâutilisateurs pour la rĂ©servation de bande passante.The emergence of new applications and services (e.g., multimedia applications, voice over IP and IPTV) and the growing need for mobility of users cause more and more growth of bandwidth demand and a difficulty of its management in Wireless Cellular Networks (WCNs). In this thesis, we are interested in resources management, specifically the bandwidth, in WCNs.
In the first part of the thesis, we study the user mobility prediction that is one of key to guarantee efficient management of available bandwidth. In this context, we propose a relatively accurate mobility prediction model that allows predicting final or intermediate destinations and subsequently mobility paths of mobile users to reach these predicted destinations. This model takes into account (a) userâs habits in terms of movements (filtered according to the type of day and the time of the day); (b) user's current movement; (c) userâs contextual knowledge; (d) direction from current location to estimated destination; and (e) spatial conceptual maps. Simulation results show that the proposed model provides good accuracy compared to existing models in the literature.
In the second part of the thesis, we focus on call admission control and bandwidth management in WCNs. Indeed, we propose an efficient bandwidth utilization scheme that consists of three schemes: (1) handoff time estimation scheme that considers navigation zone density in term of users, usersâ mobility characteristics and traffic light scheduling; (2) available bandwidth estimation scheme that estimates bandwidth available in the cells that considers required bandwidth and lifetime of ongoing sessions; and (3) passive bandwidth reservation scheme that passively reserves bandwidth in cells expected to be visited by ongoing sessions and call admission control scheme for new call requests that considers the behavior of an individual user and the behavior of cells. Simulation results show that the proposed scheme reduces considerably the handoff call dropping rate while maintaining acceptable new call blocking rate and provides high bandwidth utilization rate.
In the third part of the thesis, we focus on the main limitation of the first and second part of the thesis which is the scalability (with the number of users) and propose a framework, together with schemes, that integrates mobility prediction models with bandwidth availability prediction models. Indeed, in the two first contributions of the thesis, mobility prediction schemes process individual user requests. Thus, to make the proposed framework scalable, we propose group-based mobility prediction schemes that predict mobility for a group of users (not only for a single user) based on usersâ profiles (i.e., their preference in terms of road characteristics), state of road traffic and users behaviors on roads and spatial conceptual maps. Simulation results show that the proposed framework improves the network performance compared to existing schemes which propose aggregate mobility prediction bandwidth reservation models