57 research outputs found
Mobile Networks
The growth in the use of mobile networks has come mainly with the third generation systems and voice traffic. With the current third generation and the arrival of the 4G, the number of mobile users in the world will exceed the number of landlines users. Audio and video streaming have had a significant increase, parallel to the requirements of bandwidth and quality of service demanded by those applications. Mobile networks require that the applications and protocols that have worked successfully in fixed networks can be used with the same level of quality in mobile scenarios. Until the third generation of mobile networks, the need to ensure reliable handovers was still an important issue. On the eve of a new generation of access networks (4G) and increased connectivity between networks of different characteristics commonly called hybrid (satellite, ad-hoc, sensors, wired, WIMAX, LAN, etc.), it is necessary to transfer mechanisms of mobility to future generations of networks. In order to achieve this, it is essential to carry out a comprehensive evaluation of the performance of current protocols and the diverse topologies to suit the new mobility conditions
Acesso banda larga sem fios em ambientes heterogéneos de próxima geração
Doutoramento em Engenharia InformáticaO acesso ubíquo à Internet é um dos principais desafios para os operadores
de telecomunicações na próxima década. O número de utilizadores da Internet
está a crescer exponencialmente e o paradigma de acesso "always connected,
anytime, anywhere" é um requisito fundamental para as redes móveis de
próxima geração. A tecnologia WiMAX, juntamente com o LTE, foi
recentemente reconhecida pelo ITU como uma das tecnologias de acesso
compatíveis com os requisitos do 4G. Ainda assim, esta tecnologia de acesso
não está completamente preparada para ambientes de próxima geração,
principalmente devido à falta de mecanismos de cross-layer para integração de
QoS e mobilidade. Adicionalmente, para além das tecnologias WiMAX e LTE,
as tecnologias de acesso rádio UMTS/HSPA e Wi-Fi continuarão a ter um
impacto significativo nas comunicações móveis durante os próximos anos.
Deste modo, é fundamental garantir a coexistência das várias tecnologias de
acesso rádio em termos de QoS e mobilidade, permitindo assim a entrega de
serviços multimédia de tempo real em redes móveis.
Para garantir a entrega de serviços multimédia a utilizadores WiMAX, esta
Tese propõe um gestor cross-layer WiMAX integrado com uma arquitectura de
QoS fim-a-fim. A arquitectura apresentada permite o controlo de QoS e a
comunicação bidireccional entre o sistema WiMAX e as entidades das
camadas superiores. Para além disso, o gestor de cross-layer proposto é
estendido com eventos e comandos genéricos e independentes da tecnologia
para optimizar os procedimentos de mobilidade em ambientes WiMAX. Foram
realizados testes para avaliar o desempenho dos procedimentos de QoS e
mobilidade da arquitectura WiMAX definida, demonstrando que esta é
perfeitamente capaz de entregar serviços de tempo real sem introduzir custos
excessivos na rede.
No seguimento das extensões de QoS e mobilidade apresentadas para a
tecnologia WiMAX, o âmbito desta Tese foi alargado para ambientes de
acesso sem-fios heterogéneos. Neste sentido, é proposta uma arquitectura de
mobilidade transparente com suporte de QoS para redes de acesso multitecnologia.
A arquitectura apresentada integra uma versão estendida do IEEE
802.21 com suporte de QoS, bem como um gestor de mobilidade avançado
integrado com os protocolos de gestão de mobilidade do nível IP. Finalmente,
para completar o trabalho desenvolvido no âmbito desta Tese, é proposta uma
extensão aos procedimentos de decisão de mobilidade em ambientes
heterogéneos para incorporar a informação de contexto da rede e do terminal.
Para validar e avaliar as optimizações propostas, foram desenvolvidos testes
de desempenho num demonstrador inter-tecnologia, composta pelas redes de
acesso WiMAX, Wi-Fi e UMTS/HSPA.Ubiquitous Internet access is one of the main challenges for the
telecommunications industry in the next decade. The number of users
accessing the Internet is growing exponentially and the network access
paradigm of “always connected, anytime, anywhere” is a central requirement
for the so-called Next Generation Mobile Networks (NGMN). WiMAX, together
with LTE, was recently recognized by ITU as one of the compliant access
technologies for 4G. Nevertheless, WiMAX is not yet fully prepared for next
generation environments, mainly due to the lack of QoS and mobility crosslayer
procedures to support real-time multimedia services delivery.
Furthermore, besides the 4G compliant WiMAX and LTE radio access
technologies, UMTS/HSPA and Wi-Fi will also have a significant impact in the
mobile communications during the next years. Therefore, it is fundamental to
ensure the coexistence of multiple radio access technologies in what QoS and
mobility procedures are concerned, thereby allowing the delivery of real-time
services in mobile networks.
In order to provide the WiMAX mobile users with the demanded multimedia
services, it is proposed in this Thesis a WiMAX cross-layer manager integrated
in an end-to-end all-IP QoS enabled architecture. The presented framework
enables the QoS control and bidirectional communication between WiMAX and
the upper layer network entities. Furthermore, the proposed cross-layer
framework is extended with media independent events and commands to
optimize the mobility procedures in WiMAX environments. Tests were made to
evaluate the QoS and mobility performance of the defined architecture,
demonstrating that it is perfectly capable of handling and supporting real time
services without introducing an excessive cost in the network.
Following the QoS and mobility extensions provided for WiMAX, the scope of
this Thesis is broaden and a seamless mobility architecture with QoS support in
heterogeneous wireless access environments is proposed. The presented
architecture integrates an extended version of the IEEE 802.21 framework with
QoS support, as well as an advanced mobility manager integrated with the IP
level mobility management protocols. Finally, to complete the work within the
framework of this Thesis, it is proposed an extension to the handover decisionmaking
processes in heterogeneous access environments through the
integration of context information from both the network entities and the enduser.
Performance tests were developed in a real testbed to validate the
proposed optimizations in an inter-technology handover scenario involving
WiMAX, Wi-Fi and UMTS/HSPA
Implementation and Performance Evaluation of an NGN prototype using WiMax as an Access Technology
Telecommunications networks have evolved to IP-based networks, commonly known as Next Generation Networks (NGN). The biggest challenge in providing high quality realtime multimedia applications is achieving a Quality of Service (QoS) consistent with user expectations. One of the key additional factors affecting QoS is the existence of different QoS mechanisms on the heterogeneous technologies used on NGN platforms. This research investigates the techniques used to achieve consistent QoS on network technologies that use different QoS techniques. Numerous proposals for solving the end-to-end QoS problem in IP networks have adopted policy-based management, use of signalling protocols for communicating applications QoS requirements across different Network Elements and QoS provisioning in Network Elements. Such solutions are dependent on the use of traffic classification and knowledge of the QoS requirements of applications and services on the networks. This research identifies the practical difficulties involved in meeting the QoS requirements of network traffic between WiMax and an IP core network. In the work, a solution based on the concept of class-of-service mapping is proposed. In the proposed solution, QoS is implemented on the two networks and the concept of class-of-service mapping is used to integrate the two QoS systems. This essentially provides consistent QoS to applications as they traverse the two network domains and hence meet end-user QoS expectations. The work is evaluated through a NGN prototype to determine the capabilities of the networks to deliver real-time media that meets user expectations
A framework to provide charging for third party composite services
Includes synopsis.Includes bibliographical references (leaves 81-87).Over the past few years the trend in the telecommunications industry has been geared towards offering new and innovative services to end users. A decade ago network operators were content with offering simple services such as voice and text messaging. However, they began to notice that these services were generating lower revenues even while the number of subscribers increased. This was a direct result of the market saturation and network operators were forced to rapidly deploy services with minimum capital investment and while maximising revenue from service usage by end users. Network operators can achieve this by exposing the network to external content and service providers. They would create interfaces that would allow these 3rd party service and content providers to offer their applications and services to users. Composing and bundling of these services will essentially create new services for the user and achieve rapid deployment of enhanced services. The concept of offering a wide range of services that are coordinated in such a way that they deliver a unique experience has sparked interest and numerous research on Service Delivery Platforms (SDP). SDP‟s will enable network operators to be able to develop and offer a wide-variety service set. Given this interest on SDP standardisation bodies such as International Telecommunications Union – Telecommunications (ITU-T), Telecoms and Internet converged Servicers and Protocols for Advanced Networks) (TISPAN), 3rd Generations Partnership Project (3GPP) and Open Mobile Alliance (OMA) are leading efforts into standardising functions and protocols to enhance service delivery by network operators. Obtaining revenue from these services requires effective accounting of service usage and requires mechanisms for billing and charging of these services. The IP Multimedia subsystem(IMS) is a Next Generation Network (NGN) architecture that provides a platform for which multimedia services can be developed and deployed by network operators. The IMS provides network operators, both fixed or mobile, with a control layer that allows them to offer services that will enable them to remain key role players within the industry. Achieving this in an environment where the network operator interacts directly with the 3rd party service providers may become complicated
Major: Electronics and Communication Engineering
Today, information technology is strategically important to the goals and aspirations of the business enterprises, government and high-level education institutions – university.
Universities are facing new challenges with the emerging global economy characterized by the importance of providing faster communication services and improving the productivity and effectiveness of individuals. New challenges such as provides an information network that supports the demands and diversification of university issues. A new network architecture, which is a set of design principles for build a network, is one of the pillar bases. It is the cornerstone that enables the university’s faculty, researchers, students, administrators, and staff to discover, learn, reach out, and serve society.
This thesis focuses on the network architecture definitions and fundamental components. Three most important characteristics of high-quality architecture are that: it’s open network architecture; it’s service-oriented characteristics and is an IP network based on packets. There are four important components in the architecture, which are: Services and Network Management, Network Control, Core Switching and Edge Access.
The theoretical contribution of this study is a reference model Architecture of University Campus Network that can be followed or adapted to build a robust yet flexible network that respond next generation requirements. The results found are relevant to provide an important complete reference guide to the process of building campus network which nowadays play a very important role. Respectively, the research gives university networks a structured modular model that is reliable, robust and can easily grow
Avaliação de desempenho do funcionamento de serviços VoIP sobre redes 3GPP
Mestrado em Engenharia Electrónica e de TelecomunicaçõesA gestão de conteúdos orientados ao utilizador tem-se vindo a revelar uma
questão de extrema importância para os operadores, que embora não sejam
os produtores e distribuidores da informação acedida, são no entanto parte
interessada pois em última análise é a sua insignia que deve assegurar o
acesso. Os modelos de negócio desenvolvidos actualmente antevêm a
distribuição destes conteúdos assegurando o cumprimento dos parâmetros de
QoS. Com a evolução da distribuição de serviços sobre as redes IP, seguindo
a tendência da perspectiva “All-over-IP”, os ISPs necessitam cada vez mais de
ter conhecimento acerca da forma como estes serviços e os seus utilizadores
influenciam a utilização dos recursos da rede.
A monitorização de desempenho requer estratégias eficientes e optimizadas
com múltiplas implicações ao nível da segurança/privacidade. Cada serviço
possui características específicas que o podem tornar mais ou menos
resistente a determinadas condições da rede. O objectivo deste trabalho é
relacionar a informação relativa à sessão de um determinado tipo de serviço
baseado em IP, com as condições de desempenho na entrega do serviço por
parte da rede. O desafio é analisar diferentes tipos de informação, por um lado
a informação de sessão foca-se nos eventos gerados durante o seu ciclo de
vida, enquanto a informação de Performance Management (PM) da rede focase
primordialmente no comportamento e capacidade da rede em suportar a
entrega do serviço, a um grande número de assinantes, relevando portanto a
utilização das métricas de QoS.
A proposta deste trabalho é definir uma série de ferramentas como relatórios e
indicadores de desempenho, em que baseado na informação cross-layer, se
possa descrever uniformemente o desempenho do serviço.The management of user oriented contents is becoming of extreme relevance
for network operators, which while not being the producers of the consumed
data, are the ultimate insignia for the assured delivery. The business models
being currently applied envision the assured delivery of multimedia services
with the assurance of Quality of Service. By evolving towards the delivery of
services over IP networks undergoing the “all-over-IP” perspective, the Internet
Service Providers (ISP) needs to be aware of how the behavior of these
services and users influences the network resources usage. Performance
monitoring requires efficient and optimized strategies with multiple implications
at the security/privacy levels. Each service has specific characteristics which
may make it more or less resilient to some network performance issues. The
scope of this work is to relate session information with the underlying network
service delivery performance. The challenge is to analyze different kind of
information, session information focus is event driven tracing the entire lifecycle
of each event and network Performance Management (PM) information
focusing on the behavior and ability of the network to support service delivery
to a large number of subscribers, thus focusing on overall QoS metrics. The
proposal is to define use cases that can be implemented to ease this analysis
while defining general Key Performance Indicators (KPI) based on cross-layer
information, to uniformly describe the service performance
On the development of Voice over IP
This record of study documents the experience acquired during my internship at Sonus
Networks, Inc. for the Doctor of Engineering Program.
In this record of study, I have surveyed and analyzed the current standardization
status of Voice over Internet Protocol (VoIP) security and proposed an Internet draft on
secure retargeting and response identity. The draft provides a simple and comprehensive
solution to the response identity, call recipient identity and intermediate server
retargeting problems in the Session Initiation Protocol (SIP) call setup process.
To support product line development and enable product evolution in the quickly
growing VoIP market, I have proposed a generic development framework for SIP
application servers. The common and open architecture of the framework supports
multiple products development and facilitates integration of new service modules. The
systematical reuse of proven software design and implementation enables companies to
reduce the development cost and shorten the time-to-market.
As the development and diffusion of VoIP can never be isolated from the social
sphere, I have investigated the current status, influence and interaction of three most important factors: standardization, market forces and government regulation on the
development and diffusion of VoIP. The worldwide deregulation and market
privatization have caused the transition of the standards development model. This
transition in turn influences the market diffusion. Other than standardization, market
forces including customer needs, the revenue pressure on carriers and vendors,
competitive and economic environment, social culture and regulation uncertainties
create both threats and opportunities. I have examined market drivers and obstacles in
the current VoIP adoption stage, analyzed current VoIP market players and their
strategies, and predicted the direction of VoIP business. The regulation creates the macro
environment in which VoIP develops and diffuses. I have explored modern
telecommunications regulation principles based on which government makes decisions
on most current issues, including 911 support, mergers and acquisitions, interconnection
obligation and leasing rights, rate structure and universal service fees
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