1,614 research outputs found
Seamless Infrastructure independent Multi Homed NEMO Handoff Using Effective and Timely IEEE 802.21 MIH triggers
Handoff performance of NEMO BS protocol with existent improvement proposals
is still not sufficient for real time and QoS-sensitive applications and
further optimizations are needed. When dealing with single homed NEMO, handoff
latency and packet loss become irreducible all optimizations included, so that
it is impossible to meet requirements of the above applications. Then, How to
combine the different Fast handoff approaches remains an open research issue
and needs more investigation. In this paper, we propose a new Infrastructure
independent handoff approach combining multihoming and intelligent
Make-Before-Break Handoff. Based on required Handoff time estimation, L2 and L3
handoffs are initiated using effective and timely MIH triggers, reducing so the
anticipation time and increasing the probability of prediction. We extend MIH
services to provide tunnel establishment and switching before link break. Thus,
the handoff is performed in background with no latency and no packet loss while
pingpong scenario is almost avoided. In addition, our proposal saves cost and
power consumption by optimizing the time of simultaneous use of multiple
interfaces. We provide also NS2 simulation experiments identifying suitable
parameter values used for estimation and validating the proposed mode
QoE de streaming de vídeo em redes veiculares com multihoming
With the ever-increasing interest and availability of vehicular networks, it is important
to study the Quality-of-Experience provided by these networks, which
ultimately determines the general public perception and thus the overall user
adoption. The broad Internet access, the evolution of user equipment, such
as smartphones, tablets and personal computers, and the appearance of services
like Youtube and Netflix, is leading the user content consumption to be
more and more in the form of video streaming. Either motivated by safety or
commercial applications, video streaming in such highly mobile environments
offers multiple challenges.
This dissertation evaluates the QoE of a multihoming communication strategy,
supported simultaneously byWAVE and Wi-Fi, for increasing the reliability and
performance of video streams in these environments. Furthermore, it also investigates
how distinct network functionalities, such as multihoming load balance,
buffering, and network metrics such as throughput and latency affect the
overall QoE observed. The results obtained led to the proposal of a multihoming
load balance policy for video applications based on access technologies,
aiming to improve QoE. The overall results show that QoE improves by 7.5%
using the proposed approach.Com o aumento contínuo do interesse e disponibilidade de redes veiculares,
é importante agora estudar a Qualidade de Experiência fornecida por estas
redes, que fundamentalmente determina a opinião e a percepção do público
geral sobre um dado serviço. O vasto acesso à Internet, a evolução dos equipamentos,
como os telemóveis atuais, tablets e computadores pessoais, e o
aparecimento de serviços como o YouTube e o Netflix, está a fazer com que
o conteúdo mais consumido seja cada vez mais em forma de streaming de
vídeo. Quer seja motivado por aplicações de segurança ou comerciais, o streaming
de vídeo em ambientes altamente móveis levanta vários desafios.
Esta dissertação avalia a Qualidade de Experiência de técnicas de multihoming,
permitindo o uso de diferentes tecnologias de comunicação, como o
WAVE e o Wi-Fi, para aumentar a fiabilidade e desempenho de streams de
vídeo nestes ambientes. Para além disso, investiga também como é que diferentes
mecanismos de rede, como o balanceamento, multihoming e o buffering,
e métricas como a taxa de transferência e latência, afetam a QoE observada.
Os resultados obtidos levaram à proposta de uma política de divisão
de tráfego para aplicações de vídeo baseada em tecnologias de acesso
para situações de multihoming, visando uma melhoria da QoE do utilizador.
Utilizando o método proposto, os resultados mostram que a experiência do
utilizador tem uma melhoria de 7,5%.Mestrado em Engenharia de Computadores e Telemátic
Future Trends and Challenges for Mobile and Convergent Networks
Some traffic characteristics like real-time, location-based, and
community-inspired, as well as the exponential increase on the data traffic in
mobile networks, are challenging the academia and standardization communities
to manage these networks in completely novel and intelligent ways, otherwise,
current network infrastructures can not offer a connection service with an
acceptable quality for both emergent traffic demand and application requisites.
In this way, a very relevant research problem that needs to be addressed is how
a heterogeneous wireless access infrastructure should be controlled to offer a
network access with a proper level of quality for diverse flows ending at
multi-mode devices in mobile scenarios. The current chapter reviews recent
research and standardization work developed under the most used wireless access
technologies and mobile access proposals. It comprehensively outlines the
impact on the deployment of those technologies in future networking
environments, not only on the network performance but also in how the most
important requirements of several relevant players, such as, content providers,
network operators, and users/terminals can be addressed. Finally, the chapter
concludes referring the most notable aspects in how the environment of future
networks are expected to evolve like technology convergence, service
convergence, terminal convergence, market convergence, environmental awareness,
energy-efficiency, self-organized and intelligent infrastructure, as well as
the most important functional requisites to be addressed through that
infrastructure such as flow mobility, data offloading, load balancing and
vertical multihoming.Comment: In book 4G & Beyond: The Convergence of Networks, Devices and
Services, Nova Science Publishers, 201
Design and prototype of a train-to-wayside communication architecture
Telecommunication has become very important in modern society and seems to be almost omnipresent, making daily life easier, more pleasant and connecting people everywhere. It does not only connect people, but also machines, enhancing the efficiency of automated tasks and monitoring automated processes. In this context the IBBT (Interdisciplinary Institute for BroadBand Technology) project TRACK (TRain Applications over an advanced Communication networK), sets the definition and prototyping of an end-to-end train-to-wayside communication architecture as one of the main research goals. The architecture provides networking capabilities for train monitoring, personnel applications and passenger Internet services. In the context of the project a prototype framework was developed to give a complete functioning demonstrator. Every aspect: tunneling and mobility, performance enhancements, and priority and quality of service were taken into consideration. In contrast to other research in this area, which has given mostly high-level overviews, TRACK resulted in a detailed architecture with all different elements present
Analysis, evaluation and improvement of RT-WMP for real-time and QoS wireless communication: Applications in confined environments
En los ultimos años, la innovación tecnológica, la característica de flexibilidad y el rápido despligue de las redes inalámbricas, han favorecido la difusión de la redes móviles ad-hoc (MANETs), capaces de ofrecer servicios para tareas específicas entre nodos móviles. Los aspectos relacionados al dinamismo de la topología móvil y el acceso a un medio compartido por naturaleza hacen que sea preciso enfrentarse a clases de problemas distintos de los relacionados con la redes cableadas, atrayendo de este modo el interés de la comunidad científica. Las redes ad-hoc suelen soportar tráfico con garantía de servicio mínimo y la mayor parte de las propuestas presentes en literatura tratan de dar garantías de ancho de banda o minimizar el retardo de los mensajes. Sin embargo hay situaciones en las que estas garantías no son suficientes. Este es el caso de los sistemas que requieren garantías mas fuertes en la entrega de los mensajes, como es el caso de los sistemas de tiempo real donde la pérdida o el retraso de un sólo mensaje puede provocar problemas graves. Otras aplicaciones como la videoconferencia, cada vez más extendidas, implican un tráfico de datos con requisitos diferentes, como la calidad de servicio (QoS). Los requisitos de tiempo real y de QoS añaden nuevos retos al ya exigente servicio de comunicación inalámbrica entre estaciones móviles de una MANET. Además, hay aplicaciones en las que hay que tener en cuenta algo más que el simple encaminamiento de los mensajes. Este es el caso de aplicaciones en entornos subterráneos, donde el conocimiento de la evolución de propagación de la señal entre los diferentes nodos puede ser útil para mejorar la calidad de servicio y mantener la conectividad en cada momento. A pesar de ésto, dentro del amplio abanicos de propuestas presente en la literatura, existen un conjunto de limitaciones que van de el mero uso de protocolos simulados a propuestas que no tienen en cuenta entornos no convencionales o que resultan aisladas desde el punto de vista de la integración en sistemas complejos. En esta tesis doctoral, se propone un estudio completo sobre un plataforma inalámbrica de tiempo real, utilizando el protocolo RT-WMP capaz de gestionar trafíco multimedia al mismo tiempo y adaptado al entorno de trabajo. Se propone una extensión para el soporte a los datos con calidad de servicio sin limitar las caractaristícas temporales del protocolo básico. Y con el fin de tener en cuenta el efecto de la propagación de la señal, se caracteriza el entorno por medio de un conjunto de restricciones de conectividad. La solución ha sido desarrollada y su validez ha sido demostrada extensamente en aplicaciones reales en entornos subterráneos, en redes malladas y aplicaciones robóticas
An overview of internet engineering task force mobility management protocols: approaches and its challenges
In recent years, internet protocol mobility management has become one of the most popular research areas in networking. Mobility management protocols are in charge of preserving continuing communications as a user roam between different networks. All existing internet protocols (IP), like MIPv6, and PMIPv6, rely on a centralized mobility anchor to control mobile node traffic and signaling. The disadvantages of centralized mobility management (CMM) include ineffectiveness in handling massive volumes of traffic, poor scalability, wasteful use of network resources, and packet delay. When CMM is required to handle mobile media, which demands a huge amount of information and frequently needs quality of services (QoS) such as session continuance and reduced latency, these difficulties become apparent. It drives the need for distributed mobility management protocol (DMM) systems to manage the growing amount of mobile data, the overwhelming of this is video communication. DMM approaches could be regarded as an innovative and effective method to deal with mobility. An overview of the CMM protocol and its drawbacks are analyzed. This study examines the various DMM protocol techniques and their performance metrics are compared to highlight similarities and differences. The study reveals the network-based DMM protocol improves overall handoff time and packet loss
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