5 research outputs found
ANÁLISE DO PARADIGMA BITTORRENT PARA STREAMING DE VÍDEO SOB DEMANDA NA INTERNET ANTE ACESSO SEQUENCIAL PARTICIONADO SINCRONIZADO
Considering the video-on-demand (VoD) streaming serviceand a mostly sequential-data access pattern by users, thisarticle has the two following goals. Firstly, to analyze theBitTorrent paradigm's eciency under this access-patterntype. Secondly, to propose and analyze a new policy for dataselection by users, denoted as Smart Policy, focused on thisaccess-pattern type. For that, simulations are carried outin dierent VoD streaming scenarios, evaluating a varietyof performance metrics. Compared to previous proposalsin the literature, the nal results highlight optimizationsof up to 24,3% and 100% at the download rate and datawaiting time, respectively. Conclusions and directions forfuture work close this article.DOI: 10.36558/rsc.v11i2.722
Towards video streaming in IoT environments: vehicular communication perspective
Multimedia oriented Internet of Things (IoT) enables pervasive and real-time communication of video, audio and image data among devices in an immediate surroundings. Today's vehicles have the capability of supporting real time multimedia acquisition. Vehicles with high illuminating infrared cameras and customized sensors can communicate with other on-road devices using dedicated short-range communication (DSRC) and 5G enabled communication technologies. Real time incidence of both urban and highway vehicular traffic environment can be captured and transmitted using vehicle-to-vehicle and vehicle-to-infrastructure communication modes. Video streaming in vehicular IoT (VSV-IoT) environments is in growing stage with several challenges that need to be addressed ranging from limited resources in IoT devices, intermittent connection in vehicular networks, heterogeneous devices, dynamism and scalability in video encoding, bandwidth underutilization in video delivery, and attaining application-precise quality of service in video streaming. In this context, this paper presents a comprehensive review on video streaming in IoT environments focusing on vehicular communication perspective. Specifically, significance of video streaming in vehicular IoT environments is highlighted focusing on integration of vehicular communication with 5G enabled IoT technologies, and smart city oriented application areas for VSV-IoT. A taxonomy is presented for the classification of related literature on video streaming in vehicular network environments. Following the taxonomy, critical review of literature is performed focusing on major functional model, strengths and weaknesses. Metrics for video streaming in vehicular IoT environments are derived and comparatively analyzed in terms of their usage and evaluation capabilities. Open research challenges in VSV-IoT are identified as future directions of research in the area. The survey would benefit both IoT and vehicle industry practitioners and researchers, in terms of augmenting understanding of vehicular video streaming and its IoT related trends and issues
PERFORMANCE EVALUATION OF CROSS-LAYER DESIGN WITH DISTRIBUTED AND SEQUENTIAL MAPPING SCHEME FOR VIDEO APPLICATION OVER IEEE 802.11E
The rapid development of wireless communication imposes several challenges to support QoS for real-time multimedia applications such as video stream applications. Researchers tackled these challenges from different points of view including the semantics of the video to achieve better QoS requirements. The main goal of this research is to design a UDP protocol to realize a distributed sequential mapping scheme (DSM) with a cross-layer design and evaluate its accuracy under different network conditions. In DSM, the perceived quality of a multi-layer video is addressed by mapping each video layer into channel resources represented as queues or access categories (ACs) existing in IEEE 802.11e MAC layer. This research work further investigates the efficiency of this scheme with actual implementation and thorough simulation experiments. The experiments reported the efficiency of this scheme with the presence of different composite traffic models covering most known traffic scenarios using Expected Reconstructed Video Layers (ERVL) and packet loss rate as accuracy measures. This research work also investigates the accuracy of calculating the ERVL compared to its value using actual readings of layers drop rate. The effect of changing the ACs queue size on the ERVL is studied. The use of this scheme shows zero-drop in the base layer in almost all scenarios where no ongoing traffic is presented except that the testing video sessions between nodes. In these experiments, the ERVL continuously reported high values for the number of expected reconstructed video layers. While these values dramatically vary when introducing ongoing different composite traffic models together with the testing video sessions between nodes. Finally, a 40% increase in the ACs queue size shows significant improvement on ERVL while an increase of the queue size beyond this value has very little significance on ERVL
Communication between nodes for autonomic and distributed management
Doutoramento conjunto MAPi em InformáticaOver the last decade, the most widespread approaches for traditional management
were based on the Simple Network Management Protocol (SNMP) or Common
Management Information Protocol (CMIP). However, they both have several problems
in terms of scalability, due to their centralization characteristics. Although
the distributed management approaches exhibit better performance in terms of
scalability, they still underperform regarding communication costs, autonomy, extensibility,
exibility, robustness, and cooperation between network nodes. The
cooperation between network nodes normally requires excessive overheads for synchronization
and dissemination of management information in the network. For
emerging dynamic and large-scale networking environments, as envisioned in Next
Generation Networks (NGNs), exponential growth in the number of network devices
and mobile communications and application demands is expected. Thus, a
high degree of management automation is an important requirement, along with
new mechanisms that promote it optimally and e ciently, taking into account the
need for high cooperation between the nodes. Current approaches for self and autonomic
management allow the network administrator to manage large areas, performing
fast reaction and e ciently facing unexpected problems. The management
functionalities should be delegated to a self-organized plane operating within the
network, that decrease the network complexity and the control information ow,
as opposed to centralized or external servers. This Thesis aims to propose and
develop a communication framework for distributed network management which
integrates a set of mechanisms for initial communication, exchange of management
information, network (re) organization and data dissemination, attempting
to meet the autonomic and distributed management requirements posed by NGNs.
The mechanisms are lightweight and portable, and they can operate in di erent
hardware architectures and include all the requirements to maintain the basis for
an e cient communication between nodes in order to ensure autonomic network
management. Moreover, those mechanisms were explored in diverse network conditions
and events, such as device and link errors, di erent tra c/network loads
and requirements. The results obtained through simulation and real experimentation
show that the proposed mechanisms provide a lower convergence time, smaller
overhead impact in the network, faster dissemination of management information,
increase stability and quality of the nodes associations, and enable the support for
e cient data information delivery in comparison to the base mechanisms analyzed.
Finally, all mechanisms for communication between nodes proposed in this Thesis,
that support and distribute the management information and network control
functionalities, were devised and developed to operate in completely decentralized
scenarios.Durante a última década, protocolos como Simple Network Management Protocol
(SNMP) ou Common Management Information Protocol (CMIP) foram as abordagens
mais comuns para a gestão tradicional de redes. Essas abordagens têm
vários problemas em termos de escalabilidade, devido às suas características de
centralização. Apresentando um melhor desempenho em termos de escalabilidade,
as abordagens de gestão distribuída, por sua vez, são vantajosas nesse sentido,
mas também apresentam uma série de desvantagens acerca do custo elevado de
comunicação, autonomia, extensibilidade, exibilidade, robustez e cooperação entre
os nós da rede. A cooperação entre os nós presentes na rede é normalmente
a principal causa de sobrecarga na rede, uma vez que necessita de colectar, sincronizar
e disseminar as informações de gestão para todos os nós nela presentes.
Em ambientes dinâmicos, como é o caso das redes atuais e futuras, espera-se um
crescimento exponencial no número de dispositivos, associado a um grau elevado
de mobilidade dos mesmos na rede. Assim, o grau elevado de funções de automatiza
ção da gestão da rede é uma exigência primordial, bem como o desenvolvimento
de novos mecanismos e técnicas que permitam essa comunicação de forma optimizada
e e ciente. Tendo em conta a necessidade de elevada cooperação entre
os elementos da rede, as abordagens atuais para a gestão autonómica permitem
que o administrador possa gerir grandes áreas de forma rápida e e ciente frente
a problemas inesperados, visando diminuir a complexidade da rede e o uxo de
informações de controlo nela gerados. Nas gestões autonómicas a delegação de
operações da rede é suportada por um plano auto-organizado e não dependente
de servidores centralizados ou externos. Com base nos tipos de gestão e desa os
acima apresentados, esta Tese tem como principal objetivo propor e desenvolver
um conjunto de mecanismos necessários para a criação de uma infra-estrutura
de comunicação entre nós, na tentativa de satisfazer as exigências da gestão auton
ómica e distribuída apresentadas pelas redes de futura geração. Nesse sentido,
mecanismos especí cos incluindo inicialização e descoberta dos elementos da rede,
troca de informação de gestão, (re) organização da rede e disseminação de dados
foram elaborados e explorados em diversas condições e eventos, tais como: falhas
de ligação, diferentes cargas de tráfego e exigências de rede. Para além disso, os
mecanismos desenvolvidos são leves e portáveis, ou seja, podem operar em diferentes
arquitecturas de hardware e contemplam todos os requisitos necessários para
manter a base de comunicação e ciente entre os elementos da rede. Os resultados
obtidos através de simulações e experiências reais comprovam que os mecanismos
propostos apresentam um tempo de convergência menor para descoberta e troca
de informação, um menor impacto na sobrecarga da rede, disseminação mais rápida
da informação de gestão, aumento da estabilidade e a qualidade das ligações entre
os nós e entrega e ciente de informações de dados em comparação com os mecanismos
base analisados. Finalmente, todos os mecanismos desenvolvidos que fazem
parte da infrastrutura de comunicação proposta foram concebidos e desenvolvidos
para operar em cenários completamente descentralizados