128 research outputs found
Evaluation of unidirectional background push content download services for the delivery of television programs
Este trabajo de tesis presenta los servicios de descarga de contenido en modo push como un
mecanismo eficiente para el envío de contenido de televisión pre-producido sobre redes de
difusión. Hoy en día, los operadores de red dedican una cantidad considerable de recursos
de red a la entrega en vivo de contenido televisivo, tanto sobre redes de difusión como
sobre conexiones unidireccionales. Esta oferta de servicios responde únicamente a
requisitos comerciales: disponer de los contenidos televisivos en cualquier momento y
lugar. Sin embargo, desde un punto de vista estrictamente académico, el envío en vivo es
únicamente un requerimiento para el contenido en vivo, no para contenidos que ya han sido
producidos con anterioridad a su emisión. Más aún, la difusión es solo eficiente cuando el
contenido es suficientemente popular.
Los servicios bajo estudio en esta tesis utilizan capacidad residual en redes de difusión para
enviar contenido pre-producido para que se almacene en los equipos de usuario. La
propuesta se justifica únicamente por su eficiencia. Por un lado, genera valor de recursos de
red que no se aprovecharían de otra manera. Por otro lado, realiza la entrega de contenidos
pre-producidos y populares de la manera más eficiente: sobre servicios de descarga de
contenidos en difusión.
Los resultados incluyen modelos para la popularidad y la duración de contenidos, valiosos
para cualquier trabajo de investigación basados en la entrega de contenidos televisivos.
Además, la tesis evalúa la capacidad residual disponible en redes de difusión, por medio de
estudios empíricos. Después, estos resultados son utilizados en simulaciones que evalúan
las prestaciones de los servicios propuestos en escenarios diferentes y para aplicaciones
diferentes. La evaluación demuestra que este tipo de servicios son un recurso muy útil para
la entrega de contenido televisivo.This thesis dissertation presents background push Content Download Services as an
efficient mechanism to deliver pre-produced television content through existing broadcast
networks. Nowadays, network operators dedicate a considerable amount of network
resources to live streaming live, through both broadcast and unicast connections. This
service offering responds solely to commercial requirements: Content must be available
anytime and anywhere. However, from a strictly academic point of view, live streaming is
only a requirement for live content and not for pre-produced content. Moreover,
broadcasting is only efficient when the content is sufficiently popular.
The services under study in this thesis use residual capacity in broadcast networks to push
popular, pre-produced content to storage capacity in customer premises equipment. The
proposal responds only to efficiency requirements. On one hand, it creates value from
network resources otherwise unused. On the other hand, it delivers popular pre-produced
content in the most efficient way: through broadcast download services.
The results include models for the popularity and the duration of television content,
valuable for any research work dealing with file-based delivery of television content. Later,
the thesis evaluates the residual capacity available in broadcast networks through empirical
studies. These results are used in simulations to evaluate the performance of background
push content download services in different scenarios and for different applications. The
evaluation proves that this kind of services can become a great asset for the delivery of
television contentFraile Gil, F. (2013). Evaluation of unidirectional background push content download services for the delivery of television programs [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31656TESI
Optimal Proxy Cache Allocation for Efficient Streaming Media Distribution
In this paper, we address the problem of efficiently streaming a set of heterogeneous videos from a remote server through a proxy to multiple asynchronous clients so that they can experience playback with low startup delays. We develop a technique to analytically determine the optimal proxy prefix cache allocation to the videos that minimizes the aggregate network bandwidth cost. We integrate proxy caching with traditional serverbased reactive transmission schemes such as batching, patching and stream merging to develop a set of proxy-assisted delivery schemes. We quantitatively explore the impact of the choice of transmission scheme, cache allocation policy, proxy cache size, and availability of unicast versus multicast capability, on the resultant transmission cost. Our evaluations show that even a relatively small prefix cache (10%-20% of the video repository) is sufficient to realize substantial savings in transmission cost. We find that carefully designed proxy-assisted reactive transmission schemes can produce significant cost savings even in predominantly unicast environments such as the Internet
A Hybrid of Adaptation and Dynamic Routing based on SDN for Improving QoE in HTTP Adaptive VBR Video Streaming
Recently, HTTP Adaptive Streaming HAS has received significant attention from
both industry and academia based on its ability to enhancing media streaming
services over the Internet. Recent research solutions that have tried to
improve HAS by adaptation at the client side only may not be completely
effective without interacting with routing decisions in the upper layers. In
this paper, we address the aforementioned issue by proposing a dynamic
bandwidth allocation and management architecture for streaming video flows to
improve users satisfaction. We also introduce an initial cross layer hybrid
method that combines quality adaptation of variable bitrate video streaming
over the HTTP protocol at the client side and SDN based dynamical routing. This
scheme is enabled by the Software Defined Networking architecture that is now
being considered as an emerging paradigm that disassociates the forwarding
process from the routing process. SDN brings flexibility and the ability to
flexibly change routing solutions, in turn resulting in dynamically improving
the services provided in the application layer. Our experimental results show
that the proposed solution offers significantly higher overall bitrates as well
as smoother viewing experience than existing methods.Comment: 14 pages, 17 figures, IJCSNS International Journal of Computer
Science and Network Security,
http://paper.ijcsns.org/07_book/201907/20190708.pd
Performance evaluation of an open distributed platform for realistic traffic generation
Network researchers have dedicated a notable part of their efforts
to the area of modeling traffic and to the implementation of efficient traffic
generators. We feel that there is a strong demand for traffic generators
capable to reproduce realistic traffic patterns according to theoretical
models and at the same time with high performance. This work presents an open
distributed platform for traffic generation that we called distributed
internet traffic generator (D-ITG), capable of producing traffic (network,
transport and application layer) at packet level and of accurately replicating
appropriate stochastic processes for both inter departure time (IDT) and
packet size (PS) random variables. We implemented two different versions of
our distributed generator. In the first one, a log server is in charge of
recording the information transmitted by senders and receivers and these
communications are based either on TCP or UDP. In the other one, senders and
receivers make use of the MPI library. In this work a complete performance
comparison among the centralized version and the two distributed versions of
D-ITG is presented
ActiveSTB: an efficient wireless resource manager in home networks
The rapid growth of new wireless and mobile devices accessing the internet has
led to an increase in the demand for multimedia streaming services. These home-based
wireless connections require efficient distribution of shared network resources which is a
major concern for the transport of stored video. In our study, a set-top box is the access
point between the internet and a home network. Our main goal is to design a set-top box
capable of performing network flow control in a home network and capable of quality
adaptation of the delivered stream quality to the available bandwidth. To achieve our
main goal, estimating the available bandwidth quickly and precisely is the first task in
the decision of streaming rates of layered and scalable multimedia services. We present
a novel bandwidth estimation method called IdleGap that uses the NAV (Network
Allocation Vector) information in the wireless LAN. We will design a new set-top box
that will implement IdleGap and perform buffering and quality adaptation to a wireless
network based on the IdleGap’s bandwidth estimate. We use a network simulation tool
called NS-2 to evaluate IdleGap and our ActiveSTB compared to traditional STBs. We
performed several tests simulating network conditions over various ranges of cross
traffic with different error rates and observation times. Our simulation results reveal
how IdleGap accurately estimates the available bandwidth for all ranges of cross traffic
(100Kbps ~ 1Mbps) with a very short observation time (10 seconds). Test results also
reveal how our novel ActiveSTB outperforms traditional STBs and provides good QoS
to the end-user by reducing latency and excess bandwidth consumption
Performance evaluation of caching placement algorithms in named data network for video on demand service
The purpose of this study is to evaluate the performance of caching placement algorithms
(LCD, LCE, Prob, Pprob, Cross, Centrality, and Rand) in Named Data Network (NDN) for Video on Demand (VoD). This study aims to increment the service quality and to decrement the time of download. There are two stages of activities resulted in the outcome of the study: The first is to determine the causes of delay performance
in NDN cache algorithms used in VoD workload. The second activity is the evaluation of the seven cache placement algorithms on the cloud of video content in terms of the key performance metrics: delay time, average cache hit ratio, total reduction in the network footprint, and reduction in load. The NS3 simulations and the Internet2 topology were used to evaluate and analyze the findings of each algorithm, and to compare the results based on cache sizes: 1GB, 10GB, 100GB, and 1TB. This study proves that the different user requests of online videos would lead to delay in network performance. In addition to that the delay also caused by the high increment of video
requests. Also, the outcomes led to conclude that the increase in cache capacity leads
to make the placement algorithms have a significant increase in the average cache hit
ratio, a reduction in server load, and the total reduction in network footprint, which resulted in obtaining a minimized delay time. In addition to that, a conclusion was made
that Centrality is the worst cache placement algorithm based on the results obtained
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