164 research outputs found
Evaluation of background push content download services to mobile devices over DVB networks
© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper proposes a multicast content download service based on the use of residual network capacity to push multimedia content to available local storage in personal multimedia devices. The service under study is based on the FLUTE protocol. Specifically, FLUTE packets fill the spare capacity in the IP tunnels reserved for the primary streaming service (opportunistic insertion). The paper also evaluates the use of AL-FEC parity to overcome transmission errors,object multiplexing to send the most popular multimedia contents more frequently and cache management policies that consider user preferences in order to keep in storage the most useful items. The service has been evaluated through simulations and measurements performed with an application prototype based on the DVB-H standards. The results show that AL-FEC enables the use of residual capacity for background content download services. In turn, AL-FEC, as well as object multiplexing, improves the relation between the number of content items and the overall access time. Moreover, results show that high percentages of requests can be served from the local cache of the service, provided that it is possible to estimate the popularity of content items and the user preferences.This work was supported by the PAID-05-12 program of the UniversitatPolitecnica de Valencia.Fraile Gil, F.; De Fez Lava, I.; Guerri Cebollada, JC. (2014). Evaluation of background push content download services to mobile devices over DVB networks. IEEE Transactions on Broadcasting. 60(1):1-15. https://doi.org/10.1109/TBC.2013.2289639S11560
Network coding meets multimedia: a review
While every network node only relays messages in a traditional communication system, the recent network coding (NC) paradigm proposes to implement simple in-network processing with packet combinations in the nodes. NC extends the concept of "encoding" a message beyond source coding (for compression) and channel coding (for protection against errors and losses). It has been shown to increase network throughput compared to traditional networks implementation, to reduce delay and to provide robustness to transmission errors and network dynamics. These features are so appealing for multimedia applications that they have spurred a large research effort towards the development of multimedia-specific NC techniques. This paper reviews the recent work in NC for multimedia applications and focuses on the techniques that fill the gap between NC theory and practical applications. It outlines the benefits of NC and presents the open challenges in this area. The paper initially focuses on multimedia-specific aspects of network coding, in particular delay, in-network error control, and mediaspecific error control. These aspects permit to handle varying network conditions as well as client heterogeneity, which are critical to the design and deployment of multimedia systems. After introducing these general concepts, the paper reviews in detail two applications that lend themselves naturally to NC via the cooperation and broadcast models, namely peer-to-peer multimedia streaming and wireless networkin
WIMAX Basics from PHY Layer to Scheduling and Multicasting Approaches
WiMAX (Worldwide Interoperability for Microwave Access) is an emerging broadband wireless technology for providing Last mile solutions for supporting higher bandwidth and multiple service classes with various quality of service requirement. The unique architecture of the WiMAX MAC and PHY layers that uses OFDMA to allocate multiple channels with different modulation schema and multiple time slots for each channel allows better adaptation of heterogeneous user’s requirements. The main architecture in WiMAX uses PMP (Point to Multipoint), Mesh mode or the new MMR (Mobile Multi hop Mode) deployments where scheduling and multicasting have different approaches. In PMP SS (Subscriber Station) connects directly to BS (Base Station) in a single hop route so channel conditions adaptations and supporting QoS for classes of services is the key points in scheduling, admission control or multicasting, while in Mesh networks SS connects to other SS Stations or to the BS in a multi hop routes, the MMR mode extends the PMP mode in which the SS connects to either a relay station (RS) or to Bs. Both MMR and Mesh uses centralized or distributed scheduling with multicasting schemas based on scheduling trees for routing. In this paper a broad study is conducted About WiMAX technology PMP and Mesh deployments from main physical layers features with differentiation of MAC layer features to scheduling and multicasting approaches in both modes of operations
Resource Allocation Frameworks for Network-coded Layered Multimedia Multicast Services
The explosive growth of content-on-the-move, such as video streaming to
mobile devices, has propelled research on multimedia broadcast and multicast
schemes. Multi-rate transmission strategies have been proposed as a means of
delivering layered services to users experiencing different downlink channel
conditions. In this paper, we consider Point-to-Multipoint layered service
delivery across a generic cellular system and improve it by applying different
random linear network coding approaches. We derive packet error probability
expressions and use them as performance metrics in the formulation of resource
allocation frameworks. The aim of these frameworks is both the optimization of
the transmission scheme and the minimization of the number of broadcast packets
on each downlink channel, while offering service guarantees to a predetermined
fraction of users. As a case of study, our proposed frameworks are then adapted
to the LTE-A standard and the eMBMS technology. We focus on the delivery of a
video service based on the H.264/SVC standard and demonstrate the advantages of
layered network coding over multi-rate transmission. Furthermore, we establish
that the choice of both the network coding technique and resource allocation
method play a critical role on the network footprint, and the quality of each
received video layer.Comment: IEEE Journal on Selected Areas in Communications - Special Issue on
Fundamental Approaches to Network Coding in Wireless Communication Systems.
To appea
Algorithm design for scheduling and medium access control in heterogeneous mobile networks
Mención Internacional en el tÃtulo de doctorThe rapid growth of wireless mobile devices has led to saturation and congestion of wireless channels – a well-known fact. In the recent years, this issue is further exacerbated by the ever-increasing demand for traffic intensed multimedia content applications, which include but are not limited to social media, news and video streaming applications. Therefore the development of highly efficient content distribution technologies is of utmost importance, specifically to cope with the scarcity and the high cost of wireless resources. To this aim, this thesis investigates the challenges and the considerations required to design efficient techniques to improve the performance of wireless networks. Since wireless signals are prone to fluctuations and mobile users are, with high likelihood, have difference channel qualities, we particularly focus on the scenarios with heterogeneous user distribution. Further, this dissertation considers two main techniques to cope with mobile users demand and the limitation of wireless resources. Firstly, we propose an opportunistic multicast scheduling to efficiently distribute or disseminate data to all users with low delay. Secondly, we exploit the Millimeter-Wave (mm-Wave) frequency band that has a high potential of meeting the high bandwidth demand. In particular, we propose a channel access mechanism and a scheduling algorithm that take into account the limitation of the high frequency band (i.e., high path loss).
Multicast scheduling has emerged as one of the most promising techniques for multicast applications when multiple users require the same content from the base station. Unlike a unicast scheduler which sequentially serves the individual users, a multicast scheduler efficiently utilizes the wireless resources by simultaneously transmitting to multiple users. Precisely, it multiplies the gain in terms of the system throughput compared to unicast transmissions. In spite of the fact that multicast schedulers are more efficient than unicast schedulers, scheduling for multicast transmission is a challenging task. In particular, base station can only chose one rate to transmit to all users. While determining the rate for users with a similar instantaneous channel quality is straight forward, it is non-trivial when users have different instantaneous channel qualities, i.e., when the channel is heterogeneous. In such a scenario, on one hand, transmitting at a low rate results in low throughput. On the other hand, transmitting at a high rate causes some users to fail to receive the transmitted packet while others successfully receive it but with a rate lower than their maximum rate. The most common and simplest multicasting technique, i.e., broadcasting, transmits to all receivers using the maximum rate that is supported by the worst receiver.
In recent years, opportunistic schedulers have been considered for multicasting. Opportunistic multicast schedulers maximize instantaneous throughput and transmit at a higher rate to serve only a subset of the multicast users. While broadcasting suffers from high delay for all users due to low transmission rate, the latter causes a long delay for the users with worse channel quality as they always favor users with better channel quality. To address these problems, we designed an opportunistic multicast scheduling mechanism that aims to achieve high throughput as well as low delay. Precisely, we are solving the finite horizon problem for multicasting. Our goal is that all multicast users receive the same amount of data within the shortest amount of time.
Although our proposed opportunistic multicast scheduling mechanism improves the system throughput and reduces delay, a common problem in multicast scheduling is that its throughput performance is limited by the worst user in the system. To overcome this problem, transmit beamforming can be used to adjust antenna gains to the different receivers. This allows improving the SNR of the receiver with the worst channel SNR at the expense of worsening the SNR of the better channel receivers. In the first part of this thesis, two different versions of the finite horizon problem are considered: (i) opportunistic multicast scheduling and (ii) opportunistic multicast beamforming.
In recent years, many researchers venture into the potential of communication over mm-Wave band as it potentially solves the existing network capacity problem. Since beamforming is capable to concentrate the transmit energy in the direction of interest, this technique is particularly beneficial to improve signal quality of the highly attenuated mm-Wave signal. Although directional beamforming in mm-Wave offers multi-gigabit-per-second data rates, directional communication severely deteriorates the channel sensing capability of a user. For instance, when a user is not within the transmission coverage or range of the communicating users, it is unable to identify the state of the channel (i.e., busy or free). As a result, this leads to a problem commonly known as the deafness problem. This calls for rethinking of the legacy medium access control and scheduling mechanisms for mm-Wave communication. Further, without omni-directional transmission, disseminating or broadcasting global information also becomes complex. To cope with these issues, we propose two techniques in the second part of this thesis. First, leveraging that recent mobile devices have multiple wireless interface, we present a dual-band solution. This solution exploits the omni-directional capable lower frequency bands (i.e., 2.4 and 5 GHz) to transmit control messages and the mm-Wave band for high speed data transmission. Second, we develop a decentralized scheduling technique which copes with the deafness problem in mm-Wave through a learning mechanism.
In a nutshell, this thesis explores solutions which (i) improve the utilization of the network resources through multicasting and (ii) meet the mobile user demand with the abundant channel resources available at high frequency bands.This work has been supported by IMDEA Networks Institute.Programa Oficial de Doctorado en IngenierÃa TelemáticaPresidente: Ralf Steinmetz.- Secretario: Carlos Jesús Bernardos Cano.- Vocal: Jordi Domingo Pascua
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 envÃo de contenido de televisión pre-producido sobre redes de
difusión. Hoy en dÃa, 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 envÃo 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 aprovecharÃan 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 empÃricos. 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
Radio resource allocation algorithms for multicast OFDM systems
Mención Internacional en el tÃtulo de doctorVideo services have become highly demanded in mobile networks leading
to an unprecedented traffic growth. It is expected that traffic from wireless
and mobile devices will account for nearly 70 percent of total IP traffic
by the year 2020, and the video services will account for nearly 75 percent
of mobile data traffic by 2022. Multicast transmission is one of the key
enablers towards a more spectral and energy efficient distribution of multimedia
content in current and envisaged mobile networks. It is worth noting
that multicast is a mechanism that efficiently delivers the same content to
many users, not only focusing on video broadcasting, but also distributing
many other media, such as software updates, weather forecast or breaking
news.
Although multicast services are available in Long Term Evolution (LTE)
and LTE-Advanced (LTE-A) networks, new improvements are needed in
some areas to handle the demands expected in the near future. Resource
allocation techniques for multicast services are one of the main challenging
issues, since it is required the development of novel schemes to meet the
demands of their evolution towards the next generation. Most multicast
techniques adopt rather conservative strategies that select a very robust
modulation and coding scheme (MCS), whose characteristics are determined
by the propagation conditions experienced by the worst user in the group
in order to ensure that all users in a multicast group are able to correctly
decode the received data. Obviously, this robustness comes at the prize of
a low spectral efficiency.
This thesis presents an exhaustive study of broadcast/multicast technology
for current mobile networks, especially focusing on the scheduling
and resource allocation (SRA) strategies to maximize the potential benefits
that multicast transmissions imply on the spectral efficiency. Based on that
issue, some contributions have been made to the state of the art in the radio
resource management (RRM) for current and beyond mobile multicast
services.
• In the frame of LTE/LTE-A, the evolved multimedia broadcast and
multicast service (eMBMS) shares the physical layer resources with the
unicast transmission mode (at least up to Release 12). Consequently,
the time allocation to multicast transmission is limited to a maximum
of a 60 percent, and the remaining subframes (at least 40 percent)
are reserved for unicast transmissions. With the aim of achieving the
maximum aggregated data rate (ADR) among the multicast users, we
have implemented several innovative SRA schemes that combine the
allocation of multicast and unicast resources in the LTE/LTE-A frame,
guaranteeing the prescribed quality of service (QoS) requirements for
every user.
• In the specific context of wideband communication systems, the selection
of the multicast MCS has often relied on the use of wideband
channel quality indicators (CQIs), providing rather imprecise information
regarding the potential capacity of the multicast channel. Only
recently has the per-subband CQI been used to improve the spectral
efficiency of the system without compromising the link robustness.
We have proposed novel subband CQI-based multicast SRA strategies
that, relying on the selection of more spectrally efficient transmission
modes, lead to increased data rates while still being able to fulfill
prescribed QoS metrics.
• Mobile broadcast/multicast video services require effective and low complexity
SRA strategies. We have proposed an SRA strategy based
on multicast subgrouping and the scalable video coding (SVC) technique for multicast video delivery. This scheme focuses on reducing
the search space of solutions and optimizes the ADR. The results in
terms of ADR, spectral efficiency, and fairness among multicast users,
along with the low complexity of the algorithm, show that this new
scheme is adequate for real systems.
These contributions are intended to serve as a reference that motivate
ongoing and future investigation in the challenging field of RRM for broadcast/
multicast services in next generation mobile networks.La demanda de servicios de vÃdeo en las redes móviles ha sufrido un incremento
exponencial en los últimos años, lo que a su vez ha desembocado
en un aumento sin precedentes del tráfico de datos. Se espera que antes
del año 2020, el trafico debido a dispositivos móviles alcance cerca del 70
por ciento del tráfico IP total, mientras que se prevé que los servicios de
vÃdeo sean prácticamente el 75 por ciento del tráfico de datos en las redes
móviles hacia el 2022. Las transmisiones multicast son una de las tecnologÃas
clave para conseguir una distribución más eficiente, tanto espectral como
energéticamente, del contenido multimedia en las redes móviles actuales y
futuras. Merece la pena reseñar que el multicast es un mecanismo de entrega
del mismo contenido a muchos usuarios, que no se enfoca exclusivamente
en la distribución de vÃdeo, sino que también permite la distribución de
otros muchos contenidos, como actualizaciones software, información meteorológica o noticias de última hora.
A pesar de que los servicios multicast ya se encuentran disponibles en
las redes Long Term Evolution (LTE) y LTE-Advanced (LTE-A), la mejora
en algunos ámbitos resulta necesaria para manejar las demandas que se
prevén a corto plazo. Las técnicas de asignación de recursos para los servicios
multicast suponen uno de los mayores desafÃos, ya que es necesario
el desarrollo de nuevos esquemas que nos permitan acometer las exigencias
que supone su evolución hacia la próxima generación. La mayor parte de
las técnicas multicast adoptan estrategias conservadoras, seleccionando esquemas
de modulación y codificación (MCS) impuestos por las condiciones de propagación que experimenta el usuario del grupo con peor canal, para
asà asegurar que todos los usuarios pertenecientes al grupo multicast sean
capaces de decodificar correctamente los datos recibidos. Como resulta obvio,
la utilización de esquemas tan robustos conlleva el precio de sufrir una
baja eficiencia espectral.
Esta tesis presenta un exhaustivo estudio de la tecnologÃa broadcast/
multicast para las redes móviles actuales, que se centra especialmente en
las estrategias de asignación de recursos (SRA), cuyo objetivo es maximizar
los beneficios que la utilización de transmisiones multicast potencialmente
implica en términos de eficiencia espectral. A partir de dicho estudio, hemos
realizado varias contribuciones al estado del arte en el ámbito de la gestión
de recursos radio (RRM) para los servicios multicast, aplicables en las redes
móviles actuales y futuras.
• En el marco de LTE/LTE-A, el eMBMS comparte los recursos de la
capa fÃsica con las transmisiones unicast (al menos hasta la revisión
12). Por lo tanto, la disponibilidad temporal de las transmisiones
multicast está limitada a un máximo del 60 por ciento, reservándose
las subtramas restantes (al menos el 40 por ciento) para las transmisiones
unicast. Con el objetivo de alcanzar la máxima tasa total de
datos (ADR) entre los usuarios multicast, hemos implementado varios
esquemas innovadores de SRA que combinan la asignación de los recursos
multicast y unicast de la trama LTE/LTE-A, garantizando los
requisitos de QoS a cada usuario.
• En los sistemas de comunicaciones de banda ancha, la selección del
MCS para transmisiones multicast se basa habitualmente en la utilización de CQIs de banda ancha, lo que proporciona información bastante
imprecisa acerca de la capacidad potencial del canal multicast.
Recientemente se ha empezado a utilizar el CQI por subbanda para
mejorar la eficiencia espectral del sistema sin comprometer la robustez
de los enlaces. Hemos propuesto nuevas estrategias para SRA multicast
basadas en el CQI por subbanda que, basándose en la selección de los modos de transmisión con mayor eficiencia espectral, conducen
a mejores tasas de datos, a la vez que permiten cumplir los requisitos
de QoS.
• Los servicios móviles de vÃdeo broadcast/multicast precisan estrategias
eficientes de SRA con baja complejidad. Hemos propuesto una
estrategia de SRA basada en subgrupos multicast y la técnica de
codificación de vÃdeo escalable (SVC) para la difusión de vÃdeo multicast,
la cual se centra en reducir el espacio de búsqueda de soluciones
y optimizar el ADR. Los resultados obtenidos en términos de ADR,
eficiencia espectral y equidad entre los usuarios multicast, junto con la
baja complejidad del algoritmo, ponen de manifiesto que el esquema
propuesto es adecuado para su implantación en sistemas reales.
Estas contribuciones pretenden servir de referencia que motive la investigación actual y futura en el interesante ámbito de RRM para los servicios
broadcast/multicast en las redes móviles de próxima generación.Programa Oficial de Doctorado en Multimedia y ComunicacionesPresidente: Atilio Manuel Da Silva Gameiro.- Secretario: VÃctor Pedro Gil Jiménez.- Vocal: MarÃa de Diego Antó
Method and device for live-streaming with opportunistic mobile edge cloud offloading
A novel, pervasive approach to disseminating live streaming content combines secure distributed systems, WiFi multicast, erasure coding, source coding and opportunistic offloading using hyperlocal mobile edge clouds. The solution disclosed to the technical problem of disseminating live streaming content without requiring a substantial equipment, planning and deployment of appropriate network infrastructure points offers an 11 fold reduction on the infrastructural WiFi bandwidth usage without having to modify any existing software or firmware stacks while ensuring stream integrity, authorization and authentication
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