164 research outputs found
Review on Radio Resource Allocation Optimization in LTE/LTE-Advanced using Game Theory
Recently, there has been a growing trend toward ap-plying game theory (GT) to various engineering fields in order to solve optimization problems with different competing entities/con-tributors/players. Researches in the fourth generation (4G) wireless network field also exploited this advanced theory to overcome long term evolution (LTE) challenges such as resource allocation, which is one of the most important research topics. In fact, an efficient de-sign of resource allocation schemes is the key to higher performance. However, the standard does not specify the optimization approach to execute the radio resource management and therefore it was left open for studies. This paper presents a survey of the existing game theory based solution for 4G-LTE radio resource allocation problem and its optimization
Multimedia content delivery for emerging satellite networks
Multimedia content delivery over satellite systems is considered as a promising service in the emerging networks. The aim of this work is to design a novel radio resource management (RRM) algorithm for efficiently managing multicast multimedia content transmission over satellite network. The proposed approach performs the spectrum management on a per-group basis, by splitting multicast terminals into different subgroups according to the experienced channel qualities. We demonstrate that subgrouping policy defined by the authors as multicast subgrouping-maximum satisfaction index (MS-MSI), is based on a new metric (i.e., MSI), which overcomes the weakness of the previous techniques proposed in literature and provides the best trade-off between user throughput and fairness. As a further result, we demonstrate that MS-MSI is robust to the long propagation delay of satellite links. An extensive simulation campaign has been conducted by considering several satellite environments
Recent Advances in Cellular D2D Communications
Device-to-device (D2D) communications have attracted a great deal of attention from researchers in recent years. It is a promising technique for offloading local traffic from cellular base stations by allowing local devices, in physical proximity, to communicate directly with each other. Furthermore, through relaying, D2D is also a promising approach to enhancing service coverage at cell edges or in black spots. However, there are many challenges to realizing the full benefits of D2D. For one, minimizing the interference between legacy cellular and D2D users operating in underlay mode is still an active research issue. With the 5th generation (5G) communication systems expected to be the main data carrier for the Internet-of-Things (IoT) paradigm, the potential role of D2D and its scalability to support massive IoT devices and their machine-centric (as opposed to human-centric) communications need to be investigated. New challenges have also arisen from new enabling technologies for D2D communications, such as non-orthogonal multiple access (NOMA) and blockchain technologies, which call for new solutions to be proposed. This edited book presents a collection of ten chapters, including one review and nine original research works on addressing many of the aforementioned challenges and beyond
A review on green caching strategies for next generation communication networks
© 2020 IEEE. In recent years, the ever-increasing demand for networking resources and energy, fueled by the unprecedented upsurge in Internet traffic, has been a cause for concern for many service providers. Content caching, which serves user requests locally, is deemed to be an enabling technology in addressing the challenges offered by the phenomenal growth in Internet traffic. Conventionally, content caching is considered as a viable solution to alleviate the backhaul pressure. However, recently, many studies have reported energy cost reductions contributed by content caching in cache-equipped networks. The hypothesis is that caching shortens content delivery distance and eventually achieves significant reduction in transmission energy consumption. This has motivated us to conduct this study and in this article, a comprehensive survey of the state-of-the-art green caching techniques is provided. This review paper extensively discusses contributions of the existing studies on green caching. In addition, the study explores different cache-equipped network types, solution methods, and application scenarios. We categorically present that the optimal selection of the caching nodes, smart resource management, popular content selection, and renewable energy integration can substantially improve energy efficiency of the cache-equipped systems. In addition, based on the comprehensive analysis, we also highlight some potential research ideas relevant to green content caching
Radio resource allocation algorithms for multicast OFDM systems
Mención Internacional en el título 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 vídeo 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
vídeo sean prácticamente el 75 por ciento del tráfico de datos en las redes
móviles hacia el 2022. Las transmisiones multicast son una de las tecnologías
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 vídeo, 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 desafíos, 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
así 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 tecnología 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 física 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 vídeo 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 vídeo escalable (SVC) para la difusión de vídeo 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: Víctor Pedro Gil Jiménez.- Vocal: María de Diego Antó
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