76 research outputs found
Direct communication radio Iinterface for new radio multicasting and cooperative positioning
Cotutela: Universidad de defensa UNIVERSITA’ MEDITERRANEA DI REGGIO CALABRIARecently, the popularity of Millimeter Wave (mmWave) wireless networks has increased due to their capability to cope with the escalation of mobile data demands caused by the unprecedented proliferation of smart devices in the fifth-generation (5G). Extremely high frequency or mmWave band is a fundamental pillar in the provision of the expected gigabit data rates. Hence, according to both academic and industrial communities, mmWave technology, e.g., 5G New Radio (NR) and WiGig (60 GHz), is considered as one of the main components of 5G and beyond networks. Particularly, the 3rd Generation Partnership Project (3GPP) provides for the use of licensed mmWave sub-bands for the 5G mmWave cellular networks, whereas IEEE actively explores the unlicensed band at 60 GHz for the next-generation wireless local area networks. In this regard, mmWave has been envisaged as a new technology
layout for real-time heavy-traffic and wearable applications.
This very work is devoted to solving the problem of mmWave band communication system while enhancing its advantages through utilizing the direct communication radio interface for NR multicasting, cooperative positioning, and mission-critical applications. The main contributions presented in this work include: (i) a set of mathematical frameworks and simulation tools to characterize multicast traffic delivery in mmWave directional systems; (ii) sidelink
relaying concept exploitation to deal with the channel condition deterioration of dynamic multicast systems and to ensure mission-critical and ultra-reliable low-latency communications; (iii) cooperative positioning techniques analysis for enhancing cellular positioning accuracy for 5G+ emerging applications that require not only improved communication characteristics but also precise localization.
Our study indicates the need for additional mechanisms/research that can be utilized: (i) to further improve multicasting performance in 5G/6G systems; (ii) to investigate sideline aspects, including, but not limited to, standardization perspective and the next relay selection strategies; and (iii) to design cooperative positioning systems based on Device-to-Device (D2D) technology
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
5G NR-V2X: Towards Connected and Cooperative Autonomous Driving
This paper is concerned with the key features and fundamental technology
components for 5G New Radio (NR) for genuine realization of connected and
cooperative autonomous driving. We discuss the major functionalities of
physical layer, Sidelink features and its resource allocation, architecture
flexibility, security and privacy mechanisms, and precise positioning
techniques with an evolution path from existing cellular vehicle-to-everything
(V2X) technology towards NR-V2X. Moreover, we envisage and highlight the
potential of machine learning for further enhancement of various NR-V2X
services. Lastly, we show how 5G NR can be configured to support advanced V2X
use cases in autonomous driving
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