14 research outputs found
Pioneering Studies on LTE eMBMS: Towards 5G Point-to-Multipoint Transmissions
The first 5G (5th generation wireless systems) New Radio Release-15 was
recently completed. However, the specification only considers the use of
unicast technologies and the extension to point-to-multipoint (PTM) scenarios
is not yet considered. To this end, we first present in this work a technical
overview of the state-of-the-art LTE (Long Term Evolution) PTM technology,
i.e., eMBMS (evolved Multimedia Broadcast Multicast Services), and investigate
the physical layer performance via link-level simulations. Then based on the
simulation analysis, we discuss potential improvements for the two current
eMBMS solutions, i.e., MBSFN (MBMS over Single Frequency Networks) and SC-PTM
(Single-Cell PTM). This work explicitly focus on equipping the current eMBMS
solutions with 5G candidate techniques, e.g., multiple antennas and millimeter
wave, and its potentials to meet the requirements of next generation PTM
transmissions.Comment: SAM 2018, 5 pages, 4 fig
System Level Simulation of E-MBMS Transmissions in LTE-A
Interference coordination methods for EvolvedMultimedia Broadcast/Multicast Service (E-MBMS) in LongTerm Evolution Advanced (LTE-A) are presented. In this paper, OFDM/OFDMA signals based on LTE parameters are combined with Multipoint MIMO, Turbo codes and signal space diversity methods. Different interference coordination techniques, such as, Multipoint MIMO coordination, Fixed Relay stations, adaptive frequency reuse and schedulers are considered to evaluate the E-MBMS spectral efficiency at the cell borders. The system level coverage and throughput gains of Multipoint MIMO system with hierarchical constellations and Turbo-codes are simulated associated to the presence or not of fixed relays and measuring the maximum spectral efficiencies at cell borders of single cell point-to-multipoint or single frequency network topologies. The influence of the relay transmission power and cell radius in the performance of the previous cellular topologies is also evaluated
A Novel Local and Hyper-Local Multicast Services Transmission Scheme for Beyond 5G Networks
The efficiency of the broadcast network is impacted by the different types of
services that may be transmitted over it. Global services serve users across
the entire network, while local services cater to specific regions, and
hyper-local services have even narrower coverage. Multimedia Broadcast over a
Single-Frequency Network (MBSFN) is typically used for global service
transmission while existing literature extensively discusses schemes for
transmitting local or hyper-local services with or without Single Frequency
Network (SFN) gain. However, these schemes fall short when network-wide
requests for only local and hyper-local services are made, leading operators to
scale down to either Single Cell-Point to Multipoint (SCPtM) or Multi-Frequency
Network (MFN). SCPtM is highly susceptible to interference, and MFN requires
substantial amounts of valuable spectrum. They both employ the Least Channel
Gain (LCG) strategy for transmitting hyper-local services without SFN gain. Our
proposed Local and Hyper-Local Services (LHS) transmission scheme utilizes the
knowledge of user distribution and their corresponding radio link channel
quality to schedule single or multi-resolution, local or hyper-local services
within a three-cell cluster and aims to enhance spectral efficiency and
maximize system throughput. It leverages Scalable Video Coding (SVC) in
conjunction with Hierarchical Modulation (HM) for transmitting multi-resolution
multimedia content to address the problem of heterogeneity amongst the
multicast group users. The proposed scheme also employs macro-diversity
combining with optimal HM parameters for each gNB catering to a local service
area in order to minimize the service outage. System-level simulation results
testify to the better performance achieved by the proposed LHS transmission
scheme with respect to SCPtM.Comment: 12 pages, 18 figures, 2 tables, 3 algorithm
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
On Performance Analysis of Single Frequency Network with C-RAN
Centralized-RAN (C-RAN) is an architectural trend that uses resource sharing and a set of interference mitigation techniques to reduce capital and operational expenditures for mobile network operators (MNOs). One of the technical enablers of a C-RAN solution is single frequency network (SFN) that curbs the interference and allows MNOs to transmit over single frequency across coordinated cells. One of the main advantages of SFN is that it reduces the number of handovers between neighboring cells while improving the overall system performance. In contrast to previous approaches that demonstrate some of the most prominent C-RAN features, in this paper, we first investigate two different SFN deployment scenarios’ characteristics, benefits, and limitations. Second, we perform a simulation analysis of non-SFN and SFN without joint scheduling to observe signal to interference ratio heatmap distribution of the experimental test-site using similar system configurations. Finally, we perform an experimental analysis of joint scheduling in SFN based on coordinated inter baseband units scenario using C-RAN in a realistic environment. The experimental results are tested on a real operating site of a major MNO’s infrastructure in Turkey. Through experimental results, we show overall performance gains of SFN feature in terms of different key performance indicators that are obtained from coordinating remote radio units in an SFN cell. Finally, we discuss about the main takeaways, lessons learned, and challenges of the considered SFN implementation
Multiuser Diversity Management for Multicast/Broadcast Services in 5G and Beyond Networks
The envisaged fifth-generation (5G) and beyond networks represent a paradigm shift for global communications, offering unprecedented breakthroughs in media service delivery with novel capabilities and use cases. Addressing the critical research verticals and challenges that characterize the International Mobile Telecommunications (IMT)-2030 framework requires a compelling mix of enabling radio access technologies (RAT) and native softwarized, disaggregated, and intelligent radio access network (RAN) conceptions. In such a context, the multicast/broadcast ser
vice (MBS) capability is an appealing feature to address the ever-growing traffic demands, disruptive multimedia services, massive connectivity, and low-latency applications.
Embracing the MBS capability as a primary component of the envisaged 5G and beyond networks comes with multiple open challenges. In this research, we contextualize and address the necessity of ensuring stringent quality of service (QoS)/quality of experience (QoE) requirements, multicasting over millimeter-wave (mmWave) and sub-Terahertz (THz) frequencies, and handling complex mobility behaviors. In the broad problem space around these three significant challenges, we focus on the specific research problems of effectively handling the trade-off between multicasting gain and multiuser diversity, along with the trade-off between optimal network performance and computational complexity.
In this research, we cover essential aspects at the intersection of MBS, radio resource management (RRM), machine learning (ML), and the Open RAN (O-RAN) framework. We characterize and address the dynamic multicast multiuser diversity through low-complexity RRM solutions aided by ML, orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) techniques in 5G MBS and beyond networks. We characterize the performance of the multicast access techniques conventional multicast scheme (CMS), subgrouping based on OMA (S-OMA), and subgrouping based on NOMA (S-NOMA). We provide conditions for their adequate selection regarding the specific network conditions (Chapter 4). Consequently,
we propose heuristic methods for the dynamic multicast access technique selection and resource allocation, taking advantage of the multiuser diversity (Chapter 5.1). Moreover, we proposed a multicasting strategy based on fixed pre-computed multiple-input multiple-output (MIMO) multi-beams and S-NOMA (Chapter 5.2). Our approach tackles specific throughput requirements for enabling extended reality (XR) applications attending multiple users and handling their spatial and channel quality diversity.
We address the computational complexity (CC) associated with the dynamic multicast RRM strategies and highlight the implications of fast variations in the reception conditions of the multicast group (MG) members. We propose a low complexity ML-based solution structured by a multicast-oriented trigger to avoid overrunning the algorithm, a K-Means clustering for group-oriented detection and splitting, and a classifier for selecting the most suitable multicast access technique (Chapter 6.1). Our proposed approaches allow addressing the trade-off between optimal network performance and CC by maximizing specific QoS parameters through non-optimal solutions, considerably reducing the CC of conventional exhaustive mechanisms. Moreover, we discuss the insertion of ML-based multicasting RRM solutions into the envisioned disaggregated O-RAN framework (Chapter 6.2.5). We
analyze specific MBS tasks and the importance of a native decentralized, softwarized, and intelligent conception.
We assess the effectiveness of our proposal under multiple numerical and link level simulations of recreated 5G MBS use cases operating in μWave and mmWave. We evaluate various network conditions, service constraints, and users’ mobility behaviors