16 research outputs found
Performance evaluation of wireless local area network with congested fading channels
The IEEE 802.11ay wireless communication standard consents gadgets to link in the spectrum of millimeter wave (mm-Wave) 60 Giga Hertz band through 100 Gbps bandwidth. The development of promising high bandwidth in communication networks is a must as QoS, throughput and error rates of bandwidth-intensive applications like merged reality (MR), artificial intelligence (AI) related apps or wireless communication boggling exceed the extent of the chronic 802.11 standard established in 2012. Thus, the IEEE 802.11ay task group committee has newly amended recent physical (PHY) and medium access control (MAC) blueprints to guarantee a technical achievement especially in link delay on multipath fading channels (MPFC). However, due to the congestion of super bandwidth intensive apps such as IoT and big data, we propose to diversify a propagation delay to practical extension. This article then focuses on a real-world situation and how the IEEE 802.11ay design is affected by the performance of mm-Wave propagation. In specific, we randomize the unstable MPFC link capacity by taking the divergence of congested network parameters into account. The efficiency of congested MPFC-based wireless network is simulated and confirmed by advancements described in the standard
Multi-User Ultra-Massive MIMO for very high frequency bands (mmWave and THz): a resource allocation problem
A dynamic subarray allocation for multi-user massive MIMO systems working in very high frequency bands (mmWave and THz) is proposed as a promising technique to unleash the capacity limits in future cellular networks capable of supporting high consuming bandwidth applications
Enhanced Next Generation Millimeter-Wave Multicarrier System with Generalized Frequency Division Multiplexing
Orthogonal Frequency Division Multiplexing (OFDM) is a popular multicarrier technique used to attain high spectral efficiencies. It also has other advantages such as multipath tolerance and ease of implementation. However, OFDM based systems suffer from high Peak-to-Average Power Ratio (PAPR) problem. Because of the nonlinearity of the power amplifiers, the high PAPR causes significant distortion in the transmitted signal for millimeter-wave (mmWave) systems. To alleviate the high PAPR problem, this paper utilizes Generalized Frequency Division Multiplexing (GFDM) which can achieve high spectral efficiency as well as low PAPR. In this paper, we show the performance of GFDM using the IEEE 802.11ad multicarrier frame structures. IEEE 802.11ad is considered one of the most successful industry standards utilizing unlicensed mmWave frequency band. In addition, this paper indicates the feasibility of using GFDM for the future standards such as IEEE 802.11ay. This paper studies the performance improvements in terms of PAPR reduction for GFDM. Based on the performance results, the optimal numbers of subcarriers and subsymbols are calculated for PAPR reduction while minimizing the Bit Error Rate (BER) performance degradation. Moreover, transmitter side ICI (Intercarrier Interference) reduction is introduced to reduce the receiver load
Heterogeneous Acceleration for 5G New Radio Channel Modelling Using FPGAs and GPUs
L'abstract è presente nell'allegato / the abstract is in the attachmen
Ondas milimétricas e MIMO massivo para otimização da capacidade e cobertura de redes heterogeneas de 5G
Today's Long Term Evolution Advanced (LTE-A) networks cannot support
the exponential growth in mobile traffic forecast for the next decade. By
2020, according to Ericsson, 6 billion mobile subscribers worldwide are projected
to generate 46 exabytes of mobile data traffic monthly from 24 billion
connected devices, smartphones and short-range Internet of Things (IoT)
devices being the key prosumers. In response, 5G networks are foreseen
to markedly outperform legacy 4G systems. Triggered by the International
Telecommunication Union (ITU) under the IMT-2020 network initiative, 5G
will support three broad categories of use cases: enhanced mobile broadband
(eMBB) for multi-Gbps data rate applications; ultra-reliable and low latency
communications (URLLC) for critical scenarios; and massive machine
type communications (mMTC) for massive connectivity. Among the several
technology enablers being explored for 5G, millimeter-wave (mmWave)
communication, massive MIMO antenna arrays and ultra-dense small cell
networks (UDNs) feature as the dominant technologies. These technologies
in synergy are anticipated to provide the 1000_ capacity increase for 5G
networks (relative to 4G) through the combined impact of large additional
bandwidth, spectral efficiency (SE) enhancement and high frequency reuse,
respectively. However, although these technologies can pave the way towards
gigabit wireless, there are still several challenges to solve in terms of
how we can fully harness the available bandwidth efficiently through appropriate
beamforming and channel modeling approaches. In this thesis, we
investigate the system performance enhancements realizable with mmWave
massive MIMO in 5G UDN and cellular infrastructure-to-everything (C-I2X)
application scenarios involving pedestrian and vehicular users. As a critical
component of the system-level simulation approach adopted in this thesis,
we implemented 3D channel models for the accurate characterization of the
wireless channels in these scenarios and for realistic performance evaluation.
To address the hardware cost, complexity and power consumption of the
massive MIMO architectures, we propose a novel generalized framework for
hybrid beamforming (HBF) array structures. The generalized model reveals
the opportunities that can be harnessed with the overlapped subarray structures
for a balanced trade-o_ between SE and energy efficiently (EE) of 5G
networks. The key results in this investigation show that mmWave massive
MIMO can deliver multi-Gbps rates for 5G whilst maintaining energy-efficient operation of the network.As redes LTE-A atuais não são capazes de suportar o crescimento exponencial
de tráfego que está previsto para a próxima década. De acordo
com a previsão da Ericsson, espera-se que em 2020, a nÃvel global, 6 mil
milhões de subscritores venham a gerar mensalmente 46 exa bytes de tráfego
de dados a partir de 24 mil milhões de dispositivos ligados à rede móvel,
sendo os telefones inteligentes e dispositivos IoT de curto alcance os principais
responsáveis por tal nÃvel de tráfego. Em resposta a esta exigência,
espera-se que as redes de 5a geração (5G) tenham um desempenho substancialmente
superior às redes de 4a geração (4G) atuais. Desencadeado pelo
UIT (União Internacional das Telecomunicações) no âmbito da iniciativa
IMT-2020, o 5G irá suportar três grandes tipos de utilizações: banda larga
móvel capaz de suportar aplicações com débitos na ordem de vários Gbps;
comunicações de baixa latência e alta fiabilidade indispensáveis em cenários
de emergência; comunicações massivas máquina-a-máquina para conectividade
generalizada. Entre as várias tecnologias capacitadoras que estão a ser
exploradas pelo 5G, as comunicações através de ondas milimétricas, os agregados
MIMO massivo e as redes celulares ultradensas (RUD) apresentam-se
como sendo as tecnologias fundamentais. Antecipa-se que o conjunto
destas tecnologias venha a fornecer às redes 5G um aumento de capacidade
de 1000x através da utilização de maiores larguras de banda, melhoria da
eficiência espectral, e elevada reutilização de frequências respetivamente.
Embora estas tecnologias possam abrir caminho para as redes sem fios
com débitos na ordem dos gigabits, existem ainda vários desafios que têm
que ser resolvidos para que seja possÃvel aproveitar totalmente a largura de
banda disponÃvel de maneira eficiente utilizando abordagens de formatação
de feixe e de modelação de canal adequadas. Nesta tese investigamos a
melhoria de desempenho do sistema conseguida através da utilização de
ondas milimétricas e agregados MIMO massivo em cenários de redes celulares
ultradensas de 5a geração e em cenários 'infraestrutura celular-para-qualquer
coisa' (do inglês: cellular infrastructure-to-everything) envolvendo
utilizadores pedestres e veiculares. Como um componente fundamental das
simulações de sistema utilizadas nesta tese é o canal de propagação, implementamos modelos de canal tridimensional (3D) para caracterizar de
forma precisa o canal de propagação nestes cenários e assim conseguir uma
avaliação de desempenho mais condizente com a realidade. Para resolver os
problemas associados ao custo do equipamento, complexidade e consumo
de energia das arquiteturas MIMO massivo, propomos um modelo inovador
de agregados com formatação de feixe hÃbrida. Este modelo genérico revela
as oportunidades que podem ser aproveitadas através da sobreposição
de sub-agregados no sentido de obter um compromisso equilibrado entre
eficiência espectral (ES) e eficiência energética (EE) nas redes 5G. Os principais
resultados desta investigação mostram que a utilização conjunta de
ondas milimétricas e de agregados MIMO massivo possibilita a obtenção, em
simultâneo, de taxas de transmissão na ordem de vários Gbps e a operação
de rede de forma energeticamente eficiente.Programa Doutoral em Telecomunicaçõe
ERROR CORRECTION CODE-BASED EMBEDDING IN ADAPTIVE RATE WIRELESS COMMUNICATION SYSTEMS
In this dissertation, we investigated the methods for development of embedded channels within error
correction mechanisms utilized to support adaptive rate communication systems. We developed an error
correction code-based embedding scheme suitable for application in modern wireless data communication
standards. We specifically implemented the scheme for both low-density parity check block codes and
binary convolutional codes. While error correction code-based information hiding has been previously
presented in literature, we sought to take advantage of the fact that these wireless systems have the ability to
change their modulation and coding rates in response to changing channel conditions. We utilized this
functionality to incorporate knowledge of the channel state into the scheme, which led to an increase in
embedding capacity. We conducted extensive simulations to establish the performance of our embedding
methodologies. Results from these simulations enabled the development of models to characterize the
behavior of the embedded channels and identify sources of distortion in the underlying communication
system. Finally, we developed expressions to define limitations on the capacity of these channels subject to
a variety of constraints, including the selected modulation type and coding rate of the communication
system, the current channel state, and the specific embedding implementation.Commander, United States NavyApproved for public release; distribution is unlimited
Real-time wireless networks for industrial control systems
The next generation of industrial systems (Industry 4.0) will dramatically transform manyproductive sectors, integrating emerging concepts such as Internet of Things, artificialintelligence, big data, cloud robotics and virtual reality, to name a few. Most of thesetechnologies heavily rely on the availability of communication networks able to offernearly–istantaneous, secure and reliable data transfer. In the industrial sector, these
tasks are nowadays mainly accomplished by wired networks, that combine the speed ofoptical fiber media with collision–free switching technology.
However, driven by the pervasive deployment of mobile devices for personal com-munications in the last years, more and more industrial applications require wireless connectivity, which can bring enormous advantages in terms of cost reduction and flex-ibility. Designing timely, reliable and deterministic industrial wireless networks is a complicated task, due to the nature of the wireless channel, intrinsically error–prone andshared among all the devices transmitting on the same frequency band.
In this thesis, several solutions to enhance the performance of wireless networks employed in industrial control applications are proposed. The presented approaches differ in terms of achieved performance and target applications, but they are all characterized by an improvement over existing industrial wireless solutions in terms of timeliness, reliability and determinism. When possible, an experimental validation of the designed
solutions is provided.
The obtained results prove that significant performance improvements are already possible, often using commercially available devices and preserving compliance to existing standards. Future research efforts, combined with the availability of new chipsets and
standards, could lead to a world where wireless links effectively replace most of the existing cables in industrial environments, as it is already the case in the consumer market
Cellular and Wi-Fi technologies evolution: from complementarity to competition
This PhD thesis has the characteristic to span over a long time because while working on it, I was working as a research engineer at CTTC with highly demanding development duties. This has delayed the deposit more than I would have liked. On the other hand, this has given me the privilege of witnessing and studying how wireless technologies have been evolving over a decade from 4G to 5G and beyond.
When I started my PhD thesis, IEEE and 3GPP were defining the two main wireless technologies at the time, Wi-Fi and LTE, for covering two substantially complementary market targets. Wi-Fi was designed to operate mostly indoor, in unlicensed spectrum, and was aimed to be a simple and cheap technology. Its primary technology for coexistence was based on the assumption that the spectrum on which it was operating was for free, and so it was designed with interference avoidance through the famous CSMA/CA protocol. On the other hand, 3GPP was designing technologies for licensed spectrum, a costly kind of spectrum. As a result, LTE was designed to take the best advantage of it while providing the best QoE in mainly outdoor scenarios.
The PhD thesis starts in this context and evolves with these two technologies. In the first chapters, the thesis studies radio resource management solutions for standalone operation of Wi-Fi in unlicensed and LTE in licensed spectrum. We anticipated the now fundamental machine learning trend by working on machine learning-based radio resource management solutions to improve LTE and Wi-Fi operation in their respective spectrum. We pay particular attention to small cell deployments aimed at improving the spectrum efficiency in licensed spectrum, reproducing small range scenarios typical of Wi-Fi settings.
IEEE and 3GPP followed evolving the technologies over the years: Wi-Fi has grown into a much more complex and sophisticated technology, incorporating the key features of cellular technologies, like HARQ, OFDMA, MU-MIMO, MAC scheduling and spatial reuse. On the other hand, since Release 13, cellular networks have also been designed for unlicensed spectrum. As a result, the two last chapters of this thesis focus on coexistence scenarios, in which LTE needs to be designed to coexist with Wi-Fi fairly, and NR, the radio access for 5G, with Wi-Fi in 5 GHz and WiGig in 60 GHz. Unlike LTE, which was adapted to operate in unlicensed spectrum, NR-U is natively designed with this feature, including its capability to operate in unlicensed in a complete standalone fashion, a fundamental new milestone for cellular. In this context, our focus of analysis changes. We consider that these two technological families are no longer targeting complementarity but are now competing, and we claim that this will be the trend for the years to come.
To enable the research in these multi-RAT scenarios, another fundamental result of this PhD thesis, besides the scientific contributions, is the release of high fidelity models for LTE and NR and their coexistence with Wi-Fi and WiGig to the ns-3 open-source community. ns-3 is a popular open-source network simulator, with the characteristic to be multi-RAT and so naturally allows the evaluation of coexistence scenarios between different technologies. These models, for which I led the development, are by academic citations, the most used open-source simulation models for LTE and NR and havereceived fundings from industry (Ubiquisys, WFA, SpiderCloud, Interdigital, Facebook) and federal agencies (NIST, LLNL) over the years.Aquesta tesi doctoral té la caracterÃstica d’allargar-se durant un llarg perÃode de temps ja que mentre treballava en ella, treballava com a enginyera investigadora a CTTC amb tasques de desenvolupament molt exigents. Això ha endarrerit el dipositar-la més del que m’hagués agradat. D’altra banda, això m’ha donat el privilegi de ser testimoni i estudiar com han evolucionat les tecnologies sense fils durant més d’una dècada des del 4G fins al 5G i més enllà . Quan vaig començar la tesi doctoral, IEEE i 3GPP estaven definint les dues tecnologies sense fils principals en aquell moment, Wi-Fi i LTE, que cobreixen dos objectius de mercat substancialment complementaris. Wi-Fi va ser dissenyat per funcionar principalment en interiors, en espectre sense llicència, i pretenia ser una tecnologia senzilla i barata. La seva tecnologia primà ria per a la convivència es basava en el supòsit que l’espectre en el que estava operant era de franc, i, per tant, es va dissenyar simplement evitant interferències a través del famós protocol CSMA/CA. D’altra banda, 3GPP estava dissenyant tecnologies per a espectres amb llicència, un tipus d’espectre costós. Com a resultat, LTE està dissenyat per treure’n el mà xim profit alhora que proporciona el millor QoE en escenaris principalment a l’aire lliure. La tesi doctoral comença amb aquest context i evoluciona amb aquestes dues tecnologies. En els primers capÃtols, estudiem solucions de gestió de recursos de radio per a operacions en espectre de Wi-Fi sense llicència i LTE amb llicència. Hem anticipat l’actual tendència fonamental d’aprenentatge automà tic treballant solucions de gestió de recursos de radio basades en l’aprenentatge automà tic per millorar l’LTE i Wi-Fi en el seu espectre respectiu. Prestem especial atenció als desplegaments de cèl·lules petites destinades a millorar la eficiència d’espectre llicenciat, reproduint escenaris de petit abast tÃpics de la configuració Wi-Fi. IEEE i 3GPP van seguir evolucionant les tecnologies al llarg dels anys: El Wi-Fi s’ha convertit en una tecnologia molt més complexa i sofisticada, incorporant les caracterÃstiques clau de les tecnologies cel·lulars, com ara HARQ i la reutilització espacial. D’altra banda, des de la versió 13, també s’han dissenyat xarxes cel·lulars per a espectre sense llicència. Com a resultat, els dos darrers capÃtols d’aquesta tesi es centren en aquests escenaris de convivència, on s’ha de dissenyar LTE per conviure amb la Wi-Fi de manera justa, i NR, l’accés a la radio per a 5G amb Wi-Fi a 5 GHz i WiGig a 60 GHz. A diferència de LTE, que es va adaptar per funcionar en espectre sense llicència, NR-U està dissenyat de forma nativa amb aquesta caracterÃstica, inclosa la seva capacitat per operar sense llicència de forma autònoma completa, una nova fita fonamental per al mòbil. En aquest context, el nostre focus d’anà lisi canvia. Considerem que aquestes dues famÃlies de tecnologia ja no estan orientades cap a la complementarietat, sinó que ara competeixen, i afirmem que aquesta serà el tendència per als propers anys. Per permetre la investigació en aquests escenaris multi-RAT, un altre resultat fonamental d’aquesta tesi doctoral, a més de les aportacions cientÃfiques, és l’alliberament de models d’alta fidelitat per a LTE i NR i la seva coexistència amb Wi-Fi a la comunitat de codi obert ns-3. ns-3 és un popular simulador de xarxa de codi obert, amb la caracterÃstica de ser multi-RAT i, per tant, permet l’avaluació de manera natural d’escenaris de convivència entre diferents tecnologies. Aquests models, pels quals he liderat el desenvolupament, són per cites acadèmiques, els models de simulació de codi obert més utilitzats per a LTE i NR i que han rebut finançament de la indústria (Ubiquisys, WFA, SpiderCloud, Interdigital, Facebook) i agències federals (NIST, LLNL) al llarg dels anys.Esta tesis doctoral tiene la caracterÃstica de extenderse durante mucho tiempo porque mientras trabajaba en ella, trabajaba como ingeniera de investigación en CTTC con tareas de desarrollo muy exigentes. Esto ha retrasado el depósito más de lo que me hubiera gustado. Por otro lado,
gracias a ello, he tenido el privilegio de presenciar y estudiar como las tecnologÃas inalámbricas
han evolucionado durante una década, de 4G a 5G y más allá.
Cuando comencé mi tesis doctoral, IEEE y 3GPP estaban definiendo las dos principales
tecnologÃas inalámbricas en ese momento, Wi-Fi y LTE, cumpliendo dos objetivos de mercado
sustancialmente complementarios. Wi-Fi fue diseñado para funcionar principalmente en
interiores, en un espectro sin licencia, y estaba destinado a ser una tecnologÃa simple y barata.
Su tecnologÃa primaria para la convivencia se basaba en el supuesto en que el espectro en
el que estaba operando era gratis, y asà fue diseñado simplemente evitando interferencias a
través del famoso protocolo CSMA/CA. Por otro lado, 3GPP estaba diseñando tecnologÃas
para espectro con licencia, un tipo de espectro costoso. Como resultado, LTE está diseñado
para aprovechar el espectro al máximo proporcionando al mismo tiempo el mejor QoE en
escenarios principalmente al aire libre.
La tesis doctoral parte de este contexto y evoluciona con estas dos tecnologÃas. En los
primeros capÃtulos, estudiamos las soluciones de gestión de recursos de radio para operación
en espectro Wi-Fi sin licencia y LTE con licencia. Anticipamos la tendencia ahora fundamental
de aprendizaje automático trabajando en soluciones de gestión de recursos de radio para
mejorar LTE y funcionamiento deWi-Fi en su respectivo espectro. Prestamos especial atención
a las implementaciones de células pequeñas destinadas a mejorar la eficiencia de espectro
licenciado, reproduciendo los tÃpicos escenarios de rango pequeño de la configuración Wi-Fi.
IEEE y 3GPP siguieron evolucionando las tecnologÃas a lo largo de los años: Wi-Fi
se ha convertido en una tecnologÃa mucho más compleja y sofisticada, incorporando las
caracterÃsticas clave de las tecnologÃas celulares, como HARQ, OFDMA, MU-MIMO, MAC
scheduling y la reutilización espacial. Por otro lado, desde la Release 13, también se han
diseñado redes celulares para espectro sin licencia. Como resultado, los dos últimos capÃtulos
de esta tesis se centran en estos escenarios de convivencia, donde LTE debe diseñarse para
coexistir con Wi-Fi de manera justa, y NR, el acceso por radio para 5G con Wi-Fi en 5 GHz
y WiGig en 60 GHz. A diferencia de LTE, que se adaptó para operar en espectro sin licencia,
NR-U está diseñado de forma nativa con esta función, incluyendo su capacidad para operar
sin licencia de forma completamente independiente, un nuevo hito fundamental para los
celulares. En este contexto, cambia nuestro enfoque de análisis. Consideramos que estas dos
familias tecnológicas ya no tienen como objetivo la complementariedad, sino que ahora están
compitiendo, y afirmamos que esta será la tendencia para los próximos años.
Para permitir la investigación en estos escenarios de múltiples RAT, otro resultado fundamental
de esta tesis doctoral, además de los aportes cientÃficos, es el lanzamiento de modelos de alta
fidelidad para LTE y NR y su coexistencia con Wi-Fi y WiGig a la comunidad de código
abierto de ns-3. ns-3 es un simulador popular de red de código abierto, con la caracterÃstica
de ser multi-RAT y asÃ, naturalmente, permite la evaluación de escenarios de convivencia
entre diferentes tecnologÃas. Estos modelos, para los cuales lideré el desarrollo, son por citas
académicas, los modelos de simulación de código abierto más utilizados para LTE y NR y
han recibido fondos de la industria (Ubiquisys, WFA, SpiderCloud, Interdigital, Facebook) y
agencias federales (NIST, LLNL) a lo largo de los años.Postprint (published version