407 research outputs found
Advanced Technologies Enabling Unlicensed Spectrum Utilization in Cellular Networks
As the rapid progress and pleasant experience of Internet-based services, there is an increasing demand for high data rate in wireless communications systems. Unlicensed spectrum utilization in Long Term Evolution (LTE) networks is a promising technique to meet the massive traffic
demand. There are two effective methods to use unlicensed bands for delivering LTE traffic. One is offloading LTE traffic toWi-Fi. An alternative method is LTE-unlicensed (LTE-U), which aims to directly use LTE protocols and infrastructures over the unlicensed spectrum. It has also
been pointed out that addressing the above two methods simultaneously could further improve the system performance.
However, how to avoid severe performance degradation of the Wi-Fi network is a challenging issue of utilizing unlicensed spectrum in LTE networks. Specifically, first, the inter-system spectrum sharing, or, more specifically, the coexistence of LTE andWi-Fi in the same unlicensed
spectrum is the major challenge of implementing LTE-U. Second, to use the LTE and Wi-Fi integration approach, mobile operators have to manage two disparate networks in licensed and unlicensed spectrum. Third, optimization for joint data offloading to Wi-Fi and LTE-U in multi-
cell scenarios poses more challenges because inter-cell interference must be addressed.
This thesis focuses on solving problems related to these challenges. First, the effect of bursty traffic in an LTE and Wi-Fi aggregation (LWA)-enabled network has been investigated. To enhance resource efficiency, the Wi-Fi access point (AP) is designed to operate in both the native
mode and the LWA mode simultaneously. Specifically, the LWA-modeWi-Fi AP cooperates with the LTE base station (BS) to transmit bearers to the LWA user, which aggregates packets from both LTE and Wi-Fi. The native-mode Wi-Fi AP transmits Wi-Fi packets to those native Wi-Fi users that are not with LWA capability. This thesis proposes a priority-based Wi-Fi transmission scheme with congestion control and studied the throughput of the native Wi-Fi network, as well as the LWA user delay when the native Wi-Fi user is under heavy traffic conditions. The results
provide fundamental insights in the throughput and delay behavior of the considered network. Second, the above work has been extended to larger topologies. A stochastic geometry model has been used to model and analyze the performance of an MPTCP Proxy-based LWA network with intra-tier and cross-tier dependence. Under the considered network model and the activation conditions of LWA-mode Wi-Fi, this thesis has obtained three approximations for the density of active LWA-mode Wi-Fi APs through different approaches. Tractable analysis is provided for the downlink (DL) performance evaluation of large-scale LWA networks. The impact of different parameters on the network performance have been analyzed, validating the significant gain of using LWA in terms of boosted data rate and improved spectrum reuse. Third, this thesis also takes a significant step of analyzing joint multi-cell LTE-U and Wi-Fi network, while taking into account different LTE-U and Wi-Fi inter-working schemes. In particular, two technologies enabling data offloading from LTE to Wi-Fi are considered, including LWA and Wi-Fi offloading in the context of the power gain-based user offloading scheme. The LTE cells in this work are subject to load-coupling due to inter-cell interference. New system frameworks for maximizing the demand scaling factor for all users in both Wi-Fi and multi-cell LTE networks have been proposed. The potential of networks is explored in achieving optimal capacity with arbitrary topologies, accounting for both resource limits and inter-cell interference. Theoretical analyses have been proposed for the proposed optimization problems, resulting in algorithms that achieve global optimality. Numerical results show the algorithms’ effectiveness and benefits of joint use of data offloading and the direct use of LTE over the unlicensed band. All the derived results in this thesis have been validated by Monte Carlo simulations in Matlab, and the conclusions observed from the results can provide guidelines for the future unlicensed spectrum utilization in LTE networks
Towards Massive Machine Type Communications in Ultra-Dense Cellular IoT Networks: Current Issues and Machine Learning-Assisted Solutions
The ever-increasing number of resource-constrained Machine-Type Communication
(MTC) devices is leading to the critical challenge of fulfilling diverse
communication requirements in dynamic and ultra-dense wireless environments.
Among different application scenarios that the upcoming 5G and beyond cellular
networks are expected to support, such as eMBB, mMTC and URLLC, mMTC brings the
unique technical challenge of supporting a huge number of MTC devices, which is
the main focus of this paper. The related challenges include QoS provisioning,
handling highly dynamic and sporadic MTC traffic, huge signalling overhead and
Radio Access Network (RAN) congestion. In this regard, this paper aims to
identify and analyze the involved technical issues, to review recent advances,
to highlight potential solutions and to propose new research directions. First,
starting with an overview of mMTC features and QoS provisioning issues, we
present the key enablers for mMTC in cellular networks. Along with the
highlights on the inefficiency of the legacy Random Access (RA) procedure in
the mMTC scenario, we then present the key features and channel access
mechanisms in the emerging cellular IoT standards, namely, LTE-M and NB-IoT.
Subsequently, we present a framework for the performance analysis of
transmission scheduling with the QoS support along with the issues involved in
short data packet transmission. Next, we provide a detailed overview of the
existing and emerging solutions towards addressing RAN congestion problem, and
then identify potential advantages, challenges and use cases for the
applications of emerging Machine Learning (ML) techniques in ultra-dense
cellular networks. Out of several ML techniques, we focus on the application of
low-complexity Q-learning approach in the mMTC scenarios. Finally, we discuss
some open research challenges and promising future research directions.Comment: 37 pages, 8 figures, 7 tables, submitted for a possible future
publication in IEEE Communications Surveys and Tutorial
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 tĂ© la caracterĂstica d’allargar-se durant un llarg perĂode 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 mĂ©s del que m’haguĂ©s agradat. D’altra banda, això m’ha donat el privilegi de ser testimoni i estudiar com han evolucionat les tecnologies sense fils durant mĂ©s d’una dècada des del 4G fins al 5G i mĂ©s enllĂ . 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 primĂ 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 travĂ©s del famĂłs protocol CSMA/CA. D’altra banda, 3GPP estava dissenyant tecnologies per a espectres amb llicència, un tipus d’espectre costĂłs. Com a resultat, LTE estĂ dissenyat per treure’n el mĂ 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 capĂtols, estudiem solucions de gestiĂł 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 automĂ tic treballant solucions de gestiĂł de recursos de radio basades en l’aprenentatge automĂ tic per millorar l’LTE i Wi-Fi en el seu espectre respectiu. Prestem especial atenciĂł als desplegaments de cèl·lules petites destinades a millorar la eficiència d’espectre llicenciat, reproduint escenaris de petit abast tĂpics de la configuraciĂł Wi-Fi. IEEE i 3GPP van seguir evolucionant les tecnologies al llarg dels anys: El Wi-Fi s’ha convertit en una tecnologia molt mĂ©s complexa i sofisticada, incorporant les caracterĂstiques clau de les tecnologies cel·lulars, com ara HARQ i la reutilitzaciĂł espacial. D’altra banda, des de la versiĂł 13, tambĂ© s’han dissenyat xarxes cel·lulars per a espectre sense llicència. Com a resultat, els dos darrers capĂtols 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’accĂ©s 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 estĂ dissenyat de forma nativa amb aquesta caracterĂstica, 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’anĂ lisi canvia. Considerem que aquestes dues famĂlies de tecnologia ja no estan orientades cap a la complementarietat, sinĂł que ara competeixen, i afirmem que aquesta serĂ el tendència per als propers anys. Per permetre la investigaciĂł en aquests escenaris multi-RAT, un altre resultat fonamental d’aquesta tesi doctoral, a mĂ©s de les aportacions cientĂfiques, Ă©s 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 Ă©s un popular simulador de xarxa de codi obert, amb la caracterĂstica de ser multi-RAT i, per tant, permet l’avaluaciĂł de manera natural d’escenaris de convivència entre diferents tecnologies. Aquests models, pels quals he liderat el desenvolupament, sĂłn per cites acadèmiques, els models de simulaciĂł de codi obert mĂ©s utilitzats per a LTE i NR i que han rebut finançament de la indĂşstria (Ubiquisys, WFA, SpiderCloud, Interdigital, Facebook) i agències federals (NIST, LLNL) al llarg dels anys.Esta tesis doctoral tiene la caracterĂstica de extenderse durante mucho tiempo porque mientras trabajaba en ella, trabajaba como ingeniera de investigaciĂłn en CTTC con tareas de desarrollo muy exigentes. Esto ha retrasado el depĂłsito más de lo que me hubiera gustado. Por otro lado,
gracias a ello, he tenido el privilegio de presenciar y estudiar como las tecnologĂas 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
tecnologĂas 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 tecnologĂa simple y barata.
Su tecnologĂa 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
travĂ©s del famoso protocolo CSMA/CA. Por otro lado, 3GPP estaba diseñando tecnologĂas
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 tecnologĂas. En los
primeros capĂtulos, estudiamos las soluciones de gestiĂłn de recursos de radio para operaciĂłn
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 atenciĂłn
a las implementaciones de células pequeñas destinadas a mejorar la eficiencia de espectro
licenciado, reproduciendo los tĂpicos escenarios de rango pequeño de la configuraciĂłn Wi-Fi.
IEEE y 3GPP siguieron evolucionando las tecnologĂas a lo largo de los años: Wi-Fi
se ha convertido en una tecnologĂa mucho más compleja y sofisticada, incorporando las
caracterĂsticas clave de las tecnologĂas 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 Ăşltimos capĂtulos
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 adaptĂł 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 investigaciĂłn en estos escenarios de mĂşltiples RAT, otro resultado fundamental
de esta tesis doctoral, además de los aportes cientĂficos, es el lanzamiento de modelos de alta
fidelidad para LTE y NR y su coexistencia con Wi-Fi y WiGig a la comunidad de cĂłdigo
abierto de ns-3. ns-3 es un simulador popular de red de cĂłdigo abierto, con la caracterĂstica
de ser multi-RAT y asĂ, naturalmente, permite la evaluaciĂłn de escenarios de convivencia
entre diferentes tecnologĂas. Estos modelos, para los cuales liderĂ© 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
Survey of Spectrum Sharing for Inter-Technology Coexistence
Increasing capacity demands in emerging wireless technologies are expected to
be met by network densification and spectrum bands open to multiple
technologies. These will, in turn, increase the level of interference and also
result in more complex inter-technology interactions, which will need to be
managed through spectrum sharing mechanisms. Consequently, novel spectrum
sharing mechanisms should be designed to allow spectrum access for multiple
technologies, while efficiently utilizing the spectrum resources overall.
Importantly, it is not trivial to design such efficient mechanisms, not only
due to technical aspects, but also due to regulatory and business model
constraints. In this survey we address spectrum sharing mechanisms for wireless
inter-technology coexistence by means of a technology circle that incorporates
in a unified, system-level view the technical and non-technical aspects. We
thus systematically explore the spectrum sharing design space consisting of
parameters at different layers. Using this framework, we present a literature
review on inter-technology coexistence with a focus on wireless technologies
with equal spectrum access rights, i.e. (i) primary/primary, (ii)
secondary/secondary, and (iii) technologies operating in a spectrum commons.
Moreover, we reflect on our literature review to identify possible spectrum
sharing design solutions and performance evaluation approaches useful for
future coexistence cases. Finally, we discuss spectrum sharing design
challenges and suggest future research directions
Optimization of 5G Second Phase Heterogeneous Radio Access Networks with Small Cells
Due to the exponential increase in high data-demanding applications and their services per
coverage area, it is becoming challenging for the existing cellular network to handle the massive
sum of users with their demands. It is conceded to network operators that the current
wireless network may not be capable to shelter future traffic demands. To overcome the challenges
the operators are taking interest in efficiently deploying the heterogeneous network.
Currently, 5G is in the commercialization phase. Network evolution with addition of small
cells will develop the existing wireless network with its enriched capabilities and innovative
features. Presently, the 5G global standardization has introduced the 5G New Radio (NR) under
the 3rd Generation Partnership Project (3GPP). It can support a wide range of frequency
bands (<6 GHz to 100 GHz).
For different trends and verticals, 5G NR encounters, functional splitting and its cost evaluation
are well-thought-out. The aspects of network slicing to the assessment of the business
opportunities and allied standardization endeavours are illustrated. The study explores the
carrier aggregation (Pico cellular) technique for 4G to bring high spectral efficiency with the
support of small cell massification while benefiting from statistical multiplexing gain. One
has been able to obtain values for the goodput considering CA in LTE-Sim (4G), of 40 Mbps
for a cell radius of 500 m and of 29 Mbps for a cell radius of 50 m, which is 3 times higher
than without CA scenario (2.6 GHz plus 3.5 GHz frequency bands).
Heterogeneous networks have been under investigation for many years. Heterogeneous network
can improve users service quality and resource utilization compared to homogeneous
networks. Quality of service can be enhanced by putting the small cells (Femtocells or Picocells)
inside the Microcells or Macrocells coverage area. Deploying indoor Femtocells for 5G
inside the Macro cellular network can reduce the network cost. Some service providers have
started their solutions for indoor users but there are still many challenges to be addressed.
The 5G air-simulator is updated to deploy indoor Femto-cell with proposed assumptions with
uniform distribution. For all the possible combinations of apartments side length and transmitter
power, the maximum number of supported numbers surpassed the number of users
by more than two times compared to papers mentioned in the literature. Within outdoor environments,
this study also proposed small cells optimization by putting the Pico cells within
a Macro cell to obtain low latency and high data rate with the statistical multiplexing gain of
the associated users.
Results are presented 5G NR functional split six and split seven, for three frequency bands
(2.6 GHz, 3.5GHz and 5.62 GHz). Based on the analysis for shorter radius values, the best
is to select the 2.6 GHz to achieve lower PLR and to support a higher number of users, with
better goodput, and higher profit (for cell radius u to 400 m). In 4G, with CA, from the
analysis of the economic trade-off with Picocell, the Enhanced multi-band scheduler EMBS
provide higher revenue, compared to those without CA. It is clearly shown that the profit of
CA is more than 4 times than in the without CA scenario. This means that the slight increase
in the cost of CA gives back more than 4-time profit relatively to the ”without” CA scenario.Devido ao aumento exponencial de aplicações/serviços de elevado débito por unidade de
área, torna-se bastante exigente, para a rede celular existente, lidar com a enormes quantidades
de utilizadores e seus requisitos. É reconhecido que as redes móveis e sem fios atuais
podem não conseguir suportar a procura de tráfego junto dos operadores. Para responder
a estes desafios, os operadores estão-se a interessar pelo desenvolvimento de redes heterogéneas
eficientes. Atualmente, a 5G está na fase de comercialização. A evolução destas
redes concretizar-se-á com a introdução de pequenas células com aptidões melhoradas e
caracterĂsticas inovadoras. No presente, os organismos de normalização da 5G globais introduziram
os Novos Rádios (NR) 5G no contexto do 3rd Generation Partnership Project
(3GPP). A 5G pode suportar uma gama alargada de bandas de frequĂŞncia (<6 a 100 GHz).
Abordam-se as divisões funcionais e avaliam-se os seus custos para as diferentes tendências
e verticais dos NR 5G. Ilustram-se desde os aspetos de particionamento funcional da rede Ă
avaliação das oportunidades de negócio, aliadas aos esforços de normalização. Exploram-se
as técnicas de agregação de espetro (do inglês, CA) para pico células, em 4G, a disponibilização
de eficiência espetral, com o suporte da massificação de pequenas células, e o ganho
de multiplexagem estatĂstica associado. Obtiveram-se valores do dĂ©bito binário Ăştil, considerando
CA no LTE-Sim (4G), de 40 e 29 Mb/s para células de raios 500 e 50 m, respetivamente,
três vezes superiores em relação ao caso sem CA (bandas de 2.6 mais 3.5 GHz).
Nas redes heterogéneas, alvo de investigação há vários anos, a qualidade de serviço e a utilização
de recursos podem ser melhoradas colocando pequenas células (femto- ou pico-células)
dentro da área de cobertura de micro- ou macro-células). O desenvolvimento de pequenas
células 5G dentro da rede com macro-células pode reduzir os custos da rede. Alguns prestadores
de serviços iniciaram as suas soluções para ambientes de interior, mas ainda existem
muitos desafios a ser ultrapassados. Atualizou-se o 5G air simulator para representar a
implantação de femto-células de interior com os pressupostos propostos e distribuição espacial
uniforme. Para todas as combinações possĂveis do comprimento lado do apartamento, o
número máximo de utilizadores suportado ultrapassou o número de utilizadores suportado
(na literatura) em mais de duas vezes. Em ambientes de exterior, propuseram-se pico-células
no interior de macro-células, de forma a obter atraso extremo-a-extremo reduzido e taxa de
transmissĂŁo dados elevada, resultante do ganho de multiplexagem estatĂstica associado.
Apresentam-se resultados para as divisões funcionais seis e sete dos NR 5G, para 2.6 GHz,
3.5GHz e 5.62 GHz. Para raios das células curtos, a melhor solução será selecionar a banda
dos 2.6 GHz para alcançar PLR (do inglês, PLR) reduzido e suportar um maior número de
utilizadores, com débito binário útil e lucro mais elevados (para raios das células até 400 m).
Em 4G, com CA, da análise do equilĂbrio custos-proveitos com pico-cĂ©lulas, o escalonamento
multi-banda EMBS (do inglĂŞs, Enhanced Multi-band Scheduler) disponibiliza proveitos superiores
em comparação com o caso sem CA. Mostra-se claramente que lucro com CA é mais
de quatro vezes superior do que no cenário sem CA, o que significa que um aumento ligeiro
no custo com CA resulta num aumento de 4-vezes no lucro relativamente ao cenário sem CA
Spectrum Sharing, Latency, and Security in 5G Networks with Application to IoT and Smart Grid
The surge of mobile devices, such as smartphones, and tables, demands additional capacity. On the other hand, Internet-of-Things (IoT) and smart grid, which connects numerous sensors, devices, and machines require ubiquitous connectivity and data security. Additionally, some use cases, such as automated manufacturing process, automated transportation, and smart grid, require latency as low as 1 ms, and reliability as high as 99.99\%. To enhance throughput and support massive connectivity, sharing of the unlicensed spectrum (3.5 GHz, 5GHz, and mmWave) is a potential solution. On the other hand, to address the latency, drastic changes in the network architecture is required. The fifth generation (5G) cellular networks will embrace the spectrum sharing and network architecture modifications to address the throughput enhancement, massive connectivity, and low latency.
To utilize the unlicensed spectrum, we propose a fixed duty cycle based coexistence of LTE and WiFi, in which the duty cycle of LTE transmission can be adjusted based on the amount of data. In the second approach, a multi-arm bandit learning based coexistence of LTE and WiFi has been developed. The duty cycle of transmission and downlink power are adapted through the exploration and exploitation. This approach improves the aggregated capacity by 33\%, along with cell edge and energy efficiency enhancement. We also investigate the performance of LTE and ZigBee coexistence using smart grid as a scenario.
In case of low latency, we summarize the existing works into three domains in the context of 5G networks: core, radio and caching networks. Along with this, fundamental constraints for achieving low latency are identified followed by a general overview of exemplary 5G networks. Besides that, a loop-free, low latency and local-decision based routing protocol is derived in the context of smart grid. This approach ensures low latency and reliable data communication for stationary devices.
To address data security in wireless communication, we introduce a geo-location based data encryption, along with node authentication by k-nearest neighbor algorithm. In the second approach, node authentication by the support vector machine, along with public-private key management, is proposed. Both approaches ensure data security without increasing the packet overhead compared to the existing approaches
Enabling Technologies for Ultra-Reliable and Low Latency Communications: From PHY and MAC Layer Perspectives
© 1998-2012 IEEE. Future 5th generation networks are expected to enable three key services-enhanced mobile broadband, massive machine type communications and ultra-reliable and low latency communications (URLLC). As per the 3rd generation partnership project URLLC requirements, it is expected that the reliability of one transmission of a 32 byte packet will be at least 99.999% and the latency will be at most 1 ms. This unprecedented level of reliability and latency will yield various new applications, such as smart grids, industrial automation and intelligent transport systems. In this survey we present potential future URLLC applications, and summarize the corresponding reliability and latency requirements. We provide a comprehensive discussion on physical (PHY) and medium access control (MAC) layer techniques that enable URLLC, addressing both licensed and unlicensed bands. This paper evaluates the relevant PHY and MAC techniques for their ability to improve the reliability and reduce the latency. We identify that enabling long-term evolution to coexist in the unlicensed spectrum is also a potential enabler of URLLC in the unlicensed band, and provide numerical evaluations. Lastly, this paper discusses the potential future research directions and challenges in achieving the URLLC requirements
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