26 research outputs found
Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks
Soaring capacity and coverage demands dictate that future cellular networks
need to soon migrate towards ultra-dense networks. However, network
densification comes with a host of challenges that include compromised energy
efficiency, complex interference management, cumbersome mobility management,
burdensome signaling overheads and higher backhaul costs. Interestingly, most
of the problems, that beleaguer network densification, stem from legacy
networks' one common feature i.e., tight coupling between the control and data
planes regardless of their degree of heterogeneity and cell density.
Consequently, in wake of 5G, control and data planes separation architecture
(SARC) has recently been conceived as a promising paradigm that has potential
to address most of aforementioned challenges. In this article, we review
various proposals that have been presented in literature so far to enable SARC.
More specifically, we analyze how and to what degree various SARC proposals
address the four main challenges in network densification namely: energy
efficiency, system level capacity maximization, interference management and
mobility management. We then focus on two salient features of future cellular
networks that have not yet been adapted in legacy networks at wide scale and
thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and
device-to-device (D2D) communications. After providing necessary background on
CoMP and D2D, we analyze how SARC can particularly act as a major enabler for
CoMP and D2D in context of 5G. This article thus serves as both a tutorial as
well as an up to date survey on SARC, CoMP and D2D. Most importantly, the
article provides an extensive outlook of challenges and opportunities that lie
at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201
5G and beyond networks
This chapter investigates the Network Layer aspects that will characterize the merger of the cellular paradigm and the IoT architectures, in the context of the evolution towards 5G-and-beyond, including some promising emerging services as Unmanned Aerial Vehicles or Base Stations, and V2X communications
Cooperative Radio Communications for Green Smart Environments
The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin
Cooperative Radio Communications for Green Smart Environments
The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin
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Wireless indoor localisation within the 5G internet of radio light
This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonNumerous applications can be enhanced by accurate and efficient indoor localisation using wireless
sensor networks, however trade-offs often exist between these two parameters. In this thesis, realworld
and simulation data is used to examine the hybrid millimeter wave and Visible Light
Communications (VLC) architecture of the 5G Internet of Radio Light (IoRL) Horizon 2020 project.
Consequently, relevant localisation challenges within Visible Light Positioning (VLP) and asynchronous
sampling networks are identified, and more accurate and efficient solutions are developed.
Currently, VLP relies strongly on the assumed Lambertian properties of light sources.
However, in practice, not all lights are Lambertian. To support the widespread deployment of VLC
technology in numerous environments, measurements from non-Lambertian sources are analysed to
provide new insights into the limitations of existing VLP techniques. Subsequently, a novel VLP
calibration technique is proposed, and results indicate a 59% accuracy improvement against existing
methods. This solution enables high accuracy centimetre level VLP to be achieved with non-
Lambertian sources.
Asynchronous sampling of range-based measurements is known to impact localisation
performance negatively. Various Asynchronous Sampling Localisation Techniques (ASLT) exist to
mitigate these effects. While effective at improving positioning performance, the exact suitability of
such solutions is not evident due to their additional processes, subsequent complexity, and increased
costs. As such, extensive simulations are conducted to study the effectiveness of ASLT under variable
sampling latencies, sensor measurement noise, and target trajectories. Findings highlight the
computational demand of existing ASLT and motivate the development of a novel solution. The
proposed Kalman Extrapolated Least Squares (KELS) method achieves optimal localisation
performance with a significant energy reduction of over 50% when compared to current leading ASLT.
The work in this thesis demonstrates both the capability for high performance VLP from non-
Lambertian sources as well as the potential for energy efficient localisation for sequentially sampled
range measurements.Horizon 202
Digital Processing for an Analogue Subcarrier Multiplexed Mobile Fronthaul
In order to meet the demands of the fifth generation of mobile communication networks (5G), such as very high bit-rates, very low latency and massive machine connectivity, there is a need for a flexible, dynamic, scalable and versatile mobile fronthaul. Current industry fronthaul standards employing sampled radio waveforms for digital transport suffer from spectral inefficiency, making this type of transport impractical for the wide channel bandwidths and multi-antenna systems required by 5G. On the other hand, analogue transport does not suffer from these limitations. It is, however, prone to noise, non-linearity and poor dynamic range. When combined with analogue domain signal aggregation/multiplexing, it also lacks flexibility and scalability, especially at millimetre wave frequencies.
Measurements (matched in simulation) of analogue transport at millimetre wave frequencies demonstrate some of these issues. High data rates are demonstrated employing wide bandwidth channels combined using traditional subcarrier multiplexing techniques. However, only a limited number of channels can be multiplexed in this manner, with poor spectral efficiency, as analogue filter limitations do not allow narrow gaps between channels.
To this end, over the last few years, there has been significant investigation of analogue transport schemes combined with digital channel aggregation/ de-aggregation (combining/ separating multiple radio waveforms in the digital domain). This work explores such a technique.
Digital processing is used at the transmitter to flexibly multiplex a large number of channels in a subcarrier multiplex, without the use of combiners, mixers/ up-converters or Hilbert transforms. Orthogonal Frequency Division Multiplexing (OFDM) - derived Discrete Multi-Tone (DMT) and Single Sideband (SSB) modulated channels are integrated within a single Inverse Fast Fourier Transform (IFFT) operation. Channels or channel groups are mapped systematically into Nyquist zones by using, for example, a single IFFT (for a single 5G mobile numerology) or multiple IFFTs (for multiple 5G mobile numerologies).
The analogue transport signal generated in this manner is digitally filtered and band-pass sampled at the receiver such that each corresponding channel (e.g. channels destined to the same radio frequency (RF)/ millimetre wave (mmW) frequency) in the multiplex is presented at the same intermediate frequency, due to the mapping employed at the transmitter. Analogue or digital domain mixers/ down-converters are not required with this technique. Furthermore, each corresponding channel can be readily up-converted to their respective RF/mmW channels with minimal per-signal processing. Measurement results, matched in simulation, for large signal multiplexes with both generic and 5G mobile numerologies show error-vector magnitude performance well within specifications, validating the proposed system.
For even larger multiplexes and/or multiplexes residing on a higher IF exceeding the analogue bandwidth and sampling rate specifications of the ADCs at the receiver, the use of a bandwidth-extension device is proposed to extend the mapping to a mapping hierarchy and relax the analogue bandwidth and sampling rate requirements of the ADCs. This allows the receiver to still use digital processing, with only minimal analogue processing, to band-pass sample smaller blocks of channels from the larger multiplex, down to the same intermediate frequency. This ensures that each block of channels is within the analogue bandwidth specification of the ADCs. Performance predictions via simulation (based on a system model matched to the measurements) show promising results for very large multiplexes and large channel bandwidths.
The multiplexing technique presented in this work thus allows reductions in per-channel processing for heterogeneous networking (or multi-radio access technologies) and multi-antenna configurations. It also creates a re-configurable and adaptable system based on available processing resources, irrespective of changes to the number of channels and channel groups, channel bandwidths and modulation formats
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