Gotowa bibliografia na temat „5G Cellular systems”

Universal filtered multi-carrier (UFMC) is a potential multi-carrier system for future cellular networks. UFMC provides low latency, frequency offset robustness, and reduced out-of-band (OOB) emission that results in better spectral efficiency. However, UFMC suffers from the problem of high peak-to-average power ratio (PAPR), which might impact the function of high power amplifiers causing a nonlinear distortion. We propose a comparative probabilistic PAPR reduction technique, called the decomposed selective mapping approach, to alleviate PAPR in UFMC systems. The concept of this proposal depends on decomposing the complex symbol into real and imaginary parts, and then converting each part to a number of different phase vectors prior to the inverse fast Fourier transform (IFFT) operation. The IFFT copy, which introduces the lowest PAPR, is considered for transmission. Results obtained using theoretical analysis and simulations show that the proposed approach can significantly enhance the performance of the UFMC system in terms of PAPR reduction. Besides, it maintains the OOB emission with candidate bit error rate and error vector magnitude performances.

Unmanned aerial vehicles (UAVs) have sparked a lot of interest in the wireless networking community as an emerging subject in aerial robotics. The UAV environment can be used to improve UAV communications in various ways. These smart devices cater for a broad variety of wireless technologies and applications because of UAV's inherent features related to versatile mobility in 3D space, autonomous operations as well as intelligent positioning. This study will investigate the convergence synergies between 5G/B5G mobile systems and UAV technologies, with the UAV being integrated into current cellular networks as a modern aerial user equipment (UE). In this integration, UAVs play the function of cellular flying customers, and are hence referred to as cellularly linked UAVs (a.k.a. UAVUE, drone-UE, 5G-connected drone, or aerial user). The major goal of this research is to provide a thorough analysis of the integration task, as well as major technical breakthroughs from 5G/B5G and current work in prototyping architecture and field trials that support cell-based UAVs. This study examines recent 3GPP standards advances as well as socio-economic challenges that must be addressed before this promising technology can be properly implemented. There are already some accessible issues clearing the way for potential study opportunities.

Internet of Things (IoT) is a key business driver for the upcoming fifth-generation (5G) mobile networks, which in turn will enable numerous innovative IoT applications such as smart city, mobile health, and other massive IoT use cases being defined in 5G standards. To truly unlock the hidden value of such mission-critical IoT applications in a large scale in the 5G era, advanced self-protection capabilities are entailed in 5G-based Narrowband IoT (NB-IoT) networks to efficiently fight off cyber-attacks such as widespread Distributed Denial of Service (DDoS) attacks. However, insufficient research has been conducted in this crucial area, in particular, few if any solutions are capable of dealing with the multiple encapsulated 5G traffic for IoT security management. This paper proposes and prototypes a new security framework to achieve the highly desirable self-organizing networking capabilities to secure virtualized, multitenant 5G-based IoT traffic through an autonomic control loop featured with efficient 5G-aware traffic filtering. Empirical results have validated the design and implementation and demonstrated the efficiency of the proposed system, which is capable of processing thousands of 5G-aware traffic filtering rules and thus enables timely protection against large-scale attacks.

In recent years, 5G (Fifth Generation) and 6G (Sixth Generation) wireless networks have attracted extensive research interest. According to the 3GPP (3rd Generation Partnership Project) project, 5G networks should be support three main application scenarios: enhanced Mobile Broadband (eMBB), Massive Machine-Type Communications, (mMTC), Ultra-Reliable Low Latency Communication (URLLC). In addition to that, enhanced vehicle-to-everything, (eV2X) are also considered as key technology in 5G. All these scenarios require ubiquitous connectivity providing high data rates and spectral efficiency. These issues lead to many challenges for introducing 5G and 6G networks. Traditional modulation and multiple access schemes will not achieve the requirements of 5G and 6G networks. In order to meet these upcoming requirements, it is necessary to explore novel modulation and multiple access schemes. Data rate, resistance to noise and capacity of wireless network depend on choosing current modulation scheme. To meet the requirements of 5G and 6G and reduce the out-of-band (OOB) leakage various modulation schemes based on subband filtering, pulse shaping and precoding have been proposed. This article provides an overview of the different modulation schemes for 5G and 6G systems.

In recent years, wireless technology in China has been further improved. Wireless system designers have also begun research on 5G wireless communication systems and obtained good research results. The application of the 5G cellular structure can effectively solve the problems existing in the current wireless technology application, thereby promoting the further improvement of the wireless technology level. This paper mainly discusses the cellular technology and the key technologies of 5G wireless communication network.

5G is the latest generation of mobile cellular technology, which is designed to significantly increase Internet speed, coverage and reduce the data packet transfer time in wireless networks. 5G brings together all latest and most advanced developments of mankind in terms of communications and IT. This is the limit of existing technologies of microelectronics and data radio transmission. The new generation of 5G mobile communication has a number of fundamental advantages compared to 4G: higher data transfer rate; low signal delay; the ability to connect more devices; high energy efficiency; multiply increased throughput; high user mobility. Another important difference of 5G deserves attention – large-scale virtualization. The new technology goes beyond just hardware solutions. Many functions in it are implemented not at the level of physical infrastructure, but in a software way. This article covers the topic of applicability of GNSS and 5G mobile communications. The material of article will tell you why GNSS and 5G are interesting and how User Equipment developers can start shaping the 5G device market today.

Advanced spectrum sharing and resource management techniques are needed in future wireless cellular networks to ensure high data rates to the end users. New system architec- tures will be required, taking into account aspects such as like spectrum resources availabil- ity, deployment and operational costs, as well as power consumption. Thus, it becomes key for the development of the fifth generation of cellular networks (5G) to pursue an efficient exploitation of the wireless medium, in the sense of both using advanced physical (PHY) layer techniques, and also seeking coordination among operators. In this thesis, we analyze the problem of spectrum management within the next generation of cellular networks and we propose new algorithms for spectrum sharing and for interference coordination. In the first part of the thesis, we focus on the spectrum sharing between operators. Firstly, we develop a Long Term Evolution (LTE) standard compliant simulation environ- ment extending the open-source network simulator ns3 to support multi-input multi-output (MIMO) systems and advanced beamforming systems. Then, we present a mathematical analysis for the network performance of non-orthogonal spectrum sharing, connecting it directly with the statistics of the radio channel and we develop some spectrum sharing al- gorithms considering different aspects of the operators coexistence. The analysis is further extended to the performance evaluation of more complex digital beamforming techniques developed in a multi-input-single-output (MISO) system allowing to reach a Pareto equi- librium between the operators. Finally, we consider also an orthogonal spectrum sharing scenario investigating the impact of asymmetries and dynamics of the user demands on the implementation of spectrum sharing techniques. In the second part of the thesis, we extend the concept of spectrum management to two different scenarios. In the first scenario, we consider coordination between multiple cells, e.g. coordinated multipoint (CoMP). In particular, thanks to the exploitation of digital beamforming techniques, we present a novel distributed clustering algorithm that adapts the cluster configuration according to the users distribution and the average cluster size. In the second scenario, we extend the concept of spectrum sharing to the coexistence between different communications system in order to study the feasibility of the deployment of the cellular systems within the mmWave spectrum. In particular, we analyze the impact of the novel cellular networks on the fixed satellite system (FSS). In the last part of the thesis, we focus on the mobility management of the users in a het- erogeneous network. Firstly, we focus on the average performance experienced by a mobile user while crossing a pico/femtocell, as a function of the handover parameters to provide an approximate expression of the average Shannon capacity experienced by a mobile user when crossing the femtocell. Then, we propose a Markov-based framework to model the user state during the handover process and, based on such a model, we derive an optimal context-dependent handover criterion.
I futuri sistemi di comunicazione cellulare dovranno affrontare nei prossimi anni un rapido aumento della domanda di traffico dati mobile rendendo necessario l’utilizzo di avanzate tecniche di condivisione dello spettro e gestione delle risorse. Sara` quindi fonda- mentale lo sviluppo di nuove tecnologie che dovranno considerare aspetti quali la disponi- bilita` di risorse spettrali, i costi di realizzazione ed il consumo di energia. La chiave per lo sviluppo della quinta generazione di sistemi cellulari (5G), sara` quindi la ricerca di un uso piu` efficiente delle risorse wireless, sfruttando nello stesso tempo le piu` avanzate tecniche a livello fisico e la coordinazione tra gli operatori. In questa tesi, vengono analizzati i problemi relativi alla gestione delle risorse spettrali nelle reti cellulari di nuova generazione propo- nendo nuovi algoritmi per la condivisione dello spettro e la gestione delle interferenze. Nella prima parte di questa tesi vengono analizzate tematiche relative alla condivisione dello spettro tra operatori. In primo luogo e` stata implementata un’estensione del simulatore di rete ns3, basata sullo standard Long Term Evolution (LTE) al fine di supportare l’analisi di sistemi multi antenna (MIMO) e di avanzate tecniche di beamforming. E` stata quindi effettuata un’analisi matematica delle performance ottenibili dalla condivisione di spettro non ortogonale connessa direttamente al comportamento statistico del canale radio. Sono stati quindi sviluppati alcuni algoritmi di condivisione dello spettro considerando diversi aspetti della coesistenza tra operatori. L’analisi e` stata quindi estesa alla valutazione di tec- niche di beamforming digitale sviluppate in uno scenario multi-input-single-output (MISO) e atte a realizzare un equilibrio di Pareto tra gli operatori. Al termine di questa sezione sono inoltre stati analizzati alcuni scenari di condivisione ortogonale delle risorse, al fine di studi- are l’impatto delle dinamiche degli utenti sulla implementazione delle tecniche di gestione delle risorse spettrali. Nella seconda parte di questa tesi il concetto di gestione delle risorse e` stato esteso a due ulteriori scenari. Nel primo scenario, si e` considerata la coordinazione tra celle diverse (CoMP). Nello specifico, grazie all’uso di tecniche di beamforming digitale, e` stato ideato un nuovo algoritmo di clustering delle celle capace di adattare la configurazione dei clusters in relazione alla distribuzione degli utenti e alla dimensione dei cluster stessi. Nel secondo scenario, il concetto di condivisione di spettro e` stato esteso alla coesistenza tra diversi sis- temi di comunicazione, al fine di fornire uno studio di fattibilita` sullo sviluppo dei sistemi cellulari all’interno dello spettro delle onde millimetriche. In particolare, e` stato analizzato l’impatto delle nuove reti cellulari su sistemi satellitari fissi (FSS). Nell’ultima parte delle tesi vengono invece trattati aspetti riguardanti la gestione della mobilita` degli utenti all’interno delle reti eterogenee. Inizialmente, sono state analizzate le performance ottenute da un utente mobile nell’attraversare una pico/femto cella in funzione dei parametri di handover, al fine di fornire un espressione della capacita` di Shannon media dell’utente. E’ stato quindi proposto un modello basato su una catena dI Markov atto a studiare lo stato dell’utente durante il processo di handover e, sfruttando tale modello, e` stato derivato un criterio di handover ottimale basato sulle condizioni del contesto.

From the first generation, 1G, to the fourth generation, 4G, the development and technological advancements in telecommunications network systems have been remarkable. Faster and better connections have opened up for new markets, ideas and possibilities, to that extent that there now is a demand that surpasses the supply. Despite all these advancements made in the mobile communications field most of the concept of how the technology works and its infrastructure has remained the same. This however, is about to change with the introduction of the fifth generation (5G) mobile communication. With the introduction of 5G much of the technology introduced will be different from that of previous generations. This change extends to include the entire infrastructure of the mobile communications system. With these major changes, many of the tools available today for telecommunications network evaluation do not really suffice to include the 5G network standard. For this reason, there is a need to develop a new kind of tool that will be able to include the changes brought by this new network standard. In this thesis a simulation framework adapted for the next generation telecommunication standard 5G is set to be developed. This framework should include many of the characteristics that set 5G aside from previous generations.

Mobile traffic forecasting is a relatively new research area, which is becoming of fundamental importance for next-generation networks. Proactively knowing the user demand allows the system to allocate resources and apply energy-saving decisions properly. Classical models are limited by the stationary assumption of time sequences and fail to take correlations into account. This work presents results on cellular network traffic analysis and prediction, providing a novel, robust, and precise machine learning model to efficiently and dynamically manage network resources in 5G systems.

Future fifth generation (5G) cellular networks have to cope with the expected ten-fold increase in mobile data traffic between 2015 and 2021. To achieve this goal, new technologies are being considered, including massive multiple-input multiple-output (MIMO) systems and millimeter-wave (mmWave) communications. Massive MIMO involves the use of large antenna array sizes at the base station, while mmWave communications employ frequencies between 30 and 300 GHz. In this thesis we study the impact of these technologies on the performance of channel estimators. Our results show that the characteristics of the propagation channel at mmWave frequencies improve the channel estimation performance in comparison with current, low frequency-based, cellular networks. Furthermore, we demonstrate the existence of an optimal angular spread of the multipath clusters, which can be used to maximize the capacity of mmWave networks. We also propose efficient noise variance estimators, which can be employed as an input to existing channel estimators.

En la actualidad, la Internet de las Cosas (Internet of Things, IoT) es una tecnología esencial para la próxima generación de sistemas inalámbricos. La conectividad es la base de IoT, y el tipo de acceso requerido dependerá de la naturaleza de la aplicación. Uno de los principales facilitadores del entorno IoT es la comunicación machine-to-machine (M2M) y, en particular, su enorme potencial para ofrecer conectividad ubicua entre dispositivos inteligentes. Las redes celulares son la elección natural para las aplicaciones emergentes de IoT y M2M. Un desafío importante en las redes celulares es conseguir que la red sea capaz de manejar escenarios de acceso masivo en los que numerosos dispositivos utilizan comunicaciones M2M. Por otro lado, los sistemas celulares han experimentado un tremendo desarrollo en las últimas décadas: incorporan tecnología sofisticada y nuevos algoritmos para ofrecer una amplia gama de servicios. El modelado y análisis del rendimiento de estas redes multiservicio es también una tarea desafiante que podría requerir un gran esfuerzo computacional. Para abordar los desafíos anteriores, nos centramos en primer lugar en el diseño y la evaluación de las prestaciones de nuevos mecanismos de control de acceso para hacer frente a las comunicaciones masivas M2M en redes celulares. Posteriormente nos ocupamos de la evaluación de prestaciones de redes multiservicio y proponemos una nueva técnica analítica que ofrece precisión y eficiencia computacional. Nuestro principal objetivo es proporcionar soluciones para aliviar la congestión en la red de acceso radio cuando un gran número de dispositivos M2M intentan conectarse a la red. Consideramos los siguientes tipos de escenarios: (i) los dispositivos M2M se conectan directamente a las estaciones base celulares, y (ii) forman grupos y los datos se envían a concentradores de tráfico (gateways) que les proporcionan acceso a la infraestructura. En el primer escenario, dado que el número de dispositivos añadidos a la red aumenta continuamente, esta debería ser capaz de manejar el considerable incremento en las solicitudes de acceso. El 3rd Generation Partnership Project (3GPP) ha propuesto el access class barring (ACB) como una solución práctica para el control de congestión en la red de acceso radio y la red troncal. El ajuste correcto de los parámetros de ACB de acuerdo con la intensidad del tráfico es crítico, pero cómo hacerlo de forma dinámica y autónoma es un problema complejo cuya solución no está recogida en las especificaciones del 3GPP. Esta tesis doctoral contribuye al análisis del rendimiento y al diseño de nuevos algoritmos que implementen efectivamente este mecanismo, y así superar los desafíos introducidos por las comunicaciones masivas M2M. En el segundo escenario, dado que la heterogeneidad de los dispositivos IoT y las arquitecturas celulares basadas en hardware imponen desafíos aún mayores para permitir una comunicación flexible y eficiente en los sistemas inalámbricos 5G, esta tesis doctoral también contribuye al diseño de software-defined gateways (SD-GWs) en una nueva arquitectura propuesta para redes inalámbricas definidas por software que se denomina SoftAir. Esto permite manejar tanto un gran número de dispositivos como el volumen de datos que estarán vertiendo en la red. Otra contribución de esta tesis doctoral es la propuesta de una técnica novedosa para el análisis de prestaciones de redes multiservicio de alta capacidad que se basa en un nuevo enfoque del modelizado analítico de sistemas que operan a diferentes escalas temporales. Este enfoque utiliza el análisis del transitorio de una serie de subcadenas absorbentes y lo denominamos absorbing Markov chain approximation (AMCA). Nuestros resultados muestran que para un coste computacional dado, AMCA calcula los parámetros de prestaciones habituales de un sistema con mayor precisión, en comparación con los resultados obtenidos por otr
Nowadays, Internet of Things (IoT) is an essential technology for the upcoming generation of wireless systems. Connectivity is the foundation for IoT, and the type of access required will depend on the nature of the application. One of the leading facilitators of the IoT environment is machine-to-machine (M2M) communication, and particularly, its tremendous potential to offer ubiquitous connectivity among intelligent devices. Cellular networks are the natural choice for emerging IoT and M2M applications. A major challenge in cellular networks is to make the network capable of handling massive access scenarios in which myriad devices deploy M2M communications. On the other hand, cellular systems have seen a tremendous development in recent decades; they incorporate sophisticated technology and algorithms to offer a broad range of services. The modeling and performance analysis of these large multi-service networks is also a challenging task that might require high computational effort. To address the above challenges, we first concentrate on the design and performance evaluation of novel access control schemes to deal with massive M2M communications. Then, we focus on the performance evaluation of large multi-service networks and propose a novel analytical technique that features accuracy and computational efficiency. Our main objective is to provide solutions to ease the congestion in the radio access or core network when massive M2M devices try to connect to the network. We consider the following two types of scenarios: (i) massive M2M devices connect directly to cellular base stations, and (ii) they form clusters and the data is forwarded to gateways that provide them with access to the infrastructure. In the first scenario, as the number of devices added to the network is constantly increasing, the network should handle the considerable increment in access requests. Access class barring (ACB) is proposed by the 3rd Generation Partnership Project (3GPP) as a practical congestion control solution in the radio access and core network. The proper tuning of the ACB parameters according to the traffic intensity is critical, but how to do so dynamically and autonomously is a challenging task that has not been specified. Thus, this dissertation contributes to the performance analysis and optimal design of novel algorithms to implement effectively this barring scheme and overcome the challenges introduced by massive M2M communications. In the second scenario, since the heterogeneity of IoT devices and the hardware-based cellular architectures impose even greater challenges to enable flexible and efficient communication in 5G wireless systems, this dissertation also contributes to the design of software-defined gateways (SD-GWs) in a new architecture proposed for wireless software-defined networks called SoftAir. The deployment of these SD-GWs represents an alternative solution aiming at handling both a vast number of devices and the volume of data they will be pouring into the network. Another contribution of this dissertation is to propose a novel technique for the performance analysis of large multi-service networks. The underlying complexity of the network, particularly concerning its size and the ample range of configuration options, makes the solution of the analytical models computationally costly. However, a typical characteristic of these networks is that they support multiple types of traffic flows operating at different time-scales. This time-scale separation can be exploited to reduce considerably the computational cost associated to determine the key performance indicators. Thus, we propose a novel analytical modeling approach based on the transient regime analysis, that we name absorbing Markov chain approximation (AMCA). For a given computational cost, AMCA finds common performance indicators with greater accuracy, when compared to the results obtained by other approximate methods proposed in the literature.
En l'actualitat, la Internet de les Coses (Internet of Things, IoT) és una tecnologia essencial per a la propera generació de sistemes sense fil. La connectivitat és la base d'IoT, i el tipus d'accés requerit dependrà de la naturalesa de l'aplicació. Un dels principals facilitadors de l'entorn IoT és la comunicació machine-to-machine (M2M) i, en particular, el seu enorme potencial per oferir connectivitat ubiqua entre dispositius intel · ligents. Les xarxes mòbils són l'elecció natural per a les aplicacions emergents de IoT i M2M. Un desafiament important en les xarxes mòbils que actualment está rebent molta atenció és aconseguir que la xarxa siga capaç de gestionar escenaris d'accés massiu en què una gran quantitat de dispositius utilitzen comunicacions M2M. D'altra banda, els sistemes mòbils han experimentat un gran desenvolupament en les últimes dècades: incorporen tecnologia sofisticada i nous algoritmes per oferir una àmplia gamma de serveis. El modelatge i análisi del rendiment d'aquestes xarxes multiservei és també un desafiament important que podria requerir un gran esforç computacional. Per abordar els desafiaments anteriors, en aquesta tesi doctoral ens centrem en primer lloc en el disseny i l'avaluació de les prestacions de nous mecanismes de control d'accés per fer front a les comunicacions massives M2M en xarxes cel · lulars. Posteriorment ens ocupem de l'avaluació de prestacions de xarxes multiservei i proposem una nova tècnica analítica que ofereix precisió i eficiència computacional. El nostre principal objectiu és proporcionar solucions per a alleujar la congestió a la xarxa d'accés ràdio quan un gran nombre de dispositius M2M intenten connectar-se a la xarxa. Considerem els dos tipus d'escenaris següents: (i) els dispositius M2M es connecten directament a les estacions base cel · lulars, i (ii) formen grups i les dades s'envien a concentradors de trànsit (gateways) que els proporcionen accés a la infraestructura. En el primer escenari, atès que el nombre de dispositius afegits a la xarxa augmenta contínuament, aquesta hauria de ser capaç de gestionar el considerable increment en les sol · licituds d'accés. El 3rd Generation Partnership Project (3GPP) ha proposat l'access class barring (ACB) com una solució pràctica per al control de congestió a la xarxa d'accès ràdio i la xarxa troncal. L'ajust correcte dels paràmetres d'ACB d'acord amb la intensitat del trànsit és crític, però com fer-ho de forma dinàmica i autònoma és un problema complex, la solució del qual no està recollida en les especificacions del 3GPP. Aquesta tesi doctoral contribueix a l'anàlisi del rendiment i al disseny de nous algoritmes que implementen efectivament aquest mecanisme, i així superar els desafiaments introduïts per les comunicacions massives M2M en les xarxes mòbils actuals i futures. En el segon escenari, atès que l'heterogeneïtat dels dispositius IoT i les arquitectures cel · lulars basades en hardware imposen desafiaments encara més grans per permetre una comunicació flexible i eficient en els sistemes sense fil 5G, aquesta tesi doctoral també contribueix al disseny de software-defined gateways (SD-GWS) en una nova arquitectura proposada per a xarxes sense fils definides per programari que s'anomena SoftAir. Això permet gestionar tant un gran nombre de dispositius com el volum de dades que estaran abocant a la xarxa. Una altra contribució d'aquesta tesi doctoral és la proposta d'una tècnica innovadora per a l'anàlisi de prestacions de xarxes multiservei d'alta capacitat que es basa en un nou enfocament del modelitzat analític de sistemes que operen a diferents escales temporals. Aquest enfocament utilitza l'anàlisi del transitori d'una sèrie de subcadenes absorbents i l'anomenem absorbing Markov chain Approximation (AMCA). Els nostres resultats mostren que per a un cost computacional donat, AMCA calcula els paràmetres de prestacions habituals d
Tello Oquendo, LP. (2018). Design and Performance Analysis of Access Control Mechanisms for Massive Machine-to-Machine Communications in Wireless Cellular Networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/107946
TESIS

Nei prossimi anni è previsto un aumento del traffico dati, e la quinta generazione cellulare 5G dovrà fare affidamento su nuove tecnologie, come le onde millimetriche e il massive-MIMO, per soddisfare tale richiesta. Lo spettro di frequenze sotto i 6 GHz risulta infatti sovra-utilizzato, e le frequenze relative alle onde millimetriche promettono di garantire alte velocità di trasmissione dei dati, grazie alla grande disponibilità di banda, specialmente attorno ai 60 GHz. Nonostante questo aspetto favorevole, si ha però un elevato path loss e la difficoltà nel penetrare gli ostacoli. Per ovviare a tali problemi, l'utilizzo di tecniche di beamforming, ottenibili grazie all'uso congiunto di frequenze a onde millimetriche e massive-MIMO, permette di direzionare il pattern dell'antenna nelle direzioni spaziali desiderate, e di compensare il path loss grazie all'aumento della direttività. Considerando un sistema cellulare 5G, una comunicazione di tipo direttivo impone che i beam dell'utente e della stazione radio base debbano essere allineati per garantire la comunicazione, introducendo possibili ritardi nella fase di accesso iniziale. Di conseguenza, lo studio di algoritmi ad-hoc, progettati per velocizzare questa fase rappresenta un sfida importante per l'ottimizzazione dei futuri sistemi 5G. Nell'ottica quindi di velocizzare l'accesso iniziale nelle reti 5G, in questa tesi prima di tutto mostriamo gli approcci proposti nello stato dell'arte, mettendo in evidenza gli aspetti che possono essere migliorati. Successivamente viene spiegato il simulatore che abbiamo implementato su Matlab, e infine viene introdotto un nuovo algoritmo. In particolare, l'algoritmo proposto si basa sulla memoria degli utenti visti per settore e sull'utilizzo di diverse configurazioni dei beam. Questi due aspetti combinati tra loro risultano innovativi rispetto allo stato dell'arte. I risultati numerici ottenuti dimostrano la bontà della tecnica proposta negli scenari 5G considerati.

Předkládaná disertační práce je zaměřena na "heterogenní propojení mobilních zařízení v bezdrátových systémech 5. generace". Navzdory nepochybnému pokroku v rámci navržených komunikačních řešení postrádají mobilní sítě nastupující generace dostatečnou šířku pásma a to hlavně kvůli neefektivnímu využívání rádiového spektra. Tato situace tedy v současné době představuje řadu otázek v oblasti výzkumu. Hlavním cílem této disertační práce je proto návrh nových komunikačních mechanismů pro komunikaci mezi zařízeními v bezprostřední blízkosti s asistencí mobilní sítě a dále pak návrh a implementace algoritmů pro dynamické přidělování frekvenčního spektra v nastupujících mobilních sítích 5G. Navrhnuté komunikační mechanismy a algoritmy jsou následně komplexně vyhodnoceny pomocí nově vyvinutých simulačních nástrojů (kalibrovaných s využitím 3GPP trénovacích dat) a zejména pak v experimentální mobilní síti LTE-A, která se nachází v prostorách Vysokého učení technického v Brně, Česká Republika. Získané praktické výsledky, které jsou podpořeny zcela novou matematickou analýzou ve speciálně navržených charakteristických scénářích, představují řešení pro vlastníka spektra v případě požadavků na jeho dynamické sdílení. Tato metoda tedy představuje možnost pro efektivnější využití spektra v rámci mobilních sítí 5G bez degradace kvality služeb (QoS) a kvality zážitků (QoE) pro koncové uživatele. Vědecký přínos dosažených výsledků dokazuje fakt, že některé z principů představených v této disertační práci byly zahrnuty do celosvětově uznávaného standardu (specifikace) 3GPP Release 12.

La quinta generación de redes móviles (5G) se encuentra a la vuelta de la esquina. Se espera provea de beneficios extraordinarios a la población y que resuelva la mayoría de los problemas de las redes 4G actuales. El éxito de 5G, cuya primera fase de estandarización ha sido completada, depende de tres pilares: comunicaciones tipo-máquina masivas, banda ancha móvil mejorada y comunicaciones ultra fiables y de baja latencia (mMTC, eMBB y URLLC, respectivamente). En esta tesis nos enfocamos en el primer pilar de 5G, mMTC, pero también proveemos una solución para lograr eMBB en escenarios de distribución masiva de contenidos. Específicamente, las principales contribuciones son en las áreas de: 1) soporte eficiente de mMTC en redes celulares; 2) acceso aleatorio para el reporte de eventos en redes inalámbricas de sensores (WSNs); y 3) cooperación para la distribución masiva de contenidos en redes celulares. En el apartado de mMTC en redes celulares, esta tesis provee un análisis profundo del desempeño del procedimiento de acceso aleatorio, que es la forma mediante la cual los dispositivos móviles acceden a la red. Estos análisis fueron inicialmente llevados a cabo por simulaciones y, posteriormente, por medio de un modelo analítico. Ambos modelos fueron desarrollados específicamente para este propósito e incluyen uno de los esquemas de control de acceso más prometedores: access class barring (ACB). Nuestro modelo es uno de los más precisos que se pueden encontrar en la literatura y el único que incorpora el esquema de ACB. Los resultados obtenidos por medio de este modelo y por simulación son claros: los accesos altamente sincronizados que ocurren en aplicaciones de mMTC pueden causar congestión severa en el canal de acceso. Por otro lado, también son claros en que esta congestión se puede prevenir con una adecuada configuración del ACB. Sin embargo, los parámetros de configuración del ACB deben ser continuamente adaptados a la intensidad de accesos para poder obtener un desempeño óptimo. En la tesis se propone una solución práctica a este problema en la forma de un esquema de configuración automática para el ACB; lo llamamos ACBC. Los resultados muestran que nuestro esquema puede lograr un desempeño muy cercano al óptimo sin importar la intensidad de los accesos. Asimismo, puede ser directamente implementado en redes celulares para soportar el tráfico mMTC, ya que ha sido diseñado teniendo en cuenta los estándares del 3GPP. Además de los análisis descritos anteriormente para redes celulares, se realiza un análisis general para aplicaciones de contadores inteligentes. Es decir, estudiamos un escenario de mMTC desde la perspectiva de las WSNs. Específicamente, desarrollamos un modelo híbrido para el análisis de desempeño y la optimización de protocolos de WSNs de acceso aleatorio y basados en cluster. Los resultados muestran la utilidad de escuchar el medio inalámbrico para minimizar el número de transmisiones y también de modificar las probabilidades de transmisión después de una colisión. En lo que respecta a eMBB, nos enfocamos en un escenario de distribución masiva de contenidos, en el que un mismo contenido es enviado de forma simultánea a un gran número de usuarios móviles. Este escenario es problemático, ya que las estaciones base de la red celular no cuentan con mecanismos eficientes de multicast o broadcast. Por lo tanto, la solución que se adopta comúnmente es la de replicar e contenido para cada uno de los usuarios que lo soliciten; está claro que esto es altamente ineficiente. Para resolver este problema, proponemos el uso de esquemas de network coding y de arquitecturas cooperativas llamadas nubes móviles. En concreto, desarrollamos un protocolo para la distribución masiva de contenidos, junto con un modelo analítico para su optimización. Los resultados demuestran que el modelo propuesto es simple y preciso, y que el protocolo puede reducir el con
La cinquena generació de xarxes mòbils (5G) es troba molt a la vora. S'espera que proveïsca de beneficis extraordinaris a la població i que resolga la majoria dels problemes de les xarxes 4G actuals. L'èxit de 5G, per a la qual ja ha sigut completada la primera fase del qual d'estandardització, depén de tres pilars: comunicacions tipus-màquina massives, banda ampla mòbil millorada, i comunicacions ultra fiables i de baixa latència (mMTC, eMBB i URLLC, respectivament, per les seues sigles en anglés). En aquesta tesi ens enfoquem en el primer pilar de 5G, mMTC, però també proveïm una solució per a aconseguir eMBB en escenaris de distribució massiva de continguts. Específicament, les principals contribucions són en les àrees de: 1) suport eficient de mMTC en xarxes cel·lulars; 2) accés aleatori per al report d'esdeveniments en xarxes sense fils de sensors (WSNs); i 3) cooperació per a la distribució massiva de continguts en xarxes cel·lulars. En l'apartat de mMTC en xarxes cel·lulars, aquesta tesi realitza una anàlisi profunda de l'acompliment del procediment d'accés aleatori, que és la forma mitjançant la qual els dispositius mòbils accedeixen a la xarxa. Aquestes anàlisis van ser inicialment dutes per mitjà de simulacions i, posteriorment, per mitjà d'un model analític. Els models van ser desenvolupats específicament per a aquest propòsit i inclouen un dels esquemes de control d'accés més prometedors: el access class barring (ACB). El nostre model és un dels més precisos que es poden trobar i l'únic que incorpora l'esquema d'ACB. Els resultats obtinguts per mitjà d'aquest model i per simulació són clars: els accessos altament sincronitzats que ocorren en aplicacions de mMTC poden causar congestió severa en el canal d'accés. D'altra banda, també són clars en què aquesta congestió es pot previndre amb una adequada configuració de l'ACB. No obstant això, els paràmetres de configuració de l'ACB han de ser contínuament adaptats a la intensitat d'accessos per a poder obtindre unes prestacions òptimes. En la tesi es proposa una solució pràctica a aquest problema en la forma d'un esquema de configuració automàtica per a l'ACB; l'anomenem ACBC. Els resultats mostren que el nostre esquema pot aconseguir un acompliment molt proper a l'òptim sense importar la intensitat dels accessos. Així mateix, pot ser directament implementat en xarxes cel·lulars per a suportar el trànsit mMTC, ja que ha sigut dissenyat tenint en compte els estàndards del 3GPP. A més de les anàlisis descrites anteriorment per a xarxes cel·lulars, es realitza una anàlisi general per a aplicacions de comptadors intel·ligents. És a dir, estudiem un escenari de mMTC des de la perspectiva de les WSNs. Específicament, desenvolupem un model híbrid per a l'anàlisi de prestacions i l'optimització de protocols de WSNs d'accés aleatori i basats en clúster. Els resultats mostren la utilitat d'escoltar el mitjà sense fil per a minimitzar el nombre de transmissions i també de modificar les probabilitats de transmissió després d'una col·lisió. Pel que fa a eMBB, ens enfoquem en un escenari de distribució massiva de continguts, en el qual un mateix contingut és enviat de forma simultània a un gran nombre d'usuaris mòbils. Aquest escenari és problemàtic, ja que les estacions base de la xarxa cel·lular no compten amb mecanismes eficients de multicast o broadcast. Per tant, la solució que s'adopta comunament és la de replicar el contingut per a cadascun dels usuaris que ho sol·liciten; és clar que això és altament ineficient. Per a resoldre aquest problema, proposem l'ús d'esquemes de network coding i d'arquitectures cooperatives anomenades núvols mòbils. En concret, desenvolupem un protocol per a realitzar la distribució massiva de continguts de forma eficient, juntament amb un model analític per a la seua optimització. Els resultats demostren que el model proposat és simple i precís
The 5th generation (5G) of mobile networks is just around the corner. It is expected to bring extraordinary benefits to the population and to solve the majority of the problems of current 4th generation (4G) systems. The success of 5G, whose first phase of standardization has concluded, relies in three pillars that correspond to its main use cases: massive machine-type communication (mMTC), enhanced mobile broadband (eMBB), and ultra-reliable low latency communication (URLLC). This thesis mainly focuses on the first pillar of 5G: mMTC, but also provides a solution for the eMBB in massive content delivery scenarios. Specifically, its main contributions are in the areas of: 1) efficient support of mMTC in cellular networks; 2) random access (RA) event-reporting in wireless sensor networks (WSNs); and 3) cooperative massive content delivery in cellular networks. Regarding mMTC in cellular networks, this thesis provides a thorough performance analysis of the RA procedure (RAP), used by the mobile devices to switch from idle to connected mode. These analyses were first conducted by simulation and then by an analytical model; both of these were developed with this specific purpose and include one of the most promising access control schemes: the access class barring (ACB). To the best of our knowledge, this is one of the most accurate analytical models reported in the literature and the only one that incorporates the ACB scheme. Our results clearly show that the highly-synchronized accesses that occur in mMTC applications can lead to severe congestion. On the other hand, it is also clear that congestion can be prevented with an adequate configuration of the ACB scheme. However, the configuration parameters of the ACB scheme must be continuously adapted to the intensity of access attempts if an optimal performance is to be obtained. We developed a practical solution to this problem in the form of a scheme to automatically configure the ACB; we call it access class barring configuration (ACBC) scheme. The results show that our ACBC scheme leads to a near-optimal performance regardless of the intensity of access attempts. Furthermore, it can be directly implemented in 3rd Generation Partnership Project (3GPP) cellular systems to efficiently handle mMTC because it has been designed to comply with the 3GPP standards. In addition to the analyses described above for cellular networks, a general analysis for smart metering applications is performed. That is, we study an mMTC scenario from the perspective of event detection and reporting WSNs. Specifically, we provide a hybrid model for the performance analysis and optimization of cluster-based RA WSN protocols. Results showcase the utility of overhearing to minimize the number of packet transmissions, but also of the adaptation of transmission parameters after a collision occurs. Building on this, we are able to provide some guidelines that can drastically increase the performance of a wide range of RA protocols and systems in event reporting applications. Regarding eMBB, we focus on a massive content delivery scenario in which the exact same content is transmitted to a large number of mobile users simultaneously. Such a scenario may arise, for example, with video streaming services that offer a particularly popular content. This is a problematic scenario because cellular base stations have no efficient multicast or broadcast mechanisms. Hence, the traditional solution is to replicate the content for each requesting user, which is highly inefficient. To solve this problem, we propose the use of network coding (NC) schemes in combination with cooperative architectures named mobile clouds (MCs). Specifically, we develop a protocol for efficient massive content delivery, along with the analytical model for its optimization. Results show the proposed model is simple and accurate, and the protocol can lead to energy savings of up to 37 percent when compared to the traditional approach.
Leyva Mayorga, I. (2018). On reliable and energy efficient massive wireless communications: the road to 5G [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/115484
TESIS

碩士
國立中正大學
通訊工程研究所
104
Two-layer cell architecture has been proposed as a candidate for future 5G systems, where the system constitutes of macro cells and small cells. Macro cells use the existing 4G system while small cell use 5G technology to provide higher high data rate and system capacity. A user first camps 4G systems through contention-based random access mechanism, and when very high data rate is needed it is handed over to 5G systems via contention-free random access. Whether the current 4G random access design is able to cope with the very large number of users anticipated in the future 5G systems is theme of this research. In this thesis, the performance of random access in the two-layer cell architecture is studied in realistic channel environment, with MTC (Machine-Type Communications) traffic model proposed by 3GPP. The performance indexes include access success probability, collision probability, the access delay and total power consumption. Numerical results show that the current 4G random access design is not able to achieve the 5G requirements because of high collision probability, and excessive access delay and power consumption. One remedy is to increase the random access opportunity (RAO). Our results show that with 3-times RAO, access success rate is increased to 96%, and collision probability is decreased to 17%, and that significantly improves the random access performance.

碩士
國立交通大學
電信工程研究所
103
In this thesis, we propose two kinds of iterative channel estimation method to suppress the pilot contamination phenomenon in 5G cellular mobile radio communication systems. Due to pilot sequence reuse in different cells, the estimated channel would be contaminated by neighboring cells which use the same pilot. To solve the pilot contamination problems caused by pilot sequence reuse, we first use estimated data sequence as a pilot signal to execute iterative channel estimation. Secondly, as the pilot and data sequences are transmitted in a combined manner, our second proposed method utilizes data sequence as an auxiliary pilot signal in addition to utilizing the orthogonal pilot signal when executing channel estimation. Our simulation results show that these methods can achieve the required BER performance within a acceptable number of iterations.

Experience a guided tour of the key information-theoretic principles that underpin the design of next-generation cellular systems with this invaluable reference. Written by experts in the field, the text encompasses principled theoretical guidelines for the design and performance analysis of network architectures, coding and modulation schemes, and communication protocols. Presenting an extensive overview of the most important ideas and topics necessary for the development of future wireless systems, as well as providing a detailed introduction to network information theory, this is the perfect tool for researchers and graduate students in the fields of information theory and wireless communications, as well as for practitioners in the telecommunications industry.

AbstractCommercial 5G mobile communication installations are currently ongoing. A variety of reasons, notably rising business and consumer needs as well as the advent of much more cheap equipment, are driving 5G and IoT growth. Substantial carrier investments in 5G networks, frequency, and infrastructure, as well as the adoption of international standards, are indeed assisting in driving development and increasing investor interest in IoT. Today’s modern 5G mobile cellular systems are emerging beyond current 4G technology, which will remain to fulfill diverse applications. 5G, which is expected to last a long time, may meet present needs like intelligent power applications while also forecasting future use cases like self-driving automobiles. Mobile operators would need to guarantee to ensure its added versatility simultaneously present as well as future use cases need as companies oversee the growth of technology. Cautious providers would control their expenditures to assure customer service as infrastructures migrate to 5G. The majority of 5G use case scenarios fall into three broad segments: improved mobile broadband (eMBB), enormous IoT, as well as critical communications, within each set of performance, and bandwidth, including delay needs. While 4G would remain to be utilized for so many consumers and commercial IoT scenarios, 5G offers IoT features that 4G as well as other networks do not. This would include 5G's capacity to accommodate a massive amount of fixed and portable IoT systems with variable speeds, capacity, and service level needs. As the Internet of Things develops, the adaptability of 5G would become increasingly more important for organizations wanting to satisfy the stringent needs of vital connectivity. Because of 5G's ultra-reliability as well as reduced latency, self-driving vehicles, intelligent power infrastructures, better industrial automation, and some other demanding technologies are becoming a possibility. While 5G increases Internet bandwidth, cloud services, machine intelligence, as well as cloud technologies would all assist to manage huge data quantities created by IoT. Additional 5G advancements, like low latency, and non-public networking, including the core of 5G, would eventually help realize the goals of an IoT network that is worldwide and capable of sustaining connectivity that is larger in size.

AbstractIn this technological era of wireless communication, various Internet devices and Wi-Fi zone play a significant role in the fast growth of data usage. The communication of people has been revolutionized by mobile communication systems. The rapid increase in the number of users, higher data rate, and requirement for higher bandwidth and voluminous data has become a challenge for Internet service providers. All these requirements are expected to be met by the next-generation communication network. The evolution of next-generation communication technology aims to emphasize the user terminal development that will provide access to various technologies and combine several flows from numerous technologies. In this paper, the authors have provided a detailed overview of the various wireless communication technologies and how it can be enhanced in future. A comparative study of the different generations of communication technologies has been done which includes 1G which has contented the elementary mobile voice, and 2G which has familiarized us with capacity and coverage. The quest continued with 3G for high-speed data that in turn provided a true experience to mobile bandwidth with 4G and finally the next-generation communication technology—5G. The varied variety of telecommunication services such as advanced mobile services, with the help of mobile and fixed networks, can be accessed with the help of the Fourth Generation (4G). The technology in the Fifth Generation (5G) is more advanced, and intelligent and it interconnects with the entire world. Moreover, in this paper, the authors have discussed the various issues and challenges faced in the existing cellular network, the limitation of conventional cellular systems, and the reason for the need for next-generation communication technology. Also, a detailed study on 5G network communication has been deliberated.