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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Novostavba Komerčně-administrativního centra v Chomutově / The Commercial-administrative Center in Chomutov

Konárek, Lukáš January 2019 (has links)
Diploma thesis deal with New building of The Commercial-administrative center in Chomutov. The Center has common basement and overground part is created from three separated buildings. These buildings are designed to create an atrium between them and sidewalk follow-up to adjacent sidewalks. Western building has two above ground floor, which they offer administrative place. Other two buildings are one above ground floor. They have place to shop, light refection and toilets. In basement of the Center there are a technological background and parking places. The remaining parking places are located on the terrain in the northern part. Construction system of the building is monolithic reinforced concrete. Roof is flat and single-skinned. Architectural building solution is created in software Archicad 21.0.0 Component from the company Graphisoft. Building physics is processed in group of software’s from the company K-CAD spol. s.r.o. In the specialization is the Diploma thesis dealing with study of roof panel. Panel is modeled in software RFEM 5.14 from the company Dlubal software s.r.o. The study then deals with the evaluation of the stress in the board from the most unfavorable combination of loads, the design of the reinforcement and the assessment of the reality of the proposed slab thickness, which was determined in the framework of study work using empirical formulas.
292

Horský hotel / Mountain hotel

Krošláková, Petra January 2020 (has links)
The main aim of this diploma´s thesis is an elaboration of the project documentation for the construction of object of mountain hotel, which is situated in the community Tatranská Lomnica which a part of the city High Tatras. The land is quiet gentle orientated on the northeast part. There is a beutiful view on the majestic peaks of High Tatras expecially Lomnický peak and on Liptovská basin from the south parth. The newly-built hotel is located in the turists and recreational location with pensions, and mountain hotels and also by it´s own architectural solution fits into the closest development area. This newly-built object is projected as a wooden construction made of massive wooden CLT panels. The building has four aboveground floors and one underground floor where are situated also parking places. There is a spacious parking lot in front of the object with the main entrance from the western part of the land. The facade and roof construction is projected as iventilated. The roof construction is projected as a pitched roof. The project documentation is procesed in the connection with the czech actual laws, notice and norms. The main work is deviced in to the text part and drawing part.
293

Cosmologies with massive gravitons and their properties / Cosmologie avec des gravitons massifs et leurs propriétés

Mazuet, Charles 27 September 2018 (has links)
La cosmologie en général et plus particulièrement le problème de la constante cosmologique sont d'une extrême importance et une ouverture vers une nouvelle physique. En effet grâce à la découverte de l’accélération de l’expansion de l’Univers, un tout nouveau groupe de théories est apparu. Jusqu’à présent la théorie utilisée pour décrire l’Univers à grande échelle était la Relativité Générale, mais maintenant plusieurs théories alternatives sont de bons candidats pour décrire et étudier le comportement de notre Univers à grande échelle. Parmi ces théories, la gravité massive sans fantôme (dRGT), propose d’ajouter une masse au graviton dans le but de simuler une constante cosmologique au lieu d’utiliser ce que l’on appelle l’énergie noire. Il a été prouvé que cette théorie est cohérente, mais aujourd’hui l’existence de cosmologies viables fournies par cette dernière est toujours une question ouverte. Au début de ma thèse, j’ai obtenu une procédure permettant d’obtenir toutes les solutions du type de Sitter dans la théorie dROT, en utilisant l’espace de Sitter comme espace physique et une métrique de référence plate dépendante d’un champ de Stuckelberg noté T(t,r). Une autre partie de ma thèse a été consacrée à l’analyse des perturbations anisotropes autour d’une des solutions mentionnées précédemment, pour pouvoir étudier la stabilité des solutions cosmologiques au sein de cette théorie. J’ai aussi exploré la possibilité de répondre à une question de longue date, qui est l’origine de la matière noire en utilisant la théorie dRGT. En effet l’idée est de partir de cette dernière pour obtenir une théorie mathématiquement et physiquement cohérente d’un champ massif de spin-2 sur un fond arbitraire, Ainsi, à la place de décrire l’énergie noire, j’ai conjecturé que le champ maintenant décrit pouvait faire partie de la matière noire, dont la nature est une des grandes questions de la physique moderne. / Cosmology in general and the cosmological constant problem are highly important as an insight on new physics. Indeed thanks to the discovery of the accelerating expansion of the Universe a whole bunch of new theories appeared. Until then, the General Relativity was the theory describing the Universe at large scale, but now several alternatives are good candidates to provide a better description about the large scale behaviour of our Universe. Among these theories, there is one called ghost-free Massive Gravity which gives the graviton a mass in order to mimic the cosmological constant instead of using the so-called dark energy. This theory was proved to be consistent but, until nowadays, the existence of viable cosmologies is still an on-going issue. In the first part of this thesis, we investigated a procedure to obtain all de Sitter solutions in dRGT theory, using de Sitter space as the physical space, with at reference metric depending on a Stuckelberg field T(t; r). The second part is devoted to the analysis of the anistropic perturbations around one of this solution, to investigate the stability of the cosmology of the theory. In the last part, we explore the posibility to answer a long-standing question, using the ghost-free Massive Gravity as a starting point in order to obtain a consistent theory of a massive spin-2 field on an arbitrary background. This time, instead of describing the dark energy, we conjecture that this field can be a part of dark matter, which is one of the substantial question for modern physics.
294

Analysis of Bandwidth and Latency Constraints on a Packetized Cloud Radio Access Network Fronthaul

Chaudhary, Jay Kant 20 May 2020 (has links)
Cloud radio access network (C-RAN) is a promising architecture for the next-generation RAN to meet the diverse and stringent requirements envisioned by fifth generation mobile communication systems (5G) and future generation mobile networks. C-RAN offers several advantages, such as reduced capital expenditure (CAPEX) and operational expenditure (OPEX), increased spectral efficiency (SE), higher capacity and improved cell-edge performance, and efficient hardware utilization through resource sharing and network function virtualization (NFV). However, these centralization gains come with the need for a fronthaul, which is the transport link connecting remote radio units (RRUs) to the base band unit (BBU) pool. In conventional C-RAN, legacy common public radio interface (CPRI) protocol is used on the fronthaul network to transport the raw, unprocessed baseband in-phase/quadrature-phase (I/Q) samples between the BBU and the RRUs, and it demands a huge fronthaul bandwidth, a strict low-latency, in the order of a few hundred microseconds, and a very high reliability. Hence, in order to relax the excessive fronthaul bandwidth and stringent low-latency requirements, as well as to enhance the flexibility of the fronthaul, it is utmost important to redesign the fronthaul, while still profiting from the acclaimed centralization benefits. Therefore, a flexibly centralized C-RAN with different functional splits has been introduced. In addition, 5G mobile fronthaul (often also termed as an evolved fronthaul ) is envisioned to be packet-based, utilizing the Ethernet as a transport technology. In this thesis, to circumvent the fronthaul bandwidth constraint, a packetized fronthaul considering an appropriate functional split such that the fronthaul data rate is coupled with actual user data rate, unlike the classical C-RAN where fronthaul data rate is always static and independent of the traffic load, is justifiably chosen. We adapt queuing and spatial traffic models to derive the mathematical expressions for statistical multiplexing gains that can be obtained from the randomness in the user traffic. Through this, we show that the required fronthaul bandwidth can be reduced significantly, depending on the overall traffic demand, correlation distance and outage probability. Furthermore, an iterative optimization algorithm is developed, showing the impacts of number of pilots on a bandwidth-constrained fronthaul. This algorithm achieves additional reduction in the required fronthaul bandwidth. Next, knowing the multiplexing gains and possible fronthaul bandwidth reduction, it is beneficial for the mobile network operators (MNOs) to deploy the optical transceiver (TRX) modules in C-RAN cost efficiently. For this, using the same framework, a cost model for fronthaul TRX cost optimization is presented. This is essential in C-RAN, because in a wavelength division multiplexing-passive optical network (WDM-PON) system, TRXs are generally deployed to serve at a peak load. But, because of variations in the traffic demands, owing to tidal effect, the fronthaul can be dimensioned requiring a lower capacity allowing a reasonable outage, thus giving rise to cost saving by deploying fewer TRXs, and energy saving by putting the unused TRXs in sleep mode. The second focus of the thesis is the fronthaul latency analysis, which is a critical performance metric, especially for ultra-reliable and low latency communication (URLLC). An analytical framework to calculate the latency in the uplink (UL) of C-RAN massive multiple-input multiple-output (MIMO) system is presented. For this, a continuous-time queuing model for the Ethernet switch in the fronthaul network, which aggregates the UL traffic from several massive MIMO-aided RRUs, is considered. The closed-form solutions for the moment generating function (MGF) of sojourn time, waiting time and queue length distributions are derived using Pollaczek–Khinchine formula for our M/HE/1 queuing model, and evaluated via numerical solutions. In addition, the packet loss rate – due to the inability of the packets to reach the destination in a certain time – is derived. Due to the slotted nature of the UL transmissions, the model is extended to a discrete-time queuing model. The impact of the packet arrival rate, average packet size, SE of users, and fronthaul capacity on the sojourn time, waiting time and queue length distributions are analyzed. While offloading more signal processing functionalities to the RRU reduces the required fronthaul bandwidth considerably, this increases the complexity at the RRU. Hence, considering the 5G New Radio (NR) flexible numerology and XRAN functional split with a detailed radio frequency (RF) chain at the RRU, the total RRU complexity is computed first, and later, a tradeoff between the required fronthaul bandwidth and RRU complexity is analyzed. We conclude that despite the numerous C-RAN benefits, the stringent fronthaul bandwidth and latency constraints must be carefully evaluated, and an optimal functional split is essential to meet diverse set of requirements imposed by new radio access technologies (RATs). / Ein cloud-basiertes Mobilfunkzugangsnetz (cloud radio access network, C-RAN) stellt eine vielversprechende Architektur für das RAN der nächsten Generation dar, um die vielfältigen und strengen Anforderungen der fünften (5G) und zukünftigen Generationen von Mobilfunknetzen zu erfüllen. C-RAN bietet mehrere Vorteile, wie z.B. reduzierte Investitions- (CAPEX) und Betriebskosten (OPEX), erhöhte spektrale Effizienz (SE), höhere Kapazität und verbesserte Leistung am Zellrand sowie effiziente Hardwareauslastung durch Ressourcenteilung und Virtualisierung von Netzwerkfunktionen (network function virtualization, NFV). Diese Zentralisierungsvorteile erfordern jedoch eine Transportverbindung (Fronthaul), die die Antenneneinheiten (remote radio units, RRUs) mit dem Pool an Basisbandeinheiten (basisband unit, BBU) verbindet. Im konventionellen C-RAN wird das bestehende CPRI-Protokoll (common public radio interface) für das Fronthaul-Netzwerk verwendet, um die rohen, unverarbeitet n Abtastwerte der In-Phaseund Quadraturkomponente (I/Q) des Basisbands zwischen der BBU und den RRUs zu transportieren. Dies erfordert eine enorme Fronthaul-Bandbreite, eine strenge niedrige Latenz in der Größenordnung von einigen hundert Mikrosekunden und eine sehr hohe Zuverlässigkeit. Um die extrem große Fronthaul-Bandbreite und die strengen Anforderungen an die geringe Latenz zu lockern und die Flexibilität des Fronthauls zu erhöhen, ist es daher äußerst wichtig, das Fronthaul neu zu gestalten und dabei trotzdem von den erwarteten Vorteilen der Zentralisierung zu profitieren. Daher wurde ein flexibel zentralisiertes CRAN mit unterschiedlichen Funktionsaufteilungen eingeführt. Außerdem ist das mobile 5G-Fronthaul (oft auch als evolved Fronthaul bezeichnet) als paketbasiert konzipiert und nutzt Ethernet als Transporttechnologie. Um die Bandbreitenbeschränkung zu erfüllen, wird in dieser Arbeit ein paketbasiertes Fronthaul unter Berücksichtigung einer geeigneten funktionalen Aufteilung so gewählt, dass die Fronthaul-Datenrate mit der tatsächlichen Nutzdatenrate gekoppelt wird, im Gegensatz zum klassischen C-RAN, bei dem die Fronthaul-Datenrate immer statisch und unabhängig von der Verkehrsbelastung ist. Wir passen Warteschlangen- und räumliche Verkehrsmodelle an, um mathematische Ausdrücke für statistische Multiplexing- Gewinne herzuleiten, die aus der Zufälligkeit im Benutzerverkehr gewonnen werden können. Hierdurch zeigen wir, dass die erforderliche Fronthaul-Bandbreite abhängig von der Gesamtverkehrsnachfrage, der Korrelationsdistanz und der Ausfallwahrscheinlichkeit deutlich reduziert werden kann. Darüber hinaus wird ein iterativer Optimierungsalgorithmus entwickelt, der die Auswirkungen der Anzahl der Piloten auf das bandbreitenbeschränkte Fronthaul zeigt. Dieser Algorithmus erreicht eine zusätzliche Reduktion der benötigte Fronthaul-Bandbreite. Mit dem Wissen über die Multiplexing-Gewinne und die mögliche Reduktion der Fronthaul-Bandbreite ist es für die Mobilfunkbetreiber (mobile network operators, MNOs) von Vorteil, die Module des optischen Sendeempfängers (transceiver, TRX) kostengünstig im C-RAN einzusetzen. Dazu wird unter Verwendung des gleichen Rahmenwerks ein Kostenmodell zur Fronthaul-TRX-Kostenoptimierung vorgestellt. Dies ist im C-RAN unerlässlich, da in einem WDM-PON-System (wavelength division multiplexing-passive optical network) die TRX im Allgemeinen bei Spitzenlast eingesetzt werden. Aufgrund der Schwankungen in den Verkehrsanforderungen (Gezeiteneffekt) kann das Fronthaul jedoch mit einer geringeren Kapazität dimensioniert werden, die einen vertretbaren Ausfall in Kauf nimmt, was zu Kosteneinsparungen durch den Einsatz von weniger TRXn und Energieeinsparungen durch den Einsatz der ungenutzten TRX im Schlafmodus führt. Der zweite Schwerpunkt der Arbeit ist die Fronthaul-Latenzanalyse, die eine kritische Leistungskennzahl liefert, insbesondere für die hochzuverlässige und niedriglatente Kommunikation (ultra-reliable low latency communications, URLLC). Ein analytisches Modell zur Berechnung der Latenz im Uplink (UL) des C-RAN mit massivem MIMO (multiple input multiple output) wird vorgestellt. Dazu wird ein Warteschlangen-Modell mit kontinuierlicher Zeit für den Ethernet-Switch im Fronthaul-Netzwerk betrachtet, das den UL-Verkehr von mehreren RRUs mit massivem MIMO aggregiert. Die geschlossenen Lösungen für die momenterzeugende Funktion (moment generating function, MGF) von Verweildauer-, Wartezeit- und Warteschlangenlängenverteilungen werden mit Hilfe der Pollaczek-Khinchin-Formel für unser M/HE/1-Warteschlangenmodell hergeleitet und mittels numerischer Verfahren ausgewertet. Darüber hinaus wird die Paketverlustrate derjenigen Pakete, die das Ziel nicht in einer bestimmten Zeit erreichen, hergeleitet. Aufgrund der Organisation der UL-Übertragungen in Zeitschlitzen wird das Modell zu einem Warteschlangenmodell mit diskreter Zeit erweitert. Der Einfluss der Paketankunftsrate, der durchschnittlichen Paketgröße, der SE der Benutzer und der Fronthaul-Kapazität auf die Verweildauer-, dieWartezeit- und dieWarteschlangenlängenverteilung wird analysiert. Während das Verlagern weiterer Signalverarbeitungsfunktionalitäten an die RRU die erforderliche Fronthaul-Bandbreite erheblich reduziert, erhöht sich dadurch im Gegenzug die Komplexität der RRU. Daher wird unter Berücksichtigung der flexiblen Numerologie von 5G New Radio (NR) und der XRAN-Funktionenaufteilung mit einer detaillierten RF-Kette (radio frequency) am RRU zunächst die gesamte RRU-Komplexität berechnet und später ein Kompromiss zwischen der erforderlichen Fronthaul-Bandbreite und der RRU-Komplexität untersucht. Wir kommen zu dem Schluss, dass trotz der zahlreichen Vorteile von C-RAN die strengen Bandbreiten- und Latenzbedingungen an das Fronthaul sorgfältig geprüft werden müssen und eine optimale funktionale Aufteilung unerlässlich ist, um die vielfältigen Anforderungen der neuen Funkzugangstechnologien (radio access technologies, RATs) zu erfüllen.
295

Design and implementation of LTE-A and 5G kernel algorithms on SIMD vector processor

Guo, Jiabing January 2015 (has links)
With the wide spread of wireless technology, the time for 4G has arrived, and 5G will appear not so far in the future. However, no matter whether it is 4G or 5G, low latency is a mandatory requirement for baseband processing at base stations for modern cellular standards. In particular, in a future 5G wireless system, with massive MIMO and ultra-dense cells, the demand for low round trip latency between the mobile device and the base station requires a baseband processing delay of 1 ms. This is 10 percentage of today’s LTE-A round trip latency, while at the same time massive MIMO requires large-scale matrix computations. This is especially true for channel estimation and MIMO detection at the base station. Therefore, it is essential to ensure low latency for the user data traffic. In this master’s thesis, LTE/LTE-A uplink physical layer processing is examined, especially the process of channel estimation and MIMO detection. In order to analyze this processing we compare two conventional algorithms’ performance and complexity for channel estimation and MIMO detection. The key aspect which affects the algorithms’ speed is identified as the need for “massive complex matrix inversion”. A parallel coding scheme is proposed to implement a matrix inversion kernel algorithm on a single instruction multiple data stream (SIMD) vector processor. The major contribution of this thesis is implementation and evaluation of a parallel massive complex matrix inversion algorithm. Two aspects have been addressed: the selection of the algorithm to perform this matrix computation and the implementation of a highly parallel version of this algorithm. / Med den breda spridningen av trådlös teknik, har tiden för 4G kommit, och 5G kommer inom en överskådlig framtid. Men oavsett om det gäller 4G eller 5G, låg latens är ett obligatoriskt krav för basbandsbehandling vid basstationer för moderna mobila standarder. I synnerhet i ett framtida trådlöst 5G-system, med massiva MIMO och ultratäta celler, behövs en basbandsbehandling fördröjning på 1 ms för att klara efterfrågan på en låg rundresa latens mellan den mobila enheten och basstationen. Detta är 10 procent av dagens LTE-E rundresa latens, medan massiva MIMO samtidigt kräver storskaliga matrisberäkningar. Detta är särskilt viktigt för kanaluppskattning och MIMO-detektion vid basstationen. Därför är det viktigt att se till att det är låg latens för användardatatrafik. I detta examensarbete, skall LTE/LTE-A upplänk fysiska lagret bearbetning undersökas, och då särskilt processen för kanaluppskattning och MIMO-detektion. För att analysera denna processing jämför vi två konventionella algoritmers prestationer och komplexitet för kanaluppskattning och MIMO-detektion. Den viktigaste aspekten som påverkar algoritmernas hastighet identifieras som behovet av "massiva komplex matrisinversion". Ett parallellt kodningsschema föreslås för att implementera en "matrisinversion kernel-algoritmen" på singelinstruktion multidataström (SIMD) vektorprocessor. Det största bidraget med denna avhandling är genomförande och utvärdering av en parallell massiva komplex matrisinversion kernel-algoritmen. Två aspekter har tagits upp: valet av algoritm för att utföra denna matrisberäkning och implementationen av en högst parallell version av denna algoritm.
296

Terahertz-Band Ultra-Massive MIMO Data Detection and Decoding

Jemaa, Hakim 04 April 2022 (has links)
As the quest for higher data rates continues, future generations of wireless communications are expected to concur even higher frequency bands, particularly at terahertz (THz) frequencies. Even though the vast bandwidths at the THz band promise terabit-per-second (Tbps) data rates, current baseband technologies do not support such high rates. In particular, the complexities of Tbps channel code decoding and ultra-massive multiple-input multiple-output data detection are prohibitive. This work addresses the efficient data detection and channel-code decoding problem under THz-band channel conditions and Tbps baseband processing limitations. We propose ultra-massive multiple-input multiple-output THz channel models, then investigate the corresponding performance of several candidate data detection and coding schemes. We further investigate the complexity of different detectors and decoders, motivating parallelizability at both levels. We recommend which detector to combine best with which channel code decoder under specific THz channel characteristics.
297

Corrigendum: Variability in X-Ray Line Ratios in Helium-Like Ions of Massive Stars: The Wind-Driven Case (Astronomy and Astrophysics (2019) 625 (A86) DOI: 10.1051/0004-6361/201834752)

Ignace, R., Damrau, Z., Hole, K. T. 01 June 2019 (has links)
Two equations in Ignace et al. (2019) have minor typos. The first correction is in Eq. (15). That expression has three lines. In the first line, there should be no multiplicative factor of R0 appearing. The correct equation is: (Formula Presented) The other two lines in Eq. (15) are correct. The second correction is in Eq. (19). As in Eq. (15), the appearance of R0 is in error. The correct expression is (Formula Presented) The mistakes appearing in Eqs. (15) and (19) are typos that have no bearing on the results appearing in the figures which were computed correctly, nor on the discussion or conclusions of the paper. (Equation Presented).
298

Modelo de gestión de riesgos empresariales en una organización de distribución de productos de consumo masivo / The risk management in a distribution company with massive consumption products

Luna Sánchez, Verónica, Kishimoto Uyehara, Manuel Felipe, Martell Mateo, Everth Jesús, Trigoso Roman, Allan Salvador 15 January 2020 (has links)
La gestión de riesgos empresariales es el componente estratégico y esencial que permite implementar acciones para evitar incumplimientos en los objetivos de las organizaciones, Gutierrez (2018). No es común encontrar un sistema de gestión de riesgos en empresas de distribución de productos de consumo masivo. Es por ello que el presente trabajo de investigación desarrolla un modelo de gestión de riesgos empresariales para una empresa de distribución de productos de consumo masivo. En la investigación se analizan diversos modelos de gestión de riesgos y se plantea un modelo simplificado alineado a las necesidades de los Gerentes Generales de empresas de este rubro, el cual ha sido elaborado considerando la opinión de líderes estratégicos de empresa de distribución de productos de consumo masivo. En el trabajo de investigación se concluye que el modelo de gestión de riesgos empresariales debe incluir la conformación de un comité de gestión de riesgos, la identificación de los procesos críticos a tomar en cuenta de acuerdo al impacto de los mismos en los resultados de la empresa, el análisis e identificación de riesgos, y en base a todo ello se plantean controles y mecanismos de monitoreo. El modelo incluye matrices para valoración de riesgos en base a impacto y probabilidad, un inventario de riesgos, así como propuestas para su control o mitigación. Al desplegar este modelo se pudo identificar riesgos intolerables y altos y luego de proponer controles se identificó que al aplicarse mitigaran el impacto o la probabilidad de ocurrencia del riesgo pasando a tener riesgos calificados como moderados o bajos. Se incluye una estimación de los costos de implementación del modelo, considerando recursos propios y externos, tomando en consideración la información de la empresa caso de estudio. Se obtiene como resultado que el costo de la implementación representaría aproximadamente el 0.06% de la facturación anual. / Business risk management is the strategic and essential factor that enables action to be implemented to avoid breaches of organizations' objectives. It is not common to find a risk management system in mass-consumer product distribution companies. That is why this research paper develops a business risk management model for a mass-consumption product distribution company. The research analyses various risk management models and proposes a simplified model aligned to the needs of the CEOs of the companies in this field, which has been developed, taking into account the opinion of strategic leaders of the company distributing mass consumer products. The research paper concludes that the business risk management model should include the formation of a risk management committee, the identification of critical processes to be considered according to their impact on company results, risk analysis, and identification. Based on this, monitoring controls and mechanisms are proposed. The model includes matrices for risk assessment based on impact and probability, a risk inventory, as well as proposals for control or mitigation. By deploying this model, it was possible to identify intolerable and high risks, and after proposing controls, it was identified that when applied, they mitigated the impact or likelihood of risk occurrence by becoming risks rated moderate or low. An estimate of the costs of implementing the model is included, considering own and external resources, considering the company's case study information. The results in the cost of implementation represent approximately 0.06% of annual billing. / Trabajo de investigación
299

L’amélioration des performances des systèmes sans fil 5G par groupements adaptatifs des utilisateurs / Performance improvement of 5G Wireless Systems through adaptive grouping of users

Hajri, Salah Eddine 09 April 2018 (has links)
5G est prévu pour s'attaquer, en plus d'une augmentation considérable du volume de trafic, la tâche de connecter des milliards d'appareils avec des exigences de service hétérogènes. Afin de relever les défis de la 5G, nous préconisons une utilisation plus efficace des informations disponibles, avec plus de sensibilisation par rapport aux services et aux utilisateurs, et une expansion de l'intelligence du RAN. En particulier, nous nous concentrons sur deux activateurs clés de la 5G, à savoir le MIMO massif et la mise en cache proactive. Dans le troisième chapitre, nous nous concentrons sur la problématique de l'acquisition de CSI dans MIMO massif en TDD. Pour ce faire, nous proposons de nouveaux schémas de regroupement spatial tels que, dans chaque groupe, une couverture maximale de la base spatiale du signal avec un chevauchement minimal entre les signatures spatiales des utilisateurs est obtenue. Ce dernier permet d'augmenter la densité de connexion tout en améliorant l'efficacité spectrale. MIMO massif en TDD est également au centre du quatrième chapitre. Dans ce cas, en se basant sur les différents taux de vieillissement des canaux sans fil, la périodicité d'estimation de CSI est supplémentaire. Nous le faisons en proposant un exploité comme un degré de liberté supplémentaire. Nous le faisons en proposant une adaptation dynamique de la trame TDD en fonction des temps de cohérence des canaux hétérogènes. Les stations de bases MIMO massif sont capables d'apprendre la meilleure politique d’estimation sur le uplink pour de longues périodes. Comme les changements de canaux résultent principalement de la mobilité de l'appareil, la connaissance de l'emplacement est également incluse dans le processus d'apprentissage. Le problème de planification qui en a résulté a été modélisé comme un POMDP à deux échelles temporelles et des algorithmes efficaces à faible complexité ont été fournis pour le résoudre. Le cinquième chapitre met l'accent sur la mise en cache proactive. Nous nous concentrons sur l'amélioration de l'efficacité énergétique des réseaux dotes de mise en cache en exploitant la corrélation dans les modèles de trafic en plus de la répartition spatiale des demandes. Nous proposons un cadre qui établit un compromis optimal entre la complexité et la véracité dans la modélisation du comportement des utilisateurs grâce à la classification adaptative basée sur la popularité du contenu. Il simplifie également le problème du placement de contenu, ce qui se traduit par un cadre d'allocation de contenu rapidement adaptable et économe en énergie. / 5G is envisioned to tackle, in addition to a considerable increase in traffic volume, the task of connecting billions of devices with heterogeneous service requirements. In order to address the challenges of 5G, we advocate a more efficient use of the available information, with more service and user awareness, and an expansion of the RAN intelligence. In particular, we focus on two key enablers of 5G, namely massive MIMO and proactive caching. In the third chapter, we focus on addressing the bottleneck of CSI acquisition in TDD Massive MIMO. In order to do so, we propose novel spatial grouping schemes such that, in each group, maximum coverage of the signal’s spatial basis with minimum overlapping between user spatial signatures is achieved. The latter enables to increase connection density while improving spectral efficiency. TDD Massive MIMO is also the focus of the fourth chapter. Therein, based on the different rates of wireless channels aging, CSI estimation periodicity is exploited as an additional DoF. We do so by proposing a dynamic adaptation of the TDD frame based on the heterogeneous channels coherence times. The Massive MIMO BSs are enabled to learn the best uplink training policy for long periods. Since channel changes result primarily from device mobility, location awareness is also included in the learning process. The resulting planning problem was modeled as a two-time scale POMDP and efficient low complexity algorithms were provided to solve it. The fifth chapter focuses on proactive caching. We focus on improving the energy efficiency of cache-enabled networks by exploiting the correlation in traffic patterns in addition to the spatial repartition of requests. We propose a framework that strikes the optimal trade-off between complexity and truthfulness in user behavior modeling through adaptive content popularity-based clustering. It also simplifies the problem of content placement, which results in a rapidly adaptable and energy efficient content allocation framework.
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Metodika řešení masivních úloh v GIS / Methodology for the solution of massive tasks in GIS

Opatřilová, Irena January 2015 (has links)
This doctoral thesis deals with the issue of solving massive tasks in GIS. These tasks process large volumes of geographic data with different formats. The thesis describes a theoretical analysis of the complexity of tasks and the possibilities to optimize sub-processes which lead to an acceptable solution. It considers the possibility of using parallelism in GIS, which leads to an acceleration in the processing of large volumes of geographic data. It also proposes a method for the optimization of processes through an algorithm which determines the number of means necessary for the successful solution of a task at a specified time and assigns processes to these means. Additionally, there is a proposed algorithm for the optimization of the preparation of data for extensive GIS projects. The algorithms have been validated by the results of a research project, the aim of which was to analyse the terrain surface above a gas line in the Czech Republic. The primary method of analysis was the classification of an orthophoto image, which was further refined through filtration using the ZABAGED layers. Therefore, the thesis deals with the possibility of improving the results of image classification using GIS instruments as well as dealing with the determination of the error rate in analysis results. The results of the analysis are now used for the strategic planning of maintenance and the development of gas facilities in the Czech Republic. The results of the work have general importance regarding the performance of other operations of the same class in GIS.

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