As 5G becomes more established and faces widespread roll-out, energy consumption of radio access networks around the globe will increase. Since the high-frequency radio waves used in 5G communication has a shorter effective range compared to the waves used in previous generations, 5G networks will require a higher number of radio units to compensate for their reduced range. Since the transmission of radio waves is a costly procedure in terms of energy consumption, this further increases the relevancy of radio equipment when considering solutions for increasing radio access networks' energy efficiency. This thesis has therefore provided a possible solution for increasing the energy efficiency of an O-RAN compliant radio access network by decreasing the energy consumption of its radio units. If a network's radio units are capable of entering a low-power sleep mode whenever they are left idle, i.e. not handling any traffic, the energy efficiency of a network can thus be increased by forcing its radio units to enter sleep mode as often as possible. This can be done by offloading traffic from radio units with little traffic onto other nearby radio units. The handovers required to perform such offloading, however, need to be predicted on the fly somewhere within the network. The solution proposed within this thesis therefore utilizes a component indigenous to the O-RAN architecture called RIC and its functionality-defining xApps which are capable of automatically detecting situations where radio units can be put to sleep as well as handling the offloading procedures. Through testing inside a simulated network, the set of xApps designed as a solution resulted in a potential 20-35% decrease in energy consumption among a radio access network's radio units.

This Thesis investigates and develops novel bidirectional and reconfigurable optical access architectures based on WDM technology with the aim of solving the problem of cost and complexity associated to the WDM-PON transceivers. In particular, depending on the capacity requirements of the network, the investigation and development deal with two specific environments of application. In case of low capacity access platforms, we propose and validate new dispersion tolerant optical transmission systems based on the employment of optical broadband sources operating in the third transmission band and whose adaptability to the transport of RoF signals is realized, for the first time, by means of Mach-Zehnder optical interferometer structures. The optical bandpass filtering feature of the Mach-Zehnder device is key to overcome the chromatic dispersion-induced limitations arising from the spectral width of the source and, thus, significantly increase the system operative bandwidth to several tens of GHz. The incorporation of a Mach-Zehnder structure has a relatively low degree of implementation complexity and opens the possibility to transmit RoF signals using cost-effective optical broadband sources in optical access platforms being, at the same time, a viable alternative to other dispersion compensation techniques under certain scenarios. Good RoF transmission performance is experimentally achieved over single mode and multi mode fiber links employing optical amplitude and optical phase modulation. The SCM technique is also used for the generation of down- and up-stream signals to improve the link bandwidth utilization and allow converging transport of wired and wireless services. Service flexibility is demonstrated by means of different types of codification concerning the transmitted binary information. In spectrum sliced optical broadband source multichannel applications, the dynamical assignment of capacity is realized by means of a compact routing scheme based on optical switching and validated over different routing scenarios. Moreover, two extra functionalities offered by the Mach-Zehnder device, such as the photonic suppression of harmonic and intermodulation distortion and the all-optical microwaves generation and up-conversion, are demonstrated. For optical access platforms requiring high capacity transport we propose and validate light sources-centralized optical transmission systems where the PolMUX technique is employed for the first time in the access platform as a novel strategy to minimize the cost and complexity of the terminal units in accordance with the centralization concept. The PolMUX principle uses light polarization as a degree of freedom to efficiently multiplex two orthogonal optical fields at the same wavelength into the same optical channel. Under this principle, the optical carriers required for the down- and uplink transmission can be provided by a single and centralized coherent source. It means that the terminal unit can be kept source-free and operative wavelength-independent. This concept is firstly validated over a single-channel full-duplex optical transmission system adopting RoF and SCM techniques for the generation and transport of the down- and upstream signals. Apart of fulfilling the requirements of quality of transmission after the polarization demultiplexing process, we demonstrate that the tracking and control of polarization can be also centralized at the central office for further minimization of the terminal unit complexity. Finally, the effectiveness of the PolMUX technique is exploited in the access network in order to perform full-duplex multichannel communications where reconfiguration of capacity depending on the actual demand and service convergence, required in RoF, are also demonstrated. / Grassi Marangione, F. (2013). Centralized transmission techniques for full-duplex reconfigurable WDM optical access networks [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34507

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-05-11T12:40:43Z No. of bitstreams: 1 Felipe Rabuske Costa_.pdf: 3408830 bytes, checksum: 25a67ecb02629c811b5f305a1f2e3d27 (MD5) / Made available in DSpace on 2018-05-11T12:40:43Z (GMT). No. of bitstreams: 1 Felipe Rabuske Costa_.pdf: 3408830 bytes, checksum: 25a67ecb02629c811b5f305a1f2e3d27 (MD5) Previous issue date: 2018-02-28 / Nenhuma / Estima-se que até o ano de 2020, cerca de 50 bilhões de dispositivos móveis estarão conectados a redes sem fio e que 78% de todo o tráfego de dados gerado por esse tipo de dispositivos será conteúdo multimídia. Essas estimativas fomentam o desenvolvimento da quinta geração de redes móveis (5G). Uma das arquiteturas mais recentemente proposta, chamada de Fog Radio Access Networks (F-RAN), dá aos componentes localizados na borda da rede poder de processamento e armazenamento endereçados às atividades da rede. Um dos principais problemas dessa arquitetura é o intenso tráfego de dados no seu canal de comunicação centralizado chamado fronthaul, utilizado para conectar as antenas (F-APs) à rede externa. Dado esse contexto, esse trabalho apresenta o Nuoxus, um modelo de caching de conteúdo multimídia voltado para F-RANs que visa amenizar esse problema. Ao armazenar esse tipo de conteúdo nos nós de rede mais próximos ao usuário, o número de acessos concorrentes ao fronthaul é reduzido, sendo esse um dos fatores agravantes na latência de comunicação na rede. O Nuoxus pode ser executado em qualquer nó da rede que possua capacidade de armazenamento e processamento, ficando responsável por gerenciar o caching de conteúdo desse nó. Sua política de substituição de conteúdo utiliza a similaridade de requisições entre os nós filhos e o restante da rede como um fator para definir a relevância de armazenar o conteúdo requisitado em cache. Além disso, utilizando esse mesmo processo, o Nuoxus sugere, de forma proativa, aos demais nós filhos que apresentam um alto grau de similaridade que façam o caching desse conteúdo, visando um possível futuro acesso. A análise do estado da arte demonstra que até o momento não existe nenhum outro trabalho que explore o histórico de requisições para fazer caching de conteúdo em arquiteturas multicamadas para redes sem fio de forma proativa e sem utilizar algum componente centralizado para fazer coordenação e predição de caching. A fim de comprovar a eficiência do modelo, foi desenvolvido um protótipo utilizando o simulador ns-3. Os resultados obtidos demostram que a utilização do Nuoxus foi capaz de reduzir a latência de rede em cerca de 29.75%. Além disso, quando comparado com outras estratégias de caching, o número de acesso à cache dos componentes de rede aumentou em 53.16% em relação à estratégia que obteve o segundo melhor resultado. / It is estimated that by the year 2020, about 50 billion mobile devices will be connected to wireless networks and 78% of the data traffic of this kind of device will be multimedia content. These estimates foster the development of the 5th generation of mobile networks (5G). One of the most recently proposed architectures, named Fog Radio Access Networks or F-RAN, gives the components located at the edge of the network the processing power and storage capacity to address network activities. One of the main problems of this architecture is the intense data traffic in its centralized component named fronthaul, which is used to connect the antennas (FAPs) to the external network. Given this context, we propose Nuoxus, a multimedia content caching model for F-RANs that aims to mitigate this problem. By storing the content in the nodes closest to the user, the number of concurrent accesses to the fronthaul is reduced, which decreases the communication latency of the network. Nuoxus can run on any network node that has storage and processing capacity, becoming the responsible for managing the cache of that node. Its content replacement policy uses the similarity of requests between the child nodes and the rest of the network as a factor to decide the relevance of storing the requested content in the cache. Furthermore, by using this same process, Nuoxus proactively suggests to the child nodes whose degree of similarity is high to perform the caching of the content, assuming they will access the content at a future time. The State-of-the-art analysis shows that there is no other work that explores the history of requests to cache content in multi-layer architectures for wireless networks in a proactive manner, without using some centralized component to do coordination and prediction of caching. To demonstrate the efficiency of the model, a prototype was developed using the ns 3 simulator. The results obtained demonstrate that the use of Nuoxus reduced network latency in 29.75%. In addition, when compared to other caching strategies, the cache hit increased by 53.16% when compared to the strategy that obtained the second-best result.

De nos jours, la demande en trafic mobile a considérablement augmenté. Face à cette croissance, plusieurs propositions font l'objet d'étude pour remédier à un tel défi. L’architecture des réseaux d’accès de type Cloud (C-RAN) est l’une des propositions pour faire face à cette demande croissante, et constitue une solution candidate potentielle pour les réseaux futurs 5G. L'architecture C-RAN dissocie deux éléments principaux de la station de base: La BBU ou ``Baseband Unit", qui constitue une unité intelligente pour le traitement des données en bande de base, et le RRH ou ``Remote Radio Head", constituant en une antenne passive pour fournir l'accès aux utilisateurs (UEs). Grâce à l’architecture C-RAN, les BBUs sont centralement regroupées, alors que les RRHs sont distribués sur plusieurs sites. Plusieurs avantages sont ainsi dérivés, tels que le gain en multiplexage statistique, l’efficacité d’utilisation des ressources, et l’économie de puissance. Contrairement à l’architecture conventionnelle où chaque RRH est exclusivement associé à une BBU, dans l’architecture C-RAN, plusieurs RRHs sont regroupés en une seule BBU lorsque les conditions de charge sont faibles. Ceci présente plusieurs avantages, tel que l’amélioration en efficacité énergétique et la minimisation en consommation de puissance. Dans cette thèse, nous adressons le problème d’optimisation des associations BBU-RRH. Nous nous intéressons à l’optimisation des regroupements des RRHs aux BBUs en tenant compte de critères multiples. Plusieurs contraintes sont ainsi envisagées, tel que la réduction de la consommation d'énergie sous garantie de Qualité de Service (QoS) minimale. En outre, la prise en compte du changement du niveau d’interférence en activant/désactivant les BBUs est primordiale pour l’amélioration de l’efficacité spectrale. En plus, décider dynamiquement de la réassociation des RRHs aux BBUs sous des conditions de charges variables représente un défi, vu que les UEs connectés aux RRHs changeant leurs associations font face à des ``handovers" (HOs). / The demand on mobile traffic has been largely increasing nowadays. Facing such growth, several propositions are being studied to cope with this challenge. Cloud-Radio Access Networks Architecture (C-RAN) is one of the proposed solutions to address the increased demand, and is a potential candidate for future 5G networks. The C-RAN architecture dissociates two main elements composing the base station: The Baseband Unit (BBU), consisting in an intelligent element to perform baseband tasks functionalities, and the Remote Radio Head (RRH), that consists in a passive antenna element to provide access for serviced User Equipments (UEs). In C-RAN architecture, the BBUs migrate to a Cloud data center, while RRHs remain distributed across multiple sites. Several advantages are derived, such as statistical multiplexing gain, efficiency in resource utilization and power saving. Contrarily to conventional architecture, where each RRH is associated to one BBU, in C-RAN architecture, multiple RRHs can be embraced by one single BBU when network load conditions are low, bringing along several benefits, such as enhanced energy efficiency, and power consumption minimization. In this thesis, the BBU-RRH association optimization problem is addressed. Our aim is to optimize the BBU-RRH association schemes, taking into consideration several criteria. The problem presents many constraints: For example, achieving minimized power consumption while guaranteeing a minimum level of Quality of Service (QoS) is a challenging task. Further, taking into account the interference level variation while turning ON/OFF BBUs is paramount to achieve enhanced spectral efficiency. Moreover, deciding how to re-associate RRHs to BBUs under dynamic load conditions is also a challenge, since connected UEs face handovers (HOs) when RRHs change their associations.

In order to realize the convergence of the optical infrastructure of fixed and mobile access networks, the objective of this thesis is to study the solutions for distributing native radio carriers through typical optical access networks.The first Part describes the contexts and the main physical properties of the optical and radio access networks: from nowadays deployed Fiber To The Home (FTTH) systems, and their expected evolutions, to the current radio system Universal Mobile Telecommunications System (UMTS) towards the expected requirements of modern mobile radio systems. This allows to settle the optical environment in which the Radio over Fiber(RoF)-functionalities will have to be integrated, and to know on which radio systems'figures of merits to focus on when implementing it. The second Part shows the benefit and possibilities of re-using the optical infrastructure of the fixed access networks for distributed radio systems. Then a review of the analog and digital RoF techniques is proposed, and their feasibility of integration into legacy FTTH systems is discussed. The third part deals with the computing and simulations of an analog RoF-system where the optical link is either passive or optically pre-amplified, and even boosted. The goal is to provide numerical results to the practical lab. results of the second half of the fourth part where the Signal to Noise Ratio (SNR) matters. Therefore successively formal expressions, numerical results for simple 2-tone signals and more realistic UMTS signals are considered. The fourth and last part deals with the obtained practical results. These can be split into two main categories : Error Vector Magnitude (EVM)-oriented results where an Avalanche Photo-Detector (APD) is used for legacy and extended-reach PON architectures using a direction shared Semiconductor Optical Amplifier (SOA) ; and an Adjacent/Alternate Channel power Leakage Ratio (ACLR)-driven part where the focus is seton a very critical figure of merit of radio systems, especially in the downlink. The latter part turned out to be mandatory and prevailing over the initially considered EVM concerns. Hence several RoF architectures, compatible with PONs, are introduced in order to overcome the non-linearities undergone by the RoF-signals, induced by the chromatic dispersion of the PON's fiber and the laser chirp, and degrading the ACLR performances

abstract: Access Networks provide the backbone to the Internet connecting the end-users to the core network thus forming the most important segment for connectivity. Access Networks have multiple physical layer medium ranging from fiber cables, to DSL links and Wireless nodes, creating practically-used hybrid access networks. We explore the hybrid access network at the Medium ACcess (MAC) Layer which receives packets segregated as data and control packets, thus providing the needed decoupling of data and control plane. We utilize the Software Defined Networking (SDN) principle of centralized processing with segregated data and control plane to further extend the usability of our algorithms. This dissertation introduces novel techniques in Dynamic Bandwidth allocation, control message scheduling policy, flow control techniques and Grouping techniques to provide improved performance in Hybrid Passive Optical Networks (PON) such as PON-xDSL, FiWi etc. Finally, we study the different types of software defined algorithms in access networks and describe the various open challenges and research directions. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2015

Cette thèse s’inscrit dans le cadre de la montée en débit des réseaux d’accès optiques passifs. Les travaux menés durant cette thèse s’appuient sur le constat que les technologies actuelles basées sur le multiplexage temporel, arriveront à leurs limites dans les années à venir et ne pourront plus répondre à l’évolution des besoins en débit. L’étude des problèmes rencontrés lors les déploiements actuels conduit à proposer une autre forme de multiplexage plus adaptée aux débits demandés par les utilisateurs : le multiplexage fréquentiel (ou FDM/FDMA). Les travaux réalisés dans cette thèse ont pour but de montrer la faisabilité d’une telle architecture en laboratoire. Les objectifs sont de déterminer les débits atteignables, que ce soit pour le lien descendant (du central vers l’abonné) ou pour le lien montant (abonnée vers central), mais également de réaliser une étude théorique afin de mettre en lumière les limites de cette solution. Des algorithmes d’allocation dynamique de ressources ont été élaborés et validés expérimentalement afin de déterminer la capacité totale de chaque lien. L’architecture utilisant deux longueurs d’ondes distinctes (une pour le lien descendant et l’autre pour le lien montant) permet d’atteindre un débit de 40 Gbps et 20 Gbps respectivement pour le lien descendant et montant en utilisant le format de multiplexage FDM/FDMA. Enfin, une architecture hybride n’employant qu’une seule longueur d’onde pour le transport à la fois les données montantes et descendantes a été explorée et permet d’atteindre un débit symétrique de 25Gbps. / This thesis is part of the growing capacity of passive optical access networks. The works done during this thesis are based on the fact that current technologies, employing time division multiplexing, will reach their limits in the coming years and will no longer respond to changes in high bitrates requirements. The study of problems encountered during the current deployments led us to propose another form of multiplexing more suitable for bitrates requested by users: the FDM/FDMA PON, frequency division multiplexing. The work done in this thesis aim to demonstrate the feasibility of a such architecture in the laboratory. The objectives are to determine the achievable capacity, whether for the downlink (from central office to user) or the uplink (subscriber to central), but also to achieve a theoretical study to highlight the limitations of this solution. Algorithms for dynamic allocation of resources have been developed and validated experimentally to determine the total capacity of each link. The architecture using two distinct wavelengths (one for the downlink and one for the uplink) achieves a capacity of 40Gbps for the downlink and 20Gbps for the uplink by using FDM/FDMA PON. Finally, a hybrid architecture using a single wavelength to transport both uplink and downlink data has been explored and achieves a symmetrical capacity of 25Gbps

Aujourd’hui, l’usage des données lié aux services et contenus proposés sur Internet est en croissance continue et les opérateurs de télécommunications font face à une demande croissante en connectivité. Dans ce contexte, il est indispensable que la transition vers les réseaux très haut débit soit gérée de manière efficace afin de préserver, voire incrémenter, le niveau de concurrence sur le marché ainsi que maximiser l’investissement efficace au bénéfice des consommateurs à travers une combinaison appropriée de différentes formes de concurrence, de différentes technologies et d’investissement à la fois privé et public. Si accompagnée de manière efficace, cette transition peut représenter une grande opportunité pour les marchés des télécommunications européens, les transformant en marchés modernes et concurrentiels et permettant à la régulation ex ante de se retirer progressivement. Nous passons en revue les cadres institutionnels et réglementaires pour les réseaux d’accès fixes de nouvelle génération implémentés en France, Allemagne, Italie, Royaume-Uni et Espagne. A partir d’un modèle de concurrence calibré, nous simulons l’évolution des marchés à horizon 2050 et analysons dans quelle mesure ces cadres paraissent efficaces afin de restituer les meilleurs résultats pour le secteur et pour les consommateurs. Les résultats de notre modèle calibré suggèrent que, afin d’obtenir des meilleurs résultats en terme de bien-être total de long-terme, dans des proportions plus ou moins grandes, certains ajustements pourraient être introduits dans les cadres institutionnels et réglementaires considérés.Nous formulons ainsi, pour chacun des pays analysés, des recommandations visant à accélérer la couverture en très haut débit et à améliorer le niveau de concurrence. / Today, data usage driven by content and service providers over the Internet is constantly increasing and telecoms operators are expected to meet an increasing demand for connectivity. In this context, it is vital that the transition between legacy and ultrabroadband networks is properly managed in order both to preserve or improve the state of competition in the market and to maximize efficient investment to the benefit of consumers through an appropriate combination of different forms of competition, of different technologies and of private and public investment. If properly accompanied, the transition from legacy to next generation access networks can represent a major opportunity for the current European telecommunications markets, definitively transforming them into competitive and modern markets and allowing ex ante regulation to progressively step-back.We review the institutional and regulatory frameworks for fixed next generation access networks currently implemented in France, Germany, Italy, United Kingdom and Spain. Based on a calibrated competition model, we simulate market evolution up to 2050 and appraise to what extent these frameworks seem effective in order to achieve the best long-term results both for the industry and for consumers. The results of our calibrated model suggest that, to a greater or lesser extent, some adjustments might be introduced in the above-mentioned frameworks in order to achieve better outcomes in terms of total welfare in the long run. For each of the countries reviewed, we formulate policy recommendations aimed to accelerate NGA coverage and to improve the state of competition in ultrabroadband.

Due to the rapid growth of mobile networks, network operators need to expand their coverage and capacity. Addressing these two needs is challenging. One factor is the requirement for cost-efficient transport via heterogeneous networks. In order to achieve this goal, Internet connectivity is considered a cost-efficient transport option by many operators for small cell backhaul. This thesis project investigates if a small cell network's requirements can be fulfilled by utilizing Internet connectivity for backhaul. In order to answer this question several measurements have been made to assess different aspect of live networks and compare them with the network operator's requirements. Different measurement protocols are utilized to evaluate some of the key network characteristics, such as throughput, jitter, packet loss, and delay. These measurement protocols are described in this thesis. Moreover, improving the bandwidth available in real-time (BART) measurement method was one of the main achievements of this thesis project. Evaluation of the measurement results indicates that fiber based access together with Internet connectivity would be the best and cheapest solution as a backhaul for small cell network in comparison with almost all of the other types of broadband access technologies. It should be noted that asymmetric digital subscriber line (ADSL) and cable- TV access networks proved to be unable to meet the requirements for small cell backhaul. This project gives a clear picture of the current broadband access network infrastructure's attributes and highlights the possibility of reducing backhaul costs by using broadband Internet connectivity as a backhaul transport option. / Dagens snabbt ökande mobilia datatrafik gör att nätverksoperatörerna behöver utöka både täckning och kapacitet hos sina nät. Att tillgodose båda dessa behov är en utmaning. Ett krav är kostnadseffektiva transporter via heterogena nätverk. För att uppfylla detta utreder många operatörer möjligheten att använda Internet-baserad returtrafik (backhaul) för småceller. Detta examensarbete utreder huruvida kraven för småceller kan uppfyllas genom att utnyttja en Internet-baserad returtrafik. För att kunna besvara denna fråga har flera mätningar utförts i syfte att bedöma olika aspekter av verkliga nätverk och jämföra dem med nätverksoperatörens krav. Olika mätprotokoll utnyttjas för att utvärdera några av de viktigaste egenskaperna hos nätet, såsom hastighet, jitter, paketförluster och förseningar. Dessa mätprotokoll beskrivs i dettta examensarbete. Dessutom/Vidare har metoden "bandbredd tillgänglig för realtidsmätningar" bandwidth available in real-time (BART) förbättrats. Utvärdering av mätresultaten visar att fiberbaserad access tillsammans med Internetanslutning är den bästa och billigaste returtrafiklösningen för småcellsnätverk för nästan alla olika typerna av bredbandsteknik, förutom för (asymmetric digital subscriber line) ADSL och kabelaccessnät. Detta projekt ger en tydlig bild av den aktuella nätinfrastrukturens egenskaper och möjligheten att reducera returtrafik-kostnaderna genom att använd bredbandsanslutning med Internet som transport kostnader.

The wavelength-division-multiplexed passive optical network (WDM-PON) offers many advantages such as large bandwidth per user, easy management, high network security and low insertion loss enabling long-reach and/or high split-ratio. However, with the rapid development and growing interest for deployment of WDM-PON, the PON systems are becoming increasingly vulnerable to various failures. Therefore, network supervision becomes extremely important to guarantee an appropriate level of network reliability performance. The aim of PON supervision is to provide automated test and diagnostic capability without compromising the available bandwidth for services. An essential function is to detect any kind of deterioration in the network that can cause suspended services and to remotely localize these faults in order to avoid the high cost arising from troubleshooting. In this thesis, we evaluate several existing WDM PON supervision methods, based on which two simple and cost-effective new solutions are proposed to localize fiber failures in WDM PON systems. In the first solution, a conventional optical time domain reflectometry (OTDR) and a switch unit are employed, while in the second method, a novel architecture based on N×N arrayed waveguide grating (AWG) is proposed. Both methods are able to localize failures in feeder fiber and drop fibers without e.g. using expensive tunable OTDRs. A patent has been filed based on the second solution. The first proposed method is validated by simulations using VPI Transmission Maker. According to the results, this supervision method is able to give accurate measurement of many different types of failures that may happen in a fiber link. Furthermore, VPI is examined in terms of its future applicability in modeling complete PON supervision methods based on OTDR.