Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-11-13T11:19:19Z No. of bitstreams: 1 Leandro Andrioli_.pdf: 6621163 bytes, checksum: b4a58154b0441ad094c57bbbea979ac4 (MD5) / Made available in DSpace on 2018-11-13T11:19:20Z (GMT). No. of bitstreams: 1 Leandro Andrioli_.pdf: 6621163 bytes, checksum: b4a58154b0441ad094c57bbbea979ac4 (MD5) Previous issue date: 2018-07-31 / Nenhuma / Até o ano de 2020, espera-se que a área de cobertura das redes de celulares aumente em 10 vezes, com mais de 50 bilhões de dispositivos conectados, suportando 100 vezes mais equipamentos de usuários e elevando a capacidade da taxa de dados em 1000 vezes. Tal circunstância gerará um aumento massivo no tráfego de dados, fomentando o desenvolvimento da 5G e fazendo com que a indústria e as iniciativas científicas passem a voltar seus esforços para atender a essa demanda. Ganha força, então, as pesquisas relacionadas a Cloud Radio Access Networks (C-RANs), uma arquitetura que consolida as base stations (BSs) para um ponto centralizado na nuvem, mudando a ideia de atuar com recursos fixos e limitados, na medida em que se beneficia de uma das características chave da Computação em Nuvem: a elasticidade de recursos. Um dos grandes desafios na arquitetura C-RAN reside na complexidade em orquestrar todos esses recursos computacionais de forma que o processamento das requisições seja realizado com alto desempenho e com o menor custo de infraestrutura possível. Diante de todo esse contexto, a presente dissertação busca desenvolver o modelo Elastic-RAN, propondo um conceito de elasticidade multinível não bloqueante, com orquestração automática de recursos através da coordenação de BBU Pools e seus BBUs, junto a um mecanismo de grão elástico adaptativo. A elasticidade multinível não bloqueante permite controlar o nível de BBU Pool (máquina física), haja vista o alto volume de tráfego e a distância máxima sugerida entre as antenas e os pools, e o nível de BBU (máquina virtual), em razão do alto processamento de CPU e memória necessária para as requisições, de modo a não penalizar os processamentos correntes. O mecanismo de grão elástico adaptativo permite provisionar e mapear os recursos sob demanda e em tempo de execução, considerando o uso corrente dos recursos, para que cada ação elástica seja executada com um grão próximo das necessidades correntes de processamento. O modelo Elastic-RAN foi avaliado por intermédio de experimentos que simularam diferentes perfis de cargas, os quais são executados em uma aplicação intensiva de CPU e de tráfego na rede, explorando a transferência de streamings e processando decodificação de blocos. Como resultados, foi possível constatar que o Elastic-RAN pode atingir ganhos que vão de 4% a 26%, em relação aos custos de execução, quando comparado à abordagem de elasticidade tradicional. Além disso, obteve melhor eficiência para todos os perfis de carga e reduziu em até 55% a quantidade de operações elásticas necessárias. Outrossim, frente a abordagem sem elasticidade, os ganhos de custos foram ainda superiores, ficando entre 51% e 70%. / It is expected that, by 2020, cell phone networks will have been increased 10 times their coverage area, with more than 50 billion connected devices, supporting 100 times more user equipment and increasing data rate capacity by 1000 times. This will lead to a massive increase in data traffic, fostering the development of 5G and making industry and scientific initiatives turn their efforts to meet this demand. In this scenario, Cloud Radio Access Networks (C-RANs) based researches, an architecture that consolidates base stations (BSs) to a cloud-centric point, are gaining momentum, changing the idea of fixed and limited resources, as it benefits from one of the key features of Cloud Computing: resource elasticity. One of the major challenges in C-RAN architecture lies in the high complexity of orchestrating all of these computational resources in order to perform the requests processing with high performance and the lowest possible infrastructure cost. Considering this context, the present dissertation seeks to develop the Elastic-RAN model, proposing a multilevel non-blocking elasticity concept, with automatic orchestration of resources through the coordination of BBU Pools and their BBUs, with an adaptive elastic grain mechanism. The multilevel non-blocking elasticity allows it control the level of BBU Pool (physical machine), given the high volume of traffic and the suggested maximum distance between antennas and pools, and the level of BBU (virtual machine), due to the high CPU processing and memory required for the requests, so as not to penalize the current processing. The adaptive elastic grain mechanism allows the provisioning and mapping of resources on demand and at runtime, considering the current use of resources, so that each elastic action is performed with a grain close to the current processing needs. The Elastic-RAN model was evaluated through experiments that simulated different load profiles, which are executed in an intensive CPU and network traffic application, exploiting the transfer of streamings and processing block decoding. As a result, it was possible to observe that Elastic-RAN may achieve gains ranging from 4 % to 26 %, in relation to execution costs, when compared to the traditional elasticity approach. In addition, it achieved better efficiency for all load profiles and reduced by 55 % the amount of elastic operations required. Also, given the non-elasticity approach, cost gains were even higher, going from 51 % to 70 %.

La forte croissance du trafic dans les réseaux mobiles s'accompagne d'une augmentation de son hétérogénéité, tant dans l'espace qu'au cours du temps. Cette thèse porte sur des algorithmes d’ordonnancement adaptés à des trafics avec des zones à forte concentration et variables dans le temps. Nous proposons un mécanisme de prêt de la ressource spectrale d'une cellule en sous-charge à une voisine en surcharge combinée à un ordonnancement réactif au sein de chaque cellule. Nous nous intéressons aussi à l’architecture Cloud Radio Access Network qui sépare les têtes de transmission radio (Remote Radio Heads, RRHs) des unités de traitement en bande de base (Baseband Units, BBUs). L’interconnexion entre les BBUs et les RRHs se fait selon deux modes. Le premier est appelé association bi-univoque et consiste à allouer les unités de ressources de la trame radio d’une BBU à une seule RRH. Dans le second mode, appelé association multiple, une BBU peut gérer plusieurs RRHs. Nous proposons un mode d’association hybride dans lequel les unités de ressource de chaque trame sont réparties en deux tranches. La première constitue une tranche non partagée qui est allouée aux utilisateurs centraux selon l’association bi-univoque afin d’augmenter le débit notamment à haute charge de trafic. La deuxième tranche est constituée par une quantité d’unités de ressources partagées par un groupe de RRHs appartenant au même BBU. Cette tranche commune est configurée en association multiple et est allouée aux utilisateurs frontaliers et mobiles. Nous montrons que le mode hybride réduit les interférences intercellulaires, diminue le nombre de handover inter-BBU et améliore la consommation énergétique. / The exponential growth of traffic in mobile networks is accompanied by an increase in its heterogeneity, both in space and over time. This thesis deals with scheduling algorithms adapted to highly concentrated and time-varying traffic zones. We propose a spectrum borrowing mechanism from an under-loaded cell to an overloaded one combined with a reactive intra-cellular scheduling algorithm. We are also interested in the Cloud Radio Access Network architecture that separates the Radio Head(RRH) from the Baseband Unit (BBU). The BBU is connected to the RRU according to two modes. The first one is called a one-to-one association and consists in allocating the resource units of the BBU radio frame to a single RRH. In the second mode which is called multiple association, a BBU can handle multiple RRHs. We propose a hybrid association mode in which the resource units of each frame are divided into two slices. The first one constitutes an unshared slice and is allocated to central users according to the one-to-one association in order to increase the throughput, especially at high traffic load. The second slice contains a quantity of resource units that are shared by a group of RRHs belonging to the same BBU. This common slice is configured according to the multiple association mode and is allocated to the edge and mobile users. We show that the hybrid mode reduces the inter-cell interferences, decreases the number of inter-BBU handovers and improves the energy consumption.

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Bokstavskunskap, ordavkodningsförmåga och fonologisk medvetenhet inklusive RAN (rapid automatized naming, benämningshastighet) har i tidigare studier visats vara prediktorer för den tidiga läsförmågan. Syftet med föreliggande studie var att kartlägga vilka kognitiva förmågor som kunde predicera utveckling av läsförståelse. Stort fokus lades på fonologisk medvetenhet i föreliggande studie. Metoder att mäta fonologisk medvetenhet utvärderas och diskuteras. Deltagarnas resultat från första klass jämfördes med deras prestation i andra klass. Det deltog 36 barn i föreliggande studie och de förmågor som undersöktes var: fonologisk medvetenhet, ordavkodning, läsförståelse och bokstavskunskap. Resultatet visade att läsförståelse i första klass predicerade läsförståelse i andra klass. Signifikanta korrelationer mellan läsförståelse och ordavkodning samt fonologisk medvetenhet konstaterades i föreliggande studie. Ordavkodning och fonologisk medvetenhet förklarade 58 % av variansen av läsförståelse i årskurs två.  Testet Fonologisk bearbetning förklarade den största delen av variansen. Vid undersökning av tester som mäter fonologisk medvetenhet framkom det att testet för RAN visade ett signifikant samband med rimtestet men inte med testet Fonologisk bearbetning. Resultatet beror troligen på att testerna mäter olika delar av fonologisk förmåga. Slutsatsen är att läsförståelse vid årskurs ett predicerar läsförståelse i årskurs två samt att fonologisk bearbetning tycks vara en stark prediktor för läsförståelse i årskurs två. / Letter knowledge, word decoding and phonological awareness including RAN (rapid automatized naming) are known to predict early reading ability. The purpose of this study was to evaluate the development of reading comprehension from first to second grade. Phonological awareness holds an important role in this study; different ways to measure this ability will be discussed.  In the study, 36 second graders participated and the following abilities were measured; phonological awareness, word decoding, reading comprehension and letter knowledge. Performances in first and second grade were compared. The results showed that reading comprehension in first grade predicts reading comprehension in second grade. Furthermore, significant correlations between reading comprehension, word decoding and phonological awareness were observed in second grade. Word decoding and phonological awareness together explains 58 % of the variance of reading comprehension in second grade. The test Phonological processing alone explains the biggest part of the variance in reading comprehension. The tests for phonological awareness show that RAN had a significant correlation with the rime test but not with the test Phonological processing. The correlation indicates that the tests measure different aspects of phonological skills. In conclusion reading comprehension in first grade predicts reading comprehension in second grade. Additionally, phonological processing seems to be a strong predictor for reading comprehension in second grade.

Le Cloud RAN a été préconisé pour la 5G. Cependant, sa mise en place rencontre des difficultés notamment sur l'intégration du fronthaul, ce dernier généralement basé sur l’interface CPRI représente le segment situé entre la Digital Unit et la Radio Unit. Vu les contraintes de débit, de latence et de gigue sur cette interface, le multiplexage en longueur est la solution adéquate pour son transport. En revanche, les technologies radio recommandées pour la 5G augmenteront considérablement les débits CPRI, ce qui rend l’utilisation du WDM bas coût très difficile. Cette thèse traite quatre sujets principaux : L'introduction d'un canal de contrôle dans le CPRI permettrait la supervision de l'infrastructure WDM et l'accordabilité en longueurs d'onde des transceivers. L’impact de l’intégration de ce canal de contrôle dans le fronthaul est étudié dans le chapitre II. La radio analogique sur fibre peut améliorer de manière significative l'efficacité spectrale du fronthaul, permettant potentiellement le transport des interfaces 5G. Une étude approfondie sur le gain réel apporté par cette solution est rapportée dans le chapitre III. La compression du CPRI basée sur la quantification uniforme et non uniforme est également une solution pour améliorer l'efficacité spectrale du CPRI. Le chapitre IV démontre expérimentalement les taux de compression réalisables. Enfin, les nouveaux splits fonctionnels sont considérés comme une solution prometteuse pour la 5G. Deux nouvelles interfaces ont été identifiées pour les splits couche haute et couche basse. Une étude théorique et expérimentale de ces nouvelles interfaces est présentée dans le chapitre V. / Cloud Radio Access Network (RAN) was identified as a key enabler for 5G. Its deployment is however meeting multiple challenges notably in the fronthaul integration, the latter being the segment located between the Digital Unit and the Radio Unit generally based on CPRI. Giving its bit-rate, latency and jitter constrains, Wavelength Division Multiplexing (WDM) is the most adequate solution for its transport. However, the radio technologies recommended for 5G will drastically increase the CPRI bit-rate making its transport very challenging with low-cost WDM. This thesis deals with four main topics : The introduction of a control channel in the CPRI enables offering the WDM infrastructure monitoring and the wavelength tunability in the transceivers. The study of this control channel integration in the fronthaul link is reported in the second chapter as well as an investigation on the wireless transmission of CPRI. The use of Analog Radio over Fiber (A-RoF) can significantly improve the fronthaul spectral efficiency compared to CPRI-based fronthaul enabling, potentially, the transport of 5G interfaces. A thorough investigation on the actual gain brought by this solution is stated in the third chapter. CPRI compression based on uniform and non-uniform quantization is also a solution to enhance the CPRI spectral efficiency. The fourth chapter describes this solution and experimentally shows the achievable compression rates. Finally, establishing a new functional split in the radio equipment was considered as a promising solution for 5G. Two new interfaces have been identified for high and low layer functional splits. A theoretical and experimental study of these new interfaces is reported in the fifth chapter.

La densification de réseau à l'aide de petites cellules massivement déployées sur les zones macro-cellules, représente une solution prometteuse pour les réseaux mobiles 5G avenir pour faire face à l'augmentation du trafic mobile. Afin de simplifier la gestion de l'hétérogène du réseau d'accès radio (Radio Access Network RAN) qui résulte du déploiement massif de petites cellules, des recherches récentes et des études industrielles ont favorisé la conception de nouvelles architectures de RAN centralisés appelés comme Cloud-RAN (C-RAN), ou RAN virtuel (V-RAN), en incorporant les avantages du cloud computing et Network Functions Virtualization (NFV). Le projet de DynaRoC vise l'élaboration d'un cadre théorique de l'orchestration de ressources pour les C-RAN et dériver les limites de performance fondamentaux ainsi que les arbitrages entre les différents paramètres du système, et la conception de mécanismes d'orchestration de ressources dynamiques sur la base des conclusions théoriques à atteindre un équilibre de performance souhaité, en tenant compte des différents défis de conception. Le doctorant va étudier les mécanismes d'optimisation des ressources novatrices pour favoriser le déploiement de C-RAN, améliorer leur performance exploitant la technologie Network Functions Virtualization / Network densification using small cells massively deployed over the macro-cell areas, represents a promising solution for future 5G mobile networks to cope with mobile traffic increase. In order to simplify the management of the heterogeneous Radio Access Network (RAN) that results from the massive deployment of small cells, recent research and industrial studies have promoted the design of novel centralized RAN architectures termed as Cloud-RAN (C-RAN), or Virtual RAN (V-RAN), by incorporating the benefits of cloud computing and Network Functions Virtualization (NFV). The DynaRoC project aims at (1) developing a theoretical framework of resource orchestration for C-RAN and deriving the fundamental performance limits as well as the tradeoffs among various system parameters, and (2) designing dynamic resource orchestration mechanisms based on the theoretical findings to achieve a desired performance balance, by taking into account various design challenges. The PhD student will investigate innovative resource optimization mechanisms to foster the deployment of C-RANs, improving their performance exploiting the enabling Network Functions Virtualization technology

In recent years, several studies and simulations have been made on changing the current Radio Access Network (RAN) architecture into a more centralized access network where the base band processing is done in a central oce (CO) instead of out by the antenna site. This new architecture is denoted as the mobile fronthaul and is planned to be in use for the coming 5G network. The studies that have been made so far suggest that the new architecture can reduce cost, power usage and latency which are important factors regarding environmental, economical and data transmission issues. Furthermore, the new architecture allows a smarter distribution of data for each sector covered by the antennas, reducing redundant data transmission and thus increases the data eciency. The disadvantage or challenge however is that some of the optical components will be transferred from the currently controlled environment in the CO to an uncontrolled outdoor environment at the antenna site, which may generate risks as these components may be sensitive to especially changes in temperature. In this master thesis, the optical performance of four di erent passive lter setups, using a thin lm lter (TFF), an arrayed waveguide grating (AWG) and an interleaver, has been studied and compared in order to nd the most suitable lter setup for the mobile fronthaul. These optical parameters include insertion loss, isolation, crosstalk, 3 dB passband, center wavelength drift and also bit error-rate (BER) which have all been measured over a temperature interval of -40-85oC. Moreover, the measurement results have been compared with results from simulations done with VPItransmissionmaker. From the measurement results, the TFF had a better optical performance and reliability compared to the AWG mainly due to a higher isolation and a lower BER penalty of 0.2 dB compared to 0.5-1.5 dB for the AWG. Considering data capacity and economical aspects for a more realistic mobile fronthaul scenario with 80 channels using dense wavelength division multiplexing (DWDM) however, the AWG connected to the interleaver is more benecial without risking negative a ects on trac performance. / Under senare år har flera studier och simulationer utförts med syfte att ändra arkitekturen på dagens radioaccess-nätverk till ett mer centraliserat nätverk där basbandsprocesseringen sker i en central nod istället för ute vid antennen och radiomasterna. Denna nya arkitektur kallas mobile fronthaul och planeras att realiseras till 5G-nätet. De studier som har gjorts hittills indikerar på att den nya arkitekturen kan minska ekonomiska kostnader, elanvändningen och latens vilka är viktiga faktorer som bland annat rör miljö-, ekonomi och kapacitetrelaterade områden. Dessutom kan data fördelas på ett smartare sätt över alla delområden som antennerna täcker vilket minskar redundant datatrafik och därmed ökar den effektiva mängden data som skickas ut. Problemet eller utmaningen är att vissa optiska komponenter behöver flyttas från en nuvarande kontrollerad miljö till en okontrollerad utemiljö vid radiomasterna vilket kan medföra risker då dessa komponenter främst kan vara väldigt temperaturkänsliga. Inom detta examensarbete har optisk prestanda studerats, analyserats och jämförts mellan fyra olika filterkonstellationer bestående av ett tunnfilmsfilter, ett AWG-filter och en interleaver med syfte att finna vilken konstellation som passar bäst för mobile fronthaularkitekturen. De optiska parametrarna består av insertionsförluster, isolation, överhörningsinterferens, 3 dB-passband, centervåglängdsdrift samt bitfelsgrad vilka alla har blivit undersökta över ett temperaturintervall på -40-85oC. Utöver detta så har mätresultaten jämförts med simulationer gjorda med VPItransmissionmaker. Utifrån mätresultaten kunde det konstateras att tunnfilmfiltret hade bättre optiska egenskaper och även högre trovärdighet jämfört med AWG-filtret främst på grund av en högre isolation och lägre bitfelsgradsstraff på 0.2 dB jämfört med 0.5-1.5 dB för AWG-filtret. Om en endast avväger datakapacitet och ekonomiska aspekter för ett mer realistiskt scenario för mobile fronthaul med 80 DWDM-kanaler så är AWG-filtret tillsammans med interleavern mer foördelaktig att välja utan att riskera några negativa påverkningar på trafikprestandan.

Cellular networks have significantly transformed the way we communicate and access data and the data rates have only been increasing for the last 30 years. 5G is the current generation of cellular networks and enables faster data rates and lower latency. One of the cellular network architectures used to enable 5g is centralized radio access networks (C-RAN). C-RAN centralizes all the baseband units (BBU) into one or a few locations in contrast to traditional architectures where BBUs are separated. This centralization causes more demand on the fronthaul to transfer larger amounts of data. To mitigate this demand on the fronthaul, functional splits were developed to distribute the baseband functions dependent on the need. This thesis focuses on simulating several functional splits in C-RAN with packetized fronthaul. The objective is to study the impact the functional split options have on the network by investigating key metrics such as fronthaul link throughput, utilization, and, buffer usage. The thesis includes the development of a digital twin (DT) of C-RAN deployments. This digital twin is implemented in Python using the SimPy library to enable discrete event simulation. The DT was then used to simulate each split option over low, medium, and high traffic loads. The network that was simulated includes one BBU, fronthual link, one switch, and three remote radio units with 64 antennas. The fronthaul link is 1 km long and has a transfer rate of 100 Gbps. The results show that various functional split options have a significant impact on the network’s overall performance. This impact is mostly dependent on the split option choice and not on the load for this configuration. Overall, this thesis contributes to the understanding of functional splits in centralized radio access networks with packetized fronthaul. / Mobilnäten har förändrat hur vi kommunicerar och får tillgång till data, och datahastigheterna har bara ökat under de senaste 30 åren. 5G är den nuvarande generationen av mobilnät och möjliggör snabbare datahastigheter och lägre latens. En av de mobilnät arkitekturer som används för att möjliggöra 5g är centraliserade radioaccessnät (C-RAN). C-RAN centraliserar alla basbandsenheter (BBU) till en eller ett mindre antal platser i motsats till traditionella arkitekturer där BBU är separerade. Denna centralisering leder till att fronthaul länken belastas mer för att överföra större data mängder. För att minska denna belastning på fronthaul länken kan funktionella uppdelningar användas för att distribuera basbandsfunktionerna beroende på behov. Det här arbetet fokuserar på att simulera flera funktionella uppdelningar i centraliserade radio radioaccessnätvärk med paketerad fronthaul. Syftet är att studera vilken påvärkan de funktionella uppdelnings alternativen har på nätverket genom att undersöka och mäta värden som genomströmning, utnyttjande av fronthaul kabel och buffertanvändning i fronthaulen. I arbetet inkluderar utvecklingen av en digital tvilling (DT) av C-RAN. Denna digitala tvilling implementeras i Python med hjälp av SimPy-biblioteket för att möjliggöra discrete event simulation"vilket betyder simulering av diskreta händelser. DT användes sedan för att simulera varje uppdelnings alternativ över låg, medelhög och hög trafikbelastning. Nätverket som simulerades inkluderar en badeband unit (BBH), en fronthual länk, en switch och tre remote radio unit (RRU) med 64 antenner. Fronthaul länken är 1 km lång och har en överföringshastighet på 100 Gbps. Resultaten visar att olika uppdelningar har en betydande påvärkan på nätverkets övergripande prestanda. Denna påverkan beror främst på valet av delningsalternativet och inte av belastningen för denna konfiguration.svis så bidrar detta arbete till förståelsen av funktionella delningar i centraliserade radioaccessnät radioaccessnät med paketerad fronthaul i olika trafikbelastningar.

Open Radio Access Networks (Open RANs) enable flexible cellular network deployments by adopting open-source software and white-box hardware to build reference architectures customizable to innovative target use cases. The Open Radio Access Network (O-RAN) Alliance defines specifications introducing new Radio Access Network (RAN) Intelligent Controller (RIC) functions that leverage open interfaces between disaggregated RAN elements to provide precise RAN control and monitoring capabilities using applications called xApps and rApps. Multiple xApps targeting novel use cases have been developed by the O-RAN Software Community (OSC) and incubated on the Near-Real-Time RIC (Near-RT RIC) platform. However, the Near-RT RIC has, so far, been demonstrated to support only a single xApp capable of controlling the RAN elements. This work studies the scalability of the OSC Near-RT RIC to support simultaneous control signaling by multiple xApps targeting the RAN element. We particularly analyze its internal message routing mechanism and experimentally expose the design limitations of the OSC Near-RT RIC in supporting simultaneous xApp control. To this end, we extend an existing open-source RAN slicing xApp and prototype a slice-aware User Equipment (UE) admission control xApp implementing the RAN Control E2 Service Model (E2SM) to demonstrate a multi-xApp control signaling use case and assess the control routing capability of the Near-RT RIC through an end-to-end O-RAN experiment using the OSC Near-RT RIC platform and an open-source Software Defined Radio (SDR) stack. We also propose and implement a tag-based message routing strategy for disambiguating multiple xApps to enable simultaneous xApp control. Our experimental results prove that our routing strategy ensures 100% delivery of control messages between multiple xApps and E2 Nodes while guaranteeing control scalability and xApp non-repudiation. Using the improved Near-RT RIC platform, we assess the security posture and resiliency of the OSC Near-RT RIC in the event of volumetric application layer Denial of Service (DoS) attacks exploiting the E2 interface and the E2 Application Protocol (E2AP). We design a DoS attack agent capable of orchestrating a signaling storm attack and a high-intensity resource exhaustion DoS attack on the Near-RT RIC platform components. Additionally, we develop a latency monitoring xApp solution to detect application layer signaling storm attacks. The experimental results indicate that signaling storm attacks targeting the E2 Terminator on the Near-RT RIC cause control loop violations over the E2 interface affecting service delivery and optimization for benign E2 Nodes. We also observe that a high-intensity E2 Setup DoS attack results in unbridled memory resource consumption leading to service interruption and application crash. Our results also show that the E2 interface at the Near-RT RIC is vulnerable to volumetric application layer DoS attacks, and robust monitoring, load-balancing, and DoS mitigation strategies must be incorporated to guarantee resiliency and high reliability of the Near-RT RIC. / Master of Science / Telecommunication networks need sophisticated controllers to support novel use cases and applications. Cellular base stations can be managed and optimized for better user experience through an intelligent radio controller called the Near-Real-Time Radio Access Network (RAN) Intelligent Controller (RIC) (Near-RT RIC), defined by the Open Radio Access Network (O-RAN) Alliance. This controller supports simultaneous connections to multiple base stations through the E2 interface and allows simple radio applications called xApps to control the behavior of those base stations. In this research work, we study the performance and behavior of the Near-RT RIC when a malicious or compromised base station tries to overwhelm the controller through a Denial of Service (DoS) attack. We develop a solution to determine the application layer communication delay between the controller and the base station to detect potential attacks trying to compromise the functionality and availability of the controller. To implement this solution, we also upgrade the controller to support multiple radio applications to interact and control one or more base stations simultaneously. Through the developed solution, we prove that the O-RAN Software Community (OSC) Near-RT RIC is highly vulnerable to DoS attacks from malicious base stations targeting the controller over the E2 interface.

Mobile communication technology has become crucial in shaping the way modern society functions. The evolution of cellular networks has created an increasingly interconnected world, supporting various heterogeneous infrastructures. With the rollout of 5G, cellular networks are not only expected to support social and communication transformations, but also techno-economic growth for various industry, private and enterprise users. The approach of standardizing 5G Radio Access Network (RAN) architecture has been different from previous generations as it calls for more virtualized and software-based approaches that are flexible and open. The concept of Open RAN is a movement for open interfaces between the disaggregation of software and hardware of the RAN. Traditionally, the RAN market has been dominated by a handful of incumbent vendors deploying purpose-built RAN solutions. However, Open RAN enables an ecosystem that invites multiple-vendor solutions and creates a completely different market dynamic. This thesis explored the competitive conditions for incumbent and small vendors in the Open RAN ecosystem. This was also answered within the context of scale economies of vendors and implications of enterprise solutions in Open RAN. The study applied an exploratory and inductive approach where the researcher analyzed literature, as well as conducted interviews with several industry experts. The conclusions of the study suggests that incumbent vendors will lose shares in the RAN market as they will have to compete with smaller vendors that try to establish themselves. It was also suggested that the current immature state of Open RAN is not suitable for mission-critical deployments, but is instead a more viable option for software-based enterprise solutions. Further, it is suggested that dynamic relationships between incumbents and smaller vendors is necessary in order to drive the development of Open RAN. / Mobil kommunikationsteknik har blivit avgörande för utformandet av det moderna samhället. Utvecklingen av cellulära nätverk har skapat en alltmer sammankopplad värld som stödjer olika heterogena infrastrukturer. Med utbyggnaden av 5G förväntas cellulära nätverk inte bara stödja sociala och kommunikationstransformeringar, utan även tekno-ekonomisk tillväxt för olika industri-, privat- och företagsanvändare. Tillvägagångssättet att standardisera 5G radioåtkomstnätverk (RAN) arkitektur har varit annorlunda än tidigare generationer eftersom det kräver mer virtualiserade och mjukvarubaserade metoder som är flexibla och öppna. Konceptet bakom öppna RAN (Open RAN) är en rörelse för öppna gränssnitt mellan uppdelningen av mjukvara och hårdvara i RAN. Traditionellt har RAN-marknaden dominerats av ett fåtal etablerade leverantörer som implementerar specialbyggda RAN-lösningar. Open RAN möjliggör dock ett ekosystem som öppnar upp för multileverantör lösningar och skapar en helt annan marknadsdynamik. Den här uppsatsen undersökte konkurrensvillkoren för etablerade och små leverantörer i Open RAN-ekosystemet. Detta besvarades också inom ramen för skalfördelar för leverantörer och implikationer av företagslösningar i Open RAN. Studien tillämpade ett explorativt och induktivt tillvägagångssätt där forskaren analyserade litteratur, samt genomförde intervjuer med flera branschexperter. Slutsatserna av studien tyder på att etablerade leverantörer kommer att förlora andelar på RAN-marknaden eftersom de kommer att behöva konkurrera med mindre leverantörer som försöker etablera sig. Det föreslogs också att det nuvarande omogna tillståndet för Open RAN inte är lämpligt för kritiska RAN-lösningar, istället är det ett mer genomförbart alternativ för mjukvarubaserade företagslösningar. Vidare föreslås det att dynamiska relationer mellan etablerade och mindre leverantörer är nödvändiga för att driva utvecklingen av Open RAN.