Increasing energy consumption is a result of the rapid growth in cellular communication technologies and a massive increase in the number of mobile terminals (MTs) and communication sites. In cellular communication networks, energy efficiency (EE) and spectral efficiency (SE) are two of the most important criteria employed to evaluate the performance of networks. A compromise between these two conflicting criteria is therefore required, in order to achieve the best cellular network performance. Fractional frequency reuse (FFR), classed as either strict FFR or soft frequency reuse (SFR), is an intercell interference coordination (ICIC) technique applied to manage interference when more spectrum is used, and to enhance the EE. A conventional cellular model's downlink is designed as a reference in the presence of inter-cell interference (ICI) and a general fading environment. Energy-efficient cellular models,such as cell zooming, cooperative BSs and relaying models are designed, analysed and compared with the reference model, in order to reduce network energy consumption without degrading the SE. New mathematical models are derived herein to design a distributed antenna system (DAS), in order to enhance the system's EE and SE. DAS is designed in the presence of ICI and composite fading and shadowing with FFR. A coordinate multi-point (CoMP) technique is applied, using maximum ratio transmission (MRT) to serve the mobile terminal (MT), with all distributed antenna elements (DAEs), transmit antenna selection (TAS) being applied to select the best DAE and general selection combining (GSC) being applied to select more than one DAE. Furthermore, a Cloud radio access network (C-RAN) is designed and analysed with two different schemes, using the high-power node (HPN) and a remote radio head (RRH), in order to improve the EE and SE of the system. Finally, a trade-off between the two conflicting criteria, EE and SE, is handled carefully in this thesis, in order to ensure a green cellular communication network.

This master’s thesis deals with a UMTS radio access network optimization, containing radio interface analysis, services and procedures description, ways to correct parameters calculations and settings and other issues necessary for a correct access network operation. The goal is effective network operation, minimum costs and maximum performance and flexibility of the network. The optimization during system operation is important because of the system character. The UMTS system uses the WCDMA technology, where particular users share the same frequency band and they are distinguished from one another via code sequences. The capacity of such a system is then given by the interference level - each particular user increases the interference level by the value corresponding to his transmit power. The maximum cell capacity is determined by the maximum interference level at which users can still operate with required services, so it is related not only to the number of users, but also to their bit rate. The optimization allows effective usage of the system for different services with different requirements. The main optimization tool is the radio resource management, containing number of algorithms, such as admission control, which decides the acceptance or rejection of a new user demanding certain service, power control, which ensure that users transmit with a minimal power sufficient for required service, handover and cell selection algorithms etc. The major parameter used by these algorithms is a cell load factor, which is related to the interference level margin. There are several methods for the load factor estimation and some of them are described in this work. Some other optimization techniques are mentioned here, too. This work also contains a laboratory exercise proposal for radio resource management introduction using the OPNET Modeler network simulation tool.

With Ericsson’s goal to have optimal user experience at 5G’s 2020 release, it is very important to optimize transport protocols and techniques to manage the increasing amount of data traffic. Additionally, it will be important to manage handovers between very high speed 5G networks and older networks. Today most of the traffic is video on demand and the amount of this kind of traffic is expected to increase. Moreover, the current amount of data traffic will increase by an order of magnitude over the next few years. This thesis focuses on radio access networks and the difficulties they face in delivering high speed data traffic. This thesis analyzes one of the most used TCP protocols, CUBIC, as well as a new transport protocol developed by Aspera, called the Fast and Secure Protocol. Aspera’s FASP is a new transport protocol that promises full link utilization. FASP is built upon UDP and uses advanced round trip time measurements and queuing delay to detect the available bandwidth between two communicating hosts. This thesis project also provides methods to realize experiments to assess the limitations of transport protocols. These experiments are conducted in an environment that resembles the upcoming 5G radio access network. Results have shown that both delay and packet loss affect TCP more than we expected and that high packet loss is devastating. In contrast, Aspera’s FASP is very resistant to both delay and packet loss. These results and analysis provide a foundation upon which others can build. / Med Ericssons mål att ha optimal användarupplevelse vid släppet av 5G år 2020 är det oerhört viktigt att optimera transportprotokoll och tekniker för att hantera den ökande mängden datatrafik. En annan viktig aspekt kan vara att hantera överlämningar mellan 5G nätverk och äldre radionätverk. Idag är den största trafiken streamad video och prognoser visar att den sortens trafik bara kommer att öka. Prognoserna visar också att all trafik kommer att öka mångfaldigt de närmaste åren. Denna thesis kommer att fokusera på svårigheterna just inom radionätverk. Denna thesis kommer att analysera ett av vårt mest använda transportprotokoll CUBIC TCP, den kommer också att analysera ett helt nytt transportprotokoll utvecklat av Aspera, Fast and Secure Protocol. Aspera lovar fullt utnyttjande av den mellanliggande länken. FASP är byggt ovanpå UDP och använder avancerade tur- och returtidsmätningar för att använda all outnyttjad bandbredd. Denna thesis visar även hur man kan göra experiment för att hitta begränsningar i transportprotokoll. Alla dessa experiment kommer utförs i en miljö som efterliknar det nya 5G-nätverket. Resultatet visar att både förlora paket tillsammans med en hög fördröjning påverkar mycket mer än väntat och att frekvent förlora paket är förödande för TCP. Asperas FASP är i motsats mycket tålig mot både paketförlust och hög fördröjning. Detta resultat och denna analys lägger en grund var andra kan arbeta vidare.

Dans les réseaux mobiles du future, un déploiement plus dense des points d’accés radio est prévu pour satisfaire la demande accrue de débit, mais les terminaux utilisateurs peuvent être affectés par une interférence inter-cellulaire plus forte. Par chance, la centralisation des traitements de signal en bande de base dans l’achitecture Cloud RAN (C-RAN) offre la possibilité de la coordination et du traitement conjoint de plusieurs cellules. Pour réellement permettre de déployer ces techniques, une étude bout-à-bout du CRAN est nécessaire selon plusieurs aspects, notamment l’architecture fonctionnelle, la stratégie de coordination, l’implémentation du traitement de signal multiutilisateur et les optimisations possibles pour un fonctionnement plus efficace.Dans cette thèse, nous proposons en premier une architecture qui définit le placement des fonctions du traitement en bande de base entre les unités distribuées et le serveur central. Le but de ce design est de permettre la réalisation des fonctions multi-utilisateurs en transmettant avec la moins de débit possible sur les liens de fronthaul reliant les différentes entités. Dans un second temps, nous présentons comment il est possible de coordiner les différentes cellules servies par le C-RAN en utilisant le concept de réseaux définis par logiciels adapté pour les réseaux d’accès radio. Nous avons mis en place un prototype démontrant la faisabilité de la méthode de contrôle proposée. Finalement, nous étudions l’allocation adaptative du débit sur les liens de fronthaul transportant les symboles numériques quantifiés des utilisateurs en besoin de traitement multi-cellulaire sur la voie montante pour exploiter l’interférence entre eux. Nous proposons un modèle d’optimisation qui inclut le coût des transmissions fronthaul pour maximiser ainsi le gain obtenu par l’opérateur du réseau où la communication multiutilisateur a lieu. Nous réalisons l’optimisation pour différents modèles de coût et en utilisants deux types de données: d’abord les estimations de canal supposées parfaites et disponibles en temps réel, puis seulement les statistiques du canal. Nous montrons que la méthode d’optimisation proposée permet d’exploiter plus efficacement les liens de fronthaul dans l’architecture précedemment définie. / In future mobile networks denser deployment of radio access points is planned to satisfy demand of higher throughput, but an increased number of mobile users can suffer from inter-cell interference. Fortunately, the centralization of base-band processing offered by Cloud Radio Access Network (C-RAN) architecture enables coordination and joint physical layer processing between cells. To make practical deployment of these techniques possible, we have to study C-RAN in an end-to-end view regarding several aspects: the functional architecture of a deployment, the multi-cell coordination strategy, the implementation of multi-user signal processing and possibilities for optimization to increase operational efficiency.In this thesis, first, we propose an architecture defining the placement of base-band processing functions between the distributed remote units and the central processing unit. The aim of this design is to enable multi-cell processing both on the uplink and the downlink while requiring low data rate between the involved entities. Secondly, we study how low latency coordination can be realized inside the central unit using software defined networking adapted to radio access networks. Our demonstration through a real-time prototype deployment shows the feasibility of the proposed control framework. Finally, we investigate adaptive allocation of fronthaul rate that is used for transferring quantized base-band symbols for users participating in uplink multi-cell reception in order to exploit interference between them. We propose an optimization model that includes the cost of fronthaul tranmissions and aims to maximize the gain of network operators from multi-user transmissions in C-RAN. We solve the optimization problem for different fronthaul pricing models, in a scenario where real-time and accurate channel estimates are available and in another where only channel statistics are exploited. Using our method - fitting in the architecture that we have defined - cost efficiency of fronthaul usage can be significantly improved.

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.

Currently, the IPv4 protocol is heavily used by institutions, companies and individuals, but every day there is a higher number of devices connected to the network such as home appliances, mobile phones or tablets. Each machine or device needs to have its own IP address to communicate with other machines connected to Internet. This implies the need for multiple IP addresses for a single user and the current protocol begins to show some deficiencies due to IPv4 address space exhaustion. Therefore, for several years experts have been working on an IP protocol update: the IPv6 128-bit version can address up to about 340 quadrillion system devices concurrently. With IPv6, today, every person on the planet could have millions of devices simultaneously connected to the Internet. The choice of the IP protocol version affects the performance of the UMTS mobile network and the browsers as well. The aim of the project is to measure how the IPv6 protocol performs compared to the previous IPv4 protocol. It is expected that the IPv6 protocol generates a smaller amount of signalling and less time is required to fully load a web page. We have analysed some KPIs (IP data, signalling, web load time and battery) in lab environment using Smartphones, to observe the behaviour of both, the network and the device.  The main conclusion of the thesis is that IPv6 really behaves as expected and generates savings in signalling, although the IP data generated is larger due to the size of the headers. However, there is still much work as only the most important webpages and the applications with a high level of market penetration operate well over the IPv6 protocol. / Cada día existe un mayor número de dispositivos conectados a la red, tales como electrodomésticos, teléfonos móviles inteligentes o tabletas, por lo que la red debe evolucionar constantemente y ser capaz de proveer servicio a todos los usuarios. Cada equipo necesita tener su propia dirección IP para comunicarse con otras máquinas conectadas a Internet, por lo que es necesario tener un gran número de direcciones IP y la versión del protocolo actual comienza a mostrar algunas deficiencias (debido fundamentalmente al agotamiento del espacio de direccionamiento IPv4 y algunas funciones de seguridad que han quedado obsoletas). Desde hace varios años, los expertos están trabajando en una actualización del protocolo IP: la versión seis (llamada IPv6) que utiliza 128 bits para el direccionamiento pudiendo administrar simultáneamente hasta unos 340 trillones de dispositivos al mismo tiempo. La elección de la versión del protocolo IP afecta al comportamiento de la red móvil, ya que los expertos todavía están optimizando y realizando cambios en la arquitectura de red y en los dispositivos para soportar el protocolo IPv6. El objetivo del proyecto consiste en comparar y evaluar las diferentes versiones del protocolo IP utilizado, en gran medida, para acceder a la red de internet. La principal conclusión del proyecto es que IPv6 realmente se comporta como se espera y genera ahorros en la señalización, aunque los datos IP generados son mayores. Sin embargo, aún queda mucho trabajo por hacer, ya que sólo las páginas más importantes y las aplicaciones más utilizadas por los usuarios funcionan bien sobre el protocolo IPv6.

This thesis has been carried out on behalf of the department of Digital Services - SDI at Ericsson. Ericsson Software Defined Infrastructure (SDI) is a telco grade hardware management solution for cloud infrastructure. In datacenter deployments, the extra management equipment needed by the solution becomes insignificant due to the amount of equipment it manages. But the closer to the cloudedge you get, the smaller in size the deployments become, thus making the management equipment an ever-increasing share of the total deployment seize leading to inefficient resource utilization, so called overhead. Especially with Distributed Radio Access Networks (RAN) many small deployments, often only consisting of a single compute-server used to process radio, will be deployed at radio sites and/or in buildings around cities to deliver cell service. In this type of usage, the overhead of equipment management builds up cumulatively due to the numerous amounts of deployments. This overhead leads to excessive maintenance, power usage, space needs for equipment, costs, and electronic waste. The goal of this thesis was to evaluate how to reduce the overhead of equipment management in a scenario involving numerous small-capacity widely-distributed sites which are common in the 5G telco cloud. The idea was to determine if the overhead could be reduced by exploiting Baseboard Management Controllers (BMC), this was tested by designing a low-footprint and lightweight proof of concept equipment management solution and implementing a prototype of it. By testing, verifying, and analyzing the proof-of-concept solution, it was concluded that by exploiting the BMC to run a custom software service that phoned home to a centralized management server it was possible to drastically reduce the overhead in such scenarios. It also became clear that BMCs could have even more usage areas and provide even greater value if support to run third partyapplications existed among them. / Detta examensarbete har utförts på uppdrag av avdelningen Digital Services - SDI på Ericsson. Ericsson Software Defined Infrastructure (SDI) är en hårdvaruhanteringslösning av telekomkvalitetför molnifrastruktur. I datacenterinstallationer blir den extra hanteringsutrustning som behövs av lösningen obetydlig på grund av mängden utrustning den hanterar. Men ju längre ut till molnkanten du kommer, desto mindre blir storleken på installationerna, vilket gör att hanteringsutrustning blir en ständigt ökande andel av den totala installationsstorleken som leder till ineffektivt resursutnyttjande, så kallat overhead. Speciellt med Distribuerade Radio Access Nätverk (RAN) så kommer många små installationer, ofta endast bestående av en enda server som utför radiolänksberäkningar, att vara fysiskt utplacerade vidbasstationer och/eller i byggnader runt städer för att leverera och tillhandage mobiltjänster. Vid denna typ av användning ökar overheadet för utrustningshanteringen kumulativt på grund av antalet installationer. Detta overhead leder till mer underhåll och elektroniskt avfall, större utrymmesbehov för utrustning samt högre strömförbrukning och kostnader. Målet med detta examensarbete var att utvärdera hur man kan minska overheadet hosutrustningshantering när det tillämpas på ett stort antal, små decentraliserade distribuerade installationer, vilket är förekommande i telekommoln. Idén var att undersöka om overheadet kunde minskas genom att utnyttja Baseboard Management Controllers (BMC), detta testades genom att designa en liten och lättviktigt konceptlösning för utrustningshantering samt implementera en prototyp av den. Genom att testa, verifiera och analysera konceptlösningen drogs slutsatsen att det var möjligt att drastiskt minska overheaden i sådana scenarion genom att utnyttja BMC att köra en egen mjukvarutjänst, som automatiskt anslöt till en central hanteringsserver. Genom arbetet blev det också tydligt att BMC:er skulle kunna ha ännu fler användningsområden och ge ännu större värde om stödet för att köra tredjepartsapplikationer på dem var mer utbrett

The maturing capabilities of Artificial Intelligence (AI) and Machine Learning (ML) have resulted in increased attention in research and development on adopting AI and ML in 5G and future networks. With the increased maturity, the usage of AI/ML models in production is becoming more widespread, and maintaining these systems is more complex and likely to incur technical debt when compared to standard software. This is due to inheriting all the complexities of traditional software in addition to ML-specific ones. To handle these complexities the field of ML Operations (MLOps) has emerged. The goal of MLOps is to extend DevOps to AI/ML and therefore speed up development and ease maintenance of AI/ML-based software, by, for example, supporting automatic deployment, monitoring, and continuous re-training of models. This thesis investigates how to construct an MLOps workflow by selecting a number of tools and using these to implement a workflow. Additionally, different approaches for triggering re-training are implemented and evaluated, resulting in a comparison of the triggers with regards to execution time, memory and CPU consumption, and the average performance of the Machine learning model.