Heterogeneous Network (HetNet) deployment has been considered as the main approach to boost capacity and coverage in Long Term Evolu-tion (LTE) networks in order to fulfill the huge future demand on mo-bile broadband usage. In order to study the improvement on network performance, i.e. capacity, coverage and user throughput, from pico cell densification in LTE HetNets, a network densification algorithm which determines the placement locations of the pico sites based on pathloss has been designed and applied to build several network models with different pico cell densities. The study has been taken based on a real radio network in a limited urban area using an advanced Matlab-based radio network simulator. The simulation results show that the network performance generally is enhanced by introducing more pico cells to the network.

Wireless networks have become a necessity with the increased mobility in human life. From cellular telephony to the Internet, all types of communication are now provided over wireless networks. However, to offer wireless network coverage over an area requires a potentially expensive infrastructure deployment. Such deployment requires base stations which until now have been completely proprietary to the equipment vendors. Moreover, proprietary equipment is almost always costly and offer less flexibility than standardized modular solutions. This situation results in a high cost for network upgradation and hinders network development. A remedy is available via modularization, hence the Open Base Station Architecture Initiative (OBSAI) is trying to modularize and standardize one of the most expensive elements of the wireless infrastructure, the base station. OBSAI standards aim to modularize the base station architecture and enable true interoperability among the various modules. However, the goal has not yet been achieved due to some features of the standard. This thesis project has studied the standards and pointed out some areas that must be concentrated upon when performing interoperability tests. It also proposes several standards amendments to foster greater interoperability among the modules of a base station. This study focuses on the RP3 interface of the OBSAI specification with the goal of making truly inter-operable baseband and RF modules, thus commoditizing the modules. The result is expected to be lower cost, greater interoperability, faster time-to-market, and more cooperative research. / Langattomat laajakaistaverkot ovat tulleet välttämättömäksi osaksi liikkuvien ihmisten elämää. Lähes kaikki kommunikaatiotarpeet äänipuheluista internettiin pystytään toteuttamaan langattomien verkkojen avulla. Kuitenkin jotta langattomilla verkoilla pystytään tarjoamaan täysi peittävyys yli maan, se vaatii varsin kalliita investointeja verkkoinfrastruktuuriin. Langattomien verkkojen investoinnit koostuvat suurelta osin tukiasemista, jotka tähän asti ovat olleet kullakin verkkotoimittajalla täysin omanlaisensa toteutus. Kun jokainen verkkotoimittaja toteuttaa kaikki tukiaseman osat erilailla, se tarkoittaa että kutakin tukiaseman osia valmistetaan suhteellisesti pienempiä määriä ja sitä myötä niistä tulee mahdollisesti kalliimpia verrattuna standardoituhin modulaarisiin tukiasemaratkaisuihin. Nykyinen tilanne siis osaltaan johtaa siihen että verkkojen rakentaminen ja päivittäminen on kallista. Eräs ratkaisu tähän ongelmaan on tarjolla modulaarisessa tukiasemaratkaisussa ja siksi OBSAI, Open Base Station Initiative, pyrkii modulaarisoimaan ja standardoimaan yhden kalliimmista verkkoinfrastruktuurin osista, tukiaseman. OBSAI standardi pyrkii modularisoimaan tukiasema-arkkitehtuurin ja mahdollistamaan todellisen yhteensopivuuden tukiaseman eri osien välillä. Tätä todellista yhteensopivuutta ei ole vielä täysin pystytty toteuttamaan, johtuen tietyistä standardin epätarkkuuksista. Tässä lopputyössä on analysoitu OBSAI standardia ja identifioitu alueet, joihin pitää keskittyä, kun modulien välistä yhteensopivuutta testataan. Työn lopputulemana myös ehdotetaan useita parannuksia ja muutoksia standardiin, jotta todellinen yhteensopivuus modulien välillä saavutetaan. Painopiste lopputyössä on OBSAI standardin RP3 rajapinta, joka määrittelee kantataajuusosan (BB) ja radiotaajuusosan (RF) välisen rajapinnan. Kun OBSAI standardia saadaan parannettua työssä ehdotetuin toimenpitein, lopputuloksena on oletettavasti alhaisempi tukiaseman kokonaiskustannus, mahdollisuus käyttää yhteensopivia moduleita eri valmistajilta, nopeampi tuotteiden markkinoille vienti sekä parantunut tutkimusyhteistyö eri yritysten välillä. / Trådlösa nät har blivit en nödvändighet i vår allt mer mobila livsstil. Från mobiltelefoni till Internet, trådlösa nät erbjuder många typer av kommunikation. Men att erbjuda trådlös täckning i ett område kan kräva installation av en mängd dyrbar telekomutrustning. En sådan utbyggnad kräver basstationer som fram till nu har varit patentskyddade av respektive leverantör. Och patentskyddad utrustning är oftast både dyrare och mindre flexibel jämfört med standardiserade modulära lösningar. Resultatet är höga kostnader för att uppgradera näten och att utvecklingen försvåras. Ett botemedel är användningen av standardiserade moduler. Därfär försöker Open Base Station Architecture Initiative (OBSAI) att standardisera moduler i ett av de dyraste nätelementen i trådlösa nät, basstationen. OBSAI har som mål att dela upp basstationen i definierade moduler och möjliggöra fullständig interaktion mellan olika moduler. Men på grund av vissa egenskaper hos standarden har detta inte lyckats. Denna studie har undersökt standarden och pekar på områden som man måste fokusera på när man utför tester mellan moduler. Dessutom föreslås flera tillägg till standarden för att möjliggöra bättre interaktion mellan basstationens moduler. Studien fokuserar på RP3- gränssnittet med målet att möjliggöra standardiserad interaktion mellan basbands- och radio-moduler, så att dessa moduler kan kommerisialiseras. Det förväntade resultatet är lägre kostnader, bättre interaktion mellan moduler, snabbare marknadsintroduktion och mer samarbete inom forskning och utveckling.

The market penetration of mobile access devices with multiple network interfaces has increased dramatically over the last few years. As a consequence, the quest for a widespread multi-path transport protocol that takes advantage of all available interfaces simultaneously to increase data throughput and improve robustness, has received considerable attention. One prominent protocol introduced by the IETF is Multipath TCP (MPTCP). MPTCP is an extension to the predominant single-path transport protocol, the Transport Control Protocol (TCP) that enables multihomed devices to aggregate available resources transparently to the applications. Combining multiple radio access technologies, like LTE and Wi-Fi, with diverse characteristics in terms of transmission rates and fluctuations opens for novel challenges that may disrupt and even harm the data throughput. Therefore MPTCP must take path heterogeneity into account. For MPTCP to supersede single-path TCP it is required that MPTCP always achieve at least the throughput of the best individual TCP path. This thesis investigates if MPTCP with uncoupled congestion control fulfills this condition, and if so, how much it improves the throughput. By examining the protocol in a deterministic emulated environment defined by the characteristics of LTE, we conclude two key factors impacting the outcome: the download size and the difference in characteristics between the paths. Our experiments show that MPTCP overall fulfills this task, especially during path homogeneity with near aggregated results. But we also show that MPTCP may decrease data throughput with 16% compared to TCP during path heterogeneity. Hence MPTCP does not always fulfill the goal of throughput. We therefore conclude further intelligence is needed for the packet scheduling mechanism to avoid throughput degradation in the initial phase of a transmission.

In LTE networks, there are several properties that need to be carefully planned for thenetwork to be well performing. As the networks’ traffic increases and the networks aregetting denser, this planning gets even more important. The Physical Cell Id (PCI) is theidentifier of a network cell in the physical layer. This property is limited to 504 values, andtherefore needs to be reused in the network. If the PCI assignment is poorly planned, therisk for network conflicts is high. In this work, the aim is to develop a distributed approach where the planning is performedby the cells involved in the specific conflict. Initially, the PCI allocation problem isformulated mathematically and is proven to be NP-complete by a reduction to the vertexcolouring problem. Two optimisation models are developed which are minimising thenumber of PCI changes and the number of PCIs used within the network respectively. An approach is developed which enlargers the traditional decision basis for a distributedapproach by letting the confused cell request neighbour information from its confusioncausingneighbours. The approach is complemented with several decision rules for theconfused cell to be able to make an as good decision as possible and by that mimic the behaviourof the optimisation models. Three different algorithms are implemented using theapproach as a basis. For evaluation purpose, two additional algorithms are implemented,one which is applicable to today’s standard and one inspired by the work by Amirijoo et al. The algorithms were tested against three different test scenarios where the PCI rangewas narrowed, the number of cells was increased and the network was extended. Thealgorithms were also tested on a small world network. The testing showed promisingresults for the approach, especially for larger and denser networks.

L'objectif de cette thèse est de souligner l'importance de l'abstraction de la couche physique (PHY abstraction) dans l'évaluation des systèmes LTE (Long Term Evolution). Cette thèse propose une approche pragmatique pour l'utilisation de PHY abstraction dans les simulateurs des systèmes LTE. PHY abstraction est un outil très important pour l'évaluation des systèmes LTE à grande échelle car il est efficace, pratique et à complexité réduite . Dans cette thèse, nous prouvons que, à part son objectif principal et qui consiste à fournir un indicateur instantané de la qualité de liaison pour l'évaluation du système, le PHY abstraction peut aussi: améliorer le feedback de l'indicateur sur la qualité de canal (CQI) en se basant sur les différentes configurations d'antennes, et la prédiction de la performance des réseaux LTE en se basant sur des mesures de canal réelles. Cette thèse est principalement divisée en deux parties: méthodologies et applications. La première partie présente la conception complète et la méthodologie de validation des systèmes de captage PHY pour différentes configurations d'antennes correspondant à des différentes modes de transmissions en LTE. La validation est effectuée en utilisant des simulateurs de niveau de liaison. Nous soulignons aussi les astuces de calibrage nécessaires pour que la production PHY soit précise dans la prédiction de la performance de capacité réalisant turbo-codes. / The main focus of this thesis is to highlight the importance of PHY abstraction for the system level evaluations in the framework of 3GPP Long Term Evolution (LTE) networks. This thesis presents a pragmatic approach towards the use of PHY abstraction in LTE based system level simulators. PHY abstraction is an extremely valuable low complexity tool for efficient and realistic large scale system evaluations. This thesis shows that apart from the primary purpose of PHY abstraction of providing instantaneous link quality indicator for the purpose of system level evaluations, it can be further used for an improved channel quality indicator (CQI) feedback based on the different antenna configurations and for the performance prediction of LTE networks based on the real life channel measurements. This thesis is mainly divided into two parts; methodologies and applications. The first part presents the complete design and validation methodology of PHY abstraction schemes for various antennaconfigurations corresponding to different transmission modes in LTE. The validation is performed using link level simulators and it also highlights the calibration issues necessary for the PHY abstraction to be accurate in predicting the performance of capacity achieving turbo codes.

Le trafic mobile global atteindra 24,3 exa-octets en 2019. Accueillir cette croissance dans les réseaux d’accès radio devient un véritable casse-tête. Nous porterons donc toute notre attention sur l'une des solutions à ce problème : le délestage (offloading) grâce à des communications de dispositif à dispositif (D2D). Notre première contribution est DROiD, une stratégie qui exploite la disponibilité de l'infrastructure cellulaire comme un canal de retour afin de suivre l'évolution de la diffusion d’un contenu. DROiD s’adapte au rythme de la diffusion, permettant d'économiser une quantité élevée de données cellulaires, même dans le cas de contraintes de réception très serrées. Ensuite, nous mettons l'accent sur les gains que les communications D2D pourraient apporter si elles étaient couplées avec les transmissions multicast. Par l’utilisation équilibrée d'un mix de multicast, et de communications D2D, nous pouvons améliorer, à la fois, l'efficacité spectrale ainsi que la charge du réseau. Afin de permettre l’adaptation aux conditions réelles, nous élaborons une stratégie d'apprentissage basée sur l'algorithme dit ‘’bandit manchot’’ pour identifier la meilleure combinaison de communications multicast et D2D. Enfin, nous mettrons en avant des modèles de coûts pour les opérateurs, désireux de récompenser les utilisateurs qui coopèrent dans le délestage D2D. Nous proposons, pour cela, de séparer la notion de seeders (utilisateurs qui transportent contenu, mais ne le distribuent pas) et de forwarders (utilisateurs qui sont chargés de distribuer le contenu). Avec l'aide d’un outil analytique basée sur le principe maximal de Pontryagin, nous développons une stratégie optimale de délestage. / Mobile data traffic is expected to reach 24.3 exabytes by 2019. Accommodating this growth in a traditional way would require major investments in the radio access network. In this thesis, we turn our attention to an unconventional solution: mobile data offloading through device-to-device (D2D) communications. Our first contribution is DROiD, an offloading strategy that exploits the availability of the cellular infrastructure as a feedback channel. DROiD adapts the injection strategy to the pace of the dissemination, resulting at the same time reactive and relatively simple, allowing to save a relevant amount of data traffic even in the case of tight delivery delay constraints.Then, we shift the focus to the gains that D2D communications could bring if coupled with multicast wireless networks. We demonstrate that by employing a wise balance of multicast and D2D communications we can improve both the spectral efficiency and the load in cellular networks. In order to let the network adapt to current conditions, we devise a learning strategy based on the multi-armed bandit algorithm to identify the best mix of multicast and D2D communications. Finally, we investigate the cost models for operators wanting to reward users who cooperate in D2D offloading. We propose separating the notion of seeders (users that carry content but do not distribute it) and forwarders (users that are tasked to distribute content). With the aid of the analytic framework based on Pontryagin's Maximum Principle, we develop an optimal offloading strategy. Results provide us with an insight on the interactions between seeders, forwarders, and the evolution of data dissemination.

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In modern society, security has become an increasingly important subject, as technologyhas become an integrated part of everyday life. The security of a system can be tested withthe help of fuzzing, where incoming messages to the system are altered. In this thesis, afuzzer was developed targeting an E-UTRAN Node B (eNB) in the Long-Term Evolution(LTE) landscape. The eNB is current prototype and is from the company Ericsson. Thefuzzer is particularly designed for testing the Medium Access Control (MAC) layer of theeNB. The fuzzer uses a genetic method where all of the fuzzer’s flags (the R, F2, E, LCID, Fand L flags) are triggered during the fuzzing period. Depending on the output of the firstgeneration of fuzzed values, new values are generated either by choosing a value close tothe original value, or by choosing a value that belong to the same subgroup as the originalvalue. Four test cases are made, where first test case is the base line of the program and theother three test cases fuzzes the eNB, using different parts of the fuzzer. The results show that depending on which parts of the fuzzer are used, the connectionbecomes different. For test two and three, the connection became increasingly unstable andmore data was present in the connection. Test case four did not however deviate so muchfrom the baseline, if compared to test two and three.

In the era of Industry 4 and Digital Twin – DT- (integrating Audio-Video, Virtual Reality, Augmented Reality and Haptics - from the Greek word Haptikos meaning "able to touch") and the Tactile Internet (TI), it becomes obvious that telecom stakeholders need different networks requirements to provision high quality services with respect to the new standards. In reality, this era is proposed as TI, and it will achieve a true paradigm shift from content delivery to skill-set delivery network types, thanks to recent technical breakthroughs. It will build a new internet structure with improved capabilities; but it will be difficult to meet the technical needs of the TI with current fourth generation (4G) mobile communication systems. As a result, 5G mobile communication systems will be used at the wireless edge and as a key enabler for TI due to its automated core network functionalities. Because of the COVID-19 outbreak, most daily activities such as employment, research, and education are now conducted online rather than in person. As a result, internet traffic has risen dramatically. Nowadays, Tactile Internet is in its infancy deployment phase worldwide. For this reason, and because of the growing need of its applications, the feasibility of these applications on the existing and deployed networks infrastructures, especially in the growing countries, is thought to be very hard, even quasi-impossible. Since 5G is not reaching yet its convergence stage (i.e. it is not deployed everywhere) and there is a huge stress on mobile communications given that the world is still facing the COVID-19 Pandemic, and since all the activities are taking place online, we propose design and implement a QoS framework to facilitate the feasibility and the applicability of the TI systems, where no 5G infrastructure is deployed. This framework will predict the most suitable network type to be deployed for certain given TI applications with certain given KPIs (Key Performance Indicators). Also, this framework is scalable, in such it gives an idea of even the future Next Generation Mobile Networks types (NGMN, if necessary). “To deal” with TI applications, means “to deal” with Haptics added to Audio and Video streams. Therefore, performance evaluation for haptic networks is required. And since there are different types of haptic networks, so interoperability is needed. Consequently, a standardization form is necessary for that purpose, to annotate and describe the haptic network. The first idea that flashes in mind, is the use of Ontologies. In these latters, we can add intelligent rules to infer additional data and predict resource requirements in order to achieve better performance. Many works in the research rely on Artificial Intelligence approaches to tackle the above-mentioned standardization, but very few depend on ontologies, and without futuristic outcomes, especially for the optimization problem. We mean by optimization, the optimal types, methods and rules that are able to accommodate the applicability of the TI systems (here come the applications KPIs) in an acceptable environment or infrastructure (here come the networking KPIs), and even-more, to infer the most optimal network type. To help manufacturing companies take full advantage of the TI, we propose to develop new methods and tools (ontologies) to intelligently handle the TI, DT (Digital Twin) and IoT (Internet of Things) sensor data and process data at the edge of the network and deliver faster insights. The outcomes of these ontologies, have been validated through two conducted case studies, where we simulated, in the first, TI traffic over Wi-Fi, WiMAX and UMTS (3G) infrastructures; While in the second we used 4G (LTE-A), along with SDN (Software Defined Networking) integrated to MEC (Mobile Edge Computing) as networking backbone. The results, in terms of QoS KPIs performance evaluation, present high relevance to our proposed Ontology outcomes.