As a result of the constant efforts to improve mobile system performance and spectral efficiency, the 3GPP standardization forum is currently defining new architectural and functional requirements that hope to ensure long-term evolution (specifically defined as the “Long-Term Evolution (LTE) concept”) and general future competitiveness of the 2G and 3G radio access technologies. Previous discussions on LTE efficiency have been focused on general assumptions on signaling overhead and overall system capacity, based on experience from existing mobile systems. However, as 3GPP standardization has become more mature (although not yet settled), there is a need to investigate how different potential LTE services will be affected by the use of available overhead information and basic scheduling algorithms. This thesis investigates the lower protocol layers’ overhead impacts on the downlink for different packet switched services, in an LTE radio access network (RAN). Results show that the use of RTP/TCP/IP header compression (ROHC) is the single most important factor to reduce payload overhead, for packet sizes of ~1kB or smaller. However, for packets larger than ~1 kB, the use of ROHC becomes insignificant. Protocol headers – including the AMR frame header, RLC/MAC headers, and CRC where applicable – remain the largest part of payload overhead regardless of packet size and header compression (ROHC). For VoIP over the UDP protocol (with ROHC), RLC/MAC headers constitute the largest part of protocol headers. For TCP/IP applications (without ROHC), TCP/IP headers are predominant. Services that require packet sizes beyond ~1 kB will require about the same power per payload bit regardless of percentage of payload overhead. / Som ett resultat av ständiga ansträngningar att förbättra såväl prestanda som spektrumeffektivitet för mobila system, definierar 3GPPs standardiseringsforum nya krav på arkitektur och funktionalitet. Dessa är avsedda att säkerställa långsiktig utveckling (explicit definierat som konceptet “Long-Term Evolution (LTE)”, samt framtida konkurrenskraft för både 2G och 3G som radioaccess-teknologier. Tidigare diskussioner rörande effektivitet inom LTE har fokuserat på allmänna antaganden vad gäller kontrolldata för signallering och övergripande systemprestanda. Dessa har i sin tur baserats på erfarenheter från existerande mobilsystem. När standardiseringen inom 3GPP mognar uppstår nu ett behov av att undersöka hur olika tjänster inom LTE påverkas, av såväl hur man använder den kontrollinformation som finns tillgänglig, som av basala algoritmer for schemaläggning av resurser. Denna rapport undersöker påverkan från lägre protokoll-lagers kontrollinformation på nerlänken hos olika paket-kopplade tjänster inom ett radioaccessnät för LTE. Resultaten visar att användandet av ROHC (som packar kontrollinformation för protokollen RTP/TCP/IP), är det ensamt viktigaste bidraget till minskad kontrollinformation i relation till informationsbitar för paketstorlekar upp till c:a 1kB. För större paket är vinsten med ROHC dock försumbar. Kontrollinformation för protokoll – inkluderat data avsett för AMR-tal-ramen, RLC/MAC-protokollen, samt CRC – utgör för övrigt en stor del av kontrollinformationen relativt informationsbitar, oavsett paketstorlek och packning av kontrolldata. Tjänster som kräver paketstorlekar på över c:a 1 kB kräver uppskattningsvis samma mängd energi per informationsbit, oavsett andelen kontrollinformation.

Le secteur des télécommunications mobiles a connu une croissance très rapide dans un passé récent avec pour résultat d'importantes évolutions technologiques et architecturales des réseaux sans fil. L'expansion et l'hétérogénéité de ces réseaux ont engendré des coûts de fonctionnement de plus en plus importants. Les dysfonctionnements typiques de ces réseaux ont souvent pour origines des pannes d'équipements ainsi que de mauvaises planifications et/ou configurations. Dans ce contexte, le dépannage automatisé des réseaux sans fil peut s'avérer d'une importance particulière visant à réduire les coûts opérationnels et à fournir une bonne qualité de service aux utilisateurs. Le dépannage automatisé des pannes survenant sur les réseaux sans fil peuvent ainsi conduire à une réduction du temps d'interruption de service pour les clients, permettant ainsi d'éviter l'orientation de ces derniers vers les opérateurs concurrents. Le RAN (Radio Access Network) d'un réseau sans fil constitue sa plus grande partie. Par conséquent, le dépannage automatisé des réseaux d'accès radio des réseaux sans fil est très important. Ce dépannage comprend la détection des dysfonctionnements, l'identification des causes des pannes (diagnostic) et la proposition d'actions correctives (déploiement de la solution). Tout d'abord, dans cette thèse, les travaux antérieurs liés au dépannage automatisé des réseaux sans-fil ont été explorés. Il s'avère que la détection et le diagnostic des incidents impactant les réseaux sans-fil ont déjà bien été étudiés dans les productions scientifiques traitant de ces sujets. Mais étonnamment, aucune référence significative sur des travaux de recherche liés aux résolutions automatisées des pannes des réseaux sans fil n'a été rapportée. Ainsi, l'objectif de cette thèse est de présenter mes travaux de recherche sur la " résolution automatisée des dysfonctionnements des réseaux sans fil LTE (Long Term Evolution) à partir d'une approche statistique ". Les dysfonctionnements liés aux paramètres RRM (Radio Resource Management) seront particulièrement étudiés. Cette thèse décrit l'utilisation des données statistiques pour l'automatisation du processus de résolution des problèmes survenant sur les réseaux sans fil. Dans ce but, l'efficacité de l'approche statistique destinée à l'automatisation de la résolution des incidents liés aux paramètres RRM a été étudiée. Ce résultat est obtenu par la modélisation des relations fonctionnelles existantes entre les paramètres RRM et les indicateurs de performance ou KPI (Key Performance Indicator). Une architecture générique automatisée pour RRM 8 a été proposée. Cette dernière a été utilisée afin d'étudier l'utilisation de l'approche statistique dans le paramétrage automatique et le suivi des performances des réseaux sans fil. L'utilisation de l'approche statistique dans la résolution automatique des dysfonctionnements des réseaux sans fil présente deux contraintes majeures. Premièrement, les mesures de KPI obtenues à partir du réseau peuvent contenir des erreurs qui peuvent partiellement masquer le comportement réel des indicateurs de performance. Deuxièmement, ces algorithmes automatisés sont itératifs. Ainsi, après chaque itération, la performance du réseau est généralement évaluée sur la durée d'une journée avec les nouveaux paramètres réseau implémentés. Les algorithmes itératifs devraient donc atteindre leurs objectifs de qualité de service dans un nombre minimum d'itérations. La méthodologie automatisée de diagnostic et de résolution développée dans cette thèse, basée sur la modélisation statistique, prend en compte ces deux difficultés. Ces algorithmes de la résolution automatisé nécessitent peu de calculs et convergent vers un petit nombre d'itérations ce qui permet leur implémentation à l'OMC (Operation and Maintenace Center). La méthodologie a été appliquée à des cas pratiques sur réseau LTE dans le but de résoudre des problématiques liées à la mobilité et aux interférences. Il est ainsi apparu que l'objectif de correction de ces dysfonctionnements a été atteint au bout d'un petit nombre d'itérations. Un processus de résolution automatisé utilisant l'optimisation séquentielle des paramètres d'atténuation des interférences et de packet scheduling a également été étudié. L'incorporation de la "connaissance a priori" dans le processus de résolution automatisé réduit d'avantage le nombre d'itérations nécessaires à l'automatisation du processus. En outre, le processus automatisé de résolution devient plus robuste, et donc, plus simple et plus pratique à mettre en œuvre dans les réseaux sans fil. / The mobile telecommunication industry has experienced a very rapid growth in the recent past. This has resulted in significant technological and architectural evolution in the wireless networks. The expansion and the heterogenity of these networks have made their operational cost more and more important. Typical faults in these networks may be related to equipment breakdown and inappropriate planning and configuration. In this context, automated troubleshooting in wireless networks receives a growing importance, aiming at reducing the operational cost and providing high-quality services for the end-users. Automated troubleshooting can reduce service breakdown time for the clients, resulting in the decrease in client switchover to competing network operators. The Radio Access Network (RAN) of a wireless network constitutes its biggest part. Hence, the automated troubleshooting of RAN of the wireless networks is very important. The troubleshooting comprises the isolation of the faulty cells (fault detection), identifying the causes of the fault (fault diagnosis) and the proposal and deployement of the healing action (solution deployement). First of all, in this thesis, the previous work related to the troubleshooting of the wireless networks has been explored. It turns out that the fault detection and the diagnosis of wireless networks have been well studied in the scientific literature. Surprisingly, no significant references for the research work related to the automated healing of wireless networks have been reported. Thus, the aim of this thesis is to describe my research advances on "Automated healing of LTE wireless networks using statistical learning". We focus on the faults related to Radio Resource Management (RRM) parameters. This thesis explores the use of statistical learning for the automated healing process. In this context, the effectiveness of statistical learning for automated RRM has been investigated. This is achieved by modeling the functional relationships between the RRM parameters and Key Performance Indicators (KPIs). A generic automated RRM architecture has been proposed. This generic architecture has been used to study the application of statistical learning approach to auto-tuning and performance monitoring of the wireless networks. The use of statistical learning in the automated healing of wireless networks introduces two important diculties: Firstly, the KPI measurements obtained from the network are noisy, hence this noise can partially mask the actual behaviour of KPIs. Secondly, these automated healing algorithms are iterative. After each iteration the network performance is typically evaluated over the duration of a day with new network parameter settings. Hence, the iterative algorithms should achieve their QoS objective in a minimum number of iterations. Automated healing methodology developped in this thesis, based on statistical modeling, addresses these two issues. The automated healing algorithms developped are computationaly light and converge in a few number of iterations. This enables the implemenation of these algorithms in the Operation and Maintenance Center (OMC) in the off-line mode. The automated healing methodolgy has been applied to 3G Long Term Evolution (LTE) use cases for healing the mobility and intereference mitigation parameter settings. It has been observed that our healing objective is achieved in a few number of iterations. An automated healing process using the sequential optimization of interference mitigation and packet scheduling parameters has also been investigated. The incorporation of the a priori knowledge into the automated healing process, further reduces the number of iterations required for automated healing. Furthermore, the automated healing process becomes more robust, hence, more feasible and practical for the implementation in the wireless networks.

As early as 2014, mobile network operators' spectral capacity will be overwhelmed by the demand brought on by new devices and applications. To augment capacity and meet this demand, operators may choose to deploy a Dynamic Spectrum Access (DSA) overlay. Spectrum regulation is following suit, with regulators attempting to incorporate spectrum sharing through the design of spectrum access rules that support DSA. This dissertation explores the idea of DSA applied to Long Term Evolution Advanced (LTE+) networks. This idea is explored under functional, architectural, and spectrum policy aspects. Under the functional and architectural aspects of this topic, the signaling and functionality required by such an overlay have not yet been fully considered in the architecture of an LTE+. This dissertation presents a Spectrum Accountability framework to be integrated into LTE+ MacroNet and HetNet architectures, defining specific element functionality, protocol interfaces, and signaling flow diagrams required to enforce the rights and responsibilities of primary and secondary users. We also identify and propose three DSA management frameworks for LTE+ HetNets: Spectrum Accountability Client Only, Cell Spectrum Management, and Domain Spectrum Management. Our Spectrum Accountability framework may serve as a guide in the development of future LTE+ network standards that account for DSA. We also quantify, through simulation and integer programs, the benefits of using DSA channels to augment capacity under a scenario in which LTE+ network can opportunistically use TV and GSM spectrum. In our first experiment, we a consider a scenario where three different operators share the same cell site with LTE+ equipment and a Dynamic Spectrum Access (DSA) band to augment spectral capacity. Our experiments show that throughput can increase by as much as 40%. We develop integer programs to model the assignment of spectrum channels to both a MacroNet and HetNet. In our selected scenario, we observe TV white spectrum provides the largest gain in performance for both Nets: 27% for MacroNet and 9% increase for the HetNet over our measured ranges. Although the gains in using opportunistic use of GSM is more modest, 10% and 2% for the Macro and HetNet, respectively, we believe that these gains will significantly increase as operators continue to migrate users to LTE+, thus freeing up portions of the bands currently used for GSM service. In our final analytical model, we create integer program sets to represent the different three DSA management frameworks for LTE+ HetNets and compare their results. Under the spectrum policy aspects, this dissertation develops a decision-theoretic framework for regulators to assess the impacts of different spectrum access rules on both primary and secondary operators. We analyze access rules based on sensing and exclusion areas, which in practice can be enforced through geolocation databases. Our results show that receiver-only sensing provides insufficient protection for primary and co-existing secondary users and overall low social welfare. On the other hand, combining sensing information of only the transmitter and receiver of a communication link provides dramatic increases in system performance. The performance of using these link end points is relatively close to that of using many cooperative sensing nodes associated to the same access point and large link exclusion areas. We hope these results will prove useful to regulators and network developers in un and developing rules for future DSA regulation. / Ph. D.

Le problème de coloration de graphe est un problème NP-complet particulièrement étudié, qui permet de modéliser de problèmes dans des domaines variés. Dans cette thèse, de nouveaux algorithmes exacts basés sur une étude de la structure du graphe sont proposés. Ce travail s'appuie sur l'algorithme « Total solutions Exact graph Coloring » (TexaCol) qui construit toutes les solutions en exploitant l'ensemble des cliques d'un graphe. Deux algorithmes exacts, « Partial best solutions Exact graph Coloring » (PexaCol) et « All best solutions Exact graph Coloring » (AexaCol), sont présentés ici pour construire certaines solutions optimales ou toutes les meilleures solutions. Ces deux algorithmes utilisent la méthode de backtracking, dans laquelle ils ne choisissent que les sous-ensembles de meilleurs solutions pour continuer la coloration. L’analyse de résultat montre que PexaCol et AexaCol sont capables de traiter des graphes plus grands que TexaCol. Mais surtout, AexaCol trouve toutes les meilleures solutions significativement plus vite que TexaCol ainsi que le solveur Gurobi, qui sont utilisés comme référence.La téléphonie mobile est un domaine en plein essor qui peut s'appuyer sur une modélisation à base de graphes. Actuellement, les techniques de type « Device-to-Device » (D2D) prennent une place importante dans les réseaux mobiles. L’allocation de ressource constitue l'un des principaux problèmes en matière de performance. Pour assigner efficacement une ressource radio à une paire D2D dans le système Long-Term Evolution (LTE), un schéma systématique d'allocation de ressources est proposé dans cette thèse. Il est basé sur une clusturisation des liens D2D, et permet de prendre en compte à la fois l'allocation inter-cluster et intra-cluster des ressources. En déterminant les zones d'interférence, le problème d'allocation des ressources inter-cluster est formulé comme un problème de coloration de graphe dynamique. Un algorithme de coloration de graphe dynamique est ainsi proposé, basé sur PexaCol. Cet algorithme peut assigner les ressources radio aux clusters qui sont générés ou supprimés dynamiquement. L’analyse numérique montre que cet algorithme assure une bonne performance en termes d'utilisation des ressources, de temps d’exécution et d'adaptabilité. Concernant le problème d’allocation de ressources inter-cluster, une méthode fondée sur la topologie est proposée, intégrant naturellement l'allocation de puissance et l’allocation de Resource Block (RB). Pour simplifier ce problème d'allocation de ressources, la meilleure topologie est choisie à chaque étape, celle qui permet d'obtenir le meilleur débit en utilisant le moins de RBs. A partir de ce procédé, quatre algorithmes d'optimisation sont proposés: l’algorithme glouton statique, PexaCol statique, PexaCol dynamique et PexaCol dynamique approximatif. L'analyse des résultats montre que pour les petits clusters, les versions statiques et dynamiques de PexaCol permettent d'obtenir un index d’optimisation maximal en choisissant la meilleure topologie locale pour chaque noeud. A l'opposé, les algorithmes "glouton statique" et "PexaCol dynamique approximatif" permettent d'obtenir une solution sous-optimale pour l'optimisation locale avec une complexité moindre. Pour les grands clusters, avec certaine séquence de la coloration, le PexaCol dynamique approximatif est mieux que l’algorithme glouton statique pour l’index d’optimisation pendant un temps d’exécution acceptable. / Graph coloring problem is a famous NP-complete problem, which has extensive applications. In the thesis, new exact graph coloring algorithms are researched from a graph structure point of view. Based on Total solutions Exact graph Coloring algorithm (TexaCol) which is capable of getting all coloring solution subsets for each subgraph, two other exact algorithms, Partial best solutions Exact graph Coloring algorithm (PexaCol) and All best solutions Exact graph Coloring algorithm (AexaCol), are presented to get multiple best solutions. These two algorithms utilize the backtracking method, in which they only choose the best solution subset each step to continue the coloring until partial or all best solutions are obtained. The result analysis shows that PexaCol and AexaCol can deal with larger graphs than TexaCol and especially, AexaCol runs much faster than TexaCol and the solver Gurobi to get all best solutions.Device-to-Device (D2D) is a promising technique for the future mobile networks, such as 5th generation wireless systems (5G), and the resource allocation is one of the most crucial problems for its performance. In order to efficiently allocate radio resource for D2D links in Long-Term Evolution (LTE) system, a systematic resource allocation scheme is proposed based on D2D clusters, including the inter-cluster resource allocation and the intra-cluster resource allocation. With the cluster interference range, the inter-cluster resource allocation problem is formulated as a dynamic graph coloring problem, and a dynamic graph coloring algorithm is designed based on PexaCol. This algorithm is able to allocate radio resource to clusters while they are dynamically generated and deleted. The numerical analysis results show that this algorithm has good performance in resource utilization, runtime and scalability.For the intra-cluster resource allocation problem, a topology-based resource allocation method is designed naturally combining power allocation with Resource Block (RB) allocation. To simplify this associated optimization problem, a local optimal method is proposed, in which the best topology is chosen each step achieving the maximal throughput with the minimum number of assigned RBs. With respect to this method, four algorithms are presented: static greedy, static PexaCol, dynamic PexaCol and dynamic PexaCol approximate. Result analysis shows that for small-scale clusters, static PexaCol and dynamic PexaCol are capable of getting a maximal optimization index by locally choosing the best topology for each node while static greedy and dynamic PexaCol approximate are able to get the suboptimal solution for the local optimization with much lower complexity. For large-scale clusters, giving certain treating sequences, the dynamic PexaCol approximate performs better than static greedy regarding the optimization index within an acceptable runtime.

Submitted by Automação e Estatística (sst@bczm.ufrn.br) on 2018-04-11T20:06:38Z No. of bitstreams: 1 BrunoJacomeCavalcanti_TESE.pdf: 5397909 bytes, checksum: 5a245eec570a69adf8ca5d791aaddf70 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-04-16T20:46:19Z (GMT) No. of bitstreams: 1 BrunoJacomeCavalcanti_TESE.pdf: 5397909 bytes, checksum: 5a245eec570a69adf8ca5d791aaddf70 (MD5) / Made available in DSpace on 2018-04-16T20:46:19Z (GMT). No. of bitstreams: 1 BrunoJacomeCavalcanti_TESE.pdf: 5397909 bytes, checksum: 5a245eec570a69adf8ca5d791aaddf70 (MD5) Previous issue date: 2017-10-20 / A perfeita funcionalidade dos sistemas de comunicações de 3ª. e 4ª. gerações requerem, entre outras coisas, do conhecimento dos valores numéricos da predição das perdas de propagação dos sinais propagantes nos ambientes urbano, suburbano e rural. Portanto, o estudo das condições de propagação em um ambiente qualquer sempre será uma preocupação dos engenheiros projetistas. A análise e desenvolvimento de modelos robustos de predição de perdas de propagação em redes de comunicações Long Term Evolution (LTE) e Long Term Evolution Advanced (LTE-A) usando técnicas de Inteligência Artificial são realizadas neste trabalho. Os procedimentos metodológicos empregados foram aplicados no melhoramento da predição dos modelos de perda de propagação empíricos SUI, ECC-33, Ericsson 9999, TR 36.942 e o modelo do Espaço Livre, aplicados em redes LTE e LTE-A nas frequências de 800 MHz, 1800 MHz e 2600 MHz, para ambientes suburbanos em cidades de porte médio do nordeste do Brasil. Assim, nesta tese propõem-se dois modelos de Redes Neurais Artificiais (RNA): (i) o modelo de rede neural com entradas baseadas em erro (RNBE), utilizando como principal alimentador da rede o erro entre dados medidos e simulados, e, (ii) o modelo de rede neural com entradas baseadas no terreno (RNBT). O desempenho desses modelos foram comparados com os modelos de propagação considerados no trabalho e também as versões otimizadas utilizando Algoritmos Genéticos (AG) e o Método dos Mínimos Quadrados (LMS). Também foram realizadas comparações com valores medidos, obtidos a partir de uma campanha de medição realizada na cidade de Natal, Estado do Rio Grande do Norte. Os resultados finais obtidos através de simulações e medições apresentaram boas concordâncias métricas, com destaque para a performance do modelo RNBE. A principal contribuição dessa tese é que, ao utilizar essas técnicas que fazem uso de maneira mais eficiente dos modelos de propagação empíricos, pode-se estimar sinais propagantes realistas, evitando erros no planejamento e implementações de redes sem fio LTE e LTE-A em áreas suburbanas. / The perfect functionality of the 3rd and 4th generation of wireless systems requires, among other parameters, knowledge of the numerical values of the prediction of loss of propagation of propagation signals in urban, suburban and rural environments. Therefore, the study of propagation conditions in any environment will always be a concern of design engineers. The analysis and development of robust propagation loss prediction models in Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A) communications networks using Artificial Intelligence techniques is performed in this work. The methodologies used were applied to improve the prediction of loss of empirical propagation SUI, ECC-33, Ericsson 9999, TR 36.942 models and the Free Space model applied in LTE and LTE-A networks in the frequencies of 800 MHz, 1800 MHz and 2600 MHz, for suburban environments in mid-sized cities in northeastern Brazil. Thus, in these thesis two models of Artificial Neural Networks (RNA) are proposed: (i) the neural network model with inputs based on error (RNBE) using as main feeder of the network the error between measured and simulated data, and (ii) the neural network model with land-based inputs (RNBT). The performance of these models was compared with the models of propagation considered in the work and also the versions optimized using Genetic Algorithms (AG) and the Least Square Method (LMS). Comparisons were also made with measured values, obtained from a measurement campaign carried out in the city of Natal, state of Rio Grande do Norte. The final results obtained through simulations and measurements presented good metric concordances, with emphasis on the performance of the RNBE model. Thus, the main contribution of this thesis is that, by using these techniques that make more efficient use of empirical propagation models, we can estimate realistic propagation signals, avoiding errors in the planning and implementations of LTE and LTE- A wireless networks in suburban areas.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-08-27T11:17:25Z No. of bitstreams: 2 Dissertação - Dalton Foltran de Souza - 2018.pdf: 3869661 bytes, checksum: 5fa93e5e35c983cbefa148826a07a3ef (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-08-27T11:20:32Z (GMT) No. of bitstreams: 2 Dissertação - Dalton Foltran de Souza - 2018.pdf: 3869661 bytes, checksum: 5fa93e5e35c983cbefa148826a07a3ef (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-08-27T11:20:32Z (GMT). No. of bitstreams: 2 Dissertação - Dalton Foltran de Souza - 2018.pdf: 3869661 bytes, checksum: 5fa93e5e35c983cbefa148826a07a3ef (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-07-04 / With the development of the next generation of mobile communications systems for 5G, several technologies are being studied aiming to reach the new requirements in new application scenarios. Among them, is the use of new modulations with higher spectral efficiency in substitution of OFDM, such as F-OFDM and UFMC, and also the scheduling algorithms which are in charge of sharing resources between users. In this work, we evaluated the application of F-OFDM and UFMC, 5G modulations candidates, on downlink LTE compared with OFDM and evaluated the schedulers Round Robin, QoS Guaranteed and PSO dealing with additional resources provided by the tested modulations. For that, we compared performance considering parameters like fairness, latency, throughput and spectral efficiency. The results showed that the downlink LTE improved performance in all evaluated parameters with UFMC modulation. In fact, there were a performance improvement in all schedulers evaluated. For example, PSO based scheduler improved latency and throughput while QoS Guaranteed reached the lowest loss, as the highest fairness were reached by QoS Guaranteed and Round Robin. Also, we propose a scheduling algorithm that takes into account the queue size in the user buffer and channel quality to maximize throughput and fairness in the LTE downlink network. The metrics evaluated were transmission efficiency, throughput, fairness, delay and losses. The proposed algorithm achieved better results for all evaluated metrics. / Com o desenvolvimento da próxima geração dos sistemas de comunicação móvel sem fio (5G) diversas tecnologias estão sendo estudadas com o objetivo de se atender aos novos requisitos de desempenho em diferentes cenários de aplicação. Dentre elas, está a utilização de modulações com maior eficiência espectral em substituição à OFDM, como F-OFDM e UFMC, como também os algoritmos de escalonamento que são responsáveis pelo compartilhamento dos recursos aos usuários. Neste trabalho, avaliamos a aplicação no downlink LTE das modulações F-OFDM e UFMC, candidatas ao 5G, comparadas a OFDM e avaliamos os escalonadores Round Robin, QoS Garantido e PSO ao lidar com recursos adicionais disponíveis proporcionados pelas modulações estudadas. Para tal, realizamos a análise de parâmetros de desempenho de tráfego, tais como vazão, índice de justiça, perda de dados e retardo médio. Os resultados mostraram que o enlace de descida do LTE apresentou melhor desempenho para todos os parâmetros analisados com a modulação UFMC. De fato, foram obtidas melhorias de desempenho para todos escalonadores avaliados. Como exemplo, o escalonador baseado em PSO apresentou melhorias no retardo e vazão, enquanto o escalonador QoS Garantido obteve menor taxa de perda de dados, sendo que índices de justiça mais elevados foram obtidos para os escalonadores QoS Garantido e Round Robin. Ainda, propusemos um escalonador que considera o tamanho da fila no buffer e a qualidade de canal visando maximizar a vazão e o índice de justiça no downlink da rede LTE. As métricas avaliadas foram eficiência de transmissão, vazão, índice de justiça, retardo e perda de dados. O algoritmo proposto alcançou melhores resultados em todas as métricas avaliadas em relação aos outros algoritmos considerados.

Long-Term Evolution (LTE) is the latest development in wide area cellular mobile network technology. In contrast with the earlier generations of circuit-switched mobile networks, LTE is all-IP packet-switched network. Both voice and data are sent inside IP packets. Voice over IP (VoIP) is used to provide voice service to LTE users. The speech frames are encapsulated into real-time protocol (RTP) packets and sent over the network. The underlying UDP and IP layers prepend their headers to this small RTP packet resulting in a relatively high overhead. The small size of the RTP packets containing voice/audio leads to an overhead problem as the protocol overhead is in addition to the large LTE frame overhead, thus wasting network resources. This master’s thesis project proposes to multiplex RTP and data packets at the user’s device as a solution to reduce the overhead. Moreover, the capability of modern user devices to switch between several interfaces (such as LTE and WLAN), is taken into account and the multiplexing of multiple traffic flows or a single traffic flow are studied in the case of a vertical handover. Performance and cost metrics are used to evaluate different potential demultiplexing points, and then the best possible demultiplexing point is identified. The results of this evaluation show that several demultiplexing points can be used based on the operator’s needs. The increased packet payload size increases the energy efficiency of LTE and may avoid the need of the UE to switch to WLAN to save power. In addition, to ensure high quality of service for VoIP traffic, the simultaneous use of multiple interfaces is efficient if the multiplexer is enabled. The multiplexing solution proposed by this thesis is also fully compatible with any virtual private network encapsulation protocol. / Long-Term Evolution (LTE) är den senaste tekniken inom mobil långdistanskommunikation. Jämfört med tidigare generationer av kretskopplade mobila nätverk, är LTE IP paketförmedlande nätverk. Både röstsamtal och datapaket skickas enkapsulerade i IP paket. Voice over IP (VoIP) används för att transportera röstsamtal över IP nätverket. Röstsekvenser enkapsuleras i Real Time Protocol (RTP) paket och skickas över nätverket. De underliggande lagerna som UDP och IP infogar sin huvudinformation i de små RTP paketen vilket gör att kommunikationen blir ooptimerad. De små RTP paketen som innehåller ljudinformation leder till att det blir ooptimerat tillsammans med LTE i och med att man lägger på huvudinformation för varje lager. I det här examensarbetet förslår vi att multiplexa RTP och datapaket tillsammans direkt i användarens enhet för att minska huvudinformationen. Dessutom diskuterar vi möjligheten att byta mellan olika kopplingar (som LTE och WLAN) samt att multiplexa flerfaldig eller singel trafik under en vertikal överlämning. Prestanda och kostnadsmätningar används för att evaluera olika potentiella sammankopplingspunkter, för att kunna ta reda på den bästa sammankopplingspunkten.  Resultatet av detta examensarbete visar på att flera sammankopplingspunkter kan användas beroende på operatörens behov. Den ökade storleken på nyttolasten ökar effektiviteten av LTE nätverken och minskar risken för att behöva byta UE:n till WLAN för att spara energi.  Utöver det ovannämnda kan simultan användning av olika kopplingar användas för att öka kvaliteten på VoIP trafik. Multplexlösningen som föreslås i det här examensarbete är dessutom fullt kompatibel med virtuella privata nätverksenkapsulerande protokoll.

This thesis proposes four novel techniques to solve the problem of growing energy consumption requirements in cellular communication networks. The first and second part of this work propose a novel energy efficient scheduling mechanism and two new bandwidth management techniques, while the third part provides an algorithm to actively manage the power state of base stations (BSs) so that energy consumption is minimized throughout the day while users suffer a minimal loss in achieved data rate performance within the system. The proposed energy efficient score based scheduler (EESBS) is based on the already existing principle of score based resource allocation. Resource blocks (RBs) are given scores based on their energy efficiency for every user and then their allocation is decided based on a comparison between the scores of the different users on each RB. Two additional techniques are introduced that allow the scheduler to manage the user’s bandwidth footprint or in other words the number of RBs allocated. The first one, bandwidth expansion mode (BEM), allows users to expand their bandwidth footprint while retaining their overall transmission data rate. This allows the system to save energy due to the fact that data rate scales linearly with bandwidth and only logarithmically with transmission power. The second technique, time compression mode (TCoM), is targeted at users whose energy consumption is dominated by signalling overhead transmissions. If the assumption is made that the overhead is proportional to the number of RBs allocated, then users who find themselves having low data rate demands can release some of their allocated RBs by using a higher order modulation on the remaining ones and thus reduce their overall energy expenditure. Moreover, a system that combines all of the aforementioned scheduling techniques is also discussed. Both theoretical and simulation results on the performance of the described systems are provided. The energy efficient hardware state control (EESC) algorithm works by first collecting statistical information about the loading of each BS during the day that is due to the particular mobility patterns of users. It then uses that information to allow the BSs to turn off for parts of the day when the expected load is low and they can offload their current users to nearby cell sites. Simplified theoretical, along with complete system computer simulation, results are included. All the algorithms presented are very straightforward to implement and are not computationally intensive. They provide significant energy consumption reductions at none to minimal cost in terms of experienced user data rate.

M.Ing. / The increase of interest in the development of radio communications, both terrestrial and satellite is reaching far and beyond the most optimistic expectations. There has been an accelerated emergence of newer technologies, all claiming highly coveted radio frequency spectrum resources. With the push for the development of location based services, utilizing satellite com- communications for military purposes and later for civilian use; there has been a parallel development in terrestrial communications technology making it possible to implement cost efficient reliable user systems for voice and data services ...

Spectrum scarcity is one of the most important challenges in wireless communications networks due to the sky-rocketing growth of multimedia applications. As the latest member of the multiple access family, non-orthogonal multiple access (NOMA) has been recently proposed for 3GPP Long Term Evolution (LTE) and envisioned to be a key component of the 5th generation (5G) mobile networks for its potential ability on spectrum enhancement. The feature of NOMA is to serve multiple users at the same time/frequency/code, but with di erent power levels, which yields a signi cant spectral e ciency gain over conventional orthogonal multiple access (OMA). This thesis provides a systematic treatment of this newly emerging technology, from the basic principles of NOMA, to its combination with simultaneously information and wireless power transfer (SWIPT) technology, to apply in cognitive radio (CR) networks and Heterogeneous networks (HetNets), as well as enhancing the physical layer security and addressing the fairness issue. First, this thesis examines the application of SWIPT to NOMA networks with spatially randomly located users. A new cooperative SWIPT NOMA protocol is proposed, in which near NOMA users that are close to the source act as energy harvesting relays in the aid of far NOMA users. Three user selection schemes are proposed to investigate the e ect of locations on the performance. Besides the closed-form expressions in terms of outage probability and throughput, the diversity gain of the considered networks is determined. Second, when considering NOMA in CR networks, stochastic geometry tools are used to evaluate the outage performance of the considered network. New closed-form expressions are derived for the outage probability. Diversity order of NOMA users has been analyzed based on the derived outage probability, which reveals important design insights regarding the interplay between two power constraints scenarios. Third, a new promising transmission framework is proposed, in which massive multipleinput multiple-output (MIMO) is employed in macro cells and NOMA is adopted in small cells. For maximizing the biased average received power at mobile users, a massive MIMO and NOMA based user association scheme is developed. Analytical expressions for the spectrum e ciency of each tier are derived using stochastic geometry. It is con rmed that NOMA is capable of enhancing the spectrum e ciency of the network compared to the OMA based HetNets. Fourth, this thesis investigates the physical layer security of NOMA in large-scale networks with invoking stochastic geometry. Both single-antenna and multiple-antenna aided transmission scenarios are considered, where the base station (BS) communicates with randomly distributed NOMA users. In addition to the derived exact analytical expressions for each scenario, some important insights such as secrecy diversity order and large antenna array property are obtained by carrying the asymptotic analysis. Fifth and last, the fundamental issues of fairness surrounding the joint power allocation and dynamic user clustering are addressed in MIMO-NOMA systems in this thesis. A two-step optimization approach is proposed to solve the formulated problem. Three e cient suboptimal algorithms are proposed to reduce the computational complexity. To further improve the performance of the worst user in each cluster, power allocation coe cients are optimized by using bi-section search. Important insights are concluded from the generated simulate results.