Dans les systèmes de communications sans fil, la transmission de grandes quantités d'information et à faible coût énergétique sont les deux principales questions qui n'ont jamais cessé d'attirer l'attention de la communauté scientifique au cours de la dernière décennie. Récemment, il a été démontré que la communication coopérative est une technique intéressante notamment parce qu'elle permet d'exploiter la diversité spatiale dans le canal sans fil. Cette technique assure une communication robuste et fiable, une meilleure qualité de service (QoS) et rend le concept de coopération prometteur pour les futurs générations de systèmes cellulaires. Typiquement, les QoS sont le taux d'erreurs paquet, le débit et le délai. Ces métriques sont impactées par le délai, induit par les mécanismes de retransmission Hybrid-Automatic Repeat-Request (HARQ) inhérents à la réception d'un paquet erroné et qui a un retard sur la QoS demandée. En revanche, les mécanismes HARQ créent une diversité temporelle. Par conséquent, l'adoption conjointe de la communication coopérative et des protocoles HARQ pourrait s'avérer avantageux pour la conception de schémas cross-layer. Nous proposons tout d'abord une stratégie de maximisation de débit total dans un réseau cellulaire hétérogène. Nous introduisons un algorithme qui alloue la puissance optimale à la station de base (BS) et aux relais, qui à chaque utilisateur attribue de manière optimale les sous-porteuses et les relais. Nous calculons le débit maximal atteignable ainsi que le taux d'utilisateurs sans ressources dans le réseau lorsque le nombre d'utilisateurs actifs varie. Nous comparons les performances de notre algorithme à ceux de la littérature existante, et montrons qu'un gain significatif est atteint sur la capacité globale. Dans un second temps, nous analysons théoriquement le taux d'erreurs paquet, le délai ainsi que l'efficacité de débit des réseaux HARQ coopératifs, dans le canal à évanouissements par blocs. Dans le cas des canaux à évanouissement lents, le délai moyen du mécanisme HARQ n'est pas pertinent à cause de la non-ergodicité du processus. Ainsi, nous nous intéressons plutôt à la probabilité de coupure de délai en présence d'évanouissements lents. La probabilité de coupure de délai est de première importance pour les applications sensibles au délai. Nous proposons une forme analytique de la probabilité de coupure permettant de se passer de longues simulations. Dans la suite de notre travail, nous analysons théoriquement l'efficacité énergétique (bits/joule) dans les réseaux HARQ coopératifs. Nous résolvons ensuite un problème de minimisation de l'énergie dans les réseaux coopératifs en liaison descendante. Dans ce problème, chaque utilisateur possède une contrainte de délai moyen à satisfaire de telle sorte que la contrainte sur la puissance totale du système soit respectée. L'algorithme de minimisation permet d'attribuer à chaque utilisateur la station-relai optimale et sa puissance ainsi que la puissance optimale de la BS afin de satisfaire les contraintes de délai. Les simulations montrent qu'en termes de consommation d'énergie, les techniques assistées par relais prédominent nettement les transmissions directes, dans tout système limité en délai. En conclusion, les travaux proposés dans cette thèse peuvent promettre d'établir des règles fiables pour l'ingénierie et la conception des futures générations de systèmes cellulaires énergétiquement efficaces. / In wireless systems, transmitting large amounts of information with low energetic cost are two main issues that have never stopped drawing the attention of the scientific community during the past decade. Later, it has been shown that cooperative communication is an appealing technique that exploits spatial diversity in wireless channel. Therefore, this technique certainly promises a robust and reliable communications, higher quality-of-service (QoS) and makes the cooperation concept attractive for future cellular systems. Typically, the QoS requirements are the packet error rate, throughput and delay. These metrics are affected by the delay, where each erroneous packet is retransmitted several times according to Hybrid-Automatic Repeat-Request (HARQ) mechanism inducing a delay on the demanded QoS but a temporal diversity is created. Therefore, adopting jointly cooperative communications and HARQ mechanisms could be beneficial for designing cross-layer schemes. First, a new rate maximization strategy, under heterogeneous data rate constraints among users is proposed. We propose an algorithm that allocates the optimal power at the base station (BS) and relays, assigns subcarriers and selects relays. The achievable data rate is investigated as well as the average starvation rate in the network when the load, i.e. the number of active users in the network, is increasing. It showed a significant gain in terms of global capacity compared to literature. Second, in block fading channel, theoretical analyses of the packet error rate, delay and throughput efficiency in relayassisted HARQ networks are provided. In slow fading channels, the average delay of HARQ mechanisms w.r.t. the fading states is not relevant due to the non-ergodic process of the fading channel. The delay outage is hence invoked to deal with the slow fading channel and is defined as the probability that the average delay w.r.t. AWGN channel exceeds a predefined threshold. This criterion has never been studied in literature, although being of importance for delay sensitive applications in slow fading channels. Then, an analytical form of the delay outage probability is proposed which might be useful to avoid lengthy simulations. These analyses consider a finite packet length and a given modulation and coding scheme (MCS) which leads to study the performance of practical systems. Third, a theoretical analysis of the energy efficiency (bits/joule) in relay-assisted HARQ networks is provided. Based on this analysis, an energy minimization problem in multiuser relayassisted downlink cellular networks is investigated. Each user has an average delay constraint to be satisfied such that a total power constraint in the system is respected. The BS is assumed to have only knowledge about the average channel statistics but no instantaneous channel state information (CSI). Finally, an algorithm that jointly allocates the optimal power at BS, the relay stations and selects the optimal relay in order to satisfy the delay constrains of users is proposed. The simulations show the improvement in terms of energy consumption of relay-assisted techniques compared to nonaided transmission in delay-constrained systems. Hence, the work proposed in this thesis can give useful insights for engineering rules in the design of the next generation energyefficient cellular systems.

Fondés sur la technologie IP, les réseaux de nouvelle génération (NGN) doivent surmonter les principaux défauts inhérents à cette technologie, à savoir l’absence de la qualité de service (QoS), la sécurité et la gestion de mobilité. Afin de garantir une offre de service dans un réseau NGN, un protocole de négociation de niveau de service peut être utilisé. Cependant, la majorité des protocoles de négociation existants permettent l’établissement d’un niveau de service qui ne couvre que la QoS. Quant à la sécurité et la mobilité, elles ont été souvent exclues de ces négociations, et donc gérées d’une manière indépendante. Cependant, la sécurisation d’un service peut causer la dégradation de la QoS, et la mobilité de l’utilisateur peut modifier ses besoins. D’où, l’intérêt de gérer simultanément la QoS et la sécurité tout en prenant en considération la mobilité des utilisateurs. Dans ce contexte, nous proposons de développer un protocole de signalisation qui permet à des clients fixes ou mobiles de négocier, d’une manière dynamique, automatique et sécurisée, un niveau de service couvrant à la fois la QoS et la sécurité. Notre contribution est composée de trois parties. Dans un premier temps, nous nous basons sur un protocole de négociation de QoS, utilisant les services web, afin de permettre la négociation conjointe de la sécurité et de la QoS tout en tenant compte de l’impact de la sécurité sur la QoS. Par la suite, cette négociation est rendue automatique en la basant sur un profil utilisateur qui permet d’adapter le niveau de service au contexte de l’utilisateur. Ainsi, l’offre de service est plus dynamique et peut s’adapter aux changements de réseau d’accès suite à la mobilité de l’utilisateur. Nous proposons, finalement, de sécuriser le flux de négociation afin de pallier aux différents types d’attaques qui peuvent viser les messages de négociation échangés. / Based on the IP technology, the next generation network (NGN) must overcome the main drawbacks of this technology consisting in the lack of quality of service (QoS), security and mobility management. To ensure a service offer in an NGN, a protocol for negotiating service level can be used. However, most of the existing negotiation protocols allow the establishment of a service level which includes only QoS. As for security and mobility, they were often not covered by these negotiations, and therefore managed independently. However, securing a service can cause degradation of the QoS, and the mobility of a user can change the service needs in terms of QoS and security. Thus, we need to simultaneously manage QoS and security while taking into account user’s mobility. In this context, we propose to develop a signaling protocol that allows fixed and mobile users to negotiate a service level covering both QoS and security, in a dynamic, automatic and secure manner. Our contribution is achieved in three steps. Initially, we rely on a signaling protocol, which performs QoS negotiation using web services, to enable the negotiation of both security and QoS while taking into account the impact of security on QoS. Then, this negotiation is automated by basing it on a user profile. This allows adjusting the service level according to changes which can occur on the user context. Thus, the service offer is more dynamic and can be adapted to changes of access network resulting from the mobility of the user. Finally, we propose to secure the negotiation flows in order to prevent the different attacks that can target the exchanged messages during a negotiation process.

Mobile Ad hoc Networks (MANETs) are re-emerging as a popular networking facility for wireless device users. A growing number of diversified applications are now accessible via wireless devices. The different applications may have different Quality of Service (QoS) requirements, which may better be satisfied by using different routing methods or metric types. Existing ad hoc network routing solutions do not consider various application-level requirements when making a routing decision. They typically make routing decisions based upon limited information acquired at the network layer. Most of the existing routing protocols make use of a single routing metric. Using a single metric type and/or information, only acquired at the network layer may not be able to accommodate different QoS requirements, imposed by diversified user-level applications or application-level data types.The aim of this thesis is to design an efficient routing function for ad hoc networks while at the same time satisfying users‟ and/or applications‟ QoS and security requirements. To achieve this, the thesis investigates and specifies routing requirements that could best support application-level QoS and security requirements in MANETs. It also investigates and critically analyses the state of the art in MANET routing, and the mechanisms used for protecting the routing functions. To overcome the weaknesses and advance the state of the art in MANET routing, this thesis proposes two major solutions. The first solution is the Secure ETX (SETX) routing protocol. It is a secure routing solution that can provide routing functions efficiently in malicious MANET environment. The SETX protocol provides a security mechanism to counter black hole attacks in MANETs on the ETX metric acquisition process. Simulation studies have been carried out and discussed in the thesis. Simulation results show that the SETX protocol can provide a marked improvement in network performances in the presence of black hole attacks, and it can do so with a negligible level of additional overhead.The second solution is a novel routing decision making called the Flexible Routing Decision (FRD) framework. The FRD framework supports routing decision making by using multiple metric types (i.e. multi-criteria routing decision making) and uses a cross-layer approach to support application-level QoS requirements. This allows users to use different routing metrics types, making the most appropriate routing decision for a given application. To accommodate the diversified application-level QoS requirements, multiple routing metric types have been identified and interpreted in the FRD framework design. The FRD framework has overcome some weaknesses exhibited by existing single metric routing decision making, used in MANETs. The performance of a routing decision making of FRD is also evaluated using NS2 simulation package. Simulation results demonstrate that the FRD framework outperforms the existing routing decision making methods.

[pt] A crescente demanda por aplicações em tempo real tem aumentado a necessidade de fornecimento de QoS na Internet. A arquitetura de Serviços Diferenciados (DiffServ) é uma proposta apresentada pelo IETF para suprir a qualidade de serviço necessária. Resultados de pesquisas, mostram que os componentes da arquitetura DiffServ não distribuem de forma justa os recursos da rede. Este trabalho tem como objetivo propor um mecanismo de marcação de tráfego capaz de melhorar a justiça no compartilhamento da largura de faixa excedente entre agregados de tráfego. O algoritmo de marcação proposto é comparado com os marcadores trTCM, tswTCM e ItswTCM em relação a justiça em diferentes cenários de simulação. Os resultados mostram que o algoritmo proposto apresenta desempenho superior em uma rede com carga de utilização variando entre 20% e 60%. / [en] Recent demand for real time applications has given rise to a need for Quality of Service (QoS) in the Internet. Differentiated Services (DiffServ) is one of such efforts currently pursued by IETF. Previous researchers found unfairness in DiffServ networks. The objective of this work is to propose a new marker which achieves proportional fair sharing of excess bandwidth among aggregates. The proposed algorithm is compared with the following markers trTCM, tswTCM e ItswTCM. Results show that the proposed marker performs better than the other three schemes for network provision level between 20% and 60%.

Orientadores: Nelson Luis Saldanha da Fonseca, Juliana Freitag Borin / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-27T14:47:59Z (GMT). No. of bitstreams: 1 AstudilloTrujillo_CarlosAlberto_M.pdf: 2488879 bytes, checksum: 5004b31fcfcabbbf8528fe73f484da7d (MD5) Previous issue date: 2015 / Resumo: A crescente demanda por acesso banda larga móvel tem motivado a implantação da tecnologia long term evolution (LTE) pelas operadoras de redes móveis (MNOs), permitindo o fornecimento de novos serviços que demandam alta largura de banda e requisitos rigorosos de qualidade de serviço (QoS). Este aumento da demanda de banda passante leva à necessidade de um grande número de estações rádio base e ao aumento na quantidade de tráfego injetado no backhaul da rede móvel (MBH). Para lidar com os elevados custos do MBH, redes ópticas passivas (PONs) podem ser usadas para reduzir os custos do MBH usando sistemas fiber to anywhere (FTTx) já implantado bem como lidar com a crescente demanda por acesso banda larga à Internet por usuários móveis. Além disso, a estação rádio base LTE, também conhecida como evolved NodeB (eNB), pode ser integrada à unidade de rede óptica (ONU) das PONs em um dispositivo único, chamado ONU-eNB. A ONU-eNB compete pela largura de banda com outras ONUs em PONs, o que pode potencialmente prejudicar o fornecimento de QoS aos usuários móveis. Esta dissertação propõe um framework para provisão de QoS em redes móveis LTE que empregam backhaul baseado em redes ópticas passivas Ethernet (EPONs). Propõe também, um escalonador para redes LTE com o objetivo de prover requisitos de QoS e melhorar a vazão total. O framework introduz uma arquitetura funcional para o dispositivo integrado ONU-eNB, um esquema de mapeamento de QoS e um método para permitir que os escalonadores LTE atuais possam levar em conta informações disponíveis da rede de acesso móvel (LTE) bem com informações sobre a rede de backhaul (EPON), a fim de melhorar o desempenho total da rede, especialmente quando o enlace de backhaul está congestionado. Mostra-se como a implementação do framework proposto melhora a utilização da rede e a provisão de QoS em uma rede integrada, mesmo sob variação da carga de tráfego no backhaul e na rede LTE / Abstract: The increasing demand for mobile broadband access has motivated mobile network operators (MNOs) to deploy the long term evolution (LTE) technology, which allows the support of new services demanding large amount of bandwidth and strict QoS requirements. The growth of bandwidth demands will increase dramatically the number of base stations and the amount of traffic injected into the mobile backhaul (MBH) network. To cope with the high cost of MBH networks, passive optical networks (PONs) can be employed by using the already deployed fiber to anywhere (FTTx) systems. Moreover, the LTE base station, also known as evolved NodeB (eNB), can be integrated with the optical network unit (ONU) in a single device, called ONU-eNB, which competes for bandwidth with other ONUs in PONs. Such competition for bandwidth can jeopardize the support of mobile users¿ quality of service (QoS) requirements. This dissertation proposes a QoS provisioning framework for LTE mobile networks employing Ethernet PON (EPON)-based backhaul. It also introduces a novel LTE scheduler with the aim of supporting QoS requirements as well as high throughput. The framework includes a functional architecture for the ONU-eNB, a QoS mapping scheme and a method to allow current LTE schedulers to take into account both information available from the mobile access network (LTE) and information from the backhaul network (EPON) in order to improve the overall network performance, specially when the backhaul link is congested. It is shown how the proposed framework can improve network utilization and quality of service provisioning in an integrated network even under variations of traffic load in the backhaul and in the LTE networks / Mestrado / Ciência da Computação / Mestre em Ciência da Computação

A alta competitividade e os avanços tecnológicos propiciaram o surgimento de um novo modelo de terceirização de Tecnologia de Informação (TI), os Provedores de Serviços de Aplicativos (ASP - Application Service Providers). A proposta do modelo ASP é a comercialização de aplicativos de software como serviço. A satisfação dos clientes está diretamente relacionada à qualidade do serviço prestado. Para garantir que sejam fornecidos serviços com qualidade, é fundamental a adoção dos Acordos dos Níveis de Serviços (SLA - Service Levei Agreements) como mecanismo de controle. No entanto, são escassas as informações formalizadas que venham a contribuir com a especificação desses acordos. Propondo-se a contribuir com a compreensão de SLA para ASP, apresenta-se uma pesquisa exploratória do conceito de SLA para ASP, de modelos de qualidade e dos fatores de qualidade a serem considerados nos SLA para garantir a qualidade dos serviços prestados. / lhe current competitiveness of the global market and the continuous technological evolution pushed the risen of a new model of Information Technogy Outsourcing, the Application Service Providers (ASP). The ASP modelproposes the remote delivery of software as a service. Therefore, customers\' satisfaction is strictelly related to the quality of ser\\>ice delivered. It is highly recommended the adoption of Service Levei Agreement (SLA) as a control mechanism to assure such quality of service. However, there is a lack of formalized statements regarding the specification of these agreements. As a matter of contribution for the compreension of the SLA for ASP, this work introduces an exploratory research of the concep of SLA for ASP, and of the quality models and quality metrics to be considered by the SLA to assure the quality of the services provided.

Aplicações de sistemas computacionais emergentes atribuindo requisitos de resposta na forma de tempo de resposta requerem uma abordagem de sistemas de tempo real. Nesses sistemas, a qualidade de serviço é expressa como garantia das restrições temporais. Um amplo leque de técnicas para provisão de QoS encontram-se na literatura. Estas técnicas são baseadas tanto na diferenciação de serviço (QoS relativa), quanto na especificação de garantia de desempenho (QoS absoluta). Porém, a integração de QoS relativa e absoluta em nível de aplicação não tem sido tão explorada. Este trabalho realiza o estudo, a análise e a proposta de um método de escalonamento de tempo real em um ambiente simulado, baseado em contratos virtuais adaptativos e modelo re-alimentado. O objetivo é relaxar as restrições temporais dos usuários menos exigentes e priorizar usuários mais exigentes, sem degradar a qualidade do sistema como um todo. Para tanto, estratégias são exploradas em nível de escalonamento para o cumprimento dos contratos especificados por requisitos de tempo médio de resposta. Os resultados alcançados com o emprego do método proposto sinalizam uma melhoria em termos de qualidade de serviço relativa e absoluta e uma melhor satisfação dos usuários. Este trabalho também propõe uma extensão para os modelos convencionalmente estudados nesse contexto, ampliando a formulação original de duas classes para n classes de serviços / Emerging computer system application posing responsiveness requirement in the form of response time demand a real-time system approach. In these systems, the quality of service is expressed as guarantees on time constraints. A wide range of techniques for QoS provision is found in the literature. These techniques are based both on either service differentiation (relative QoS) or specification of performance guaranteeS (absolute QoS). However, integrated provision of both relative and absolute QoS at application level is not as well explored. This work conducts the study, analysis and proposal of a real time scheduling method in a simulated environment. This method is based on adaptive virtual contracts and feedback model. The goal is to relax the time constraints of less demanding users and prioritize the time constraints of most demanding users, without degrading the quality of the system as a whole. Strategies toward this goal are exploited in the system scheduling level and are aimed at the problem of fulfulling service-level agreements specifying average response times requirements. The results achieved with the proposed method indicate an improvement in relative and absolute QoS and a better user satisfaction. This work also proposes an extension to the conventional models studied in this context, extending the original formulation of two classes for n classes of services

Este projeto de doutorado tem como objetivo definir modelos de negócio para ambientes de computação em nuvem que consideram desempenho e segurança como atributos de qualidade de serviço durante a definição do contrato. Para isso, foi necessário quantificar o impacto causado no desempenho de um ambiente em nuvem quando diferentes mecanismos de segurança foram utilizados. Para a quantificação da sobrecarga foram utilizadas técnicas e metodologias disponíveis na literatura que visam garantir a integridade, disponibilidade e confidencialidade dos dados, abordando desafios que envolvem o acesso, armazenamento e manipulação de dados em serviços oferecidos por meio de máquinas virtuais. Experimentos executados possibilitaram analisar o comportamento das variáveis de resposta na utilização de cenários com diferentes mecanismos de segurança e cargas. Dessa forma, foi possível confrontar a sobrecarga imposta pelos mecanismos de segurança com a alteração da quantidade de recursos aplicada por um módulo proposto, chamado ReMM. De acordo com os resultados, o ReMM alterou a quantidade de recursos virtuais alocados utilizando dois algoritmos de escalabilidade, garantindo as exigências definidas no contrato de níveis de serviço. No entanto, a alteração dos recursos computacionais para contrapor a sobrecarga imposta pelos mecanismos de segurança impactou nos custos finais dos serviços. Dessa forma, a sobrecarga de segurança, desempenho e custo foram considerados na definição dos modelos de negócios em diferentes ambientes de computação em nuvem. / This PhD thesis has as main goal defining business models for cloud computing environments that consider performance and security as quality of service attributes during the service level agreement definition. For this, it was necessary quantifying the impact on the performance of a cloud environment in which different security mechanisms were applied. Techniques and methodologies available in the literature that aim ensuring the integrity, availability and confidentiality of data were used to quantify the overhead, addressing challenges related to access, storage and manipulation of data in services offered through virtual machines. Experiments were executed, in which the response variable behaviors were analyzed, using scenarios with different security mechanisms and workloads. In this way, it was possible to compare the overhead imposed by the security mechanisms with the changes in the quantity of resources applied by a module proposed, called ReMM. According to the results, the ReMM changed the amount of allocated virtual resources using two scalability algorithms, ensuring the requirements defined in service level agreement. However, the changes in the computational resources to face the overhead imposed by the security mechanisms influenced the final costs of the service. Therefore, security overhead, performance and cost were considered in the definition of business models in different cloud computing environments.

It has been aimed to understand the types of resistance that take accountants in the city of São José dos Campos to outsource or reject softwares of people administration in their companies or offices of accounting services. A questionnaire was applied to a random sample of 69 accountants. Analyses of contents and descriptive statistics were used for the interpretation of informerss speeches and of the relationships among some basic variousnesses. Among the meaningful results we can find:1=Majority of the informers belong to the male gender, is married and aged between 30 and 50 years; about school background, majority is graduated from Accounting Schools. 2- According to CRC classification, majority owns small or medium offices, only 8.8% of informers classify their companies as big offices. 3- Although a good part makes use of people administration softwares, 16.1% do not believe they are developed to improve their accounting services management and 28.9% have not seen any satisfactory result in using them in their companies.4- The resistances identified were: Lack of knowledge with specific tools for people and client administration, use of accounting packages by legal requirement for fiscal services, although there are resistances to administration tools specific for people administration. It has been concluded that the informers, rarely or sometimes suffer with the level of cultural resistance, making it difficult for organizational changes necessary to be adopted. / Objetivou-se compreender os tipos de resistências que levam os contabilistas, inscritos na SESCON no município de São José dos Campos, a secundarizarem ou rejeitarem os softwares de gestão de pessoas em suas empresas ou escritórios de serviços contábeis. Aplicou-se um questionário a uma amostra aleatória de 69 contabilistas. Análises de conteúdo e estatística descritiva foram utilizadas para a interpretação das falas dos informantes e das relações entre algumas variáveis básicas. Entre os resultados significativos encontram-se: (1) a maioria dos informantes pertence ao gênero masculino, é casada e encontra-se na faixa etária de 30 ao 50 anos; quanto à escolaridade, a maioria é graduada em Ciências Contábeis. (2) Segundo a classificação do CRC, a maioria possui pequenos escritórios ou escritórios de porte médio, apenas 8,8% dos informantes classificam sua empresa como grande escritório. (3) Embora boa parte faça uso dos softwares de gestão de pessoas, 16,1% não acreditam que eles sejam desenvolvidos para melhorar o gerenciamento das empresas contábeis e 28,9% não têm verificado qualquer resultado satisfatório no uso em sua própria empresa. (4) As resistências identificadas foram falta de conhecimento em ferramentas específicas para a gestão de clientes internos e o uso de pacotes contábeis, por exigência legal no que se refere aos serviços de notas fiscais, embora haja resistências às ferramentas administrativas, específicas para a gestão de pessoas. Conclui-se que os informantes, embora conheçam as ferramentas e as utilizem pouco ou às vezes, sofrem com o nível de resistência cultural, dificultando as mudanças organizacionais necessárias para que possam ser adotadas.

This thesis dissertation addresses the problem of energy constraints in ad hoc wireless networks. In this sort of networks nodes are generally powered by means of batteries, which involves significant limitations regarding the time of operation of devices. The nodes whose battery level describes important energy depletion represent potential elements for loss of connectivity, which results in an increase of packet loss rate. Therefore, the management of energy expenditure is one of the main research challenges to face in ad hoc networks, especially when developing applications in real scenarios. However, energy management is not a trivial task due to the inherent features of this kind of networks, such as the distributed operation as well as the access medium mechanism. In that sense, traditional solutions of energy optimization based on the definition of power-saving intervals (sleep mode) are not suitable considering the operational characteristics of an ad hoc network, due to the substantial deterioration of network connectivity. In addition, the exponential growth of applications focused on the transmission of multimedia contents (especially video) available on mobile devices involves specific quality of service levels. Consequently, the design of solutions for the optimization of energy resources should be carried out without degrading the Quality of Experience perceived by the users. The contributions of this thesis are focused, in the first place, on the analysis of those factors which generate an increase of the energy consumption in the wireless medium and are related to the principle of operation of the radio interface. In particular, the intense operation in reception mode on the interference areas, as a result of the overhearing effect, as well as the high number of transmission retries due to channel access contention, are defined as the main aspects that increase energy demand in the network. On the other hand, with the aim of optimizing energy resources in the nodes without causing damage on the Quality of Service, this thesis proposes meaningful improvements to the routing protocol by means of a cross-layer scheme. Specifically, the designed mechanism carries out an evaluation of both the energy capacity available in the nodes and the distribution of devices along the wireless medium. To that end, this proposal introduces a new metric in the routing computation process, called strategic value, which reports the importance of a node in the network in terms of connectivity (i.e. number of neighbor nodes). This scheme aims to reduce the energy expenditure caused by the overhearing effect along the areas with higher node density as well as to extend the lifetime for those nodes with higher number of neighbors which are strategic to preserve network connectivity. Additionally, considering the current pragmatic approach in ad hoc networks focused on the design of specific applications, the evaluation hereby presented has been performed by means of a simulation environment and also through the implementation of a testbed. Specifically, the operation of the proposed scheme has been analyzed on a set of ad hoc nodes which has been implemented through development platforms. Also, a software tool has been developed in order to control and configure the experiments. Results prove that the proposal allows to extend the lifetime of the network as well as to increase packet reception rate as a consequence of the prevention in the route breakages due to energy depletion. Finally, it is worth mentioning that the knowledge acquired by the design, configuration and analysis of experiments by means of hardware devices, has motivated the development of proposals and application studies of ad hoc networks in real environments, which represent an additional contribution of this thesis dissertation. / El presente trabajo de tesis doctoral aborda la problemática de las limitaciones de energía en redes inalámbricas ad hoc. En este tipo de redes, los nodos generalmente emplean baterías como fuente de alimentación, lo que limita de forma dramática la autonomía de funcionamiento. Los nodos con mayor agotamiento de energía constituyen potenciales elementos para la pérdida de conectividad parcial o total de la red ocasionando el incremento de la pérdida de paquetes. Por tanto, la gestión eficiente del gasto es uno de los principales desafíos a enfrentar en el ámbito de investigación de redes ad hoc, en especial para el desarrollo de aplicaciones en escenarios reales de operación. Sin embargo, dicha gestión no es una tarea trivial debido a las características inherentes de este tipo de redes, como por ejemplo la operación distribuida, así como el acceso compartido al medio inalámbrico. En tal sentido, los mecanismos usuales de optimización del gasto de energía basados en el establecimiento de períodos de bajo consumo (modo sleep), no se ajustan a las características operativas de una red ad hoc, debido al impacto notable que ocasionan sobre la conectividad en la red. Además, el crecimiento significativo de las aplicaciones y servicios de distribución de contenidos multimedia, especialmente tráfico de vídeo, demandan niveles específicos de calidad de servicio. Por consiguiente, el diseño de soluciones de optimización de los recursos de energía disponible en los nodos no debe implicar la degradación de la calidad de experiencia percibida por los usuarios finales. Las contribuciones del trabajo de tesis se centran, en primer lugar, en el análisis de los factores que incrementan el gasto de energía en el medio inalámbrico y que están relacionados con el principio de operación de la interfaz de radio. En particular, el incremento dramático del funcionamiento en modo recepción ocasionado sobre las zonas de interferencia por el efecto overhearing así como el mayor número de intentos de transmisión debido a la contienda por el acceso al canal, se definen como las principales causas que incrementan la demanda de energía en la red. Por otra parte, con el objetivo de optimizar los recursos de energía disponibles en los nodos sin ocasionar un perjuicio sobre la calidad de servicio, en el presente trabajo de tesis se proponen mejoras al protocolo de encaminamiento mediante un esquema cross-layer. En concreto, el mecanismo diseñado realiza una evaluación de la capacidad de energía disponible en los nodos, así como de la distribución de los dispositivos en el medio inalámbrico. Con tal fin, la propuesta introduce en el cómputo de enrutamiento una métrica nueva denominada valor estratégico, la cual reporta la importancia de un nodo en la red en términos de conectividad (número de dispositivos vecinos). El esquema apunta a reducir el gasto de energía ocasionado por el efecto overhearing en las zonas con mayor densidad de dispositivos, así como extender la autonomía de operación sobre aquellos nodos con mayor número de vecinos, que resultan estratégicos para conservar la conectividad en la red. Además, de forma consecuente con el actual enfoque pragmático en redes ad hoc orientado al diseño de soluciones para escenarios específicos de aplicación, la evaluación de la propuesta se ha realizado tanto en un entorno de simulación, así como mediante la implementación de un testbed. Específicamente, se ha analizado la operación del mecanismo de enrutamiento propuesto sobre un conjunto de nodos ad hoc implementados mediante plataformas de desarrollo. Adicionalmente, se ha desarrollado una herramienta para el control y configuración de los experimentos. Los resultados demuestran que la propuesta permite extender el tiempo de operación de la red, así como incrementar la tasa de paquetes en recepción como consecuencia de la prevención en la ruptura de los enlaces por agotamiento / El present treball de tesi doctoral aborda la problemàtica de les limitacions d'energia en xarxes sense fil ad hoc. En este tipus de xarxes, els nodes generalment empren bateries com a font d'alimentació, la qual cosa limita de forma dramàtica l'autonomia de funcionament. Els nodes amb major esgotament d'energia constituïxen potencials elements per a la pèrdua de connectivitat parcial o total de la xarxa, ocasionant l'increment de la pèrdua de paquets. Per tant, la gestió eficient de la despesa és un dels principals desafiaments a enfrontar en l'àmbit d'investigació de xarxes ad hoc, en especial per al desenvolupament d'aplicacions en escenaris reals d'operació. No obstant això, aquesta gestió no és una tasca trivial a causa de les característiques inherents d'este tipus de xarxes, com per exemple l'operació distribuïda així com l'accés compartit al mitjà sense fil. En este sentit, els mecanismes usuals d'optimització de la despesa d'energia basats en l'establiment de períodes de baix consum (mode sleep), no s'ajusten a les característiques operatives d'una xarxa ad hoc, a causa de l'impacte notable que ocasionen sobre la connectivitat a la xarxa. A més, el creixement significatiu de les aplicacions i serveis de distribució de continguts multimèdia, especialment tràfic de vídeo, demanden nivells específics de qualitat de servei. Per tant, el disseny de solucions d'optimització dels recursos d'energia disponible en els nodes no ha d'implicar la degradació de la qualitat d'experiència percebuda pels usuaris finals. Les contribucions del treball de tesi se centren, en primer lloc, en l'anàlisi dels factors que incrementen la despesa d'energia en el mitjà sense fil i que estan relacionats amb el principi d'operació de la interfície de ràdio. En particular, l'increment dramàtic del funcionament en mode recepció, ocasionat sobre les zones d'interferència per l'efecte overhearing, així com el major nombre d'intents de transmissió a causa de la contesa per l'accés al canal, es definixen com les principals causes que incrementen la demanda d'energia a la xarxa. D'altra banda, amb l'objectiu d'optimitzar els recursos d'energia disponibles en els nodes sense ocasionar un perjudici sobre la qualitat de servici, en el present treball de tesi es proposen millores al protocol d'encaminament mitjançant un esquema cross-layer. En concret, el mecanisme dissenyat realitza una avaluació de la capacitat d'energia disponible en els nodes així com de la distribució dels dispositius en el mitjà sense fil. Amb tal fi, la proposta introduïx en el còmput d'encaminament una nova mètrica denominada valor estratègic, la qual reporta la importància d'un node en la xarxa en termes de connectivitat (nombre de dispositius veïns). L'esquema reduix la despesa ocasionada per l'efecte overhearing a les zones amb major densitat de dispositius i estén l'autonomia d'operació sobre aquells nodes amb major nombre de veïns, que resulten estratègics per conservar la connectivitat a la xarxa. A més, de forma conseqüent amb l'actual enfocament pragmàtic en xarxes ad hoc orientat al disseny de solucions per a escenaris específics d'aplicació, l'avaluació de la proposta s'ha realitzat tant en un entorn de simulació així com per mitjà de la implementació d'un testbed. Específicament, s'ha analitzat l'operació del mecanisme d'encaminament proposat sobre un conjunt de nodes ad hoc implementats mitjançant plataformes de desenvolupament. Addicionalment, s'ha desenvolupat una eina per al control i configuració dels experiments. Els resultats demostren que la proposta permet estendre el temps d'operació de la xarxa així com incrementar la taxa de paquets en recepció com a conseqüència de la prevenció en la ruptura dels enllaços per esgotament d'energia. / González Martínez, SR. (2017). Diseño de un Esquema Cross-Layer para el Balance entre Eficiencia Energética y Calidad de Servicio en la Transmisión de Tráfico Multimedia en Redes Ad-Hoc [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84284 / TESIS