Handheld devices are becoming increasingly common, and they have varied range of resources. Mobile Cloud Computing (MCC) allows resource constrained devices to offload computation and use storage capacities of more resourceful surrogate machines. This enables creation of new and interesting applications for all devices. We propose a scheme that constructs a high-performance de-centralized system by a group of volunteer mobile devices which come together to form a resourceful unit (cloudlet). The idea is to design a model to operate as a public-resource between mobile devices in close geographical proximity. This cloudlet can provide larger storage capability and can be used as a computational resource by other devices in the network. The system needs to watch the movement of the participating nodes and restructure the topology if some nodes that are providing support to the cloudlet fail or move out of the network. In this work, we discuss the need of the system, our goals and design issues in building a scalable and reconfigurable system. We achieve this by leveraging the concept of virtual dominating set to create an overlay in the broads of the network and distribute the responsibilities in hosting a cloudlet server. We propose an architecture for such a system and develop algorithms that are requited for its operation. We map the resources available in the network by first scoring each device individually, and then gathering these scores to determine suitable candidate cloudlet nodes. We have simulated cloudlet functionalities for several scenarios and show that our approach is viable alternative for many applications such as sharing GPS, crowd sourcing, natural language processing, etc.

In this thesis we consider a set of mobile users that employ cloud-based computation offloading. In computation offloading, user energy consumption can be decreased by uploading and executing jobs on a remote server, rather than processing the jobs locally. In order to execute jobs in the cloud however, the user uploads must occur over a base station channel which is shared by all of the uploading users. Since the job completion times are subject to hard deadline constraints, this restricts the feasible set of jobs that can be remotely processed, and may constrain the users ability to reduce energy usage. The system is modelled as a competitive game in which each user is interested in minimizing its own energy consumption. The game is subject to the real-time constraints imposed by the job execution deadlines, user specific channel bit rates, and the competition over the shared communication channel. The thesis shows that for a variety of parameters, a game where each user independently sets its offloading decisions always has a pure Nash equilibrium, and a Gauss-Seidel method for determining this equilibrium is introduced. Results are presented which illustrate that the system always converges to a Nash equilibrium using the Gauss-Seidel method. Data is also presented which show the number of Nash equilibria that are found, the number of iterations required, and the quality of the solutions. We find that the solutions perform well compared to a lower bound on total energy performance. / Thesis / Master of Applied Science (MASc)

The explosion in growth of smart wireless devices has increased the ubiquitous presence of computational resources and location-based data. This new reality of numerous wireless devices capable of collecting, sharing, and processing information, makes possible an avenue for new enhanced applications. Multiple radio nodes with diverse functionalities can form a wireless cloud computing network (WCCN) and collaborate on executing complex applications using wireless distributed computing (WDC). Such a dynamically composed virtual cloud environment can offer services and resources hosted by individual nodes for consumption by user applications. This dissertation proposes an architectural framework for WCCNs and presents the different phases of its development, namely, development of a mathematical system model of WCCNs, simulation analysis of the performance benefits offered by WCCNs, design of decision-making mechanisms in the architecture, and development of a prototype to validate the proposed architecture. The dissertation presents a system model that captures power consumption, energy consumption, and latency experienced by computational and communication activities in a typical WCCN. In addition, it derives a stochastic model of the response time experienced by a user application when executed in a WCCN. Decision-making and resource allocation play a critical role in the proposed architecture. Two adaptive algorithms are presented, namely, a workload allocation algorithm and a task allocation - scheduling algorithm. The proposed algorithms are analyzed for power efficiency, energy efficiency, and improvement in the execution time of user applications that are achieved by workload distribution. Experimental results gathered from a software-defined radio network prototype of the proposed architecture validate the theoretical analysis and show that it is possible to achieve 80 % improvement in execution time with the help of just three nodes in the network. / Ph. D.

Seamless interconnection of smart mobile devices and cloud services is a key goal in modern mobile computing. Mobile Cloud Computing is the holistic integration of contextually-rich mobile devices with computationally-powerful cloud services to create high value products for end users, such as Apple's Siri and Google's Google Now product. This coupling has enabled new paradigms and fields of research, such as crowdsourced data collection, and has helped spur substantial changes in research fields such as vehicular ad hoc networking. However, the growth of Mobile Cloud Computing has resulted in a number of new challenges, such as testing large-scale Mobile Cloud Computing systems, and increased the importance of established challenges, such as ensuring that a user's privacy is not compromised when interacting with a location-aware service. Moreover, the concurrent development of the Infrastructure as a Service paradigm has created inefficiency in how Mobile Cloud Computing systems are executed on cloud platforms. To address these gaps in the existing research, this dissertation presents a number of software and algorithmic solutions to 1) preserve user locational privacy, 2) improve the speed and effectiveness of deploying and executing Mobile Cloud Computing systems on modern cloud infrastructure, and 3) enable large-scale research on Mobile Cloud Computing systems without requiring substantial domain expertise. / Ph. D.

MCC (Mobile Cloud Computing) est un candidat très fort pour le NGN (Next Generation Network) qui permet aux utilisateurs mobiles d’avoir une mobilité étendue, une continuité de service et des performances supérieures. Les utilisateurs peuvent s’attendre à exécuter leurs travaux plus rapidement, avec une faible consommation de batterie et à des prix abordables ; mais ce n’est pas toujours le cas. Diverses applications mobiles ont été développées pour tirer parti de cette nouvelle technologie, mais chacune de ces applications possède ses propres exigences. Plusieurs MCA (Mobile Cloud Architectures) ont été proposées, mais aucune n'a été adaptée pour toutes les applications mobiles, ce qui a mené à une faible satisfaction du client. De plus, l'absence d'un modèle d'affaires (business model) valide pour motiver les investisseurs a empêché son déploiement à l'échelle de production. Cette thèse propose une nouvelle architecture de MCA (Mobile Cloud Architecture) qui positionne l'opérateur de téléphonie mobile au cœur de cette technologie avec un modèle d'affaires de recettes. Cette architecture, nommée OCMCA (Operator Centric Mobile Cloud Architecture), relie l'utilisateur d’un côté et le fournisseur de services Cloud (CSP) de l'autre côté, et héberge un cloud dans son réseau. La connexion OCMCA / utilisateur peut utiliser les canaux multiplex menant à un service beaucoup moins cher pour les utilisateurs, mais avec plus de revenus, et de réduire les embouteillages et les taux de rejet pour l'opérateur. La connexion OCMCA / CSP est basée sur la fédération, ainsi un utilisateur qui a été enregistré avec n’importe quel CSP, peut demander que son environnement soit déchargé de cloud hébergé par l'opérateur de téléphonie mobile afin de recevoir tous les services et les avantages de OCMCA.Les contributions de cette thèse sont multiples. Premièrement, nous proposons OCMCA et nous prouvons qu'il a un rendement supérieur à toutes les autres MCA (Mobile Cloud Architectures). Le modèle d'affaires (business model) de cette architecture se concentre sur la liberté de l'abonnement de l'utilisateur, l'utilisateur peut ainsi être abonné à un fournisseur de cloud et être toujours en mesure de se connecter via cette architecture à son environnement à l'aide du déchargement et de la fédération... / Mobile cloud computing is a very strong candidate for the title "Next Generation Network" which empowers mobile users with extended mobility, service continuity and superior performance. Users can expect to execute their jobs faster, with lower battery consumption and affordable prices; however this is not always the case. Various mobile applications have been developed to take advantage of this new technology, but each application has its own requirements. Several mobile cloud architectures have been proposed but none was suitable for all mobile applications which resulted in lower customer satisfaction. In addition to that, the absence of a valid business model to motivate investors hindered its deployment on production scale. This dissertation proposes a new mobile cloud architecture which positions the mobile operator at the core of this technology equipped with a revenue-making business model. This architecture, named OCMCA (Operator Centric Mobile Cloud Architecture), connects the user from one side and the Cloud Service Provider (CSP) from the other and hosts a cloud within its network. The OCMCA/user connection can utilize multicast channels leading to a much cheaper service for the users and more revenues, lower congestion and rejection rates for the operator. The OCMCA/CSP connection is based on federation, thus a user who has been registered with any CSP, can request her environment to be offloaded to the mobile operator's hosted cloud in order to receive all OCMCA's services and benefits...

La croissance des appareils connectés, principalement due au grand nombre de déploiements de l'internet des objets et à l'émergence des services de cloud mobile, introduit de nouveaux défis pour la conception d'architectures de services dans le Cloud Computing Mobile (CCM) du cloud computing mobile. Nous montrons dans cette thèse comment l'architecture orientée services SOA peut être une solution clé pour fournir des services cloud mobiles distribués et comment la plate-forme OSGi peut être un cadre adaptatif et efficace pour fournir une telle implémentation. Nous adaptons le cadre CCM proposé à différents contextes d'architecture. Le premier est un modèle centré traditionnel, où les appareils mobiles sont réduits à consommer des services. Le second est un modèle distribué où la puissance de l'interaction de mobile à mobile offre des opportunités illimitées de services de valeur, et enfin, l'architecture à trois niveaux est considérée avec l'introduction de la notion de cloudlet. Pour chaque contexte, nous explorons la performance de notre cadre axé sur le service et le comparons à d'autres solutions existantes. / The growth of connected devices, mostly due to the large number of internet of things IoT deployments and the emergence of mobile cloud services, introduces new challenges for the design of service architectures in mobile cloud computing MCC. An MCC framework should provide elasticity and scalability in a distributed and dynamic way while dealing with limited environment resources and variable mobile contexts web applications, real-time, enterprise services, mobile to mobile, hostile environment, etc. that may include additional constraints impacting the design foundation of cloud services. We show in this thesis how service-oriented architecture SOA can be a key solution to provide distributed mobile cloud services and how OSGi platform can be an adaptive and efficient framework to provide such implementation. We adapt the proposed MCC framework to different architecture contexts. The first one is a traditional centric model, where mobile devices are reduced to consuming services. The second one is a distributed model where the power of mobile-to-mobile interaction offers unlimited value-services opportunities, and finally, three-tier architecture is considered with the introduction of the cloudlet notion. For each context, we explore the performance of our service-oriented framework, and contrast it with alternative existing solutions.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-03-15T13:05:35Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Disserta__o_Igor_Costa__Copy_(1).pdf: 11507063 bytes, checksum: f631fc6dd87314e89ea560a118301875 (MD5) / Made available in DSpace on 2016-03-15T13:05:35Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Disserta__o_Igor_Costa__Copy_(1).pdf: 11507063 bytes, checksum: f631fc6dd87314e89ea560a118301875 (MD5) Previous issue date: 2015-08-31 / As limitações da computação móvel abrem caminhos para utilizar recursos de computação em nuvem voltadas à dispositivos móveis, sendo este o principal objetivo da Mobile Cloud Computing (MCC). Questões como armazenamento e processamento podem afetar a disponibilidade de um serviço no dispositivo móvel, assim, para minimizar esses problemas é possível o particionamento da aplicação em frontend e backend. Os serviços de nuvem auxiliam esse processo com a utilização de ambientes Mobile Backend-as-a-Service (MBaaS), que permitem os desenvolvedores conectar o backend de suas aplicações para o armazenamento em nuvem. Uma plataforma de MBaaS oferece um serviço de sincronização completa para aplicações móveis. Uma vez que os dados armazenados no dispositivo móvel estão sincronizados com os centros de dados distribuídos, a disponibilidade do sistema no lado servidor é um atributo fundamental que requer investigação, pois sistemas computacionais tendem a falhar. As falhas podem ocorrer em hardwares, softwares e meios de conexão, acarretando assim, em prejuízos financeiros e comprometendo a credibilidade das empresas provedoras do serviço. Os administradores necessitam de mecanismos para estimar a disponibilidade de seus sistemas, podendo definir Service Level Agreement (SLA) com mais propriedade. Assim, modelos analíticos podem ser utilizados para avaliar a disponibilidade destes tipos de ambientes, bem como auxiliar a mitigar o downtime, aumentando a disponibilidade do serviço. Este trabalho propõe modelos analíticos para avaliar a disponibilidade desses ambientes. Para tanto, foi adotada uma metodologia: primeiramente definiu-se a arquitetura básica do serviço; a qual foi modelada a partir de um modelo hierárquico, composto de diagramas de blocos de confiabilidade (RBD) e cadeias de Markov de tempo contínuo (CTMC) e validado através de um testbed de injeção de falhas e reparos em um ambiente real. Baseado no modelo de serviço proposto, foi efetuada a análise de sensibilidade, que identificou o sistema como componente crítico. A partir disto, foram sugeridos modelos hierárquicos que representem o ambiente de nuvem, e com base neste ambiente, através da técnica de análise de sensibilidade, foram propostas quatro arquiteturas, sendo estas avaliados em termos de disponibilidade e downtime anual. Os resultados demonstram que a implementação de um processo de recuperação automática sobre o componente de software, Java Virtual Machine, reduz o downtime anual na arquitetura básica em cerca de 10%, bem como é possível observar que no ambiente de nuvem utilizando o mecanismo de redundância warm-standby nos nós e no frontend apresenta efetiva melhora na disponibilidade. Desta forma, a presente pesquisa pode orientar os administradores de sistemas MBaaS no planejamento de suas políticas de manutenção. / The mobile computer restrictions propose new ways to use cloud computing resources aimed at mobile devices, this is the Mobile Cloud Computing (MCC) primary goal. Issues such as storage and processing can impact the service availability on the mobile device. With the reducing purpose, these questions are its possible divide the application into two pieces, frontend, and backend. The cloud services assist this process with the Mobile Backend-as-a- Service (MBaaS) use. This tool allows the developers connect yours application backend to cloud storage. The MBaaS OpenMobster platform offers complete synchronization service to mobile applications. Since the data stored on mobile was synchronized distributed data center, the server’s system availability is an essential attribute and request attention, because computer systems will sometimes fail. The failures can happen on components variety as hardware, software and connections, causing financial losses and reliability compromising of the companies, which offer this services. The administrators need tools to project the system availability, with this they can define the SLA with more assurance. Analytic models can be used to availability evaluate in this environment and mitigate the downtime risk, this improves the service availability. This work primary goal is proposed analytic models to availability evaluated in these environments. It was adopted a methodology as follow: First, define the base service architecture. It was modeled by use a hierarchical model, using a reliability block diagram (RBD) and continuous-time Markov chain (CTMC). The validation considers a fault injection testbed and repairs on real environment. Considering the model proposed, it was done sensitivity analysis, these results present the system as a critical component. This analysis was proposed hierarchical models to represents cloud environment. On these sensibility analysis, a background was offered four scenarios. The scenarios were evaluated to determine the availability and annual downtime. The results show that the an automatic recovery implementation process on the software component, Java Virtual Machine, decrease the annual downtime on base architecture to 10%. The results present the availability improvement when adopted redundancy strategy as warm standby on a cloud environment. This way, the work can guide the MBaaS system administrators in planning their maintenance policies.

Mobile devices are often expected to perform computational tasks that may be beyond their processing or battery capability. Cloud computing techniques have been proposed as a means to offload a mobile device's computation to more powerful resources. In this thesis, we consider the case where powerful computing resources are made available by utilizing vehicles. These vehicles can be repositioned in real time to receive computational tasks from user-carried devices. They can be either equipped with rugged high-performance computers to provide both computation and communication service, or they can be simple message ferries that facilitate communication with a more powerful computing resource. These scenarios find application in challenged environments and may be used in a military or disaster relief settings. It is further enabled by increasing feasibility of (i) constructing a Mobile High Performance Computer (MHPC) using rugged computer hardware with form factors that can be deployed in vehicles and (ii) Message Ferries (MF) that provide communication service in disruption tolerant networks. By analogy to prior work on message ferries and data mules, one can refer to the use of our first schema, MHPCs, as computational ferrying. After illustrating and motivating the computational ferrying concept, we turn our attention into the challenges facing such a deployment. These include the well known challenges of operating an opportunistic and intermittently connected network using message ferries -- such as devising an efficient mobility plan for MHPCs and developing techniques for proximity awareness. In this thesis, first we propose an architecture for the system components to be deployed on the mobile devices and the MHPCs. We then focus on defining and solving the MHPC movement scheduling problem with sufficient generality to describe a number of plausible deployment scenarios. After thorough examination of the MHPC concepts, we propose a scheme in which MHPCs are downgraded to be simple MFs that instead provide communication to a stationary HPC with powerful computing resources. Similar to the MPHCs, we provide a framework for this problem and then describe heuristics to solve it. We conduct a number of experiments that provide an understanding of how the performance of the system using MHPCs or MFs is affected by various parameters. We also provide a thorough comparison of the system in the dimensions of Computation on the Move and Controlling the Mobility.

Mobile cloud computing is a way of delegating complex algorithms from a mobile device to the cloud to complete the tasks quickly and save energy on the mobile device. However, the cloud may not be available or suitable for helping all the time. For example, in a battlefield scenario, the cloud may not be reachable. This work considers neighbouring devices as alternatives to the cloud for offloading computation and presents three key contributions, namely a comprehensive investigation of the trade-off between computation and communication, Multi-Objective Optimisation based approach to offloading, and Queuing Theory based algorithms that present the benefits of offloading to neighbours. Initially, the states of neighbouring devices are considered to be known and the decision of computation offloading is proposed as a multi-objective optimisation problem. Novel Pareto optimal solutions are proposed. The results on a simulated dataset show up to 30% increment in performance even when cloud computing is not available. However, information about the environment is seldom known completely. In Chapter 5, a realistic environment is considered such as delayed node state information and partially connected sensors. The network of sensors is modelled as a network of queues (Open Jackson network). The offloading problem is posed as minimum cost problem and solved using Linear solvers. In addition to the simulated dataset, the proposed solution is tested on a real computer vision dataset. The experiments on the random waypoint dataset showed up to 33% boost on performance whereas in the real dataset, exploiting the temporal and spatial distribution of the targets, a significantly higher increment in performance is achieved.

GOMES, Francisco Anderson de Almada. Um serviço de offloading de dados contextuais com suporte à privacidade. 2017. 95 f. Dissertação (Mestrado em Ciência da Computação)- Universidade Federal do Ceará, Fortaleza, 2017. / Submitted by Jonatas Martins (jonatasmartins@lia.ufc.br) on 2017-05-26T13:43:05Z No. of bitstreams: 1 2017_dis_faagomes.pdf: 5747766 bytes, checksum: 678be7c6e0c8e999826aa6d7060bebb5 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2017-05-26T17:04:18Z (GMT) No. of bitstreams: 1 2017_dis_faagomes.pdf: 5747766 bytes, checksum: 678be7c6e0c8e999826aa6d7060bebb5 (MD5) / Made available in DSpace on 2017-05-26T17:04:18Z (GMT). No. of bitstreams: 1 2017_dis_faagomes.pdf: 5747766 bytes, checksum: 678be7c6e0c8e999826aa6d7060bebb5 (MD5) Previous issue date: 2017 / Mobile devices became a common tool in our daily routine. Mobile applications are demanding access to contextual information increasingly. For instance, applications require user’s environment data as well as their profiles in order to adapt themselves (interfaces, services, content) according to this context data. Mobile applications with this behavior are known as context-aware applications. Several software infrastructures have been created to help the development of this applications. However, it was verified that most of them do not store history of the contextual data, since mobile devices are resource constrained. They are not built taking into account the privacy of contextual data either, due the fact that applications may expose contextual data without user consent. This dissertation addresses these topics by extending an existing middleware platform that help the development of mobile context-aware applications. This work present a service named COP (Contextual data Offloading service with Privacy Support) and is based in: (i) a context model, (ii) a privacy policy and (iii) synchronization policies. The COP aims to store and process the contextual data generated from several mobile devices, using the computational power of the cloud. To evaluate this work we developed an application that uses both the migration and the privacy mechanism of the contextual data of the COP. Other two experiments were made. The first experiment evaluated the impact of contextual filter processing in mobile device and remote environment, in which the processing time and energy consumption were measured. In this experiment was possible to conclude that the migration of data from mobile device to a remote environment is advantageous. The second experiment evaluated the energy consumption to send contextual data. / Dispositivos móveis tornaram-se uma ferramenta comum no dia a dia das pessoas. Aplicações móveis cada vez mais exigem o acesso às informações contextuais. Por exemplo, aplicações requerem os dados do ambiente do usuário, bem como dos seus perfis, a fim de se adaptarem (interfaces, serviços, conteúdo) de acordo com esses dados de contexto. Aplicações com esse comportamento são conhecidas como aplicações sensíveis ao contexto. Várias infraestruturas de software foram criadas para ajudar no desenvolvimento dessas aplicações. No entanto, foi verificado que a maioria delas não possui um histórico dos dados contextuais, uma vez que os dispositivos móveis são limitados em recursos de armazenamento. Também foi verificado que a maioria delas não é construída levando em conta a privacidade dos dados contextuais, o que pode levar à exposição desses dados sem o consentimento do usuário. Esta dissertação aborda tais tópicos, estendendo uma plataforma de middleware existente que ajuda o desenvolvimento de aplicativos móveis e sensíveis ao contexto. Este trabalho apresenta um serviço denominado COP (Contextual data Offloading service with Privacy Support) e é baseado em: (i) um modelo de contexto, (ii) uma política de privacidade e (iii) em políticas de sincronização de dados. O COP visa armazenar e processar os dados contextuais gerados a partir de vários dispositivos móveis, utilizando o poder computacional da nuvem. Para avaliar este trabalho foi desenvolvida uma aplicação que utiliza tanto a migração como o mecanismo de privacidade dos dados contextuais do COP. Outros dois experimentos foram feitos. O primeiro experimento avaliou o impacto da execução de filtros contextuais no dispositivo móvel e no ambiente remoto, em que foi medido o tempo e gasto energético desse processamento. Nesse experimento foi possível concluir que a migração de dados de um dispositivo móvel para um ambiente remoto é vantajosa. O segundo experimento avaliou o gasto energético para o envio dos dados contextuais.