Current estimated energy usage of data centers and core networks adds up to 3% of the global energy production, while only 42,3% of the population is estimated to be connected. In the last 14 years the number of Internet users has increased tenfold, especially in the period 2010-2014. According to this growing trend, Internet's energy consumption is meant to be a very critical issue in the near future. The emergence of cloud computing represented a major breakthrough in Internet technologies and in reduction of energy consumption. However, due to its centralized nature, this improvement in energy-efficiency has not been reflected in networks' consumption. In this paper, we analyze energy consumption of cloud networks, and present GRaNADA, a semi-decentralized Platform-as-a-Service architecture. Through simulations, we show an overall saving much of the energy consumed in standard centralized clouds with our approach.

Abstract-The consolidation of services is a widely accepted technique for IaaS Cloud providers to reducing energy consumption and improving the utilization of their resources. This technique is based on distributing all services in the minimum amount of servers. This way, the overall energy consumption of the datacenter is reduced, as less servers are needed to be active. Traditionally, research has focused on strategies for consolidation of Virtual Machines (VMs), but containers are changing the landscape of Cloud services. Containers are expected to optimize the consolidation of services by reducing the amount of needed resources, thus allocating more services using less servers. However, while multiple research works have been produced in the Energy Efficiency (EE) achieved through consolidation of VMs, there is yet no experimental work on how consolidation of containers affects EE, when assuming a given Quality-of-Service (QoS) to the user. In this paper we show an experimental analysis on the effects of consolidation of containers in the QoS and EE, compared to the consolidation of VMs. We demonstrate that the consolidation of containers is indeed more optimal than the one of VMs, both in terms of QoS and EE. Consecutively, we analyze how the degradation of the service is produced both in QoS and EE, and we show how QoS is the variable which is more affected by consolidation. This work provides the necessary scientific background on consolidation of two widely used virtualization technologies, and we believe it is useful for future works on the optimization of resources in datacenters.

Abstract:The current mobile Cloud computing trend has set the focus on the ubiquity of computation. However, the current architecture confines the cloud to datacenters, which are generally far from the user. Distance leads to increased utilization of the broadband Wide Area Network -WAN -and poor user experience, especially for interactive applications. Decentralized architectures are emerging as an alternative, but they still fail to adapt to situations where files are concurrently modified. A semi-decentralized approach which confines local traffic close to the user while still maintaining centralized characteristics, running on the users and network devices, can provide a better Quality of Experience (QoE) in large urban populations in mobile cloud networks. In this report, we propose a novel semi-centralized cloud architecture based on microclouds. Microclouds are dynamically created and allow users to contribute resources from their computers, mobile and network devices to the cloud. We present the process for building and reconfiguring the microclouds, whilst guaranteeing a high QoE to users of real-time applications. We also provide a description of a realistic mobile cloud use-case. Results from a simulation-based evaluation indicate that the microclouds architecture is able to sustain hundreds of mobile devices and provide a latency significantly lower than regular Clouds based on datacenters. Résumé : La tendance actuelle des applications mobiles dans les nuages informatiques (clouds) a mis láccent sur lómniprésence du calcul. Cependant, lárchitecture actuelle confine le cloud dans les centres de données qui sont généralement loin de lútilisateur. Cette distance conduit á une utilisation accrue de la bande passante des réseaux longue distance (Wide Area Network -WAN) et conduit á une expérience utilisateur médiocre, en particulier pour les applications interactives. Les architectures décentralisées apparaissent comme une alternative, mais elles ne parviennent pas toujours á s'adapter á des situations oú les fichiers sont modifiés de maniére concurrente. Une approche semi-décentralisée, mise en oeuvre sur les équipements des utilisateurs et du réseau et confinant le trafic local á proximité de lútilisateur tout en conservant les caractéristiques centralisées, peut fournir une meilleure qualité déxpérience (QoE) aux grandes populations urbaines utilisant les applications mobiles des clouds. Dans cet rapport, nous proposons une nouvelle architecture de cloud semi-centralisée fondée sur les "microclouds". Les microclouds sont créés dynamiquement et permettent aux utilisateurs de fournir au cloud des ressources de leurs ordinateurs, smartphones et équipements réseau. Nous présentons le processus de construction et de reconfiguration des microclouds, tout en garantissant un haut degré de QoE aux utilisateurs dápplications temps-réel. Nous donnons également une description dún cas d'utilisation réaliste de cloud mobile. Les résultats dúne évaluation menée par simulation indiquent que lárchitecture á base de m...

Mobile Cloud Computing is a form of collaborative decentralized Cloud which allows mobile devices to unload computation to a local Cloud formed by mobile and static devices. Mobile Cloud Computing provides a better service to latency sensitive applications, due to its physical proximity to the VM host. However, in these systems, the problem of free riding users becomes more acute, for the heterogeneity of devices (from smartphones to private servers) makes the gap of contributed resources much larger. In this work, we analyze the use of incentives for Mobile Clouds, and propose a new auction system adapted to the high dynamism and heterogeneity of these systems. We compare our solution to other existing auctions systems in a Mobile Cloud use case, and show the suitability of our solution.

We're currently involved in a project that aims to increase security in sensitive (medical or administrative) transactions in unfriendly environments. Such environments are typical in areas with major telecommunication infrastructure deficiencies. In particular, we hope to reduce intermittent communications, which cause breaks in the flow of communication, and identify organizational aspects that influence the design and use of deployed services. We're also researching usability issues that hinder user acceptance, as well as the loss of information in failed transactions, which reduces users' confidence in the services deployed.We've defined a model of communications in which all entities involved in communication exchange and share the same piece of information. These pieces of information, called Contract Documents (CDs), whose scheme is based on previously defined transaction to be