7,133 research outputs found
Enabling Disaster Resilient 4G Mobile Communication Networks
The 4G Long Term Evolution (LTE) is the cellular technology expected to
outperform the previous generations and to some extent revolutionize the
experience of the users by taking advantage of the most advanced radio access
techniques (i.e. OFDMA, SC-FDMA, MIMO). However, the strong dependencies
between user equipments (UEs), base stations (eNBs) and the Evolved Packet Core
(EPC) limit the flexibility, manageability and resiliency in such networks. In
case the communication links between UEs-eNB or eNB-EPC are disrupted, UEs are
in fact unable to communicate. In this article, we reshape the 4G mobile
network to move towards more virtual and distributed architectures for
improving disaster resilience, drastically reducing the dependency between UEs,
eNBs and EPC. The contribution of this work is twofold. We firstly present the
Flexible Management Entity (FME), a distributed entity which leverages on
virtualized EPC functionalities in 4G cellular systems. Second, we introduce a
simple and novel device-todevice (D2D) communication scheme allowing the UEs in
physical proximity to communicate directly without resorting to the
coordination with an eNB.Comment: Submitted to IEEE Communications Magazin
Application-level differential checkpointing for HPC applications with dynamic datasets
High-performance computing (HPC) requires resilience techniques such as checkpointing in order to tolerate failures in supercomputers. As the number of nodes and memory in supercomputers keeps on increasing, the size of checkpoint data also increases dramatically, sometimes causing an I/O bottleneck. Differential checkpointing (dCP) aims to minimize the checkpointing overhead by only writing data differences. This is typically implemented at the memory page level, sometimes complemented with hashing algorithms. However, such a technique is unable to cope with dynamic-size datasets. In this work, we present a novel dCP implementation with a new file format that allows fragmentation of protected datasets in order to support dynamic sizes. We identify dirty data blocks using hash algorithms. In order to evaluate the dCP performance, we ported the HPC applications xPic, LULESH 2.0 and Heat2D and analyze them regarding their potential of reducing I/O with dCP and how this data reduction influences the checkpoint performance. In our experiments, we achieve reductions of up to 62% of the checkpoint time.This project has received funding from the European Unions Seventh Framework Programme (FP7/2007-2013) and the Horizon 2020 (H2020) funding framework under grant agreement no. H2020-FETHPC-754304 (DEEP-EST); and from the European Unions Horizon 2020 research and innovation programme under the LEGaTO Project (legato- project.eu), grant agreement No 780681.Peer ReviewedPostprint (author's final draft
Discovering the Ethereum2 P2P network
Achieving the equilibrium between scalability, sustainability, and security while keeping decentralization has prevailed as the target solution for decentralized blockchain applications over the last years. Several approaches have been proposed by multiple blockchain teams to achieve it, Ethereum being among them. Ethereum is on the path of a major protocol improvement called Ethereum 2.0 (Eth2), implementing Sharding and introducing the Proof-of-Stake (PoS). As the change of consensus mechanism is a delicate matter, this improvement will be achieved through different phases, the first of which is the implementation of the Beacon Chain. As Ethereum1, Eth2 relies on a decentralized peer-to-peer (p2p) network for the message distribution. Up to date, we estimate that there are around 5.000 nodes in the Eth2 main net geographically distributed. However, the topology of this one still prevails unknown. In this paper, we present the results obtained from the analysis we performed on the Eth2 p2p network. Describing the topology of the network, as possible hazards that this one implies.This work has been supported by the Ethereum Foundation under Grant FY20-0198.Peer ReviewedPostprint (author's final draft
Armiarma: Ethereum2 Network Monitoring Tool
Achieving the equilibrium between scalability, sustainability and security
has prevailed as the ideal solution for decentralized blockchain applications
over the last years. Several approaches have been proposed being Ethereum a
solid proposal among them. Ethereum is on the path of a major protocol
improvement called Ethereum 2.0 (Eth2), implementing Sharding and introducing
the Proof-of-Stake (PoS). As the change of consensus mechanism is a delicate
matter, this improvement will be achieved through different phases, the first
of which is the implementation of the Beacon Chain. The implementation of the
latest has been stated with the recent launch of the Eth2 main net. In this
work, we introduce an Eth2 network monitor tool, called Armiarma, used to
generate a complete analysis of the p2p network of the Eth2 main net. In this
paper, we present some of the results of what this Eth2 network monitor can
achieve
El pensamiento algebraico, multiplicativo y aditivo desde una perspectiva semiótica cultural
Se propone un taller práctico para docentes investigadores que tiene como objetivo principal contribuir a ampliar la mirada de los signos que dan cuenta del pensamiento matemático, particularmente en la resolución de tareas en contextos algebraicos, aditivos y multiplicativos. Para tal fin se utilizará el análisis realizado de la actividad matemática de un grupo de estudiantes colombianos cuando resuelven tareas asociadas a la generalización de patrones y a tareas de tipo aditivo y multiplicativo. Tales tareas hacen parte de los trabajos de maestrÃa de los talleristas Gómez (2013), Pantano (2013), Mojica (2013). El propósito del taller se capitaliza al proponer a los asistentes un ejercicio de análisis de la actividad matemática de un grupo de estudiantes cuando resuelven tareas inmersas en los contextos ya mencionados. Para tal fin se usan algunos elementos de la teorÃa cultural de la objetivación como categorÃas de análisis
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