Browsing by Author "Nakamura, Eduardo Freire"

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Data centric sensor stream reduction for real-time applications in wireless sensor networks
    (2009) Aquino, André Luiz Lins de; Nakamura, Eduardo Freire
    This work presents a data-centric strategy to meet deadlines in soft real-time applications in wireless sensor networks. This strategy considers three main aspects: (i) The design of real-time application to obtain the minimum deadlines; (ii) An analytic model to estimate the ideal sample size used by data-reduction algorithms; and (iii) Two data-centric stream-based sampling algorithms to perform data reduction whenever necessary. Simulation results show that our data-centric strategies meet deadlines without loosing data representativeness.
  • No Thumbnail Available
    Item
    Data stream based algorithms for wireless sensor network applications
    (2007) Aquino, André Luiz Lins de; Figueiredo, Carlos Maurício Seródio; Nakamura, Eduardo Freire; Buriol, Luciana Salete; Loureiro, Antônio Alfredo Ferreira; Fernandes, Antônio Otávio; Coelho Júnior, Claudionor José Nunes
    A wireless sensor network (WSN) is energy con-strained, and the extension of its lifetime is one of the most important issues in its design. Usually, a WSN collects a large amount of data from the environment. In contrast to the conventional remote sensing – based on satellites that collect large images, sound files, or specific scientific data – sensor networks tend to generate a large amount of sequential small and tuple-oriented data from several nodes, which constitutes data streams. In this work, we propose and evaluate two algorithms based on data stream, which use sampling and sketch techniques, to reduce data traffic in a WSN and, consequently, decrease the delay and energy consumption. Specifically, the sampling solution, provides a sample of only log n items to represent the original data of n elements. Despite of the reduction, the sampling solution keeps a good data quality. Simulation results reveal the efficiency of the proposed meth-ods by extending the network lifetime and reducing the delay without loosing data representativeness. Such a technique can be very useful to design energy-efficient and time-constrained sensor networks if the application is not so dependent on the data precision or the network operates in an exception situation (e.g., there are few resources remaining or there is an urgent situation)
  • No Thumbnail Available
    Item
    On the use data reduction algorithms for real-time Wireless Sensor Networks.
    (2007) Aquino, André Luiz Lins de; Figueiredo, Carlos Maurício Seródio; Nakamura, Eduardo Freire; Loureiro, Antônio Alfredo Ferreira; Fernandes, Antônio Otávio; Coelho Júnior, Claudionor José Nunes
    This work presents the design of real time applications for Wireless Sensor Networks (WSNs) by using analgorithm based on data stream to process the sensor data. The proposed algorithm is based on sampling techniques applied to data histograms created from original data stream sac quired by sensor nodes. As a result, the algorithm provides a sample of log n item store present the original data stream of n elements. In this work, we show how to use the data reduction algorithmin real-time WSN design.
  • No Thumbnail Available
    Item
    A reactive role assignment for data routing in event-based wireless sensor networks.
    (2009) Nakamura, Eduardo Freire; Ramos Filho, Heitor Soares; Villas, Leandro Aparecido; Oliveira, Horácio Antônio Braga Fernandes de; Aquino, André Luiz Lins de; Loureiro, Antônio Alfredo Ferreira
    In this work, we show how we can design a routing protocol for wireless sensor networks (WSNs) to support an information-fusion application. Regarding the application, we consider that WSNs apply information fusion techniques to detect events in the sensor field. Particularly, in event-driven scenarios there might be long intervals of inactivity. However, at a given instant, multiple sensor nodes might detect one or more events, resulting in high traffic. To save energy, the network should be able to remain in a latent state until an event occurs, then the network should organize itself to properly detect and notify the event. Based on the premise that we have an information-fusion application for event detection, we propose a role assignment algorithm, called Information-Fusion-based Role Assignment(InFRA), to organize the network by assigning roles to nodes only when events are detected. The InFRA algorithm is a distributed heuristic to the minimal Steiner tree, and it is suitable for networks with severe resource constraints, such as WSNs. Theoretical anal ysis shows that, in some cases, our algorithm has aOð1 Þ-approximation ratio. Simulation results show that the InFRA algorithm can use only 70% of the communication resources spent by a reactive version of the Centered-at-Nearest-Source algorithm.
  • No Thumbnail Available
    Item
    Redes de sensores sem fio para monitoramento de anfíbios.
    (2008) Aquino, André Luiz Lins de; Figueiredo, Carlos Maurício Seródio; Loureiro, Antônio Alfredo Ferreira; Mini, Raquel Aparecida de Freitas; Nakamura, Eduardo Freire; Oliveira, Horácio Antônio Braga Fernandes de; Ruiz, Linnyer Beatrys