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1 to 19 of 19 results
  • A diffusion-based em algorithm for distributed estimation in unreliable sensor networks

     Silva Pereira, Silvana; López Valcarce, Roberto; Pages Zamora, Alba Maria
    IEEE signal processing letters
    Date of publication: 2013-01
    Journal article

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  • PORTABLE KIT FOR DETECTING TRAPPED AND BURIED PEOPLE

     Vidal Manzano, Jose; Silva Pereira, Silvana; Pages Zamora, Alba Maria
    Participation in a competitive project

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  • A diffusion-based distributed EM algorithm for density estimation in wireless sensor networks

     Silva Pereira, Silvana; López Valcarce, Roberto; Pages Zamora, Alba Maria
    IEEE International Conference on Acoustics, Speech, and Signal Processing
    Presentation's date: 2013-05-29
    Presentation of work at congresses

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    We address the problem of distributed estimation of a parameter from a set of noisy observations collected by a sensor network, assuming that some sensors may be subject to data failures and report only noise. In such scenario, simple schemes such as the Best Linear Unbiased Estimator result in an error floor in moderate and high signal-to-noise ratio (SNR), whereas previously proposed methods based on hard decisions on data failure events degrade as the SNR decreases. Aiming at optimal performance within the whole range of SNRs, we adopt a Maximum Likelihood framework based on the Expectation-Maximization (EM) algorithm. The statistical model and the iterative nature of the EM method allow for a diffusion-based distributed implementation, whereby the information propagation is embedded in the iterative update of the parameters. Numerical examples show that the proposed algorithm practically attains the Cramer-Rao Lower Bound at all SNR values and compares favorably with other approaches.

  • Distributed Consensus Algorithms for Wireless Sensor Networks Convergence Analysis and Optimization

     Silva Pereira, Silvana
    Defense's date: 2012-01-26
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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  • Consensus in random WSNs with correlated symmetric links

     Silva Pereira, Silvana; Pages Zamora, Alba Maria
    IEEE International Workshop on Signal Processing Advances in Wireless Communications
    Presentation's date: 2011-06-27
    Presentation of work at congresses

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    In this paper we study the convergence of consensus algorithms in wireless sensor networks with random topologies and instantaneous symmetric links which exist with different probabilities independently in time but correlated in space. Aiming at minimizing the convergence time of the algorithm, we adopt an optimization criterion based on the spectral radius of a positive semidefinite matrix for which we derive a closed-form expression, and propose a general formulation for the spatial correlation among the links that allows us to compute the optimum parameters ensuring almost sure convergence. We show that our general formulation can be particularized for existing protocols found in literature, and derive additionally closed-form expressions for the optimal parameters in two particular cases of equal probability of connection for all the links.

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    When gossip meets consensus : convergence in correlated random WSNs  Open access

     Silva Pereira, Silvana; Pages Zamora, Alba Maria
    International Conference on Wireless Technologies for Humanitarian Relief
    Presentation's date: 2011-12-19
    Presentation of work at congresses

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    Postprint (author’s final draft)

  • Macrocelulas y Femtocelulas en Sistemas con Técnicas Avanzadas de Coordinación de la Interferencia y Cooperación

     Vidal Manzano, Jose; Rodriguez Fonollosa, Javier; Cabrera Bean, Margarita Asuncion; Fernandez Rubio, Juan-antonio; Pages Zamora, Alba Maria; Agustin de Dios, Adrian; Silva Pereira, Silvana; Garcia Ordoñez, Luis; Vila Valls, Jordi; Muñoz Medina, Olga
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  • Consensus in Correlated Random Wireless Sensor Networks

     Silva Pereira, Silvana; Pages Zamora, Alba Maria
    IEEE transactions on signal processing
    Date of publication: 2011-12
    Journal article

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    Consensus for distributed EM-based clustering in WSNs  Open access

     Silva Pereira, Silvana; Barbarossa, Sergio; Pages Zamora, Alba Maria
    IEEE Sensor Array and Multichannel Signal Processing Workshop
    Presentation's date: 2010-10-05
    Presentation of work at congresses

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    A distributed EM algorithm with consensus is proposed for density estimation and clustering using WSNs in the presence of mixtures of Gaussians. The EM algorithm is a general framework for maximum likelihood estimation in hidden variable models, usually implemented in a central node with global information of the network. The average consensus algorithm is a simple robust scheme for computing averages in a distributed manner. In this contribution, we run a distributed EM algorithm where the nodes obtain global knowledge of the statistics through consensus with local information exchange only in a WSN with instantaneous random links. Starting from a set of initial values, the nodes are able to compute the complete statistics of a mixture of Gaussians and classify into clusters according to the sensed density using a simple decision rule. A trade off between power consumption and final accuracy of the estimates is established through simulations.

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    Mean square convergence of consensus algorithms in random WSNs  Open access

     Silva Pereira, Silvana; Pages Zamora, Alba Maria
    IEEE transactions on signal processing
    Date of publication: 2010-05
    Journal article

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    Distributed consensus algorithms for estimation of parameters or detection of events in wireless sensor networks have attracted considerable attention in recent years. A necessary condition to achieve a consensus on the average of the initial values is that the topology of the underlying graph is balanced or symmetric at every time instant. However, communication impairments can make the topology vary randomly in time, and instantaneous link symmetry between pairs of nodes is not guaranteed unless an acknowledgment protocol or an equivalent approach is implemented. In this paper, we evaluate the convergence of the consensus algorithm in the mean square sense in wireless sensor networks with random asymmetric topologies. For the case of links with equal probability of connection, a closed form expression for the mean square error of the state along with the dynamical range and the optimum value of the link weights that guarantee convergence are derived. For the case of links with different probabilities of connection, an upper bound for the mean square error of the state is derived. This upper bound can be computed for any time instant and can be employed to compute a link weight that reduces the convergence time of the algorithm.

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    Randomized transmission power for accelerated consensus in asymmetric WSNs  Open access

     Silva Pereira, Silvana; Pages Zamora, Alba Maria
    IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing
    Presentation's date: 2009-12-14
    Presentation of work at congresses

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    The total energy consumed in a wireless sensor network until reaching a consensus is proportional to the product of the sum of the transmission power of each node and the convergence time. In a network where the nodes are allowed to transmit using different power levels, the minimization of this consumption is not trivial. In this paper, we propose a heuristic scheme of randomized power transmission such that the energy consumed by the network is balanced among the nodes and the convergence time is reduced with respect to a fixed symmetric topology that spends the same average transmission power. The proposed scheme establishes random links between nodes with different probabilities of connection, giving a random asymmetric topology at every iteration. Therefore, in order to minimize the convergence time of the algorithm, we use previous results on the analysis of the mean square error of the state.

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    Fast mean square convergence of consensus algorithms in WSNs with random topologies  Open access

     Silva Pereira, Silvana; Pages Zamora, Alba Maria
    IEEE International Conference on Acoustics, Speech and Signal Processing
    Presentation's date: 2009-04-19
    Presentation of work at congresses

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    The average consensus in wireless sensor networks is achieved under assumptions of symmetric or balanced topology at every time instant. However, communication and/or node failures, as well as node mobility or changes in the environment make the topology vary in time, and instantaneous symmetry of the links is not guaranteed unless an acknowledgment protocol or an equivalent approach is implemented. In this paper, we evaluate the convergence in the mean square sense of a well-known consensus algorithm assuming a random topology and asymmetric communication links. A closed form expression for the mean square error of the state is derived as well as the optimum choice of parameters to guarantee fastest convergence of the mean square error.

  • PROCESSAMENT DEL SENYAL EN COMUNICACIONS

     Rey Micolau, Francesc; Villares Piera, N. Javier; Vazquez Grau, Gregorio; Riba Sagarra, Jaume; Vidal Manzano, Jose; Cabrera Bean, Margarita Asuncion; Garcia Ordoñez, Luis; Rodriguez Fonollosa, Javier; Ramirez Javega, Francisco; Muñoz Medina, Olga; Matas Navarro, David; Font Segura, Josep; Silva Pereira, Silvana; Agustin de Dios, Adrian; Fernandez Rubio, Juan-antonio; Lamarca Orozco, M. Meritxell; Pages Zamora, Alba Maria; Sala Alvarez, Jose
    Participation in a competitive project

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  • D3.2 v1.0 Final report on algorithms development

     Pescosolido, L; Barbarossa, S; Battisti, T; Sardellitti, S; Scutari, G; Martinelli, G; Baiocchi, A; Panella, M; Rizzi, A; Silva Pereira, Silvana; Pages Zamora, Alba Maria; Closas Gomez, Pau
    Date: 2008-01
    Report

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  • D3.3 v1.0 Additional report on algorithms development

     Barbarossa, S; Battisti, T; Martinelli, G; Panella, M; Scutari, G; Rizzi, A; Closas Gomez, Pau; Silva Pereira, Silvana; Pages Zamora, Alba Maria
    Date: 2008-10
    Report

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  • D4.1.2 Network level simulator

     Pediaditakis, D; Yovanof, G S; Valkanas, A; Pages Zamora, Alba Maria; Brahim, E; Silva Pereira, Silvana; Vidal, J; Marinis, E De
    Date: 2008-09
    Report

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  • Distributed Consensus in Wireless Sensor Networks with Quantized Information Exchange

     Silva Pereira, Silvana; Pages Zamora, Alba Maria
    9th IEEE Workshop on Signal Processing Advances in Wireless Communications
    Presentation of work at congresses

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  • D4.2. Report on the analysis of modulation techniques and radio technologies

     MENGONI, F; CALABRO, F; BARTOLI, F; PIERROT, J; DANIELE, N; HASLER, M; AJDARI, A RAD; Pages Zamora, Alba Maria; Closas Gomez, Pau; ESTELLERS, Virginia; Silva Pereira, Silvana; Fernandez Rubio, Juan-antonio; BARBAROSSA, S et al
    Date: 2007-08
    Report

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  • D3.1. Intermediate report on algorithms development

     Barbarossa, S; Scutari, G; Pescosolido, L; Sardellitti, S; Battisti, T; Pages Zamora, Alba Maria; Closas Gomez, Pau; Silva Pereira, Silvana; Maribel, Madueño; Vidal Manzano, Jose; Fernandez Rubio, Juan-antonio
    Date: 2007-03
    Report

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