POT : An Efficient Top- k Monitoring Method for Spatially Correlated Sensor Readings
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Transcript of POT : An Efficient Top- k Monitoring Method for Spatially Correlated Sensor Readings
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POT : An Efficient Top-k Monitoring Method for SpatiallyCorrelated Sensor Readings
YongHyun Cho, Jihoon Son and Yon Dohn Chung
Data management for sensor networks 2008
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Outline
Introduction Partial Ordered Tree Simulation Conclusion
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Introduction
Since sensor readings are usually correlated with location, top-k nodes are clustered at some areas
This paper propose a novel tree structure to efficiently maintain clusters of the highest readings
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Temperature of Kawah Ijen crater lake
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POT : Partial Ordered Tree
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Partial Ordered Trees
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Initial construction of POTs
(50,49,47)
(48,45,39)
TOP 3
(50,49,48,47,45,39)
(48+47)/2=47.5
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Local Top-k evaluation
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Global Top-k evaluation
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Updating the POTs
If the size of GR is k, the new threshold is the same to the previous one.
Otherwise, the new threshold is set as the average of the and the
In each POT, only the nodes that have reported their readings are required to update their thresholds.
KGR 1KGR
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Skewed distribution
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AverageEnergyConsumption(1/3)
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AverageEnergyConsumption(2/3)
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AverageEnergyConsumption(3/3)
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Network Lifetime(1/3)
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Network Lifetime(2/3)
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Network Lifetime(3/3)
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Monitoring accuracy
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Conclusion
In sensor networks, sensor readings are usually correlated with their locations
In this paper proposed a novel structure to manage the highest readings and process top-k query