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Sensor Networks Storage. Sanket Totala Sudarshan Jagannathan. Outline. Introduction Storage Mechanisms Multi-Resolution Storage Two-Tier Storage Conclusion. Introduction. Sensor Nodes Low Memory Low Power Low processing capability Inapproachability Sensor Networks

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sensor networks storage

Sensor Networks Storage

Sanket Totala

Sudarshan Jagannathan

outline
Outline
  • Introduction
  • Storage Mechanisms
  • Multi-Resolution Storage
  • Two-Tier Storage
  • Conclusion
introduction
Introduction
  • Sensor Nodes
    • Low Memory
    • Low Power
    • Low processing capability
    • Inapproachability
  • Sensor Networks
    • Efficiency requirements
    • Highly dense
introduction4
Introduction
  • Sensor Storage
    • Large number of events
    • Query handling capability required
    • Streaming data
    • Aging mechanism
    • Data organization
sensor network storage mechanism
Sensor Network Storage - Mechanism
  • Centralized Storage
    • Central server
      • Ample power
      • Sufficient storage
      • Single point of failure
    • Fast Query processing
    • High communication
    • Sparse Networks
      • Infrequent events
      • Low Data Transfer
    • Scalability problems
sensor network storage mechanism6
Sensor Network Storage - Mechanism
  • Distributed Storage
    • Storage at each node
    • Local computation
    • Scalable
    • Dense Networks
      • Frequent events
      • High Data Transfer
    • Slower Query processing
      • Flooding
      • Distributed Indexing
      • Drill-down querying
multi resolution storage
Multi-Resolution Storage
  • Multi-Resolution summarization
    • Construct data summaries
    • Hierarchy construction
  • Drill-down query evaluation
    • Narrowing search space
    • Spatio-temporal compression
  • Data aging
    • Efficient storage utilization
    • Data Degradation
multi resolution summarization
Multi-Resolution summarization
  • Temporal Summarization
    • Exploits Temporal

redundancy

    • Computation overhead
    • No communication

overhead

  • Spatial Summarization
    • Exploits Spatial redundancy
    • Data Summarization

every level

    • Hierarchy construction
drill down query evaluation
Drill-down query evaluation
  • Spatial compression
    • Finer data view with

every level.

    • Reduced search cost
  • Query routing
    • Sub region selection
    • More accurate result
data aging
Data Aging
  • Long deployment
  • Limited storage
  • Efficient resource

utilization

  • Fast query processing
  • Accuracy
  • Higher level, Higher

time periods

data aging algorithms
Data Aging – Algorithms
  • Omniscient Algorithm
    • Data sets available
    • Full global knowledge required
    • Query specific
  • Training Algorithm
    • Data sets available
    • Data set partitioned
      • Training data (available during sensor deployment)
      • Test data
  • Greedy Algorithm
    • Data set unavailable
    • Assigns weights to data summaries
outline two tier sensor storage
Outline – Two Tier Sensor Storage
  • Design Considerations and Principles
  • System Design
    • Architecture
    • Data structures
  • Data Storage
  • Sensor Network Data Summarization
  • Conclusion
design consideration and principles
Design Consideration and Principles
  • The Three-Tier Model
    • Bottom tier - Untethered sensor nodes
    • Middle tier - Tethered sensor proxies
    • Upper tier - Applications and user terminals
design consideration and principles14
Design Consideration and Principles
  • Principles
    • Store locally, access globally
    • Distinguish data from metadata
    • Provide data-centric query support
data structures used
Data Structures Used
  • Skip Graph
    • Ordered index
    • In-place indexing
    • Log n height
    • Probabilistic balance
    • Redundancy and resiliency
data structures used16
Data Structures Used
  • Interval Skip Graph
    • Extends skip graphs to store intervals
    • Allows efficient searches
    • Complexity of search is O(log n)
    • Insertion cost of O(n)
  • Sparse Interval Skip Graph
data storage
Data Storage
  • Local Storage at Sensors
    • Archival Stores: Collection of records
    • Interval skip graphs used
    • Efficient routing and query handling
    • Operations: Create, Read & Delete
sensor data summarization
Sensor Data Summarization
  • Data summaries – bind the storage at the remote sensor and the index at the proxy
  • Each update from a sensor to the proxy includes
    • The summary
    • Time period corresponding to the summary
    • The start and end offsets for the flash archive
sensor summarization
Sensor Summarization
  • Adaptive Summarization
    • Balances the cost of sending updates against the cost of false positives
    • Summarization Parameters
      • The interval over which summaries of the data are constructed and transmitted to the proxy
      • The size of the application specific summary.
conclusion
Conclusion
  • Multi-tier nature of sensor networks
  • Large amounts of events and data
    • Lossy Approach
    • Two-Tiered Approach
  • Low overheads
    • Decentralized and Hierarchical storage
  • Possible Solution
    • Combine lossy nature of Multi-resolution with routing techniques of Two-tiered approach.