Anchor Nodes Placement for Effective Passive Localization

1
Anchor Nodes Placement for Effective Passive
Localization

• Karthikeyan Pasupathy
• Major Advisor Dr. Robert Akl
• Department of Computer Science and Engineering

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Outline

• Objective
• Overview of Sensor Networks
• Localization
• Motivation
• Anchor Node Placement
• Simulations and Results
• Conclusions and Future Directions

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Objective

• How to place anchor nodes for better passive
  localization ?

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Overview of Sensor Networks

• Made of tiny sensor nodes networked together
• Communicate wirelessly

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Overview of Sensor Networks

• Architecture

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Overview of Sensor Networks

• Limitations
• Deployment
• Short lifetime
• Unmanned

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Overview of Sensor Networks

• Applications
• Military
• Reconnaissance, surveillance, shooters location,
  target tracking etc.
• Environment
• Track animals, birds, environmental conditions
  detect forest fires, floods

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Overview of Sensor Networks

• Applications
• Healthcare
• Monitor doctors, patients, drug administrators
• Hospitals monitor physiological signals
• Medication avoid wrong medication

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Overview of Sensor Networks

• Applications
• Domestic
• Smart home
• Smart kindergarten
• Industry
• Machine diagnosis monitor radiation, material
  fatigue, product quality

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Localization

• Where are these nodes ?
• Local position
• Global position
• How to localize?
• GPS

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Localization

• Localization Systems
• Centralized
• Distributed

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Localization

• Centralized
• Not limited by algorithm
• More accurate results
• Traffic congestion
• Computational complexity

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Localization

• Distributed
• Usually iterative
• Algorithms generally energy efficient and self
  organizing
• Less accurate

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Localization

• Different techniques
• Received Signal Strength (RSS)
• Time of Arrival (TOA)
• Angle of Arrival (AOA)

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RSS

• Signal strength
• Inverse Square law
• Error of several meters
• Less accurate
• Vulnerable to occlusions

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Radio Hop Count

• Nodes separated by at most R
• Affected by hindrances

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TOA

• Difference in propagation speed of signals

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TOA

• More accurate
• Vulnerable to occlusions

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Angle of Arrival

• Phase / Time difference recorded by an array of
  microphones
• Expensive
• Bulkier
• Not practical to implement
• Sensor size shrinks

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Passive Localization

• Why passive ?
• Nodes are silent
• Advantages
• No external source for signals
• Can work with existing data
• Can be used in most outdoor applications

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Passive Localization

• Disadvantages
• Centralized
• Not suitable for indoor applications

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Passive Localization

• Event detection
• Projected distances
• Localization
• Distance Matrix
• SVD

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Passive Localization

• Localization
• Linear Combination coefficients

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Motivation

• Deployment of anchor nodes at specific position
  not easy
• Function of anchor nodes are different in passive
  localization

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Anchor Node Placement

• Density
• Better to have more anchor nodes
• Deployment and hardware costs
• Redundancy
• Geometry
• No three anchor nodes may be linearly related

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Simulations and results

• Assumptions
• Propagation velocity unity
• Clocks - time synchronized.
• Global events - distributed around the network.
• Signal processing skipped

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Simulations and results

• Assumptions
• Ideal case no redundancy
• Global event static sources

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Simulations and Results

• User Interface

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Simulations and Results

• Localization Error

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Simulations and Results

• Random deployment

n 10, k 3
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Simulations and Results

• Random deployment

n 10, e 20
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Simulations and Results

• Manual deployment Sparse network

? Sensor Nodes Computed position ? Anchor
Nodes
(Lerr 15.52)
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Simulations and Results

• Manual deployment Sparse network

(Lerr 9.68 )
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Simulations and Results

• Manual deployment Sparse network

(Lerr 5.75 )
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Simulations and Results

• Manual deployment Dense network

(Lerr 18.63 )
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Simulations and Results

• Manual deployment Dense network

(Lerr 12.24 )
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Simulations and Results

• Manual deployment Dense network

(Lerr 43.75 )
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Simulations and Results

• Manual deployment Dense network

(Lerr 586.54 )
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Simulations and Results

• Manual deployment Dense network

(Lerr 14.92 )
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Simulations and Results

• Manual deployment Dense network

(Lerr 14.11 )
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Simulations and Results

• Manual deployment Dense network

(Lerr 11.57 )
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Simulations and Results

• Manual deployment Dense network

(Lerr 11.32 )
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Simulations and Results

• Manual deployment Dense network

(Lerr 11.54 )
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Conclusions

• Investigated positioning of anchor nodes
• Better to deploy anchor nodes at the center of
  the network
• Less linearity Better localization
• Placing at right angles
• Real situations may be different

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Future Directions

• Implementation on motes.
• Third dimension
• Time synchronization
• Mobile global events

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• Questions ?