kaist adaptive triangular deployment algorithm for unattended mobile sensor networks suho yang...

KAIST

Adaptive Triangular Deployment Adaptive Triangular Deployment Algorithm Algorithm

for Unattended Mobile Sensor Networksfor Unattended Mobile Sensor Networks

Suho Yang(September 4, 2008)

Ming Ma, Yuanyuan Yang

IEEE Transactions On Computers 2007

Adaptive Triangular Deployment Algorithm for Unattended MSNs / 29/ 29

ContentsContents

Introduction

Assumption

Ideal Node Layout for Maximum Coverage

Two Triangular algorithmsBasic Triangular Algorithm

ATRI : Adaptive Triangular algorithm

Performance Evaluation

Conclusion

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Wireless Sensor NetworksApplications: military, environmental, health, home, commercial, …

Strong points

Small in size

Low cost → can be densely deployed

Weak points

Low computational capacities and memory

Short communication range

Low power consumption requirement: the most important metric

Other features

Wireless communication

Collaborative effort

Fault tolerance

IntroductionIntroduction


Deployment problem for WSNProblem 1: “Where to place sensors?”

To maximize sensing coverage (using a certain number of sensors)

=To minimize coverage gaps and overlaps

→ Propose the ideal node layout for maximum coverage

Problem 2: “How to move sensors?”

To minimize the total energy consumption to move sensors

→ Propose a distributed greedy heuristic algorithm

IntroductionIntroduction


AssumptionsAll sensors are mobile sensors

All sensors have the same capacities (=sensing range, energy, …)

Omni-directional sensing

No global information

No location-awarenessEach sensor only estimate the relative locations to neighbors

Initially, all sensors are randomly deployed

AssumptionAssumption


Problem 1: “Where to place sensors?”Problem 1: “Where to place sensors?”- Ideal Node Layout for Maximum Coverage- Ideal Node Layout for Maximum Coverage

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The optimal node layout for the maximum no-gap coverage

Equilateral triangulation

Ideal Node Layout for Maximum CoverageIdeal Node Layout for Maximum Coverage


ProofThe maximum value of can be obtained when

In this case, the lengths of all three edges =

88

Ideal Node Layout for Maximum CoverageIdeal Node Layout for Maximum Coverage

2

3r

r6

r3


Problem 2: “How to move sensors?”Problem 2: “How to move sensors?”- Basic Triangular Deployment Algorithm- Basic Triangular Deployment Algorithm

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Main ideaEach node divides the transmission circle into six sectors

And adjusts the relative distance to its one-hop neighbors in each sector separately

Basic Triangular Deployment AlgorithmBasic Triangular Deployment Algorithm


Adjusting the distance between neighbors Notation


rR 3where r = sensing range


Adjusting the distance between neighbors (cont.)




1313




1414


1v

2v

3v

4v

5v

6v


Algorithm

1515



Snapshots of the execution



Reducing node oscillation(1) Distance threshold strategy

Constant threshold

Variable threshold



Reducing node oscillation(2) Movement state diagram strategy



Problem 2: “How to move sensors?”Problem 2: “How to move sensors?”- - ATRI: Adaptive Triangular Deployment AlgorithmATRI: Adaptive Triangular Deployment Algorithm

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Additional consideration 1. Avoiding obstacles and boundaries

2. Non-uniform deployment

ATRI: Adaptive Triangular Deployment ATRI: Adaptive Triangular Deployment AlgorithmAlgorithm


1. Avoiding obstacles and boundariesDetect them with an ultrasonic obstacle-detecting module

And abstract them as virtual nodes



Snapshots of the execution for the environment with obstacles



2. Non-uniform deployment The density of nodes can be adjusted adaptively to different requirements of tasks

Strategy: set a shorter sensing range in important area



Snapshots of the execution for non-uniform deployment



Performance EvaluationPerformance Evaluation

Measurement of performanceDeployment quality: total coverage area

Moving energy consumption: moving distance

Comparison with VEC in [G. Wang, G. Cao, and T. La Porta, “Movement-Assisted Sensor Deployment,” INFOCOM, 2004]

2525



Total coverage area gets larger

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Average moving distance gets smaller

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The optimal node layout for maximum coverageEquilateral triangulation (the length of each side equals )

Basic Triangular AlgorithmDivides the transmission circle into six sectors and adjust the relative distance between neighbors

For reducing node oscillationDistance threshold strategy

Movement state diagram strategy

Adaptive Triangular algorithmAvoiding obstacles and boundaries

Abstract them as virtual nodes

Non-uniform deploymentSet a shorter sensing range in important area

ConclusionConclusion

r3


The lack of mentions aboutRelation between communication range and sensing range

Definition of some notations

The meaning of some equations

Termination condition

No consideration aboutCommunication overhead

Deployment time

Impact of threshold

Synchronization and collision

DiscussionDiscussion


Thank youThank you

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[1] I. Akyildiz, W. Su, Y. Sankarasubramaniam, and E. Cayirci, “Wireless Sensor Networks: A Survey,” Computer Networks, 2002.[2] G. Wang, G. Cao, and T. La Porta, “Movement-Assisted Sensor Deployment,” INFOCOM, 2004

ReferencesReferences


What is Delaunay Triangulation?

Appendix A: Delaunay TriangulationAppendix A: Delaunay Triangulation


Minimum average moving distance

Proof

3333

Appendix B: Minimum average moving Appendix B: Minimum average moving distancedistance

kaist adaptive triangular deployment algorithm for unattended mobile sensor networks suho yang...

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