KAIS T Sensor Deployment Based on Virtual Forces Reference: Yi Zou and Krishnendu Chakarabarty, “Sensor…

KAIST

Sensor Deployment Based on Virtual Forces

Reference: Yi Zou and Krishnendu Chakarabarty, “Sensor Deployment and Target Localization Based on Virtual Forces”, Department of Electrical and Computer Engineering, Duke University, IEEE INFOCOM 2003

2007. 10. 4Hong Jae-Young

22/18/18Sensor Deployment Based on VFA

Contents

Introduction

Related Prior Work

Virtual Force Algorithm

Simulation Results

Conclusion


Introduction

The effectiveness of distributed sensor networks (DSN)Depends on the sensor deployment

Coverage, communication cost, resource management

Random deployment

Practical for military applications

Not always lead to effective coverage

New sensor placement strategyMaximize the coverage for a given number of sensors

Virtual Force Algorithm (VFA) as a sensor deployment of sensors

Enhance the coverage after initial random placement of sensors


Related Prior Work

A variety of work for Sensor deployment problemsA bidding Protocol for Deploying Mobile Sensor

Sensor Deployment and Sensor Planning for Elusive Targets A priori knowledge about possible target

No information about potential target

Mobile Sensor Network Deployment Using Potential FieldEach robot is a sensor node

Expensive and a large amount of computation

Coverage problems in wireless ad-hoc sensor networksSelf-localization

Sensor nodes are should be highly mobile and move frequently

Radar and sonar coverage


Virtual Force Algorithm : VFA (1/7)

Basic assumptionsAfter the initial random deployment, all sensor nodes are able to

communicate with the cluster head

The cluster head is responsible for executing the VFA and managing the

one-time movement of sensors to the desired locations

Basic idea of VFAEach sensor behaves as a “Source of force” for all other sensors

Positive (Attractive) vs. Negative (Repulsive)

Globally uniform sensor placement



Sensor Detection ModelsConsider an n by m sensor field grid

K sensor deployed in the random deployment stage

Each sensor has a detection range r

Let si deployed at point (xi , yi), any point P at (x , y)

22 y)(yx)(x,P)d(s ii i

Binary Sensor Detection Model

Probabilistic Sensor Detection Model

r

n

m

rr

P (x , y)



Virtual ForcesNotation

Let the total force action on sensor si be denoted by

Let the force exerted on si by another sensor sj be denoted by

Let total repulsive force on si by

Let total attractive force on si by

Virtual force calculation in the VFATotal force on si,

iF

ijF

iAFiRF

iF

k

ijjiAiRiji FFFF

,1



An example of virtual forces with four sensors

1413121 FFFF

If we assume that d12>dth , d13<dth , d14=dth ,s2 exerts an attractive force on s1,s3 exerts a repulsive force on s1,s4 exerts no force on s1

If re=0 then Binary sensor detection modelMake dij as close to 2r as possible



Non-overlapped and overlapped sensor coverage areas

Non-overlapped area Overlapped area

Non-overlapped areaMinimize “wasted overlap”

A few grid points are not covered by any sensor

Overlapped areaMore sensors for grid coverage

Therefore, adopt the Non-overlapped areaTotal Coverage area is 2rk



If re>0, re is not negligible

Probabilistic Sensor Detection Model

Grid points are not covered with the same probability

Necessary overlap sensor detection areas

))(1))((1(1),( ,,, jyxiyxjiyx scscssc

ovi Ss

iyxovyx scsc ))(1(1)( ,,



Coverage Evaluation

Virtual Forces among sensors

Move sensor virtually


Simulation Results (1/5)

ParametersA total of 20 sensors

Random placement

Detection radius as 5 unit (r=5)

Large detection error as 3 unit (re=3)

50 by 50 sensor field

Pentium III 1.0GHz PC using MATLAB









Probabilistic sensor detection model




Conclusion

Virtual Force Algorithm Practical approach for sensor deployment

Advantages

Negligible computation timeSmall amount of computation

One time repositioning of the sensorsLow-cost


Questions & Comments

Any Questions?Comments?

KAIS T Sensor Deployment Based on Virtual Forces Reference: Yi Zou and Krishnendu Chakarabarty, “Sensor…

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