Barrier Coverage with Mobile Sensors

Changxiang Shen Weifang ChengXiangke Liao Shaoliang Peng

National University of Defense Technology

Proceedings of the International Symposium on Parallel Architectures, Algorithms and Networks

I-SPAN 2008

OutlineOutline

IntroductionIntroduction Problem FormulationProblem Formulation CBarrier algorithmCBarrier algorithm DBarrier algorithmDBarrier algorithm Performance EvaluationPerformance Evaluation ConclusionConclusion

IntroductionIntroduction

In the wireless sensor network (WSN) In the wireless sensor network (WSN) sensors monitor the field for some sensors monitor the field for some applicationapplication to monitor the entire environmentto monitor the entire environment

Full coverageFull coverage the boundary guard or the movement the boundary guard or the movement

detectiondetection Barrier coverageBarrier coverage

IntroductionIntroduction

An example An example

randomly deployed sensors for barrier coveragerandomly deployed sensors for barrier coverage

"Reliable Density Estimates for Achieving Coverage and Connectivity in Thin Strips of Finite Length" P. Balister, B. Bollobas, A. Sarkar, S. Kumar. in Proceedings ofACM MobiCom. 2007.

IntroductionIntroduction

When sensors are deployedWhen sensors are deployed Randomly Randomly

much more sensors are required than much more sensors are required than deterministically deployeddeterministically deployed

DeterministicallyDeterministically Environment limitationEnvironment limitation Cost a lot of timeCost a lot of time

This paper study barrier coverage This paper study barrier coverage with mobile sensorswith mobile sensors Relocated after random deploymentRelocated after random deployment Utilize much fewer mobile sensorsUtilize much fewer mobile sensors

Problem FormulationProblem Formulation

AssumptionAssumption N mobile sensorN mobile sensor

S={S={ss11,s,s22,…,s,…,sNN}} Each sensor sEach sensor sii has initial coordinates has initial coordinates ((xxii,y,yii)) Sensing range : Sensing range : RR

Problem FormulationProblem Formulation

The interesting area : W x LThe interesting area : W x L

L

W

(0,0)

(0,W) (L,W)

(L,0)

Minimum number :Minimum number : RL 2/

Maximum numberMaximum number

R

RL

2

22

Problem FormulationProblem Formulation

Given the randomly deployed mobile Given the randomly deployed mobile sensorssensors To provide required barrier coverageTo provide required barrier coverage

(It is not hard)(It is not hard) The sensor moving is waste energyThe sensor moving is waste energy

The paper propose an relocation The paper propose an relocation algorithmalgorithm Save energy consumptionSave energy consumption

Problem FormulationProblem Formulation22 )''()''(),( jiji yyxxjid

N

iiiii yyxx

1

22 )'()'(min

NiRjidxxj ij ...1 ))2),(()''((

NiRjidxxj ji ...1 ))2),(()''((

)'0( Rxj j

)'( LxRLj j

Goal :

There is a left neighbor

There is a right neighbor

There is a sensor overlapping the left boundary

There is a sensor overlapping the right boundary

Centralize Barrier Algorithm(CBarrier) To assume that To assume that

the relocated sensors are aligned into a straight lithe relocated sensors are aligned into a straight line y=ax+bne y=ax+b

yyii’=ax’=axii’+b’+b Order the xOrder the xii by the sort of by the sort of

xx11≤x≤x2 2 ≤≤ xx3 3 ≤≤ … ≤ x… ≤ xNN

xx11’=R , x’=R , xNN’=L-R’=L-R the xthe xii’=R+(i-1)[(L-R)-R]/(N-1)’=R+(i-1)[(L-R)-R]/(N-1)

R

WLN

2

22

Centralize Barrier Algorithm(CBarrier)

)]1/()2[(*)1(

)''(*)1(

)'')(1(

))'()'(()''(

)''()''()1,(

2

12

21

2

21

21

21

21

NRLa

xxa

xxa

baxbaxxx

yyxxiid

ii

ii

iiii

iiii

Centralize Barrier Algorithm(CBarrier)

L

W

(0,0)

(0,W) (L,W)

(L,0)LWa /

Riid 2)1,( Riid 2),1(

N

iiiii yyxxbaF

1

22 ))'()'((),(

Centralize Barrier Algorithm(CBarrier)

Distributed Barrier AlgorithmDistributed Barrier Algorithm(DBarrier)(DBarrier) The virtual forceThe virtual force

FR : repulsive forceFR : repulsive force FA : attractive forceFA : attractive force

L

W

(0,0)

(0,W) (L,W)

(L,0)

Distributed Barrier AlgorithmDistributed Barrier Algorithm(DBarrier)(DBarrier)

Distributed Barrier AlgorithmDistributed Barrier Algorithm(DBarrier)(DBarrier)

Distributed Barrier AlgorithmDistributed Barrier Algorithm(DBarrier)(DBarrier)

Distributed Barrier AlgorithmDistributed Barrier Algorithm(DBarrier)(DBarrier)

Performance EvaluationPerformance Evaluation

MATLABMATLAB Sensing range Sensing range R R : 4m: 4m Communication range Communication range RRc c : 10m: 10m Field size W x L : 15m x 60mField size W x L : 15m x 60m The number of sensor :15The number of sensor :15 Move unit :0.1m~0.8mMove unit :0.1m~0.8m MAX_STEP = 100MAX_STEP = 100

Performance EvaluationPerformance Evaluation

Performance EvaluationPerformance Evaluation

ConclusionConclusion

This paper discusses the MEBC problem This paper discusses the MEBC problem and propose two algorithmand propose two algorithm The CBarrier algorithmThe CBarrier algorithm

To compute the relocated position with knowing To compute the relocated position with knowing the initial positionthe initial position

The DBarrier algorithmThe DBarrier algorithm Sensors adjust the position according the total vSensors adjust the position according the total v

irtual forceirtual force