[email protected] Approximations for Min Connected Sensor Cover Ding-Zhu Du University of Texas...

36
[email protected] Approximations for Min Connected Sensor Cover Ding-Zhu Du University of Texas at Dallas

Transcript of [email protected] Approximations for Min Connected Sensor Cover Ding-Zhu Du University of Texas...

lidongwuutdallasedu

Approximations for Min Connected Sensor Cover

Ding-Zhu DuUniversity of Texas at Dallas

Outline

I Introduction

II Two Approximations

III Final Remarks

Have you watched movie Twister

sensorBucket ofsensors

tornado

Where are all the sensors

Smartphone with a dozen of sensors

Where are all the sensors

Wearable devices - Google Glass Applersquos iWatch

Buildings

Where are all the sensors

Transportation systems etc

Where are all the sensors

Sensor Web

Large of simple sensors Usually deployed randomly Multi-hop wireless link Distributed routing No infrastructure Collect data and send it to base station

Applications of Senor Web

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Outline

I Introduction

II Two Approximations

III Final Remarks

Have you watched movie Twister

sensorBucket ofsensors

tornado

Where are all the sensors

Smartphone with a dozen of sensors

Where are all the sensors

Wearable devices - Google Glass Applersquos iWatch

Buildings

Where are all the sensors

Transportation systems etc

Where are all the sensors

Sensor Web

Large of simple sensors Usually deployed randomly Multi-hop wireless link Distributed routing No infrastructure Collect data and send it to base station

Applications of Senor Web

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
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  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Have you watched movie Twister

sensorBucket ofsensors

tornado

Where are all the sensors

Smartphone with a dozen of sensors

Where are all the sensors

Wearable devices - Google Glass Applersquos iWatch

Buildings

Where are all the sensors

Transportation systems etc

Where are all the sensors

Sensor Web

Large of simple sensors Usually deployed randomly Multi-hop wireless link Distributed routing No infrastructure Collect data and send it to base station

Applications of Senor Web

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Slide 7
  • Slide 8
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Slide 17
  • Slide 18
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Where are all the sensors

Smartphone with a dozen of sensors

Where are all the sensors

Wearable devices - Google Glass Applersquos iWatch

Buildings

Where are all the sensors

Transportation systems etc

Where are all the sensors

Sensor Web

Large of simple sensors Usually deployed randomly Multi-hop wireless link Distributed routing No infrastructure Collect data and send it to base station

Applications of Senor Web

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
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  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Where are all the sensors

Wearable devices - Google Glass Applersquos iWatch

Buildings

Where are all the sensors

Transportation systems etc

Where are all the sensors

Sensor Web

Large of simple sensors Usually deployed randomly Multi-hop wireless link Distributed routing No infrastructure Collect data and send it to base station

Applications of Senor Web

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Slide 7
  • Slide 8
  • Slide 9
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  • Slide 14
  • Slide 15
  • Slide 16
  • Slide 17
  • Slide 18
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Buildings

Where are all the sensors

Transportation systems etc

Where are all the sensors

Sensor Web

Large of simple sensors Usually deployed randomly Multi-hop wireless link Distributed routing No infrastructure Collect data and send it to base station

Applications of Senor Web

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Slide 7
  • Slide 8
  • Slide 9
  • Slide 10
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  • Slide 13
  • Slide 14
  • Slide 15
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  • Slide 17
  • Slide 18
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Transportation systems etc

Where are all the sensors

Sensor Web

Large of simple sensors Usually deployed randomly Multi-hop wireless link Distributed routing No infrastructure Collect data and send it to base station

Applications of Senor Web

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Slide 7
  • Slide 8
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Slide 17
  • Slide 18
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Sensor Web

Large of simple sensors Usually deployed randomly Multi-hop wireless link Distributed routing No infrastructure Collect data and send it to base station

Applications of Senor Web

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
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  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Applications of Senor Web

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Slide 7
  • Slide 8
  • Slide 9
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  • Slide 14
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  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

observerAn example of sensor web

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Slide 7
  • Slide 8
  • Slide 9
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  • Slide 14
  • Slide 15
  • Slide 16
  • Slide 17
  • Slide 18
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Whatrsquos Sensor

Small size Large number Tether- lessBUThellip

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Slide 7
  • Slide 8
  • Slide 9
  • Slide 10
  • Slide 11
  • Slide 12
  • Slide 13
  • Slide 14
  • Slide 15
  • Slide 16
  • Slide 17
  • Slide 18
  • Slide 19
  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Whatrsquos limiting the task

Energy Sense Communication scale

CPU

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Challenge

Target is Covered

Sensor system is Connected

Coverage amp Connectivity

Golden Rule then we say

System is alive

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
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  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

sensor

target

communication radius

sensing radius

Rc

Rs

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
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  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Coverage amp Connectivity

Communication Range

Sensing Range

d le Rs

d le Rc

sensor

target

communication radius

sensing radius

Rc

Rs

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
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  • Slide 5
  • Slide 6
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  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Min-Connected Sensor Cover Problem

Figure Min-CSC Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

[Resource Saving]

communicationnetwork

sensing disks

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

  • Slide 1
  • Slide 2
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Slide 7
  • Slide 8
  • Slide 9
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  • Slide 20
  • Slide 21
  • Slide 22
  • Slide 23
  • Slide 24
  • Slide 25
  • Slide 26
  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

Previous Work for PTAS

Itrsquos NP-hard

Ο(r ln n) ndash approximation given by Gupta Das and Gu [MobiHocrsquo03 2003] where n is the number of sensors and r is the link radius of the sensor network

Min-Connected Sensor Cover Problem

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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  • Slide 35
  • Slide 36

Outline

I Introduction

II Two Approximations

III Final Remarks

Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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Main Results

Random algorithm

Ο(log3n log log n)-approximation n is the

number of sensors

Partition algorithm

Ο(r)-approximation r is the link radius of the

network

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

With a random algorithm which with probability 1- ɛ produces an Ο(log3n log log n) - approximation

1

Algorithm 1

Group

Steiner Tree

2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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1 2Min-CSC Min-CTC GST

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • Slide 27
  • Slide 28
  • What Is Link Radius
  • Slide 30
  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Sensor Cover Problem

A uniform set of sensors and a target area

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target area and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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1 2Min-CSC Min-CTC GST

How to map to GST

Min-Connected Target Coverage Problem

A uniform set of sensors and a target POINTS

Find a minimum of sensors

to meet two requirements

[Coverage] cover the target POINTS and

[Connectivity] form a connected communication network

1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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1 2Min-CSC Min-CTC GST

A graph G = (V E) with positive edge weight c for every edge e isin E

k subsets (or groups) of vertices G1Gk Gi sube V

Find a minimum total weight tree T contains at least one vertex in each Gi

Group Steiner Tree

Figure GST ProblemThis tree has minimum weight

1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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1 2Min-CSC Min-CTC GST

Choose at least one sensor from each group

Coverage

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Consider communication network

Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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1 2Min-CSC Min-CTC GST

b3

b1

b2

b6

b5

b4

S1S2

S3S4

b7

Find a group Steiner tree in communication network

Min-Coverage amp Connectivity

b2 b6b3 b4b1 b5 b7

S1 S2

S1 S3

S1 S2 S3

S2 S3

S2 S4

S3 S4

Gi contains all sensors covering bi

S2 S3 S4

1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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  • Slide 32
  • Slide 33
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1 2Min-CSC Min-CTC GST

Garg Konjevod and Ravi [SODA 2000] showed with probability 1- ε an approximation solution of GROUP STEINER TREE on tree metric T is within a factor of Ο(log2 n log log n log k) from optimal

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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  • Slide 31
  • Slide 32
  • Slide 33
  • Slide 34
  • Slide 35
  • Slide 36

What Is Link Radius

3 example In this onintersecti sensing

nonempty having sensors twoof distancefor boundupper least theis radiuslink

r

r

Communication disk

Sensing disk

Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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Connected

Sensor Cover with Target

Area

Connected

Sensor Cover

with Target Points

Connect output of Min-TC into Min-CTC It can be done in Ο(r) - approximation

1

Algorithm 2

2Min-CSC Min-CTC Min-TC

Refer to Lidong Wursquos paper [INFOCOM 2013rsquo]

There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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There exists a polynomial-time (1 + ε)- approximation for MIN-TC

Green is an opt (CTC)

Red is an approx (TC)

lt (1+ε) opt (TC) lt (1+ε) opt (CTC)

Step 2 Target Coverage

Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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Byrka et al [6] showed there exists a polynomial-time139-approximation of for Network Steiner Minimum Tree

Green is an opt (CTC)

Red is an approx (TC)

Step 2 Network Steiner Tree

Let Sprime sube S be a (1 + ε)-approximation for MIN-TC Assign

weight one to every edge of G Interconnect sensors in Sprime to

compute a Steiner tree T as network Steiner minimum tree

All sensors on the tree form an approxfor min CTC

nodes approx for min CTC= edges +1 approx for Network STlt 139 opt (Network ST) +1lt 139 opt (CTC) + 1

Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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Step 2 Network Steiner Tree

Green is an opt (CTC)

Red is an approx (TC)

Each orange line has distance lt r

opt (Network ST)

lt opt (CTC) -1 + r = opt (CTC) O(r)

Note lt (1+ε) opt (CTC)

Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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Outline

I Introduction

II Two Approximations

III Final Remarks

Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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  • What Is Link Radius
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Future Works

Ο(log3n log log n)

n is the number of sensors

1 Unknown Relationship

2 Constant-appro for Min-CSC

Ο(r)

r is the link radius

THANK YOU

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THANK YOU

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