Fei Yang, Isabelle Augé-Blum

Delivery ratio-maximized wakeup scheduling for ultra-low duty-cycled WSNs

under real-time constraints

Fei Yang, Isabelle Augé-BlumNational Institute of Applied Sciences of Lyon in the Telecommunications department

( 法國里昂國立應用科學學院 )

Computer Networks 2011

898410120 陳正昌 2011/03/28

Page: 2WMNL

Performance Evaluation

Outline

Introduction and Goals

Wakeup Scheduling Algorithm

Conclusions

Page: 3WMNL


Outline



Conclusions

Page: 4WMNL

Introduction

• WSNs have been widely used in many applications.

• The data flows of WSN applications can be mainly classified into four types

– Event-driven

– Query-driven

– Continuous

– Hybrid

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Introduction

• The characteristics of event-driven WSN applications are

– Not have data most of the time

– Have to report to the sink with real-time constraints

• Nodes spend most of the time on idle listening.

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Introduction

• Typical power consumptions for an IEEE 802.15.4 radio (CC2420).

– Transmit ： 52.2 mW

– Receive ： 56.4 mW

– Listen ： 56.4 mW

– Sleep ： 3 W

• Sensor nodes are battery-powered

– Energy saving is an important issue in WSNs.

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Introduction

• Duty-cycled approach can prolongs the sensor lifetime.

…Time

Scheduling period

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Introduction

• Duty-cycle will negatively affect other performances

– End-to-end delay

– Connectivity

• Although some existing scheduling algorithms can reduce the end-to-end delay

– Didn’t takes routing into account

– Didn’t have a bounded delay

– Didn’t takes unreliable links into account

Page: 9WMNL

Goals

• Proposes a novel forwarding scheme for ultra-low duty-cycle WSNs.

– Improve the energy efficiency

– Decrease end-to-end delay

– Increase delivery ratio

– Guarantee bounded delay on the messages

– Distributed scheduling

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Outline



Conclusions

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…Time

Network Assumptions

• All nodes are locally synchronized with their neighbors.

• Only one node sends the alarm when the event happens.

• One duty-cycle period is divided into many slots and have same duration.

• Each node wakes up for only one slot during one period.

• The node can wake up for more than one slot when it has packets to send.

B B BA A A

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Basic Idea

Sink

…

Time

…

31 slots

Slots1~5

Slots6~10

Slots11~15

Slots16~20

Slots21~25

Slots26~30

Slot 31

0.9

0.8

0.7

0.6

0.5

Slot 1

Slot 2

Slot 3

Slot 4

Slot 5

Expected Delivery Ratio

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Expected Delivery Ratio (EDR)

1

01

1k

jnn

r

kni jkk

PPEDRFEDR

Hop Count (HC)

otherwise

&&1 if

11 jjj nn

ni

ni

nni

LQHCHC

HC

HCHC

Page: 14WMNL

∞∞


Hop Count (HC)

otherwise

&&1 if

11 jjj nn

ni

ni

nni

LQHCHC

HC

HCHC

D

A

B

Sink

Cα=0.5

0.9

0.8

0.3

0.8

0.8 0.6

1

0

1

3

2 ∞∞

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1

01

1k

jnn

r

kni jkk

PPEDRFEDR

D

A

B

SinkC

0.7

0.4

0.6

0.6

0.7

0.8

100

95

94

93

π(FD)={B, C, A}

EDR(π(FD))=

0.6*0.4

+(1-0.6)*0.7*0.6

+(1-0.6)*(1-0.7)*0.8*0.7

=0.4752

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1

01

1k

jnn

r

kni jkk

PPEDRFEDR

D

A

B

SinkC

0.7

0.4

0.6

0.6

0.7

0.8

100

93

94

95

π(FD)={A, C, B}

EDR(π(FD))=

0.8*0.7

+(1-0.8)*0.7*0.6

+(1-0.8)*(1-0.7)*0.6*0.4

=0.6584 > 0.4752

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1

01

1k

jnn

r

kni jkk

PPEDRFEDR

Hop Count (HC)

otherwise

&&1 if

11 jjj nn

ni

ni

nni

LQHCHC

HC

HCHC

Wakeup Slot (WS) Selection

iii EDRSRHCSRTWS 1

Selectable Range (SR)

upboundHC

TSR …

Time

…

T

Page: 18WMNL



1

01

1k

jnn

r

kni jkk

PPEDRFEDR

Hop Count (HC)

otherwise

&&1 if

11 jjj nn

ni

ni

nni

LQHCHC

HC

HCHC


i

upboundi

upboundi EDR

HC

THC

HC

TTWS 1

0~1

1 , i

upboundi

upboundi HC

HC

TTHC

HC

TTWS

Page: 19WMNL

Wakeup Scheduling AlgorithmWakeup Slot (WS) Selection

i

upboundi

upboundi EDR

HC

THC

HC

TTWS 1

Sink

HC=1HC=2HC=3HC=4HC=5HC=6

HCupbound=6

54 slots

…Time0 8 9 17 18 26 27 35 36 44 45 53

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Wakeup Scheduling AlgorithmWakeup Slot (WS) Selection

i

upboundi

upboundi EDR

HC

THC

HC

TTWS 1

SinkB

C

A

HC=5HC=6

HCupbound=6

54 slots

…Time0 8 9 17 18 26 27 35 36 44 45 53

EDRC=0.6

EDRB=0.4

EDRA=0.8 102.099 AWS

146.099 BWS

124.099 CWS

Slot T

(HC=0, EDR=1)

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Distributed Wakeup Scheduling

Sink broadcasts a packet that includes its

　　 EDR(1), WS(T) and HC(0)

Every node except the sink runs the following algorithm

if receives a packet from one of the neighbors

　 Calculates the new HC

　 Calculates the new EDR

　 if the change of EDR is higher than a threshold

　　　 or the HC is changed

　　 Calculates the new WS

　　 Broadcasts the new values

　 endif

endif


1

01

1k

jnn

r

kni jkk

PPEDRFEDR

Hop Count (HC)

otherwise

&&1 if

11 jjj nn

ni

ni

nni

LQHCHC

HC

HCHC


i

upboundi

upboundi EDR

HC

THC

HC

TTWS 1

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Sink

…

Time

…

54 slots

Slots45~53

(HCi, EDRi, WSi)

(0, 1, 54)

(1, 0.95, ∞)

(1, 0.9, ∞)

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(1, 0.95, 47)

(1, 0.9, 50)


Sink

…

Time

…

54 slots

Slots36~44

Slots45~53

(HCi, EDRi, WSi)

(0, 1, 54)

(2, 0.92, ∞)

(2, 0.9, ∞)

(2, 0.88, ∞)

(2, 0.86, ∞)

(2, 0.92, 38)

(2, 0.9, 39)

(2, 0.88, 40)

(2, 0.86, 41)

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(1, 0.95, 47)

(1, 0.9, 50)


Sink

…

Time

…

54 slots

Slots27~35

Slots36~44

Slots45~53

(HCi, EDRi, WSi)

(0, 1, 54)

(2, 0.92, 38)

(2, 0.9, 39)

(2, 0.88, 40)

(2, 0.86, 41)

(3, 0.89, ∞)

(3, 0.88, ∞)

(3, 0.85, ∞)

(3, 0.83, ∞)

(3, 0.8, ∞)

(3, 0.89, 28)

(3, 0.88, 29)

(3, 0.85, 31)

(3, 0.83, 32)

(3, 0.8, 33)

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(3, 0.89, 28)

(3, 0.88, 29)

(3, 0.85, 31)

(3, 0.83, 32)

(3, 0.8, 33)

(1, 0.95, 47)

(1, 0.9, 50)


Sink

…

Time

…

54 slots

Slots0~8

Slots9~17

Slots18~26

Slots27~35

Slots36~44

Slots45~53

(HCi, EDRi, WSi)

(0, 1, 54)

(2, 0.92, 38)

(2, 0.9, 39)

(2, 0.88, 40)

(2, 0.86, 41)

(4, 0.85, 19)

(4, 0.83, 20)

(4, 0.82, 21)

(4, 0.78, 23)

(4, 0.76, 24)

(5, 0.80, 11)

(5, 0.78, 12)

(5, 0.76, 13)

(5, 0.75, 14)

(5, 0.73, 16)

(6, 0.75, 2)

(6, 0.73, 3)

(6, 0.70, 5)

(6, 0.68, 6)

(6, 0.6, 7)

Page: 26WMNL

(3, 0.89, 28)

(3, 0.88, 29)

(3, 0.85, 31)

(3, 0.83, 32)

(3, 0.8, 33)

(1, 0.95, 47)

(1, 0.9, 50)


Sink

…

Time

…

54 slots

Slots0~8

Slots9~17

Slots18~26

Slots27~35

Slots36~44

Slots45~53

(HCi, EDRi, WSi)

(0, 1, 54)

(2, 0.92, 38)

(2, 0.9, 39)

(2, 0.88, 40)

(2, 0.86, 41)

(4, 0.85, 19)

(4, 0.83, 20)

(4, 0.82, 21)

(4, 0.78, 23)

(4, 0.76, 24)

(5, 0.80, 11)

(5, 0.78, 12)

(5, 0.76, 13)

(5, 0.75, 14)

(5, 0.73, 16)

(6, 0.75, 2)

(6, 0.73, 3)

(6, 0.70, 5)

(6, 0.68, 6)

(6, 0.6, 7)

12 20 29 39 47

54

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Outline



Conclusions

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Simulation Parameters

Simulator WSNet

Deploy Nodes 250 nodes

Network Size 150m * 150m

Slots 750, 1000, 2000, 3000 slots

Hop Count Bound 10 hops

Run Time 100

Modulation FSK

Data Rate 19.2 kbps

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Performance metrics

Delivery Ratio

End-to-End Delay

Energy Consumption

Impact factor

Density and Link Quality

Duty Cycle

Sink Position

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Experiments

Experiment 1 Each node only considers the neighboring nodes with the lower HC

Experiment 2Every node considers the neighboring nodes with not only the lower HC but also the

same HC

Sink

HC=1HC=2HC=3HC=4HC=5HC=6

Page: 31WMNL


Comparison

WSEDR

Random

i

upboundi

upboundi EDR

HC

THC

HC

TTWS 1

random

HC

THC

HC

TTWS

upboundi

upboundi

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Delivery Ratio (Duty-Cycle ： 0.1%, Sink Location ： (75,75))

Experiment 1 Experiment 2

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Delivery Ratio (α ： 0.3, Sink Location ： (75,75))



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Delivery Ratio (Density ： 29 neighbors, α ： 0.3, Duty-Cycle ： 0.1%)



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End-to-End Delay (Duty-Cycle ： 0.1%, Sink Location ： (75,75))



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End-to-End Delay (α ： 0.3, Sink Location ： (75,75))



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End-to-End Delay (Density ： 29 neighbors, α ： 0.3, Duty-Cycle ： 0.1%)



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Energy Consumption (Duty-Cycle ： 0.1%, Sink Location ： (75,75))



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Energy Consumption (α ： 0.3, Sink Location ： (75,75))



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Energy Consumption (Density ： 29 neighbors, α ： 0.3, Duty-Cycle ： 0.1%)



Page: 41WMNL


Outline



Conclusions

Page: 42WMNL

Conclusion

• Proposes a novel forwarding scheme for ultra-low duty-cycle WSNs.

– Improve the energy efficiency

– Decrease end-to-end delay

– Maximizes the delivery ratio

– Distributed scheduling

– Highly suitable for ultra-low duty-cycle real-time event-driven WSN

Page: 43WMNL

Thanks~~~Thanks~~~Thanks~~~

Documents

Fei Yang, Isabelle Augé-Blum