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Dynamic Object Tracking in Wireless Sensor Networks
Tzung-Shi Chen1, Wen-Hwa Liao2, Ming-De Huang3, and Hua-Wen Tsai4
1 National University of Tainan, Dept. Information and Learning Technology2 Tatung University, Dept. Information Management
3 Chang Jung Christian University, Dept. Information Management4 National Cheng-Kung University, Dept. CSIE
Wang, Sheng-ShihWang, Sheng-ShihDec. 26, 2005Dec. 26, 2005
IEEE International Conference on Networks (ICON 2005)
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Outline
• Introduction• Movement Object Tracking• Simulation• Conclusion
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Introduction
• Motivations Target tracking is an important issue in WSNs
• Enemy vehicle tracking, habitat monitoring, etc Cooperation of multiple sensors
• Objectives Mobile object tracking
• Accurate• Quick• Energy efficiency
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Movement Object Tracking --- Overview
A
F1
F3
F6
F7
F10
F2 F11
F12
F13
source
mobile target
ingress node
sensor
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Movement Object Tracking --- Operation
• Target discovery• Mobile target detection• Target tracking• Track improvement
Face track adjustment Loop face track adjustment
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Target Discovery
Target enters the network
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Target Discovery (cont’d)
Three sensor nodes detect the target
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Target Discovery (cont’d)
Where ?
Three sensor nodes build their corresponding faces
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Target Discovery (cont’d)
querypacket
Source sends a query packet to discover the target
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Target Discovery (cont’d)
replypacket
• state active• active time infinite
Ingress nodeThe sensor closest to the target replies the packet to the source
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Target Discovery (cont’d)
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Mobile Target Detection
wak
eup
Wakeup packet• ingress id (node A)• face hop count (1)
A
B
Node A is the 1st ingress node
wakeup
wakeup
wakeup
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Mobile Target Detection (cont’d)
wak
eup
Wakeup packet• ingress id (node A)• face hop count (1)
A
B
Node A is the 1st ingress node
wakeup
wak
eup
wakeup
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Mobile Target Detection (cont’d)
A
B
Target may enter face F0, F2, or F5
F2
F5
F0
F1
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Mobile Target Detection (cont’d)
A
B
Node B sends the wakeup packets to all of its neighboring face nodes (F1, F2, F3, F4, and F5) Node A knows that node B is the next ingress node
F2
F3
F4
F1
F0
F5
Node B is the 2nd ingress node
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Mobile Target Detection (cont’d)
A
BF2
F3
F4
F1
active time expires go to sleep
F0
F5
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Target Tracking
A
B
C
D
• Node A knows the next ingress node (node B)• Node B knows the next ingress node (node C)• Node C knows the next ingress node (node D)
• Source knows the 1st ingress node (node A)
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Face Track Adjustment
A
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Face Track Adjustment (cont’d)
AG
B
C
D
E
F
• Track : <A, B, C, D, E, F> (F1, F2, F3, F6, F7, F8, F9)• Face hop count = 7
Not optimaltrack
F1
F2
F3
F4
F5
F6
F7
F8
F9
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Face Track Adjustment (cont’d)
AG
B
C
Optimal track : <A, G, F>
F1
F3
F4
F5
F6
F7
F8
F9F
D
EF2
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Face Track Adjustment (cont’d)
AG
B
C
F1
F3
F4
F5
F6
F7
F8
F9
if (face hop count = k)then send infoadj packet to the last checkface (node A)
F
D
EF2
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Face Track Adjustment (cont’d)
AG
B
C
F1
F3
F4
F5
F6
F7
F8
F9F
D
EF2
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Face Track Adjustment (cont’d)
AG
B
C
F1
F3
F4
F5
F6
F7
F8
F9F
D
E
The ingress nodes, B, C, D, and E, are canceled
F2
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Face Track Adjustment (cont’d)
AG
B
C
Node A finds the next ingress node closest to the kth ingress node (F),and then sends an adjustment packet to the next ingress node
F1
F3
F4
F5
F6
F7
F8
F9F
D
E
adjustment adjustment
F2
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Loop Face Track Adjustment
AG
B
C
F1
F3
F4
F5
F6
F7
F8
F9
D
EF2
F
H
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Loop Face Track Adjustment (cont’d)
AG
B
C
F1
F3
F4
F5
F6
F7
F8
F9
D
EF2
• Track : <A, B, C, D, E, F, H> (F1, F2, F3, F6, F7, F8, F9, F4, F3)
F
H
loop
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Loop Face Track Adjustment (cont’d)
A
H
B
C
F1
F3
F4
F5
F6
F7
F8
F9
F
D
EF2
• Node C receives the wakeup packet from node H and detects the loop, node C sends a deletion packet to node H
deletionG
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Loop Face Track Adjustment (cont’d)
AG
B
C
F1
F3
F4
F5
F6
F7
F8
F9
D
EF2
F
H
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Simulation Model
• ns-2 simulator• Sensing field: 500 m 500 m• 1000 sensor nodes (random deployment)• Communication range = sensing range = 25
m• Power
Tx = Rx = 175 mW Initial: 5 joule
• Moving speed Target: 20 m/s Source: 10 m/s, 20 m/s, or 30 m/s
• Simulation time: 2000 secs
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Simulation --- Comparison
• Threshold Flooding (TF) When the source reaches the location of the
target, target discovery process is executed again• Schedule Flooding (SF)
The source executes the target discovery process every 2 secs
• Schedule Updating (SU) The source queries once The sensor which detects the target sends the
update message to the source every 2 secs• Proposed Object Tracking scheme (OT)
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Simulation Result --- First Catching Time
infrequent query flooding and face track adjustment
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Simulation Result --- Energy Consumption
• before the first catch • after the first catch
flooding-based
less query flooding
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Simulation Result --- Lifetime
query packet is required although the source is near the target
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Conclusion
• Target tracking protocol Dynamic Energy efficiency Shorter tracking path Loop avoidance