Post on 27-Dec-2015
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Wireless Sensor Networking for “Hot” Applications: Effects of Temperature on Signal Strength, Data
Collection and Localization
Kenneth Bannister, Gianni Giorgetti, Sandeep K.S. Gupta
HotEmnets’08 – Charlottesville – 3 June 2008
IMPACT LABhttp://IMPACT.ASU.EDU
http://www.IMPACT.asu.edu
Outline
• Signal Strength Observations• Lab Experiments• Effect of Temperature on:
• Link Budget and Communication Range• Network Connectivity and Data Collection• Localization
• Conclusions and Future Work
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Environmental MonitoringDaily Variations in RSS
The “SMART” Container
“SMART” Container Project Daily Variations in RSS
Botanical Garden, Phoenix, AZ
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Correlation With Temperature
The “SMART” Container
“SMART” Container Project
Botanical Garden, Phoenix, AZRSS
TEMP
RSS
TEMP
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Outline
• Signal Strength Observations• Lab Experiments• Effect of Temperature on:
• Link Budget and Communication Range• Network Connectivity and Data Collection• Localization
• Conclusions and Future Work
http://www.IMPACT.asu.edu
25 30 35 40 45 50 55 60 65
-62
-60
-58
-56
-54
Heated Transmitter
Temperature [C]
RS
S [
dBm
]
25 30 35 40 45 50 55 60 65
-62
-60
-58
-56
-54
Heated Transmitter
Temperature [C]
RS
S [
dBm
]
25 30 35 40 45 50 55 60 65
-62
-60
-58
-56
-54
Heated Transmitter
Temperature [C]
RS
S [
dBm
]
Experimental Setup & Results
Temperature at the Transmitter/RSS
Effects of temperature on the transmitter
AttenuatorsThermal Chamber
POWER AMPLIFIER
RX Section of the CC2420
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25 30 35 40 45 50 55 60 65
-62
-60
-58
-56
-54
Heated Receiver
Temperature [C]
RS
S [
dBm
]
Temperature Effects on the ReceiverEffects of temperature on the receiver
25 30 35 40 45 50 55 60 65
-62
-60
-58
-56
-54
Heated Receiver
Temperature [C]
RS
S [
dBm
]
25 30 35 40 45 50 55 60 65
-62
-60
-58
-56
-54
Heated Receiver
Temperature [C]
RS
S [
dBm
]
RX Section of the CC2420
Amplifies the RF signal from the antenna
LNA
Measures RSS
DEMODULATOR
AttenuatorsThermal Chamber
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Sensitivity
~ 3 dB
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Loss due to Temperature
-3.3 dB
-3.7 dB
-2.0 dB
-1.6 dB
TI CC2400 and CC2520 DatasheetsOutput Power vs Temperature
Sensitivity vs Temperature
Output Power vs Temperature
Sensitivity vs Temperature
Temperature (°C) Temperature (°C)
Temperature (°C) Temperature (°C)
Ou
tpu
t P
ow
er (
dB
m)
Ou
tpu
t P
ow
er (
dB
m)
Sen
siti
vity
(d
Bm
)
Sens
itivi
ty (d
Bm)
CC2400 and CC2520 DATASHEETS
CC2400
CC2400
CC2520
CC2520
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Outline
• Signal Strength Observations• Lab Experiments• Effect of Temperature on:
• Link Budget and Communication Range• Network Connectivity and Data Collection• Localization
• Conclusions and Future Work
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Link Budget Analysis
PRX(d) = P0 + 10nplog10(d0/d)
0 25 50 75 100 125 150-100
-90
-80
-70
-60
-50
-40
RS
S [d
Bm
]
Distance [m]
+ LTX(T) + LRX(T)
np =2.3
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Communication Range
Depending on the path loss model, losses due temperature cause reduction in range comprised between 40% and 60% the max. value
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Outline
• Signal Strength Observations• Lab Experiments• Effect of Temperature on:
• Link Budget and Communication Range• Network Connectivity and Data Collection• Localization
• Conclusions and Future Work
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Network Connectivity @ 25°C
Avg. Connectivity = 8.94; Connected nodes = 100%; Avg. Path Length = 2.95.
SINK NODE
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Network Connectivity @ 45°C
Avg. Connectivity = 4.57; Connected nodes = 98%. Avg. Path Length = 4.93.
Few nodes are disconnected.
SINK NODE
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Network Connectivity @ 65°C
Avg. Connectivity = 1.88; Connected nodes = 0%. The sink is disconnected from the rest of the network!
SINK NODE
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Data Collection: Summary
• Temperature steadily decreases connectivity• Failure of Critical Links can cause the sink to
become disconnected
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Outline
• Signal Strength Observations• Lab Experiments• Effect of Temperature on:
• Link Budget and Communication Range• Network Connectivity and Data Collection• Localization
• Conclusions and Future Work
http://www.IMPACT.asu.edu
Effect of Temperature on Localization
Anchors (GPS) Blind Nodes
Location awareness:• Enable Context-Aware Apps• Resource & Services Discovery• Tracking (People, Equipment,...)• Navigation Support• Security (Location-based access)
Two Approaches:• Range-Based Localization (e.g. triangulation)• Range-Free Localization (e.g connectivity)
Both Range Estimates and Connectivity can be obtained from
radio communication.
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Ranging Errors
-90-85-80-75-70-650
0.1
0.2
RSS [dBm]
d = 10 md*=11.6m
• Received power modeled by the log-normal shadowing model:• PRX(d) = PLOG-D(d) + ∆; ∆~N(0, σdB);
• Maximum Likelihood Estimate:
• Errors increase with the temperature
d* = 21.5m
-95
σdB
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Ranging Errors
Case 1Case 2Temperature will cause to over-estimate the node distances
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Effect of Connectivity on Localization
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Effect of Connectivity on Localization
1
11
1 1
1
132
2
3
4
2
2
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Range-Based Connectivity-Based
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Outline
• Signal Strength Observations• Lab Experiments• Effect of Temperature on:
• Link Budget and Communication Range• Network Connectivity and Data Collection• Localization
• Conclusions and Future Work
http://www.IMPACT.asu.edu
Conclusions and Future Work• Actual measurements only available for the
CC2420 radio. Simple model to account for temperature effects on RSS.
• Tests with other platforms in progress• Importance of including temperature sensors in
node design.• Importance of proper insulation and placement.
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Impact of Temperature on WSN Design
MCU
OS / HAL
Networking
Services
Applications
Sensors
Radio
Battery
Soft
war
eH
ardw
are
WSN Architecture
Link Budget RSS
Energy Capacity
Physical Models
Connectivity
Life-time
Networking Models
Design & Implementation
Routing / Scheduling
Data Collection
Localization
TEM
PERA
TURESource: CR2330 Datasheet
Panasonic
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Don’t forget the sunscreen! Thanks