Wireless Sensor Mote (TelosB)

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Wireless Sensor Mote (TelosB)

• Ultra low-power wireless module
• for sensor networks, monitoring app, rapid
  prototyping
• Key Features
• 2.4GHz 802.15.4 radio, 250kps
• 8MHz processor, 10k RAM, 48k Flash
• Fast wakeup (6?s)
• 1MB external flash (16 segments, each 64kB)
• Ultra low current consumption
• TinyOS support

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Some Useful Components of Mote/TOS

• Radio
• UART
• Timer (unique)
• Flash memory
• LEDs
• Sensor(s)

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Some Research Area in WSN

• Wireless Communication
• Localization
• Calibration
• Time Synchronization
• Routing (Data-Centric Routing)
• Deployment, Lifetime optimization
• Signal Processing - compression, detection
• Storage (Data-Centric Storage)
• Mobility

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Wireless Communication
Ideal model
Ganesan TR 02 Marco Zuniga et al., USC
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Wireless Communication
Empirical link behavior

• Three regions
• Connected
• Disconnected
• Transitional
• Transitional region
• Asymmetric links
• High variance space/time
• Large extent
• Significant impact on some routing
  protocols

transitional
PRR
connected
disconnected
distance (m)
Zhao SenSys 03 Woo SenSys 03 Ganesan TR
02 Aguayo SIGCOMM04 Zhou
MobiSys03
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Routing (Information Gradient-based Active
Routing)
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Routing (Information Gradient-based Active
Routing)

• Challenges
• In real life, sensors are unable to detect or
  measure the events effect below certain
  threshold. So, diffusion curve has finite tail
  - Lack of sensitivity of sensor device(s)
  - Creates flat information region
• Erroneous reading of the malfunctioning sensors
  - Due to calibration error or
  obstacle - Cause local maxima or minima
• Environmental noise

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Brief Description of Routing Approaches
Single-path Query forwarding with look-ahead, r
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Multiple-path Query forwarding
57.4
41.5
57.4
57.4
41.5
57.4
41.5
57.4
57.4
41.5
S
S
23.8
27.8
32.9
41.5
57.4
100
57.4
41.5
23.8
27.8
32.9
41.5
57.4
100
57.4
41.5
23.8
27.8
3.4
41.5
57.4
57.4
57.4
41.5
23.8
27.8
3.4
41.5
57.4
57.4
57.4
41.5
23.8
31.0
32.9
41.5
41.5
41.5
41.5
41.5
21.1
23.8
31.0
32.9
41.5
41.5
41.5
41.5
41.5
18.9
21.1
30.0
27.5
29.0
32.9
32.9
80.5
32.9
32.9
32.9
18.9
21.1
30.0
27.5
29.0
32.9
32.9
9.0
32.9
67.0
3.2
21.1
23.8
27.5
27.5
27.5
27.5
27.5
27.5
27.5
67.0
3.2
21.1
23.8
27.5
27.5
27.5
27.5
27.5
27.5
27.5
Q
Q
17.2
92.1
21.1
23.8
23.8
4.1
98.1
23.8
23.8
23.8
23.8
23.8
17.2
92.1
21.1
23.8
23.8
4.1
98.1
23.8
23.8
23.8
Active Nodes
17.2
18.9
21.1
21.1
21.1
6.9
21.1
21.1
17.2
18.9
21.1
21.1
21.1
6.9
21.1
21.1
Active Node
Candidate Node
17.2
18.9
3.8
18.9
17.2
18.9
3.1
18.9
17.2
17.2
17.2
17.2
17.2
17.2
17.2
17.2
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Still Have Limitations
Multiple Events
Q
Q
Q

• Flooding overhead is high for sparsely
  distributed events
• Unable to detect sparsely located events