Presentation at the 3rd IEEE Track on Collaborative Modeling & Simulation - CoMetS'12 http://www.sel.uniroma2.it/comets12/

1. Integrated Modeling and Simulation Framework
for Wireless Sensor Networks
Baobing Wang and John S. Baras
Institute for Systems Research
Department of Electrical and Computer Engineering
University of Maryland, College Park, USA
WETICE/COMETS, Toulouse, France
June 27, 2012

2. Content
• Motivation
• Contributions
• System Framework and Design Flow
• Model Libraries
• Case Study
• Conclusion
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3. Motivation
• WSNs as cyber-physical systems
– Physical environments, physical platforms
– Communication protocols
– Computation algorithms
• Drawbacks of current design methodology
– Ad hoc design approaches
– Test only limited design alternatives
– Lack of reusability
– Little consideration of the interaction between
continuous-time domain and event-triggered domain
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4. Motivation
• Support system design for heterogeneous
WSNs
– Hybrid design framework required: event-
triggered and continuous-time dynamics
– Component reusability
– Multiple optimization objectives: trade-off
analysis and design space exploration
– Mission-critical applications: model-checking
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5. Contributions
• Propose a model-based system design
framework for WSNs
– Integrate both event-triggered and continuous-time
dynamics
– Provide a hierarchy of system model libraries
• Propose a system design flow within our model-
based framework
– Based on an industry standard tool
– Simulation codes (Simulink and C++) are generated
automatically
– Support trade-off analysis and optimization
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6. System Framework
• Model libraries
– Application Model Library
– Service Model Library
– Network Model Library
– Physical System Model Library
– Environment Model Library
• Development Principles
– Event-triggered: Statecharts in SysML
– Continuous-time: Simulink or Modelica
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7. System Framework
Distributed Computing
Communication and
Sensor Database
Physical World
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8. System Design Flow
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9. System Design Flow
• Trade-off analysis and design space exploration
– Each component is described with performance index
– Parametric Diagrams
– Parametric Constraint Evaluator or CPLEX
• Simulate in Matlab/Simulink
– All SysML blocks are transformed into a single S-function
– Generate Simulink source file
• Simulate in IBM Rational Rhapsody
– Generate C/C++ source code
– Statechart animation
– Interactive simulation
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10. Model Libraries
• Physical Platforms
– Battery, CPU, sensors and transceiver
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11. Model Libraries
Example: behavior
model of a transceiver
using Statechart in IBM
Rhapsody
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12. Model Libraries
• MAC Layer Components
– Low Power Listener: adjust radio’s power state based
on channel activity
– CSMA/CA Channel Access: gain channel access right
in CSMA/CA mechanisms
– CSMA/CA Sender: send one packet with
retransmissions in CSMA/CA mechanisms
– MAC Controller: specify the control logic of a MAC
protocol (ports are defined, but behavior should be
customized for each protocol)
– Slot Manager, Queue Manager, TDMA Sender,
Receiver …
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13. Model Libraries
Example: IEEE 802.15.4 unslotted mode for Controller
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14. Model Libraries
• Physical Environment
– Modeled using Simulink or Modelica
– Built using the Embedded Coder to generate C/C++
codes
– Imported as SysML blocks
– New environment information are pushed to event-
triggered blocks periodically
• Wireless Channels
– Radio propagation models, channel fading models
and BER under different modulation schemes
– Currently support: free space model, UDG model, ITU
indoor model and Rayleigh fading model
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15. Case Study
Data Center Living Room
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16. Case Study
• Simulation scenarios
– Wireless + No Pipe: disable pipe, send data
wirelessly, measure period is 5 seconds
– Wireless + Pipe (5s): similar to above, but
pipe is enabled
– Wireless + Pipe (60s): similar to above, but
measure period is 60 seconds
– Wired + Pipe: temperature data are available
immediately and directly
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17. Case Study
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18. Simulate Results
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19. Conclusions
• We proposed a model-based system
design framework for WSNs
• The proposed system design flow can
integrate both continuous-time and event-
triggered modules, and study the system
performance using generated codes
• Composability and reusability are
demonstrated through a case study
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20. Thank You!
baras@umd.edu
301-405-6606
http://www.isr.umd.edu/~baras
Questions?
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