1. Behavioural Design of Sensor Network Applications using Activity-Driven States
Amir Taherkordi, Frank Eliassen, and Einar Broch Johnsen
Department of Informatics
University of Oslo, Norway

2. Introduction Low cost design phase Fast optimization Abstract level
Software design in WSNs require a dynamic design view
Control flow, state transition, delayed states and transitions, etc.
Previous works mainly focus on coarse-grain and network-level behaviuors
E.g. Timed Automata, Timed Petri Net, StateCharts

3. Motivation Example – Health Care System
Wearable location data propagation sensors are used
After sending the location information, the sensor node waits for ACK
In order to reduce the energy consumption of sensor nodes, listening window is used
The sensor check patient’s temperature periodically

4. Motivation Example – patient tracking
Step1: Check initial settings and default parameters
Step2: Send Positioning packet, then wait for t0 ms
Step3: Start listening to gate unit for ACK for t1 ms
If ACK received, wait Ti ms, go to step2
If no ACK, listen to gate unit for t2 ms
If no ACK, listen to gate unit for t3 ms
If no ACK, go to step2 immediately
At the same time, temperature sensor is polled evert t4 ms

5. Inability of existing models
The following need to be abstracted:
Scheduling
Listening
Order of activity
Events
States
Transitions
Timing constraints
No existing model can abstract all these aspects in a single model while providing an easy approach to convert to actual programs

6. SENSEACT Overview An extension of finite automaton
Activity-driven states (ActState)
Current state
Current activity
Transition functions
State variables
Transition-level
Global-level
Time information

7. SENSEACT Definition

8. SENSEACT Extension Parallel transition Pull-based event
Parametric repetition
Push-based event

9. Implement Motivation Example

10. Convert to Programming Model
ActStates
Interface for lifecycle manageent (initiating, executing, terminating)
Local state variables
StayIn(Time duration)
Transition
Internal transition
External transition

11. Evaluation Programming abstraction and runtime model
Not considered in this work since it is dependent on platform
Assessment of the model itself
Focus on code generation
Focus on low-level abstraction needs
Focus on both

12. Conclusion
The gap between the behavioural description of WSN software and the structural design models of typical programs is filled
SENSEACT models timed activities, states, events and delayed transition in one single model
SENSEACT model can be converted to a coarse-grained programming constructs easily, both at the node level and network level