TOSSTI: Saving Time and Energy in TinyOS with Software Thread Integration

Many wireless sensor nodes (motes) interface with slow peripheral devices, requiring the processor to wait. These delays waste time, energy and power, which are valuable but limited resources on many motes. This paper presents techniques to use software thread integration (STI) in TinyOS applications to recover the idle time for useful processing. We modify the TOS scheduler to support the selection and execution of integrated threads. We analyze the impact of integration on task response time. We demonstrate these methods by applying them to a microphone array sampling application to save computation time and energy. We find that the integrated tasks finish 17.7% faster, reducing application active time (and hence application energy) by 6.3%.