Efficient reprogramming of wireless sensor networks using incremental updates

Software reprogramming enables users to extend or correct functionality of a sensor network after deployment, preferably at a low cost. This paper investigates the improvement of energy efficiency and delay of reprogramming, at low resource cost. As enabling technologies data compression and incremental updates are used. Algorithms for both approaches are analyzed, as well as their combination, applied to resource-constrained devices. All algorithms are ported to the Contiki operating system, and profiled for different types of reprogramming. The presented results show that there is a clear trade-off between performance and resource requirements. Furthermore, the best reprogramming approach depends on the type of update. Experimentally, VCDIFF, or the combination of Lempel-Ziv-77/FastLZ for compression with BSDIFF for delta encoding, have been identified as the best possible options.