LiREP: Lightweight incremental reprogramming of sensor nodes based on in-situ modification

Energy-efficient consumption of the reprogramming approaches is one of key issues for long-term living wireless sensor networks. Most of the current approaches focus on the power efficiency during data dissemination. However, the program rebuilding phase on target node is rarely considered as another significant part of total reprogramming energy consumed. We propose a novel reprogramming approach-LiREP in two-fold: first, we design an in-situ code modification method which saves more energy compared with traditional way to rebuild program in external flash. Three basic modifying operations are proposed and realized. These operations can reduce the writing/reading operations of flash ROM by producing a modified program with redundant codes in memory. Secondly, we also propose a novel rebuilding method to remove the redundant codes when the available memory is not enough for the in-situ code modification. This rebuilding method totally runs in-chip with least the rebuilding overhead. Experiment results show that LiREP reduces the rebuilding energy overhead by approximately 84% and 74% compared to Deluge and Hermes, and further minimizes the reprogramming energy overhead.