R-Node: New Pipelined Approach for an Effective Reconfigurable Wireless Sensor Node

The pipeline of reconfiguration is a novel approach that gives a decision making mechanism for any system of tasks when several reconfiguration scenarios are required. These scenarios represent the run-time operations that allow automatic functional modification of the system behavior. In the case of their frequent income, the pipeline follows a specific set of steps in order to figure out the scenarios that need to be applied without altering its own performance. The steps are represented by a sequence of modules. The first module checks the availability of the resources needed by the tasks. The second maintains the stability by rejecting any insupportable flow of software reconfigurations that can destabilize a system. The third module checks the availability of memory for each software reconfiguration request, whereas the fourth verifies the availability of energy for the execution of a new system software configuration. The last module checks the schedulability of this configuration by changing the priorities of the finally accepted tasks in order to reduce their response and blocking times, and to meet their deadlines. The feasibility of the reconfiguration through this approach allows its implementation in wireless sensor nodes. Known by their important requirements in terms of memory and energy, this proposition is adequate when it comes to guaranteeing a maximum lifespan of the nodes. Therefore, the pipeline of reconfiguration is integrated as a middleware within the software architecture of a node. The functionality of this middleware is coordinated by the mean of a set of threads that manage the communication between the pipeline of reconfiguration and the operating system. A tool has been developed within LISI Laboratory to encode this proposition and show its impact on a large range of real devices under diversified scenarios of reconfigurations.