An Error Detection and Recovery Scheme for Dynamically Downloadable Modules in Wireless Sensor Networks

Abstract

Some sensor network operating systems support network reprogramming based on the dynamically loadable modules. Nevertheless, sensor nodes are resource-constrained and may not have the memory management unit. As a result, preventing memory access errors by the downloadable modules from crashing the sensor nodes pose a challenge in the design of wireless sensor networks. In this paper, we propose a software-based memory protection scheme that not only detects memory access faults but can also recovery from the faults. Our fault detection scheme is based on the idea of sandboxing. Each application module can only access regions of memory that it resides or is granted. A fault is detected when a module tries to access an invalid memory region. The fault recovery scheme is based on the idea of “n-version programming”. When an error is detected in a module, we recover from the error by replacing the buggy module by another version having the same functionality of the original module. We have implemented our memory protection scheme on the SOS operating system on the Mica2 mote. According to the experimental results, our proposed scheme consumes less memory overhead under the sequential execution, which is the most prevalent execution pattern.