Watchdog Designs for TinyOS Motes

We investigate a way to increase the reliability of distributed wireless networks by introducing two watchdog designs on the Mica mote. These watchdogs detect errors through monitoring aspects of the system and then take steps so that the mote recovers from these errors. The first design is a coprocessor watchdog that monitors the functionality of the main processor through heartbeat signals. The second watchdog design is a buddy system consisting of three motes that monitors each other’s radio functionality through heartbeat packets. From these watchdog designs, we analyze the scenarios where they are able to detect errors and recover. We also estimate the costs of memory usage, CPU utilization, and power consumption to implement these watchdogs and show that these costs are small percentages of the overall available resources. We conclude that the distributed wireless network would benefit from these watchdogs by the additional error detection and recovery that was not previously available. We find that the benefits of increased overall system reliability greatly outweigh the costs.