A reliable task scheduling scheme for sensor-based real-time operating system

The emergence of wireless networked sensors constitutes a hot research topic in embedded system design. Although system resource is seriously limited, operating system applied in sensors has to implement complex task scheduling, which should support concurrent operations, real-time constraint, adaptability and reliability. In this paper, we present a reliable OS scheduling scheme for wireless networked sensors. According to the analysis of operating model and task set of wireless networked sensors, a primary and subordinate two-level task-scheduling scheme is implemented to schedule time-critical and non-time-critical tasks, and an admission control policy is employed to meet hard real-time requirement of some real-time tasks. Furthermore, based on this scheme, some fault tolerance strategies are outlined to improve reliability at run time, including fault tolerance analysis, admission control based on fault tolerance, fault detection, and fault recovery.