Analysis Of Task Scheduling For Real-time System Based On Smart Sensors

Smart sensors are resource restricted devices which can be deeply embedded in the physical world or spread throughout our environment. Although system resource is seriously limited, operating system applied in smart sensors has to implement complex tasks scheduling, which should support concurrent operation, real-time constraint, adaptability and reliability. In this paper, we study the real-time system based on smart sensors, especially analyze the task scheduling for the real-time system based on smart sensors. The main contents and contributions of the work are as follows:1. Analyze the application characteristic of smart sensors which have real-time constraints, and analyze the module of real-time system based on smart sensors. Study the theory of task scheduling in real-time systems, which includes task scheduling, resource access control protocol, schedulability analysis based on CPU utilization and schedulability analysis based on calculation of tasks' worst-case response time.2. Deeply study the task scheduling for real-time system based on smart sensors. Set up a task set module for smart sensor systems. And we analyze three task scheduling schemes based on this task set module, which include hybrid preemptive scheduling, priority-based grouping scheduling and FCFS scheduling. because the schedulability analysis is the most important among the scheduling theory for real-time, we analyze the schedulability for hybrid preemptive scheduling and priority-based grouping scheduling.3. Analyze task-level Fault-tolerance scheme for real-time system based on smart sensors. It is difficult to implement Fault-tolerance scheme for smart sensors, because of the restricted resource. We mainly analyze the transient fault tolerance by applying time redundancy.4. Analyze the Micro operating system TinyOS and y OS as example platforms for smart sensors, analyze the characteristic of these two operating systems. Especially, we analyze the difference of the task scheduling scheme of these two systems. γ OS is an micro operating system to support smart sensor, which is sponsored by the National 863 Program. And the priority-based grouping scheduling scheme is applied in the y OS.