Preemptive two-level priority real-time scheduling strategy for node system in wireless sensor network

Abstract

Emerging applications such as forest fire monitoring have increasing demands on WSN to transmit data in real-time. In order to ensure real-time data transmission, it requires that the operating system of a node should schedule tasks in real-time. TinyOS is one of the most popular operation systems that support multifarious applications. However, its FIFO scheduling strategy does not guarantee requirements for hard real-time applications. A Preemptive Two-Level Priority (PTLP) Real-time Scheduling Strategy is proposed in this paper. Two tier priorities, static and dynamic, are designed and integrated in TinyOS task queue to guarantee the real-time task scheduling. We demonstrate this approach by a real-world case study: a WSN hardware node embedded with our task scheduling strategy is designed and implemented. The result demonstrates that our PTLP real-time scheduling strategy performs efficiently in terms of packet throughput and task scheduling time.