We propose FIT, a flexible, lightweight, and real-time scheduling system for wireless sensor platforms. There are three salient features of FIT. First, its two-tier hierarchical framework supports customizable application-specific scheduling policies, hence, FIT is very flexible. Second, FIT is lightweight in terms of minimizing the thread number to reduce preemptions and memory consumption while at the same time ensuring system schedulability. We propose a novel Minimum Thread Scheduling Policy (MTSP) exploration algorithm within FIT to achieve this goal. Finally, FIT provides a detailed real-time schedulability analysis method to help check if application's temporal requirements can be met. We implemented FIT on MicaZ motes and carried out extensive evaluations. Results demonstrate that FIT is indeed flexible and lightweight for implementing real-time applications, at the same time, the schedulability analysis provided can predict the real-time behavior. FIT is a promising scheduling system for implementing complex real-time applications in sensor networks.

Wireless networked sensors raise a great number of programming challenges in applications. In this paper, we present AntC, a systems programming language, which focuses on the super-micro embedded system that supports wireless networked sensors. It provides four broad characteristics: it is a component-oriented application design; it integrates an embedded OS with two-level dispatcher; it improves the fault tolerance in run-time; furthermore, the improvement on multiplatform adaptability allows AntC program to be easily transplanted to other platforms with different embedded processors.

Smart sensors are sensing nodes that contain local intelligence to receive commands and take actions. They act as feelers of ubiquitous computing environments. Their software platform has to meet the requirements of concurrent operations, real-time constraint, adaptability and dependability. Gamma-OS is an OS kernel designed for these smart devices. This work analyzes the typical task model of smart sensors and presents the implementation of scheduling, resource access and dynamic admission control schemes in gamma-OS. Its primary and subordinate two-level task-scheduling scheme can efficiently isolate the scheduling of time-critical and time-uncritical tasks. Fault tolerance strategies including FTRMS admission control, fault detection, and fault recovery are also extended in gamma-OS to tolerate transient faults in executions of tasks.