Traditional embedded operation systems are resource consuming multitask, thus they are not adapted for smart wireless sensors. This paper presents a super-small distributed real-time microkernel (SDREAM) dedicated to wireless sensors. SDREAM is a tuple-based message-driven real-time kernel. It adopts a meta language: Kernel Modeling Language to define and describe the system primitives in abstract manner. The IPC and processes synchronization are based on the LINDA concept: the tuple model implemented by two light primitives (SND: OUT & RCV: IN). In SDREAM, tasks are classified into two categories: periodic and priority. The periodic task has the highest priority level and is responsible for capturing sensor signals or actuating control signals; the priority task has various priority levels and is suitable for time-constraints applications. A two-level task scheduling policy scheme, named priority-based pre-emptive scheduling, is used for task scheduling. SDREAM is simple and efficient. It has a flexible hardware abstraction capability that enables it to be rapidly ported into different WSN platforms and other tiny embedded devices. Currently, it has been ported and evaluated in several hardware platforms. The performance results show SDREAM requires tiny resource and is suitable and efficient for hard real-time multitask WSN applications.
"However, this mechanism consumes high resources in terms of energy, CPU and memory. The existing embedded RTOSs such as SDREAM , μC/OS-II , VxWorks, QNX, pSOS, WinCE.NET, RTLinux, Lynxos, RTX, and HyperKernel are not suitable for the embedded IVC system because they only operate as this mechanism and it is resource consuming (CPU and memory) comparing with our proposed solution one. "
[Show abstract][Hide abstract] ABSTRACT: To overcome system latency and network delay is essential for intervehicle communication (IVC) applications such as hazard alarming and cooperative driving. This paper proposes a low-cost embedded software system dedicated to such applications. It consists of two basic component layers: an operating system, named HEROS (hybrid event-driven and real-time multitasking operating system), and a communication protocol, named CIVIC (Communication Inter Véhicule Intelligente et Coopérative). HEROS is originally designed for wireless sensor networks (WSNs). It contains a component-based resource-aware kernel and a low-latency tuple-based communication system. Moreover, it provides a configurable event-driven and/or real-time multitasking mechanism for various embedded applications. The CIVIC is an autoconfiguration cooperative IVC protocol. It merges proactive and reactive approaches to speed up and optimize location-based routing discovery with high-mobility nodes. Currently, this embedded system has been implemented and tested. The experiment results show that the new embedded system has low system latency and network delay under the principle of small resource consumption.
EURASIP Journal on Embedded Systems 01/2010; DOI:10.1155/2010/601343
"Due to resource constraints of WSN node and its diverse application domains, the key features of WSN operating systems (WSNOS) should be resource-aware and be configurable to adapt to each situation. Note that most of traditional embedded RTOSs such as SDREAM8, µC/OS-II, VxWorks, QNX, pSOS, Lynxos, RTLinux, WinCE.NET, RTX and HyperKernel are unfit for WSN as they are resource consuming. On the other hand, the eventdriven operating systems are essentially single task systems. "
[Show abstract][Hide abstract] ABSTRACT: Traditional operating systems for wireless sensor networks (WSN) are based on either event-driven or multitask concept. Instead, this paper presents an embedded real-time operating system, named HEROS ‘Hybrid Embedded Real-time Operating System’, which is configurable to run in different modes: event-driven, multitask or hybrid to adapt to diverse domains of WSN applications. HEROS adopts a modular and hierarchical architecture: action (system operation), thread (component) and event (etask) and provides a predictable and deterministic scheduling mechanism: ‘non pre-emption priority based’ scheduling for events and ‘pre-emptive priority-based’ scheduling for threads. Furthermore, to ease distributed cooperative application, HEROS adopts LINDA concept by providing a simplified tuple space and a lightweight IN/OUT primitive-pair to implement system communication & synchronization. Currently, HEROS has been implemented and evaluated in different applications and on different platforms. The experimentation results show that HEROS has a small footprint and meets different real-time application requirements.
Journal of Networks 08/2009; DOI:10.4304/jnw.4.6.428-435
[Show abstract][Hide abstract] ABSTRACT: TinyOS is a natural event-driven single-task system. It fits for the single-task specific-application but not for the real-time multi-task application; while, SDREAM is a typical distributed real-time micro-kernel. It supports real-time multi-task applications but normally consumes more resources. This paper presents a novel hybrid real-time micro-kernel: LIMOS (lightweight multi-threading operating system), which combines the features of TinyOS and SDREAM. LIMOS adopts the event & thread two-level architecture and correspondingly has a two-level scheduling policy: 'event-driven' (high level scheduling for events) and 'priority-based preemptive' (low level scheduling for threads). LIMOS adopts the LINDA concept: tuple space and in & out primitive-pair for system synchronization & communication. At present, LIMOS has been applied into a wireless application with the integration of multi-wireless techniques (RFID, ZigBee, and WiFi)
Wireless Communications, Networking and Mobile Computing, 2006. WiCOM 2006.International Conference on; 10/2006
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