SDREAM: A Super-Small Distributed REAL-Time Microkernel Dedicated to Wireless Sensors.
ABSTRACT 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.
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ABSTRACT: The operating systems of wireless sensor networks should be suitable for strict-constrained system resources and support two operation modes: event-driven & multi-threading. Traditional embedded operating systems are generally not fit for WSN applications. This paper presents a smart, resource-aware, low-power-consuming and distributed real-time micro-kernel: LIMOS. LIMOS adopts an event & thread two-level system architecture and a two-level scheduling policy: 'non pre-emption priority based' high level scheduling for events; and 'preemptive priority-based' low level scheduling for threads. The scheduling scheme is predictable and deterministic with respect to real-time applications. A unique system interface and a system primitive-pair, i.e. tuple and IN & OUT, are proposed for all kinds of system synchronization and communication. LIMOS integrates the advantages of tinyOS and SDREAM. It allows running in different modes. The combination of two kernels extends greatly the application range of LIMOS from simple single-task to multitask applications. In present, LIMOS has been evaluated on several hardware platforms and ported for different applications.01/2007;
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ABSTRACT: The traditional urban public transport system generally cannot provide an effective access service for people with disabilities, especially for disabled, wheelchair and blind (DWB) passengers. In this paper, based on advanced information & communication technologies (ICT) and green technologies (GT) concepts, a dedicated public urban transportation service access system named Mobi+ has been introduced, which facilitates the mobility of DWB passengers. The Mobi+ project consists of three subsystems: a wireless communication subsystem, which provides the data exchange and network connection services between buses and stations in the complex urban environments; the bus subsystem, which provides the DWB class detection & bus arrival notification services; and the station subsystem, which implements the urban environmental surveillance & bus auxiliary access services. The Mobi+ card that supports multi-microcontroller multi-transceiver adopts the fault-tolerant component-based hardware architecture, in which the dedicated embedded system software, i.e., operating system micro-kernel and wireless protocol, has been integrated. The dedicated Mobi+ embedded system provides the fault-tolerant resource awareness communication and scheduling mechanism to ensure the reliability in data exchange and service provision. At present, the Mobi+ system has been implemented on the buses and stations of line '2' in the city of Clermont-Ferrand (France). The experiential results show that, on one hand the Mobi+ prototype system reaches the design expectations and provides an effective urban bus access service for people with disabilities; on the other hand the Mobi+ system is easily to deploy in the buses and at bus stations thanks to its low energy consumption and small form factor.Sensors 01/2012; 12(8):10678-92. · 2.05 Impact Factor
Conference Paper: LIMOS: A Tiny Real-Time Micro-Kernel for Wireless Objects[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