accelerated by the readily-available hardware platforms, as well as This paper presents the design principles, implementation, and core system software such as sensor node operating systems in evaluation of the RETOS operating system which is specifically particular. From the early days, much effort has been given to developed for micro sensor nodes. RETOS has four distinct develop efficient and yet complete operating systems for micro objectives, which are to provide (1) a multithreaded programming sensor nodes. For instance, TinyOS [1] has historically been used by interface, (2) system resiliency, (3) kerel extensibility with many practitioners in the field and even advocated as "the" dynamic reconfiguration, and (4) WSN-oriented network operating system for WSN. Other operating systems such as abstraction. RETOS is a multithreaded operating system, hence it SOS[2], Contiki[3], MANTIS[4], and t-kernel[5] have challenged provides the commonly used thread model of programming the success of TinyOS and provide incremental, or even alternative interface to developers. We have used various implementation solutions for many practical issues still being debated in the related techniques to optimize the performance and resource usage of communities.multithreading. RETOS also provides software solutions to separate Writing an operating system for micro sensor platforms poses kernel from user applications, and supports their robust execution on several unprecedented problems. First, the OS implementation MMU-less hardware. The RETOS kernel can be dynamically should consider microcontrollers which typically provide very reconfigured, via loadable kernel framework, so a applicationlimited processing power, memory and battery life-time. The eventoptimized and resource-efficient kernel is constructed. Finally, the driven paradigm for sensor OS is especially favored for the networking architecture in RETOS is designed with a layering resource-constrained environment, and we have seen the concept to provide WSN-specific network abstraction. RETOS proliferation of TinyOS or SOS in this context. Second, the currently supports Atmel ATmegal28, TI MSP430, and Chipcon application programming model should be seriously considered to CC2430 family of microcontrollers. Several real-world WSN provide an easy and convenient programming interface to applications are developed for RETOS and the overall evaluation of application developers, without needing to be aware of underlying the systems is described in the paper.operating system principles. The event-driven operating systems, for example, enforce programmers to structure and program an Categories and Subject Descriptors application as a state machine in terms of tasks and event handlers. D.4.7 [Operating systems]: Organization and DesignUnderstanding this concept is an easy task for experts, but conventional programmers who are accustomed to a process model General Terms of programming may find the concept hard to grasp. Third, a micro Design,eralerimentation, Measurement, Perfonnan...

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Target localization, whose goal is to estimate the location of an unknown target, is one of the key issues in applications of wireless sensor networks (WSNs). With recent advances in fabrication technology, deployments of large-scale WSNs have become economically feasible. However, there exist issues such as limited communication and the curse of dimensionality in applying machine-learning algorithms such as support vector regression (SVR) on large-scale WSNs. Here, in order to overcome such issues, we propose an ensemble implementation of SVR for the problem of target localization. The convergence property of the localization algorithm using the ensemble SVR is verified, and the robustness of the proposed scheme against measurement noise is analyzed. Furthermore, experimental results confirm that the estimation performance of the proposed method is more accurate and robust to measurement noise than the conventional SVR predictor.