Abstract-Programming Wireless Sensor Network (WSN) applications is known to be a difficult task. Part of the problem is that the resource limitations of typical WSN nodes force programmers to use relatively low-level techniques to deal with the logical concurrency and asynchronous event handling inherent in these applications. In addition, existing general-purpose, nodelevel programming tools only support the networked nature of WSN applications in a limited way and result in application code that is hardly portable across different software platforms. All of this makes programming a single device a tedious and error-prone task.To address these issues we propose a high-level programming model that allows programmers to express applications as hierarchical state machines and to handle events and application concurrency in a way similar to imperative synchronous languages. Our program execution model is based on static scheduling what allows for standalone application analysis and testing. For deployment, the resulting programs are translated into efficient sequential C code. A prototype compiler for TinyOS has been implemented and its evaluation in described in this paper.

Wireless sensor, actuator networks distinguish themselves from wireless sensor networks by the need to coordinate actuators' actions, real-time constraints on communication and the frequently feedback-based nature of computation performed in the network. In this paper we propose a functional macro-programming language, SOSNA, that employs the stream programming paradigm to concisely specify data transformations in the network so that wireless sensor actuator network (WSAN) application developers can focus on higher-level control-oriented problems rather than on designing the way in which communication is organised in the network. SOSNA accommodates a broad class of WSAN coordination models, supports mobility and provides a means of employing feedback for distributed state maintenance. Program execution proceeds in rounds providing real-time guarantees on actuator decision making and synchronisation. In addition, static program semantics permit nodes to switch their radios off to conserve energy.

Abstract-Pedestrian safety is a major concern in road transportation as pedestrian/vehicle accidents account for the second largest cause of traffic-related injuries and fatalities worldwide. Considerable work has examined the use of lidar, radar and computer vision for pedestrian detection but existing solutions are costly and work only if pedestrians are in the vehicle's lineof-sight. In this paper, we present a novel technique based on wireless sensor networks that is cheap and enables pedestrian detection beyond the driver's horizon. The detection system is based on the use of "cat's eyes" augmented with embedded processing and communication capabilities that are able to detect pedestrians and forward this information along the road. We describe how such a system was successfully built with SOL, a high-level programming language for wireless sensor networks. Initial results show that the system obtains detection rates of 100%, false positive rates of 0%, and that the precision of the estimated position of pedestrians depends on their heading and relative position to sensor nodes.

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