In the recent years, rapid development of Wireless Sensor Network (WSN) technology promises a revolution in sensing applications which are deeply embedded in the physical world. Each node in the network has to operate with a very limited memory, energy, and computation capacity and is very prone to failures. Besides, it has to provide a lot of functionalities as the applications for WSN become more and more sophisticated.
Dynamic reconfiguration and self-adaptation are also vital for WSN to operate in a dynamic environment. Runtime technologies which allow software to evolve as system requirements and environment changes are critical to develop and deploy applications for such networks. As the result, more and more challenges are posed to the developers. One of those is to design an efficient operating system for sensor nodes. With low power consumption, small code and data size, evolvability as design criteria, we develop an $\It{evolvable operating system}$ (EOS) for WSN applications. The EOS provides memory space efficient thread management, collaborative thread communication model and network stack. It also supports power management of microcontroller and radio transceiver, and network wide time synchronization function. Above all, we propose our concept of $\Itbf{evolvability}$ and an approach for $\It{evolvable software reconfiguration}$ for WSN. Our approach provides a general framework for on-the-fly upgrading software ranging from operating system to application modules. Upgrading procedures can be implemented transparently to users with minimal system interruption.
Our system was implemented on our ANTS-H2 outdoor hardware platform and deployed in Halla Mountain, Jeju Island (Haroobang project).
We also describe our system's performance evaluation in terms of time and memory usage.
