Major breakthroughs in the deep sub-micron technology have led to the emergence of ubiquitous computing \cite{ME93}. Small and inexpensive devices like Wireless Sensor Network (WSN) have a lot of attention in recent years. Thanks to its portability, it may be carried out on everywhere from the human body to be deeply embedded in the environment. WSN can easily be deployed in large space with dramatically less complexity and cost compared to wired networks. Additionally, sensors can self-organize to form routing paths, collaborate on data processing, and establish hierarchies. The WSN is also re-configurable by easily adding and removing sensor nodes. However, on the one hand Wireless Sensor Nodes(WSNOs) are usually deployed in hostile environment containing many potential hardware failures. Hence, it is difficult for human to intervene in case of hard-failure of node element, and battery energy is leaked if a failing element is still supplied. On the other hand WSNOs have a limited power supply usually powered by batteries. Therefore, reliability and energy-efficiency of WSNO are important constraints for designers.