Research Of Low Power Technology For WSN Node With Environmental Energy Replenishing

The lifetime of wireless sensor network (WSN) is restricted by the energy capacity of battery. On the premise of guaranteeing the performance of node, the focus of node technology is to reduce the power consumption of each module so as to prolong the lifetime of node. With the development of environmental energy harvesting technology, it's an effective way to harvest ambient energy for WSN nodes self-powered. The uncertainty and randomness of energy harvested keep the power changing dynamically. The research on the low power strategy of node's each module also needs to adapt to the technology and characteristics of energy harvesting. Therefore, the research on the universal design principle is necessary to the design of low power WSN node.This thesis analyzes the energy consuming characteristics and the general principles in WSN node. According to the normal working modes, existing electronic devices and power saving technology, the result calculated confirms the feasibility of ultra-low power technology. Based on the characteristics of environmental energy replenishing and the energy consuming characteristics of four modules which make up of WSN node, the thesis presents relative low power design strategies. Set the lowest appropriate operating voltage for node and switching the power supply of other devices dynamically according to the variational load, the strategies not only keep high power efficiency of power module with the variation load, but also utilize and store the energy harvested effectively. The low power strategies are helpful to reducing the average power consumption of sensor module in continuous monitoring, including choosing sensors, setting working parameters, hierarchical sensing and adaptive sampling and so on. It is helpful to decreasing the energy consumption of micro controller unit by lowing down the operating voltage and frequency, choosing low power memory chips, working with necessary module only and optimizing compiler. For wireless communication module, the presented schemes used in the node can low down the transmitting power and multi-hop communication paradigm. Keeping in the low power working state as long as possible can reduce energy consumption of the peripheral devices. The relevant schemes are applied to improving the design of Mica2 node. According to the power estimation of Mica2, the result of power calculation verifies that the feasibility and effectiveness of the low power strategies.With the solar energy replenishing technologies and the low power strategies presented, in the thesis a new kind of low power WSN node is designed which can measure the dynamic parameters in the continuous monitoring application, such as acceleration in vibration. The experiment shows that the low power strategies for WSN node with environmental energy replenishing are effective and feasible. These schemes for WSN node designing are universal and practical.