The Optimization Design Of Low-Power Dissipation Wireless Sensor Network For Environmental Monitoring

Wireless Sensor Network(WSN), as the communication network of 21 century, is a technology integration of sensor, computer and wireless communication. Both its application and research value are of great significance. The large number of network nodes are characterized by rapid deployment, self-organization and unattended operation. Despite of the existence of some problems such as the relative change in the position of sensor node and the invalidation of some nodes, which actually don’t exert a destructive effect on the system’s function, it can be applied in the fields such as environment monitoring, national defense & military and bio-medical treatment. However, Problems now confronted by WSN lie in its limitation in resources, transmission distance and versatility.Nowadays, energy problem has already become one of the core issues in the research of WSN, which involves two aspects: energy supply and its consumption. With the miniaturization and functional diversities of sensor node, the traditional power supply mode cannot meet user’s application demand of the sensor nodes any more. In the present study, after reviewing the related literature of theories about energy supply and system power dissipation reduction, taking low-power dissipation as the principle in the WSN node designing, and energy conservation as the objective from node’s hardware designing to its software implementation, the author intended to put forward a low-power dissipation WSN node model. In the process of hardware designing, real-time clock chips were applied to govern the supply circuit of the whole system, and switching circuit was used to control the sensor interface. Time synchronization mechanism, sleeping mechanism and minimal transmitting power mechanism were proposed in the process of software designing. Therefore, the overall system power dissipation was greatly reduced, which in turn prolonged the lifetime of sensor node and the survival time of the whole network. The wireless communication protocol adopted in the present study was the wireless sensor network communication protocol, which was researched and developed by our lab on the basis of Zigbee protocol. In the meantime, solar cell’s maximum power tracking technique was utilized to make a power supplement to lithium battery, which proved that the problem of supplying nodes with energy on a long-term basis was finally solved.By comparison to traditional sensor nodes, the author in the present study put forward the real-time clock control power supply on-off design proposal to achieve low power consumption, in which the problem concerning about the energy consumption of sensor node can be greatly resolved by reducing the dormant power dissipation to uA scale. Besides, because of its strong versatility, the sensor interface of the sensor node designed in the present study can also be applied in environment monitoring. Finally, it is verified by system testing that the WSN node designed in the present study can meet the needs of the long-term outdoor environment data collecting task.