Research On Wireless Sensor Network Techinology And Implementation Of Greenhouse Monitoring System

With the rapid development of information technologies such as micro-electro-mechanical systems(MEMS), wireless communication systems and computer networks, Wireless Sensor Networks(WSNs) have been becoming attractive in monitoring systems. Wireless sensor nodes which perceive and collect the environment data can be distributed into the interested area and be set up a multi-hop wireless network to send the data to the controlling center. WSNs can be used for many low-power, low-data-rate applications, such as military, industrial and agricultural production, environmental monitoring and space exploration. Wired monitoring devices have been widely used in traditional greenhouse monitoring systems, which are inconvenient to be deployed and maintained. In this thesis, WSN technology was applied to the greenhouse monitoring system to accomplish all the controlling functions as automatic data collection, self-organized networking and data transmission and intelligent control, etc.This thesis focuses on the study of wireless sensor network technologies and the implementation of greenhouse monitoring system. The main work includes:Routing protocols of WSN. Energy consumption and the life of the whole system should be firstly considered in routing protocols. In this thesis, considering the asymmetry characteristic in up and down link communication, a new routing protocol was proposed, which was called minimal energy consumption and hop count routing protocol, with remaining power and location supporting routing. It effectively improved the energy efficiency of WSN, balanced the energy consumption and extended the life of the network. Meanwhile, central supporting strategy effectively offset weak calculation capability of the processor.Wireless sensor node system. The hardware platform of the node system is composed of sensor board and processor board. The processor is AVR ATmegal28L, and the wireless communication IC, CC1000. The system is based an embedded operating system, TinyOS. The node system has the functions such as sensor data collection, LCD display, data sending and receiving by wireless communication, multi-hop routing protocols, smart battery management and so on.Locating technology of WSN. This thesis introduced a distributed weighted-multidimensional scaling algorithm that adaptively emphasizes the lowest relative error within the sensor networks. It chose neighbors of low relative error to participate in the iterative optimization. Greater weight was given to the lower relative error nodes to increase the location accuracy. The simulation results showed that the algorithm has good accuracy and convergence.Data analysis and management system. The software system supported the traditional data analysis and management functions including sensor node control, data storage, data display by chart, data inquiries, statistical analysis, etc.