Study On Techniques Of Wireless Sensor Network Oriented To Forest Fire Detection

Forest fire prevention has been characterized great ecological significance, social significance and economic significance. Advanced technological means are utilized to acquire and describing the forest environment variable information rapidly and effectively in order to realize forest fire automatic monitoring, which is just the prerequisite and guarantee of forest fire prevention.This dissertation presents a method in which the GPRS and the ZigBee-based wireless sensor network technology are introduced into the forest fire detection, and it carries out a major study on the applied basic issues facing in application of the wireless sensor network technology to forest fire detection, such as system construction, communication protocol selection, nodes development, routing protocols simulation research, location algorithms improvement as well as building attenuation model of internal communications in network etc.. The main content and conclusions of this study are as follows:1. Combining with the characteristics of application requirement of forest fire detection, this study presents a new forest fire detection system based on GPRS and ZigBee wireless sensor network technology, and develops wireless sensor network nodes, including basic nodes and coordinate nodes, for forest fire detection. This scheme has not ever been reported being used in a practical application interiorly.2. This study improves the node self-localization classical algorithm DV-Hop in the wireless sensor network. Aiming at the deficiency of original DV-Hop and its existing improved algorithm, this paper proposes an improvement scheme, which modifies average hop distance of the network based on minimum mean-variance criterion and weighted average method. The simulation results show that the performance of improved algorithms in this paper is slightly better than existing improved algorithm, but they has obvious advantages compared to original DV-Hop algorithm.3. It mainly studies and compares the typical algorithms of hierarchical routing protocols of ZigBee network. NS2 network simulation software is used to carry out simulation research and comparison on LEACH protocol and its improved algorithm LEACH-C protocol, which helps determine the suited idiographic route protocol for the Cluster-Tree topology of the forest fire-detection system built in the paper.4. This study researches the propagation characteristics of 2.4GHz wireless transmission signal in the environment of plantation and establishes a field-strength attenuation prediction model for 2.4GHz wireless transmission signal, the equation follows as:E_ryu =40.043- 20 lg(d) + 20 lg(0.949e^-0.010d)- 0.26d^0.6 , where d represents the distancebetween test points and signal transmitter module (unit: m). The maximum communication distance of 2.4GHz signal in plantation is 51.618m determined by this model. The wireless sensor networks nodes in plantation is distributed as equilateral triangle (equilateral diamond-shaped). The distance betweennodes takes the smaller value between 51.618m and (3r)^1/2, where r represents the sensor sensing radius (unit: m). These results provide an important theoretical basis for layout of wireless sensor network nodes in the plantation.5. Prototype system of the forest fire detection system is built based on the ZigBee wireless sensor network. The main research results are verified by debug of the prototype system.In short, the research results in this paper can provide basis for practical application of forest fire detection system based on ZigBee wireless sensor network, meanwhile, they provide an effective new idea to promote the information, automation and intelligence of forest fire detection for our country.