【作者】 张军国；

【导师】 李文彬； 赵燕东；

【作者基本信息】 北京林业大学 ， 森林工程， 2010， 博士

【摘要】 森林防火具有重要的生态意义、社会意义和经济意义。利用先进的技术手段快速有效地获取和描述森林环境变量信息,以实现森林火灾的自动监测是森林防火的前提和保障。本文提出了将GPRS和ZigBee无线传感器网络技术引入到森林火灾监测中的方案,对面向森林火灾监测应用的无线传感器网络技术所面临的应用基础性问题,如系统构建、通信协议选择、节点开发、路由协议仿真研究、定位算法改进以及网络内部通信衰减模型建立等进行了研究,主要研究内容和结论如下:1、结合森林火灾监测应用需求特点,提出了基于GPRS和ZigBee无线传感器网络技术的森林火灾监测系统,研制了面向森林火灾监测的无线传感器网络节点,包括普通节点和协调节点。该方案目前在国内尚无实际应用的报道。2、改进了无线传感器网络中节点自定位经典算法DV-Hop算法。针对DV-Hop算法及已有DV-Hop改进算法存在的不足,提出了基于最小均方误差准则以及加权平均法来修正网络平均每跳距离的改进方案,通过仿真验证表明,本文改进算法相对已有的改进算法性能略优,但与DV-Hop算法相比具有明显优势。3、对ZigBee网络的层次路由协议中的典型算法进行了重点研究和比较,利用NS2网络仿真软件对LEACH协议及其改进算法LEACH-C协议进行了仿真研究和比较,确定了适用于本文所构建的面向森林火灾监测的树型拓扑结构的具体路由协议类型。4、对2.4GHz的无线通信传输信号在人工林环境中的传播特性进行研究,建立了人工林环境下2.4GHz的无线电波信号场强衰减预测模型(?),其中d是测试点与信号发射模块之间的距离(单位:m);确定了2.4GHz信号在人工林最大通信距离为51.618m;提出了无线传感器网络节点在人工林中按照等边三角形(等边菱形)的方式排列的方案,节点之间的距离取51.618m和(?)中间的较小值,其中r为传感器感知半径(单位:m);为人工林无线传感器网络节点布置提供了重要的理论依据。5、建立了基于ZigBee无线传感器网络的森林火灾监测系统的原型系统,通过对原型系统的调试验证了本文主要研究成果。总之,本文研究成果为基于ZigBee无线传感器技术的森林火灾监测系统的实际应用提供了基础,为推进我国森林火灾监测工作的信息化、自动化与智能化提供了一种有效的新思路。更多还原

【Abstract】 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.更多还原