| 桉树人工林中433MHz信道LoRa信号的传播特性 |
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| 作者姓名： | 谭星 于新文 张旭 李凡 刘燕 欧阳萱 文永志 |
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| 作者单位： | 中国林业科学研究院资源信息研究所,北京 100091;陕西省汉中市留坝县林业局,陕西 汉中 724100 |
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| 基金项目： | 国家重点研发计划(2017YFD0600901) |
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| 摘 要： | LoRa技术是最新出现的一种无线通信技术,具有低功耗、距离远、工作在非授权波段等特点,与ZigBee等现在常用的无线通信技术相比,其在人工林无线传感器网中更具潜力。然而由于LoRa的传输受环境影响较大,目前在人工林中传播特性的研究还处于空白。本研究基于Shadowing信号衰减模型,在广西东门林场中测试了433 MHz信道LoRa信号在两种天线高度下(1.5,2.0 m)和3种不同环境下(开阔环境、3 a林龄桉树人工林,5 a林龄桉树人工林)LoRa信号接收强度(RSSI)随距离变化的情况,每种条件下得到了两组数据。首先利用其中一组数据对模型进行拟合,拟合结果表明,LoRa信号传输遵从Shadowing模型,拟合度在0.886~0.982。然后利用另一组数据对模型的精度进行验证,验证结果表明,模型精度较高,模型的精度介于0.780~0.961。最后分析了桉树人工林中影响LoRa信号传输的主要因素。本研究的方法和获得的信号衰减系数可以为桉树人工林无线传感器网络监测中LoRa节点的组网和部署提供依据和参考。
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| 关 键 词： | 无线传感器网络 桉树人工林 LoRa 信号传播 森林监测 |
Propagation characteristics of LoRa signal at 433 MHz channel in eucalyptus plantation environment |
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| Authors: | TAN Xing YU Xinwen ZHANG Xu LI Fan LIU Yan OUYANG Xuan WEN Yongzhi |
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| Institution: | (Institute of Forest Resource Information Techniques,Chinese Academy of Forestry,Beijing 100091,China;Liuba Forestry Bureau,Hanzhong 724100,Shaanxi,China) |
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| Abstract: | The growth and environmental information of the planted forest can be automatically obtained by wireless sensor network(WSN)in near real-time,providing important data support for the management of the planted forest.Due to issues such as the power consumption,limited communication coverage,etc.,it is very difficult to meet all the requirements of planted forest monitoring by using conventional wireless communication technologies.The LoRa(long range)technology is the latest wireless communication technology.Comparing with ZigBee,it has more potential applications for plantation wireless sensor networks construction because of the features of long-distance coverage,low power consumption,and workable in unlicensed band.However,the propagation of LoRa signal is greatly affected by the environment,and the research on its propagation characteristics in plantations is still blank.Based on the previous research,this study tested the variation of the received signal strength(RSSI)of the LoRa signal at 433 MHz channel with distance at two antenna heights(1.5 and 2.0 m)and three different environments(open environment,3-year-old eucalyptus plantation environment,5-year-old eucalyptus plantation environment)in the Dongmen,Guangxi Province.Two sets of data were obtained under each condition.Firstly,one set of the data was used to fit the Shadowing signal attenuation model.The fitting results showed that the LoRa signal transmission conformed to the Shadowing model,the regression coefficient R 2 ranged from 0.886 to 0.982,and the path loss index in the model which reflects the influence of environment were:2.894(open environment with 1.5 m antenna height),2.491(open environment with 2.0 m antenna height),3.733(3-year-old eucalyptus plantation with 1.5 m antenna height),3.586(3-year-old eucalyptus plantation with 2.0 m antenna height),4.146(5-year-old eucalyptus plantation with 1.5 m antenna height)and 3.805(5-year-old eucalyptus plantation with 2.0 m antenna height).Then another set was used to verify the accuracy of the model.The results showed that the model had high precision.The R 2 ranged from 0.780 to 0.961 and the MSE(root mean square error)values of the models ranged from 3.522 to 6.872.Finally,the main factors affecting the LoRa signal transmission in eucalyptus plantations were analyzed.The path loss index in the eucalyptus model was larger,the signal attenuation speed was faster,and the transmission distance was shorter compared with the model in open environment.The LoRa signal propagation in the eucalyptus plantation environment with the height of antenna between 1.5 m to 2.0 m was less affected by the antenna height,but more affected by the thickness of the trunk.The larger the diameter of the trunk,the larger the path loss index,the faster the signal attenuation and the shorter the transmission distance.The research method and the signal attenuation coefficient calculated in this study can provide basis and reference for the construction of LoRa wireless sensor networks in the eucalyptus plantation. |
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| Keywords: | WSN eucalyptus plantation LoRa signal propagation forest monitoring |
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