| With the development of sensing technology,wireless communication,could computation and etc.Using Internet of Things(IoT)to monitoring the plantation constinuously,chronically dynamically,is an important way to improving the platation management level and realizing the multi-target platation management.Due to the multi-variety sensor,large area,complex forest environment there still have many problems need to solve when IoT used in forest.In this paper,based on the devolpment of IoT platform,eucalyptus plantation was taked as research object,the eucalptus plantation IoT monitoring system using OID(Object Identifier)technology was proposed,the transmission characteristic of LoRa signal was tested in eucalyptus plantation,and the preliminary design of eucalyptus plantation IoT monitoring gateway was carried out.The main work of this paper is as follows:1)eucalptus plantation IoT monitoring system was proposedBased on the characteristics of eucalyptus plantation IoT monitoring,considering the latest IoT development trend and the latest research results,the eucalyptus plantation IoT monitoring system with four-layer-structure was proposed:sensing layer,transimit layer,cloud platform and application layer.In order to solve the island phenomenon in the existing forestry IoT system,and make the system easy to be compatible with other forestry IoT systems.The OID identification system of the eucalyptus plantation monitoring node is proposed,the system is divided into 10 layers,the sort of monitoring object,node's geographical location are under considered.The JSON format profile file,also called profile,is used to standardize and certify the forestry IoT collection node to deal with the problem such as the various types of forestry IoT sensor nodes and complex functions.2)The 433MHz LoRa signal propagation was testedLoRa is a new wireless communication technology with long distance and low power consumption.It is very suitable for the use of forestry IoT.However,the propagation of LoRa signals was effected by physical parameters and environment.In this paper we focused on the propagation characteristics of LoRa signal at 433MHz channel in eucalyptus plantation environment,to provide theoretical basis for the efficient deployment of LoRa WSN in eucalyptus plantation.Experiment was conducted in Dongmen Forest Farm in Guangxi province with several different eucalyptus forest environment(open environment,3-year-old eucalyptus plantation,and 5-year-old eucalyptus plantation,slope environment)and two different antenna heights(1.5m and 2m)were selected.The variations of RSSI(received signal strength indication)value by distance in different environments were measured.The shadowing model was fitted and the accuracy of model was evaluated.The experimental results show that,the RSSI and the propagation distance are in accordance with the shadowing model under the above conditions,and the regression coefficient R~2ranged from 0.886 to0.982,the path loss index in the model which reflects the influence from different environments are:2.894(open environment with 1.5m antenna height),2.491(open environment with 2m antenna height),3.733(3-year-old eucalyptus plantation with 1.5m antenna height),3.586(3-year-old eucalyptus plantation with 2m antenna height),4.146(5-year-old eucalyptus plantation with 1.5m antenna height)and 3.805(5-year-old eucalyptus plantation with 2m antenna height).Meanwhile,the verification data showed that the RMSE(Root Mean Square Error)values of the models ranged from 3.522 to 6.872,and R~2ranged from 0.780 to 0.961,indicating that the model was well fitted.From the result we can know the transmission distance was shorter compared with the model in open environment.LoRa signal propagation in eucalyptus plantation environment with the height of antenna between1.5m to 2m 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 LoRa signal is affected by the slope,the region where the slope changes is larger,the faster the signal is attenuated.3)the eucalyptus plantation IoT monitoring gateway was preliminally designedAim at the problem of existing IoT gateways such as:use inter-identification to mark the child nodes which makes it difficult to be compatible with other IoT systems;use HTTP to transmit the data makes it unsuitable for using in forest areas where energy is tight and resources are limited.The forestry IoT gateway using OID technology to identification the node and MQTT proctol to communicate with Server was proposed in this paper.The hardware of the gateway is designed,using low-cost Raspberry Pi as the hardware platform,equipped with LoRa communication module and Ethernet communication module,so that it can communicate with the sensor layer network through the LoRa communication module,and the could platform throught the Ethernet communication module;the workflow of the data collection of the LoRa sensor node by the gateway was introduced;the main functions of the gateway,such as node network access,data collection and control command delivery,were introduced in detail;In the Chinese Academy of Forestry,the actual sensor device was used to test the gateway function.The test results show that the gateway can achieve the intended purpose and can upload the collected node data in time.The key technologies of the IoT monitoring system of eucalyptus plantation were disccused in this paper,which provides new ideas and solutions for the eucalyptus plantation monitoring using IoT.At the same time,the system is designed to be compatible with other forestry IoT systems,which make it could be integrated easily with other plantation IoT systems.In a word,this paper has carried out beneficial exploration for the monitoring and management of artificial forest using IoT technology,and provided a new idea for the forest monitoring. |
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