| The timely grasp of forest fire risk and the early detection of forest fires are crucial to the accurate prevention and control of forest fires.At present,forest fire prevention and control mainly adopts ground patrol,lookout post stationed,remote video monitoring and satellite remote sensing.Although certain results have been achieved,they are all constrained by the complex geographical environment of the forest and the harsh meteorological conditions.Although the development of wireless sensor network technology has brought new opportunities for forest fire prevention and control,there are still problems such as short communication distance of nodes,high energy consumption and unstable network topology.Therefore,it is urgent to develop a wireless sensor network system applicable to the complex forest environment,design a low-power reliable wireless communication networking protocol under the strong shading environment in forest areas,and realize the long-distance and stable transmission of sensory information.In this thesis,a series of low-power networking protocol design schemes such as hybrid Media Access Control protocol(MAC),improved hierarchical routing protocol and node localization algorithm are proposed to provide a new technical idea for low-power,stable and reliable monitoring of wireless monitoring system in complex forest environment.The main work of the thesis is as follows:(1)The environmental characteristics of forest areas and their impact on wireless communication are analyzed,and the networking requirements of wireless sensor networks in forest environments are proposed.By comparing various wireless communication technologies,the long-range and low-power LoRa technology is applied to forest area monitoring.Improvements are made to existing MAC protocols,routing protocols,and node localization algorithms with the aim of optimizing network performance,enhancing data transmission reliability,and adapting to the uncertainties and dynamics of complex forest environments.(2)Firstly,a hybrid MAC protocol that can be adaptively adjusted according to the network load is proposed by combining the advantages of MAC protocols based on allocation and competition.Then a hierarchical routing protocol is proposed.The protocol constructs a tree with a gateway node as the root node and transmits packets along the spanning tree path to the root node,which greatly reduces the amount of raw data transmission and reduces energy consumption after the layer-wise fusion process of cluster head nodes in the tree.Finally,the software and cloud platform of the nodes in the system are designed,and the workflow of the system is elaborated.(3)Combined with the characteristics of forest environment,this thesis proposes a new method aiming to improve the traditional non-ranging Distance Vector Hop Localization Algorithm(DV-Hop)in order to reduce the error when applying the algorithm in forest environment.Firstly,the minimum hop count calculation in the DV-Hop algorithm is modified using the idea of multiple communication radii;subsequently,the least squares criterion is introduced and the average hop distance calculation is modified.Through simulation analysis,the improved algorithm outperforms the traditional algorithm in terms of positioning accuracy.(4)A hardware test platform is built to test the networking effect of multiple nodes and the positioning accuracy of the nodes,and to test the life cycle of the system.The test results show that the proposed wireless sensor network system solution in forest area can achieve stable and reliable monitoring of complex forest environment for a long time. |
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