Research On Communication And Coverage Of ZigBee And Lora Wireless Sensor Networks For Forest Fire Early Warning

Forest is the natural resource on which human lives.In recent years,more and more forest fires have posed a great threat to human property and life safety.It is urgent to set up an efficient and practical forest fire intelligent warning and control system to protect forest areas.The application of Internet of Things technology in forest fire warning project is also gradually under study.The main wireless sensor network communication technologies are short-distance self-organizing network ZigBee technology and low-power wide area network Lo Ra technology.For forest fire warning applications,this paper compares ZigBee and LoRa technologies respectively.To solve the problem that ZigBee communication distance is too short and LoRa has a low rate and is difficult to self-network,a communication method that combines ZigBee with LoRa technology to form a layered wireless sensor network is proposed.Among them,the forest area perception monitoring node uses ZigBee technology to set up a network,locate by GPS and collect monitoring data such as flame,smoke,temperature and humidity using various sensors;LoRa combines ZigBee technology to form a convergent node,and uses relay "multi-hop" network to aggregate and forward data in each monitoring area,which is ultimately transmitted to the LoRa base station for processing;the base station aggregates and merges dataTransfer to the server of the control center for relevant personnel of forestry bureau to view the fire alarm and fire development analysis,and formulate corresponding fire fighting measures and emergency plans,and notify the forest fire fighters to put out the fire.Because LoRaWAN,a standardized LoRa communication protocol,does not meet the requirements of relay networking,this paper studies LoRa relay communication,and designs a practical relay networking communication protocol based on LoRa serial port wireless transmission characteristics.This protocol is based on serial communication data frame settings and can be ported to LoRa devices through simple programming to achieve large-scale relay networking.To solve the network coverage problem of forest convergence relay nodes,the LoRa communication range of convergence nodes is simplified to the intersection of circles in the mathematical geometry by studying the related coverage algorithm.Then,a non-blind area network coverage connectivity scheme for forest convergence relay nodes based on LoRa communication distance is proposed,which maximizes the communication coverage and maintains a low deployment cost.The scheme can also estimate the monitoring forest.The minimum number of sink relay nodes required by the zone.Through the design of corresponding hardware and software,the experimental platform of sensory nodes and convergent relay nodes of the data collection subsystem for forest fire warning is implemented.The aggregate relay node processor STM32 ports the embedded system of ?C/OS-III,and implements the LoRa wireless through relay networking protocol in the system.Finally,on the experimental platform,the proposed networking communication schemes and the overall function of the system are tested.Although there are differences between the experimental results and the ideal communication conditions,the scheme can basically realize the tasks of data collection and relay communication networking for forest fire alarm and early warning system.From data collection to data display,it can be fully automated and applied to forest fire.In the early warning data collection subsystem,it can provide reference value for related areas of Internet of Things applications.