Research On LoRa Wireless Mesh Network Routing Protocol And Node Location Algorithm

In farmland environment monitoring,it has the characteristics of wide monitoring area,long period,and complex and changeable environmental factors.LoRa modulation and demodulation technology provides two-way communication by chirp spread spectrum(CSS)modulation of narrowband signals spread over a wider channel bandwidth.It provides long-distance communication in open areas up to 10-15 kilometers and 1-5 kilometers in urban areas.This technology brings great development prospects for agricultural information monitoring.In whichthe LoRaWAN communication protocol provides a star networking protocol,which limits the scope of LoRa modulation and demodulation technology in agricultural information monitoring.Therefore,a Mesh ad hoc network protocol is needed to increase the scope of LoRa communication in agricultural information monitoring.At the same time,there is no protocol content about location information in the LoRaWAN communication protocol.In agricultural information data collection and monitoring,the detailed location information of sensor nodes is an important factor for big data analysis.The location information of a large number of nodes must be determined in order to effectively sense sensor information.In view of the above challanges,this paper proposes a mesh routing protocol and node positioning algorithm based on LoRa wireless sensor networks.For the positioning algorithm in this paper,some sensor nodes obtain position information through Global Positioning System(GPS)as a coordinate reference,and then use the positioning algorithm to determine the position information of other sensor nodes,and finally achieve the coordinate position of the sensor nodes in the entire network to achieve accurate positioning lower the cost.The main research contents of this article include the following aspects:(1)Study on LoRa modulation and demodulation technology and LoRaWAN standard.LoRa is a modulation and demodulation technology,which has the characteristics of low power consumption,long distance and low rate communication,and subverts the traditional Internet of Things communication method in transmission distance.LoRaWAN defines the communication protocols and system architecture of the network.LoRaWAN between the terminal equipment and the back-end network server,and are backward compatible with all LoRa frequency bands.(2)Study on Mesh routing protocol.Firstly,the related background and application prospects of wireless network were deeply understood.This aspect of research focuses on routing protocols,topology discovery and multi-hop algorithms.During the design of the entire Mesh routing protocol,based on the AODV on-demand routing protocol,it was optimized and location information was added.(3)Study on positioning algorithms.This part first analyzes the classic ranging method.It delves into three-sided positioning method,the hyperbolic positioning method and according to the positioning requirements,then finally proposes a LoRa Gateway RSSI real-time correction positioning method.Finally,the position was estimated using Mann filter and least square method.(4)Design of hardware and software for agricultural information monitoring system.Design of hardware and software for agricultural information monitoring system.The hardware design of this article mainly includes power supply design,communication circuit design,main chip circuit design and so on.The software design includes the flow chart design,the system program is written in C language,and the routing protocol,positioning algorithm and control logic are embedded in the hardware system.This paper designs two experiments to test the communication and positioning of the system.The first experiment tested the overall operation of the system,communication networking and communication reliability;the second experiment tested the positioning feasibility and positioning accuracy of the system.The experimental analysis results show that the overall system is stable in operation,reliable in data transmission,high in wireless transmission efficiency,and high in positioning accuracy,which has effectively improved the efficiency of agricultural information collection.