Research And Design Of Key Technologies Based On LoRa Localization

In recent years,low-power wide-area network technology has begun to rise,but its outdoor location technology is still in the early stages of research.This paper focuses on the low power,low cost and long-distance communication advantages of LoRa.An outdoor positioning solution based on LoRa technology combined with TDOA is proposed.The main tasks include the following aspects:1.Combining with the characteristics of LoRa technology,two outdoor location algorithms based on TDOA are proposed,linear positioning and nonlinear positioning.The linear multilateration algorithm uses TDOA measurements and its hyperbolic positioning model to estimate the position of the target node.However,in this positioning process,the signal propagation is susceptible to multipath effects and non-line-of-sight effects,causing outliers in TDOA measurements.In this paper,the generalized ESD detection method is used to detect the outliers and remove them.Using the coordinate conversion formula,the geodetic coordinates of the gateway are converted into Cartesian coordinates.The position of the target node is estimated by using the processed TDOA values and the gateway Cartesian coordinates.Low,but there is an error in the coordinate transformation;in order to avoid loss of accuracy due to coordinate transformation,the nonlinear multilateration algorithm meshes the area where the target node is located,and always uses the geodetic coordinates and TDOA measurements to estimate the position of the target node.2.A positioning data acquisition system based on LoRa technology was built.The system consists of a terminal node,four gateways,a LoRa server and a local application.The terminal node is the target node for positioning.The terminal node broadcasts data packets.The four gateways that use the timestamp of GPS satellites for time synchronization within the positioning range receive the data packets and print them with an accurate time stamp.The gateway forwards the acquired data information to the LoRa server,and the local application obtains the data information from the LoRa server and stores it in the MySQL database.3.In the outdoor environment,using the established LoRa positioning data acquisition system,a static target node is located,the TDOA data set required for positioning and the earth coordinates of the four gateways are acquired,and the two positioning algorithms are run in MATLAB to obtain position of the target node.Making use of the position of the target node analyzes the positioning accuracy of the two positioning algorithms.In addtiion,evaluateing the LoRa technology's positioning performance.