Research On Indoor Localization Technology Of Wireless Sensor Network Based On Dynamic Logarithmic Path Model

The global positioning system is applied in a variety of fields,providing accurate geographic location service for outdoor environment.Because the signal is blocked by large buildings,GPS cannot be used for positioning in the indoor environment.Wireless sensor network technology integrates sensor technology,embedded computing,radio communication technology and information processing technology.Sensor nodes can be arranged in any location,and the information of the indoor environment or the detected objects can be monitored and collected in real time.Based on this,wireless sensor network technology has become an important technology of indoor location services,which fills the blank field of GPS technology and is crucial for the positioning of indoor nodes to be tested.In order to save the cost of indoor positioning,reduce the ranging error,and improve the accuracy of positioning,this paper improves the log distance path loss model and corrects the path loss parameters,which are studied and analyzed in the actual environment.ZigBee technology has the advantages of low power consumption,low cost,easy to achieve,and has been widely used in indoor positioning.In fact,when electromagnetic waves propagate in space,they may be reflected or diffracted under the influence of walls and furnishings of indoor objects,making signals generate certain loss in the propagation path.In order to reduce the ranging error,the electromagnetic wave propagation model is studied,and the log-path loss model suitable for indoor environment is selected.Since the received signal fluctuates greatly,RSSI value needs to be pretreated.Through experimental analysis,the error of RSSI value processed by Kalman filtering method is small.The relationship between the distance between the nodes and the RSSI value is analyzed,and the fixed path loss parameters and the optimal communication distance of the nodes are obtained by fitting using the least square method,so that the beacon nodes are reasonably deployed;In the positioning process,appropriate beacon nodes are selected to avoid nodes being collinear or close to collinear.In this paper,a dynamic log-path model algorithm is proposed based on log-path model estimation algorithm.in order to obtain the minimum neighborhood where the node to be tested is located,the node to be tested needs to transmit signals to the surroundings.the region formed by the three beacon nodes with larger RSSI values is the minimum neighborhood where the node to be tested is located.then according to the position relationship of the mass center in the region,the path loss parameters are preliminarily calculated.On this basis,the proportional coefficient is obtained by the relationship between the distance between nodes and the signal strength value,and the path loss parameter is corrected by introducing the correction factor.Beacon nodes are deployed in the actual environment,and the trilateration positioning algorithm is used to locate the nodes to be tested.The experimental results show that the average positioning error of the dynamic log-path model algorithm in this paper is0.672 m,which is 64% higher than that of the fixed-path model algorithm,42% higher than that of the path model estimation algorithm,and 39% higher than that of the dynamic path model algorithm before correction.In general,the modified dynamic path loss model reduces the ranging error and improves the positioning accuracy.