Research On Wireless Indoor Positioning Technology Based On RSSI

With the rapid development of modern economy,the demand for LBS(Location Based Services)is increasing.The existing GPS positioning technology has been widely used in the outdoors,and is affected by various factors such as the complex indoor environment and poor signal penetration.The positioning technology cannot be well applied indoors.Because of the advantages of self-organization and low power consumption,wireless sensor network technology has also been applied in the field of indoor positioning,which has promoted the development of indoor positioning technology.For the problem of low positioning accuracy of the traditional triangular centroid positioning algorithm,an iterative localization algorithm based on distance correction is proposed in this thesis.The main steps are as follows.In the first step,an iterative positioning model is established by segmenting the positioning area,and the initial positioning coordinates are solved using the triangle centroid algorithm.In the second step,the distance offset coefficient was calculated from the current blind node location coordinates,and the median of distance offset coefficient was used to characterize the degree of deviation of the overall distance measurement.The ratio between the distance measured by the log-normal distribution model and the median is taken as the new distance between the anchor node and the blind node.In the third step,under the new distance,the four anchor nodes with the highest signal strength between the blind nodes are selected and two triangular regions are constructed.The two positioning coordinates are solved using the centroid positioning method,and these two positioning coordinates are weighted as current iteration positioning results.In the fourth step,step 2 and step 3 repeated until the number of iterations reaches the setting value.In addition,hardware circuit design and software design of the positioning system are performed in this thesis.The hardware part of the positioning system was designed for three parts in the minimum system module,the input and output module,and the radio frequency module.Based on the Z-Stack protocol stack,the software has completed the preparation of the coordinator nodes,anchor nodes,and blind node function programs.In order to display the positioning results more intuitively,the positioning system upper computer was designed by the graphic programming software LabView.In order to verify the correctness of the proposed algorithm,MATLAB software was used to simulate and analyze the noise impact factors in the cases of constant value and random value,and the positioning algorithm was verified in the actual environment.Simulation results and location experiments show that the proposed algorithm is superior to the traditional centroid positioning method and weighted centroid positioning method in positioning accuracy,and has certain value of application.