Analysis And Research Of Tunnel Personnel Location Algorithm Based On WIFI

Science and technology highly developing,people grow their needs to obtain their own position,and location-based services have gained more and more attention.GPS technology is widely used at present,can provide fast and accurate positioning service,widely used in mobile GPS navigation.Due to the serious attenuation when GPS signal passed through the wall,GPS can hardly be used indoor.In the last few years,with the rapid development of WIFI technology,WIFI coverage rate increased significantly,based on WIFI technology to achieve the positioning of the tunnel personnel,regardless of the network capacity,economic benefits,or positioning accuracy is very suitable.Indoor positioning technology based on RSSI,using WIFI(received signal strength)as the signal characteristic value.RSSI positioning algorithm has two categories,one is based on ranging algorithm,and the other one doesn't depend on ranging algorithm.Localization algorithm based on the ranging is according to the free space of the wireless signal transmission loss model,to determine the location of the target location RSSI value,the environment has a very large dependence.RSSI location algorithm without distance measurement,namely position fingerprint algorithm,can be divided into two stages: off-line fingerprint acquisition and online location estimation.Offline fingerprint acquisition stage needs to collect the RSSI value of each location to establish the fingerprint database.Online position estimation stage,get the RSSI value of the target position,match with the database,estimate the target position.This paper selects the tunnel personnel as the research direction,analyzes the advantages and disadvantages of the existing localization algorithm and improved these algorithm.The main contents are as follows.(1)This paper analyzed the localization algorithm based on distance,adopted the transmission loss model of point and reference points to measure the distance and adopted maximum likelihood estimation method which is based on weighted centroid position to estimate the position in order to improve the positioning accuracy of theranging algorithm.(2)In order to improve the positioning accuracy of the traditional position fingerprint location algorithm,the fingerprint data is processed by the off-line fingerprint acquisition stage.Using the method of cluster analysis to train the fingerprint database and reduce the complexity of the time of the algorithm.In the online position estimation stage,the improved nearest neighbor algorithm is used to estimate the location.This method can effectively improve the positioning accuracy of the traditional location fingerprint algorithm.(3)This paper tested the feasibility of improved positioning algorithm and compared the positioning accuracy between the before and after improvement.Analysis of factors affecting the accuracy of positioning.