| With the continuous progress of science and technology,and the gradual improvement of living standards,people's demand for location-based services is increasing.Positioning service has been widely used in many industries,such as commercial activity,military service,scientific research,rescue,etc.In recent years,indoor and outdoor positioning technologies are also developing rapidly.In the outdoor environments,GPS positioning system has win the favor of the users because of its advantages such as convenient operation.But in the indoor or other confined space,the phenomenon of GPS signal shading is serious,which results in GPS cannot be applied in indoor or dense environment.So a lot of indoor positioning algorithm came into being.Indoor positioning algorithm mainly includes three kinds: triangle location method,scene analysis method and position neighbor algorithm.Triangle positioning algorithm is a typical ranging algorithm,including TOA,TDOA,AOA and RSSI methods.The principle of this method is simple,but the requirement of the equipment is high.Scene analysis method and position proximity algorithm are based on non-ranging method.Location proximity algorithm determines its location by gathering the cell identification number of the terminal.This positioning technology is easy to realize,but the positioning error is relatively large.The scene analysis method,also known as the fingerprint algorithm,is simple and the positioning accuracy is high,so it has been widely used.In dense scenes,such as the location of the light plug in the communication cabinet,the gap between the light plug is very small,only about 2cm,the traditional indoor positioning method cannot be used to realize the location of the light plug.RFID positioning technology has the advantages of small size,low cost,and high positioning accuracy in the dense environments,so it becomes the first choice for the realization of the communication cabinet.In addition,according to the compariso n of different positioning methods,we find that the positioning accuracy of fingerprint positioning method is high.Therefore the fingerprint algorithm is chosen to achieve the location of the light plug in the communication cabinet.The fingerprint positioning algorithm based on RFID is divided into two stages,the offline sampling stage and the online positioning stage.In the offline phase,the main task is to build a fingerprint database.First of all,the signal intensity of each reference tag,which is obtained by the RFID read-and-write device,is recorded in the database,and then the physical coordinates corresponding to each reference tag is also recorded in the database.Finally,the coordinates of the position to be located can be estimated by matching the signal intensity of this position with that of the reference tags using the matching algorithm.According to the difference of the matching methods,the fingerprint positioning method based on RFID can be divided into the deterministic and the probability distribution method.Aiming at the positioning problem of the optical fiber plug in the communication cabinet,this paper puts forward the dense RFID fingerprint location algorithm discussed above.And then the performance of two kinds of fingerprint algorithms,the deterministic algorithm and the probability distribution method,are simulated in this paper.The simulation results show that the proposed method has significant improvement in the precision compared with the traditional three edge location algorithm based on empirical formula,whose accuracy can reach 2cm.So the two methods can be used to realize the positioning of the optical fiber plug in the communication cabinet.But,because the probability distribution method is vulnerable to environmental interference,the deterministic method is more stable than the probability distribution method. |
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