RFID based localization techniques for indoor environment

In this paper, the Radio Frequency Identification (RFID) technology is used for indoor localization (i.e. location estimation). The location of a RFID reader is estimated based on the known locations of the RFID tags attached to the ceiling with 60 cm separation. Two arranged pattern of tags are considered. One is a square arranged pattern and another one is a triangle arranged pattern. Then, two simple location estimation methods are employed. The basic principle of location estimation for both methods is based on the average of the locations of detected tags observed by the reader. For the first estimation method, only maximum and minimum coordinates of detected tag are average. But for the second estimation method, all coordinates of detected tag are average. The effectiveness of tag arranged pattern and the location estimation methods is evaluated by the indoor experiment data. The results of the location estimated by both methods are compared. Also, the results of location estimation using the square and triangle arranged patterns are also shown. It is illustrated that the triangle arranged patterns gives better results than the square pattern in some certain. Moreover, the location estimations error for all observed locations for both methods are less than 30 cm. Furthermore, the average of the location estimation error for both methods is less than 15 cm. This is satisfied and applicable for some indoor applications.