DESIGN AND EVALUATION OF ACTIVE RFID POSITIONING SYSTEM FOR HOME HEALTHCARE SERVICE

This paper is mainly to implement an active RFID system for 2-dimensional positioning service for home healthcare applications. It elaborates on the research processes including designing, planning and building of the system. The proposed system uses four active tags for the reference addresses and an object equipped with an active tag. It transmits the received signal strength indicator (RSSI) and the unique electronic product code (EPC) back to the tag reader through wireless transmission. Then the system employs the information, which is received from the tag reader via the monitor center, to compute the geometric relation between the reference tags and the object to determine the location of the object by the positioning algorithm. Because the radio signal is vulnerable to the interferences from the terrain and obstacles while propagating, the tag reader is likely to receive signals with bad quality thats result in errors. Therefore, this paper studies and sorts out several issues that could affect the positioning accuracy, and probes into the influence degree of distance errors by experiment. The experiment results show that the confidence rate of the distance error within 2.5 meters is as high as 95% of a 5 m × 5 m region where four coordinates references are arranged.