Experimental analysis for signal strength (SS) based estimation method in RFID systems

High performance RFID anti-collision systems require accurate information on the number of tags left in the interrogation zone. Signal strength (SS) based tag estimation was shown to be an accurate and effective method to speed up RFID tag interrogation [1-2]. SS estimation first shown to work in Manchester based RFID system [1], was analytically extended to a comprehensive list of encoding formats including all those used in commercially available tags [2]. This paper presents the SS method applied to an experimental RFID system, in which measurements of signal strength were used to identify the different numbers of tags. Our experiments verify the capabilities and identify the limitations of tag number estimation using the SS method.