An Efficient Tag Collision Detection Method for Active RFID Systems

We propose an efficient tag collision detection method using the asynchronous mode of the RF transceiver for active RFID systems. In the proposed method, active RFID tags communicate using the synchronous mode of the RF transceiver to reduce the packet processing overheads and power consumption, but the active RFID reader uses the asynchronous mode for packet reception from the tags to detect the occurrence of tag collisions by analyzing the raw signal pulses demodulated from the RF transceiver. We implemented an active RFID reader and multiple tags that supported the proposed tag collision detection method. Experiments with a reader and 60 tags showed that the proposed method could detect tag collisions with a high average accuracy of 97.22%, and could choose the optimum frame size dynamically by estimating the number of tags, which results in the improvement of the tag collection performance.