Patent ID: 8085131

Claim:
A system for preventing collision, which may occur when a Radio Frequency Identification (RFID) reader identifies an RFID tag in an RFID system including the RFID reader and the RFID tag, wherein the RFID reader comprises: an identification means for transmitting an instruction message to the RFID tag and receiving information from the RFID tag; a collision management means for recognizing collision between the RFID tag and additional tags and calculating a collision probability, the collision management means comparing the collision probability with a threshold, lowering the collision probability by reducing a number of tags when the collision probability exceeds the threshold, and repeatedly calculating the collision probability using the reduced number of tags after each respective lowering of the collision probability until the collision probability is smaller than the threshold; a tag number estimation means for estimating the number of tags by using the collision probability, the estimated number of tags being multiplied by a reduction factor after each respective lowering of the collision probability; and a reader control means for generating the instruction message, setting a size of a frame to be used in identification of the RFID tag based on the estimated number of tags, and controlling identification of the RFID tag, wherein the RFID reader performs a tag number estimation phase and an identification phase in order to identify the RFID tag, identifies the RFID tag according to Framed-Slotted ALOHA (FSA) scheme by using the estimated number of tags, and identifies colliding tags according to a binary tree scheme.