METHOD FOR IDENTIFYING RF TAGS IN A RADIO FREQUENCY IDENTIFICATION SYSTEM BY ADVANCED QUERY TREE BASED ANTI-COLLISION ALGORITHM

A method for identifying an RF tag in an RFID system by using an advanced query tree based anti-collision algorithm is provided to solve problems related to production cost, weight and power consumption of the RF tag caused by other special hardware and software which can sense and process a transmission stop instruction of a reader while receiving a prefix B from each RF tag and transmitting ID matched with the prefix B bit by bit when there occurs a collision. A method for identifying an RF tag in an RFID system by using an advanced query tree based anti-collision algorithm comprises the following several steps. A reader queries a prefix B composed of binary codes with k bits to all the RF tags which embed ID composed of binary codes with n bits(S10). The reader receives k+1 bit to the final bit among the n bits from all the RF tag and detects whether there occurs a collision(S20,S30). If only one RF tag makes response, the reader identifies the RF tag composed of the k bit binary codes of the prefix B and the binary codes of the k+1-th bit to the final bit among the n bits(S40). If plural RF tags make response and there occur collisions, the reader identifies the RF tag by repeating a step of querying a prefix B' and a prefix B'' to all the RF tags wherein the prefix B' is made by adding bits of the k+1-th bit to the c-1-th bit and one bit with a value of zero to the binary codes of the prefix B, the prefix B'' is made by adding one bit with a value of one to the binary codes of the prefix B and the collision occurs at the c-th bit(S50).