Query tree based tag identification method in RFID systems

A tag identification method in REID systems including a reader and a plurality of tags, the method comprising the steps of:

• (a) forming a temporary ID for each of the tags;
• (b) comparing an inquiry of the reader with a portion of the temporary ID in each tag when receiving the inquiry from the reader;
• (c) if the inquiry and the portion of the temporary ID are identical to each other, transmitting a remainder of the temporary ID in each tag to the reader;
• (d) if a collision occurs in the step (c), generating new inquiries for storing them in the reader;
• (e) if there is no collision in the step (c), transmitting an ACK signal to each tag whose temporary ID is identified to receive its real tag ID therefrom;
• and
• (f) repeating the steps (b) to (e) until there is no inquiry in the reader,
• wherein, in step (d), in case the tag responds with only a last bit of its temporary ID after step (c), the reader identifies two temporary IDs if there is any collision.