An identification (ID) anti-collision method using a data structure to be applied to a radio frequency identification (RFID) system, includes transmitting an ID transmission request command from the reader to the tags using a predetermined request value; determining whether the IDs of the tags collide with one another, based on a bit pattern transmitted from the tags; if the IDs of the tags collide, computing a next request value to be used at a next request to transmit a request command, and if the IDs of the tags do not collide, computing and storing a future request value to be used; and if the IDs of the tags do not collide, transmitting and receiving data and a tag using an ID of the tag corresponding to the bit pattern and if the requested value is stored, transmitting a request command using the stored request value.


> Media services with access control

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