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This paper proposes an anti-collision algorithm needed in the process of recognizing data of the tags when one reader and multiple passive tags simultaneously have data communications in RFID system. QTA And 4-ary QTA which are based on the Tree algorithm, have the problem that the numbers of query - response are many and the idle cycle (requesting about non-existent tag) exists in the process of recognizing the tags. Advanced 4-ary Query Tree Algorithm(A4QTA) has a 4-ary tree structure and when tag responses according to query of the reader, it applies a digital coding method, the Manchester code, in order to detect the collision point. Also, this algorithm reduces the number of query-response compared to QTA and 4-ary QTA by devising a method for one bit collision and series two bit?s collision in these bits as well as improves the performance by removing the idle cycle. |
