Tag 0101
0
00 01 10 11
1
Tag 1001
010 011
Tag 1101
Idle
Readable
Collision
148 RFID Handbook: Applications, Technology, Security, and Privacy
8.6 Adaptive Binary Splitting
ABS uses random numbers with the aim of splitting a set of tags transmitting at the same
cycle like the binary tree protocol but starts the tree search only from the nodes of readable
cycles of the last frame. AQS, as described in the previous section, can reduce collisions
as compared with the binary tree protocol and the query tree protocol, but it produces idle
cycles. To guarantee identi?¬?cation of all tags, the reader uses not only queries of readable
cycles but also queries of idle cycles of the last frame. Though the query deletion procedure
of AQS eliminates unnecessary idle cycles by leaving tags, it cannot be avoided that
the start of the tree search includes some of idle cycles to cover all possible ranges of the
tag ID. On the contrary, ABS starts tag identi?¬?cation only from readable cycles of the last
frame and uses binary numbers selected randomly in each con?¬‚icting tag for the splitting
procedure. During tag identi?¬?cation, ABS allocates different cycles to tags by revising the
tag??™s counter into the ranking of recognition. The allocation of cycles to staying tags
enables fast identi?¬?cation without collisions between staying tags in the next identi?¬?cation
frame.
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