For example, if the tag travels to Europe or Asia where the RFID
system follows the ISO standard, the smart buffer can perceive that it is being accessed by
ISO primitives. However, if the tag returns to the United States, it would switch over to
recognizing ANSI commands.
For broadcast commands, both standards allow partitioning of the tags into different
bins with a unique identi?¬?er where a logical bin can contain an unlimited number of tags.
This is accomplished by assigning that unique id to each tag contained within the bin. In
ISO this is called the Owner ID and for ANSI the Group ID. For P2P commands, a Tag ID is
used to distinguish the destination tag.
The packet analysis algorithms are summarized in Tables 11.5 and 11.6. In both standards,
commands are segregated into broadcast commands (B) and P2P commands. If the
tag receives an ISO broadcast command, it always responds if no Owner ID is set within
the tag. If an Owner ID is set, the tag only responds if an Owner ID is included in the
command and it matches the stored Owner ID. For ANSI, broadcast commands are
subdivided between 3 opcodes, 30, 16, and 35. If the opcode is either 16 or 35, the tag
always responds. If the opcode is 30, the tag only responds if the internal Group ID
TABLE 11.5
Packet Analysis Algorithm for the ISO Standard
Input Output
B=P2P Owner ID ?¬?eld Owner ID in tag Process Command
B No No Yes
B No Yes No
B Yes No Yes
B Yes Yes If Owner ID matches
P2P No No If Tag ID matches
P2P No Yes If Tag ID matches
P2P Yes No If Tag ID matches
P2P Yes Yes If Tag ID and Owner ID match
Minimum Energy=Power Considerations 221
matches the primitive Group ID.
Pages:
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431