Reliability in transmission between a reader and a tag is
perfectly guaranteed. All the protocols considered make use of the same type of physical
functionalities. The transmission rate depends on modulation scheme of physical layer. All
protocols have same time for transmitting their ID codes. The reader just targets tag
identi?¬?cation and does not perform any additional operations.
The transmitted message format is set based on ISO 18000-6 speci?¬?cation. Table 9.2
shows message formats of tag and reader. Protocols which have ?¬?xed-length reader
message are frame slotted ALOHA-based protocols, binary tree protocol, and ABS protocol.
Query tree protocol and ABS protocol have variable length reader message. Figure 9.9
describes data transmission between a reader and a tag. As we mentioned earlier,
the identi?¬?cation operation begins with reader??™s starting message under frame slotted
ALOHA protocols. Since we would like to evaluate the performance of protocols based
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DFSA
Binary tree
e m
2.885 m
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Number of tags
Total identification slot delay
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FIGURE 9.8
The average slot delay of DFSA and binary tree protocol.
TABLE 9.2
Message Format
Message Type Preamble Detect Header Data CRC
Reader message 400 ms 7 bits 11 bits=variable length 5 bits
Tag response 300 ms ??” 96 bits 16 bits
174 RFID Handbook: Applications, Technology, Security, and Privacy
on transmission slots, we do not consider the computation delay between end point of data
receiving and start point of data sending.
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