Download Career Final Project

4.2.3.2 Protocols - ISO 18000-6 type A
ISO 18000-6 A protocol is based on the concept of “interrogator talks first”. This means
that the tag shall wait to receive a correctly decoded command from the interrogator
before transmitting.
So the protocol is based on an exchange of; a command from the interrogator to the
tag, and a response from the tag(s) to the interrogator.
Each command and each response are contained in a frame. Each command consists
of the following fields; SoF, RFU field (reserved for protocol extension), command
code, parameters (or RFU), CRC-5, Optional parameter fields (depending on the
command), application data fields, CRC-16 and EoF. And each response consists of
the following fields; SoF, flags, mandatory and optional parameters fields (depending
on the command), application data fields, CRC-16 and EoF.
This protocol is bit-oriented. A single field is transmitted most significant bit first.
There are two forms of commands, short commands of 16 bits, Figure 4.6, and longer,
Figure 4.7.
Figure 4.6 – Short command format
Figure 4.7 – Long command format
The response from the tag, as explained before, has the structure of Figure 4.8.
Figure 4.8- General response format
4.2.3.3 Protocols - ISO 18000-6 type B
ISO 18000-6 B protocol is based on the concept of “interrogator talks first”, like ISO
18000-6 A. In this protocol data is encoded and presented in slightly different ways in
the constituent fields. For interrogator-to-tag communication, data is sent using an onoff key format. For tag-to-interrogator communication, data is sent using backscatter
techniques. This requires that the interrogator provide steady power to the tag during
the return link (tag-to-interrogator). This protocol is bit-oriented.
18