Telemetry use cases: Radio Frequency Identification (RFID)
RFID is the use of an embedded RFID tag to identify and track an object wirelessly. RFID tags can be read up to a range of several meters, and out of the line of sight of the RFID reader. Passive tags are activated by an RFID reader. Active tags transmit without external activation. Active tags must have a power source. Passive tags can include a power source to increase their range.
RFID is used in many applications, and the types of use cases vary enormously. RFID use cases, and home patient monitoring and home energy monitoring and control use cases, have some similarities and differences.
- Invisibility
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In many use cases, the RFID reader is deployed in large numbers and must work without user intervention. The reader includes an embedded MQTT client to communicate with a central control point.
For example, in a distribution warehouse, a reader uses a motion sensor to detect a pallet. It activates the RFID tags of items on the pallet and sends data and requests to central applications. The data is used to update the location of stock. The requests control what happens to the pallet next, such as moving it to a particular bay. Airlines, and airport baggage systems, are using RFID in this way.
In some RFID use cases, the reader has a standard computing environment, such as Java ME. In these cases, the MQTT client might be deployed in a distinct configuration step, after manufacture.
- Uneven connectivity
- The RFID readers might be separated from the local control device that contains an MQTT client, or each reader might embed an MQTT client. Typically, geographical or communications factors indicate the choice of topology.
- Security
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Privacy and authenticity are security concerns in the attachment of RFID tags. RFID tags are unobtrusive and can be covertly monitored, spoofed, or tampered with.
Solution of RFID security issues increases the opportunity for deployment of new RFID solutions. Although the security exposure is in the RFID tag, and the local reader, using central information processing suggests approaches for countering different threats. For example, tag tampering might be detected by dynamically correlating stock levels against deliveries and dispatches.
- Connectivity
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RFID applications typically involved both batched store and forward of information gathered from RFID readers and immediate queries. In the distribution warehouse use case, the RFID reader is connected all the time. When a tag is read, it is published along with information about the reader. The warehousing application publishes the response back to the reader.
In the warehousing application the network is typically reliable, and the immediate requests might use fire and forget messages for low latency performance. The batched store and forward data might use exactly once messaging to minimize administration costs associated with loosing data.
- Scalability
- If the RFID application requires immediate responses, in the order of a second or two, then the RFID readers must stay connected.