For RFID tags, bulk reading is the extension of single reading to a set of tags. A group of objects, all of them RFID tagged, are read completely from one single reader position at one time.
Contents
Limitations
Bulk reading is a possible use of HF (ISO 18000-3), UHF (ISO 18000-6) and SHF (ISO 18000-4) RFID tags. However, as RFID communications address RFID tags respond strictly sequentially, the time needed for bulk reading grows linearly with the number of labels to be read. This means it takes at least twice as long to read twice as many labels. Due to collision effects, the time required is greater.
Principle
A bulk of RFID tags has to be illuminated by the interrogating signal just like a single tag. This is not a challenge concerning energy, but with respect to visibility, especially in electromagnetic fields and using UHF or SHF dipole antennas. If any of the tags are shielded by other tags, they might not be sufficiently illuminated to return a sufficient response.
The response conditions for inductively coupled HF RFID tags and coil antennas in magnetic fields appear better than for UHF or SHF dipole fields, but then distance limits apply and may prevent success.
Operational advantage
Under operational conditions, bulk reading is not reliable. Bulk reading can be a rough guide for logistics decisions, but due to a high proportion of reading failures, it is not (yet) suitable for inventory management.
However, when a single RFID tag might be seen as not guaranteeing a proper read, a bunch of RFID tags, where at least one will respond, may be a safer approach for detecting a known grouping of objects. In this respect, bulk reading is a fuzzy method for process support.
From the perspective of cost and effect, bulk reading is not reported as an economical approach to secure process control in logistics.