EPC Gen2
Standards & ProtocolsSecond-generation EPC protocol for UHF RFID defining the air interface, standardized internationally as ISO/IEC 18000-63.
EPC Gen2
epc-gen2/" class="glossary-term-link" data-term="EPC Gen2" data-definition="UHF RFID air interface standard." data-category="Standards & Protocols">EPC Gen2 (formally GS1." data-category="Standards & Protocols">EPCglobal UHF Class 1 Generation 2, standardised internationally as ISO 18000-63) is the dominant air interface protocol for UHF RFID operating in the 860-960 MHz band. It defines how readers and passive tags communicate, covering everything from physical-layer signalling to application-level commands.
Protocol Layers
| Layer | Specification | Content |
|---|---|---|
| Physical | Modulation, encoding, timing | Reader: DSB-ASK/SSB-ASK/PR-ASK; Tag: FM0/Miller |
| Tag identification | Singulation and anti-collision | Q-algorithm with adjustable slot counts |
| Tag access | Memory read/write, lock, kill | Four memory banks, access password, kill password |
| Security (v2) | Authentication, privacy | Crypto suite, untraceable, tag auth |
Inventory Process
A Gen2 inventory round proceeds as follows:
- Select -- the reader issues Select commands to filter the tag population (e.g., only tags in a specific EPC range).
- Query -- the reader begins an inventory round, specifying a session flag (S0-S3) and the Q parameter (2^Q time slots).
- Singulation -- each tag picks a random slot; if only one tag responds in a slot, the reader reads its data. Collisions trigger the tag to repick.
- ACK -- the reader acknowledges a successfully singulated tag, which then transmits its full EPC.
Gen2v2 Enhancements
The 2015 revision (Gen2v2) added cryptographic security features: mutual authentication using AES-128, the untraceable command for consumer privacy, and secure tag authentication to combat cloning. These features are marketed by RAIN RFID as enabling brand protection and anti-counterfeiting.
Why Gen2 Matters
EPC Gen2 is the lingua franca of UHF RFID. Any reader from Impinj, Zebra, Alien, or ThingMagic can communicate with any Gen2-compliant tag from any manufacturer. This interoperability has driven tag prices below $0.05 at billion-unit volumes and enabled global-scale deployments.
See also: RAIN RFID | ISO 18000-63 | Standards
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The RFID glossary is a comprehensive reference of technical terms, acronyms, and concepts used in Radio-Frequency Identification technology. It is designed for engineers, system integrators, and project managers who work with RFID and need clear definitions of terms like EPC, backscatter, anti-collision, and ISO 18000.
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