ISO/IEC 18000-63 (EPC Gen2)

ISO/IEC 18000-63, commonly known as EPC Class 1 Generation 2 or simply Gen2, is the dominant global standard for passive UHF RFID systems operating in the 860-960 MHz frequency range. Originally developed by EPCglobal (now part of GS1) and later adopted by the International Organization for Standardization, this standard defines how RFID readers and tags communicate in supply chain, retail, and logistics applications. The standard specifies both the physical layer characteristics and the protocol that governs tag-to-reader communication, making it the backbone of modern item-level tracking systems worldwide. The physical layer of Gen2 operates in the UHF band, with specific frequencies varying by region: 902-928 MHz in North America, 865-868 MHz in Europe, and 920-925 MHz in Japan and other Asian countries. Tags are passive, meaning they harvest energy from the reader's radio signal to power their circuits and respond. Communication from reader to tag uses amplitude shift keying, while tags respond using backscatter modulation, essentially reflecting the reader's signal back with encoded data. This approach enables typical read ranges from 1 to 12 meters depending on tag design, reader power, and environmental conditions, though specialized systems can achieve even greater distances. A critical feature of Gen2 is its sophisticated anticollision protocol based on a slotted random algorithm with adaptive Q-parameter adjustment. When multiple tags enter a reader's field simultaneously, the reader uses this protocol to inventory them efficiently, reading hundreds of tags per second. The reader issues queries with a Q parameter that determines how many time slots tags can choose from to respond. Tags randomly select a slot, and the reader acknowledges successful reads while adjusting Q to optimize throughput based on the estimated tag population. Typical applications include retail inventory management, where entire store inventories can be scanned in minutes; supply chain logistics, tracking pallets and cases through distribution networks; library book management; asset tracking in healthcare and manufacturing; and access control for vehicles. The standard has become so ubiquitous that billions of Gen2 tags are produced annually, with costs dropping below a few cents per tag for high-volume applications, making it economically viable for disposable and single-use tracking scenarios.