Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) procedures in idle mode

Grounded in the official 3GPP Scope excerpt

TS 36.304 (Rel-19) specifies the Access Stratum portion of idle mode procedures for UEs supporting E-UTRA, including multi-RAT devices. It defines the functional split between NAS and AS within the UE, covering behavior both when camped on an E-UTRA cell and when searching for a cell to camp on. The NAS side of idle mode is handled separately in TS 23.122. Procedures defined here also apply to UEs in RRC_INACTIVE state unless explicitly excluded. When a UE is camped on or searching for a cell of another RAT, that RAT's own specifications govern behavior. A RAN or core engineer would open this spec when troubleshooting or designing UE behavior related to cell selection and reselection in E-UTRA idle mode, or when resolving ambiguities in the NAS/AS functional boundary for idle-mode operation. It is also relevant when evaluating RRC_INACTIVE state procedures in LTE, or when assessing multi-RAT UE behavior specifically during the E-UTRA portions of idle mode operation.

Generated 10/19/2026 · cached for 90 days