This clause provides an overview about 5GS optimizations and functionality for support of Cellular Internet-of-Things (Cellular IoT, or CIoT) according to service requirements described in TS 22.261. Cellular IoT is in earlier 3GPP releases aka Machine Type Communication (MTC) (see TS 23.401, clause 4.3.17). The specific functionality is described in the affected procedures and features of this specification, TS 23.502, TS 23.503 and other specifications.
In this Release Control Plane CIoT 5GS Optimisations (clause 5.31.4) and User Plane CIoT 5GS Optimisations (clause 5.31.18) are only supported over E-UTRA.
CIoT functionality is provided by the visited and home networks when the networks are configured to support CIoT. It applies to both the non-roaming case and the roaming case and some functionality may be dependent upon the existence of appropriate roaming agreements between the operators.
Some of the CIoT functions are controlled by subscriber data. Other CIoT functions are based on indicators sent by the UE to the network. CIoT functionality is performed by UEs that are configured to support different options as described in clause 5.31.2
Though motivated by scenarios and use cases defined in TS 22.261, the functions added to support CIoT have general applicability and are in no way constrained to any specific scenario, use case or UE types, except where explicitly stated.
In the context of CIoT the term AF denotes an SCS/AS as defined TS 23.682.