Section: 5.31 Support for Cellular IoT 5.31.1 General
Content: This clause provides an overview about 5GS optimisations and functionality for support of Cellular Internet-of-Things (Cellular IoT, or CIoT) according to service requirements described in TS 22.261[ Service requirements for the 5G system ]  [2]. Cellular IoT is in earlier 3GPP releases also referred to as Machine Type Communication (MTC) (see clause 4.3.17 of TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [26]). The specific functionality is described in the affected procedures and features of this specification, in TS 23.502[ Procedures for the 5G System (5GS) ]  [3], TS 23.503[ Policy and charging control framework for the 5G System (5GS); Stage 2 ]  [45] 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 and these CIoT 5GS optimisations are not supported over Non-3GPP RAT type accesses. 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[ Service requirements for the 5G system ]  [2], 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[ Architecture enhancements to facilitate communications with packet data networks and applications ]  [36].