4.10 Introduction of CIoT EPS Optimisations

23.4013GPPGeneral Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) accessRelease 18TS

CIoT EPS Optimisations provide improved support of small data transfer. One optimisation is based on User Plane transport of user data and is referred to as User Plane CIoT EPS Optimisation. Another optimisation, known as Control Plane CIoT EPS Optimisation, transports user data or SMS messages via MME by encapsulating them in NAS, reducing the total number of control plane messages when handling a short data transaction. For EPC Mobile Originated Location Request (EPC-MO-LR) and EPC Mobile Terminated Location Request (EPC-MT-LR) when the UE and network support Control Plane CIoT EPS Optimisation, Control Plane Service Request is used. These optimisations can be used separately e.g. if the UE or the network supports one of them, or in parallel if the UE and the network supports both. If both the Control Plane and User Plane CIoT EPS Optimisations are supported for a UE, the PDN connections that only use the Control Plane CIoT EPS Optimisation, i.e. the MME has included Control Plane Only Indicator in the ESM request, will only be handled via the Control Plane CIoT EPS Optimisation. All other PDN connections are handled using Control Plane or User Plane CIoT EPS Optimisations. In addition, the Control Plane CIoT Optimisation can be used to support PDN connections to an SCEF, while regular S1-U data transfer is used independently to support PDN connections to P-GW. The MME shall consistently include Control Plane Only Indicator either in all SGi PDN connections of a UE or in none of them. All the SGi PDN connections of a UE shall either use S11-U or S1-U at any point in time.

The CIoT data could include e.g. status information, measurement data from Machine-to-Machine applications.

Several types of MME are envisaged, e.g.

– an MME that supports either User Plane or Control Plane CIoT EPS Optimisation;

– an MME that supports both User Plane and Control Plane CIoT EPS Optimisations;

– an MME that does not support any CIoT EPS Optimisations.

The E-UTRAN shall support the routeing of UEs to an MME that can process the request from the UE.

The CIoT EPS Optimisations are negotiated as described in clause 4.3.5.10 "Preferred and Supported Network Behaviour".

CIoT EPS Optimisations may be supported also by UEs that are not limited to low complexity and low throughput applications for Machine Type Communications.

If Control Plane CIoT EPS Optimisation applies, separation of S11-U from S1-U may be required, and if required, the MME and the Serving GW shall handle the IP address and TEID for the S1-U and the address and TEID for the S11-U separately.

NOTE: Homogeneous support of separation of S11-U from S1-U in the MMEs and Serving GWs is assumed.