The EPS Optimised for CIoT includes the support of the following characteristics:
-
Ultra low UE power consumption.
-
Large number of devices per cell.
-
Narrowband spectrum RATs.
-
Enhanced coverage level.
The EPS Optimised for CIoT supports traffic patterns that is different as compared to the normal UEs and may support only sub-set and necessary functionalities as compared with the existing EPS.
An EPS Optimised for CIoT can be enabled by having sub-set of functionalities implemented in single logical entity C-SGN (CIoT Serving Gateway Node). C-SGN is described in
clause L.4. Mobility and Attach procedures are performed as described in other clauses for corresponding entities MME, S-GW and P-GW.
The Core Network node involved in the EPS Architecture optimised for CIoT can be deployed as DCNs within a PLMN.
The C-SGN (CIoT Serving Gateway Node) is a combined node EPC implementation option that minimizes the number of physical entities by collocating EPS entities in the control and user planes paths (e.g. MME, S-GW, P-GW), which may be preferred in CIoT deployments. The external interfaces of C-SGN implementation option are the interfaces of the respective EPC entity supported by the C-SGN, such as MME, S-GW, and P-GW.
A C-SGN supports sub-set and necessary functionalities compared with the existing EPS core network elements and also supports at least some of the following CIoT EPS Optimisations:
-
Control Plane CIoT EPS Optimisation for small data transmission.
-
User Plane CIoT EPS Optimisation for small data transmission.
-
Necessary security procedures for efficient small data transmission.
-
SMS without combined attach for NB-IoT only UEs.
-
Paging optimisations for coverage enhancements.
-
Support for non-IP data transmission via SGi tunnelling and/or SCEF.
-
Support for Attach without PDN connectivity.