ETSI - TS 123 122
Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; 5G; Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode
|Publication Date:||1 April 2021|
The present document gives an overview of the tasks undertaken by the Core network protocols of a Mobile Station (MS) when in idle mode, that is, switched on but typically not having a dedicated channel allocated. It also describes the corresponding network functions. The idle mode functions are also performed by a GPRS MS as long as no dedicated channel is allocated to the MS. The conditions when the idle mode functions are performed by an MS in the UTRA RRC connected mode states are specified in 3GPP TS 25.331 . The conditions when the idle mode functions are performed by an MS in the E-UTRAN are specified in 3GPP TS 36.304 . The conditions when the idle mode functions are performed by an MS in the NG-RAN are specified in 3GPP TS 36.304  and 3GPP TS 38.304 . The conditions when the idle mode functions are performed by an MS in the NG-RAN RRC inactive state are specified in 3GPP TS 36.331  and 3GPP TS 38.331 .
The present document defines the PLMN selection for a multi mode MS that supports both 3GPP and 3GPP2 systems. The common PLMN selection logic covers also PLMNs that are available in 3GPP2 system, but the present document makes no changes on the cdma2000® signalling towards networks that are available via 3GPP2 system.
The present document gives procedures for using the CSG cells, whenever such use is permitted.
The present document gives procedures for using the CAG cells, when the MS supports CAG.
The present document specifies the SNPN selection.
This 3GPP TS outlines how the requirements of the 22 series Technical Specifications (especially 3GPP TS 22.011 ) on idle mode operation shall be implemented. Further details are given in 3GPP TS 24.008 .
Clause 2 of this 3GPP TS gives a general description of the idle mode process. Clause 3 outlines the main requirements and technical solutions of those requirements. Clause 4 describes the processes used in idle mode. There is inevitably some overlap between these clauses.
NOTE: cdma2000® is a registered trademark of the Telecommunications Industry Association (TIA-USA).
The present document describes the procedures for control plane solution of steering of roaming in 5GS in annex C.
Annex C is applicable to the MS, the AMF, the UDM and the SOR-AF in the 5GS.
The present document does not consider GERAN Iu mode.