Content for  TS 23.041  Word version:  17.0.0

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B (Normative)  5GS Network Architecture, AMF to CBC inter-connection via PWS-IWF |R15|Word‑p. 93

B.1  5GS PWS architecture with PWS-IWF

Figure B.1-1 depicts the optional deployment network structure of PWS architecture in 5GS with AMF to CBC inter-connection via PWS-IWF using the reference point representation showing how the network functions interact with each other. In this option the PWS-IWF implements functionality to transfer messages between N50 and SBc reference points, and vice versa.
Reproduction of 3GPP TS 23.041, Figure B.1-1: 5GS PWS architecture with PWS-IWF
The PWS architecture using PWS-IWF contains the following reference points:
Reference point between the NG-RAN and the AMF.
Reference point between the PWS-IWF and the CBC.
Reference point between the AMF and the PWS-IWF.
The CBE and the interface between CBE and CBC are out of scope of 3GPP specifications.
The present document describes logical functional entities, and how these are realized in actual deployments is an implementation and deployment issue. It can however be foreseen that the PWS-IWF functionality may be co-located with the AMF, with the CBC, or deployed as a stand-alone network function. At AMF/PWS-IWF co-location, the AMF/PWS-IWF entity interacts with the CBC via SBc. At CBC/PWS-IWF co-location, the CBC/PWS-IWF interacts with the AMF via N50. At stand-alone PWS-IWF, the PWS-IWF interacts with the AMFvia N50 and with the CBC via SBc.
A PWS-IWF co-located with AMF or a stand-alone PWS-IWF may interface to one CBC or multiple CBCs (i.e. the PWS-IWF is allowed to have SCTP transport associations established with one or multiple CBCs). A stand-alone PWS-IWF or a PWS-IWF co-located with the CBC may interface to several AMFs.

B.2  CBE Functionality

See clause 4 of the present document.

B.3  CBC FunctionalityWord‑p. 94
See clause 5 of the present document.

B.4  PWS-IWF Functionality

B.4.1  PWS-IWF generic functionality

The PWS-IWF is a logical function which functionality is to translate from N50 to SBc.
If the Write-Replace-Warning-Indication and Stop-Warning-Indication or the Restart-Indication-E-UTRAN and Failure-Indication-E-UTRAN are supported on SBc then the PWS-IWF shall manage the subscriptions for the corresponding notifications that may be received over N50.
The PWS-IWF may interface to one or multiple AMFs. The PWS-IWF may interface to one or multiple CBCs. Exceptions from straightforward mapping by the PWS-IWF from SBc based messages and parameters to SBI based messages and parameters are described in the following clauses.

B.4.2  Mapping of Repetition-Period

If the PWS-IWF receives a Write-Replace-Warning Request message from the CBC which contains the Extended Repetition-Period IE then the PWS-IWF shall map the Extended Repetition-Period IE onto the Repetition-Period NG-RAN IE in the Write-Replace-Warning Request message towards the AMF and shall ignore the Repetition-Period IE that is received from the CBC.

B.5  AMF Functionality

See clause 6 of the present document.

B.6  UE Functionality

See clause 8 of the present document.

B.7  Protocol stack when AMF and CBC inter-connects via PWS-IWFWord‑p. 95
Reproduction of 3GPP TS 23.041, Figure B.7-1: CBC - NG-RAN with PWS-IWF
  • NG Application Protocol information for Cell Broadcast (NG-AP-CB): Subset of NG-AP information that the AMF transparently relays between the NG-RAN and the PWS-IWF. NG-AP-CB corresponds to a subset of NG-AP defined in TS 38.413.
  • NG Application Protocol (NGAP): Application Layer Protocol between the NG-RAN node and the AMF. The NGAP protocol is defined in TS 38.413.
  • SBc Application Protocol (SBc-AP): Application Layer Protocol between PWS-IWF and CBC. This protocol supports transfer of warning messages.
  • SCTP for the control plane (SCTP): This protocol guarantees delivery of signalling messages between AMF and NG-RAN (N2), and between PWS-IWF and CBC (SBc). SCTP is defined in RFC 4960.
  • HTTP/2: Application layer protocol for Service based interface between AMF and CBCF. HTTP/2 is defined in RFC 7540.

$  Change historyWord‑p. 96

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