3 Network Architecture

23.0413GPPRelease 18Technical realization of Cell Broadcast Service (CBS)TS

3.0 General

The chosen network architectures differ for GSM, UMTS, EPS, and 5GS. In clause 3.1 the GSM network architecture is descripted, in clause 3.2 the UMTS network architecture, in clause 3.3 the EPS network architecture, and in clause 3.4 the 5GS network architecture.

3.1 GSM Network Architecture

The basic network structure of CBS is depicted by figure 1.

Figure 1

– message transfer on link 1 is outside the scope of 3GPP specifications;

– message transfer on link 2 is described in clause 9.1;

– message transfer on link 3 is described in 3GPP TS 48.058 [11];

– message transfer on link 4 is described in 3GPP TS 44.012 [7] and the timing of messages transferred on link 4 is described in 3GPP TS 45.002 [8].

3.2 UMTS Network Architecture

The basic network structure of CBS is depicted by figure 2.

Figure 2

The basic network structure replaces the GSM BSS with the UTRAN containing the RNC and the Node B. The cell broadcast centre (CBC) is part of the core network and connected to a routing node e.g. a 3G SGSN via the Bc reference point. Thus the CBC can reach every RNC via the user plane of the Iu interface. On the logical interface  between the CBC and the RNC protocol is described in 3GPP TS 25.419 [29]. The other UTRAN related interfaces are described in the according UTRAN specifications based on the 3GPP TR 25.925 [21]. Based on this architecture and the current requirements for cell broadcast the core network elements like MSC, VLR, HLR etc are not involved for the service delivery.

The CBE and the interface between CBE and CBC are out of scope of 3GPP specifications.

3.3 EPS Network Architecture

The basic network structure of PWS architecture in E-UTRAN is depicted by figure 3.3-1.

Figure 3.3-1: PWS architecture

The cell broadcast centre (CBC) is part of the core network and connected to the MME via the SBc reference point. The interface between the CBC and the MME is described in 3GPP TS 29.168 [35] and the interface between the MME and the eNodeB is described in 3GPP TS 36.413 [34].

The CBE and the interface between CBE and CBC are out of scope of 3GPP specifications.

3.4 5GS Network Architecture

Figures 3.4-1, 3.4.-2 and 3.4-3 depict the basic network structure of 5GS PWS architecture.

Figure 3.4-1 depicts the 5GS PWS system architecture, using service-based interfaces between CBCF and AMF, showing how the network functions interact with each other. This option is further described in clauses 4 to 8. The service-based interfaces are further described in clause 9A.

Figure 3.4-1: 5GS PWS architecture

NOTE: No services are provided by CBCF or PWS-IWF, thus no service-based interfaces are depicted for these NFs in the 5GS PWS architecture.

Figure 3.4-2 depicts the basic network structure of 5GS PWS architecture using the reference point representation showing how the network functions interact with each other when no PWS-IWF is used. This option is further described in clauses 4 to 8.

Figure 3.4-2: 5GS PWS architecture in reference point representation without PWS-IWF

Figure 3.4-3 depicts the basic network structure of 5GS PWS architecture using the reference point representation showing how the network functions interact with each other when PWS-IWF is used. This option is further described in Annex B.

Figure 3.4-3: 5GS PWS architecture in reference point representation with PWS-IWF

The 5GS PWS architecture contains the following service-based interface:

Namf: Service-based interface exhibited by AMF.

The 5GS PWS architecture contains the following reference points:

N2: Reference point between the NG-RAN and the AMF.

NOTE 1: NG-RAN can be NR based or E-UTRA based (See 3GPP TS 23.501 [39] , 3GPP TS 38.413 [40] and 3GPP TS 36.413 [34]).

N50: Reference point between the AMF and the CBCF or between the AMF and the PWS-IWF.

NOTE 2: N50 uses service-based interfaces, further described in clause 9A of the present document.

SBc: Reference point between the PWS-IWF and the CBC.

The CBE and the interface between CBE and CBC are out of scope of 3GPP specifications.