7.1.6 Query to opposite domain

23.2513GPPArchitecture and functional descriptionNetwork sharingRelease 17TS

The RAN may query the CN nodes in the opposite domain whether the UE is served by any of the sharing operators in the opposite domain. In the example below a registration attempt is made in the CS domain and the query in the opposite domain is sent to the PS domain i.e. the SGSNs and if not registered in the SGSN the SGSN sends the query to all MMEs that may hold the UEs context. If the registration attempt was made in the PS domain the query to opposite domain is send to the CS domain i.e. the MSCs.

Figure 10: PS domain query

1) The SGSN receives a UE (IMSI) query from the RAN node including an indication to also query MMEs if the UE is not served by the SGSN.

2) If the UE is not served by the SGSN the SGSN forwards the UE (IMSI) query to all MMEs that may hold the UEs context of the same operator as the SGSN.

3) If the UE is not served by any node in E-UTRAN each MME replies with a negative response to the UE query. If the UE is served by any of the MMEs, this MME replies with a positive response.

4) If the SGSN or any MME serves the UE, the SGSN replies with a positive response to the UE query from RAN. If the UE is not served by any SGSN or MME, the SGSN replies with a negative response to RAN.

Annex A (informative):
Network Resource Indicator (NRI) allocation examples

This annex contains examples for NRI co-ordination for non-supporting UEs in shared networks.