H.4 Location handling

23.1673GPPIP Multimedia Subsystem (IMS) emergency sessionsRelease 17TS

The applicable location solutions are specified in TS 23.271 [5] for control plane with UTRAN and E-UTRAN access, in TS 23.501 [48] and TS 23.502 [49] for control plane with NG-RAN access and in SUPL 2.0 (OMA AD SUPL[15], OMA TS ULP [16]) for user plane. For SUPL, SUPL Initiation Function using UDP/IP (OMA AD SUPL [15]) shall be supported by the SET.

If the operator policy requires network provided location using PCC-based solutions for the UE location (e.g. serving cell), the P-CSCF retrieves location information from the access network and includes it in the emergency service request, as described in TS 23.228 [1]. The UE location is marked as being network provided to distinguish it from location information that the UE provided.

If the operator policy requires network provided location using the LRF-based solution for the UE location (e.g. serving cell), the P-CSCF forwards the emergency request to E-CSCF. The E-CSCF retrieves location information from LRF as described in clause 6.2.2.

Operator policies in the P-CSCF and E-CSCF should be aligned to ensure that the E-CSCF doesn’t attempt to retrieve location information from the LRF if network-provided location information is present in the initial emergency request. However, as described in clause 6.2.2, the E-CSCF may request the LRF to retrieve additional location information (e.g. the UE’s geographical location information).