9.1.13 IW-MT-LR Procedure

23.2713GPPFunctional stage 2 description of Location Services (LCS)Release 17TS

Figure 9.16 describes the IW-MT-LR procedure. This procedure is applicable to the I-WLAN defined in TS 23.234 [52] and it is no longer maintained.

Figure 9.16: IW-MT-LR in I-WLAN

NOTE 1: Even though figure 9.16 does not specify the specific services with IW-MT-LR, this flow can be applicable for both immediate and triggered services (e.g. periodic or change of area event case).

1. A WLAN UE selects a WLAN AN and establishes the WLAN connection and is authenticated in I-WLAN. The WLAN AN may send the current location of WLAN AN to the WLAN UE. The WLAN AN may send its location to the AAA. The tunnel may be established with between WLAN UE and one of PDGs in PLMN.

2. An external LCS client sends the LCS request to the GMLC. An external LCS client requests the current location, e.g. immediate location request, from a GMLC. The LCS Client may also request a triggered location request, e.g. periodic or change of area event. The GMLC verifies the identity of the LCS client and its subscription to the LCS service requested and derives the MSISDN or IMSI or pseudonym of the target UE to be located and the LCS QoS from either subscription data or data supplied by the LCS client.

The LCS request may carry also the Service Identity and the Codeword. The GMLC may verify that the Service Identity received in the LCS request matches one of the service identities allowed for the LCS client. If the service identity does not match one of the service identities for the LCS client, the GMLC shall reject the LCS request. Otherwise, the GMLC can map the received service identity in a corresponding service type.

If the location request is originated by a Requestor, the Requestor Identity may be added to the LCS service request. The LCS client should authenticate the Requestor Identity but this is outside the scope of this specification. The LCS service request may also contain the type of the Requestor identity if the requestor identity was included.

The GMLC performs privacy check on the basis of the UE user’s privacy profile stored in the GMLC or PPR.

3. Steps 3 and 4 may be skipped if the GMLC already has the address of the AAA server. Steps 3 to 6 may be skipped if the GMLC has alternative access to the UE’s IP address (e.g. using dynamic DNS or from a previous interaction with the UE) or is able to instigate step 7 without knowing this address (e.g. using MT-SMS or WAP Push in the case of SUPL). GMLC requests the address of AAA server and WLAN UE capability to the HSS. In this case, the capability information of the WLAN UE refers to capability information of the terminal relevant to positioning such as whether the terminal supports the OMA SUPL (OMA AD SUPL [38], OMA TS ULP [39]) or whether it supports another location procedures.

4. HSS returns the address of AAA server of the target WLAN UE and the capability of the WLAN UE to GMLC.

5. If the target WLAN UE supports the OMA SUPL, GMLC queries AAA to obtain the address of WLAN UE. GMLC may request the location of WLAN UE.

6. If its location is available and the quality of position meets the LCS QoS requested by GMLC, then AAA responds with available location information of the WLAN UE to the GMLC. Otherwise, GMLC retrieves the address of WLAN UE from AAA. If there is no tunnel is available between the PDG and the WLAN UE, the AAA will return an indication that UE is not reachable.

7. GMLC initiates positioning procedure. This shall use SUPL procedures based on OMA SUPL (OMA AD SUPL [38], OMA TS ULP [39]). If the tunnel between the WLAN UE and the PDG is available and the GMLC has obtained the UE IP address, GMLC generates an SUPL initiation message, and transmits it to the WLAN UE by using the address of WLAN UE over available IP connection between the WLAN UE and the PDG. If the tunnel between the WLAN UE and the PDG is not available or if the GMLC did not obtain the UE IP address, GMLC sends an SUPL initiation message using the UE IP address if available or by other means (e.g. MT-SMS or WAP Push).

8. The location information obtained will be transferred to external LCS client.

NOTE 2: The GMLC may, as an implementation option, cache the results received in step 4 and/or step 6 in order to avoid further queries when a location request is received for the same target UE at a later time and the AAA server address and/or WLAN UE address, respectively, has not changed.