9.2 Mobile Originating Location Request

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

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

9.2.1 Mobile Originating Location Request, Circuit Switched (CS-MO-LR)

The following procedure shown in figure 9.7 allows an UE to request either its own location and optionally, velocity, location assistance data or broadcast assistance data message ciphering keys from the network. Location assistance data may be used subsequently by the UE to compute its own location throughout an extended interval using a mobile based position method. The ciphering key enables the UE to decipher other location assistance data broadcast periodically by the network. The MO‑LR after location update request may be used to request ciphering keys or GNSS assistance data using the follow-on procedure described in TS 24.008 [24]. The procedure may also be used to enable an UE to request that its own location be sent to an external LCS client.

Figure 9.7: General Network Positioning for CS-MO-LR

9.2.1.1 Location Preparation Procedure

1) If the UE is in idle mode, the UE requests a radio connection setup and sends a CM service request indicating a request for a call independent supplementary services to the VMSC/MSC server via RAN.

2) RAN shall convey the CM service request to the core network. If the UE is in dedicated mode, the UE sends a CM Service Request on the already established radio connection.

3) The VMSC/MSC server instigates authentication and ciphering if the UE was in idle mode or returns a Direct Transfer CM Service Accept if the UE was in dedicated mode. The UE will inform the network about its LCS capabilities, as described in clause 6.3.4.

4) The UE sends a LCS CS-MO-LR Location Services invoke to the VMSC/MSC server. Different types of location services can be requested: location estimate of the UE, location estimate of the UE to be sent to an external LCS client, location assistance data or broadcast assistance data message ciphering keys. If the UE is requesting its own location estimate or that its own location be sent to an external LCS client, this message carries LCS requested QoS information (e.g. accuracy, response time, LCS QoS Class), the requested maximum age of location and the requested type of location (e.g. "current location", "current or last known location"). If the UE is requesting that its location be sent to an external LCS client, the message shall include the identity of the LCS client and may include the address of the GMLC through which the LCS client should be accessed. In addition, a Service Identity indicates which MO-LR service of the LCS Client is requested by the UE may be included. The message also may include a pseudonym indicator to indicate a pseudonym should be assigned by the network and transferred to the LCS Client as the UE’s identity. If the UE is instead requesting location assistance data or ciphering keys, the message specifies the type of assistance data or deciphering keys and the positioning method for which the assistance data or ciphering applies. For an LCS CS-MO-LR Location Services invoke, the VMSC/MSC server shall assign a GMLC address, i.e. V-GMLC address, which is stored in the VMSC/MSC server. If a V-GMLC address is not available, the VMSC/MSC server may reject the location request. The VMSC/MSC server verifies in the UE’s subscription profile that the UE has permission to request its own location, request that its location be sent to an external LCS client or request location assistance data or deciphering keys (whichever applies). If the UE is requesting positioning and has an established call, the VMSC/MSC server may reject the request for certain non-speech call types.

5) In case the requested type of location is "current or last known location" and the requested maximum age of location information is sent from UE, the VMSC/MSC server verifies whether it stores the previously obtained location estimate of the target UE. If the VMSC/MSC server stores the location estimate and the location estimate satisfies the requested maximum age of location, this step and steps 6 and 7 may be skipped. Otherwise the VMSC/MSC server sends a Location Request message to RAN associated with the Target UE. The message indicates whether a location estimate or location assistance data is requested and, in GSM, includes the UE’s location capabilities. If the UE’s location is requested, the message also includes the requested QoS. If location assistance data is requested, the message carries the requested types of location assistance data.

9.2.1.2 Positioning Measurement Establishment Procedure

6) If the UE is requesting its own location, RAN determines the positioning method and instigates the particular message sequence for this method, as specified in UTRAN Stage 2, TS 25.305 [1] and GERAN Stage 2, TS 43.059 [16]. If the UE is instead requesting location assistance data, RAN transfers this data to the UE as described in subsequent clauses in TS 25.305 [1] and TS 43.059 [16] UE.

9.2.1.3 Location Calculation and Release Procedure

7) When a location estimate best satisfying the requested QoS has been obtained or when the requested location assistance data has been transferred to the UE, RAN returns a Location Report to the VMSC/MSC server with an indication whether the obtained location estimate satisfies the requested accuracy or not. This message carries the location estimate or ciphering keys if this was obtained. If a location estimate or deciphering keys were not successfully obtained or if the requested location assistance data could not be transferred successfully to the UE, a failure cause is included in the Location Report.

8) If the location estimate was successfully obtained, the VMSC/MSC server shall send a MAP Subscriber Location Report to the V-GMLC assigned in the step 4, carrying the MSISDN/IMSI of the UE, the event causing the location estimate (CS‑MO-LR) and the location estimate, its age, obtained accuracy indication and the LCS QoS Class requested by the target UE. In addition, the MAP Subscriber Location Report may include the pseudonym indicator, the identity of the LCS Client, the GMLC address and the Service Identity specified by the UE, if available.

9) Upon receipt of the MAP Subscriber Location Report, the V-GMLC shall determine whether the UE requests transfer of its location estimate to an external LCS Client. If the identity of the LCS Client is not available, this step and steps 10 to 14 are skipped. Otherwise, the V-GMLC shall send the MO-LR Location Information to the H-GMLC (the V-GMLC may query the HLR/HSS of the UE to obtain the address of the H-GMLC), carrying the MSISDN/IMSI of the UE, the event causing the location estimate (CS‑MO-LR), the location estimate and its age and the identity of the LCS Client. The pseudonym indicator and/or the GMLC address specified by the UE may also be included if available.

10) If the pseudonym indicator is included in the MO-LR Location Information, the H-GMLC assigns or asks the PMD to assign a pseudonym to the UE. If the identity of the LCS Client and the GMLC address access to the LCS Client are available, the H-GMLC shall send the MO-LR Location Information to the specified GMLC. If the identity of the LCS Client is available but the GMLC address access to the LCS Client is not available, the H-GMLC determines whether the specified LCS Client is accessible. If yes, the H-GMLC shall send the Location Information to the LCS Client, then the H-GMLC itself act as the specified GMLC, this step and step 13 are skipped. If not, according to the LCS Client identity, the H-GMLC shall determine a GMLC that can access the LCS Client, and send the MO-LR Location Information to the GMLC, carrying the MSISDN or the pseudonym of the UE, the identity of the LCS client, the event causing the location estimate (CS‑MO-LR), location estimate and its age.

11) If the identified LCS Client is not accessible, this step and step 12 are skipped. Otherwise the GMLC transfers the location information to the LCS client, carrying the MSISDN/IMSI or the pseudonym of the UE, the event causing the location estimate (CS-MO‑LR), the Service Identity, if available, and the location estimate and its age, in accordance with the LCS QoS Class requested by the target UE. If the UE requested LCS QoS class was Assured, GMLC sends the result to the LCS client only if the result has been indicated to fulfil the requested accuracy. If the UE requested LCS QoS class was Best Effort, GMLC sends whatever result it received to the LCS client with an appropriate indication if the requested accuracy was not met.

12) If the LCS Client does not support MO-LR (for temporary or permanent reasons) or can not handle the location estimate of the UE, e.g. the LCS Client does not know the Service Identity, or the UE does not register to the LCS Client, the LCS Client have no corresponding data of the UE, the LCS Client shall return the Location Information ack message to the GMLC or the H-GMLC (in case the LCS Client received Location Information is sent from H-GMLC) with a suitable error cause. Otherwise, the LCS Client handles the location estimate according to the Service Identity, sends the GMLC or the H-GMLC the Location Information ack message signalling that the location estimate of the UE has been handled successfully.

13) If the identified LCS Client is not accessible, the GMLC sends MO-LR Location Information Acknowledgement to the H-GMLC with an appropriate error cause. Otherwise, the GMLC shall send MO-LR Location Information Acknowledgement to the H-GMLC. The message shall specify whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not, the corresponding error cause obtained in step 12. The GMLC may record charging information both for the LCS Client and inter-operator revenue charges.

14) In case the H-GMLC receives the MO-LR Location Information Acknowledgement from the GMLC, it shall forward the MO-LR Location Information Acknowledgement from the GMLC to the V-GMLC, and record charging information both for the UE and inter-working revenue charges.

In case the H-GMLC receives the Location Information Acknowledgement from the LCS Client, it shall send MO-LR Location Information Acknowledgement to the V-GMLC. The message shall specify whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not, the corresponding error cause obtained in step 12. The H-GMLC shall record charging information both for the UE and inter-working revenue charges.

15) In case the V-GMLC receives the MO-LR Location Information Acknowledgement from the H-GMLC, the V-GMLC shall record charging information both for the UE and inter-working revenue charges and send the MAP Subscriber Location Report Acknowledgement to the VMSC/MSC server, carrying the information specifies whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not success, the corresponding error cause obtained in step 14.

In case the V-GMLC receives the MAP Subscriber Location Report from the VMSC/MSC server and it is not required to send to any LCS Client, the V-GMLC shall record charging information for the UE and response the MAP Subscriber Location Report Acknowledgement to the VMSC/MSC server.

16) The VMSC/MSC server returns a CS-MO-LR Return Result to the UE carrying any location estimate requested by the UE including the indication received from RAN whether the obtained location estimate satisfies the requested accuracy or not, ciphering keys or an indicator whether a location estimate was successfully transferred to the identified LCS client. If the location estimate was successfully transferred to the identified LCS Client, the CS-MO-LR Return Result message shall specify whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not, the corresponding error cause obtained in step 15.

17) The VMSC/MSC server may release the CM, MM and radio connections to the UE, if the UE was previously idle, and the VMSC/MSC server may record charging information.

9.2.2 Mobile Originating Location Request, Packet Switched (PS-MO-LR)

The following procedure shown in figure 9.8 allows an UE to request either its own location and optionally, velocity; location assistance data or broadcast assistance data message ciphering keys from the network. Location assistance data may be used subsequently by the UE to compute its own location throughout an extended interval using a mobile based position method. A ciphering key enables the UE to decipher other location assistance data broadcast periodically by the network. The PS‑MO‑LR may be used to request ciphering keys or GNSS assistance data. The procedure may also be used to enable an UE to request that its own location be sent to an external LCS client.

Figure 9.8: General Network Positioning for packet switched MO-LR

9.2.2.1 Location Preparation Procedure

1) In UMTS, if the UE is in idle mode, the UE requests a PS signalling connection and sends a Service request indicating signalling to the SGSN via the RAN. If the UE already has PS signalling connection, the UE does not need to send Service request. Security functions may be executed. These procedures are described in TS 23.060 [15]. In GSM this signalling step is not needed.

2) The UE sends a LCS PS-MO-LR Location Services invoke message to the SGSN. Different types of location services can be requested: location estimate of the UE, location estimate of the UE to be sent to an external LCS client, location assistance data or broadcast assistance data message ciphering keys. If the UE is requesting its own location or that its own location be sent to an external LCS client, this message carries LCS requested QoS information (e.g. accuracy, response time, LCS QoS Class), the requested maximum age of location and the requested type of location (e.g. "current location", "current or last known location"). If the UE is requesting that its location be sent to an external LCS client, the message shall include the identity of the LCS client and may include the address of the GMLC through which the LCS client should be accessed. In addition, a Service Identity indicates which MO-LR service of the LCS Client is requested by the UE may be included. The message also may include a pseudonym indicator to indicate a pseudonym should be assigned by the network and transferred to the LCS Client as the UE’s identity. If the UE is instead requesting location assistance data or ciphering keys, the message specifies the type of assistance data or deciphering keys and the positioning method for which the assistance data or ciphering applies. For an LCS PS-MO-LR Location Services invoke, the SGSN shall assign a GMLC address, i.e. V-GMLC address, which is stored in the SGSN. If a V-GMLC address is not available, the SGSN may reject the location request. The SGSN verifies the subscription profile of the UE and decides if the requested service is allowed or not.

3) In case the requested type of location is "current or last known location" and the requested maximum age of location information is sent from UE, the SGSN verifies whether it stores the previously obtained location estimate of the target UE. If the SGSN stores the location estimate and the location estimate satisfies the requested maximum age of location, this step and steps 4 and 5 may be skipped. Otherwise the SGSN sends a Location Request message to the RAN associated with the Target UE’s location. The message indicates whether a location estimate or location assistance data is requested. If the UE’s location is requested, the message also includes the requested QoS. If location assistance data is requested, the message carries the requested types of location assistance data. The message carries also location parameters received in the Service Invoke message.

9.2.2.2 Positioning Measurement Establishment Procedure

4) If the UE is requesting its own location, the actions described in UTRAN Stage 2, TS 25.305 [1] or GERAN stage 2 TS 43.059 [16] are performed. If the UE is instead requesting location assistance data, the RAN transfers this data to the UE as described in subsequent clauses. The RAN determines the exact location assistance data to transfer according to the type of data specified by the UE, the UE location capabilities and the current cell.

9.2.2.3 Location Calculation and Release Procedure

5) When a location estimate best satisfying the requested QoS has been obtained or when the requested location assistance data has been transferred to the UE, the RAN returns a Location Report to the SGSN with an indication whether the obtained location estimate satisfies the requested accuracy or not. This message carries the location estimate or ciphering keys if this was obtained. If a location estimate or deciphering keys were not successfully obtained or if the requested location assistance data could not be transferred successfully to the UE, a failure cause is included in the Location Report.

6) If the location estimate was successfully obtained, the SGSN shall send a Subscriber Location Report to the V-GMLC assigned in the step 2, carrying the MSISDN/IMSI of the UE, the event causing the location estimate (PS-MO‑LR) and the location estimate, its age, obtained accuracy indication and the LCS QoS Class requested by the target UE. In addition, the Subscriber Location Report may include the pseudonym indicator, the identity of the LCS Client, the GMLC address and the Service Identity specified by the UE, if available.

7) Upon receipt of the Subscriber Location Report, the V-GMLC shall determine whether the UE requests transfer of its location estimate to an external LCS Client. If the identity of the LCS Client is not available, this step and steps 8 to 12 are skipped. Otherwise, the V-GMLC shall send the MO-LR Location Information to the H-GMLC (the V-GMLC may query the HLR/HSS of the UE to obtain the address of the H-GMLC), carrying the MSISDN/IMSI of the UE, the event causing the location estimate (PS‑MO-LR), the location estimate and its age, and the identity of the LCS Client. The pseudonym indicator and/or the GMLC address specified by the UE may also be included if available.

8) If the pseudonym indicator is included in the MO-LR Location Information, the H-GMLC assigns or asks the PMD to assign a pseudonym to the UE. If the identity of the LCS Client and the GMLC address access to the LCS Client are available, the H-GMLC shall send the MO-LR Location Information to the specified GMLC. If the identity of the LCS Client is available but the GMLC address access to the LCS Client is not available, the H-GMLC determines whether the specified LCS Client is accessible. If yes, the H-GMLC shall send the Location Information to the LCS Client, then the H-GMLC itself act as the specified GMLC, this step and step 11 are skipped. If not, according to the LCS Client identity, the H-GMLC shall determine a GMLC that can access the LCS Client, and send the MO-LR Location Information to the GMLC, carrying the MSISDN or the pseudonym of the UE, the identity of the LCS client, the event causing the location estimate (PS‑MO-LR), location estimate and its age.

9) If the identified LCS Client is not accessible, this step and step 10 are skipped. Otherwise the GMLC transfers the location information to the LCS client, carrying the MSISDN/IMSI or the pseudonym of the UE, the event causing the location estimate (PS-MO‑LR), the Service Identity, if available, and the location estimate and its age, in accordance with the LCS QoS Class requested by the target UE. If the UE requested LCS QoS class was Assured, GMLC sends the result to the LCS client only if the result has been indicated to fulfil the requested accuracy. If the UE requested LCS QoS class was Best Effort, GMLC sends whatever result it received to the LCS client with an appropriate indication if the requested accuracy was not met.

10) If the LCS Client does not support MO-LR (for temporary or permanent reasons) or can not handle the location estimate of the UE, e.g. the LCS Client does not know the Service Identity, or the UE does not register to the LCS Client, the LCS Client have no corresponding data of the UE, the LCS Client shall return the Location Information ack message to the GMLC or the H-GMLC (in case the LCS Client received Location Information is sent from H-GMLC) with a suitable error cause. Otherwise, the LCS Client handles the location estimate according to the Service Identity, sends the GMLC or the H-GMLC the Location Information ack message signalling that the location estimate of the UE has been handled successfully.

11) If the identified LCS Client is not accessible, the GMLC sends MO-LR Location Information Acknowledgement to the H-GMLC with an appropriate error cause. Otherwise, the GMLC shall send MO-LR Location Information Acknowledgement to the H-GMLC. The message shall specify whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not, the corresponding error cause obtained in step 10. The GMLC may record charging information both for the LCS Client and inter-operator revenue charges.

12) In case the H-GMLC receives the MO-LR Location Information Acknowledgement from the GMLC, it shall forward the MO-LR Location Information Acknowledgement from the GMLC to the V-GMLC, and record charging information both for the UE and inter-working revenue charges.

In case the H-GMLC receives the Location Information Acknowledgement from the LCS Client, it shall send MO-LR Location Information Acknowledgement to the V-GMLC. The message shall specify whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not, the corresponding error cause obtained in step 10. The H-GMLC shall record charging information both for the UE and inter-working revenue charges.

13) In case the V-GMLC receives the MO-LR Location Information Acknowledgement from the H-GMLC, the V-GMLC shall record charging information both for the UE and inter-working revenue charges and send the Subscriber Location Report Acknowledgement to the SGSN, carrying the information specifies whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not success, the corresponding error cause obtained in step 12.

In case the V-GMLC receives the Subscriber Location Report from the SGSN and it is not required to send to any LCS Client, the V-GMLC shall record charging information for the UE and response the Subscriber Location Report Acknowledgement to the SGSN.

14) The SGSN returns a Service Response message to the UE carrying any location estimate requested by the UE including the indication received from RAN whether the obtained location estimate satisfies the requested accuracy or not, ciphering keys or an indicator whether a location estimate was successfully transferred to the identified LCS client. If the location estimate was successfully transferred to the identified LCS Client, the Service Response message shall specify whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not, the corresponding error cause obtained in step 13. The SGSN may record charging information.

9.2.3 MO-LR Request for Periodic Location Transfer to a Third Party

The following procedure shown in figure 9.8a allows a UE to instigate a periodic transfer of location to an external LCS client. The procedure would be executed once after which it would be followed by the procedure described in clause 9.1.12.2.

Figure 9.8a: Deferred MO-LR Initiation for Periodic Location in CS and PS domain

1) to 2) If the UE is in idle mode, the UE requests a radio connection setup and sends a CM Service Request indicating a request for call independent supplementary service to the VMSC/MSC server via RAN (CS domain). If the UE is in dedicated mode, the UE sends a CM Service Request on the already established radio connection. The VMSC/MSC server instigates authentication and ciphering if the UE was in idle mode or returns a CM Service Accept if the UE was in dedicated mode.

For PS domain, in UMTS, if the UE is in idle mode, the UE requests a PS signalling connection and sends a Service Request indicating signalling to the SGSN via RAN. If the UE already has PS signalling connection, the UE does not need to send the Service Request. Security functions may be executed. These procedures are described in TS 23.060 [15]. In GSM this signalling step is not needed.

3) The UE sends an LCS MO-LR Invoke for periodic transfer of location to a third party LCS client. The UE shall include the periodic location related parameters (reporting interval and total number of reports). The UE shall also include the identity of the LCS client and may include the address of the GMLC through which the LCS client can be accessed. The UE may include a request for use of MO-LR Short Circuit (e.g. if the UE supports UE based positioning). The absence of an H-GMLC assigned LDR reference number in this case indicates that the request has not yet been authorized.

4) to 7) The request to initiate periodic location shall be transferred in succession from the MSC/SGSN to the V‑GMLC, H-GMLC, R-GMLC serving the LCS client and finally may be transferred to the LCS client. The periodic location parameters (reporting interval and number of reports) are included as well as any request for use of MO-LR Short Circuit. Any entity (MSC/SGSN, V‑GMLC, H‑GMLC, R‑GMLC and, if notified, LCS Client) is enabled to accept or refuse the request. In addition, if the request was accepted, any entity is free to reject use of MO-LR Short Circuit. If the request is accepted, a LDR reference number is assigned by the H‑GMLC.

8) to 11) The response transferred back to the MSC/SGSN shall indicate acceptance or rejection and whether MO‑LR short circuit (if requested) has been accepted. The response also includes the LDR reference number assigned by the H-GMLC and the H-GMLC address. The H-GMLC may include in the response a list of PLMNs and possibly associated radio access technologies, either prioritized or non-prioritized, in which subsequent location estimates must be obtained and an indication for each PLMN (and possibly each associated radio access technology) of whether periodic location in the RAN is supported. If no list is included, subsequent locations are restricted to the current serving PLMN only

12) The MSC/SGSN returns the result of the request to the UE in a LCS MO-LR Return Result message including the LDR reference number, the H-GMLC address any reporting PLMN list and an indication whether MO-LR Short Circuit is allowed (if requested by the UE in step 3.

13a) The UE may instigate release of the CM, MM/GMM and radio connections – e.g. if the request was rejected or if the MSC/SGSN provided a list of PLMNs that did not include the serving PLMN (or if the serving PLMN was included in a prioritized list with a lower priority). Assuming the request was accepted, the UE may then initiate reporting of the first location estimate using the procedure described in clause 9.1.12.2 and beginning at step 1.

13b) If the request was accepted and the serving PLMN can be used for subsequent location, the UE may initiate reporting of the first location estimate by sending an MO-LR request indicating transfer of location to the LCS Client using the procedure described in clause 9.1.12.2 and beginning at step 3.

NOTE: If the UE receives a response in step 12 indicating that the MO-LR request for periodic location transfer to a third party cannot be supported (for temporary or permanent reasons), the UE may periodically invoke the MO-LR procedure for location transfer to a third party defined in clause 9.2.1 for the CS domain (CS-MO-LR) and in clause 9.2.2 for the PS domain (PS-MO-LR).

9.2.4 MO-LR Request for Periodic Self Location

The following procedure shown in figure 9.8b allows an UE to request its own location periodically if the RAN serving the target UE supports periodic location. This procedure is useful if a UE only supports UE-assisted positioning or has no positioning capability.

Figure 9.8b: MO-LR for Periodic Self Location with Periodic Positioning in the RAN

3) The UE sends an MO-LR invoke requesting periodic self location. The request includes the required QoS, the periodic location interval and the total number of reports.

4) The MSC/SGSN sends a location request to the RAN containing the QoS and periodic location information received in step 3.

5) RAN determines the positioning method and instigates the particular message sequence for this method, as specified in UTRAN Stage 2, TS 25.305 [1] and GERAN Stage 2, TS 43.059 [16].

6) When a location estimate best satisfying the requested QoS has been obtained, RAN returns it to the MSC/SGSN.

7) The MSC/SGSN sends an LCS Location Update invoke to the UE containing the first location estimate.

8) The UE acknowledges receipt of the first location estimate. If the UE wished to cancel the periodic location procedure at that point, an additional parameter (e.g. flag or cause value) is included in this message.

9-12) As steps 5-8 for the second location estimate and thereafter repeated at the periodic location interval until the total number of reports is attained.

13) After the final location estimate has been transferred in step 12, the MSC/SGSN returns an MO-LR return result to the UE to indicate completion of the periodic location request in step 3. As an implementation option, the final location estimate may be returned in the MO-LR return result in step 13 rather than in an LCS Location Update in step 11.

14) The MSC/SGSN instigates clearing of the CM, MM/GMM and radio connections.

NOTE: If the UE receives a response in step 13 indicating that the MO-LR request for periodic self location cannot be supported (for temporary or permanent reasons), the UE may periodically invoke the MO‑LR procedure for self location defined in clause 9.2.1 for the CS domain (CS-MO-LR) and in clause 9.2.2 for the PS domain (PS-MO-LR).

9.2.5 WLAN UE Originated Procedure in I-WLAN

This procedure is applicable to a UE connected to I-WLAN defined in TS 23.234 [52] and it is no longer maintained.

Figure 9.8c describes the MO-LR procedure for LCS for I-WLAN.

Figure 9.8c: WLAN UE Originated Procedure in I-WLAN

1. The WLAN UE selects a WLAN AN and establishes the WLAN connection and is authenticated in I-WLAN. The tunnel is established with between WLAN UE and one of PDGs in PLMN.

2. WLAN UE initiates positioning procedure by establishing a so called user plane connection with the GMLC/SLP and shall use the OMA SUPL mechanism specified by OMA (OMA AD SUPL [38], OMA TS ULP [39]) to transport location related assistance data and location information between the UE and GMLC/SLP. The UE may receive assistance data and determine its own location and send its location information to the GMLC/SLP or the UE sends measurement results to the GMLC/SLP. In case GMLC/SLP determines the location of the UE, the GMLC/SLP shall send the location information to the WLAN UE. The UE may also send the identifier of the access node (e.g., MAC address of the AP) to the GMLC and GMLC, possibly using an external database, maps this location identifier to the corresponding geographical information, e.g. coordinates or street address and returns the result to the UE.

3. The location information obtained is transferred to external LCS client if requested by WLAN UE. The estimated position of a WLAN UE can be stored in the GMLC after WLAN UE originated positioning procedure for future uses subject to the privacy settings of the WLAN UE. If there is an LCS request from an external LCS Client, the stored location information can be delivered to the external LCS client if the stored location information satisfies LCS QoS requested.

9.2.6 Mobile Originating Location Request, EPC (EPC-MO-LR)

The following procedure shown in figure 9.8d allows an UE to request either, its own location and optionally, velocity or location assistance data. Location assistance data may be used subsequently by the UE to compute its own location throughout an extended interval using a mobile based position method. The EPC MO LR may be used to request GNSS assistance data. The procedure may also be used to enable an UE to request that its own location be sent to an external LCS client.

Figure 9.8d: General Network Positioning for packet switched MO-LR

9.2.6.1 Location Preparation Procedure

1) If the UE is not using Control Plane CIoT EPS Optimisation and if the UE is in ECM-IDLE state, the UE performs a UE triggered service request as defined in TS 23.401 [41] in order to establish a signalling connection with the MME and assign a specific eNodeB.

If the UE is using Control Plane CIoT EPS Optimisation, procedures for Mobile Originated Data Transport in Control Plane CIoT EPS optimisation as defined in TS 23.401 [41] are performed by the UE to establish a signalling connection with the MME.

2) The UE sends a NAS PDU containing an MO-LR Request inside an RRC UL Information Transfer message to the eNodeB. The MO-LR Request may optionally include an LPP positioning message. The eNodeB forwards the MO-LR Request (including any embedded LPP message) to the MME inside an S1AP Uplink NAS Transport message. Different types of location services can be requested: location estimate of the UE, location estimate of the UE to be sent to an external LCS client or location assistance data. If the UE is requesting its own location or that its own location be sent to an external LCS client, this message carries LCS requested QoS information (e.g. accuracy, response time, LCS QoS Class), the requested maximum age of location and the requested type of location (e.g. "current location", "current or last known location"). If the UE is requesting that its location be sent to an external LCS client, the message shall include the identity of the LCS client and may include the address of the GMLC through which the LCS client should be accessed. In addition, a Service Identity indicates which MO-LR service of the LCS Client is requested by the UE may be included. The message also may include a pseudonym indicator to indicate a pseudonym should be assigned by the network and transferred to the LCS Client as the UE’s identity. If the UE is instead requesting location assistance data, the embedded LPP message specifies the type of assistance data and the positioning method for which the assistance data applies. For an LCS EPC-MO-LR requesting location transfer to an external LCS Client, the MME shall assign a GMLC address, i.e. V-GMLC address, which is stored in the MME. If a V-GMLC address is not available, the MME may reject the location request. The MME verifies the subscription profile of the UE and decides if the requested service is allowed or not.

3) The MME selects a E-SMLC as described in clause 6.3.13 and sends a Location Request message to the selected E-SMLC. The Location Request message conveys any embedded LPP message in the MO-LR Request. Once an MME has selected an E-SMLC it must continue to use that E-SMLC for the duration of the session. The Location Request message indicates whether a location estimate or location assistance data is requested. If the UE’s location is requested, the message also includes the requested QoS. If location assistance data is requested, the embedded LPP message will convey the requested types of location assistance data. The message carries also other location parameters received in the MO-LR Request message, the current cell identity obtained from S1-AP message that carries the NAS MO-LR Request, and the UE capability to support LPP. The message also indicates RAT type and/or coverage level if applicable.

9.2.6.2 Positioning Measurement Establishment Procedure

4) If the UE is requesting its own location, the actions described in clause 9.3a are performed. If the UE is instead requesting location assistance data, the E-SMLC transfers this data to the UE as described in clause 9.3a.1. The E-SMLC determines the exact location assistance data to transfer according to the type of data specified by the UE, the UE location capabilities and the current cell.

NB-IoT UEs may perform measurements for some positioning methods only when in ECM-IDLE state. An E-SMLC that is aware of this (e.g. from an indication sent by the UE) may allow additional response time to the UE (e.g. in the QoS) to obtain the measurements. An MME that is aware of this (e.g. from the UE access type) may also allow additional time for a location session to complete.

9.2.6.3 Location Calculation and Release Procedure

5) When a location estimate best satisfying the requested QoS has been obtained or when the requested location assistance data has been transferred to the UE, the E-SMLC returns a Location Response to the MME with an indication whether the obtained location estimate satisfies the requested accuracy or not. This message carries the location estimate if this was obtained. If a location estimate was not successfully obtained, or if the requested location assistance data could not be transferred successfully to the UE, a failure cause is included in the Location Response.

6) If the UE did not request transfer of its location to an external LCS Client in step 2, steps 6 to 13 are skipped. Otherwise, if the location estimate was successfully obtained, the MME shall send a Subscriber Location Report to the V-GMLC assigned in the step 2, carrying the MSISDN/IMSI of the UE, the event causing the location estimate (EPC-MO LR) and the location estimate, its age, obtained accuracy indication and the LCS QoS Class requested by the target UE. In addition, the Subscriber Location Report may include the pseudonym indicator, the identity of the LCS Client, the GMLC address and the Service Identity specified by the UE, if available.

7) This step is the same as step 7 for a PS-MO-LR in clause 9.2.2.3.

8) This step is the same as step 8 for a PS-MO-LR in clause 9.2.2.3.

9) This step is the same as step 9 for a PS-MO-LR in clause 9.2.2.3.

10) This step is the same as step 10 for a PS-MO-LR in clause 9.2.2.3.

11) This step is the same as step 11 for a PS-MO-LR in clause 9.2.2.3.

12) This step is the same as step 12 for a PS-MO-LR in clause 9.2.2.3.

13) If the V-GMLC receives the MO-LR Location Information Acknowledgement from the H-GMLC, the V-GMLC shall record charging information both for the UE and inter-working revenue charges and send the Subscriber Location Report Acknowledgement to the MME, carrying the information specifies whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not success, the corresponding error cause obtained in step 12.

If the V-GMLC receives the Subscriber Location Report from the MME and it is not required to send to any LCS Client, the V-GMLC shall record charging information for the UE and response the Subscriber Location Report Acknowledgement to the MME.

14) The MME returns a NAS MO-LR Response message to the UE carrying any location estimate requested by the UE including the indication received from E-SMLC whether the obtained location estimate satisfies the requested accuracy or not, or an indicator whether a location estimate was successfully transferred to the identified LCS client. If the location estimate was successfully transferred to the identified LCS Client, the MO-LR Response message shall specify whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not, the corresponding error cause obtained in step 13. The MME may record charging information.