Content for TS 23.272 Word version: 19.0.0
1…
4…
5…
5.4…
6…
6.3
6.4…
7…
7.3
7.4…
7.5a…
8…
8.2.4a…
8.3…
8.4…
B…
B.2…
B.2.2…
B.2.3a…
B.2.3a.4…
B.2.4…
B.3…
C…
C.8…
8.3 Location Services (LCS)
8.3.1 MO-LR procedure
8.3.2 MT-LR procedure
8.3.3 NI-LR procedure
8.3.4 Returning back to E-UTRAN
8.3.5 Co-Existence with Other Location Services
...
...
8.3 Location Services (LCS) p. 62
8.3.1 MO-LR procedure p. 62
8.3.1.1 General |R10| p. 62
MO-LR procedure in the CS fallback in EPS is performed as specified in TS 23.271.
When the MO-LR procedure is triggered by the UE's application, UE will check the LCS Support Indication provided by the Attach and TAU procedures as specified in TS 23.401:
- If the LCS Support Indication indicates EPC-MO-LR is supported, and if the UE supports EPC-MO-LR, the UE stays in LTE and initiates the EPC-MO-LR procedure.
- If EPC-MO-LR is not supported by either the network or the UE and if the LCS Support Indication indicates CS-MO-LR is supported, and the UE supports CS-MO-LR, the UE assumes CS-MO-LR is provided. Also, if EPC-MO-LR is not supported by either the network or the UE and if network does not provide information on whether CS-MO-LR is supported, then UE assumes CS-MO-LR may be provided. In these cases, if the previous combined EPS/IMSI Attach or Combined TA/LA Update is accepted with no "SMS only" indication, then the UE initiates CS Fallback to perform CS-MO-LR.
- Otherwise, the UE shall not attempt the EPC-MO-LR procedure, i.e. neither EPC-MO-LR nor CS-MO-LR with CS Fallback.
- When the UE is in active mode without an IMS VoIP session, the UE and the network follow the procedure in clause 6.2 "Mobile Originating Call in Active Mode - PS HO supported" or clause 6.3 "Mobile Originating call in Active Mode - No PS HO supported". After the UE changes its RAT from E-UTRAN to UTRAN/GERAN, it performs CS-MO-LR procedures as specified in TS 23.271.
- When the UE is in active mode with an IMS VoIP session and if the UE supports SRVCC procedures, the UE and the network follow the procedure in clause 8.3.1.2 "MO-LR in Active Mode with IMS VoIP session - PS HO supported".
- When the UE is in active mode without an IMS VoIP session but the network decides not to perform PS-Handover, then the UE and the network follow the procedure in clause 6.3 "Mobile Originating Call in Active Mode - No PS HO Support". After the UE changes its RAT from E-UTRAN to UTRAN/GERAN, it performs CS-MO-LR procedure as specified in TS 23.271.
- When the UE is in active mode with an IMS VoIP session and if the UE supports SRVCC procedures but the network decides not to perform PS-Handover, then the UE and the network follow the procedure in clause 8.3.1.3 "MO-LR in Active Mode with IMS VoIP session - No PS HO supported".
- When UE is in idle mode, UE follows the procedure in clause 6.4 "Mobile Originating Call in Idle Mode". After UE changes its RAT from E-UTRAN to UTRAN/GERAN, it performs CS-MO-LR procedure as specified in TS 23.271.
8.3.1.2 MO-LR in Active Mode with IMS VoIP session - PS HO supported |R10| p. 63
Figure 8.3.1.2-1: MO-LR Request in E-UTRAN while UE is in IMS VoIP session
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
Step 1a.-2.
When SRVCC capable UE is in active mode with an IMS VoIP session but the network does not support SRVCC, MME sends a Service Reject in response to step 1a based on EPS bearer information, i.e. MME rejects the request if UE has EPS bearer with QCI=1, i.e. IMS VoIP session.
These steps are performed as defined in clause 6.2.
Step 3.
Based on UE measurement reports and CS Fallback Indicator in step 1b, the source E-UTRAN decides to trigger an SRVCC handover to UTRAN/GERAN. Continuous SRVCC procedures are continued as specified in clause 6.2.2.2 of TS 23.216.
Step 4.
After sending a Handover Complete message via the RNS/BSS to the MSC in step 3, the UE sends a CM Service Request to the MSC indicating a request for location services. After the HLR is updated and the subscriber data are downloaded from the HLR, the MSC sends a CM Service Accept to the UE. Then the UE sends a NAS MO-LR Request to the MSC.
Step 5.
Continuation of MO-LR procedures as specified in clause 9.2.6 of TS 23.271.
8.3.1.3 MO-LR in Active Mode with IMS VoIP session - No PS HO supported |R10| p. 64
The same procedure as described in clause 8.3.1.2 applies for "MO-LR in Active Mode with IMS VoIP session - No PS HO supported" case except that the SRVCC procedure in step 3 follows clause 6.2.2.1A of TS 23.216.
8.3.2 MT-LR procedure p. 64
8.3.2.1 MT-LR procedure if UE is not in IMS VoIP session |R10| p. 64
Step 1.
MSC receives a PROVIDE_SUBSCRIBER_LOCATION message due to CS-MT-LR (clause 9.1.2 of TS 23.271).
Step 2.
MSC sends Paging (LCS Client Identity, LCS indicator) message to MME.
Step 3.
If the MME did not return the "SMS-only" indication to the UE during Attach or Combined TA/LA Update procedures, the MME sends Paging (parameters as specified in TS 23.401, CN Domain Indicator, LCS Client Identity, LCS indicator) message to UE. LCS indicator is used to inform the UE that this paging if for MT-LR request. LCS Client Identity and LCS indicator are only included in CS Page if UE is in active mode.
If the MME returned the "SMS-only" indication to the UE during Attach or Combined TA/LA Update procedures, the MME shall not send Paging to the UE, and the MME sends CS Paging Reject towards MSC to stop CS Paging procedure and this CSFB procedure stops.
Step 4.
UE responds with Paging_Resp message in UMTS/GERAN. Service based redirection/reselection or PS Handover may take place as specified in clause 7.
Step 5.
MSC continues with the CS-MT-LR procedure as defined in clause 9.1.2 of TS 23.271.
8.3.2.2 MT-LR procedure while UE is in IMS VoIP session |R10| p. 65
Step 1.
When SRVCC capable UE is in active mode with an IMS VoIP session but the network does not support SRVCC, MME sends Paging Reject towards MSC and this CSFB procedure stops. This is based on the bearer information at MME indicating UE has IMS VoIP session, i.e. EPS bearer with QCI=1.Corresponding error handling is returned to the GMLC as specified in TS 23.271.
MSC receives a PROVIDE_SUBSCRIBER_LOCATION message due to CS MT LR (clause 9.1.2 of TS 23.271).
Step 1a.
The MSC responds by sending a Paging Request (LCS Client Identity, LCS indicator) to the MME over a SGs interface. The MSC only sends a CS Page for an UE that provides location update information using the SGs interface. The MME has an established S1 connection for IMS VoIP session.
If the MME did not return the "SMS-only" indication to the UE during Attach or Combined TA/LA Update procedures, the MME sends Paging (parameters as specified in TS 23.401, CN Domain Indicator, LCS Client Identity, LCS indicator) message to UE. LCS indicator is used to inform the UE that this paging is for MT-LR request.
If the MME returned the "SMS-only" indication to the UE during Attach or Combined TA/LA Update procedures, the MME shall not send Paging to the UE, and the MME sends CS Paging Reject towards MSC to stop CS Paging procedure and this CSFB procedure stops.
The eNodeB forwards the paging message to the UE.
Step 1b.
UE sends an Extended Service Request (Reject or Accept) message to the MME for mobile terminating CS Fallback. The Extended Service Request message is encapsulated in RRC and S1-AP messages. The UE may decide to reject CSFB based on LCS Client Identity.
Step 1c.
Upon receiving the Extended Service Request (Reject) for mobile terminating CS Fallback, the MME sends Paging Reject towards MSC to stop CS Paging procedure and this CSFB procedure stops. Corresponding error handling is returned to the GMLC as specified in TS 23.271.
Step 1d.
MME sends an S1-AP Request message to eNodeB that includes the UE Radio Capabilities and a CS Fallback Indicator. This message: indicates to the eNodeB that the UE should be moved to UTRAN/GERAN.
Step 1e.
The eNodeB shall reply with S1-AP Response message.
Step 2.
These steps are performed as defined in clause 7.3 for PS handover supported case and clause 7.4 for No PS handover supported case.
Step 3.
Based on UE measurement reports and CS Fallback Indicator in step 1d, the source E-UTRAN decides to trigger an SRVCC handover to UTRAN/GERAN. Continuous SRVCC procedures as specified in clause 6.2.2.2 of TS 23.216 for PS handover supported case and clause 6.2.2.1A for No PS HO supported case are performed.
Step 4.
After receiving Relocation/Handover Complete message from the RNS/BSS in step 3, MSC sends LCS Location Notification Invoke to the UE.
Step 5.
Continuation of CS-MT-LR procedures as specified in clause 9.1.2 of TS 23.271.
8.3.3 NI-LR procedure p. 66
NI-LR procedure takes place during emergency calls, and is thus performed in GERAN/UTRAN during the Mobile Originating call procedure.
8.3.4 Returning back to E-UTRAN p. 66
Once CS service ends in CS domain, existing mechanisms as specified in TS 23.401 can be used to move the UE to E-UTRAN, no specific CS Fallback mechanisms are needed.
During the release of an RR connection the MSC should indicate to GERAN/UTRAN that the RR connection (for call or CISS or LCS) was established as a result of CS fallback. GERAN and UTRAN may use the indication to determine which of the existing mechanisms that should be used to move the UE to E-UTRAN.
When configured to support the return to the last used PLMN after CSFB, after a successful setup of an RR connection or during the release of the UTRAN RR connection, the MSC shall further indicate to GERAN/UTRAN the last used LTE PLMN ID. GERAN and UTRAN shall take the last used LTE PLMN ID into account when selecting the target cell in PS handover to E-UTRAN or when selecting the dedicated target frequency list for idle mode mobility to E-UTRAN in RR Connection Release procedure.
8.3.5 Co-Existence with Other Location Services p. 66
8.3.5.1 Co-Existence with SUPL p. 66
There is no race condition between OMA AD SUPL [9] and CS Fallback for LCS. When network initiated SUPL procedure takes place, the paging message does not contain CN Domain Indicator by default. This prevents CS Fallback for LCS to take place. For SET initiated SUPL procedure, changing of RAT does not take place.
