Content for TR 23.885 Word version: 11.0.0
5 Architecture model and reference points
6 Solutions
7 Assessment of the solutions
8 Conclusion
A Mechanisms to re-enable E-UTRAN capability
B Mechanisms for GERAN/UTRAN sending Handover/Relocation Required message
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5 Architecture model and reference points
5.1 General
5.2 Reference architecture Word‑p. 11
5.2.1 3GPP UTRAN/GERAN and E-UTRAN SRVCC architecture
5.2.2 3GPP UTRAN/GERAN and UTRAN (HSPA) SRVCC architecture
5.3 Functional Entities Word‑p. 12
5.4 Reference points
6 Solutions
6.1 Solution 1: Session transfer initiated on E-UTRAN/HSPA
6.1.1 Functional Description
6.1.2 Information flows Word‑p. 13
6.1.2.1 GERAN/UTRAN Attach procedure
6.1.2.2 E-UTRAN attach procedure
6.1.2.3 Call establishment procedure in GERAN/UTRAN
6.1.2.4 SRVCC from E-UTRAN/HSPA to GERAN/UTRAN Word‑p. 14
6.1.2.5 Handover procedure in GERAN/UTRAN
6.1.2.6 Call flows for SRVCC from UTRAN/GERAN to E-UTRAN
6.1.2.6.1 SRVCC handover from GERAN without DTM support to E-UTRAN
6.1.2.6.2 SRVCC handover from UTRAN or GERAN with PS handover support to E-UTRAN Word‑p. 16
6.1.2.7 Call flows for SRVCC from UTRAN/GERAN to HSPA Word‑p. 18
6.2 Solution 2: Session transfer initiated on E-UTRAN/HSPA Word‑p. 20
6.2.0 General
6.2.1 Functional Description Word‑p. 21
6.2.2 Information flows
6.3 Solution 3+5: Media anchoring in serving network with Access Transfer Control Functionality Word‑p. 25
6.3.1 Architecture Reference Model
6.3.2 Functional Entities Word‑p. 26
6.3.2.1 ATCF
6.3.2.2 SCC AS Word‑p. 27
6.3.2.3 P-CSCF
6.3.2.4 MSC Server enhanced for reverse SRVCC
6.3.2.5 SGSN enhanced for rSRVCC
6.3.2.6 UE enhanced for rSRVCC
6.3.2.7 HSS Word‑p. 28
6.3.2.8 MME/SGSN enhanced for rSRVCC
6.3.3 Message Flows
6.3.3.1 General principles
6.3.3.2 GERAN/UTRAN Attach procedure Word‑p. 29
6.3.3.3 E-UTRAN attach procedure
6.3.3.3a Informing the source RAN about the possibility to perform rSRVCC
6.3.3.4 Codec and transport address related procedure Word‑p. 30
6.3.3.5 Establish a session over CS
6.3.3.5.1 STN-SR allocated by the ATCF and Transfer Info sent to ATCF
6.3.3.5.2 Registration when ATCF involved Word‑p. 31
6.3.3.5.3 Origination procedures when ATCF involved
6.3.3.5.4 Termination procedures when ATCF involved Word‑p. 32
6.3.3.6 CS - PS Access Transfer Overview Word‑p. 33
6.3.3.7 Access Transfer Preparation
6.3.3.7.1 Access Transfer Preparation Alternative 1
6.3.3.7.2 Access Transfer Preparation Alternative 2 Word‑p. 36
6.3.3.7.3 Access Transfer Preparation Alternative 3 Word‑p. 38
6.3.3.7.4 Access Transfer Preparation Alternative 4 Word‑p. 40
6.3.3.7.5 Access Transfer Preparation Alternative 5 (the combination) Word‑p. 43
6.3.3.8 IMS Session Continuity procedure Word‑p. 45
6.3.3.9 Identification of serving PS node Word‑p. 48
6.3.4 IMS registration Considerations Word‑p. 50
6.4 Solution 4: Session transfer by local anchoring with Indirect Forwarding Word‑p. 53
6.5 Solution 5: IMS procedure is initiated by MSC Server to ATCF Word‑p. 59
6.5.1 Architecture Reference Model
6.5.1.1 General
6.5.1.2 Concepts of reverse SRVCC Word‑p. 60
6.5.2 Functional Entities Word‑p. 61
6.5.2.1 ATCF
6.5.2.2 SCC AS
6.5.2.3 S-CSCF Word‑p. 62
6.5.2.4 MSC Server enhanced for reverse SRVCC
6.5.2.5 MME
6.5.2.6 UE enhanced for reverse SRVCC
6.5.2.7 UTRAN/GERAN
6.5.3 Message Flows Word‑p. 63
6.5.3.1 Home control rSRVCC
6.5.3.2 RAU/LAU/TAU procedure
6.5.3.3 GERAN/UTRAN performs handover procedure
6.5.3.4 Maintaining IMS Registration
6.5.3.5 Preparation of media transfer
6.5.3.6 Selection of the ATCF Word‑p. 64
6.5.3.7 Originating sessions in CS Word‑p. 65
6.5.3.7.1 Serving MSC Server is not enhanced for ICS
6.5.3.7.2 Serving MSC Server is enhanced for ICS Word‑p. 66
6.5.3.7.3 Serving MSC Server is enhanced for rSRVCC
6.5.3.7.4 UE is enhanced for ICS Word‑p. 67
6.5.3.8 Terminating sessions in CS Word‑p. 68
6.5.3.9 CS - PS Access Transfer Word‑p. 70
6.5.3.9.0 Introduction
6.5.3.9.1 IMS Session Continuity procedure
6.5.3.9.2 CS to PS handover procedure Word‑p. 71
6.5.3.10 Failure to complete CS-PS Access Transfer Word‑p. 72
7 Assessment of the solutions Word‑p. 73
7.1 Assessment Criteria
7.2 Assessment of the solution 3+5 access transfer preparation alternatives Word‑p. 74
8 Conclusion Word‑p. 77
8.1 General
8.2 Access Transfer preparation / How to reserve bearer for VoIP
8.3 Source SGSN selection by MSC Server
8.4 Maintaining IMS registration over PS access during the CS session
8.5 Summary
A Mechanisms to re-enable E-UTRAN capability Word‑p. 78
A.1 Functional description
A.2 Information flows Word‑p. 79
A.2.1 Proposed signalling flow for Alternative A to re-enable E-UTRAN capabilities using broadcast indicator
A.2.2 Proposed signalling flow for Alternative B to re-enable E-UTRAN capabilities using NAS indicator Word‑p. 80
A.2.3 Proposed signalling flow for Alternative C to re-enable E-UTRAN capabilities using change in RFSP/RAC of the UE Word‑p. 81
B Mechanisms for GERAN/UTRAN sending Handover/Relocation Required message Word‑p. 82
$ Change history Word‑p. 83
