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
$ Change history
5 Architecture model and reference points p. 10
5.1 General p. 10
5.2 Reference architecture p. 11
5.2.1 3GPP UTRAN/GERAN and E-UTRAN SRVCC architecture p. 11
5.2.2 3GPP UTRAN/GERAN and UTRAN (HSPA) SRVCC architecture p. 11
5.3 Functional Entities p. 12
5.4 Reference points p. 12
6 Solutions p. 12
6.1 Solution 1: Session transfer initiated on E-UTRAN/HSPA p. 12
6.1.1 Functional Description p. 12
6.1.2 Information flows p. 13
6.1.2.1 GERAN/UTRAN Attach procedure p. 13
6.1.2.2 E-UTRAN attach procedure p. 13
6.1.2.3 Call establishment procedure in GERAN/UTRAN p. 13
6.1.2.4 SRVCC from E-UTRAN/HSPA to GERAN/UTRAN p. 14
6.1.2.5 Handover procedure in GERAN/UTRAN p. 14
6.1.2.6 Call flows for SRVCC from UTRAN/GERAN to E-UTRAN p. 14
6.1.2.6.1 SRVCC handover from GERAN without DTM support to E-UTRAN p. 14
6.1.2.6.2 SRVCC handover from UTRAN or GERAN with PS handover support to E-UTRAN p. 16
6.1.2.7 Call flows for SRVCC from UTRAN/GERAN to HSPA p. 18
6.2 Solution 2: Session transfer initiated on E-UTRAN/HSPA p. 20
6.2.0 General p. 20
6.2.1 Functional Description p. 21
6.2.2 Information flows p. 21
6.2.2.1 GERAN/UTRAN Attach procedure p. 21
6.2.2.2 E-UTRAN attach procedure p. 21
6.2.2.3 Call establishment procedure in GERAN/UTRAN p. 21
6.2.2.4 SRVCC from E-UTRAN/HSPA to GERAN/UTRAN p. 22
6.2.2.5 Handover procedure in GERAN/UTRAN p. 22
6.2.2.6 Call flows for SRVCC from UTRAN/GERAN to E-UTRAN p. 23
6.3 Solution 3+5: Media anchoring in serving network with Access Transfer Control Functionality p. 25
6.3.1 Architecture Reference Model p. 25
6.3.2 Functional Entities p. 26
6.3.2.1 ATCF p. 26
6.3.2.2 SCC AS p. 27
6.3.2.3 P-CSCF p. 27
6.3.2.4 MSC Server enhanced for reverse SRVCC p. 27
6.3.2.5 SGSN enhanced for rSRVCC p. 27
6.3.2.6 UE enhanced for rSRVCC p. 27
6.3.2.7 HSS p. 28
6.3.2.8 MME/SGSN enhanced for rSRVCC p. 28
6.3.3 Message Flows p. 28
6.3.3.1 General principles p. 28
6.3.3.2 GERAN/UTRAN Attach procedure p. 29
6.3.3.3 E-UTRAN attach procedure p. 29
6.3.3.3a Informing the source RAN about the possibility to perform rSRVCC p. 29
6.3.3.4 Codec and transport address related procedure p. 30
6.3.3.5 Establish a session over CS p. 30
6.3.3.5.1 STN-SR allocated by the ATCF and Transfer Info sent to ATCF p. 30
6.3.3.5.2 Registration when ATCF involved p. 31
6.3.3.5.3 Origination procedures when ATCF involved p. 31
6.3.3.5.4 Termination procedures when ATCF involved p. 32
6.3.3.6 CS - PS Access Transfer Overview p. 33
6.3.3.7 Access Transfer Preparation p. 34
6.3.3.7.1 Access Transfer Preparation Alternative 1 p. 34
6.3.3.7.2 Access Transfer Preparation Alternative 2 p. 36
6.3.3.7.3 Access Transfer Preparation Alternative 3 p. 38
6.3.3.7.4 Access Transfer Preparation Alternative 4 p. 40
6.3.3.7.5 Access Transfer Preparation Alternative 5 (the combination) p. 43
6.3.3.8 IMS Session Continuity procedure p. 45
6.3.3.9 Identification of serving PS node p. 48
6.3.4 IMS registration Considerations p. 50
6.4 Solution 4: Session transfer by local anchoring with Indirect Forwarding p. 53
6.4.1 Functional Description p. 53
6.4.2 Architecture Reference Model p. 54
6.4.3 Information flows p. 54
6.5 Solution 5: IMS procedure is initiated by MSC Server to ATCF p. 59
6.5.1 Architecture Reference Model p. 59
6.5.1.1 General p. 59
6.5.1.2 Concepts of reverse SRVCC p. 60
6.5.2 Functional Entities p. 61
6.5.2.1 ATCF p. 61
6.5.2.2 SCC AS p. 61
6.5.2.3 S-CSCF p. 62
6.5.2.4 MSC Server enhanced for reverse SRVCC p. 62
6.5.2.5 MME p. 62
6.5.2.6 UE enhanced for reverse SRVCC p. 62
6.5.2.7 UTRAN/GERAN p. 62
6.5.3 Message Flows p. 63
6.5.3.1 Home control rSRVCC p. 63
6.5.3.2 RAU/LAU/TAU procedure p. 63
6.5.3.3 GERAN/UTRAN performs handover procedure p. 63
6.5.3.4 Maintaining IMS Registration p. 63
6.5.3.5 Preparation of media transfer p. 63
6.5.3.6 Selection of the ATCF p. 64
6.5.3.7 Originating sessions in CS p. 65
6.5.3.7.1 Serving MSC Server is not enhanced for ICS p. 65
6.5.3.7.2 Serving MSC Server is enhanced for ICS p. 66
6.5.3.7.3 Serving MSC Server is enhanced for rSRVCC p. 66
6.5.3.7.4 UE is enhanced for ICS p. 67
6.5.3.8 Terminating sessions in CS p. 68
6.5.3.9 CS - PS Access Transfer p. 70
6.5.3.9.0 Introduction p. 70
6.5.3.9.1 IMS Session Continuity procedure p. 70
6.5.3.9.2 CS to PS handover procedure p. 71
6.5.3.10 Failure to complete CS-PS Access Transfer p. 72
7 Assessment of the solutions p. 73
7.1 Assessment Criteria p. 73
7.2 Assessment of the solution 3+5 access transfer preparation alternatives p. 74
8 Conclusion p. 77
8.1 General p. 77
8.2 Access Transfer preparation / How to reserve bearer for VoIP p. 77
8.3 Source SGSN selection by MSC Server p. 77
8.4 Maintaining IMS registration over PS access during the CS session p. 77
8.5 Summary p. 77
A Mechanisms to re-enable E-UTRAN capability p. 78
A.1 Functional description p. 78
A.2 Information flows p. 79
A.2.1 Proposed signalling flow for Alternative A to re-enable E-UTRAN capabilities using broadcast indicator p. 79
A.2.2 Proposed signalling flow for Alternative B to re-enable E-UTRAN capabilities using NAS indicator 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 p. 81
B Mechanisms for GERAN/UTRAN sending Handover/Relocation Required message p. 82
$ Change history p. 83
