Content for TR 23.732 Word version: 16.0.0
5 Key Issues p. 9
5.1 Key Issue 1: Interaction between UDM and HSS with separate repositories p. 9
5.1.1 Description p. 9
5.2 Key Issue 2: Supporting a common repository for both HSS and UDM p. 10
5.2.1 Description p. 10
6 Solutions p. 10
6.1 Solution #1: Retrieving subscription data from separate UDR repositories for EPS and 5GS subscription data using a UDR Translation Function (UTF) p. 10
6.1.1 Introduction p. 10
6.1.2 High-level Description p. 10
6.1.3 Services and Illustrated Procedures p. 11
6.1.3.1 General p. 11
6.1.3.2 5GS to EPS Interworking when N26 is not supported p. 13
6.1.3.3 Terminating Access Domain Selection (T-ADS) p. 16
6.1.3.3.1 Alternative 1 p. 16
6.1.3.3.2 Alternative 2 p. 18
6.1.3.4 P-CSCF restoration p. 18
6.1.4 Impacts on existing services and interfaces p. 18
6.1.5 Evaluation p. 19
6.2 Solution #2: Direct SBA UDM-HSS Interworking p. 19
6.2.1 Introduction p. 19
6.2.2 High-level Description p. 19
6.2.3 Services and Illustrated Procedures p. 21
6.2.3.1 General p. 21
6.2.3.2 Subscriber Profile Indications p. 22
6.2.3.3 Authentication p. 22
6.2.3.3.1 Single AV Generation Engine in HSS(AuC) and Credentials stored in EPC-UDR p. 22
6.2.3.3.2 Single AV Generation Engine in UDM and Credentials stored in UDR p. 23
6.2.3.4 Mobility Scenarios p. 24
6.2.3.4.1 Mobility from 5GC to EPC, single registration, with N26 Interface p. 24
6.2.3.4.2 Mobility from EPC to 5GC, single registration, with N26 Interface p. 25
6.2.3.4.3 Interworking without N26 Interface p. 26
6.2.3.5 T-ADS p. 27
6.2.3.6 P-CSCF Restoration p. 27
6.2.3.7 SMS support p. 28
6.2.4 Impacts on existing services and interfaces p. 31
6.2.5 Evaluation p. 32
6.3 Solution #3: UDM/HSS FE interaction reusing legacy protocol p. 32
6.3.1 Introduction p. 32
6.3.2 High-level Description p. 32
6.3.2.1 Authentication p. 32
6.3.2.2 IP address continuity of interworking without N26 from 5GS to EPS p. 33
6.3.2.3 T-ADS for IMS voice p. 34
6.3.2.4 Supporting IMS related procedures p. 35
6.3.2.5 SMS over NAS p. 36
6.3.3 Services and Illustrated Procedures p. 37
6.3.3.1 Authentication p. 37
6.3.3.2 IP address continuity of interworking without N26 from 5GS to EPS p. 39
6.3.3.3 T-ADS for IMS voice p. 40
6.3.3.4 Supporting IMS related procedures p. 41
6.3.3.5 SMSF address storage and retrieval p. 42
6.3.4 Impacts on existing services and interfaces p. 43
6.3.4.1 Authentication impacts p. 43
6.3.4.2 IP address continuity impacts p. 43
6.3.4.3 T-ADS for voice impacts p. 43
6.3.4.4 Supporting IMS related procedures p. 43
6.3.5 Evaluation p. 44
6.4 Solution #4: Use of a Data Access Layer for interaction between HSS FE and UDM with common repository p. 44
6.4.1 Introduction p. 44
6.4.2 High-level Description p. 44
6.4.2.1 Assumptions p. 44
6.4.2.2 Architectural proposal p. 45
6.4.3 Services and Illustrated Procedures p. 46
6.4.3.1 General description p. 46
6.4.3.2 5GS procedures p. 46
6.4.3.3 EPS procedures p. 47
6.4.3.4 Handover procedures p. 47
6.4.3.4.0 General p. 47
6.4.3.4.1 5GS to EPS with N26 p. 49
6.4.3.4.2 EPS to 5GS with N26 p. 49
6.4.3.4.3 5GS to EPS without N26 - single registration p. 50
6.4.3.4.4 EPS to 5GS without N26 - single registration p. 50
6.4.3.4.5 Handovers without N26 - dual registration p. 50
6.4.3.5 IMS interaction p. 50
6.4.4 Impacts on existing services and interfaces p. 53
6.4.4.1 General p. 53
6.4.4.2 Summary of impacts on UDM p. 54
6.4.4.3 Summary of impacts on HSS FE p. 54
6.4.4.4 Summary of impacts on EPS UDR p. 54
6.4.5 Evaluation p. 54
6.5 Solution #5: Use of a Data Access Layer for interaction between HSS FE and UDM with separate repositories p. 55
6.5.1 Introduction p. 55
6.5.2 High-level Description p. 55
6.5.2.1 Assumptions p. 55
6.5.2.2 Architectural proposal p. 56
6.5.3 Services and Illustrated Procedures p. 57
6.5.3.1 General description p. 57
6.5.3.2 5GS procedures p. 58
6.5.3.3 EPS procedures p. 58
6.5.3.4 Handover procedures p. 58
6.5.3.4.0 General p. 58
6.5.3.4.1 5GS to EPS with N26 p. 60
6.5.3.4.2 EPS to 5GS with N26 p. 61
6.5.3.4.3 5GS to EPS without N26 - single registration p. 61
6.5.3.4.4 EPS to 5GS without N26 - single registration p. 61
6.5.3.4.5 Handovers without N26 - dual registration p. 62
6.5.3.5 IMS interaction p. 62
6.5.4 Impacts on existing services and interfaces p. 64
6.5.4.1 General p. 64
6.5.4.2 Summary of impacts on UDM p. 65
6.5.4.3 Summary of impacts on HSS FE p. 65
6.5.4.4 Summary of impacts on EPS UDR or 5G repository p. 65
6.5.5 Evaluation p. 65
6.6 Solution #6: Deployment and coexistence without interworking between UDM and existing HSS p. 66
7 Evaluation p. 70
7.1 Evaluation of solutions p. 70
7.1.1 Evaluation of solutions with separation of FEs and repositories p. 71
7.1.2 Evaluation of solutions with separation of FEs with common repository p. 72
7.1.3 Evaluation of solutions with common FEs with separate repositories p. 72
7.1.4 Evaluation of solutions with common FEs with common repository p. 73
8 Conclusions p. 73
8.1 For EPS and 5GS interworking required for mobility cases from EPS to 5GS and from 5GS to EPS, including the impacts on SMS handling p. 73
8.2 For IMS and 5GS interworking required for T-ADS, P-CSCF restoration and NPLI retrieval p. 73
$ Change History p. 75
