Content for TR 23.720 Word version: 13.0.0
4 Architectural Considerations and Assumptions
5 Key Issues
6 Solutions
7 Overall Evaluation
8 Conclusions
$ Change History
4 Architectural Considerations and Assumptions p. 9
4.1 Architectural Reference Model for Cellular IoT p. 9
4.2 Architectural assumptions for Cellular IoT system p. 9
4.3 Traffic Models for Cellular IoT p. 10
5 Key Issues p. 10
5.1 Key Issue 1 - Architecture Reference Model for Cellular IoT p. 10
5.1.1 Description p. 10
5.1.2 Architectural Requirements p. 11
5.2 Key Issue 2 - Efficient support of infrequent small data transmission for Cellular IoT p. 11
5.2.1 Description p. 11
5.2.2 Architectural Requirements p. 11
5.3 Key Issue 3 - Efficient support of tracking devices using small data transmission for Cellular IoT p. 11
5.3.1 Description p. 11
5.3.2 Architectural Requirements p. 11
5.3.3 Traffic model for efficient support of tracking devices using small data transmission for Cellular IoT p. 12
5.4 Key Issue 4 - Support of efficient Paging area management for Cellular IoT p. 12
5.4.1 Description p. 12
5.4.2 Architectural Requirements p. 12
5.5 Key Issue 5: Selection of CIoT-EPC Dedicated Core Network p. 13
5.5.1 Description p. 13
5.5.2 Architectural Requirements p. 13
5.6 Key Issue 6 - Support of Non IP data p. 13
5.6.1 Description p. 13
5.7 Key Issue 7 - Support of SMS p. 13
5.7.1 Description p. 13
5.8 Key Issue 8 - Control of small data misuse p. 13
5.8.1 Description p. 13
5.9 Key Issue 9 - Optimised Support of SMS transmission p. 13
5.9.1 Description p. 13
5.10 Key Issue 10 - Authorization of use of Coverage Enhancement p. 14
5.10.1 Description p. 14
5.10.2 Architectural Requirements p. 14
5.11 Key Issue 11 - Header compression enhancements for CIOT p. 14
5.11.1 Description p. 14
5.11.2 Architectural Requirements p. 14
6 Solutions p. 14
6.1 Solution 1: Lightweight CN architecture for CIoT p. 14
6.1.1 Description p. 14
6.1.1.1 Introduction p. 14
6.1.1.2 Architecture basic principles p. 15
6.1.1.3 Functional Description of new entities p. 16
6.1.1.3.1 C-SGN p. 16
6.1.1.3.2 S1-lite p. 17
6.1.1.4 Protocol stack p. 17
6.1.2 Impacts on existing nodes and functionality p. 18
6.1.3 Solution Evaluation p. 18
6.2 Solution 2: Infrequent small data transmission using pre-established NAS security p. 18
6.2.1 Description p. 18
6.2.1.1 General p. 18
6.2.1.2 CIoT Attach Procedure p. 19
6.2.1.3 Procedure for MO Small Data Transfer (and response) p. 21
6.2.1.4 Procedure for MT Small Data Transfer p. 22
6.2.2 Impacts on existing nodes and functionality p. 23
6.2.3 Solution Evaluation p. 24
6.3 Solution 3: Connectionless small data transmission with immediate return to idle p. 24
6.3.1 Description p. 24
6.3.2 Impacts on existing nodes and functionality p. 28
6.3.3 Solution Evaluation p. 28
6.4 Solution 4: Non-IP small data transmission via MTC-IWF p. 28
6.4.1 Description p. 28
6.4.1.1 General p. 28
6.4.1.2 Procedure p. 29
6.4.2 Impacts on existing nodes and functionality p. 31
6.4.3 Solution Evaluation p. 31
6.4a Solution 4a: non-IP small data transmission via SCEF p. 32
6.4a.1 Description p. 32
6.4a.1.1 General p. 32
6.4a.1.2 Procedures p. 32
6.4a.2 Impacts on existing nodes and functionality p. 32
6.4a.3 Solution Evaluation p. 33
6.4b Solution 4b: Non-IP small data transmission via SCEF with minimized load to HSS p. 33
6.4b.1 Description p. 33
6.4b.1.1 General p. 33
6.4b.1.2 Procedures p. 33
6.4b.2 Impacts on existing nodes and functionality p. 35
6.4b.3 Solution Evaluation p. 35
6.5 Solution 5: UE state transition signalling reduction p. 36
6.5.1 Description p. 36
6.5.1.1 General p. 36
6.5.1.2 RRC Suspend p. 36
6.5.1.3 RRC Resume p. 38
6.5.1.4 States description and transitions handling p. 40
6.5.1.5 Further aspects p. 41
6.5.2 Impacts on existing nodes and functionality p. 41
6.5.3 Solution Evaluation p. 42
6.6 Solution 6: User plane based solution with enhanced ECM-CONNECTED state p. 42
6.6.1 Description p. 42
6.6.1.1 Underlying assessment p. 42
6.6.1.2 Proposed architecture p. 43
6.6.1.3 Proposed High level Solution attributes p. 43
6.6.1.4 Expected RAN dependencies / impacts p. 44
6.6.1.5 Procedures p. 44
6.6.1.5.1 General p. 44
6.6.1.5.2 Attach p. 45
6.6.1.5.3 ECM-IDLE to enhanced ECM-CONNECTED TRANSITION (eNB-m without valid retained context) p. 46
6.6.1.5.4 ECM-IDLE to enhanced ECM-CONNECTED TRANSITION (eNB-m with retained context) p. 47
6.6.1.5.5 RRC connection re-establishment in enhanced ECM-CONNECTED state in an eNB-m without valid UE context p. 48
6.6.1.5.6 RRC connection re-establishment in enhanced ECM-CONNECTED state in an eNB-m with valid UE context p. 49
6.6.1.5.7 Network initiated Temporary UE ID reallocation and Key refresh p. 50
6.6.2 Impacts on existing nodes and functionality p. 50
6.6.3 Solution Evaluation p. 50
6.7 Solution 7: Paging for static and dynamic coverage enhancement (CE) level p. 51
6.7.1 Description p. 51
6.7.1.1 General p. 51
6.7.1.2 Design for Static Paging CE level (for scenario 1) p. 51
6.7.1.3 Design for Dynamic CE level (for scenario 2) p. 52
6.7.2 Impacts on existing nodes and functionality p. 53
6.7.3 Solution Evaluation p. 53
6.8 Solution 8: Cell based paging area update for efficient paging area management p. 53
6.8.1 Description p. 53
6.8.2 Impacts on existing nodes and functionality p. 54
6.8.3 Solution Evaluation p. 55
6.9 Solution 9: UE provided indication for selection of CIoT-EPC DCN or EPC DCN p. 55
6.9.1 Description p. 55
6.10 Solution 10: Support for "non IP" PDN types p. 56
6.10.1 Description p. 56
6.10.2 Impacts on existing nodes and functionality p. 58
6.10.3 Solution Evaluation p. 58
6.11 Solution 11: SMS over PS without combined attach and default PDN connection p. 58
6.11.1 Description p. 58
6.11.2 Impacts on existing nodes and functionality p. 59
6.11.3 Solution Evaluation p. 59
6.12 Solution 12: Solution on simplification of MM and SM procedures p. 59
6.12.1 Description p. 59
6.12.1.1 Simplification of MM and SM messages p. 59
6.12.1.2 Simplification of IEs in MM and SM messages p. 63
6.12.2 Impacts on existing nodes and functionality p. 63
6.12.3 Solution Evaluation p. 63
6.13 Solution 13: RRC FastConnect for Service Request p. 63
6.13.0 Description p. 63
6.13.1 Procedures p. 64
6.13.1.1 Storing UE's AS Context in MME when UE goes idle p. 64
6.13.1.2 Service Request Procedure p. 64
6.13.2 Impacts on existing nodes and functionality p. 66
6.14 Solution 14: Setup of CIoT PDN connection with minimum NAS p. 66
6.14.1 Description p. 66
6.14.1.1 General p. 66
6.14.1.2 CIoT PDN connection/PDP Context setup p. 66
6.14.1.3 CIoT PDN connection/PDP Context setup for "EMM context only case" p. 68
6.14.1.4 Affected ESM & GSM messages p. 68
6.14.2 Impacts on existing nodes p. 69
6.14.3 Solution Evaluation p. 69
6.15 Solution 15: Support for "non IP" small data by UDP/IP encapsulation over SGi p. 69
6.15.1 Description p. 69
6.15.1.1 General p. 69
6.15.1.2 Non IP PDN connection setup p. 70
6.15.2 Impacts on existing nodes p. 71
6.15.3 Solution Evaluation p. 71
6.16 Solution 16: Optimised SMS over PS without combined attach and default PDN connection p. 71
6.16.1 Description p. 71
6.16.1.1 General p. 71
6.16.1.2 Attach with MO SMS PDU p. 72
6.16.1.3 Attach with MT SMS PDU p. 73
6.16.1.4 Attach with MT SMS PDU - more messages to send p. 74
6.16.1.5 Attach with MO/MT SMS PDU p. 75
6.16.2 Impacts on existing nodes and functionality p. 75
6.16.3 Solution Evaluation p. 75
6.17 Solution 17: Optimized SMS relay for CIoT p. 76
6.17.1 Description p. 76
6.17.1.1 Background p. 76
6.17.1.2 Optimized SMS relay p. 77
6.17.2 Impacts on existing nodes p. 79
6.17.3 Solution Evaluation p. 79
6.18 Solution 18: User plane based solution with AS information stored in RAN p. 79
6.18.1 Description p. 79
6.18.1.1 General p. 79
6.18.1.2 Initial connection and AS context setup p. 80
6.18.1.3 RRC Suspend procedure p. 81
6.18.1.4 RRC Resume procedure p. 82
6.18.1.5 Resumption when AS information is not available in the eNB p. 85
6.18.1.6 MM procedure using user plane based solution p. 86
6.18.1.7 Further aspects p. 86
6.18.2 Impacts on existing nodes and functionality p. 87
6.18.3 Solution Evaluation p. 87
6.19 Solution 19: Header compression at C-SGN p. 87
7 Overall Evaluation p. 92
8 Conclusions p. 92
$ Change History p. 94
