Content for TR 26.930 Word version: 18.0.0
6 Solutions
6.1 General
6.2 Solution #1: Enhancements on RTC architecture
6.3 Solution #2: Functional requirements for C-Plane
6.4 Solution #3: C-Plane signalling protocol
6.5 Solution #4: Functional requirements for U-Plane
6.6 Solution #5: Service control API
6.7 Solution #6: WSF Discovery mechanism
6.8 Solution #7: Interworking with IMS network
6.9 Solution #8: Protocol-level interworking between RTC network and IMS network
6.10 Solution #9: Tethered cases
6.11 Solution #10: Security considerations
6.12 Solution #11: Related groups considerations
7 Key findings
6 Solutions p. 32
6.1 General p. 32
6.2 Solution #1: Enhancements on RTC architecture p. 32
6.2.1 Solution description p. 32
6.2.2 Possible enhancements on functional entities and RTC architecture based on WebRTC viewpoint p. 33
6.2.2.1 Overview p. 33
6.2.2.2 Functional entities for WebRTC p. 33
6.2.2.2.1 General p. 33
6.2.2.2.2 Functional entities defined in WebRTC-related standardized specifications p. 34
6.2.2.2.3 Functional entities widely implemented for WebRTC p. 36
6.2.2.2.3.1 WMCF (WebRTC Media Centre Function) p. 36
6.2.2.2.3.2 CSF (Conference Supporting Function) p. 36
6.2.2.2.4 Functional entities needed for inter-operator services p. 37
6.2.2.3 Reference Points p. 37
6.2.3 Interaction between functional entities in the enhanced RTC architecture and 5GC p. 38
6.2.3.1 Overview p. 38
6.2.3.2 Mapping of functional entities for interaction with 5GC p. 38
6.2.3.2.1 General p. 38
6.2.3.2.2 WSF and AF p. 38
6.2.3.2.3 WNSGF p. 39
6.2.3.2.3.1 Overview p. 39
6.2.3.2.3.2 WNSGF and NEF p. 39
6.2.3.2.3.3 WNSGF and SEPP p. 39
6.2.3.2.3.4 New functional entity p. 39
6.2.3.3 Possible architecture integrated with 5GC p. 40
6.2.3.4 Mapping to RTC collaboration scenarios p. 41
6.2.4 Media connection model p. 41
6.2.4.1 General p. 41
6.2.4.2 Target use cases from network view p. 42
6.2.4.3 QoS-enabled end-to-end path p. 48
6.2.5 IP Addressing p. 48
6.2.5.1 Overview p. 48
6.2.5.2 NAT p. 49
6.2.5.2.1 Overview p. 49
6.2.5.2.2 NAT Variation p. 49
6.2.5.2.3 Existing NAT-traversal p. 50
6.2.5.2.4 Conclusion of NAT handling p. 52
6.2.5.3 IP Address and Trustable Subscriber Identifier p. 52
6.2.5.4 Conclusion of IP Addressing p. 53
6.2.6 Alignment and gap analysis between the enhanced RTC architecture and the current RTC architecture p. 53
6.2.6.1 General p. 53
6.2.6.2 WebRTC endpoint and RTC endpoint on UE p. 54
6.2.6.3 WSF and (RTC) WSF p. 54
6.2.6.4 WNSGF and Inter-working Function p. 54
6.2.6.5 CSF and Application Supporting Web Function p. 54
6.2.6.6 WMCF and Media Function p. 54
6.2.6.7 WNMGF and Transport Gateway Function p. 54
6.2.7 Enhanced RTC Architecture for collaboration scenario 4 p. 54
6.2.8 Proposed enhancements on RTC architecture p. 57
6.2.8.1 General p. 57
6.2.8.2 Derivative RTC architecture supporting collaboration scenario 3 and 4 p. 57
6.2.8.3 Enhancements on functionality in RTC AS functional entities p. 59
6.2.8.3.1 General p. 59
6.2.8.3.2 User Equipment p. 59
6.2.8.3.3 WebRTC Signalling Function p. 59
6.2.8.3.4 Media Function p. 60
6.2.8.3.5 Application Supporting Web Function p. 60
6.2.8.3.6 Inter-working Function p. 61
6.2.8.3.7 Transport Gateway Function p. 61
6.2.8.4 Enhancements on reference points p. 61
6.2.8.5 Enhancements on architecture diagrams in 3GPP TS 26.506 p. 62
6.2.9 Solution evaluation p. 64
6.3 Solution #2: Functional requirements for C-Plane p. 64
6.3.1 Solution description p. 64
6.3.2 Functional requirements for C-Plane interface p. 65
6.3.2.1 General p. 65
6.3.2.2 Support of WebRTC based RTC services p. 65
6.3.2.3 Transport of signalling message p. 65
6.3.2.4 Media session control and management p. 65
6.3.3 Protocol stack for C-Plane interface p. 66
6.3.3.1 General p. 66
6.3.3.2 Base protocol p. 66
6.3.3.3 Upper layer protocol over WebSocket p. 67
6.3.3.4 Proposed Protocol Stack p. 68
6.3.4 Solution evaluation p. 68
6.4 Solution #3: C-Plane signalling protocol p. 68
6.4.1 Solution description p. 68
6.4.2 Overview p. 69
6.4.2.1 General p. 69
6.4.2.2 Basic connection model p. 69
6.4.2.3 Target use case p. 70
6.4.2.4 Target architecture and reference points p. 70
6.4.2.5 Protocol stack p. 70
6.4.3 High-level features p. 70
6.4.3.1 General p. 70
6.4.3.2 List of high-level features p. 71
6.4.4 Transport of signalling massage p. 72
6.4.4.1 General p. 72
6.4.4.2 WebSocket connection establishment p. 73
6.4.4.3 WebSocket connection keep alive p. 73
6.4.4.4 WebSocket connection closure p. 73
6.4.4.5 Sending a RESPECT message over WebSocket p. 74
6.4.4.6 Error handling p. 74
6.4.4.6.1 General p. 74
6.4.4.6.2 Protocol version error p. 74
6.4.4.6.3 Network congestion error p. 74
6.4.4.6.4 Timeout error p. 74
6.4.5 RESPECT (signalling protocol) p. 74
6.4.5.1 General p. 74
6.4.5.2 Key features of the RESPECT protocol p. 74
6.4.5.2.1 General p. 74
6.4.5.2.2 Control session management p. 75
6.4.5.2.3 Media session management p. 76
6.4.5.2.4 Transaction management p. 77
6.4.5.2.5 Simplified mechanism on SDP offer/answer p. 78
6.4.5.2.7 Feature negotiation p. 79
6.4.5.3 Protocol usage on UNI/NNI p. 79
6.4.5.4 Protocol and version identification p. 81
6.4.5.5 RESPECT messages p. 81
6.4.5.5.1 General p. 81
6.4.5.5.2 Signalling message definition p. 81
6.4.5.5.3 Supported methods p. 82
6.4.5.5.3.1 General p. 82
6.4.5.5.3.2 Authentication method ("auth") p. 83
6.4.5.5.3.3 Media session set up method ("msetup") p. 83
6.4.5.5.3.4 Media session update method ("mupdate") p. 83
6.4.5.5.3.5 Media session disconnect method ("mdisc") p. 83
6.4.5.5.3.6 Information query method ("getinfo") p. 84
6.4.5.5.4 Keys (information elements) included in RESPECT messages p. 84
6.4.5.5.4.1 General p. 84
6.4.5.5.4.2 Common key p. 84
6.4.5.5.4.3 Individual key p. 85
6.4.5.5.4.4 Application specific key p. 98
6.4.5.5.5 Response code for error response p. 98
6.4.5.5.5.1 General p. 98
6.4.5.5.6 Originating ID and verification using signature verification and attestation information p. 99
6.4.5.5.6.1 General p. 99
6.4.5.5.6.2 Handling of originating ID p. 99
6.4.5.5.6.3 Originating ID verification using signature verification and attestation information p. 100
6.4.5.6 General call flow and procedure p. 100
6.4.5.6.1 General p. 100
6.4.5.6.2 Authentication p. 101
6.4.5.6.3 Media session setup and disconnection for the operator self-contained RTC resource p. 103
6.4.5.6.4 Media session setup and disconnection for the RTC resource provided by other operator p. 106
6.4.5.6.5 Media session setup and disconnection between UEs within a single operator network p. 110
6.4.5.6.6 Media session setup and disconnection between UEs over inter-operator networks p. 113
6.4.6 SDP p. 115
6.4.6.1 General p. 115
6.4.6.2 Session-Level Section p. 115
6.4.6.2.1 General p. 115
6.4.6.2.2 Protocol Version ("v=") p. 116
6.4.6.2.3 Origin ("o=") p. 116
6.4.6.2.4 Session Name ("s=") p. 116
6.4.6.2.5 Time Active ("t=") p. 116
6.4.6.2.6 Group Attribute ("a=group") p. 116
6.4.6.2.7 "ice-ufrag" and "ice-pwd" attributes p. 116
6.4.6.3 Media description p. 116
6.4.6.3.1 General p. 116
6.4.6.3.2.2 Audio and video p. 117
6.4.6.3.2.3 Data channel p. 117
6.4.6.3.2.4 Disabling and (re-)enabling the media description p. 117
6.4.6.3.2.5 Partial non-use of Media description p. 117
6.4.6.3.3 Connection Information ("c=") p. 117
6.4.6.3.4 Media Stream Identification Attribute ("a=mid") p. 117
6.4.6.3.5 "candidate" Attribute ("a=candidate") p. 117
6.4.6.3.6 "ice-lite" Attribute ("a=ice-lite") p. 117
6.4.6.3.7 Attribute ("a=ice-options") p. 117
6.4.6.3.8 "ice-ufrag" and "ice-pwd" attributes ("a=ice-ufrag"/"a=ice-pwd") p. 118
6.4.6.3.9 Attribute ("a=extmap") p. 118
6.4.6.3.10 Attribute ("a=bundle-only") p. 118
6.4.6.3.11 Attribute ("a=rtcp-mux-only") p. 118
6.4.6.3.12 Attribute ("a=rtcp-mux") p. 118
6.4.6.3.13 Attribute ("a=msid") p. 118
6.4.6.3.14 Attribute ("a=ssrc") p. 118
6.4.6.3.15 Attribute ("a=sendrecv" / "a=sendonly" / "a=recvonly" / "a=inactive") p. 118
6.4.6.3.16 Attribute ("a=setup") p. 118
6.4.6.3.17 Attribute ("a=fingerprint") p. 118
6.4.6.3.18 Attribute ("a=rtpmap" / "a=fmtp") p. 118
6.4.6.3.19 Attribute ("a=dcmap") p. 118
6.4.6.3.20 Attribute ("a=sctp-port") p. 119
6.4.6.3.21 Attribute ("a=max-message-size") p. 119
6.4.6.3.22 Attribute ("a=rtcp-rsize") p. 119
6.4.7 Solution evaluation p. 119
6.5 Solution #4: Functional requirements for U-Plane p. 119
6.5.1 Solution description p. 119
6.5.2 Functional requirements for U-Plane interface p. 120
6.5.3 Protocol stack p. 120
6.5.4 Solution evaluation p. 121
6.6 Solution #5: Service control API p. 121
6.6.1 Solution Description p. 121
6.6.2 Procedures for service control p. 122
6.6.2.1 General p. 122
6.6.2.2 CP-oriented procedure p. 123
6.6.2.2.1 General p. 123
6.6.2.2.2 RTC ID resource management p. 123
6.6.2.2.2.1 General p. 123
6.6.2.2.2.2 Create RTC ID resource p. 124
6.6.2.2.2.3 Read RTC ID resource p. 124
6.6.2.2.2.4 Update RTC ID resource p. 124
6.6.2.2.2.5 Delete RTC ID resource p. 124
6.6.2.3 Callback procedure p. 124
6.6.2.3.1 General p. 124
6.6.2.3.2 Notification of RTC ID resource deletion p. 125
6.6.2.3.3 Notification of forced RTC ID resource deletion p. 125
6.6.2.3.4 Notification of RTC ID resource suspended p. 125
6.6.2.3.5 Notification of RTC ID resource resumed p. 126
6.6.2.3.6 Notification of user call in requested p. 126
6.6.2.3.7 Notification of user call in accepted p. 126
6.6.2.3.8 Notification of user call in connected p. 126
6.6.2.3.9 Notification of user call disconnected p. 126
6.6.2.3.10 Notification of media routing query p. 126
6.6.3 Service Control APIs p. 127
6.6.3.1 General aspects of service control API p. 127
6.6.3.1.1 Usage of HTTP p. 127
6.6.3.1.2 Content type p. 127
6.6.3.1.3 URI structure p. 127
6.6.3.1.4 Error handling p. 128
6.6.3.1.5 HTTP headers p. 128
6.6.3.2 RTC ID resource management API p. 128
6.6.3.2.1 API URI p. 128
6.6.3.2.2 Resources p. 129
6.6.3.2.2.1 Overview p. 129
6.6.3.2.2.2 Resource: RTC ID resources p. 129
6.6.3.2.2.3 Resource: Individual RTC ID resource p. 130
6.6.3.2.3 Data model p. 132
6.6.3.2.3.1 General p. 132
6.6.3.2.3.2 Structured data types p. 134
6.6.3.2.3.3 Simple data types and enumerations p. 143
6.6.3.2.4 Error Handling p. 143
6.6.3.3 Notification of RTC ID resource deletion p. 144
6.6.3.3.1 API URI p. 144
6.6.3.3.2 Resources p. 144
6.6.3.3.3 Notification operation p. 144
6.6.3.3.4 Data Model p. 145
6.6.3.3.4.1 General p. 145
6.6.3.3.4.2 Structured data types p. 145
6.6.3.3.4.3 Simple data types and enumerations p. 146
6.6.3.3.5 Error Handling p. 146
6.6.3.4 Notification of forced RTC ID resource deletion p. 146
6.6.3.4.1 API URI p. 146
6.6.3.4.2 Resources p. 146
6.6.3.4.3 Notification operation p. 146
6.6.3.4.4 Data Model p. 147
6.6.3.4.4.1 General p. 147
6.6.3.4.4.2 Structured data types p. 148
6.6.3.4.4.3 Simple data types and enumerations p. 148
6.6.3.4.5 Error Handling p. 148
6.6.3.5 Notification of RTC ID resource suspended p. 148
6.6.3.5.1 API URI p. 148
6.6.3.5.2 Resources p. 148
6.6.3.5.3 Notification operation p. 148
6.6.3.5.4 Data Model p. 149
6.6.3.5.4.1 General p. 149
6.6.3.5.4.2 Structured data types p. 149
6.6.3.5.4.3 Simple data types and enumerations p. 149
6.6.3.5.5 Error Handling p. 150
6.6.3.6 Notification of RTC ID resource resumed p. 150
6.6.3.6.1 API URI p. 150
6.6.3.6.2 Resources p. 150
6.6.3.6.3 Notification operation p. 150
6.6.3.6.4 Data Model p. 151
6.6.3.6.4.1 General p. 151
6.6.3.6.4.2 Structured data types p. 151
6.6.3.6.4.3 Simple data types and enumerations p. 151
6.6.3.6.5 Error Handling p. 151
6.6.3.7 Notification of user call in requested p. 151
6.6.3.7.1 API URI p. 151
6.6.3.7.2 Resources p. 151
6.6.3.7.3 Notification operation p. 152
6.6.3.7.4 Data Model p. 152
6.6.3.7.4.1 General p. 152
6.6.3.7.4.2 Structured data types p. 153
6.6.3.7.4.3 Simple data types and enumerations p. 153
6.6.3.7.5 Error Handling p. 153
6.6.3.8 Notification of user call in accepted p. 153
6.6.3.8.1 API URI p. 153
6.6.3.8.2 Resources p. 153
6.6.3.8.3 Notification operation p. 153
6.6.3.8.4 Data Model p. 154
6.6.3.8.4.1 General p. 154
6.6.3.8.4.2 Structured data types p. 155
6.6.3.8.4.3 Simple data types and enumerations p. 155
6.6.3.8.5 Error Handling p. 155
6.6.3.9 Notification of user call in connected p. 155
6.6.3.9.1 API URI p. 155
6.6.3.9.2 Resources p. 155
6.6.3.9.3 Notification operation p. 155
6.6.3.9.4 Data Model p. 156
6.6.3.9.4.1 General p. 156
6.6.3.9.4.2 Structured data types p. 156
6.6.3.9.4.3 Simple data types and enumerations p. 157
6.6.3.9.5 Error Handling p. 157
6.6.3.10 Notification of user call in connected p. 157
6.6.3.10.1 API URI p. 157
6.6.3.10.2 Resources p. 157
6.6.3.10.3 Notification operation p. 157
6.6.3.10.4 Data Model p. 158
6.6.3.10.4.1 General p. 158
6.6.3.10.4.2 Structured data types p. 158
6.6.3.10.4.3 Simple data types and enumerations p. 158
6.6.3.10.5 Error Handling p. 158
6.6.3.11 Notification of media routing query p. 159
6.6.3.11.1 API URI p. 159
6.6.3.11.2 Resources p. 159
6.6.3.11.3 Notification operation p. 159
6.6.3.11.4 Data Model p. 160
6.6.3.11.4.1 General p. 160
6.6.3.11.4.2 Structured data types p. 160
6.6.3.11.4.3 Simple data types and enumerations p. 160
6.6.3.11.5 Error Handling p. 160
6.6.4 Solution evaluation p. 160
6.7 Solution #6: WSF Discovery mechanism p. 161
6.7.1 Solution description p. 161
6.7.1.1 General p. 161
6.7.1.2 Analysis on possible mechanisms p. 161
6.7.2 Common URL based WSF discovery mechanism p. 161
6.7.2.1 General p. 161
6.7.2.2 Common URL format p. 162
6.7.2.3 Common URL based WSF discovery procedure p. 162
6.7.3 Functional entity supporting WSF discovery function p. 164
6.7.4 Solution evaluation p. 164
6.8 Solution #7: Interworking with IMS network p. 165
6.8.1 Solution description p. 165
6.8.2 Interface between RTC network and IMS network p. 165
6.8.3 Interworking scenarios p. 166
6.8.3.1 General p. 166
6.8.3.2 Supported connection patterns p. 166
6.8.3.3 Supported media session p. 167
6.8.4 Functional requirements for RTC-IMS interworking p. 167
6.8.4.1 General p. 167
6.8.4.2 Functional requirements for RTC network p. 167
6.8.4.3 Functional requirements for IMS network p. 168
6.8.5 RTC architecture enhancement for RTC-IMS interworking p. 168
6.8.6 Solution evaluation p. 168
6.9 Solution #8: Protocol-level interworking between RTC network and IMS network p. 169
6.9.1 Solution description p. 169
6.9.2 C-Plane signalling interworking p. 169
6.9.2.1 General p. 169
6.9.2.2 Protocol stack p. 170
6.9.2.3 Interworking procedures at the IWF p. 170
6.9.2.3.1 General p. 170
6.9.2.3.2 Media session setup from RTC to IMS p. 170
6.9.2.3.2.1 General p. 170
6.9.2.3.2.2 Receiving msetup request containing a preOffer p. 170
6.9.2.3.2.3 Receiving SIP 18x response containing an initial SDP answer p. 172
6.9.2.3.2.4 Receiving SIP 18x response not containing SDP p. 173
6.9.2.3.2.5 Receiving SIP 200 (OK) response containing an initial SDP answer to the initial INVITE request p. 174
6.9.2.3.2.6 Receiving SIP 200 (OK) response not containing SDP to the initial INVITE request p. 176
6.9.2.3.3 Media session setup from IMS to RTC p. 177
6.9.2.3.3.1 General p. 177
6.9.2.3.3.2 Receiving SIP initial INVITE request containing an initial SDP offer p. 177
6.9.2.3.3.3 Receiving msetup response not containing SDP with media session state change p. 178
6.9.2.3.3.4 Receiving mupdate request not containing SDP without media session state change p. 178
6.9.2.3.3.5 Receiving mupdate request containing an "answer" with media session state change p. 179
6.9.2.3.3.6 Receiving mupdate request containing an "offer" without media session state change p. 180
6.9.2.3.3.7 Receiving mupdate request not containing SDP with media session state change p. 181
6.9.2.3.4 Media session set up callcellation from RTC to IMS p. 181
6.9.2.3.4.1 General p. 181
6.9.2.3.4.2 Receiving mdisc request for establishing media session p. 181
6.9.2.3.5 Media session set up callcellation from IMS to RTC p. 182
6.9.2.3.5.1 General p. 182
6.9.2.3.5.2 Receiving SIP CANCEL request for establishing media session p. 182
6.9.2.3.6 Media session update from RTC to IMS p. 183
6.9.2.3.7 Media session update from IMS to IMS p. 183
6.9.2.3.8 Media session release from RTC to IMS p. 183
6.9.2.3.9 Media session release from IMS to RTC p. 184
6.9.3 U-Plane media related interworking p. 185
6.9.5 Solution evaluation p. 186
6.10 Solution #9: Tethered cases p. 186
6.10.1 Solution description p. 186
6.10.2 Solution evaluation p. 189
6.11 Solution #10: Security considerations p. 189
6.11.1 Solution Description p. 189
6.11.2 Adaptation of the trust domain p. 189
6.11.3 Network-asserted identity within the trust domain p. 189
6.11.4 Adaptation of calling number verification using signature verification and attestation information p. 190
6.12 Solution #11: Related groups considerations p. 191
6.12.1 Solution description p. 191
6.12.2 Solution evaluation p. 191
7 Key findings p. 191
