5.2.2 Message flows

32.2553GPP5G data connectivity domain chargingCharging managementRelease 17Stage 2Telecommunication managementTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

5.2.2.1 General

The flows in the present document specify the interaction between the SMF and the CHF for 5G data connectivity converged charging functionality, in different scenarios, based on TS 23.501 [200] and TS 23.502 [201] procedures and flows.

This interaction is based on Charging Data Request /Response specified in TS 32.290 [57], exchanged between the SMF embedding the CTF and the CHF.

As a general principle, the steps in the figures for the message flows below correspond to the steps of figures in TS 23.502 [201], which is the reference. This document specifies the charging specific extension part.

5.2.2.2 PDU session charging from SMF

5.2.2.2.1 General

The subclause below describes PDU session charging in non-roaming scenarios.

5.2.2.2.2 PDU session establishment

The following figure 5.2.2.2.2-1 describes a PDU session establishment charging, based on figure 4.3.2.2.1.1 TS 23.502 [202] description:

Figure 5.2.2.2.2-1: PDU session establishment

8. The SMF selects an SSC mode for the PDU Session and also selects one or more UPFs.

9. The SMF may perform a Session Management Policy Modification procedure to report some event to the PCF that has previously subscribed.

9ch-a.The SMF creates a Charging Id for the PDU session, and sends Charging Data Request[initial] to CHF for authorization for the subscriber to start the PDU session which is triggered by start of PDU session charging event (The SMF may include 5GS CIoT optimizations information, see TS TS 23.502 [201]).

9ch-b. The CHF opens CDR for this PDU session.

9ch-c. The CHF acknowledges by sending Charging Data Response[Initial] to the SMF.

15. AMF to SMF: SM Request (N2 SM information).

[16a-b]. N4 session Modification.

16ch-a. This step may occur in case "start of service data flow" needs quota from CHF, for the SMF to request quota.

16ch-b. The CHF updates CDR for this PDU session.

16ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

NOTE 1: The steps from 16ch-a to 16ch-c for quota request from CHF are not applicable for offline only charging.

17. SM Request with PDU session Update Response to AMF.

18. SMF sends SM Context Status Notify to AMF.

19. In case of PDU Type IPv6, IPv6 Address Configuration.

5.2.2.2.3 PDU Session Modification

The following figure 5.2.2.2.3-1 describes the PDU session modification charging, based on figure 4.3.3.2-1 TS 23.502 [202] description:

Figure 5.2.2.2.3-1: PDU Session Modification

2ch-a. The SMF sends Charging Data Request [Update] to the CHF for reporting the charging information when the corresponding trigger is armed.

2ch-b. The CHF update the CDR for the PDU session.

2ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the SMF.

5.2.2.2.4 PDU Session Release

The following figure 5.2.2.2.4-1 describes the PDU session release charging, based on figure 4.3.4.2-1 TS 23.502 [202] description:

Figure 5.2.2.2.4-1: PDU Session Release

2ch-a. The SMF sends Charging Data Request [Termination] to the CHF for terminating the charging associated with PDU sessions, with the trigger "End of PDU session".

2ch-b. The CHF closes the CDR for the PDU session.

2ch-c. The CHF acknowledges by sending Charging Data Response [Termination] to the SMF.

5.2.2.3 PDU session charging SSC Mode 1 from SMF

5.2.2.3.1 General

The subclause below describes PDU session SSC mode 1 charging in non-roaming scenarios.

5.2.2.3.2 PDU session charging SSC Mode 1

The following figure 5.2.2.3.2.1 describes a PDU session SSC mode 1 charging, based on clause 5.6.9.2.1 TS 23.501 [201] description:

Figure 5.2.2.3.2.1: (R)AN relocation for PDU session in SSC mode 1

Ongoing charging interaction associated with the established PDU session (UPF).

1. A (R)AN relocation is performed.

2. The SMF determines that the serving UPF needs to be maintained and interacts with the UPF for the path switch to the new (R)AN access.

3. the SMF acknowledges the path switch to the new (R)AN.

3ch-a. The SMF sends Charging Data Request[Update] to the CHF for reporting the charging information User location information/ Access Technology Type Information.

3ch-b. The CHF updates the CDR.

3ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

5.2.2.4 PDU session Charging SSC Mode 2 from SMF

5.2.2.4.1 General

The subclause below describes PDU session charging for change the PDU Session Anchor serving a PDU Session of SSC mode 2

5.2.2.4.2 PDU session Charging SSC Mode 2

The following figure 5.2.2.4.2.1 describes a PDU session anchor relocation in SSC mode 2 charging, based on figure 4.3.5.1.1 TS 23.502 [201] description:

Figure 5.2.2.4.2.1: PDU session anchor relocation in SSC mode 2 with single PDU session anchor

Ongoing charging session associated with the established PDU session (UPF1)

2. PDU session release procedure (UPF1).

2ch-a. The SMF1 sends Charging Data Request[Termination] to the CHF for terminating the charging associated with old PDU session in UPF1.

2ch-b. The CHF closes the CDR for old PDU session in UPF1.

2ch-c. The CHF acknowledges by sending Charging Data Response[Termination] to the SMF1.

3. PDU session establishment procedure (UPF2).

3ch-a. The SMF2 creates a Charging Id for new PDU session ID in UPF2 and sends Charging Data Request[initial] to CHF for authorization for the subscriber to start the new PDU session which is triggered by start of PDU session charging event.

3ch-b. The CHF opens CDR for new PDU session in UPF2.

3ch-c. The CHF acknowledges by sending Charging Data Response[initial] to the SMF2.

NOTE: If the same SMF1 is re-selected is step 3, the same steps 3ch-a to b apply to SMF1

5.2.2.5 PDU session Charging SSC Mode 3 from SMF

5.2.2.5.1 General

The subclause below describes PDU session charging for change the PDU Session Anchor serving a PDU Session of SSC mode 3.

5.2.2.5.2 PDU session Charging SSC Mode 3

The following figure 5.2.2.5.2.1 describes a PDU session anchor relocation in SSC with mode 3 multiple PDU sessions and SMF reallocation, based on figure 4.3.5.2.1 TS 23.502 [201] description:

Figure 5.2.2.5.2.1: PDU session anchor relocation in SSC mode 3 with multiple PDU sessions – SMF reallocation

Ongoing charging interaction associated with the established PDU session (with UPF1).

4. UE initiates PDU session establishment procedure with UPF2..

4ch-a. The SMF2 creates a Charging Id for new PDU session ID with UPF2 and sends Charging Data Request[initial] to CHF for authorization for the subscriber to start the new PDU session (with UPF2) which is triggered by start of PDU session charging event.

4ch-b. The CHF opens CDR for new PDU session in UPF2.

4ch-c. The CHF acknowledges by sending Charging Data Response[initial] to the SMF2.

6. Old PDU session for UPF1 release.

6ch-a. The SMF1 sends Charging Data Request[Termination] to the CHF for terminating the charging associated with old PDU session in UPF1.

6ch-b. The CHF closes the CDR for old PDU session in UPF1.

6ch-c. The CHF acknowledges by sending Charging Data Response[Termination] to the SMF1.

5.2.2.6 PDU session Charging SSC Mode 3 IPv6 Multi Homed from SMF

5.2.2.6.1 General

The subclause below describes PDU session charging for service continuity with SSC mode 3 using the multi-homed PDU Session.

5.2.2.6.2 PDU session Charging SSC Mode 3 IPv6 Multi Homed

The following figure 5.2.2.6.2.1 describes a PDU session anchor relocation in SSC mode 3 with IPv6 Multi homed PDU Session charging, based on figure 4.3.5.3.1 TS 23.502 [201] description:

Figure 5.2.2.6.2.1: PDU session anchor relocation in SSC mode 3 with IPv6 Multi homed PDU Session

Ongoing charging interaction associated with the established PDU session (UPF1).

Traffic starts at UPF2.

11ch-a. The SMF sends Charging Data Request[Update] to the CHF for request quota for UPF2 which is triggered by start of service data flow charging event, if quota management per UPF.

11ch-b. The CHF updates CDR for this PDU session

11ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

[12a-b to 13a-b] The SMF releases the UE’s old IPv6 prefix (IP@1), and releases the path between BP UPF and UPF1.

13ch-a. The SMF sends Charging Data Request[Update] to the CHF for usage reporting for UPF1 which is triggered by termination of service data flow charging event, if quota management per UPF.

13ch-b. The CHF updates CDR for this PDU session.

13ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

In this scenario, the PDU session Id is maintained during the whole procedure.

5.2.2.7 Addition of additional PDU Session Anchor and Branching Point or UL CL

The following figure 5.2.2.7.1 describes the charging procedure to add a PDU Session Anchor and a Branching Point or UL CL for an established PDU Session, based on figure 4.3.5.4.1 TS 23.502[201].

Figure 5.2.2.7.1: Addition of additional PDU Session Anchor and Branching Point or UL CL

Ongoing charging interaction associated with the established PDU session (UPF).

3. The SMF establishes the Branching Point (in case of IPv6 multi-homing) or a UL CL for the PDU Session.

3ch-a. The SMF sends Charging Data Request[Update] to the CHF for the additional of UPF (PSA 2) if quota management is granted per UPF by trigger "Addition of UPF".

3ch-b. The CHF updates the CDR for the charging information of UPF (PSA 2).

3ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

5.2.2.8 Removal of additional PDU Session Anchor and Branching Point or UL CL

The following figure 5.2.2.8.1 describes charging procedure to remove a PDU Session Anchor and (optionally) remove Branching Point or UL CL for an established PDU Session, based on figure 4.3.5.5.1 TS 23.502[201].

Figure 5.2.2.8.1: Removal of additional PDU Session Anchor and Branching Point or UL CL

Ongoing charging interaction associated with the established PDU session (UPF).

5. The SMF releases via N4 the PSA1.

5ch-a. The SMF sends Charging Data Request[Update] to the CHF for the removal of UPF (PSA 1) if quota management is granted per UPF by trigger "Removal of UPF".

5ch-b. The CHF updates the CDR for the charging information of UPF (PSA 1).

5ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

6. If steps 4 and 5 were executed, the SMF releases the Branching Point / UL CL.

5.2.2.9 Change of additional PDU Session Anchor for IPv6 multi-homing or UL CL

The following figure 5.2.2.9.1 charging procedure to establish a new additional PDU Session Anchor (i.e., PSA2) and conditionally releases the existing additional PDU Session Anchor (i.e. PSA1), while modifying IPv6 multi-homing or UL CL rule in the same Branching Point or UL CL under controlled by the same SMF abased on figure 4.3.5.6.1 TS 23.502[201].

Figure 5.2.2.9.1: Change of additional PSA for a PDU Session in IPv6 multi-homing or UL CL case

Ongoing charging interaction associated with the established PDU session (UPF).

3a-b. The SMF exchange the N4 message toBranching Point or UL CL .

3ch-a. The SMF sends Charging Data Request[Update] to the CHF for the additional of UPF (PSA 2) if quota management is granted per UPF by trigger "Addition of UPF".

3ch-b. The CHF updates the CDR for the charging information of UPF (PSA 2).

3ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

6a-b. Step 6 occurs only if the Branching Point or UL CL does not have any traffic filter on the PDU Session which forwards a traffic flow to PSA1.

6ch-a. The SMF sends Charging Data Request[Update] to the CHF for the removal of UPF (PSA 1) if quota management is granted per UPF by trigger "Removal of UPF".

6ch-b. The CHF updates the CDR for the charging information of UPF (PSA 1).

6ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

5.2.2.10 Simultaneous change of Branching Point or UL CL and additional PSA for a PDU Session

The following figure 5.2.2.10.1 describe the charging procedure to change the Branching Point or the UL CL and additional PSA serving a PDU Session for a UE triggered by SMF ((just an example call flow triggered by Xn based handover) based on figure 4.3.5.7.1 TS 23.502[201].

Figure 5.2.2.10.1: Simultaneous change of Branching Point or UL CL and additional PSA for a PDU Session

Ongoing charging interaction associated with the established PDU session (UPF).

3ch-a. The SMF sends Charging Data Request[Update] to the CHF for the additional of Target UPF if quota management is granted per UPF by trigger "Addition of UPF".

3ch-b. The CHF updates the CDR for the charging information of Target UPF.

3ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

9. The SMF releases PSA2.

9ch-a. The SMF sends Charging Data Request[Update] to the CHF for the removal of Source UPF if quota management is granted per UPF by trigger "Removal of UPF".

9ch-b. The CHF updates the CDR for the charging information of Source UPF.

9ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the SMF.

5.2.2.11 PDU session charging for interworking with EPC

5.2.2.11.1 General

In order to interwork with EPC, the N26 interface is introduced as an inter-CN interface between the MME in EPC and 5GS AMF in order to enable provide seamless session continuity for single registration mode UE for inter-system change in the clause 5.17.2.2 TS 23.501[201].

PCF + PCRF, PGW-C + SMF and UPF + PGW-U are dedicated for interworking between 5GS and EPC, which are optional and are based on UE MM Core Network Capability and UE subscription in the clause 4.3 TS 23.501 [201]. The procedures for interworking with EPS based on N26 interface are specified in clause 4.11.1 TS 23.502 [201].

When 5GS and EPC interworking, interaction between the PGW-C + SMF and CHF is using the same interface as for interaction between SMF and CHF.

When a UE establishes a PDN connection/PDU session with PGW-C+SMF in EPS or 5GS, a charging session is established for the PDU session and PDN connection to support 5GS and EPS interworking as follows:

– When a UE is served by EPC, a charging session is established between the PGW-C+SMF and CHF via Nchf interface for EPC online charging and offline charging if 5GS interworking indication from SGW indicates that the UE supports 5G and the PDN connection is not restricted to interworking with 5GS by user subscription.

– When a UE is served by 5GS, a charging session is established between the PGW-C+SMF and CHF via Nchf interface for 5GS converged online and offline charging.

– When a UE is served by EPC, the PGW-C+SMF acts as the PGW and a charging session is established via Gy interface for EPC online charging and Gz interface for offline charging if 5GS interworking is not supported.

The chargeable events for 5GS and EPC interworking are handover cancel, handover start and handover complete.

The triggers for 5GS and EPC interworking may be enabled or disabled, the PGW-C+SMF will interact with charging system as the following:

– If the trigger for interworking is enabled and the category is set to "immediate reporting", the PGW-C+SMF will report usage in source network and/or request quota for target network.

– If the trigger for interworking is enabled and the category is set to "defered reporting", the PGW-C+SMF will close the count in source network and start a new count in target network, and continue to consume the quota in target network. The source access specific triggers will no more be applicable in the PGW-C+SMF, the target access specific triggers will apply instead.

– If the trigger for interworking is disabled, the PGW-C+SMF will record usage for both source and target network accesses into common count, and consumes the same quota in source and target network. The source access specific triggers will no more be applicable in the PGW-C+SMF, the target access specific triggers will apply instead.

5.2.2.11.2 5GS to EPS handover using N26 interface

The following figure 5.2.2.11.2.1 describes the handover from 5GS to EPS when N26 is supported, based on figure 4.11.1.2.1.1 TS 23.502 [201] description:

Figure 5.2.2.11.2.1: 5GS to EPS handover using N26

0. A PDU session is established in 5GS with multiple QoS Flows. A "Charging Id" was assigned to the PDU session.

0ch. A charging session between the PGW-C+SMF and CHF exists for this PDU session.

10c. PDU session update response to AMF.

10ch-a. This step occurs if steps 10a-c occurred. All counts are closed and a Charging Data Request [Update] is sent to CHF, if required by "Handover start" trigger. New counts and time stamps for all active service data flows are started in the PGW-C+SMF.

10ch-b. The CHF updates CDR for this PDU session.

10ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

16. User Plane path switch for the default bearer and the dedicated GBR bearers between the UE and PGW-U+UPF via SGW. The "Charging Id" assigned to the PDN connection is supplied as the "Charging Id" for the default bearer. The "EPS bearer Charging Id" assigned to the dedicated EPS bearer(s), is supplied as the "Charging Id" for that dedicated EPS bearer.

16ch-a. All counts are closed and a Charging Data Request [Update] is sent to CHF, if required by "RAT type change" trigger. New counts and time stamps for all active service data flows are started in the PGW-C+SMF (The PGW-C+SMF may include APN Rate Control Change, see TS 23.502 [201]).

16ch-b. The CHF updates CDR.

16ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

19. Dedicated bearer activation procedure for non-GBR QoS flows initiated by PGW-C+SMF.

19ch. Needed counts are started on start of service data flows of corresponding non-GBR Qos Flows.

5.2.2.11.3 EPS to 5GS handover using N26 interface

The following figures 5.2.2.11.3.1 and 5.2.2.11.3.2 describe the handover from EPS to 5GS when N26 is supported, based on figures 4.11.1.2.2.2.1 and 4.11.1.2.2.3.1 TS 23.502 [201] description:

Figure 5.2.2.11.3.1: EPS to 5GS handover using N26 – preparation

0. If the UE supports 5G and the PDN connection is not restricted to interworking with 5GS by user subscription, the PGW-C+SMF is aware that 5GS interworking is supported. A PDN connection is established in EPC with default bearer and dedicated bearers. Association between the EPS bearer and the corresponding 5G QoS Rules is stored by the PGW-C+SMF.

0ch. A charging session between the PGW-C+SMF and CHF exists for this PDN connection with associated to the default bearer and dedicated bearers. The default bearer is assigned with the "Charging Id" of the PDN connection. The dedicated bearers are assigned with the "EPS bearer Charging Id".

As described in clause 4.11.1.2.2 of TS 23.502 [201] the PGW-C+SMF may receive APN Rate Control Status enabled during interworking with EPC for this PDN connection, the PGW-C+SMF interacts with CHF as following:

13ch-a. All counts are closed and a Charging Data Request [Update] is sent to CHF, if required by "RAT type change" trigger. The APN Rate Control Change may be provided by PGW-C+SMF in charging information if received.

13ch-b. The CHF updates CDR for this PDN connection.

13ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

Figure 5.2.2.11.3.2: EPS to 5GS handover using N26 – execution

10ch-a. All counts are closed and a Charging Data Request [Update] is sent to CHF, if required by "RAT type change" trigger. New counts and time stamps for all active service data flows are started in the PGW-C+SMF.

10ch-b. The CHF updates CDR for this PDU session.

10ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

5.2.2.11.4 Handover Cancel

The following figures 5.2.2.11.4.1 describe the handover cancel, based on clause 4.11.1.2.3 TS 23.502 [201] description:

Figure 5.2.2.11.4.1: Handover Cancel

4. Based on the Relocation Cancel Indication, the target CN node (MME or AMF) deletes the session resources established during handover preparation phase in SGW (SGW-C and SGW-U)/ (SMF and UPF).

4ch-a. All counts are closed and a Charging Data Request [Update] is sent to CHF which triggered by "Handover cancel", New counts and time stamps for all active service data flows are started in the PGW-C+SMF.

4ch-b. The CHF updates CDR for this PDU session.

4ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

7. If indirect forwarding tunnel is setup during handover preparation phase then cancellation of handover triggers the source CN node to release the temporary resources used for indirect forwarding.

8. If indirect forwarding tunnel is setup during handover preparation phase then cancellation of handover triggers the target CN node to release the temporary resources used for indirect forwarding.

5.2.2.11.5 EPS to 5GS mobility without N26 interface

The following figures 5.2.2.11.5.1 describe the handover from EPS to 5GS without N26 support, based on clause 4.11.2.3 TS 23.502 [201] description:

Figure 5.2.2.11.5.1: EPS to 5GS mobility without N26

0. The UE is attached in EPC.

1-8. UE initiate registration procedure to the 5GS and indicates that it is moving from EPC.

9. UE requested PDU Session Establishment.

9ch-a. a Charging Data Request [Update] is sent to CHF which is trigged by Handover start charging event, New counts and time stamps for all active service data flows are started in the PGW-C+SMF.

9ch-b. The CHF updates CDR for this PDU session.

9ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

10. The PGW-C+SMF performs release of the resources in EPC for the PDN connections(s) transferred to 5GS by performing the PDN GW initiated bearer deactivation procedure.

10ch-a. All counts are closed and a Charging Data Request [Update] is sent to CHF which is trigged by Handover complete charging event.

10ch-b. The CHF updates CDR.

10ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

5.2.2.11.6 5GS to EPS mobility without N26 interface

The following figures 5.2.2.11.6.1 describe the handover from 5GS to EPS without N26 support, based on clause 4.11.2.2 TS 23.502 [201] description:

Figure 5.2.2.11.6.1: 5GS to EPS mobility without N26

UE is registered in 5GS.

1-6. TAU procedure is triggered to start for E-UTRAN initial attach.

7. UE initiate E-UTRAN Initial Attach procedure to the EPS and indicates that it is moving from 5GS.

7ch-a. a Charging Data Request [Update] is sent to CHF which is triggered by Handover start charging event. New counts and time stamps for all active service data flows are started in the PGW-C+SMF.

7ch-b. The CHF updates CDR for this PDU session.

7ch-c.The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

10. If the UE has remaining PDU Sessions in 5GS which it wants to transfer to EPS and maintain the same IP address/prefix, the UE performs the UE requested PDN Connectivity Procedure.

14. The PGW-C+SMF initiates release of the PDU Session(s) in 5GS transferred to EPS.

14ch-a. All counts are closed and a Charging Data Request [Update] is sent to CHF which is triggered by Handover complete charging event.

14ch-b. The CHF updates CDR for this PDU session.

14ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

5.2.2.11.7 EPS to 5GS handover for roaming in Home routed scenario

The following figure 5.2.2.11.7.1 describes the handover from EPS to 5GS for roaming in Home routed scenario, focusing on the charging id generation mechanism.

Figure 5.2.2.11.7.1: EPS to 5GS mobility without N26 in Home-Routed Roaming

1. The UE is attached in EPC and initiates a new PDU connection(IP-CAN session).

1ch-a. A Charging Data Request [Initial] is sent to CHF via PGW-C+SMF in HPLMN. The charging ID included is generated by PGW-C +SMF in HPLMN.

1ch-b. The H-CHF opens a CDR 1ch-c. The H-CHF acknowledges by sending Charging Data Response [Initial] to the PGW-C+SMF.

2. UE initiates registration procedure to the 5GS and indicates that it is moving from EPC. UE requests PDU Session Establishment.

2ch-a. SMF in VPLMN creates a charging ID (Visited created Charging Id) for the PDU session and sends the Charging Data Request [Initial] to CHF in VPLMN

2ch-b. The CHF in VPLMN opens a CDR.

2ch-c. The CHF in VPLMN acknowledges by sending Charging Data Response [Initial] to the SMF and optionally supplies a “Roaming Charging Profile” to the V-SMF which override the default one.

3. UPF selection and V-SMF sends the PDU session establishement request to H-SMF.

3ch-a. A Charging Data Request [Update] is sent to CHF in HPLMN, indicating the "Roaming Charging Profile" received from the VPLMN. The same charging ID in step 1ch-a will be the only one charging ID used for any subsequent charging data request sent from H-SMF to CHF i.e. the charging id generated in PGW-C +SMF in HPLMN.

3ch-b. The CHF in HPLMN updates the CDR.

3ch-c. The CHF in HPLMN acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF and supplies the HPLMN selected "Roaming Charging Profile" to the PGW-C+SMF.

4. H-SMF sends the PDU session establishment response with charging Id (Home provided Charging ID).

4ch-a. A Charging Data Request [Update] is sent to CHF in VPLMN, with the "Roaming Charging Profile", charging ID (Visited created Charging Id) and Home provided Charging ID.

4ch-b. The CHF updates the CDR.

4ch-c. The CHF acknowledges by sending Charging Data Response [Update].

NOTE: Void

In subsequent charging data request sent from V-SMF to V-CHF, the charging ID Information element has the value of Home provided charging ID, and the Home provided charging ID Information element is not provided

5.2.2.11.8 Handover from EPC/ePDG to 5GS

The following figure 5.2.2.11.11.1 describes the handover from EPC/ePDG to 5GS for non-roaming scenario based on clause 4.11.4.1 Handover from EPC/ePDG to 5GS of TS 23.502 [201].

Figure 5.2.2.11.11.1: Handover from EPC/ePDG to 5GS

0. One or more PDN Connections have been established.

1. UE register to 5GC via NG RAN.

2. The UE initiates a UE requested PDU Session Establishment via 3GPP Access and includes the "Existing PDU Session" indication or "Existing Emergency PDU Session" and the PDU Session ID.

2ch-a. PGW-C+SMF sends Charging Data Request [Update] to CHF if required by "RAT type change" trigger.

2ch-b. The CHF updates for this PDU session

2ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

3. Step 10-14, in procedure of UE requested PDU Session Establishment.

4. The combined PGW+SMF/UPF initiates a PDN GW initiated Resource Allocation Deactivation to release the EPC and ePDG resources.

5.2.2.11.9 Handover from 5GS to EPC/ePDG

The following figure 5.2.2.11.9.1 describes the handover from 5GS to EPC/ePDG based on clause 4.11.4.2 Handover from 5GS to EPC/ePDG in TS 23.502 [201].

Figure 5.2.2.11.9.1: Handover from 5GS to EPC/ePDG

0) One or more PDU Sessions have been established between the UE and the SMF/UPF via NG-RAN.

1) UE selects an ePDG.

2) Step A1 in procedure of the UE initiates a Handover Attach procedure.

2ch-a. PGW-C+SMF sends Charging Data Request [Update] to CHF if required by "RAT type change" trigger.

2ch-b. The CHF updates for this PDU session.

2ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

3) Step C1, in procedure of the UE initiates a Handover Attach procedure to the release of resources.

4) The combined PGW+SMF/UPF initiates a network requested PDU Session Release via 3GPP access.

5.2.2.12 PDU session charging for roaming in Home routed scenario

5.2.2.12.1 General

The subclauses below describe PDU session charging for roaming in Home routed scenario focusing on roaming QBC procedures between SMF and a CHF in respective PLMNs.

In H-PLMN, PDU session charging for FBC between H-SMF and a H-CHF occurring within the same charging session is not reflected.

5.2.2.12.2 PDU session establishment

The following figure 5.2.2.12.2.1 describes a PDU session charging establishment in roaming Home routed scenario based on figure 4.3.2.2.2.1 TS 23.502 [201] description:

Figure 5.2.2.12.2.1: PDU session charging: establishment roaming Home Routed

1-3a. UE initiates a new PDU session. V-SMF and H-SMF selection by the AMF.

3ch-a. The UE is identified as a roamer (PLMN ID of the received SUPI is different from VPLMN PLMN ID), the CHF is selected accordingly (the V-SMF may include 5GS CIoT related information).

3ch-b. A Charging Data Request [Initial] is sent to CHF, indicating "in-bound roamer".

3ch-c. The CHF opens a CDR (indicating "in-bound roamer")

3ch-d. The CHF acknowledges by sending Charging Data Response[Initial] to the SMF and optionally supplies a "Roaming Charging Profile" to the V-SMF which overrides the default one.

10. UPF selection.

11. If dynamic PCC is deployed, SM policy association modification.

11ch-a. Based on UE is identified as roaming in a different PLMN, the CHF is selected accordingly.

11ch-b. A Charging Data Request [Initial] is sent to CHF, indicating "out-bound roamer", with the "Roaming Charging Profile" received from the VPLMN (the H-SMF may include 5GS CIoT related information).

11ch-c. The CHF opens a CDR (indicating "out-bound roamer").

11ch-d. The CHF acknowledges by sending Charging Data Response[Initial] to the H-SMF and supplies the HPLMN selected "Roaming Charging Profile" (either the same as the one received from VPLMN, either its own selected) to the H-SMF.

[12a-b]. The SMF initiates an N4 Session Establishment procedure with the selected UPF.

12ch. Counts per QFI are started.

13. Nsmf_PDUSession_Create Response from H-SMF to V-SMF

13ch-a. Based on "received PDU session conditions" trigger, a Charging Data Request [Update] is sent to CHF with charging information received from H-SMF, which includes the HPLMN selected "Roaming Charging Profile" and counts per QFI are started.

13ch-b. The CHF updates the CDR.

13ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the V-SMF.

19a-b. N4 session modification.

19ch-a. Counts per rejected QFI(s) are closed. A Charging Data Request [Update] is sent to CHF to report if needed.

19ch-b. The CHF updates the CDR.

19ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the V-SMF.

23. Nsmf_PDUSession_UpdateRequest from V-SMF to H-SMF. The rejected QFI(s) are notified to H-SMF.

23ch-a. Counts per rejected QFI(s) are closed. A Charging Data Request [Update] is sent to CHF to report if needed.

23ch-b. The CHF updates the CDR.

23ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the H-SMF.

5.2.2.12.3 PDU session modification

The following figure 5.2.2.12.3.1 describes a PDU Session Modification procedure, home-routed roaming scenario based on figure 4.3.3.3.1 TS 23.502 [201] description:

Figure 5.2.2.12.3.1: UE or network requested PDU Session Modification (for home-routed roaming scenario)

9ch-a. A Charging Data Request [Update] is sent to V-CHF with charging information received from V-SMF, if needed and new counts per QFI are started.

9ch-b. The CHF updates the CDR.

9ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the V-SMF.

16ch-a. A Charging Data Request [Update] is sent to H-CHF with charging information received from H-SMF, if needed, and new counts per QFI are started.

16ch-b. The CHF updates the CDR.

16ch-c. The CHF acknowledges by sending Charging Data Response[Update] to the H-SMF.

5.2.2.12.4 PDU session release

The following figure 5.2.2.8.4.1 describes a PDU session charging release in roaming home routed scenario based on figure 4.3.4.3.1 TS 23.502 [201] description:

Figure 5.2.2.12.4.1: PDU session charging: release roaming home Routed

2a-2b. (UE, (R)AN or serving network initiated) N4 session release between H-SMF and H-UPF.

2ch_a. A Charging Data Request [Termination] is sent to CHF with the set of QFI(s) counts.

2ch-b. The CHF closes the CDR

2ch-c. The CHF acknowledges by sending Charging Data Response[Termination] to the H-SMF.

4a-4b. N4 session release between V-SMF and V-UPF.

4ch-a. A Charging Data Request [Termination] is sent to CHF with the set of QFI(s) counts.

4ch-b. The CHF closes the CDR

4ch-c. The CHF acknowledges by sending Charging Data Response[Termination] to the V-SMF.

15b-15c. (HPLMN initiated release) N4 session release between H-SMF and H-UPF.

15ch_a. A Charging Data Request [Termination] is sent to CHF with the set of QFI(s) counts.

15ch-b. The CHF closes the CDR

15ch-c. The CHF acknowledges by sending Charging Data Response [Termination] to the H-SMF.

NOTE: Either 2ch or 15ch is done depending on if the release is UE, (R)AN, serving network, or HPLMN initiated.

5.2.2.13 PDU session charging – non-3GPP access

5.2.2.13.1 General

After UE registration to 5GC via an non-3GPP access network, a PDU session can be established via this non-3GPP access. For following scenarios, the PDU session establishment via untrusted non-3GPP access network is specified in clause 4.12 of TS 23.502 [201] and the PDU session establishment via trusted non-3GPP access network is specified in clause 4.12a of TS 23.502 [201]:

– UE initiated PDU session establishment;

– Handover of a PDU Session from 3GPP access to untrusted non-3GPP access;

– Service Request procedures via Untrusted non-3GPP Access specified in clause 4.12.4.5 of TS 23.502 [201];

– Service Request procedures via Trusted non-3GPP Access specified in clause 4.12.4a.5 of TS 23.502 [201].

Handover procedure of a PDU Session between 3GPP access and non-3GPP access is achieved by PDU Session Establishment over source access followed by PDU Session Release over the target access for respective N2 Resources Release. The PDU Session ID, IP address/prefix, and SSC mode are maintained during the move.

PDU session over Untrusted non-3GPP Access release and Trusted non-3GPP Access release are specified in clause 4.12.7 and clause 4.12a.7 of TS 23.502 [201].

5.2.2.13.2 PDU session establishment

5.2.2.13.2.1 PDU session establishment via an untrusted non-3GPP access network

The following figure 5.2.2.13.2.1 describes a PDU session charging establishment via an untrusted non-3GPP access network scenario based on figure 4.12. 5.1 in TS 23.502 [201] description:

Figure 5.2.2.13.2.1: PDU Session establishment via untrusted non-3GPP access

[2ch-a to 2ch-c]. Two cases:

– In case of "Initial request" the same steps as steps 7ch-a to 7ch-c in figure 5.2.2.2.1 apply, for initial SMF interaction with CHF, with Charging Data Request [Initial].

– In case of "Existing PDU Session" the "radio access type change" trigger may apply for SMF interaction with CHF, with Charging Data Request [Update].

5.2.2.13.2.2 PDU session establishment via Trusted Non-3GPP access network

After the UE registers to 5GC via trusted non-3GPP access network, the UE may request a PDU Session establishment by using the same procedure as the one specified in clause 5.2.2.13.2.1 for untrusted non-3GPP access, with the following modifications:

– The N3IWF in Figure 5.2.2.13.2.1 should be substituted with a TNGF and the Untrusted non-3GPP access should be substituted with a Trusted non-3GPP Access Point (TNAP).

– Charging Data Request [Initial/Update] contains RAT type and user location specifics to trusted non-3GPP.

– The TNGF may send a TNGF Identities parameter to AMF inside an N2 Uplink NAS Transport message. The TNGF Identities parameter contains a list of identifiers (i.e. FQDNs or IP addresses) of N3 terminations supported by the TNGF. If received by the AMF, it shall forward it to the SMF, which may use it as input to UPF selection.

5.2.2.13.3 PDU session modification

5.2.2.13.3.1 PDU session modification via an untrusted non-3GPP access network

The following figure 5.2.2.13.3.1 describes a PDU session charging modification via an untrusted non-3GPP access network scenario based on figure 4.12.16.1 in TS 23.502 [201] description:

Figure 5.2.2.13.3.1: PDU Session modification via untrusted non-3GPP access

[2ch-a to 2ch-c]: Interaction between SMF and CHF triggered by the modification applied to the PDU session (e.g. QoS handling).

5.2.2.13.3.2 PDU session modification via Trusted Non-3GPP access network

The UE or network requested PDU Session Modification procedure via trusted non-3GPP access network is the same procedure as the one specified in clause 5.2.2.13.3.1 for untrusted non-3GPP access, with the following modifications:

– The N3IWF in Figure 5.2.2.13.3.1 should be substituted with a TNGF and the Untrusted non-3GPP access should be substituted with a Trusted non-3GPP Access Point (TNAP).

– Interaction between SMF and CHF triggered by the modification contains RAT type and user location specifics to trusted non-3GPP.

5.2.2.13.4 PDU session release

5.2.2.13.4.1 PDU session release via an untrusted non-3GPP access network

The following figure 5.2.2.13.4.1 describes a PDU session charging release via an untrusted non-3GPP access network scenario based on figure 4.12.17.1 in TS 23.502 [201] description:

Figure 5.2.2.13.4.1: PDU Session release via untrusted non-3GPP access

[3cha-3chb]. Two cases:

– In case the PDU session needs to be released, SMF interaction with CHF for release, with Charging Data Request [Termination].

– In case of handover from non-3GPP access to 3GPP access, SMF may interacts with CHF, with Charging Data Request [Update].

NOTE 1: the "radio access type change" trigger, if enabled, applied during the PDU session establishment over the 3GPP access which was performed prior to this PDU session release over non-3GPP access.

5.2.2.13.4.2 PDU session release via Trusted Non-3GPP access network

The UE or the network can release a PDU Session via a trusted non-3GPP access network as specified in clause 5.2.2.13.4.1 for the untrusted non-3GPP access with the following modifications:

– The untrusted non-3GPP access is substituted by a trusted non-3GPP access point (TNAP).

– The N3IWF is substituted by the TNGF.

5.2.2.14 PDU session served by I-SMF and SMF

5.2.2.14.1 General

When the I-SMF is inserted, re-allocated, or removed in a PDU Session as specified in TS 23.501 [200], the SMF may report the charging information to the CHF.

When the I-SMF with UL CL/BP is inserted based on information received from SMF, the I-SMF forwards traffic usage information to the SMF as specified in TS 23.501 [200].

When the V-SMF is changed for a Home Routed PDU Session as specified in TS 23.502 [201], the H-SMF may report the charging information to the H-CHF.

5.2.2.14.2 PDU session establishment with I-SMF insertion

The following figure 5.2.2.14.2.1 describes a PDU session establishment charging, for the case where the service area of the selected SMF does not include the location where the UE camps, based on TS 23.502 [201] figure 4.3.2.2.2, where the V-SMF and V-UPF are replaced by I-SMF and I-UPF, and H-SMF and H-UPF are replaced by SMF and UPF (PSA) respectively:

Figure 5.2.2.14.2.1: UE-requested PDU Session Establishment with I-SMF insertion

2. The AMF selects SMF and I-SMF upon SMF serving area cannot cover UE location.

5a. I-SMF selects one or more UPFs.

11. The SMF may perform a Session Management Policy Modification procedure to report some event to the PCF that has previously subscribed.

11ch-a. The SMF creates a Charging Id for the PDU session, and sends Charging Data Request [initial] including I-SMF information to CHF for authorization for the subscriber to start the PDU session which is triggered by start of PDU session charging event.

11ch-b. The CHF opens CDR for this PDU session.

11ch-c. The CHF acknowledges by sending Charging Data Response [Initial] to the SMF.

14. AMF to SMF: SM Request (N2 SM information).

[19a-b]. N4 session Modification.

19c, I-SMF notify SMF on N4 information with Traffic usage reporting.

19ch-a. This step may occur in case "start of service data flow" needs quota from CHF, for the SMF to request quota for both own and I-SMF usage.

19ch-b. The CHF updates CDR for this PDU session.

19ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the SMF.

NOTE 1: The steps from 19ch-a to 19ch-c for quota request from CHF are not applicable for offline only charging.

20. SM Request with PDU session Update Response to AMF.

21. SMF sends SM Context Status Notify to AMF.

22. In case of PDU Type IPv6, IPv6 Address Configuration.

NOTE 2: I-SMF controlling both I-UPF and PSA2 UPF upon local traffic offload scenarios, can enforce usage report and/or quota management for PSA2 UPF.

5.2.2.14.3 PDU Session modification procedure with I-SMF involved

The following figure 5.2.2.14.3-1 describes a PDU Session modification charging message flow, for the case where the service area of the selected SMF does not include the location where the UE camps, with simplified I-SMF with UE and Serving Network message flows , based on TS 23.502 [201] figure 4.3.3.3-1, where the V-SMF and V-UPF are replaced by I-SMF and I-UPF, and H-SMF and H-UPF are replaced by SMF and UPF (PSA) respectively:

Figure 5.2.2.14.3-1: UE or network requested PDU Session Modification charging with I-SMF involved

PDU Session served by both I-SMF and SMF has been established, with the ongoing Charging session.

1a. UE or serving network AMF requested PDU Session Modification Request to I-SMF, I-SMF invokes a Nsmf_PDUSession_Update Request message to SMF, including User Location Information, QoS information and I-SMF information. SMF accept with Nsmf_PDUSession_Update_Response message to I-SMF.

1a.ch-a. All counts are closed in SMF and a Charging Data Request [Update] message with PDU Session related triggers including I-SMF information is sent to CHF, if required by immediate report category trigger. New counts and time stamps for all active service data flows are started in the SMF.

1a.ch-b. The CHF updates CDR for this PDU session.

1a.ch-c. The CHF acknowledges by sending Charging Data Response [Update] message to the SMF.

1b~1d. With PCF initiated SM Policy Association Modification or UDM updated the subscription data or SMF decided to modify PDU Session triggers, SMF starts SMF requested PDU Session Modification procedures.

1e. (R)AN initiated PDU Session Modification Request to I-SMF, I-SMF invokes a Nsmf_PDUSession_Update Request message to SMF, including User Location Information, QoS information with indication of QoS flow released and I-SMF information. SMF accept with Nsmf_PDUSession_Update_Response message to I-SMF.

1b~1e.ch-a. All counts are closed in SMF and a Charging Data Request [Update] message with PDU Session related triggers including I-SMF information is sent to CHF, if required by immediate report category trigger. New counts and time stamps for all active service data flows are started in the SMF.

1b~1e.ch-b. The CHF updates CDR for this PDU session.

1b~1e.ch-c. The CHF acknowledges by sending Charging Data Response [Update] message to the SMF.

3. With SMF initiated QoS flows modification procedure, SMF invokes a Nsmf_PDUSession_Update Request message to I-SMF.

4~14. I-SMF interacting with UE and Serving Network message flows, including the QoS rule(s) and QoS Flow level QoS parameters operations.

15. I-SMF invokes a Nsmf_PDUSession_Update Response message to SMF, including User Location Information, QoS flow information and I-SMF information.

15.ch-a. All counts are closed in SMF and a Charging Data Request [Update] message with PDU Session related triggers including I-SMF information is sent to CHF, if required by immediate report category trigger. New counts and time stamps for all active service data flows are started in the SMF.

15.ch-b. The CHF updates CDR for this PDU session.

15.ch-c. The CHF acknowledges by sending Charging Data Response [Update] message to the SMF.

5.2.2.14.4 PDU Session release procedure with I-SMF involved

The following figure 5.2.2.14.4-1 describes a PDU session release charging message flow, for the case where the service area of the selected SMF does not include the location where the UE camps, with simplified I-SMF with UE and Serving Network message flows , based on TS 23.502 [201] figure 4.3.4.3-1, where the V-SMF and V-UPF are replaced by I-SMF and I-UPF, and H-SMF and H-UPF are replaced by SMF and UPF (PSA) respectively.

Figure 5.2.2.14.4-1: UE or network requested PDU Session release charging with I-SMF involved

PDU Session served by both I-SMF and SMF has been established, with the ongoing Charging session.

1a-14. UE initiates PDU session release procedure, finally with Nsmf_PDUSession_Update Response message sent from SMF to the inserted I-SMF.

14.ch-a. All counts are closed in SMF and a Charging Data Request [Release] message including I-SMF information is sent to CHF, with usage reporting.

14.ch-b. The CHF close CDR for this PDU session.

14.ch-c. The CHF acknowledges by sending Charging Data Response [Release] message to the SMF.

5.2.2.14.5 PDU Session procedures with I-SMF insertion/change/removal

PDU Session procedures with I-SMF insertion/change/removal, including below three figures described procedures covering Service Request, N2 based handover and Xn based handover.

The following figure 5.2.2.14.5-1 describes PDU session charging message flows, for the Service Request cases where

– the UE moves from SMF service area to new I-SMF service area, a new I-SMF is inserted (i.e. I-SMF insertion); or

– the UE moves from old I-SMF service area to new I-SMF service area, the I-SMF is changed (i.e. I-SMF change); or

– the UE moves from I-SMF service area back to SMF service area, the I-SMF is removed (i.e. I-SMF removal).

with simplified UE with 5GS message flows, based on TS 23.502 [201] figure 4.23.4.3-1, for I-SMF insertion, change, removal respectively, and specifies the corresponding charging message flow between SMF and CHF.

Figure 5.2.2.14.5-1: PDU Session charging message flows for UE Triggered Service Request procedure with I-SMF insertion/change/removal

PDU Session served by both I-SMF and SMF has been established, with the ongoing Charging session.

PDU Session message flows for UE Triggered Service Request procedure, with I-SMF insertion/change/removal triggers charging message flows as below:

– I-SMF insertion message flows, upon UE moves from SMF service area to I-SMF service area, finally with Nsmf_PDUSession_Create Response message sent from SMF to the inserted I-SMF (Detail message flows refer to TS 23.502,4.23.4.3-1 step 3 to 8c), or finally with Nsmf_PDUSession_Update Response message sent from SMF to the inserted I-SMF (Detail message flows refer to TS 23.502 [201],4.23.4.3-1 step 18 to 20c).

– I-SMF change message flows, upon UE moves from old SMF service area to new I-SMF service area, finally with Nsmf_PDUSession_Update Response message sent from SMF to the inserted new I-SMF (Detail message flows refer to TS 23.502 [201],4.23.4.3-1 step 3 to 8c, or step 18 to 20c).

– I-SMF removal message flows, upon UE moves from I-SMF service area back to SMF service area, finally SMF send Nsmf_PDUSession_CreateSMContext Response message to AMF (Detail message flows refer to TS 23.502,4.23.4.3-1 step 10 to 16), or SMF send Nsmf_PDUSession_UpdateSMContext Response message to AMF (Detail message flows refer to TS 23.502 [201], 4.23.4.3-1 step 22 to 25)

x.ch-a. All counts are closed in SMF, and a Charging Data Request [Update] message including I-SMF information and “insertion/change/removal of I-SMF” trigger is sent to CHF, if required by immediate report category trigger. New counts and time stamps for all active service data flows are started in the SMF.

x.ch-b. The CHF updates CDR for this PDU session.

x.ch-c. The CHF acknowledges by sending Charging Data Response [Update] message to the SMF.

NOTE 1: x in figure 5.2.2.14.5-1, refer to the last step number in the detail message flows. For I-SMF insertion or I-SMF change, x refers to 8c or 20c. For I-SMF removal, x refers to 16 or 25.

The following figure 5.2.2.14.5-2 describes PDU session charging message flows, for N2 based handover, with I-SMF insertion, change, removal.

Figure 5.2.2.14.5-2: PDU Session charging message flows for Inter NG-RAN node N2 based handover, execution phase, with I-SMF insertion/change/removal

PDU Session served by both I-SMF and SMF has been established, with the ongoing Charging session between SMF and CHF.

PDU Session message flows for Inter NG-RAN node N2 based handover procedure, with I-SMF insertion/change/removal triggers charging message flows as below:

– I-SMF insertion message flows, for N2 based handover, refer to TS 23.502 [201], 4.23.7.3.3-1 step 2 to 8.

– I-SMF Change message flows, for N2 based handover, refer to TS 23.502 [201], 4.23.7.3.3-1 step 2 to 8,

– I-SMF Removal message flows, for N2 based handover, refer to TS 23.502 [201], 4.23.7.3.3-1 step 10 to 14.

x.ch-a. All counts are closed in SMF with the I-SMF, and a Charging Data Request [Update] message including I-SMF information and “insertion/change/removal of I-SMF” trigger is sent to CHF, if required by immediate report category trigger. New counts and time stamps for all active service data flows are started in the SMF.

x.ch-b. The CHF updates CDR for this PDU session.

x.ch-c. The CHF acknowledges by sending Charging Data Response [Update] message to the SMF.

NOTE 2: x in figure 5.2.2.14.5-2, refer to the last step number in the detail message flows. For I-SMF insertion or I-SMF change, x refers to 8. For I-SMF removal, x refers to 14.

The following figure 5.2.2.14.5-3 describes PDU session charging message flows, for Xn based handover, with I-SMF insertion, change, removal.

Figure 5.2.2.14.5-3: PDU Session charging message flows for Xn based handover, execution phase, with I-SMFinsertion/change/removal

PDU Session served by both I-SMF and SMF has been established, with the ongoing Charging session between SMF and CHF.

PDU Session message flows for X2 based handover procedure, with I-SMF insertion/change/removal triggers charging message flows as below:

– I-SMF insertion message flows, for Xn based handover, refer to TS 23.502 [201], 4.23.11.2-1 step 1 to 9.

– I-SMF Change message flows, for Xn based handover, refer to TS 23.502 [201], 4.23.11.3-1 step 1 to 9,

– I-SMF Removal message flows, for Xn based handover, refer to TS 23.502 [201], 4.23.11.4-1 step 1 to 8.

x.ch-b. The CHF updates CDR for this PDU session.

x.ch-c. The CHF acknowledges by sending Charging Data Response [Update] message to the SMF.

NOTE 3: x in figure 5.2.2.13.5-3, refer to the last step number in the detail message flows. For I-SMF insertion or I-SMF change, x refers to 9. For I-SMF removal, x refers to 8.

5.2.2.14.6 5GS to EPS handover using N26 interface with I-SMF removal

When 5GS to EPS handover using N26 interface in idle mode, procedure in TS 23.502 [201] clause 4.23.12.2 is applicable.

When 5GS to EPS handover using N26 interface in active mode, procedure in TS 23.502 [201] clause 4.23.12.6 is applicable.

Upon UE moves from I-SMF service area to EPS service area, with both RAT Type change and I-SMF removal triggered, PGW-C+SMF and CHF will conduct below charging procedures:

x.ch-a. All counts are closed in PGW-C+SMF with a Charging Data Request [Update] message including I-SMF information and both “RAT Type change” and “removal of I-SMF” triggers are sent to CHF, if required by immediate report category trigger. New counts and time stamps for all active service data flows are started in the PGW-C+SMF.

x.ch-b. The CHF updates CDR for this PDU session.

x.ch-c. The CHF acknowledges by sending Charging Data Response [Update] message to the PGW-C+SMF.

NOTE 1: x refers to the last message step number with I-SMF removal in the detail message flows in TS 23.502 [201] clause 4.23.12.2 or clause 4.23.12.6.

5.2.2.14.7 EPS to 5GS handover using N26 interface with I-SMF insertion

When EPS to 5GS handover using N26 interface in idle mode, procedure in TS 23.502 [201] clause 4.23.12.3 is applicable.

When EPS to 5GS handover using N26 interface in active mode, procedure in TS 23.502 [201] clause 4.23.12.7 is applicable.

Upon UE moves from EPS service area to I-SMF service area, with both RAT Type change and I-SMF insertion triggered, PGW-C+SMF and CHF conduct below charging procedures:

x.ch-a. All counts are closed in PGW-C+SMF with a Charging Data Request [Update] message including I-SMF information and both “RAT Type change” and “insertion of I-SMF” triggers are sent to CHF, if required by immediate report category trigger. New counts and time stamps for all active service data flows are started in the PGW-C+SMF.

x.ch-b. The CHF updates CDR for this PDU session.

x.ch-c. The CHF acknowledges by sending Charging Data Response [Update] message to the PGW-C+SMF.

NOTE 1: x refers to the last message step number with I-SMF insertion in the detail message flows in TS 23.502 [201] clause 4.23.12.3 or clause 4.23.12.7.

5.2.2.14.8 Addition/removal/change of PSA and UL CL or BP controlled by I-SMF

This clause is based on TS 23.502 clause 4.23.9.1, 4.23.9.2 and 4.23.9.3 procedures, describes simplified procedures of addition/removal/change of PSA and UL CL or BP controlled by I-SMF, adding with charging message flow:

Figure 5.2.2.14.8-1: Addition/removal/change of PSA and UL CL or BP controlled by I-SMF

PDU Session served by both I-SMF and SMF has been established, with the ongoing Charging session.

PDU Session message flows with addition/removal/change of I-SMF controlled addition/removal/change of PSA and UL CL/BP with charging message flows as below:

– Addition of PDU Session Anchor (PSA2) for UL CL/BP controlled by I-SMF message flows, refer step 2 to step 4 described in figure 4.23.9.1-1 of TS 23.502[201].

– Removal of PDU Session Anchor (PSA2) for UL CL/BP controlled by I-SMF message flows, refer step 2 to step 9 described in figure 4.23.9.2-1 of TS 23.502[201].

– Change of PDU Session Anchor (PSA0 to PSA2) for UL CL/BP controlled by I-SMF message flows, refer step 2 to step 3 and step 4 to step 10 described in figure 4.23.9.3-1 of TS 23.502[201].

x.ch-a. All counts are closed in SMF for I-SMF controlled local PSA traffic, and a Charging Data Request [Update] message including I-SMF information and “addition/removal of UPF” trigger is sent to CHF, if required by immediate report category trigger. New counts and time stamps for all addition of PSA active service data flows are started in the SMF.

x.ch-b The CHF updates the CDR for this PDU Session.

x.ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the SMF.

NOTE 1: x in figure 5.2.2.14.8-1, refer to the last step number in the detail message flows. For addition of PDU Session Anchor (PSA2), x refers to 4. For removal of PDU Session Anchor (PSA2), x refers to 9. For addition of PDU Session Anchor (PSA2) during change of PSA2, x refers to 3.

Removal of PDU Session Anchor (PSA0) for UL CL/BP controlled by I-SMF message flows, refer step 4 to step 10 described in figure 4.23.9.3-1 of TS 23.502[201].

10.ch-a. All counts are closed in SMF for I-SMF controlled the PSA0 traffic, and a Charging Data Request [Update] message including I-SMF information and “removal of UPF” trigger is sent to CHF, if required by immediate report category trigger.

10.ch-b The CHF updates the CDR for this PDU Session.

10.ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the SMF.

NOTE 2: steps 10.ch-a to 10.ch-c are only applied in Change of PDU Session Anchor (PSA0 to PSA2) procedure.

5.2.2.14.9 Roaming Home routed PDU session – inter-PLMN V-SMF change

The following figure 5.2.2.14.9.1 describes the Home Routed PDU Session case in which the UE moves out of V-SMF service area in the serving PLMN to a new PLMN V-SMF service area, based on figure 4.23.4.3-1 of TS 23.502 [201], with I-SMF replaced by V-SMF in I-SMF change scenario:

Figure 5.2.2.14.9.1: Roaming Home routed PDU session inter-PLMN V-SMF change

0ch-a: Ongoing charging session in old VPLMN for UE served by old V-SMF, using Charging Id1.

0ch-b: Ongoing charging session for HPLMN for UE served by old V-SMF, using Charging Id1.

1-2. UE moves into a different PLMN, and the new AMF determines the new V-SMF based on service area.

3- 4b. SM Context retrieval by new V-SMF from the old V-SMF. The Charging Id containing Charging Id1 value is conveyed to the new V-SMF.

4ch-a. The UE is identified as a roamer, the CHF is selected accordingly.

4ch-b. A Charging Data Request [Initial] is sent to new V-CHF, indicating "in-bound roamer", with charging Id = Charging Id1 received on step 4b.

4ch-c. The new V-CHF opens a CDR (indicating "in-bound roamer").

4ch-d. The new V-CHF acknowledges by sending Charging Data Response [Initial] to new V-SMF and optionally supplies a "Roaming Charging Profile" to new V-SMF which overrides the default one.

5-7c. Refer steps 5 to 7c in Figure 4.23.4.3-1 of TS 23.502 [201].

7ch-a. A Charging Data Request [Termination] is sent to old V-CHF, with charging Id = Charging Id1.

7ch-c. The old V-CHF closes the CDR.

7ch-d. The old V-CHF acknowledges by sending Charging Data Response [Initial] to old V-SMF.

8a. Nsmf_PDUSession_Update Request from new V-SMF towards the H-SMF with the "Roaming Charging Profile".

8ach-a. A Charging Data Request [Update] is sent to H-CHF in HPLMN, indicating the V-SMF change and "Roaming Charging Profile" received from the VPLMN.

8ach-b. The H-CHF in HPLMN updates the CDR.

8ach-c. The H-CHF in HPLMN acknowledges by sending Charging Data Response [Update] to the H-SMF and supplies the HPLMN selected "Roaming Charging Profile" for this VPLMN.

8c. Nsmf_PDUSession_Update Response from H-SMF to new V-SMF with the "Roaming Charging Profile".

8cch-a. A Charging Data Request [Update] is sent to V-CHF with charging information received from H-SMF, which includes the HPLMN selected "Roaming Charging Profile".

8cch-b. The V-CHF updates the CDR.

8cch-c. The V-CHF acknowledges by sending Charging Data Response [Update] to the V-SMF.

9, 17-21. Refer steps 9 and 17 to 21 in Figure 4.23.4.3-1 of TS 23.502 [201].

5.2.2.14.10 Roaming Home routed PDU session – intra-PLMN V-SMF change

The following figure 5.2.2.14.10.1 describes the Home Routed PDU Session case in which the UE moves out of V-SMF service area in the serving PLMN to a new V-SMF service area in the serving PLMN, based on figure 4.23.4.3-1 of TS 23.502 [201], with I-SMF replaced by V-SMF in I-SMF change scenario:

Figure 5.2.2.14.10.1: Roaming Home routed PDU session intra-PLMN V-SMF change

0ch-a and 0ch-b: same as in Figure 5.2.2.14.10.1

1-2. UE moves out of the old V-SMF service area, and the new AMF determines the new V-SMF service area in the same VPLMN.

3- 4b. SM Context retrieval by new V-SMF from the old V-SMF. The Charging Id containing Charging Id1 value, the "Home Roaming Charging Profile", and the V-CHF address, are conveyed to the new V-SMF.

4ch-a. A Charging Data Request [Initial] is sent to V-CHF, indicating "in-bound roamer", with charging Id (i.e. Charging Id1) received on step 4b.

NOTE: Since the same V-CHF is used, the Home Roaming Charging Profile to be used is already known by the V-CHF

4ch-b. The V-CHF opens a CDR (indicating "in-bound roamer").

4ch-c. The V-CHF acknowledges by sending Charging Data Response [Initial] to new V-SMF.

4ch-d. A Charging Data Request [Termination] is sent to V-CHF, with charging Id (i.e. Charging Id1).

4ch-e. The V-CHF closes the CDR.

4ch-f. The V-CHF acknowledges by sending Charging Data Response [Termination] to old V-SMF.

5-21. Same steps as in Figure 5.2.2.14.10.1, except the "Roaming Charging Profile" is not renegotiated, i.e.not contained in steps 8a, 8ach-a, 8ach-c, 8c and 8cch-a.

5.2.2.15 PDU session charging from SMF – ATSSS

5.2.2.15.1 General

This clause specifies PDU session charging for a MA PDU session as defined in TS 23.501 [200].

The flows are based on message flows specified in clause 4.22 TS 23.502 [201],

5.2.2.15.2 UE requested MA PDU session establishment

The following figure 5.2.2.15.2.1 describes charging procedure for MA PDU Session establishment requested by UE, based on figure 5.2.2.2.2.1 description with the following differences identified in clause 4.22.2.1 TS 23.502 [202]:

Figure 5.2.2.15.2.1: UE Requested MA PDU session establishment

– The UE is registered in both 3GPP access and non-3GPP access, and UE PDU Session Establishment Request message is sent over the 3GPP access.

1. PDU Session Establishment Request is indicated with "MA PDU Request" and ATSSS Capability (e.g. an "MPTCP Capability" and/or an "ATSSS-LL Capability").

2-3. The AMF informs the SMF that the request is for a MA PDU Session and indicates the UE is registered over both accesses.

7a-b. PCC Rules supplied by PCF contain ATSSS policy control information, optionally with a dedicated non-3GPP access rating group. From these PCC Rules, the SMF derives ATSSS rules for uplink and N4 rules for downlink for controlling the traffic steering, switching and splitting.

9ch-a. The SMF sends Charging Data Request [initial] indicating "MA PDU session requested by UE" to CHF for authorization for the subscriber to start the MA PDU session.

9ch-b. The CHF opens CDR for this MA PDU session.

9ch-c. The CHF acknowledges by sending Charging Data Response [Initial] to the SMF.

10-13. Procedure based on ATSSS policy and SMF derived both N4 Rules and ATSSS rules to UE.

16ch-a. This step may occur in case "start of service data flow" over 3GPP needs quota from CHF for appropriate rating group, the SMF sends Charging Data Request [Update] for requesting quota.

16ch-b. The CHF updates CDR for this MA PDU session.

16ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the SMF.

After step 18 in figure 5.2.2.2.2.1, if the SMF was informed in step 2 that the UE is registered over both accesses, the SMF initiates the establishment of user-plane resources over non-3GPP access via AMF. After the user plane is established with the non-3GPP access:

Xch-a. The SMF sends Charging Data Request [Update]. This step may occur in case following chargeable events need quota from CHF for appropriate rating group, or if required by "immediate reporting" category:

– "start of SDF additional access" over non-3GPP.

– "start of service data flow" over non-3GPP or 3GPP.

Xch-b. The CHF updates CDR for this MA PDU session.

Xch-c. The CHF acknowledges by sending Charging Data Response [Update] to the SMF.

In the scenario where the PDU Session Establishment Request message for the MA PDU session is sent over the non-3GPP access, and the user plane over the non-3GPP access is established before the user plane over 3GPP:

16ch-a. This step may occur in case "start of service data flow" over non-3GPP needs quota from CHF for appropriate rating group, or if required by "immediate reporting" category

Xch-a. This step may occur in case following chargeable events need quota from CHF for appropriate rating group, or if required by "immediate reporting" category:

– "start of SDF additional access" over 3GPP.

– "start of service data flow" over non-3GPP or 3GPP.

5.2.2.15.3 UE requested PDU session establishment with Network Modification to MA PDU Session

The following flow describes the charging procedure for a single access PDU session establishment by ATSSS-capable UE and the 5GC network decides to convert to a Multi-Access PDU (MA PDU) Session, based on figure 5.2.2.2.2.1 description with the following differences identified in clause 4.22.3 TS 23.502 [202]:

– The UE is registered in both 3GPP access and non-3GPP access and sends a PDU Session Establishment Request message over the 3GPP access.

1. PDU Session Establishment Request may include "MA PDU Network-Upgrade Allowed" indication and its ATSSS Capability.7. The single-access PDU Session requested by the UE is converted into a MA PDU Session by SMF based on "MA PDU Network-Upgrade Allowed" indication, and PCC Rules are supplied by PCF containing ATSSS policy control information optionally with a dedicated non-3GPP access rating group.

9ch-a. The SMF sends Charging Data Request [initial] indicating "MA PDU session requested by Network modification" to CHF.

9ch-b. The CHF opens CDR for this MA PDU session.

9ch-c. The CHF acknowledges by sending Charging Data Response [Initial] to the SMF.

Steps after step 10 in clause 5.2.2.15.2 apply.

5.2.2.15.4 UE Requested PDU Session Establishment with Network Modification to MA PDU Session – roaming in Home routed scenario

The charging procedure for single access PDU session establishment requested by ATSSS-capable UE and converted to a Multi-Access PDU (MA PDU) Session by the 5GC network in roaming Home routed scenario, is based on figures in clause 5.2.2.15.X. and description in clause 4.22.3 TS 23.502 [202].

5.2.2.15.4.1 UE registered to the same VPLMN over 3GPP access and non-3GPP access

The charging procedure for UE registered to the same VPLMN over 3GPP access and non-3GPP access is based on figure 5.2.2.15.X.1.1 with differences identified in clause 4.22.3 TS 23.502 [202]:

– The UE is registered to the same VPLMN over 3GPP access and non-3GPP access, and UE PDU Session Establishment Request message is sent over the 3GPP access.

1-3a. UE PDU Session Establishment Request may include "MA PDU Network-Upgrade Allowed" indication and its ATSSS Capability. This indication may be conveyed by AMF to V-SMF.

6. The V-SMF provides the "MA PDU Network-Upgrade Allowed" indication to H-SMF, if received from AMF together with an indication whether the UE is registered over both accesses.

9a-b. The single-access PDU Session received by H-SMF with "MA PDU Network-Upgrade Allowed" indication is converted into a MA PDU Session. PCC Rules are supplied by PCF containing ATSSS policy control information optionally with a non-3GPP access dedicated rating group.

11ch-a to c. Same steps as in figure 5.2.2.12.2.1 with Charging Data Request [Initial] indicating "MA PDU session requested by the Network".

5.2.2.15.5 UE requested MA PDU session establishment – roaming in Home routed scenario

5.2.2.15.5.1 General

The charging procedure for MA PDU Session establishment requested by UE in roaming Home routed scenario is based on figure 5.2.2.12.2.1 and description in clause 4.22.2.2 TS 23.502 [202].

5.2.2.15.5.2 UE registered to the same VPLMN over 3GPP access and non-3GPP access

The following figure 5.2.2.15.5.2.1 describes charging procedure for MA PDU session charging establishment requested by UE in roaming Home routed scenario for UE registered to the same VPLMN over 3GPP access and non-3GPP access:

Figure 5.2.2.15.5.2.1: UE requested MA PDU session – Roaming Home Routed – same VPLMN

– The UE is registered to the same VPLMN over 3GPP access and non-3GPP access, and UE PDU Session Establishment Request message is sent over the 3GPP access.

1-3a. UE initiates a new PDU session indicated with "MA PDU Request" and ATSSS Capability. Selection by the AMF of V-SMF which supports MA PDU sessions. The AMF indicates to V-SMF that the UE is registered over both accesses

3ch-a to 3ch-d. Same steps as in figure 5.2.2.12.2.1.

6. The V-SMF informs the H-SMF that the request is for a MA PDU Session and the UE is registered over both accesses.

9a-b. PCC rules are supplied by H-PCF containing MA PDU session control information based on currently used list of Access Type(s) and RAT Type(s). The H-SMF initiates the establishment of user-plane resources over non-3GPP access and derives the ATSSS rules for the UE and the N4 rules for the H-UPF.

11ch-a to c. Same steps as in figure 5.2.2.12.2.1 with Charging Data Request [Initial] indicating "MA PDU session requested by UE".

12ch. Counts per QFI are started for both 3GPP and non-3GPP accesses.

13. Nsmf_PDUSession_Create Response from H-SMF to V-SMF with "MA PDU session Accepted" indication.

13ch-a to c. Same steps as in figure 5.2.2.12.2.1. Counts per QFI are started for both 3GPP and non-3GPP accesses.

14-19b. Procedure in the VPLMN for 3GPP access and based on H-SMF derived ATSSS rules to UE for the MA PDU session.

Xch-a. The H-SMF sends Charging Data Request [Update]. This step may occur in case "start of service data flow" chargeable event over 3GPP, when required by "immediate reporting" category.

Xch-b. The H-CHF updates CDR for this MA PDU session.

Xch-c. The H-CHF acknowledges by sending Charging Data Response [Update] to the V-SMF.

After the user plane resources are established over non-3GPP access in VPLMN, and traffic goes through between VPLMN and HPLMN over non-3GPP access:

Ych-a. The H-SMF sends Charging Data Request [Update] to H-CHF. This step may occur in case "start of service data flow " chargeable event over non-3GPP, when required by "immediate reporting" category.

Ych-b. The H-CHF updates CDR for this MA PDU session.

Ych-c. The H-CHF acknowledges by sending Charging Data Response [Update] to the V-SMF.

5.2.2.15.6 EPS interworking

5.2.2.15.6.1 5GS to EPS handover using N26 interface

The charging procedure for MA PDU Session 5GS to EPS handover using N26 interface scenario is based on figure 5.2.2.11.2.1 description with the differences identified in clause 4.22.6.2.1 TS 23.502 [202]:

0ch. A charging session between the PGW-C+SMF and CHF exists for the MA PDU Session with multiple QoS Flows over 3GPP access and non-3GPP access.

16ch-a. MA PDU session moved to EPS: All counts affected by the MA PDU session move to EPS are closed and a Charging Data Request [Update] is sent to CHF, if required by "RAT type change" trigger. New counts and time stamps for all active service data flows are started in the PGW-C+SMF.

MA PDU Session Release procedure over non-3GPP access triggered by PGW-C+SMF: All counts affected by the release of non-3GPP access are closed by "Termination of service data flow" trigger.

5.2.2.15.6.2 5GS to EPS mobility without N26 interface

The charging procedure for MA PDU Session 5GS to EPS mobility without using N26 interface scenario is based on figure 5.2.2.11.6.1 description with the differences identified in clause 4.22.6.2.5 TS 23.502 [202]:

0. UE is registered in 5GS and MA PDU Session is over both 3GPP and non-3GPP accesses.

10. E-UTRAN Initial attach procedure:

10ch-a. MA PDU Session is moved to EPS: All counts affected by the MA PDU session move to EPS are closed and a Charging Data Request [Update] is sent to CHF, if required by "Handover start" trigger. New counts and time stamps for all active service data flows are started in the PGW-C+SMF

10ch-b. The CHF updates CDR for this PDU session.

10ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+SMF.

The PGW-C + SMF triggers the MA PDU Session Release procedure over non-3GPP access: All counts affected by the release of non-3GPP access are closed by "Termination of service data flow" trigger.

14. The PGW-C+SMF initiates release of the 5GS MA PDU Session(s) transferred to EPS.

5.2.2.15.7 Hybrid Access with Multi-Access PDU Session connectivity over NG-RAN and W-5GAN

The following flow describes the charging procedure for MA PDU Session establishment over NG-RAN and W-5GAN requested by 5G-RG, based on figure 5.2.2.15.2.1 description with the following differences identified in clause 4.12.2 TS 23.316 [203]:

– The UE is replaced by 5G-RG.

– Non-3GPP access(es) is specifically referred to wireline access.

When PDU Session Establishment Request message is sent over the 3GPP access (i.e. NG-RAN), or sent over the non-3GPP access (i.e. W-5GAN):

9ch-a. The SMF sends Charging Data Request [initial] to CHF for authorization for the 5G-RG to start the MA PDU session.

9ch-b. The CHF opens CDR for this MA PDU session.

9ch-c. The CHF acknowledges by sending Charging Data Response [Initial] to the SMF.

5.2.2.15.8 Hybrid Access with multi-access connectivity over E-UTRAN/EPC and W-5GAN

The following flow describes the charging procedure for MA PDU Session establishment over E-UTRAN/EPC and W-5GAN requested by 5G-RG using EPC interworking procedures, based on clause 4.12.3 TS 23.316 [203]:

Figure 5.2.2.15.8.1: MA PDU session establishment requested by 5G-RG via EPC

– The 5G-RG is registered in EPC.

1. 5G-RG initiates PDN Connection establishment via E-UTRAN, indicating the PDN Connection is requested to be associated with a MA PDU Session and its "ATSSS-LL Capability".

2. Create session request in EPC to the selected PGW-C+SMF with the indication the PDN Connection is requested to be associated with a MA PDU Session.

2ch-a. The PGW-C+ SMF sends Charging Data Request [initial] indicating "MA PDU session requested" to CHF for authorization for the 5G-RG to use the PDN connection for a MA PDU session.

2ch-b. The CHF opens CDR for this PDN connection.

2ch-c. The CHF acknowledges by sending Charging Data Response [Initial] to the PGW-C+ SMF.

3. Create session response indicating the request for using the PDN Connection for MA-PDU Session is accepted.

4-5. User Plane resources establishment for E-UTRAN

5ch-a. This step may occur in case "start of service data flow" over 3GPP needs quota from CHF for appropriate rating group, the PGW-C+ SMF sends Charging Data Request [Update] for requesting quota.

5ch-b. The CHF updates CDR for this PDN connection.

5ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+ SMF.

6. PDN connection establishment continuation

7. 5G-RG sends a PDU Session Establishment Request indicating "MA PDU Request" to establish W-5GAN user-plane resources.

When the user plane is established with W-5GAN (X corresponds to step 16a-b of figure 5.2.2.2.2.1 for the W-5GAN):

Xch-a. The PGW-C+ SMF sends Charging Data Request [Update]. This step may occur if required by "addition of access" trigger.

Xch-b. The CHF updates CDR for this MA PDU session.

Xch-c. The CHF acknowledges by sending Charging Data Response [Update] to the SMF.

After the user plane is established:

Ych-a. The PGW-C+ SMF sends Charging Data Request [Update]. This step may occur in case "start of service data flow" chargeable event needs quota from CHF for appropriate rating group, or if required by "immediate reporting" category.

Ych-b. The CHF updates CDR for this MA PDU session.

Ych-c. The CHF acknowledges by sending Charging Data Response [Update] to the PGW-C+ SMF.

In the scenario where the MA PDU Session is requested via 5GC/W-5GAN, the 5G-RG is registered to EPC and user-plane resources are added on 3GPP access over EPC, the following applies:

MA PDU session establishment via 5GC/W-5GAN per figure 5.2.2.15.2.1 until step 18 with PDU Session Establishment Request message for the MA PDU session sent over W-5GAN (i.e. non-3GPP access).

After step 18 of figure 5.2.2.2.2.1, the 5G-RG sends a PDN Connection Establishment Request via E-UTRAN, indicating "handover" and "MA PDU Request".

When the user plane is established with E-UTRAN over EPC:

Xch-a. The PGW-C+ SMF sends Charging Data Request [Update]. This step may occur if required by "addition of access" trigger.

After the user plane is established with E-UTRAN over EPC:

Ych-a. This step may occur in case "start of service data flow" chargeable event needs quota from CHF for appropriate rating group, or if required by "immediate reporting" category.

5.2.2.16 PDU session charging – wireline access

5.2.2.16.1 General

After registration management procedures to 5GC via wireline access network, a PDU session can be established via this wireline access, as specified in TS 23.316 [203] for different scenarios:

– 5G-RG connected via NR-RAN and W-5GAN;

– FN-RG connected via W-5GAN.

5.2.2.16.2 5G-RG Requested PDU Session Establishment via W-5GAN

The following figure 5.2.2.16.2.1 describes charging when 5G-RG requests a PDU session establishment via W-AGF.

1) The 5G-RG connects to a W-5GAN and the W-AGF sends an EAP-Request/5G-Start packet over the W-CP connection as described in clause 7.3.1.1 in TS 23.316 [203].

2) The steps are specified as step 2-7 in clause 4.3.2.1 of TS 23.502 [202].

3ch-a. The SMF creates a Charging Id for the PDU session, and sends Charging Data Request [Initial] to CHF for authorization for the subscriber information via wireline network to start the PDU session which is triggered by start of PDU session charging event.

3ch-b. The CHF opens CDR for this PDU session.

3ch-c. The CHF acknowledges by sending Charging Data Response [Initial] to the SMF.

4) The steps of PDU session establishment are specified in clause 7.3.1.1 of TS 23.316 [203].

5.2.2.16.3 FN-RG related PDU Session Establishment via W-5GAN

The following figure 5.2.2.16.3.1 describes charging when FN-RG requests a PDU session establishment via W-AGF. As described in clause 7.3.4 in TS 23.316 [203], after the registration procedure is completed, the W-AGF may establish PDU session(s) on behalf of the FN-RG.

Figure 5.2.2.16.3.1: charging when FN-RG requests a PDU session establishment via W-AGF

1) After the registration procedure is completed, the W-AGF may establish PDU session(s) on behalf of the FN-RG as described in clause 7.3.4 in TS 23.316 [203].

2) The steps are specified as step 2-9 in clause 4.3.2.2.1 of TS 23.502 [202].

3ch-a. The SMF creates a Charging Id for the PDU session, and sends Charging Data Request [Initial] to CHF for authorization for the subscriber identified under wireline network to start the PDU session which is triggered by start of PDU session charging event.

3ch-b. The CHF opens CDR for this PDU session.

3ch-c. The CHF acknowledges by sending Charging Data Response [Initial] to the SMF.

4) The steps of PDU session establishment are specified in clause 7.3.4 of TS 23.316 [203].

5.2.2.16.4 Handover procedure

5.2.2.16.4.1 5G RG handover of a PDU Session procedure from W-5GAN access to 3GPP access

Following figure 5.2.2.16.4.1.1 describes charging when 5G-RG handover of a PDU Session procedure from W-5GAN access to 3GPP access.

Figure 5.2.2.16.4.1.1: Handover of PDU session from W-5GAN access to 3GPP access

As described in clause 7.6.2.1 in TS 23.316 [203], the handover of a PDU session from W-5GAN access to 3GPP access is as following.

1-2) The steps are described in clause 7.6.2.1 in TS 23.316 [203], 5G-RG peforms registeration via 3GPP access and PDU session establishmeng procedure.

2ch-a-c. SMF may interact with CHF with Charging Data Request [Update].This step occurs in case "RAT type change" triggers, if required by "immediate reporting" category. The RAT type change trigger, if enabled, applied during the PDU session establishment via the 3GPP access network before SMF executes the release of W-5GAN access resource. Which RAT type used is described in clause 5.3.2.3 of TS 23.501 [200].

NOTE: Void

3. The step that the SMF executes the release of resources in W-5GAN access is same as step 3 as described in clause 7.6.3.1 of TS 23.316 [203].

5.2.2.16.4.2 5G RG handover of a PDU Session procedure from 3GPP to W-5GAN access

Following figure 5.2.2.16.4.2.1 describes charging when 5G-RG handover of a PDU Session procedure from 3GPP to W-5GAN access.

Figure 5.2.2.16.4.2.1: Handover of a PDU Session procedure from 3GPP to W-5GAN access

As described in clause 7.6.3.2 in TS 23.316 [203], the handover of a PDU session from 3GPP access to W-5GAN access is as following.

1) The 5G-RG initiates Reigistration procedure via W-5GAN as defined in clause 7.2.1.1 of TS 23.316 [203].

2) The 5G-RG performs PDU Session Establishment procedure via W-5GAN access as described in 7.6.3.2 of TS 23.316 [203].

2ch-a-c. SMF may interact with CHF with Charging Data Request [Update]. This step occurs in case "RAT type change" triggers, if required by "immediate reporting" category The RAT type change trigger, if enabled, applied during the PDU session establishment via the W-5GAN before SMF performs the release of 3GPP access resource. Which RAT type used is described in clause 5.3.2.3 of TS 23.501 [200].

NOTE: Void

3) The step that the SMF executes the release of resource via 3GPP access is same as step 3 as described in clause 7.6.3.2 of TS 23.316 [203].

5.2.2.17 Ultra Reliable Low Latency Communication (URLLC)

5.2.2.17.1 General

Support highly reliable URLLC services is specified in TS 23.501 [200] clause 5.33 procedures and TS 23.502 [201] message flows for different scenarios:

– Dual Connectivity based end to end Redundant User Plane Paths.

– Support of redundant transmission on N3/N9 interfaces.

– Support for redundant transmission at transport layer.

5.2.2.17.2 Void

5.2.2.17.3 Redundant transmission for high reliability communication

5.2.2.17.3.1 PDU Session establishment

– Dual Connectivity based end to end Redundant User Plane Paths

The charging message flow of PDU session establishment for supporting Dual Connectivity based end to end Redundant User Plane Paths, is based on Figure 5.2.2.2.2-1 description with the differences identified in clause 4.3.2.2.1.1 TS 23.502 [202].

In the Step 9ch-a, if the PDU Session requires redundancy, SMF sends the Charging Data Request [Initial] with the redundant transmission information.

If the PDU session establishment without redundancy handling based on local policy, SMF sends the Charging Data Request [Initial] as descriped in Figure 5.2.2.2.2-1. CHF considers the PDU session is used for the non-redundant transmission.

– Redundant transmission on N3/N9 interfaces

The charging message flow of PDU session establishment for supporting redundant transmission on N3/N9 interfaces, is based on Figure 5.2.2.2.2-1 description with the differences identified in clause 4.3.2.2.1.1 TS 23.502 [202].

As described in clause 5.33.1.2 of TS 23.501 [201], SMF decides to perform redundant transmission for one or more QoS Flows at the step 10.

In the Step 16ch-a，the SMF sends the Charging Data Request [Update] with the redundant transmission information.

– Redundant transmission at transport layer

The charging message flow of PDU session establishment for supporting redundant transmission at transport layer, is based on Figure 5.2.2.2.2-1 description with the differences identified in clause 4.3.2.2.1.1 TS 23.502 [202].

As per the clause 5.33.2.3 TS 23.501[201], the knowledge of supporting redundant transmission at transport layer can be configured in the SMF, or be configured in UPF and then obtained by the SMF via N4 capability negotiation during N4 Association setup procedure.

In the Step 16ch-a, SMF sends the Charging Data Request [Update] with the redundant transmission information.

5.2.2.17.3.2 PDU Session Modification

For redundant transmission on N3/N9 interfaces, the charging message flow of PDU session modification is based on Figure 5.2.2.2.3-1 description with the differences identified in clause 4.3.3.2 TS 23.502 [202].

2ch-a. If redundant transmission has not been activated to the PDU session and the SMF performs redundant transmission for the QoS Flow in step 2a, the SMF sends Charging Data Request [Update] to the CHF for the PDU session, with the trigger "Redundant transmission change".

If redundant transmission has been activated on the PDU Session, and the SMF stops redundant transmission in step 2a, the SMF sends Charging Data Request [Update] to the CHF for the PDU session, with the trigger "Redundant transmission change".

2ch-b. The CHF update the CDR for the URLLC.

2ch-c. The CHF acknowledges by sending Charging Data Response [Update] to the SMF.

5.2.2.17.3.3 PDU Session Release

For redundant transmission on N3/N9 interfaces, the charging message flow of PDU session release is based on Figure 5.2.2.2.4-1 description with the differences identified in clause 4.3.4.2 TS 23.502 [202].

2ch-a. The SMF sends Charging Data Request [Termination] to the CHF for terminating the charging associated with PDU session in each UPF, with the trigger "End of PDU session".

2ch-b. The CHF closes the CDR for the URLLC.

2ch-c. The CHF acknowledges by sending Charging Data Response [Termination] to the SMF.

5.2.2.18 PDU session charging for roaming in Local breakout scenario

5.2.2.18.1 General

The clause below describes PDU session charging in roaming with local breakout scenarios.

5.2.2.18.2 PDU session establishment

The following figure 5.2.2.18.2-1 describes a PDU session establishment charging, based on figure 4.3.2.2.1-1 UE-requested PDU Session Establishment for non-roaming and roaming with local breakout TS 23.502 [202] description:

Figure 5.2.2.18.2-1: PDU session establishment

9ch-a. The UE is identified as a roamer (e.g., PLMN ID of the received SUPI is different from VPLMN PLMN ID), the V-CHF and optionally H-CHF are selected accordingly.

9ch-b1. The Charging Data Request [Initial] is sent to V-CHF, for the subscriber triggered by start of PDU session charging event.

9ch-c1. The V-CHF opens a CDR.

9ch-d1. The V-CHF acknowledges by sending Charging Data Response [Initial] to the V-SMF and optionally supplies a "Roaming Charging Profile" to the V-SMF (which overrides the default one).

9ch-b2. If a H-CHF was selected a Charging Data Request [Initial] is sent to H-CHF, with charging id, and with or without quota management and optionally including the "Roaming Charging Profile".

9ch-c2. The H-CHF opens a CDR.

9ch-d2. The H-CHF acknowledges by sending Charging Data Response [Initial] to the V-SMF and optionally supplies a "Roaming Charging Profile" to the V-SMF.

10ch-a1. The Charging Data Request [Update] is sent to V-CHF with QBC and/or FBC information, when enabled triggers are met, optionally including the new "Roaming Charging Profile"..

10ch-b1. The V-CHF update the CDR.

10ch-c1. The V-CHF acknowledges by sending Charging Data Response [Update] to the V-SMF.

10ch-a2. If a H-CHF was selected a Charging Data Request [Update] is sent to H-CHF with QBC and/or FBC information, when enabled triggers are met, for FBC it may include a request for quota.

10ch-b2. The H-CHF update the CDR.

10ch-c2. The H-CHF acknowledges by sending Charging Data Response [Update] to the V-SMF.

5.2.2.18.3 PDU Session Modification

The following figure 5.2.2.18.3-1 describes the PDU session modification charging, based on figure 4.3.3.2-1 UE or network requested PDU Session Modification (for non-roaming and roaming with local breakout) TS 23.502 [202] description:

Figure 5.2.2.18.3-1: PDU Session Modification

2ch-a1. The Charging Data Request [Update] is sent to V-CHF for reporting the QBC and/or FBC information when enabled triggers are met.

2ch-b1. The V-CHF update the CDR.

2ch-c1. The V-CHF acknowledges by sending Charging Data Response [Update] to the V-SMF.

2ch-a2. If a H-CHF was selected a Charging Data Request [Update] is sent to H-CHF with QBC and/or FBC information, when the enabled triggers are met, and for FBC it may include a request for quota.

2ch-b2. The H-CHF update a CDR.

2ch-c2. The H-CHF acknowledges by sending Charging Data Response [Update] to the V-SMF.

5.2.2.18.4 PDU Session Release

The following figure 5.2.2.18.4-1 describes the PDU session release charging, based on figure 4.3.4.2-1 UE or network requested PDU Session Release for non-roaming and roaming with local breakout TS 23.502 [202] description:

Figure 5.2.2.18.4-1: PDU Session Release

2ch-a1. The Charging Data Request [Termination] is sent to V-CHF.

2ch-b1. The V-CHF close the CDR.

2ch-c1. The V-CHF acknowledges by sending Charging Data Response [Termination] to the V-SMF.

2ch-a2. If a H-CHF was selected a Charging Data Request [Termination] is sent to H-CHF.

2ch-b2. The H-CHF close the CDR.

2ch-c2. The H-CHF acknowledges by sending Charging Data Response [Termination] to the V-SMF.

5.2.2.19 PDU session charging for additional actor (MVNO)

5.2.2.19.1 General

The clause below describes PDU session charging for additional actor (MVNO) which is only applicable for non-roaming case.

5.2.2.19.2 Additional actor (MVNO)

The clause contains the description for the scenario of MVNO as additional actor with A-CHF.

For non-roaming scenarios, the message flows for the PDU session establishment, PDU session Modification and PDU session Release for LBO charging specified in clause 5.2.2.18 could be applicable depending on the deployment scenarios for additional actor (MVNO), with the following differences:

– V-SMF in V-PLMN is replaced by the SMF in MNO;

– V-CHF in V-PLMN is replaced by the CHF in MNO;

– H-CHF in H-PLMN is replaced by the A-CHF in MVNO.