7.2 Connection, Registration and Mobility Management procedures

23.3163GPPRelease 18TSWireless and wireline convergence access support for the 5G System (5GS)

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

The listed parameters in the procedures are not exhaustive, but more parameters can be used as described in the protocol specifications.

Where parameters have not been described, the meaning of the parameter is the same as for 3GPP access as described in TS 23.502 [3], TS 24.501 [22], TS 38.413 [23].

7.2.1 Registration Management procedures

This clause specifies delta for Registration Management procedure defined in TS 23.502 [3] clause 4.2 for 5G-RG and FN-RG.

7.2.1.1 5G-RG Registration via W-5GAN

The 5G-RG registration management procedures are followed for both W-5GBAN and W-5GCAN.

Clause 7.2.1.1 specifies how a 5G-RG can register to 5GC via aW-5GAN. It is based on the Registration procedure specified in TS 23.502 [3] clause 4.2.2.2.2. The NAS protocol is transported between 5G-RG and W-AGF as documented in BBF TR‑456 issue 2 [43] and CableLabs WR‑TR‑5WWC‑ARCH [27]. If the 5G-RG needs to be authenticated, mutual authentication is executed between the 5G-RG and AUSF. The details of the authentication procedure are specified in TS 33.501 [11]. In Registration and subsequent Registration procedures via W-5GAN access, the NAS messages are always exchanged between the 5G-RG and the AMF. When possible, the 5G-RG can be authenticated by reusing the existing UE security context in AMF for the 5G-RG.

Figure 7.2.1.1-1 only shows authentication flow using EAP-AKA’ (specifically in step 6c, step 7a and step 7b) but other methods are possible: Authentication procedures that 5G-RG and the 5GC shall support, are specified in TS 33.501 [11]. Specific EAP authentication methods (see TS 33.501 [11]) for 5G-CRG with non-3GPP identities and credentials may be used for isolated network (see TS 33.501 [11]).

Figure 7.2.1.1-1: 5G-RG Registration via W-5GAN

1. The 5G-RG connects to a W-5GAN with procedures outside the scope of 3GPP and creates an initial signalling connection using W-CP protocol stack. This connection shall support transfer of AS parameters and NAS messages between 5G-RG and W-AGF.

2. Void.

3. The 5G-RG using W-CP protocol stack sends a message that contains the Access Network parameters (GUAMI if available, the selected PLMN, Requested NSSAI and Establishment Cause) and a NAS Registration Request message (SUCI or 5G-GUTI as defined in TS 24.501 [22], security parameters/UE security capability, NSSAI parameters, UE MM Core Network Capability, PDU session status, Follow-on request). The Establishment cause provides the reason for requesting a signalling connection with 5GC.

NOTE 1: While PLMN selection is not supported for W-5GAN access, the 5G RG provides a selected PLMN ID in Access Network parameters sent to the W-AGF. In this version of the specifications, this selected PLMN ID is the home domain of the SUCI. This information is transparently transferred from 5G RG to AUSF via the W-AGF and the AMF; it ensures the AUSF and the 5G RG consider the same information for Key derivations defined in TS 33.501 [11].

NOTE 2: The steps from 1 to 3 depend on BBF decision for what protocols to use for NAS transport. The step needs to be revised based on their decision.

4. The W-AGF shall select an AMF based on the received AN parameters and local policy, as specified in clause 6.3.5 of TS 23.501 [2]. The W-AGF shall then forward the Registration Request received from the UE to the selected AMF within an N2 initial UE message (NAS message, ULI, Establishment cause, UE context request, selected PLMN ID).

5. The selected AMF may decide to request the SUCI by sending a N2 Downlink NAS transport message (NAS Identity Request) message to W-AGF. This NAS message and the response are sent between W-AGF and 5G-RG as described in BBF TR-456 [43] and CableLabs WR‑TR‑5WWC‑ARCH [27]. In this case the RG shall answer with a NAS Identity response.

6. The AMF may decide to authenticate the 5G-RG by invoking an AUSF. In this case, the AMF shall select an AUSF as specified in TS 23.501 [2] clause 6.3.4 based on SUPI or SUCI. As defined in 33.501 [11], the AMF transfers the SUCI and the selected PLMN ID to the AUSF.

The AUSF executes the authentication of the UE as specified in TS 33.501 [11]. The AUSF selects a UDM as described in clause 6.3.8 of TS 23.501 [2] and gets the authentication data from UDM. The authentication packets are encapsulated within NAS authentication messages. Between W-AGF and AMF, the messages are encapsulated within N2 downlink/uplink NAS transport messages. After the successful authentication the AUSF provides relevant security related information to the AMF. If the AMF provided a SUCI to AUSF, the AUSF shall return the SUPI to AMF only after the authentication is successful.

The AMF decides if the Registration Request needs to be rerouted as described in clause TS 23.502 [3] clause 4.2.2.2.3, where the initial AMF refers to the AMF.

7a. If NAS security context does not exist, the NAS security initiation is performed as described in TS 33.501 [11]: the AMF initiates NAS Security Mode command. If the 5G-RG had no NAS security context in step 1, the UE includes the full Registration Request message as defined in TS 24.501 [22]. If an EAP-AKA’ authentication was successfully executed in step 6, the AMF shall encapsulate the EAP-Success received from AUSF within the NAS Security Mode Command message. The message is encapsulated within a N2 downlink NAS transport message.

The AMF initiates a NGAP/N2 procedure to provide the 5G-AN with security context as specified in TS 38.413 [23].

7b. The W-AGF shall forward the NAS Security Mode Command message to 5G-RG.

7c. The 5G-RG completes the authentication procedure (if initiated in step 6), creates a NAS security context as defined in TS 33.501 [11] and sends the NAS Security Mode Complete message (IMEISV) to the AMF.

7d. The W-AGF relays the NAS Security Mode Complete message to the AMF in a N2 Uplink NAS transport message.

8. [Conditional] The AMF may request the PEI from the 5G-RG as described in clause 4.2.2.2.2, step 11 of TS 23.502 [3].

9. The AMF performs step 12-16 in TS 23.502 [3] clause 4.2.2.2.2. At AMF registration to UDM for the 5G-RG, the Access Type non-3GPP access is used. The RAT type used toward PCF and UDM shall indicate wireline access. The AMF determines Access Type and RAT Type based on the Global RAN Node ID associated with the N2 interface.

10. The AMF sends an N2 Initial Context Setup Request message as defined in TS 38.413 [23] and TS 29.413 [42] possibly including as additional W-AGF specific parameter the RG Level Wireline Access Characteristics.

11a. Void.

11b. Void.

12. W-AGF notifies the AMF that the 5G-RG context was created by sending a N2 Initial Context Setup Response.

13. The AMF sends N2 Downlink NAS transport with the NAS Registration Accept message (as defined in step 21 TS 23.502 [3] clause 4.2.2.2.2) to the W-AGF, which forwards the NAS Registration accept message to the 5G-RG.

14. [Conditional] The 5G-RG responds with NAS Registration Complete message as described in TS 23.502 [3] clause 4.2.2.2.2 step 22 and W-AGF forwards the NAS Registration Complete message to AMF in a N2 Uplink NAS transport message. The N2 Uplink NAS transport message to AMF may contain W-AGF identities. The AMF stores the received W-AGF identities in the UE context.

NOTE 3: The W-AGF identities contains a list of Identifiers (i.e. a list of FQDN and/or IP address(es)) of N3 terminations at W-AGF and can be used by SMF as input to select an UPF during PDU Session Establishment, as described in clauses 7.3.1.1 and 7.3.4.

15. The AMF performs step 23-24 in TS 23.502 [3] clause 4.2.2.2.2.

7.2.1.2 5G-RG Deregistration via W-5GAN

Figure 7.2.1.2-1: 5G-RG Deregistration procedure via W-5GAN

1. The Deregistration procedure is triggered by one of the events:

1a. For 5G-RG-initiated Deregistration as in Figure 4.2.2.3.2-1, steps 1 to 7 of TS 23.502 [3].

1b. For network initiated deregistration as in Figure 4.2.2.3.3-1, steps 1 to 6 of TS 23.502 [3].

If the 5G-RG is in CM-CONNECTED state either in 3GPP access, W-5GAN access or both:

– the AMF may explicitly deregister the 5G-RG by sending a Deregistration request message (Deregistration type, access type set to -W-5GAN) to the 5G-RG as in Figure 4.2.2.3.3-1, step 2 of TS 23.502 [3]. The 5G-RG will interpret access type set to non-3GPP as referring to wireline access.

– the UDM may want to request the deletion of the subscribers RM contexts and PDU Sessions with the reason for removal set to subscription withdrawn to the registered AMF as in Figure 4.2.2.3.3-1, step 1 of TS 23.502 [3].

2. AMF to W-AGF: The AMF sends a N2 UE Context Release Command message to the W-AGF with the cause set to Deregistration to release N2 signalling as defined in clause 4.12.4.2, step 4 of TS 23.502 [3].

3. The W-AGF may initiate the release of the signalling connection between 5G-RG and W-AGF.

NOTE: Whether this step is needed, and if so, the details of this step is defined by BBF.

4. W-AGF to AMF: The W-AGF acknowledges the N2 UE Context Release Command message by sending N2 UE Context Release Complete message to the AMF as defined in clause 4.12.4.2, step 7 of TS 23.502 [3].

7.2.1.3 FN-RG Registration via W-5GAN

The FN-RG registration management procedures are followed for both W-5GBAN and W-5GCAN. The FN-RG does not support N1 but instead the W-AGF handles the NAS signalling on behalf of the FN-RG as defined by BBF TR-456 [9] and WT-457 [10] for FN-BRG and by WT-TR-5WWC-ARCH [27] for FN-CRG.

When the connectivity is established between the FN-RG and the W-AGF in the W-5GAN, the W-AGF may authenticate the FN-RG; this is controlled by local policies and defined in BBF specifications. Then when the RM state of the FN-RG is "RM-DEREGISTERED" the W-AGF shall perform registration to 5GC as described in this clause, otherwise it performs Service Request as defined in clause 7.2.2.

Once the FN-RG is in RM-REGISTERED and CM-CONNECTED the W-AGF may setup PDU session(s) on behalf of the FN-RG (as described in clause 7.3.4).

Figure 7.2.1.3-1: FN-RG Registration via W-5GAN

1. The FN-RG connects to a W-AGF (W-5GAN) via a layer-2 (L2) connection, based on Wireline AN specific procedure.

The FN-RG is authenticated by the W-5GAN based on Wireline AN specific mechanisms.

2. W-AGF selects an AMF based on the AN parameters and local policy. W-AGF may use the Line ID / HFC identifier provided from the Wireline AN to determine the 5GC and AN parameters to be used for the FN-RG registration. How the W-AGF can determine the necessary 5GC and AN parameters is defined in BBF TR-456 [9], WT-457 [10] or CableLabs WR-TR-5WWC-ARCH [27].

3. W-AGF performs initial registration on behalf of the FN-RG to the 5GC. The W-AGF sends a Registration Request to the selected AMF within an N2 initial UE message (NAS Registration Request, ULI, Establishment cause, UE context request, Allowed NSSAI, Authenticated Indication).

The NAS Registration Request contains the SUCI or 5G-GUTI of the FN-RG, security parameters/UE security capability, UE MM Core Network Capability, PDU Session Status, Follow-on request, Requested NSSAI. The 5G-GUTI, if available, has been received from the AMF during a previous registration and stored in W-AGF.

The NSSAI parameters are provided based on W-AGF configuration. Based on W-AGF configuration of the 5GC NAS parameters, one or multiple Requested S-NSSAI may be used; e.g. when the W-AGF has been configured to use a specific slice for RG management purposes.

The following differences exist, compared to 5G-RG case:

– The W-AGF use SUCI as defined in clause 4.7.3 and clause 4.7.4.

– The Authenticated Indication indicates to AMF and 5GC that the FN-RG has been authenticated by the access network.

The SUCI is built by the W-AGF based on:

– In the case of a BBF access: the GLI as defined in clause 4.7.8 together with an identifier of the Home network as described in TS 23.003 [14].

– In the case of a Cable access: the GCI as defined in clause 4.7.8 together with an identifier of the Home network as described in TS 23.003 [14].

NOTE 1: Further description for how W-AGF obtain parameters required in AS and NAS message e.g. to build the SUCI is defined in BBF TR-456 [9], WT-457 [10] and CableLabs WR-TR-5WWC-ARCH [27].

4 If the AMF receives a SUCI, the AMF shall select an AUSF as specified in TS 23.501 [2] clause 6.3.4 based on SUCI. If 5G-GUTI is provided, there is no need to map SUCI to SUPI and steps 5-9 can be skipped.

5. AMF sends an authentication request to the AUSF in the form of, Nausf_UEAuthentication_Authenticate. It contains the SUCI of the FN-RG. It also contains an indication that the W-5GAN has authenticated the FN-RG.

6. AUSF selects a UDM as described in clause 6.3.8 of TS 23.501 [2] and sends a Nudm_UEAuthentication_Get Request to the UDM. It contains the SUCI of the FN-RG and indication that the W-5GAN has authenticated the FN-RG.

7. UDM invokes the SIDF to map the SUCI to a SUPI.

8. UDM sends a Nudm_UEAuthentication_Get Response to the AUSF. It contains the SUPI corresponding to the SUCI. It also contains an indication that authentication is not required for the FN-RG.

9. AUSF sends a Nausf_UEAuthentication_Authenticate Response to the AMF. This response from AUSF indicates that authentication is successful. The response contains the SUPI corresponding to the SUCI.

The procedure described in TS 23.502 [3] clause 4.2.2.2.3 may apply (the AMF decides if the Registration Request needs to be rerouted, where the initial AMF refers to the AMF).

10a. AMF initiates a NAS security mode command procedure upon successful authentication as defined in TS 33.501 [11].

The NAS security mode command is sent from the AMF to the W-AGF in a N2 Downlink NAS transport message.

10b. W-AGF responds to the AMF with a NAS Security Mode Complete message in a N2 Uplink NAS transport message. A NAS security context is created between W-AGF and AMF.

11. The AMF performs steps 11-16 in TS 23.502 [3] clause 4.2.2.2.2.

The AMF may be configured by local policies to issue EIR check:

– Only if the PEI is an IMEI; or

– Only if the PEI is an IMEI or a user device trusted MAC address.

These local policies may be defined on a per RAT Type basis.

At FN-RG registration to UDM, the Access Type non-3GPP access is used. The UDM, based on Access and Mobility Subscription information authorizes the FN-RG to access the 5GC. For FN-CRG, the AMF compares the list of serving area restrictions it receives from the UDM against the ULI from the W-AGF to check if the location information is allowed for the FN-CRG, as defined in clause 9.5.1. The AMF may also interact with the PCF for obtaining the Access and Mobility policy for the FN-RG.

12a. Upon receiving NAS Security Mode Complete, the AMF shall send an N2 Initial Context Setup Request message as defined in TS 38.413 [23] and TS 29.413 [42] including possibly as additional W-AGF specific parameter the RG Level Wireline Access Characteristics to the W-AGF.

12b W-AGF notifies to the AMF that the FN-RG context was created by sending a N2 Initial Context Setup Response.

13. The AMF sends the N2 Downlink NAS transport with NAS Registration Accept message (5GS registration result, 5G-GUTI, Equivalent PLMNs, Non-3GPP TAI, Allowed NSSAI, Rejected NSSAI, Configured NSSAI, 5GS network feature support, network slicing indication, Non-3GPP de-registration timer value, Emergency number lists, SOR transport container, NSSAI inclusion mode) to the W-AGF.

The following parameters are ignored by the W-AGF if received from the AMF: Emergency number lists, SOR transport container, NSSAI inclusion mode.

NOTE 2: Further description on how W-AGF handles the parameters received from 5GC is provided in BBF TR-456 [9], WT-457 [10] and CableLabs WR-TR-5WWC-ARCH [27].

14. The W-AGF sends a N2 Uplink NAS transport message, including a NAS Registration Complete message, back to the AMF when the procedure is completed. The W-AGF shall store the 5G-GUTI to be able to send it in potential later NAS procedures.

15. The AMF performs step 23-24 in TS 23.502 [3] clause 4.2.2.2.2.

The W-AGF may continue by establishing PDU session(s) on behalf of the FN-RG.

7.2.1.4 FN-RG Deregistration via W-5GAN

The deregistration procedure for the FN-RG is similar to that of 5G-RG described in clause 7.2.1.2 but with the following differences:

– The 5G-RG is replaced with a FN-RG.

– In step 1a and 1b, the W-AGF sends and receives NAS deregistration request/accept messages on behalf of FN-RG.

– UE-initiated deregistration procedure can be initiated by the W-AGF, when it has lost connectivity to the FN-RG.

– For both UE/Network-initiated deregistration procedures, the W-AGF may initiate the release of the signalling connection between the FN-RG and W-AGF based on legacy protocols.

NOTE: As described in clause 6.2.2, the message exchanges between the FN-RG and W-AGF are based on legacy protocols in the wireline access network.

7.2.2 Service Request procedures

7.2.2.1 5G-RG Service Request procedure via W-5GAN Access

The Service Request procedure via W-5GAN shall be used by a 5G-RG in CM-IDLE state over W-5GAN to request the re-establishment of the NAS signalling connection and the re-establishment of the user plane for all or some of the PDU Sessions which are associated to non-3GPP access.

NOTE 1: For a W-5GAN access, the Service Request procedure is never a response to a Paging i.e. Paging does not apply on a W-5GAN access.

The Service Request procedure via W-5GAN shall be used by a 5G-RG in CM-CONNECTED state over wireline access to request the re-establishment of the user plane for one or more PDU Sessions which are associated to non-3GPP access.

Figure 7.2.2.1-1: 5G-RG Triggered Service Request procedure via W-5GAN

1. The 5G-RG connects to a W-5GAN as described in step 1 of Figure 7.2.1.1-1.

2. Void.

3. The 5G-RG using W-CP protocol stack sends a message that contains the Access Network parameters (GUAMI and Establishment Cause) and a NAS Service Request message (List Of PDU Sessions To Be Activated, security parameters, PDU Session status, Uplink Data Status, 5G-S-TMSI). The Establishment cause provides the reason for requesting a signalling connection with 5GC. In this release of the specification no Selected PLMN parameter is sent by a 5G RG.

4. The W-AGF shall then forward the Service Request received from the 5G-RG to the selected AMF within an N2 initial UE message (NAS Service Request message, User Location Information, Establishment cause, UE context request).

5. The AMF may initiate NAS authentication/security procedure as defined in step 6 and step 7 in clause 7.2.1.1.

If the UE in CM-IDLE state triggered the Service Request to establish a signalling connection only, after successful establishment of the signalling connection the UE and the network can exchange NAS signalling and steps 6 and 14 are skipped.

6. Steps 4-11 in TS 23.502 [3] figure 4.2.3.2-1 are performed for each requested PDU session user plane.

7. (If the 5G RG was CM-IDLE) AMF sends an N2 Initial Context Setup Request message (N2 SM information received from SMF(s), RG Level Wireline Access Characteristics, GUAMI, Allowed NSSAI, UE security capability, Security Key, Trace Activation, Masked IMEISV).

If the 5G RG was CM-CONNECTED the AMF sends N2 SM information received from SMF(s).

The W-AGF ignores any UE security capability received in a N2 Initial Context Setup Request message.

NOTE 2: The UE Security Capability IE is mandatory in NGAP protocol, but it is not applicable to wireline access, so the AMF can provide any value and the W-AGF ignores it.

8. Void.

9. [Conditional, if the 5G RG was CM-IDLE] A signalling connection using W-CP protocol stack is established between the 5G-RG and W-AGF.

NOTE 3: Steps 9-11 are defined by BBF/Cablelabs.

Steps 10 and 11 are carried out for each PDU Session indicated in step 7

10. Based on its own policies and configuration and based on the QoS flows and QoS parameters received in the previous step, the W-AGF shall determine what W-UP resources are needed for the PDU session.

11. The W-AGF sets up the W-UP resources for the PDU session. This step is specified by BBF for W-5BGAN and by CableLabs for W-5GCAN. The access dependent W-UP resource setup procedure shall map to the identity of the PDU Session associated with the W-UP resource.

12. W-AGF notifies the AMF that the 5G-RG context was created by sending a N2 Initial Context Setup Response (N2 SM information that provides AN Tunnel Info, List of accepted QoS Flows, List of rejected QoS Flows per PDU Session ID for PDU Sessions whose UP connections are activated).

13. AMF sends NAS Service Accept via W-AGF to the 5G-RG.

14. All steps after step 14 in TS 23.502 [3] figure 4.2.3.2-1 are performed for each requested PDU Session user plane.

When the 5G-RG is in CM-CONNECTED state over W-5GAN access and the network receives downlink data for a PDU Session over wireline access that has no user plane connection, the steps 1-4a in clause 4.2.3.3 of TS 23.502 [3] (Network Triggered Service Request) shall be performed with the following exceptions:

– The (R)AN corresponds to an W-AGF.

– The UE corresponds to the 5G-RG.

– In step 4a of TS 23.502 [3] clause 4.2.3.3, the steps 2b-6 in figure 7.3.1.1-1 are performed to establish the W-UP resources and to establish N3 tunnel. In steps 2b and 6, no NAS message is exchanged with the UE.

7.2.2.2 FN-RG Service Request procedure via W-5GAN Access

The Service Request procedure via W-5GAN shall be used by a W-AGF when the CM state in W-AGF for a FN-RG is CM-IDLE over W-5GAN to request the re-establishment of the NAS signalling connection and the re-establishment of the user plane for all or some of the PDU Sessions which are associated to non-3GPP access.

The Service Request procedure via W-5GAN shall be used by a W-AGF when the CM state in W-AGF for a FN-RG is CM-CONNECTED over wireline access to request the re-establishment of the user plane for one or more PDU Sessions which are associated to non-3GPP access.

Figure 7.2.2.2-1: FN-RG Service Request procedure via W-5GAN

1. If the FN-RG has lost the L2 connection with W-AGF, the FN-RG connects to a W-AGF (W-5GAN) via a layer-2 (L2) connection, based on Wireline AN specific procedure.

2. If step 1 was done, the FN-RG may be authenticated by the W-5GAN based on Wireline AN specific procedure.

3. The W-AGF shall then send a Service Request to the selected AMF within an N2 initial UE message (NAS Service Request message, User Location Information, Establishment cause, UE context request, Auth_Indicate).

4. The AMF may initiate NAS authentication/security procedure as defined in steps 5-10 in clause 7.2.1.3.

If the W-AGF triggered the Service Request to establish a signalling connection only, after successful establishment of the signalling connection the W-AGF and the network can exchange NAS signalling and steps 5 and 10 are skipped.

5. Steps 4-11 in TS 23.502 [3] figure 4.2.3.2-1 are performed for each requested PDU session user plane.

6. (If the FN-RG CM state was CM-IDLE) AMF sends an N2 Initial Context Setup Request message (N2 SM information received from SMF(s), RG Level Wireline Access Characteristics, GUAMI, Allowed NSSAI, UE security capability, Security Key, Trace Activation, Masked IMEISV).

If the FN-RG CM state in W-AGF was CM-CONNECTED the AMF sends N2 SM information received from SMF(s).

The W-AGF ignores any UE security capability received in a N2 Initial Context Setup Request message.

NOTE: The UE Security Capability IE is mandatory in NGAP protocol, but it is not applicable to a wireline access, so the AMF can provide any value and the W-AGF ignores it.

Step 7 is carried out for each PDU Session indicated in step 6.

7. Based on its own policies and configuration and based on the QoS flows and QoS parameters received in the previous step, the W-AGF shall determine what W-UP resources are needed for the PDU session.

The W-AGF may perform BBF specific resource reservation with the AN, that is, it sets up the L-W-UP resources for the PDU session. This step is specified by BBF for W-5GBAN and by CableLabs for W-5GCAN.

8. W-AGF notifies the AMF that the FN-RG context in W-AGF was created by sending a N2 Initial Context Setup Response (N2 SM information that provides AN Tunnel Info, List of accepted QoS Flows, List of rejected QoS Flows per PDU Session ID for PDU Sessions whose UP connections are activated).

9. AMF sends NAS Service Accept to W-AGF.

10. All steps after step 14 in figure 4.2.3.2-1 of TS 23.502 [3] are performed for each requested PDU session user plane.

When the FN-RG CM state in W-AGF is CM-CONNECTED over W-5GAN access and the network receives downlink data for a PDU Session over wireline access that has no user plane connection, the steps 1-4a in clause 4.2.3.3 of TS 23.502 [3] (Network Triggered Service Request) shall be performed with the following exceptions:

– The (R)AN corresponds to an W-AGF.

– The UE corresponds to the FN-RG.

– In step 4a, the steps 6-10 in figure 7.2.2.2-1 are performed to establish the L-W-UP resources and to establish N3 tunnel. In step 6, the AMF does not send the NAS Service Accept message to the UE.

7.2.3 5G-RG and FN-RG Configuration Update

7.2.3.0 General

This clause specifies delta for Configuration Update procedure defined in TS 23.502 [3] clause 4.2.4 for 5G-RG and FN-RG.

7.2.3.1 5G-RG Configuration Update via W-5GAN Access

The 5G-RG Configuration Update procedures via W-5GAN may be used by the network at any time to update 5G-RG configuration which includes:

– Access and Mobility Management related parameters decided and provided by the AMF. This includes the Configured NSSAI and its mapping to the Subscribed S-NSSAIs, the Allowed NSSAI and its mapping to Subscribed S-NSSAIs.

– 5G-RG Policy (i.e. URSP) provided by the PCF.

The procedure described in TS 23.502 [3] clause 4.2.4.2 is used for the AMF to change the 5G-RG configuration for access and mobility management related parameters, with the following differences:

– The UE is replaced by the 5G-RG.

– The (R)AN corresponds to the W-5GAN.

Figure 7.2.3.1-1: 5G-RG Configuration Update procedure for access and mobility management related parameters

In Step 0, the AMF determines the necessity of 5G-RG configuration change due to various reasons, but UE mobility change is not applicable in this release of specification. If a 5G-RG is in CM-IDLE, the AMF can wait until the 5G-RG is in CM-CONNECTED state as Network Triggered Service Request is not applicable.

In step 1, the AMF sends UE Configuration Update Command to the 5G-RG. The following parameters are not included: Mapping Of Allowed NSSAI, Configured NSSAI for the Serving PLMN, Mapping Of Configured NSSAI, MICO, Operator-defined access category definitions, SMS Subscribed Indication.

Step 2c is not applicable in this procedure.

Step 3a is not applicable since it is only for NAS parameters that can be updated without transition from CM-IDLE are included, e.g. MICO mode.

The procedure for UE Configuration Update procedure for transparent UE Policy delivery described in TS 23.502 [3] clause 4.2.4.3 is used for the PCF to change or provide new 5G-RG policies in the 5G-RG, with the following differences:

– The UE is replaced by the 5G-RG.

– The (R)AN corresponds to the W-5GAN.

– The means for carrying NAS messages between 5G-RG and W-AGF within the W-GAN are to be defined by BBF.

– Step 2 is not applicable since the Network Triggered Service Request is not applicable in the case of W-5GAN.

Figure 7.2.3.1-2: 5G-RG Configuration Update procedure for transparent UE Policy delivery

7.2.3.2 FN-RG related Configuration Update via W-5GAN Access

The FN-RG related Configuration Update procedures via W-5GAN may be used by the network at any time to update FN-RG configuration in W-AGF which includes:

– FN-RG related Policy (i.e. URSP) provided by the PCF.

The W-AGF acts as an N1 termination point on behalf of FN-RG. Therefore, the configuration update procedures described in clause 7.2.3.1, shown in figure 7.2.3.1-1, apply to the FN-RG, with the following additional differences:

– The 5G-RG is replaced by the W-AGF which is acting as a UE towards the 5GC on behalf of the FN-RG.

– In step 1 the AMF sends the UE Configuration Update Command to the FN-RG, which is received by the W-AGF terminating the N1 and acting as a UE on behalf of the FN-RG. The W-AGF stores the UE Configuration as defined in clause 9.4. If requested by the AMF, the W-AGF shall acknowledge the UE Configuration Update Command.

– Step 2d is not applicable.

– When requested by the AMF, in step 4 the W-AGF starts the registration procedure described in clause 7.2.1.3.

– The Emergency service is not applicable.

Figure 7.2.3.2-1: FN-RG related Configuration Update procedure for access and mobility management related parameters

The procedure of UE Configuration Update procedure for transparent UE Policy delivery described in TS 23.502 [3] clause 4.2.4.3 is used by the PCF to change or provide new FN-RG policies in the W-AGF, with the following differences:

– The UE is replaced by the W-AGF which is acting as a UE towards the 5GC on behalf of the FN-RG.

– The (R)AN corresponds to the W-5GAN.

– The FN-RG is only registered over W-5GAN.

– Step 2 is not applicable since the Network Triggered Service Request is not applicable in the case of W-5GAN.

– In step 3, the W-AGF receives the delivery of UE policies on behalf of FN-RG.

– The FN-RG policies are managed by W-AGF as defined in clause 9.5.2.2.

How the W-5GAN applies the configuration update to the wireline network is to be defined by the BBF for the FN-BRG and by CableLabs for the FN-CRG.

The operator may configure the W-AGF locally by provisioning means not specified by 3GPP as an alternative to the Configuration Update procedure for UE Policy delivery. The 3GPP Configuration Update will take precedence over a locally configured policy for FN-BRGs or FN-CRGs being serviced by the 5GC.

Figure 7.2.3.2-2: FN-RG related Configuration Update procedure for transparent UE Policy delivery

7.2.4 Reachability procedures

The procedures described in TS 23.502 [3] clause 4.2.5 are not applicable for 5G-RG and FN-RG access via W-5GAN.

7.2.5 AN Release

7.2.5.1 General

The AN Release procedure via W-5GAN access is used by the W-5GAN or the AMF to release the logical NG-AP signalling connection and the associated N3 User Plane connections between the W-5GAN and the 5GC.

7.2.5.2 5G-RG AN Release via W-5GAN

The procedure will move the 5G-RG from CM-CONNECTED to CM-IDLE in AMF, and all 5G-RG related context information is deleted in the W-AGF.

Both W-AGF initiated and AMF-initiated AN release in the W-5GAN procedures are shown in Figure 7.2.5-1.

Figure 7.2.5-1: 5G-RG AN release in the W-AGF

1 The 5G-RG has already registered in the 5GC and may have established one or multiple PDU Sessions.

2. The W-AGF detects that the 5G-RG is not reachable.

3. The W-AGF sends a N2 UE Context Release Request message to the AMF This step is equivalent to step 1b of Figure 4.2.6-1 in TS 23.502 [3].

NOTE 1: The triggers for W-AGF to send UE Context Release Request are defined by BBF in [9] and in CableLabs WR-TR-5WWC-ARCH [27] and may e.g. include events where W-AGF has lost of synchronisation of physical link, loss of PPPoE session, or detects that the RG has been replaced.

NOTE 2: AN Release procedure can also be triggered by an AMF internal event and in that case step 2 and step 3 do not take place.

4. AMF to W-AGF: If the AMF receives the N2 UE Context Release Request from W-AGF or if due to an internal AMF event the AMF wants to release N2 signalling, the AMF sends an N2 UE Context Release Command (Cause) to the W-AGF. The cause indicated is cause from step 3 or a cause due to internal AMF event. This step is equivalent to step 2 in Figure 4.2.6-1 of TS 23.502 [3].

5. If the W-CP signalling connection and W-UP resources has not been released yet, the W-AGF releases the W-CP connection and W-UP resources with a procedure out of scope of 3GPP. The W-AGF sends to the 5G-RG the indication of the release reason if received in step 4.

6. W-AGF to AMF: The W-AGF confirms the release of the 5G-RG-associated N2-logical connection by returning N2 UE Context Release Complete (list of PDU Session ID(s) with active N3 user plane) to the AMF as in step 4 defined in clause 4.2.6 of TS 23.502 [3]. The AMF marks the 5G-RG as CM-IDLE state in non-3GPP access.

7. For each of the PDU Sessions in the N2 UE Context Release Complete, the steps 5 to 7 in TS 23.502 [3] clause 4.2.6 are performed (PDU Session Update SM Context). After the AMF receives the Nsmf_PDUSession_UpdateSMContext Response as in step 7 of TS 23.502 [3] clause 4.2.6, the AMF considers the N3 connection as released. If list of PDU Session ID(s) with active N3 user plane is included in step 3, then this step is performed before step 4.

7.2.5.3 FN-RG AN Release via W-5GAN

The AN release procedure for the FN-RG is similar to that of 5G-RG described in clause 7.2.5.2 but with the following differences:

– The 5G-RG is replaced with a FN-RG.

– In step 5, the W-AGF may initiate the release of the L-W-CP signalling and L-W-UP resources between the FN-RG and W-AGF based on legacy protocols.

NOTE: The message exchanges between the FN-RG and W-AGF are based on legacy protocols in the wireline access network as described in clause 6.2.2.

7.2.6 N2 procedures

7.2.6.0 General

This clause specifies delta for N2 procedures defined in TS 23.502 [3] clause 4.2.7 for 5G-RG and FN-RG.

7.2.6.1 N2 procedures via W-5GAN Access

At power up, restart and when modifications are applied, the W-AGF node and AMF use non-UE related N2 signalling to exchange configuration data. The N2 Configuration as described in TS 23.502 [3] clause 4.2.7.1 is used with the following differences:

– The 5G-AN corresponds to the W-AGF.

The Creating NGAP UE-TNLA-bindings during Registration and Service Request procedure as described in TS 23.502 [3] clause 4.2.7.2.1 is used for 5G-RG connecting to 5GC via W-5GAN Access, with the following differences:

– The 5G-AN corresponds to the W-AGF.

– The UE corresponds to 5G-RG.

The Creating NGAP UE-TNLA-bindings during Registration and Service Request procedure as described in TS 23.502 [3] clause 4.2.7.2.1 is used for FN-RG connecting to 5GC via W-5GAN Access with the following differences:

– The 5G-AN corresponds to the W-AGF.

– The UE corresponds to W-AGF on behalf of FN-RG.

– If the W-AGF does not have any UE identities (i.e. a GUAMI or a 5G-S-TMSI) for the FN-RG, e.g. during Initial Registration procedure, the following differences are further applied:

– In step 2, the W-AGF shall handle the access specific messages received from the FN-RG as described in BBF TR456 [9] and WT-457 [10], e.g. PPPoE messages, and does not forward them to the AMF via the selected TNL association. Instead, the W-AGF shall send NAS messages on behalf of the FN-RG to the AMF via the selected TNL association.

– Step 3 can only take place during the Initial Registration procedure.

– The AMF may decide to modify the NGAP UE-TNLA-binding toward other 5G-AN nodes such as W-AGF. This is done if AMF is changed and old AMF have existing NGAP UE-TNLA-bindings toward another W-AGF.

The Creating NGAP UE-TNLA-bindings during handovers as described in TS 23.502 [3] Clause 4.2.7.2.2 is not applicable to the scenario when 5G-RG or FN-RG is access to 5GC via W-5GAN.

Re-Creating NGAP UE-TNLA-bindings subsequent to NGAP UE-TNLA-binding release as described in TS 23.502 [3] clause 4.2.7.2.3 is used for 5G-RG connecting to 5GC via W-5GAN Access with the following exceptions:

– The 5G-AN corresponds to the W-AGF.

– The UE corresponds to 5G-RG.

Re-Creating NGAP UE-TNLA-bindings subsequent to NGAP UE-TNLA-binding release as described in TS 23.502 [3] clause 4.2.7.2.3 is used for FN-RG connecting to 5GC via W-5GAN Access with the following exceptions:

– The 5G-AN corresponds to the W-AGF.

– The UE corresponds to W-AGF on behalf of FN-RG.

7.2.7 5G-RG and FN-RG Capability Match Request procedure

This procedure is not applicable to 5G-RG and FN-RG access via wireline access.