D.2 Procedures

24.5013GPPNon-Access-Stratum (NAS) protocol for 5G System (5GS)Release 17Stage 3TS

D.2.1 Network-requested UE policy management procedure

D.2.1.1 General

The purpose of the network-requested UE policy management procedure is to enable the network to:

a) add one or more new UE policy sections to the UE;

b) modify one or more UE policy sections stored at the UE; or

c) delete one or more UE policy sections stored at the UE.

D.2.1.2 Network-requested UE policy management procedure initiation

In order to initiate the network-requested UE policy management procedure, the PCF shall:

a) if the network-requested UE policy management procedure is triggered by the UE-requested V2X policy provisioning procedure as specified in 3GPP TS 24.587 [19B] or the UE-requested ProSeP policy provisioning procedure as specified in 3GPP TS 24.554 [19E], then set the PTI IE to the PTI value of the received UE POLICY PROVISIONING REQUEST message of the UE-requested V2X policy provisioning procedure or the UE-requested ProSeP policy provisioning procedure, otherwise allocate a PTI value currently not used and set the PTI IE to the allocated PTI value;

b) encode the information about the UE policy sections to be added, modified or deleted in a UE policy section management list IE as specified in subclause D.6.2 and include it in a MANAGE UE POLICY COMMAND message;

c) send the MANAGE UE POLICY COMMAND message to the UE via the AMF as specified in 3GPP TS 23.502 [9]; and

d) start timer T3501 (see example in figure D.2.1.2.1).

NOTE: The PCF starts a different timer T3501 for each PTI value.

Figure D.2.1.2.1: Network-requested UE policy management procedure

Upon receipt of the MANAGE UE POLICY COMMAND message with a PTI value currently not used by a network-requested UE policy management procedure, for each instruction included in the UE policy section management list IE, the UE shall:

a) store the received UE policy section of the instruction, if the UE has no stored UE policy section associated with the same UPSI as the UPSI associated with the instruction;

b) replace the stored UE policy section with the received UE policy section of the instruction, if the UE has a stored UE policy section associated with the same UPSI as the UPSI associated with the instruction; or

c) delete the stored UE policy section, if the UE has a stored UE policy section associated with the same UPSI as the UPSI associated with the instruction and the UE policy section contents of the instruction is empty.

The UE may continue storing a received UE policy section for a PLMN or SNPN when the UE registers in another PLMN or SNPN. If necessary, the UE may delete UE policy sections stored for a PLMN or SNPN other than the RPLMN and the HPLMN or the registered SNPN, before storing the new received UE policy sections.

When storing a UE policy sections received from an SNPN, the UE shall associate the NID of that SNPN with the UPSI of the stored UE policy section.

NOTE: The maximum number of UE policy sections for PLMNs or SNPNs other than the HPLMN and the RPLMN or the registered SNPN that the UE can store and how the UE selects the UE policy sections to be deleted are up to the UE implementation.

D.2.1.3 Network-requested UE policy management procedure accepted by the UE

If all instructions included in the UE policy section management list IE were executed successfully by the UE, the UE shall:

a) create a MANAGE UE POLICY COMPLETE message including the PTI value received within the MANAGE UE POLICY COMMAND message; and

b) transport the MANAGE UE POLICY COMPLETE message using the NAS transport procedure as specified in subclause 5.4.5.

Upon receipt of the MANAGE UE POLICY COMPLETE message, the PCF shall stop timer T3501. The PCF should ensure that the PTI value assigned to this procedure is not released immediately.

NOTE: The way to achieve this is implementation dependent. For example, the PCF can ensure that the PTI value assigned to this procedure is not released during the time equal to or greater than the default value of timer T3501.

D.2.1.4 Network-requested UE policy management procedure not accepted by the UE

If the UE could not execute all instructions included in the UE policy section management list IE successfully, the UE shall:

a) set the PTI IE to the PTI value received within the MANAGE UE POLICY COMMAND message and encode the UPSI associated with the instructions which could not be executed successfully and the associated UE policy delivery service cause indicating the cause of the failure in a UE policy section management result IE as specified in subclause D.5.3 and include it in a MANAGE UE POLICY COMMAND REJECT message, and

b) transport the MANAGE UE POLICY COMMAND REJECT message using the NAS transport procedure as specified in subclause 5.4.5.

Upon receipt of the MANAGE UE POLICY COMMAND REJECT message, the PCF shall stop timer T3501. Any instruction that was included in the UE policy section management list IE and whose associated UPSI is not included in a UE policy section management result IE of the received MANAGE UE POLICY COMMAND REJECT message is considered as successfully executed.

The PCF should ensure that the PTI value assigned to this procedure is not released immediately.

NOTE: The way to achieve this is implementation dependent. For example, the PCF can ensure that the PTI value assigned to this procedure is not released during the time equal to or greater than the default value of timer T3501.

Upon receipt of the notification from the AMF that the UE is not reachable, the PCF shall stop the T3501.

D.2.1.5 Abnormal cases on the network side

The following abnormal cases can be identified:

a) T3501 expired.

The PCF shall, on the first expiry of the timer T3501, retransmit the MANAGE UE POLICY COMMAND message and shall reset and start timer T3501. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3501, the PCF shall abort the procedure and release the allocated PTI.

D.2.1.6 Abnormal cases in the UE

The following abnormal cases can be identified:

a) Receipt of an instruction associated with a UPSI which has a PLMN ID part that is not equal to the PLMN ID of the UE’s HPLMN and the instruction contains a UE policy part with a UE policy part type set to "URSP" for a UE not operating in SNPN access operation mode, or receipt of an instruction associated with a UPSI which has a PLMN ID part that is not equal to the PLMN ID part of the selected SNPN and the instruction contains a UE policy part with a UE policy part type set to "URSP" for a UE operating in SNPN access operation mode.

The UE shall set the UE policy delivery service cause to #111 (Protocol error, unspecified) for the instruction in the UE policy section management result IE of the MANAGE UE POLICY COMMAND REJECT message.

b) Receipt of an instruction associated with a UPSI which has a PLMN ID part that is not equal to the PLMN ID of the UE’s HPLMN or the UE’s RPLMN and the instruction contains a UE policy part with a UE policy part type set to "ANDSP" for a UE not operating in SNPN access operation mode.

The UE shall set the UE policy delivery service cause to #111 (Protocol error, unspecified) for the instruction in the UE policy section management result IE of the MANAGE UE POLICY COMMAND REJECT message.

c) Transmission failure of the MANAGE UE POLICY COMPLETE message indication from lower layers.

The UE shall not diagnose an error and consider the network-initiated UE policy delivery procedure complete.

NOTE 1: Considering the network-initiated UE policy delivery procedure complete as a result of this abnormal case does not cause the UE to revert the execution of the instructions included in the MANAGE UE POLICY COMMAND message.

d) Transmission failure of the MANAGE UE POLICY COMMAND REJECT message indication from lower layers.

The UE shall not diagnose an error and consider the network-initiated UE policy delivery procedure complete.

NOTE 2: Considering the network-initiated UE policy delivery procedure complete as a result of this abnormal case does not cause the UE to revert the execution of the instructions included in the MANAGE UE POLICY COMMAND message and successfully processed by the UE.

e) Receipt of a MANAGE UE POLICY COMMAND message with a PTI set to the same value as the PTI of a previously received MANAGE UE POLICY COMMAND message.

The UE shall discard the message and retransmit the MANAGE UE POLICY COMMAND COMPLETE or MANAGE UE POLICY COMMAND REJECT message transmitted in response to the previously received MANAGE UE POLICY COMMAND message.

NOTE 3: The way to achieve this is UE implementation dependent. For example, the UE can assume that on the fifth expiry of timer T3501, the PCF will abort the procedure and that the PTI value assigned to the procedure will be released.

D.2.2 UE-initiated UE state indication procedure

D.2.2.1 General

The purpose of the UE-initiated UE state indication procedure is:

a) to deliver the UPSI(s) of the UE policy section(s) which are:

– identified by a UPSI with the PLMN ID part indicating the HPLMN or the selected PLMN; and

– stored in the UE;

to the PCF if the UE has one or more stored UE policy sections identified by a UPSI with the PLMN ID part indicating the HPLMN or the selected PLMN; and

b) to indicate whether UE supports ANDSP; and

c) to deliver the UE’s one or more OS IDs.

D.2.2.2 UE-initiated UE state indication procedure initiation

In order to initiate the UE-initiated UE state indication procedure, the UE shall create a UE STATE INDICATION message. The UE:

a) shall allocate a PTI value currently not used and set the PTI IE to the allocated PTI value;

b) if not operating in SNPN access operation mode, shall include the UPSI(s) of the UE policy section(s) which are identified by a UPSI with the PLMN ID part indicating the HPLMN or the selected PLMN available in the UE in the UPSI list IE;

c) if operating in SNPN access operation mode, shall include UPSI(s) of the UE policy section(s) which are identified by a UPSI:

– with the PLMN ID part indicating the MCC and MNC of the selected SNPN; and

– associated with the NID of the selected SNPN;

available in the UE in the UPSI list IE;

d) shall specify whether the UE supports ANDSP in the UE policy classmark IE; and

e) may include the UE’s one or more OS IDs in the UE OS Id IE.

The UE shall send the UE STATE INDICATION message (see example in figure D.2.2.2.1). The UE shall transport the created UE STATE INDICATION message using the registration procedure (see subclause 5.5.1).

Figure D.2.2.2.1: UE-initiated UE state indication procedure

D.2.2.3 UE-initiated UE state indication procedure accepted by the network

Upon receipt of the UE STATE INDICATION message, the PCF shall operate as described in 3GPP TS 23.502 [9] and 3GPP TS 29.525 [21].

D.2.2.4 Abnormal cases on the network side

Apart from the case described in subclause D.2.2.3, no abnormal cases have been identified.