5.3.25 Core network assistance for paging early indication with paging subgrouping assistance (PEIPS)

The UE and the network may support PEIPS assistance information (see 3GPP TS 23.501 [8]).

If the UE supports PEIPS assistance information, the UE indicates its capability to support PEIPS assistance information during the registration procedure for either initial registration or mobility registration update, using the NR paging subgrouping capability indication. If the UE indicates support of PEIPS assistance information the UE can include its UE paging probability information in the Requested PEIPS assistance information IE in the REGISTRATION REQUEST message when the UE:

• initiates a registration procedure with 5GS registration type IE not set to "emergency registration"; and
• does not have an active emergency PDU session.

NOTE: The requirements for UE-ID based PEI are specified in 3GPP TS 38.300 [27].

If a UE supporting NR paging subgrouping did not indicate its capability to support NR paging subgrouping during the last registration procedure due to an active emergency PDU session over 3GPP access, the UE shall initiate a registration procedure for mobility and periodic registration update to indicate its capability to support NR paging subgrouping after the emergency PDU session is released over 3GPP access.

If the UE indicates support of PEIPS assistance information and the network supports and accepts the use of the PEIPS assistance information for the UE, the network provides to the UE:

• the Negotiated PEIPS assistance information IE, including the PEIPS assistance information, in the REGISTRATION ACCEPT message; or
• the Updated PEIPS assistance information IE, including the PEIPS assistance information, in the CONFIGURATION UPDATE COMMAND message as part of the registration procedure.

The PEIPS assistance information includes the Paging subgroup ID. The UE NAS layer shall indicate the PEIPS assistance information to lower layers. The network shall store the UE support indication of PEIPS assistance information and the PEIPS assistance information in the 5GMM context of the UE.

The UE shall use PEIPS assistance information only if the UE received the Negotiated PEIPS assistance information IE during the last registration procedure for either initial registration or mobility registration update. If the UE did not receive the Negotiated PEIPS assistance information IE during the last registration procedure for either initial registration or mobility registration update, the UE shall delete any existing PEIPS assistance information received from the network.

If the network did not accept the use of PEIPS assistance information during the registration procedure for either initial registration or mobility registration update, the network shall delete the PEIPS assistance information stored in the 5GMM context of the UE, if available.

If the network provided PEIPS assistance information to the UE in the last registration procedure for either initial registration or mobility registration update, either in the REGISTRATION ACCEPT message or in the CONFIGURATION UPDATE COMMAND message as part of the registration procedure, the network can provide the updated PEIPS assistance information to the UE by including the Updated PEIPS assistance information IE in the CONFIGURATION UPDATE COMMAND message.

When an emergency PDU session is successfully established over 3GPP access after the UE received the Negotiated PEIPS assistance information IE during the last registration procedure, the UE and the AMF shall not use PEIPS assistance information until:

• the successful completion of the PDU session release procedure of the emergency PDU;
• the UE receives PEIPS assistance information during a registration procedure with PDU session status IE or upon successful completion of a service request procedure, if the UE or the network locally releases the emergency PDU session;
• the successful completion of handover of emergency PDU session to non-3GPP access; or
• the successful transfer of the emergency PDU session in 5GS to the EPS or ePDG connected to EPC.