Method and apparatus for slice replacement in a communication network system

A user equipment (UE) comprising:

• at least one transceiver;
• at least one processor communicatively coupled to the at least one transceiver;
• and
• memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the UE to:
• receive, from an access and mobility management function (AMF) entity via the at least one transceiver, a message including an alternative network slice selection assistance information (NSSAI) and single-NSSAI (S-NSSAI) time validity information, wherein the alternative NSSAI comprises an entry including a replaced S-NSSAI and an alternative S-NSSAI to be included in an allowed NSSAI,
• remove either the replaced S-NSSAI or the alternative S-NSSAI from the allowed NSSAI, based on the S-NSSAI time validity information, and
• delete the entry from the alternative NSSAI, in case that the replaced S-NSSAI or the alternative S-NSSAI is removed from the allowed NSSAI.

An access and mobility management function (AMF) entity, the AMF entity comprising:

• at least one transceiver;
• at least one processor communicatively coupled to the at least one transceiver;
• and
• memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the AMF entity to:
• transmit, to a user equipment (UE) via the at least one transceiver, a message including an alternative network slice selection assistance information (NSSAI) and single-NSSAI (S-NSSAI) time validity information, wherein the alternative NSSAI comprises an entry including a replaced S-NSSAI and an alternative S-NSSAI to be included in an allowed NSSAI;
• and
• remove either the replaced S-NSSAI or the alternative S-NSSAI from the allowed NSSAI, and the entry from the alternative NSSAI based on the S-NSSAI time validity information.