Method of access and mobility management function (AMF), method of user equipment (UE), AMF and UE

A method of a User equipment (UE) comprising:

• sending, to an Access and Mobility Management Function (AMF), a registration request message after the AMF receives, from a Network Slice Admission Control Function (NSACF), a message including information indicating that an Early Admission Control (EAC) mode is deactivated for Single Network Slice Selection Assistance Information (S-NSSAI),
• wherein the registration request message includes requested Network Slice Selection Assistance Information (NSSAI), and
• wherein the requested NSSAI includes Single Network Slice Selection Assistance Information (S-NSSAI);
• receiving, from the AMF, allowed NSSAI, wherein the allowed NSSAI includes the S-NSSAI, and wherein the AMF sends, to the NSACF, a request message after the UE receives, from the AMF, the allowed NSSAI;
• and
• receiving, from the AMF, a de-registration request message after a response, from the NSACF is waited, the response being related to the S-NSSAI,
• wherein the de-registration request message includes rejected NSSAI, and
• wherein the rejected NSSAI includes the S-NSSAI.

An Access and Mobility Management Function (AMF) comprising one or more memories storing instructions and one or more processors configured to execute the instructions to:

• receive, from a Network Slice Admission Control Function (NSACF), a message including information indicating that an Early Admission Control (EAC) mode is deactivated for Single Network Slice Selection Assistance Information (S-NSSAI);
• receive, from a User equipment (UE), a registration request message,
• wherein the registration request message includes requested Network Slice Selection Assistance Information (NSSAI), and
• wherein the requested NSSAI includes Single Network Slice Selection Assistance Information (S-NSSAI);
• send, to the UE, allowed NSSAI wherein the allowed NSSAI includes the S-NSSAI;
• send, to the NSACF, a request message;
• process a first Non-Access Stratum (NAS) message related to the S-NSSAI while the AMF waits, from the NSACF, for a response being related to the S-NSSAI;
• and
• send, to the UE, a de-registration request message after the AMF waits, from the NSACF, for the response,
• wherein the de-registration request message includes rejected NSSAI, and
• wherein the rejected NSSAI includes the S-NSSAI.

A User equipment (UE) comprising one or more memories storing instructions and one or more processors configured to execute the instructions to:

• send, to an Access and Mobility Management Function (AMF), a registration request message after the AMF receives, from a Network Slice Admission Control Function (NSACF), a message including information indicating that an Early Admission Control (EAC) mode is deactivated for Single Network Slice Selection Assistance Information (S-NSSAI),
• wherein the registration request message includes requested Network Slice Selection Assistance Information (NSSAI), and
• wherein the requested NSSAI includes Single Network Slice Selection Assistance Information (S-NSSAI);
• receive, from the AMF, allowed NSSAI, wherein the allowed NSSAI includes the S-NSSAI, and wherein the AMF sends, to the NSACF, a request message after the UE receives, from the AMF, the allowed NSSAI;
• and
• receive, from the AMF, a de-registration request message after a response, from the NSACF is waited, the response being related to the S-NSSAI,
• wherein the de-registration request message includes rejected NSSAI, and
• wherein the rejected NSSAI includes the S-NSSAI.