Method and apparatus for controlling network slice in wireless communication system

1 . A method performed by a network entity in a wireless communication system, the method comprising:

triggering an update for a number of at least one user equipment (UE) with at least one packet data unit (PDU) session or packet data network (PDN) connection established on a network slice, when a UE establishes a first PDU session or a first PDN connection associated with the network slice, or a last PDU session or a last PDN connection associated with the network slice is released;

transmitting, to a network slice admission control function (NSACF), an update request message for the number of the at least one UE; and

receiving, from the NSACF, an update response message indicating whether the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice reaches a maximum number of UEs with the at least one PDU session or PDN connection for the network slice.

2 . The method of claim 1 , wherein the update request message includes single-network slice selection assistance information (S-NSSAI), an identifier of a UE, and an update flag, and

wherein the update flag indicates whether to increase or decrease the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice.

3 . The method of claim 2 , wherein the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice is increased:

the update flag indicates to increase the number of the at least one UE,

the identifier of the UE is not included in a list of UEs associated with the S-NSSAI, and

the number of the at least one UE is less than the maximum number of UEs.

4 . The method of claim 1 , further comprising:

transmitting, to a network repository function (NRF), a network function discovery request message for the NSACF; and

receiving, from the NRF, a network function discovery response message including a network function profile of the NSACF,

wherein the network function discovery request message includes an NSACF service capability indicator to support monitoring and controlling the number of at least one UE with the at least one PDU session or PDN connection established on the network slice.

5 . A method performed by a network slice admission control function (NSACF) in a wireless communication system, the method comprising:

receiving, from a network entity, an update request message for a number of at least one user equipment (UE) with at least one packet data unit (PDU) session or packet data network (PDN) connection established on a network slice, when a UE establishes a first PDU session or a first PDN connection associated with the network slice, or a last PDU session or a last PDN connection associated with the network slice is released; and

in response to receiving the update request message from the network entity, transmitting, to the network entity, an update response message indicating whether the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice reaches a maximum number of UEs with the at least one PDU session or PDN connection for the network slice.

6 . The method of claim 5 , wherein the update request message includes single-network slice selection assistance information (S-NSSAI), an identifier of a UE, and an update flag, and

wherein the update flag indicates whether to increase or decrease the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice.

7 . The method of claim 6 , further comprising:

increasing the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice if:

the update flag indicates to increase the number of the at least one UE,

the identifier of the UE is not included in a list of UEs associated with the S-NSSAI, and

the number of the at least one UE is less than the maximum number of UEs.

8 . The method of claim 5 , further comprising:

transmitting, to a network repository function (NRF) entity, a network function register request message; and

receiving, from the NRF, a network function response message,

wherein the network function register message includes an NSACF service capability indicator to support monitoring and controlling the number of at least one UE with the at least one PDU session or PDN connection established on the network slice.

9 . A network entity in a wireless communication system, the network entity comprising:

a transceiver; and

at least one processor coupled to the transceiver and configured to:

trigger an update for a number of at least one user equipment (UE) with at least one packet data unit (PDU) session or packet data network (PDN) connection established on a network slice, when a UE establishes a first PDU session or a first PDN connection associated with the network slice, or a last PDU session or a last PDN connection associated with the network slice is released,

transmit, to a network slice admission control function (NSACF) entity, an update request message for the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice, and

receive, from the NSACF entity, an update response message indicating whether the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice reaches a maximum number of UEs with the at least one PDU session or PDN connection for the network slice.

10 . The network entity of claim 9 , wherein the update request message includes single-network slice selection assistance information (S-NSSAI), an identifier of a UE, and an update flag, and

wherein the update flag indicates whether to increase or decrease the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice.

11 . The network entity of claim 10 , wherein the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice is increased if:

the update flag indicates to increase the number of the at least one UE,

the identifier of the UE is not included in a list of UEs associated with the S-NSSAI, and

the number of the at least one UE is less than the maximum number of UEs.

12 . The network entity of claim 9 , wherein the at least one processor is further configured to:

transmit, to a network repository function (NRF) entity, a network function discovery request message for the NSACF entity, and

receive, from the NRF entity, a network function discovery response message including a network function profile of the NSACF entity,

wherein the network function discovery request message includes an NSACF service capability indicator to support monitoring and controlling the number of at least one UE with the at least one PDU session or PDN connection established on the network slice.

13 . A network slice admission control function (NSACF) entity in a wireless communication system, the NSACF entity comprising:

a transceiver; and

at least one processor coupled to the transceiver and configured to:

receive, from a network entity, an update request message for a number of at least one user equipment (UE) with at least one packet data unit (PDU) session or packet data network (PDN) connection established on a network slice, when a UE establishes a first PDU session or a first PDN connection associated with the network slice, or a last PDU session or a last PDN connection associated with the network slice is released, and

in response to receiving the update request message from the network entity, transmit, to the network entity, an update response message indicating whether the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice reaches a maximum number of UEs with the at least one PDU session or PDN connection for the network slice.

14 . The NSACF entity of claim 13 , wherein the update request message includes single-network slice selection assistance information (S-NSSAI), an identifier of a UE, and an update flag, and

wherein the update flag indicates whether to increase or decrease the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice.

15 . The NSACF entity of claim 14 , wherein the at least one processor is further configured to increase the number of the at least one UE with the at least one PDU session or PDN connection established on the network slice if:

the update flag indicates to increase the number of the at least one UE,

the identifier of the UE is not included in a list of UEs associated with the S-NSSAI, and

the number of the at least one UE is less than the maximum number of UEs.

16 . The NSACF entity of claim 13 , wherein the at least one processor is further configured to:

transmit, to a network repository function (NRF) entity, a network function register request message, and

receive, from the NRF entity, a network function response message,

wherein the network function register message includes an NSACF service capability indicator to support monitoring and controlling the number of at least one UE with the at least one PDU session or PDN connection established on the network slice.