Method and system for HPLMN-based traffic control when UE is registered on different PLMNs

1. A method for establishing a multi-access protocol data unit (MA PDU) session by a home session management function (H-SMF) in a wireless communication network, the method comprising:

receiving, by the H-SMF from a visited SMF (V-SMF) associated with a visited public land mobile network (VPLMN) in the wireless communication network, an MA PDU session establish request message for a user equipment (UE) registered to the VPLMN over 3 rd Generation Partnership Project (3GPP) access and to a home public land mobile network (HPLMN) over non-3GPP access;

identifying, by the H-SMF, whether the MA PDU session is allowed based on information received from a home policy control function (H-PCF); and

transmitting, by the H-SMF to the UE via the VPLMN, a MA PDU session establishment accept message including an access traffic steering, switching and splitting (ATSSS) rules for the MA PDU session, which were derived by the H-SMF.

2. The method of claim 1 , further comprising:

retrieving, via an unified data management (UDM), subscription data of the UE when the identifying whether the MA PDU session is allowed.

3. The method of claim 1 , wherein the MA PDU session establish request message includes an ATSSS capability information of the UE.

4. The method of claim 1 , wherein an N16 interface is used between the V-SMF in the VPLMN and the H-SMF.

5. A method for establishing a multi-access protocol data unit (MA PDU) session by a visited-session management function (V-SMF) in a visited public land mobile network (VPLMN) of a wireless communication network, the method comprising:

receiving, by the V-SMF from a user equipment (UE), a MA PDU session establish request message, wherein the MA PDU session is over 3rd Generation Partnership Project (3GPP) access in the VPLMN and non-3GPP access in a home public land mobile network (HPLMN);

transmitting, by the V-SMF to a home SMF (H-SMF), a MA PDU session establish request message for the UE;

receiving, by the V-SMF from the H-SMF, a response message to the MA PDU session establishment request message for the UE; and

transmitting, by the V-SMF to the UE, a message informing an MA PDU session accept including an access traffic steering, switching and splitting (ATSSS) rules for the MA PDU session, which were derived by the H-SMF based on the response message, so that the UE receives traffic via the non- 3 GPP access from the HPLMN,

wherein the wireless communication network includes the VPLMN and the HPLMN.

6. The method of claim 5 , wherein the MA PDU session establish request message includes an ATSSS capability information of the UE.

7. The method of claim 5 , wherein an N 16 interface is used between the V-SMF and the H-SMF.

8. A method for establishing a multi-access protocol data unit (MA PDU) session of a user equipment (UE) by a home public land mobile network (HPLMN) in a wireless communication network including a visited public land mobile network (VPLMN) and the HPLMN, the method comprising:

receiving, by the HPLMN from a visited SMF (V-SMF) associated with the VPLMN, an MA PDU session establish request message for the UE;

identifying, by the HPLMN, whether the MA PDU session is allowed based on a subscriber data and home operator policy information; and

transmitting, by the HPLMN to the UE via the VPLMN, a MA PDU session establishment accept message including an access traffic steering, switching and splitting (ATSSS) rules for the MA PDU session, which were derived by a home session management function (H-SMF),

wherein the MA PDU session request indicates the VPLMN access over 3rd Generation Partnership Project (3GPP) access and the HPLMN access over a non-3GPP access in the HPLMN.

9. The method of claim 8 , wherein the subscriber data is stored in an unified data management (UDM) of the HPLMN.

10. The method of claim 8 , wherein the home operator policy information is stored in a home policy control function (H-PCF) of the HPLMN.

11. The method of claim 8 , wherein a home user plane function (H-UPF) in the HPLMN is an anchor point between the H-UPF and a visited User Plane Function (V-UPF).

12. The method of claim 8 , wherein the MA PDU session establish request message includes an ATSSS capability information of the UE.

13. The method of claim 8 , wherein an N 16 interface is used between the V-SMF and the H-SMF.

14. The method of claim 8 , wherein an N 11 interface is used between the V-SMF in the VPLMN and a home user plane function (H-UPF) in the HPLMN.

15. The method of claim 8 , wherein traffic for the non-3GPP access for the UE is transmitted from a home user plane function (H-UPF) to the UE over a non- 3 GPP access network.

16. A method for transmitting traffic to a user equipment (UE) by a visited public land mobile network (VPLMN) in a wireless communication network including a home public land mobile network (HPLMN) and the VPLMN, the method comprising:

receiving, by the VPLMN from the UE, a multi-access protocol data unit (MA PDU) session establish request message;

transmitting, by the VPLMN to the HPLMN, an MA PDU session establish request message for the UE;

receiving, by the VPLMN from a home session management function (H-SMF) in the HPLMN, a response message to the MA PDU session establishment request message for the UE; and

transmitting, to the UE, a message informing an MA PDU session accept, including an access traffic steering, switching and splitting (ATSSS) rules for the MA PDU session, which were derived by the H-SMF so that the UE receives traffic via non-3rd Generation Partnership Project (non-3GPP) access from the HPLMN,

wherein the MA PDU session request indicates the VPLMN access over 3rd Generation Partnership Project (3GPP) access and the HPLMN access over the non-3GPP access in the HPLMN.

17. The method of claim 16 , wherein the MA PDU session establish request message includes an ATSSS capability information of the UE.

18. The method of claim 16 , wherein an N 16 interface is used between a visited-session management function (V-SMF) in the VPLMN and the H-SMF.