Method and apparatus for providing traffic steering in mobile communication system

1. A method of a user plane function (UPF) for providing a multiple access protocol data unit (MA PDU) service to a user equipment (UE) in a mobile communication system, the method comprising:

receiving, from a session management function (SMF), an N4 rule including a traffic transmission scheme for downlinks (DLs) to the UE, wherein the DLs include a DL of 3 rd generation partnership project (3GPP) access and a DL of non-3GPP access;

in response to a change of an access traffic steering, switching, splitting (ATSSS) rule determined by the UE, receiving, from the UE, a split ratio change report for an updated split ratio for uplink (UL) traffic to the 3GPP access and UL traffic to the non-3GPP access determined by the UE, wherein the ATSSS is related to the N4 rule;

generating an updated traffic counter for counting an amount of UL traffic according to the received split ratio change report; and

transmitting, to the SMF, the split ratio change report.

2. The method of claim 1 , wherein the split ratio change report includes at least one of information on a start point at which a changed ratio of the UL traffic to the 3GPP access or the UL traffic to non-3GPP access is applied.

3. The method of claim 2 , wherein the information on the start point includes at least one of a packet sequence number for identifying a packet or a timestamp for identifying a time point to apply the changed ratio.

4. The method of claim 1 , wherein the N4 rule includes an indicator as to whether the UPF is capable of autonomously changing a data traffic split ratio to the DL, and a user plane usage measurement condition for each access type.

5. The method of claim 4 , further comprising:

identifying the indicator in the N4 rule when a change request of the DL is included in the received split ratio change report; and

when the indicator allows the UPF to autonomously change the data traffic split ratio to the DL, determining the data traffic split ratio to DL traffic for the 3GPP access and DL traffic for the non-3GPP access, based on a split ratio of UL traffic for the 3GPP access and UL traffic for the non-3GPP access included in the split ratio change report.

6. The method of claim 1 , further comprising:

counting a resource usage for a user plane for the UE by using the updated traffic counter.

7. The method of claim 6 , further comprising:

receiving, from the SMF, a new N4 rule or a new traffic monitoring condition;

delivering, to the SMF, the counted resource usage for the user plane; and

recounting resource usage for the user plane based on the new N4 rule or the new traffic monitoring condition.

8. The method of claim 6 , further comprising:

receiving, from the SMF, a notification that the split ratio change report is reflected; and

maintaining the updated traffic counter based on the received notification.

9. A user plane function (UPF) for providing a multiple access protocol data unit (MA PDU) service to a user equipment (UE) in a mobile communication system, the UPF comprising:

a network interface configured to communicate with the UE and other network functions (NF s);

memory; and

at least one processor operably coupled with the network interface and the memory, the at least one processor configured to:

control the network interface to receive, from a session management function (SMF), an N4 rule including a traffic transmission scheme for downlinks (DLs) to the UE, wherein the DLs include a DL of 3 rd generation partnership project (3GPP) access and a DL of non-3GPP access,

in response to a change of an access traffic steering, switching, splitting (ATSSS) rule determined by the UE, control the network interface to receive, from the UE, a split ratio change report for an updated split ratio for uplink (UL) traffic to the 3GPP access and UL traffic to the non-3GPP access determined by the UE, wherein the ATSSS is related to the N4 rule,

generate an updated traffic counter for counting an amount of UL traffic according to the received split ratio change report, and

control the network interface to transmit, to the SMF, the split ratio change report.

10. The UPF of claim 9 , wherein the split ratio change report includes at least one of information on a start point at which a changed ratio of the UL traffic to the 3GPP access or the UL traffic to non-3GPP access is applied.

11. The UPF of claim 10 , wherein the information on the start point includes at least one of a packet sequence number for identifying a packet or a timestamp for identifying a time point to apply the changed ratio.

12. The UPF of claim 9 , wherein the N4 rule includes an indicator as to whether the UPF is capable of autonomously changing a data traffic split ratio to the DL, and a user plane usage measurement condition for each access type.

13. The UPF of claim 12 , wherein the at least one processor is further configured to:

identify the indicator in the N4 rule when a change request of the DL is included in the received split ratio change report, and

when the indicator allows the UPF to autonomously change the data traffic split ratio to the DL, determine the data traffic split ratio to DL traffic for the 3GPP access and DL traffic for the non-3GPP access, based on a split ratio of UL traffic for the 3GPP access and UL traffic for the non-3GPP access included in the split ratio change report.

14. The UPF of claim 9 , wherein the at least one processor is further configured to:

count a resource usage for a user plane for the UE by using the updated traffic counter.

15. The UPF of claim 14 , wherein the at least one processor is further configured to control to:

receive, from the SMF, a new N4 rule or a new traffic monitoring condition through the network interface,

deliver, to the SMF, the counted resource usage for the user plane, and

recount resource usage for the user plane, based on the new N4 rule or the new traffic monitoring condition.

16. The UPF of claim 14 , wherein the at least one processor is further configured to:

control the network interface to receive, from the SMF, a notification that the split ratio change report is reflected, and

maintain the updated traffic counter based on the received notification.