Session continuity for 3GPP and non-3GPP interworking
A method for S-NSSAI handling of a 5GS capable UE supporting session continuity between 3GPP and non-3GPP interworking is proposed. The UE maintains a PDN connection/PDU session. The UE performs interworking among S1 mode, N1 mode (including 3GPP and non-3GPP access), and ePDG. The UE associates the existing S-NSSAI with the new PDN connection/PDU session after interworking, no matter whether the S-NSSAI is provided by the network or not. The UE can update the S-NSSAI upon receipt of new value from the network. When interwork to N1 mode, the UE applies the S-NSSAI.
1. A method, comprising:
maintaining an existing Packet data network (PDN) connection by a user equipment (UE) in evolved packet core (EPC), wherein the existing PDN connection is established over a first access type and is associated with a single network slice selection assistance information (S-NSSAI);
performing a first handover for the existing PDN connection over the first access type to a new PDN connection over a second access type in EPC;
associating the new PDN connection over the second access type with the S-NSSAI of the existing PDN connection; and
performing a second handover for the new PDN connection over the second access type in EPC to a protocol data unit (PDU) session in 5G evolved Packet Core (5GC).
2. The method of claim 1 , wherein the first access type is non-3GPP access type, and wherein the second access type is 3GPP access type.
3. The method of claim 1 , wherein the first access type is 3GPP access type, and the second access type is non-3GPP access type.
4. The method of claim 1 , wherein the UE associated the S-NSSAI to the new PDN connection when an evolved Packet Data Gateway (ePDG) in EPC does not provide any S-NSSAI to the new PDN connection.
5. The method of claim 1 , wherein the S-NSSAI of the new PDN connection is updated by an evolved Packet Data Gateway (ePDG) in EPC.
6. The method of claim 1 , wherein the UE applies the associated S-NSSAI when performing the second handover to N1 mode in 5GC.
7. The method of claim 1 , wherein the UE does not perform the second handover if the S-NSSAI is not included in an allowed NSSAI list of a target access in 5GC.
8. A User Equipment (UE), comprising:
a connection handling circuit that maintains an existing Packet data network (PDN) connection in evolved packet core (EPC), wherein the existing PDN connection is established over a first access type and is associated with a single network slice selection assistance information (S-NSSAI);
an intersystem handling circuit that performs a first handover for the existing PDN connection over the first access type to a new PDN connection over a second access type in EPC; and
a controller that associates the new PDN connection over the second access type with the S-NSSAI of the existing PDN connection, wherein the UE performs a second handover for the new PDN connection over the second access type in EPC to a protocol data unit (PDU) session in 5G evolved Packet Core (5GC).
9. The UE of claim 8 , wherein the first access type is non-3GPP access type, and wherein the second access type is 3GPP access type.
10. The UE of claim 8 , wherein the first access type is 3GPP access type, and the second access type is non-3GPP access type.
11. The UE of claim 8 , wherein the UE associated the S-NSSAI to the new PDN connection when an evolved Packet Data Gateway (ePDG) in EPC does not provide any S-NSSAI to the new PDN connection.
12. The UE of claim 8 , wherein the S-NSSAI of the new PDN connection is updated by an evolved Packet Data Gateway (ePDG) in EPC.
13. The UE of claim 8 , wherein the UE applies the associated S-NSSAI when performing the second handover to N1 mode in 5GC.