Method for updating PDU session and network side-device

1. A method of updating a Protocol Data Unit (PDU) session, the method being applied to a network-side device, wherein the method comprises:

during a registration procedure initiated after a User Equipment (UE) moves across Public Land Mobile Networks (PLMN) or across systems, determining that the UE has a first PDU session of which an anchor SMF is not in a current PLMN;

determining a Session Management Function V-SMF in a Visited Public Land Mobile Network (VPLMN) for the first PDU session, and updating the first PDU session by using the V-SMF,

wherein the method further comprises:

receiving a registration request of the UE, wherein the registration request carries temporary identifier information of the UE; and

judging, according to the temporary identifier information, whether the UE moves across PLMNs or across systems;

wherein the temporary identifier information is a Global Unique Temporary Identifier (GUTI) of the UE.

2. The method according to claim 1 , further comprising:

determining that the UE has a second PDU session of which the SMF is in the current PLMN, updating the second PDU session.

3. The method according to claim 1 , wherein judging, according to the temporary identifier information, whether the UE moves across PLMNs or across systems comprises:

when the GUTI is a 5G GUTI and a mobile country code (MCC) and a mobile network code (MNC) in the GUT1 are different from those in the current PLMN, determining that the UE moves across PLMNs.

4. The method according to claim 1 , wherein judging, according to the temporary identifier information, whether the UE moves across PLMNs or across systems comprises:

when the GUTI is a Mapped 5G GUTI, determining that the UE moves across systems.

5. The method according to claim 1 , wherein determining that the UE has the first PDU session of which the anchor SMF is not in the current PLMN, comprises:

obtaining an identifier or address of the anchor SMF of the first PDU session, and determining, according to the identifier or address of the anchor SMF, that the anchor SMF of the first PDU session is not in the current PLMN; or

if the first PDU session is a home routed PDU session and the UE is in the VPLMN, then determining that the anchor SMF of the first PDU session is not in the current PLMN.

6. The method according to claim 1 , wherein determining the V-SMF for the first PDU session comprises:

selecting the V-SMF based on one or a combination of the following information: Single Network Slice Selection Assistance Information (S-NSSAI) of the first PDU session; a Data Network Name (DNN) of the first PDU session; an anchor SMF of the first PDU session.

7. The method according to claim 1 , wherein updating the first PDN session by using the V-SMF comprises:

sending, to the V-SMF, a request for creating a Session Management (SM) context, so that the V-SMF sends, to an anchor SMF of the first PDU session, a request for updating the SM context.

8. The method according to claim 4 , wherein updating the first PDN session by using the V-SMF comprises:

sending, to an existing V-SMF in a context of the UE, a request for releasing the SM context, wherein the existing V-SMF is a default V-SMF.

9. The method according to claim 2 , wherein determining that the UE has the second PDU session of which the SMF is in the current PLMN comprises:

obtaining an identifier or address of the anchor SMF of the second PDU session, and determining, according to the identifier or address of the anchor SMF, that the anchor SMF of the second PDU session is in the current PLMN; or

if the second PDU session is a home routed PDU session and the UE is in the Home Public Land Mobile Network (HPLMN), determining that the anchor SMF is in the current PLMN; or

updating the second PDU session comprises sending, to the anchor SMF of the second PDU session, a request for updating a Session Management (SM) context.

10. A network-side device, comprising:

a storage, a processor, a transceiver, and a computer program stored on the storage and executable by the processor, wherein, when the processor executes the computer program, the processor implements following steps:

during a registration procedure initiated after a User Equipment (UE) moves across Public Land Mobile Networks (PLMN) or across systems, determining that the UE has a first PDU session of which an anchor SMF is not in a current PLMN;

determining a Session Management Function V-SMF in a Visited Public Land Mobile Network (VPLMN) for the first PDU session, and updating the first PDN session by using the V-SMF,

wherein the transceiver is configured for receiving a registration request of the UE, wherein the registration request carries temporary identifier information of the UE;

when the processor executes the computer program, the processor further implements the following step:

judging, according to the temporary identifier information, whether the UE moves across PLMNs or across systems;

wherein the temporary identifier information is a Global Unique Temporary Identifier (GUTI) of the UE.

11. The network-side device according to claim 10 , wherein when the processor executes the computer program, the processor further implements the following step:

determining that the UE has a second PDU session of which the SMF is in the current PLMN, updating the second PDU session.

12. The network-side device according to claim 10 , wherein when the processor executes the computer program, the processor further implements the following step:

when the GUTI is a 5G GUTI and a mobile country code (MCC) and a mobile network code (MNC) in the GUT1 are different from those in the current PLMN, determining that the UE moves across PLMNs.

13. The network-side device according to claim 10 , wherein when the processor executes the computer program, the processor further implements the following step:

when the GUTI is a Mapped 5G GUTI, determining that the UE moves across systems.

14. The network-side device according to claim 10 , wherein when the processor executes the computer program, the processor further implements the following steps:

obtaining an identifier or address of the anchor SMF of the first PDU session, and determining, according to the identifier or address of the anchor SMF, that the anchor SMF of the first PDU session is not in the current PLMN; or

if the first PDU session is a home routed PDU session and the UE is in the VPLMN, then determining that the anchor SMF of the first PDU session is not in the current PLMN.

15. The network-side device according to claim 10 , wherein when the processor executes the computer program, the processor further implements the following step:

selecting the V-SMF based on one or a combination of the following information: Single Network Slice Selection Assistance Information (S-NSSAI) of the first PDU session; a Data Network Name (DNN) of the first PDU session; an anchor SMF of the first PDU session.

16. The network-side device according to claim 10 , wherein the transceiver is further configured for:

sending, to the V-SMF, a request for creating a Session Management (SM) context, so that the V-SMF sends, to an anchor SMF of the first PDU session, a request for updating the SM context.

17. The network-side device according to claim 13 , wherein the transceiver is further configured for:

sending, to an existing V-SMF in a context of the UE, a request for releasing the SM context, wherein the existing V-SMF is a default V-SMF.

18. The network-side device according to claim 11 , wherein when the processor executes the computer program, the processor further implements the following step:

obtaining an identifier or address of the anchor SMF of the second PDU session, and determining, according to the identifier or address of the anchor SMF, that the anchor SMF of the second PDU session is in the current PLMN; or

if the second PDU session is a home routed PDU session and the UE is in the Home Public Land Mobile Network (HPLMN), determining that the anchor SMF is in the current PLMN; or

the transceiver is further configured for sending, to the anchor SMF of the second PDU session, a request for updating a Session Management (SM) context.