De-registration method in wireless communication system and device therefor
An aspect of the present invention relates to a UE-initiated de-registration method by an AMF in a wireless communication system, and comprises the steps of: receiving, from UE, a de-registration request message that requests de-registration, wherein the de-registration request message includes de-registration type information and first access type information indicating a target access to which the de-registration is to be applied; requesting, when the UE has an established protocol data unit (PDU) session through the target access, an SMF to release the established PDU session; and transmitting a de-registration accept message to the UE depending on the de-registration type.
1. A method for performing, by an access and mobility management function (AMF), a deregistration procedure in a wireless communication system, the method comprising:
receiving, from a user equipment (UE), a first message for requesting a deregistration, wherein the first message includes first information related to a type of the deregistration and second information for a target access related to the deregistration,
wherein the second information is information for whether the target access is a 3rd Generation Partnership Project (3GPP) access or a non-3GPP access, or both the 3GPP access and the non-3GPP access;
requesting, when the UE has a protocol data unit (PDU) session established through the target access, to a session management function (SMF) to release the established PDU session;
determining whether to transmit a third message to the UE based on the first information; and
transmitting, to a radio access network (RAN), a fourth message for releasing an N2 signaling connection, the fourth message including third information for cause set to the deregistration, wherein:
when the first information represents that a request of the deregistration is due to a switch-off of the UE, not transmitting the third message,
when the first information does not represent that the request of the deregistration is due to the switch-off of the UE, transmitting the third message, and
the fourth message is transmitted when the target access is the 3GPP access or both the 3GPP access and the non-3GPP access and there is the N2 signaling connection between the UE and the RAN.
2. The method of claim 1 , further comprising:
when the target access is both the 3GPP access and the non-3GPP access, and there is the N2 signaling connection between the UE and a non-3GPP interworking function (N3IWF),
transmitting, to the N3IWF, the fourth message in which the cause is configured to the deregistration to release the N2 signaling connection.
3. The method of claim 1 , wherein the requesting of the release of the established PDU session includes transmitting, to the SMF, a fifth message for requesting the release of the established PDU session.
4. The method of claim 3 , wherein the fifth message includes a subscriber permanent identifier (SUPI) corresponding to the UE and an identifier of a PDU session to be released.
5. The method of claim 4 , wherein the SMF is a network entity that releases an Internet protocol (IP) address and/or prefix allocated to the PDU session to be released, and releases user plane resources corresponding to the PDU session to be released.
6. The method of claim 4 , wherein:
the SMF is a network entity that transmits an N4 session release request message for requesting the release of an N4 session to a user plane function (UPF), and
the UPF is a network entity that releases all tunnel resources and contexts associated with the N4 session.
7. The method of claim 1 , further comprising invoking, when there is a policy control function (PCF) associated with the UE, an operation for deleting an association between the UE and the PCF.
8. An access and mobility management function (AMF) configured to perform a deregistration procedure in a wireless communication system, the AMF comprising:
a transceiver configured to transmit and receive radio signals;
at least one processor; and
at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations comprising:
receiving, from a user equipment (UE), a first message for requesting a deregistration, wherein the first message includes first information related to a type of the deregistration and second information for a target access related to the deregistration,
wherein the second information is information for whether the target access is a 3rd Generation Partnership Project (3GPP) access or a non-3GPP access, or both the 3GPP access and the non-3GPP access;
requesting, when the UE has a protocol data unit (PDU) session established through the target access, to a session management function (SMF) to release the established PDU session;
determining whether to transmit a third message to the UE based on the first information; and
transmitting, to a radio access network (RAN), a fourth message for releasing an N2 signaling connection, the fourth message including third information for cause set to the deregistration, wherein:
when the first information represents that a request of the deregistration is due to a switch-off of the UE, not transmitting the third message,
when the first information does not represent that the request of the deregistration is due to the switch-off of the UE, transmitting the third message, and
the fourth message is transmitted when the target access is the 3GPP access or both the 3GPP access and the non-3GPP access and there is the N2 signaling connection between the UE and the RAN.