Apparatus and method for supporting handover in a wireless communication system
The present disclosure relates to a pre-5 th -Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4 th -Generation (4G) communication system such as Long Term Evolution (LTE). The present invention provides a method for supporting handover, comprising the steps of: informing, by a source base station, a core network whether a direct data forwarding path is available; deciding, by the core network, whether to use direct data forwarding or indirect data forwarding; informing, by the core network, a target base station of information about the direct data forwarding or indirect data forwarding; allocating, by the target base station, data forwarding tunnel information, the target base station allocating the data forwarding tunnel information according to the received information about the direct data forwarding or indirect data forwarding; transmitting, by the target base station, the allocated data forwarding tunnel information to the core network; and informing, by the core network, the source base station of the data forwarding tunnel information. With the present invention, different data forwarding methods are supported to prevent data loss and ensure service continuity.
1. A method performed by an access control and mobility management function (AMF) in a wireless communication system, the method comprising:
receiving, from a source radio access network (RAN) node, a handover required message for a handover from the source RAN node to a target RAN node including a source-to-target transparent container, wherein the source-to-target transparent container includes protocol data unit (PDU) session information; and
transmitting, to the source RAN node, a handover command message,
wherein the PDU session information includes:
an identifier of a PDU session, and
information on one or more quality of service (QoS) flows in the PDU session,
wherein the handover command message includes information on at least one QoS flow in the PDU session, and
wherein a data forwarding associated with the at least one QoS flow is performed for the target RAN node.
2. The method of claim 1 ,
wherein the handover required message further includes information for indicating whether a direct forwarding between the source RAN node and the target RAN node is available or not,
wherein the handover command message further includes forwarding tunnel information,
wherein, in case of the direct data forwarding, the forwarding tunnel information comprises tunnel information received by the target RAN node, and
wherein, in case of an indirect data forwarding, the forwarding tunnel information comprises tunnel information allocated by a user plane function (UPF) entity.
3. The method of claim 1 ,
wherein the data forwarding for the at least one QoS flow is performed based on the forwarding tunnel information, and
wherein the forwarding tunnel information includes an address of a transport layer and a tunnel endpoint ID (TEID).
4. The method of claim 1 , wherein the method further comprising:
transmitting, to the target RAN node, a handover request message, and
receiving, from the target RAN node, a handover request acknowledge message including uplink tunnel information for a data radio bearer (DRB),
wherein the handover request acknowledge message indicates that the target RAN node requests uplink data forwarding for the DRB.
5. The method of claim 1 , further comprising:
transmitting, to the target RAN node, a handover request message including the source-to-target transparent container; and
receiving, from the target RAN node, a handover request acknowledge message including the information on the at least one QoS flow and the forwarding tunnel information for the PDU session,
wherein the data forwarding associated with the at least one QoS flow is accepted by the target RAN node.
6. The method of claim 1 ,
wherein the source-to-target transparent container further includes mapping information between a QoS flow and a data radio bearer (DRB), and
wherein the PDU session information further includes an indicator for indicating that the source RAN node proposes a data forwarding of data for each of the one or more QoS flows.
7. The method of claim 1 , wherein the information indicating the direct forwarding is available or not is indicated based on a presence of internet protocol, IP, connectivity.
8. The method of claim 1 , further comprising:
transmitting, to the target RAN node, a handover request message; and
receiving, from the target RAN node, a handover request acknowledge message including downlink tunnel information for a data radio bearer, DRB,
wherein the handover request acknowledge message indicates that the target RAN node accepts downlink data forwarding for the DRB.
9. The method of claim 1 , further comprising:
transmitting, to a target AMF entity which is different from the AMF entity, information indicating whether a direct data forwarding is available or not; and
receiving, from the target AMF entity, forwarding tunnel information,
wherein the AMF entity is associated with the source RAN node and the target AMF entity is associated with the target RAN node.
10. The method of claim 1 , further comprising:
transmitting, to a session management function (SMF) entity, a request message including the information on the at least one QoS flow; and
receiving, from the SMF entity, a response message including tunnel information based on request message.
11. The method of claim 1 , further comprising:
transmitting, to a session management function (SMF) entity, a request message including the identifier of the PDU session; and
receiving, from the SMF entity, a response message including the identifier of the PDU session and information for indicating whether a direct data forwarding is available or not.
12. An apparatus of an access control and mobility management function (AMF) in a wireless communication system, the AMF comprising:
a transceiver; and
at least one processor coupled to the transceiver and configured to:
receive, from a source radio access network (RAN) node, a handover required message for a handover from the source RAN node to a target RAN node including a source-to-target transparent container, wherein the source-to-target transparent container includes protocol data unit (PDU) session information, and
transmit, to the source RAN node, a handover command message,
wherein the PDU session information includes:
an identifier of a PDU session, and
information on one or more quality of service (QoS) flows in the PDU session,
wherein the handover command message includes information on at least one QoS flow in the PDU session, and
wherein a data forwarding associated with the at least one QoS flow is performed for the target RAN node.
13. The server apparatus of claim 12 ,
wherein the handover required message further includes information for indicating whether a direct forwarding between the source RAN node and the target RAN node is available or not,
wherein the handover command message further includes forwarding tunnel information,
wherein, in case of the direct data forwarding, the forwarding tunnel information comprises tunnel information received by the target RAN node, and
wherein, in case of an indirect data forwarding, the forwarding tunnel information comprises tunnel information allocated by a user plane function (UPF) entity.
14. The apparatus of claim 12 , wherein the at least one processor is further configured to:
transmit, to the target RAN node, a handover request message including the source-to-target transparent container, and
receive, from the target RAN node, a handover request acknowledge message including the information on the at least one QoS flow and the forwarding tunnel information for the PDU session,
wherein the data forwarding associated with the at least one QoS flow is accepted by the target RAN node.
15. The server apparatus of claim 12 ,
wherein the source-to-target transparent container further includes mapping information between a QoS flow and a data radio bearer (DRB), and
wherein the PDU session information further includes an indicator for indicating that the source RAN node proposes a data forwarding of data for each of the one or more QoS flows.
16. The apparatus of claim 12 ,
wherein the data forwarding for the at least one QoS flow is performed based on the forwarding tunnel information, and
wherein the forwarding tunnel information includes an address of a transport layer and a tunnel endpoint ID (TEID).
17. The apparatus of claim 12 , wherein the at least one processor is further configured to:
transmit, to the target RAN node, a handover request message, and
receive, from the target RAN node, a handover request acknowledge message including uplink tunnel information for a data radio bearer (DRB),
wherein the handover request acknowledge message indicates that the target RAN node requests uplink data forwarding for the DRB.
18. The apparatus of claim 12 , wherein the information indicating the direct forwarding is available or not is indicated based on a presence of internet protocol, IP, connectivity.
19. The apparatus of claim 12 ,
wherein the at least one processor is further configured to:
transmit, to the target RAN node, a handover request message, and
receive, from the target RAN node, a handover request acknowledge message including downlink tunnel information for a data radio bearer (DRB),
and
wherein the handover request acknowledge message indicates that the target RAN node accepts downlink data forwarding for the DRB.
20. The apparatus of claim 12 , wherein the at least one processor is further configured to:
transmit, to a target AMF entity which is different from the AMF entity, information indicating whether a direct data forwarding is available or not, and
receive, from the target AMF entity, forwarding tunnel information,
wherein the AMF entity is associated with the source RAN node and the target AMF entity is associated with the target RAN node.
21. The apparatus of claim 12 , wherein the at least one processor is further configured to:
transmit, to a session management function (SMF) entity, a request message including the information on the at least one QoS flow, and
receive, from the SMF entity, a response message including tunnel information based on request message.
22. The apparatus of claim 12 , wherein the at least one processor is further configured to:
transmit, to a session management function (SMF) entity, a request message including the identifier of the PDU session, and
receive, from the SMF entity, a response message including the identifier of the PDU session and information for indicating whether a direct data forwarding is available or not.