Method and device for supporting handover
The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. According to an aspect of the embodiments of the present disclosure, a method for supporting handover is provided, comprising: receiving a message from a central unit control plane entity of a target base station; receiving a data packet from a source base station; and discarding a packet data convergence protocol (PDCP) service data unit (SDU) including the PDCP sequence number (SN) in the received data packet according to the indication of the message.
1. A method performed by a target base station in a communication system, the method comprising:
transmitting, at a central unit-control plane (CU-CP) of the target base station to a central unit-user plane (CU-UP) of the target base station, a bearer context setup request message including configuration information on a data radio bearer (DRB) to setup, the configuration information on the DRB to setup including first information on at least one first quality of service (QoS) flow mapped to the DRB, second information on at least one second QoS flow to be setup for the DRB, and third information indicating a source configuration, wherein the at least one first QoS flow is associated with forwarded data packets sent on the DRB during a handover; and
receiving, at the CU-CP of the target base station from the CU-UP of the target base station, a bearer context setup response message as a response to the bearer context setup request message,
wherein, after the forwarded data packets are processed over the DRB during the handover, the second information is ignored by the CU-UP of the target base station based on the third information indicating the source configuration.
2. The method of claim 1 , further comprising:
receiving, at the CU-CP of the target base station from a CU-CP of a source base station or a core network, a handover request message including information on a first mapping of QoS flow to the DRB at the source base station; and
transmitting, at the CU-CP of the target base station to the CU-CP of the source base station, a message as a response to the handover request message including a handover command message for a terminal, the handover command message including information on a second mapping of QoS flow to the DRB at the target base station.
3. The method of claim 2 ,
wherein the at least one first QoS flow is identified based on the information on the first mapping.
4. The method of claim 2 ,
wherein the information on the second mapping indicates that the at least one second QoS flow identified by the second information is mapped to the DRB.
5. The method of claim 1 , wherein the bearer context setup response message includes data forwarding information for the DRB.
6. A method performed by a target base station in a communication system, the method comprising:
receiving, at a central unit-user plane (CU-UP) of the target base station from a central unit-control plane (CU-CP) of the target base station, a bearer context setup request message including configuration information on a data radio bearer (DRB) to setup, the configuration information on the DRB to setup including first information on at least one first quality of service (QoS) flow mapped to the DRB, second information on at least one second QoS flow to be setup for the DRB, and third information indicating a source configuration, wherein the at least one first QoS flow is associated with forwarded data packets sent on the DRB during a handover;
transmitting, at the CU-UP of the target base station to the CU-CP of the target base station, a bearer context setup response message as a response to the bearer context setup request message;
receiving, at the CU-UP of the target base station from a CU-UP of a source base station, the forwarded data packets; and
processing the forwarded data packets over the DRB based on the configuration information on the DRB,
wherein the second information is ignored by the CU-UP of the target base station based on the third information indicating the source configuration.
7. The method of claim 6 , further comprising:
generating data forwarding information for the DRB,
wherein the bearer context setup response message includes the data forwarding information.
8. The method of claim 6 , further comprising:
receiving, at the CU-UP of the target base station from a core network, new data packets for a new DRB,
wherein the forwarded data packets are first processed, before the new data packets are transmitted to a terminal on the new DRB.
9. A target base station in a communication system, the target base station comprising:
a transceiver; and
a controller coupled with the transceiver and configured to:
transmit, at a central unit-control plane (CU-CP) of the target base station to a central unit-user plane (CU-UP) of the target base station, a bearer context setup request message including configuration information on a data radio bearer (DRB) to setup, the configuration information on the DRB to setup including first information on at least one first quality of service (QoS) flow mapped to the DRB, second information on at least one second QoS flow to be setup for the DRB, and third information indicating a source configuration, wherein the at least one first QoS flow is associated with forwarded data packets sent on the DRB during a handover, and
receive, at the CU-CP of the target base station from the CU-UP of the target base station, a bearer context setup response message as a response to the bearer context setup request message,
wherein, after the forwarded data packets are processed over the DRB during the handover, the second information is ignored by the CU-UP of the target base station based on the third information indicating the source configuration.
10. The target base station of claim 9 , wherein the controller is further configured to:
receive, at the CU-CP of the target base station from a CU-CP of a source base station or a core network, a handover request message including information on a first mapping of QoS flow to the DRB at the source base station, and
transmit, at the CU-CP of the target base station to the CU-CP of the source base station, a message as a response to the handover request message including a handover command message for a terminal, the handover command message including information on a second mapping of QoS flow to the DRB at the target base station.
11. The target base station of claim 10 ,
wherein the at least one first QoS flow is identified based on the information on the first mapping.
12. The target base station of claim 10 ,
wherein the information on the second mapping indicates that the at least one second identified by the second information is mapped to the DRB.
13. The target base station of claim 10 , wherein the bearer context setup response message includes data forwarding information for the DRB.
14. A target base station in a communication system, the target base station comprising:
a transceiver; and
a controller coupled with the transceiver and configured to:
receive, at a central unit-user plane (CU-UP) of the target base station from a central unit-control plane (CU-CP) of the target base station, a bearer context setup request message including configuration information on a data radio bearer (DRB) to setup, the configuration information on the DRB to setup including first information on at least one first quality of service (QoS) flow mapped to the DRB, second information on at least one second QoS flow to be setup for the DRB, and third information indicating a source configuration, wherein the at least one first QoS flow is associated with forwarded data packets sent on the DRB during a handover,
transmit, at the CU-UP of the target base station to the CU-CP of the target base station, a bearer context setup response message as a response to the bearer context setup request message,
receive, at the CU-UP of the target base station from a CU-UP of a source base station, the forwarded data packets, and
process the forwarded data packets over the DRB based on the configuration information on the DRB,
wherein the second information is ignored by the CU-UP of the target base station based on the third information indicating the source configuration.
15. The target base station of claim 14 ,
wherein the controller is further configured to generate data forwarding information for the DRB, and
wherein the bearer context setup response message includes the data forwarding information.
16. The target base station of claim 14 ,
wherein the controller is further configured to receive, at the CU-UP of the target base station from a core network, new data packets for a new DRB, and
wherein the forwarded data packets are first processed, before the new data packets are transmitted to a terminal on the new DRB.