Handover method and apparatus

A method for data transmission in a handover process, wherein the method comprises:

• configuring, by a source radio access network (RAN) device for a terminal device, a first mapping relationship between downlink transmission of a quality of service (QoS) flow and a first data radio bearer (DRB) and a second mapping relationship between uplink transmission of the QoS flow and a second DRB;
• notifying, by the source RAN device by using air interface signaling, the terminal device of the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• receiving, by a target radio access network (RAN) device, a handover request message from the source RAN device or from a core network (CN) device,
• wherein the handover request message comprises the first mapping relationship between the downlink transmission of the QoS flow and the first DRB and the second mapping relationship between the uplink transmission of the QoS flow and the second DRB,
• wherein the first mapping relationship between the downlink transmission of the QoS flow and the first DRB is different from the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• in a process in which the terminal device is handed over from the source RAN device to the target RAN device, receiving, by the target RAN device, data that is of the QoS flow, that is on the source RAN device, and that is forwarded by the source RAN device;
• sending, by the target RAN device, downlink data based on the first mapping relationship between the downlink transmission of the QoS flow and the first DRB;
• and
• receiving, by the target RAN device, uplink data based on the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• wherein:
• the first mapping relationship between the downlink transmission of the QoS flow and the first DRB comprises a mapping relationship between a QoS flow identifier (QFI) of the QoS flow and a DRB identifier (ID) of the first DRB;
• and
• the second mapping relationship between the uplink transmission of the QoS flow and the second DRB comprises a mapping relationship between the QFI of the QoS flow and a DRB ID of the second DRB.

A mobile communication system, wherein the mobile communication system comprises:

• a first network device and a second network device, wherein:
• the first network device is a source radio access network (RAN) device, wherein the source RAN device comprises at least one first processor, one or more first non-transitory memories, and a first transceiver, wherein:
• the at least one first processor is communicatively coupled to the first transceiver, wherein the one or more first non-transitory memories store first instructions for execution by the at least one first processor, wherein the first instructions instruct the at least one first processor to:
• configure, for a terminal device, a first mapping relationship between downlink transmission of a quality of service (QoS) flow and a first data radio bearer (DRB) and a second mapping relationship between uplink transmission of the QoS flow and a second DRB;
• and
• notify, by using air interface signaling, the terminal device of the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• the first instructions further instruct the at least one first processor to instruct the first transceiver to send a handover request message to a target RAN device or send a handover requirement message to a core network (CN) device,
• wherein the handover request message or the handover requirement message comprises the first mapping relationship between the downlink transmission of the QoS flow and the first DRB and the second mapping relationship between the uplink transmission of the QoS flow and the second DRB,
• wherein the first mapping relationship between the downlink transmission of the QoS flow and the first DRB is different from the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• and
• the first instructions further instruct the at least one first processor to instruct the first transceiver to forward data of the QoS flow on the source RAN device to the target RAN device in a process in which a terminal device is handed over from the source RAN device to the target RAN device;
• and
• the second network device is a target RAN device, wherein the target RAN device comprises at least one second processor, one or more second non-transitory memories, and a second transceiver, wherein:
• the at least one second processor is communicatively coupled to the second transceiver, wherein the one or more second non-transitory memories store second instructions for execution by the at least one second processor, wherein the second instructions instruct the at least one second processor to instruct the second transceiver to receive the handover request message from the source RAN device or from the CN device;
• the second instructions further instruct the at least one second processor to instruct the second transceiver to receive, in a process in which the terminal device is handed over from the source RAN device to the target RAN device, data that is of the QoS flow, that is on the source RAN device, and that is forwarded by the source RAN device;
• the second instructions further instruct the at least one second processor to instruct the second transceiver to send downlink data based on the first mapping relationship between the downlink transmission of the QoS flow and the first DRB;
• and
• the second instructions further instruct the at least one second processor to instruct the second transceiver to receive uplink data based on the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• wherein:
• the first mapping relationship between the downlink transmission of the QoS flow and the first DRB comprises a mapping relationship between a QoS flow identifier (QFI) of the QoS flow and a DRB identifier (ID) of the first DRB;
• and
• the second mapping relationship between the uplink transmission of the QoS flow and the second DRB comprises a mapping relationship between the QFI of the QoS flow and a DRB ID of the second DRB.

A non-transitory computer-readable storage medium storing computer instructions, that when executed by one or more first processors, cause the one or more first processors to perform operations comprising:

• configuring, by a source radio access network (RAN) device for a terminal device, a first mapping relationship between downlink transmission of a quality of service (QoS) flow and a first data radio bearer (DRB) and a second mapping relationship between uplink transmission of the QoS flow and a second DRB;
• notifying, by the source RAN device by using air interface signaling, the terminal device of the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• sending, by the source RAN device, a handover request message to a target RAN device, or sending, by the source RAN device, a handover requirement message to a core network (CN) device,
• wherein the handover request message or the handover requirement message comprises the first mapping relationship between the downlink transmission of the QoS flow and the first DRB and the second mapping relationship between the uplink transmission of the QoS flow and the second DRB,
• wherein the first mapping relationship between the downlink transmission of the QoS flow and the first DRB is different from the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• and
• forwarding, by the source RAN device, data of the QoS flow on the source RAN device to the target RAN device in a process in which a terminal device is handed over from the source RAN device to the target RAN device;
• wherein the computer instructions, that when executed by one or more second processors, further cause the one or more second processors to perform operations comprising:
• receiving, by the target RAN device, the handover request message from the source RAN device or from the CN device, wherein the handover request message comprises the first mapping relationship between the downlink transmission of the QoS flow and the first DRB and the second mapping relationship between the uplink transmission of the QoS flow and the second DRB, wherein the first mapping relationship between the downlink transmission of the QoS flow and the first DRB is different from the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• in a process in which the terminal device is handed over from the source RAN device to the target RAN device, receiving, by the target RAN device, the data that is of the QoS flow, that is on the source RAN device, and that is forwarded by the source RAN device;
• sending, by the target RAN device, downlink data based on the first mapping relationship between the downlink transmission of the QoS flow and the first DRB;
• and
• receiving, by the target RAN device, uplink data based on the second mapping relationship between the uplink transmission of the QoS flow and the second DRB;
• wherein:
• the first mapping relationship between the downlink transmission of the QoS flow and the first DRB comprises a mapping relationship between a QoS flow identifier (QFI) of the QoS flow and a DRB identifier (ID) of the first DRB;
• and
• the second mapping relationship between the uplink transmission of the QoS flow and the second DRB comprises a mapping relationship between the QFI of the QoS flow and a DRB ID of the second DRB.