Data transmission method and communication apparatus

A data transmission method, wherein the method comprises:

• sending, by a first access network device, a handover request message to a second access network device, wherein the handover request message carries an identifier of a terminal device;
• receiving, by the first access network device and from the second access network device, a handover acknowledgment message to configure the terminal device to transmit a first data packet to the second access network device, wherein
• the first data packet is a data packet that has been sent by the terminal device to the first access network device before the terminal device successfully accesses the second access network device, and
• the first data packet is carried on a first data radio bearer (DRB) of unacknowledged mode (UM) radio link control (RLC);
• and
• sending, by the first access network device, first information to the terminal device, wherein the first information indicates the terminal device to be handed over and connected to the second access network device, and the first information comprises the handover acknowledgment message.

A data transmission apparatus, wherein the apparatus comprises:

• at least one processor;
• and
• a memory coupled to the at least one processor and configured to store executable instructions for execution by the at least one processor to instruct the at least one processor to:
• receive first information from a first access network device, wherein the first information indicates the apparatus to be handed over and connected to a second access network device;
• and
• send a first data packet to the second access network device after the apparatus successfully accesses the second access network device, wherein the first data packet is a data packet that has been sent by the apparatus to the first access network device before the apparatus successfully accesses the second access network device, and the first data packet is carried on a first data radio bearer (DRB) of unacknowledged mode (UM) radio link control (RLC).

A data transmission apparatus, wherein the apparatus comprises:

• at least one processor;
• and
• a memory coupled to the at least one processor and configured to store executable instructions for execution by the at least one processor to instruct the at least one processor to:
• send a handover request message to a second access network device, wherein the handover request message carries an identifier of a terminal device;
• receive, from the second access network device, a handover acknowledgment message to configure the terminal device to transmit a first data packet to the second access network device, wherein
• the first data packet is a data packet that has been sent by the terminal device to the apparatus before the terminal device successfully accesses the second access network device, and
• the first data packet is carried on a first data radio bearer (DRB) of unacknowledged mode (UM) radio link control (RLC);
• and
• send first information to the terminal device, wherein the first information indicates the terminal device to be handed over and connected to the second access network device, and the first information comprises the handover acknowledgment message.