Data flow transmission method, device, and system

A first relay user equipment, comprising:

• a processor, a memory, and a bus, wherein the processor and the memory are connected to each other by using the bus;
• the processor is configured to:
• obtain position information of a user equipment for which a first network device provides a service;
• determine a quantity of user equipments in a wireless network coverage according to the position information of the user equipment;
• when the quantity of user equipments in the wireless network coverage is less than a first threshold, determine, according to the position information of the user equipment, a quantity of remote user equipments in a first group connected to a relay user equipment, wherein the remote user equipments are user equipments located outside the wireless network coverage;
• when the quantity of the remote user equipments in the first group connected to the relay user equipment is greater than or equal to a second threshold:
• determine to send data to the remote user equipments in a unicast mode;
• and
• trigger the relay user equipment to establish a common data flow bearer;
• when the first network device triggers the first relay user equipment to establish the common data flow bearer with a second network device, establish the common data flow bearer with the second network device, wherein:
• the common data flow bearer is used to carry a data flow transmitted from the second network device to a remote user equipment in a first group;
• the remote user equipment in the first group is connected to the second network device by using the first relay user equipment;
• and
• the first group comprises at least two remote user equipments;
• and
• obtain an identifier of a common data flow before or after the first relay user equipment establishes the common data flow bearer with the second network device, wherein the identifier of the common data flow is used to instruct the first relay user equipment to send data of the common data flow to the remote user equipment in the first group.

A first network device, comprising:

• a processor, a memory, and a bus, wherein the processor and the memory are connected to each other by using the bus;
• the processor is configured to:
• obtain position information of a user equipment for which the first network device provides a service;
• determine a quantity of user equipments in a wireless network coverage according to the position information of the user equipment;
• when the quantity of user equipments in the wireless network coverage is less than a first threshold, determine, according to the position information of the user equipment, a quantity of remote user equipments in a first group connected to a relay user equipment, wherein the remote user equipments are user equipments located outside the wireless network coverage;
• when the quantity of the remote user equipments in the first group connected to the relay user equipment is greater than or equal to a second threshold:
• determine to send data to the remote user equipment in a unicast mode;
• and
• trigger the relay user equipment to establish a common data flow bearer;
• when the first network device triggers a first relay user equipment to establish the common data flow bearer with a second network device, establish the common data flow bearer with the second network device, wherein:
• the common data flow bearer is used to carry a data flow transmitted from the second network device to a remote user equipment in a first group;
• the remote user equipment in the first group is connected to the second network device by using the first relay equipment;
• and
• obtain an identifier of a common data flow before or after the first relay user equipment establishes the common data flow bearer with the second network device, wherein the identifier of the common data flow is used to instruct the first relay user equipment to send data of the common data flow to the remote user in the first group.