Relay communication method and apparatus

1. A relay communication method applied to a unidirectional relay scenario, where in the unidirectional relay scenario, an uplink includes a physical channel from a remote terminal device to a relay device and a physical channel from the relay device to a radio access network device, a downlink includes a physical channel from the radio access network device to the remote terminal device, and the method comprising:

receiving, by a first radio access network device, first information sent by a first terminal device, wherein the first information indicates that the first terminal device has limited uplink power;

determining, by the first radio access network device, based on the first information, a second terminal device that provides, in a target cell, a relay service for the first terminal device; and

sending, by the first radio access network device, second information to a second radio access network device, wherein

the second information indicates the second terminal device that provides, in the target cell, the relay service for the first terminal device,

the second radio access network device belongs to the target cell, and

the first terminal device requires connection to the target cell, wherein

the method further comprises:

receiving, by the first radio access network device, third information and fourth information sent by the second radio access network device, wherein

the third information includes a target cell identifier and a first cell radio network temporary identifier (C-RNTI) allocated to the first terminal device, and

the fourth information includes the target cell identifier, a second C-RNTI allocated to the second terminal device, and a random access resource;

sending, by the first radio access network device, the third information to the first terminal device; and

sending, by the first radio access network device, the fourth information to the second terminal device.

2. The method according to claim 1 , further comprising:

receiving, by the first radio access network device, fifth information sent by the first terminal device, wherein the fifth information indicates the second terminal device that provides, in the target cell, the relay service for the first terminal device.

3. The method according to claim 1 , wherein

the second information comprises an identifier of the first terminal device and an identifier of the second terminal device, or

the second information comprises the identifier of the second terminal device.

4. The method according to claim 1 , wherein the second information comprises fifth information indicating that the second terminal device provides, in the target cell, the relay service for the first terminal device.

5. The method according to claim 1 , wherein the third information and the fourth information are contained in a same interface message sent by the second radio access network device to the first radio access network device.

6. The method according to claim 1 , wherein

the first radio access network device receives the first information and a measurement report sent by the first terminal device, and

the first radio access network device determines, based on the first information and the measurement report, the second terminal device.

7. An apparatus, comprising:

a processor; and

a memory storing instructions that, when executed by the processor, cause the apparatus to:

receive first information sent by a first terminal device, wherein the first information indicates that the first terminal device has limited uplink power;

determine, based on the first information, a second terminal device that provides, in a target cell, a relay service for the first terminal device; and

send second information to a first radio access network device, wherein

the second information indicates the second terminal device that provides, in the target cell, the relay service for the first terminal device,

the first radio access network device belongs to the target cell, and

the first terminal device requires connection to the target cell, wherein

the apparatus is further caused to:

receive third information and fourth information sent by the first radio access network device, wherein

the third information includes a target cell identifier and a first cell radio network temporary identifier (C-RNTI) allocated to the first terminal device, and

the fourth information includes the target cell identifier, a second C-RNTI allocated to the second terminal device, and a random access resource; and

send the third information to the first terminal device; and

send the fourth information to the second terminal device.

8. The apparatus according to claim 7 , wherein the apparatus is further caused to:

receive fifth information sent by the first terminal device, wherein the fifth information indicates the second terminal device that provides, in the target cell, the relay service for the first terminal device.

9. The apparatus according to claim 7 , wherein

the second information comprises an identifier of the first terminal device and an identifier of the second terminal device, or

the second information comprises the identifier of the second terminal device.

10. The apparatus according to claim 7 , wherein the second information includes fifth information indicating that the second terminal device provides, in the target cell, the relay service for the first terminal device.

11. The apparatus according to claim 7 , wherein the third information and the fourth information are contained in a same interface message sent by the first radio access network device to a second radio access network device.

12. The apparatus according to claim 7 , wherein the apparatus is applied to a unidirectional relay scenario, where in the unidirectional relay scenario, an uplink includes a physical channel from a remote terminal device to a relay device and a physical channel from the relay device to a radio access network device, and a downlink includes a physical channel from the radio access network device to the remote terminal device.

13. A non-transitory computer readable storage medium storing computer readable instructions that, when executed by a processor of a computer, cause the computer to provide execution comprising:

receiving first information sent by a first terminal device, wherein the first information indicates that the first terminal device has limited uplink power; and

sending second information to a first radio access network device, wherein

the second information indicates a second terminal device that provides, in a target cell, a relay service for the first terminal device,

the first radio access network device belongs to the target cell, and

the first terminal device requires connection to the target cell, wherein

the computer is further caused to provide execution comprising:

receiving third information and fourth information sent by the first radio access network device, wherein

the third information comprises a target cell identifier and a first cell radio network temporary identifier (C-RNTI) allocated to the first terminal device, and

the fourth information comprises the target cell identifier, a second C-RNTI allocated to the second terminal device, and a random access resource; and

sending the third information to the first terminal device; and

sending the fourth information to the second terminal device.

14. The computer readable storage medium according to claim 13 , wherein the computer is further caused to provide execution comprising:

receiving fifth information sent by the first terminal device, wherein the fifth information indicates the second terminal device that provides, in the target cell, the relay service for the first terminal device.

15. The computer readable storage medium according to claim 13 , wherein

the second information comprises an identifier of the first terminal device and an identifier of the second terminal device, or

the second information comprises the identifier of the second terminal device.

16. The computer readable storage medium according to claim 13 , wherein the second information comprises fifth information indicating that the second terminal device provides, in the target cell, the relay service for the first terminal device.

17. The computer readable storage medium according to claim 13 , wherein the computer readable instructions are applied to a unidirectional relay scenario, where in the unidirectional relay scenario, an uplink includes a physical channel from a remote terminal device to a relay device and a physical channel from the relay device to a radio access network device, and a downlink includes a physical channel from the radio access network device to the remote terminal device.

18. The computer readable storage medium according to claim 13 , wherein the computer is further caused to provide execution comprising:

determining, based on the first information, the second terminal device that provides, in the target cell, the relay service for the first terminal device.

19. The computer readable storage medium according to claim 13 , wherein the third information and the fourth information are contained in a same interface message sent by the first radio access network device to a second radio access network device.