Communication method and communications apparatus to implement a network slice based service in a central unit (CU)-distributed unit (DU) architecture

1. A communication method in a wireless communication system that comprises a central unit (CU) and a plurality of distributed units (DUs), the method comprising:

receiving, by a CU of a radio access network (RAN), an indication of a user equipment- aggregate maximum bit rate (UE-AMBR) from a core network device;

allocating, by the CU, a first portion of the UE-AMBR as a first DU UE-AMBR and a second portion of the UE-AMBR as a second DU UE-AMBR, wherein the first DU UE-AMBR indicates an aggregate maximum bit rate to be enforced by a first DU of the RAN for a terminal device, and the second DU UE-AMBR indicates an aggregate maximum bit rate to be enforced by a second DU of the RAN for the terminal device;

sending, by the CU, to the first DU a first UE context setup request message, wherein the first UE context setup request message comprises an identifier of a first bearer to be established, and indication information of a network slice corresponding to the first bearer, and first indication information indicating the first DU UE-AMBR;

sending, by the CU, to the second DU, a second UE context setup request message, wherein the second UE context setup request message comprises an identifier of a second bearer to be established, and indication information of a network slice corresponding to the second bearer, and second indication information indicating the second DU UE-AMBR;

sending, by the first DU to the CU, a first response message in response to the first UE context setup request message; and

sending, by the second DU to the CU, a second response message in response to the second UE context setup request message.

2. The method according to claim 1 , wherein the method further comprises:

sending, by the CU, a radio resource control (RRC) message to the first DU;

sending, by the first DU, the RRC message to the terminal device, wherein the RRC message comprises an identifier of a successfully established session and an identifier of a successfully established bearer;

receiving, by the first DU, an RRC response message from the terminal device; and

sending, by the first DU, the RRC response message to the CU.

3. The method according to claim 2 , wherein the RRC message is an RRC connection reconfiguration message.

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

sending, by the first DU, a connection setup request message to the CU, wherein the connection setup request message comprises information of network slice supported by the first DU of the RAN; and

sending, by the CU, a connection setup response message to the first DU.

5. The method according to claim 4 , wherein the information of network slice supported by the first DU comprises: an identifier of a tracking area corresponding to at least one cell of the first DU and indication information of network slice supported by the tracking area.

6. The method according to claim 4 , wherein the connection setup request message is a F1 setup request message.

7. The method according to claim 4 , wherein the connection setup request message further comprises a cell identifier of the first DU, and the cell identifier is a cell global ID (CGI), or a physical cell identifier (PCI).

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

sending, by the first DU, a configuration update message to the CU, wherein the configuration update message comprises updated information of network slice supported by the first DU; and

sending, by the CU, a configuration update response message to the first DU.

9. The method according to claim 1 , wherein the indication information of the network slice comprises single network slice selection assistance information (S-NSSAI), and the S-NSSAI comprises slice/service type.

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

sending, by a source network device, a handover request message to the CU; sending, by the CU, a handover request response message to the source network device; and

wherein the source network device comprises one of a source radio access network device, a source access and mobility management network element, or a source CU.

11. The method according to claim 10 , wherein the UE context setup request message further comprises configuration information of the source network device for at least one protocol stack corresponding to the bearer.

12. The method according to claim 11 , wherein the at least one protocol stack comprises at least one of: a Radio Link Control (RLC) protocol stack, a Media Access Control (MAC) protocol stack, or a physical layer (PHY) protocol stack.

13. The method according to claim 10 , further comprising:

sending, by the CU, a path switch request message to a core network device, wherein the path switch request message comprises an identifier of a session successfully established by the CU, or an identifier of a flow that corresponds to a session that is successfully established by the CU; and

sending, by the core network device, a path switch response message to the CU.

14. The method according to claim 1 , wherein the CU comprises an RRC protocol stack function, a Packet Data Convergence Protocol (PDCP) protocol stack function, and an SDAP protocol stack function; and

the first DU comprises an RLC protocol stack function, a MAC protocol stack function, and a PHY protocol stack function.

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

configuring, by an operation, administration and maintenance (OAM) system, the indication information of the network slice supported by the first DU.

16. A wireless communication system, comprising:

a central unit (CU) of a radio access network (RAN), a first distributed unit (DU) and a second DU in a plurality of DUs of the RAN;

the CU comprises:

at least one processor; and

a non-transitory computer-readable storage medium coupled to the at least one processor and storing programming instructions for execution by the at least one processor, the programming instructions instruct the at least one processor to:

receive an indication of a user equipment-aggregate maximum bit rate (UE-AMBR) from a core network device;

allocate a first portion of the UE-AMBR as a first DU UE-AMBR and a second portion of the UE-AMBR as a second DU UE-AMBR, wherein the first DU UE-AMBR indicates an aggregate maximum bit rate to be enforced by a first DU of the RAN for a terminal device, and the second DU UE-AMBR indicates an aggregate maximum bit rate to be enforced by a second DU of the RAN for the terminal device;

send, to the first DU, a first UE context setup request message, wherein the first UE context setup request message comprises an identifier of a first bearer to be established, and indication information of a network slice corresponding to the first bearer, and first indication information indicating the first DU UE AMBR; and

send, to the second DU, a second UE context setup request message, wherein the second UE context setup request message comprises an identifier of a second bearer to be established, and indication information of a network slice corresponding to the second bearer, and second indication information indicating the second DU UE-AMBR;

the first DU comprises:

at least one processor; and

a non-transitory computer-readable storage medium coupled to the at least one processor and storing programming instructions for execution by the at least one processor, the programming instructions instruct the at least one processor to send a first response message in response to the first UE context setup request message to the CU; and

the second DU comprises:

at least one processor; and

a non-transitory computer-readable storage medium coupled to the at least one processor and storing programming instructions for execution by the at least one processor, the programming instructions instruct the at least one processor to send a second response message in response to the second UE context setup request message to the CU.

17. The system according to claim 16 , wherein

the programming instructions further instruct the at least one processor of the CU to send a radio resource control (RRC) message to the first DU;

the programming instructions further instruct the at least one processor of the first DU to send the RRC message to the terminal device, wherein the RRC message comprises an identifier of a successfully established session and an identifier of a successfully established bearer;

receive an RRC response message from the terminal device; and

send the RRC response message to the CU.

18. The system according to claim 16 , wherein the system further comprises an operation, administration and maintenance (OAM) system, the OAM system is adapted to configure the indication information of the network slice supported by the first DU.

19. The system according to claim 16 , wherein the programming instructions further instruct the at least one processor of the first DU to send a connection setup request message to the CU, wherein the connection setup request message comprises information of network slice supported by the first DU; and

the programming instructions further instruct the at least one processor of the CU to send a connection setup response message to the first DU.

20. The system according to claim 19 , wherein the information of network slice supported by the first DU comprises: an identifier of a tracking area corresponding to at least one cell of the first DU and indication information of network slice supported by the tracking area.

21. The system according to claim 19 , wherein the connection setup request message is a F1 setup request message.

22. The system according to claim 16 , wherein

the programming instructions further instruct the at least one processor of the first DU to send a configuration update message to the CU, wherein the configuration update message comprises updated information of network slice supported by the first DU; and

the programming instructions further instruct the at least one processor of the CU to send a configuration update response message to the first DU.

23. The system according to claim 16 , wherein the indication information of the network slice comprises single network slice selection assistance information (S-NSSAI), and the S-NSSAI comprises slice/service type.

24. The system according to claim 16 , wherein the system further comprises a source network device, the source network device is configured to send a handover request message to the CU; and

the programming instructions further instruct the at least one processor of the CU to send a handover request response message to the source network device; and

wherein the source network device comprises one of a source radio access network device, a source access and mobility management network element, or a source CU.

25. The system according to claim 24 , wherein the UE context setup request message further comprises configuration information of the source network device for at least one protocol stack corresponding to the bearer.

26. The system according to claim 25 , wherein the at least one protocol stack comprises at least one of: a Radio Link Control (RLC) protocol stack, a Media Access Control (MAC) protocol stack, or a physical layer (PHY) protocol stack.

27. The system according to claim 16 , wherein the system further comprises a core network device,

the programming instructions further instruct the at least one processor of the CU to send a path switch request message to the core network device, wherein the path switch request message comprises an identifier of a session successfully established by the CU, or an identifier of a flow that corresponds to a session that is successfully established by the CU; and

the core network device is configured to send a path switch response message to the CU.

28. The system according to claim 16 , wherein the CU comprises an RRC protocol stack function, a Packet Data Convergence Protocol (PDCP) protocol stack function, and an SDAP protocol stack function; and

the first DU comprises an RLC protocol stack function, a MAC protocol stack function, and a PHY protocol stack function.