Wireless communications method and device

1. A network device, comprising:

a memory storing code; and

a processor connected to the memory and, when the code is executed, configured to:

determine at least one of a registration mode of a terminal device, a supported registration mode of the terminal device, a support for interworking with an N26 interface by a first system, or a support for interworking without an N26 interface by the first system, wherein the registration mode is a single registration (SR) mode of registration with a single system or a dual registration (DR) mode of registration with dual systems, and a first cell in the first system is accessed by the terminal device;

determine, according to the determined at least one of the registration mode of the terminal device, the supported registration mode of the terminal device, the support for interworking with an N26 interface by the first system, or the support for interworking without an N26 interface by the first system, an allowed procedure for the terminal device to access a second cell in a second system; and

make the terminal device to perform the allowed procedure to establish an access to the second cell,

wherein in response to the registration mode of the terminal device being an SR mode, the determined procedure is a handover procedure or a redirection procedure,

wherein in response to the terminal device keeping a connected state with the first cell, and the first system not supporting interworking with an N26 interface, the determined procedure is the redirection procedure,

wherein the network device is an access network device, and

wherein the processor is configured to determine at least one of the support for interworking with an N26 interface by the first system or the support for interworking without an N26 interface by the first system based on preset information.

2. The network device according to claim 1 , wherein the processor is further configured to cause the network device to receive first information sent by the terminal device, indicative of at least one of the registration mode or the supported registration mode of the terminal device.

3. The network device according to claim 2 , wherein the first information is carried in a registration message or a location update message.

4. The network device according to claim 1 , wherein the processor is further configured to cause the network device to receive second information sent by a second network device indicative of the registration mode of the terminal device.

5. The network device according to claim 4 , wherein the processor is further configured to after the first cell is accessed by the terminal device, cause the network device to send a subscription notification to the second network device,

wherein the subscription notification instructs the second network device to notify the network device after the terminal device registers with the second system, and

the second information indicates that the registration mode of the terminal device is a DR mode by indicating that the terminal device has registered with the second system.

6. The network device according to claim 5 , wherein to cause the network device to send the subscription notification to the second network device, the processor is further configured to in response to the supported registration mode of the terminal device being a DR mode, cause the network device to send the subscription notification to the second network device.

7. The network device according to claim 1 , wherein the processor is further configured to:

cause the network device to receive third information sent by a third network device in the first system indicative of registration of the terminal device with the second system; and

determine the registration mode of the terminal device according to the registration of the terminal device with the second system.

8. The network device according to claim 7 , wherein the network device is an access network device in the first system, and the third network device is a core network device in the first system; and

the third information is a cause value in a handover request reject message, and the third information indicates that the terminal device has registered with the second system.

9. The network device according to claim 8 , wherein the processor is further configured to cause the network device to send a handover request to the third network device to allow the third network device to send a redirection request to a core network device in the second system through an N26 interface.

10. The network device according to claim 1 , wherein in response to the terminal device keeping a connected state with the first cell, and the first system supporting interworking with an N26 interface, the determined procedure is a handover procedure.

11. The network device according to claim 1 , wherein in response to the terminal device keeping a connected state with the first cell, and the first system supporting interworking without an N26 interface, the determined procedure is a redirection procedure.

12. The network device according to claim 1 , wherein in response to the registration mode of the terminal device being a DR mode, the determined procedure is a redirection procedure.

13. The network device according to claim 1 , wherein in response to at least one of the first system supporting interworking without an N26 interface or the registration mode of the terminal device being a DR mode, the determined procedure is a redirection procedure.

14. The network device according to claim 1 , wherein the processor is further configured to in response to the determined procedure being a handover procedure, trigger sending a handover request message to a core network device in the first system.

15. The network device according to claim 1 , wherein the processor is further configured to, in response to the determined procedure being a redirection procedure, trigger the terminal device to access the second cell while keeping accessing the first cell.

16. The network device according to claim 1 , wherein the preset information comprises at least one of an N2 message sent by a core network device in the first system, a message returned by the core network device in the first system for a registration message of the terminal device or another terminal device, a support for interworking with an N26 interface by a system corresponding to at least one Public Land Mobile Network (PLMN), or a support without an N26 interface by the system corresponding to at least one PLMN.

17. The network device according to claim 1 , wherein the first system is a 5th generation system (5GS), and the second system is a Long Term Evolution (LTE) system.

18. The network device according to claim 1 , wherein the supported registration mode of the terminal device is the DR mode, and the processor is further configured to cause the network device to receive an attach request messaged with a handover indication.

19. A terminal device, comprising:

a memory storing code; and

a processor connected to the memory and, when the code is executed, configured to:

cause the terminal device to access a first cell in a first system;

generate first information indicative of whether the terminal device supports sending an attach request message with a handover indication to a network device;

cause the terminal device to send the first information to the network device in the first system; and

perform a procedure determined by the network device in the first system to cause the terminal device to establish an access to a second cell in a second system,

wherein in response to a registration mode of the terminal device being an SR mode, the determined procedure is a handover procedure or a redirection procedure,

wherein in response to the terminal device keeping a connected state with the first cell, and the first system not supporting interworking with an N26 interface, the determined procedure is the redirection procedure,

wherein the network device is an access network device, and

wherein the processor is configured to determine at least one of the support for interworking with an N26 interface by the first system or the support for interworking without an N26 interface by the first system based on preset information.

20. The terminal device according to claim 19 , wherein the first information is carried in a registration message or a location update message.

21. The terminal device according to claim 19 , wherein the procedure determined by the network device is a redirection procedure.

22. The terminal device according to claim 21 , wherein the processor is further configured to:

recognize indication information from the network device indicative of a support of a handover without an N26 interface; and

in response to recognizing the indication information, cause the terminal device to send the attach request message to the network device after performing the redirection procedure.

23. The terminal device according to claim 21 , wherein the first information indicates that a registration mode of the terminal device is a dual registration (DR) mode, and the processor is further configured to cause the terminal device to send the attach request message to the network device after performing the redirection procedure.

24. The terminal device according to claim 21 , wherein the attach request message comprises a Packet Data Network (PDN) connectivity request parameter carrying the handover indication.

25. A method for wireless communication, comprising:

determining, by a first network device in a first system, at least one of a registration mode of a terminal device, a supported registration mode of the terminal device, a support for interworking with an N26 interface by a first system, or a support for interworking without an N26 interface by the first system, wherein the registration mode is a single registration (SR) mode of registration with a single system or a dual registration (DR) mode of registration with dual systems, and a first cell in the first system is accessed by the terminal device;

determining, by the first network device, according to the determined at least one of the registration mode of the terminal device, the supported registration mode of the terminal device, the support for interworking with an N26 interface by the first system, or the support for interworking without an N26 interface by the first system, an allowed procedure for the terminal device to access a second cell in a second system; and

making, by the first network device, the terminal device to perform the allowed procedure to establish an access to the second cell,

wherein in response to the registration mode of the terminal device being an SR mode, the determined procedure is a handover procedure or a redirection procedure,

wherein in response to the terminal device keeping a connected state with the first cell, and the first system not supporting interworking with an N26 interface, the determined procedure is the redirection procedure,

wherein the network device is an access network device, and

wherein the processor is configured to determine at least one of the support for interworking with an N26 interface by the first system or the support for interworking without an N26 interface by the first system based on preset information.

26. A method for wireless communication, comprising:

accessing, by a terminal device, a first cell in a first system;

generating, by the terminal device, first information indicative of whether the terminal device supports sending an attach request message with a handover indication to a network device;

sending, by the terminal device, the first information to the network device in the first system; and

performing, by the terminal device, a procedure determined by the network device in the first system to establish an access to a second cell in a second system,

wherein in response to a registration mode of the terminal device being an SR mode, the determined procedure is a handover procedure or a redirection procedure,

wherein in response to the terminal device keeping a connected state with the first cell, and the first system not supporting interworking with an N26 interface, the determined procedure is the redirection procedure,

wherein the network device is an access network device, and

wherein the processor is configured to determine at least one of the support for interworking with an N26 interface by the first system or the support for interworking without an N26 interface by the first system based on preset information.