Communication method and device

Abstract

A communication method and apparatus, a second network device receiving reference identifier information from a first network device, sending the reference identifier information and a first identifier to a third network device, and receiving the first identifier and a second identifier from the third network device. The reference identification information is used for identifying the terminal equipment. The first identifier is an identifier which is allocated by the second network equipment as the source network equipment and is used for identifying the terminal equipment on an interface of the second network equipment and the third network equipment. The second identifier is an identifier which is allocated by the third network equipment as the target network equipment and is used for identifying the terminal equipment on the interface of the second network equipment and the third network equipment. The first network device is a source network device for the first switching of the terminal device, the second network device is a source network device for the second switching of the terminal device, and the third network device is a candidate network device for the second switching of the terminal device. And correct transmission of messages related to the specific terminal equipment between the second network equipment and the third network equipment is facilitated.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0002] In mobile communication systems, the movement of a terminal device may necessitate cell handover. When the source and target cells for this handover are managed by different network devices, the network device providing services to the terminal device needs to switch from the source network device to the target network device. The source network device manages the source cell, and the target network device manages the target cell. The source and target network devices need to transmit messages related to the terminal device. For mobility management technologies that support "subsequent handovers" or "multiple handovers," how to ensure the correct transmission of messages related to a specific terminal device between the source and target network devices during subsequent or multiple handovers requires further research. Summary of the Invention

[0003] This application provides a communication method and apparatus that facilitates the correct transmission of messages related to a specific terminal device between the source network device and the target network device during subsequent or multiple handovers of the terminal device.

[0004] Firstly, this application provides a communication method applicable to network device 2, a chip within network device 2, and a logic module or software capable of implementing all or part of the functions of network device 2. The method is described below using network device 2 as an example. The method includes: network device 2 receiving reference identification information 5 from network device 1; network device 2 sending a message 7 to network device 3, the message 7 including reference identification information 5 and an identifier 5; and network device 2 receiving identifier 5 and identifier 6 sent by network device 3 in response to message 7. The reference identification information 5 is used to identify a terminal device. Identifier 5 is assigned by network device 2 as the source network device for identifying the terminal device at the interface between network device 2 and network device 3, and identifier 6 is assigned by network device 3 as the target network device for identifying the terminal device at the interface between network device 2 and network device 3. Network device 1 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0005] As can be seen, in this method, network device 2, as the source network device, is assigned an identifier, i.e., identifier 5, for identifying the terminal device on the interface between network device 2 and network device 3. Network device 3, as the target network device, is assigned an identifier, i.e., identifier 6, for identifying the terminal device on the interface between network device 2 and network device 3. Furthermore, network device 2 and network device 3 exchange their respective assigned identifiers so that when the target network device for the second handover of the terminal device is network device 3, network device 2 and network device 3 can carry identifiers 5 and 6 when transmitting messages related to the terminal device between them. This allows network device 2 to identify the terminal device targeted by the message from network device 3 based on identifier 5, and network device 3 to identify the terminal device targeted by the message from network device 2 based on identifier 6. This facilitates the correct transmission of messages related to a specific terminal device between network device 2 and network device 3.

[0006] Furthermore, network device 2 also receives reference identification information 5 sent by the source network device, i.e., network device 1, when the terminal device performs its first handover. Network device 2 sends reference identification information 5 to network device 3, enabling network device 3 to determine the context of the terminal device based on reference identification information 5 and associate identifier 6 with the context of the terminal device. Thus, when network device 3 determines that the terminal device identified by identifier 6 has switched from network device 2 to network device 3, it can communicate with the terminal device based on the context of the terminal device associated with identifier 6, which helps the terminal device identified by identifier 6 to successfully switch from network device 2 to network device 3.

[0007] In one optional implementation, the reference identification information 5 is used to identify the terminal device within a preset area. Alternatively, the reference identification information 5 is used by network devices 1, 2, and 3 to identify the terminal device during multiple handovers, including a first handover and a second handover.

[0008] In one optional implementation, the reference identification information 5 received by network device 2 from network device 1 is carried in message 1, which is used to request configuration information of candidate cells.

[0009] In one alternative implementation, the reference identification information 5 is identification 2 or identification 4. Identifier 2 is an identifier assigned by network device 1 as the source network device for identifying the terminal device on the interface between network device 1 and network device 3. Identifier 4 is an identifier assigned by network device 3 as the target network device for identifying the terminal device on the interface between network device 1 and network device 3.

[0010] In one optional implementation, the reference identification information 5 received by network device 2 from network device 1 is carried in message 6, which is used to notify network device 2 that the terminal device has switched from network device 1 to network device 2.

[0011] In an optional implementation, the method further includes: network device 2 receiving message 1 from network device 1, message 1 requesting configuration information of candidate cells, message 1 including identifier 1; network device 2 sending message 3 to network device 1, message 3 including configuration information of cell 2, identifier 1, and identifier 3. Wherein, cell 2 is managed by network device 2, the configuration information of cell 2 is used for terminal devices to access cell 2, identifier 1 is an identifier assigned by network device 1 as the source network device for identifying the terminal device at the interface between network device 1 and network device 2, and identifier 3 is an identifier assigned by network device 2 as the target network device for identifying the terminal device at the interface between network device 1 and network device 2.

[0012] In an optional implementation, the method further includes: network device 2 sending message 9 to network device 3, message 9 including identifier 5 and identifier 6; message 9 is used to notify network device 3 that the terminal device has switched from network device 2 to network device 3.

[0013] Secondly, this application provides a communication method that can be applied to a network device 3, a chip within the network device 3, or a logic module or software capable of implementing all or part of the functions of the network device 3. The following description uses the network device 3 as an example. The method includes: the network device 3 receiving a message 7 from a network device 2, the message 7 including reference identification information 5 and an identifier 5; the network device 3 determining the context of a terminal device based on the reference identification information 5; the network device 3 associating an identifier 6 with the context of the terminal device; and the network device 3 sending identifier 5 and identifier 6 to the network device 2. Wherein, the reference identification information 5 is used to identify the terminal device; identifier 5 is an identifier assigned by the network device 2 as the source network device for identifying the terminal device at the interface between the network device 2 and the network device 3; identifier 6 is an identifier assigned by the network device 3 as the target network device for identifying the terminal device at the interface between the network device 2 and the network device 3; network device 2 is the source network device for the second handover of the terminal device; and network device 3 is the candidate network device for the second handover of the terminal device.

[0014] As can be seen, in this method, network device 2, as the source network device, is assigned an identifier, i.e., identifier 5, for identifying the terminal device on the interface between network device 2 and network device 3. Network device 3, as the target network device, is assigned an identifier, i.e., identifier 6, for identifying the terminal device on the interface between network device 2 and network device 3. Furthermore, network device 2 and network device 3 exchange their respective assigned identifiers so that when the target network device for the second handover of the terminal device is network device 3, network device 2 and network device 3 can carry identifiers 5 and 6 when transmitting messages related to the terminal device between them. This allows network device 2 to identify the terminal device targeted by the message from network device 3 based on identifier 5, and network device 3 to identify the terminal device targeted by the message from network device 2 based on identifier 6. This facilitates the correct transmission of messages related to a specific terminal device between network device 2 and network device 3.

[0015] Furthermore, network device 3 also receives reference identification information 5 sent by network device 2, thereby determining the context of the terminal device based on the reference identification information 5, and associating identifier 6 with the context of the terminal device. Thus, when network device 3 determines that the terminal device identified by identifier 6 has switched from network device 2 to network device 3, it can communicate with the terminal device based on the context of the terminal device associated with identifier 6, which helps the terminal device identified by identifier 6 to successfully switch from network device 2 to network device 3.

[0016] In one optional implementation, the reference identification information 5 is used to identify the terminal device within a preset area. Alternatively, the reference identification information 5 is used by network devices 1, 2, and 3 to identify the terminal device during multiple handovers, where network device 1 is the source network device for the first handover of the terminal device, and the multiple handovers include the first handover and the second handover.

[0017] In one optional implementation, the reference identification information 5 is identification 2 or identification 4. Identifier 2 is an identifier assigned by network device 1 as the source network device for identifying the terminal device on the interface between network device 1 and network device 3. Identifier 4 is an identifier assigned by network device 3 as the target network device for identifying the terminal device on the interface between network device 1 and network device 3. Network device 1 is the source network device for which the terminal device performs its first handover.

[0018] In an optional implementation, the method further includes: network device 3 receiving message 2 from network device 1, message 2 requesting configuration information of candidate cells, message 2 including identifier 2. Network device 3 sending message 4 to network device 1, message 4 including configuration information of cell 3, identifier 2, and identifier 4. Wherein, cell 3 is managed by network device 3, the configuration information of cell 3 is used for terminal devices to access cell 3, identifier 2 is an identifier assigned by network device 1 as the source network device for identifying the terminal device at the interface between network device 1 and network device 3, and identifier 4 is an identifier assigned by network device 3 as the target network device for identifying the terminal device at the interface between network device 1 and network device 3. Network device 1 is the source network device for the terminal device's first handover.

[0019] In one alternative implementation, the context of the terminal device includes the configuration information of cell 3.

[0020] In an optional implementation, the method further includes: network device 3 receiving message 9 from network device 2, message 9 including identifier 5 and identifier 6; message 9 is used to notify network device 3 that the terminal device has switched from network device 2 to network device 3.

[0021] Thirdly, this application provides a communication method that can be applied to network device 2, to a chip in network device 2, or to a logic module or software that can implement all or part of the functions of network device 2. The following description uses network device 2 as an example. The method includes: network device 2 assigning an identifier 8 to a terminal device; network device 2 receiving an identifier 9 from network device 1, where identifier 9 is an identifier assigned to the terminal device by network device 3. Identifier 8 is used by network device 2 to communicate with other network devices (excluding network device 2) for the terminal device, including network device 3. Identifier 9 is used by network device 3 to communicate with other network devices (excluding network device 3) for the terminal device, including network device 2. Network device 1 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0022] As can be seen, in this method, the identifier assigned by network device 2, i.e., identifier 8, can be used by network device 2 to communicate with other network devices (excluding network device 2) regarding terminal devices, so that network device 2 can identify the terminal device through identifier 8 during multiple handovers of the terminal device. The identifier assigned by network device 3, i.e., identifier 9, can be used by network device 3 to communicate with other network devices (excluding network device 3) regarding terminal devices, so that network device 3 can identify the terminal device through identifier 9 during multiple handovers of the terminal device. Network device 2 will receive identifier 9 sent by the source network device (i.e., network device 1) when the terminal device performs its first handover, so that when the target network device for the second handover of the terminal device is network device 3, network device 2 can carry identifier 8 and identifier 9 when sending relevant messages about the terminal device to network device 3. This allows network device 3 to identify the terminal device to which the transmitted message is targeted based on identifier 9, which is beneficial for the correct transmission of messages related to a specific terminal device between network device 2 and network device 3.

[0023] In an optional implementation, the method further includes: network device 2 sending identifier 8 to network device 1. Network device 2 receiving identifier 9 from network device 1 includes: network device 2 receiving identifier 8 and identifier 9 from network device 1.

[0024] In an optional implementation, the method further includes: network device 2 receiving a message 10 from network device 1, the message 10 requesting configuration information for a candidate cell, the message 10 including an identifier 7. Network device 2 then sends an identifier 8 to network device 1, including: network device 2 sending a message 11 to network device 1, the message 11 including configuration information for cell 2, identifier 7, and identifier 8. Wherein, cell 2 is managed by network device 2, the configuration information for cell 2 is used for terminal devices to access cell 2, and identifier 7 is an identifier used by network device 1 to communicate with network devices other than network device 1 for terminal devices. Network devices other than network device 1 include network device 2.

[0025] In an optional implementation, message 10 further includes instruction information 1, which instructs network device 2 to assign an identifier to identify the terminal device during multiple handovers, including a first handover and a second handover.

[0026] In an optional implementation, the method further includes: network device 2 sending message 15 to network device 3, message 15 including identifier 8 and identifier 9; message 15 is used to notify network device 3 that the terminal device has switched from network device 2 to network device 3.

[0027] Fourthly, this application provides a communication method that can be applied to network device 1, a chip in network device 1, or a logic module or software capable of implementing all or part of the functions of network device 1. The following description uses network device 1 as an example. The method includes: network device 1 receiving an identifier 9 from network device 3; and network device 1 sending the identifier 9 to network device 2. The identifier 9 is used by network device 3 to communicate with other network devices (excluding network device 3) for a terminal device. Network device 1 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0028] As can be seen, in this method, the identifier assigned by network device 3, namely identifier 9, can be used by network device 3 to communicate with other network devices (excluding network device 3) regarding terminal devices. This allows network device 3 to identify the terminal device through identifier 9 during multiple handovers. After receiving identifier 9 from network device 3, network device 1 sends identifier 9 to network device 2. This allows network device 2 to carry identifier 9 when sending terminal device-related messages to network device 3 if the target network device for the second handover of the terminal device is network device 3. This enables network device 3 to identify the terminal device to which the transmitted message is targeted based on identifier 9, facilitating the correct transmission of messages related to a specific terminal device between network device 2 and network device 3.

[0029] In an optional implementation, the method further includes: network device 1 receiving an identifier 8 from network device 2. Network device 1 sending an identifier 9 to network device 2, including: network device 1 sending identifier 8 and identifier 9 to network device 2.

[0030] In an optional implementation, the method further includes: network device 1 sending a message 10 to network device 2, the message 10 requesting configuration information of a candidate cell, the message 10 including an identifier 7. Network device 1 receiving an identifier 8 from network device 2 includes: network device 1 receiving a message 11 from network device 2, the message 11 including configuration information of cell 2, identifier 7, and identifier 8. Wherein, cell 2 is managed by network device 2, the configuration information of cell 2 is used for terminal devices to access cell 2, and identifier 7 is an identifier used by network device 1 to communicate with network devices other than network device 1 for terminal devices. Network devices other than network device 1 include network device 2.

[0031] In an optional implementation, the method further includes: network device 1 sending message 10 to network device 3, message 10 requesting configuration information of candidate cells, message 10 including identifier 7. Network device 1 receiving identifier 9 from network device 3 includes: network device 1 receiving message 12 from network device 3, message 12 including configuration information of cell 3, identifier 7, and identifier 9. Cell 3 is managed by network device 3, and the configuration information of cell 3 is used by terminal devices to access cell 3. Identifier 7 is an identifier used by network device 1 to communicate with network devices other than network device 1 for terminal devices, and network devices other than network device 1 include network device 3.

[0032] In an optional implementation, message 10 further includes indication information 1, which indicates the allocation of an identifier to identify the terminal device during multiple handovers, including a first handover and a second handover.

[0033] Fifthly, this application provides a communication method that can be applied to network device 2, to a chip in network device 2, or to a logic module or software capable of implementing all or part of the functions of network device 2. The following description uses network device 2 as an example. The method includes: network device 2 assigning identifiers 8a and 8b to a terminal device; and network device 2 receiving identifiers 9a and 9b from network device 1.

[0034] In this context, identifier 8a is assigned by network device 2 as a source network device for communication between network device 2 and other network devices (excluding network device 2) with a terminal device. Identifier 8b is assigned by network device 2 as a target network device for communication between network device 2 and other network devices (excluding network device 2) with a terminal device. Network devices other than network device 2 include network device 3.

[0035] Identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include network device 2.

[0036] Network device 1 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0037] As can be seen, in this method, network device 2 obtains identifiers 9a and 9b so that when the target network device for the second handover of the terminal device is network device 3, network device 2 can carry identifiers 8a and 9b when sending terminal device-related messages to network device 3. This allows network device 3 to identify the terminal device to which the transmitted message is targeted based on identifier 9b, which is beneficial for the correct transmission of messages related to a specific terminal device between network device 2 and network device 3. When the source network device for the handover is network device 3 and the target network device for this handover is network device 2, network device 2 can carry identifiers 8b and 9a when sending terminal device-related messages to network device 3. This allows network device 3 to identify the terminal device to which the transmitted message is targeted based on identifier 9a, which is also beneficial for the correct transmission of messages related to a specific terminal device between network device 2 and network device 3.

[0038] In one optional implementation, the method further includes: network device 2 sending identifier 8a and identifier 8b to network device 1. Network device 2 receiving identifier 9a and identifier 9b from network device 1 includes: network device 2 receiving identifier 8a, identifier 8b, identifier 9a, and identifier 9b from network device 1.

[0039] In an optional implementation, the method further includes: network device 2 receiving a message 10 from network device 1, message 10 requesting configuration information for a candidate cell, message 10 including identifier 7a and identifier 7b. Network device 2 then sends identifiers 8a and 8b to network device 1, including: network device 2 sending a message 11 to network device 1, message 11 including configuration information for cell 2, identifier 7a, identifier 7b, identifier 8a, and identifier 8b. Cell 2 is managed by network device 2, and the configuration information for cell 2 is used by terminal devices to access cell 2. Identifier 7a is an identifier assigned by network device 1 as a source network device for communication between network device 1 and network devices other than network device 1 for terminal devices. Identifier 7b is an identifier assigned by network device 1 as a target network device for communication between network device 1 and network devices other than network device 1 for terminal devices. Network devices other than network device 1 include network device 2.

[0040] In an optional implementation, the method further includes: network device 2 sending message 15 to network device 3, message 15 including identifier 8a and identifier 9b; message 15 is used to notify network device 3 that the terminal device has switched from network device 2 to network device 3.

[0041] Sixthly, this application provides a communication method that can be applied to network device 1, a chip in network device 1, or a logic module or software capable of implementing all or part of the functions of network device 1. The following description uses network device 1 as an example. The method includes: network device 1 receiving identifiers 9a and 9b from network device 3; and network device 1 sending identifiers 9a and 9b to network device 2.

[0042] In this context, identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include network device 2.

[0043] Network device 1 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0044] As can be seen, in this method, network device 1 forwards identifiers 9a and 9b to network device 3 so that when network device 2 sends messages related to the terminal device to network device 3, it can carry identifiers 8a and 9b. This allows network device 3 to identify the terminal device to which the transmitted message is targeted based on identifier 9b, which is beneficial for the correct transmission of messages related to a specific terminal device between network device 2 and network device 3. When the source network device for the handover is network device 3 and the target network device for this handover is network device 2, network device 2 can carry identifiers 8b and 9a when sending messages related to the terminal device to network device 3. This allows network device 3 to identify the terminal device to which the transmitted message is targeted based on identifier 9a, which is also beneficial for the correct transmission of messages related to a specific terminal device between network device 2 and network device 3.

[0045] In an optional implementation, the method further includes: network device 1 receiving identifiers 8a and 8b from network device 2. Network device 1 sending identifiers 9a and 9b to network device 2 includes: network device 1 sending identifiers 8a, 8b, 9a, and 9b to network device 2.

[0046] In an optional implementation, the method further includes: network device 1 sending message 10 to network device 2, message 10 requesting configuration information of candidate cells, message 10 including identifier 7a and identifier 7b. Network device 1 receiving identifier 8a and identifier 8b from network device 2 includes: network device 1 receiving message 11 from network device 2, message 11 including configuration information of cell 2, identifier 7a and identifier 7b, identifier 8a and identifier 8b. Cell 2 is managed by network device 2, and the configuration information of cell 2 is used by terminal devices to access cell 2. Identifier 7a is an identifier assigned by network device 1 as a source network device for communication between network device 1 and network devices other than network device 1 for terminal devices. Identifier 7b is an identifier assigned by network device 1 as a target network device for communication between network device 1 and network devices other than network device 1 for terminal devices. Network devices other than network device 1 include network device 2.

[0047] In an optional implementation, the method further includes: network device 1 sending message 10 to network device 3, message 10 requesting configuration information of candidate cells, message 10 including identifier 7a and identifier 7b. Network device 1 receiving identifier 9a and identifier 9b from network device 3 includes: network device 1 receiving message 12 from network device 3, message 12 including configuration information of cell 3, identifier 7a, identifier 7b, identifier 9a, and identifier 9b. Cell 3 is managed by network device 3, and the configuration information of cell 3 is used by terminal devices to access cell 3.

[0048] Seventhly, this application also provides a communication device. This communication device may be a network device, a chip within a network device, or a logic module or software capable of implementing all or part of the functions of a network device. The communication device has the function of implementing some or all of the embodiments described in any one of the first to sixth aspects. The function can be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more units or modules corresponding to the above functions.

[0049] In one possible design, the communication device may include a processing unit configured to support the communication device in performing the corresponding functions described in the above methods. Optionally, the communication device may also include a communication unit for supporting communication between the communication device and other communication devices. Optionally, the communication device may further include a storage unit coupled to the processing unit and the communication unit, which stores necessary program instructions and data for the communication device. Additionally, the processing unit may be used to control the communication unit to transmit and receive data / signaling.

[0050] In one embodiment, the communication unit is configured to receive reference identification information 5 from network device 1. The communication unit is also configured to send a message 7 to network device 3, the message 7 including the reference identification information 5 and an identifier 5. The communication unit is further configured to receive identifier 5 and identifier 6 sent by network device 3 in response to message 7. The reference identification information 5 is used to identify the terminal device; identifier 5 is an identifier assigned by the communication device as the source network device for identifying the terminal device at the interface between the communication device and network device 3; identifier 6 is an identifier assigned by network device 3 as the target network device for identifying the terminal device at the interface between the communication device and network device 3. Network device 1 is the source network device for the first handover of the terminal device, the communication device is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0051] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the first aspect above, and will not be described in detail here.

[0052] In another embodiment, the communication unit is configured to receive a message 7 from the network device 2, the message 7 including reference identification information 5 and an identifier 5. The processing unit is configured to determine the context of the terminal device based on the reference identification information 5. The processing unit is further configured to associate the identifier 6 with the context of the terminal device. The communication unit is further configured to send the identifier 5 and the identifier 6 to the network device 2. Wherein, the reference identification information 5 is used to identify the terminal device; the identifier 5 is an identifier assigned by the network device 2 as the source network device for identifying the terminal device at the interface between the network device 2 and the communication device; the identifier 6 is an identifier assigned by the communication device as the target network device for identifying the terminal device at the interface between the network device 2 and the communication device; the network device 2 is the source network device for the second handover of the terminal device; and the communication device is a candidate network device for the second handover of the terminal device.

[0053] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the second aspect above, and will not be described in detail here.

[0054] In another embodiment, a processing unit is used to assign an identifier 8 to a terminal device. A communication unit is used to receive an identifier 9 from network device 1, where identifier 9 is an identifier assigned to the terminal device by network device 3. Identifier 8 is used when a communication device communicates with other network devices (excluding the communication device) for the terminal device, and these other network devices include network device 3. Identifier 9 is used when network device 3 communicates with other network devices (excluding network device 3) for the terminal device, and these other network devices include the communication device. Network device 1 is the source network device for the first handover of the terminal device, the communication device is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0055] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the third aspect above, and will not be described in detail here.

[0056] In another embodiment, the processing unit is configured to receive an identifier 9 from network device 3. The communication unit is further configured to send the identifier 9 to network device 2. The identifier 9 is used by network device 3 to communicate with other network devices (excluding network device 3) regarding the terminal device. Network device 2 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0057] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the fourth aspect above, and will not be described in detail here.

[0058] In another embodiment, a processing unit is used to assign identifiers 8a and 8b to the terminal device. A communication unit is used to receive identifiers 9a and 9b from network device 1.

[0059] Here, identifier 8a is assigned by the communication device as a source network device for communication between the communication device and network devices other than the communication device for communication with a terminal device. Identifier 8b is assigned by the communication device as a target network device for communication between the communication device and network devices other than the communication device for communication with a terminal device. Network devices other than the communication device include network device 3.

[0060] Identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include communication devices.

[0061] Network device 1 is the source network device for the first handover of the terminal device, the communication device is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0062] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the fifth aspect above, and will not be described in detail here.

[0063] In another embodiment, the communication unit is configured to receive identifiers 9a and 9b from network device 3; the communication unit is also configured to send identifiers 9a and 9b to network device 2.

[0064] In this context, identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include network device 2.

[0065] The communication device is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0066] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the sixth aspect above, and will not be described in detail here.

[0067] As an example, the communication unit can be a transceiver or a communication interface, the storage unit can be a memory, and the processing unit can be a processor. The processor is coupled to the memory, which stores programs or instructions for the processor. The processor can be used to cause the communication device to perform the method described in the first aspect above when the program or instructions are executed by the processor. The transceiver or communication interface can be used to send and receive signals and / or data.

[0068] In one embodiment, the transceiver is configured to receive reference identification information 5 from network device 1. The transceiver is also configured to send a message 7 to network device 3, the message 7 including the reference identification information 5 and an identifier 5. The transceiver is further configured to receive identifier 5 and identifier 6 sent by network device 3 in response to message 7. The reference identification information 5 is used to identify the terminal device; identifier 5 is an identifier assigned by the communication device as the source network device for identifying the terminal device at the interface between the communication device and network device 3; identifier 6 is an identifier assigned by network device 3 as the target network device for identifying the terminal device at the interface between the communication device and network device 3. Network device 1 is the source network device for the first handover of the terminal device, the communication device is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0069] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the first aspect above, and will not be described in detail here.

[0070] In another embodiment, a transceiver is used to receive a message 7 from network device 2, the message 7 including reference identification information 5 and an identifier 5. A processor is used to determine the context of the terminal device based on the reference identification information 5. The processor is also used to associate the identifier 6 with the context of the terminal device. The transceiver is also used to send the identifier 5 and the identifier 6 to network device 2. The reference identification information 5 is used to identify the terminal device; the identifier 5 is an identifier assigned by network device 2 as the source network device for identifying the terminal device at the interface between network device 2 and the communication device; the identifier 6 is an identifier assigned by the communication device as the target network device for identifying the terminal device at the interface between network device 2 and the communication device. Network device 2 is the source network device for the second handover of the terminal device, and the communication device is a candidate network device for the second handover of the terminal device.

[0071] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the second aspect above, and will not be described in detail here.

[0072] In another embodiment, a processor is used to assign an identifier 8 to the terminal device. A transceiver is used to receive an identifier 9 from network device 1, where identifier 9 is an identifier assigned to the terminal device by network device 3. Identifier 8 is used when the communication device communicates with other network devices (including network device 3) regarding the terminal device. Identifier 9 is used when network device 3 communicates with other network devices (including the communication device) regarding the terminal device. Network device 1 is the source network device for the first handover of the terminal device, the communication device is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0073] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the third aspect above, and will not be described in detail here.

[0074] In another embodiment, the processor is configured to receive identifier 9 from network device 3. The transceiver is further configured to send identifier 9 to network device 2. Identifier 9 is used by network device 3 to communicate with other network devices (including network device 2) regarding the terminal device. The communication device is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0075] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the fourth aspect above, and will not be described in detail here.

[0076] In another embodiment, a processor is used to assign identifiers 8a and 8b to the terminal device. A transceiver is used to receive identifiers 9a and 9b from network device 1.

[0077] Here, identifier 8a is assigned by the communication device as a source network device for communication between the communication device and network devices other than the communication device for communication with a terminal device. Identifier 8b is assigned by the communication device as a target network device for communication between the communication device and network devices other than the communication device for communication with a terminal device. Network devices other than the communication device include network device 3.

[0078] Identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include communication devices.

[0079] Network device 1 is the source network device for the first handover of the terminal device, the communication device is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0080] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the fifth aspect above, and will not be described in detail here.

[0081] In another embodiment, the transceiver is used to receive identifiers 9a and 9b from network device 3; the transceiver is also used to send identifiers 9a and 9b to network device 2.

[0082] In this context, identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include network device 2.

[0083] The communication device is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0084] In addition, other alternative implementations of the communication device in this regard can be found in the relevant content of the sixth aspect above, and will not be described in detail here.

[0085] In another embodiment, the communication device is a chip or chip system. The processing unit may also be a processing circuit or logic circuit; the transceiver unit may be an input / output interface, interface circuit, output circuit, input circuit, pin, or related circuit on the chip or chip system.

[0086] In implementation, the processor can be used for, but is not limited to, baseband-related processing, and the transceiver or communication interface can be used for, but is not limited to, radio frequency transceiver. These devices can be disposed on separate chips, or at least partially or entirely on the same chip. For example, the processor can be further divided into analog baseband processors and digital baseband processors. The analog baseband processor can be integrated with the transceiver (or communication interface) on the same chip, while the digital baseband processor can be disposed on a separate chip. With the continuous development of integrated circuit technology, more and more devices can be integrated on the same chip. For example, a digital baseband processor can be integrated with multiple application processors (e.g., but not limited to graphics processors, multimedia processors, etc.) on the same chip. Such a chip can be called a system-on-a-chip (SoC). Whether the various devices are disposed independently on different chips or integrated on one or more chips often depends on the needs of the product design. This application does not limit the implementation form of the above-mentioned devices.

[0087] Eighthly, this application also provides a processor for executing the various methods described above. In executing these methods, the processes of sending and receiving the aforementioned information can be understood as the process of the processor outputting the aforementioned information and the process of the processor inputting the aforementioned information. When outputting the aforementioned information, the processor outputs the aforementioned information to a transceiver so that the transceiver (or communication interface) can transmit it. After being output by the processor, the aforementioned information may require further processing before reaching the transceiver (or communication interface). Similarly, when the processor receives the input information, the transceiver (or communication interface) receives the aforementioned information and inputs it into the processor. Furthermore, after the transceiver (or communication interface) receives the aforementioned information, the aforementioned information may require further processing before being input into the processor.

[0088] Unless otherwise specified, or unless it contradicts its actual function or internal logic in the relevant description, the transmission and reception operations involved by the processor can be more generally understood as processor output and reception, input and other operations, rather than transmission and reception operations directly performed by radio frequency circuits and antennas.

[0089] In implementation, the processor can be a dedicated processor for executing these methods, or it can be a processor that executes computer instructions stored in memory to execute these methods, such as a general-purpose processor. The memory can be a non-transitory memory, such as read-only memory (ROM), which can be integrated with the processor on the same chip or disposed on different chips. This application does not limit the type of memory or the arrangement of the memory and processor.

[0090] Ninthly, this application also provides a communication system including means for performing the method of the first aspect and means for performing the method of the second aspect. In another possible design, the system may further include other devices that interact with the means for performing the method of the first aspect, and / or other devices that interact with the means for performing the method of the second aspect.

[0091] Tenthly, this application also provides a communication system including means for performing the method described in the third aspect and means for performing the method described in the fourth aspect. In another possible design, the system may further include other devices that interact with the means for performing the method described in the third aspect, and / or other devices that interact with the means for performing the method described in the fourth aspect.

[0092] Eleventhly, this application also provides a communication system including means for performing the method described in the fifth aspect and means for performing the method described in the sixth aspect. In another possible design, the system may further include other devices that interact with the means for performing the method described in the fifth aspect, and / or other devices that interact with the means for performing the method described in the sixth aspect.

[0093] In a twelfth aspect, this application provides a computer-readable storage medium storing a computer program that, when run, causes the method described in any one of the first to sixth aspects to be executed.

[0094] In a thirteenth aspect, this application also provides a computer program product including instructions, the computer program product comprising: computer program code, which, when executed, causes the method described in any one of the first to sixth aspects to be performed.

[0095] In a fourteenth aspect, this application provides a chip system including a processor and an interface. The interface is used to acquire programs or instructions, and the processor is used to invoke the programs or instructions to implement the functions involved in any of the first to sixth aspects. In one possible design, the chip system further includes a memory for storing program instructions and data necessary for the terminal. This chip system may be composed of chips or may include chips and other discrete devices. Attached Figure Description

[0096] Figure 1 This is a schematic diagram of a system architecture provided in an embodiment of this application;

[0097] Figure 2 This is a schematic diagram of a CU-DU separation architecture provided in an embodiment of this application;

[0098] Figure 3 This is a schematic diagram of another system architecture provided in an embodiment of this application;

[0099] Figure 4 This is a schematic diagram of a UE XnAP ID interaction provided in an embodiment of this application;

[0100] Figure 5 This is a flowchart illustrating a communication method provided in an embodiment of this application;

[0101] Figure 6 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0102] Figure 7 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0103] Figure 8 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0104] Figure 9 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0105] Figure 10 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0106] Figure 11 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0107] Figure 12 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0108] Figure 13 This application provides a schematic diagram of the structure of a communication device;

[0109] Figure 14 This application provides a schematic diagram of the structure of another communication device. Detailed Implementation

[0110] The embodiments of this application are described below with reference to the accompanying drawings.

[0111] The technical solutions of this application can be applied to various communication systems. For example, the Global System for Mobile Communications (GSMA), Long Term Evolution (LTE) system, Universal Mobile Telecommunications System (UMTS), 4th Generation (4G) mobile communication system, 4.5th Generation (4.5G) mobile communication system, 5th Generation (5G) mobile communication system, and, with the continuous development of communication technology, the technical solutions of this application can also be used in subsequent evolved communication systems, such as 6th Generation (6G) mobile communication system, 7th Generation (7G) mobile communication system, and so on. The technical solutions of this application can also be applied to Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access (CDMA) system, Wireless Local Area Network (WLAN), etc.

[0112] This application provides a communication system including a network device and a terminal device. The terminal device is located within the coverage area of ​​one or more cells (carriers) managed by the network device, and the cells providing services to the terminal device can be one or more. When multiple cells provide services to the terminal device, the terminal device can operate according to carrier aggregation (CA), dual connectivity (DC), or cooperative multipoint transmission modes. At least one of the multiple cells can provide at least two sets of parameter numbers to simultaneously provide radio resources to the terminal device. For example, such as... Figure 1 As shown, the terminal device is simultaneously located within the coverage area of ​​the cell managed by network device A, the cell managed by network device B, and the cell managed by network device C. Figure 1In this context, network device A can be, for example, a macro base station (macro evolutional Node B, macro eNB, or macro e-NodeB), while network devices B and C can be, for example, micro base stations (small eNB or small e-NodeB).

[0113] In this application embodiment, the terminal device may also be referred to as user equipment (UE), terminal, access terminal, user unit, user station, mobile station, mobile station (MS), mobile terminal (MT), remote station, remote terminal, mobile device, user terminal, user agent, or user equipment, and can be applied to 4G, 5G, or even 6G systems. The terminal device can provide users with voice and / or data connectivity. Terminal devices can be joint devices that transmit and receive digital signals over ordinary telephone lines, handheld devices with wireless connectivity, vehicle-mounted devices, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), mobile phones, tablets, laptops, PDAs, computers with wireless transceiver capabilities, mobile internet devices (MIDs), wearable devices, head-mounted displays (HMDs), virtual reality (VR) devices (such as VR glasses), augmented reality (AR) devices (such as AR glasses), mixed reality (MR) devices, wireless terminals in industrial control, processing devices connected to wireless modems, tactile terminal devices, vehicle-mounted devices, wireless terminals in self-driving cars, wireless terminals in remote medical care, and smart grids. Wireless terminals in grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, roadside units (RSUs) of the aforementioned wireless terminal types, etc.

[0114] Network equipment can be access network equipment, which is a radio access network (RAN) node (or device) that connects terminal devices to a wireless network. Network equipment includes, but is not limited to: base stations (BS), radio network controllers (RNC), base station controllers (BSC), base transceiver stations (BTS), home base stations (e.g., home evolved Node B, or home Node B, HNB), baseband units (BBU), wireless fidelity (Wi-Fi) access points (AP), wireless relay nodes, wireless backhaul nodes, and transmission and reception points (TRP; or transmission point, TP). A base station is a device deployed in a radio access network that provides wireless communication functions; it can also be called base station equipment, such as evolved Node B (eNB or e-NodeB) in LTE systems, Node B (NB), base stations (gNodeB or gNB) in 5G systems, and base stations in 6G systems. A base station can contain a Base Station Unit (BBU) and a Remote Radio Unit (RRU). The BBU and RRU can be located in different places; for example, the RRU can be deployed remotely to a high-traffic area, while the BBU is located in the central equipment room. Alternatively, the BBU and RRU can be located in the same equipment room. The BBU and RRU can also be different components within the same rack. Base stations can take the following forms: macro base stations, micro base stations (also known as small cells), pico base stations, relay stations, access points, balloon stations, etc.

[0115] Optionally, in some network device deployments, the network device may include a central unit (CU) and / or a distributed unit (DU). Where the network device includes both CU and DU, it employs a CU-DU separation architecture, also known as a distributed deployment architecture. In this case, the functions of the network device can be split, with some functions deployed in a CU and the remaining functions in DUs; multiple DUs can share a single CU. Furthermore, the separation of CU and DU can be based on the protocol stack. For example, in an LTE system, the protocol layer of the eNB can be split, with some protocol layer functions centrally controlled by the CU, and the remaining partial or complete protocol layer functions distributed in DUs and centrally controlled by the DUs. In further deployments, the CU can be divided into CU-control plane (CP) and CU-user plane (UP), etc. In still other deployments, the network device can also be an open radio access network (ORAN) architecture, etc. This application does not limit the specific deployment method of the network device.

[0116] For example, combining Figure 2 Logically, a network device may include one CU and one or more DUs. Each DU can connect to the CU via an F1 interface, and information exchange between different DUs can be completed based on forwarding by the CU. The CU and DU can be physically set together or physically separated; there is no limitation on this. The CU can support the functions of the radio resource control (RRC) layer, the service data adaptation protocol (SDAP) layer, and the packet data convergence protocol (PDCP) layer. The DU can support the functions of the radio link control (RLC) layer, the media access control (MAC) layer, and the physical layer (PHY). Figure 2 The following is an example of a network device consisting of one CU and two DUs.

[0117] The network architecture described in this application is for the purpose of more clearly illustrating the technical solutions of this application and does not constitute a limitation on the technical solutions provided in this application. As network architectures evolve and new service scenarios emerge, the technical solutions provided in this application are also applicable to similar technical problems.

[0118] The relevant concepts involved in the embodiments of this application are described below.

[0119] 1. Source network equipment and target network equipment, source cell and target cell, candidate cell and candidate network equipment

[0120] For a handover of a terminal device, the network device providing services to the terminal device before the handover is the source network device, and the cell the terminal device accessed before the handover is the source cell, managed by the source network device. The network device providing services to the terminal device after the handover is the target network device, and the cell the terminal device accesses after the handover is the target cell, managed by the target network device. In this embodiment, the cell accessed by the terminal device can also be called the serving cell of the terminal device, and the network device accessed by the terminal device can also be called the serving network device, which provides services to the terminal device.

[0121] For example, the cell that the terminal device accesses is cell 1, which is managed by network device 1. After the terminal device switches from cell 1 to cell 2, it accesses cell 2 and is provided with services by network device 2, which manages cell 2. It can be seen that in this switch, the source network device is network device 1, the source cell is cell 1, the target network device is network device 2, and the target cell is cell 2.

[0122] A candidate cell is a cell that a terminal device may hand over to from its serving cell. A candidate cell can be a neighboring cell of the serving cell. There can be one or more candidate cells, and one of these candidate cells is chosen as the target cell for the handover. For example, if the serving cell of the terminal device is cell 1, the candidate cells for handover from cell 1 include cells 2 and 3, with cell 2 serving as the target cell for the handover.

[0123] A candidate network device is a network device that manages candidate cells. For example, the serving network device for a terminal device is network device 1, and the serving cell for the terminal device is cell 1, which is managed by network device 1. Cell 2, managed by network device 2, and cell 3, managed by network device 3, are both candidate cells for the terminal device to hand over from cell 1. Therefore, both network device 2 and network device 3 are candidate network devices for the terminal device to hand over from network device 1. If cell 2 is the target cell for the terminal device to hand over from cell 1, then network device 2 is the target network device for the terminal device to hand over from network device 1.

[0124] 2. Xn Interface

[0125] Network devices can connect via the Xn interface. Messages exchanged between network devices through the Xn interface can also be called Xn messages. For example, in a 5G mobile communication system, base stations connect via the Xn interface; base stations in a 5G mobile communication system can also be referred to as gNBs or ng-eNBs.

[0126] For example, taking gNB as a CU-DU separation architecture, combined with Figure 3 In 5G mobile communication systems, the next-generation radio access network (NG-RAN) includes one or more gNBs. Figure 3 The following example uses two gNBs. The gNBs are connected to the 5G core network (5Gcore, 5GC) via the NG interface, and to each other via the Xn interface. The gNB uses a CU-DU separation architecture; multiple DUs within a gNB share the same CU, or are managed by the same CU. Each DU is connected to the CU via the F1 interface. Figure 3 The example shown uses a gNB consisting of one CU and two DUs. For details on the CU-DU separation architecture, please refer to the preceding explanations, which will not be repeated here. Furthermore, the CU in a gNB can represent the gNB connecting to the core network via the NG interface, or it can represent the gNB connecting to other gNBs via the Xn interface.

[0127] 3. Terminal device Xn application protocol identifier (UE Xn AP ID)

[0128] The UE XnAP ID is used when network devices are connected via the Xn interface. The UE XnAP ID is an identifier assigned by the network device to a terminal device, uniquely identifying the terminal device managed by that network device on an Xn interface. In 5G mobile communication systems, the UE XnAP ID can also be called the NG-RAN node UE XnAPID (NG-RAN node UE XnAP ID), where NG-RAN Node refers to a network node, such as a gNB.

[0129] In scenarios where terminal devices are switching over, the UE XnAP ID assigned by the network device as the source network device can also be called the source node UE XnAP ID, and the UE XnAP ID assigned by the network device as the target network device can also be called the target node UE XnAP ID.

[0130] For example, taking the network device as an NG-RAN node, the allocation of UE XnAPID by the network device as the source network device can also be understood as: an old NG-RAN node UE XnAP ID should be allocated so as to uniquely identify the UE over the Xn interface within a source NG-RAN node.

[0131] Assigning a UE XnAP ID to a network device as a target network device can also be understood as: a new NG-RAN node UE XnAP ID should be assigned so as to uniquely identify the UE over the Xn interface within a target NG-RAN node.

[0132] In addition, the Xn messages transmitted by the source network device and the target network device on the Xn interface carry: a source node UEXnAP ID assigned by the source network device for identifying the terminal device on the Xn interface between the source and target network devices, and a target node UE XnAP ID assigned by the target network device for identifying the terminal device on the Xn interface between the source and target network devices. Thus, the source network device can identify which terminal device the Xn message is associated with based on the source node UEXnAP ID carried in the Xn message. Similarly, the target network device can identify which terminal device the Xn message is associated with based on the target node UE XnAP ID carried in the Xn message.

[0133] For example, network device 1 assigns ID1 as the source node UE XnAP ID for identifying terminal device 1 on the Xn interface between network device 1 and network device 2. Network device 2 assigns ID2 as the target node UE XnAP ID for identifying terminal device 1 on the Xn interface between network device 1 and network device 2. When network device 1 sends an Xn message related to terminal device 1 to network device 2 on the Xn interface, it carries both ID1 and ID2. Thus, network device 2 can identify that the received Xn message is related to terminal device 1 based on the presence of ID2. Similarly, when network device 2 sends an Xn message related to terminal device 1 to network device 1 on the Xn interface, it carries both ID1 and ID2. Thus, network device 1 can identify that the received Xn message is related to terminal device 1 based on the presence of ID1.

[0134] It should be noted that the UE XnAP ID is used as an example of network devices connecting via the Xn interface, but it does not constitute a limitation on the embodiments of this application. With the evolution of network architecture and the emergence of new service scenarios, the interface used for connecting network devices may change. The UE XnAP ID in the embodiments of this application can be replaced with a name derived from the new interface. For example, with the evolution of network architecture, the interface used for connecting network devices changes to the "YY interface." The "UE XnAP ID" in the embodiments of this application can be replaced with "UE YYAP ID," which has similar functions to "UE XnAPID," i.e., it is an identifier assigned by the network device to the terminal device, and this identifier can uniquely identify the identity of the terminal device managed by the network device on a YY interface. For ease of explanation, "UE XnAPID" will be used as an example in the following description.

[0135] 4. UE XnAP ID allocation in the switching scenario

[0136] In a single handover scenario, upon each handover trigger, the source network device sends a handover request message to the target network device. If the target network device agrees to the terminal device handing over to it, it sends a handover request acknowledgement message to the source network device, including the target cell's configuration information. The source network device then sends this target cell's configuration information to the terminal device. During the interaction between the handover request message and the handover request acknowledgement message, the source and target network devices also exchange their respective assigned UE XnAP IDs.

[0137] For example, combining Figure 4 In a handover scenario, the source network device for terminal device 1 is network device 1, and the target network device is network device 2. Network device 1 sends a handover request message to network device 2, which carries ID1. ID1 is the source node UE XnAP ID assigned by network device 1 to identify terminal device 1 on the interface between network device 1 and network device 2. If network device 2 agrees to the handover of terminal device 1 to network device 2, network device 2 sends a handover request confirmation message to network device 1. This confirmation message carries ID1 and ID2, where ID2 is the target node UE XnAPID assigned by network device 2 to identify terminal device 1 on the interface between network device 1 and network device 2. After receiving the handover request confirmation message from network device 2, network device 1 can determine that the confirmation message is a handover request confirmation from network device 2 for terminal device 1 based on ID1 carried in the confirmation message.

[0138] During the handover process from network device 1 to network device 2, all messages related to terminal device 1 exchanged between network device 1 and network device 2 will carry ID1 and ID2, enabling network device 1 and network device 2 to identify that the exchanged messages are related to terminal device 1. For example, the sequence number status transfer (SN Status Transfer) message sent by network device 1 to network device 2 needs to carry ID1 and ID2. After receiving the sequence number status transfer message, network device 2 can determine that the sequence number status transfer message is related to terminal device 1 based on ID2 in the message.

[0139] visible, Figure 4 The described process, designed for single-handover scenarios, enables the allocation and interaction of UE XnAP IDs between the source and target network devices during the handover process. This allows the source and target network devices to identify which terminal device the interacting messages are applicable to. For each handover performed by a terminal device, it is necessary to... Figure 4 The aforementioned process is executed again in its entirety. However, for technologies that support subsequent handover, how to achieve UE XnAP ID allocation and interaction between the source and target network devices during subsequent handover still requires further investigation.

[0140] Specifically, in technologies supporting subsequent handovers, before the terminal device performs its first handover, the serving network device sends a handover request message to each candidate network device to obtain pre-configuration information for each candidate network device, and then sends this pre-configuration information to the terminal device. However, how the source and target network devices allocate and interact with the UE XnAP ID required for transmitting terminal-related messages between them for any subsequent handover requires further investigation. If the source and target network devices do not allocate the UE XnAP ID required for transmitting terminal-related messages, they will be unable to transmit terminal-related messages. Alternatively, even if the source network device sends a terminal-related message, the target network device may not be able to identify the terminal device to which the message is addressed. Similarly, even if the target network device sends a terminal-related message, the source network device may not be able to identify the terminal device to which the message is addressed, leading to handover failure.

[0141] The embodiments of this application are described in detail below with reference to the accompanying drawings. This application uses network devices and terminal devices as examples to illustrate the corresponding methods, but this application does not limit the executing entity of the method. For example, the device in the method can also be a chip, chip system, or processor that supports the device in implementing the corresponding method, or it can be a logic module or software that can implement all or part of the device's functions.

[0142] For ease of explanation, the following will be combined with Figures 5 to 10 This explanation uses network device 1, network device 2, network device 3, and a terminal device as examples. Network device 1 is the network device configured for multiple handovers (or subsequent handovers) of the terminal device. It can also be understood as: network device 1 can configure multiple candidate network devices for the terminal device to perform multiple handovers (or subsequent handovers), and the terminal device can perform multiple handovers (or subsequent handovers) among these candidate network devices. Network devices 2 and 3 are candidate network devices for the terminal device to perform multiple handovers (or subsequent handovers). Furthermore, cell 1 is the cell managed by network device 1 that provides services to the terminal device; cell 2 and cell 3 are candidate cells for the terminal device to perform multiple handovers (or subsequent handovers). Cell 2 is managed by network device 2, and cell 3 is managed by network device 3.

[0143] Optionally, network device 1 is the network device that initially triggers mobility technology. Network device 1 can also be referred to as the initial source network device, and cell 1 can also be referred to as the initial source cell. The initial source network device can also be considered as the network device that initially provides candidate cell configuration to the terminal device. In addition, the initial source network device can also be understood as the source network device for the terminal device's first handover; the initial source cell can also be understood as the source cell for the terminal device's first handover. For example, the embodiments of this application can be applied to layer 1 (L1) / layer 2 (L1) triggered mobility (LTM) technology that supports subsequent handovers, where network device 1 is the network device that initially initiates LTM. Here, L1 is the physical layer, and L2 is the MAC layer, RLC layer, PDCP layer, or SDAP layer. In addition to LTM technology, the embodiments of this application can also be applied to other mobility technologies that support subsequent handover, such as layer 3 (L3) handover technology, where L3 refers to the RRC layer. L3 handover technology is a handover technology in which the handover decision-related actions are mainly performed by L3. This application does not limit the specific handover technology.

[0144] Alternatively, the candidate network device for multiple handovers (or subsequent handovers) by the terminal device may include network device 1, and the candidate cell for multiple handovers (or subsequent handovers) by the terminal device may include cell 1. Understandably, after the terminal device hands over from network device 1 to another network device, network device 1 can also be a candidate network device for the terminal device to handover from other network devices, and the terminal device can also access network device 1 during subsequent handovers. Correspondingly, after the terminal device hands over from cell 1 to another cell, cell 1 can also be a candidate cell for the terminal device to handover from other network devices, and the terminal device can also access cell 1 during subsequent handovers.

[0145] Please see Figure 5 , Figure 5 This is a flowchart illustrating a communication method provided in an embodiment of this application. The communication method includes the following steps.

[0146] S101, Network device 1 sends message 1 to network device 2. Message 1 is used to request configuration information of candidate cells. Message 1 includes identifier 1 and reference identifier information 1. Correspondingly, network device 2 receives message 1 from network device 1.

[0147] Here, Identifier 1 is an identifier assigned by network device 1 as the source network device to identify the terminal device on the interface between network device 1 and network device 2. For example, Identifier 1 is the source node UE XnAP ID assigned by network device 1 to identify the terminal device on the Xn interface between network device 1 and network device 2.

[0148] Reference identification information 1 is used to identify the terminal device. Reference identification information 1 can uniquely identify the terminal device within a certain geographical area (which may be a predefined area). Alternatively, reference identification information 1 can uniquely identify the terminal device during multiple handovers (including the first handover initiated by network device 1 and subsequent handovers). Understandably, reference identification information 1 enables network device 1, network device 2, and network device 3 to identify the terminal device during multiple handovers.

[0149] For example, reference identification information 1 consists of the identifier of network device 1 and the identifier of terminal device. The identifier of network device can be, for example, a gNB ID. The identifier of terminal device is assigned to terminal device by network device 1, and can be, for example, a random number assigned to terminal device by network device 1 or a source node UE XnAP ID, etc.

[0150] Alternatively, message 1 could be a handover request message sent by network device 1 to network device 2.

[0151] S102, Network device 1 sends message 2 to network device 3. Message 2 is used to request configuration information of candidate cells. Message 2 includes identifier 2 and reference identifier information 1. Correspondingly, network device 3 receives message 2 from network device 1.

[0152] Here, identifier 2 is an identifier assigned by network device 1 as the source network device to identify the terminal device on the interface between network device 1 and network device 3. For example, identifier 2 is the source node UE XnAP ID assigned by network device 1 to identify the terminal device on the Xn interface between network device 1 and network device 3. For a detailed explanation of reference identifier information 1, please refer to the foregoing related explanations, which will not be repeated here. Additionally, message 2 may be, for example, a handover request message sent by network device 1 to network device 3.

[0153] In one alternative implementation, identifier 1 and identifier 2 may be the same or different.

[0154] In the case where identifier 1 and identifier 2 are the same, it can also be understood that the same identifier assigned by network device 1 as the source network device can be used by network device 1 to identify the terminal device on the interface with network device 2, and can also be used by network device 1 to identify the terminal device on the interface with network device 3.

[0155] The difference between identifier 1 and identifier 2 can also be understood as follows: the identifier assigned by network device 1 as the source network device for identifying the terminal device on the interface with network device 2 is different from the identifier used for identifying the terminal device on the interface with network device 3.

[0156] S103, Network device 2 sends message 3 to network device 1. Message 3 includes configuration information 1, identifier 1, and identifier 3. Correspondingly, network device 1 receives message 3 from network device 2.

[0157] In this context, configuration information 1 refers to the configuration information of cell 2, used for terminal devices to access cell 2. Identifier 3 is an identifier assigned by network device 2 as the target network device to identify the terminal device on the interface between network device 1 and network device 2. For example, identifier 3 is the target node UE XnAP ID assigned by network device 2 to identify the terminal device on the Xn interface between network device 1 and network device 2. Additionally, message 3 is, for example, a handover request acknowledgement message sent by network device 2 to network device 1.

[0158] Understandably, after receiving message 1, network device 2, as the target network device, assigns an identifier, i.e., identifier 3, corresponding to identifier 1. In other words, network device 2 assigns an identifier as the target network device to identify the terminal device identified by identifier 1 on its interface with network device 1. Network device 2 also determines configuration information 1 for the terminal device identified by identifier 1, so that the terminal device identified by identifier 1 can access cell 2. Therefore, network device 2 can determine that the following multiple items are associated with the same terminal device: identifier 1, identifier 3, configuration information 1, and reference identifier information 1.

[0159] In addition, it is understandable that message 3 carries not only configuration information 1 and identifier 3, but also identifier 1. This allows network device 1 to determine, based on identifier 1 in message 3, that message 3 is related to the terminal device identified by identifier 1. For example, if message 3 is a handover request confirmation message sent by network device 2 to network device 1, network device 1 can determine, based on identifier 1 in message 3, that the message 3 sent by network device 2 to network device 1 is a handover request confirmation from network device 2 for the terminal device identified by identifier 1.

[0160] In one optional implementation, configuration information 1 includes configuration information to be used by the terminal device when accessing cell 2, which may include at least one of the following: uplink physical channel configuration information, downlink physical channel configuration information, measurement configuration information, or radio bearer-related configuration information. In configuration information 1, the uplink physical channel configuration information is used by the terminal device to configure the uplink physical channel used in cell 2 when accessing cell 2. The downlink physical channel configuration information is used by the terminal device to configure the downlink physical channel used in cell 2 when accessing cell 2. The measurement configuration information is used by the terminal device to configure information such as the time-domain and frequency-domain location of the reference signal to be measured when accessing cell 2. The radio bearer-related configuration information is used by the terminal device to configure the radio bearer for transmitting data with network device 2 when accessing cell 2.

[0161] S104, Network device 3 sends message 4 to network device 1. Message 4 includes configuration information 2, identifier 2, and identifier 4. Correspondingly, network device 1 receives message 4 from network device 3.

[0162] In this context, configuration information 2 refers to the configuration information of cell 3 and is used for terminal devices to access cell 3. Identifier 4 is an identifier assigned by network device 3 as the target network device to identify the terminal device on the interface between network device 1 and network device 3. For example, identifier 4 is the target node UE XnAP ID assigned by network device 3 to identify the terminal device on the Xn interface between network device 1 and network device 3. Additionally, message 4 is, for example, a handover request acknowledgement message sent by network device 3 to network device 1.

[0163] Understandably, after receiving message 2, network device 3, as the target network device, assigns an identifier, i.e., identifier 4, corresponding to identifier 2. In other words, network device 3 assigns an identifier as the target network device to identify the terminal device identified by identifier 1 on its interface with network device 1. Network device 3 also determines configuration information 2 for the terminal device identified by identifier 1, so that the terminal device identified by identifier 1 can access cell 3. Therefore, network device 3 can determine that the following multiple items are associated with the same terminal device: identifier 2, identifier 4, configuration information 2, and reference identifier information 1.

[0164] In addition, it is understandable that message 4 carries not only configuration information 2 and identifier 4, but also identifier 2. This allows network device 1 to determine, based on identifier 2 in message 4, that message 4 is related to the terminal device identified by identifier 2. For example, if message 4 is a handover request confirmation message sent by network device 3 to network device 1, network device 1 can determine, based on identifier 2 in message 4, that sending message 4 to network device 1 by network device 3 is a handover request confirmation from network device 3 for the terminal device identified by identifier 2.

[0165] In one optional implementation, configuration information 2 includes configuration information to be used by the terminal device when accessing cell 3, which may include at least one of the following: uplink physical channel configuration information, downlink physical channel configuration information, measurement configuration information, or radio bearer-related configuration information. Similar to configuration information 1, it can be referred to the foregoing description of configuration information 1, and will not be repeated here.

[0166] S105, Network device 1 sends message 5 to terminal device. Message 5 includes configuration information 1 and configuration information 2.

[0167] In an optional implementation, when the terminal devices managed by network device 1 include multiple terminal devices, network device 1, network device 2, and network device 3 can perform steps S101 to S105 for each of the multiple terminal devices. The following description uses the example of network device 1 managing terminal devices including terminal device 1 and terminal device 2.

[0168] The identifier assigned by network device 1 as the source network device for identifying terminal device 1 on the interface between network device 1 and network device 2 is different from the identifier assigned by network device 1 as the source network device for identifying terminal device 2 on the interface between network device 1 and network device 2.

[0169] The identifier assigned to network device 1 as the source network device for identifying terminal device 1 on the interface between network device 1 and network device 3 is different from the identifier assigned to network device 1 as the source network device for identifying terminal device 2 on the interface between network device 1 and network device 3.

[0170] The identifier assigned to network device 2 as the target network device for identifying terminal device 1 on the interface between network device 1 and network device 2 is different from the identifier assigned to network device 2 as the target network device for identifying terminal device 2 on the interface between network device 1 and network device 2.

[0171] The identifier assigned to network device 3 as the target network device for identifying terminal device 1 on the interface between network device 1 and network device 3 is different from the identifier assigned to network device 3 as the target network device for identifying terminal device 2 on the interface between network device 1 and network device 3.

[0172] The reference identification information that can uniquely identify terminal device 1 within a certain geographical area or during multiple switching processes of terminal device 1 is different from the reference identification information that can uniquely identify terminal device 2 within a certain geographical area or during multiple switching processes of terminal device 2.

[0173] The configuration information determined by network device 2 for terminal device 1 to access cell 2 may be the same as or different from the configuration information for terminal device 2 to access cell 2.

[0174] The configuration information determined by network device 3 for terminal device 1 to access cell 3 may be the same as or different from the configuration information for terminal device 2 to access cell 3.

[0175] The following describes the first and second handover processes of the terminal device, taking cell 2 as the target cell for the first handover and cell 3 as the target cell for the second handover as an example, as described in steps S106 to S115 below.

[0176] S106. Network device 1 sends handover command 1 to the terminal device, which instructs the terminal device to hand over to cell 2. Correspondingly, the terminal device receives handover command 1 from network device 1.

[0177] In one optional implementation, the handover command may be carried in a media access control element (MAC CE), downlink control information (DCI), or radio resource control (RRC) messages. This application does not limit the specific signaling carrying method. In the scenario where this application's embodiments are applied to LTM technology, the handover command may be an LTM handover command (LTM HOCMD). Further details will not be elaborated upon below.

[0178] In one optional implementation, the handover command includes the identifier of the target cell, so that the terminal device can determine the target cell based on the identifier of the target cell in the handover command, and then the terminal device can handover to the target cell based on the configuration information of the target cell. In this embodiment, the cell identifier can be, for example, a cell global identifier (CGI), a physical cell identifier (PCI), or a configured cell identifier (ID), and there is no limitation thereto. Further details will not be elaborated below.

[0179] For example, handover command 1 can be carried in MAC CE, DCI, or RRC, without limitation. Handover command 1 may include the identifier of cell 2, so that the terminal device can determine that the target cell for handover is cell 2 based on the identifier of cell 2, and then the terminal device can handover to cell 2 based on configuration information 1. In addition, other handover commands mentioned later (such as handover command 2) are similar and will not be described in detail.

[0180] S107, Network device 1 sends message 6 to network device 2. Message 6 notifies network device 2 that the terminal device has switched from network device 1 to network device 2. Message 6 includes identifier 1 and identifier 3. Correspondingly, network device 2 receives message 6 from network device 1.

[0181] Message 6 is, for example, a handover notification message sent by network device 1 to network device 2. For instance, in the scenario of applying LTM technology in this embodiment, message 6 could be an LTM notification message sent by network device 1 to network device 2. Furthermore, regarding identifiers 1 and 3, please refer to the foregoing descriptions, which will not be repeated here.

[0182] Understandably, after receiving message 6, network device 2 can determine the identity of the terminal device switching from network device 1 to network device 2 based on the identifier 3 carried in message 6. Network device 2 can also determine the context of the terminal device, including configuration information 1 associated with the same terminal device as the identifier 3. Thus, during the process of the terminal device switching from network device 1 to network device 2, network device 2 can communicate with the terminal device based on configuration information 1, which helps the terminal device to successfully switch from network device 1 to network device 2.

[0183] S108. The terminal device switches to cell 2 based on configuration information 1. For details on configuration information 1, please refer to the aforementioned explanation; it will not be repeated here.

[0184] S109, Network device 2 sends message 7 to network device 3. Message 7 includes reference identification information 1 and identification 5. Correspondingly, network device 3 receives message 7 from network device 2.

[0185] Here, identifier 5 is an identifier assigned by network device 2 as the source network device for identifying the terminal device on the interface between network device 2 and network device 3. For example, identifier 5 is the source node UE XnAP ID assigned by network device 2 for identifying the terminal device on the Xn interface between network device 2 and network device 3. For reference identifier information 1, please refer to the foregoing explanation, which will not be repeated here.

[0186] S110 and network device 3 determine the context of the terminal device based on reference identification information 1.

[0187] S111, Network device 3 assigns identifier 6 to the terminal device.

[0188] Here, identifier 6 is an identifier assigned by network device 3 as the target network device for identifying the terminal device on the interface between network device 2 and network device 3. For example, identifier 6 is the target node UE XnAP ID assigned by network device 3 for identifying the terminal device on the Xn interface between network device 2 and network device 3.

[0189] In addition, the method also includes: network device 3 associating identifier 6 with the context of terminal device.

[0190] Understandably, after receiving message 7, network device 3 identifies the terminal device identified by reference identification information 1 in message 7 and determines the context of the terminal device. Network device 3 also associates identifier 6 with the context of the terminal device. In this embodiment, the context of the terminal device includes, for example, configuration information for the terminal device to access the cell.

[0191] For example, taking the terminal devices managed by network device 1 as including terminal device 1 and terminal device 2 as an example. For terminal device 1, reference identification information 1 that can uniquely identify terminal device 1 within a certain geographical area or during multiple handovers of terminal device 1 is reference identification information 1a, and configuration information 2 used for terminal device 1 to access cell 3 is configuration information 2a. Based on steps S102 and S104, network device 3 determines that reference identification information 1a and configuration information 2a are associated with terminal device 1. For terminal device 2, reference identification information 1 that can uniquely identify terminal device 2 within a certain geographical area or during multiple handovers of terminal device 2 is reference identification information 1b, and configuration information 2 used for terminal device 2 to access cell 3 is configuration information 2b. Based on steps S102 and S104, network device 3 determines that reference identification information 1b and configuration information 2b are associated with terminal device 2.

[0192] If the reference identification information 1 carried in message 7 received by network device 3 is reference identification information 1a, network device 3 can identify that the terminal device subsequently switching from network device 2 to network device 3 is terminal device 1. Network device 3 can determine that configuration information 2a is associated with the same terminal device (i.e., terminal device 1) as reference identification information 1a. Network device 3 also associates identifier 6 with configuration information 2a. This is beneficial for network device 3 to subsequently determine, based on identifier 6 carried in the handover notification message from network device 2, that the context corresponding to terminal device 1 subsequently switching from network device 2 to network device 3 includes configuration information 2a. Therefore, when terminal device 1 switches from network device 2 to network device 3, network device 3 can communicate with terminal device 1 based on configuration information 2a, which helps terminal device 1 to successfully switch from network device 2 to network device 3.

[0193] S112, Network device 3 sends message 8 to network device 2. Message 8 includes identifier 5 and identifier 6. Correspondingly, network device 2 receives message 8 from network device 3.

[0194] Understandably, message 8 includes not only identifier 6 but also identifier 5. This allows network device 2 to determine, based on identifier 5 in message 8, that identifier 6 and identifier 5 are associated with the same terminal device. Thus, network device 2 can carry identifier 5 and identifier 6 when sending messages related to the terminal device on the interface with network device 3, so that network device 3 can identify that the message is related to the terminal device identified by identifier 6 based on identifier 6 carried in the message received on the interface with network device 2.

[0195] In an optional implementation, steps S109 to S112 can be executed after the terminal device completes the first handover, that is, after the terminal device connects to the target network device of the first handover, i.e., network device 2. Understandably, network device 2 executes steps S109 to S112 after the terminal device connects to network device 2. Figure 6 The following diagram illustrates steps S109 to S112 performed after step S108. As can be seen, in this method, network device 2, as the source network device, allocates an identifier for identifying the terminal device on the interface between network device 2 and other network devices (including network device 3) only after the terminal device has connected to network device 2. Upon receiving this identifier, other network devices, acting as the target network device, allocate a corresponding identifier and send it to network device 2. However, if the terminal device is not connected to network device 2, network device 2 and other network devices (including network device 3) do not need to allocate or interact with each other for identifying the terminal device on the interface between network device 2 and other network devices, thus reducing overhead.

[0196] In another optional implementation, steps S109 to S112 can be executed before the terminal device performs its first handover. In this case, the serving network device for the terminal device is network device 1. It is understood that before the terminal device performs its first handover, network device 1 provides services to the terminal device. After receiving message 1 in step S102, network device 2 can execute steps S109 to S112 in addition to executing step S103. Therefore, after receiving message 1, network device 2, in addition to acting as the target network device, allocates an identifier for identifying the terminal device on the interface between network device 2 and network device 1 and sends it to network device 1. It can also act as the source network device, allocating an identifier for identifying the terminal device on the interface between network device 2 and other candidate network devices, and sending it along with reference identifier information 1 to other candidate network devices (including network device 3). This allows other candidate network devices to allocate corresponding identifiers as target network devices and associate the allocated identifiers with the context of the terminal device determined based on reference identifier information 1.

[0197] In addition, in this method, after receiving message 2, network device 3, in addition to executing step S104, also allocates an identifier for identifying the terminal device on the interface between network device 3 and network device 2 as the source network device, and sends it and reference identifier information 1 to network device 2. This allows network device 2 to allocate an identifier for identifying the terminal device on the interface between network device 3 and network device 2 as the target network device, and associate it with the context of the terminal device determined based on reference identifier information 1. Similar to steps S109 to S112, further details are omitted.

[0198] S113. Network device 2 sends handover command 2 to the terminal device, which instructs the terminal device to hand over to cell 3. Correspondingly, the terminal device receives handover command 2 from network device 2. This step is similar to step S106, and can be referred to the relevant description of step S106, so it will not be repeated here.

[0199] S114, Network device 2 sends message 9 to network device 3. Message 9 is used to notify network device 3 that the terminal device has switched from network device 2 to network device 3. Message 9 includes identifier 5 and identifier 6. Correspondingly, network device 3 receives message 9 from network device 2.

[0200] Message 9 is, for example, a handover notification message sent by network device 2 to network device 3. For instance, in the scenario of applying LTM technology in this embodiment, message 9 could be an LTM notification message sent by network device 2 to network device 3. Furthermore, regarding identifiers 5 and 6, please refer to the foregoing descriptions, which will not be repeated here.

[0201] Understandably, after receiving message 9, network device 3 can determine the identity of the terminal device switching from network device 2 to network device 3 based on the identifier 6 carried in message 9. Network device 3 can determine the context of the terminal device, including the configuration information 2 associated with the same terminal device as the identifier 6. Thus, during the process of the terminal device switching from network device 2 to network device 3, network device 3 can communicate with the terminal device based on the configuration information 2, which helps the terminal device to successfully switch from network device 2 to network device 3.

[0202] S115. The terminal device switches to cell 3 based on configuration information 2.

[0203] In one optional implementation, the candidate network devices for multiple handovers of the terminal device include not only network device 2 and network device 3, but also other candidate network devices. The following description uses network device 4 as an example, where the candidate cell managed by network device 4 is cell 4:

[0204] When network device 1 executes steps S101 and S102, network device 1 also sends message a to network device 4. Message a requests configuration information for candidate cells. Message a includes identifier a and reference identifier information 1. Identifier a is an identifier assigned by network device 1 as the source network device to identify the terminal device on the interface between network device 1 and network device 4. For example, identifier a is the source node UE XnAP ID assigned by network device 1 to identify the terminal device on the Xn interface between network device 1 and network device 4. Optionally, identifier a and identifier 1 may be the same or different, and identifier a and identifier 2 may be the same or different.

[0205] After receiving message a, network device 4 sends message b to the network device. Message b includes configuration information a, identifier a, and identifier b. Configuration information a is the configuration information of cell 4 and is used for terminal devices to access cell 4. Identifier b is an identifier assigned by network device 4 as the target network device to identify the terminal device on the interface between network device 1 and network device 4. For example, identifier b is the target node UE XnAP ID assigned by network device 4 to identify the terminal device on the Xn interface between network device 1 and network device 4.

[0206] In step S105, the message 5 sent by network device 1 to terminal device includes configuration information 1 and configuration information 2, as well as configuration information a.

[0207] In step S109, network device 2 further sends message c to network device 4. Message c includes reference identification information 1 and identification c. Identifier c is an identifier assigned by network device 2 as the source network device for identifying the terminal device on the interface between network device 2 and network device 4. For example, identification c is the source node UE XnAP ID assigned by network device 2 for identifying the terminal device on the Xn interface between network device 2 and network device 4.

[0208] After receiving message c, network device 4 determines the context of the terminal device, including configuration information a, based on reference identifier information 1. Network device 4 associates identifier d with the determined context of the terminal device. Network device 4 also sends message d to network device 2, message d including identifier c and identifier d. Identifier d is an identifier assigned by network device 4 as the target network device for identifying the terminal device on the interface between network device 2 and network device 4. For example, identifier d is the target node UE XnAP ID assigned by network device 4 for identifying the terminal device on the Xn interface between network device 2 and network device 4. Similar to steps S110 to S112, refer to the foregoing description of steps S110 to S112, and will not be repeated here.

[0209] In addition, the above steps only describe the process of the first and second handovers. It should be understood that this can be extended to the process of the third, fourth, and subsequent handovers. The process of each subsequent handover is similar and will not be described again.

[0210] Optionally, if steps S109 to S112 are performed after the terminal device completes the first handover, that is, when a network device allocates and interacts with other network devices only after the terminal device has connected to it, if the source and target network devices in a subsequent handover are the same as those in a previous handover, it indicates that the allocation and interaction of the UE XnAP ID between the source and target network devices in the subsequent handover has been completed. Therefore, operations similar to steps S109 to S112 may not be performed during the subsequent handover. For example, if the source network device in the second handover is network device 2 and the target network device is network device 3; and the source network device in the fourth handover is network device 2 and the target network device is network device 3; then, during the fourth handover, operations similar to steps S109 to S112 may not be performed between network device 2 and network device 3.

[0211] Please see Figure 6 , Figure 6 This is a flowchart illustrating another communication method provided in an embodiment of this application. Figure 6The communication method described above and Figure 5 The communication methods described are similar, but there are differences, which are mainly explained below. Figure 6 The communication method described above and Figure 5 The differences between the aforementioned communication methods. Figure 6 The communication method shown includes the following steps.

[0212] S201, Network device 1 sends message 1 to network device 2. Message 1 is used to request configuration information of candidate cells. Message 1 includes identifier 1. Correspondingly, network device 2 receives message 1 from network device 1.

[0213] Here, Identifier 1 is an identifier assigned by network device 1 as the source network device to identify the terminal device on the interface between network device 1 and network device 2. For example, Identifier 1 is the source node UE XnAP ID assigned by network device 1 to identify the terminal device on the Xn interface between network device 1 and network device 2.

[0214] It is evident that the difference between step S201 and step S101 lies in the fact that, in step S201, message 1 sent by network device 1 to network device 2 does not include reference identification information 1. For a detailed explanation of reference identification information 1, please refer to... Figure 5 The relevant descriptions of the communication method will not be repeated here.

[0215] S202, Network device 1 sends message 2 to network device 3. Message 2 is used to request configuration information of candidate cells, and message 2 includes identifier 2. Correspondingly, network device 3 receives message 2 from network device 1.

[0216] Here, identifier 2 is an identifier assigned by network device 1 as the source network device for identifying the terminal device on the interface between network device 1 and network device 3. For example, identifier 2 is the source node UE XnAP ID assigned by network device 1 for identifying the terminal device on the Xn interface between network device 1 and network device 3.

[0217] It is evident that the difference between step S202 and step S102 lies in the fact that, in step S202, the message 2 sent by network device 1 to network device 3 does not include reference identification information 1. For a detailed explanation of reference identification information 1, please refer to... Figure 5 The relevant descriptions of the communication method will not be repeated here.

[0218] In addition, for a detailed explanation of message 1, message 2, identifier 1, and identifier 2, please refer to [link to relevant documentation]. Figure 5 The relevant descriptions of the communication method will not be repeated here.

[0219] S203, Network device 2 sends message 3 to network device 1. Message 3 includes configuration information 1, identifier 1, and identifier 3. Correspondingly, network device 1 receives message 3 from network device 2.

[0220] In this configuration, configuration information 1 is the configuration information for cell 2 and is used for terminal devices to access cell 2. Identifier 3 is an identifier assigned by network device 2 as the target network device for identifying the terminal device on the interface between network device 1 and network device 2. For example, identifier 3 is the target node UE XnAP ID assigned by network device 2 for identifying the terminal device on the Xn interface between network device 1 and network device 2. For a detailed explanation of step S203, please refer to [link to relevant documentation]. Figure 5 The details of step S103 in the communication method will not be repeated here.

[0221] Understandably, since reference identification information 1 is not carried in step S201, after receiving message 3, network device 2 can determine that the following multiple items are associated with the same terminal device: identification 1, identification 3, and configuration information 1, but not reference identification information 1.

[0222] S204, Network device 3 sends message 4 to network device 1. Message 4 includes configuration information 2, identifier 2, and identifier 4. Correspondingly, network device 1 receives message 4 from network device 3.

[0223] Configuration information 2 refers to the configuration information of cell 3 and is used for terminal devices to access cell 3. Identifier 4 is an identifier assigned by network device 3 as the target network device for identifying the terminal device on the interface between network device 1 and network device 3. For example, identifier 4 is the target node UE XnAP ID assigned by network device 3 for identifying the terminal device on the Xn interface between network device 1 and network device 3. For a detailed explanation of step S204, please refer to [link to relevant documentation]. Figure 5 The details of step S104 in the communication method will not be repeated here.

[0224] Understandably, since reference identification information 1 is not carried in step S202, after receiving message 4, network device 3 can determine that the following multiple items are associated with the same terminal device: identification 2, identification 4, and configuration information 2, but not reference identification information 1.

[0225] S205, Network device 1 sends message 5 to terminal device. Message 5 includes configuration information 1 and configuration information 2.

[0226] S206a. Network device 1 sends reference identification information 2 to network device 2 and reference identification information 3 to network device 3. Reference identification information 2 includes either identifier 2 or identifier 4. Reference identification information 3 includes either identifier 1 or identifier 3.

[0227] In this context, identifier 2 is an identifier assigned by network device 1 as the source network device to identify the terminal device on the interface between network device 1 and network device 3, and identifier 4 is an identifier assigned by network device 3 as the target network device to identify the terminal device on the interface between network device 1 and network device 3. Therefore, the reference identifier information 2 sent by network device 1 to network device 2 includes the identifier corresponding to network device 3. This method is advantageous when network device 2 initiates the allocation and exchange of UE XnAP ID with network device 3, by sending identifier 2 or identifier 4 to network device 3. This allows network device 3 to determine that the context of the terminal device includes configuration information 2 associated with the same terminal device as identifier 2 or identifier 4, and associates the identifier assigned by network device 3 as the target network device to identify the terminal device on the interface between network device 2 and network device 3 with configuration information 2. Consequently, when the terminal device switches from network device 2 to network device 3, network device 3 can communicate with the terminal device based on configuration information 2, facilitating a successful switch from network device 2 to network device 3.

[0228] Identifier 1 is an identifier assigned by network device 1 as the source network device to identify the terminal device on the interface between network device 1 and network device 2. Identifier 3 is an identifier assigned by network device 2 as the target network device to identify the terminal device on the interface between network device 1 and network device 2. Therefore, the reference identification information 3 sent by network device 1 to network device 3 includes the identifier corresponding to network device 2. Similar to the process of network device 1 sending reference identification information 2 to network device 2, please refer to the aforementioned explanation, which will not be repeated here.

[0229] Alternatively, the reference identification information 2 sent by network device 1 to network device 2 may be carried in the reference identification information notification message sent by network device 1 to network device 2, and the reference identification information 3 sent by network device 1 to network device 3 may be carried in the reference identification information notification message sent by network device 1 to network device 3.

[0230] In one optional implementation, the reference identification information 2 further includes an identifier of the network device 3; in the reference identification information 2, identifier 2 or identifier 4 corresponds to the identifier of the network device 3. And / or, the reference identification information 3 further includes an identifier of the network device 2; in the reference identification information 3, identifier 1 or identifier 3 corresponds to the identifier of the network device 2.

[0231] S206b, Network device 1 sends reference identification information 2 to network device 2. Reference identification information 2 includes identification 2 or identification 4.

[0232] For a detailed explanation of step S206b, please refer to the relevant explanation of "network device 1 sends reference identification information 2 to network device 2" in step S206a, which will not be repeated here.

[0233] In this case, one of steps S206a and S206b is executed, while the other step is not executed.

[0234] If step S206a is executed, step S206a can be executed when network device 1 has not yet determined the target network device for the first handover of the terminal device. Understandably, when network device 1 has not yet determined the target network device for the first handover of the terminal device, network device 1 can send reference identification information to each candidate network device for subsequent handovers of the terminal device.

[0235] If step S206b is executed, step S206b can be executed when network device 1 determines that the target network device for the first handover of the terminal device is network device 2. When network device 1 determines that the target network device for the first handover of the terminal device is network device 2, network device 1 sends reference identification information 2 to network device 2, but does not need to send reference identification information to non-target network devices for the first handover of the terminal device, including not needing to send reference identification information 3 to network device 3.

[0236] The following describes the handover process of the terminal device, taking cell 2 as the target cell for the first handover and cell 3 as the target cell for the second handover as an example, as described in steps S207 to S216 below.

[0237] S207. Network device 1 sends handover command 1 to the terminal device, which instructs the terminal device to hand over to cell 2. Correspondingly, the terminal device receives handover command 1 from network device 1. This step S207 can be found in [reference needed]. Figure 5 The details of step S106 in the communication method will not be repeated here.

[0238] S208, Network device 1 sends message 6 to network device 2. Message 6 notifies network device 2 that the terminal device has switched from network device 1 to network device 2. Message 6 includes identifier 1 and identifier 3. Correspondingly, network device 2 receives message 6 from network device 1. This step S208 can be found in [reference needed]. Figure 5 The details of step S107 in the communication method will not be repeated here.

[0239] In an optional implementation, if step S206b is executed, step S206b can be executed in step S208. Specifically, the reference identification information 2 sent by network device 1 to network device 2 can be carried in message 6 sent by network device 1 to network device 2. Alternatively, if step S206b is executed, steps S206b and S208 can be executed separately; that is, the reference identification information 2 sent by network device 1 to network device 2 may not be carried in message 6 sent by network device 1 to network device 2. No limitations are imposed.

[0240] S209. The terminal device switches to cell 2 based on configuration information 1. For details on configuration information 1, please refer to the aforementioned explanation; it will not be repeated here.

[0241] S210, network device 2 sends message 7 to network device 3. Message 7 includes reference identification information 4 and identification 5. Correspondingly, network device 3 receives message 7 from network device 2.

[0242] In this context, reference identification information 4 is the identifier corresponding to network device 3 in reference identification information 2; that is, reference identification information 4 is identifier 2 or identifier 4. For a detailed explanation of identifier 2 and identifier 4, please refer to the aforementioned related explanations, which will not be repeated here.

[0243] Identifier 5 is an identifier assigned by network device 2 as the source network device to identify the terminal device on the interface between network device 2 and network device 3. For example, identifier 5 is the source node UE XnAP ID assigned by network device 2 to identify the terminal device on the Xn interface between network device 2 and network device 3.

[0244] As can be seen, the difference between step S210 and step S109 is that in step S210, the message 7 sent by network device 2 to network device 3 carries reference identification information 4, but not reference identification information 1. Therefore, in step S211, network device 3 determines the context of the terminal device based on reference identification information 4.

[0245] S211, Network device 3 determines the context of the terminal device based on reference identification information 4.

[0246] S212, Network device 3 assigns identifier 6 to terminal device.

[0247] Here, identifier 6 is an identifier assigned by network device 3 as the target network device for identifying the terminal device on the interface between network device 2 and network device 3. For example, identifier 6 is the target node UE XnAP ID assigned by network device 3 for identifying the terminal device on the Xn interface between network device 2 and network device 3.

[0248] In addition, the method also includes: network device 3 associating identifier 6 with the context of terminal device.

[0249] Understandably, reference identification information 4 is either identification 2 or identification 4. Since network device 3 can determine through steps S202 and S204 that the following multiple items are associated with the same terminal device: identification 2, identification 4, and configuration information 2, after receiving message 7 carrying reference identification information 4, network device 3 can determine the context of the terminal device based on reference identification information 4, including configuration information 2, which is associated with the same terminal device as reference identification information 4. Network device 3 also associates identification 6 with the context of the terminal device. Therefore, after receiving message 9 from network device 2 (message 9 is used to notify network device 3 that the terminal device has switched from network device 2 to network device 3, and message 9 includes identification 5 and identification 6), network device 3 can communicate with the terminal device based on the configuration information 2 associated with identification 6, which helps the terminal device to successfully switch from network device 2 to network device 3.

[0250] S213, Network device 3 sends message 8 to network device 2. Message 8 includes identifier 5 and identifier 6. Correspondingly, network device 2 receives message 8 from network device 3. This step S213 can be found in [reference needed]. Figure 5 The details of step S112 in the communication method will not be repeated here.

[0251] In one optional implementation, if step S206a is executed, steps S210 to S213 can be executed after the terminal device completes the first handover, that is, after the terminal device connects to the target network device of the first handover, i.e., network device 2. In another optional implementation, if step S206a is executed, steps S109 to S112 can be executed before the terminal device performs the first handover, in which case the serving network device of the terminal device is network device 1. Figure 5 Steps S109 to S112 in the communication method shown are similar and will not be described again.

[0252] S214. Network device 2 sends handover command 2 to the terminal device, which instructs the terminal device to hand over to cell 3. Correspondingly, the terminal device receives handover command 2 from network device 2. This step S214 can be found in [reference needed]. Figure 5 The details of step S113 in the communication method will not be repeated here.

[0253] S215, Network device 2 sends message 9 to network device 3. Message 9 notifies network device 3 that the terminal device has switched from network device 2 to network device 3. Message 9 includes identifier 5 and identifier 6. Correspondingly, network device 3 receives message 9 from network device 2. This step S215 can be found in [reference needed]. Figure 5 The details of step S114 in the communication method will not be repeated here.

[0254] S216. The terminal device switches to cell 3 based on configuration information 2.

[0255] In one optional implementation, for cases where the candidate network devices that the terminal device may switch to from network device 1 include not only network device 2 and network device 3, but also other candidate network devices, the following explanation will take network device 4 as an example, where the candidate cell managed by network device 4 is cell 4:

[0256] When network device 1 executes steps S201 and S202, network device 1 also sends message a to network device 4. Message a requests configuration information for candidate cells, and message a includes identifier a. Identifier a is an identifier assigned by network device 1 as the source network device to identify the terminal device on the interface between network device 1 and network device 4. For example, identifier a is the source node UE XnAP ID assigned by network device 1 to identify the terminal device on the Xn interface between network device 1 and network device 4. Optionally, identifier a may be the same as or different from identifier 1, and identifier a may be the same as or different from identifier 2.

[0257] After receiving message a, network device 4 sends message b to the network device. Message b includes configuration information a, identifier a, and identifier b. Configuration information a is the configuration information of cell 4 and is used for terminal devices to access cell 4. Identifier b is an identifier assigned by network device 4 as the target network device to identify the terminal device on the interface between network device 1 and network device 4. For example, identifier b is the target node UE XnAP ID assigned by network device 4 to identify the terminal device on the Xn interface between network device 1 and network device 4.

[0258] In step S205, the message 5 sent by network device 1 to terminal device includes configuration information 1 and configuration information 2, as well as configuration information a.

[0259] In step S206a, the reference identification information 2 sent by network device 1 to network device 2 includes, in addition to identifier 2 or identifier 4, identifier a or identifier b. In reference identification information 2, identifier 2 or identifier 4 corresponds to network device 3, and identifier a or identifier b corresponds to network device 4. The reference identification information 3 sent by network device 1 to network device 3 includes, in addition to identifier 1 or identifier 3, identifier a or identifier b. In reference identification information 3, identifier 1 or identifier 3 corresponds to network device 2, and identifier a or identifier b corresponds to network device 4. Furthermore, network device 1 also sends reference identification information a to network device 4. Reference identification information a includes identifier 1 or identifier 3 and identifier 2 or identifier 4. In reference identification information a, identifier 1 or identifier 3 corresponds to network device 2, and identifier 2 or identifier 4 corresponds to network device 2.

[0260] In step S206b, the reference identification information 2 sent by network device 1 to network device 2 includes not only identifier 2 or identifier 4, but also identifier a or identifier b. In the reference identification information 2, identifier 2 or identifier 4 corresponds to network device 3, and identifier a or identifier b corresponds to network device 4.

[0261] In step S210, network device 2 further sends message c to network device 4. Message c includes reference identification information b and identifier c. Reference identification information b is the identifier in reference identification information 2 corresponding to network device 4; that is, reference identification information b is identifier a or identifier b. Identifier c is an identifier assigned by network device 2 as the source network device for identifying the terminal device on the interface between network device 2 and network device 4. For example, identifier c is the source node UE XnAP ID assigned by network device 2 for identifying the terminal device on the Xn interface between network device 2 and network device 4.

[0262] After receiving message c, network device 4 determines the context of the terminal device, including configuration information a, based on the reference identification information c. Network device 4 associates identifier d with the determined context of the terminal device. Network device 4 also sends message d to network device 2, message d including identifier c and identifier d. Identifier d is an identifier assigned by network device 4 as the target network device for identifying the terminal device on the interface between network device 2 and network device 4; for example, identifier d is the target node UE XnAP ID assigned by network device 4 for identifying the terminal device on the Xn interface between network device 2 and network device 4. Similar to steps S211 to S213, please refer to the foregoing description of steps S211 to S213, which will not be repeated here.

[0263] Additionally, after step S213 and after network device 2 receives message d from network device 4, the method includes the operation described in either method A or method B.

[0264] Method A: Network device 2 sends reference identification information c to network device 3 and reference identification information d to network device 4. Reference identification information c includes either identifier c or identifier d, and reference identification information d includes either identifier 5 or identifier 6.

[0265] Method B: Network device 2 sends reference identification information c to network device 3. Reference identification information c includes identification c or identification d.

[0266] In this scenario, one of methods A and B is executed, while the other is not. If method A is executed, it can be executed when network device 2 has not yet determined the target network device for the second handover of the terminal device. If method B is executed, it can be executed when network device 2 determines that the target network device for the second handover of the terminal device is network device 3. Furthermore, method A is similar to the aforementioned step S206a, and method B is similar to the aforementioned step S206b. Please refer to the relevant descriptions of steps S206a and S206b; they will not be repeated here.

[0267] In one optional approach, in a scenario where the candidate network device also includes network device 4, the reference identification information 2 sent by network device 1 to network device 2 includes: identifier 2 or identifier 4, identifier of network device 3, identifier a or identifier b, and identifier of network device 4. In the reference identification information 2, identifier 2 or identifier 4 corresponds to the identifier of network device 3, and identifier a or identifier b corresponds to the identifier of network device 4.

[0268] This method helps network device 2 determine that identifier 2 or identifier 4 corresponds to network device 3, and identifier a or identifier b corresponds to network device 4. Therefore, network device 2 can determine the reference identifier information 4 to be sent to network device 3 based on the identifier corresponding to network device 3 in reference identifier information 2, enabling network device 3 to recognize reference identifier information 4 and thus determine the context of the terminal device. Similarly, network device 2 can determine the reference identifier information c to be sent to network device 4 based on the identifier corresponding to network device 4 in reference identifier information 2, enabling network device 4 to recognize reference identifier information c and thus determine the context of the terminal device. Reference identifier information 3 and reference identifier information a are similar to reference identifier information 2 and will not be described further.

[0269] In addition, the above steps only describe the process of the first and second handovers. It should be understood that this can be extended to the process of the third, fourth, and subsequent handovers. The process of each subsequent handover is similar and will not be described again.

[0270] Optionally, if the source and target network devices in a subsequent handover are the same as those in a previous handover, it indicates that the UE XnAP ID allocation has been completed between the source and target network devices in the subsequent handover. In this case, operations similar to steps S210 to S213 may not be performed during the subsequent handover. For example, if the source network device in the second handover is network device 2 and the target network device is network device 3, and the source network device in the fourth handover is network device 2 and the target network device is network device 3, then operations similar to steps S210 to S213 may not be performed between network device 2 and network device 3 during the fourth handover.

[0271] Please see Figure 7 , Figure 7 This is a flowchart illustrating another communication method provided in an embodiment of this application. Figure 7 In the communication method illustrated, for the same terminal device, the network device assigns it a unique identifier to identify the terminal device on interfaces with other candidate network devices. That is, this identifier is applicable to communication between the network device and different interfaces with other candidate network devices. Furthermore, this identifier can be used as both a source node UE XnAP ID and a target node UE XnAP ID. For example, taking the UEXnAP ID as an example, for the same terminal device, the network device assigns it a unique UE XnAP ID. This UE XnAP ID is applicable to communication between the network device and different Xn interfaces with other candidate network devices, and it can be used as both a source node UE XnAP ID and a target node UE XnAP ID. Figure 7 The communication method shown includes the following steps.

[0272] S301, Network device 1 sends message 10 to Network device 2 and Network device 3. Message 10 is used to request configuration information of candidate cells, and message 10 includes identifier 7. Correspondingly, Network device 2 receives message 10 from Network device 1, and Network device 3 receives message 10 from Network device 1.

[0273] Here, identifier 7 is an identifier assigned by network device 1 for use when network device 1 communicates with other network devices (excluding network device 1) for the terminal device. These other network devices include network device 2 and network device 3. For example, identifier 7 can be used by network device 1 on different Xn interfaces to uniquely identify the terminal device. Identifier 7 can serve as the source node UE XnAP ID assigned when network device 1 is the source network device. Identifier 7 can also serve as the target node UE XnAP ID assigned when network device 1 is the target network device. Therefore, identifier 7 can be used by network device 1 to identify the terminal device during multiple handovers.

[0274] For example, identifier 7 can serve as both the source node UE XnAP ID for network device 1 to identify the terminal device at its interface with network device 2, and the target node UE XnAP ID for network device 1 to identify the terminal device at its interface with network device 2. Identifier 7 can also serve as the source node UE XnAP ID for network device 1 to identify the terminal device at its interface with network device 3, and the target node UE XnAP ID for network device 1 to identify the terminal device at its interface with network device 3.

[0275] Alternatively, message 10 could be, for example, a handover request message.

[0276] In an optional implementation, message 10 further includes indication information 1, which indicates the allocation of an identifier to identify the terminal device during multiple handovers, including a first handover and a second handover. Understandably, indication information 1 indicates the allocation of an identifier that uniquely identifies the terminal device. This identifier can also be understood as a terminal device-specific identifier, or a dedicated / unique identifier used for the terminal device during subsequent handovers.

[0277] S302, Network device 2 sends message 11 to network device 1. Message 11 includes configuration information 1, identifier 7, and identifier 8. Correspondingly, network device 1 receives message 11 from network device 2.

[0278] Configuration information 1 refers to the configuration information for cell 2 and is used for terminal devices to access cell 2. For more information on configuration information 1, please refer to [link to configuration information]. Figure 5 The relevant descriptions of the communication method will not be repeated here.

[0279] Identifier 8 is an identifier assigned by network device 2 for use when network device 2 communicates with other network devices (including network device 1 and network device 3) for the terminal device. For example, identifier 8 can be used by network device 2 on different Xn interfaces to uniquely identify the terminal device. Identifier 8 can serve as the source node UE XnAP ID assigned when network device 2 is the source network device. Identifier 8 can also serve as the target node UE XnAP ID assigned when network device 2 is the target network device. Therefore, identifier 8 can be used by network device 2 to identify the terminal device during multiple handovers.

[0280] For example, identifier 8 can serve as both the source node UE XnAP ID for network device 2 to identify the terminal device at its interface with network device 1, and the target node UE XnAP ID for network device 2 to identify the terminal device at its interface with network device 1. Identifier 8 can also serve as the source node UE XnAP ID for network device 2 to identify the terminal device at its interface with network device 3, and the target node UE XnAP ID for network device 2 to identify the terminal device at its interface with network device 3.

[0281] Alternatively, message 11 could be, for example, a handover request acknowledgment message sent by network device 2 to network device 1.

[0282] Understandably, after receiving message 10, network device 2 assigns identifier 8 to the terminal device identified by identifier 7 and establishes an association between identifier 8 and the terminal device's identity. Network device 2 also determines configuration information 1 for the terminal device identified by identifier 7, so that the terminal device identified by identifier 1 can access cell 2. Therefore, network device 2 can determine that the following multiple things are associated with the same terminal device: identifier 7, identifier 8, and configuration information 1. Optionally, if message 10 carries indication information 1, network device 2 assigns identifier 8 and establishes an association between identifier 8 and the terminal device's identity.

[0283] Understandably, in addition to carrying configuration information 1 and identifier 8, message 11 also carries identifier 7. This allows network device 1 to determine, based on identifier 7 in message 10, that message 11 is a message related to the terminal device identified by identifier 7. For example, if message 11 is a handover request confirmation message sent by network device 2 to network device 1, network device 1 can determine, based on identifier 7 in message 11, that the sending of message 11 by network device 2 to network device 1 is a handover request confirmation from network device 2 for the terminal device identified by identifier 7.

[0284] S303, network device 3 sends message 12 to network device 1. Message 12 includes configuration information 2, identifier 7, and identifier 9. Correspondingly, network device 1 receives message 12 from network device 3.

[0285] Configuration information 2 refers to the configuration information for cell 3 and is used for terminal devices to access cell 3. For more information on configuration information 2, please refer to [link to configuration information 2]. Figure 5 The relevant descriptions of the communication method will not be repeated here.

[0286] Identifier 9 is an identifier assigned by network device 3 for use when network device 3 communicates with other network devices (including network device 1 and network device 2) for the terminal device. For example, identifier 9 can be used by network device 3 on different Xn interfaces to uniquely identify the terminal device. Identifier 9 can serve as the source node UE XnAP ID assigned when network device 3 is the source network device. Identifier 9 can also serve as the target node UE XnAP ID assigned when network device 3 is the target network device. Therefore, identifier 9 can be used by network device 3 to identify the terminal device during multiple handovers.

[0287] For example, identifier 9 can serve as both the source node UE XnAP ID for network device 3 to identify the terminal device at its interface with network device 1, and the target node UE XnAP ID for network device 3 to identify the terminal device at its interface with network device 1. Identifier 9 can also serve as the source node UE XnAP ID for network device 3 to identify the terminal device at its interface with network device 2, and the target node UE XnAP ID for network device 3 to identify the terminal device at its interface with network device 2.

[0288] Alternatively, message 12 could be, for example, a handover request acknowledgement message sent by network device 2 to network device 1. Step S303 is similar to step S302, and can be referred to the aforementioned description of step S302, so it will not be repeated here.

[0289] S304. Network device 1 sends configuration information 1 and configuration information 2 to the terminal device. Correspondingly, the terminal device receives configuration information 1 and configuration information 2 from network device 1.

[0290] In an optional implementation, when the terminal devices managed by network device 1 include multiple terminal devices, network device 1, network device 2, and network device 3 can perform steps S301 to S304 for each of the multiple terminal devices. The following description uses the example of network device 1 managing terminal devices including terminal device 1 and terminal device 2.

[0291] The identifier assigned by network device 1 for use when network device 1 communicates with other network devices for use with terminal device 1 is different from the identifier assigned by network device 1 for use when network device 1 communicates with other network devices for use with terminal device 2.

[0292] The identifier assigned to network device 2 for use when network device 2 communicates with other network devices for use with terminal device 1 is different from the identifier assigned to network device 2 for use when network device 2 communicates with other network devices for use with terminal device 2.

[0293] The identifier assigned by network device 3 for use when network device 3 communicates with other network devices (excluding network device 3) in relation to terminal device 1 is different from the identifier assigned by network device 3 for use when network device 3 communicates with other network devices (excluding network device 3) in relation to terminal device 2.

[0294] The configuration information determined by network device 2 for terminal device 1 to access cell 2 may be the same as or different from the configuration information for terminal device 2 to access cell 2.

[0295] The configuration information determined by network device 3 for terminal device 1 to access cell 3 may be the same as or different from the configuration information for terminal device 2 to access cell 3.

[0296] S305a, Network device 1 sends message 13 to network device 2 and network device 3. Message 13 includes identifier 8 and identifier 9.

[0297] Understandably, each identifier in message 13 corresponds to the network device that assigned that identifier. For example, in message 13, identifier 8 corresponds to network device 2, and identifier 9 corresponds to network device 3. Optionally, message 13 includes: identifier 8, identifier of network device 2, identifier 9, and identifier of network device 4, where identifier 8 corresponds to the identifier of network device 2, and identifier 9 corresponds to the identifier of network device 4.

[0298] This method helps network device 2 determine that identifier 9 corresponds to network device 3. As a result, network device 2 can determine that when sending relevant messages about the terminal device to network device 3, it should carry identifier 9. This enables network device 3 to determine that the message received from network device 2 is related to the terminal device identified by identifier 9, and to determine that the context of the terminal device includes configuration information 2 associated with the same terminal device as identifier 9. Therefore, when the terminal device switches from network device 2 to network device 3, network device 3 can communicate with the terminal device based on configuration information 2, which helps the terminal device to successfully switch from network device 2 to network device 3.

[0299] Additionally, message 13 includes the identifier assigned to the terminal device by each network device participating in the subsequent handover. If network device 1 is also a candidate network device for the subsequent handover of the terminal device, message 13 also includes identifier 7.

[0300] Alternatively, message 13 could be, for example, a UE XnAP ID notification message.

[0301] S305b, Network device 1 sends message 13 to network device 2. Message 13 includes identifier 8 and identifier 9. For details about message 13, please refer to the relevant explanation in step S305a, which will not be repeated here.

[0302] In this case, one of steps S305a and S305b is executed, while the other step is not executed.

[0303] If step S305a is executed, step S305a can be executed when network device 1 has not yet determined the target network device for the first handover of the terminal device. Understandably, when network device 1 has not yet determined the target network device for the first handover of the terminal device, network device 1 can send message 13 to each candidate network device participating in the subsequent handover of the terminal device.

[0304] If step S305b is executed, step S305b can be executed when network device 1 determines that the target network device for the first handover of the terminal device is network device 2. When network device 1 determines that the target network device for the first handover of the terminal device is network device 2, network device 1 sends message 13 to network device 2, but may not send message 13 to non-target network devices for the first handover of the terminal device, including network device 3.

[0305] The following describes the handover process of the terminal device, taking cell 2 as the target cell for the first handover and cell 3 as the target cell for the second handover as an example, as described in steps S306 to S311 below.

[0306] S306. Network device 1 sends handover command 1 to the terminal device, which instructs the terminal device to hand over to cell 2. Correspondingly, the terminal device receives handover command 1 from network device 1. This step S306 can be found in [reference needed]. Figure 5 The details of step S106 in the communication method will not be repeated here.

[0307] S307, Network device 1 sends message 14 to network device 2. Message 14 notifies network device 2 that the terminal device has switched from network device 1 to network device 2. Message 14 includes identifier 7 and identifier 8. Correspondingly, network device 2 receives message 14 from network device 1. This step S307 can be referred to... Figure 5 The details of step S107 in the communication method will not be repeated here.

[0308] In one optional implementation, if step S305b is executed, the message 12 sent by network device 1 to network device 2 in step S305b is the same message as message 6 in step S307, or message 12 can be carried in message 13. Alternatively, if step S305b is executed, step S305b and step S307 can be executed separately. No restrictions are imposed.

[0309] S308, the terminal device switches to cell 2 based on configuration information 1.

[0310] S309, Network device 2 sends handover command 2 to the terminal device, which instructs the terminal device to hand over to cell 3. Correspondingly, the terminal device receives handover command 2 from network device 2. This step S309 can be found in [reference needed]. Figure 5 The details of step S111 in the communication method will not be repeated here.

[0311] S310, Network device 2 sends message 15 to network device 3. Message 15 notifies network device 3 that the terminal device has switched from network device 2 to network device 3. Message 15 includes identifiers 8 and 9. Correspondingly, network device 3 receives message 15 from network device 2. This step S310 can be referenced... Figure 5 The details of step S114 in the communication method will not be repeated here.

[0312] S311. The terminal device switches to cell 3 based on configuration information 2.

[0313] In an optional implementation, if step S305b is executed, the method further includes: when network device 2 determines that the target network device for the second handover of the terminal device is network device 3, it sends message 13 to network device 3. Thus, in this method, message 13 is sent from the source network device in each handover to the target network device in this handover.

[0314] In an optional implementation, the method further includes: network device 1 sending message 16 to network device 2 and / or network device 3, message 16 indicating that the canceled identifier is associated with the identity of the terminal device.

[0315] Understandably, taking the example of network device 1 sending message 16 to network device 2, after receiving message 16, when network device 2 communicates with other network devices for the terminal device, it does not use identifier 8, but uses an identifier assigned according to, for example, the following allocation rules: the identifier assigned by network device 2 as the source network device for identifying the terminal device on the interface with other network devices may be different from the identifier assigned by network device 2 as the target network device for identifying the terminal device on the interface with other network devices. Furthermore, the identifier assigned by network device 2 as the source network device for identifying the terminal device on the interface with different network devices may be different, and the identifier assigned by network device 2 as the target network device for identifying the terminal device on the interface with different network devices may be different.

[0316] For example, taking the UE XnAP ID as an example, after receiving message 16, when network device 2 communicates with other network devices for the terminal device, network device 2 does not use identifier 8, but uses the UE XnAP ID allocated according to the following allocation rules: the target node UE XnAP ID and the source node UE XnAP ID allocated by network device 2 can be different, and the source node UE XnAP ID allocated by network device 2 for identifying the terminal device on the interface with different network devices can be different, and the target node UE XnAP ID allocated by network device 2 for identifying the terminal device on the interface with different network devices can be different.

[0317] In one optional implementation, for cases where the candidate network devices that the terminal device may switch to from network device 1 include not only network device 2 and network device 3, but also other candidate network devices, the following explanation will take network device 4 as an example, where the candidate cell managed by network device 4 is cell 4:

[0318] In step S301, network device 1 also sends message 10 to network device 4. After receiving message 10, network device 4 sends message e to network device 1. Message e includes configuration information a, identifier 7, and identifier e. This operation is similar to steps S302 and S303 and will not be described again. In step S304, network device 1 also sends configuration information a to the terminal device.

[0319] Here, configuration information 'a' is the configuration information for cell 4 and is used by terminal devices to access cell 4. Identifier 'e' is an identifier assigned by network device 4 for communication between network device 4 and other network devices (excluding network device 4) with the terminal device. Network devices other than network device 4 include network device 1, network device 2, and network device 3. Configuration information 'a' is similar to configuration information 1 and configuration information 2, and identifier 'e' is similar to identifiers 7, 8, and 9, so further details are omitted.

[0320] In step S305a, network device 1 also sends message 13 to network device 4. Furthermore, in steps S305a and S305b, message 13 also includes an identifier e, in which the identifier e corresponds to network device 4.

[0321] In addition, the above steps only describe the process of the first and second handovers. It should be understood that this can be extended to the process of the third, fourth, and subsequent handovers. The process of each subsequent handover is similar and will not be described again.

[0322] Optionally, for each handover, if the source network device sends message 13 to the target network device, as in the case where step S305b is executed, and if the source and target network devices in a subsequent handover are the same as those in a previous handover, then the source network device in the subsequent handover process may not need to perform the operation of sending message 13 to the target network device. For example, the source network device in the second handover is network device 2, and the target network device is network device 3; and the source network device in the fourth handover is network device 2, and the target network device is network device 3; since network device 2 has already sent message 13 to network device 3 in the second handover, then network device 2 may not need to perform the operation of sending message 13 to network device 3 in the fourth handover process.

[0323] Please see Figure 8 , Figure 8 This is a flowchart illustrating another communication method provided in an embodiment of this application. Figure 8 The communication method shown is Figure 7 The communication methods shown are similar, but there are differences, namely: Figure 7 In the communication method shown, for the same terminal device, the network device assigns a unique identifier to it. This identifier is used by the network device when communicating with other network devices regarding the terminal device. Furthermore, this unique identifier is both the identifier assigned by the network device as a source network device and the identifier assigned by the network device as a target network device. Figure 8 In the communication method shown, the network device, as the source network device, assigns an identifier for use when communicating with other network devices to a terminal device. The network device, as the target network device, also assigns an identifier for use when communicating with other network devices to a terminal device. These two identifiers may be different. Figure 8 The communication method shown includes the following steps.

[0324] S401, Network device 1 sends message 10 to Network device 2 and Network device 3. Message 10 is used to request configuration information of candidate cells. Message 10 includes identifier 7a and identifier 7b. Correspondingly, Network device 2 receives message 10 from Network device 1, and Network device 3 receives message 10 from Network device 1.

[0325] Here, identifier 7a is an identifier assigned by network device 1 as a source network device for use when network device 1 communicates with other network devices (excluding network device 1) for use with a terminal device. For example, identifier 7a is the source node UEXnAP ID assigned by network device 1 for use when network device 1 communicates with other network devices (excluding network device 1) for use with a terminal device. Network devices other than network device 1 include network device 2 and network device 3.

[0326] Identifier 7b is an identifier assigned by network device 1 as a target network device for use when network device 1 communicates with other network devices (excluding network device 1) for use with a terminal device. For example, identifier 7b is the target node UE XnAPID assigned by network device 1 for use when network device 1 communicates with other network devices (excluding network device 1) for use with a terminal device.

[0327] Identifiers 7a and 7b may be the same or different.

[0328] S402, Network device 2 sends message 11 to network device 1. Message 11 includes configuration information 1, identifier 7a, identifier 7b, identifier 8a, and identifier 8b. Correspondingly, network device 1 receives message 11 from network device 2.

[0329] Here, identifier 8a is an identifier assigned by network device 2 as a source network device for use when network device 2 communicates with other network devices (excluding network device 2) for use with the terminal device. For example, identifier 8a is the source node UEXnAP ID assigned by network device 2 for use when network device 2 communicates with other network devices (excluding network device 2) for use with the terminal device. Network devices other than network device 2 include network device 1 and network device 3.

[0330] Identifier 8b is an identifier assigned by network device 2 as a target network device for use when network device 2 communicates with other network devices for use with a terminal device. For example, identifier 8b is the target node UE XnAPID assigned by network device 2 for use when network device 2 communicates with other network devices for use with a terminal device.

[0331] Identifier 8a and Identifier 8b may be the same or different.

[0332] S403, network device 3 sends message 12 to network device 1. Message 12 includes configuration information 2, identifier 7a, identifier 7b, identifier 9a, and identifier 9b. Correspondingly, network device 1 receives message 12 from network device 3.

[0333] Here, identifier 9a is an identifier assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with the terminal device. For example, identifier 9a is the source node UEXnAP ID assigned by network device 3 for communication between network device 3 and other network devices (excluding network device 3) with the terminal device. Network devices other than network device 3 include network device 1 and network device 2.

[0334] Identifier 9b is an identifier assigned by network device 3 as a target network device for use when network device 3 communicates with other network devices for use with a terminal device. For example, identifier 9b is the target node UE XnAPID assigned by network device 3 for use when network device 3 communicates with other network devices for use with a terminal device.

[0335] Identifier 9a and Identifier 9b may be the same or different.

[0336] S404. Network device 1 sends configuration information 1 and configuration information 2 to the terminal device. Correspondingly, the terminal device receives configuration information 1 and configuration information 2 from network device 1.

[0337] S405a, Network device 1 sends message 13 to Network device 2 and Network device 3. Message 13 includes identifier 8a, identifier 8b, identifier 9a and identifier 9b.

[0338] S405b, Network device 1 sends message 13 to network device 2. Message 13 includes identifier 8a, identifier 8b, identifier 9a and identifier 9b.

[0339] S406. Network device 1 sends handover command 1 to the terminal device, which instructs the terminal device to hand over to cell 2. Correspondingly, the terminal device receives handover command 1 from network device 1.

[0340] S407, Network device 1 sends message 14 to network device 2. Message 14 is used to notify network device 2 that the terminal device has switched from network device 1 to network device 2. Message 14 includes identifier 7a and identifier 8b. Correspondingly, network device 2 receives message 14 from network device 1.

[0341] S408, the terminal device switches to cell 2 based on configuration information 1.

[0342] S409, Network device 2 sends handover command 2 to terminal device, which instructs terminal device to hand over to cell 3. Correspondingly, terminal device receives handover command 2 from network device 2.

[0343] S410, Network device 2 sends message 15 to Network device 3. Message 15 is used to notify Network device 3 that the terminal device has switched from Network device 2 to Network device 3. Message 15 includes identifiers 8a and 9b. Correspondingly, Network device 3 receives message 15 from Network device 2.

[0344] S411. The terminal device switches to cell 3 based on configuration information 2.

[0345] For a detailed explanation of steps S401 to S411 above, please refer to [link / reference]. Figure 7 The relevant descriptions of steps S301 to S311 in the method will not be repeated here.

[0346] In another optional embodiment, for the case where the network device is a CU-DU separated architecture, the Xn interface for communication between network devices corresponds to the interface between CUs, so different network devices communicate through the CU.

[0347] For example, with Figure 5 Taking the method described above as an example, network device 1, network device 2, and network device 3 all use a CU-DU separation architecture, combined with... Figure 9 The communication between network devices 1, network devices 2, and network devices 3 specifically refers to the communication between the CU in network device 1, the CU in network device 2, and the CU in network device 3.

[0348] Additionally, in a CU-DU separated architecture, the handover command can be generated by the CU within the network device and sent to the terminal device. Alternatively, the handover command can be generated by the DU within the network device and sent to the terminal device, with the DU also sending a notification message to the CU to inform it that a handover has occurred.

[0349] For example, such as Figure 9 As shown in the gray solid line box, in step S106, for the L3 handover scenario, the CU in network device 1 can generate handover command 1 and send handover command 1 to the terminal device, as follows: Figure 9 The solid arrow in the middle indicates step S106. For LTM handover scenarios, the DU in network device 1 can generate handover command 1 and send it to the terminal device. The DU in network device 1 also sends a notification message to the CU to notify the CU that an LTM handover has occurred, such as... Figure 9 The dashed arrow in the middle indicates step S106.

[0350] For example, such as Figure 9 As shown in the gray solid line box, in step S113, for the L3 handover scenario, the CU in network device 2 can generate handover command 2 and send handover command 2 to the terminal device, as follows: Figure 9The solid arrow in the middle indicates step S113. For LTM handover scenarios, the DU in network device 2 can generate handover command 2 and send it to the terminal device. The DU in network device 2 also sends a notification message to the CU to notify the CU that an LTM handover has occurred, such as... Figure 9 The dashed arrow in the middle indicates step S113.

[0351] in addition, Figures 5 to 9 This illustration demonstrates a scenario where a network device sends a handover command to a terminal device to trigger a handover. The method provided in this application can also be applied to scenarios where a handover is triggered by a terminal device. In a terminal device-triggered handover scenario, network device 1 sends handover triggering conditions to the terminal device; when the terminal device evaluates that the handover triggering conditions corresponding to the target cell are met, the terminal device hands over to that target cell.

[0352] For example, in a scenario where the handover is triggered by the terminal device, Figure 5 Steps S106 and S113 in the communication method shown may be omitted. Step S106 can be replaced by: Network device 1 sending the handover trigger condition to the terminal device.

[0353] For example, in a scenario where the handover is triggered by the terminal device, Figure 6 Steps S207 and S214 in the communication method shown may be omitted. Step S207 can be replaced by: Network device 1 sending the handover trigger condition to the terminal device.

[0354] For example, in a scenario where the handover is triggered by the terminal device, Figure 7 Steps S306 and S309 in the communication method shown may be omitted. Step S306 can be replaced by: Network device 1 sending the handover trigger condition to the terminal device.

[0355] For example, in a scenario where the handover is triggered by the terminal device, Figure 8 Steps S406 and S409 in the communication method shown may be omitted. Step S406 can be replaced by: Network device 1 sending the handover trigger condition to the terminal device.

[0356] Please see Figure 10 , Figure 10 This is a flowchart illustrating another communication method provided in this application embodiment. In this communication method, network device 1 is the source network device for the terminal device to perform the first handover, network device 2 is the source network device for the terminal device to perform the second handover, and network device 3 is the candidate network device for the terminal device to perform the second handover. Figure 10 The communication method shown includes the following steps.

[0357] S501, Network device 1 sends reference identification information 5 to network device 2. Correspondingly, network device 2 receives reference identification information 5 from network device 1.

[0358] Reference identification information 5 is used to identify terminal equipment.

[0359] In one optional implementation, the reference identification information 5 is used to identify the terminal device within a predefined area. Alternatively, the reference identification information 5 is used by network devices 1, 2, and 3 to identify the terminal device during multiple handovers, including a first handover and a second handover. Therefore, the reference identification information 5 can be as described above. Figure 5 Reference identification information 1 in the communication method shown; for a detailed explanation of reference identification information 1, please refer to [link to relevant documentation]. Figure 5 The specific details of the communication method shown will not be repeated here. Optionally, the reference identification information 5 received by network device 2 from network device 1 can be carried in message 1 sent by network device 1 to network device 2. Message 1 is used to request configuration information of candidate cells.

[0360] In another optional implementation, the reference identification information 5 is either identifier 2 or identifier 4. Identifier 2 is an identifier assigned by network device 1 as the source network device for identifying the terminal device on the interface between network device 1 and network device 3; for example, identifier 2 is the source node UE XnAP ID assigned by network device 1 for identifying the terminal device on the Xn interface between network device 1 and network device 3. Identifier 4 is an identifier assigned by network device 3 as the target network device for identifying the terminal device on the interface between network device 1 and network device 3; for example, identifier 4 is the target node UE XnAP ID assigned by network device 3 for identifying the terminal device on the Xn interface between network device 1 and network device 3. Therefore, the reference identification information 5 can be the aforementioned... Figure 6 Reference identification information 4 in the communication method shown; for a detailed explanation of reference identification information 4, please refer to [link to relevant documentation]. Figure 6 The specific details of the communication method shown will not be repeated here. Optionally, the reference identification information 5 received by network device 2 from network device 1 can be carried in message 6, which is used to notify network device 2 that the terminal device has switched from network device 1 to network device 2.

[0361] S502, Network device 2 sends message 7 to network device 3. Message 7 includes reference identification information 5 and identification 5. Correspondingly, network device 3 receives message 7 from network device 2.

[0362] Here, identifier 5 is an identifier assigned by network device 2 as the source network device for identifying the terminal device on the interface between network device 2 and network device 3. For example, identifier 5 is the source node UE XnAP ID assigned by network device 2 for identifying the terminal device on the Xn interface between network device 2 and network device 3.

[0363] S503 and network device 3 determine the context of the terminal device based on reference identification information 5.

[0364] S504, Network device 3 associates identifier 6 with the context of the terminal device.

[0365] Here, identifier 6 is an identifier assigned by network device 3 as the target network device for identifying the terminal device on the interface between network device 2 and network device 3. For example, identifier 6 is the target node UE XnAP ID assigned by network device 3 for identifying the terminal device on the Xn interface between network device 2 and network device 3.

[0366] Additionally, reference identification information 5 is as described above. Figure 5 In the case of reference identifier information 1 in the communication method shown, a detailed explanation of steps S503 and S504 can be found in [reference needed]. Figure 5 The relevant descriptions of steps S110 and S111 in the communication method shown will not be repeated here.

[0367] Reference identification information 5 is as described above. Figure 6 In the case of reference identifier information 4 in the communication method shown, a detailed explanation of steps S503 and S504 can be found in [reference needed]. Figure 6 The relevant descriptions of steps S211 and S212 in the communication method shown will not be repeated here.

[0368] S505, network device 3 sends identifiers 5 and 6 to network device 2. Correspondingly, network device 2 receives identifiers 5 and 6 from network device 3. Therefore, network device 2 receives identifiers 5 and 6 sent by network device 3 in response to message 7.

[0369] In an optional implementation, the method further includes: network device 2 sending message 9 to network device 3, message 9 including identifier 5 and identifier 6; message 9 is used to notify network device 3 that the terminal device has switched from network device 2 to network device 3. For a detailed explanation, please refer to [link to relevant documentation]. Figure 5 and Figure 6 The relevant descriptions of the communication method will not be repeated here.

[0370] In an optional implementation, the method further includes: network device 1 sending message 1 to network device 2, message 1 requesting configuration information of a candidate cell, message 1 including identifier 1. Network device 2 sending message 3 to network device 1, message 3 including configuration information 1, identifier 1, and identifier 3. Configuration information 1 is the configuration information of cell 2 and is used by terminal device 1 to access cell 2. Identifier 1 is an identifier assigned by network device 1 as a source network device for identifying the terminal device on the interface between network device 1 and network device 2; for example, identifier 1 is the source node UE XnAP ID assigned by network device 1 for identifying the terminal device on the Xn interface between network device 1 and network device 2. Identifier 3 is an identifier assigned by network device 2 as a target network device for identifying the terminal device on the interface between network device 1 and network device 2; for example, identifier 3 is the target node UE XnAP ID assigned by network device 2 for identifying the terminal device on the Xn interface between network device 1 and network device 2. For more information on message 1, message 3, configuration information 1, identifier 1, and identifier 3, please refer to [link to relevant documentation]. Figure 5 and Figure 6 The relevant descriptions of the communication method will not be repeated here.

[0371] In an optional implementation, the method further includes: network device 1 sending message 2 to network device 3, message 2 requesting configuration information of candidate cells, message 2 including identifier 2. Network device 3 sending message 4 to network device 1, message 4 including configuration information 2, identifier 2, and identifier 4. Configuration information 2 is the configuration information of cell 3 and is used by terminal device 1 to access cell 3. Identifier 2 is an identifier assigned by network device 1 as a source network device for identifying the terminal device on the interface between network device 1 and network device 3; for example, identifier 2 is the source node UE XnAP ID assigned by network device 1 for identifying the terminal device on the Xn interface between network device 1 and network device 3. Identifier 4 is an identifier assigned by network device 3 as a target network device for identifying the terminal device on the interface between network device 1 and network device 3; for example, identifier 4 is the target node UE XnAP ID assigned by network device 3 for identifying the terminal device on the Xn interface between network device 1 and network device 3. For more information on message 2, message 4, configuration information 2, identifier 2, and identifier 4, please refer to [link to relevant documentation]. Figure 5 and Figure 6 The relevant descriptions of the communication method will not be repeated here.

[0372] in addition, Figure 10 For a detailed description of each implementation method described herein, please refer to [link / reference]. Figure 5 and Figure 6 The relevant descriptions in the method, Figure 10The method may also include Figure 5 and Figure 6 The methods described also have corresponding beneficial effects, which will not be elaborated further.

[0373] In summary, in this communication method, network device 2, as the source network device, is assigned an identifier, i.e., identifier 5, for identifying the terminal device on the interface between network device 2 and network device 3. Network device 3, as the target network device, is assigned an identifier, i.e., identifier 6, for identifying the terminal device on the interface between network device 2 and network device 3. Furthermore, network device 2 and network device 3 exchange their assigned identifiers so that when the target network device for the second handover of the terminal device is network device 3, network device 2 and network device 3 can carry identifiers 5 and 6 when transmitting messages related to the terminal device. This allows network device 2 to identify the terminal device targeted by the message from network device 3 based on identifier 5, and network device 3 to identify the terminal device targeted by the message from network device 2 based on identifier 6. This facilitates the correct transmission of messages related to a specific terminal device between network device 2 and network device 3.

[0374] Furthermore, network device 2 also receives reference identification information 5 sent by the source network device, i.e., network device 1, when the terminal device performs its first handover. Network device 2 sends reference identification information 5 to network device 3, enabling network device 3 to determine the context of the terminal device based on reference identification information 5 and associate identifier 6 with the context of the terminal device. Thus, when network device 3 determines that the terminal device identified by identifier 6 has switched from network device 2 to network device 3, it can communicate with the terminal device based on the context of the terminal device associated with identifier 6, which helps the terminal device identified by identifier 6 to successfully switch from network device 2 to network device 3.

[0375] Please see Figure 11 , Figure 11 This is a flowchart illustrating another communication method provided in this application embodiment. In this communication method, network device 1 is the source network device for the terminal device to perform the first handover, network device 2 is the source network device for the terminal device to perform the second handover, and network device 3 is the candidate network device for the terminal device to perform the second handover. Figure 11 The communication method shown includes the following steps.

[0376] S601 and network device 2 assign identifier 8 to the terminal device.

[0377] Here, identifier 8 is used by network device 2 to communicate with terminal devices via other network devices besides network device 2. These other network devices include network device 3. For a detailed explanation of identifier 8, please refer to [link to relevant documentation]. Figure 7 The relevant explanations of the communication methods shown will not be repeated here.

[0378] S602, Network device 3 sends identifier 9 to network device 1. Correspondingly, network device 1 receives identifier 9 from network device 3.

[0379] Here, identifier 9 is the identifier assigned by network device 3 to the terminal device. Identifier 9 is used by network device 3 to communicate with other network devices (excluding network device 3) regarding the terminal device. These other network devices include network device 2.

[0380] Optionally, the identifier 9 sent by network device 3 to network device 1 can be carried in message 12. Message 12 includes configuration information 2, identifier 7, and identifier 9. Configuration information 2 is the configuration information of cell 3 and is used by terminal device 1 to access cell 3. Identifier 7 is an identifier assigned by network device 1 for use by network device 1 when communicating with other network devices (excluding network device 1) for terminal device 1. Network devices other than network device 1 include network device 2 and network device 3. For further details, please refer to [link to relevant documentation]. Figure 7 The relevant explanations in the methods shown will not be repeated here.

[0381] Optionally, step S602 can be performed after network device 3 receives message 10 from network device 1. Message 10 is used to request configuration information for candidate cells, and message 10 includes identifier 7. For a detailed explanation, please refer to [link to relevant documentation]. Figure 7 The relevant explanations in the methods shown will not be repeated here.

[0382] S603, Network device 1 sends identifier 9 to network device 2. Correspondingly, network device 2 receives identifier 9 from network device 1.

[0383] In an optional implementation, the method further includes: network device 2 sending identifier 8 to network device 1. Network device 2 receiving identifier 9 from network device 1 includes: network device 2 receiving identifier 8 and identifier 9 from network device 1. For details, please refer to [link to relevant documentation]. Figure 7 The relevant descriptions of steps S305a or S305b in the method will not be repeated here.

[0384] In an optional implementation, the method further includes: network device 2 receiving a message 10 from network device 1, message 10 requesting configuration information of a candidate cell, message 10 including an identifier 7. Network device 2 then sends an identifier 8 to network device 1, including: network device 2 sending a message 11 to network device 1, message 11 including configuration information 1, identifier 7, and identifier 8. The configuration information 1 is the configuration information of cell 2 and is used by terminal device 1 to access cell 2. For further details, please refer to... Figure 7 The relevant explanations in the methods shown will not be repeated here.

[0385] In an optional implementation, message 10 further includes indication information 1, which indicates the allocation of an identifier to identify the terminal device during multiple handovers, including a first handover and a second handover. Understandably, indication information 1 sent by network device 1 to network device 2 instructs network device 2 to allocate an identifier to identify the terminal device during multiple handovers. Indication information 1 sent by network device 1 to network device 3 instructs network device 3 to allocate an identifier to identify the terminal device during multiple handovers. Further details can be found in [link to relevant documentation]. Figure 7 The relevant explanations in the methods shown will not be repeated here.

[0386] In an optional implementation, the method further includes: network device 2 sending message 15 to network device 3, message 15 including identifier 8 and identifier 9; message 15 is used to notify network device 3 that the terminal device has switched from network device 2 to network device 3. For further details, please refer to... Figure 7 The relevant explanations in the methods shown will not be repeated here.

[0387] in addition, Figure 11 For a detailed description of each implementation method described herein, please refer to [link / reference]. Figure 7 The relevant descriptions in the method, Figure 11 The method may also include Figure 7 The methods described also have corresponding beneficial effects, which will not be elaborated further.

[0388] In summary, in this communication method, the identifier 8 assigned by network device 2 can be used by network device 2 to communicate with other network devices (excluding network device 2) regarding terminal devices, so that network device 2 can identify the terminal device through identifier 8 during multiple handovers. Similarly, the identifier 9 assigned by network device 3 can be used by network device 3 to communicate with other network devices (excluding network device 3) regarding terminal devices, so that network device 3 can identify the terminal device through identifier 9 during multiple handovers. Network device 2 receives identifier 9 from the source network device (network device 1) during the first handover of the terminal device. This allows network device 2 to carry identifiers 8 and 9 when sending terminal device-related messages to network device 3 if the target network device for the second handover is network device 3. This enables network device 3 to identify the terminal device to which the transmitted message is targeted based on identifier 9, facilitating the correct transmission of messages related to a specific terminal device between network device 2 and network device 3.

[0389] Furthermore, the identifier 8 assigned to network device 2 can be used by network device 2 when communicating with other network devices for terminal devices. This also eliminates the need for network device 2 to assign an identifier separately to each network device other than network device 2 for terminal device communication, thus reducing the overhead of network device 2. Similarly, the identifier 9 assigned to network device 3 can be used by network device 3 when communicating with other network devices for terminal devices. This also eliminates the need for network device 3 to assign an identifier separately to each network device other than network device 3 for terminal device communication, thus reducing the overhead of network device 3.

[0390] Please see Figure 12 , Figure 12 This is a flowchart illustrating another communication method provided in this application embodiment. In this communication method, network device 1 is the source network device for the terminal device to perform the first handover, network device 2 is the source network device for the terminal device to perform the second handover, and network device 3 is the candidate network device for the terminal device to perform the second handover. Figure 12 The communication method shown includes the following steps.

[0391] S701 and network device 2 assign identifiers 8a and 8b to the terminal devices.

[0392] Specifically, identifier 8a is assigned by network device 2 as a source network device for communication between network device 2 and other network devices (excluding network device 2) with a terminal device. Identifier 8b is assigned by network device 2 as a target network device for communication between network device 2 and other network devices (excluding network device 2) with a terminal device. For a detailed explanation of identifiers 8a and 8b, please refer to [link to relevant documentation]. Figure 8 The relevant explanations of the communication methods shown will not be repeated here.

[0393] S702, Network device 3 sends identifier 9a and identifier 9b to network device 1. Correspondingly, network device 1 receives identifier 9a and identifier 9b from network device 3.

[0394] Specifically, identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. For a detailed explanation of identifiers 9a and 9b, please refer to [link to relevant documentation]. Figure 8 The relevant explanations of the communication methods shown will not be repeated here.

[0395] Optionally, the identifiers 9a and 9b sent by network device 3 to network device 1 can be carried in message 12. Message 12 includes configuration information 2, identifiers 7a, 7b, 9a, and 9b. Configuration information 2 is the configuration information of cell 3 and is used by terminal device 1 to access cell 3. Identifier 7a is an identifier assigned by network device 1 as a source network device for communication between network device 1 and other network devices for communication with the terminal device. Identifier 7b is an identifier assigned by network device 1 as a target network device for communication between network device 1 and other network devices for communication with the terminal device. For a more detailed explanation, please refer to [link to relevant documentation]. Figure 8 The relevant explanations in the methods shown will not be repeated here.

[0396] Optionally, step S702 can be performed after network device 3 receives message 10 from network device 1. Message 10 is used to request configuration information for candidate cells, and message 10 includes identifier 7a and identifier 7b. For a detailed explanation, please refer to [link to relevant documentation]. Figure 8 The relevant explanations in the methods shown will not be repeated here.

[0397] S703, Network device 1 sends identifier 9a and identifier 9b to network device 2. Correspondingly, network device 2 receives identifier 9a and identifier 9b from network device 1.

[0398] In an optional implementation, the method further includes: network device 2 sending identifier 8a and identifier 8b to network device 1. Network device 2 receiving identifier 9a and identifier 9b from network device 1 includes: network device 2 receiving identifiers 8a, 8b, 9a, and 9b from network device 1. For a detailed explanation, please refer to [link to relevant documentation]. Figure 8 The details of steps S405a or S405b in the method will not be repeated here.

[0399] In an optional implementation, the method further includes: network device 2 receiving a message 10 from network device 1, message 10 requesting configuration information of candidate cells, message 10 including identifier 7a and identifier 7b. Network device 2 sending identifier 8a and identifier 8b to network device 1 includes: network device 2 sending a message 11 to network device 1, message 11 including configuration information 1, identifier 7a, identifier 7b, identifier 8a, and identifier 8b. Wherein, configuration information 1 is the configuration information of cell 2 and is used by terminal device 1 to access cell 2. For further details, please refer to... Figure 8 The relevant explanations in the methods shown will not be repeated here.

[0400] In an optional implementation, the method further includes: network device 2 sending message 15 to network device 3, message 15 including identifier 8a and identifier 9b; message 15 is used to notify network device 3 that the terminal device has switched from network device 2 to network device 3. For further details, please refer to... Figure 8 The relevant explanations in the methods shown will not be repeated here.

[0401] in addition, Figure 12 For a detailed description of each implementation method described herein, please refer to [link / reference]. Figure 8 The relevant descriptions in the method, Figure 12 The method may also include Figure 8 The methods described also have corresponding beneficial effects, which will not be elaborated further. Figure 12 The method and Figure 11 The method described above is similar; for details, please refer to [link / reference]. Figure 11 The specific details of the method will not be repeated here.

[0402] in addition, Figure 5 , Figure 6 and Figure 10 The method described can also be adaptively applied to the allocation of user plane tunnel address information. In scenarios where terminal devices switch network equipment, the user plane tunnel address information allocated by the target network device can be used by the source network device to forward data corresponding to the terminal device to the target network device, thereby ensuring service continuity. For a single handover of a terminal device, the source network device will send the data corresponding to the terminal device to the target network device based on the user plane tunnel address information of the target network device. The data corresponding to the terminal device includes: downlink data that the source network device failed to transmit to the terminal device, and / or uplink data that the source network device failed to deliver to the core network. This ensures that after the terminal device successfully switches to the target network device, the target network device can transmit the downlink data that the source network device failed to transmit to the terminal device to the terminal device, and / or send the uplink data that the source network device failed to deliver to the core network to the core network, thereby ensuring service continuity.

[0403] The user plane tunnel address information can be, for example, uplink user plane tunnel address information and / or downlink user plane tunnel address. Uplink user plane tunnel address information can be, for example, uplink user plane transport network layer information (UP TNL information), and downlink user plane tunnel address information can be, for example, downlink UP TNL information. Uplink UP TNL information can include, for example, one or more of the following: uplink transport layer address, or uplink General Packet Radio System (GPRS) tunneling protocol-tunnel endpoint identifier (GTP-TEID); downlink UP TNL information can include, for example, one or more of the following: downlink transport layer address, or downlink GTP-TEID, where the transport layer address is, for example, an Internet Protocol (IP) address. Additionally, user plane tunnel address information can also be referred to as user plane data tunnel address information.

[0404] Combination Figure 10 For example, specifically, in step S501, network device 1 sends reference identification information 5 to network device 2. Reference identification information 5 is used to identify the terminal device. In step S502, network device 2 sends reference identification information 5 to network device 3. Network device 3 determines the context of the terminal device based on reference identification information 5. Network device 3 allocates user plane tunnel address information 1 to the terminal device, where user plane tunnel address information 1 is the user plane tunnel address information of network device 3, and user plane tunnel address information 1 is used by network device 2 to forward data from the terminal device to network device 3. In step S505, network device 3 sends user plane tunnel address information 1 to network device 2. Thus, network device 2 can send data from the terminal device to network device 3 based on user plane tunnel address information 1. For more information on reference identification information 5, please refer to [link to relevant documentation]. Figure 10 The specific details of the method described herein will not be repeated here. This method is similar to... Figure 5 , Figure 6 , Figure 10 The method described above is similar and can be found in the foregoing descriptions; it will not be repeated here.

[0405] To achieve the functions of the methods provided in the embodiments of this application, the network element / device may include hardware structures and / or software modules, implementing the above functions in the form of hardware structures, software modules, or a combination of hardware structures and software modules. Whether a particular function is executed in the form of hardware structures, software modules, or a combination of hardware structures and software modules depends on the specific application and design constraints of the technical solution.

[0406] like Figure 13 As shown, this application embodiment provides a communication device 1300. The communication device 1300 can be a network device, or a component of a network device (e.g., an integrated circuit, a chip, etc.). The communication device 1300 can also be other communication units used to implement the methods in the method embodiments of this application. The communication device 1300 may include a processing unit 1301. Optionally, the communication device 1300 may further include a communication unit 1302, where the processing unit 1301 controls the communication unit 1302 to transmit and receive data / signaling. The communication unit 1302 may also be called a transceiver unit. Optionally, the communication unit 1302 may include a sending unit and a receiving unit. The sending unit can be used to send data / signaling, and the receiving unit can be used to receive data / signaling. Optionally, the communication device 1300 may further include a storage unit 1303, which can be used to store information and / or data and / or instructions, etc. The storage unit 1303 can interact with the processing unit 1301 and also with the communication unit 1302.

[0407] In one possible design, regarding the case where the communication device 1300 is used to implement the functions of the network device 2 in the above method embodiments:

[0408] Communication unit 1302 is configured to receive reference identification information 5 from network device 1. Communication unit 1302 is also configured to send message 7 to network device 3, message 7 including reference identification information 5 and identification 5. Communication unit 1302 is also configured to receive identification 5 and identification 6 sent by network device 3 in response to message 7. Reference identification information 5 is used to identify the terminal device; identification 5 is an identifier assigned by communication device 1300 as the source network device for identifying the terminal device at the interface between communication device 1300 and network device 3; identification 6 is an identifier assigned by network device 3 as the target network device for identifying the terminal device at the interface between communication device 1300 and network device 3. Network device 1 is the source network device for the first handover of the terminal device, communication device 1300 is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0409] In one optional implementation, the reference identification information 5 is used to identify the terminal device within a preset area. Alternatively, the reference identification information 5 is used by network device 1, communication device 1300, and network device 3 to identify the terminal device during multiple handovers, including a first handover and a second handover.

[0410] In an optional implementation, the reference identification information 5 received by the communication device 1300 from the network device 1 is carried in message 1, which is used to request configuration information of candidate cells.

[0411] In one alternative implementation, the reference identification information 5 is identification 2 or identification 4. Identifier 2 is an identifier assigned by network device 1 as the source network device for identifying the terminal device on the interface between network device 1 and network device 3. Identifier 4 is an identifier assigned by network device 3 as the target network device for identifying the terminal device on the interface between network device 1 and network device 3.

[0412] In an optional implementation, the reference identification information 5 received by the communication device 1300 from the network device 1 is carried in a message 6, which is used to notify the communication device 1300 that the terminal device has switched from the network device 1 to the communication device 1300.

[0413] In an optional implementation, the communication unit 1302 is further configured to receive message 1 from network device 1, message 1 requesting configuration information of candidate cells, message 1 including identifier 1. The communication unit 1302 is further configured to send message 3 to network device 1, message 3 including configuration information of cell 2, identifier 1, and identifier 3. Cell 2 is managed by communication device 1300, the configuration information of cell 2 is used for terminal devices to access cell 2, identifier 1 is an identifier assigned by network device 1 as the source network device for identifying the terminal device at the interface between network device 1 and communication device 1300, and identifier 3 is an identifier assigned by communication device 1300 as the target network device for identifying the terminal device at the interface between network device 1 and communication device 1300.

[0414] In an optional implementation, the communication unit 1302 is further configured to send a message 9 to the network device 3, the message 9 including identifier 5 and identifier 6; the message 9 is configured to notify the network device 3 that the terminal device has switched from the communication device 1300 to the network device 3.

[0415] In another possible design, regarding the case where the communication device 1300 is used to implement the functions of the network device 3 in the above method embodiment:

[0416] Communication unit 1302 is used to receive message 7 from network device 2, message 7 including reference identification information 5 and identifier 5. Processing unit 1301 is used to determine the context of terminal device based on reference identification information 5. Processing unit 1301 is also used to associate identifier 6 with the context of terminal device. Communication unit 1302 is also used to send identifier 5 and identifier 6 to network device 2. Reference identification information 5 is used to identify terminal device; identifier 5 is an identifier assigned by network device 2 as the source network device for identifying terminal device on the interface between network device 2 and communication device 1300; identifier 6 is an identifier assigned by communication device 1300 as the target network device for identifying terminal device on the interface between network device 2 and communication device 1300. Network device 2 is the source network device for the second handover of terminal device, and communication device 1300 is the candidate network device for the second handover of terminal device.

[0417] In one optional implementation, the reference identification information 5 is used to identify the terminal device within a preset area. Alternatively, the reference identification information 5 is used by network device 1, network device 2, and communication device 1300 to identify the terminal device during multiple handovers, where network device 1 is the source network device for the first handover of the terminal device, and the multiple handovers include the first handover and the second handover.

[0418] In one optional implementation, the reference identification information 5 is identification 2 or identification 4. Identifier 2 is an identifier assigned by network device 1 as the source network device for identifying the terminal device at the interface between network device 1 and communication device 1300. Identifier 4 is an identifier assigned by communication device 1300 as the target network device for identifying the terminal device at the interface between network device 1 and communication device 1300. Network device 1 is the source network device for which the terminal device performs its first handover.

[0419] In an optional implementation, the communication unit 1302 is further configured to receive a message 2 from the network device 1, the message 2 requesting configuration information for a candidate cell, and the message 2 includes an identifier 2. The communication unit 1302 is also configured to send a message 4 to the network device 1, the message 4 including configuration information for cell 3, identifier 2, and identifier 4. Cell 3 is managed by the communication device 1300; the configuration information for cell 3 is used by the terminal device to access cell 3; identifier 2 is an identifier assigned by the network device 1 as the source network device for identifying the terminal device at the interface between the network device 1 and the communication device 1300; and identifier 4 is an identifier assigned by the communication device 1300 as the target network device for identifying the terminal device at the interface between the network device 1 and the communication device 1300. Network device 1 is the source network device for the terminal device's first handover.

[0420] In one alternative implementation, the context of the terminal device includes the configuration information of cell 3.

[0421] In an optional implementation, the communication unit 1302 is further configured to receive a message 9 from the network device 2, the message 9 including identifier 5 and identifier 6; the message 9 is configured to notify the communication device 1300 that the terminal device has switched from the network device 2 to the communication device 1300.

[0422] In another possible design, regarding the case where the communication device 1300 is used to implement the functions of the network device 2 in the above method embodiment:

[0423] Processing unit 1301 is used to assign identifier 8 to the terminal device. Communication unit 1302 is used to receive identifier 9 from network device 1, where identifier 9 is an identifier assigned to the terminal device by network device 3. Identifier 8 is used by the communication device to communicate with network devices other than communication device 1300 regarding the terminal device, including network device 3. Identifier 9 is used by network device 3 to communicate with other network devices other than network device 3 regarding the terminal device, including the communication device. Network device 1 is the source network device for the first handover of the terminal device, communication device 1300 is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0424] In an optional implementation, the communication unit 1302 is further configured to send identifier 8 to the network device 1. Specifically, the communication unit 1302 receives identifier 9 from the network device 1.

[0425] In an optional implementation, the communication unit 1302 is further configured to receive a message 10 from the network device 1, the message 10 requesting configuration information for a candidate cell, and the message 10 includes an identifier 7. The communication unit 1302 sends an identifier 8 to the network device 1, specifically configured to send a message 11 to the network device 1, the message 11 including configuration information for cell 2, identifier 7, and identifier 8. Cell 2 is managed by the communication device 1300, the configuration information for cell 2 is used by the terminal device to access cell 2, and identifier 7 is used by the network device 1 to communicate with other network devices (excluding network device 1) for the terminal device. The network devices other than network device 1 include the communication device 1300.

[0426] In an optional implementation, message 10 further includes instruction information 1, which instructs the communication device 1300 to identify the terminal device during multiple handovers, including a first handover and a second handover.

[0427] In an optional implementation, the communication unit 1302 is further configured to send a message 15 to the network device 3, the message 15 including identifier 8 and identifier 9; the message 15 is configured to notify the network device 3 that the terminal device has switched from the communication device 1300 to the network device 3.

[0428] In another possible design, regarding the case where the communication device 1300 is used to implement the functions of the network device 1 in the above method embodiment:

[0429] Processing unit 1301 is configured to receive identifier 9 from network device 3. Communication unit 1302 is further configured to send identifier 9 to network device 2. Identifier 9 is used by network device 3 to communicate with other network devices (excluding network device 3) regarding the terminal device. Network devices other than network device 3 include network device 2. Communication device 1300 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0430] In an optional implementation, the communication unit 1302 is further configured to receive an identifier 8 from the network device 2. Specifically, the communication unit 1302 sends an identifier 9 to the network device 2 by sending both identifier 8 and identifier 9.

[0431] In an optional implementation, the communication unit 1302 is further configured to send a message 10 to the network device 2, the message 10 requesting configuration information for candidate cells, and the message 10 includes an identifier 7. The communication unit 1302 receives an identifier 8 from the network device 2, specifically configured to receive a message 11 from the network device 2, the message 11 including configuration information for cell 2, identifier 7, and identifier 8. Cell 2 is managed by the network device 2, the configuration information for cell 2 is used by the terminal device to access cell 2, and identifier 7 is an identifier used by the communication device 1300 to communicate with network devices other than the communication device 1300 for the terminal device. Network devices other than the communication device 1300 include the network device 2.

[0432] In an optional implementation, the communication unit 1302 is further configured to send a message 10 to the network device 3, the message 10 requesting configuration information for candidate cells, and the message 10 includes an identifier 7. The communication unit 1302 receives an identifier 9 from the network device 3, specifically configured to receive a message 12 from the network device 3, the message 12 including configuration information for cell 3, identifier 7, and identifier 9. Cell 3 is managed by the network device 3, and the configuration information for cell 3 is used by the terminal device to access cell 3. Identifier 7 is used by the communication device 1300 to communicate with network devices other than the communication device 1300 for the terminal device; the network devices other than the communication device 1300 include the network device 3.

[0433] In an optional implementation, message 10 further includes indication information 1, which indicates the allocation of an identifier to identify the terminal device during multiple handovers, including a first handover and a second handover.

[0434] In another possible design, regarding the case where the communication device 1300 is used to implement the functions of the network device 2 in the above method embodiment:

[0435] Processing unit 1301 is used to assign identifier 8a and identifier 8b to the terminal device. Communication unit 1302 is used to receive identifier 9a and identifier 9b from network device 1.

[0436] Specifically, identifier 8a is assigned by communication device 1300 as a source network device for communication between communication device 1300 and network devices other than communication device 1300 for communication with a terminal device. Identifier 8b is assigned by communication device 1300 as a target network device for communication between communication device 1300 and network devices other than communication device 1300 for communication with a terminal device. Network devices other than communication device 1300 include network device 3.

[0437] Identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include communication device 1300.

[0438] Network device 1 is the source network device for the first handover of the terminal device, communication device 1300 is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0439] In an optional implementation, the communication unit 1302 is further configured to send identifiers 8a and 8b to the network device 1. Specifically, the communication unit 1302 receives identifiers 9a and 9b from the network device 1.

[0440] In an optional implementation, the communication unit 1302 is further configured to receive a message 10 from the network device 1, the message 10 requesting configuration information for a candidate cell, and the message 10 includes identifiers 7a and 7b. The communication unit 1302 sends identifiers 8a and 8b to the network device 1, specifically configured to send a message 11 to the network device 1, the message 11 including configuration information for cell 2, identifiers 7a, 7b, 8a, and 8b. Cell 2 is managed by the communication device 1300, and the configuration information of cell 2 is used by the terminal device to access cell 2. Identifier 7a is an identifier assigned by the network device 1 as a source network device for communication between the network device 1 and other network devices (excluding the network device 1) with the terminal device. Identifier 7b is an identifier assigned by the network device 1 as a target network device for communication between the network device 1 and other network devices (excluding the network device 1) with the terminal device. The network devices other than the network device 1 include the communication device 1300.

[0441] In an optional implementation, the communication unit 1302 is further configured to send a message 15 to the network device 3, the message 15 including identifier 8a and identifier 9b; the message 15 is configured to notify the network device 3 that the terminal device has switched from the communication device 1300 to the network device 3.

[0442] In another possible design, regarding the case where the communication device 1300 is used to implement the functions of the network device 1 in the above method embodiment:

[0443] The communication unit 1302 is used to receive identifiers 9a and 9b from the network device 3; the communication unit 1302 is also used to send identifiers 9a and 9b to the network device 2.

[0444] In this context, identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include network device 2.

[0445] Communication device 1300 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0446] In an optional implementation, the communication unit 1302 is further configured to receive identifiers 8a and 8b from the network device 2. Specifically, the communication unit 1302 sends identifiers 9a and 9b to the network device 2 by sending identifiers 8a, 8b, 9a, and 9b to the network device 2.

[0447] In an optional implementation, the communication unit 1302 is further configured to send a message 10 to the network device 2, the message 10 requesting configuration information for a candidate cell, and the message 10 includes identifiers 7a and 7b. The communication unit 1302 receives identifiers 8a and 8b from the network device 2, specifically configured to receive a message 11 from the network device 2, the message 11 including configuration information for cell 2, identifiers 7a and 7b, and identifiers 8a and 8b. Cell 2 is managed by the network device 2, and the configuration information for cell 2 is used by the terminal device to access cell 2. Identifier 7a is an identifier assigned by the communication device 1300 as a source network device for communication between the communication device 1300 and other network devices (excluding the communication device 1300) for the terminal device. Identifier 7b is an identifier assigned by the communication device 1300 as a target network device for communication between the communication device 1300 and other network devices (excluding the communication device 1300) for the terminal device. Network devices other than the communication device 1300 include network device 2.

[0448] In an optional implementation, the communication unit 1302 is further configured to send message 10 to the network device 3, message 10 requesting configuration information for candidate cells, and message 10 includes identifiers 7a and 7b. The communication unit 1302 receives identifiers 9a and 9b from the network device 3, specifically configured to receive message 12 from the network device 3, message 12 including configuration information for cell 3, identifiers 7a, 7b, 9a, and 9b. Cell 3 is managed by the network device 3, and the configuration information for cell 3 is used by terminal devices to access cell 3.

[0449] The embodiments of this application and the method embodiments shown above are based on the same concept and have the same technical effects. For the specific principles, please refer to the description of the embodiments shown above, which will not be repeated here.

[0450] This application also provides a communication device 1400, such as... Figure 14 As shown. The communication device 1400 can be a network device, or a chip, chip system, or processor that supports the network device in implementing the above methods. This device can be used to implement the methods described in the above method embodiments, and for details, please refer to the description in the above method embodiments.

[0451] The communication device 1400 may include one or more processors 1401. The processor 1401 can be used to implement some or all of the functions of the network device through logic circuits or by running computer programs. The processor 1401 may be a general-purpose processor or a special-purpose processor, such as a baseband processor, digital signal processor, application-specific integrated circuit, field-programmable gate array or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or CPU. The baseband processor can be used to process communication protocols and communication data, and the central processing unit can be used to control the communication device, execute software programs, and process data from the software programs. The communication device may be, for example, a base station, a baseband chip, a terminal, a terminal chip, a distributed unit (DU), or a centralized unit (CU).

[0452] Optionally, the communication device 1400 may include one or more memories 1402, which may store instructions 1404 that can be executed on the processor 1401, causing the communication device 1400 to perform the methods described in the above method embodiments. Optionally, the memory 1402 may also store data. The processor 1401 and the memory 1402 may be provided separately or integrated together.

[0453] The memory 1402 may include, but is not limited to, non-volatile memory such as hard disk drive (HDD) or solid-state drive (SSD), random access memory (RAM), erasable programmable read-only memory (EPROM), ROM or compact disc read-only memory (CD-ROM), etc.

[0454] Optionally, the communication device 1400 may further include a transceiver 1405 and an antenna 1406. The transceiver 1405 may be referred to as a transceiver unit, transceiver, or transceiver circuit, etc., and is used to implement the transmission and reception functions. The transceiver 1405 may include a receiver and a transmitter. The receiver may be referred to as a receiver or receiving circuit, etc., and is used to implement the receiving function; the transmitter may be referred to as a transmitter or transmitting circuit, etc., and is used to implement the transmitting function.

[0455] In one possible design, regarding the case where the communication device 1400 is used to implement the functions of the network device 2 in the above method embodiments:

[0456] Transceiver 1405 is used to receive reference identification information 5 from network device 1. Transceiver 1405 is also used to send message 7 to network device 3, message 7 including reference identification information 5 and identification 5. Transceiver 1405 is also used to receive identification 5 and identification 6 sent by network device 3 in response to message 7. Reference identification information 5 is used to identify the terminal device; identification 5 is assigned by communication device 1400 as the source network device for identifying the terminal device at the interface between communication device 1400 and network device 3; identification 6 is assigned by network device 3 as the target network device for identifying the terminal device at the interface between communication device 1400 and network device 3. Network device 1 is the source network device for the first handover of the terminal device, communication device 1400 is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0457] In another possible design, regarding the case where the communication device 1400 is used to implement the functions of the network device 3 in the above method embodiment:

[0458] Transceiver 1405 is used to receive message 7 from network device 2, message 7 including reference identification information 5 and identifier 5. Processor 1401 is used to determine the context of the terminal device based on reference identification information 5. Processor 1401 is also used to associate identifier 6 with the context of the terminal device. Transceiver 1405 is also used to send identifier 5 and identifier 6 to network device 2. Reference identification information 5 is used to identify the terminal device; identifier 5 is an identifier assigned by network device 2 as the source network device for identifying the terminal device at the interface between network device 2 and communication device 1400; identifier 6 is an identifier assigned by communication device 1400 as the target network device for identifying the terminal device at the interface between network device 2 and communication device 1400. Network device 2 is the source network device for the second handover of the terminal device, and communication device 1400 is the candidate network device for the second handover of the terminal device.

[0459] In another possible design, regarding the case where the communication device 1400 is used to implement the functions of the network device 2 in the above method embodiment:

[0460] Processor 1401 is used to assign identifier 8 to the terminal device. Transceiver 1405 is used to receive identifier 9 from network device 1, where identifier 9 is an identifier assigned to the terminal device by network device 3. Identifier 8 is used by the communication device to communicate with network devices other than communication device 1400 regarding the terminal device, including network device 3. Identifier 9 is used by network device 3 to communicate with other network devices other than network device 3 regarding the terminal device, including the communication device. Network device 1 is the source network device for the first handover of the terminal device, communication device 1400 is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0461] In another possible design, regarding the case where the communication device 1400 is used to implement the functions of the network device 1 in the above method embodiment:

[0462] Processor 1401 is used to receive identifier 9 from network device 3. Transceiver 1405 is also used to send identifier 9 to network device 2. Identifier 9 is used by network device 3 to communicate with other network devices (including network device 2) regarding the terminal device. Communication device 1400 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0463] In another possible design, regarding the case where the communication device 1400 is used to implement the functions of the network device 2 in the above method embodiment:

[0464] Processor 1401 is used to assign identifier 8a and identifier 8b to terminal devices. Transceiver 1405 is used to receive identifier 9a and identifier 9b from network device 1.

[0465] Specifically, identifier 8a is assigned by communication device 1400 as a source network device for communication between communication device 1400 and network devices other than communication device 1400 for communication with a terminal device. Identifier 8b is assigned by communication device 1400 as a target network device for communication between communication device 1400 and network devices other than communication device 1400 for communication with a terminal device. Network devices other than communication device 1400 include network device 3.

[0466] Identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include communication device 1400.

[0467] Network device 1 is the source network device for the first handover of the terminal device, communication device 1400 is the source network device for the second handover of the terminal device, and network device 3 is the candidate network device for the second handover of the terminal device.

[0468] In another possible design, regarding the case where the communication device 1400 is used to implement the functions of the network device 1 in the above method embodiment:

[0469] Transceiver 1405 is used to receive identifiers 9a and 9b from network device 3; transceiver 1405 is also used to send identifiers 9a and 9b to network device 2.

[0470] In this context, identifier 9a is assigned by network device 3 as a source network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Identifier 9b is assigned by network device 3 as a target network device for communication between network device 3 and other network devices (excluding network device 3) with a terminal device. Network devices other than network device 3 include network device 2.

[0471] Communication device 1400 is the source network device for the first handover of the terminal device, network device 2 is the source network device for the second handover of the terminal device, and network device 3 is the target network device for the second handover of the terminal device.

[0472] In another possible design, the processor 1401 may include a transceiver for implementing receive and transmit functions. For example, the transceiver may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing receive and transmit functions may be separate or integrated. The aforementioned transceiver circuit, interface, or interface circuit may be used for reading and writing code / data, or for transmitting or relaying signals.

[0473] In another possible design, the processor 1401 may optionally store instructions 1403, which, when executed on the processor 1401, cause the communication device 1400 to perform the methods described in the above method embodiments. Instructions 1403 may be embedded in the processor 1401; in this case, the processor 1401 may be implemented in hardware.

[0474] In another possible design, the communication device 1400 may include circuitry that can perform the functions of transmitting, receiving, or communicating as described in the foregoing method embodiments. The processor and transceiver described in this application embodiment can be implemented on integrated circuits (ICs), analog ICs, radio frequency integrated circuits (RFICs), mixed-signal ICs, application-specific integrated circuits (ASICs), printed circuit boards (PCBs), electronic devices, etc. The processor and transceiver can also be manufactured using various IC process technologies, such as complementary metal-oxide semiconductors (CMOS), n-metal-oxide-semiconductor (NMOS), positive-channel metal-oxide semiconductors (PMOS), bipolar junction transistors (BJTs), bipolar CMOS (BiCMOS), silicon-germanium (SiGe), gallium arsenide (GaAs), etc.

[0475] Those skilled in the art will also understand that the various illustrative logical blocks and steps listed in the embodiments of this application can be implemented by electronic hardware, computer software, or a combination of both. Whether such functionality is implemented through hardware or software depends on the specific application and the overall system design requirements. Those skilled in the art can use various methods to implement the described functionality for a specific application, but such implementation should not be construed as exceeding the scope of protection of the embodiments of this application.

[0476] The embodiments of this application and the above-described method embodiments are based on the same concept and have the same technical effects. For the specific principles, please refer to the description in the above-described method embodiments, which will not be repeated here.

[0477] This application also provides a computer-readable storage medium for storing computer software instructions that, when executed by a communication device, implement the functions of any of the above method embodiments.

[0478] This application also provides a computer program product for storing computer software instructions, which, when executed by a communication device, implement the functions of any of the above method embodiments.

[0479] This application also provides a computer program that, when run on a computer, implements the functions of any of the above method embodiments.

[0480] This application also provides a chip including a processor. The processor is used to execute code or instructions to implement the functions of any of the above method embodiments. Optionally, the chip further includes an interface, and the processor is coupled to the interface, which is used to receive or output signals.

[0481] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., SSDs), etc.

[0482] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0483] Furthermore, unless otherwise specified or logically conflicting, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0484] It is understood that some optional features in the various embodiments of this application may not depend on other features in certain scenarios, or may be combined with other features in certain scenarios, without limitation.

[0485] It is understood that the solutions in the embodiments of this application can be used in combination, and the explanations or descriptions of various terms, similar operations or steps appearing in the embodiments can be referenced or explained to each other in the various embodiments, and this application does not limit them.

[0486] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, and c can mean: a, or, b, or, c, or, a and b, or, a and c, or, b and c, or, a, b, and c. Here, a, b, and c can each be single or multiple.

[0487] In this application, the terms "first," "second," and various numerical designations are used for ease of description and are not intended to limit the scope of the embodiments of this application. For example, they may be used to distinguish different messages, rather than to describe a specific order or sequence. It should be understood that such descriptions can be interchanged where appropriate to describe solutions other than those described in this application.

[0488] In this application, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0489] In this application, "for indicating" can include both direct and indirect indication. When describing an indication message as indicating A, it can include whether the indication message directly indicates A or indirectly indicates A, but does not necessarily mean that the indication message carries A.

[0490] In this application, "sending information to XX (device / network element)" can be understood as the destination of the information being that device / network element. This can include sending information directly or indirectly to that device / network element. "Receiving information from XX (device / network element), or receiving information from XX (device / network element)" can be understood as the source of the information being that device / network element. This can include receiving information directly or indirectly from that device / network element. Information may undergo necessary processing between the source and destination, such as format changes, but the destination can understand the valid information from the source.

[0491] In this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner to facilitate understanding.

Claims

1. A communication method, characterized in that, The method includes: The second network device receives reference identification information from the first network device; The second network device sends a first message to the third network device, the first message including the reference identification information and the first identification; The second network device receives the first identifier and the second identifier from the third network device in response to the first message. The reference identification information is used to identify the terminal device. The first identifier is an identifier assigned by the second network device as the source network device for identifying the terminal device at the interface between the second network device and the third network device. The second identifier is an identifier assigned by the third network device as the target network device for identifying the terminal device at the interface between the second network device and the third network device. The first network device is the source network device for the first handover of the terminal device, the second network device is the source network device for the second handover of the terminal device, and the third network device is the candidate network device for the second handover of the terminal device.

2. The method according to claim 1, characterized in that, The reference identification information is used to identify the terminal device within a preset area; or, The reference identification information is used by the first network device, the second network device, and the third network device to identify the terminal device during the multiple handovers of the terminal device, wherein the multiple handovers include the first handover and the second handover.

3. The method according to claim 2, characterized in that, The reference identification information received by the second network device from the first network device is carried in a second message, which is used to request configuration information of the candidate cell.

4. The method according to claim 1, characterized in that, The reference identification information is a third or fourth identification; The third identifier is an identifier assigned by the first network device as the source network device for identifying the terminal device at the interface between the first network device and the third network device. The fourth identifier is an identifier assigned by the third network device as the target network device for identifying the terminal device at the interface between the first network device and the third network device.

5. The method according to claim 4, characterized in that, The reference identification information received by the second network device from the first network device is carried in a third message, which is used to notify the second network device that the terminal device has switched from the first network device to the second network device.

6. The method according to any one of claims 1 to 5, characterized in that, The method further includes: The second network device receives a second message from the first network device, the second message being used to request configuration information for candidate cells, the second message including a fifth identifier; The second network device sends a fourth message to the first network device, the fourth message including the configuration information of the first cell, the fifth identifier, and the sixth identifier; The first cell is managed by the second network device, and the configuration information of the first cell is used by the terminal device to access the first cell. The fifth identifier is an identifier assigned by the first network device as the source network device for identifying the terminal device on the interface between the first network device and the second network device. The sixth identifier is an identifier assigned by the second network device as the target network device for identifying the terminal device on the interface between the first network device and the second network device.

7. The method according to any one of claims 1 to 6, characterized in that, The method further includes: The second network device sends a fifth message to the third network device, the fifth message including the first identifier and the second identifier; The fifth message is used to notify the third network device that the terminal device has switched from the second network device to the third network device.

8. A communication method, characterized in that, The method includes: The third network device receives a first message from the second network device, the first message including reference identification information and a first identification; The third network device determines the context of the terminal device based on the reference identification information; The third network device associates the second identifier with the context of the terminal device; The third network device sends the first identifier and the second identifier to the second network device; The reference identification information is used to identify the terminal device. The first identifier is an identifier assigned by the second network device as the source network device for identifying the terminal device at the interface between the second network device and the third network device. The second identifier is an identifier assigned by the third network device as the target network device for identifying the terminal device at the interface between the second network device and the third network device. The second network device is the source network device for the second handover of the terminal device, and the third network device is the candidate network device for the second handover of the terminal device.

9. The method according to claim 8, characterized in that, The reference identification information is used to identify the terminal device within a preset area; or, The reference identification information is used by the first network device, the second network device, and the third network device to identify the terminal device during the multiple handovers of the terminal device. The first network device is the source network device for the first handover of the terminal device, and the multiple handovers include the first handover and the second handover.

10. The method according to claim 8, characterized in that, The reference identification information is a third or fourth identification; The third identifier is an identifier assigned by the first network device as the source network device for identifying the terminal device on the interface between the first network device and the third network device. The first network device is the source network device for the first handover of the terminal device. The fourth identifier is an identifier assigned by the third network device as the target network device for identifying the terminal device at the interface between the first network device and the third network device.

11. The method according to any one of claims 8 to 10, characterized in that, The method further includes: The third network device receives a sixth message from the first network device, the sixth message being used to request configuration information for candidate cells, the sixth message including a third identifier; The third network device sends a seventh message to the first network device, the seventh message including the configuration information of the second cell, the third identifier, and the fourth identifier; The second cell is managed by the third network device, and the configuration information of the second cell is used by the terminal device to access the second cell. The third identifier is an identifier assigned by the first network device as the source network device for identifying the terminal device at the interface between the first network device and the third network device. The fourth identifier is an identifier assigned by the third network device as the target network device for identifying the terminal device at the interface between the first network device and the third network device. The first network device is the source network device for the first handover of the terminal device.

12. The method according to claim 11, characterized in that, The context of the terminal device includes the configuration information of the second cell.

13. The method according to any one of claims 8 to 12, characterized in that, The method further includes: The third network device receives a fifth message from the second network device, the fifth message including the first identifier and the second identifier; The fifth message is used to notify the third network device that the terminal device has switched from the second network device to the third network device.

14. A communication method, characterized in that, The method includes: The second network device assigns a first identifier to the terminal device; The second network device receives a second identifier from the first network device, the second identifier being an identifier assigned to the terminal device by the third network device; Wherein, the first identifier is an identifier used by the second network device to communicate with network devices other than the second network device regarding the terminal device, and the network devices other than the second network device include the third network device. The second identifier is used by the third network device to communicate with other network devices (excluding the third network device) regarding the terminal device. The other network devices include the second network device. The first network device is the source network device for the first handover of the terminal device, the second network device is the source network device for the second handover of the terminal device, and the third network device is the candidate network device for the second handover of the terminal device.

15. The method according to claim 14, characterized in that, The method further includes: The second network device sends the first identifier to the first network device; The second network device receives a second identifier from the first network device, including: the second network device receiving the first identifier and the second identifier from the first network device.

16. The method according to claim 15, characterized in that, The method further includes: The second network device receives a first message from the first network device, the first message being used to request configuration information of candidate cells, the first message including a third identifier; The second network device sends the first identifier to the first network device, including: the second network device sends a second message to the first network device, the second message including the configuration information of the first cell, the third identifier and the first identifier; The first cell is managed by the second network device, and the configuration information of the first cell is used by the terminal device to access the first cell. The third identifier is an identifier used by the first network device to communicate with other network devices besides the first network device in relation to the terminal device, and the other network devices besides the first network device include the second network device.

17. The method according to claim 16, characterized in that, The first message also includes first indication information, which is used to instruct the second network device to identify the terminal device during multiple handovers of the terminal device, the multiple handovers including the first handover and the second handover.

18. The method according to any one of claims 14 to 17, characterized in that, The method further includes: The second network device sends a third message to the third network device, the third message including the first identifier and the second identifier; The third message is used to notify the third network device that the terminal device has switched from the second network device to the third network device.

19. A communication method, characterized in that, The method includes: The first network device receives a second identifier from the third network device; The first network device sends the second identifier to the second network device; The second identifier is used by the third network device to communicate with other network devices (excluding the third network device) in relation to a terminal device. The other network devices include the second network device. The first network device is the source network device for the first handover of the terminal device, the second network device is the source network device for the second handover of the terminal device, and the third network device is the target network device for the second handover of the terminal device.

20. The method according to claim 19, characterized in that, The method further includes: The first network device receives a first identifier from the second network device; Sending the second identifier from the first network device to the second network device includes: the first network device sending the first identifier and the second identifier to the second network device.

21. The method according to claim 20, characterized in that, The method further includes: The first network device sends a first message to the second network device, the first message being used to request configuration information of candidate cells, and the first message including a third identifier; The first network device receives a first identifier from the second network device, including: the first network device receives a second message from the second network device, the second message including configuration information of the first cell, the third identifier, and the first identifier; The first cell is managed by the second network device, and the configuration information of the first cell is used by the terminal device to access the first cell. The third identifier is an identifier used by the first network device to communicate with other network devices besides the first network device in relation to the terminal device, and the other network devices besides the first network device include the second network device.

22. The method according to any one of claims 18 to 21, characterized in that, The method further includes: The first network device sends a first message to the third network device, the first message being used to request configuration information of the candidate cell, and the first message including a third identifier; The first network device receives a second identifier from the third network device, including: the first network device receives a third message from the third network device, the third message including configuration information of the second cell, the third identifier, and the second identifier; The second cell is managed by the third network device, and the configuration information of the second cell is used by the terminal device to access the second cell. The third identifier is an identifier used by the first network device to communicate with other network devices besides the first network device in relation to the terminal device. The other network devices besides the first network device include the third network device.

23. The method according to claim 21 or 22, characterized in that, The first message also includes first indication information, which is used to indicate an identifier assigned to identify the terminal device during multiple switching processes of the terminal device, the multiple switching processes including the first switching and the second switching.

24. A communication device, characterized in that, The apparatus includes a module or unit for implementing the method of any one of claims 1 to 7, or includes a module or unit for implementing the method of any one of claims 8 to 13, or includes a module or unit for implementing the method of any one of claims 14 to 18, or includes a module or unit for implementing the method of any one of claims 19 to 23.

25. A communication device, characterized in that, Including the processor; The processor is configured to execute a computer program or instructions to cause the communication device to perform the method according to any one of claims 1 to 7, or the method according to any one of claims 8 to 13, or the method according to any one of claims 14 to 18, or the method according to any one of claims 19 to 23.

26. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the method of any one of claims 1 to 7, or the method of any one of claims 8 to 13, or the method of any one of claims 14 to 18, or the method of any one of claims 19 to 23.

27. A computer program product, the computer program product comprising: Computer program code, when the computer program code is executed, implements the method of any one of claims 1 to 7, or implements the method of any one of claims 8 to 13, or implements the method of any one of claims 14 to 18, or implements the method of any one of claims 19 to 23.

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