Communication method, and apparatus

Abstract

A communication method, and an apparatus. In the communication method, a first network device receives from a second network device configuration information of a first RB; the first network device sends to a third network device the configuration information of the first RB; the first network device receives configuration information of a first candidate cell sent by the third network device in response to the configuration information of the first RB; and the first network device sends to a terminal device the configuration information of the first candidate cell, wherein the configuration information of the first candidate cell comprises configuration information of a second RB and first instruction information, the second RB being different from the first RB, and the first instruction information being used for instructing the terminal device to configure the first RB for the first candidate cell; or, the configuration information of the first candidate cell comprises the configuration information of the second RB, the second RB being the same as the first RB. The method facilitates the terminal device to achieve data lossless handover when performing a subsequent handover or multiple handovers, thereby improving the service continuity.

Description

Communication method and device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on March 30, 2024, with application number 202410386944.0 and application name “Communication Method and Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0003] When the source cell and target cell of the handover are managed by different network devices, the network device providing services for the terminal device needs to be switched from the source network device to the target network device, where the source network device is the network device that manages the source cell, and the target network device is the network device that manages the target cell.

[0004] In addition, because quality of service flow (QoS Flow) is used to transmit data between network devices and the core network, and radio bearers (RBs) are used to transmit data between network devices and terminal devices, network devices need to map QoS Flows to RBs. When a terminal device switches from a source network device to a target network device, data may still exist between the source and terminal devices that was not successfully transmitted via the RBs mapped by the source network device, potentially resulting in data loss. For mobility management technologies that support "subsequent handovers" or "multiple handovers," how to achieve lossless data switching during subsequent handovers or multiple handovers requires further research. Summary of the Invention

[0005] The embodiments of the present application provide a communication method and apparatus, which are advantageous for a source network device to send data corresponding to a terminal device to a target network device during subsequent switching or multiple switching of a terminal device, thereby achieving lossless switching of data and ensuring business continuity.

[0006] In a first aspect, the present application provides a communication method. The method can be applied to a network device, a chip within the network device, or a logic module or software capable of implementing all or part of the network device's functions. The following description uses network device 1 as an example. The method comprises: network device 1 receiving configuration information for RB2 from network device 2, the RB2 configuration information including a mapping relationship between QoS flow 1 configured by network device 2 and RB2; network device 1 sending the RB2 configuration information to network device 3; network device 1 receiving configuration information for cell 3 sent by network device 3 in response to the RB2 configuration information; and network device 1 sending the configuration information for cell 3 to a terminal device. The configuration information for cell 3 includes configuration information for RB3 and indication information 4, where RB3 is different from RB2; indication information 4 is used to instruct the terminal device to configure RB2 for cell 3. Alternatively, the configuration information for cell 3 includes configuration information for RB3, where RB3 is the same as RB2; and the RB3 configuration information includes a mapping relationship between QoS flow 1 configured by network device 3 and RB3. Network device 1 is the network device to which the terminal device accesses, and cell 3 is a candidate cell for handover by the terminal device.

[0007] As can be seen, this method allows network device 3 to be configured with RB2 when RB3 and RB2 are different, and the terminal device to be configured with RB2 and RB3. During subsequent handovers or multiple handovers of the terminal device, before switching from network device 2 to network device 3, the terminal device transmits data with network device 2 via RB2. After switching from network device 2 to network device 3, since both the terminal device and network device 3 are configured with RB2, data can be transmitted between the terminal device and network device 3 via RB2. Data that was not successfully transmitted between the terminal device and network device 2 via RB2 is then transferred without loss, thus improving service continuity.

[0008] This method enables the UE to configure RB3 when RB3 is the same as RB2. During subsequent handovers or multiple handovers of the terminal device, before switching from network device 2 to network device 3, the terminal device transmits data with network device 2 via RB2. After switching from network device 2 to network device 3, because RB3 is configured for the terminal device and is the same as RB2, data between the terminal device and network device 3 can be transmitted via RB2. Data that was not successfully transmitted between the terminal device and network device 2 via RB2 can be transferred without loss of data, thus improving service continuity.

[0009] In an optional implementation, network device 1 sends configuration information of RB2 to network device 3, including: network device 1 sends configuration information of RB2 to network device 3, and when RB2 is the same as RB3, the configuration information of RB2 is used by network device 3 to determine that RB2 is the same as RB3.

[0010] In an optional implementation, network device 1 sends configuration information of RB2 to network device 3, including: network device 1 sends configuration information of RB2 to network device 3, and when RB2 is different from RB3, the configuration information of RB2 is used by network device 3 to configure RB2.

[0011] In an optional implementation, the configuration information of RB2 is used by the network device 3 to determine whether RB3 is the same as RB2. The configuration information of RB2 is also used by the network device 3 to configure RB2 when it is determined that RB3 is different from RB2.

[0012] In an optional implementation, the method further includes: network device 1 sending message 1 to network device 2, where message 1 is used to request configuration information of RBs mapped to QoS flow 1.

[0013] In an optional embodiment, the method further includes: network device 1 sending configuration information of RB1 to network device 3, where the configuration information of RB1 includes a mapping relationship between QoS flow 1 configured by network device 1 and RB1. Network device 1 receives configuration information of cell 3 sent by network device 3 in response to configuration information of RB2, including: network device 1 receives configuration information of cell 3 sent by network device 3 in response to configuration information of RB2 and configuration information of RB1; when RB1 and RB3 are different, the configuration information of cell 3 further includes indication information 5, where indication information 5 is used to instruct the terminal device to configure RB1 for cell 3.

[0014] As can be seen, this method allows network device 3 to be configured with RB1 when RB3 is different from RB1, and the terminal device to be configured with RB1 and RB3. During subsequent handovers or multiple handovers of the terminal device, before switching from network device 1 to network device 3, the terminal device transmits data with network device 1 via RB1. After switching from network device 1 to network device 3, since both the terminal device and network device 3 are configured with RB1, data between the terminal device and network device 3 can be transmitted via RB1. Data that was not successfully transmitted between the terminal device and network device 1 via RB1 is then transferred without loss, thus improving service continuity.

[0015] In an optional implementation, the method further includes: network device 1 sending indication information 1 to network device 3, where indication information 1 is used to instruct network device 3 to cooperate in data lossless switching, where data lossless switching includes providing configuration information of cell 3.

[0016] In an optional embodiment, the method further includes: network device 1 receiving, from network device 3, user plane tunnel address information allocated by network device 3 to RB2; and network device 1 sending, to network device 2, the user plane tunnel address information allocated by network device 3 to RB2, whereby network device 2 forwards data of RB2 to network device 3. This approach facilitates network device 2 forwarding data of RB2 to network device 3 based on the user plane tunnel address information allocated by network device 3 to RB2 when a terminal device switches from network device 2 to network device 3.

[0017] Among them, the RB2 data forwarded by network device 2 to network device 3 may include: the downlink data that network device 2 failed to send successfully to the terminal device through RB2, so that after the terminal device accesses network device 3, network device 3 can send to the terminal device through RB2: the downlink data that network device 2 failed to send successfully to the terminal device through RB2, thereby realizing lossless data switching.

[0018] And / or the data of RB2 forwarded by network device 2 to network device 3 may include: the uplink data from the terminal device received by network device 2 through RB2 and the uplink data not sent to the core network device. In this way, after the terminal device accesses network device 3, network device 3 can reorder the uplink data received from the terminal device through RB2: the uplink data that the terminal device failed to successfully send to network device 2 through RB2, and the uplink data forwarded by network device 2 to network device 3, and then send them to the core network device, so as to realize the uplink data of RB2 being sent to the core network device in sequence.

[0019] In an optional implementation, network device 1 is the source network device for the first switching of the terminal device, network device 2 is the source network device for the i-th switching of the terminal device, and network device 3 is the target network device for the i-th switching of the terminal device, where i is an integer greater than 1.

[0020] In a second aspect, the present application provides a communication method, which can be applied to a network device, a chip in a network device, or a logic module or software that can implement all or part of the network device functions. The following description takes network device 3 as an example. The method includes: network device 3 receives the configuration information of RB2 from network device 1, and the configuration information of RB2 includes the mapping relationship between QoS flow 1 configured by network device 2 and RB2; network device 3 responds to the configuration information of RB2 and sends the configuration information of cell 3 to network device 1. The configuration information of cell 3 includes the configuration information of RB3 and indication information 4, RB3 is different from RB2, and indication information 4 is used to instruct the terminal device to configure RB2 for cell 3. Alternatively, the configuration information of cell 3 includes the configuration information of RB3, and RB3 is the same as RB2; the configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by network device 3 and RB3. Network device 1 is the network device accessed by the terminal device, and cell 3 is a candidate cell for the terminal device to switch.

[0021] As can be seen, this method allows network device 3 to be configured with RB2 when RB3 and RB2 are different, and the terminal device to be configured with RB2 and RB3. During subsequent handovers or multiple handovers of the terminal device, before switching from network device 2 to network device 3, the terminal device transmits data with network device 2 via RB2. After switching from network device 2 to network device 3, since both the terminal device and network device 3 are configured with RB2, data can be transmitted between the terminal device and network device 3 via RB2. Data that was not successfully transmitted between the terminal device and network device 2 via RB2 is then transferred without loss, thus improving service continuity.

[0022] This method enables the UE to configure RB3 when RB3 is the same as RB2. During subsequent handovers or multiple handovers of the terminal device, before switching from network device 2 to network device 3, the terminal device transmits data with network device 2 via RB2. After switching from network device 2 to network device 3, because RB3 is configured for the terminal device and is the same as RB2, data between the terminal device and network device 3 can be transmitted via RB2. Data that was not successfully transmitted between the terminal device and network device 2 via RB2 can be transferred without loss of data, thus improving service continuity.

[0023] In an optional implementation, the method further includes: the network device 3 determines, based on the configuration information of RB2, that RB2 is the same as RB3.

[0024] In an optional implementation, the method further includes: when RB2 is different from RB3, the network device 3 configures RB2 based on the configuration information of RB2.

[0025] In an optional embodiment, the method further includes: network device 3 receiving configuration information of RB1 from network device 1, where the configuration information of RB1 includes a mapping relationship between QoS flow 1 configured by network device 1 and RB1. Network device 3 sends configuration information of cell 3 to network device 1 in response to the configuration information of RB2, including: network device 3 sends the configuration information of cell 3 to network device 1 in response to the configuration information of RB2 and the configuration information of RB1; when RB1 and RB3 are different, the configuration information of cell 3 further includes indication information 5, where indication information 5 is used to instruct the terminal device to configure RB1 for cell 3.

[0026] As can be seen, this method allows network device 3 to be configured with RB1 when RB3 is different from RB1, and the terminal device to be configured with RB1 and RB3. During subsequent handovers or multiple handovers of the terminal device, before switching from network device 1 to network device 3, the terminal device transmits data with network device 1 via RB1. After switching from network device 1 to network device 3, since both the terminal device and network device 3 are configured with RB1, data between the terminal device and network device 3 can be transmitted via RB1. Data that was not successfully transmitted between the terminal device and network device 1 via RB1 is then transferred without loss, thus improving service continuity.

[0027] In an optional embodiment, the method further includes: the network device 3 receives indication information 1 from the network device 1, the indication information 1 is used to instruct the network device 3 to cooperate in data lossless switching, and the data lossless switching includes providing configuration information of the cell 3.

[0028] In an optional embodiment, the method further includes: network device 3 sending, to network device 1, user plane tunnel address information allocated by network device 3 to RB2, where the user plane tunnel address information is used by network device 2 to forward data of RB2 to network device 3. This approach facilitates network device 2 to forward data of RB2 to network device 3 based on the user plane tunnel address information allocated by network device 3 to RB2 when a terminal device switches from network device 2 to network device 3.

[0029] Among them, the RB2 data forwarded by network device 2 to network device 3 may include: the downlink data that network device 2 failed to send successfully to the terminal device through RB2, so that after the terminal device accesses network device 3, network device 3 can send to the terminal device through RB2: the downlink data that network device 2 failed to send successfully to the terminal device through RB2, thereby realizing lossless data switching.

[0030] And / or the data of RB2 forwarded by network device 2 to network device 3 may include: the uplink data from the terminal device received by network device 2 through RB2 and the uplink data not sent to the core network device. In this way, after the terminal device accesses network device 3, network device 3 can reorder the uplink data received from the terminal device through RB2: the uplink data that the terminal device failed to successfully send to network device 2 through RB2, and the uplink data forwarded by network device 2 to network device 3, and then send them to the core network device, so as to realize the uplink data of RB2 being sent to the core network device in sequence.

[0031] In an optional embodiment, the method also includes: network device 3 receives the identifier of cell 2 from network device 2 or terminal device; network device 3 determines that the RB corresponding to cell 2 is RB2; after the terminal device switches from cell 2 to cell 3, network device 3 transmits RB2 data to the terminal device through RB2.

[0032] In an optional implementation, network device 1 is the source network device for the first switching of the terminal device, network device 2 is the source network device for the i-th switching of the terminal device, and network device 3 is the target network device for the i-th switching of the terminal device, where i is an integer greater than 1.

[0033] In a third aspect, the present application further provides a communication device. The communication device may be a network device, a chip within the network device, or a logic module or software capable of implementing all or part of the network device's functions. The communication device has the function of implementing some or all of the embodiments described in the first or second aspects above. The functions may be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more units or modules corresponding to the functions described above.

[0034] In one possible design, the communication device may include a processing unit configured to support the communication device in executing the corresponding functions in the above method. Optionally, the communication device may also include a communication unit configured to support communication between the communication device and other communication devices. Optionally, the communication device may also include a storage unit coupled to the processing unit and the communication unit to store program instructions and data necessary for the communication device. In addition, the processing unit may be used to control the communication unit to transmit and receive data / signaling.

[0035] In one embodiment, the communication unit is used to receive the configuration information of RB2 from the network device 2, and the configuration information of RB2 includes the mapping relationship between QoS flow 1 configured by the network device 2 and RB2. The communication unit is also used to send the configuration information of RB2 to the network device 3. The communication unit is also used to receive the configuration information of cell 3 sent by the network device 3 in response to the configuration information of RB2. The communication unit is also used to send the configuration information of cell 3 to the terminal device. The configuration information of cell 3 includes the configuration information of RB3 and indication information 4, RB3 is different from RB2, and indication information 4 is used to instruct the terminal device to configure RB2 for cell 3; or, the configuration information of cell 3 includes the configuration information of RB3, and RB3 is the same as RB1; the configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by the network device 3 and RB3. The network device 1 is the network device to which the terminal device accesses, and the cell 3 is a candidate cell for the terminal device to switch.

[0036] In addition, in this aspect, other optional implementations of the communication device can refer to the relevant content of the first aspect above and will not be described in detail here.

[0037] In another embodiment, the communication unit is used to receive the configuration information of RB2 from the network device 1, and the configuration information of RB2 includes the mapping relationship between QoS flow 1 configured by the network device 2 and RB2. The communication unit is also used to respond to the configuration information of RB2 and send the configuration information of cell 3 to the network device 1; the configuration information of cell 3 includes the configuration information of RB3 and indication information 4, RB3 is different from RB2, and indication information 4 is used to instruct the terminal device to configure RB2 for cell 3; or, the configuration information of cell 3 includes the configuration information of RB3, and RB3 is the same as RB2; the configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by the network device 3 and RB3. Among them, the network device 1 is the network device accessed by the terminal device, and the cell 3 is a candidate cell for the terminal device to switch.

[0038] In addition, in this aspect, other optional implementations of the communication device can refer to the relevant content of the second aspect above and will not be described in detail here.

[0039] As an example, the communication unit may be a transceiver or a communication interface, the storage unit may be a memory, and the processing unit may be a processor. The processor is coupled to the memory, the memory is used to store programs or instructions to the processor, and the processor is configured to cause the communication device to perform the method described in the first aspect when the programs or instructions are executed by the processor. The transceiver or communication interface may be configured to transmit and receive signals and / or data.

[0040] In one embodiment, the transceiver is used to receive configuration information of RB2 from network device 2, and the configuration information of RB2 includes the mapping relationship between QoS flow 1 configured by network device 2 and RB2. The transceiver is also used to send the configuration information of RB2 to network device 3. The transceiver is also used to receive the configuration information of cell 3 sent by network device 3 in response to the configuration information of RB2. The transceiver is also used to send the configuration information of cell 3 to the terminal device. The configuration information of cell 3 includes the configuration information of RB3 and indication information 4, RB3 is different from RB2, and indication information 4 is used to instruct the terminal device to configure RB2 for cell 3; or, the configuration information of cell 3 includes the configuration information of RB3, and RB3 is the same as RB1; the configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by network device 3 and RB3. Network device 1 is the network device accessed by the terminal device, and cell 3 is a candidate cell for switching by the terminal device.

[0041] In addition, in this aspect, other optional implementations of the communication device can refer to the relevant content of the first aspect above and will not be described in detail here.

[0042] In another embodiment, the transceiver is used to receive the configuration information of RB2 from the network device 1, and the configuration information of RB2 includes the mapping relationship between QoS flow 1 configured by the network device 2 and RB2. The transceiver is also used to respond to the configuration information of RB2 and send the configuration information of cell 3 to the network device 1; the configuration information of cell 3 includes the configuration information of RB3 and indication information 4, RB3 is different from RB2, and indication information 4 is used to instruct the terminal device to configure RB2 for cell 3; or, the configuration information of cell 3 includes the configuration information of RB3, and RB3 is the same as RB2; the configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by the network device 3 and RB3. Among them, the network device 1 is the network device accessed by the terminal device, and the cell 3 is a candidate cell for the terminal device to switch.

[0043] In addition, in this aspect, other optional implementations of the communication device can refer to the relevant content of the second aspect above and will not be described in detail here.

[0044] In another embodiment, the communication device is a chip or a chip system. The processing unit may also be embodied as a processing circuit or a logic circuit; and the transceiver unit may be an input / output interface, an interface circuit, an output circuit, an input circuit, a pin, or a related circuit on the chip or chip system.

[0045] During implementation, the processor can be used to perform, for example, but not limited to, baseband-related processing, and the transceiver or communication interface can be used to perform, for example, but not limited to, radio frequency transceiver. The above-mentioned devices can be provided on separate chips, or at least partially or entirely on the same chip. For example, the processor can be further divided into an analog baseband processor and a digital baseband processor. The analog baseband processor can be integrated with the transceiver (or communication interface) on the same chip, while the digital baseband processor can be provided 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 (such as, but not limited to, a graphics processor, a multimedia processor, etc.) on the same chip. Such a chip can be called a system on a chip (SoC). Whether each device is provided independently on different chips or integrated on one or more chips often depends on the needs of the product design. The embodiments of the present application do not limit the implementation form of the above-mentioned devices.

[0046] In a fourth aspect, the present application also provides a processor for executing the various methods described above. In the process of executing these methods, the process of sending the above information and receiving the above information in the above method can be understood as the process of outputting the above information by the processor, and the process of inputting the above information by the processor. When outputting the above information, the processor outputs the above information to the transceiver so that it is transmitted by the transceiver (or communication interface). After being output by the processor, the above information may also need to undergo other processing before reaching the transceiver (or communication interface). Similarly, when the processor receives the input information, the transceiver (or communication interface) receives the above information and inputs it into the processor. Furthermore, after the transceiver (or communication interface) receives the above information, the above information may need to undergo other processing before being input into the processor.

[0047] For the sending and receiving operations involved in the processor, unless otherwise specified, or unless they conflict with their actual functions or internal logic in the relevant descriptions, they can be more generally understood as processor output, reception, input and other operations, rather than sending and receiving operations directly performed by the RF circuit and antenna.

[0048] During implementation, the processor may be a processor specifically configured to execute these methods, or may be a processor that executes computer instructions in a memory to execute these methods, such as a general-purpose processor. The memory may be a non-transitory memory, such as a read-only memory (ROM), which may be integrated with the processor on the same chip or disposed on separate chips. The embodiments of the present application do not limit the type of memory or the configuration of the memory and the processor.

[0049] In a fifth aspect, the present application further provides a communication system, comprising an apparatus for executing the method described in the first aspect and an apparatus for executing the method described in the second aspect. In another possible design, the system may further include other devices that interact with the apparatus for executing the method described in the first aspect, and / or other devices that interact with the apparatus for executing the method described in the second aspect.

[0050] In a sixth aspect, the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is run, the method described in the first or second aspect above is executed.

[0051] In a seventh aspect, the present application further provides a computer program product comprising instructions, the computer program product comprising: computer program code, which, when the computer program code is run, enables the method described in the first aspect or the second aspect above to be executed.

[0052] In an eighth aspect, the present application provides a chip system, which includes a processor and an interface, wherein the interface is used to obtain a program or instruction, and the processor is used to call the program or instruction to implement the functions involved in the first aspect or the second aspect. In one possible design, the chip system also includes a memory, which is used to store program instructions and data necessary for the terminal. The chip system can be composed of a chip, or it can include a chip and other discrete devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIG1 is a schematic diagram of a system architecture provided in an embodiment of the present application;

[0054] FIG2 is a schematic diagram of a CU-DU separation architecture provided in an embodiment of the present application;

[0055] FIG3 is a schematic diagram of a QoS flow mapping to RBs provided in an embodiment of the present application;

[0056] FIG4 is a schematic diagram of a switching process provided in an embodiment of the present application;

[0057] FIG5 is a schematic diagram of another switching process provided in an embodiment of the present application;

[0058] FIG6 is a schematic diagram of another QoS flow mapping to RBs provided in an embodiment of the present application;

[0059] FIG7 is a flow chart of a communication method provided in an embodiment of the present application;

[0060] FIG8 is a flow chart of another communication method provided in an embodiment of the present application;

[0061] FIG9 is a flow chart of another communication method provided in an embodiment of the present application;

[0062] FIG10 is a flow chart of another communication method provided in an embodiment of the present application;

[0063] FIG11 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0064] FIG12 is a schematic structural diagram of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0065] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0066] The technical solutions of the embodiments of the present application can be applied to various communication systems. For example, the global mobile communication system, the long term evolution (LTE) system, the universal mobile communication system, the fourth generation (4G) mobile communication system, the fourth point five generation (4.5G) mobile communication system, the fifth generation (5G) mobile communication system, and with the continuous development of communication technology, the technical solutions of the embodiments of the present application can also be used for subsequent evolved communication systems, such as future communication systems, and so on. The technical solutions of the embodiments of the present application can also be applied to the universal mobile telecommunications system (UMTS), the code division multiple access (CDMA) system, the wireless local area network (WLAN), etc.

[0067] An embodiment of the present application provides a communication system, which includes a network device and a terminal device. The terminal device is located within the coverage of one or more cells (carriers) managed by the network device, and the cell providing services to the terminal device may be one or more. In the case where there are multiple cells providing services to the terminal device, the terminal device may operate in accordance with carrier aggregation (CA) or dual connectivity (DC) or coordinated multi-point transmission mode, and at least one of the multiple cells may provide at least two parameter sets (numerology) for the terminal device to simultaneously provide wireless resources for the terminal device. For example, as shown in Figure 1, the terminal device is simultaneously located within the coverage of the cell managed by network device A, the cell managed by network device B, and the cell managed by network device C. In Figure 1, network device A may be, for example, a macro base station (macro evolutional Node B, macro eNB or macro e-NodeB), and network device B and network device C may be, for example, micro base stations (small eNB or small e-NodeB).

[0068] In the embodiments of the present application, the terminal device may also be referred to as user equipment (UE), terminal, access terminal, subscriber unit, subscriber station, mobile station, mobile station (MS), mobile terminal (MT), remote station, remote terminal, mobile device, user terminal, user agent, or user device, and may be applied to 4G, 5G, and even future communication systems. The terminal device may provide voice and / or data connectivity to the user. The terminal device can be a joint device that transmits and receives digital signals on an ordinary telephone line, or a handheld device with wireless connection function, a vehicle-mounted device, a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a mobile phone, a tablet computer (pad), a laptop computer, a handheld computer, a computer with wireless transceiver function, a mobile internet device (MID), a wearable device, a head mounted display (HMD), a virtual reality (VR) device (such as VR glasses), an augmented reality (AR) device (such as AR glasses), a mixed reality (MR) device, a wireless terminal in industrial control, a processing device connected to a wireless modem, a tactile terminal device, a vehicle-mounted device, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in smart grid, a transportation security device, a wireless terminal in medical field ... safety), wireless terminals in smart cities, wireless terminals in smart homes, road side units (RSUs) of the aforementioned wireless terminal types, and so on.

[0069] A network device may be an access network device, which is a radio access network (RAN) node (or device) that connects a terminal device to a wireless network. Network devices include, but are 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 (Wifi) 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 can provide wireless communication functions. It may also be referred to as a base station device, such as an evolved Node B (eNB or e-NodeB) in an LTE system, a Node B (NB), a base station (gNodeB or gNB) in a 5G system, or a base station in a future communication system. A base station can consist of a base station unit (BBU) and a remote radio unit (RRU). The BBU and RRU can be placed in different locations. For example, the RRU can be remotely located in a high-traffic area, while the BBU can be placed in a central equipment room. The BBU and RRU can also be placed in the same equipment room. The BBU and RRU can also be separate 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, and so on.

[0070] Optionally, in some deployments of network devices, the network device may include a centralized unit (CU) and / or a distributed unit (DU). In the case where the network device includes a CU and a DU, the network device adopts a CU-DU separation architecture, which can also be called a distributed deployment architecture; in this case, the protocol layer of the eNB in ​​the LTE system is split, and the functions of some protocol layers are centrally controlled by the CU, and the functions of the remaining part or all of the protocol layers are distributed in the DU and centrally controlled by the DU. In some further deployments of network devices, the CU can also be divided into a CU-control plane (CP) and a CU-user plane (UP), etc. In some further deployments of network devices, 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.

[0071] For example, in conjunction with Figure 2, the network device can logically include a CU and one or more DUs. Each DU can be connected to the CU through the F1 interface, and the information interaction between different DUs can be completed based on the forwarding of the CU. The CU and the DU can be physically set together or physically separated, and there is no limitation on this. Among them, 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 illustrates an example of a network device including 1 CU and 2 DUs.

[0072] The network architecture described in the embodiments of this application is intended to more clearly illustrate the technical solutions of the embodiments of this application and does not constitute a limitation on the technical solutions provided by the embodiments of this application. With the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0073] The following describes the relevant concepts involved in the embodiments of the present application.

[0074] 1. Source network device and target network device, source cell and target cell, candidate cell and candidate network device

[0075] For a handover of a terminal device, the network device that provides services to the terminal device before the handover is the source network device, the cell accessed by the terminal device before the handover is the source cell, and the source cell is managed by the source network device; the network device that provides services to the terminal device after the handover is the target network device, the cell accessed by the terminal device after the handover is the target cell, and the target cell is managed by the target network device. In the embodiment of the present application, the cell accessed by the terminal device may also be referred to as the serving cell of the terminal device, the network device accessed by the terminal device may also be referred to as the serving network device of the terminal device, and the serving network device provides services to the terminal device.

[0076] For example, the cell accessed by the terminal device is cell 1 managed by network device 1. After the terminal device switches from cell 1 to cell 2, the terminal device accesses cell 2, and network device 2 used to manage cell 2 provides services to the terminal device. It can be seen that in this switching, 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.

[0077] A candidate cell is a cell to which a terminal device may switch from a serving cell. A candidate cell can be a neighboring cell of the terminal device's serving cell. There can be one or more candidate cells, with one of the one or more candidate cells serving as the target cell for the terminal device to switch from the serving cell. For example, if the terminal device's serving cell is cell 1, the candidate cells for the terminal device to switch from cell 1 include cell 2 and cell 3, with cell 2 serving as the target cell for the terminal device to switch from cell 1.

[0078] A candidate network device is a network device that manages a candidate cell. For example, the serving network device of a terminal device is network device 1, and the serving cell of the terminal device is cell 1 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 switch from cell 1. Therefore, network device 2 and network device 3 are both candidate network devices for the terminal device to switch from network device 1. If cell 2 is the target cell for the terminal device to switch from cell 1, then network device 2 is the target network device for the terminal device to switch from network device 1.

[0079] 2. Quality of service flow (QoS Flow)

[0080] QoS flows are used between network devices and core network devices to manage and transmit data for different services. Specifically, a QoS flow includes data flows with the same QoS requirements, such as the same transmission latency and packet loss rate requirements. Based on the QoS requirements of the QoS flow, network devices can use corresponding network transmission resources and transmission policies for the QoS flow. For example, if a QoS flow requires extremely low transmission latency, the network device can use more bandwidth resources to prioritize the transmission of data for that QoS flow.

[0081] For the same service, the same QoS flow can be used to transmit data between different network devices and core network devices. The same QoS flow refers to a QoS flow with the same QoS flow identifier (QoS Flow identifier, QFI). For example, for the telephone service of the terminal device, the QoS flow used by network device 1 when providing services to the terminal device, the QoS flow used by network device 2 when providing services to the terminal device, and the QoS flow used by network device 3 when providing services to the terminal device can be the same QoS flow. The same QoS flow means that the identifier of the QoS flow used by network device 1 when providing services to the terminal device, the identifier of the QoS flow used by network device 2 when providing services to the terminal device, and the identifier of the QoS flow used by network device 3 when providing services to the terminal device are the same identifier.

[0082] 3. Radio bearer (RB)

[0083] Network devices and terminal devices use RBs for differentiated management and data transmission of different services. Terminal devices and network devices can transmit data based on the same configured RBs. For example, if a terminal device is configured with RB1 and network device 1 is configured with RB1, when the terminal device is connected to network device 1, data can be transmitted between the two devices using RB1.

[0084] The RBs used for data transmission between different network devices and terminal devices can be the same or different. Identical RBs are RBs with the same identifier, and different RBs are RBs with different identifiers. For example, taking network device 1 configured with RB1 and network device 2 configured with RB2 as an example, when the terminal device accesses network device 1, it transmits data with network device 1 through the configured RB1. When the terminal device switches from network device 1 to network device 2, if RB2 is the same as RB1, the terminal device can reuse the previously configured RB1 for data transmission with network device 2 without having to reconfigure RB1. If RB2 is different from RB1, the terminal device needs to configure RB2 and transmit data with network device 2 through RB2. The terminal device can determine whether RB2 is the same as RB1 based on the identifier of RB2 and the identifier of RB1. If the identifier of RB2 is the same as the identifier of RB1, the terminal device determines that RB2 and RB1 are the same. If the identifier of RB2 is different from the identifier of RB1, the terminal device determines that RB2 and RB1 are different.

[0085] When a network device manages multiple cells, the RBs used by a terminal device to transmit data with the network device when accessing different cells can be the same or different. For example, the network device manages cell 1a and cell 1b. When a terminal device accesses cell 1a, data is transmitted between the terminal device and the network device via RB1. When the terminal device accesses cell 1b, data is transmitted between the terminal device and the network device via RB2. RB1 and RB2 can be the same RB or different RBs.

[0086] 4. QoS Flow to RB mapping

[0087] Because QoS flows are used to transmit data between network devices and core network devices, and RBs are used to transmit data between network devices and terminal devices, network devices need to map QoS flows to RBs. Specifically, the SDAP layer in the network device maps QoS flows to RBs. For example, referring to Figure 3, QoS flows A, B, and C exist between the core network device and the network device. The SDAP layer in the network device maps QoS flows A and B to RB1 and QoS flow C to RB2. In the network device, different PDCP layers and different RLC layers can be used to process RB1 and RB2, respectively. Alternatively, the same MAC layer and the same PHY can be used to process RB1 and RB2.

[0088] The network device may map the same RB to the same QoS flow in different cells, or it may map different RBs. For example, a network device manages cell 1a and cell 1b. For cell 1a, the network device maps QoS flow A to RB1, and transmits data to the terminal device via RB1 when the terminal device accesses cell 1a. For cell 1b, the network device maps QoS flow A to RB2, and transmits data to the terminal device via RB2 when the terminal device accesses cell 1b. RB1 and RB2 can be the same RB or different RBs.

[0089] Different network devices may map the same RB to the same QoS flow, or they may map to different RBs. For example, network device 1 maps QoS flow A to RB1, and network device 2 maps QoS flow A to RB2. RB1 and RB2 may be the same RB or different RBs.

[0090] In addition, for each cell managed by the network device, the cell configuration information may include configuration information related to RBs. The configuration information related to RBs includes one or more of the following: configuration information for each of one or more RBs, or the number of RBs. The one or more RBs are RBs that the network device maps to each of one or more QoS flows for the cell, and the configuration information for each RB is used to configure the RB. The number of RBs is the number of RBs that the network device maps to one or more QoS flows for the cell.

[0091] For example, a network device in cell 1 can transmit telephone service data and video service data with a terminal device. Telephone service data is transmitted between the network device and the core network device via QoS flow A, and video service data is transmitted via QoS flow B. For cell 1, the network device maps QoS flow A to RB1 and QoS flow B to RB2. The configuration information for cell 1 may include one or more of the following: RB1 configuration information, RB2 configuration information, or the number of RBs, where the number of RBs is 2.

[0092] In one optional manner, the RB configuration information includes one or more of the following: a mapping relationship between a QoS flow and an RB (or also referred to as a QoS flow to RB mapping rule), an RB identifier, or PDCP configuration information corresponding to the RB. Optionally, the PDCP configuration information includes one or more of the following: a PDCP sequence number (SN) length, or a PDCP discard timer duration.

[0093] 5. User plane tunnel address information

[0094] The user plane tunnel address information may be, for example, uplink user plane tunnel address information and / or downlink user plane tunnel address. The uplink user plane tunnel address information may be, for example, uplink user plane transport network layer information (UP TNL information), and the downlink user plane tunnel address information may be, for example, downlink UP TNL information. The uplink UP TNL information may, for example, include one or more of the following: an uplink transport layer address, or an uplink general packet radio system (GPRS) tunneling protocol-tunnel endpoint identifier (GTP-TEID), and the downlink UP TNL information may, for example, include one or more of the following: a downlink transport layer address, or a downlink GTP-TEID, wherein the transport layer address is, for example, an Internet Protocol (IP) address. In addition, the user plane tunnel address information may also be referred to as user plane data tunnel address information.

[0095] In one embodiment, user plane tunnel address information is allocated at the RB level. For example, the network device may allocate user plane tunnel address information for each RB. If the network device maps the same RB to different cells, the user plane tunnel address information allocated by the network device to the same RB mapped to different cells may be the same or different.

[0096] For example, a network device manages cell 1a and cell 1b. For cell 1a, the network device maps QoS flow A to RB1 and QoS flow B to RB2. For cell 1b, the network device maps QoS flow A to RB1 and QoS flow B to RB2.

[0097] The network device allocates user plane tunnel address information A to RB1 corresponding to cell 1a, allocates user plane tunnel address information B to RB2 corresponding to cell 1a, allocates user plane tunnel address information C to RB1 corresponding to cell 1b, and allocates user plane tunnel address information D to RB2 corresponding to cell 1b. User plane tunnel address information A, user plane tunnel address information B, user plane tunnel address information C, and user plane tunnel address information D are different.

[0098] Alternatively, RB1 corresponding to cell 1a and RB1 corresponding to cell 1b share user plane tunnel address information A, and RB2 corresponding to cell 1a and RB2 corresponding to cell 1b share user plane tunnel address information B. User plane tunnel address information A and user plane tunnel address information B are different.

[0099] In addition, user plane tunnel address information is used for data forwarding. The user plane tunnel address information corresponding to an RB is used to forward data for that RB. For example, network device 1 and a terminal device transmit data via RB1. When the terminal device switches from network device 1 to network device 2, network device 1 sends RB1's data to network device 2 based on the user plane tunnel address information allocated by network device 2 for RB1.

[0100] 6. Re-mapping of QoS flows to RBs in handover scenarios

[0101] When a terminal device switches from a source network device to a target network device, the source and target network devices may map different RBs to the same QoS flow. This change in RB usage is also known as QoS flow-to-RB remapping.

[0102] Exemplarily, in conjunction with Figure 4, take the example that the source network device maps QoS flow 1 to RB1, the target network device maps QoS flow 1 to RB2, and RB1 is different from RB2. When the terminal device accesses the source network device, it transmits data with the source network device through RB1. The source network device sends a handover request message to the target network device. The target network device sends a handover request acknowledgement message to the source network device, and the handover request acknowledgement message includes the configuration information of RB2. The source network device sends a handover command to the terminal device, and the handover command is used to instruct the terminal device to switch to the target network device, and the handover command includes the configuration information of RB2. After receiving the handover command, the terminal device switches to the target network device. After accessing the target network device, the terminal device transmits data between the configured RB2 and the target network device.

[0103] The process shown in Figure 4 may result in data loss caused by switching. For example, during downlink transmission between the terminal device and the source network device, the source network device sends 100 data packets to the terminal device via RB1. The 100 data packets are numbered 1 to 100. When the terminal device switches to the target network device, the data packets numbered 1 to 90 have been successfully received by the terminal device, while the data packets numbered 91 to 100 have not yet been successfully received by the terminal device. Because RB2 is different from RB1, the switching of the terminal device from the source network device to the target network device will cause the QoS flow to be remapped to RB, and RB2 will be used to transmit data between the target network device and the terminal device. It can be seen that because the target network device is not aware that the data packets numbered 91 to 100 previously transmitted by the source network device using RB1 were not successfully transmitted to the terminal device, and the target network device cannot retransmit the data packets numbered 91 to 100, data loss, i.e., packet loss, will occur, affecting service continuity.

[0104] For another example, during uplink transmission between a terminal device and a source network device, the terminal device sends 100 data packets to the source network device via RB1. The 100 data packets are numbered 101 to 200. When the terminal device switches to the target network device, the data packets numbered 101 to 190 have been successfully received by the source network device, while the data packets numbered 191 to 200 have not yet been successfully received by the source network device. Because RB2 is different from RB1, the switching of the terminal device from the source network device to the target network device will cause the QoS flow to be remapped to RB, and RB2 will be used to transmit data between the target network device and the terminal device. Furthermore, because the terminal device releases the configuration information of RB1 when switching from the source network device to the target network device, the terminal device cannot retransmit the data packets numbered 191 to 200 in RB1 to the target network device. The target network device cannot receive the data packets numbered 191 to 200 in RB1, which will result in data loss, i.e., packet loss, affecting service continuity.

[0105] For example, in conjunction with Figure 5, a data lossless switching can be performed. The difference between the process described in Figure 5 and the process described in Figure 4 is that:

[0106] (1) The handover request message sent by the source network device to the target network device includes the configuration information of RB1, that is, the configuration information of the RB used for data transmission between the terminal device and the source network device.

[0107] (2) The handover request confirmation message sent by the target network device to the source network device also includes the configuration information of RB1.

[0108] (3) The handover command sent by the source network device to the terminal device includes not only the configuration information of RB2 but also the configuration information of RB1.

[0109] (4) After receiving the switching request confirmation message, network device 1 not only sends a switching command to the terminal device, but also forwards data to network device 2.

[0110] Among them, the forwarded data may include: downlink data that the source network device sent to the terminal device through RB1 but was not successfully received by the terminal device. Specifically, the target network device can configure RB1 based on the configuration information of RB1 in the switching request message. After the terminal device accesses the target network device, the target network device sends to the terminal device through RB1: downlink data that the source network device sent to the terminal device through RB1 but was not successfully received by the terminal device. Accordingly, the terminal device can retain the configured RB1 based on the configuration information of RB1 in the switching command, and after accessing the target network device, receive the downlink data from the target network device through RB1, which is conducive to lossless switching of downlink data.

[0111] And / or, the forwarded data may include: uplink data from the terminal device that is successfully received by the source network device through RB1, and the uplink data is not transmitted to the core network device. Specifically, the terminal device can retain the configured RB1 based on the configuration information of RB1 in the switching command, so that after the terminal device accesses the target network device, it can send to the target network device through RB1: uplink data that the terminal device sent to the source network device through RB1 but was not successfully received by the source network device. Accordingly, the target network device configures RB1 based on the configuration information of RB1 in the switching request message, and receives uplink data from the terminal device through RB1 after the terminal device accesses the target network device. In addition, the target network device reorders the uplink data received through RB1 with the uplink data forwarded by the source network device to the target network device, and then sends them to the core network device, which is conducive to achieving lossless switching of uplink data and sending RB1 data to the core network device in sequence.

[0112] As can be seen, the process described in Figure 5 can achieve lossless data switching in a single handover scenario when QoS flow to RB remapping occurs during the handover process. For each handover performed by the terminal device, the process described in Figure 5 needs to be executed again in its entirety. However, for technologies that support subsequent handovers, how to achieve lossless data switching when QoS flow to RB remapping occurs during subsequent handovers requires further research.

[0113] Specifically, in the technology that supports subsequent switching, before the terminal device performs the first switching, the service network device of the terminal device will send a switching request message to each candidate network device to obtain the pre-configuration information of each candidate network device, and send the pre-configuration information of each candidate network device to the terminal device. For any switching of the terminal device, the source network device will no longer send a switching request message to the target network device. Therefore, the target network device cannot determine the source network device and the RB mapped by the source network device through the switching request message, and thus the target network device cannot determine whether the QoS flow is remapped to the RB in this switching and whether the data lossless guarantee mechanism needs to be executed, which may cause data loss during the switching process.

[0114] For example, in conjunction with Figure 6, take the example where network device 1 maps QoS flow 1 to RB1 for cell 1, network device 2 maps QoS flow 1 to RB2 for cell 2, and network device 3 maps QoS flow 1 to RB2 for cell 3. In the technology that supports subsequent switching, the terminal device has obtained the pre-configuration information of network device 1, network device 2, and network device 3 before the first switching, and the terminal device performs subsequent switching between network device 1, network device 2, and network device 3. For the scenario where the target network device for a certain switching of the terminal device is network device 3, if the source network device of this switching is network device 1, remapping of QoS flow to RB occurs in this switching; if the source network device of this switching is network device 2, remapping of QoS flow to RB does not occur in this switching. Since the source network device of this switch will no longer send a switch request message to network device 3, network device 3 cannot determine the source network device of this switch and the RB mapped by the source network device. As a result, network device 3 cannot determine whether this switch has performed a remapping of the QoS flow to the RB and whether a data lossless guarantee mechanism needs to be executed, which may cause data loss during the switching process, affect business continuity, and reduce user experience.

[0115] The following describes an embodiment of the present application in detail with reference to the accompanying drawings. While the embodiments of the present application use network devices and terminal devices as examples to illustrate the corresponding methods, the present application does not limit the execution of the methods. For example, the device in the method may also be a chip, chip system, or processor that supports the device in implementing the corresponding method, or a logic module or software that implements all or part of the functions of the device.

[0116] For ease of explanation, the following description is made using network device 1, network device 2, and network device 3 as examples, in conjunction with Figures 7 to 10. Network device 1 is the serving network device of the terminal device, and network device 2 and network device 3 are candidate network devices for the terminal device to switch from network device 1. The serving cell of the terminal device is cell 1, which is managed by network device 1. The candidate cells for the terminal device to switch from cell 1 include cell 2 and cell 3, where cell 2 is managed by network device 2 and cell 3 is managed by network device 3. Furthermore, network device 1 maps QoS flow 1 to RB1 for cell 1, network device 2 maps QoS flow 1 to RB2 for cell 2, and network device 3 maps QoS flow 1 to RB3 for cell 3.

[0117] Optionally, in a scenario where the mobility technology is triggered by a network device (i.e., the network device triggers the terminal device to switch), network device 1 is the network device that initially triggers the mobility technology, network device 1 may also be referred to as the initial source network device, and cell 1 may also be referred to as the initial source cell. The initial source network device may also be regarded as the network device that first provides the candidate cell configuration to the terminal device. In addition, the initial source network device may also be understood as: the source network device where the terminal device performs the first switch; the initial source cell may also be understood as: the source cell where the terminal device performs the first switch. Exemplarily, the embodiment of the present application may be applicable to layer 1 (layer 1, L1) / layer 2 (layer 2, L1) triggered mobility (L1 / L2 triggered mobility, LTM) technology that supports subsequent switching, and network device 1 is the network device that initially initiates LTM. Wherein, L1 refers to the physical layer, and L2 refers to the MAC layer or RLC layer or PDCP or SDAP layer. In addition, in addition to the LTM technology, the embodiment of the present application may also be applicable to other mobility technologies that are triggered by a network device and support subsequent switching, without limitation.

[0118] Optionally, in a scenario where the mobility technology is triggered by a terminal device (i.e., handover is triggered by the terminal device), network device 1 is the source network device accessed when the terminal device initially triggers the mobility technology. Network device 1 may also be referred to as the initial source network device, and cell 1 may also be referred to as the initial source cell. The initial source network device may also be regarded as the network device that initially provides the candidate cell configuration to the terminal device. In addition, the initial source network device may also be understood as: the source network device on which the terminal device performs the first handover; the initial source cell may also be understood as: the source cell on which the terminal device performs the first handover. Exemplarily, the embodiment of the present application may be applicable to an LTM technology that supports subsequent handovers, and network device 1 is the source network device accessed when the terminal device initially initiates LTM. In addition, in addition to the LTM technology, the embodiment of the present application may also be applicable to other mobility technologies triggered by a terminal device and supporting subsequent handovers, such as conditional L1 / L2 triggered mobility (C-LTM) technology and conditional handover technology that supports continuous handovers, without limitation thereto.

[0119] In addition, optionally, after the terminal device switches from network device 1 to another network device, network device 1 may also be a candidate network device for the terminal device to switch from the other network device, and the terminal device may also access network device 1 during a subsequent switching process. Correspondingly, after the terminal device switches from cell 1 to another cell, cell 1 may also be a candidate cell for the terminal device to switch from the other network device, and the terminal device may also access cell 1 during a subsequent switching process.

[0120] Please refer to FIG. 7 , which is a flow chart of a communication method provided in an embodiment of the present application. The communication method includes the following steps.

[0121] S101. Network device 1 sends message 1 to network device 2 and network device 3. Message 1 is used to request configuration information of RBs mapped to QoS flow 1. Accordingly, network device 2 receives message 1 from network device 1, and network device 3 receives message 1 from network device 1.

[0122] Optionally, message 1 includes an identifier of QoS flow 1. In this way, network device 2 and network device 3 can determine QoS flow 1 based on the identifier of QoS flow 1 in message 1, map QoS flow 1 to RB, and provide configuration information for the RB mapped to QoS flow 1.

[0123] In an optional embodiment, message 1 is specifically used to request configuration information of RBs mapped to QoS flow 1 by the candidate cell. Exemplarily, message 1 sent by network device 1 to network device 2 is used to request network device 2 to provide configuration information of RBs mapped to QoS flow 1 by cell 2. Furthermore, illustratively, message 1 sent by network device 1 to network device 3 is used to request network device 3 to provide configuration information of RBs mapped to QoS flow 1 by cell 3.

[0124] In an optional embodiment, message 1 includes the configuration information of RB1. It is understandable that when the network device 1 sends message 1, the service cell of the terminal device is cell 1, and message 1 may also include the configuration information of the RB mapped by the network device 1 to the service cell of the terminal device (i.e., cell 1) for QoS flow 1. Optionally, the configuration information of RB1 includes at least one of the following: the mapping relationship between QoS flow 1 configured by the network device 1 and RB1, the identifier of RB1, or the PDCP configuration corresponding to RB1. Optionally, the PDCP configuration corresponding to RB1 includes at least one of the following: the PDCP SN length corresponding to RB1, or the duration of the PDCP discard timer, etc.

[0125] In an optional embodiment, message 1 includes indication information 1, and indication information 1 is used to instruct cooperation in data lossless switching. Exemplarily, the indication information 1 sent by network device 1 to network device 2 is used to instruct network device 2 to cooperate in data lossless switching, and data lossless switching may include: network device 2 determines whether RB2 is the same as RB1, determines the configuration information of cell 2 based on the judgment result, and provides the configuration information of cell 2. Also exemplarily, the indication information 1 sent by network device 1 to network device 3 is used to instruct network device 3 to cooperate in data lossless switching, and data lossless switching may include: network device 3 determines whether RB3 is the same as RB1, determines the configuration information of cell 3 based on the judgment result, and provides the configuration information of cell 3.

[0126] S102: Network device 2 sends message 2 to network device 1, where message 2 includes configuration information of RB2. Correspondingly, network device 1 receives message 2 from network device 2.

[0127] In an optional implementation, the configuration information of RB2 includes at least one of the following: a mapping relationship between QoS flow 1 configured by network device 2 and RB2, an identifier of RB2, or a PDCP configuration corresponding to RB2. Optionally, the PDCP configuration corresponding to RB2 includes at least one of the following: a PDCP SN length corresponding to RB2, or a PDCP discard timer duration.

[0128] In an optional implementation, when message 1 includes the configuration information of RB1, network device 2 may refer to the configuration information of RB1 to generate the configuration information of RB2. RB2 may be the same as or different from RB1. For example, network device 2 may determine, based on the configuration information of RB1 in message 1, that network device 1 maps QoS flow 1 to RB1 for cell 1. In this case, network device 2 may also map QoS flow 1 to RB1 for cell 2. In other words, RB2 and RB1 are the same RB.

[0129] In another optional implementation, network device 2 maps QoS flow 1 to RB2 without referring to the configuration information of RB1. RB2 to which network device 2 maps QoS flow 1 may be the same as RB1 or different from RB1.

[0130] In an optional embodiment, message 2 also includes user plane tunnel address information 1, which is user plane tunnel address information allocated by network device 2 to RB2. It is understandable that network device 2 maps QoS flow 1 to RB2 and allocates user plane tunnel address information 1 to RB2. Message 2 sent by network device 2 to network device 1 includes RB2 configuration information and user plane tunnel address information 1. For details about user plane tunnel address information, please refer to the detailed description of the related concepts above and will not be repeated here.

[0131] S103 : Network device 3 sends message 3 to network device 1 , where message 3 includes configuration information of RB 3 . Correspondingly, network device 1 receives message 3 from network device 3 .

[0132] In an optional implementation, the configuration information of RB3 includes at least one of the following: a mapping relationship between QoS flow 1 configured by network device 3 and RB3, an identifier of RB3, or a PDCP configuration corresponding to RB3. Optionally, the PDCP configuration corresponding to RB3 includes one or more of the following: a PDCP SN length corresponding to RB3, or a PDCP discard timer duration.

[0133] In an optional embodiment, when message 1 includes the configuration information of RB1, network device 3 can refer to the configuration information of RB1 to generate the configuration information of RB3. RB3 and RB1 can be the same or different. This is similar to the aforementioned generation of the configuration information of RB2 by network device 2 referring to the configuration information of RB1, and will not be repeated here.

[0134] In another optional implementation, the network device 3 maps the QoS flow 1 to RB3 without referring to the configuration information of RB1. The RB3 to which the network device 3 maps the QoS flow 1 may be the same as or different from RB1.

[0135] In an optional embodiment, message 3 also includes user plane tunnel address information 2, which is user plane tunnel address information allocated by network device 3 to RB3. It is understandable that network device 3 maps QoS flow 1 to RB3 and allocates user plane tunnel address information 2 to RB3. Message 3 sent by network device 3 to network device 1 includes RB3 configuration information and user plane tunnel address information 2. For details about user plane tunnel address information, please refer to the detailed description of the related concepts above and will not be repeated here.

[0136] S104: Network device 1 sends message 4 to network device 2 and network device 3. Message 4 is used to request configuration information of candidate cells. Message 4 includes configuration information of RB2 and RB3. Accordingly, network device 2 receives message 4 from network device 1, and network device 3 receives message 4 from network device 1.

[0137] Message 4 may be, for example, a handover request message.

[0138] In an optional embodiment, message 4 also includes configuration information of RB1 and / or instruction information 1, and instruction information 1 is used to instruct to cooperate with data lossless switching. For the detailed description of configuration information of RB1 and instruction information 1, please refer to the above related description and will not be repeated here.

[0139] In another optional approach, Message 4 does not need to repeat the information included in Message 1, thereby reducing signaling overhead. For example, if Message 1 already includes RB1 configuration information, Message 4 may not include RB1 configuration information. If Message 1 already includes Indication Information 1, Message 4 may not include Indication Information 1, which is used to indicate cooperation for lossless data handover.

[0140] S105 : Network device 2 sends message 5 to network device 1 , where message 5 includes configuration information of cell 2 . Correspondingly, network device 1 receives message 5 from network device 2 .

[0141] Message 5 may be, for example, a handover request acknowledgement message sent by network device 2. The configuration information of cell 2 includes configuration information that a terminal device should use when accessing cell 2.

[0142] In an optional embodiment, when RB2 and RB3 are different, the configuration information of cell 2 in message 5 includes the configuration information of RB2 and indication information 2. Indication information 2 is used to instruct the terminal device to configure RB3 for cell 2. Indication information 2 is specifically, for example, RB3 configuration information. Alternatively, indication information 2 is used to instruct the terminal device not to release RB3 for cell 2.

[0143] It is understandable that for the terminal device, the terminal device communicates with the network device 3 through RB3 when the serving cell is cell 3. If the terminal device receives indication information 2, the terminal device configures RB3 when switching from cell 3 to cell 2, or retains (i.e., does not release) the previously configured RB3, so that the terminal device can transmit between the network device 2 through RB3 after accessing cell 2: data that is not successfully transmitted between the terminal device and the network device 3 through RB3, which is conducive to achieving lossless data switching.

[0144] In addition, in another implementation manner parallel to the manner in which the configuration information of cell 2 includes indication information 2, the configuration information of cell 2 does not include information for instructing the terminal device to release RB3 for cell 2. In this way, if the terminal device does not receive the information for instructing the terminal device to release RB3 for cell 2, the terminal device does not release RB3, that is, the terminal device retains the previously configured RB3.

[0145] Optionally, when RB2 and RB3 are different, message 5 further includes: user plane tunnel address information 1 and user plane tunnel address information 3, where user plane tunnel address information 1 is user plane tunnel address information allocated to RB2 by network device 2, and user plane tunnel address information 3 is user plane tunnel address information allocated to RB3 by network device 2. User plane tunnel address information 3 can be used to forward RB3 data to network device 2 when a terminal device switches from cell 3 to cell 2; this facilitates transmission of RB3 data between the terminal device and network device 2 after the terminal device accesses cell 2, thereby facilitating lossless data switching.

[0146] Exemplarily, network device 2 determines whether RB2 and RB3 are the same based on the configuration information of RB3 in message 4 received in step S104. If RB2 and RB3 are different, network device 2 configures RB3 and assigns user plane tunnel address 3 to RB3. Message 5 sent by network device 2 to network device 1 includes: configuration information of cell 2, user plane tunnel address information 1, and user plane tunnel address information 3. The configuration information of cell 2 includes: configuration information of RB2 and indication information 2, where indication information 2 is, for example, configuration information of RB3.

[0147] In an optional implementation, when RB2 and RB3 are the same, the configuration information of cell 2 in message 5 includes the configuration information of RB2. In this case, the configuration information of cell 2 in message 5 does not include indication information 2, which is used to instruct the terminal device to configure RB3 for cell 2. Optionally, message 5 also includes user plane tunnel address information 1, which is the user plane tunnel address information allocated by network device 2 to RB2.

[0148] Exemplarily, network device 2 determines whether RB2 and RB3 are the same based on the configuration information of RB3 in message 4 received in step S104. If RB2 and RB3 are the same, network device 2 sends message 5 to network device 1 including: configuration information of cell 2 and user plane tunnel address information 1, wherein the configuration information of cell 2 includes the configuration information of RB2.

[0149] In an optional implementation, when RB2 is different from RB1, the configuration information of cell 2 in message 5 also includes indication information 3. Indication information 3 is used to instruct the terminal device to configure RB1 for cell 2. Indication information 3 is, for example, specifically configuration information for RB1. Alternatively, indication information 3 is used to instruct the terminal device not to release RB1 for cell 2. In addition, in another implementation parallel to the method in which the configuration information of cell 2 includes indication information 3, the configuration information of cell 2 does not include information for instructing the terminal device to release RB1 for cell 2.

[0150] Optionally, when RB2 is different from RB1, the configuration information of cell 2 in message 5 also includes user plane tunnel address information 4, where user plane tunnel address information 4 is user plane tunnel address information allocated to RB1 by network device 2. This method is similar to the configuration information of cell 2 in message 5 when RB2 is different from RB3, and is not further described.

[0151] Exemplarily, network device 2 maps QoS flow 1 to RB2 and assigns user plane tunnel address information 1 to RB2. Furthermore, based on RB3's configuration information, network device 2 determines whether RB2 and RB3 are identical. If RB2 and RB3 are different, network device 2 configures RB3 and assigns user plane tunnel address information 3 to RB3. Based on RB1's configuration information, network device 2 determines whether RB2 and RB1 are identical. If RB2 and RB1 are different, network device 2 configures RB1 and assigns user plane tunnel address information 4 to RB1.

[0152] If RB2 is different from RB3 and RB2 is the same as RB1, message 5 includes: configuration information of cell 2, user plane tunnel address information 1, and user plane tunnel address information 3, wherein the configuration information of cell 2 includes: configuration information of RB2 and indication information 2, and indication information 2 is, for example, configuration information of RB3.

[0153] If RB2 is the same as RB3 and RB2 is different from RB1, message 5 includes: configuration information of cell 2, user plane tunnel address information 1, and user plane tunnel address information 4, wherein the configuration information of cell 2 includes: configuration information of RB2 and indication information 3, and indication information 3 is, for example, configuration information of RB1.

[0154] If RB2 is different from RB3 and RB2 is different from RB1, message 5 includes: configuration information of cell 2, user plane tunnel address information 1, user plane tunnel address information 3, and user plane tunnel address information 4, wherein the configuration information of cell 2 includes: configuration information of RB2, indication information 2, and indication information 3, indication information 2 is, for example, the configuration information of RB3, and indication information 3 is, for example, the configuration information of RB1.

[0155] If RB2, RB3, and RB1 are the same, message 5 includes: configuration information of cell 2 and user plane tunnel address information 1, wherein the configuration information of cell 2 includes: configuration information of RB2.

[0156] In another optional embodiment, message 5 sent by network device 2 in step S105 may not repeatedly carry the information already included in message 2 sent by network device 2 in step S102, thereby reducing signaling overhead. For example, since message 2 sent by network device 2 in step S102 already includes RB2 configuration information, message 5 sent by network device 2 in step S105 may not repeatedly carry RB2 configuration information. Furthermore, for example, if message 2 also includes user plane tunnel address information 1, message 5 may not repeatedly carry user plane tunnel address information 1.

[0157] For example, in step S102, if message 2 sent by network device 2 includes RB2 configuration information and user plane tunnel address information 1, and RB2 is different from RB3, message 5 sent by network device 2 includes: cell 2 configuration information and user plane tunnel address information 3, where the cell 2 configuration information includes indication information 2. However, message 5 may not include user plane tunnel address information 1, and the cell 2 configuration information in message 5 may not include RB2 configuration information, thereby reducing signaling overhead.

[0158] In an optional implementation, the configuration information of cell 2 further includes one or more of the following: uplink physical channel configuration information, downlink physical channel configuration information, or measurement configuration information. In the configuration information of cell 2, 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, and the measurement configuration information is used by the terminal device to configure information such as the time domain and frequency domain position of the reference signal to be measured when accessing cell 2.

[0159] S106 : Network device 3 sends message 6 to network device 1 , where message 6 includes configuration information of cell 3 . Correspondingly, network device 1 receives message 6 from network device 3 .

[0160] Message 6 is, for example, a handover request acknowledgement message sent by network device 3. The configuration information of cell 3 includes configuration information that a terminal device should use when accessing cell 3.

[0161] In addition, the network device 3 sends a message 6 to the network device 1, which is similar to the aforementioned network device 2 sending a message 5 to the network device 1. For detailed description, please refer to the description of step S105, which is briefly described below.

[0162] In an optional implementation, when RB3 is different from RB2, the configuration information of cell 3 in message 6 includes the configuration information of RB3 and indication information 4. Indication information 4 is used to instruct the terminal device to configure RB2 for cell 3, and indication information 4 is, for example, specifically the configuration information of RB2. Alternatively, indication information 4 is used to instruct the terminal device not to release RB2 for cell 3. In addition, in another implementation parallel to the method in which the configuration information of cell 3 includes indication information 4, the configuration information of cell 3 does not include information for instructing the terminal device to release RB2 for cell 3.

[0163] Optionally, message 6 also includes: user plane tunnel address information 2 and user plane tunnel address information 5, where user plane tunnel address information 2 is the user plane tunnel address information allocated by network device 3 to RB3, and user plane tunnel address information 5 is the user plane tunnel address information allocated by network device 3 to RB2.

[0164] In an optional implementation, when RB3 is the same as RB2, the configuration information of cell 3 in message 6 includes the configuration information of RB3. In this case, the configuration information of cell 3 in message 6 does not include indication information 4, which is used to instruct the terminal device to configure RB2 for cell 3. Optionally, message 6 also includes user plane tunnel address information 2, which is the user plane tunnel address information allocated by network device 3 to RB3.

[0165] In an optional implementation, when RB3 is different from RB1, the configuration information of cell 3 in message 6 also includes indication information 5. Indication information 5 is used to instruct the terminal device to configure RB1 for cell 3, and indication information 5 is, for example, specific configuration information of RB1. Alternatively, indication information 5 is used to instruct the terminal device not to release RB1 for cell 3. In addition, in another parallel implementation method to the method in which the configuration information of cell 3 includes indication information 5, the configuration information of cell 3 does not include information for instructing the terminal device to release RB1 for cell 3. Optionally, the configuration information of cell 3 in message 6 also includes user plane tunnel address information 6, which is user plane tunnel address information allocated by network device 3 to RB1.

[0166] In another optional implementation, the message 6 sent by the network device 3 in step S106 may not repeatedly carry the information already included in the message 3 sent by the network device 3 in step S103, thereby reducing signaling overhead.

[0167] In an optional implementation manner, the configuration information of cell 3 further includes one or more of the following: uplink physical channel configuration information, downlink physical channel configuration information, or measurement configuration information, etc.

[0168] S107 : Network device 1 sends message 7 to the terminal device, where message 7 includes configuration information of cell 2 and configuration information of cell 3. Correspondingly, the terminal device receives message 7 from network device 1 .

[0169] In the case where the configuration information of cell 2 in message 5 received by the network device 1 through step S105 includes the configuration information of RB2, the configuration information of cell 2 in message 7 is the configuration information of cell 2 in message 5. In the case where the configuration information of cell 2 in message 5 received by the network device 1 through step S105 does not include the configuration information of RB2, the configuration information of cell 2 in message 7 includes, in addition to the configuration information of cell 2 in message 5, the configuration information of cell 2 in message 7 also includes the configuration information of RB2 in message 2 received through step S102.

[0170] Similarly, in the case where the configuration information of cell 3 in message 6 received by network device 1 through step S106 includes the configuration information of RB3, the configuration information of cell 3 in message 7 is the configuration information of cell 3 in message 6. In the case where the configuration information of cell 3 in message 6 received by network device 1 through step S106 does not include the configuration information of RB3, the configuration information of cell 3 in message 7 includes, in addition to the configuration information of cell 3 in message 6, the configuration information of cell 3 in message 7 also includes the configuration information of RB3 in message 3 received through step S103.

[0171] In an optional implementation, for a case where the candidate cells managed by the network device 2 include other candidate cells in addition to cell 2, the candidate cells managed by the network device 2 include cell 4 in addition to cell 2, and the RB mapped by the network device 2 to QoS flow 1 for cell 4 is RB4 as an example for explanation:

[0172] In step S102, network device 2 sends message 2 to network device 1, including not only the configuration information for RB2 but also the configuration information for RB4. The configuration information for RB4 is similar to that for RB2 and will not be described in detail. Optionally, message 2 also includes user plane tunnel address information allocated by network device 2 to RB4.

[0173] In step S104 , the message 4 sent by the network device 1 includes the configuration information of RB4 in addition to the configuration information of RB2 and RB3 .

[0174] In step S105, the message 5 sent by network device 2 to network device 1 includes not only the configuration information of cell 2 but also the configuration information of cell 4. The configuration information of cell 4 is similar to that of cell 2 and will not be described in detail.

[0175] In step S106, the configuration information of cell 3 in message 6 sent by network device 3 to network device 1 is determined based on the configuration information of RB4 in addition to the configuration information of RB2. Specifically, network device 3 also determines whether RB3 and RB4 are the same based on the configuration information of RB4. When RB3 and RB4 are different, network device 3 configures RB4, and the configuration information of cell 3 in message 6 sent to network device 1 also includes: indication information for instructing the terminal device to configure RB4 for cell 3, and the indication information is, for example, the configuration information of RB4. Optionally, when RB3 and RB4 are different, network device 3 also allocates user plane tunnel address information to RB4, and message 6 also includes the user plane tunnel address information allocated by network device 3 to RB4.

[0176] In step S107 , the message 7 sent by the network device 1 to the terminal device includes the configuration information of cell 4 in addition to the configuration information of cell 2 and cell 3 .

[0177] In addition, the situation that the candidate cells managed by the network device 3 include other candidate cells in addition to the cell 3 is similar and will not be described in detail.

[0178] In an optional implementation, for the case 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 is explained as follows: the candidate network devices also include network device 4, the candidate cell managed by network device 4 is cell 5, and the RB mapped by network device 4 to QoS flow 1 for cell 5 is RB5.

[0179] In step S101, in addition to sending message 1 to network devices 2 and 3, network device 1 also sends message 1 to network device 4. After receiving message 1 from network device 1, network device 4 sends a message including configuration information of RB5 to network device 1. The configuration information of RB5 is similar to the configuration information of RB1, RB2, and RB3, and will not be repeated here.

[0180] In step S104 , network device 1 sends message 4 to network device 4 in addition to network device 2 and network device 3 . Message 4 includes configuration information of RB5 in addition to configuration information of RB2 and RB3 .

[0181] In step S105, the configuration information of cell 2 in message 5 sent by network device 2 to network device 1 is determined based on the configuration information of RB5 in addition to the configuration information of RB3. Specifically, network device 2 also determines whether RB2 and RB5 are the same based on the configuration information of RB5. When RB2 and RB5 are different, network device 2 configures RB5. The configuration information of cell 2 in message 5 sent to network device 1 also includes: indication information for instructing the terminal device to configure RB5 for cell 2. The indication information is, for example, the configuration information of RB5. Optionally, when RB2 and RB5 are different, network device 2 also allocates user plane tunnel address information to RB5. Message 5 also includes the user plane tunnel address information allocated by network device 2 to RB5.

[0182] In step S106, the configuration information of cell 3 in message 6 sent by network device 3 to network device 1 is determined based on the configuration information of RB5 in addition to the configuration information of RB2. This is similar to the case where message 5 sent by network device 2 to network device 1 is also determined based on the configuration information of RB5, and will not be repeated here.

[0183] After receiving message 4 from network device 1, network device 4 also sends a message including configuration information of cell 5 to network device 1. This is similar to network device 2 sending message 5 to network device 1 and network device 3 sending message 6 to network device 1, and will not be repeated here.

[0184] In step S107 , the message 7 sent by the network device 1 to the terminal device includes the configuration information of cell 5 in addition to the configuration information of cell 2 and cell 3 .

[0185] It can be seen that in this communication method, the network device 1 collects the configuration information of the RB mapped by each candidate network device, and sends the configuration information of the RB mapped by other candidate network devices to each candidate network device, which is beneficial for each candidate network device to judge whether the QoS flow to RB remapping occurs during the switching when the terminal device switches to itself, and in the event that the QoS flow to RB remapping occurs, the RB mapped by the configured source network device can be used to transmit: data that was not successfully transmitted between the source network device and the terminal device, thereby realizing lossless data switching.

[0186] The following describes the handover process of a terminal device by taking the case where the target cell for handover from cell 1 is cell 2, and the target cell for handover from cell 2 is cell 3 after the terminal device accesses cell 2 as an example:

[0187] S108 : Network device 1 sends a handover command 1 to the terminal device, where the handover command 1 is used to instruct the terminal device to handover to cell 2. Correspondingly, the terminal device receives the handover command 1 from network device 1 .

[0188] In an optional implementation, the handover command may be carried, for example, in a media access control control element (MAC CE), or in downlink control information (DCI), or in a radio resource control (RRC) message. This application does not limit the specific signaling carrying method. In a scenario where the embodiment of the present application is applied to LTM technology, the handover command may be an LTM handover command (LTM handover command, LTM HO CMD). This will not be described in detail below.

[0189] In an optional embodiment, the handover command includes an 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 switch to the target cell based on the configuration information of the target cell. In the embodiment of the present application, the identifier of the cell can be, for example, a global cell identifier (CGI), a physical cell identifier (PCI), or a configured cell identifier (ID), without limitation. This will not be repeated herein.

[0190] For example, the handover command 1 may be carried in a MAC CE, a DCI, or an RRC, without limitation. The handover command 1 may include an identifier of cell 2, so that the terminal device may determine that the target cell for handover is cell 2 based on the identifier of cell 2, and the terminal device may then handover to cell 2 based on the configuration information of cell 2. In addition, other handover commands mentioned later (such as the handover command 2) are similar to the handover command 1 and are not described in detail.

[0191] S109 : Network device 1 sends message 8 to network device 2 , where message 8 is used to notify network device 2 that the terminal device is about to switch to network device 2 . Correspondingly, network device 2 receives message 8 from network device 1 .

[0192] Message 8 is, for example, a handover notification message sent by network device 1 to network device 2. For example, in a scenario where the embodiment of the present application is applied to the LTM technology, message 8 may be an LTM Notification message sent by network device 1 to network device 2.

[0193] In an optional implementation, message 8 includes the identifier of cell 2. In this way, network device 2 can determine that the target cell when the terminal device is handed over from network device 1 to network device 2 is cell 2.

[0194] In an optional implementation, message 8 includes the identifier of cell 1. In this way, network device 2 can determine that the source cell when the terminal device switches from network device 1 to network device 2 is cell 1 based on the identifier of cell 1.

[0195] S110: Network device 1 sends data from RB1 to network device 2; correspondingly, network device 2 receives data from RB1 of network device 1. The data from RB1 includes: downlink data that network device 1 failed to send to the terminal device via RB1, and / or uplink data from the terminal device that network device 1 received via RB1 and that was not sent to the core network device.

[0196] In an optional embodiment, the method further includes: network device 1 determining, based on an identifier of cell 2, user plane tunnel address information allocated by network device 2 to RB1 for cell 2. Then, network device 1 sends data of RB1 to network device 2 based on the user plane tunnel address information allocated by network device 2 to RB1 for cell 2.

[0197] For example, if RB2 is the same as RB1, the user plane tunnel address information allocated by network device 2 to RB1 is: the user plane tunnel address information allocated by network device 2 to RB2 is user plane tunnel address information 1, and user plane tunnel address information 1 is carried in message 2 in step S102 and / or message 5 in step S105 and sent by network device 2 to network device 1, so that network device 1 sends RB1 data to network device 2 based on user plane tunnel address information 1.

[0198] Exemplarily, if RB2 is different from RB1, network device 2 additionally allocates user plane tunnel address information 4 to RB1, and carries it in message 5 in step S105 and sends it to network device 1, so that network device 1 sends RB1 data to network device 2 based on user plane tunnel address information 4.

[0199] S111. The terminal device switches to cell 2 based on the configuration information of cell 2.

[0200] In an optional embodiment, the method further includes: network device 2 determining, based on the identifier of cell 1, that the RB mapped by cell 1 to QoS flow 1 is RB1. Network device 2 determines whether RB2 is the same as RB1. If RB2 is different from RB1, after the terminal device accesses cell 2, network device 2 may transmit data between the terminal device and network device 1 through RB1, including data that was not successfully transmitted between the terminal device and network device 1, and further transmit data between the network device and the terminal device through RB2.

[0201] In another optional manner, the method further includes: network device 2 determining, based on the identifier of cell 1, that the RB mapped by cell 1 to QoS flow 1 is RB1. Network device 2 determines the RB used for data transmission with the terminal device from the locally configured RBs.

[0202] The RB used by network device 2 for data transmission with the terminal device is RB2, which is the same as RB1. The data that can be transmitted between network device 2 and the terminal device via RB1 includes: data that was not successfully transmitted between the terminal device and network device 1, and data between the terminal device and network device 2.

[0203] Alternatively, network device 2 determines that the RBs used for data transmission with the terminal device are RB1 and RB2, and RB1 is different from RB2. Network device 2 and the terminal device can transmit data via RB1: data that was not successfully transmitted between the terminal device and network device 1 can also be transmitted between network device 2 and the terminal device via RB2.

[0204] For example, network device 2 sends data 1 to the terminal device through RB1, and the terminal device receives data 1 from network device 2 through RB1. Data 1 is the downlink data that network device 1 fails to send to the terminal device through RB1. Data 1 is forwarded by network device 1 to network device 2 in step S110, thereby realizing lossless switching of downlink data when the terminal device switches from cell 1 to cell 2.

[0205] Exemplarily, the terminal device sends data 2 to network device 2 via RB1, and network device 2 receives data 2 from the terminal device via RB1. Data 2 is the uplink data that the terminal device failed to successfully send to network device 1 via RB1, thereby achieving lossless switching of uplink data when the terminal device switches from cell 1 to cell 2. Optionally, in step S110, the data forwarded by network device 1 to network device 2 includes: uplink data from the terminal device received by network device 1 via RB1 and the uplink data is not sent to the core network device. In this case, network device 2 also reorders data 2 with the uplink data received in step S110 and sends them to the core network device, thereby enabling the uplink data of RB1 to be sent to the core network device in sequence.

[0206] Optionally, the identifier of cell 1 may be carried in message 8 sent by network device 1 to network device 2 in step S109, so that network device 2 determines that the source cell when the terminal device switches to cell 2 is cell 1. In addition, in addition to this method, network device 2 may also determine the source cell when the terminal device switches to cell 2 by other methods. The embodiment of the present application does not limit the specific method by which the target network device determines the source cell.

[0207] S112: Network device 2 sends handover command 2 to the terminal device, where handover command 2 is used to instruct the terminal device to handover to cell 3. Accordingly, the terminal device receives handover command 2 from network device 2. This step is similar to step S108 and will not be repeated here.

[0208] S113: Network device 2 sends message 9 to network device 3, which notifies network device 3 that the terminal device is about to switch to network device 3. Accordingly, network device 3 receives message 9 from network device 2. This step is similar to step S109 and will not be repeated here.

[0209] S114: Network device 2 sends RB2 data to network device 3; correspondingly, network device 3 receives RB2 data from network device 2. The RB2 data includes: downlink data that network device 2 failed to send to the terminal device via RB2, and / or uplink data from the terminal device that network device 2 received via RB2 and that was not sent to the core network device.

[0210] In an optional embodiment, the method further includes: network device 2 determining, based on the identifier of cell 3, user plane tunnel address information allocated by network device 3 to RB2 for cell 3. Then, network device 2 sends data of RB2 to network device 3 based on the user plane tunnel address information allocated by network device 3 to RB2 for cell 3.

[0211] Exemplarily, if RB3 is the same as RB2, the user plane tunnel address information allocated by network device 3 to RB2 is: the user plane tunnel address information allocated by network device 3 to RB3 is user plane tunnel address information 2, and user plane tunnel address information 2 is carried in message 3 in step S103 and / or message 6 in step S106 and sent by network device 3 to network device 1. Exemplarily, if RB2 is different from RB1, network device 2 additionally allocates user plane tunnel address information 4 to RB1, and carries it in message 5 in step S105 and sends it to network device 1.

[0212] In an optional manner, after collecting the user plane tunnel address information assigned by each candidate network device, network device 1 sends the user plane tunnel address information assigned by each candidate network device to each candidate network device, so that network device 2 can obtain the user plane tunnel address information assigned by each candidate network device (including network device 3). Exemplarily, network device 1 sends the user plane tunnel address information (i.e., the user plane tunnel address information assigned by network device 2) carried in the message received from network device 2 based on steps S102 and S105 to network device 3, and sends the user plane tunnel address information (i.e., the user plane tunnel address information assigned by network device 3) carried in the message received from network device 3 based on steps S103 and S106 to network device 2.

[0213] In another optional manner, the message 8 sent by network device 1 through step S109 also includes: user plane tunnel address information allocated by each candidate network device collected by network device 1, so that network device 2 can obtain the user plane tunnel address information allocated by each candidate network device (including network device 3). Exemplarily, the message 8 sent by network device 1 to network device 2 also includes: user plane tunnel address information carried in the message from network device 3 received by network device 1 based on steps S103 and S106 (i.e., user plane tunnel address information allocated by network device 3). Optionally, in this manner, the message 9 sent by network device 2 to network device 3 in step S113 also includes: user plane tunnel address information allocated by each candidate network device collected by network device 1, so that network device 3 can obtain the user plane tunnel address information allocated by each candidate network device (including network device 2). Then, when the terminal device switches from cell 3 to cell 2, network device 3 can forward RB3 data to network device 2 based on the user plane tunnel address information allocated by network device 2 for RB3, thereby facilitating lossless data switching. It is understandable that the source network device of each handover may send the user plane tunnel address information allocated to each candidate network device collected by the network device 1 to the target network device via a handover notification message.

[0214] In addition to the above-mentioned method in which the network device 2 determines the user plane tunnel address information allocated by the network device 3 to the RB2, the network device 2 may also determine it in other methods, which are not limited.

[0215] S115. The terminal device switches to cell 3 based on the configuration information of cell 3.

[0216] In an optional embodiment, the method further includes: network device 3 determining, based on the identifier of cell 2, that the RB mapped by cell 2 to QoS flow 1 is RB2. Network device 3 determines whether RB3 is the same as RB2. If RB3 is different from RB2, after the terminal device accesses cell 3, network device 3 may transmit data between the terminal device and network device 2 via RB2: data that was not successfully transmitted between the terminal device and network device 2, and network device 3 may also transmit data between the terminal device and network device 2 via RB3.

[0217] In another optional manner, the method further includes: the network device 3 determines that the RB mapped by the cell 2 to the QoS flow 1 is RB2 based on the identifier of the cell 2. The network device 3 determines the RB used for data transmission with the terminal device from the locally configured RBs.

[0218] Among them, the RB used for data transmission between network device 3 and terminal device is determined to be RB3, which is the same as RB2. The data that can be transmitted between network device 3 and terminal device via RB3 includes: data that was not successfully transmitted between terminal device and network device 1, and data between terminal device and network device 2.

[0219] Alternatively, network device 3 determines that the RBs used for data transmission with the terminal device are RB2 and RB3, and RB2 is different from RB3. Network device 3 and the terminal device can transmit data via RB2: data that was not successfully transmitted between the terminal device and network device 2 can also be transmitted between network device 3 and the terminal device via RB3.

[0220] Optionally, the identifier of cell 2 may be included in message 9 sent by network device 2 to network device 3 in step S113, so that network device 3 determines that the source cell when the terminal device switches to cell 3 is cell 2. In addition to this method, network device 3 may also determine the source cell when the terminal device switches to cell 3 by other methods, without limitation. This is similar to the case where the terminal device switches to cell 2, and will not be further described.

[0221] Please refer to FIG8 , which is a flow chart of another communication method provided in an embodiment of the present application. The communication method includes the following steps.

[0222] S201. Network device 1 sends message 1 to network device 2 and network device 3. Message 1 is used to request configuration information of RBs mapped to QoS flow 1. Accordingly, network device 2 receives message 1 from network device 1, and network device 3 receives message 1 from network device 1.

[0223] S202: Network device 2 sends message 2 to network device 1, where message 2 includes configuration information of RB2. Correspondingly, network device 1 receives message 2 from network device 2.

[0224] S203 : Network device 3 sends message 3 to network device 1 , where message 3 includes configuration information of RB 3 . Correspondingly, network device 1 receives message 3 from network device 3 .

[0225] S204: Network device 1 sends message 4 to network device 2 and network device 3. Message 4 is used to request configuration information of candidate cells. Message 4 includes configuration information of RB2 and RB3. Accordingly, network device 2 receives message 4 from network device 1, and network device 3 receives message 4 from network device 1.

[0226] S205 : Network device 2 sends message 5 to network device 1 , where message 5 includes configuration information of cell 2 . Correspondingly, network device 1 receives message 5 from network device 2 .

[0227] S206 : Network device 3 sends message 6 to network device 1 , where message 6 includes configuration information of cell 3 . Correspondingly, network device 1 receives message 6 from network device 3 .

[0228] S207 : Network device 1 sends message 7 to the terminal device, where message 7 includes configuration information of cell 2 and configuration information of cell 3. Correspondingly, the terminal device receives message 7 from network device 1 .

[0229] For detailed description of steps S201 to S207 , please refer to the relevant description of steps S101 to S107 in the communication method described in FIG7 , which also have corresponding beneficial effects and will not be described in detail.

[0230] In addition, in step S207, the configuration information of cell 2 in message 7 sent by network device 1 to the terminal device also includes the switching trigger condition corresponding to cell 2, and the configuration information of cell 3 also includes the switching trigger condition corresponding to cell 3. It can be understood that the switching trigger condition corresponding to the cell is used by the terminal device to determine to switch to the cell when the cell meets the corresponding switching trigger condition. For example, the switching trigger condition corresponding to cell 2 is that the signal quality of cell 2 is X higher than the signal quality of the terminal device's current serving cell; after measurement, the terminal device determines that the signal quality of cell 2 is X higher than the signal quality of the serving cell, that is, when cell 2 meets its corresponding switching trigger condition, the terminal device determines to switch to cell 2.

[0231] The following describes the handover process of a terminal device by taking the case where the target cell for handover from cell 1 is cell 2, and the target cell for handover from cell 2 is cell 3 after the terminal device accesses cell 2 as an example:

[0232] S208. The terminal device determines whether the switching trigger condition is met.

[0233] S209. Network device 1 sends data from RB1 to network device 2, and / or sends data from RB1 to network device 3. Accordingly, network device 2 receives data from RB1 of network device 1, and network device 3 receives data from RB1 of network device 1. The data from RB1 includes: downlink data that network device 1 failed to send to the terminal device via RB1, and / or uplink data that network device 1 received from the terminal device via RB1 and that was not sent to the core network device.

[0234] It is understood that, when network device 1 has not yet determined the target network device to which the terminal device is to be switched, it sends the data of RB1 to network device 2 and / or sends the data of RB1 to network device 3, so that network device 2 can transmit the data acquired in advance when the terminal device successfully switches to network device 2. It should be understood that step S209 is an early data forwarding process, or an advance data forwarding process, and step S209 is an optional step.

[0235] Optionally, before determining the target network device for handover of the terminal device, network device 1 may determine to send the RB1 data to network device 2 and / or network device 3 based on the measurement results reported by the terminal device. The measurement results reported by the terminal device may include the signal quality of the candidate cell measured by the terminal device. For example, if the signal quality of the cell managed by network device 2 is good, network device 1 may send the RB1 data of the terminal device to network device 2.

[0236] In addition, network device 1 sends RB1 data to network device 3, which is similar to network device 1 sending RB1 data to network device 2. For details about network device 1 sending RB1 data to network device 2, please refer to the relevant description in the communication method described in Figure 7, which will not be repeated here.

[0237] S210. When cell 2 meets the switching triggering condition, the terminal device switches to cell 2 based on the configuration information of cell 2.

[0238] S211 : Network device 2 sends a switching success message to network device 1 .

[0239] It is understandable that network device 2 determines that the source network device when the terminal device switches to network device 2 is network device 1. After the terminal device accesses cell 2, network device 2 sends a switching success message to network device 1. The specific implementation of network device 2 determining that the source network device when the terminal device switches to network device 2 is network device 1 is described in the following optional implementations 1 to 3.

[0240] In implementation mode 1, network device 2 determines that the source network device when a terminal device switches to network device 2 is network device 1, including: during the process of switching to cell 2 or after successfully switching to cell 2, the terminal device sends the identifier of cell 1 or the identifier of network device 1 to network device 2. Based on the identifier of cell 1 received from the terminal device, network device 2 determines that the source cell when the terminal device switches to cell 2 is cell 1, thereby determining that the source network device when the terminal device switches to network device 2 is: network device 1 for managing cell 1. Alternatively, network device 2 determines that the source network device when the terminal device switches to network device 2 is network device 1 based on the identifier of network device 1 received from the terminal device.

[0241] Implementation method 2, in which network device 2 determines that the source network device when the terminal device switches to network device 2 is network device 1, includes: when the terminal device determines that the target cell to which it is about to switch from cell 1 is cell 2, the terminal device may also communicate with network device 1, and the terminal device sends an identifier of cell 2 or an identifier of network device 2 to network device 1. Network device 1 determines that the network device for managing cell 2 is network device 2 based on the identifier of cell 2; alternatively, network device 1 determines network device 2 based on the identifier of network device 2. Network device 1 sends the identifier of cell 1 or an identifier of network device 1 to network device 2. Network device 2 determines that the source cell when the terminal device switches to cell 2 is cell 1 based on the identifier of cell 1 received from network device 1, thereby determining that the source network device when the terminal device switches to network device 2 is: network device 1 for managing cell 1. Alternatively, network device 2 determines that the source network device when the terminal device switches to network device 2 is network device 1 based on the identifier of network device 1 received from network device 1.

[0242] Implementation method 3, network device 2 determines that the source network device when the terminal device switches to network device 2 is network device 1, including: when the terminal device accesses network device 2, if the message most recently received by network device 2 for indicating the identity of the serving network device of the terminal device is: a message for indicating that the serving network device of the terminal device is network device 1, network device 2 determines that the source network device when the terminal device switches to network device 2 is network device 1. If network device 2 does not receive the message for indicating the identity of the serving network device of the terminal device, network device 2 determines that the source network device when the terminal device switches to network device 2 is: network device 1 that sent message 1 (message 1 is used to request configuration information of RBs mapped to QoS flow 1) and message 4 (message 4 is used to request configuration information of candidate cells).

[0243] In addition, based on Embodiment 3, the method further includes: when the terminal device successfully switches to Network Device 2, Network Device 2 sends a message indicating that the terminal device's current serving network device is Network Device 2 to candidate network devices to which the terminal device may switch from Network Device 2. This approach enables the target network device in the next handover after the terminal device switches from Network Device 1 to Network Device 2 to determine that the source network device is Network Device 2. Similarly, in each subsequent handover of the terminal device, the target network device notifies all candidate network devices of the identity of the current serving network device of the terminal device after the terminal device connects.

[0244] S212: Network device 1 sends data from RB1 to network device 2; correspondingly, network device 2 receives data from RB1 of network device 1. The data from RB1 includes: downlink data that network device 1 failed to send to the terminal device via RB1, and / or uplink data from the terminal device that network device 1 received via RB1 and that was not sent to the core network device.

[0245] For the detailed description of step S212 , please refer to the detailed description of step S110 , which will not be repeated here.

[0246] In an optional embodiment, the method further includes: the network device 2 determines that the RB mapped by cell 1 to QoS flow 1 is RB1 based on the identifier of cell 1. The network device 2 determines whether RB2 is the same as RB1. When RB2 is different from RB1, after the terminal device accesses cell 2, the network device 2 can transmit data with the terminal device through RB1: for data that was not successfully transmitted between the terminal device and network device 1, the network device 2 also transmits data with the terminal device through RB3. In another optional manner, the method further includes: the network device 2 determines that the RB mapped by cell 1 to QoS flow 1 is RB1 based on the identifier of cell 1. The network device 2 determines the RB used for data transmission with the terminal device from the locally configured RBs. For the specific description of this embodiment, please refer to the relevant description in the communication method described in Figure 7, which will not be repeated here.

[0247] S213: The terminal device determines whether the switching trigger condition is met.

[0248] At step S214, network device 2 sends the data for RB2 to network device 3. Correspondingly, network device 3 receives the data for RB2 from network device 2. It should be understood that step S214 is an early data forwarding process, or an advanced data forwarding process, and is optional. Step S214 is similar to step S209, and reference can be made to the detailed description of step S209.

[0249] S215. When cell 3 meets the switching triggering condition, the terminal device switches to cell 3 based on the configuration information of cell 3.

[0250] S216 : Network device 3 sends a switching success message to network device 2 . Correspondingly, network device 2 receives the switching success message from network device 3 .

[0251] It is understandable that network device 3 determines that the source network device when the terminal device switches to network device 3 is network device 2. After the terminal device accesses cell 3, network device 3 sends a switching success message to network device 2. Network device 3 determines that the source network device when the terminal device switches to network device 3 is network device 2, which is similar to the aforementioned network device 2 determining that the source network device when the terminal device switches to network device 2 is network device 1, and will not be repeated.

[0252] S217: Network device 2 sends RB2 data to network device 3; correspondingly, network device 3 receives RB2 data from network device 2. The RB2 data includes: downlink data that network device 3 failed to send to the terminal device via RB2, and / or uplink data from the terminal device that network device 2 received via RB2 and that was not sent to the core network device.

[0253] In an optional embodiment, the method further includes: network device 2 determining, based on the identifier of cell 3, user plane tunnel address information allocated by network device 3 to RB2 for cell 3. Then, network device 2 sends RB2 data to network device 3 based on the user plane tunnel address information allocated by network device 3 to RB2 for cell 3. For this embodiment, reference can be made to the relevant description of network device 2 sending RB2 data to network device 3 in the communication method depicted in FIG. The following briefly describes how network device 2 obtains the user plane tunnel address information allocated by network device 3:

[0254] In an optional manner, after collecting the user plane tunnel address information assigned by each candidate network device, network device 1 sends the user plane tunnel address information assigned by each candidate network device to each candidate network device, so that network device 2 can obtain the user plane tunnel address information assigned by each candidate network device (including network device 3). Exemplarily, network device 1 sends the user plane tunnel address information (including the user plane tunnel address information assigned by network device 2 to RB3) carried in the message received from network device 2 based on steps S202 and S205 to network device 3, and sends the user plane tunnel address information (including the user plane tunnel address information assigned by network device 3 to RB2) carried in the message received from network device 3 based on steps S203 and S206 to network device 2.

[0255] In another optional manner, after step S211, network device 1 sends to network device 2: the user plane tunnel address information allocated by each candidate network device collected by network device 1, so that network device 2 can obtain the user plane tunnel address information allocated by each candidate network device (including network device 3). Exemplarily, after step S211, network device 1 sends to network device 2: the user plane tunnel address information (including the user plane tunnel address information allocated by network device 3 to RB2) carried in the message received from network device 3 based on steps S203 and S206. Optionally, in this manner, after step S216, network device 2 also sends to network device 3: the user plane tunnel address information allocated by each candidate network device collected by network device 1, so that network device 3 can obtain the user plane tunnel address information allocated by each candidate network device (including network device 2). Then, when the terminal device switches from cell 3 to cell 2, network device 3 can forward RB3's data to network device 2 based on the user plane tunnel address information allocated by network device 2 to RB3, thereby facilitating lossless data switching. It is understandable that the source network device of each handover may send to the target network device: the user plane tunnel address information allocated to each candidate network device collected by the network device 1 .

[0256] In addition to the above-mentioned method in which the network device 2 determines the user plane tunnel address information allocated by the network device 3 to the RB2, the network device 2 may also determine it in other methods, which are not limited.

[0257] In an optional embodiment, the method further includes: the network device 3 determines that the RB mapped by cell 2 to QoS flow 1 is RB2 based on the identifier of cell 2. The network device 3 determines whether RB3 is the same as RB2. When RB3 is different from RB2, after the terminal device accesses cell 3, the network device 3 can transmit data with the terminal device through RB2: for data that has not been successfully transmitted between the terminal device and network device 2, the network device 3 also transmits data with the terminal device through RB3. In another optional manner, the method further includes: the network device 3 determines that the RB mapped by cell 2 to QoS flow 1 is RB2 based on the identifier of cell 2. The network device 3 determines the RB used for data transmission with the terminal device from the locally configured RBs. For the specific description of this embodiment, please refer to the relevant description in the communication method described in Figure 7, which will not be repeated here.

[0258] In addition, in an optional embodiment, for the case where the network device is a CU-DU separation architecture, different network devices communicate through the CU, and the communication between the CU in the network device and the terminal device is achieved by forwarding the DU in the network device.

[0259] For example, using the method described in FIG7 as an example, network devices 1, 2, and 3 all employ a CU-DU split architecture. In conjunction with FIG9 , communication between network devices 1, 2, and 3 specifically involves communication between the CU in network device 1, the CU in network device 2, and the CU in network device 3. Communication between the CU in any of network devices 1, 2, and 3 and the terminal device is achieved through DU forwarding. Furthermore, in step S107, the CU in network device 1 sends message 7 to the terminal device.

[0260] In addition, in the case where the network device is a CU-DU separation architecture, the switching command can be generated by the CU in the network device, and then the CU in the network device sends the switching command to the DU, and the DU sends the switching command to the terminal device; or, the switching command can be generated by the DU in the network device, and the DU sends the switching command to the terminal device.

[0261] For example, in step S108, the handover command 1 sent by network device 1 to the terminal device may be generated by the CU in network device 1, which then sends the handover command to the DU in network device 1, which then sends the handover command 1 to the terminal device. Alternatively, the handover command 1 may be generated by the DU in network device 1, which then sends the handover command 1 to the terminal device.

[0262] For another example, in step S112, the handover command 2 sent by network device 2 to the terminal device may be generated by the CU in network device 2, which then sends the handover command to the DU in network device 2, which then sends the handover command to the terminal device. Alternatively, the handover command 2 may be generated by the DU in network device 2, which then sends the handover command 2 to the terminal device.

[0263] Please refer to FIG10 , which is a flow chart of another communication method provided in an embodiment of the present application. The communication method includes the following steps.

[0264] S301 : Network device 2 sends RB2 configuration information to network device 1 . The RB2 configuration information includes a mapping relationship between QoS flow 1 and RB2 configured by network device 2 . Correspondingly, network device 1 receives the RB2 configuration information from network device 2 .

[0265] In an optional embodiment, the method further includes: network device 1 sends message 1 to network device 2, message 1 being used to request provision of configuration information of RB mapped to QoS flow 1. Optionally, message 1 includes an identifier of QoS flow 1. Optionally, message 1 further includes configuration information and / or indication information 1 of RB1, the configuration information of RB1 includes a mapping relationship between QoS flow 1 configured by network device 1 and RB1, and indication information 1 is used to indicate cooperation in lossless data switching. Optionally, in the case that message 1 includes the configuration information of RB1, network device 2 may refer to the configuration information of RB1 to generate the configuration information of RB2, and RB2 may be the same as or different from RB1.

[0266] In an optional embodiment, the method further includes: network device 2 sending user plane tunnel address information 1 to network device 1, where user plane tunnel address information 1 is user plane tunnel address information allocated by network device 2 to RB2; and network device 1 sending user plane tunnel address information 1 to network device 3. Optionally, user plane tunnel address information 1 and RB2 configuration information may be carried in the same message and sent by network device 2 to network device 1.

[0267] S302: Network device 1 sends configuration information of RB2 to network device 3. Correspondingly, network device 3 receives configuration information of RB2 from network device 1.

[0268] In an optional implementation, the configuration information of RB2 sent by network device 1 to network device 3 may be carried in message 4 sent by network device 3, where message 4 is used to request configuration information of candidate cells. Optionally, message 4 also includes configuration information of RB1 and / or indication information 1, where the configuration information of RB1 includes a mapping relationship between QoS flow 1 configured by network device 1 and RB1, and indication information 1 is used to instruct cooperation in lossless data switching.

[0269] S303 : Network device 3 responds to the configuration information of RB2 and sends the configuration information of cell 3 to network device 1 . Correspondingly, network device 1 receives the configuration information of cell 3 from network device 3 .

[0270] In the case where RB3 is different from RB2, the configuration information for cell 3 includes the configuration information for RB3 and indication information 4. Indication information 4 is used to instruct the terminal device to configure RB2 for cell 3. Indication information 4 may be, for example, the configuration information for RB2. Alternatively, indication information 4 is used to instruct the terminal device not to release RB2 for cell 3. Furthermore, in another implementation parallel to the method in which the configuration information for cell 3 includes indication information 4, the configuration information for cell 3 does not include indication information for instructing the terminal device to release RB2 for cell 3.

[0271] In the case that RB3 is the same as RB2, the configuration information of cell 3 includes the configuration information of RB3, wherein the configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by network device 3 and RB3.

[0272] In an optional embodiment, the method further includes: network device 3 determining whether RB3 is the same as RB2 based on the configuration information of RB2. If RB3 is different from RB2, network device 2 configures RB3.

[0273] In an optional implementation, when RB3 and RB2 are different, the configuration information of RB3 and indication information 4 in the configuration information of cell 3 can be received separately by network device 1, or can be carried in the same message and sent by network device 3 to network device 1.

[0274] Exemplarily, network device 1 sends message 1 to network device 3, requesting configuration information for RBs mapped to QoS flow 1; network device 3 sends configuration information for RB3 to network device 1. Next, network device 1 sends message 4 to network device 3, requesting configuration information for candidate cells, including configuration information for RB2; if RB3 is different from RB2, network device 3 sends indication message 4 to network device 1.

[0275] As another example, network device 1 sends message 4 to network device 3, where message 4 is used to request configuration information of the candidate cell, and message 4 includes configuration information of RB2; when RB3 is different from RB2, network device 3 sends configuration information of RB3 and indication information 4 to network device 1.

[0276] In an optional embodiment, the method further includes: when RB3 and RB2 are different, network device 3 assigns user plane tunnel address information 5 to RB2 and sends user plane tunnel address information 5 to network device 1; and network device 1 sends user plane tunnel address information 5 to network device 2. In this way, when RB3 and RB2 are different, network device 2 can forward RB2's data to network device 3 based on user plane tunnel address information 5 when a terminal device switches from network device 2 to network device 3, facilitating lossless data handover. Optionally, user plane tunnel address information 5 and cell 3 configuration information can be included in the same message sent by network device 3 to network device 1.

[0277] In an optional embodiment, the method further includes: network device 1 sends configuration information of RB1 to network device 3, and the configuration information of RB1 includes a mapping relationship between QoS flow 1 configured by network device 1 and RB1; network device 1 receives the configuration information of cell 3 sent by network device 3 in response to the configuration information of RB2, including: network device 1 receives the configuration information of cell 3 sent by network device 3 in response to the configuration information of RB2 and the configuration information of RB1. In the case that RB3 is different from RB1, the configuration information of cell 3 also includes indication information 5. The indication information 5 is used to instruct the terminal device to configure RB1 for cell 3, and the indication information 5 is, for example, the configuration information of RB1. Alternatively, the indication information 5 is used to instruct the terminal device not to release RB1 for cell 3. In addition, in another parallel implementation method to the method in which the configuration information of cell 3 includes the indication information 5, the configuration information of cell 3 does not include information for instructing the terminal device to release RB1 for cell 3.

[0278] Optionally, the configuration information of RB1 sent by network device 1 to network device 3 can be carried in: message 1 and / or message 4 sent by network device 1 to network device 3, message 1 is used to request the configuration information of RB mapped to QoS flow 1, and message 4 is used to request the configuration information of candidate cells.

[0279] In an optional embodiment, the method further includes: network device 1 sending indication information 1 to network device 3, where indication information 1 is used to instruct cooperation in data lossless switching. Optionally, indication information 1 sent by network device 1 to network device 3 may be carried in message 1 and / or message 4 sent by network device 1 to network device 3, where message 1 is used to request configuration information of RBs mapped to QoS flow 1, and message 4 is used to request configuration information of candidate cells.

[0280] S304. Network device 1 sends configuration information of cell 3 to terminal device.

[0281] In an optional embodiment, the method further includes: network device 3 sending RB3 configuration information to network device 1, where the RB3 configuration information includes a mapping relationship between QoS flow 1 configured by network device 3 and RB3. Network device 1 sends the RB3 configuration information to network device 2. Network device 2 responds to the RB3 configuration information by sending the configuration information of cell 2 to network device 1. Therefore, in addition to sending the configuration information of cell 3 to the terminal device, network device 1 also sends the configuration information of cell 2 to the terminal device.

[0282] In an optional embodiment, network device 1 is the source network device for the first handover performed by the terminal device, network device 2 is the source network device for the i-th handover performed by the terminal device, and network device 3 is the target network device for the i-th handover performed by the terminal device, where i is an integer greater than 1. The first handover performed by the terminal device can be network device 1 or the first handover of the mobility technology initially initiated by the terminal device, that is, the source network device for the first handover performed by the terminal device is the initial source network device. For example, the embodiment of the present application can be applied to LTM technology, and the first handover performed by the terminal device can be network device 1 or the first handover of LTM initially initiated by the terminal device.

[0283] In an optional manner, the method further includes: when network device 2 determines that the target network device for the terminal device to perform the i-th handover is network device 3, network device 2 forwards RB2 data to network device 3 based on the user plane tunnel address information assigned by network device 3 to RB2. After the terminal device accesses cell 3, network device 3 transmits to the terminal device via RB2: data that was not successfully transmitted between the terminal device and network device 2 via RB2. The specific manner in which network device 2 obtains the user plane tunnel address information assigned by network device 3 to RB2 can be found in the relevant description of the method described in Figures 7 and 8, and will not be repeated here.

[0284] Optionally, after the terminal device accesses the network device 3, the network device 3 determines that the source cell for the terminal device to perform the i-th handover is cell 2, and further determines that the RB mapped by cell 2 to QoS flow 1 is RB2. The network device 3 determines whether RB3 is the same as RB2. In the case that RB3 is different from RB2, after the terminal device accesses the cell 3, the network device 3 can transmit data with the terminal device through RB2: for data that has not been successfully transmitted between the terminal device and the network device 2, the network device 3 also transmits data with the terminal device through RB3. In another optional manner, the method further includes: the network device 3 determines that the RB mapped by cell 2 to QoS flow 1 is RB2 based on the identifier of cell 2; the network device 3 determines the RB used for data transmission with the terminal device from the locally configured RBs.

[0285] For example, network device 3 receives an identifier of cell 2 from network device 2 or a terminal device, and determines that the RB corresponding to cell 2 is RB2. After the terminal device switches from cell 2 to cell 3, network device 3 transmits data of RB2 to the terminal device via RB2. Furthermore, the specific manner in which network device 3 determines the source cell for the terminal device's i-th handover can be found in the relevant description of the methods described in FIG. 7 and FIG. 8 , and will not be further described.

[0286] In addition, the specific description of each implementation method in the method described in Figure 10 can refer to the relevant description in the methods described in Figures 7 and 8. The method described in Figure 10 can also include the contents of the methods described in Figures 7 and 8, and also has corresponding beneficial effects, which will not be repeated here.

[0287] To summarize, in this communication method, network device 2 sends the configuration information of RB2 to network device 1. The configuration information of RB2 includes the mapping relationship between QoS flow 1 configured by network device 2 and RB2. Network device 1 sends the configuration information of RB2 to network device 3. Network device 1 receives the configuration information of cell 3 sent by network device 3 in response to the configuration information of RB2. Network device 1 sends the configuration information of cell 3 to the terminal device. The configuration information of cell 3 includes the configuration information of RB3 and indication information 4. RB3 is different from RB2. Indication information 4 is used to instruct the terminal device to configure RB2 for cell 3. Alternatively, the configuration information of cell 3 includes the configuration information of RB3. RB3 is the same as RB2. The configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by network device 3 and RB3. Network device 1 is the network device accessed by the terminal device, and cell 3 is a candidate cell for switching by the terminal device.

[0288] As can be seen, this method allows network device 3 to be configured with RB2 when RB3 and RB2 are different, and the terminal device to be configured with RB2 and RB3. During subsequent handovers or multiple handovers of the terminal device, before switching from network device 2 to network device 3, the terminal device transmits data with network device 2 via RB2. After switching from network device 2 to network device 3, since both the terminal device and network device 3 are configured with RB2, data can be transmitted between the terminal device and network device 3 via RB2. Data that was not successfully transmitted between the terminal device and network device 2 via RB2 is then transferred without loss, thus improving service continuity.

[0289] This method enables the UE to configure RB3 when RB3 is the same as RB2. During subsequent handovers or multiple handovers of the terminal device, before switching from network device 2 to network device 3, the terminal device transmits data with network device 2 via RB2. After switching from network device 2 to network device 3, because RB3 is configured for the terminal device and is the same as RB2, data between the terminal device and network device 3 can be transmitted via RB2. Data that was not successfully transmitted between the terminal device and network device 2 via RB2 can be transferred without loss of data, thus improving service continuity.

[0290] To implement the various functions of the methods provided in the embodiments of the present application, network elements / devices may include hardware structures and / or software modules, and the aforementioned functions may be implemented in the form of hardware structures, software modules, or a combination of hardware structures and software modules. Whether a particular one of the aforementioned functions is implemented 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.

[0291] As shown in Figure 11, an embodiment of the present application provides a communication device 1100. The communication device 1100 can be a network device, or a component of a network device (for example, an integrated circuit, a chip, etc.). The communication device 1100 can also be other communication units for implementing the method in the method embodiment of the present application. The communication device 1100 may include a processing unit 1101. Optionally, the communication device 1100 may also include a communication unit 1102, and the processing unit 1101 is used to control the communication unit 1102 to send and receive data / signaling. The communication unit 1102 may also be referred to as a transceiver unit. Optionally, the communication unit 1102 may include a sending unit and a receiving unit, and the sending unit may be used to send data / signaling, and the receiving unit may be used to receive data / signaling. Optionally, the communication device 1100 may also include a storage unit 1103, and the storage unit 1103 may be used to store information and / or data and / or instructions, etc. The storage unit 1103 may interact with the processing unit 1101, and may also interact with the communication unit 1102.

[0292] In one possible design, for a case where the communication apparatus 1100 is used to implement the functions of the network device 1 in the above method embodiment:

[0293] Communication unit 1102 is used to receive configuration information of RB2 from network device 2, and the configuration information of RB2 includes the mapping relationship between QoS flow 1 configured by network device 2 and RB2. Communication unit 1102 is also used to send the configuration information of RB2 to network device 3. Communication unit 1102 is also used to receive the configuration information of cell 3 sent by network device 3 in response to the configuration information of RB2. Communication unit 1102 is also used to send the configuration information of cell 3 to the terminal device. The configuration information of cell 3 includes the configuration information of RB3 and indication information 4, RB3 is different from RB2, and indication information 4 is used to instruct the terminal device to configure RB2 for cell 3; or, the configuration information of cell 3 includes the configuration information of RB3, and RB3 is the same as RB1; the configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by network device 3 and RB3. Communication device 1100 is the network device accessed by the terminal device, and cell 3 is a candidate cell for switching by the terminal device.

[0294] In an optional implementation, the communication unit 1102 sends the configuration information of RB2 to the network device 3, specifically for: sending the configuration information of RB2 to the network device 3, and when RB2 is the same as RB3, the configuration information of RB2 is used by the network device 3 to determine that RB2 is the same as RB3.

[0295] In an optional implementation, the communication unit 1102 sends the configuration information of RB2 to the network device 3, specifically for: sending the configuration information of RB2 to the network device 3, and when RB2 is different from RB3, the configuration information of RB2 is used by the network device 3 to configure RB2.

[0296] In an optional implementation, the communication unit 1102 is further configured to send a message 1 to the network device 2 , where the message 1 is used to request configuration information of RBs mapped to the QoS flow 1 .

[0297] In an optional embodiment, the communication unit 1102 is further configured to send configuration information of RB1 to the network device 3, where the configuration information of RB1 includes a mapping relationship between QoS flow 1 configured by the communication apparatus 1100 and RB1. The communication unit 1102 receives the configuration information of cell 3 sent by the network device 3 in response to the configuration information of RB2, and is specifically configured to: receive the configuration information of cell 3 sent by the network device 3 in response to the configuration information of RB2 and the configuration information of RB1; if RB1 and RB3 are different, the configuration information of cell 3 further includes indication information 5, where indication information 5 is used to instruct the terminal device to configure RB1 for cell 3.

[0298] In an optional implementation, the communication unit 1102 is further configured to send indication information 1 to the network device 3 , where the indication information 1 is configured to instruct the network device 3 to cooperate in performing data lossless switching, where the data lossless switching includes providing configuration information of the cell 3 .

[0299] In an optional embodiment, communication unit 1102 is further configured to receive user plane tunnel address information allocated by network device 3 to RB2, which is sent by network device 3. Communication unit 1102 is further configured to send user plane tunnel address information allocated by network device 3 to RB2 to network device 2. The user plane tunnel address information is used by network device 2 to forward data of RB2 to network device 3.

[0300] In an optional embodiment, communication device 1100 is the source network device for the first switching of the terminal device, network device 2 is the source network device for the i-th switching of the terminal device, and network device 3 is the target network device for the i-th switching of the terminal device, where i is an integer greater than 1.

[0301] In another possible design, for the case where the communication device 1100 is used to implement the functions of the network device 3 in the above method embodiment:

[0302] Communication unit 1102 is used to receive configuration information of RB2 from network device 1. The configuration information of RB2 includes the mapping relationship between QoS flow 1 configured by network device 2 and RB2. Communication unit 1102 is also used to respond to the configuration information of RB2 and send configuration information of cell 3 to network device 1. The configuration information of cell 3 includes configuration information of RB3 and indication information 4. RB3 is different from RB2. Indication information 4 is used to instruct the terminal device to configure RB2 for cell 3. Alternatively, the configuration information of cell 3 includes configuration information of RB3. RB3 is the same as RB2. The configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by network device 3 and RB3. Network device 1 is the network device accessed by the terminal device, and cell 3 is a candidate cell for the terminal device to switch.

[0303] In an optional implementation, the processing unit 1101 is configured to determine, based on the configuration information of RB2, that RB2 is the same as RB3.

[0304] In an optional implementation, the processing unit 1101 is configured to configure RB2 based on the configuration information of RB2 when RB2 is different from RB3.

[0305] In an optional embodiment, the communication unit 1102 is further configured to receive configuration information of RB1 from the network device 1, where the configuration information of RB1 includes a mapping relationship between QoS flow 1 configured by the network device 1 and RB1. The communication unit 1102 sends configuration information of cell 3 to the network device 1 in response to the configuration information of RB2, and is specifically configured to: send the configuration information of cell 3 to the network device 1 in response to the configuration information of RB2 and the configuration information of RB1; if RB1 and RB3 are different, the configuration information of cell 3 further includes indication information 5, where indication information 5 is used to instruct the terminal device to configure RB1 for cell 3.

[0306] In an optional implementation, the communication unit 1102 is further configured to receive indication information 1 from the network device 1 , where the indication information 1 is configured to instruct the network device 3 to cooperate in performing lossless data switching, where the lossless data switching includes providing configuration information of the cell 3 .

[0307] In an optional implementation, the communication unit 1102 is further configured to send to the network device 1: user plane tunnel address information allocated by the communication apparatus 1100 to RB2, where the user plane tunnel address information is used by the network device 2 to forward the data of RB2 to the network device 3.

[0308] In an optional embodiment, communication unit 1102 is further configured to receive an identifier of cell 2 from network device 2 or terminal device; network device 3 determines that the RB corresponding to cell 2 is RB2. Communication unit 1102 is further configured to transmit data of RB2 to the terminal device via RB2 after the terminal device switches from cell 2 to cell 3.

[0309] In an optional embodiment, network device 1 is the source network device for the first switching of the terminal device, network device 2 is the source network device for the i-th switching of the terminal device, and communication device 1100 is the target network device for the i-th switching of the terminal device, where i is an integer greater than 1.

[0310] The embodiments of the present application and the method embodiments shown above are based on the same concept, and the technical effects they bring are also the same. For the specific principles, please refer to the description of the embodiments shown above, and no further details will be given.

[0311] The present application also provides a communication device 1200, as shown in Figure 12. Communication device 1200 can be a network device, or a chip, chip system, or processor that supports the network device in implementing the above method. This device can be used to implement the method described in the above method embodiment. For details, please refer to the description of the above method embodiment.

[0312] The communication device 1200 may include one or more processors 1201. The processor 1201 may be used to implement some or all of the functions of the network device through logic circuits or running computer programs. The processor 1201 may be a general-purpose processor or a dedicated processor. For example, it may be a baseband processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or a CPU. The baseband processor may be used to process communication protocols and communication data, and the central processing unit may be used to control the communication device, execute software programs, and process data of 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).

[0313] Optionally, the communication device 1200 may include one or more memories 1202, on which instructions 1204 may be stored. The instructions may be executed on the processor 1201, causing the communication device 1200 to perform the method described in the above method embodiment. Optionally, the memory 1202 may also store data. The processor 1201 and the memory 1202 may be provided separately or integrated together.

[0314] The memory 1202 may include, but is not limited to, non-volatile memory such as a hard disk drive (HDD) or a solid-state drive (SSD), random access memory (RAM), erasable programmable ROM (EPROM), ROM or compact disc read-only memory (CD-ROM), etc.

[0315] Optionally, the communication device 1200 may further include a transceiver 1205 and an antenna 1206. The transceiver 1205 may be referred to as a transceiver unit, a transceiver, or a transceiver circuit, etc., and is configured to implement transceiver functions. The transceiver 1205 may include a receiver and a transmitter. The receiver may be referred to as a receiver or a receiving circuit, etc., and is configured to implement a receiving function; the transmitter may be referred to as a transmitter or a transmitting circuit, etc., and is configured to implement a transmitting function.

[0316] In one possible design, for a case where the communication apparatus 1200 is used to implement the functions of the network device 1 in the above method embodiment:

[0317] Transceiver 1205 is used to receive the configuration information of RB2 from network device 2. The configuration information of RB2 includes the mapping relationship between QoS flow 1 configured by network device 2 and RB2. Transceiver 1205 is also used to send the configuration information of RB2 to network device 3. Transceiver 1205 is also used to receive the configuration information of cell 3 sent by network device 3 in response to the configuration information of RB2. Transceiver 1205 is also used to send the configuration information of cell 3 to the terminal device. The configuration information of cell 3 includes the configuration information of RB3 and indication information 4. RB3 is different from RB2. Indication information 4 is used to instruct the terminal device to configure RB2 for cell 3; or, the configuration information of cell 3 includes the configuration information of RB3. RB3 is the same as RB1. The configuration information of RB3 includes the mapping relationship between QoS flow 1 configured by network device 3 and RB3. The communication device 1200 is the network device accessed by the terminal device, and cell 3 is a candidate cell for switching by the terminal device.

[0318] In another possible design, for the case where the communication device 1200 is used to implement the functions of the network device 3 in the above method embodiment:

[0319] Transceiver 1205 is configured to receive configuration information for RB2 from network device 1. The configuration information for RB2 includes a mapping relationship between QoS flow 1 configured by network device 2 and RB2. Transceiver 1205 is further configured to respond to the configuration information for RB2 and send configuration information for cell 3 to network device 1. The configuration information for cell 3 includes configuration information for RB3 and indication information 4. RB3 is different from RB2. Indication information 4 is used to instruct the terminal device to configure RB2 for cell 3. Alternatively, the configuration information for cell 3 includes configuration information for RB3. RB3 is the same as RB2. The configuration information for RB3 includes a mapping relationship between QoS flow 1 configured by network device 3 and RB3. Network device 1 is the network device accessed by the terminal device, and cell 3 is a candidate cell for handover by the terminal device.

[0320] In another possible design, processor 1201 may include a transceiver for implementing receiving and transmitting 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 the receiving and transmitting functions may be separate or integrated. The transceiver circuit, interface, or interface circuit may be used for reading and writing code / data, or the transceiver circuit, interface, or interface circuit may be used for transmitting or delivering signals.

[0321] In another possible design, processor 1201 may optionally store instructions 1203. Instructions 1203, when executed on processor 1201, may cause communication device 1200 to perform the method described in the above method embodiment. Instructions 1203 may be fixed in processor 1201. In this case, processor 1201 may be implemented by hardware.

[0322] In another possible design, the communication device 1200 may include a circuit that can implement the functions of sending, receiving, or communicating in the aforementioned method embodiments. The processor and transceiver described in the embodiments of the present application can be implemented in an integrated circuit (IC), an analog IC, a radio frequency integrated circuit (RFIC), a mixed signal IC, an application specific integrated circuit (ASIC), a printed circuit board (PCB), an electronic device, etc. The processor and transceiver can also be manufactured using various IC process technologies, such as complementary metal oxide semiconductor (CMOS), N-type metal oxide semiconductor (nMetal-oxide-semiconductor, NMOS), P-type metal oxide semiconductor (positive channel metal oxide semiconductor, PMOS), bipolar junction transistor (bipolar junction transistor, BJT), bipolar CMOS (BiCMOS), silicon germanium (SiGe), gallium arsenide (GaAs), etc.

[0323] Those skilled in the art will also appreciate that the various illustrative logical blocks and steps listed in the embodiments of the present application can be implemented by electronic hardware, computer software, or a combination of both. Whether such functions are implemented by hardware or software depends on the specific application and the design requirements of the entire system. Those skilled in the art may use various methods to implement the described functions for specific applications, but such implementations should not be construed as exceeding the scope of protection of the embodiments of the present application.

[0324] The embodiments of the present application and the above-mentioned method embodiments are based on the same concept, and the technical effects they bring are also the same. For the specific principles, please refer to the description in the above-mentioned method embodiments, and no further details will be given.

[0325] The present application also provides a computer-readable storage medium for storing computer software instructions, which, when executed by a communication device, implements the functions of any of the above method embodiments.

[0326] The present application also provides a computer program product for storing computer software instructions, which, when executed by a communication device, implements the functions of any of the above method embodiments.

[0327] The present application also provides a computer program that, when executed on a computer, implements the functions of any of the above method embodiments.

[0328] The present application also provides a chip including a processor. The processor is configured to execute code or instructions to implement the functions of any of the above method embodiments. Optionally, the chip also includes an interface, the processor being coupled to the interface, and the interface being configured to receive or output signals.

[0329] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments may be implemented in the form of 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 the present application are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium may be any available medium accessible by a computer or a data storage device such as a server or data center that includes one or more available media integrated therein. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a high-density digital video disc (DVD)), or a semiconductor medium (eg, an SSD).

[0330] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

[0331] In addition, in this application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other, and the technical features in different embodiments can be combined to form new embodiments according to their internal logical relationships.

[0332] It can be understood that some optional features in the embodiments of the present application may not depend on other features in certain scenarios, and may also be combined with other features in certain scenarios, without limitation.

[0333] It can be understood that the solutions in the embodiments of this application can be used in combination, and the explanations or descriptions of each term, similar operations or steps appearing in the embodiments can be referenced or explained with each other in each embodiment, and this application does not limit this.

[0334] In this application, "at least one" means one or more, and "more" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. In the text description of this application, the character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" or similar expressions refers 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 represent: a, or b, or c, or a and b, or a and c, or b and c, or a, b and c. Wherein a, b and c can be single or multiple, respectively.

[0335] Throughout this application, the terms "first," "second," and various numerical references are used for ease of description and are not intended to limit the scope of the embodiments of this application. For example, they are used to distinguish between different messages, rather than to describe a specific order or precedence. It should be understood that such references are interchangeable, where appropriate, to allow for the description of scenarios beyond the embodiments of this application.

[0336] In this application, the terms "comprises" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product or apparatus.

[0337] In this application, "used to indicate" may include direct indication and indirect indication. When describing that a certain indication information is used to indicate A, it may include that the indication information directly indicates A or indirectly indicates A, but it does not mean that the indication information must carry A.

[0338] In this application, "sending information to XX (device / network element)" can be understood as the destination of the information being the device / network element. This can include sending information directly or indirectly to the 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 the device / network element. This can include receiving information directly or indirectly from the device / network element. The information may undergo necessary processing between the source and destination, such as format changes, but the destination can still understand the valid information from the source.

[0339] In this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner to facilitate understanding.

Claims

1. A communication method, characterized in that: The method comprises: The first network device receives configuration information of a first radio bearer (RB) from the second network device, where the configuration information of the first RB includes a mapping relationship between a first quality of service (QoS) flow configured by the second network device and the first RB; The first network device sends the configuration information of the first RB to the third network device; The first network device receives configuration information of a first candidate cell sent by the third network device in response to configuration information of the first RB; The first network device sends configuration information of the first candidate cell to the terminal device; The configuration information of the first candidate cell includes configuration information of a second RB and first indication information, the second RB is different from the first RB, and the first indication information is used to instruct the terminal device to configure the first RB for the first candidate cell; or the configuration information of the first candidate cell includes configuration information of a second RB, and the second RB is the same as the first RB; The configuration information of the second RB includes a mapping relationship between the first QoS flow configured by the third network device and the second RB.

2. The method according to claim 1, characterized in that The first network device sending configuration information of the first RB to the third network device includes: The first network device sends configuration information of the first RB to the third network device, and when the first RB is the same as the second RB, the configuration information of the first RB is used by the third network device to determine that the first RB is the same as the second RB.

3. The method according to claim 1, characterized in that The first network device sending configuration information of the first RB to the third network device includes: The first network device sends configuration information of the first RB to the third network device, and when the first RB is different from the second RB, the configuration information of the first RB is used by the third network device to configure the first RB.

4. The method according to any one of claims 1 to 3, characterized in that The method further comprises: The first network device sends a first message to the second network device, where the first message is used to request configuration information of RBs mapped to the first QoS flow.

5. The method according to any one of claims 1 to 4, characterized in that The method further comprises: The first network device sends configuration information of a third RB to the third network device, where the configuration information of the third RB includes a mapping relationship between the first QoS flow configured by the first network device and the third RB; The step of receiving, by the first network device, the configuration information of the first candidate cell sent by the third network device in response to the configuration information of the first RB includes: receiving, by the first network device, the configuration information of the first candidate cell sent by the third network device in response to the configuration information of the first RB and the configuration information of the third RB; In a case where the third RB is different from the second RB, the configuration information of the first candidate cell further includes second indication information, where the second indication information is used to instruct the terminal device to configure the third RB for the first candidate cell.

6. The method according to any one of claims 1 to 5, characterized in that The method further comprises: The first network device sends third indication information to the third network device, where the third indication information is used to instruct the third network device to cooperate in data lossless switching, where the data lossless switching includes providing configuration information of the first candidate cell.

7. The method according to any one of claims 1 to 6, characterized in that The method further comprises: The first network device receives first user plane tunnel address information from the third network device, where the first user plane tunnel address information is user plane tunnel address information allocated by the third network device to the first RB; The first network device sends the first user plane tunnel address information to the second network device; The first user plane tunnel address information is used by the second network device to forward the data of the first RB to the third network device.

8. The method according to any one of claims 1 to 7, characterized in that The first network device is the source network device for the first switching of the terminal device, the second network device is the source network device for the i-th switching of the terminal device, and the third network device is the target network device for the i-th switching of the terminal device, where i is an integer greater than 1.

9. A communication method, characterized in that: The method comprises: The third network device receives configuration information of a first radio bearer RB from the first network device, where the configuration information of the first RB includes a mapping relationship between a first quality of service QoS flow configured by the second network device and the first RB; The third network device sends the configuration information of the first candidate cell to the first network device in response to the configuration information of the first RB; The configuration information of the first candidate cell includes configuration information of a second RB and first indication information, where the second RB is different from the first RB, and the first indication information is used to instruct the terminal device to configure the first RB for the first candidate cell; or, the configuration information of the first candidate cell includes configuration information of a second RB, where the second RB is the same as the first RB; The configuration information of the second RB includes a mapping relationship between the first QoS flow configured by the third network device and the second RB.

10. The method according to claim 9, characterized in that The method further comprises: The third network device determines, based on the configuration information of the first RB, that the first RB is the same as the second RB.

11. The method according to claim 9, characterized in that The method further comprises: When the first RB is different from the second RB, the third network device configures the first RB based on the configuration information of the first RB.

12. The method according to any one of claims 9 to 11, characterized in that The method further comprises: The third network device receives configuration information of a third RB from the first network device, where the configuration information of the third RB includes a mapping relationship between the first QoS flow configured by the first network device and the third RB; The third network device sending the configuration information of the first candidate cell to the first network device in response to the configuration information of the first RB, including: the third network device sending the configuration information of the first candidate cell to the first network device in response to the configuration information of the first RB and the configuration information of the third RB; In a case where the third RB is different from the second RB, the configuration information of the first candidate cell further includes second indication information, where the second indication information is used to instruct the terminal device to configure the third RB for the first candidate cell.

13. The method according to any one of claims 9 to 12, characterized in that The method further comprises: The third network device receives third indication information from the first network device, where the third indication information is used to instruct the third network device to cooperate in data lossless switching, where the data lossless switching includes providing configuration information of the first candidate cell.

14. The method according to any one of claims 9 to 13, characterized in that The method further comprises: The third network device sends first user plane tunnel address information to the first network device, where the first user plane tunnel address information is user plane tunnel address information allocated by the third network device to the first RB; The first user plane tunnel address information is used by the second network device to forward the data of the first RB to the third network device.

15. The method according to any one of claims 9 to 14, characterized in that The method further comprises: The third network device receives an identifier of the first cell from the second network device or the terminal device; Determining, by the third network device, that the RB corresponding to the first cell is the first RB; After the terminal device switches from the first cell to the second cell, the third network device transmits the data of the first RB to the terminal device through the first RB, and the second cell is the first candidate cell.

16. The method according to any one of claims 9 to 15, characterized in that The first network device is the source network device for the first switching of the terminal device, the second network device is the source network device for the i-th switching of the terminal device, and the third network device is the target network device for the i-th switching of the terminal device, where i is an integer greater than 1.

17. A communication device, characterized in that: The apparatus includes a module or unit for implementing the method according to any one of claims 1 to 8, or includes a module or unit for implementing the method according to any one of claims 9 to 16.

18. A communication device, characterized in that: Including processor; The processor is configured to execute a computer program or instruction to enable the communication device to perform the method according to any one of claims 1 to 8, or to perform the method according to any one of claims 9 to 16.

19. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed, the method according to any one of claims 1 to 8 or the method according to any one of claims 9 to 16 is implemented.

20. A computer program product, comprising: Computer program code, when the computer program code is run, implements the method according to any one of claims 1 to 8, or implements the method according to any one of claims 9 to 16.

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