Communication method and apparatus

Abstract

A communication method and a communication device are provided, the method including: receiving a first configuration from an access network device, the first configuration including a first reference configuration and a delta configuration of a target cell, the first reference configuration being related to the delta configuration of the target cell; and determining a radio configuration of a terminal device based on the first reference configuration and the delta configuration of the target cell. According to the method and device of the present application, the terminal device can accurately apply the configuration of the target cell, thereby improving handover efficiency.

Description

[Technical Field]

[0001] TECHNICAL FIELD Embodiments of the present application relate to the field of communication technologies, and in particular to communication methods and devices. [Background technology]

[0002] Mobility management enables a terminal to use network services regardless of how the terminal moves within a network coverage area by changing the terminal's serving cell. Mobility in a connected state is achieved through cell handover. In a wireless communication system, when a terminal moves from one cell to another while the terminal is in a service connected state and the service serving is maintained, a handover must be performed to ensure communication continuity for the terminal.

[0003] Currently, in the 5th generation (5G) radio access network (RAN) architecture, access network devices are expected to adopt an independent deployment of centralized units (CU) and distributed units (DU) to better meet the requirements of various scenarios and applications. In the CU-DU separated base station deployment, the 5G system is expected to adopt lower layer triggered handover to reduce handover delays and further improve service continuity.

[0004] In a handover process in which a terminal is handed over from a source cell to a target cell, how the terminal determines the configuration of the target cell is a research direction. Summary of the Invention [Means for solving the problem]

[0005] SUMMARY OF THE INVENTION Embodiments of the present application provide a communication method and apparatus for improving the performance of a terminal device during cell handover.

[0006] According to a first aspect, there is provided a communication method. The method is applied to a terminal and is executed by a terminal device. The terminal device may be a terminal or a chip, circuit, etc. used in the terminal. The method includes: receiving a first configuration from an access network device, the first configuration including a first reference configuration and a delta configuration of a target cell, the first reference configuration being related to the delta configuration of the target cell; and determining a radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell.

[0007] According to the above design, if the configuration of the target cell is a delta configuration based on the current handover design, the terminal device directly applies the delta configuration of the target cell based on the configuration of the source cell. The determined configuration of the target cell is inaccurate, resulting in a handover failure. Furthermore, if the terminal device does not apply the configuration of the target cell based on the current handover design, it is unclear how the terminal applies the configuration of the target cell, which also causes a handover failure. In this embodiment of the present application, the delta configuration of the target cell is applied based on the first reference configuration. The terminal device determines the configuration of the target cell based on the first reference configuration and the delta configuration of the target cell. The configuration of the target cell determined by the terminal device is accurate. Therefore, the determined radio configuration of the terminal in the target cell is also accurate, thereby improving the handover success rate.

[0008] In one embodiment, the method further includes a step of releasing current configuration information of the terminal device excluding at least one of the master cell group MCG cell radio network temporary identifier C-RNTI, the access stratum security configuration, the radio bearer RB configuration, the radio link control RLC bearer configuration, the secondary cell SCell configuration, or the recorded measurement configuration.

[0009] According to the above design, when the reference configuration is applied, the aforementioned configurations, such as the radio bearer configuration, the RLC bearer configuration in the cell group, or the secondary cell configuration, do not need to be released first. Subsequently, after the delta configuration of the target cell is applied, the aforementioned configurations included in the source cell but not the target cell are released. This reduces handover interruptions and delays, improves handover efficiency and performance, and ensures service continuity.

[0010] In one embodiment, the step of determining the radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell includes the steps of: if the first variable includes the radio configuration of the first reference configuration, updating the first variable based on the delta configuration of the target cell, wherein the updated first variable includes the radio configuration of the target cell; and determining a radio configuration of the terminal device based on the radio configuration in the updated first variable.

[0011] In one embodiment, the step of updating the first variable based on the delta configuration of the target cell includes at least one of the following steps: updating the first radio configuration in the first variable to the second radio configuration if the first variable includes the first radio configuration, the first list includes the second radio configuration, the first list is a list in the delta configuration of the target cell, and an identifier of the first radio configuration is the same as an identifier of the second radio configuration; adding the third radio configuration to the first variable if the first list includes the third radio configuration and the first variable includes a radio configuration other than the third radio configuration; or releasing the fourth radio configuration in the first variable if the first variable includes a fourth radio configuration, the second list includes a fifth radio configuration, the second list is a list in the delta configuration of the target cell, and an identifier of the fourth radio configuration is the same as the identifier of the fifth radio configuration.

[0012] In one embodiment, the step of determining the radio configuration of the terminal device based on the radio configuration in the updated first variable includes at least one of the following steps: reconfiguring the seventh radio configuration based on the sixth radio configuration if the updated first variable includes the sixth radio configuration, and the radio configuration of the source cell includes the seventh radio configuration, and the identifier of the sixth radio configuration is the same as the identifier of the seventh radio configuration; creating the eighth radio configuration in the radio configuration of the terminal device if the updated first variable includes the eighth radio configuration and the radio configuration of the source cell includes a configuration other than the eighth radio configuration; or releasing the ninth radio configuration in the radio configuration of the terminal device if the radio configuration of the source cell includes the ninth radio configuration and the updated first variable includes a configuration other than the ninth radio configuration.

[0013] According to the above design, for a radio configuration in the target cell configuration that has the same identifier as the source cell configuration, the "first release, then create" method is not used, and the source cell configuration is reconfigured or updated based on the target cell configuration, thereby improving handover efficiency and reducing handover delay.

[0014] In one embodiment, the method further includes releasing current cell group configuration information of the terminal device in the cell group configuration except for at least one of the MCG C-RNTI or the RLC bearer configuration.

[0015] According to the above design, when the reference configuration is applied, the configuration that affects service continuity within the master cell group does not need to be released first. After the delta configuration of the target cell is applied, the configuration that is included in the source cell but not the target cell is released. This reduces handover interruptions and delays, improves handover efficiency and performance, and ensures service continuity.

[0016] In one embodiment, the step of determining the radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell includes the steps of determining a second reference configuration based on the radio configuration in the first reference configuration, and determining the radio configuration of the terminal device based on the second reference configuration and the delta configuration of the target cell.

[0017] According to the above design, if the target cell configuration is a delta configuration based on the current handover design, the terminal device directly applies the delta configuration of the target cell based on the configuration of the source cell. The determined configuration of the target cell is inaccurate, resulting in a handover failure. Alternatively, if the terminal device does not apply the target cell configuration based on the current handover design, it is unclear how the terminal applies the configuration of the cell in the LTM, which also results in a handover failure. In this embodiment of the present application, the delta configuration of the target cell is applied based on a second reference configuration determined based on a first reference configuration. The terminal device determines the target cell configuration based on the first reference configuration and the delta configuration of the target cell. The target cell configuration determined by the terminal device is accurate. Therefore, the determined radio configuration of the terminal in the target cell is also accurate, thereby improving the handover success rate.

[0018] In one embodiment, determining the second reference configuration based on the radio configurations in the first reference configuration includes at least one of: updating the eleventh radio configuration of the terminal device to the tenth radio configuration if the first reference configuration includes the tenth radio configuration, the radio configuration of the source cell includes the eleventh radio configuration, and an identifier of the tenth radio configuration is the same as the identifier of the eleventh radio configuration; or creating a twelfth radio configuration if the first reference configuration includes the twelfth radio configuration and the radio configuration of the source cell includes a radio configuration other than the twelfth radio configuration, and the second reference configuration includes at least the tenth radio configuration and the twelfth radio configuration. Optionally, the second reference configuration further includes another radio configuration other than the eleventh radio configuration in the current radio configuration of the terminal.

[0019] In one embodiment, when the first reference configuration includes a tenth radio configuration, and the radio configuration of the source cell includes an eleventh radio configuration, and an identifier of the tenth radio configuration is the same as an identifier of the eleventh radio configuration, the method includes: Deleting the identifier of the eleventh radio configuration from the radio configuration identifier of the source cell, which is included in the second variable. Further includes:

[0020] In one embodiment, the step of determining the radio configuration of the terminal device based on the second reference configuration and the delta configuration of the target cell includes: if the second reference configuration of the terminal device includes the thirteenth radio configuration, and the first reference configuration includes the fourteenth radio configuration, and the third list includes the fifteenth radio configuration, and the third list is a list in the delta configuration of the target cell, and the thirteenth radio configuration, the fourteenth radio configuration, and the fifteenth radio configuration have the same identifier, reconfiguring the thirteenth radio configuration of the terminal device based on the fifteenth radio configuration; if the third list includes the sixteenth radio configuration, and the third list is a list in the delta configuration of the target cell, and the second reference configuration and the first reference configuration include a configuration other than the sixteenth radio configuration, reconfiguring the sixteenth radio configuration of the terminal device based on the sixteenth radio configuration. the fourth list includes at least one of the following steps: creating a list of the 17th radio configuration based on the 17th radio configuration; updating the 18th radio configuration based on the 17th radio configuration if the third list includes the 17th radio configuration, the third list is a list in the delta configuration of the target cell, the first reference configuration includes a configuration other than the 17th radio configuration, the second reference configuration includes the 18th radio configuration, and an identifier of the 17th radio configuration is the same as the identifier of the 18th radio configuration; or releasing the 20th radio configuration in the radio configuration of the terminal device if the fourth list includes the 19th radio configuration, the fourth list is a list in the delta configuration of the target cell, the second reference configuration includes the 20th radio configuration, and an identifier of the 19th radio configuration is the same as the identifier of the 20th radio configuration.

[0021] In one embodiment, when the third list includes the 17th radio configuration, and the third list is a list within the delta configuration of the target cell, and the first reference configuration includes a configuration other than the 17th radio configuration, and the second reference configuration includes the 18th radio configuration, and the identifier of the 17th radio configuration is the same as the identifier of the 18th radio configuration, the method further includes a step of deleting the identifier of the 17th radio configuration from the radio configuration identifier of the source cell included in the second variable.

[0022] In one embodiment, the method further comprises releasing, in the radio configuration of the terminal device, a radio configuration corresponding to the radio configuration identifier included in the second variable.

[0023] According to the above design, configurations that affect service continuity, e.g., RLC bearers, may not be released first in the handover process. After the reference configuration and the delta configuration of the target cell are applied, configurations included in the source cell but not in the target cell are released. This reduces handover interruptions and handover delays, improves handover efficiency and performance, and ensures service continuity. In one embodiment, before determining the radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell, the method further includes receiving a handover command from the access network device or satisfying a handover condition by the terminal device.

[0024] In one design, determining a radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell includes generating a configuration of the target cell based on the first reference configuration and the delta configuration of the target cell, and replacing the radio configuration of the terminal device with a radio configuration in the configuration of the target cell. Optionally, generating the configuration of the target cell includes, if the sixth variable includes the first reference configuration, reconfiguring a sixth variable based on the delta configuration of the target cell, where the reconfigured sixth variable is the generated configuration of the target cell.

[0025] According to the above design, a method is provided for generating a target cell configuration by a terminal. For a radio configuration, such as an RLC bearer configuration, an RB configuration, or a secondary cell configuration, when an LTM handover is performed, if the radio configuration included in the source cell configuration and the radio configuration included in the target cell configuration have the same identifier, the radio configuration in the source cell configuration may be replaced with the radio configuration in the target cell radio configuration. In this way, unnecessary processes of releasing and adding radio configurations may be avoided, handover interruptions and handover delays may be reduced, handover efficiency and performance may be improved, and service continuity may be guaranteed.

[0026] In one design, the method further includes retaining, by the terminal device, current measurement results if the measurement configuration in the target cell's configuration is the same as the measurement configuration in the terminal device's configuration.

[0027] The measurement configuration of the terminal may remain unchanged before and after the LTM handover. According to the above design, unnecessary release or clearing of measurement results when the terminal applies the configuration of the target cell during the LTM may be avoided, thereby reducing the measurement power consumption of the terminal and improving handover performance.

[0028] In one design, before determining the radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell, the method further includes a step of receiving a handover command from the access network device or a step of satisfying a handover condition by the terminal device.

[0029] In one embodiment, the radio configuration of the terminal device includes at least one of a radio bearer RB configuration, a radio link control RLC bearer configuration, or a secondary cell configuration.

[0030] According to a second aspect, there is provided a communication method, which is applied to an access network device and may be executed by the access network device or a circuit, chip, or the like within the access network device. The method includes: generating a first configuration, the first configuration including a reference configuration and a delta configuration of a target cell, the reference configuration being related to the delta configuration of the target cell, and the delta configuration of the target cell and the reference configuration being for determining a radio configuration of a terminal device; and transmitting the first configuration to the terminal device.

[0031] In one embodiment, the radio configuration of the terminal device includes at least one of a radio bearer RB configuration, a radio link control RLC bearer configuration, or a secondary cell configuration.

[0032] In one embodiment, the method further includes sending a handover command to the terminal device after sending the first configuration to the terminal device.

[0033] According to a third aspect, there is provided an apparatus, the apparatus comprising corresponding units or modules for performing the method according to the first or second aspect, the units or modules may be realized by hardware circuits, by software, or by a combination of hardware circuits and software.

[0034] According to a fourth aspect, there is provided an apparatus, the apparatus including a processor and an interface circuit, the processor configured to communicate with another apparatus via the interface circuit and to perform a method according to the first or second aspect, and there may be one or more processors.

[0035] According to a fifth aspect, there is provided an apparatus, the apparatus including a processor coupled to a memory. The processor is configured to execute a program stored in the memory to perform a method according to the first or second aspect. The memory may be located internal or external to the apparatus. Additionally, there may be one or more processors.

[0036] According to a sixth aspect, there is provided an apparatus, the apparatus including a processor and a memory, the memory configured to store computer instructions, and when the apparatus operates, the processor executes the computer instructions stored in the memory to enable the apparatus to perform a method according to the first or second aspect.

[0037] According to a seventh aspect, there is provided a chip system, the chip system including a processor or circuitry and configured to perform a method according to the first or second aspect.

[0038] According to an eighth aspect, there is provided a computer-readable storage medium having instructions stored thereon that, when executed in a communications device, perform a method according to the first or second aspect.

[0039] According to a ninth aspect, there is provided a computer program product, the computer program product comprising a computer program or instructions which, when executed by an apparatus, perform a method according to the first or second aspect.

[0040] According to a tenth aspect, there is provided a system, the system comprising an apparatus for performing the method according to the first aspect and an apparatus for performing the method according to the second aspect. [Brief explanation of the drawings]

[0041] [Figure 1] 1 is a diagram of a communication system according to an embodiment of the present application; [Figure 2]2 is a flowchart of an L1 / L2 handover according to an embodiment of the present application; [Figure 3] 1 is another flowchart of L1 / L2 handover according to an embodiment of the present application; [Figure 4] 1 is a flowchart of a communication method according to an embodiment of the present application. [Figure 5] 1 is a diagram of the structure of an apparatus according to an embodiment of the present application; [Figure 6] FIG. 2 is another diagram of the structure of the device according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0042] 1 is an architecture diagram of a communication system 1000 to which the present application is applicable. As shown in FIG. 1, the communication system 1000 includes a radio access network 100 and a core network 200. Optionally, the communication system 1000 may further include the Internet 300.

[0043] The wireless access network 100 may include at least one access network device (e.g., 100a and 110b in FIG. 1 ) and may further include at least one terminal (e.g., 120a to 120j in FIG. 1 ). The terminal is connected to the access network device wirelessly, and the access network device is connected to the core network wirelessly or wired. The core network device and the access network device may be separate physical devices, or the core network device's functionality and the access network device's logical functionality may be integrated into the same physical device, or some of the core network device's functionality and some of the access network device's functionality may be integrated into one physical device. The terminals may be connected to each other in a wired or wireless manner, and the access network devices may be connected to each other in a wired or wireless manner. FIG. 1 is merely a diagram. The communication system 1000 may further include other network devices, such as wireless relay devices and wireless backhaul devices not shown in FIG. 1 .

[0044] The access network device may be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next-generation NodeB (gNB) in a fifth-generation (5G) mobile communication system, an access network device in an open radio access network (O-RAN), a next-generation base station in a sixth-generation (6G) mobile communication system, an access node in a wireless fidelity (WiFi) system, or the like, or may be a module or unit performing part of the functions of a base station, such as a central unit (CU), a distributed unit (DU), a centralized unit control plane (CU-CP) module, or a centralized unit user plane (CU-UP) module. The access network device may be a macro base station (e.g., 110a in FIG. 1), a micro base station, or an indoor base station (e.g., 110b in FIG. 1), or may be a relay node, a donor node, or the like. The specific technology used by the access network devices and the specific device configuration are not limited by this application.

[0045] In the present application, an apparatus configured to realize the functions of an access network device may be an access network device, or may be an apparatus that can assist an access network device to realize functions, such as a chip system, a hardware circuit, a software module, or a combination of a hardware circuit and a software module. The apparatus may be installed in an access network device or may be combined with an access network device for use. In the present application, a chip system may include a chip, or may include a chip and another individual component. For ease of description, the following will describe the technical solutions provided in the present application by using an example in which the apparatus configured to realize the functions of an access network device is an access network device.

[0046] (1) Protocol layer structure Communications between the access network device and the terminal conform to a specific protocol layer structure. The protocol layer structure may include a control plane protocol layer structure and a user plane protocol layer structure. For example, the control plane protocol layer structure may include protocol layer functions such as a radio resource control (RRC) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, a media access control (MAC) layer, and a physical layer. For example, the user plane protocol layer structure may include protocol layer functions such as a PDCP layer, an RLC layer, a MAC layer, and a physical layer. In one possible embodiment, a service data adaptation protocol (SDAP) layer may be further included above the PDCP layer.

[0047] (2) Central unit (CU) and distributed unit (DU) An access network device may include a CU and a DU. Multiple DUs may be centrally controlled by one CU. For example, the interface between a CU and a DU may be called an F1 interface. A control plane (CP) interface may be F1-C, and a user plane (UP) interface may be F1-U. The specific names of each interface are not limited in this application. The CU and the DU may be divided based on the protocol layer of the wireless network. For example, the functions of the PDCP layer and the functions of the protocol layers above the PDCP layer are configured on the CU, and the functions of the protocol layers below the PDCP layer (e.g., the RLC layer and the MAC layer) are configured on the DU. As another example, the functions of the protocol layers above the PDCP layer are configured on the CU, and the functions of the PDCP layer and the functions of the protocol layers below the PDCP layer are configured on the DU. This is not a limitation.

[0048] The division of the processing functions of the CU and the DU based on the protocol layer is merely an example, and other division schemes may be used. For example, the CU or DU may have more protocol layer functions. As another example, the CU or DU may have some protocol layer processing functions. In one embodiment, some of the RLC layer functions and functions of protocol layers above the RLC layer are configured on the CU, and the remaining RLC layer functions and functions of protocol layers below the RLC layer are configured on the DU. In another embodiment, the division of the CU or DU functions may alternatively be based on service type or other system requirements. For example, the division may be based on latency. Functions whose processing time must meet latency requirements are configured on the DU, and functions whose processing time does not need to meet latency requirements are configured on the CU. In another design, the CU may alternatively have one or more functions of the core network. For example, the CU may be located on the network side to facilitate centralized management. In another design, the radio unit (RU) of the DU is remotely located. Optionally, the RU may have radio frequency functionality.

[0049] Optionally, the DU and the RU may be distinguished at the physical layer (PHY). For example, the DU may implement higher layer functions of the PHY layer, and the RU may implement lower layer functions of the PHY layer. When used for transmission, the PHY layer functions may include one or more of cyclic redundancy check (CRC) code addition, channel coding, rate matching, scrambling, modulation, layer mapping, precoding, resource mapping, physical antenna mapping, or radio frequency transmission functions. When used for reception, the PHY layer functions may include one or more of CRC checking, channel decoding, de-rate matching, descrambling, demodulation, layer demapping, channel detection, resource demapping, physical antenna demapping, or radio frequency reception functions. The higher layer functions of the PHY layer may include some functions of the PHY layer. For example, some of these functions are closer to the MAC layer. The lower layer functions of the PHY layer may include some other functions of the PHY layer. For example, some of the functions are closer to the radio frequency functions. For example, the upper layer functions of the PHY layer may include CRC code addition, channel coding, rate matching, scrambling, modulation, and layer mapping, while the lower layer functions of the PHY layer may include precoding, resource mapping, physical antenna mapping, and radio frequency transmission functions. Alternatively, the upper layer functions of the PHY layer may include CRC code addition, channel coding, rate matching, scrambling, modulation, layer mapping, and precoding. The lower layer functions of the PHY layer may include resource mapping, physical antenna mapping, and radio frequency transmission functions. For example, the upper layer functions of the PHY layer may include CRC checking, channel decoding, de-rate matching, decoding, demodulation, and layer demapping, while the lower layer functions of the PHY layer may include channel detection, resource demapping, physical antenna demapping, and radio frequency reception functions.Alternatively, the upper layer functions of the PHY layer may include CRC checking, channel decoding, de-rate matching, decoding, demodulation, layer demapping, and channel detection, and the lower layer functions of the PHY layer may include resource demapping, physical antenna demapping, and radio frequency receiving functions.

[0050] For example, the functions of the CU may be realized by one entity or by different entities. For example, the functions of the CU may be further divided. Specifically, the control plane and the user plane are separated and realized by different entities, namely, a control plane CU entity (i.e., a CU-CP entity) and a user plane CU entity (i.e., a CU-UP entity). The CU-CP entity and the CU-UP entity may be coupled to the DU to jointly perform the functions of an access network device.

[0051] Optionally, any one of the DU, CU, CU-CP, CU-UP, and RU may be a software module, a hardware structure, or a combination of a software module and a hardware structure. This is not limited thereto. Different entities may exist in different forms. This is not limited thereto. For example, the DU, CU, CU-CP, and CU-UP are software modules, and the RU is a hardware structure. These modules and the methods performed by these modules also fall within the scope of protection of the embodiments of the present application.

[0052] In one possible embodiment, the access network device includes a CU-CP, a CU-UP, a DU, and an RU. For example, the embodiments of the present application may be performed by a DU, or a DU and an RU, or a CU-CP, a DU, and an RU, or a CU-UP, a DU, and an RU. This is not limited thereto. Methods performed by modules also fall within the scope of protection of the embodiments of the present application.

[0053] A terminal may alternatively be referred to as a terminal device, user equipment (UE), mobile station, mobile terminal, etc. A terminal may be widely used for communication in various scenarios including, for example, but not limited to, one or more of the following scenarios: device-to-device (D2D), vehicle-to-everything (V2X), machine-type communication (MTC), internet of things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city, etc. A terminal may be a mobile phone, a tablet computer, a computer with wireless transceiver capability, a wearable device, a vehicle, an unmanned aerial vehicle, a helicopter, an airplane, a ship, a robot, a mechanical arm, a smart home device, etc. The specific technology used by the terminal and the specific device form are not limited by this application.

[0054] In the present application, a device configured to realize the functions of a terminal may be a terminal, or may be a device that can assist a terminal in realizing a function, such as a chip system, a hardware circuit, a software module, or a combination of a hardware circuit and a software module. The device may be installed in a terminal or combined with a terminal for use. For ease of explanation, the following will describe the technical solutions provided in the present application by using an example in which the device configured to realize the functions of a terminal is a terminal.

[0055] The access network devices and terminals may be fixed or mobile. The access network devices and / or terminals may be deployed on land, on water, or on airborne aircraft, balloons, and satellites, including indoor or outdoor and handheld or vehicle-mounted devices. The application scenarios of the access network devices and terminals are not limited in this application. The access network devices and terminals may be deployed in the same scenario or in different scenarios. For example, the access network devices and terminals may both be deployed on land, or the access network devices may be deployed on land and the terminals may be deployed on water. Examples are not provided one by one.

[0056] The roles of an access network device and a terminal may be relative. For example, helicopter or unmanned aerial vehicle 120i in FIG. 1 may be configured as a mobile access network device. For terminal 120j accessing wireless access network 100 via access network device 120i, terminal 120i is an access network device. However, for access network device 110a, 120i is a terminal. Specifically, 110a and 120i communicate with each other according to a wireless air interface protocol. Alternatively, 110a and 120i communicate with each other by using an interface protocol between access network devices. In this case, for access network device 110a, 120i is also an access network device. Therefore, both access network devices and terminals may be collectively referred to as communication devices. 110a and 110b in FIG. 1 may be referred to as communication devices having the functionality of access network devices, and 120a to 120j in FIG. 1 may be referred to as communication devices having the functionality of terminals.

[0057] Communications between access network devices and terminals, between access network devices, or between terminals may occur using licensed spectrum, unlicensed spectrum, or both licensed and unlicensed spectrum, or may occur using spectrum below 6 gigahertz (GHz), above 6 GHz, or both below and above 6 GHz. Spectral resources for wireless communications are not limited in this application.

[0058] The Layer 1 (L1) / Layer 2 (L2) triggered mobility (LTM) process, also known as lower layer triggered mobility, refers to a cell handover of a terminal triggered by L1 / L2 signaling. For example, an access network device transmits L1 / L2 signaling to a terminal, and the L1 / L2 signaling may include information about a target cell, such as a configuration identifier of the target cell. The terminal receives the L1 / L2 signaling from the access network device and is handed over from a source cell to a target cell, where the source cell is the serving cell of the terminal before the handover and the target cell is the serving cell of the terminal after the handover. The L1 / L2 signaling may also be referred to as an L1 / L2 handover command, an L1 / L2 cell handover command, an LTM handover command, or the like, but is not limited thereto. Optionally, according to protocol stack division, L1 includes a PHY layer, L2 includes a MAC layer, an RLC layer, and a PDCP layer, and L3 includes an RRC layer. L1 / L2 signaling may be MAC control element (CE) signaling or downlink control information (DCI). LTM handover can reduce handover delay, thereby reducing service interruption and improving the user experience of the terminal.

[0059] The gist of LTM is as follows: An access network device determines one or more LTM candidate cells and configures the LTM candidate cells for a terminal by using an RRC message; The access network device receives an L1 measurement report from the terminal, selects a target cell from the LTM candidate cells based on the L1 measurement report, and sends an L1 / L2 handover command to the terminal to trigger an LTM cell handover of the terminal.

[0060] In one embodiment, the access network device employs a CU-DU separation architecture. The access network device includes a CU and a DU. Multiple DUs may be centrally controlled by one CU. Each DU is associated with at least one cell. In an embodiment of the present application, when a terminal's serving cell switches from a source cell to a target cell, the source cell and the target cell may belong to different CUs. This is called an inter-CU handover. Alternatively, the source cell and the target cell may belong to the same CU and different DUs. This is called an inter-DU handover. Alternatively, the source cell and the target cell may belong to the same CU and the same DU. In this case, the terminal handover does not involve inter-CU or inter-DU handover.

[0061] As shown in FIG. 2, inter-DU handover is used as an example to provide a handover procedure, which includes the following steps:

[0062] Step 200: The CU sends an L3 measurement configuration to the terminal.

[0063] Step 201: The terminal reports an L3 measurement report to the CU based on the L3 measurement configuration.

[0064] For example, the terminal measures reference signals based on the L3 measurement configuration to obtain L3 measurement results. For example, the reference signals may include synchronization signals / physical broadcast channel blocks (SS / PBCH blocks, SSBs) and channel state information-reference signals (CSI-RSs). The terminal reports an L3 measurement report to the CU. The L3 measurement report includes the L3 measurement results.

[0065] Step 202: The CU determines that an L1 / L2 handover needs to be performed based on the L3 measurement report reported by the terminal, and sends a terminal context setup request to at least one candidate target DU. The candidate target DU may also be referred to as a candidate DU.

[0066] The procedure in FIG. 2 uses an example in which a CU sends a terminal context setup request to two candidate target DUs, which are referred to as candidate target DU1 and candidate target DU2, respectively.

[0067] Step 203: The candidate target DU performs admission control. If the candidate target DU determines that the terminal is allowed to access, the candidate target DU returns a context setup request acknowledgement message to the CU, where the context setup request acknowledgement message includes configuration information of the LTM candidate cell.

[0068] Step 204: The CU sends an RRC reconfiguration message to the terminal, where the RRC reconfiguration message includes configuration information of the LTM candidate cell. Optionally, the RRC reconfiguration message further includes L1 measurement configuration information.

[0069] Step 205: The terminal sends an RRC reconfiguration complete message to the CU.

[0070] Step 206: The terminal sends an L1 measurement report to the source DU, where the L1 measurement report includes the L1 measurement result.

[0071] In one embodiment, the LTM candidate cells configured in step 203 include at least one candidate cell. The terminal may measure reference signals based on L1 measurement configuration information of each candidate cell in the LTM candidate cells and determine L1 measurement results for each candidate cell. The terminal transmits an L1 measurement report to the source DU based on reporting configuration information in the L1 measurement configuration. The L1 measurement report includes L1 measurement results corresponding to each candidate cell in the LTM candidate cells. The source DU makes a handover decision based on the L1 measurement report reported by the terminal and determines to trigger an LTM handover. The source DU may select a cell from the LTM candidate cells based on the L1 measurement report reported by the terminal, and the cell is used as a target cell for the LTM handover. For example, a corresponding candidate cell whose measurement result quality included in the L1 measurement report is greater than a preset threshold may be selected as the target cell from the LTM candidate cells.

[0072] Step 207: The source DU sends an L1 / L2 handover command to the terminal, where the handover command includes information about the target cell. Optionally, the information about the target cell includes a configuration identifier of the target cell.

[0073] The terminal decides to handover from the source cell to the target cell. Optionally, the source DU sends a sequence number state transition to the candidate target DU1.

[0074] Optionally, in step 208, the terminal synchronizes with the target DU to which the target cell belongs.

[0075] For example, the synchronization process may be implemented by using a random access channel (RACH) process, or may be implemented by using another process, such as RACH-less, without being limited thereto.

[0076] It should be noted that in the procedure of FIG. 2, an example is used for explanation in which the target DU to which the target cell belongs is candidate target DU1.

[0077] Optionally, in step 209, the terminal sends a handover complete message to the candidate target DU1, where the handover complete message may be an RRC reconfiguration complete, a cell-radio network temporary identifier (C-RNTI) MAC CE, etc.

[0078] Through the above process, the serving cell of the terminal is switched from the source cell to the target cell. When the CU receives the user data of the terminal from the core network, the CU transmits the user data to the candidate target DU1, and the candidate target DU1 transmits the user data to the terminal via the target cell.

[0079] As shown in Figure 3, an embodiment of the present application further provides a handover procedure. In the handover procedure of Figure 3, the source cell and the target cell belong to the same CU and the same DU. Because the source DU and the target DU are the same DU, the difference from the inter-DU handover of Figure 2 lies in steps 202 and 203. Specifically, in Figure 3, step 202 is for the CU to send a terminal context modification request to the DU, and step 203 is for the DU to send a terminal context modification acknowledgement to the CU.

[0080] As described above, in step 204, the CU sends an RRC reconfiguration message to the terminal, where the RRC reconfiguration message includes configuration information of the LTM candidate cell, and the configuration information of the LTM candidate cell includes configurations of one or more LTM candidate cells. In one design, the configuration information of the LTM candidate cell may be a full configuration or a delta configuration. The delta configuration is a delta configuration based on the first reference configuration.

[0081] The configuration of the LTM candidate cell includes at least a cell group configuration and may optionally further include a measurement configuration and a radio bearer configuration. The first reference configuration includes at least a cell group configuration and may optionally further include a measurement configuration and a radio bearer configuration.

[0082] Optionally, if the LTM candidate cells are in a delta configuration, the configuration information of the LTM candidate cells included in step 204 includes a first reference configuration and a delta configuration of each candidate cell based on the first reference configuration. In step 207, the source DU sends an L1 / L2 handover command to the terminal, where the L1 / L2 handover command includes information about the target cell. The terminal determines the configuration information of the target cell in the configuration information of the LTM candidate cells. The terminal applies the configuration of the target cell based on the configuration information of the target cell. In the current handover design, when the configuration of the target cell is a delta configuration, the terminal determines the configuration of the target cell based on the configuration of the source cell and the configuration of the target cell. In other words, the terminal directly applies the delta configuration of the target cell based on the source configuration. However, as described in step 204, if the delta configurations of the candidate target cells (including the target cell) are based on the first reference configuration, the terminal directly applies the delta configuration of the target cell based on the configuration of the source cell according to the current handover design, and the determined or applied configuration of the target cell is incorrect, resulting in a handover failure. In addition, when the LTM candidate cell is in a delta configuration, if the terminal does not apply the configuration of the target cell according to the current handover design, it is unclear how the terminal will apply the configuration of the target cell in LTM.

[0083] In an embodiment of the present application, the terminal device determines the configuration of the target cell for handover based on the first reference configuration and the delta configuration of the target cell. The configuration of the target cell determined by the terminal is accurate, thereby improving the handover success rate. The terminal device is a device used in a terminal, and may be a terminal, or a chip, circuit, etc. used in a terminal. The access network device may be an access network device, or a chip, circuit, etc. used in an access network device. In the following description, an example in which the terminal device is a terminal and the access network device is specifically an access network device is used for explanation. As shown in FIG. 4, a procedure is provided, and the procedure includes the following steps:

[0084] Step 401: An access network device sends a first configuration to a terminal, and in response, the terminal receives the first configuration.

[0085] The first configuration includes a first reference configuration and a delta configuration of the target cell, and the first reference configuration is related to the delta configuration of the target cell.

[0086] Step 402: The terminal determines a configuration of the terminal in the target cell based on the first reference configuration and the delta configuration of the target cell.

[0087] Determining the configuration of the terminal in the target cell includes the terminal determining a radio configuration of the terminal based on the first reference configuration and the delta configuration of the target cell, where the radio configuration of the terminal includes the radio configuration of the terminal in the target cell.

[0088] Optionally, before step 402, the method further includes the terminal receiving a handover command from the access network device. For example, the handover command may instruct the terminal to hand over from the source cell to the target cell. For example, the handover command may include information about the target cell. Alternatively, the terminal satisfies a handover condition. In other words, the terminal may decide by itself whether to hand over from the source cell to the target cell based on the handover condition. The handover condition may be specified in a protocol, pre-set, configured for the terminal by another device, or similarly determined by other methods. This is not limited thereto. The other device may be an access network device, a core network device, etc. For example, when the handover condition is satisfied, the terminal may decide to hand over from the source cell to the target cell. For example, the terminal may determine through measurements that a signal measurement amount of the source cell is below a threshold and a signal measurement amount of the target cell is equal to or greater than a threshold. In this case, the terminal may determine that the terminal satisfies the handover condition and to hand over from the source cell to the target cell. In other words, the handover condition may be that the signal measurement of the source cell is below a threshold and the signal measurement of the target cell is above a threshold, and so on.

[0089] In this embodiment of the present application, the terminal determines the configuration of the target cell based on a first reference configuration and a delta configuration of the target cell. The first reference configuration includes a cell group configuration. Optionally, the first reference configuration further includes a measurement configuration, a radio bearer configuration, etc. The cell group configuration, the measurement configuration, or the radio bearer configuration may include one or more fields or information elements. Each field or information element has an existence condition. The existence condition may be mandatory existence, optional existence, or conditional existence. For example, in the case of optional existence, the existence condition may be Need M, Need N, Need R, or Need S. The specific meanings of Need M, Need N, Need R, or Need S are the same as those in the protocol. For example, as follows:

[0090] Need M: If the first reference configuration received by the terminal from the access network device includes the field or information element, the value of the field or information element is used. If the configuration of the terminal from the access network device does not include the field or information element, the current value is retained.

[0091] Need N: If the first reference configuration received by the terminal from the access network device includes a field or information element, the value of the field or information element is used. If the first reference configuration received by the terminal from the access network device does not include a field or information element, the terminal does not perform any operation, i.e., does not use the field or information element.

[0092] Need R: If the first reference configuration received by the terminal from the access network device includes a field or information element, the value of the field or information element is used. If the first reference configuration received by the terminal from the access network device does not include a field or information element, the terminal releases the current value of the field or information element.

[0093] The delta configuration of the target cell includes a cell group configuration. Optionally, the delta configuration of the target cell may further include a measurement configuration and / or a radio bearer configuration.

[0094] For example, a cell group configuration, a measurement configuration, or a radio bearer configuration may include one or more fields or information elements. Each field or information element has an existence condition. The existence condition may be mandatory, optional, or conditional. If optional, the existence condition may be Need M, Need N, Need R, or Need S. The specific meaning of Need M, Need N, Need R, or Need S is the same as the meaning in the protocol.

[0095] The delta configuration of the target cell is a delta configuration based on the first reference configuration. It will be understood that the delta configuration of the target cell is a reconfiguration based on the first reference configuration. The following will use an example to explain the understanding of the delta configuration of the target cell.

[0096] For example, the existence condition for field or information element 1 is Need M, and the first reference configuration includes field or information element 1. If the delta configuration of the target cell also includes field or information element 1, the value of the first field in the first reference configuration is replaced with the value of the first field in the delta configuration of the target cell. If the first reference configuration includes field or information element 1 and the delta configuration of the target cell does not include field or information element 1, the value in the first reference configuration is used for field 1 in the configuration of the terminal in the target cell.

[0097] For example, the existence condition of field or information element 2 is Need R. If the first reference configuration includes field or information element 2 and the delta configuration of the target cell also includes field or information element 2, the second field in the first reference configuration is replaced with the value of the second field in the delta configuration of the target cell. If the first reference configuration includes field or information element 2 and the delta configuration of the target cell does not include field or information element 2, the configuration of the terminal in the target cell does not include field or information element 2.

[0098] For example, the existence condition of field or information element 3 is Need N. If the first reference configuration includes field or information element 3 and the delta configuration of the target cell also includes field or information element 3, the third field in the first reference configuration is replaced with the value of the third field in the delta configuration of the target cell. If the first reference configuration includes field or information element 3 and the delta configuration of the target cell does not include field or information element 3, the configuration of the terminal in the target cell does not include field or information element 3, and the terminal does not need to take any action based on field or information element 3.

[0099] For example, if the delta configuration of the target cell further includes field or information element 4 and the first reference configuration includes field or information element 4, the configuration of the terminal in the target cell includes field or information element 4 in the delta configuration of the target cell.

[0100] [Embodiment 1] In one embodiment, in step 402, the terminal determining a configuration for the terminal in the target cell based on the first reference configuration and the delta configuration of the target cell includes the terminal applying the first reference configuration and the terminal applying the delta configuration of the target cell.

[0101] The terminal applying the first reference configuration includes, but is not limited to, the following process: The terminal releases its current dedicated radio configuration except for at least one of a master cell group (MCG) C-RNTI, an access stratum security configuration associated with a master key, a radio bearer configuration, an RLC bearer configuration, a secondary cell (SCell) configuration, and a recorded measurement configuration.

[0102] Optionally, the terminal applying the first reference configuration may further include at least one of the following: The terminal applies default Layer 1 parameter values ​​except for parameters provided by system information block 1 (SIB1) and applies a default MAC configuration for the cell group.

[0103] Optionally, applying the first reference configuration by the terminal further includes performing measurement configuration if the first reference configuration includes a measurement configuration. Performing measurement configuration by the terminal includes releasing / clearing a current terminal measurement configuration of the associated cell group, including at least one of releasing a measurement configuration report, releasing a measurement configuration variable, stopping any ongoing periodic reporting, stopping timer T321, stopping timer T322, etc. Optionally, performing measurement configuration by the terminal may further include performing measurement object addition / modification if the measurement configuration of the first reference configuration includes a measurement object addition / modification list, performing measurement object deletion if the measurement configuration includes a measurement object deletion list, performing measurement report configuration addition / modification if the measurement configuration includes a measurement report configuration addition / modification list, performing measurement report configuration deletion if the measurement configuration includes a measurement report configuration deletion list, performing a measurement quantity configuration process if the measurement configuration includes a measurement quantity configuration, performing measurement identifier addition / modification if the measurement configuration includes a measurement identifier addition / modification list, or performing measurement identifier deletion if the measurement configuration includes a measurement identifier deletion list.

[0104] The terminal device applying the delta configuration of the target cell includes at least one of determining a radio configuration of the terminal based on the delta configuration of the target cell if the delta configuration of the target cell includes a radio configuration, configuring a MAC entity of the cell group if the delta configuration of the target cell includes a MAC configuration of the cell group, or performing a measurement configuration process if the target cell configuration includes a measurement configuration. It should be understood that the terminal device applies the delta configuration of the target cell based on application of the first reference configuration. Specifically, the terminal first applies the first reference configuration and then applies the delta configuration of the target cell.

[0105] In step 402, determining the radio configuration of the terminal in the target cell based on the first reference configuration and the delta configuration of the target cell, or determining the radio configuration of the terminal in the target cell based on the delta configuration of the target cell, may be expressed in the following form:

[0106] For example, the first variable includes a radio configuration of the first reference configuration, the first variable is updated based on the delta configuration of the target cell, the updated first variable includes the radio configuration of the target cell, and the radio configuration of the terminal in the target cell is determined based on the updated first variable.

[0107] The first variable includes a first reference configuration, and the terminal updates the first variable based on the first reference configuration and the delta configuration of the target cell, where the updated first variable includes the radio configuration of the target cell. In this embodiment of the present application, the first reference configuration includes a radio configuration list, and the radio configuration list includes at least one radio configuration. For example, the first reference configuration includes an RLC bearer configuration addition / modification list, and the RLC bearer configuration addition / modification list includes at least one RLC bearer configuration. As another example, the first reference configuration includes a radio bearer configuration, and the radio bearer configuration includes a data radio bearer (DRB) addition / modification list, and the DRB addition / modification list includes at least one DRB configuration. The delta configuration of the target cell is a delta configuration based on the first reference configuration. The delta configuration of the target cell may include a first list and / or a second list. For example, the first list may be a radio configuration addition / modification list, and the second list may be a radio configuration release list. Updating the first variable based on the delta configuration of the target cell includes at least one of the following 1 to 3:

[0108] 1. Correction If the first variable includes a first radio configuration, the first list includes a second radio configuration, the first list is a list in a delta configuration of the target cell, and an identifier of the first radio configuration is the same as an identifier of the second radio configuration, the first radio configuration in the first variable is updated to the second radio configuration.

[0109] Optionally, in one embodiment, updating the first radio configuration in the first variable to the second radio configuration may comprise reconfiguring the first radio configuration based on the second radio configuration.

[0110] Optionally, in another embodiment, updating the first variable of the first radio configuration to the second radio configuration may include determining a complete configuration of the second radio configuration based on the first radio configuration and the second radio configuration, and replacing the first radio configuration with the complete configuration of the second radio configuration.

[0111] 2. Add If the first list includes a third wireless configuration and the first variable includes a wireless configuration other than the third wireless configuration, the third wireless configuration is added to the first variable.

[0112] 3. Delete If the first variable includes a fourth radio configuration, the second list includes a fifth radio configuration, the second list is a list in a delta configuration of the target cell, and the identifier of the fourth radio configuration is the same as the identifier of the fifth radio configuration, the fourth radio configuration is released in the first variable.

[0113] For example, the delta configuration of the target cell includes a first list and a second list, where the first list is a radio configuration addition / modification list and the second list is a radio configuration release list. The radio configuration addition / modification list is mainly used to add and / or modify radio configurations in the first reference configuration. The first variable before the update includes the first reference configuration, and a radio configuration (e.g., the first radio configuration) included in the first variable and a radio configuration (e.g., the second radio configuration) included in the addition / modification list have the same identifier. In this case, the first radio configuration in the first variable is updated to the second radio configuration. Alternatively, if a radio configuration (e.g., the third radio configuration) included in the radio configuration addition / modification list is not included in the first variable, the third radio configuration is added to the first variable. Alternatively, if a radio configuration (e.g., the fourth radio configuration) included in the radio configuration release list and a radio configuration (e.g., the fifth radio configuration) included in the first variable before the update have the same identifier, the fourth radio configuration is released in the first variable. Through the aforementioned processes of modifying, adding, and / or deleting, the updated first variable includes the complete radio configuration of the target cell.

[0114] For example, the first reference configuration includes radio configuration 1 and radio configuration 4, and the delta configuration of the target cell includes a radio configuration addition / modification list and a radio configuration release list. The radio configuration addition / modification list includes radio configuration 1, radio configuration 2, and radio configuration 3. The radio configuration release list includes radio configuration 4. In this case, it is as follows:

[0115] If the radio configuration 1 included in the radio configuration addition / modification list included in the delta configuration of the target cell and the radio configuration 1 included in the first reference configuration (i.e., the first variable) have the same identifier, the radio configuration 1 in the first variable may be updated to the radio configuration 1 in the radio configuration addition / modification list of the target cell. The radio configuration 1 in the first variable corresponds to an example of the first radio configuration described above, and the radio configuration 1 in the radio configuration addition / modification list in the delta configuration of the target cell corresponds to an example of the second radio configuration described above. It will be understood that the radio configuration 1 in the first reference configuration and the radio configuration 1 in the delta configuration of the target cell may have the same radio configuration identifier but may have certain different radio configuration parameters or fields. For example, if the radio configuration is an RLC bearer configuration, radio configuration 1 is an RLC bearer configuration whose logical channel ID (LCID) value is 1, radio configuration 2 is an RLC bearer configuration whose LCID value is 2, radio configuration 3 is an RLC bearer configuration whose LCID value is 3, and radio configuration 4 is an RLC bearer configuration whose LCID value is 4. In another example, if the radio configuration is a DRB configuration, radio configuration 1 is a DRB configuration whose DRB identifier is 1, radio configuration 2 is a DRB configuration whose DRB identifier is 2, radio configuration 3 is a DRB configuration whose DRB identifier is 3, and radio configuration 4 is a DRB configuration whose DRB identifier is 4.

[0116] If radio configuration 2 and radio configuration 3 included in the radio configuration addition / modification list are not included in the first reference configuration (i.e., the first variable), radio configuration 2 and radio configuration 3 are added to the first variable. Radio configuration 2 and radio configuration 3 correspond to the example of the third radio configuration described above.

[0117] Because the radio configuration release list includes radio configuration 4 and the first reference configuration also includes radio configuration 4, radio configuration 4 is deleted from the first variable. Radio configuration 4 corresponds to an example of the fourth radio configuration described above.

[0118] Through the above-mentioned update process, the updated first variable includes the complete radio configuration of the target cell. In the above example, the complete radio configurations of the target cell included in the updated first variable are radio configuration 1, radio configuration 2, and radio configuration 3.

[0119] Determining a radio configuration of the terminal in the target cell based on the first variable updated by the terminal includes at least one of the following 1 to 3:

[0120] 1. Reconstruction If the updated first variable includes a sixth radio configuration, the radio configuration of the source cell includes a seventh radio configuration, and the identifier of the sixth radio configuration is the same as the identifier of the seventh radio configuration, the terminal reconfigures the seventh radio configuration based on the sixth radio configuration.

[0121] In one embodiment, reconfiguring the seventh radio configuration based on the sixth radio configuration means replacing the sixth radio configuration of the terminal with the seventh radio configuration, i.e., replacing the sixth radio configuration with the seventh radio configuration in the radio configuration of the terminal.

[0122] 2. Create If the updated first variable includes the eighth radio configuration and the radio configuration of the source cell includes a configuration other than the eighth radio configuration, the terminal creates the eighth radio configuration.

[0123] 3. Liberation If the radio configuration of the source cell includes the ninth radio configuration and the updated first variable includes a configuration other than the ninth radio configuration, the terminal releases the ninth radio configuration.

[0124] For example, the updated first variable includes the full configuration of the target cell. The updated first variable includes a radio configuration list of the target cell. For example, the radio configuration list includes radio configuration 1, radio configuration 2, and radio configuration 3. The radio configuration list of the source cell includes radio configuration 3 and radio configuration 4.

[0125] The radio configuration list of the source cell includes radio configuration 3, and the radio configuration list of the target cell also includes radio configuration 3. In this case, the radio configuration 3 of the terminal (radio configuration 3 is the radio configuration 3 of the terminal in the source cell) may be reconfigured based on the radio configuration 3 of the target cell. The radio configuration 3 of the target cell is an example of the sixth radio configuration described above, and the radio configuration 3 of the source cell is an example of the seventh radio configuration described above. It will be understood that the radio configuration 3 of the target cell and the radio configuration 3 of the source cell have the same identifier but may correspond to different specific radio configuration parameters or fields.

[0126] The previous example will be continued. The radio configuration 1 and radio configuration 2 of the target cell are not included in the radio configuration of the source cell. In this case, the radio configuration 1 and radio configuration 2 may be created in the radio configuration of the terminal. The radio configuration 1 and radio configuration 2 of the target cell are an example of the above-mentioned eighth radio configuration.

[0127] The previous example will be continued. The radio configuration of the source cell includes radio configuration 4, and the radio configuration of the target cell does not include radio configuration 4. In this case, radio configuration 4 is released in the radio configuration of the terminal. Radio configuration 4 of the source cell is an example of the above-mentioned ninth radio configuration.

[0128] In one design, during a cell handover process, the terminal first releases the radio configuration of the source cell and then creates the radio configuration of the target cell. For example, in the aforementioned example, the terminal first releases radio configuration 3 and radio configuration 4 of the source cell and then creates radio configuration 1, radio configuration 2, and radio configuration 3 of the target cell. If the aforementioned release-first-create method is used for radio configuration 3, handover efficiency and handover delay are affected, and service continuity is affected. In this embodiment of the present application, a reconfiguration method is used for radio configuration 3. Specifically, the entity corresponding to radio configuration 3 is not released, and the entity is only reconfigured based on the radio configuration 3 of the target cell, thereby improving handover efficiency and reducing handover delay. Furthermore, during a cell handover process, if the entity corresponding to radio configuration 3 contains service data to be transmitted, the corresponding entity is released. This may cause the loss of the service data to be transmitted and result in discontinuity of the service data. However, in this embodiment of the present application, the corresponding entity is not released, and only the corresponding radio configuration is modified. After the cell handover is successful, the service data in the entity continues to be transmitted, thereby ensuring service continuity.

[0129] In this embodiment of the present application, the radio configuration of the terminal includes at least one of a radio bearer (RB) configuration, an RLC bearer configuration, a secondary cell configuration, etc. It should be noted that in this embodiment of the present application, the first variable is for determining or storing the radio configuration of the target cell. For example, if the radio configuration of the target cell is an RLC bearer configuration, the first variable is for storing or determining the RLC bearer configuration of the target cell. Alternatively, if the radio configuration of the target cell is a DRB configuration, the first variable is for storing or determining the DRB configuration of the target cell. Alternatively, if the radio configuration of the target cell is a signaling radio bearer (SRB), the first variable is for storing or determining the SRB configuration of the target cell. Alternatively, if the radio configuration of the target cell is a secondary cell SCell, the first variable is for storing or determining the SCell configuration of the target cell.

[0130] It should be understood that the name of the "variable" is not limited in this embodiment of the present application. Other parameters that can realize the function of the "variable" also fall within the scope of protection of this embodiment of the present application. For example, the variable may be replaced by a "list", "configuration", "temporary list", "intermediate state", etc., maintained by the terminal. This is not limited.

[0131] An example is used in which the radio configuration of the terminal is an RLC bearer configuration. This embodiment of the present application provides a cell handover solution. The gist of the solution is that when the terminal receives a handover command, the terminal first applies a first reference configuration. Optionally, the first reference configuration is a complete configuration, a full configuration, etc. It will be understood that the first reference configuration includes complete configuration parameters and is not a delta configuration based on the configuration. Then, the terminal applies a delta configuration of the target cell based on the first reference configuration. Optionally, for the RLC bearer configuration, the terminal determines a first variable, where the first variable includes an RLC bearer configuration of the LTM target cell. When the terminal receives the handover command and applies the delta configuration of the target cell, the terminal compares the current configuration of the terminal with the RLC bearer configuration included in the first variable, and releases, adds, and / or modifies the RLC bearer configuration. This solution includes the following steps:

[0132] 1: The terminal receives an RRC reconfiguration message from an access network device, and the RRC reconfiguration message includes configuration information of an LTM candidate cell.

[0133] In one embodiment, the RRC reconfiguration message includes an LTM configuration. The LTM configuration includes an LTM candidate cell configuration and, optionally, further includes a first reference configuration. The LTM candidate cell configuration includes configuration information for one or more LTM candidate cells. The configuration information for each LTM candidate cell includes an LTM candidate cell configuration identifier and a configuration for the LTM candidate cell.

[0134] Optionally, the LTM candidate cell configuration may be configured by using an LTM candidate cell addition / modification list and / or an LTM candidate cell release list. The LTM candidate cell addition / modification list includes configuration information of one or more candidate cells. The configuration information of each candidate cell includes an LTM candidate cell configuration identifier and a configuration of the LTM candidate cell. The configuration of the LTM candidate cell is a delta configuration with respect to a first reference configuration. For example, if the configuration of the LTM candidate cell is a delta configuration with respect to the first reference configuration, the configuration of the LTM candidate cell may be referred to as a delta configuration of the LTM candidate cell. The LTM candidate cell release list includes the LTM candidate cell configuration identifier.

[0135] Optionally, if the RRC reconfiguration message includes the first reference configuration, the terminal stores the first reference configuration.

[0136] Optionally, the terminal maintains or stores a third variable, the third variable for determining an LTM candidate cell configuration configured by the access network device for the terminal. For example, the third variable may be referred to as an LTM candidate configuration variable. The third variable includes an LTM candidate cell configuration configured by the access network device for the terminal and may optionally be an LTM candidate cell list, the LTM candidate cell list including configuration information of at least one LTM candidate cell.

[0137] Optionally, the third variable may further include a first reference configuration. In this embodiment of the present application, upon receiving the RRC reconfiguration message, the terminal updates the LTM candidate cell configuration or the first reference configuration of the terminal based on the LTM configuration included in the RRC reconfiguration message. For example,

[0138] (1) LTM candidate cell deletion If the RRC reconfiguration message includes the LTM candidate cell release information, the terminal releases the LTM candidate cell based on the LTM candidate cell release information. For example, if the LTM candidate cell release information in the RRC reconfiguration message includes an LTM candidate cell configuration identifier, the terminal releases the LTM candidate cell configuration.

[0139] Optionally, in an embodiment, the LTM candidate cell release list includes a first LTM candidate cell configuration identifier, and the terminal device releases the first LTM candidate cell configuration.

[0140] Optionally, in another embodiment, the LTM candidate cell release list includes a first LTM candidate cell and the third variable includes a second LTM candidate cell. If a configuration identifier of the first LTM candidate cell is the same as a configuration identifier of the second LTM candidate cell, the second LTM candidate cell and the corresponding configuration of the second LTM candidate cell are deleted from the third variable.

[0141] (2) Add / modify LTM candidate cells If the RRC reconfiguration message includes LTM candidate cell addition / modification information, the terminal adds or modifies the LTM candidate cell based on the LTM candidate cell addition / modification information. For example, if the LTM candidate cell addition / modification information in the RRC reconfiguration message includes a third LTM candidate cell configuration identifier and configuration information associated with the third LTM candidate cell configuration identifier, and if the terminal's current configuration does not include the third LTM candidate cell configuration identifier when the terminal receives the RRC reconfiguration message, the terminal adds the third LTM candidate cell. As another example, if the LTM candidate cell addition / modification information in the RRC reconfiguration message includes a fourth LTM candidate cell configuration identifier and configuration information associated with the fourth LTM candidate cell configuration identifier, and if the terminal's current configuration includes the fourth LTM candidate cell configuration identifier when the terminal receives the RRC reconfiguration message, the terminal updates the fourth LTM candidate cell configuration included in the terminal's current configuration based on the fourth LTM candidate cell configuration included in the LTM candidate cell addition / modification information. In other words, the fourth LTM candidate cell configuration included in the current configuration of the terminal is replaced with the fourth LTM candidate cell configuration included in the LTM candidate cell addition / modification information in the RRC reconfiguration message.

[0142] Optionally, in another embodiment, the LTM candidate cell addition / modification list includes a third LTM candidate cell and the third variable includes a fourth LTM candidate cell. If the configuration identifier of the third LTM candidate cell is the same as the configuration identifier of the fourth LTM candidate cell, in the third variable, the configuration of the fourth LTM candidate cell is replaced with the configuration of the third LTM candidate cell.

[0143] If the LTM candidate cell addition / modification list includes a fifth LTM candidate cell and the third variable includes a configuration of a cell other than the fifth LTM candidate cell, the fifth LTM candidate cell and the configuration corresponding to the fifth LTM candidate cell are added to the third variable.

[0144] (3) Update the first reference configuration Optionally, when the access network device needs to update the first reference configuration, the access network device may include a full configuration of the first reference configuration or a delta configuration of the first reference configuration. The delta configuration of the first reference configuration is a delta configuration based on the first reference configuration previously stored by the terminal. Optionally, in the reconfiguration message for updating the first reference configuration, the access network device may include an instruction to instruct the terminal to release the currently stored LTM candidate cell configuration. Optionally, the access network device may again provide the LTM candidate cell configuration based on the new reference.

[0145] The terminal receives a reconfiguration message for updating the first reference configuration from the access network device, and the terminal updates the stored first reference configuration. Optionally, the terminal releases the previously stored LTM candidate cell configuration based on the instruction of the access network device and stores the latest LTM candidate cell configuration based on the new reference configuration, or the terminal directly stores the new LTM candidate cell configuration provided by the network.

[0146] In one embodiment, when the terminal receives an RRC reconfiguration message, the process of updating the LTM candidate cell configuration or the first reference configuration of the terminal based on the LTM configuration included in the RRC reconfiguration message is a process of the terminal updating a third variable.

[0147] 2: The terminal receives an LTM handover command from the access network device, and the LTM handover command includes information about a target cell. The target cell in the LTM handover command is one of the LTM candidate cells configured by the access network device for the terminal.

[0148] 3: The terminal performs an LTM handover.

[0149] The terminal performs handover from the source cell to the target cell based on the information about the target cell included in the LTM handover command.

[0150] Optionally, the configuration of the LTM candidate cell is a delta configuration relative to the first reference configuration, e.g., the configuration of the LTM candidate cell may be referred to as a delta configuration of the LTM candidate cell, and the configuration of the target cell for handover may be referred to as a delta configuration of the target cell.

[0151] Optionally, the terminal determines a delta configuration of the target cell in the LTM candidate cell configuration included in the third variable.

[0152] A specific process in which a terminal determines a configuration of a terminal in a target cell based on a first reference configuration and a delta configuration of a target cell, or in which a terminal determines an RLC bearer of a terminal in a target cell based on a first reference configuration and a delta configuration of a target cell, includes:

[0153] It should be noted that in this embodiment of the present application, the RLC bearer configuration is for configuring an RLC entity, a corresponding MAC logical channel, and a radio bearer of an associated service. The RLC bearer configuration of the LTM target cell includes configuration information of at least one RLC bearer. The configuration information of each RLC bearer includes at least a logical channel identifier of the RLC bearer. For example, the value of the logical channel identifier may be 1 to 65855. Optionally, the RLC bearer configuration may further include at least one of a serving radio bearer, an RLC re-establishment indication, an RLC configuration, a MAC logical channel configuration, etc.

[0154] (1) The terminal applies the first reference configuration.

[0155] The terminal releases the current configuration information of the terminal except for at least one of the MCG C-RNTI, the access stratum security configuration, the RB configuration, the RLC bearer configuration, the SCell configuration, or the recorded measurement configuration.

[0156] Optionally, the terminal applies default L1 parameter values ​​except for the parameters provided in SIB1.

[0157] Optionally, the terminal applies a default MAC configuration for the cell group.

[0158] When the first reference configuration includes a cell group configuration, performing the cell group configuration process includes, when the LTM process is running and the terminal is applying the first reference configuration, setting a first variable to an RLC bearer configuration included in the first reference configuration. Optionally, the first reference configuration may include an RLC bearer addition / modification list, and the first variable is set to an RLC bearer configuration included in the RLC bearer addition / modification list in the first reference configuration. For example, the first variable may be referred to as an RLC bearer configuration list variable.

[0159] Optionally, if the first reference configuration includes a measurement configuration, a measurement configuration process is performed.

[0160] Optionally, if the first reference configuration includes a dedicated non-access stratum (NAS) message list, each information element in the NAS message list is forwarded to the upper layer.

[0161] Optionally, if the first reference configuration includes dedicated system information, an operation of receiving the system information is performed.

[0162] (2) The terminal applies the delta configuration of the target cell.

[0163] In one embodiment, the terminal applies a delta configuration of the target cell that includes at least one of (2.1) to (2.4).

[0164] (2.1) If the delta configuration of the target cell includes a cell group configuration, a cell group configuration process including either (2.1.1) or (2.1.2) is performed.

[0165] (2.1.1) If the LTM process is running and the terminal applies the target cell configuration, the terminal updates the first variable based on the delta configuration of the target cell, and the terminal performs the RLC bearer configuration process. Otherwise, if the LTM process is not running and the cell group configuration includes an RLC bearer release list, the RLC bearer release process is performed. If the cell group configuration includes an RLC bearer addition / modification list, the RLC bearer addition / modification process is performed.

[0166] When the LTM process is running and the terminal is applying the target cell configuration, the terminal updating the first variable based on the delta configuration of the target cell includes:

[0167] The delta configuration of the target cell includes an RLC bearer addition / modification list and / or an RLC bearer release list. The RLC bearer addition / modification list includes configuration information of one or more RLC bearers that need to be added and / or modified with respect to the first reference configuration. The configuration information of each RLC bearer includes at least a logical channel identifier of the RLC bearer and a configuration of the RLC bearer. Optionally, the configuration of the RLC bearer may further include at least one of a serving radio bearer, an RLC re-establishment indication, an RLC configuration, and a MAC logical channel configuration. The RLC bearer release list includes logical channel identifiers of RLC bearers that need to be released with respect to the first reference configuration. There is a correspondence between RLC bearers and logical channels, and the RLC bearers can be identified by using LCIDs. In other words, the identifiers of the RLC bearers can be LCIDs. Specifically, at least one of the following is included:

[0168] If the RLC bearer release list in the delta configuration of the target cell includes an LCID value and the LCID value is included in the first variable, the RLC bearer corresponding to the LCID value is deleted from the first variable. Deleting the RLC bearer corresponding to the LCID value includes deleting the configuration of the RLC bearer.

[0169] If the LCID value included in the first variable is present in the RLC bearer addition / modification list included in the delta configuration of the target cell, the configuration of the RLC bearer corresponding to the LCID in the first variable is replaced with the corresponding configuration in the delta configuration of the target cell.

[0170] If the LCID value included in the RLC bearer addition / modification list included in the delta configuration of the target cell does not exist in the first variable, the configuration information of the RLC bearer is added to the first variable, i.e., the LCID and configuration of the corresponding RLC bearer are added to the first variable.

[0171] After the above processing, the updated first variable contains the complete RLC bearer configuration of the target cell.

[0172] The terminal performing the RLC bearer configuration process includes at least one of the following:

[0173] If the current RLC configuration of the terminal includes a first LCID value, the first variable includes the first LCID value, and the first LCID value may mean that the LCID value is the first value, the RLC entity in the current configuration of the terminal is reconfigured based on the RLC bearer configuration corresponding to the first LCID value included in the first variable. Optionally, the RLC bearer corresponding to the first LCID value in the current configuration of the terminal and the RLC bearer corresponding to the first LCID value included in the first variable belong to the same cell group. The reconfiguration of the RLC entity in the current configuration of the terminal may be understood as the terminal replacing the RLC bearer configuration corresponding to the first LCID value in the current configuration of the terminal based on the RLC bearer configuration corresponding to the first LCID value in the first variable. Optionally, the terminal may further reconfigure logical channels based on MAC logical channels in the delta configuration of the target cell.

[0174] If the first variable includes a second LCID value, an RLC bearer corresponding to the second LCID value does not exist in the current configuration of the terminal, and the second LCID value may mean that the LCID value is the second value, the terminal creates an RLC entity based on the RLC bearer configuration corresponding to the second LCID value included in the first variable.

[0175] If the current configuration of the terminal includes a third LCID value but the first variable does not include the third LCID value, and the third LCID value may mean that the LCID value is the third value, the RLC entity corresponding to the third LCID value in the current configuration of the terminal is released, and the corresponding logical channel is released.

[0176] (2.1.2) If the cell configuration includes a MAC configuration for a cell group, the MAC entity of the cell group is configured. For the process of configuring the MAC entity of a cell group, please refer to the protocol description.

[0177] (2.2) If the delta configuration of the target cell includes a measurement configuration, the measurement configuration process is performed. For the measurement process, please refer to the protocol description.

[0178] (2.3) If the target cell's delta configuration includes a dedicated NAS message list, each information element in the list is forwarded to the upper layer.

[0179] (2.4) If the delta configuration of the target cell includes dedicated system information, an operation of receiving system information is performed. For the operation of receiving system information, please refer to the protocol description.

[0180] 4. The terminal performs a RACH or RACH-less process for the target cell.

[0181] In embodiment 1, in the process of a terminal performing an LTM cell handover, the terminal applies a first reference configuration and then applies a delta configuration of the target cell, so that the terminal can accurately apply the configuration of the target cell and perform the process of handover to the target cell, thereby improving the handover success rate. Furthermore, when the LTM target cell configuration is applied, a first variable and a new processing process are introduced for configurations that affect service continuity (e.g., RLC bearer, radio bearer, and SCell configuration). Because the configuration of the source cell and the configuration of the target cell are compared, the terminal does not perform unnecessary "release and add" processes for configurations that affect service continuity and are included in both the source cell and the target cell in the handover process, thereby improving LTM handover performance and reducing handover interruptions and handover delays.

[0182] [Embodiment 2] In one embodiment, in step 402, the terminal determining a configuration for the terminal in the target cell based on the first reference configuration and the delta configuration of the target cell includes the terminal applying the first reference configuration and the terminal applying the delta configuration of the target cell.

[0183] The application of the first reference configuration by the terminal includes, but is not limited to, the following process: The terminal releases the current cell group configuration of the terminal in the current cell group configuration except for at least one of the MCG C-RNTI or the RLC bearer configuration.

[0184] Optionally, the terminal applying the first reference configuration may further include at least one of the following: the terminal applies default Layer 1 parameter values ​​excluding parameters provided by SIB1, and applies a default MAC configuration for the cell group.

[0185] Optionally, the applying of the first reference configuration by the terminal further includes, if the first reference configuration includes a measurement configuration, performing measurement configuration. The performing of the measurement configuration by the terminal may include releasing / clearing a current terminal measurement configuration of the associated cell group, including at least one of releasing a measurement configuration report, releasing a measurement configuration variable, stopping any running periodic reports, stopping timer T321, or stopping timer T322. Optionally, performing measurement configuration by the terminal may further include performing measurement object addition / modification if the measurement configuration of the first reference configuration includes a measurement object addition / modification list, performing measurement object deletion if the measurement configuration includes a measurement object deletion list, performing measurement report configuration addition / modification if the measurement configuration includes a measurement report configuration addition / modification list, performing measurement report configuration deletion if the measurement configuration includes a measurement report configuration deletion list, performing a measurement quantity configuration process if the measurement configuration includes a measurement quantity configuration, performing measurement identifier addition / modification if the measurement configuration includes a measurement identifier addition / modification list, or performing measurement identifier deletion if the measurement configuration includes a measurement identifier deletion list.

[0186] The terminal device applying the delta configuration of the target cell includes at least one of determining a radio configuration of the terminal based on the delta configuration of the target cell if the delta configuration of the target cell includes a radio configuration, configuring a MAC entity of the cell group if the delta configuration of the target cell includes a MAC configuration of the cell group, or performing a measurement configuration process if the delta configuration of the target cell includes a measurement configuration. It should be understood that the terminal device applies the delta configuration of the target cell based on the application of the first reference configuration.

[0187] The process of determining the configuration of the terminal in the target cell based on the first reference configuration and the delta configuration of the target cell in step 402 includes the terminal determining a second reference configuration based on the radio configuration in the first reference configuration, and determining the configuration of the terminal in the target cell based on the second reference configuration and the delta configuration of the target cell.

[0188] The process by which the terminal determines the second reference configuration based on the radio configuration in the first reference configuration includes at least one of the following:

[0189] If the first reference configuration includes the tenth radio configuration, the radio configuration of the source cell includes the eleventh radio configuration, and the identifier of the tenth radio configuration is the same as the identifier of the eleventh radio configuration, the eleventh radio configuration of the terminal is updated to the tenth radio configuration. Optionally, updating the eleventh radio configuration to the tenth radio configuration may be understood as replacing the eleventh radio configuration in the current configuration of the terminal with the tenth radio configuration.

[0190] If the first reference configuration includes the twelfth radio configuration and the radio configuration of the source cell includes a radio configuration other than the twelfth radio configuration, the twelfth radio configuration is created for the terminal.

[0191] The second reference configuration includes at least a tenth radio configuration and a twelfth radio configuration. Optionally, the second reference configuration further includes another radio configuration other than the eleventh radio configuration in the current radio configuration of the terminal.

[0192] In this embodiment of the present application, the aforementioned process of determining a second reference configuration based on a first reference configuration can be understood as the terminal applying the first reference configuration in the radio configuration of the source cell. For example, for a radio configuration having the same identifier in the source cell and the first reference configuration, the corresponding radio configuration in the current configuration is replaced with the radio configuration in the first reference configuration. When a radio configuration exists in the first reference configuration but not in the source cell, a corresponding configuration is created for the terminal based on the radio configuration in the first reference configuration. The difference is that if a radio configuration exists in the source cell of the terminal but not in the first reference configuration, no release operation is performed first. After the delta configuration of the target cell is completed, a release operation is finally performed for the radio configuration in the radio configuration of the source cell that does not exist in either the first reference configuration or the delta configuration of the target cell.

[0193] In this embodiment of the present application, the terminal may maintain a second variable, the second variable being for determining a radio configuration that should be released by the terminal in the handover process and that is included in the source cell but not included in the target cell. Before the terminal applies the first reference configuration, the second variable includes an identifier of the radio configuration of the source cell. When the first reference configuration includes a tenth radio configuration, the radio configuration of the source cell includes an eleventh radio configuration, and the identifier of the tenth radio configuration is the same as the identifier of the eleventh radio configuration, the method further includes the terminal deleting the identifier of the eleventh radio configuration from the radio configuration identifier of the source cell, which is included in the second variable.

[0194] After the terminal applies the first reference configuration through the above process, the current configuration of the terminal may be referred to as the second reference configuration. In one embodiment, the terminal determines the radio configuration of the terminal in the target cell based on the second reference configuration and the delta configuration of the target cell, reconfiguring a thirteenth radio configuration of the terminal based on the fifteenth radio configuration when the second reference configuration of the terminal includes a thirteenth radio configuration, the first reference configuration includes a fourteenth radio configuration, the third list includes a fifteenth radio configuration, the third list is a list in a delta configuration of the target cell, and the thirteenth radio configuration, the fourteenth radio configuration, and the fifteenth radio configuration have the same identifier; creating a sixteenth radio configuration if the third list includes a sixteenth radio configuration and the second reference configuration and the first reference configuration include a configuration other than the sixteenth radio configuration; if the third list includes a 17th radio configuration, the first reference configuration includes a configuration other than the 17th radio configuration, the second reference configuration includes an 18th radio configuration, and an identifier of the 17th radio configuration is the same as an identifier of the 18th radio configuration, updating the 18th radio configuration based on the 17th radio configuration, optionally, updating the 18th radio configuration based on the 17th radio configuration may also be understood as replacing the 18th radio configuration with the 17th radio configuration; or Releasing the twentieth radio configuration in the radio configuration of the terminal if the fourth list includes the 19th radio configuration, the fourth list is a list in the delta configuration of the target cell, the second reference configuration includes the 20th radio configuration, and an identifier of the 19th radio configuration is the same as an identifier of the 20th radio configuration; It includes at least one of the following:

[0195] Optionally, the delta configuration of the target cell includes a third list and / or a fourth list. In one example, the third list is a radio configuration addition / modification list, and the fourth list is a radio configuration release list. The second reference configuration of the terminal is the radio configuration of the terminal after the terminal applies the first reference configuration. If the radio configuration addition / modification list included in the delta configuration of the target cell includes the fifteenth radio configuration, and the terminal's current configuration (the terminal's current configuration is the configuration after the terminal applies the first reference configuration, i.e., the second reference configuration) includes a thirteenth radio configuration whose identifier is the same as that of the fifteenth radio configuration, and the first reference configuration includes a fourteenth radio configuration whose identifier is the same as that of the fifteenth radio configuration, the thirteenth radio configuration of the terminal is reconfigured based on the tenth radio configuration. Alternatively, if the radio configuration addition / modification list of the target cell includes the 16th radio configuration and neither the terminal's current configuration nor the first reference configuration includes a configuration having the same identifier as the 16th radio configuration, the terminal creates the 16th radio configuration. Alternatively, if the radio configuration addition / modification list of the target cell includes the 17th radio configuration, the first reference configuration does not include a radio configuration whose identifier is the same as that of the 17th radio configuration, and the terminal's current configuration includes an 18th radio configuration whose identifier is the same as that of the 17th radio configuration, the 18th radio configuration in the terminal's current configuration is replaced with the 17th radio configuration. Alternatively, if the radio configuration release list of the target cell includes the 19th radio configuration and the terminal's current configuration includes a 20th radio configuration whose identifier is the same as that of the 19th radio configuration, the 20th radio configuration is released in the terminal's current configuration.

[0196] Optionally, when the terminal applies the delta configuration of the target cell, if the third list includes the 17th radio configuration, the third list is a list within the delta configuration of the target cell, the first reference configuration includes a configuration other than the 17th radio configuration, the second reference configuration includes the 18th radio configuration, and an identifier of the 17th radio configuration is the same as the identifier of the 18th radio configuration, the method further includes the terminal deleting the identifier of the 17th radio configuration from the radio configuration identifier of the source cell included in the second variable.

[0197] Furthermore, applying the delta configuration of the target cell by the terminal further includes the terminal releasing the radio configuration corresponding to the radio configuration identifier included in the second variable. For example, the radio configuration of the source cell includes radio configuration 1, radio configuration 2, and radio configuration 3. Therefore, before the first reference configuration is applied or in the process of applying the first reference configuration, the second variable may be set to include an identifier of radio configuration 1 (e.g., 1), an identifier of radio configuration 2 (e.g., 2), and an identifier of radio configuration 3 (e.g., 3). If the radio configuration in the source cell is updated, replaced, or reconfigured in the process of applying the first reference configuration and the delta configuration of the target cell, the identifier of the updated, replaced, or reconfigured radio configuration is deleted from the second variable. For example, if the aforementioned update, replacement, or reconfiguration process is performed on radio configuration 1 of the source cell, the identifier of radio configuration 1 (1) is deleted from the second variable, and the identifier variables of the radio configurations included in the second variable are the identifier of radio configuration 2 (e.g., 2) and the identifier of radio configuration 3 (e.g., 3). Then, in the radio configuration of the terminal, the terminal may release radio configuration 2 and radio configuration 3. For example, the radio configuration is an RLC bearer configuration. If radio configuration 1 is an RLC bearer configuration whose LCID value is 1, the identifier of radio configuration 1 is an LCID whose value is 1. If radio configuration 2 is an RLC bearer configuration whose LCID value is 2, the identifier of radio configuration 2 is an LCID whose value is 2. If radio configuration 3 is an RLC bearer configuration whose LCID value is 3, the identifier of radio configuration 3 is an LCID whose value is 3. In another example, the radio configuration is a DRB configuration. If radio configuration 1 is a DRB configuration whose DRB identifier is 1, the identifier of radio configuration 1 is DRB1 whose value is 1. If radio configuration 2 is a DRB configuration whose DRB identifier is 2, the identifier of radio configuration 2 is DRB2 whose value is 2. If radio configuration 3 is a DRB configuration whose DRB identifier is 3, the identifier of radio configuration 3 is DRB3.

[0198] For example, the radio configuration includes an RLC bearer configuration and / or a DRB configuration. Embodiment 2 provides a solution. The gist of the solution is that the terminal first applies a first reference configuration, and then applies a delta configuration of the target cell based on the first reference configuration. For processing the RLC bearer, a fourth variable is introduced, which stores the RLC bearer that needs to be released in the radio configuration of the source cell in the LTM handover process. For processing the DRB, a fifth variable is introduced, which stores the DRB bearer that needs to be released in the radio configuration of the source cell in the LTM handover process. The fourth variable or the fifth variable is a specific implementation of the above-mentioned second variable. The solution includes the following steps:

[0199] 1: The terminal receives an RRC reconfiguration message from an access network device, and the RRC reconfiguration message includes configuration information of an LTM candidate cell.

[0200] This is the same as the process of embodiment 1. The RRC reconfiguration message includes an LTM candidate cell configuration and optionally further includes a first reference configuration. The LTM candidate cell configuration includes configuration information of one or more LTM candidate cells. For detailed process descriptions, please refer to the description of embodiment 1.

[0201] 2: The terminal receives an LTM handover command from the access network device, where the LTM handover command includes information about the target cell.

[0202] It should be appreciated that the target cell in the LTM handover command may be one of the LTM candidate cells configured by the access network device for the terminal.

[0203] 3: The terminal performs an LTM handover.

[0204] The terminal performs handover from the source cell to the target cell based on the information about the target cell included in the LTM handover command.

[0205] Optionally, when the configuration of the LTM candidate cell is a delta configuration with respect to the first reference configuration, for example, the configuration of the LTM candidate cell may be referred to as a delta configuration of the LTM candidate cell. For example, the configuration of the target cell for handover may be referred to as a delta configuration of the target cell.

[0206] Optionally, the terminal obtains the first reference configuration and the delta configuration of the LTM candidate cell from the third variable, and the delta configuration of the target cell is obtained from the delta configuration of the LTM candidate cell.

[0207] When the terminal receives an LTM handover command of the access network device, the terminal may first apply the first reference configuration and then apply the delta configuration of the target cell.

[0208] For example, the terminal may not release entities related to the radio configuration when applying the first reference configuration, and may apply the first reference configuration based on the radio configuration of the current configuration. For example, the first reference configuration may include a radio configuration addition / modification list. For an identifier of a radio configuration included in the radio configuration addition / modification list, if the identifier of the radio configuration is also included in the current configuration of the terminal, the configuration information of the radio configuration in the current configuration of the terminal is replaced with the configuration information of the radio configuration in the radio configuration addition / modification list. Alternatively, if the identifier of a radio configuration included in the radio configuration addition / modification list is not included in the current configuration of the terminal, the terminal creates a radio configuration or creates entities related to the radio configuration and configures parameters related to the radio configuration. When applying the first reference configuration or before applying the first reference configuration, the terminal releases configurations other than the radio configuration in the reference configuration. Optionally, the terminal applies a default configuration and then applies the first reference configuration. After the first reference configuration is applied through the above process, the current configuration of the terminal may be referred to as the second reference configuration. The delta configuration of the target cell is applied based on the second reference configuration. Optionally, the delta configuration of the target cell may include a radio configuration addition / modification list and / or a radio configuration release list. The terminal replaces and / or creates a second reference configuration based on the radio configuration addition / modification list. The terminal releases the corresponding radio configuration in the second reference configuration based on the radio configuration release list, etc. Optionally, a variable may be set, which may be a fourth variable or a fifth variable, for determining a radio configuration that the terminal needs to release in the handover process and that is included in the source cell but not in the target cell. An initial value of the fourth or fifth variable includes an identifier of the radio configuration of the source cell. In other words, before the terminal applies the radio configuration in the first reference configuration, the fourth or fifth variable includes an identifier of the radio configuration of the source cell.

[0209] In this embodiment of the present application, the process in which the terminal applies the first reference configuration and the delta configuration of the target cell has many similar processes. In this embodiment of the present application, the process in which the terminal applies the first reference configuration and the delta configuration of the target cell are described together.

[0210] (1) If the first reference configuration or the delta configuration of the target cell includes a cell group configuration, the terminal performs a cell group configuration process.

[0211] Optionally, the terminal performing the cell group configuration process may be understood as the terminal applying the cell group configuration in the first reference configuration or the delta configuration of the target cell.

[0212] When the terminal performs the process of applying the first reference configuration, the terminal releases the terminal's current cell group configuration in the cell group configuration except for at least one of the MCG C-RNTI or the RLC bearer configuration. Optionally, when the terminal performs the process of applying the first reference configuration, the terminal sets a fourth variable, where the fourth variable includes an LCID list of the cell group RLC bearers in the terminal's current configuration, where the list includes one or more LCIDs. It should be understood that the terminal's current configuration here refers to the terminal's configuration in the source cell, the configuration before the terminal applies the first reference configuration, or the configuration when the terminal applies the first reference configuration.

[0213] Optionally, if the terminal applies the delta configuration of the LTM target cell, or if the terminal does not perform the LTM process, and the cell group configuration includes synchronous reconfiguration, the terminal performs a synchronous reconfiguration process. Optionally, for the synchronous reconfiguration process, see the protocol description.

[0214] If the cell group configuration includes an RLC bearer addition / modification list, an RLC bearer addition / modification process is performed. The RLC bearer addition / modification list includes configuration information for one or more RLC bearers. The configuration information for each RLC bearer includes at least the LCID of the RLC bearer. The value of the LCID may be any positive integer between 1 and 65855. Optionally, the RLC bearer configuration may further include at least one of, but not limited to, a serving radio bearer, an RLC re-establishment indication, an RLC configuration, a MAC logical channel configuration, etc.

[0215] In one embodiment, the RLC bearer addition / modification process includes: For the configuration information of each RLC bearer in the RLC bearer addition / modification list:

[0216] Optionally, if the terminal's current configuration includes an LCID value associated with an RLC bearer, the LCID value is included in the RLC bearer addition / modification list, and the RLC bearer associated with the LCID in the terminal's current configuration and the RLC bearer associated with the LCID in the RLC bearer addition / modification list belong to the same cell group, then when the terminal receives an RLC re-establishment indication from the access network device, the terminal re-establishes the RLC entity.

[0217] If the terminal's current configuration includes an LCID value associated with an RLC bearer, the LCID value is included in the RLC bearer addition / modification list, and optionally, if the RLC bearer associated with the LCID in the terminal's current configuration and the RLC bearer associated with the LCID in the RLC bearer addition / modification list belong to the same cell group, when the terminal is in the process of applying the first reference configuration, the current terminal configuration of the RLC entity is replaced with the RLC configuration in the configuration information of the RLC bearer in the RLC bearer addition / modification list. Optionally, the current terminal configuration of the logical channel is replaced with the configuration in the MAC logical channel configuration in the RLC bearer addition / modification list, and the LCID value is deleted from the fourth variable.

[0218] If the terminal's current configuration includes an LCID value associated with an RLC bearer, the LCID value is included in the RLC bearer addition / modification list, and optionally, if the RLC bearer associated with the LCID in the terminal's current configuration and the RLC bearer associated with the LCID in the RLC bearer addition / modification list belong to the same cell group, and if the terminal is in the process of applying a delta configuration of the target cell and the first reference configuration does not include configuration information for the RLC bearer having the LCID value, the current terminal configuration of the RLC entity is replaced with the RLC configuration in the configuration information of the RLC bearer in the RLC bearer addition / modification list. Optionally, the current terminal configuration of the logical channel is replaced with the configuration in the MAC logical channel configuration in the RLC bearer addition / modification list, and the LCID value is deleted from the fourth variable.

[0219] If the terminal does not apply the first reference configuration and does not apply the delta configuration of the target cell, the RLC entities are reconfigured based on the received RLC configuration and the logical channels are reconfigured based on the received MAC logical channels. Alternatively, the terminal performs a process of applying the delta configuration of the target cell, where the RLC bearer addition / modification list in the delta configuration of the target cell includes an LCID value, the LCID value is included in the RLC bearer addition / modification list in the first reference configuration, the RLC entities are reconfigured based on the received RLC configuration and the logical channels are reconfigured based on the received MAC logical channels.

[0220] If the RLC bearer addition / modification list in the first reference configuration or the target cell configuration includes an LCID value and the LCID value is not included in the terminal's current configuration, and optionally not in the same cell group, an RLC entity is established. Optionally, in one embodiment, if the RLC bearer addition / modification list in the first reference configuration or the target cell configuration includes an LCID value and the LCID value is not included in the terminal's current configuration, and optionally not in the same cell group, and the serving radio configuration bearer is associated with an SRB logical channel and does not include an RLC configuration, the terminal establishes an RLC entity based on the SRB default configuration; otherwise, the terminal establishes an RLC entity based on the received RLC configuration. If the serving radio bearer associates a logical channel with an SRB and does not include a MAC logical channel configuration, the terminal configures a logical channel for the MAC entity based on the SRB default configuration; otherwise, the terminal configures a logical channel for the MAC entity based on the SRB default configuration; A logical channel is associated with a PDCP entity identified by a serving radio bearer or a serving mobile base station (MBS) radio bearer.

[0221] In another embodiment, the RLC bearer addition / modification process includes at least one of the following, but is not limited to: If the RLC bearer addition / modification list includes an LCID value and the LCID value does not belong to the identifier of an RLC bearer in the terminal's current configuration, an RLC bearer is created based on the RLC bearer corresponding to the LCID value included in the RLC bearer modification list; or If the terminal's current configuration includes an RLC bearer received in the same cell group and having an LCID identifier, when the terminal receives an RLC re-creation instruction from the access network device, the terminal recreates the RLC entity. Alternatively, when the terminal applies the first reference configuration, or when the terminal performs a process of applying a delta configuration of a target cell, and the cell group configuration of the same cell group in the first reference configuration does not include any RLC bearer configuration with the LCID value received in the target cell configuration, i.e., if the RLC bearer is included in the LTM target cell configuration but not in the first reference configuration, the current terminal configuration of the RLC entity is replaced with the RLC bearer configuration in the first reference configuration or in the delta configuration of the target cell, and the current terminal MAC logical channel of the logical channel is replaced with the configuration in the MAC logical channel, etc., and the logical channel identifier is deleted from the fourth variable. Alternatively, If the terminal does not apply the LTM first reference configuration and does not apply the delta configuration of the LTM target cell, the terminal reconfigures the RLC entities based on the received RLC configuration and reconfigures the logical channels based on the received MAC logical channels. Alternatively, the terminal performs a process of applying the delta configuration of the target cell, where the RLC bearer addition / modification list in the delta configuration of the target cell includes an LCID value, the LCID value is included in the RLC bearer addition / modification list in the first reference configuration, the RLC entities are reconfigured based on the received RLC configuration, and the logical channels are reconfigured based on the received MAC logical channels. Alternatively, If a logical channel associated with a logical channel identifier value in the first reference configuration or the target cell's delta configuration is not configured in the same cell group of the terminal's current configuration, if the serving radio configuration bearer is associated with the logical channel of an SRB and does not include an RLC configuration, the terminal creates an RLC entity based on the default configuration of the SRB; otherwise, the terminal creates an RLC entity based on the received RLC configuration. If the serving radio bearer associates a logical channel with an SRB and does not include a MAC logical channel configuration, the logical channel is configured for the MAC entity based on the default configuration of the SRB. Otherwise, the logical channel is configured for the MAC entity based on the received MAC logical channel configuration. The logical channel is associated with the PDCP entity of the radio bearer identifier of the serving radio bearer or serving MBS.

[0222] Optionally, if the cell group configuration includes an RLC bearer release list, an RLC bearer release process is performed; or Optionally, when the terminal performs a process of applying the delta configuration of the target cell, the terminal releases the RLC bearer corresponding to the RLC bearer identifier included in the fourth variable. Optionally, the fourth variable is cleared or released.

[0223] The RLC Bearer Addition / Modification List indicates the RLC entities and corresponding MAC logical channels that need to be released by the terminal. The RLC Bearer Addition / Modification List contains one or more LCIDs.

[0224] The RLC bearer release process includes: for each logical channel identifier included in the RLC bearer release list, which identifier is part of the terminal's current configuration in the same cell group, an RLC entity is released and the corresponding logical channel is released, for each logical channel identifier released due to the release of a secondary cell group (SGC), or for each logical channel identifier to be released during the processing of an LTM target cell configuration, an RLC entity is released and the corresponding logical channel is released.

[0225] If the cell group includes a MAC configuration for the cell group, the MAC entity of the cell group is configured.

[0226] (2) If the first reference configuration or the delta configuration of the target cell includes a radio bearer configuration, the terminal performs a radio bearer configuration process.

[0227] The radio bearer configuration process includes:

[0228] When the terminal performs the process of applying the first reference configuration, the fifth variable is set to the DRB identifier list in the terminal's current configuration. For example, the fifth variable may be referred to as a DRB release variable. If the radio bearer configuration includes an SRB addition / modification list or if a dual active protocol stack (DAPS) bearer is configured, the terminal performs an SRB addition or reconfiguration. When the terminal performs an SRB addition or reconfiguration, the terminal performs an SRB addition / modification process.

[0229] If the radio bearer configuration includes a DRB release list, the terminal performs a DRB release process.

[0230] If the radio bearer configuration includes a DRB addition / modification list, the terminal performs a DRB addition or reconfiguration process.

[0231] Optionally, the terminal instructs upper layers to release all SDAP entities that do not have an associated DRB and, if present, release user plane resources of protocol data unit (PDU) sessions associated with the released SDAP entities. Optionally, the terminal instructs upper layers to release all SDAP entities that do not have an associated multicast MRB and release user plane resources of MRB multicast.

[0232] The SRB addition / modification process includes at least the following: for SRB values ​​included in the SRB addition / modification list and not part of the current terminal configuration, if a PDCP entity is established and access stratum (AS) security is activated, the PDCP entity is configured by using a security algorithm based on the security configuration, applying a key associated with the master or secondary key indicated by the access network device; if a PDCP configuration is included, the PDCP entity is configured based on the received PDCP configuration; if no PDCP configuration is included, the PDCP entity is configured by default based on the corresponding SRB.

[0233] For SRB values ​​included in the SRB addition / modification list that is part of the terminal's current configuration, optionally, if PDCP is configured to be re-established, the PDCP entity is configured to apply the indicated integrity protection algorithm and key associated with the master key or secondary key, and the PDCP entity is configured to apply the indicated encryption algorithm and key associated with the master key or secondary key to re-establish the PDCP entity for the SRB; optionally, if PDCP is configured to be discarded, the PDCP entity is triggered to perform service data unit (SDU) discard; and optionally, if the PDCP configuration is included, if the terminal applies a first reference configuration, the terminal replaces the PDCP entity's current terminal configuration with the PDCP configuration associated with the SRB identifier in the SRB addition / modification list in the first reference configuration; otherwise, if the terminal applies a delta configuration of the target cell or if the terminal does not perform an LTM process, the terminal reconfigures the PDCP entity based on the received PDCP configuration.

[0234] The DRB release process includes at least the following: for each DRB identifier value included in a DRB release list that is part of the current terminal configuration, for each DRB identifier value that has been released because full configuration has been performed, for a DRB identifier value that needs to be released when delta configuration of the first target cell is performed or processed, or optionally, for an identifier value of a DRB that needs to be released when delta configuration of the first target cell is performed or processed, where the fifth variable in the process is a DRB identifier value, the terminal releases the PDCP entity and the DRB identifier, and if an SDAP entity associated with the DRB is configured, releases the DRB-to-SDAP association associated with the DRB, i.e., deletes all quality of service (QoS) flow-to-DRB mappings associated with the DRB, and if the DRB is associated with an evolved packet system (EPS) bearer identifier, instructs upper layers to release the DRB and the EPS bearer identifier of the DRB if a new bearer is not added with the same ESP bearer identifier.

[0235] The DRB addition / modification process includes the following: For DRB identifier values ​​included in the DRB addition / modification list and not belonging to the current terminal configuration, DRB establishment is performed. The DRB establishment includes the establishment of a PDCP entity and configuration based on the received PDCP configuration.

[0236] The DRB addition / modification process further includes the following: for each DRB identifier value included in the DRB addition / modification list used as part of the current terminal and not configured as a DAPS bearer, optionally, if the PDCP re-establishment indication is set and the PDCP entity of the DRB is not configured with a disabled configuration, configure an encryption algorithm and key associated with a master key or a secondary key for the PDCP entity; if the PDCP re-establishment indication is set and the PDCP entity of the DRB is configured with integrity protection, configure an integrity protection algorithm for the PDCP entity based on the security configuration, and apply the integrity protection key associated with the master key or a secondary key. Optionally, if the PDCP re-establishment indication is set and the PDCP configuration includes DRB robust header compression (ROHC) continuity, the RRC layer of the terminal indicates to lower layers that DRB ROHC continuity is configured. Optionally, if the PDCP re-establishment indication is set and the PDCP configuration includes DRB downlink Ethernet header compression (EHC) continuity, the lower layer is instructed that DRB downlink EHC continuity is configured. Optionally, if the PDCP re-establishment indication is set and the PDCP configuration includes DRB UDC continuity, the lower layer is instructed that DRB downlink UDC continuity is configured, or if the PDCP re-establishment indication is set, the terminal re-establishes the PDCP entity of the DRB. Optionally, if PDCP recovery is set, the terminal triggers the PDCP entity of the DRB to perform data recovery. For each DRB used as part of the current terminal, if an identifier value included in the DRB addition / modification list includes an associated PDCP configuration, when the terminal applies the first reference configuration, the current terminal configuration of the PDCP entity is replaced with the PDCP configuration associated with the DRB identifier value in the DRB addition / modification list, and the DRB identifier is deleted from the fifth variable.If an identifier value included in the DRB addition / modification list of each DRB used as part of the current terminal includes an associated PDCP configuration, and the terminal performs a delta configuration process for the target cell, and the first reference configuration does not include a PDCP configuration associated with the DRB identifier value in the target cell configuration, which can be understood as the DRB identifier value and the associated PDCP configuration being included in the target configuration but not included in the first reference configuration, the current terminal configuration of the PDCP entity is replaced with the PDCP configuration associated with the DRB identifier value in the DRB addition / modification list, and the DRB identifier value is deleted from the fifth variable. If an identifier value included in the DRB addition / modification list of each DRB used as part of the current terminal includes an associated PDCP configuration, and the terminal does not perform an LTM process, the PDCP entity is reconfigured based on the received PDCP configuration. For each DRB identifier value included in the DRB addition / modification list used as part of the current terminal, if an associated PDCP configuration is included, and if the terminal applies the delta configuration of the LTM target cell and the first reference configuration does not include a PDCP associated with the DRB identifier value in the delta configuration of the target cell, the PDCP entity is reconfigured based on the received PDCP configuration in the delta configuration of the target cell. Optionally, if an SDAP configuration is included, the SDAP entity is reconfigured based on the received SDAP configuration. Optionally, for each QFI value added to the mapping QoS flow addition field, if a QoS flow identifier (QFI) value was previously configured, the QFI value is released in the old DRB.

[0237] (3) When the terminal performs the process of applying the delta configuration of the LTM target cell, the terminal releases the DRB identifier value included in the fifth variable and releases the corresponding PDCP entity.

[0238] (4) Optionally, if the first reference configuration or the target cell configuration includes a measurement configuration, the terminal performs a measurement configuration process. For details about the measurement configuration process, please refer to the protocol.

[0239] Optionally, when the terminal applies a first reference configuration and the first reference configuration includes a measurement configuration, performing measurement configuration by the terminal may further include releasing / clearing a current terminal measurement configuration of the associated cell group, including at least one of releasing a measurement configuration report, releasing a measurement configuration variable, stopping any ongoing periodic reporting, stopping timer T321, or stopping timer T322. Optionally, performing measurement configuration by the terminal may further include performing measurement object addition / modification if the measurement configuration of the first reference configuration includes a measurement object addition / modification list, performing measurement object deletion if the measurement configuration includes a measurement object deletion list, performing measurement report configuration addition / modification if the measurement configuration includes a measurement report configuration addition / modification list, performing measurement report configuration deletion if the measurement configuration includes a measurement report configuration deletion list, performing a measurement quantity configuration process if the measurement configuration includes a measurement quantity configuration, performing measurement identifier addition / modification if the measurement configuration includes a measurement identifier addition / modification list, or performing measurement identifier deletion if the measurement configuration includes a measurement identifier deletion list.

[0240] In embodiment 2, a new handover target cell application process is introduced for the LTM process. In the process of a terminal performing an LTM cell handover, the terminal applies a first reference configuration and then applies a delta configuration of the target cell to ensure that the terminal can accurately apply the target cell configuration and perform the handover process to the target cell, thereby ensuring a handover success rate. Furthermore, when the LTM target cell configuration is applied, a new processing process is introduced for configurations that affect service continuity (e.g., RLC bearer, radio bearer, and SCell configuration). Because the configuration of the source cell and the configuration of the target cell are compared, the terminal does not perform an unnecessary "release and add" process for configurations that affect service continuity and are included in both the source cell and the target cell in the handover process. For example, when the terminal applies the target configuration based on the first reference configuration, this avoids unnecessary release and addition of RLC bearers or radio bearers that are included in both the terminal's current configuration and the target configuration in the LTM execution process, thereby improving LTM handover performance and reducing handover interruptions and handover delays.

[0241] [Embodiment 3] The difference between embodiment 3 and embodiment 1 is that in embodiment 1, the terminal first applies the first reference configuration and then applies the delta configuration of the target cell. In embodiment 3, the terminal generates a configuration of the target cell based on the first reference configuration and the delta configuration of the target cell. The terminal applies the configuration of the target cell. For example, the terminal generates the configuration of the target cell based on the first reference configuration and the delta configuration of the target cell. Optionally, the configuration of the target cell may be the full configuration of the target cell in embodiment 3. The terminal replaces the current radio configuration of the terminal with the radio configuration in the configuration of the target cell.

[0242] For example, the terminal generating the configuration of the target cell includes: if the sixth variable includes the first reference configuration, reconfiguring the sixth variable based on the delta configuration of the target cell, where the reconfigured sixth variable is the generated configuration of the target cell; or if the sixth variable is empty, reconfiguring the sixth variable based on the first reference configuration to obtain a seventh variable, and reconfiguring the seventh variable based on the delta configuration of the target cell, where the reconfigured seventh variable is the generated configuration of the target cell.

[0243] It will be appreciated that if the measurement configuration in the target cell configuration is the same as the measurement configuration in the current terminal configuration, the terminal will retain the current measurement results.

[0244] In one design, the terminal applying the full configuration of the target cell includes the terminal releasing current configuration information of the terminal except for at least one of an MCG C-RNTI, an access stratum security configuration, an RB configuration, an RLC bearer configuration, an SCell configuration, or a recorded measurement configuration. The terminal maintains first variables, the first variables including a first reference configuration, updates the first variables based on a delta configuration of the target cell, the updated first variables including a full radio configuration of the target cell, and determines a radio configuration of the terminal in the target cell based on the updated first variables.

[0245] In another design, the terminal applying the complete target cell configuration includes, but is not limited to, at least one of the following processes: the terminal releasing the terminal's current configuration information except for at least one of the MCG C-RNTI, the access stratum security configuration, the RB configuration, the RLC bearer configuration, the SCell configuration, or the recorded measurement configuration; the terminal applying default L1 parameter values ​​except for parameters provided in SIB1; and the terminal applying a default MAC configuration for the cell group. Alternatively, if the target cell configuration includes a master cell group configuration, a cell group configuration process is performed; if the first reference configuration includes a secondary cell group configuration, a cell group configuration process is performed; if the measurement configuration is included, a measurement configuration process is performed; if a dedicated NAS message list is included, each information element in the list is forwarded to an upper layer; or if dedicated system information is included, an operation of receiving system information is performed. The terminal does not need to maintain the first variable. The terminal compares the radio configuration in the complete configuration of the target cell with the radio configuration of the terminal in the source cell, i.e., the terminal compares the radio configuration in the complete configuration of the target cell with the radio configuration in the current configuration of the terminal to determine the radio configuration of the terminal in the target cell. Alternatively, the terminal maintains a first variable, and the terminal compares the radio configuration in the complete configuration of the target cell with the radio configuration in the current configuration of the terminal to determine the radio configuration of the terminal in the target cell. In other words, the terminal replaces the current radio configuration of the terminal with the radio configuration of the target cell, thereby avoiding unnecessary releases and additions.

[0246] The radio configuration of the terminal may include at least one of an RLC bearer configuration, a DRB bearer configuration, an SRB bearer configuration, or an SCell configuration.

[0247] An example is used in which the radio configuration of the terminal is an RLC bearer configuration. An embodiment of the present application provides a solution including the following steps:

[0248] 1: The terminal receives an RRC reconfiguration message from an access network device, and the RRC reconfiguration message includes configuration information of an LTM candidate cell.

[0249] 2: The terminal receives an LTM handover command from the access network device, where the LTM handover command includes information about the target cell.

[0250] 3: The terminal performs an LTM handover from the source cell to the target cell.

[0251] The terminal applying the complete target cell configuration includes, but is not limited to, at least one of the following processes: the terminal releasing the terminal's current configuration information excluding at least one of the MCG C-RNTI, the access stratum security configuration, the RB configuration, the RLC bearer configuration, the SCell configuration, or the recorded measurement configuration; the terminal applying default L1 parameter values ​​excluding parameters provided in SIB1; and the terminal applying a default MAC configuration for the cell group. Alternatively, if the target cell configuration includes a master cell group configuration, a cell group configuration process is performed; if the first reference configuration includes a secondary cell group configuration, a cell group configuration process is performed; if the measurement configuration is included, a measurement configuration process is performed; if a dedicated NAS message list is included, each information element in the list is forwarded to an upper layer; or if dedicated system information is included, an operation of receiving system information is performed.

[0252] In one implementation process, the process of determining the radio configuration in the cell group configuration process is the same as the first variable in embodiment 1. For specific implementation, please refer to embodiment 1.

[0253] In another implementation process, the cell group configuration process may include the terminal performing an RLC bearer processing process when the LTM process is running. This process is the same as the RLC processing principle in embodiment 1, but the implementation of the terminal is different. For an LCID of an RLC bearer configuration of a target cell, if the RLC bearer configuration of a source cell includes an RLC bearer with the same LCID and the two RLC bearers belong to the same cell group, the RLC bearer with the same LCID is reconfigured in the current configuration of the terminal by using the RLC bearer of the target cell. In one understanding, reconfiguring an RLC bearer with the same LCID in the current configuration of the terminal by using the RLC bearer of the target cell means replacing the current RLC bearer configuration of the terminal with the RLC bearer configuration of the target cell. For an LCID of an RLC bearer configuration of a target cell, if an RLC bearer with the same LCID does not exist in the RLC bearer of the source cell, an RLC bearer corresponding to the LCID is created in the current configuration of the terminal. For the LCID of an RLC bearer in the source cell, if an RLC bearer corresponding to the LCID does not exist in the RLC bearer of the target cell, the RLC bearer corresponding to the LCID is released in the current configuration of the terminal. If the LTM process is not running, if the cell group configuration includes an RLC bearer release list, an RLC bearer release process is performed. If the cell group configuration includes an RLC bearer addition / modification list, an RLC bearer addition / modification process is performed. If the cell group configuration includes a MAC configuration for the cell group, the MAC entity of the cell group is configured.

[0254] 4: The terminal performs a RACH or RACH-less process with the target cell.

[0255] In embodiment 3, in the process of performing an LTM cell handover by a terminal, the terminal generates a complete target cell configuration based on the first reference configuration and the delta configuration of the target cell, and then applies a complete configuration process for the target cell. Therefore, the terminal can accurately apply the target cell configuration to perform a handover to the target cell, thereby improving the handover success rate. When the LTM target cell configuration is applied, the configuration of the source cell and the configuration of the target cell are compared for configuration parameters (e.g., RLC bearers) that affect service continuity. Therefore, the terminal does not perform an unnecessary "release and add" process for configurations that affect service continuity and are included in both the source cell and the target cell in the handover process. For example, when the terminal applies the target configuration based on the first reference configuration, this avoids unnecessary release and addition of RLC bearers or radio bearers that are included in both the terminal's current configuration and the target configuration in the LTM execution process, thereby improving LTM handover performance and reducing handover interruptions and handover delays.

[0256] [Embodiment 4] The gist of embodiment 4 is as follows: When a terminal receives an LTM handover command, the terminal determines a full configuration of the target cell based on the first reference configuration and the delta configuration of the target cell, and the terminal applies the full configuration of the target cell.

[0257] In one embodiment, applying the full configuration of the target cell by the terminal includes the terminal applying the full radio configuration of the target cell. Applying the full radio configuration of the target cell by the terminal includes the terminal determining a radio configuration addition / modification list and / or a radio configuration release list based on the radio configuration of the target cell and the radio configuration of the source cell, the radio configuration addition / modification list and / or the radio configuration release list being a delta configuration based on the source cell, and applying the radio configuration of the target cell based on the radio configuration addition / modification list and / or the radio configuration release list.

[0258] An example is used in which the radio configuration of the terminal is an RLC bearer. An embodiment of the present application provides a solution including the following steps:

[0259] 1: The terminal receives an RRC reconfiguration message from an access network device, and the RRC reconfiguration message includes configuration information of an LTM candidate cell.

[0260] 2: The terminal receives an LTM handover command from the access network device, where the LTM handover command includes information about the target cell.

[0261] 3: The terminal performs an LTM handover from the source cell to the target cell.

[0262] The terminal generates a full configuration of the target cell based on the first reference configuration and the delta configuration of the target cell. The terminal generates a new delta configuration of the target cell by comparing the configuration of the source cell with the configuration of the target cell. The new delta configuration of the target cell is a delta configuration based on the configuration of the source cell. The new delta configuration of the target cell includes a new RLC bearer addition / modification list and / or a new RLC bearer release list. The new RLC bearer addition / modification list and / or the new RLC bearer release list are delta configurations based on the RLC bearer configuration of the source cell of the terminal.

[0263] 4: The terminal applies the complete target cell configuration, which includes but is not limited to the following processes:

[0264] The terminal releases its current configuration information except for at least one of the MCG C-RNTI, access stratum security configuration, RB configuration, RLC bearer configuration, SCell configuration, or recorded measurement configuration. The terminal applies default L1 parameter values ​​except for parameters provided in SIB1. The terminal applies the default MAC configuration for the cell group.

[0265] If the complete radio configuration of the target cell includes a master cell group configuration, a cell group configuration process is performed, which includes the following: If the LTM process is running, for each RLC bearer included in the RLC bearer addition / modification list, if the current configuration of the terminal includes an RLC bearer that belongs to the same cell group and has the same LCID value, the RLC entity is reconfigured, otherwise an RLC entity is created. For each RLC bearer included in the RLC bearer release list, if the LCID of the RLC bearer is part of the current terminal configuration, the RLC entity associated with the LCID is released and the corresponding logical channel is released.

[0266] If the cell group configuration includes a MAC configuration for the cell group, the MAC entity of the cell group is configured. If the full configuration of the target cell includes a secondary cell group configuration, the cell group configuration process is performed. If a measurement configuration is included, the measurement configuration process is performed. If a dedicated NAS message list is included, each information element in the list is forwarded to higher layers. If dedicated system information is included, an operation to receive system information is performed.

[0267] 5: The terminal performs a RACH or RACH-less process with the target cell to maintain synchronization with the target cell.

[0268] According to the aforementioned embodiment 4, in the process of performing LTM cell handover, the terminal can accurately apply the target cell configuration and perform the process of handover to the target cell, thereby improving the handover success rate. When the target cell configuration is applied, for configuration parameters (e.g., RLC bearers) that affect service continuity, the terminal generates a new delta configuration based on the source cell configuration to avoid the terminal's unnecessary "release and add" process, thereby improving LTM handover performance and reducing handover interruptions and handover delays.

[0269] [Embodiment 5] Embodiment 5 provides a handover procedure including the following steps:

[0270] 1: The terminal reports a measurement report based on the measurement configuration. The measurement configuration and report may be an L3 measurement configuration and report, or may be configured by the CU.

[0271] 2: The CU makes a handover decision and decides to perform an L1 / L2 handover.

[0272] Optionally, the access network device may make a handover decision based on measurement results reported by the terminal and / or a handover algorithm of the access network device. The CU sends a terminal context setup request message to one or more candidate DUs.

[0273] Optionally, the CU transmits one or more reference configurations to the candidate DU. The reference configurations are used by the candidate DU to determine delta configurations of one or more candidate cells based on the reference configurations, or the reference configurations are used by the candidate DU to determine configurations of one or more LTM candidate cells. For example, the CU transmits multiple reference configurations, referred to herein as third reference configurations, to the candidate DU. The third reference configuration is a general term for reference configurations transmitted by the CU to the candidate DU, and the third reference configuration is not specifically one reference configuration. It will be understood that, optionally, when the CU transmits multiple reference configurations to the candidate DU, the multiple reference configurations may be different configurations, i.e., the multiple third reference configurations may be understood as multiple third reference configurations including different configuration contents.

[0274] The reference configuration may be empty or non-empty. If the reference configuration is non-empty, it includes a first radio resource configuration. Optionally, in another embodiment, the first radio resource configuration includes a radio configuration. For the radio configuration, see the above description. The first radio resource configuration is one or more information elements in a second radio resource configuration included in a candidate cell configuration. For example, if specified, the second radio resource configuration included in a candidate cell configuration may include a cell group configuration, a radio bearer configuration, and a measurement configuration, and the first radio resource configuration may include a cell group configuration, a radio bearer configuration, and / or a measurement configuration. Each configuration in a radio resource configuration may be referred to as an information element, i.e., the radio resource configuration includes one or more information elements. For example, the cell group configuration is an information element, and the radio bearer configuration is also an information element in the radio resource configuration. Information elements not included in the second radio resource configuration are not included in the reference configuration.

[0275] 1: The candidate DU performs admission control. If the candidate DU determines that the terminal is allowed to access, the candidate DU sends a terminal context setup request acknowledgment message to the CU, and the terminal context setup request acknowledgment message may include configuration information of the LTM candidate cell.

[0276] Each candidate DU and / or CU determines a delta configuration based on the reference configuration for each candidate cell of the candidate DU based on the reference configuration. Alternatively, if the candidate DU and / or CU cannot understand, decode, or identify the reference configuration, the candidate DU and / or CU provides the complete configuration of the candidate cell to the candidate cell under the candidate DU. The complete configuration of the candidate cell may also refer to the candidate cell configuration in step 2. In one understanding, the complete configuration of the candidate cell includes the complete second radio resource configuration. Alternatively, in another understanding, the complete configuration of the candidate cell may be the complete second radio resource configuration obtained based on the reference configuration and the delta configuration. Alternatively, the complete configuration of the candidate cell includes the second radio resource configuration and the third radio resource configuration. Alternatively, in another understanding, the complete configuration of the candidate cell includes a complete RRC reconfiguration information element. Optionally, if the configuration of the candidate cell is the complete configuration, the terminal performs a replacement operation when LTM is performed, and optionally, the terminal does not need to clear the current configuration. For example, an RLC configuration and / or a PDCP configuration in the full configuration of a candidate cell is intended to replace an RLC configuration and / or a PDCP configuration having the same identifier in the current terminal configuration. For example, if the logical channel identifier of an RLC bearer in the full configuration of a candidate cell is the same as the logical channel identifier associated with the RLC bearer in the current terminal configuration, when LTM is performed, the RLC configuration having the same logical channel identifier in the current terminal configuration is replaced with the RLC configuration in the full configuration of the candidate cell associated with the logical channel identifier. As another example, if the RB identifier in the full configuration of a candidate cell is the same as the RB identifier in the current terminal configuration, when LTM is performed, the configuration (e.g., a PDCP configuration) associated with the RB identifier in the full configuration of the candidate cell is intended to replace a configuration (e.g., a PDCP configuration) having the same RB identifier in the current terminal configuration. The network (i.e., candidate DU and / or CU) may configure all candidate cells with a delta configuration based on a non-empty reference configuration, or may configure all candidate cells with a full configuration.Alternatively, the network may configure the candidate cell with a full configuration including a fullconfig instruction (the fullconfig instruction may also be called a fullconfig instruction or written as fullConfig, see the standard protocol for an explanation), or a hybrid configuration (specifically, a hybrid configuration where two or three of the candidate cell configurations are delta configurations, the candidate cell configuration is a full configuration, and the candidate cell configuration is a full configuration including a fullconfig instruction).

[0277] Optionally, to enable the terminal to know whether each candidate cell configuration is a delta configuration, a full configuration, or a full configuration including a fullconfig indication, when configuring LTM candidate cells for the terminal, the network may include indication information to indicate which of the three configurations each LTM candidate cell configuration is. This operation has the beneficial effect that the terminal can accurately determine the configuration (delta configuration, full configuration, or full configuration) of each candidate cell, so that a complete candidate cell configuration can be accurately determined or generated for each candidate cell, and the candidate cell configuration can be correctly applied, thereby ensuring the success of handover.

[0278] The access network device may instruct the configuration of each LTM candidate cell based on at least one of the following indication information:

[0279] Scheme 1: The indication information may be a preset bit for indicating whether the candidate cell configuration is a delta configuration or a full configuration. For example, in the case of one-bit indication information, when the value of the one-bit indication information is 1, it indicates that the LTM candidate cell configuration is a delta configuration based on a reference configuration, and when the value of the one-bit indication information is 0, it may indicate that the LTM candidate cell configuration is a full configuration. Alternatively, when the value of the one-bit indication information is 0, it may indicate that the LTM candidate cell configuration is a delta configuration based on a reference configuration, and when the value of the one-bit indication information is 1, it may indicate that the LTM candidate cell configuration is a full configuration. Alternatively, when the value of the one-bit indication information is true, it indicates that the LTM candidate cell configuration is a delta configuration based on a reference configuration, or when the value of the one-bit indication information is true, it indicates that the LTM candidate cell configuration is a full configuration.

[0280] Method 2: New indication information indicates whether the candidate cell configuration is a full configuration or not. In this way, for each LTM candidate cell configuration, the terminal determines whether the LTM candidate cell configuration is a full configuration including a fullconfig indication or a full configuration based on the indication information in the LTM candidate cell, or if the candidate cell configuration does not include a fullconfig indication or a fullconfig indication, the terminal considers the candidate cell configuration to be a delta configuration based on the reference configuration. It should be understood that the fullconfig indication refers to an existing 3GPP (registered trademark, the same applies hereinafter) protocol.

[0281] Method 3: Reference configuration is mandatory. If all candidate cell configurations are full configurations, the network configures an empty reference configuration. If the candidate cell configuration is the hybrid configuration described above, the network may configure multiple reference configurations. When configuring LTM candidate cells for a terminal, the network indicates the identifier of the candidate cell's reference configuration for each LTM candidate cell. The reference configuration identifier indicates to the terminal whether the configuration is based on a delta configuration or a full configuration (if the reference configuration is empty and the delta configuration of any candidate cell is based on the delta configuration of the empty reference configuration, it can be understood that the candidate cell is a full configuration), and / or is of a particular reference configuration and indicates the delta configuration on which the candidate cell is based.

[0282] When a candidate cell is in a delta configuration based on a reference configuration, any information element in the second radio configuration that is not included in the reference configuration needs to be included in the delta configuration of each candidate cell. Such an operation has the beneficial effect of avoiding a case where a candidate cell cannot use an information element or an information element does not have available configuration parameters, and thus avoiding a case where a service or data cannot be transmitted.

[0283] 2: The CU sends an RRC reconfiguration message to the terminal, where the RRC reconfiguration message includes LTM pre-configuration information, and the LTM pre-configuration information includes one or more LTM candidate cell configurations. Optionally, the RRC reconfiguration message sent by the CU to the terminal further includes L1 measurement configuration information.

[0284] In one embodiment, the LTM pre-configuration information provided by the CU to the terminal further includes a reference configuration for the LTM candidate cell. In one optional embodiment, when multiple reference configurations are configured for the network, an index or identifier of the reference configuration for each candidate cell needs to be indicated for each LTM candidate cell configuration. Optionally, the reference configuration index or identifier is included in each LTM candidate cell configuration. The terminal determines the full configuration and / or reference configuration to be used for each candidate cell based on the configuration information of each candidate cell and / or the index or identifier of the corresponding reference configuration. In this way, the terminal can accurately determine the reference configuration on which the delta configuration for each candidate cell is based, so that a full candidate cell configuration can be accurately determined or generated for each candidate cell and the candidate cell configuration can be correctly applied, thereby ensuring successful handover.

[0285] In another optional embodiment, when the current terminal configuration is used as the reference configuration, the network indicates to the terminal an information element stored as the reference configuration. For example, the first radio resource configuration is indicated as the reference configuration. For example, the first radio resource configuration includes a cell group configuration, a measurement configuration, and / or a radio bearer configuration.

[0286] In one embodiment, the reference configuration described in step 2 and / or step 3 is the reference configuration between the CU and the DU.

[0287] The reference configuration of the air interface is the reference configuration configured by the network for the terminal in the RRC reconfiguration message. In one embodiment, the reference configuration of the air interface may be the reference configuration of steps 2 and 3, i.e., includes the first radio resource configuration. Optionally, in this embodiment, the reference configuration between the CU and the DU is the same as the reference configuration of the air interface. In one understanding, the complete configuration of the candidate cell includes the complete second radio resource configuration. In another understanding, the complete configuration of the candidate cell may be the complete second radio resource configuration obtained based on the reference configuration and the delta configuration.

[0288] In another embodiment, the reference configuration of the air interface includes the first radio resource configuration and the third radio resource configuration, and the third radio resource configuration is a configuration other than the second radio resource configuration or the current terminal configuration. In this case, the complete configuration of the candidate cell includes the complete second radio configuration and the complete third radio configuration. For example, the reference configuration described in step 3 and / or step 4 includes the first radio resource configuration and the third radio resource configuration.

[0289] In one optional embodiment, the reference configuration between the CU and the DU includes a first radio resource configuration, and the reference configuration of the air interface includes the first radio resource configuration and a third radio resource configuration. Optionally, in this embodiment, the reference configuration between the CU and the DU is different from the reference configuration of the air interface. The terminal determines a complete candidate cell configuration based on the empty reference configuration.

[0290] It should be understood that the reference configuration between the CU and the DU may be the same as or different from the reference configuration of the air interface.

[0291] Optionally, for the measurement configuration, the measurement configuration of the terminal before and after the LTM handover may remain unchanged. To avoid releasing or clearing the measurement results when the terminal applies the configuration of the target cell during LTM execution, it may be indicated whether the measurement configuration of the LTM candidate cell has changed. Optionally, whether the measurement configuration has changed may be indicated for each candidate cell. The indication scheme may be one of the following two solutions:

[0292] Solution 1: The LTM pre-configuration information configured by the network for the terminal includes a measurement configuration resource pool. The measurement configuration resource pool includes one or more measurement configurations, and each measurement configuration is associated with one measurement configuration identifier ID. For each LTM candidate cell configuration, the candidate cell configuration includes a measurement configuration identifier ID. The terminal determines the measurement configuration of the candidate cell based on the measurement configuration identifier ID in the candidate cell configuration. If the measurement configuration ID of the target cell (e.g., the target cell is one of the candidate cells) is the same as the terminal's current measurement configuration ID, the terminal does not release the measurement results when performing an LTM handover. In another understanding, if the measurement configuration IDs of two candidate cells are the same, the terminal retains the measurement results when performing an LTM handover between two candidate cells.

[0293] Solution 2: Each candidate cell includes indication information indicating whether the measurement configuration has changed. Optionally, the indication information indicates whether the candidate cell changes the measurement configuration of the source cell when the terminal receives the LTM pre-configuration. Optionally, if the terminal is handed over to a cell whose measurement configuration has changed, the terminal clears or releases the measurement results when a subsequent LTM handover is performed.

[0294] It should be understood that Steps 2 to 4 of Embodiment 5 may be used separately or in combination with other aforementioned embodiments, without limitation.

[0295] 1: After receiving the RRC reconfiguration message, the terminal sends an RRC reconfiguration complete message to the source cell.

[0296] 2: The terminal sends an L1 measurement report based on the L1 measurement configuration to report the L1 measurement result. The L1 measurement configuration may be included in the RRC reconfiguration message of step 4.

[0297] 3: The source DU decides to trigger an LTM handover based on the L1 measurement report sent by the terminal.

[0298] The source DU sends an L1 / L2 handover command to the terminal. The handover command indicates the target cell to which the terminal should be handed over or indicates the configuration information of the target cell to which the terminal should be handed over. The target cell is included in the candidate cells.

[0299] 4: The terminal receives the handover command and performs handover to the target cell.

[0300] 4.1. The terminal generates the complete configuration of the candidate or target cell (the target cell can be one of the candidate cells), specifically as follows:

[0301] If the reference configuration is empty or the candidate or target cell configuration is a complete configuration, the candidate or target cell configuration is already a complete configuration, and / or If the reference configuration is not empty, the candidate cell configuration or the target cell configuration is a delta configuration based on the reference configuration, or the candidate cell configuration or the target cell configuration is not a complete configuration. The terminal generates a complete configuration for the candidate cell or the target cell based on the delta configuration for the candidate cell or the target cell and the reference configuration for the delta configuration for the candidate cell or the target cell. In one embodiment, the terminal generates a configuration for the target cell, and the configuration of the target cell is the complete configuration for the target cell when the terminal stores a sixth variable including the first reference configuration, reconfigures the sixth variable based on the delta configuration for the target cell, and the reconfigured sixth variable is the generated configuration for the target cell.

[0302] It should be understood that the order of execution of step 8 and step 8.1 is not limited. For example, step 8.1 may be performed before step 8.

[0303] 4.2. The terminal applies the full configuration of the target cell.

[0304] If the target cell configuration includes a fullconfig directive, the full configuration process is performed. For more information, see 3GPP TS 38.331.

[0305] Otherwise, if the target cell configuration does not include the fullconfig instruction, a new LTM process is performed. The new LTM process includes, but is not limited to:

[0306] If each RLC bearer included in the current terminal configuration is also included in the target cell's configuration, the RLC configuration in the current terminal configuration is replaced with the RLC configuration of the target cell, or if an RLC bearer included in the target cell's configuration is not included in the current terminal configuration, the RLC entity is released. The current terminal configuration is the terminal configuration of the terminal when the terminal receives the handover command or the source configuration. The target cell's configuration may be the complete configuration of the target cell. It should be understood that replacing the RLC configuration in the current terminal configuration with the RLC configuration of the target cell if each RLC bearer included in the current terminal configuration is also included in the target cell's configuration means that, for an RLC bearer identifier of the target cell, if the RLC bearer identifier is also included in the current terminal configuration, the current RLC configuration of the terminal associated with the same RLC bearer identifier is replaced with the RLC configuration of the target cell associated with that identifier.

[0307] Optionally, if each radio bearer RB included in the current terminal configuration is also included in the configuration of the target cell, the RB configuration in the current terminal configuration is replaced with the RB configuration of the target cell, or if an RB included in the target cell configuration is not included in the current terminal configuration, the RB is released. Optionally, each RB configuration includes a PDCP configuration associated with the RB configuration. The configuration of the target cell may be the complete configuration of the target cell. It should be understood that, if each RB included in the current terminal configuration is also included in the configuration of the target cell, replacing the RB configuration in the current terminal configuration with the RB configuration of the target cell means that, for an RB identifier of the target cell, if the RB identifier is also included in the current terminal configuration, the RB configuration associated with the same RB identifier in the current terminal configuration is replaced with the RB configuration of the target cell associated with that RB identifier.

[0308] Optionally, if each SCell included in the current terminal configuration is also included in the configuration of the target cell, the SCell configuration in the current terminal configuration is replaced with the SCell configuration of the target cell, or if a SCell included in the target cell configuration is not included in the current terminal configuration, the SCell is released. The configuration of the target cell may be the complete configuration of the target cell. It should be understood that if each SCell included in the current terminal configuration is also included in the configuration of the target cell, replacing the SCell configuration in the current terminal configuration with the SCell configuration of the target cell means that for SCell configurations having the same SCell identifier in the target cell configuration and the current terminal configuration, the SCell configuration having the same SCell identifier in the current terminal configuration is replaced with the SCell configuration in the target cell configuration.

[0309] Optionally, if the measurement configuration of the target cell does not change, the terminal retains the current measurement results. In this way, if the measurement configuration remains unchanged when LTM is performed, a beneficial effect can be achieved in that the release or clearing of measurement results is avoided when the terminal applies the target cell configuration. This reduces the power consumption of the terminal. After the terminal is handed over to the target cell, the terminal performs measurements based on the measurement configuration of the target cell.

[0310] Optionally, for a third radio resource configuration:

[0311] If the reference configuration includes a third radio resource configuration, the full configuration includes the third radio resource configuration, and the terminal applies the third radio resource configuration in the full configuration or the reference configuration.

[0312] If the reference configuration does not include the third radio resource configuration, the terminal keeps the information elements in the third radio resource configuration in the current configuration unchanged. The third radio resource configuration is, for example, a master key update (e.g., masterKeyUpdate), sk-Counter, otherconfig, and / or needForGapsConfigNR-r16. For specific descriptions of masterKeyUpdate, sk-Counter, otherconfig, and needForGapsConfigNR-r16, please refer to the standard protocol.

[0313] It should be understood that each step of embodiment 5 may be performed as an optional step. That is, the terminal may perform some steps of this embodiment. The reference configuration in steps 4 to 8 of embodiment 5 is the reference configuration of the candidate cell configured by the network (e.g., CU) for the terminal, i.e., the reference configuration of the air interface. Optionally, the reference configuration in steps 3 to 8 of embodiment 5 may be the first reference configuration of another embodiment, which may be any one of embodiments 1 to 4 and embodiment 6.

[0314] In embodiment 5, to ensure that a terminal can use the correct configuration during an LTM handover, how to configure information elements that may be included in the configuration of a candidate cell is specified, how to use the information elements included in the configuration of a candidate cell is specified, and a configuration usage rule for the terminal is specified, thereby ensuring successful handover and normal data transmission and reception. Furthermore, when an LTM handover is performed, whether the measurement configuration has changed is indicated. If the measurement configuration remains unchanged, the terminal retains the measurement results, thereby reducing the power consumption of the terminal. For each candidate cell, whether the configuration is a delta configuration, a full configuration, or a full configuration including a fullconfig indication is indicated. Since the terminal can accurately determine the configuration of each candidate cell, a complete candidate cell configuration can be accurately determined or generated for each candidate cell, and the candidate cell configuration can be correctly applied, thereby ensuring successful handover.

[0315] [Embodiment 6] Embodiment 6 provides an LTM handover method, including:

[0316] The access network device sends an LTM candidate cell configuration to the terminal. The LTM candidate cell configuration includes configuration information of one or more LTM candidate cells. Optionally, the configuration information of each LTM candidate cell may include measurement configuration information of the LTM candidate cell.

[0317] The terminal receives LTM candidate cell configurations from the access network device. Optionally, the terminal releases or retains measurement results of the terminal when performing LTM based on measurement configuration information included in the configuration information of each LTM candidate cell. If the measurement configuration of the candidate cell is the same as the measurement configuration of the source cell, the terminal retains the measurement results of the terminal when performing LTM, or if the measurement configuration of the candidate cell is different from the measurement configuration of the source cell, the terminal releases the measurement results of the terminal when performing LTM.

[0318] In one optional embodiment, the LTM candidate cell configuration includes a measurement configuration resource pool, the measurement configuration resource pool including one or more measurement configurations, and each measurement configuration in the measurement configuration resource pool is associated with a measurement configuration identifier ID. For each LTM candidate cell configuration, the candidate cell configuration includes a measurement configuration identifier ID. The terminal determines the measurement configuration of the candidate cell based on the measurement configuration identifier ID in the candidate cell configuration. If the measurement configuration ID of the candidate cell is the same as the terminal's current measurement configuration ID, the terminal holds or does not release the terminal's current measurement results when the terminal performs an LTM handover to the candidate cell. In another understanding, if the measurement configuration IDs of two candidate cells are the same, the terminal holds the measurement results when performing an LTM handover between the two candidate cells. If the measurement configuration ID of the candidate cell is different from the terminal's current measurement configuration ID, the terminal releases the terminal's current measurement results when performing an LTM handover to the candidate cell. In another understanding, if the measurement configuration IDs of the two candidate cells are different, the terminal releases the measurement results when performing an LTM handover between the two candidate cells.

[0319] In another optional embodiment, the terminal receives an LTM candidate cell configuration from an access network device. Optionally, the terminal performs measurement configuration based on measurement configuration information included in the configuration information of each LTM candidate cell. The measurement configuration information included in the configuration information of each LTM candidate cell includes first indication information, where the first indication information indicates whether the measurement configuration has changed. Optionally, the first indication information indicates whether the candidate cell changes the measurement configuration of the source cell when the terminal receives the LTM pre-configuration. If the first indication information indicates that the measurement configuration does not change, the terminal retains the terminal's measurement results when LTM is performed, or if the first indication information indicates that the measurement configuration does not change, the terminal releases the terminal's measurement results when LTM is performed. Optionally, if the terminal is handed over to a cell whose measurement configuration has changed, the terminal clears or releases the measurement results when a subsequent LTM handover is performed. Optionally, the first indication information may be a pre-configuration bit.

[0320] In embodiment 6, a method for indicating a measurement configuration method and / or whether the measurement configuration is changed when LTM is performed is provided. The terminal can accurately determine the measurement configuration of the candidate cell and / or whether the measurement configuration has been changed based on the measurement configuration method and / or the first indication information. In addition, the measurement configuration of the terminal can remain unchanged before and after LTM handover. According to the method of embodiment 6, unnecessary release or clearing of measurement results can be avoided when the terminal applies the configuration of the target cell during LTM, thereby reducing the measurement power consumption of the terminal and improving handover performance.

[0321] It will be understood that embodiment 6 may be used in combination with any one of embodiments 1 to 5. For example, embodiment 6 may be added to a previous embodiment, or embodiment 6 may be combined with some steps of the previous embodiment to form a new embodiment.

[0322] [Embodiment 7] Embodiment 7 provides an LTM handover method, including:

[0323] The access network device transmits an LTM candidate cell configuration to the terminal. The LTM candidate cell configuration includes configuration information of one or more LTM candidate cells. Optionally, the configuration information of each LTM candidate cell may include second indication information, which indicates whether the configuration of the LTM candidate cell is a delta configuration, a full configuration, or a full configuration including a fullconfig indication. It should be understood that the delta configuration is a delta configuration based on a reference configuration. For details, please refer to the description in the previous embodiment. For an understanding of the full configuration, please refer to the description of the full configuration of the candidate cell in embodiment 5.

[0324] The terminal receives an LTM candidate cell configuration from the access network device. Optionally, when handing over to each LTM candidate cell, the terminal performs an LTM-related operation based on second indication information included in the configuration information of the LTM candidate cell. The LTM-related operation may include at least one of the following: If the target cell configuration includes a fullconfig indication, a full configuration process is performed (see 3GPP TS 38.331 for details); or if the target cell configuration does not include a fullconfig indication, the target cell configuration is a full configuration, or the target cell configuration is a delta configuration, a new LTM process is performed. For a description of the new LTM process, see the description of step 8.2 in embodiment 6.

[0325] Optionally, if the reference configuration is not empty, or the candidate cell configuration or the target cell configuration is a delta configuration based on the reference configuration, or the candidate cell configuration or the target cell configuration is not a complete configuration, the terminal generates a complete configuration of the candidate cell or the target cell based on the delta configuration of the candidate cell or the target cell and the reference configuration of the candidate cell or the target cell. The complete configuration of the target cell is the configuration of the target cell. In one embodiment, the terminal generating the configuration of the target cell may be the terminal storing a sixth variable including the first reference configuration, reconfiguring the sixth variable based on the delta configuration of the target cell, where the reconfigured sixth variable is the generated configuration of the target cell, or if the sixth variable is empty, reconfiguring the sixth variable based on the first reference configuration to obtain a seventh variable, and reconfiguring the seventh variable based on the delta configuration of the target cell, where the reconfigured seventh variable is the generated configuration of the target cell. In one embodiment, the implementation in which the terminal generates the complete configuration of the candidate cell is the same as the implementation in which the terminal generates the configuration of the target cell.

[0326] In one optional embodiment, the second indication information is a preset bit, and the preset bit indicates whether the candidate cell is in a delta configuration or a full configuration. For example, the preset bit is one-bit indication information. When the value of the one-bit indication information is one, it may indicate that the LTM candidate cell configuration is a delta configuration based on a reference configuration, and when the value of the one-bit indication information is zero, it may indicate that the LTM candidate cell configuration is a full configuration. Alternatively, when the value of the one-bit indication information is zero, it may indicate that the LTM candidate cell configuration is a delta configuration based on a reference configuration, and when the value of the one-bit indication information is one, it may indicate that the LTM candidate cell configuration is a full configuration. Alternatively, when the value of the one-bit indication information is true, it indicates that the LTM candidate cell configuration is a delta configuration based on a reference configuration, or when the value of the one-bit indication information is true, it indicates that the LTM candidate cell configuration is a full configuration. As another example, the preset bit is a two-bit indicator, where the first bit indicates that the candidate cell is in the delta configuration and the second preset bit indicates that the candidate cell is in the full configuration.

[0327] In another optional embodiment, the second indication information is new indication information indicating whether the candidate cell configuration is a full configuration or not. For example, the new indication information is preset bit information of 1 bit. When the value of the 1 bit is 1, it indicates that the LTM candidate cell configuration is a full configuration, and when the value of the 1 bit is 0, it indicates that the LTM candidate cell configuration is not a full configuration. Alternatively, when the value of the 1 bit is 1, it indicates that the LTM candidate cell configuration is not a full configuration, and when the value of the 1 bit is 0, it indicates that the LTM candidate cell configuration is a full configuration. Alternatively, when the value of the 1 bit of the indication information is true, it indicates that the LTM candidate cell configuration is a full configuration, and when the 1 bit is not included or the value of the 1 bit of the indication information is false, it indicates that the LTM candidate cell configuration is not a full configuration, or when the value of the 1 bit of the indication information is true, it indicates that the LTM candidate cell configuration is not a full configuration. In this way, for each LTM candidate cell, the terminal determines that the LTM candidate cell is a full configuration based on the second indication information in the LTM candidate cell, or determines that the LTM candidate cell is a full configuration including a fullconfig indication based on a fullconfig indication. Alternatively, if the candidate cell configuration does not include a fullconfig indication or a fullconfig indication, the terminal considers the candidate cell configuration to be a delta configuration based on the reference configuration. Alternatively, if the candidate cell configuration does not indicate either a full configuration or a full configuration, the terminal considers the candidate cell configuration to be a delta configuration based on the reference configuration. It should be understood that the fullconfig indication refers to existing 3GPP protocols.

[0328] In another optional embodiment, the reference configuration of the candidate cell is mandatory. If all candidate cell configurations are full configurations, the network configures the reference configuration to be empty. If the LTM candidate cell configuration is a hybrid configuration (a hybrid configuration may be understood as a hybrid configuration of two or three of the candidate cell configurations being delta configurations, where the candidate cell configuration is a full configuration and the candidate cell configuration is a full configuration including a fullconfig indication), the network may configure multiple reference configurations. Alternatively, the network may configure different reference configurations for different candidate cells, or the network may configure multiple reference configurations. In the case of multiple reference configurations, when configuring LTM candidate cells for a terminal, the network indicates an identifier of the candidate cell's reference configuration for each LTM candidate cell. Optionally, the identifier of the reference configuration indicates to the terminal whether the configuration is based on a delta configuration or a full configuration (if the reference configuration is empty and the delta configuration of any candidate cell is based on the delta configuration of the empty reference configuration, it may be understood that the candidate cell is a full configuration) and / or of a particular reference configuration within the multiple reference configurations, indicating the delta configuration on which the candidate cell is based. It should be appreciated that in this embodiment, the second indication may be an identifier of the reference configuration.

[0329] In embodiment 7, to enable the terminal to know whether each candidate cell is a delta configuration, a full configuration, or a full configuration including a fullconfig instruction, when configuring an LTM candidate cell for the terminal, the network may include second indication information to indicate which of the three configurations is the configuration of each LTM candidate cell. In this way, the terminal can accurately determine the configuration (delta configuration, full configuration, or full configuration) of each candidate cell, so that a complete candidate cell configuration can be accurately determined or generated for each candidate cell, and the candidate cell configuration can be correctly applied, thereby ensuring the success of handover.

[0330] It will be understood that embodiment 7 may be used in combination with any one of embodiments 1 to 6. For example, embodiment 7 may be added to a previous embodiment, or embodiment 7 may be combined with some steps of the previous embodiment to form a new embodiment.

[0331] It should be understood that in the embodiments of the present application:

[0332] 1. In addition to highlighting the differences between different embodiments, the repeated contents of different embodiments may be explained in relation to each other.

[0333] 2. In the embodiments of the present application, an example in which the radio configuration is an RLC bearer configuration is used for explanation. When the radio configuration is a DRB, the description related to the RLC bearer in the embodiments is replaced with the description related to the DRB. The principles, mechanisms, and methods are the same. Similarly, the RLC bearer in the embodiments of the present application can also be replaced with an SRB, an SCell, etc.

[0334] 3. In the embodiments of the present application, the LTM candidate cell configuration may also be referred to as the LTM candidate target cell configuration, the candidate cell configuration, or the LTM candidate cell configuration information, and their meanings may be the same. The LTM candidate cell has the same meaning as the candidate cell. The LTM candidate cell configuration information and the LTM pre-configuration information may have the same meaning. The names here are merely examples and do not constitute limitations.

[0335] 4. In the embodiments of the present application, the description "corresponding to" may be the description "associated with."

[0336] 5. In the embodiments of the present application, "in the process of the terminal performing ..." may also be understood as "the terminal is applying ..." or "the terminal applies the process of ...". In the embodiments of the present application, the configuration of the source cell may also be understood as the current terminal configuration or the terminal configuration when the handover command is received.

[0337] 6. In the embodiments of the present application, the target cell configuration and the target cell configuration have the same meaning. The target cell configuration or the target cell configuration may be the complete configuration of the target cell. The meanings of the two descriptions may be the same.

[0338] 7. In the embodiments of the present application, examples are merely examples, and the contents of the present invention are not limited thereto.

[0339] It should be understood that, to realize the functions in the foregoing embodiments, the access network device and the terminal include corresponding hardware structures and / or software modules for performing each function. In this application, those skilled in the art should easily recognize that the units and method steps in the examples described with reference to the embodiments disclosed in this application can be realized by hardware or a combination of hardware and computer software. Whether the functions are performed by hardware or by hardware driven by computer software depends on the specific application scenario and design constraints of the technical solutions.

[0340] 5 and 6 are diagrams of possible communication device structures according to embodiments of the present application. These communication devices may be configured to implement the functions of the terminal device or the access network device in the above-described method embodiments. Thus, the beneficial effects of the above-described method embodiments can also be achieved. In the embodiments of the present application, the communication device may be one of the terminals 120a to 120j shown in FIG. 1, the access network device 110a or 110b shown in FIG. 1, or a module (e.g., a chip) used in the terminal or the access network device.

[0341] 5, the communication device 500 includes a processing unit 510 and a transceiver unit 520. The communication device 500 is configured to implement the functions of a terminal or an access network device in the embodiments of the aforementioned methods.

[0342] When the communication device 500 is configured to realize the functions of the terminal in the embodiment of the above-mentioned method, the transceiver unit 520 is configured to receive a first configuration from an access network device, the first configuration including a first reference configuration and a delta configuration of a target cell, the first reference configuration being associated with the delta configuration of the target cell, and the processing unit 510 is configured to determine a radio configuration of the terminal based on the first reference configuration and the delta configuration of the target cell.

[0343] In one embodiment, the processing unit 510 is further configured to release current configuration information of the terminal except for at least one of a master cell group MCG cell radio network temporary identifier C-RNTI, an access stratum security configuration, a radio bearer RB configuration, a radio link control RLC bearer configuration, a secondary cell SCell configuration, or a recorded measurement configuration.

[0344] In one embodiment, when determining the radio configuration of the terminal based on the first reference configuration and the delta configuration of the target cell, the processing unit 510 is configured to: if the first variable includes the radio configuration of the first reference configuration, update the first variable based on the delta configuration of the target cell, the updated first variable includes the radio configuration of the target cell, and determine the radio configuration of the terminal based on the radio configuration in the updated first variable.

[0345] In one embodiment, when updating the first variable based on the delta configuration of the target cell, the processing unit 510 is configured to do at least one of: updating the first radio configuration in the first variable to the second radio configuration if the first variable includes the first radio configuration, the first list includes the second radio configuration, the first list is a list in the delta configuration of the target cell, and an identifier of the first radio configuration is the same as an identifier of the second radio configuration; adding the third radio configuration to the first variable if the first list includes the third radio configuration and the first variable includes a radio configuration other than the third radio configuration; or releasing the fourth radio configuration in the first variable if the first variable includes a fourth radio configuration, the second list includes a fifth radio configuration, the second list is a list in the delta configuration of the target cell, and an identifier of the fourth radio configuration is the same as the identifier of the fifth radio configuration.

[0346] In one embodiment, when determining the radio configuration of the terminal based on the updated radio configuration in the first variable, the processing unit 510 is configured to perform at least one of: reconfiguring the seventh radio configuration based on the sixth radio configuration if the updated first variable includes the sixth radio configuration and the radio configuration of the source cell includes the seventh radio configuration and an identifier of the sixth radio configuration is the same as the identifier of the seventh radio configuration; creating the eighth radio configuration in the radio configuration of the terminal if the updated first variable includes the eighth radio configuration and the radio configuration of the source cell includes a configuration other than the eighth radio configuration; or releasing the ninth radio configuration in the radio configuration of the terminal if the radio configuration of the source cell includes the ninth radio configuration and the updated first variable includes a configuration other than the ninth radio configuration.

[0347] In one embodiment, the processing unit 510 is further configured to release current cell group configuration information of terminals in the cell group configuration except for at least one of an MCG C-RNTI or an RLC bearer configuration.

[0348] In one embodiment, when determining the radio configuration of the terminal based on the first reference configuration and the delta configuration of the target cell, the processing unit 510 is specifically configured to: determine a second reference configuration based on the radio configuration in the first reference configuration, and determine the radio configuration of the terminal based on the second reference configuration and the delta configuration of the target cell. The second reference configuration includes at least a tenth radio configuration and a twelfth radio configuration. Optionally, the second reference configuration further includes another radio configuration other than the eleventh radio configuration in the current radio configuration of the terminal.

[0349] In one embodiment, when determining the second reference configuration based on the radio configuration in the first reference configuration, the processing unit 510 is configured to perform at least one of: updating the eleventh radio configuration of the terminal to the tenth radio configuration if the first reference configuration includes the tenth radio configuration, and the radio configuration of the source cell includes the eleventh radio configuration, and the identifier of the tenth radio configuration is the same as the identifier of the eleventh radio configuration; or creating the twelfth radio configuration if the first reference configuration includes the twelfth radio configuration and the radio configuration of the source cell includes a radio configuration other than the twelfth radio configuration.

[0350] In one embodiment, when the first reference configuration includes a tenth radio configuration, and the radio configuration of the source cell includes an eleventh radio configuration, and the identifier of the tenth radio configuration is the same as the identifier of the eleventh radio configuration, the processing unit 510 is further configured to remove the identifier of the eleventh radio configuration from the radio configuration identifier of the source cell included in the second variable.

[0351] In one embodiment, when determining the radio configuration of the terminal based on the second reference configuration and the delta configuration of the target cell, the processing unit 510 is configured to: reconfigure the thirteenth radio configuration of the terminal based on the fifteenth radio configuration if the second reference configuration of the terminal includes the thirteenth radio configuration, the first reference configuration includes the fourteenth radio configuration, the third list includes the fifteenth radio configuration, the third list is a list in the delta configuration of the target cell, and the thirteenth radio configuration, the fourteenth radio configuration, and the fifteenth radio configuration have the same identifier; and reconfigure the sixteenth radio configuration of the terminal based on the sixteenth radio configuration if the third list includes the sixteenth radio configuration, the third list is a list in the delta configuration of the target cell, and the second reference configuration and the first reference configuration include a configuration other than the sixteenth radio configuration. updating the 18th radio configuration based on the 17th radio configuration if the third list includes the 17th radio configuration and the third list is a list in the delta configuration of the target cell and the first reference configuration includes a configuration other than the 17th radio configuration and the second reference configuration includes the 18th radio configuration and an identifier of the 17th radio configuration is the same as an identifier of the 18th radio configuration; or releasing the 20th radio configuration in the radio configuration of the terminal if the fourth list includes the 19th radio configuration and the fourth list is a list in the delta configuration of the target cell and the second reference configuration includes the 20th radio configuration and an identifier of the 19th radio configuration is the same as an identifier of the 20th radio configuration.

[0352] In one embodiment, when the third list includes the 17th radio configuration, and the third list is a list within the delta configuration of the target cell, and the first reference configuration includes a configuration other than the 17th radio configuration, and the second reference configuration includes the 18th radio configuration, and the identifier of the 17th radio configuration is the same as the identifier of the 18th radio configuration, the processing unit 510 is further configured to delete the identifier of the 17th radio configuration from the radio configuration identifier of the source cell included in the second variable.

[0353] In one embodiment, the processing unit 510 is further configured to release, in the radio configuration of the terminal, a radio configuration corresponding to the radio configuration identifier included in the second variable.

[0354] In one embodiment, the radio configuration of the terminal includes at least one of a radio bearer (RB) configuration, a radio link control (RLC) bearer configuration, or a secondary cell configuration.

[0355] In one embodiment, before determining the radio configuration of the terminal based on the first reference configuration and the delta configuration of the target cell, the transceiver unit 520 is further configured to receive a handover command from the access network device or satisfy a handover condition by the terminal.

[0356] When the communication device 500 is configured to realize the functions of the access network device in the embodiment of the above-mentioned method, the processing unit 510 is configured to generate a first configuration, the first configuration including a reference configuration and a delta configuration of a target cell, the reference configuration being related to the delta configuration of the target cell, and the delta configuration of the target cell and the reference configuration being for determining a radio configuration of the terminal, and the transceiver unit 520 is configured to transmit the first configuration to the terminal.

[0357] In one embodiment, the radio configuration of the terminal includes at least one of a radio bearer (RB) configuration, a radio link control (RLC) bearer configuration, or a secondary cell configuration.

[0358] In one embodiment, after transmitting the first configuration to the terminal, the transceiver unit 520 is further configured to transmit a handover command to the terminal.

[0359] For a more detailed description of the processing unit 510 and the transceiver unit 520, please directly refer to the relevant descriptions of the aforementioned method embodiments, and the details will not be described again here.

[0360] 6, the communication device 600 includes a processor 610 and an interface circuit 620. The processor 610 and the interface circuit 620 are coupled to each other. It will be understood that the interface circuit 620 may be a transceiver or an input / output interface. Optionally, the communication device 600 may further include a memory 630 configured to store instructions to be executed by the processor 610, to store input data required for the processor 610 to execute the instructions, or to store data generated after the processor 610 executes the instructions.

[0361] When the communication device 600 is configured to perform the methods provided in the above method embodiments, the processor 610 is configured to implement the functions of the processing unit 510, and the interface circuit 620 is configured to implement the functions of the transceiver unit 520.

[0362] When the communication device is a chip used in a terminal, the chip in the terminal realizes the functions of the terminal in the above-mentioned method embodiments. The chip in the terminal receives information from another module in the terminal (e.g., a radio frequency module or an antenna), and the information is transmitted to the terminal by an access network device. Alternatively, the chip in the terminal transmits information to another module in the terminal (e.g., a radio frequency module or an antenna), and the information is transmitted to the access network device by the terminal.

[0363] When the communication apparatus is a module used in an access network device, the module in the access network device realizes the functions of the access network device in the aforementioned method embodiments. The module in the access network device receives information from another module (e.g., a radio frequency module or an antenna) in the access network device, and the information is transmitted to the access network device by a terminal. Alternatively, the module in the access network device transmits information to another module (e.g., a radio frequency module or an antenna) in the access network device, and the information is transmitted to the terminal by the access network device. The module in the access network device here may be a baseband chip of the access network device, a DU, or another module. The DU here may be a DU in an open radio access network (O-RAN) architecture.

[0364] It will be understood that the processor in embodiments of the present application may be a central processing unit (CPU), another general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0365] The steps of the method in the embodiments of the present application may be implemented in a hardware manner or by a processor executing software instructions. The software instructions may include corresponding software modules. The software modules may be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disk, removable hard disk, CD-ROM, or any other form of storage medium known in the art. For example, the storage medium is coupled to the processor so that the processor can read information from and write information to the storage medium. Of course, the storage medium may be a component of the processor. The processor and the storage medium may be located in an ASIC. In addition, the ASIC may be located in a base station or a terminal. Of course, the processor and the storage medium may reside as separate components in the base station or the terminal.

[0366] All or part of the above-described embodiments may be realized using software, hardware, firmware, or any combination thereof. When software is used to realize the embodiments, all or part of the embodiments may be realized in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, all or part of the procedures or functions of the embodiments of the present application are performed. The computer may be a general-purpose computer, a special-purpose computer, a computer network, a network device, user equipment, or another programmable device. The computer program or instructions may be stored in a computer-readable storage medium or transmitted from a computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center via wired or wireless communication. The computer-readable storage medium may be any available medium that can be accessed by a computer, or may be a data storage device, such as a server or data center that integrates one or more available media. The available media may be magnetic media such as floppy disks, hard disks, or magnetic tapes, optical media such as digital video disks, or semiconductor media such as solid-state drives. The computer-readable storage media may be volatile or nonvolatile storage media, or may include both types of storage media: volatile and nonvolatile storage media.

[0367] In the embodiments of the present application, unless otherwise specified or there is no logical contradiction, the terms and / or descriptions of different embodiments are consistent and may be cross-referenced, and the technical features of different embodiments may be combined based on their internal logical relationships to form new embodiments.

[0368] In the embodiments of the present application, unless otherwise specified, identical or similar parts of the embodiments are mutually referenced. In the embodiments and implementations / methods / implementations of the embodiments of the present application, unless otherwise specified or unless a logical conflict occurs, the terms and / or descriptions are consistent and may be mutually referenced between different embodiments or between implementations / methods / implementations of the embodiments. The technical features of different embodiments and implementations / methods / implementations of the embodiments may be combined to form new embodiments, implementations, methods, or implementations based on the internal logical relationships of those technical features. The above descriptions are embodiments of the present application, but are not intended to limit the scope of protection of the present application. The steps of each embodiment may be partially performed (e.g., a terminal device may not perform a step performed by the terminal device in the above embodiment). The execution order of different steps may be changed. The embodiments described in this specification may be combined with other embodiments, and steps of different embodiments of the present specification may be combined.

[0369] The term "embodiment" as used herein means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present application. Phrases appearing in various places in this specification may not necessarily refer to the same embodiment, and are not an independent or optional embodiment that excludes another embodiment.

[0370] In the description of this application, unless otherwise specified, the character " / " indicates an "or" relationship between related objects. For example, A / B may indicate A or B. In the description of this application, the term "and / or" only describes the relationship between related objects and indicates that three relationships may exist. For example, A and / or B may indicate the following three cases: when only A is present, when both A and B are present, and when only B is present. Here, A and B may be singular or plural. Additionally, in the description of this application, "plurality" means two or more than two unless otherwise specified. "At least one of the following items (elements)" or similar expressions means any combination of these items, including one item (element) or any combination of multiple items (elements). For example, at least one item (element) of a, b, or c may refer to a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be singular or plural. In addition, in order to clearly describe the technical solutions in the embodiments of the present application, terms such as "first" and "second" are used to distinguish between identical or similar items that basically provide the same function or purpose in the embodiments of the present application. Those skilled in the art can understand that terms such as "first" and "second" do not limit the quantity or execution order, and terms such as "first" and "second" do not indicate clear distinctions.

[0371] In addition, the network architectures and service scenarios described in the embodiments of the present application are intended to more clearly explain the technical solutions in the embodiments of the present application, and do not constitute limitations on the technical solutions provided in the embodiments of the present application. With the evolution of network architectures and the emergence of new service scenarios, those skilled in the art may know that the technical solutions provided in the embodiments of the present application can also be applied to similar technical problems.

[0372] All aspects, embodiments, or features are presented in this application by describing a system that may include multiple devices, assemblies, modules, etc. It is appreciated and understood that each system may include different devices, assemblies, modules, etc. and / or may not include all of the devices, assemblies, modules, etc. described with reference to the accompanying drawings. Additionally, combinations of these solutions may be used.

[0373] Additionally, in the embodiments of this application, terms such as "example" and "for example" are used to denote serving as an example, illustration, or explanation. Any embodiment or design scheme described in this application as an "example" should not be described as preferred or having more advantages than another embodiment or design scheme. Rather, the term "example" is intended to present a concept in a particular way.

[0374] In the embodiments of this application, the terms "of," "corresponding," "relevant," and "corresponding" are sometimes used interchangeably. It should be noted that the meanings conveyed by these terms are consistent when differences are not emphasized.

[0375] The network architectures and service scenarios described in the embodiments of the present application are intended to more clearly explain the technical solutions in the embodiments of the present application, and do not constitute limitations on the technical solutions provided in the embodiments of the present application. With the evolution of network architectures and the emergence of new service scenarios, those skilled in the art may know that the technical solutions provided in the embodiments of the present application can also be applied to similar technical problems.

[0376] It should be understood that various numbers in the embodiments of the present application are only used for distinction to facilitate description, and are not used to limit the scope of the embodiments of the present application. The sequence numbers of the above processes do not imply an execution order, and the execution order of the processes should be determined based on the functions and internal logic of the processes. [Explanation of symbols]

[0377] 100 Wireless Access Network 110a Access Network Devices 110b Access Network Devices 120a terminal 120b terminal 120c terminal 120d terminal 120e terminal 120f terminal 120g terminal 120h terminal 120i terminal 120j terminal 200 Core Network 300 Internet 1000 Communication Systems 500 Communication Equipment 510 Processing Unit 520 Transceiver Unit 600 Communication Equipment 610 processor 620 Interface Circuit 630 memory

Claims

1. 1. A communication method comprising: receiving a first configuration from an access network device, the first configuration including a first reference configuration and a delta configuration of a target cell, the first reference configuration being related to the delta configuration of the target cell; determining a radio configuration of a terminal device based on the first reference configuration and a delta configuration of the target cell; A method comprising:

2. Releasing current configuration information of the terminal device except for at least one of a master cell group (MCG) cell radio network temporary identifier (C-RNTI), an access stratum security configuration, a radio bearer (RB) configuration, a radio link control (RLC) bearer configuration, a secondary cell (SCell) configuration, or a recorded measurement configuration.

10. The method of claim 1, further comprising:

3. The step of determining the radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell includes: If the first variable includes a radio configuration of the first reference configuration, updating the first variable based on a delta configuration of the target cell, the updated first variable including a radio configuration of the target cell; determining the radio configuration of the terminal device based on the radio configuration in the updated first variable; 3. The method of claim 1 or 2, comprising:

4. updating the first variable based on the delta configuration of the target cell, updating the first radio configuration in the first variable to the second radio configuration if the first variable includes a first radio configuration, the first list includes a second radio configuration, the first list is a list in a delta configuration of the target cell, and an identifier of the first radio configuration is the same as an identifier of the second radio configuration; if the first list includes a third wireless configuration and the first variable includes a wireless configuration other than the third wireless configuration, adding the third wireless configuration to the first variable; or Releasing the fourth radio configuration in the first variable if the first variable includes a fourth radio configuration, the second list includes a fifth radio configuration, the second list is a list in a delta configuration of the target cell, and an identifier of the fourth radio configuration is the same as an identifier of the fifth radio configuration. The method of claim 3, comprising at least one of:

5. The step of determining the radio configuration of the terminal device based on the radio configuration in the updated first variable includes: If the updated first variable includes a sixth radio configuration, and the radio configuration of a source cell includes a seventh radio configuration, and an identifier of the sixth radio configuration is the same as an identifier of the seventh radio configuration, reconfiguring the seventh radio configuration in the radio configuration of the terminal device based on the sixth radio configuration; If the updated first variable includes an eighth radio configuration and the radio configuration of the source cell includes a configuration other than the eighth radio configuration, creating the eighth radio configuration in the radio configuration of the terminal device; or If the radio configuration of the source cell includes a ninth radio configuration and the updated first variable includes a configuration other than the ninth radio configuration, releasing the ninth radio configuration in the radio configuration of the terminal device.

5. The method of claim 3 or 4, comprising at least one of:

6. Releasing current cell group configuration information of the terminal device in a cell group configuration excluding at least one of an MCG C-RNTI or an RLC bearer configuration.

10. The method of claim 1, further comprising:

7. The step of determining the radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell includes: determining a second reference configuration based on a radio configuration in the first reference configuration; determining the radio configuration of the terminal device based on the second reference configuration and a delta configuration of the target cell; 10. The method of claim 1 or 6, comprising:

8. determining the second reference configuration based on the radio configuration in the first reference configuration, If the first reference configuration includes a tenth radio configuration, and the radio configuration of a source cell includes an eleventh radio configuration, and an identifier of the tenth radio configuration is the same as an identifier of the eleventh radio configuration, updating the eleventh radio configuration of the terminal device to the tenth radio configuration; or creating a twelfth radio configuration when the first reference configuration includes a twelfth radio configuration and the radio configuration of the source cell includes a radio configuration other than the twelfth radio configuration; and the second reference configuration includes at least the tenth radio configuration and the twelfth radio configuration.

9. When the first reference configuration includes the tenth radio configuration, and the radio configuration of the source cell includes the eleventh radio configuration, and an identifier of the tenth radio configuration is the same as an identifier of the eleventh radio configuration, the method includes: removing the identifier of the eleventh radio configuration from the radio configuration identifier of the source cell, the identifier being included in a second variable; 9. The method of claim 8, further comprising:

10. The step of determining the radio configuration of the terminal device based on the second reference configuration and the delta configuration of the target cell includes: reconfiguring the thirteenth radio configuration of the terminal device based on the fifteenth radio configuration when the second reference configuration of the terminal device includes a thirteenth radio configuration, the first reference configuration includes a fourteenth radio configuration, the third list includes a fifteenth radio configuration, the third list is a list in a delta configuration of the target cell, and the thirteenth radio configuration, the fourteenth radio configuration, and the fifteenth radio configuration have the same identifier; creating the sixteenth radio configuration if the third list includes a sixteenth radio configuration, the third list is a list within a delta configuration of the target cell, and the second reference configuration and the first reference configuration include a configuration other than the sixteenth radio configuration; updating the 18th radio configuration based on the 17th radio configuration when the third list includes a 17th radio configuration, the third list is a list in a delta configuration of the target cell, the first reference configuration includes a configuration other than the 17th radio configuration, the second reference configuration includes an 18th radio configuration, and an identifier of the 17th radio configuration is the same as an identifier of the 18th radio configuration; or Releasing the twentieth radio configuration in the radio configuration of the terminal device when the fourth list includes a nineteenth radio configuration, the fourth list is a list in a delta configuration of the target cell, the second reference configuration includes a twentieth radio configuration, and an identifier of the nineteenth radio configuration is the same as an identifier of the twentieth radio configuration.

10. The method of claim 7, comprising at least one of:

11. When the third list includes the 17th radio configuration, and the third list is a list in a delta configuration of the target cell, and the first reference configuration includes a configuration other than the 17th radio configuration, and the second reference configuration includes the 18th radio configuration, and an identifier of the 17th radio configuration is the same as an identifier of the 18th radio configuration, the method includes: removing the identifier of the seventeenth radio configuration from the radio configuration identifier of the source cell included in the second variable; 11. The method of claim 10, further comprising:

12. Releasing a wireless configuration corresponding to the wireless configuration identifier included in the second variable in the wireless configuration of the terminal device.

12. The method of any one of claims 9 to 11, further comprising:

13. The step of determining the radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell includes: generating a configuration for the target cell based on the first reference configuration and a delta configuration for the target cell; replacing the radio configuration of the terminal device with a radio configuration in the configuration of the target cell; 2. The method of claim 1, comprising:

14. generating a configuration for the target cell, reconfiguring the sixth variable based on a delta configuration of the target cell if the sixth variable includes the first reference configuration, wherein the reconfigured sixth variable is the generated configuration of the target cell.

14. The method of claim 1 or 13, comprising:

15. If the measurement configuration in the configuration of the target cell is the same as the measurement configuration in the configuration of the terminal device, retaining the current measurement results by the terminal device.

15. The method of claim 1, 13, or 14, further comprising:

16. before determining the radio configuration of the terminal device based on the first reference configuration and the delta configuration of the target cell, receiving a handover command from the access network device or satisfying a handover condition by the terminal device; 16. The method of any one of claims 1 to 15, further comprising:

17. 17. The method of claim 1, wherein the radio configuration of the terminal device includes at least one of a radio bearer (RB) configuration, a radio link control (RLC) bearer configuration, or a secondary cell configuration.

18. 1. A communication method comprising: generating a first configuration, the first configuration including a first reference configuration and a delta configuration of a target cell, the first reference configuration being related to the delta configuration of the target cell, and the delta configuration of the target cell and the first reference configuration being for determining a radio configuration of a terminal device; transmitting the first configuration to the terminal device; A method comprising:

19. 20. The method of claim 18, wherein the radio configuration of the terminal device includes at least one of a radio bearer (RB) configuration, a radio link control (RLC) bearer configuration, or a secondary cell configuration.

20. 20. The method of claim 18 or 19, further comprising the step of sending a handover command to the terminal device after sending the first configuration to the terminal device.

21. A communication device comprising a unit configured to perform the method of any one of claims 1 to 17.

22. A communications device comprising a processor and a memory, the processor coupled to the memory, the processor configured to perform the method of any one of claims 1 to 17.

23. 18. A communication device comprising a processor and an interface circuit, the interface circuit configured to receive a signal from another communication device other than the communication device and transmit the signal to the processor or transmit a signal from the processor to another communication device other than the communication device, the processor configured to perform the method of any one of claims 1 to 17 by using logic circuits or by executing code instructions.

24. A communication device comprising a unit configured to perform the method of any one of claims 18 to 20.

25. 21. A communications device comprising a processor and a memory, the processor coupled to the memory, the processor configured to perform the method of any one of claims 18 to 20.

26. 21. A communication device comprising a processor and an interface circuit, the interface circuit configured to receive a signal from another communication device other than the communication device and transmit the signal to the processor or transmit a signal from the processor to another communication device other than the communication device, the processor configured to perform the method of any one of claims 18 to 20 by using logic circuits or by executing code instructions.

27. 21. A computer-readable storage medium storing instructions that, when executed in a computer, enable the computer to perform the method of any one of claims 1 to 17 or any one of claims 18 to 20.

28. A computer program product comprising a computer program or instructions, which, when executed by an apparatus, performs the method of any one of claims 1 to 17 or performs the method of any one of claims 18 to 20.

29. A chip including a processor, the processor coupled to a memory, the processor configured to execute computer programs or instructions stored in the memory to enable the chip to perform the method of any one of claims 1 to 17 or any one of claims 18 to 20.

30. A communication system including a first communication device and a second communication device, The first communication device is configured to perform the method of any one of claims 1 to 17, A communication system, wherein the second communication device is configured to perform the method of any one of claims 18 to 20.

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