Communication method, apparatus and system

Abstract

The present application relates to the technical field of communications. Disclosed are a communication method, an apparatus and a system. The method comprises: a terminal side apparatus receives a first message from a first network side apparatus, the first message being used for configuring M handover conditions; receiving a second message from the first network side apparatus, the second message being used for instructing evaluating a handover condition for a first cell, and the M handover conditions comprising the handover condition for the first cell; and, in response to the second message, evaluating the handover condition for the first cell. In the method, the first network side apparatus can send the second message to the terminal side apparatus in advance when the signal quality of a source cell is good and, after receiving the second message, the terminal side apparatus will not immediately perform a handover, but evaluate the handover condition for the first cell, so as to aid in avoiding the problem that a rapid change in the signal quality of the source cell results in failure to send a handover command message and thus affects the handover, thereby improving handover robustness.

Description

Communication method, device and system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on January 31, 2024, with application number 202410153049.4 and application name "A Communication Method, Device and System", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of communication technology, and in particular to a communication method, device, and system. Background Art

[0004] Cell switching is a very important feature in communication systems. It mainly involves the network equipment switching the terminal to a neighboring cell with better signal quality before the signal quality of the serving cell becomes poor, thereby providing lossless or packet loss-free communication services.

[0005] In current cell handovers, the network sends a handover command to the terminal, which then switches from the source cell to the target cell according to the handover command. However, if the signal quality of the source cell changes rapidly, such as if the signal quality of the source cell suddenly deteriorates, the handover command may fail to be sent, resulting in poor handover robustness. Summary of the Invention

[0006] The present application provides a communication method, device, and system for improving the robustness of handover.

[0007] In a first aspect, an embodiment of the present application provides a communication method, which can be applied to a terminal-side device, where the terminal-side device can be a terminal or a component in the terminal (such as a chip or circuit). For example, in this method, the terminal-side device receives a first message from a first network-side device, where the first message is used to configure M switching conditions; receives a second message from the first network-side device, where the second message is used to instruct the evaluation of the switching conditions of the first cell; wherein the M switching conditions include the switching conditions of the first cell, and M is an integer greater than or equal to 1; and in response to the second message, evaluates the switching conditions of the first cell.

[0008] By adopting the above method, the first network side device can send the second message to the terminal side device in advance when the signal quality of the source cell is good. After receiving the second message, the terminal side device will not switch immediately, but will evaluate the switching conditions of the first cell, thereby avoiding the problem of failure to send the switching command message due to rapid changes in the signal quality of the source cell, thereby affecting the switching, and improving the robustness of the switching.

[0009] In one possible design, the second message includes: identification information corresponding to the first cell, and / or identification information of the switching condition of the first cell.

[0010] In this way, the second message can indicate which cell's switching condition is to be evaluated through the identification information corresponding to the first cell; and / or, the second message can indicate which switching condition of the first cell is to be evaluated through the identification information of the switching condition of the first cell.

[0011] In one possible design, the M switching conditions correspond to N cells, where the N cells include the first cell, N is less than or equal to M, and N is an integer greater than or equal to 1.

[0012] In one possible design, the first message is also used to indicate that the switching condition of the first cell is not to be evaluated.

[0013] The first message may explicitly indicate that the switching condition of the first cell is not to be evaluated (for example, the first message includes deactivation information); or, the first message may implicitly indicate that the switching condition of the first cell is not to be evaluated.

[0014] In one possible design, the second message includes first indication information, where the first indication information is used to indicate conditional switching; the second message also includes second indication information, where the second indication information is used to indicate evaluating the switching condition of the first cell in the case of the conditional switching.

[0015] In one possible design, the method further includes: switching to the first cell in response to an evaluation of a switching condition of the first cell.

[0016] In one possible design, switching to the first cell in response to an evaluation of a switching condition of the first cell includes switching to the first cell if an evaluation result determines that the switching condition of the first cell is met.

[0017] In one possible design, the switching conditions of the first cell include K switching conditions, where K is an integer greater than or equal to 1; the switching conditions of the first cell are met, including: one of the K switching conditions of the first cell is met.

[0018] For example, the second message indicates that switching condition 1 among the K switching conditions should be evaluated. If switching condition 1 is met, the terminal side device can switch to the first cell. For another example, the second message indicates that switching condition 1 and switching condition 2 among the K switching conditions should be evaluated. If one of the switching conditions of switching condition 1 and switching condition 2 is met, the terminal side device can switch to the first cell.

[0019] In one possible design, the K switching conditions include a first switching condition and a second switching condition; the type of the first switching condition and the type of the second switching condition are different; or, when the type of the first switching condition and the type of the second switching condition are the same, the threshold values ​​corresponding to the first switching condition and the second switching condition are different; or, the first switching condition is evaluated after receiving the first message, and the second switching condition is evaluated after receiving the second message.

[0020] In one possible design, the switching condition of the first cell is met, including at least one of the following: the signal quality of the source cell is less than or equal to a first threshold value; the signal quality of the first cell is greater than or equal to a second threshold value; the difference between the signal quality of the first cell and the signal quality of the source cell is greater than or equal to a third threshold value.

[0021] In one possible design, the switching condition of the first cell corresponds to a first transmission configuration indication TCI state; switching to the first cell includes: accessing the first cell based on the first TCI state corresponding to the switching condition of the first cell.

[0022] In one possible design, the first message or the second message is also used to indicate that the switching condition of the first cell corresponds to the first TCI state.

[0023] In one possible design, switching to the first cell includes: accessing the first cell in a random access-free manner.

[0024] In one possible design, the second message includes the timing advance TA information of the first cell; or, the method further includes: receiving the TA information of the first cell after the second message; wherein, the TA information of the first cell is used to access the first cell in a random access-free manner.

[0025] In this way, the terminal side device can obtain the TA information of the first cell before switching, and thus access the first cell in a random access-free manner, which is convenient for reducing switching delay and improving switching efficiency.

[0026] In one possible design, after switching to the first cell, the method further includes: canceling conditional switching that satisfies switching conditions of other cells. In this way, the problem of frequent switching of the terminal side device due to the satisfaction of switching conditions of multiple cells can be avoided.

[0027] In the second aspect, an embodiment of the present application provides a communication method, which can be applied to a first network side device, and the first network side device can be a first network device or a component (such as a chip or circuit) in the first network device, and the first network device can be, for example, a CU of a source access network node, a DU of a source access network node, or a source access network node. For example, in this method, the first network side device sends a first message to a terminal side device, and the first message is used to configure M switching conditions; and sends a second message to the terminal side device, and the second message is used to instruct the terminal side device to evaluate the switching conditions of the first cell; wherein the M switching conditions include the switching conditions of the first cell, and M is an integer greater than or equal to 1.

[0028] In one possible design, the method further includes: sending a third message, wherein the third message is used to indicate that the terminal side device has been instructed to evaluate the switching conditions of the first cell.

[0029] In one possible design, the method further includes: sending a fourth message, wherein the fourth message is used to indicate that the TA information of the first cell has been sent to the terminal side device. In other words, the fourth message is used to indicate that a TA command has been sent to the terminal side device.

[0030] In one possible design, the third message is also used to indicate the probability of the terminal side device switching to the first cell.

[0031] In one possible design, the M switching conditions correspond to N cells, where the N cells include the first cell, N is less than or equal to M, and N is an integer greater than or equal to 1.

[0032] In one possible design, the method further includes: receiving a fifth message, where the fifth message is used to request configuration of switching conditions for the N cells.

[0033] In one possible design, the second message includes: identification information corresponding to the first cell, and / or identification information of the switching condition of the first cell.

[0034] In one possible design, the first message is also used to instruct the terminal side device not to evaluate the switching condition of the first cell.

[0035] In one possible design, the second message includes first indication information, where the first indication information is used to indicate conditional switching;

[0036] The second message further includes second indication information, where the second indication information is used to instruct to evaluate a switching condition of the first cell in the case of the conditional switching.

[0037] In one possible design, the first message or the second message is also used to indicate that the condition of the first cell corresponds to a first TCI state.

[0038] In one possible design, the second message includes the TA information of the first cell; or the method further includes: after the second message, sending the TA information of the first cell to the terminal side device; wherein, the TA information of the first cell is used by the terminal side device to access the first cell in a random access-free manner.

[0039] In one possible design, the switching conditions of the first cell include K switching conditions, where K is an integer greater than or equal to 1; the K switching conditions include a first switching condition and a second switching condition; the type of the first switching condition is different from the type of the second switching condition; or, when the type of the first switching condition is the same as the type of the second switching condition, the threshold values ​​corresponding to the first switching condition and the second switching condition are different; or, the first switching condition is evaluated after receiving the first message, and the second switching condition is evaluated after receiving the second message.

[0040] In a third aspect, an embodiment of the present application provides a communication method, which can be applied to a second network-side device, where the second network-side device can be a second network device or a component (such as a chip or circuit) in the second network device, and the second network device can be, for example, a CU of a candidate access network node, a DU of a candidate access network node, or a candidate access network node. For example, in this method, the second network-side device receives a third message, where the third message is used to indicate that an instruction has been given to the terminal-side device to evaluate the switching condition of the first cell; in response to the third message, it is determined that an instruction has been given to the terminal-side device to evaluate the switching condition of the first cell.

[0041] In one possible design, the method further includes: receiving a fourth message, where the fourth message is used to indicate that timing advance TA information of the first cell has been sent to the terminal side device.

[0042] In one possible design, the third message is also used to indicate the probability of the terminal side device switching to the first cell.

[0043] In addition, an embodiment of the present application also provides a communication method, which can be applied to a second network side device, where the second network side device can be a second network device or a component (such as a chip or circuit) in the second network device, and the second network device can be, for example, a CU of a candidate access network node. For example, in this method, the CU of the candidate access network node receives a sixth message from the CU of the source access network node, where the sixth message is used to request an advance synchronization configuration for the first identification information, where the advance synchronization configuration belongs to the configuration of the first cell; based on the sixth message, a seventh message is sent to the DU of the candidate access network node, where the seventh message is used to request the advance synchronization configuration for the first identification information and the second identification information, where the second identification information is used to identify the source access network node (or the CU of the source access network node); the advance synchronization configuration, the first identification information, and the second identification information are received from the DU; and the advance synchronization configuration and the first identification information are sent to the CU.

[0044] In one possible design, the method also includes: receiving the TA information of the first cell, the random access resource information corresponding to the TA information, the first identification information and the second identification information from the DU of the candidate access network node, the first identification information corresponds to the DU of the source access network node, and the second identification information is used to identify the source access network node (or the CU of the source access network node); sending the TA information of the first cell, the random access resource information corresponding to the TA information, and the first identification information to the CU of the source access network node.

[0045] It can be understood that the communication methods provided in the second and third aspects correspond to the first aspect, and the beneficial effects of the relevant technical features in the second and third aspects can be referred to the description of the first aspect and will not be repeated here.

[0046] In a fourth aspect, the present application provides a communication device, which has the ability to implement the functions involved in any one of the first to third aspects above. For example, the communication device includes modules or units or means corresponding to the operations involved in any one of the first to third aspects above. The functions or units or means can be implemented through software, or through hardware, or the corresponding software can be implemented through hardware.

[0047] In one possible design, the communication device includes a processing unit and a communication unit. The communication unit can be used to send and receive signals to enable communication between the communication device and other devices; the processing unit can be used to perform certain internal operations of the communication device. The functions performed by the processing unit and the communication unit can correspond to the operations described in any of the first to third aspects above.

[0048] In one possible design, the communication device includes a processor, which can be coupled to a memory. The memory can store the necessary computer programs or instructions for implementing the functions of any of the first to third aspects described above. The processor can execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the method of any possible design or implementation of the first to third aspects described above.

[0049] In one possible design, the communication device includes a processor and a memory, and the memory may store the necessary computer programs or instructions for implementing the functions of any of the first to third aspects described above. The processor may execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the method of any possible design or implementation of the first to third aspects described above.

[0050] In one possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute the method in any possible design or implementation of the first to third aspects above.

[0051] It can be understood that in the fourth aspect above, the processor can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processor can be a general-purpose processor, which is implemented by reading the software code stored in the memory. In addition, the above processors can be one or more, and the memories can be one or more. The memory can be integrated with the processor, or the memory and the processor can be set separately. In the specific implementation process, the memory can be integrated with the processor on the same chip, or can be set on different chips respectively. The embodiment of the present application does not limit the type of memory and the setting method of the memory and the processor.

[0052] In a fifth aspect, the present application provides a communication system, which may include a first network-side device and a terminal-side device; wherein the first network-side device is configured to execute the method described in the first aspect, and the terminal-side device is configured to execute the method described in the second aspect. Optionally, the communication system further includes a second network-side device, configured to execute the method described in the third aspect.

[0053] In a sixth aspect, the present application provides a computer-readable storage medium, in which computer-readable instructions are stored. When a computer reads and executes the computer-readable instructions, the computer executes the method in any possible design of the first to third aspects above.

[0054] Exemplarily, a computer-readable storage medium can be any available medium that can be accessed by a computer. By way of example and not limitation, a computer-readable medium can include a non-transitory computer-readable medium, a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a CD-ROM or other optical disk storage, a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer.

[0055] In a seventh aspect, the present application provides a computer program product, which, when read and executed by a computer, enables the computer to execute the method in any possible design of the first to third aspects above.

[0056] In an eighth aspect, the present application provides a chip (or chip system), which includes a processor, and the processor is coupled to a memory, and is used to read and execute a software program stored in the memory to implement the method in any possible design of the first to third aspects above. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] FIG1 is a schematic diagram of a communication system applicable to an embodiment of the present application;

[0058] FIG2A is a schematic diagram of a CU-DU separation architecture provided in an embodiment of the present application;

[0059] FIG2B is a schematic diagram of another CU-DU separation architecture provided in an embodiment of the present application;

[0060] FIG3 is a schematic diagram of the LTM switching process provided in an embodiment of the present application;

[0061] FIG4 is a schematic diagram of a conditional switching process according to an embodiment of the present application;

[0062] FIG5 is a flow chart of the communication method according to the first embodiment of the present application;

[0063] FIG6 is a flow chart of the communication method according to the second embodiment of the present application;

[0064] FIG7 is a flow chart of the communication method according to the third embodiment of the present application;

[0065] FIG8 is a flow chart of the communication method according to the fourth embodiment of the present application;

[0066] FIG9 is a flow chart of a communication method according to a fifth embodiment of the present application;

[0067] FIG10 is a possible exemplary block diagram of a device involved in an embodiment of the present application;

[0068] FIG11 is a schematic structural diagram of a network-side device provided in an embodiment of the present application;

[0069] FIG12 is a schematic structural diagram of a terminal-side device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0070] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application. The technical solutions in the embodiments of the present application can be applied to various communication systems, such as universal mobile telecommunications system (UMTS), wireless local area network (WLAN), wireless fidelity (Wi-Fi) system, 4th generation (4G) mobile communication system, such as long term evolution (LTE) system, fifth generation (5G) mobile communication system, such as new radio (NR) system, and future evolved communication systems, such as sixth generation (6G) mobile communication system.

[0071] This application will present various aspects, embodiments, or features in the context of systems that may include multiple devices, components, modules, etc. It should be understood and appreciated that each system may include additional devices, components, modules, etc., and / or may not include all of the devices, components, modules, etc. discussed in conjunction with the figures. Furthermore, combinations of these aspects may also be used.

[0072] In addition, in the embodiments of the present application, words such as "exemplarily" and "such as" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as an "example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present concepts in a concrete way. In the embodiments of the present application, "of", "corresponding, relevant" and "corresponding" can sometimes be used interchangeably. It should be noted that when the distinction between them is not emphasized, the meanings to be expressed are consistent.

[0073] The communication system and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. A person skilled in the art will appreciate that, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0074] To facilitate understanding of the embodiments of the present application, the communication system applicable to the embodiments of the present application is first described in detail using the communication system shown in Figure 1 as an example. As shown in Figure 1, the communication system 10 includes one or more access network nodes 20, and one or more terminals 30. Among them, the interface between the access network node and the terminal can be a Uu interface (or called an air interface), and data can be transmitted between the access network node 20 and the terminal 30 through air interface resources. Exemplarily, the terminal can be located within the communication coverage of one or more cells of the access network node, and the cell providing service to the terminal (i.e., the service cell of the terminal) can be one or more.

[0075] (1) Terminal

[0076] A terminal can be a device that accesses the above-mentioned communication system and has wireless transceiver capabilities. A terminal may also be called user equipment (UE), terminal equipment, user device, access terminal, user unit, user station, mobile station, mobile station (MS), remote station, remote terminal, mobile device, user terminal, terminal unit, terminal station, terminal device, wireless communication device, user agent, or user device.

[0077] For example, the terminal in the embodiment of the present application can be a mobile phone, a personal digital assistant (PDA), a laptop computer, a tablet computer, a drone, a computer with wireless transceiver function, a machine type communication (MTC) terminal, a virtual reality (VR) terminal, an augmented reality (AR) terminal, an Internet of Things (IoT) terminal, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home (such as a game console, a smart TV, a smart speaker, a smart refrigerator, and fitness equipment, etc.), a vehicle-mounted terminal, and an RSU with terminal function.

[0078] (2) Access network nodes

[0079] An access network node is a device located on the network side of the communication system and has wireless transceiver capabilities. An access network node can also be called an access network device or a wireless access network device.

[0080] For example, the access network node in the embodiment of the present application can be an access point (AP) in a Wi-Fi system, such as a home gateway, a router, a server, a switch, a bridge, etc., a base station, an evolved Node B (eNB), a radio network controller (RNC), a base station controller (BSC), a base transceiver station (BTS), a home base station, a baseband unit (BBU), a wireless relay node, a wireless backhaul node, a transmission point (TRP; or a transmission point, TP), etc. It can also be a next-generation NodeB (gNB) in a 5G system, or a network node constituting a gNB, such as a road side unit (RSU) with base station functions, etc., or it can also be a satellite or various future forms of base stations.

[0081] (3) Communication between terminals and access network nodes

[0082] Communication between a terminal and an access network node follows a specific protocol layer structure. For example, the control plane protocol layer structure may include the radio resource control (RRC) layer, the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer, the media access control (MAC) layer, and the physical layer (PHY). The user plane protocol layer structure may include the PDCP layer, the RLC layer, the MAC layer, and the physical layer. In one possible implementation, the service data adaptation protocol (SDAP) layer may also be included above the PDCP layer. The SDAP layer, PDCP layer, RLC layer, MAC layer, and physical layer may also be collectively referred to as the access layer. For detailed descriptions of each of the above protocol layers, please refer to the relevant technical specifications of the 3rd Generation Partnership Project (3GPP).

[0083] (4) CU-DU separation architecture

[0084] For example, in some possible network structures, an access network node may include one or more centralized units (CUs) and one or more distributed units (DUs), and multiple DUs may be centrally controlled by one CU. This architecture may be referred to as a CU-DU separation architecture. As an example, the interface between the CU and the DU may be referred to as an F1 interface, where the control plane (CP) interface may be an F1-C interface and the user plane (UP) interface may be an F1-U interface.

[0085] The processing functions of CU and DU can be divided according to the protocol layers of the wireless network: for example, as shown in Figure 2A, the functions of the PDCP layer and above protocol layers are set in the CU, and the functions of the protocol layers below the PDCP layer (such as the RLC layer and the MAC layer, etc.) are set in the DU. It can be understood that the above division of the processing functions of CU and DU according to the protocol layer is only an example, and can also be divided in other ways, such as the functions of the protocol layers above the RLC layer are set in the CU, and the functions of the protocol layers of the RLC layer and below are set in the DU. For example, the CU or DU can be divided into functions with more protocol layers, and the CU or DU can also be divided into partial processing functions with protocol layers. The embodiments of the present application are not limited to this.

[0086] Furthermore, the functions of the CU can be implemented by one entity, or by different entities. For example, the functions of the CU can be further divided, that is, the control plane and the user plane are separated and implemented through different entities, namely the control plane CU entity (i.e., CU-CP entity) and the user plane CU entity (i.e., CU-UP entity). The CU-CP entity and the CU-UP entity can be coupled with the DU to jointly complete the functions of the RAN device. The interface between the CU-CP entity and the CU-UP entity can be an E1 interface, the interface between the CU-CP entity and the DU can be an F1-C interface, and the interface between the CU-UP entity and the DU can be an F1-U interface. Among them, one DU and one CU-UP can be connected to one CU-CP. Under the control of the same CU-CP, one DU can be connected to multiple CU-UPs, one CU-UP can be connected to multiple DUs, and under the collaboration of multiple CU-CPs, one CU-UP can also be connected to multiple cooperating CU-CPs, thereby improving the flexibility of the CU-CP. Figure 2B is a schematic diagram of an air interface protocol stack distribution. As shown in FIG2B , for both the user plane and the control plane, the air interface protocol stack may be RLC, MAC, and PHY in the DU, and PDCP and above protocol layers in the CU.

[0087] It should be noted that: in the architecture shown in Figures 2A and 2B above, the signaling generated by the CU can be sent to the terminal through the DU, or the signaling generated by the terminal can be sent to the CU through the DU. The DU can directly encapsulate the signaling through the protocol layer and transparently transmit it to the terminal or CU without parsing it. In the following embodiments, if the transmission of such signaling between the DU and the terminal is involved, then the sending or receiving of the signaling by the DU includes this scenario. For example, the signaling of the RRC or PDCP layer will eventually be processed into physical layer data and sent to the terminal, or converted from the received physical layer data. Under this architecture, the signaling of the RRC layer or PDCP layer can also be considered to be sent by the DU, or sent by the DU and the radio frequency device.

[0088] It can be understood that the embodiments of the present application do not limit the number of access network nodes and the number of terminals included in the communication system. In addition, in addition to access network nodes and terminals, the above-mentioned communication system may also include other devices or network elements, such as core network devices, relay devices, etc., which are not limited by the embodiments of the present application.

[0089] The following first explains the relevant terms involved in the embodiments of this application. When not specifically explained, these explanations are intended to support the meaning of the relevant terms and make the embodiments of this application easier to understand, and should not be regarded as strict limitations on the relevant terms in the scope of protection claimed by this application.

[0090] (1) Cell switching scenario

[0091] When a terminal switches or handovers between different cells, there may be multiple specific switching scenarios. For example, the switching scenarios may be divided according to the location relationship between the source cell and the target cell.

[0092] Among them, when the access network node adopts a CU-DU separation architecture (for example, the access network node includes a CU and multiple DUs, the multiple DUs are centrally controlled by a CU, and each of the multiple DUs may include one or more cells), the positional relationship between the source cell and the target cell may refer to whether the source cell and the target cell belong to the same CU and / or the same DU. Among them, "DU includes one or more cells" can also be described as "DU manages or controls one or more cells", or "one or more cells of DU", or "one or more cells belong to DU". Three possible switching scenarios are described here, namely scenarios 1 to 3.

[0093] Scenario 1: A terminal switches from one cell in a DU to another cell in the same DU. In other words, the source and target cells belong to the same DU. The cell handover corresponding to Scenario 1 is called intra-DU handover.

[0094] Scenario 2: A terminal switches from a cell in DU1 controlled by a CU to a cell in DU2 controlled by the same CU. DU1 is called the source DU, and DU2 is called the target DU. In other words, the source and target cells of the terminal belong to different DUs controlled by the same CU. The cell handover in Scenario 2 is called an inter-DU handover.

[0095] Scenario 3: The terminal switches from a cell in DU1 controlled by CU1 to a cell in DU3 controlled by CU2. In this case, CU1 is called the source CU and CU2 is called the target CU. In other words, the source and target cells of the terminal belong to different DUs controlled by different CUs. The cell handover corresponding to Scenario 2 is called inter-CU handover.

[0096] When the access network node is considered as a whole (e.g., a gNB), the location relationship between the source cell and the target cell can refer to whether the source cell and the target cell belong to the same access network node. Two possible handover scenarios are described here: Scenario 4 and Scenario 5.

[0097] Scenario 4: A terminal switches from a cell in access network node 1 to a cell in access network node 2. In this case, access network node 1 is called the source access network node, and access network node 2 is called the target access network node. In other words, the source and target cells of the terminal belong to different access network nodes. The cell handover in Scenario 4 is called inter-gNB handover.

[0098] Scenario 5: A terminal is handed over from one cell of an access network node to another cell of the same access network node. In other words, the source and target cells of the terminal belong to the same access network node. The cell handover corresponding to Scenario 5 is called intra-gNB handover.

[0099] The communication method provided in the embodiments of the present application can be applied to any of the above scenarios.

[0100] (2) Layer 1 / Layer 2 Triggered Mobility Handover

[0101] Cell handover can be divided into two types, one of which is cell handover based on layer 1 / layer 2, which can be called layer 1 / layer 2 handover or layer 1 / layer 2 triggered mobility (L1 / L2 triggered mobility, LTM) handover, and the other is cell handover based on layer 3, which can be called layer 3 handover (L3 handover). Among them, layer 1 can refer to the physical layer, layer 2 can refer to any one or more layers of the MAC layer, RLC layer, PDCP layer, and SDAP layer, and layer 3 can refer to the RRC layer. Since layer 1 / layer 2 is located at a lower level of the protocol stack than the RRC layer (layer 3), layer 1 / layer 2 handover can also be called low-layer handover, or bottom layer handover, or lower-layer handover. This application does not limit the name of the specific handover technology.

[0102] Compared with layer 3 switching, LTM switching can effectively reduce switching delay. The reason is: for layer 3 switching, in the CU-DU separation architecture, the CU receives the measurement results of the terminal (the measurement results are forwarded to the CU through the DU), and determines whether to initiate switching based on the measurement results. If it is determined to initiate switching, the switching command is sent to the DU, and the DU sends it to the terminal. Since this process involves communication interaction between the CU and the DU (that is, the interaction of the F1 interface), and the maximum transmission delay of the F1 interface is approximately 3ms to 10ms, it will cause a certain switching delay. The switching decision of LTM switching is sent from the CU to the DU, that is, the DU determines whether to initiate switching (LTM cell switch) based on the measurement results of the terminal, and sends the switching command message directly to the terminal, which can effectively reduce F1 interaction and reduce switching delay.

[0103] Figure 3 is a schematic diagram of a possible implementation process of LTM switching. As shown in Figure 3, the process includes:

[0104] S301: A source access network node sends an RRC reconfiguration message to a terminal; correspondingly, the terminal receives the RRC reconfiguration message.

[0105] Exemplarily, after the terminal accesses the cell of the source access network node, the source access network node may obtain LTM configuration information of multiple candidate cells, and send the LTM configuration information of the multiple candidate cells to the terminal through an RRC reconfiguration message.

[0106] S302: The source access network node determines to hand over the terminal to cell a.

[0107] S303 , the source access network node sends a handover command message to the terminal, where the handover command message is used to instruct the terminal to handover to cell a; accordingly, the terminal receives the handover command message.

[0108] Exemplarily, the terminal may send a measurement report to the source access network node, where the measurement report includes lower layer measurement results for multiple candidate cells. If the source access network node determines to handover the terminal to cell a based on the lower layer measurement results for the multiple candidate cells, the source access network node sends a handover command message to the terminal. The lower layer measurement results may be layer 1 / layer 2 measurement results.

[0109] S304: The terminal switches to cell a according to the switching command message.

[0110] It is understandable that the above S301 to S304 are only a brief process example, and the embodiment of the present application does not limit the specific implementation.

[0111] (3) Conditional switching

[0112] Conditional handover (CHO) refers to a handover performed by a terminal when one or more handover execution conditions are met. Handover execution conditions can also be referred to as handover conditions or execution conditions. For example, the source access network node configures a handover condition for a candidate cell and sends it to the terminal. Subsequently, if the handover condition is met, the terminal can switch to the candidate cell.

[0113] Figure 4 is a schematic diagram of a possible implementation process of CHO. As shown in Figure 4, the process includes:

[0114] S401: A source access network node sends an RRC reconfiguration message to a terminal; correspondingly, the terminal receives the RRC reconfiguration message.

[0115] Exemplarily, after the terminal accesses the cell of the source access network node, the source access network node may obtain CHO configuration information of multiple candidate cells and send the CHO configuration information of the multiple candidate cells to the terminal via an RRC reconfiguration message. For example, the multiple candidate cells include cell a, and the CHO configuration information of cell a includes configuration information of the handover condition of cell a.

[0116] S402: The terminal evaluates handover conditions of the multiple candidate cells according to CHO configuration information of the multiple candidate cells.

[0117] S403: When the handover condition of cell a is met, the terminal hands over to cell a.

[0118] It is understandable that the above S401 to S403 are only a brief process example, and the embodiments of the present application do not limit the specific implementation. In the conditional handover process shown in Figure 4, after the source access network node sends an RRC reconfiguration message to the terminal, the terminal immediately evaluates the handover conditions of the candidate cell based on the configuration information of the handover conditions of the candidate cell in the RRC reconfiguration message. For ease of description, the embodiment of the present application refers to the conditional handover shown in Figure 4 as traditional conditional handover.

[0119] (4) Switching conditions

[0120] As a possible implementation, a switching condition refers to one or more switching events, where the switching events include A3 events, A5 events, or other events.

[0121] Event A3: The difference between the signal quality of the candidate cell and the signal quality of the serving cell becomes better than (better than) the third threshold, or is better than the third threshold (ie, greater than or equal to the third threshold).

[0122] Event A5: The signal quality of the candidate cell becomes better than the second threshold (ie, greater than or equal to the second threshold), and the signal quality of the serving cell becomes worse than the first threshold (ie, less than or equal to the first threshold).

[0123] It should be noted that signal quality can be beam-level signal quality or cell-level signal quality. Signal quality includes at least one of the following: reference signal receiving power (RSRP) or reference signal receiving quality (RSRQ) or signal to interference plus noise ratio (SINR). Signal quality is obtained by measuring the synchronization signal and physical broadcast channel block (SSB) or the channel state information reference signal (CSI-RS).

[0124] For a handover event, the terminal can evaluate the event to determine whether "the entry condition is met or the exit condition is met". For example, for an A3 event, "the entry condition of the event is met" can be understood as the difference between the signal quality of the candidate cell and the signal quality of the serving cell is greater than or equal to the third threshold value, and "the exit condition of the event is met" can be understood as the difference between the signal quality of the candidate cell and the signal quality of the serving cell is less than the third threshold value; for an A5 event, "the entry condition of the event is met" can be understood as the signal quality of the candidate cell is greater than or equal to the second threshold value, and the signal quality of the serving cell is less than or equal to the first threshold value, and "the exit condition of the event is met" can be understood as the signal quality of the candidate cell is less than the second threshold value, and the signal quality of the serving cell is greater than the first threshold value. Exemplarily, when the terminal moves toward the candidate cell, the entry condition may be met; after the entry condition is met, if the terminal moves toward the serving cell, the exit condition may be met. In the embodiments of the present application, "the handover condition is met" below may refer to "the entry condition is met".

[0125] Furthermore, optionally, the handover condition of the candidate cell corresponds to the transmission configuration indication (TCI) state of the candidate cell, where the TCI state can be used to indicate beam information; different handover conditions correspond to different TCI states, and different TCI states are associated with different reference signals. Taking "handover condition a1" as an example, assuming that handover condition a1 corresponds to TCI state 1, the terminal receives the reference signal associated with TCI state 1, and then measures the signal quality of cell a based on the reference signal associated with TCI state 1. Then, based on the signal quality of cell a, the terminal evaluates handover condition a1.

[0126] As described above, in LTM handover, the network device determines whether to trigger a handover based on the measurement results reported by the terminal. If a handover is triggered, a handover command is sent to the terminal, which then switches from the source cell to the target cell according to the handover command. However, if the signal quality of the source cell changes rapidly, such as if the signal quality of the source cell suddenly deteriorates, the handover command may fail to be sent, resulting in poor handover robustness.

[0127] Based on this, an embodiment of the present application provides a communication method for improving the robustness of switching. The communication method provided in the embodiment of the present application involves a terminal side device and at least one network side device, wherein the "terminal side device" can be a terminal, or it can also be a component in the terminal, such as a chip or chip system provided in the terminal; the "network side device" can be a network device, or it can also be a component in the network device, such as a chip or chip system provided in the network device. The network device can be an access network node, or a CU of an access network node, or a DU of an access network node. In the embodiment of the present application, "the terminal side device is a terminal, and the network side device is a network device" will be described as an example.

[0128] The following describes the network devices involved in the communication method provided in the embodiments of the present application in conjunction with some of the switching scenarios described above:

[0129] (1) In the same DU handover (scenario 1), the network device involved in the embodiment of the present application includes a CU and a DU managed by the CU, and the source cell and candidate cells of the terminal both belong to the DU.

[0130] (2) In cross-DU handover (scenario 2), the network devices involved in the embodiment of the present application include a CU, a first DU managed by the CU (i.e., the source DU of the terminal), and a second DU managed by the CU (i.e., the candidate DU of the terminal). The first DU, the second DU, and the CU may belong to the same access network node (e.g., gNB). In the embodiment of the present application, if the terminal switches to a cell managed by a candidate DU, the candidate DU may also be referred to as a target DU. Other similarities (e.g., candidate cells, candidate access network nodes) may be handled similarly.

[0131] (3) In cross-CU switching (scenario 3), the network device involved in the embodiment of the present application includes a first CU, a first DU managed by the first CU (i.e., the source DU of the terminal), a second CU, and a second DU managed by the second CU (i.e., the candidate DU of the terminal). The first CU and the first DU belong to the first access network node (the source access network node), and the second CU and the second DU belong to the second access network node (the candidate access network node).

[0132] (4) In cross-site handover (scenario 4), the network device involved in the embodiments of the present application may include a first access network node (source access network node) and a second access network node (candidate access network node).

[0133] (5) In the same-site handover (scenario 5), the network device involved in the embodiment of the present application is an access network node (such as g-NB), and the source access network node and candidate access network node of the terminal are both the access network node.

[0134] For example, in the communication method provided in an embodiment of the present application, after the network device configures M switching conditions for the terminal, it instructs the terminal to evaluate the switching conditions of the first cell. The terminal then evaluates the switching conditions of the first cell according to the instruction of the network device, and switches to the first cell if the evaluation result determines that the switching conditions of the first cell are met. This type of switching can be called conditional LTM switching. Different from traditional conditional switching, after the network device configures the switching conditions of the first cell for the terminal, the terminal does not immediately evaluate the switching conditions of the first cell. Instead, it evaluates the switching conditions of the first cell after receiving the instruction of the network device.

[0135] The communication method provided in the embodiments of the present application is described in detail below in conjunction with embodiments 1 to 4.

[0136] Example 1

[0137] In the first embodiment, the interaction between the first network device, the second network device and the terminal is taken as an example for description.

[0138] Among them, for scenario 1: the first network device and the second network device can be the same DU. In this case, the relevant operations for interaction between the first network device and the second network device may not be performed. For scenario 2: the first network device can be the first DU (i.e., the source DU), the second network device can be the second DU (i.e., the candidate DU), and the first network device and the second network device communicate via the CU, i.e., first DU->CU->second DU, or second DU->CU->first DU. For transit communication, the information transmitted between different nodes is the same, and the message names carrying this information can be the same or different, without limitation. For example, the specific implementation of "the first network device sends a third message to the second network device" is: the first network device sends a third message a to the CU, and after the CU receives the third message a, it sends a third message b to the second network device. The third message a and the third message b carry the same information, and the message names of the third message a and the third message b can be the same or different. The same is true for the second network device sending the corresponding message to the first network device, i.e., transiting through the CU. For scenario 3: the first network device can be the first DU managed by the first CU, the second network device can be the second DU managed by the second CU, and the first network device and the second network device communicate through the first CU and the second CU, that is, first DU->first CU->second CU->second DU, or second DU->second CU->first CU->first DU. For scenario 4: the first network device can be the first access network node, the second network device can be the second access network node, and the first access network node and the second access network node can communicate through the Xn interface. For scenario 5: the first network device and the second network device can be the same access network node. In this case, the relevant operations for the interaction between the first network device and the second network device may not be performed.

[0139] FIG5 is a flow chart of the communication method according to the first embodiment of the present application. As shown in FIG5 , the method includes:

[0140] S501: A first network device sends a first message to a terminal, where the first message is used to configure M switching conditions; accordingly, the terminal receives the first message.

[0141] (1) Introduce M switching conditions.

[0142] M switching conditions correspond to N cells, N is less than or equal to M, and M and N are integers greater than or equal to 1. The N cells are candidate cells for the terminal, and the first cell among the N cells belongs to the cell managed by the second network device. For example, if N=1, the N cells include the first cell. In this case, the M switching conditions are all switching conditions of the first cell, that is, the M switching conditions correspond to the first cell. For another example, if N=2, the N cells include the first cell and the second cell. In this case, the M switching conditions include the switching conditions of the first cell and the switching conditions of the second cell, that is, some of the switching conditions of the M switching conditions correspond to the first cell, and the other part of the switching conditions correspond to the second cell; the number of switching conditions corresponding to the first cell and the second cell may be the same or different.

[0143] For example, the handover conditions of the first cell include K conditions (i.e., all or part of the M handover conditions), where K is less than or equal to M and is an integer greater than or equal to 1. For example, the K handover conditions include a first handover condition and a second handover condition.

[0144] In one example, the type of the first switching condition is different from the type of the second switching condition, wherein the types of the different switching conditions may be different events, for example, the first switching condition is an A3 event, and the second switching condition is an A5 event.

[0145] In another example, the first switching condition and the second switching condition are of the same type, that is, they correspond to the same event, but have different thresholds. For example, the first switching condition is an A3 event, and the second switching condition is another A3 event, and the thresholds for these two A3 events are different. For another example, the first switching condition is an A5 event, and the second switching condition is another A5 event, and the thresholds for these two A5 events are different.

[0146] In another example, the first handover condition is evaluated after receiving the first message, and the second handover condition is evaluated after receiving the second message; that is, the terminal starts evaluating the first handover condition and the second handover condition at different times. For example, the first handover condition is a handover condition corresponding to a traditional conditional handover (i.e., an unconditional LTM handover), and the second handover condition is a handover condition corresponding to a conditional LTM handover.

[0147] In another example, the first switching condition corresponds to conditional switching based on random access, and the second switching condition corresponds to conditional switching without random access. In this case, when the first switching condition of the first cell is met, the terminal accesses the first cell by random access; when the second switching condition of the first cell is met, the terminal accesses the first cell by random access. Among them, random access-free can also be called random access channel (RACH) (i.e., RACH less), and random access-free can also be understood as random access skip (RACH skip).

[0148] In addition, the first message may also be used to indicate TCI state identification information corresponding to the K conditions, wherein the second switching condition corresponds to the first TCI state identification information. Specifically, the first message includes the first TCI state identification information, and the first TCI state identification information is used to indicate that it corresponds to the second switching condition.

[0149] (2) Introduce the content of the first message.

[0150] Exemplarily, the first message is an RRC message, such as an RRC reconfiguration message.

[0151] The first message may include configuration information of M switching conditions, wherein the configuration information of the switching conditions includes a threshold value. For example, for an A3 event, the threshold value is a third threshold value; for an A5 event, the threshold value is a first threshold value and a second threshold value. For details, see above.

[0152] For example, the first message includes configuration information of the first switching condition and configuration information of the second switching condition. Taking the second switching condition as an example (other switching conditions can be understood similarly), the configuration information of the second switching condition includes identification information of the second switching condition and a threshold value of the second switching condition. For example, the second switching condition can be an A3 or A5 event.

[0153] Optionally, the first message is further used to indicate that after receiving the first message, the handover condition of the first cell is not evaluated. For example, the first message is further used to indicate that after receiving the first message, the second handover condition of the first cell is not evaluated. There are multiple implementations of the first message indicating that after receiving the first message, the second handover condition of the first cell is not evaluated.

[0154] In one possible implementation, the state of the switching condition includes an activation state and a deactivation state. When the state of the switching condition is the activation state, the terminal evaluates the switching condition; when the state of the switching condition is the deactivation state, the terminal does not evaluate the switching condition.

[0155] The specific method of indicating not to evaluate the switching condition of the first cell is any one of the following, such as indication method 1 or indication method 2.

[0156] Indication method 1: Explicit indication. The first message includes initial state information of the second handover condition. For example, the initial state information of the second handover condition may be included in the configuration information of the second handover condition. The initial state information of the second handover condition is used to indicate that the initial state of the second handover condition is a deactivated state. In other words, the first network device indicates the initial state of the second handover condition as a deactivated state through the first message, thereby instructing the terminal not to evaluate the second handover condition after receiving the first message.

[0157] Indication method 2: implicit indication, the first message includes an information element (IE) corresponding to the traditional conditional switching and an information element corresponding to the conditional LTM switching. The configuration information of the first switching condition is included in the information element corresponding to the traditional conditional switching, and the configuration information of the second switching condition is included in the information element corresponding to the conditional LTM switching; that is, the first network device indicates through the first message that the second switching condition is the switching condition corresponding to the conditional LTM switching, so as to indicate that after receiving the first message, the terminal defaults to the deactivated state, that is, the second switching condition is not evaluated.

[0158] Optionally, the first message also includes configuration information of early synchronization of the first cell, where early synchronization includes early uplink synchronization and / or early downlink synchronization. The configuration information of early uplink synchronization may include random access configuration information, such as random access time-frequency resource information (including the first resource) and / or index information of the random access preamble (including the first preamble). The configuration information of early downlink synchronization includes configuration information of the transmission configuration indication (TCI) status. It should be understood that the TCI status can be used to indicate beam information.

[0159] It is understandable that the first message also includes other possible information, such as configured grant (CG) resource information allocated by the second network device to the terminal for the first cell, etc., which is not specifically limited.

[0160] Exemplarily, the M switching conditions (and the initial states of the M switching conditions) can be determined by the first network device, for example, the first network device receives the fifth message (refer to Example 2 or Example 3), and then determines the M switching conditions (and the initial states of the M switching conditions) in response to the fifth message.

[0161] S502: The first network device sends a second message to the terminal, where the second message is used to instruct to evaluate a handover condition of the first cell; accordingly, the terminal receives the second message.

[0162] Some possible implementations of the second message are described here in combination with implementation modes 1 to 3.

[0163] (1) Implementation method 1

[0164] In implementation manner 1, the second message may be a cell switch command message, such as a MAC control element (CE). The cell switch command message may also be referred to as a handover command message.

[0165] In one example, the second message includes first indication information and second indication information, wherein the first indication information is used to indicate conditional switching (i.e., conditional LTM switching), and the second indication information is used to indicate the evaluation of the switching condition of the first cell in the case of conditional LTM switching. The first indication information may include 1 bit. When the value of the bit is 1, the first indication information is used to indicate that the second message is for conditional LTM switching. In this case, the second message also includes the second indication information. When the value of the bit is 0, the first indication information is used to indicate other switching scenarios (such as unconditional LTM switching). The other switching is a network-triggered switching. In this case, the second message does not need to include the second indication information, that is, it is not necessary to instruct the terminal to evaluate the switching condition of the first cell. In this example, both the conditional LTM switching command and the unconditional LTM switching command can reuse the second message (i.e., the same MAC CE).

[0166] In yet another example, the second message includes the second indication information but does not include the first indication information. In this example, the second message is a dedicated message for conditional LTM switching.

[0167] In this implementation, when the handover condition of the first cell in S503 is met, the terminal accesses the first cell through random access.

[0168] (2) Implementation method 2

[0169] In implementation method 2, the second message may be a cell handover command message. In addition to the second indication information (and the first indication information), the second message also includes the TA information of the first cell. The TA information of the first cell is used to indicate the TA of the first cell. When the conditions of the first cell are met, the terminal accesses the first cell by means of random access-free access (or access through a physical uplink shared channel (PUSCH)) based on the TA of the first cell.

[0170] For example, before sending the second message, the first network device instructs the terminal to perform early synchronization for the first cell, and then the first network device obtains the TA information of the first cell through the early synchronization process of the first cell.

[0171] The specific process of early synchronization: the first network device sends a TCI state activation indication for the first cell to the terminal, and then the terminal can complete the early downlink synchronization with the first cell according to the activated TCI state activation indication; and / or, the first network device sends a physical downlink control channel (PDCCH) command (PDCCH order) to the terminal. The PDCCH order is used to instruct the terminal to use the first resource to send the first preamble in the first cell; accordingly, after receiving the PDCCH order, the terminal can send the first preamble on the first resource. The second network device determines the TA information of the first cell based on the first preamble, and sends the TA information of the first cell to the first network device, and then the first network device can send the TA information of the first cell to the terminal.

[0172] In this implementation, when the handover condition of the first cell in S503 is met, the terminal accesses the first cell in a random access-free manner.

[0173] (3) Implementation method 3

[0174] In implementation 3, after the second message, the first network device sends the TA information of the first cell to the terminal. For example, after the second message, the first network device sends a cell handover command message to the terminal, and the cell handover command message includes the TA information of the first cell. Unlike implementation 2, the TA information of the first cell is not carried in the second message, but is carried in other messages after the second message (such as the handover command message).

[0175] For example, when sending the second message, the first network device has not yet acquired the TA information of the first cell. After sending the second message, the first network device instructs the terminal to perform early synchronization with respect to the first cell to acquire the TA information of the first cell. The specific process of early synchronization is described above. For example, the first network device may instruct the terminal to perform early synchronization with respect to the first cell and instruct the terminal to evaluate the handover conditions of the first cell through the second message. Further, after acquiring the TA information of the first cell through the early synchronization process of the first cell, the first network device sends a cell handover command message to the terminal.

[0176] In this implementation, when the handover condition of the first cell in S503 is met, the terminal accesses the first cell in a random access-free manner.

[0177] In addition, there are various triggering factors for the first network device to send the second message to the terminal. For example, the first network device obtains the location information of the terminal (for example, RSRP information). Based on the location information of the terminal, if it is determined that the terminal may subsequently move to the coverage of the first cell, or the terminal may subsequently move out of the coverage of the service cell, the second message can be sent to the terminal.

[0178] S503: In response to the second message, the terminal evaluates a handover condition of the first cell.

[0179] It should be understood that, in response to the second message, the terminal activates the handover condition of the first cell. When the handover condition is activated, the terminal evaluates the handover condition of the first cell.

[0180] Exemplarily, the second message (or the second indication information in the second message) includes identification information corresponding to the first cell, and / or identification information of the switching condition of the first cell, such as identification information of the second switching condition. The identification information corresponding to the first cell includes any one of the following: an index value of the first cell, a configuration identifier of the first cell, or a cell global identifier (CGI) of the first cell; the index value or configuration identifier of the first cell corresponds to the CGI of the first cell. The identification information of the second switching condition includes the index value of the second switching condition, and / or the first TCI state identification information corresponding to the second switching condition.

[0181] For example, the second message includes the identification information corresponding to the first cell, that is, the second message indicates which cell's switching condition is to be evaluated through the identification information corresponding to the first cell, but does not indicate which switching condition of the first cell is to be evaluated. In this case, which switching condition of the first cell is to be evaluated specifically may be predefined or preconfigured; or, the terminal evaluates all switching conditions of the first cell by default, or evaluates all switching conditions corresponding to the conditional LTM switching of the first cell, without specific limitation. It should be noted that "all switching conditions" may be one or more switching conditions.

[0182] For another example, the second message includes identification information corresponding to the first cell and identification information of the switching condition of the first cell (such as identification information of the second switching condition), that is, the second message indicates which cell's switching condition is to be evaluated through the identification information corresponding to the first cell, and indicates which switching condition of the first cell is to be evaluated through the identification information of the second switching condition. In this example, the identification information of the second switching condition can uniquely identify the switching condition among multiple switching conditions of the first cell, and the identification information of the switching conditions of different cells can be the same.

[0183] For another example, the second message includes identification information of the handover condition of the first cell (such as identification information of the second handover condition). The identification information of the second handover condition is the index value of the second handover condition, which is the index value of the second handover condition in the M handover conditions and can uniquely identify the handover condition among the M handover conditions. In this case, the first network device can first indicate the correspondence between the M handover conditions and the N cells to the terminal, and then the first network device can indicate which handover condition of which cell to evaluate through the identification information of the second handover condition. In this example, the identification information of the handover conditions of different cells is different.

[0184] For example, the second message includes the first TCI state identification information, and the first TCI state identification information is also used to instruct the terminal to evaluate the switching condition corresponding to the first TCI state identification information. According to the correspondence between the first TCI state identification information and the second switching condition, the terminal determines to evaluate the second switching condition.

[0185] When the second message includes identification information of the switching condition of the first cell (such as identification information of the second switching condition) or the first TCI state identification information, the terminal evaluates the second switching condition without evaluating other switching conditions (i.e., other switching conditions in the deactivated state).

[0186] Optionally, the second message also includes other possible information, such as information indicating that "the terminal initiates conditional switching without random access". When the second message includes this information, the terminal evaluates that the switching conditions of the first cell are met and accesses the first cell without random access.

[0187] It will be understood that the above description uses the first cell as an example. In other embodiments, the first network device may also instruct the terminal to evaluate the handover conditions of one or more other cells. For example, the second message may also be used to instruct the terminal to evaluate the handover conditions of the second cell, i.e., the first network device instructs the terminal to evaluate the handover conditions of multiple cells through the same message. Alternatively, the first network device may instruct the terminal to evaluate the handover conditions of multiple cells through multiple messages. For example, the first network device may send a second message a and a second message b to the terminal, where the second message a is used to instruct the terminal to evaluate the handover conditions of the first cell, and the second message b is used to instruct the terminal to evaluate the handover conditions of the second cell. The second cell is different from the first cell.

[0188] Optionally, the above method further includes S504 and S505:

[0189] S504: The first network device sends a third message to the second network device, where the third message is used to indicate that the terminal has been instructed to evaluate a handover condition of the first cell. Accordingly, the second network device receives the third message.

[0190] Exemplarily, the third message includes identification information corresponding to the first cell (see the above description for specific definition) and third indication information, and the third indication information is used to indicate that the terminal has been instructed to evaluate the switching conditions of the first cell. The third message is also used to indicate the probability of the terminal switching to the first cell. For example, the third message also includes probability information 1 and / or probability information 2, wherein probability information 1 is used to indicate the probability of the terminal switching to (or arriving at) the first cell, and probability information 2 is used to indicate the probability of the terminal switching to (or arriving at) P TCI states (for example, including the first TCI state) of the first cell, and P is an integer greater than or equal to 1. It should be understood that probability information 1 is the probability of the cell, and probability information 2 is the probability of the TCI state of the cell. The probabilities of different TCI states may be the same or different. Specifically, the first network device estimates the target cell for conditional switching, as well as probability information 1 and / or probability information 2 of conditional switching of the target cell based on the location information and historical movement trajectory of the terminal. Optionally, the third message also includes other possible information, such as identification information of P TCI states of the first cell (for example, including the first TCI state), where the P TCI states are activated TCI states, or TCI states that can communicate directly with the terminal.

[0191] Optionally, the first network device sends a fourth message to the second network device, where the fourth message is used to indicate that the TA information of the first cell has been sent to the terminal. The fourth message and the third message may be the same message, or may be different messages.

[0192] Based on the third message (and the fourth message), the second network device determines that the terminal may switch to the first cell in the future through conditional switching, and can then prepare resources in advance to serve the terminal. In one possible implementation, the second network device determines that the terminal may switch to the first cell in the future through conditional switching based on random access-free conditional switching based on the third message and the fourth message, and can then determine the scheduling strategy of the terminal. For example, the second network device receives the third message, and based on the probability information in the third message (i.e., probability information 1 and / or probability information 2), determines that the probability of the terminal switching to the first cell is high (greater than a certain threshold), then: for the CG resources of the terminal, the second network device can try to receive the data of the terminal on the CG resources of the first cell, without allocating the CG resources of the terminal after the third message to other terminals; and / or, the second network device starts to use dynamic grant (DG) to schedule the terminal to perform uplink data transmission for the first cell.

[0193] It should be noted that, in any embodiment of the present application, “having instructed the terminal to evaluate the handover condition of the first cell” can also be understood as “having sent a second message (i.e., a conditional handover command) to the terminal.” In any embodiment of the present application, “having sent the TA information of the first cell to the terminal” can also be understood as “having sent a TA command for the first cell to the terminal.”

[0194] S505 : In response to the evaluation of the handover condition of the first cell, the terminal hands over to the first cell.

[0195] For example, in S503, the terminal evaluates the second switching condition of the first cell. If the evaluation result is determined that the second switching condition of the first cell is met, the terminal switches to the first cell; if the evaluation result is determined that the second switching condition of the first cell is not met, the terminal does not switch to the first cell and continues to evaluate the switching condition of the first cell.

[0196] Regarding the specific implementation of the terminal switching to the first cell:

[0197] In one example, a terminal accesses a first cell in a random access-free manner. Specifically, the terminal accesses the first cell based on a first TCI state and a PUSCH resource, wherein the first TCI state may correspond to a second switching condition, or may be instructed by the first network device to the terminal. "Accessing the first cell" includes: for example, after the terminal sends initial uplink data on the CG resource (i.e., a periodic PUSCH resource) of the first cell, based on the first TCI state, receiving feedback information for the uplink data from the second network device (e.g., a PDCCH carrying terminal identification information), and accordingly, the second network device sends feedback information for the uplink data to the terminal based on the first TCI state; for another example, the terminal receives a DG from the second network device based on the first TCI state, and accordingly, the second network device sends a DG to the terminal based on the first TCI state, the DG being used for the terminal to send initial uplink data on the first cell, such as a DG being used to indicate a one-shot PUSCH resource.

[0198] In another example, the terminal accesses the first cell through random access. Specifically, the terminal accesses the first cell based on random access resources.

[0199] If the terminal performs advance synchronization before switching to the first cell and obtains the TA information of the first cell, the terminal accesses the first cell in a random access-free manner; otherwise, the terminal accesses the first cell in a random access manner.

[0200] In addition, if the first network device instructs the terminal to evaluate the switching conditions of multiple cells, such as the switching conditions of the first cell and the switching conditions of the second cell, then when the evaluation results of the switching conditions of the first cell and the switching conditions of the second cell are determined to be met, when the terminal switches to the first cell based on the switching conditions of the first cell being met, the terminal can cancel the conditional switching of the second cell, that is, no longer switch to the second cell based on the switching conditions of the second cell being met; or, when the terminal switches to the second cell based on the switching conditions of the second cell being met, the terminal can cancel the conditional switching of the first cell (or the terminal determines that the switching conditions of the first cell are in a deactivated state), that is, no longer switch to the first cell based on the switching conditions of the first cell being met. In this way, the problem of frequent terminal switching due to the satisfaction of the switching conditions of multiple cells can be avoided.

[0201] It is understandable that, for subsequent switching, S502 to S505 can be executed by a third network device and the terminal, and the third network device is different from the first network device. For example, after switching to the first cell, the terminal can execute S502' to S505'. In S502', the second network device sends a second message ' to the terminal, and the second message ' is used to indicate the evaluation of the switching conditions of the second cell, and the second cell belongs to the third network device; in S503', in response to the second message ', the terminal evaluates the switching conditions of the second cell; in S504', the second network device sends a third message ' to the third network device, and the third message ' is used to indicate that the terminal has been instructed to evaluate the switching conditions of the second cell; in S505', in response to the evaluation of the switching conditions of the second cell, the terminal switches to the second cell.

[0202] It is understandable that in other embodiments, if the terminal does not receive the second message, the terminal can determine whether the switching condition corresponding to the traditional conditional switching is met. If the switching condition corresponding to the traditional conditional switching is met, the terminal can access the target cell through RACH.

[0203] Using the above method, after the first network device configures the handover conditions of the first cell to the terminal through the first message, it can instruct the terminal to evaluate the handover conditions of the first cell through the second message. Then, in response to the second message, the terminal evaluates the handover conditions of the first cell and switches to the first cell when the evaluation result determines that the handover conditions of the first cell are met. Compared with the LTM handover process shown in Figure 3, since the first network device can send the second message to the terminal in advance when the signal quality of the source cell is good, the terminal does not switch immediately after receiving the second message (such as the handover command message), but evaluates the handover conditions of the first cell, thereby facilitating the avoidance of the problem that the signal quality of the source cell changes rapidly, resulting in the failure of the handover command message to be sent, thereby affecting the handover, and improving the robustness of the handover. Compared with the traditional conditional handover process shown in Figure 4, after the first network device configures the handover conditions of the first cell for the terminal, the terminal does not immediately evaluate the handover conditions of the first cell, but evaluates the handover conditions of the first cell after receiving the instruction of the network device, thereby facilitating the network device's control over the terminal and facilitating the avoidance of the problem that the terminal evaluates too early, resulting in excessive energy consumption or premature handover.

[0204] Optionally, the second message includes TA information of the first cell, and when the evaluation result determines that the switching condition of the first cell is met, the terminal can access the first cell without random access, thereby effectively reducing the switching delay and improving the switching efficiency.

[0205] Optionally, the switching condition of the first cell corresponds to the TCI state, and the terminal can evaluate the switching condition based on the corresponding TCI state, and when the evaluation result shows that the switching condition is met, access the first cell based on the corresponding TCI state, so as to complete the beam alignment in advance during the switching process and reduce the interruption of data transmission.

[0206] Example 2

[0207] In the second embodiment ( FIG6 ), based on the first embodiment, a possible implementation process will be described using scenario 2 as an example. That is, the second embodiment can be combined with the first embodiment, and the specific implementation of the relevant steps in the second embodiment can refer to the first embodiment.

[0208] FIG6 is a flow chart of the communication method according to the second embodiment of the present application. As shown in FIG6 , the method includes:

[0209] S601, the CU sends a message 1 to the second DU, where the message 1 is used to request LTM configuration of the first cell.

[0210] Here, there may be multiple triggering factors for the CU to send Message 1 to the second DU. For example, the terminal sends a measurement report to the first DU, and the measurement report includes the measurement results of Layer 3, which may specifically include the measurement results of neighboring cells. The neighboring cell refers to the cell to which the terminal may switch after moving. In addition, the first DU sends the measurement report to the CU, for example, the first DU sends an uplink (UL) RRC message to the CU, and the UL RRC message includes the measurement report; accordingly, the CU can decide whether to initiate LTM configuration based on the measurement report. If the CU decides to initiate LTM configuration, it can send Message 1 to the second DU.

[0211] Message 1 may include first identification information, the first identification information is used to identify the first DU, for example, the first identification information corresponds to the ID of the first DU. Message 1 is also used to request early synchronization configuration for the first identification information, the early synchronization configuration belonging to the configuration of the first cell.

[0212] S602 , the second DU sends message 2 to the CU; correspondingly, the CU receives message 2.

[0213] Here, message 2 includes early synchronization configuration information A and / or early synchronization configuration information B. Optionally, message 2 also includes configuration information of the first cell (such as lower-layer RRC configuration and / or reference signal configuration), CG resource information allocated by the second DU to the terminal for the first cell, etc. The lower-layer RRC configuration can be layer 1 / layer 2 configuration, such as bearer configuration information and / or media access control configuration information.

[0214] Among them, the early synchronization configuration information A is the configuration information subsequently sent to the first DU, so that the first DU can instruct the terminal to perform early synchronization according to the early synchronization configuration information A; the early synchronization configuration information B is the configuration information subsequently sent to the terminal, so that the terminal can perform early synchronization according to the early synchronization configuration information B and the early synchronization indication of the first DU.

[0215] The early synchronization configuration information A and the early synchronization configuration information B may be the same information, or there may be some differences. For example, the early synchronization configuration information A includes the indexes of multiple preambles, and the early synchronization configuration information B includes the root sequence of the preamble. In this way, the first DU can indicate the index of one of the preambles (such as the first preamble) to the terminal, and then the terminal determines the first preamble based on the root sequence of the preamble and the index of the first preamble indicated by the first DU, and uses the first preamble for early synchronization.

[0216] Message 2 also includes first identification information, and the above-mentioned advance synchronization configuration information A and / or advance synchronization configuration information B corresponds to the first identification information.

[0217] In addition, the above-mentioned message 1 may be a UE context setup request message, and the message 2 may be a UE context modification response message.

[0218] S603 , the CU sends message 3 (ie, the fifth message) to the first DU; correspondingly, the first DU receives message 3 .

[0219] Exemplarily, message 3 includes the early synchronization configuration information A and the identification information corresponding to the first cell, and may also include other possible information, such as the reference signal configuration of the first cell.

[0220] Optionally, message 3 includes indication information 1, which is used to instruct the first DU to configure the switching conditions of N cells. For example, indication information 1 includes identification information corresponding to N cells. Furthermore, after receiving message 3, the first DU can determine the M switching conditions corresponding to the N cells (and the initial states of the M switching conditions). In this embodiment, "N=1, N cells are the first cell" will be used as an example for description. When there are multiple cells, the description of the first cell can be referred to.

[0221] S604 , the first DU sends message 4 to the CU; correspondingly, the CU receives message 4 .

[0222] Exemplarily, message 4 includes configuration information of M switching conditions, and optionally, also includes initial state information of M switching conditions.

[0223] The above message 3 may be a UE context modification request message, and the message 4 may be a UE context modification response message.

[0224] S605: The CU sends an RRC reconfiguration message to the terminal; correspondingly, the terminal receives the RRC reconfiguration message.

[0225] Exemplarily, there are multiple ways for the CU to send an RRC reconfiguration message to the terminal. For example, the CU sends a downlink (DL) RRC message to the first DU, where the DL RRC message includes the RRC reconfiguration message; accordingly, after receiving the DL RRC message, the first DU sends the RRC reconfiguration message to the terminal.

[0226] The RRC reconfiguration message may include configuration information of the first cell (such as lower-layer RRC configuration and / or reference signal configuration) and configuration information of the M handover conditions, and optionally, initial state information of the M handover conditions. In addition, the RRC reconfiguration message may also include other possible information, such as early synchronization configuration information B. The content of the RRC reconfiguration message may refer to the description of the first message in Example 1.

[0227] S606: The terminal sends an RRC reconfiguration completion message to the CU; correspondingly, the CU receives the RRC reconfiguration completion message.

[0228] Here, after receiving the RRC reconfiguration message, the terminal may send a UL RRC message to the first DU, where the UL RRC message includes an RRC reconfiguration complete message; further, the first DU may forward the RRC reconfiguration complete message to the CU.

[0229] S607 , the first DU sends a PDCCH order to the terminal, where the PDCCH order is used to instruct the terminal to send a random access preamble on the first cell; accordingly, the terminal receives the PDCCH order.

[0230] S608 , in response to the PDCCH order, the terminal sends a random access preamble on the first cell; correspondingly, the second DU receives the random access preamble.

[0231] Exemplarily, the first DU may send a PDCCH order to the terminal based on the early synchronization configuration information A. For example, the PDCCH order includes an index of the first preamble and a mask index (MASK index) corresponding to the first resource. Accordingly, the terminal sends a random access preamble (i.e., a first preamble) of the first cell to the second DU on the first resource based on the early synchronization configuration information B and the PDCCH order of the first cell.

[0232] S609: The second DU determines the TA information of the first cell according to the random access preamble, and sends message 5 to the CU. Accordingly, the CU receives message 5.

[0233] Exemplarily, after receiving the first preamble on the first resource, the second DU may determine the TA information of the first cell and the first identification information corresponding to the first resource and the first preamble based on the first preamble, and then send message 5 to the CU. For example, message 5 includes the TA information of the first cell, random access resource information corresponding to the TA information of the first cell, and the first identification information, wherein the random access resource information corresponding to the TA information of the first cell includes the index of the first preamble and the random access radio network temporary identity (RA-RNTI) corresponding to the first resource.

[0234] S610 , the CU sends a message 6 to the first DU according to the message 5 , where the message 6 includes the TA information of the first cell and the random access resource information corresponding to the TA information of the first cell; accordingly, the first DU receives the message 6 .

[0235] Exemplarily, the CU sends message 6 to the first DU according to the first identification information in message 5. After receiving message 6, the first DU can determine that the TA information of the first cell corresponds to the terminal according to the random access resource information corresponding to the TA information of the first cell.

[0236] It is understandable that the terminal can also perform downlink synchronization with the first cell. For example, the first DU sends a TCI state activation indication of the first cell to the terminal, and the activation indication is used to activate the TCI state of the first cell. The terminal tracks the downlink timing of the first cell based on the activation indication of the first cell.

[0237] S611, the first DU sends a handover command message (ie, a second message) to the terminal, where the second message is used to instruct to evaluate a handover condition of the first cell; accordingly, the terminal receives the second message.

[0238] This embodiment is described by taking the second message as a handover command message as an example, for example, the second message includes the second indication information (and the first indication information) and also includes the TA information of the first cell. For other possible implementations, refer to the description in the first embodiment.

[0239] S612: In response to the handover command message, the terminal evaluates a handover condition of the first cell.

[0240] Here, the specific implementation of the terminal evaluating the handover condition of the first cell may refer to the description in the first embodiment.

[0241] S613, the first DU sends a cell switching notification message (ie, the third message a) to the CU, where the cell switching notification message is used to indicate that the terminal has been instructed to evaluate the switching condition of the first cell; accordingly, the CU receives the cell switching notification message.

[0242] Exemplarily, the cell handover notification message is further used to indicate the probability of the terminal handing over to the first cell, and the cell handover notification message is further used to indicate that the TA information of the first cell has been sent to the terminal.

[0243] S614, the CU sends a cell switching notification message (ie, the third message b) to the second DU; accordingly, the second DU receives the cell switching notification message.

[0244] S615: The second DU determines a scheduling policy for the terminal according to the cell switching notification message, and schedules the terminal according to the scheduling policy.

[0245] Here, the specific implementation of the second DU scheduling terminal may refer to the description in the first embodiment.

[0246] S616: In response to the evaluation of the handover condition of the first cell, the terminal hands over to the first cell.

[0247] Here, the specific implementation of the terminal switching to the first cell may refer to the description in the first embodiment.

[0248] Example 3

[0249] In the third embodiment ( FIG. 7 ), a possible implementation process will be described based on the first embodiment, taking scenario 3 as an example. That is, the third embodiment can be combined with the first embodiment, and the specific implementation of the relevant steps in the third embodiment can refer to the first embodiment.

[0250] FIG7 is a flow chart of the communication method according to the third embodiment of the present application. As shown in FIG7 , the method includes:

[0251] S701 , the first CU sends a message 1a (ie, the sixth message) to the second CU, where the message 1a is used to request LTM configuration of the first cell; accordingly, the second CU receives the message 1a .

[0252] Here, there may be multiple triggering factors for the first CU to send message 1a to the second CU. For example, the terminal sends a measurement report to the first DU, and the measurement report includes the measurement results of layer 3, which may specifically include the measurement results of the neighboring cells. The neighboring cells refer to the cells that the terminal may switch to after moving. Furthermore, the first DU sends the measurement report to the first CU, for example, the first DU sends a UL RRC message to the first CU, and the UL RRC message includes the measurement report; accordingly, the first CU can decide whether to initiate LTM configuration based on the measurement report. If the first CU decides to initiate LTM configuration, it can send message 1a to the second CU.

[0253] The message 1a may include first identification information, the first identification information being used to identify the first DU. The message 1a is also used to request an early synchronization configuration for the first identification information, the early synchronization configuration belonging to the configuration of the first cell.

[0254] S702 : The second CU sends a message 1b (ie, the seventh message) to the second DU. The message 1b is used to request LTM configuration of the first cell.

[0255] Message 1b includes first identification information and second identification information. The second identification information is used to identify the source access network node (or the CU of the source access network node, i.e., the first CU). For example, the second identification information corresponds to the ID of the first CU. Message 1b is used to request early synchronization configuration for the first identification information and the second identification information. The early synchronization configuration belongs to the configuration of the first cell.

[0256] S703 , the second DU sends a message 2a to the second CU; correspondingly, the second CU receives the message 2a.

[0257] Message 2a includes the pre-synchronization configuration information A and / or the pre-synchronization configuration information B, the first identification information, and the second identification information. Message 2a may also include other possible information, as described in the second embodiment for details.

[0258] S704 , the second CU sends a message 2b to the first CU; correspondingly, the first CU receives the message 2b.

[0259] Exemplarily, the second CU sends a message 2b to the first CU based on the second identification information in the message 2a, wherein the message 2b includes the pre-synchronization configuration information A and / or the pre-synchronization configuration information B and the first identification information.

[0260] S705 , the first CU sends message 3 (ie, the fifth message) to the first DU; accordingly, the first DU receives message 3 .

[0261] Exemplarily, message 3 includes the early synchronization configuration information A and the identification information corresponding to the first cell, and may also include other possible information, such as the reference signal configuration of the first cell. The first CU may send message 3 to the first DU based on the first identification information in message 2.

[0262] Optionally, message 3 includes indication information 1, which is used to instruct the first DU to configure the handover conditions for N cells. Furthermore, after receiving message 3, the first DU can determine the M handover conditions corresponding to the N cells (as well as the initial states of the M handover conditions). In this embodiment, "N = 1, N cells are the first cell" will be used as an example for description.

[0263] S706 , the first DU sends message 4 to the first CU; correspondingly, the first CU receives message 4 .

[0264] Exemplarily, message 4 includes configuration information of M switching conditions, and optionally also includes initial state information of M switching conditions.

[0265] S707: The first CU sends an RRC reconfiguration message to the terminal; accordingly, the terminal receives the RRC reconfiguration message.

[0266] The RRC reconfiguration message may include configuration information of the first cell (such as lower-layer RRC configuration and / or reference signal configuration) and configuration information of the M handover conditions, and optionally, initial state information of the M handover conditions. In addition, the RRC reconfiguration message may also include other possible information, such as early synchronization configuration information B. The content of the RRC reconfiguration message may refer to the description of the first message in Example 1.

[0267] S708 , the terminal sends an RRC reconfiguration completion message to the first CU; correspondingly, the first CU receives the RRC reconfiguration completion message.

[0268] S709 , the first DU sends a PDCCH order to the terminal, where the PDCCH order is used to instruct the terminal to send a random access preamble on the first cell; accordingly, the terminal receives the PDCCH order.

[0269] S710 , in response to a PDCCH order, the terminal sends a random access preamble on the first cell; correspondingly, the second DU receives the random access preamble.

[0270] Exemplarily, the first DU may send a PDCCH order to the terminal based on the early synchronization configuration information A. For example, the PDCCH order includes an index of the first preamble and a mask index (MASK index) corresponding to the first resource. Accordingly, the terminal sends a random access preamble (i.e., a first preamble) of the first cell to the second DU on the first resource based on the early synchronization configuration information B and the PDCCH order of the first cell.

[0271] S711: The second DU determines the TA information of the first cell according to the random access preamble and sends a message 5a to the second CU. Correspondingly, the second CU receives the message 5a.

[0272] Exemplarily, after receiving the first preamble on the first resource, the second DU may determine the TA information of the first cell based on the first preamble, as well as the first identification information and the second identification information corresponding to the first resource and the first preamble, and then send message 5a to the second CU. For example, message 5a includes the TA information of the first cell and the random access resource information corresponding to the TA information of the first cell, the first identification information, and the second identification information, wherein the random access resource information corresponding to the TA information of the first cell includes the index of the first preamble and the RA-RNTI corresponding to the first resource.

[0273] S712: In response to the message 5a, the second CU sends a message 5b to the first CU; accordingly, the first CU receives the message 5b.

[0274] Here, the second CU may send a message 5b to the first CU based on the second identification information in the message 5a, wherein the message 5b includes the TA information of the first cell, the random access resource information corresponding to the TA information of the first cell, and the first identification information.

[0275] S713 , the first CU sends message 6 to the first DU, where message 6 includes TA information of the first cell and random access resource information corresponding to the TA information of the first cell; accordingly, the first DU receives message 6 .

[0276] Exemplarily, the first CU sends message 6 to the first DU according to the first identification information in message 5b. After receiving message 6, the first DU can determine that the TA information of the first cell corresponds to the terminal according to the random access resource information corresponding to the TA information of the first cell.

[0277] It is understandable that the terminal can also perform downlink synchronization with the first cell. For example, the first DU sends a TCI state activation indication of the first cell to the terminal, and the activation indication is used to activate the TCI state of the first cell. The terminal tracks the downlink timing of the first cell based on the activation indication of the first cell.

[0278] S714, the first DU sends a handover command message (ie, a second message) to the terminal, where the second message is used to instruct to evaluate a handover condition of the first cell; accordingly, the terminal receives the second message.

[0279] This embodiment is described by taking the second message as a handover command message as an example, for example, the second message includes the second indication information (and the first indication information) and also includes the TA information of the first cell. For other possible implementations, refer to the description in the first embodiment.

[0280] S715 : In response to the handover command message, the terminal evaluates a handover condition of the first cell.

[0281] S716, the first DU sends a cell switching notification message (i.e., the third message) to the second DU through the first CU and the second CU. The cell switching notification message is used to indicate that the terminal has been instructed to evaluate the switching conditions of the first cell; accordingly, the second DU receives the cell switching notification message.

[0282] Exemplarily, the cell handover notification message is further used to indicate the probability of the terminal handing over to the first cell, and the cell handover notification message is further used to indicate that the TA information of the first cell has been sent to the terminal.

[0283] S717 : In response to the cell switching notification message, the second DU determines a scheduling policy for the terminal and schedules the terminal according to the scheduling policy.

[0284] Here, the specific implementation of the second DU scheduling terminal may refer to the description in the first embodiment.

[0285] S718 : In response to the evaluation of the handover condition of the first cell, the terminal hands over to the first cell.

[0286] It is understood that the above-mentioned embodiments 2 and 3 are described using scenarios 2 and 3 as examples, respectively. For other switching scenarios (such as scenarios 1, 4, and 5), reference can be made to the descriptions of embodiments 2 and 3. When the embodiments of the present application are applied to different switching scenarios, the message names may be different, and the embodiments of the present application do not limit the message names.

[0287] Example 4

[0288] In the fourth embodiment, scenario 3 is taken as an example to describe a possible implementation process of LTM switching.

[0289] FIG8 is a flow chart of the communication method according to the fourth embodiment of the present application. As shown in FIG8 , the method includes:

[0290] S801 , a first CU sends a message 1a to a second CU, where the message 1a is used to request LTM configuration of a first cell; correspondingly, the second CU receives the message 1a .

[0291] The message 1a may include first identification information, the first identification information being used to identify the first DU. The message 1a is also used to request an early synchronization configuration for the first identification information, the early synchronization configuration belonging to the configuration of the first cell.

[0292] S802: The second CU sends a message 1b to the second DU. The message 1b is used to request LTM configuration of the first cell.

[0293] Message 1b includes first identification information and second identification information, where the second identification information is used to identify the source access network node (or the CU of the source access network node, i.e., the first CU). Message 1b is used to request an early synchronization configuration for the first identification information and the second identification information, where the early synchronization configuration belongs to the configuration of the first cell.

[0294] S803 , the second DU sends a message 2a to the second CU; correspondingly, the second CU receives the message 2a.

[0295] Message 2a includes the pre-synchronization configuration information A and / or the pre-synchronization configuration information B, the first identification information, and the second identification information. Message 2a may also include other possible information, as described in the second embodiment for details.

[0296] S804 , the second CU sends a message 2b to the first CU; correspondingly, the first CU receives the message 2b.

[0297] Exemplarily, the second CU sends a message 2b to the first CU based on the second identification information in the message 2a, wherein the message 2b includes the pre-synchronization configuration information A and / or the pre-synchronization configuration information B and the first identification information.

[0298] S805 , the first CU sends message 3 (ie, the fifth message) to the first DU; accordingly, the first DU receives message 3 .

[0299] Exemplarily, message 3 also includes early synchronization configuration information A and other possible information, such as reference signal configuration of the first cell. The first CU may send message 3 to the first DU based on the first identification information in message 2.

[0300] S806 , the first DU sends message 4 to the first CU; correspondingly, the first CU receives message 4 .

[0301] Exemplarily, message 4 may include the channel state information (CSI) resource configuration of the source cell, where the CSI resource configuration is used by the terminal to send lower layer measurement results (such as layer 1 / layer 2 measurement results) of the candidate cell (such as the first cell) in the source cell.

[0302] S807: The first CU sends an RRC reconfiguration message to the terminal; accordingly, the terminal receives the RRC reconfiguration message.

[0303] Among them, the RRC reconfiguration message may include the early synchronization configuration information B, the lower layer RRC configuration and reference signal configuration of the first cell, and optionally, also include the CG resource information allocated by the second DU to the terminal for the first cell, etc.

[0304] S808. The terminal sends an RRC reconfiguration completion message to the first CU; accordingly, the first CU receives the RRC reconfiguration completion message.

[0305] S809 , the first DU sends a PDCCH order to the terminal, where the PDCCH order is used to instruct the terminal to send a random access preamble on the first cell; accordingly, the terminal receives the PDCCH order.

[0306] S810 , in response to a PDCCH order, the terminal sends a random access preamble on the first cell; accordingly, the second DU receives the random access preamble.

[0307] Exemplarily, the first DU may send a PDCCH order to the terminal based on the early synchronization configuration information A. For example, the PDCCH order includes an index of the first preamble and a mask index (MASK index) corresponding to the first resource. Accordingly, the terminal sends a random access preamble (i.e., a first preamble) of the first cell to the second DU on the first resource based on the early synchronization configuration information B and the PDCCH order of the first cell.

[0308] S811: The second DU determines the TA information of the first cell according to the random access preamble and sends a message 5a to the second CU. Correspondingly, the second CU receives the message 5a.

[0309] Exemplarily, after receiving the first preamble on the first resource, the second DU can determine the TA information of the first cell based on the first preamble, and determine the first identification information and the second identification information corresponding to the first resource and the first preamble, and then send message 5a to the second CU. For example, message 5a includes the TA information of the first cell, the random access resource information corresponding to the TA information of the first cell, the first identification information, and the second identification information, wherein the random access resource information corresponding to the TA information of the first cell includes the index of the first preamble and the RA-RNTI corresponding to the first resource.

[0310] S812: In response to the message 5a, the second CU sends a message 5b to the first CU; accordingly, the first CU receives the message 5b.

[0311] Here, the second CU may send a message 5b to the first CU based on the second identification information in the message 5a, wherein the message 5b includes the TA information of the first cell, the random access resource information corresponding to the TA information of the first cell, and the first identification information.

[0312] S813 , the first CU sends message 6 to the first DU, where message 6 includes TA information of the first cell and random access resource information corresponding to the TA information of the first cell; accordingly, the first DU receives message 6.

[0313] Exemplarily, the first CU sends message 6 to the first DU according to the first identification information in message 5b. After receiving message 6, the first DU can determine that the TA information of the first cell corresponds to the terminal according to the random access resource information corresponding to the TA information of the first cell.

[0314] It is understandable that the terminal can also perform downlink synchronization with the first cell. For example, the first DU sends a TCI state activation indication of the first cell to the terminal, and the activation indication is used to activate the TCI state of the first cell. The terminal tracks the downlink timing of the first cell based on the activation indication of the first cell.

[0315] S814. The first DU sends a handover command message to the terminal, where the handover command message is used to instruct the terminal to handover to the first cell. Accordingly, the terminal receives the handover command message.

[0316] Exemplarily, the terminal reports the lower layer measurement results of the first cell to the first DU. If the first DU determines to switch the terminal to the first cell based on the lower layer measurement results of the first cell reported by the terminal, the first DU sends a switching command message to the terminal. The switching command message includes the identification information corresponding to the first cell (such as the configuration identifier of the first cell) and the TA information of the first cell.

[0317] S815. The first DU sends a cell switching notification message to the second DU through the first CU and the second CU. The cell switching notification message is used to indicate that the terminal has been instructed to switch to the first cell. Correspondingly, the second DU receives the cell switching notification message.

[0318] Exemplarily, the cell switching notification message includes identification information corresponding to the first cell (such as the CGI of the first cell), and optionally also includes activated TCI status information of the first cell.

[0319] S816 , in response to the cell switching notification message, the second DU determines a scheduling policy for the terminal and schedules the terminal according to the scheduling policy.

[0320] For example, after receiving the cell handover notification message, the second DU can learn that the terminal is about to be handed over to the first cell and can then determine the terminal's scheduling strategy. For example, for the terminal's CG resources, the second DU can attempt to receive the terminal's data on the CG resources without allocating the terminal's CG resources to other terminals; and / or, the second DU begins using the DG scheduling terminal for uplink data transmission.

[0321] S817: In response to the handover command message, the terminal switches to the first cell.

[0322] Here, the terminal can access the first cell in a random access-free manner according to the TA information of the first cell, that is, access the target cell through CG PUSCH or DG PUSCH, thereby completing the handover, instead of accessing the first cell through RACH.

[0323] It is understandable that the above-mentioned fourth embodiment is described using scenario 3 as an example. Other handover scenarios (such as scenario 4 and scenario 5) can refer to the description of the fourth embodiment. When the embodiment of the present application is applied to different handover scenarios, the message names may be different. For example, in scenario 4, the message names exchanged between different network devices may be handover request messages and handover request acknowledgement messages. The embodiment of the present application does not limit the message names. In addition, the above-mentioned fourth embodiment focuses on the differences between the fourth embodiment and the third embodiment in terms of the process. Except for the differences, the specific implementation of the relevant steps in the fourth embodiment can refer to the third embodiment.

[0324] Example 5

[0325] FIG9 is a flow chart of the communication method according to the fifth embodiment of the present application. As shown in FIG9 , the method includes:

[0326] S901, a first network device sends an eighth message to a terminal, and the terminal is in an RRC connected state; accordingly, the terminal receives the eighth message.

[0327] Exemplarily, the eighth message is an RRC message, such as an RRC reconfiguration message. The eighth message includes the configuration of the first TCI state and the configuration of the second TCI state, and also includes the identification information of the timing advance group (TAG) associated with the first TCI state (i.e., the identification information of the first TAG) and the identification information of the TAG associated with the second TCI state (i.e., the identification information of the second TAG). The first TCI state and the second TCI state belong to the same cell, the first TCI state and the second TCI state can be associated with different control resource sets (CORESET Pools), the first TCI state is different from the second TCI state, and the first TAG is different from the second TAG.

[0328] The cell to which the first TCI state and the second TCI state belong may be a serving cell of the terminal. In this case, the first network device and the second network device described below are the same access network node (i.e., the serving access network node of the terminal). Alternatively, the cell to which the first TCI state and the second TCI state belong may also be a candidate cell of the terminal (such as the first cell). In this case, the first network device is the source access network node of the terminal, the second network device is the candidate access network node of the terminal, and the first cell belongs to the cell managed by the second network device. In this embodiment, the description will be made using the cell to which the first TCI state and the second TCI state belong as the first cell as an example.

[0329] As a possible implementation, the eighth message and the first message in Example 1 are the same message, that is, the eighth message may also include other possible information, such as configuration information of M switching conditions, etc., please refer to the description in Example 1 for details.

[0330] S902, the first network device sends a ninth message to the terminal device; correspondingly, the terminal receives the ninth message.

[0331] Exemplarily, the ninth message includes a TA command of the first TAG, and the TA command of the first TAG includes first TA information and information indicating the first TAG. The specific implementation of the first network device obtaining the first TA information may refer to the description in the first embodiment.

[0332] Optionally, the ninth message further includes a TA command of the second TAG, and the TA command of the second TAG includes second TA information and information for indicating the second TAG.

[0333] Specifically, the ninth message includes a field whose different values ​​correspond to different tags, for example, "1" indicates the first tag and "0" indicates the second tag. The correspondence between different values ​​and tags is indicated to the terminal in the eighth message.

[0334] As a possible implementation, the ninth message and the handover command message in embodiment 1 may be the same message. For example, the TA information of the first cell in embodiment 1 may include the first TA information (and the second TA information).

[0335] S903: The second network device sends an RRC release message to the terminal. The RRC release message is used to instruct the terminal to migrate from the RRC connected state to the RRC deactivated state (RRC inactive state).

[0336] Exemplarily, the RRC release message includes a transmission configuration, which is associated with the identification information of the first TAG.

[0337] In the RRC deactivated state, the terminal maintains the configuration of the first TCI state and the configuration of the second TCI state, as well as the identification information of the TAG associated with the first TCI state (i.e., the identification information of the first TAG) and the identification information of the TAG associated with the second TCI state (i.e., the identification information of the second TAG).

[0338] As a possible implementation, the second network device can determine which TAG's TA information is used for transmission in the RRC deactivated state from the TA information of multiple TAGs associated with the first cell (such as the TA information of the first TAG and the TA information of the second TAG), and indicate it to the terminal through an RRC release message. In this case, the RRC release message also includes the identification information of the TAG corresponding to the transmission configuration (i.e., the identification information of the first TAG).

[0339] As another possible implementation, the RRC release message does not include identification information of the TAG corresponding to the transmission configuration, and the terminal determines that the transmission configuration corresponds to the first TAG in a protocol-defined manner. For example, the protocol defines: the transmission configuration corresponds to the TAG with the smallest or largest identification information, or the transmission configuration corresponds to the TAG corresponding to the timing advance timer (TAT) that is running when the RRC release message is received. For example, when the terminal receives the RRC release message, the TAT corresponding to the first TAG is running, and the TAT corresponding to the second TAG is not running, then the terminal can determine that the transmission configuration corresponds to the first TAG.

[0340] The above-mentioned transmission configuration can be a configured grant small data transmission (CG-SDT) configuration or a sounding reference signal (SRS) configuration in the RRC deactivated state. For example, the CG-SDT configuration includes time-frequency resource information of the CG-SDT, and the SRS configuration in the RRC deactivated state includes time-frequency resource information of the SRS. The time-frequency resources of the CG-SDT are used by the terminal to send uplink data to the second network device in the RRC deactivated state; the time-frequency resources of the SRS are used by the terminal to send the SRS to the second network device in the RRC deactivated state.

[0341] Optionally, before S903, the terminal may switch from the source cell to the first cell (for example, switch to the first cell in the manner described in the first embodiment), or the terminal may access the first cell in other possible ways, and the specific implementation is not limited.

[0342] S904: In response to the RRC release message, the terminal transitions to an RRC deactivated state.

[0343] Exemplarily, the terminal may communicate with the second network device using the TA information of the first TAG (i.e., the first TA information) in the RRC deactivated state. For example, the terminal sends CG-SDT data to the second network device based on the CG-SDT configuration and the first TA information; for another example, the terminal sends an inactive SRS to the second network device based on the SRS configuration in the RRC deactivated state and the first TA information.

[0344] Optionally, the terminal may determine whether the first TA information is valid based on the TCI state associated with the first TAG. For example, for the first TCI state associated with the first TAG, the terminal may receive and measure the signal (SSB or CSI-RS) associated with the first TCI state, and determine whether the first TA information is valid based on the change in the measured signal quality. For example, if the current signal quality minus the previous signal quality is less than or equal to the threshold value, the first TA information is determined to be valid; otherwise, the first TA information is determined to be invalid. The terminal will not determine whether the first TA is valid based on the TCI state associated with the second TAG.

[0345] In addition, the fifth embodiment may be implemented independently, or the fifth embodiment may be implemented in combination with the first embodiment or other embodiments.

[0346] With respect to the above embodiments, it can be understood that:

[0347] (1) In any embodiment of the present invention, “in response to A (message), execute B (behavior)” can be understood as “according to A, execute B”, or it can be understood as “because of A, execute B”.

[0348] (2) In the various embodiments of this application, unless otherwise specified or logically conflicting, the terms and / or descriptions between different embodiments are consistent and may be referenced to each other. The technical features in different embodiments may be combined to form new embodiments based on their inherent logical relationships. In addition, within the same embodiment, different implementations or different examples may also reference or refer to each other.

[0349] (3) The various numerical numbers involved in this application are only for the convenience of description and are not used to limit the scope of this application. The step numbers of the above-mentioned flowcharts are only an example of the execution process and do not constitute a restriction on the order of execution of the steps. That is, the size of the step numbers does not mean the order of execution. The execution order of each step should be determined by its function and internal logic. In addition, not all the steps shown in the flowcharts are required to be executed. Some steps can be added or deleted based on actual needs.

[0350] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of the interaction between the network side device and the terminal side device. It can be understood that in order to realize the above functions, the network side device and the terminal side device may include hardware structures and / or software modules corresponding to the execution of each function. It should be easy for those skilled in the art to realize that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the embodiments of the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0351] In the embodiments of the present application, the network-side device and the terminal-side device can be divided into functional units according to the above-mentioned method examples. For example, each functional unit can be divided according to each function, or two or more functions can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or software functional units.

[0352] In the case of adopting an integrated unit, Figure 10 shows a possible exemplary block diagram of the device involved in the embodiments of the present application. As shown in Figure 10, the device 1000 may include: a processing unit 1002 and a communication unit 1003. The processing unit 1002 is used to control and manage the actions of the device 1000. The communication unit 1003 is used to support the communication between the device 1000 and other devices. Optionally, the communication unit 1003 is also called a transceiver unit, and may include a receiving unit and / or a sending unit, which are used to perform receiving and sending operations respectively. The device 1000 may also include a storage unit 1001 for storing program code and / or data of the device 1000.

[0353] (1) The apparatus 1000 may be a terminal-side apparatus (e.g., a terminal) in the above-described embodiments. The processing unit 1002 may support the apparatus 1000 in executing the terminal actions in the above-described method examples. Alternatively, the processing unit 1002 primarily executes the internal actions of the terminal in the method examples, and the communication unit 1003 may support communication between the apparatus 1000 and other devices.

[0354] For example, in one embodiment, the communication unit 1003 is used to: receive a first message from a first network side device, the first message being used to configure M switching conditions; receive a second message from the first network side device, the second message being used to indicate the evaluation of the switching conditions of the first cell; wherein the M switching conditions include the switching conditions of the first cell, and M is an integer greater than or equal to 1; the processing unit 1002 is used to: evaluate the switching conditions of the first cell in response to the second message.

[0355] In one possible design, the second message includes: identification information corresponding to the first cell, and / or identification information of the switching condition of the first cell.

[0356] In one possible design, the M switching conditions correspond to N cells, where the N cells include the first cell, N is less than or equal to M, and N is an integer greater than or equal to 1.

[0357] In one possible design, the first message is also used to indicate that the switching condition of the first cell is not to be evaluated.

[0358] In one possible design, the second message includes first indication information, where the first indication information is used to indicate conditional switching; the second message also includes second indication information, where the second indication information is used to indicate evaluating the switching condition of the first cell in the case of the conditional switching.

[0359] In one possible design, the processing unit 1002 is further used to: switch to the first cell in response to an evaluation of a switching condition of the first cell.

[0360] In one possible design, the processing unit 1002 is specifically used to: switch to the first cell if an evaluation result determines that the switching condition of the first cell is met.

[0361] In one possible design, the switching conditions of the first cell include K switching conditions, where K is an integer greater than or equal to 1; the switching conditions of the first cell are met, including: one of the K switching conditions of the first cell is met.

[0362] In one possible design, the K switching conditions include a first switching condition and a second switching condition; the type of the first switching condition and the type of the second switching condition are different; or, when the type of the first switching condition and the type of the second switching condition are the same, the threshold values ​​corresponding to the first switching condition and the second switching condition are different; or, the first switching condition is evaluated after receiving the first message, and the second switching condition is evaluated after receiving the second message.

[0363] In one possible design, the switching condition of the first cell is met, including at least one of the following: the signal quality of the source cell is less than or equal to a first threshold value; the signal quality of the first cell is greater than or equal to a second threshold value; the difference between the signal quality of the first cell and the signal quality of the source cell is greater than or equal to a third threshold value.

[0364] In one possible design, the switching condition of the first cell corresponds to the first transmission configuration indication TCI state; the processing unit 1002 is specifically used to: access the first cell based on the first TCI state corresponding to the switching condition of the first cell.

[0365] In one possible design, the first message or the second message is also used to indicate that the switching condition of the first cell corresponds to the first TCI state.

[0366] In one possible design, the processing unit 1002 is specifically used to: access the first cell via a random access-free manner.

[0367] In one possible design, the second message includes the timing advance TA information of the first cell; or, the method further includes: receiving the TA information of the first cell after the second message; wherein, the TA information of the first cell is used to access the first cell in a random access-free manner.

[0368] In one possible design, after switching to the first cell, the processing unit 1002 is further used to cancel conditional switching that meets switching conditions of other cells.

[0369] (2) The apparatus 1000 may be the first network-side apparatus (e.g., the first network device) in the above-described embodiments. The processing unit 1002 may support the apparatus 1000 in executing the actions of the first network device in each of the above-described method examples. Alternatively, the processing unit 1002 may primarily execute the internal actions of the first network device in the method examples, and the communication unit 1003 may support communication between the apparatus 1000 and other devices.

[0370] For example, in one embodiment, the communication unit 1003 is used to: send a first message to a terminal side device, where the first message is used to configure M switching conditions; send a second message to the terminal side device, where the second message is used to instruct the terminal side device to evaluate the switching conditions of the first cell; wherein the M switching conditions include the switching conditions of the first cell, and M is an integer greater than or equal to 1.

[0371] In one possible design, the communication unit 1003 is further used to: send a third message, where the third message is used to indicate that the terminal side device has been instructed to evaluate the switching conditions of the first cell.

[0372] In one possible design, the communication unit 1003 is further used to: send a fourth message, where the fourth message is used to indicate that the TA information of the first cell has been sent to the terminal side device.

[0373] In one possible design, the third message is also used to indicate the probability of the terminal side device switching to the first cell.

[0374] In one possible design, the M switching conditions correspond to N cells, where the N cells include the first cell, N is less than or equal to M, and N is an integer greater than or equal to 1.

[0375] In one possible design, the communication unit 1003 is further used to: receive a fifth message, where the fifth message is used to request configuration of switching conditions for the N cells.

[0376] In one possible design, the second message includes: identification information corresponding to the first cell, and / or identification information of the switching condition of the first cell.

[0377] In one possible design, the first message is also used to instruct the terminal side device not to evaluate the switching condition of the first cell.

[0378] In one possible design, the second message includes first indication information, where the first indication information is used to indicate conditional switching; the second message also includes second indication information, where the second indication information is used to indicate evaluating the switching condition of the first cell in the case of the conditional switching.

[0379] In one possible design, the first message or the second message is also used to indicate that the condition of the first cell corresponds to a first TCI state.

[0380] In one possible design, the second message includes the TA information of the first cell; or, the method further includes: after the second message, sending the TA information of the first cell to the terminal side device; wherein, the TA information of the first cell is used to access the first cell in a random access-free manner.

[0381] In one possible design, the switching conditions of the first cell include K switching conditions, where K is an integer greater than or equal to 1; the K switching conditions include a first switching condition and a second switching condition; the type of the first switching condition is different from the type of the second switching condition; or, when the type of the first switching condition is the same as the type of the second switching condition, the threshold values ​​corresponding to the first switching condition and the second switching condition are different; or, the first switching condition is evaluated after receiving the first message, and the second switching condition is evaluated after receiving the second message.

[0382] It should be understood that the division of units in the above device is merely a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. Moreover, the units in the device can all be implemented in the form of software calling through processing elements; or they can all be implemented in the form of hardware; or some units can be implemented in the form of software calling through processing elements, and some units can be implemented in the form of hardware. For example, each unit can be a separately established processing element, or it can be integrated into a certain chip of the device. In addition, it can also be stored in the memory in the form of a program, called by a certain processing element of the device and execute the function of the unit. In addition, all or part of these units can be integrated together, or they can be implemented independently. The processing element described here can also be a processor, which can be an integrated circuit with signal processing capabilities. In the implementation process, each operation of the above method or each unit above can be implemented by the integrated logic circuit of the hardware in the processor element or in the form of software calling through the processing element.

[0383] In one example, the unit in any of the above devices may be one or more integrated circuits configured to implement the above method, such as one or more application specific integrated circuits (ASICs), one or more digital singnal processors (DSPs), one or more field programmable gate arrays (FPGAs), or a combination of at least two of these integrated circuit forms. For another example, when the unit in the device can be implemented in the form of a processing element scheduler, the processing element can be a processor, such as a general-purpose central processing unit (CPU), or other processor that can call a program. For another example, these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0384] The above-mentioned receiving unit is an interface circuit of the device, which is used to receive signals from other devices. For example, when the device is implemented as a chip, the receiving unit is the interface circuit of the chip used to receive signals from other chips or devices. The above-mentioned sending unit is an interface circuit of the device, which is used to send signals to other devices. For example, when the device is implemented as a chip, the sending unit is the interface circuit of the chip used to send signals to other chips or devices.

[0385] Referring to Figure 11, a structural diagram of a network-side device (such as a network device) provided in an embodiment of the present application, which can be applied to the communication system shown in Figure 1 to perform the functions of the network device in the above method embodiment. As shown in Figure 11, the network device 110 can be an access network node, and the network device 110 may include one or more DUs 1101 and one or more CUs 1102. The DU 1101 may include at least one antenna 11011, at least one radio frequency unit 11012, at least one processor 11013 and at least one memory 11014. The DU 1101 is mainly used for receiving and transmitting radio frequency signals, converting radio frequency signals into baseband signals, and partial baseband processing. CU1102 may include at least one processor 11022 and at least one memory 11021.

[0386] The CU 1102 is primarily used for baseband processing and controlling network devices. The DU 1101 and CU 1102 can be physically located together or separately, i.e., in a distributed base station. The CU 1102 is the control center of the network device, also known as a processing unit, and is primarily used to perform baseband processing. For example, the CU 1102 can be used to control the network device to execute the network device operation process described in the above method embodiments.

[0387] In addition, optionally, the network device 110 may include one or more radio frequency units, one or more DUs, and one or more CUs. The DU may include at least one processor 11013 and at least one memory 11014, the radio frequency unit may include at least one antenna 11011 and at least one radio frequency unit 11012, and the CU may include at least one processor 11022 and at least one memory 11021.

[0388] In one example, the CU1102 may be composed of one or more single boards, and the multiple single boards may jointly support a wireless access network with a single access indication (such as a 5G network), or may respectively support wireless access networks with different access standards (such as an LTE network, a 5G network, or other networks). The memory 11021 and the processor 11022 may serve one or more single boards. That is, a memory and a processor may be separately set on each single board. It is also possible that multiple single boards share the same memory and processor. In addition, necessary circuits may be provided on each single board. The DU1101 may be composed of one or more single boards, and the multiple single boards may jointly support a wireless access network with a single access indication (such as a 5G network), or may respectively support wireless access networks with different access standards (such as an LTE network, a 5G network, or other networks). The memory 11014 and the processor 11013 may serve one or more single boards. That is, a memory and a processor may be separately set on each single board. It is also possible that multiple single boards share the same memory and processor. In addition, necessary circuits may be provided on each single board.

[0389] The network device shown in Figure 11 is capable of implementing the various processes involved in the network device in the above-described method embodiments. The operations and / or functions of the various modules in the network device shown in Figure 11 are for implementing the corresponding processes in the above-described method embodiments. For details, please refer to the description in the above-described method embodiments; to avoid repetition, detailed descriptions are omitted here.

[0390] Refer to Figure 12, which is a structural diagram of a terminal-side device (such as a terminal) provided in an embodiment of the present application. The terminal can be applied to the communication system shown in Figure 1 to implement the operation of the terminal in the above embodiment. As shown in Figure 12, the terminal includes: an antenna 1210, a radio frequency part 1220, and a signal processing part 1230. The antenna 1210 is connected to the radio frequency part 1220. In the downlink direction, the radio frequency part 1220 receives information sent by the network device through the antenna 1210, and sends the information sent by the network device to the signal processing part 1230 for processing. In the uplink direction, the signal processing part 1230 processes the information of the terminal and sends it to the radio frequency part 1220. The radio frequency part 1220 processes the information of the terminal and sends it to the network device through the antenna 1210.

[0391] The signal processing unit 1230 may include a modem subsystem for processing data at various communication protocol layers; a central processing unit for processing the terminal operating system and application layers; and other subsystems, such as a multimedia subsystem for controlling the terminal's camera and screen display, and a peripheral subsystem for connecting to other devices. The modem subsystem may be a separate chip.

[0392] The modem subsystem may include one or more processing elements 1231, such as a main control CPU and other integrated circuits. Furthermore, the modem subsystem may include a storage element 1232 and an interface circuit 1233. Storage element 1232 is used to store data and programs. However, the program used to execute the method executed by the terminal in the above method may not be stored in storage element 1232 but rather in a memory external to the modem subsystem, and loaded by the modem subsystem when in use. Interface circuit 1233 is used to communicate with other subsystems.

[0393] The modem subsystem can be implemented using a chip comprising at least one processing element and an interface circuit. The processing element is configured to execute each step of any of the methods performed by the terminal, and the interface circuit is configured to communicate with other devices. In one implementation, the unit that performs each step of the method can be implemented as a processing element scheduler. For example, the terminal device includes a processing element and a storage element, and the processing element invokes a program stored in the storage element to execute the method performed by the terminal in the above method embodiments. The storage element can be a storage element located on the same chip as the processing element, i.e., an on-chip storage element.

[0394] In another implementation, the program for executing the method executed by the terminal in the above method can be stored in a memory element on a different chip from the processing element, i.e., an off-chip memory element. In this case, the processing element calls or loads the program from the off-chip memory element to the on-chip memory element to call and execute the method executed by the terminal in the above method embodiment.

[0395] In another implementation, the unit implementing each step of the above method in the terminal may be configured as one or more processing elements, which are provided in the modem subsystem. The processing elements may be integrated circuits, such as one or more ASICs, one or more DSPs, one or more FPGAs, or a combination of these integrated circuits. These integrated circuits may be integrated together to form a chip.

[0396] The units that implement the various steps of the above method in the terminal can be integrated together and implemented in the form of a SOC chip, which is used to implement the above method. The chip can integrate at least one processing element and a storage element, and the processing element can call the program stored in the storage element to implement the above terminal execution method; alternatively, the chip can integrate at least one integrated circuit to implement the above terminal execution method; or, a combination of the above implementation methods can be used, with the functions of some units implemented by the processing element calling the program, and the functions of some units implemented by the integrated circuit.

[0397] As can be seen, the above-mentioned terminal device may include at least one processing element and an interface circuit, wherein the at least one processing element is used to execute any of the terminal-executed methods provided in the above method embodiments. The processing element may execute some or all of the steps executed by the terminal in a first manner: by calling a program stored in a storage element; or in a second manner: by combining hardware integrated logic circuits in the processor element with instructions to execute some or all of the steps executed by the terminal. Of course, the first and second manners may also be combined to execute some or all of the steps executed by the terminal.

[0398] The processing element here is the same as described above and can be implemented by a processor. The function of the processing element can be the same as that of the processing unit described in Figure 10. For example, the processing element can be a general-purpose processor, such as a CPU, or one or more integrated circuits configured to implement the above method, such as one or more ASICs, or one or more microprocessors DSPs, or one or more FPGAs, or a combination of at least two of these integrated circuit forms. The storage element can be implemented by a memory, and the function of the storage element can be the same as that of the storage unit described in Figure 10. The storage element can be a single memory or a collective term for multiple memories.

[0399] The terminal shown in FIG12 is capable of implementing the various processes involved in the terminal in the above-described method embodiment. The operations and / or functions of the various modules in the terminal shown in FIG12 are respectively for implementing the corresponding processes in the above-described method embodiment. For details, please refer to the description of the above-described method embodiment. To avoid repetition, detailed description is omitted here.

[0400] The terms "system" and "network" in the embodiments of the present application can be used interchangeably. "At least one" refers to one or more, and "plurality" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of A, B or C" includes A, B, C, AB, AC, BC or ABC, and "at least one of A, B and C" can also be understood to include A, B, C, AB, AC, BC or ABC. And, unless otherwise specified, the ordinal numbers such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects and are not used to limit the order, timing, priority or importance of multiple objects.

[0401] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, optical storage, etc.) that contain computer-usable program code.

[0402] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each flow and / or box in the flow chart and / or block diagram, as well as the combination of the flow chart and / or box in the flow chart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more flow charts and / or one or more boxes in the block diagram.

[0403] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0404] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

Claims

1. A communication method, characterized in that: The method comprises: receiving a first message from a network-side device, where the first message is used to configure M switching conditions; receiving a second message from the network-side device, the second message being used to instruct evaluation of a handover condition of the first cell; wherein the M handover conditions include the handover condition of the first cell, and M is an integer greater than or equal to 1; In response to the second message, a handover condition of the first cell is evaluated.

2. The method according to claim 1, characterized in that The second message includes: Identification information corresponding to the first cell, and / or identification information of a switching condition of the first cell.

3. The method according to claim 1 or 2, characterized in that The M switching conditions correspond to N cells, where the N cells include the first cell, N is less than or equal to M, and N is an integer greater than or equal to 1.

4. The method according to any one of claims 1 to 3, characterized in that The first message is further used to indicate that a handover condition of the first cell is not to be evaluated.

5. The method according to any one of claims 1 to 4, characterized in that The method further comprises: In response to the evaluation of the handover condition of the first cell, handover is performed to the first cell.

6. The method according to claim 5, characterized in that In response to the evaluation of the handover condition of the first cell, handing over to the first cell includes: If the evaluation result determines that the handover condition of the first cell is satisfied, handover is performed to the first cell.

7. The method according to claim 6, characterized in that The handover condition of the first cell includes K handover conditions, where K is an integer greater than or equal to 1; The handover condition of the first cell is met, including: one handover condition of K handover conditions of the first cell is met.

8. The method according to claim 7, characterized in that The K switching conditions include a first switching condition and a second switching condition; The type of the first switching condition is different from the type of the second switching condition; or, When the type of the first switching condition is the same as the type of the second switching condition, the threshold values corresponding to the first switching condition and the second switching condition are different; or, The first switching condition is evaluated after the first message is received, and the second switching condition is evaluated after the second message is received.

9. The method according to any one of claims 6 to 8, characterized in that The handover condition of the first cell is met, including at least one of the following: The signal quality of the source cell is less than or equal to the first threshold; The signal quality of the first cell is greater than or equal to a second threshold; A difference between the signal quality of the first cell and the signal quality of the source cell is greater than or equal to a third threshold.

10. The method according to any one of claims 5 to 9, characterized in that The handover condition of the first cell corresponds to a first transmission configuration indication TCI state; Switching to the first cell includes: accessing the first cell based on the first TCI state corresponding to the switching condition of the first cell.

11. The method according to any one of claims 5 to 10, characterized in that Switching to the first cell includes: accessing the first cell in a random access-free manner.

12. The method according to claim 11, characterized in that The second message includes timing advance (TA) information of the first cell; Alternatively, the method further includes: receiving TA information of the first cell after the second message; The TA information of the first cell is used to access the first cell in a random access-free manner.

13. The method according to any one of claims 5 to 12, characterized in that After switching to the first cell, the method further includes: Cancel the conditional handover that meets the handover conditions of other cells.

14. A communication method, characterized in that: The method comprises: Sending a first message to the terminal side device, where the first message is used to configure M switching conditions; A second message is sent to the terminal side device, where the second message is used to instruct the terminal side device to evaluate the switching condition of the first cell; wherein the M switching conditions include the switching condition of the first cell, and M is an integer greater than or equal to 1.

15. The method according to claim 14, characterized in that The method further comprises: A third message is sent, where the third message is used to indicate that the terminal side device has been instructed to evaluate a switching condition of the first cell.

16. The method according to claim 15, characterized in that The method further comprises: A fourth message is sent, where the fourth message is used to indicate that the TA information of the first cell has been sent to the terminal side device.

17. The method according to claim 15 or 16, characterized in that The third message is also used to indicate the probability of the terminal side device switching to the first cell.

18. The method according to any one of claims 14 to 17, characterized in that The M switching conditions correspond to N cells, where the N cells include the first cell, N is less than or equal to M, and N is an integer greater than or equal to 1.

19. The method according to claim 18, characterized in that The method further comprises: A fifth message is received, where the fifth message is used to request configuration of switching conditions for the N cells.

20. The method according to any one of claims 14 to 19, characterized in that The second message includes: Identification information corresponding to the first cell, and / or identification information of a switching condition of the first cell.

21. The method according to any one of claims 14 to 20, characterized in that The first message is also used to instruct the terminal side device not to evaluate the switching condition of the first cell.

22. The method according to any one of claims 14 to 21, characterized in that The first message or the second message is further used to indicate that the condition of the first cell corresponds to a first TCI state.

23. The method according to any one of claims 14 to 22, characterized in that The second message includes the TA information of the first cell; or the method further includes: sending the TA information of the first cell to the terminal side device after the second message; The TA information of the first cell is used by the terminal side device to access the first cell in a random access-free manner.

24. The method according to any one of claims 14 to 23, characterized in that The handover condition of the first cell includes K handover conditions, where K is an integer greater than or equal to 1; the K handover conditions include a first handover condition and a second handover condition; The type of the first switching condition is different from the type of the second switching condition; or, When the type of the first switching condition is the same as the type of the second switching condition, the threshold values corresponding to the first switching condition and the second switching condition are different; or, The first switching condition is evaluated after the first message is received, and the second switching condition is evaluated after the second message is received.

25. A communication device, characterized in that: The method comprises a module for executing the method according to any one of claims 1 to 13, or a module for executing the method according to any one of claims 14 to 24.

26. A communication device, characterized in that: The communication device comprises a processor coupled to a memory, wherein a computer program is stored in the memory; the processor is used to call the computer program in the memory so that the communication device executes the method according to any one of claims 1 to 13, or the method according to any one of claims 14 to 24.

27. A communication system, characterized in that: The communication system includes a network side device and a terminal side device; wherein the terminal side device is used to execute the method described in any one of claims 1 to 13, and the network side device is used to execute the method described in any one of claims 14 to 24.

28. A computer-readable storage medium, characterized in that The storage medium stores a computer program or instruction. When the computer program or instruction is executed by a computer, the method according to any one of claims 1 to 13 or the method according to any one of claims 14 to 24 is implemented.

29. A computer program product, characterized in that When a computer reads and executes the computer program product, the computer is caused to execute the method according to any one of claims 1 to 13 or the method according to any one of claims 14 to 24.

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