Communication method and apparatus

Abstract

The present application relates to the technical field of communications. Disclosed are a communication method and an apparatus. The method comprises: a UE sends a Layer 1 measurement result to a source DU; on the basis of the Layer 1 measurement result, the source DU sends, to a CU, indication information indicating that the UE is to be handed over to one or more candidate cells; the UE sends a Layer 3 measurement result to the CU; on the basis of the Layer 3 measurement result, the CU sends, to the source DU and one or more candidate DUs, indication information indicating that the UE is to be handed over to the one or more candidate cells; and when a target cell does not belong to a first candidate DU, receiving, from the CU, indication information indicating that the UE has been handed over to a cell corresponding to a target DU. By means of the solution of the present application, the source DU and the candidate DUs can learn a handover state in a timely manner, and the UE and the target DU can complete beam alignment and uplink data can be successfully transmitted, thereby effectively avoiding failures of UEs during CLTM handover processes.

Description

Communication methods and devices

[0001] This application claims priority to Chinese Patent Application No. 202510134687.6, filed on February 6, 2025, entitled "Communication Method and Apparatus", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0003] In the conditional L1 / L2 triggered mobility (CLTM) handover technology, the source distributed unit (DU) configures CLTM handover conditions for the user equipment (UE). The UE then autonomously selects a target distributed unit (DU) to connect to based on these conditions and sends an uplink notification message to the source DU.

[0004] However, when the UE is about to hand over to the target DU, the UE is located at the edge of the source cell, and the connection quality with the source DU may be poor. The source DU may not be able to receive the uplink notification message sent by the UE, which will cause the CLTM handover to fail.

[0005] Therefore, how to enable the UE to successfully complete the CLTM handover process is an urgent problem to be solved. Summary of the Invention

[0006] This application provides a communication method and apparatus to enable the UE to successfully complete the CLTM handover process.

[0007] Firstly, a communication method is provided that can be applied to a centralized device, which can be a CU or a communication module within the CU, or a circuit or chip applied to the CU (such as a modem chip (also known as a baseband chip), or a system-on-chip (SoC) chip or system-in-package (SIP) chip containing a modem core). Taking the application of this method to a CU as an example...

[0008] In this method, the CU receives first information from the terminal, the first information being used to indicate layer 3 measurement results; based on the layer 3 measurement results, sends second information to the source DU, the second information being used to indicate that the terminal will switch to one or more candidate cells, the one or more candidate cells corresponding to one or more candidate DUs; and sends third information to the one or more candidate DUs, the third information being used to indicate that the terminal will switch to the one or more candidate cells.

[0009] Using this method, after determining the candidate cell, the CU notifies the UE that it will hand over to the candidate cell by notifying the source DU and candidate DU, and instructs other candidate DUs (excluding the target DU) that the UE has handed over to the cell corresponding to the target DU. This allows the source DU and candidate DU to know the handover status in a timely manner, enabling the UE and the target DU to complete beam alignment and successfully send uplink data, thereby effectively avoiding UE failure during the CLTM handover process.

[0010] In one possible implementation, the one or more candidate cells are obtained based on the Layer 3 measurement results.

[0011] In another possible implementation, the third information is used to instruct the terminal to switch to the first candidate cell, and the third information includes multiple TCI state IDs corresponding to the first candidate cell.

[0012] In this approach, the CU can select one or more candidate beams based on the layer 3 measurement results. These candidate beams belong to the first candidate cell (one candidate beam corresponds to one TCI state ID), and the CU can indicate the multiple TCI state IDs corresponding to the first candidate cell to the candidate DU corresponding to the first candidate cell.

[0013] In another possible implementation, the third information is used to instruct the terminal to switch to the first candidate cell and the second candidate cell. The third information includes the identifier of the TCI state corresponding to the first candidate cell and the TCI state ID corresponding to the second candidate cell.

[0014] For example, the CU can filter out one or more candidate beams based on the layer 3 measurement results. These candidate beams belong to a first candidate cell and a second candidate cell, respectively (one candidate beam corresponds to one TCI state ID). The CU indicates the TCI state ID of the first candidate cell to the candidate DU corresponding to the first candidate cell and indicates the TCI state ID of the second candidate cell to the candidate DU corresponding to the second candidate cell. For example, the candidate DU corresponding to the first candidate cell and the candidate DU corresponding to the second candidate cell can be the same DU or different DUs.

[0015] In another possible implementation, the method further includes: receiving fourth information from a target DU, the fourth information indicating that the terminal has accessed the cell corresponding to the target DU, the cell corresponding to the target DU belonging to one or more candidate cells.

[0016] Using this method, once the terminal has accessed the cell corresponding to the target DU, the target DU will promptly notify the CU that the terminal has accessed the target DU.

[0017] In another possible implementation, the method further includes sending fifth information to other candidate DUs besides the target DU, the fifth information being used to indicate that the terminal has switched to the cell corresponding to the target DU.

[0018] Using this method, when the CU determines that the terminal has been connected to the target DU, it notifies other candidate DUs besides the target DU that the terminal has been connected to the target DU, so that the other candidate DUs stop sending downlink control information to the terminal.

[0019] In yet another possible implementation, the terminal will perform a CLTM switch.

[0020] Secondly, a communication method is provided that can be applied to a source distributed device, which can be a source DU or a communication module in the source DU, or a circuit or chip applied to the source DU (such as a modem chip, or a SoC chip or SIP chip containing a modem core). Taking the application of this method to a source DU as an example.

[0021] In this method, the source DU receives sixth information from the terminal, the sixth information being used to indicate the layer 1 measurement result; and sends seventh information to the CU based on the layer 1 measurement result, the seventh information being used to indicate that the terminal will switch to one or more candidate cells, the one or more candidate cells corresponding to one or more candidate DUs.

[0022] In one possible implementation, the one or more candidate cells are obtained based on the Layer 1 measurement results.

[0023] In another possible implementation, the seventh information is used to instruct the terminal to switch to the first candidate cell, and the seventh information includes multiple TCI state IDs corresponding to the first candidate cell.

[0024] In another possible implementation, the seventh information is used to instruct the terminal to switch to the first candidate cell and the second candidate cell, and the seventh information includes the TCI state ID corresponding to the first candidate cell and the TCI state ID corresponding to the second candidate cell.

[0025] In yet another possible implementation, the terminal will perform a CLTM switch.

[0026] For information on the beneficial effects of the second aspect or any design thereof, please refer to the relevant description in the first aspect.

[0027] Thirdly, a communication method is provided, which can be applied to a first candidate distributed device, which may be a first candidate DU or a communication module in the first candidate DU, or a circuit or chip (such as a modem chip, or a SoC chip or SIP chip containing a modem core) applied to the first candidate DU. Taking the application of this method to a first candidate DU as an example.

[0028] In this method, a first candidate DU receives third information from a CU, the third information being used to indicate that the terminal will switch to one or more candidate cells; if the target cell belongs to the first candidate DU, an eighth information is sent to the terminal, the eighth information being used to indicate uplink resources; if the target cell does not belong to the first candidate DU, a fifth information is received from the CU, the fifth information being used to indicate that the terminal has switched to the cell corresponding to the target DU.

[0029] For example, the first candidate DU sends the eighth information to the UE in the beam direction indicated by the CU. If the UE enters the coverage area of ​​the first candidate DU, detects the physical downlink control channel (PDCCH), and receives the eighth information sent by the first candidate DU, then the target cell belongs to the first candidate DU. If the UE does not enter the coverage area of ​​the first candidate DU and does not receive the eighth information sent by the first candidate DU, then the target cell does not belong to the first candidate DU.

[0030] In one possible implementation, the third information includes multiple TCI state IDs corresponding to the first candidate cell.

[0031] In yet another possible implementation, the terminal will perform a CLTM switch.

[0032] For information on the beneficial effects of the third aspect or any of its designs, please refer to the relevant descriptions in the first aspect.

[0033] Fourthly, a communication method is provided that can be applied to a centralized device, which can be a CU or a communication module in the CU, or a circuit or chip applied to the CU (such as a modem chip, or a SoC chip or SIP chip containing a modem core). Taking the application of this method to a CU as an example.

[0034] In this method, the CU sends CLTM configuration information, which includes the identifiers of one or more third candidate cells and / or the identifiers of the Transmission Configuration Indicator (TCI) status corresponding to the one or more third candidate cells; and sends first information to the terminal, which includes the identifiers of one or more fourth candidate cells and / or the identifiers of the Transmission Configuration Indicator (TCI) status corresponding to the one or more fourth candidate cells, wherein the one or more fourth candidate cells correspond to one or more candidate distributed units (DUs), and the one or more fourth candidate cells belong to the one or more third candidate cells.

[0035] Using this method, the CU determines one or more fourth candidate cells and indicates them to the UE. The UE measures and evaluates whether any beam in the one or more fourth candidate cells meets the CLTM handover conditions. If a beam in the one or more fourth candidate cells meets the CLTM handover conditions, the UE hands over to a beam in the one or more fourth candidate cells; otherwise, a random access procedure is executed to hand over to a beam in one or more third candidate cells configured in the CLTM configuration information. This enables the UE and the target DU to achieve beam alignment and successfully transmit uplink data, effectively avoiding UE failure during the CLTM handover process.

[0036] In one possible implementation, the first information is used to indicate that the priority of the one or more fourth candidate cells is higher than the priority of other candidate cells in the one or more third candidate cells besides the one or more fourth candidate cells.

[0037] In yet another possible implementation, the terminal will perform a CLTM switch.

[0038] In another possible implementation, the method further includes: receiving second information from the terminal, the second information indicating layer 3 measurement results; wherein the one or more fourth candidate cells are determined based on the layer 3 measurement results.

[0039] In yet another possible implementation, the method further includes: sending third information to the source DU, the third information being used to instruct the terminal to switch to the one or more fourth candidate cells.

[0040] In yet another possible implementation, the method further includes sending fourth information to the one or more candidate DUs, the fourth information being used to instruct the terminal to switch to the one or more fourth candidate cells.

[0041] In another possible implementation, the method further includes: receiving fifth information from a target DU, the fifth information indicating that the terminal has accessed a target cell, the target cell belonging to one or more third candidate cells.

[0042] Fifthly, a communication method is provided, which can be applied to a terminal device, which may be a terminal or a communication module in a terminal, or a circuit or chip applied to the terminal (such as a modem chip, or a SoC chip or SIP chip containing a modem core). Taking the application of this method to a terminal as an example.

[0043] In this method, the terminal receives CLTM configuration information, which includes the identifiers of one or more third candidate cells and / or the identifiers of the Transmission Configuration Indicator (TCI) status corresponding to the one or more third candidate cells; receives first information from a Centralized Unit (CU) and / or a Source Distributed Unit (DU), which includes the identifiers of one or more fourth candidate cells and / or the identifiers of the Transmission Configuration Indicator (TCI) status corresponding to the one or more fourth candidate cells, wherein the one or more fourth candidate cells correspond to one or more candidate distributed units (DUs) and belong to the one or more third candidate cells; determines that one of the one or more fourth candidate cells meets the CLTM handover conditions; and hands over to a target cell, which is a fourth candidate cell that meets the CLTM handover conditions.

[0044] In one possible implementation, determining that one of the one or more fourth candidate cells meets the CLTM handover condition includes: determining a candidate cell that meets the CLTM handover condition; and determining that the candidate cell that meets the CLTM handover condition includes the one or more fourth candidate cells.

[0045] In another possible implementation, the first information is used to indicate that the priority of the one or more fourth candidate cells is higher than the priority of the one or more third candidate cells other than the one or more fourth candidate cells.

[0046] For the beneficial effects of the fifth aspect or any design of the fifth aspect, please refer to the relevant description in the fourth aspect.

[0047] Sixthly, a communication method is provided, which can be applied to a terminal device, which may be a terminal or a communication module in a terminal, or a circuit or chip applied to the terminal (such as a modem chip, or a SoC chip or SIP chip containing a modem core). Taking the application of this method to a terminal as an example.

[0048] In this method, the terminal sends an uplink message on an authorized resource associated with an identifier of a first Transmission Configuration Indicator (TCI) state, the identifier of the first TCI state corresponding to an uplink beam; and sends first information to a network device, the first information including an identifier of a second TCI state, the identifier of the second TCI state corresponding to a downlink beam.

[0049] Using this method, in the Separate TCI state scenario, the UE can only complete uplink beam alignment by sending the first uplink message after completing LTM handover. The UE can send information carrying the DL TCI state ID to the target DU / CU to further achieve downlink beam alignment.

[0050] In a seventh aspect, a communication device is provided. The communication device can perform the methods described in the first to sixth aspects or any one of the designs described in the first to sixth aspects. The communication device can be a terminal device or a network device (e.g., a CU, a source DU, a first candidate DU), or it can be a module (e.g., a chip) applied in a terminal device or a module (e.g., a chip) applied in a network device.

[0051] In one possible design, the communication device includes a transceiver unit and a processing unit. The transceiver unit performs the receiving and / or transmitting operations in the methods of the first to sixth aspects or any one of the designs described above; the processing unit performs the processing operations in the methods of the first to sixth aspects or any one of the designs described above.

[0052] In another possible design, the communication device includes a processor coupled to a memory; the processor is configured to support the device in performing the corresponding functions in the channel state information reporting method described above. The memory, coupled to the processor, stores the necessary computer programs (or computer-executable instructions) and / or data of the device. Optionally, the communication device may further include a communication interface for supporting communication between the device and other network elements, such as the transmission or reception of data and / or signals. Exemplarily, the communication interface may be a transceiver, circuit, bus, module, or other type of communication interface. Optionally, the memory may be located internally within the communication device and integrated with the processor; alternatively, it may be located externally to the communication device.

[0053] In another possible design, the communication device includes a processor and a transceiver, the processor being coupled to the transceiver. The processor executes computer programs or instructions to control the transceiver to receive and send information. When the processor executes the computer programs or instructions, it is also used to design the above-mentioned method through logic circuits or execution code instructions. The transceiver can be a transceiver circuit, a transceiver module, or an input / output interface, used to receive signals from other communication devices besides the communication device and transmit them to the processor, or to send signals from the processor to other communication devices besides the communication device. When the communication device is a chip, the transceiver is a transceiver circuit or an input / output interface.

[0054] When the communication device is a chip, the transmitting unit can be an output unit, such as an output circuit or a communication interface; the receiving unit can be an input unit, such as an input circuit or a communication interface. When the communication device is a terminal device, the transmitting unit can be a transmitter or a receiver; the receiving unit can be a receiver or a receiver.

[0055] Eighthly, a computer-readable storage medium is provided that stores a computer program or instructions thereon, which, when executed by a communication device, implement the method as described in the first aspect or any design of the first aspect, or implement the method as described in the second aspect or any design of the second aspect, or implement the method as described in the third aspect or any design of the third aspect, or implement the method as described in the fourth aspect or any design of the fourth aspect, or implement the method as described in the fifth aspect or any design of the fifth aspect, or implement the method as described in the sixth aspect or any design of the sixth aspect.

[0056] Ninthly, a computer program product is provided that, when executed on a communication device, implements the method as described in the first aspect or any design of the first aspect, or implements the method as described in the second aspect or any design of the second aspect, or implements the method as described in the third aspect or any design of the third aspect, or implements the method as described in the fourth aspect or any design of the fourth aspect, or implements the method as described in the fifth aspect or any design of the fifth aspect, or implements the method as described in the sixth aspect or any design of the sixth aspect. Attached Figure Description

[0057] Figure 1 is a schematic diagram of the architecture of the communication system 1000 used in the embodiments of this application;

[0058] Figure 2 is a schematic diagram of the gNB structure;

[0059] Figure 3 is a schematic diagram of the measurement reporting process for Layer 1 / Layer 3;

[0060] Figure 4 is a schematic diagram of UE movement;

[0061] Figure 5 is a schematic diagram of the DG-based RACH-less handover process in traditional LTM technology;

[0062] Figure 6 is a schematic diagram of a possible DG-based RACH-less handover process in existing CLTM technology;

[0063] Figure 7 is a schematic diagram of a CLTM switching scenario according to an embodiment of this application;

[0064] Figures 8-11 are schematic flowcharts of the communication method provided in the embodiments of this application;

[0065] Figures 12 and 13 are schematic diagrams of the structure of the communication device provided in the embodiments of this application. Detailed Implementation

[0066] The scheme of this application will be further described below with reference to the accompanying drawings.

[0067] Figure 1 is a schematic diagram of the architecture of a communication system 1000 provided in an embodiment of this application. As shown in Figure 1, the communication system 1000 includes a radio access network (RAN) 100, wherein the RAN 100 includes at least one RAN node (110a and 110b in Figure 1, collectively referred to as 110), and may also include at least one terminal (120a-120j in Figure 1, collectively referred to as 120). The RAN 100 may also include other RAN nodes, such as wireless relay devices and / or wireless backhaul devices (not shown in Figure 1). The terminal 120 is wirelessly connected to the RAN node 110. Terminals and RAN nodes can be interconnected via wired or wireless means. The communication system 1000 may also include a core network 200. The RAN node 110 is connected to the core network 200 via wireless or wired means. The core network equipment in core network 200 and the RAN node 110 in RAN 100 can be independent and different physical devices, or they can be the same physical device that integrates the logical functions of the core network equipment and the logical functions of the RAN node. Communication system 1000 may also include Internet 300.

[0068] RAN100 can be an evolved universal terrestrial radio access (E-UTRA) system, a new radio (NR) system, or a future radio access system as defined in the 3rd generation partnership project (3GPP), or it can be a WiFi system. RAN100 can also include two or more of the above-mentioned different radio access systems. RAN100 can also be an open RAN (O-RAN).

[0069] RAN nodes, also known as radio access network devices, RAN entities, or access nodes, are used to help terminals access communication systems wirelessly. In one application scenario, an RAN node can be a base station, an evolved NodeB (eNodeB), a TRP, a next-generation NodeB (gNB) in a 5G mobile communication system, a base station in a future mobile communication system, or an access node in a WiFi system. RAN nodes can be macro base stations (as shown in Figure 1, 110a), micro base stations or indoor stations (as shown in Figure 1, 110b), relay nodes, or donor nodes.

[0070] In another application scenario, multiple RAN nodes can collaborate to help terminals achieve wireless access, with different RAN nodes implementing different functions of the base station. For example, a RAN node can be a central unit (CU), a distributed unit (DU), or a radio unit (RU). Here, the CU performs the functions of the base station's Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP), and can also perform the functions of the Service Data Adaptation Protocol (SDAP). The DU performs the functions of the base station's Radio Link Control (RANC) and Medium Access Control (MAC) layers, and can also perform some or all of the physical layer functions. For specific descriptions of these protocol layers, refer to the relevant 3GPP technical specifications. The RU can be used to implement radio frequency signal transmission and reception. The CU and DU can be two independent RAN nodes or integrated into the same RAN node, such as within a baseband unit (BBU). The RU can be included in radio frequency equipment, such as in a remote radio unit (RRU) or an active antenna unit (AAU). The CU can be further divided into two types of RAN nodes: CU-control plane and CU-user plane.

[0071] In different systems, RAN nodes may have different names. For example, in an O-RAN system, a CU can be called an open CU (O-CU), a DU can be called an open DU (O-DU), and an RU can be called an open RU (O-RU). The RAN nodes in the embodiments of this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules. For example, a RAN node can be a server loaded with the corresponding software modules. The embodiments of this application do not limit the specific technology or device form used in the RAN nodes. For ease of description, a base station is used as an example of a RAN node in the following description.

[0072] A terminal is a device with wireless transceiver capabilities, capable of sending signals to or receiving signals from a base station. Terminals can also be called terminal equipment, user equipment (UE), mobile station, mobile terminal, etc. Terminals can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, smart cities, etc. Terminals can be mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, airplanes, ships, robots, robotic arms, smart home devices, etc. The embodiments of this application do not limit the specific technology or device form used in the terminal.

[0073] Base stations and terminals can be fixed or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can be deployed on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of the base stations and terminals.

[0074] The roles of base stations and terminals can be relative. For example, the helicopter or drone 120i in Figure 1 can be configured as a mobile base station. For terminals 120j that access the wireless access network 100 through 120i, terminal 120i is a base station; however, for base station 110a, 120i is a terminal, meaning that 110a and 120i communicate via a wireless air interface protocol. Of course, 110a and 120i can also communicate via a base station-to-base station interface protocol. In this case, relative to 110a, 120i is also a base station. Therefore, both base stations and terminals can be collectively referred to as communication devices. 110a and 110b in Figure 1 can be called communication devices with base station functions, and 120a-120j in Figure 1 can be called communication devices with terminal functions.

[0075] Communication between base stations and terminals, between base stations, and between terminals can be conducted using licensed spectrum, unlicensed spectrum, or both simultaneously. Communication can be conducted using spectrum below 6 GHz, spectrum above 6 GHz, or both simultaneously. The embodiments of this application do not limit the spectrum resources used for wireless communication.

[0076] In the embodiments of this application, the functions of the base station can be executed by modules (such as chips) within the base station, or by a control subsystem that includes base station functions. This control subsystem, including base station functions, can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. Similarly, the functions of the terminal can be executed by modules (such as chips or modems) within the terminal, or by a device that includes terminal functions.

[0077] In this application, the base station sends downlink signals or downlink information to the terminal, with the downlink information carried on the downlink channel; the terminal sends uplink signals or uplink information to the base station, with the uplink information carried on the uplink channel. To communicate with the base station, the terminal needs to establish a radio connection on a cell controlled by the base station. The cell with which the terminal has established a radio connection is called the terminal's serving cell. When the terminal communicates with this serving cell, it is also susceptible to interference from signals from neighboring cells.

[0078] In the 5G system, base stations are called gNB / ng-eNB, and will be referred to as gNB from now on. gNBs are connected to each other through the Xn interface.

[0079] Figure 2 shows a schematic diagram of the gNB structure. The gNB can be composed of a centralized unit (CU) and a distributed unit (DU). That is, the functions of the base station are split, some functions of the base station are deployed in a CU, and the remaining functions are deployed in a DU. Multiple DUs share a CU.

[0080] The separation of CU and DU can be based on the protocol stack. One possible approach is to deploy the Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) layers on the CU, and the remaining layers—Radio Link Control (RLC), Media Access Control (MAC), and Physical Layer (PHY)—on the DU. The CU and DU are connected via the F1 interface. A CU representing a gNB connects to the core network via the NG interface, while a CU representing a gNB connects to other gNBs via the Xn interface.

[0081] In Figure 2, 5GC stands for 5G core network, and NG-RAN stands for next-generation radio access network.

[0082] In the existing CLTM process, measurement reports can be triggered at layer 1 (L1) (i.e., the physical layer) and layer 3 (L3) (i.e., the RRC layer). Figure 3 shows a schematic diagram of the measurement reporting process for layer 1 / layer 3. The measurement reporting steps for layer 1 / layer 3 are as follows:

[0083] Step 1: The base station configures the reference signal resource set (RS Resource set) (also known as the candidate cell beam resource set) for the UE through RRC layer messages.

[0084] Step 2: The UE measures (or all) of the candidate beams in the candidate cell reference signal resource set.

[0085] Step 3: Based on the measurement results of the candidate beams, the UE generates a measurement report (MR), which is carried in uplink control information (UCI) or a media access control element (MAC CE) and sent to the base station. The measurement report includes, but is not limited to, beam quality parameters such as reference signal received power (RSRP), reference signal received quality (RSRQ), and signal-to-interference-plus-noise ratio (SINR).

[0086] CLTM switching conditions:

[0087] (1)CondEventA3: The neighboring cell has a better beam than the current serving cell.

[0088] (2) CondEventA5: The serving cell has a beam ratio worse than threshold 1, and the neighboring cell has a beam ratio better than threshold 2.

[0089] (3) CondEventLTM3: The candidate cell has a better beam than the serving cell.

[0090] (4) CondEventLTM5: The serving cell’s beam is worse than absolute threshold 1, and the candidate cell’s beam is better than absolute threshold 2.

[0091] Figure 4 illustrates UE movement. Mobility management is a crucial component of wireless mobile communication, determining the smooth handover and stable connection of the UE between different cells and beams. In idle and deactivated states, mobility management primarily involves cell selection / reselection; in connected states, it mainly refers to handover (HO). Both cell selection / reselection and handover are based on beam measurements taken by the user equipment and reported to the base station at the cell level or beam level. These operations are essential for ensuring communication continuity and efficient utilization of network resources.

[0092] In mobility management, Layer 1 / L2 triggered mobility (LTM) is a technology used for cell handover. L1 refers to the physical layer (PHY); L2 refers to the medium access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and service data adaptation protocol (SDAP) layers. However, during L1 / L2 handover, L2 primarily refers to the MAC layer. LTM means that handover-related operations are mainly performed at the physical and MAC layers.

[0093] In traditional LTM technology, a key step in the handover process is establishing a connection between the UE and the target gNB, i.e., the LTM cell switch. This process is divided into a random access procedure (RACH procedure) and a RACH-less procedure. The RACH-less procedure is generally preferred in LTM handover because it offers lower mobility latency. The RACH-less procedure is further divided into two types: configuration grant-based RACH-less procedure and dynamic grant-based RACH-less procedure. The main difference lies in the method used: during the connection establishment process, the UE obtains an uplink grant (UL grant), i.e., uplink resources, through either a configured grant (CG) or a dynamic grant (DG) method, thereby successfully transmitting the first uplink data and completing the LTM handover to the target gNB.

[0094] In CLTM handover technology, the source gNB configures CLTM handover conditions for the UE, and the UE autonomously selects a target base station for connection based on these conditions. CLTM technology is also divided into CG-based RACH-less handover procedures and DG-based RACH-less handover procedures. The embodiments of this application mainly focus on the application scenarios of the DG-based RACH-less handover procedure.

[0095] Traditional LTM technology's DG-based RACH-less handover process:

[0096] Figure 5 illustrates the DG-based RACH-less handover process in traditional LTM technology. The following steps describe the process of a UE handing over from a source DU to a target DU, using an intra-CU LTM cell switch scenario (i.e., UE handover within the same CU).

[0097] S501. The UE sends an L1 measurement report to the source DU.

[0098] S502. The source DU sends a handover indication message to the UE, namely the MAC layer control element for LTM handover (LTM cell switch MAC CE). This handover indication message includes, but is not limited to, the target cell identifier and the transmission configuration indication state ID (TCI state ID).

[0099] S503. The source DU sends a handover indication message to the CU via the F1 interface, notifying the CU that the UE is about to hand over to the target DU. This handover indication message includes, but is not limited to, the target cell ID and TCI status ID.

[0100] S504.CU sends a handover indication message to the target DU via the F1 interface, notifying the target DU that the UE is about to hand over to the target DU. This handover indication message includes, but is not limited to, the target cell ID and TCI status ID.

[0101] S505. After receiving the indication message from the CU, the target DU sends a downlink control information (DCI) message according to the beam direction indicated by the CU, providing uplink grant (UL grant), i.e., uplink resources. When the UE enters the coverage area of ​​the target DU, it detects the physical downlink control channel (PDCCH) and receives the DCI message sent by the target DU, thus successfully sending the first uplink data. At this point, the UE successfully accesses the target DU.

[0102] S506. After completing the above steps, the UE successfully completes the LTM handover process.

[0103] One possible DG-based RACH-less handover process in existing CLTM technology:

[0104] The following steps describe the process of a UE handing over from a source DU to a target DU, using an intra-CU LTM cell switch scenario (i.e., UE handover within the same CU LTM cell). This process is similar to the DG-based RACH-less handover procedure in traditional LTM technology, with the main difference being in step S502.

[0105] In CLTM technology, when a UE leaves its source DU, it autonomously selects a target DU based on the configured CLTM handover conditions and sends an uplink notification message to the source DU. This message includes, but is not limited to, the ID of the target cell to which the UE is about to handover and its TCI status ID.

[0106] However, Figure 6 illustrates a possible DG-based RACH-less handover process in existing CLTM technology. In this DG-based RACH-less handover scenario within CLTM technology, when the UE is about to handover to the target DU, the UE is located at the edge of the source cell, and the connection quality with the source DU is very poor. Because the source DU may not be able to receive the uplink notification message sent by the UE, the LTM handover cannot be successfully completed.

[0107] So, in the DG-based RACH-less handover process scenario of CLTM technology, how can the UE and the target DU complete beam alignment and successfully transmit uplink data, thereby smoothly completing the LTM handover process?

[0108] To this end, this application provides a communication scheme in which, after determining the candidate cell, the CU notifies the UE that it will switch to the candidate cell by notifying the source DU and the candidate DU, and instructs the other candidate DUs (excluding the target DU) that the UE has switched to the cell corresponding to the target DU. This allows the source DU and the candidate DU to know the handover status in a timely manner, enabling the UE and the target DU to complete beam alignment and successfully send uplink data, thereby effectively avoiding the failure of the UE in the CLTM handover process.

[0109] The communication method provided in the embodiments of this application is described below based on the above communication system:

[0110] Figure 7 illustrates a CLTM handover scenario according to an embodiment of this application. In CLTM handover technology, the DU (Dedicated Access Unit) accessed by the UE before handover, i.e., the DU where the current serving cell is located, can be called the source DU / source access network device; the DU accessed after handover can be called the target DU / target access device. Before the UE performs a CLTM handover, the CU (Currency Control Unit) configures one or more candidate DUs (Candidate DU1, Candidate DU2, and Target DU in Figure 7) / candidate access devices for the UE. The UE can select one candidate DU for CLTM handover, and this candidate DU is the target DU. For example, if the DU where the UE's current serving cell is located is DU 0, the CU configures candidate DUs 1, DU 2, DU 3, and DU 4 for the UE. When the UE hands over from DU 0 to DU 1, DU 0 can be understood as the source DU for this handover, while DU 1 can be understood as the target DU for this handover. DUs 1 to DU 4 constitute the candidate DUs for this handover.

[0111] Figure 8 shows a flowchart of a communication method provided in an embodiment of this application. This flowchart illustrates the DG-based RACH-less handover process in the CLTM technology provided in this application embodiment, and takes the intra-CU CLTM cell switch (i.e., UE handover in LTM cells within the same CU) scenario as an example to describe the process of the UE handing over from the source DU to the target DU.

[0112] For example, the method may include the following steps:

[0113] S801.UE sends information 1 to source DU.

[0114] Information 1 is used to indicate the measurement result of layer 1.

[0115] For example, the Layer 1 measurement results are included in the Layer 1 measurement report.

[0116] S802. The source DU sends information 2 to the CU based on the layer 1 measurement results.

[0117] After receiving the Layer 1 measurement results, the source DU can filter out one or more candidate cells that may be used for UE handover based on the Layer 1 measurement results. That is, the one or more candidate cells are obtained based on the Layer 1 measurement results. After determining one or more candidate cells, the source DU sends information 2 to the CU. This information 2 is used to instruct the UE to handover to one or more candidate cells (this information 2 can also be called handover indication information 1), and the one or more candidate cells correspond to one or more candidate DUs. For example, a candidate DU may include one or more candidate cells.

[0118] Regarding the content of information 2, there are two possible implementations:

[0119] In one implementation, information 2 is used to indicate that the UE will hand over to the first candidate cell. Information 2 includes multiple TCI state IDs corresponding to the first candidate cell. The source DU can filter out one or more candidate beams based on the layer 1 measurement results. These one or more candidate beams belong to the first candidate cell (one candidate beam corresponds to one TCI state ID), and information 2 indicates the multiple TCI state IDs corresponding to the first candidate cell.

[0120] In another implementation, information 2 is used to indicate to the UE that it will switch to the first candidate cell and the second candidate cell. Information 2 includes the TCI state ID corresponding to the first candidate cell and the TCI state ID corresponding to the second candidate cell. The source DU can filter out one or more candidate beams based on the layer 1 measurement results. These one or more candidate beams belong to the first candidate cell and the second candidate cell respectively (one candidate beam corresponds to one TCI state ID). The DU indicates the TCI state ID corresponding to the first candidate cell and the TCI state ID corresponding to the second candidate cell through information 2.

[0121] For example, the source DU sends the above information 2 to the CU through the F1 interface.

[0122] S803.UE sends information 3 to CU.

[0123] For example, the UE sends information 3 to the CU via the source DU.

[0124] Information 3 is used to indicate the L3 measurement result.

[0125] For example, the layer 3 measurement results are included in the layer 3 measurement report.

[0126] S804.CU sends information 4 to the source DU based on the layer 3 measurement results.

[0127] After receiving the Layer 3 measurement results, the CU can filter out one or more candidate cells that may be used for UE handover based on the Layer 3 measurement results. That is, the one or more candidate cells are obtained based on the Layer 3 measurement results. After determining one or more candidate cells, the CU sends information 4 to the source DU. This information 4 is used to indicate that the UE will handover to one or more candidate cells (this information 4 can also be called handover indication information 2), or to indicate that the UE is about to perform a CLTM handover. These one or more candidate cells correspond to one or more candidate DUs. Thus, the source DU can know that the UE will handover to one or more candidate cells.

[0128] For example, the CU sends information 4 to the source DU via the F1 interface.

[0129] Regarding the content of information 4, there are two possible implementations:

[0130] In one implementation, information 4 is used to indicate that the UE will hand over to the first candidate cell. Information 4 includes multiple TCI state IDs corresponding to the first candidate cell. The CU selects one or more candidate beams that belong to the first candidate cell (one candidate beam corresponds to one TCI state ID) and indicates the multiple TCI state IDs corresponding to the first candidate cell to the source DU. For example, if the CU selects a candidate beam, then the first candidate cell can also correspond to one TCI state ID.

[0131] In another implementation, information 4 is used to indicate to the UE that it will switch to the first candidate cell and the second candidate cell. Information 4 includes the TCI state ID corresponding to the first candidate cell and the TCI state ID corresponding to the second candidate cell. The CU can filter one or more candidate beams based on the layer 3 measurement results. These one or more candidate beams belong to the first candidate cell and the second candidate cell respectively (one candidate beam corresponds to one TCI state ID). The CU indicates the TCI state ID corresponding to the first candidate cell and the TCI state ID corresponding to the second candidate cell to the source DU.

[0132] It is understood that the above steps S801 and S802 are optional, that is, the CU can determine one or more candidate cells based solely on the layer 3 measurement results.

[0133] Alternatively, the CU can also determine one or more candidate cells based on the Layer 3 measurement results and the aforementioned Information 2. Since the Layer 1 measurement results are beam-level measurements, handover triggering is relatively fast, while the Layer 3 measurement results are cell-level measurements. A cell typically includes 128 beams, and averaging the measurements of the 128 beams results in slower handover triggering, but the results are more accurate. Therefore, the CU can more accurately determine candidate cells based on its received Layer 3 measurement results and the candidate cells suggested by the source DU.

[0134] Alternatively, the UE may not send the Layer 3 measurement results to the CU, and the CU may determine one or more candidate cells based on the aforementioned Information 2 (i.e., Layer 1 measurement results).

[0135] S805.CU sends information 5 to one or more candidate DUs.

[0136] After the CU determines one or more candidate cells, it sends information 5 to one or more candidate DUs. This information 5 instructs the UE to handover to one or more candidate cells (this information 5 can also be called handover indication information 3). The one or more candidate cells include the target cell. A candidate DU includes one or more candidate cells.

[0137] For example, the CU sends information 5 to one or more candidate DUs via the F1 interface.

[0138] Regarding the content of information 5, there are two possible implementations:

[0139] In one implementation, information 5 is used to indicate that the UE will hand over to the first candidate cell. Information 5 includes multiple TCI state IDs corresponding to the first candidate cell. The CU selects one or more candidate beams, which belong to the first candidate cell (one candidate beam corresponds to one TCI state ID), and indicates the multiple TCI state IDs corresponding to the first candidate cell to the candidate DU corresponding to the first candidate cell. For example, if the CU selects a candidate beam, then the first candidate cell can also correspond to one TCI state ID.

[0140] In another implementation, information 5 is used to indicate to the UE that it will hand over to the first candidate cell and the second candidate cell. Information 5 includes the TCI state ID corresponding to the first candidate cell and the TCI state ID corresponding to the second candidate cell. The CU can filter out one or more candidate beams based on the layer 3 measurement results. These one or more candidate beams belong to the first candidate cell and the second candidate cell, respectively (one candidate beam corresponds to one TCI state ID). The CU indicates the TCI state ID corresponding to the first candidate cell to the candidate DU corresponding to the first candidate cell and indicates the TCI state ID corresponding to the second candidate cell to the candidate DU corresponding to the second candidate cell. For example, the candidate DU corresponding to the first candidate cell and the candidate DU corresponding to the second candidate cell can be the same DU or different DUs.

[0141] Furthermore, the information 5 may also include the beam direction that the UE is most likely to switch to (i.e., the primary beam) and other beam directions that the UE may switch to (other beams).

[0142] For example, the format of information 5 is shown in Table 1 below:

[0143] Table 1

[0144] A candidate cell includes one or more candidate beam directions. The UE measures and evaluates the candidate beam directions of the candidate cells to determine whether they meet the CLTM handover conditions, and prioritizes handover to candidate beams that meet the CLTM handover conditions. For example, the source DU filters one or more potential target beam directions (i.e., beams that may meet the CLTM handover conditions) based on the Layer 1 measurement report, maintains an implicit target beam list, sends it to the CU, and then to one or more candidate DUs. The UE can then handover to a beam direction that meets the CLTM handover conditions. The UE can handover to a beam that meets the CLTM handover conditions in the previously sent measurement results (measurement report) based on the DG-based RACH-less handover procedure. If one or more beams that met the CLTM handover conditions in the previous measurement results do not meet the CLTM handover conditions when the UE makes the handover decision, the UE performs a random access procedure (RACH process).

[0145] S806. The target DU sends information 6 to the UE.

[0146] After receiving the aforementioned information 5, the target DU sends information 6 to the UE according to the beam direction indicated by the CU. This information 6 can be DCI or PDCCH. Information 6 is used to indicate uplink resources (also known as uplink grants), which are used by the UE to send the first uplink data.

[0147] When the UE enters the coverage area of ​​the target DU, it detects the physical downlink control channel (PDCCH), receives information 6 from the target DU, and sends the first uplink message (e.g., uplink data) on the uplink resources indicated by information 6. Thus, the UE and the target DU can achieve beam alignment and successfully send uplink messages. In a possible DG-based RACH-less handover procedure in the existing CLTM technology shown in Figure 6, if the source DU does not receive the uplink notification message sent by the UE, step S603 will not be executed, i.e., a handover indication message will not be sent to the CU, thus preventing the CLTM handover from being completed.

[0148] Understandably, other candidate DUs besides the target DU are also sending DCIs to the UE at the same time. However, since the UE is in the coverage area of ​​the target DU, it may not detect the PDCCH between the UE and other candidate DUs besides the target DU.

[0149] Thus, the UE successfully accesses the target DU, where the target DU includes the target cell, and the target cell includes the aforementioned target beam.

[0150] After completing the above steps, the UE successfully completes the LTM handover process.

[0151] S807. The target DU sends information to the CU.

[0152] For example, the target DU sends information 7 to the CU through the F1 interface.

[0153] Among them, information 7 is used to indicate that the UE has accessed the cell corresponding to the target DU (this information 7 can also be called the connection completion message).

[0154] Among them, the cell corresponding to the target DU belongs to one or more of the above-mentioned candidate cells.

[0155] S808.CU sends information 8 to other candidate DUs besides the target DU.

[0156] For example, the CU sends information 8 (which may also be called a handover stop message) to other candidate DUs besides the target DU through the F1 interface.

[0157] Among them, information 8 is used to indicate that the UE has switched to the cell corresponding to the target DU and to notify other candidate DUs other than the target DU to stop sending DCI or PDCCH to the UE in the beam direction indicated by the CU.

[0158] According to a communication method provided in the embodiments of this application, after determining a candidate cell, the CU notifies the UE that it will switch to the candidate cell by notifying the source DU and the candidate DU, and instructs other candidate DUs other than the target DU that the UE has switched to the cell corresponding to the target DU. This enables the source DU and the candidate DU to know the handover status in a timely manner, so that the UE and the target DU can complete beam alignment and successfully send uplink messages, thereby effectively avoiding the failure of the UE in the CLTM handover process.

[0159] The above embodiments describe how the CU or source DU filters one or more candidate cells and notifies the source DU and one or more candidate DUs. The following embodiments describe how the CU determines one or more second candidate cells and indicates them to the UE, and the UE measures and evaluates whether any beam in the one or more second candidate cells satisfies the CLTM handover conditions:

[0160] Figure 9 shows a flowchart of another communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0161] S901.CU sends CLTM configuration information to UE via source DU.

[0162] The CLTM configuration information is used by the UE to determine whether the beam meets the CLTM handover conditions. This CLTM configuration information includes the identifiers of one or more third candidate cells and / or the TCI state IDs corresponding to one or more third candidate cells. A third candidate cell may include one or more candidate beams.

[0163] S902.UE sends information 9 to CU.

[0164] Information 9 is used to indicate the measurement results of layer 3.

[0165] For example, the layer 3 measurement results are included in the layer 3 measurement report.

[0166] S903.CU sends information 10 to UE.

[0167] After receiving the Layer 3 measurement results, the CU determines one or more fourth candidate cells from one or more third candidate cells. For example, these one or more fourth candidate cells are determined based on the Layer 3 measurement results, or they may be determined by the CU based on other conditions. Therefore, step S902 is optional, and is shown as a dashed line in Figure 9.

[0168] Then, the CU sends information 10 to the UE, indicating that the UE will perform a CLTM handover. This information 10 includes the identifiers of one or more fourth candidate cells and / or the TCI state IDs corresponding to those fourth candidate cells. These one or more fourth candidate cells correspond to one or more candidate DUs, and belong to the aforementioned one or more third candidate cells. A fourth candidate cell may include one or more candidate beams.

[0169] Furthermore, information 10 is used to indicate that the priority of one or more fourth candidate cells is higher than the priority of other candidate cells in one or more third candidate cells other than one or more fourth candidate cells. That is, it instructs the UE to prioritize whether one or more candidate beams in one or more fourth candidate cells meet the CLTM handover conditions when determining whether a beam meets the CLTM handover conditions. If one of the candidate beams in one or more fourth candidate cells meets the CLTM handover conditions, then that candidate beam is taken as the target beam. If one or more candidate beams in one or more fourth candidate cells do not meet the CLTM handover conditions, then the UE will consider whether one or more candidate beams in other candidate cells in one or more third candidate cells meet the CLTM handover conditions.

[0170] S904.CU sends information 11 to source DU.

[0171] After the CU determines one or more fourth candidate cells, it sends information 11 to the source DU, wherein information 11 is used to instruct the UE to hand over to one or more fourth candidate cells.

[0172] In this embodiment, if one or more candidate beams in one or more fourth candidate cells meet the CLTM handover conditions, the DG-based RACH-less handover procedure in CLTM technology is executed to hand over to the target beam; if one or more candidate beams in one or more fourth candidate cells do not meet the CLTM handover conditions, a random access procedure is executed. Therefore, the CU may not notify the source DU that the UE will hand over to one or more fourth candidate cells. Therefore, this step is optional and is represented by dashed lines in Figure 9.

[0173] S905.CU sends information 12 to one or more candidate DUs.

[0174] After the CU determines one or more fourth candidate cells, it sends information 12 to one or more candidate DUs, wherein information 12 is used to instruct the UE to hand over to one or more fourth candidate cells. The one or more fourth candidate cells correspond to one or more candidate DUs.

[0175] In this embodiment, if one or more candidate beams in one or more fourth candidate cells meet the CLTM handover conditions, the DG-based RACH-less handover procedure in CLTM technology is executed to hand over to the target beam; if one or more candidate beams in one or more fourth candidate cells do not meet the CLTM handover conditions, a random access procedure is executed. Therefore, the CU may also choose not to notify the UE of the handover to one or more candidate DUs. Thus, this step is optional and is represented by dashed lines in Figure 9.

[0176] S906.UE determines that one of one or more fourth candidate cells meets the CLTM handover conditions.

[0177] After receiving the above information 10, the UE measures one or more candidate beams in one or more fourth candidate cells to evaluate whether they meet the CLTM handover conditions.

[0178] The UE determines a fourth candidate cell that meets the CLTM handover conditions (which may be a candidate beam in the fourth candidate cell whose signal quality meets the CLTM handover conditions), and determines that the candidate cells that meet the CLTM handover conditions include / belong to one or more of the above-mentioned fourth candidate cells.

[0179] S907.UE switches to the target cell.

[0180] After the UE determines the target cell, it hands over to the target cell. The target cell is a fourth candidate cell that meets the CLTM handover conditions.

[0181] S908. The target DU sends information 13 to the CU.

[0182] The target cell mentioned above corresponds to the target DU. After the UE successfully accesses the target DU, the target DU promptly sends information 13 to the CU, where information 13 indicates that the UE has accessed the target cell. This target cell belongs to one or more of the aforementioned third candidate cells.

[0183] According to a communication method provided in this application embodiment, the CU determines one or more fourth candidate cells and indicates them to the UE. The UE measures and evaluates whether there is a beam in the one or more fourth candidate cells that meets the CLTM handover conditions. If there is a beam in the one or more fourth candidate cells that meets the CLTM handover conditions, the UE hands over to the beam in the one or more fourth candidate cells; otherwise, a random access procedure is executed to hand over to the beam in one or more third candidate cells configured in the CLTM configuration information. This enables the UE and the target DU to complete beam alignment and successfully transmit uplink data, effectively avoiding UE failure during the CLTM handover process.

[0184] Based on the method shown in Figure 9 above, the following example illustrates the DG-based RACH-less handover process in the CLTM technology provided in this application embodiment, and takes the intra-CU CLTM cell switch (i.e., UE handover in LTM cell within the same CU) scenario as an example to describe the process of UE handover from source DU to target DU.

[0185] Figure 10 shows a flowchart illustrating another communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0186] S1001.CU sends an RRC measurement configuration message to the UE via the source DU.

[0187] The RRC measurement configuration message includes CLTM configuration information. Further, the RRC measurement configuration message may also include L1 / L3 measurement report configuration information and a beam set. The CLTM configuration information includes identifiers of one or more third candidate cells and / or the TCI state IDs corresponding to one or more third candidate cells. The L1 / L3 measurement report configuration information is used by the UE to measure / evaluate candidate beams. The CU typically configures a low threshold value (e.g., threshold1). If the signal quality of a candidate beam is higher than this threshold value, the UE sends an L1 / L3 measurement report. The CLTM configuration information is used by the UE to determine whether a beam meets the CLTM handover conditions. The CU typically configures a higher threshold value (e.g., threshold2), where threshold2 is greater than threshold1.

[0188] S1002. The UE sends the L1 measurement result to the source DU.

[0189] For example, the L1 measurement result is included in the L1 measurement report.

[0190] S1003. The source DU sends a handover instruction message to the CU.

[0191] After receiving the L1 measurement results, the source DU selects the target cell (denoted as the fourth candidate cell) from the L1 measurement results, indicating the most likely target cell for the UE to handover. The DU corresponding to this target cell is designated as the target DU (denoted as the fourth candidate DU). Then, the source DU sends handover indication information 4 to the CU. This handover indication information 4 indicates to the CU that the UE is about to handover to the fourth candidate DU or is about to undergo a CLTM handover. This handover indication information 4 includes, but is not limited to, the ID of the target cell (fourth candidate cell) and the TCI state ID.

[0192] For example, the source DU sends a handover instruction message 4 to the CU via the F1 interface.

[0193] S1004. The UE sends the L3 measurement results to the CU.

[0194] For example, the L3 measurement result is included in the L3 measurement report.

[0195] S1005.CU sends a handover instruction message 5 to the source DU.

[0196] After receiving the L3 measurement results, the CU selects the target cell (denoted as the fourth candidate cell) from the L3 measurement results, indicating the UE is most likely to handover. The DU corresponding to this target cell is designated as the target DU (denoted as the fourth candidate DU). Then, the CU sends handover indication information 5 to the source DU. This handover indication information 5 indicates that the UE is about to handover to the fourth candidate DU or is about to undergo a CLTM handover. This handover indication information 5 includes, but is not limited to, the ID of the target cell (fourth candidate cell) and the TCI state ID.

[0197] It is understood that the above steps S1002 and S1003 are optional, that is, the CU can determine the target cell (fourth candidate cell) based solely on the layer 3 measurement results.

[0198] Alternatively, the CU can also determine the target cell (fourth candidate cell) based on the Layer 3 measurement results and the aforementioned handover indication information 4. Since the Layer 1 measurement results are beam-level measurements, handover triggering is relatively fast, while the Layer 3 measurement results are cell-level measurements. A cell typically includes 128 beams, and averaging the measurements of the 128 beams results in slower handover triggering, but the results are more accurate. Therefore, the CU can more accurately determine the target cell (fourth candidate cell) based on its received Layer 3 measurement results and the target cell suggested by the source DU.

[0199] Alternatively, the UE may not send the Layer 3 measurement results to the CU, and the CU may determine the target cell (fourth candidate cell) based on the aforementioned handover indication information 4 (i.e., Layer 1 measurement results).

[0200] S1006.CU sends a handover instruction message 6 to the target DU.

[0201] For example, the CU sends a handover instruction message 6 to the target DU via the F1 interface.

[0202] The handover indication information 6 is used to indicate that the target DU UE is about to hand over to the target DU (the DU corresponding to the fourth candidate cell). The handover indication information 6 includes, but is not limited to, the ID of the target cell (the fourth candidate cell) and the TCI state ID.

[0203] S1007a. Source DU sends information 14 to UE.

[0204] After receiving the handover instruction information 5, the source DU sends information 14 to the UE.

[0205] Specifically, information 14 is used to instruct the UE that when performing a CLTM handover, if multiple candidate beams meet the CLTM handover conditions, the target beam direction has the highest handover priority. For example, assuming the candidate beams include reference signals (RS)1 to RS4, and the target beam is RS1, then RS1 has the highest handover priority.

[0206] It is understood that the above information 14 may also include the following: the target beam has the highest handover priority; if the target beam does not meet the CLTM handover conditions, but the second-priority beam meets the CLTM handover conditions, then the UE can handover to the second-priority beam, i.e., maintain an explicit target beam list. For example, the format of information 14 can be shown in Table 2 below:

[0207] Table 2

[0208] For example, the above information 14 may be carried in at least one of the following messages: DCI, MAC CE.

[0209] S1007b.CU sends information 15 to the UE.

[0210] The content of information 15 can be the same as that of information 14.

[0211] For example, information 15 can be carried in an RRC message.

[0212] It is understood that steps S1007a or S1007b can be performed, or steps S1007a and S1007b can be performed.

[0213] Understandably, before the UE performs a CLTM handover, the UE can send the measurement results to the source DU / CU via the L1 / L3 measurement report, thereby updating the fourth candidate cell (e.g., updating the priority of the target beam and / or candidate beams). Therefore, the above steps S1002 to S1007b can be repeated.

[0214] The UE measures and evaluates the candidate beams (e.g., RS1 to RS4) in one or more third candidate cells configured in the above RRC configuration message to determine whether the CLTM handover conditions are met; or the UE measures and evaluates the candidate beams (e.g., RS1) in one or more fourth candidate cells indicated in the above information 14 or information 15, and first determines whether RS1 meets the CLTM handover conditions.

[0215] Depending on whether the target beam (RS1) meets the CLTM switching conditions, the following two cases will be discussed:

[0216] Scenario 1:

[0217] When a UE performs a CLTM handover, if a candidate beam (e.g., RS1) in one or more fourth candidate cells indicated by the source DU / CU meets the CLTM handover conditions (e.g., the beam quality of RS1 is greater than or equal to threshold2), the UE will handover to that beam through the DG-based RACH-less handover procedure in CLTM technology.

[0218] S1008a. After receiving the indication from the source DU / CU, the target DU (the DU corresponding to one or more fourth candidate cells) sends a DCI according to the beam direction indicated by the source DU / CU, providing uplink authorization, i.e., uplink resources. When the UE enters the coverage area of ​​the target DU, it detects the PDCCH and receives the DCI sent by the target DU, thus successfully sending the first uplink data. At this time, the UE successfully accesses the target DU.

[0219] S1009a. After completing the above steps, the UE successfully completes the LTM handover process.

[0220] S1010a. The target DU sends information 16 to the CU.

[0221] For example, the target DU sends information 16 to the CU via the F1 interface.

[0222] Among them, information 16 is used to indicate that the UE has accessed the cell corresponding to the target DU (this information 16 can also be called the connection completion message).

[0223] Scenario 2:

[0224] When a UE performs a CLTM handover, if the candidate beams in one or more fourth candidate cells indicated by the source DU / CU do not meet the CLTM handover conditions (for example, the beam quality of RS1 is less than threshold2), the UE will handover to the candidate beams in one or more third candidate cells other than one or more fourth candidate cells, such as candidate beams RS2 to RS4, through the random access procedure (RACH procedure).

[0225] S1008b. The UE selects a candidate beam that meets the CLTM handover conditions as the target beam and initiates a random access procedure to the target cell. When the UE successfully sends the first uplink data to the target cell, the UE successfully accesses the target DU.

[0226] S1009b. After completing the above steps, the UE successfully completes the LTM handover process.

[0227] S1010b. The target DU sends information 17 to the CU.

[0228] For example, the target DU sends information 17 to the CU through the F1 interface.

[0229] Among them, information 17 is used to indicate that the UE has accessed the cell corresponding to the target DU (this information 17 can also be called the connection completion message).

[0230] The following examples involve uplink / downlink beam alignment:

[0231] Beam alignment is a key step in beam management. To ensure smooth signal transmission between the UE and the base station, the UE and the base station need to complete uplink beam alignment and downlink beam alignment respectively.

[0232] Uplink beam alignment: refers to the alignment of the UE's transmit beam with the base station's receive beam.

[0233] Downlink beam alignment: refers to the alignment of the UE's receive beam with the base station's transmit beam.

[0234] After beam alignment is complete, the UE's uplink and downlink can share the same Transmission Configuration Indicator State ID (TCI state ID), a situation known as Joint TCI state ID. In this case, both uplink and downlink beams use the same TCI state ID. If the uplink and downlink beams use different TCI state IDs (possibly due to different reference signal types), it is called Separate TCI state ID, which includes both the uplink TCI state ID (UL TCI state ID) and the downlink TCI state ID (DL TCI state ID).

[0235] In the traditional CLTM technology's CG-based RACH-less handover scenario, under the Joint TCI state, CG resources are associated with the TCI state ID, and uplink and downlink beam alignment are completed when the UE sends the first uplink message. However, under the Separate TCI state, uplink and downlink beams use different TCI state IDs, and CG resources are associated with the DL TCI state ID. How is the DL TCI state ID determined?

[0236] To this end, this application provides a communication scheme. In the Separate TCI state scenario, when the UE completes LTM handover and sends the first uplink message, it can only complete uplink beam alignment. The UE can send information carrying the DL TCI state ID to the target DU / CU to further achieve downlink beam alignment.

[0237] Figure 11 shows a flowchart illustrating another communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0238] S1100.CU sends an RRC measurement configuration message to the UE.

[0239] The meaning of the RRC measurement configuration message can be referred to step S1001 of the embodiment shown in Figure 10. The RRC measurement configuration message includes CLTM configuration information. Further, the RRC measurement configuration message may also include L1 / L3 measurement report configuration information and beam sets. The CLTM configuration information includes the identifiers of one or more first candidate cells and / or the TCI state IDs corresponding to one or more first candidate cells.

[0240] Specifically, when the uplink and downlink beams use the same TCI state ID (i.e., in the Joint TCI state scenario), the CG resource is associated with the TCI state ID. When the uplink and downlink beams use different TCI state IDs (i.e., in the Separate TCI state scenario), the CG resource is associated with the UL TCI state ID (denoted as the first TCI state ID).

[0241] This embodiment aims to solve the problem of how to determine the DL TCI state ID (denoted as the second TCI state ID) in the Separate TCI state scenario.

[0242] S1101~S1108. Refer to steps S801~S808 of the embodiment shown in FIG8.

[0243] When the UE enters the coverage area of ​​the target DU, it detects the PDCCH and receives the DCI message sent by the target DU, thus successfully sending the first uplink message (e.g., uplink / downlink data).

[0244] The authorized resource is associated with the first TCI state ID, which corresponds to the uplink beam.

[0245] In the Separate TCI state scenario, the UE completes uplink beam alignment by sending and receiving the first uplink message.

[0246] S1109. The UE sends information 18 to the target DU (or CU).

[0247] The information 18 includes a second TCI state ID, which corresponds to the downlink beam.

[0248] In addition, the information 18 may also include the aforementioned first TCI state ID.

[0249] For example, when the UE sends information 18 to the CU, the aforementioned information 18 can be carried in an RRC message.

[0250] For example, when the UE sends information 18 to the target DU, the information 18 may be carried in at least one of the following signaling: MAC CE, DCI.

[0251] According to a communication method provided in an embodiment of this application, in the Separate TCI state scenario, when the UE completes LTM handover and sends the first uplink message, it can only complete uplink beam alignment. The UE can send information carrying the DL TCI state ID to the target DU / CU to further achieve downlink beam alignment.

[0252] In this application, the phrase "sending information to... (e.g., UE)" or the related illustrations in the accompanying drawings can be understood as the destination of the information being the UE. This can include sending information directly or indirectly to the UE. Similarly, "receiving information from... (e.g., UE)" or "receiving information from... (e.g., UE)" or the related illustrations in the accompanying drawings can be understood as the source of the information being the UE. This can include receiving information directly or indirectly from the UE. The information may undergo necessary processing between the source and destination, such as format changes, but the destination can understand the valid information from the source. Similar expressions in this application can be interpreted similarly, and will not be elaborated further here.

[0253] It is understood that this application uses the UE and network device (including CU, source DU, and candidate DU) as examples to illustrate the execution of the interaction, but this application does not limit the execution of the interaction. For example, the UE in the method provided by this application can also be a chip, chip system, or processor applied to the UE, or a logical node, logical module, or software that can implement all or part of the UE; the network device in the method provided by this application can also be a chip, chip system, or processor applied to the network device, or a logical node, logical module, or software that can implement all or part of the network device functions.

[0254] It is understood that, in order to achieve the functions in the above embodiments, the network device and UE include hardware structures and / or software modules corresponding to perform each function. Those skilled in the art should readily recognize that, based on the units and method steps of the various examples described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0255] Figures 12 and 13 are schematic diagrams of possible communication devices provided in embodiments of this application. These communication devices can be used to implement the functions of the UE or network device in the above method embodiments, and thus can also achieve the beneficial effects of the above method embodiments. In the embodiments of this application, the communication device can be one of the UEs 120a-120j shown in Figure 1, or it can be the network device 110a or 110b shown in Figure 1, or it can be a module (such as a chip) applied to the UE or network device.

[0256] As shown in Figure 12, the communication device 1200 includes a processing unit 1210 and a transceiver unit 1220. The communication device 1200 is used to implement the functions of the UE or network device in the method embodiments shown in Figures 6-8 above.

[0257] When the communication device 1200 is used to implement the functions of the UE: the transceiver unit 1220 is used to execute at least one step performed by the UE in steps S801, S803, and S806 in the embodiment shown in FIG8; or, the transceiver unit 1220 is used to execute at least one step performed by the UE in steps S901, S902, and S903 in the embodiment shown in FIG9, and the processing unit 1210 is used to execute at least one step in steps S906 and S907 in the embodiment shown in FIG9; or, the transceiver unit 1220 is used to execute at least one step performed by the UE in steps S1100 to S1109 in the embodiment shown in FIG11.

[0258] When the communication device 1200 is used to implement the function of the source DU: the transceiver unit 1220 is used to execute at least one step performed by the source DU in steps S801, S802, and S804 in the embodiment shown in FIG8; or, the transceiver unit 1220 is used to execute step S904 in the embodiment shown in FIG9.

[0259] When the communication device 1200 is used to implement the function of the target DU: the transceiver unit 1220 is used to execute at least one step performed by the target DU in steps S805 and S807 in the embodiment shown in FIG8; or, the transceiver unit 1220 is used to execute step S908 in the embodiment shown in FIG9.

[0260] When the communication device 1200 is used to implement the function of the CU: the transceiver unit 1220 is used to execute at least one step performed by the CU in steps S802, S803, S804, S807, and S808 in the embodiment shown in FIG8; or, the transceiver unit 1220 is used to execute at least one step performed by the CU in steps S901 to S905 and S908 in the embodiment shown in FIG9.

[0261] When the communication device 1200 is used to implement the function of the candidate DU: the transceiver unit 1220 is used to execute at least one step of the candidate DU in steps S805 and S808 in the embodiment shown in FIG8; or, the transceiver unit 1220 is used to execute step S905 in the embodiment shown in FIG9.

[0262] A more detailed description of the processing unit 1210 and the transceiver unit 1220 can be obtained directly from the relevant descriptions in the method embodiments shown in Figures 8-11, and will not be repeated here.

[0263] When the aforementioned communication device is a chip applied to the UE, the UE chip implements the functions of the UE in the above method embodiments. The UE chip receives information from other modules in the UE (such as radio frequency modules or antennas), which is sent to the UE by the network device; or, the UE chip sends information to other modules in the UE (such as radio frequency modules or antennas), which is sent to the network device by the UE.

[0264] When the aforementioned communication device is a chip applied to a network device, the network device chip implements the functions of the network device in the above method embodiments. The network device chip receives information from other modules (such as radio frequency modules or antennas) in the network device, which is sent by the UE to the network device; or, the network device chip sends information to other modules (such as radio frequency modules or antennas) in the network device, which is sent by the network device to the UE.

[0265] Furthermore, it should be noted that the aforementioned transceiver unit and / or processing unit can be implemented through virtual modules. For example, the processing unit can be implemented through software functional units or virtual devices, and the transceiver unit can be implemented through software functions or virtual devices. Alternatively, the processing unit or transceiver unit can also be implemented through physical devices. For example, if the device is implemented using a chip / chip circuit, the transceiver unit can be an input / output circuit and / or a communication interface, performing input operations (corresponding to the aforementioned receiving operation) and output operations (corresponding to the aforementioned sending operation); the processing unit is an integrated processor, microprocessor, or integrated circuit.

[0266] As shown in Figure 13, the communication device 1300 includes a processor 1310 and may also include an interface circuit 1320. The processor 1310 and the interface circuit 1320 are coupled to each other. It is understood that the interface circuit 1320 can be a transceiver or an input / output interface. Optionally, the communication device 1300 may also include a memory 1330 (shown as a dashed line in the figure) for storing instructions executed by the processor 1310, or storing input data required by the processor 1310 to execute instructions, or storing data generated after the processor 1310 executes instructions.

[0267] When the communication device 1300 is used to implement the functions of the UE: the interface circuit 1320 is used to execute at least one step performed by the UE in steps S801, S803, and S806 in the embodiment shown in FIG8; or, the interface circuit 1320 is used to execute at least one step performed by the UE in steps S901, S902, and S903 in the embodiment shown in FIG9, and the processor 1310 is used to execute at least one step in steps S906 and S907 in the embodiment shown in FIG9; or, the interface circuit 1320 is used to execute at least one step performed by the UE in steps S1100 to S1109 in the embodiment shown in FIG11.

[0268] When the communication device 1300 is used to implement the function of the source DU: the interface circuit 1320 is used to execute at least one step performed by the source DU in steps S801, S802, and S804 in the embodiment shown in FIG8; or, the interface circuit 1320 is used to execute step S904 in the embodiment shown in FIG9.

[0269] When the communication device 1300 is used to implement the function of the target DU: the interface circuit 1320 is used to execute at least one step performed by the target DU in steps S805 and S807 in the embodiment shown in FIG8; or, the interface circuit 1320 is used to execute step S908 in the embodiment shown in FIG9.

[0270] When the communication device 1200 is used to implement the function of the CU: the interface circuit 1320 is used to execute at least one step performed by the CU in steps S802, S803, S804, S807, and S808 in the embodiment shown in FIG8; or, the interface circuit 1320 is used to execute at least one step performed by the CU in steps S901 to S905 and S908 in the embodiment shown in FIG9.

[0271] When the communication device 1300 is used to implement the function of the candidate DU: the interface circuit 1320 is used to execute at least one step of the candidate DU in steps S805 and S808 in the embodiment shown in FIG8; or, the interface circuit 1320 is used to execute step S905 in the embodiment shown in FIG9.

[0272] A more detailed description of the processor 1310 and interface circuit 1320 can be obtained directly from the relevant descriptions in the method embodiments shown in Figures 8-11, and will not be repeated here.

[0273] When the aforementioned communication device is a chip applied to a terminal, the terminal chip implements the functions of the terminal in the above method embodiments. The terminal chip receives information from the base station, which can be understood as the information being first received by other modules in the terminal (such as an RF module or antenna), and then sent to the terminal chip by these modules. The terminal chip sends information to the base station, which can be understood as the information being first sent to other modules in the terminal (such as an RF module or antenna), and then sent to the base station by these modules.

[0274] When the aforementioned communication device is a chip applied to a base station, the base station chip implements the functions of the base station in the above method embodiments. The base station chip receives information from the terminal, which can be understood as the information being first received by other modules in the base station (such as an RF module or antenna), and then sent to the base station chip by these modules. The base station chip sends information to the terminal, which can be understood as the information being sent down to other modules in the base station (such as an RF module or antenna), and then sent to the terminal by these modules.

[0275] In this application, entity A sends information to entity B, either directly or indirectly through other entities. Similarly, entity B receives information from entity A, either directly or indirectly through other entities. Entities A and B can be RAN nodes or terminals, or modules within RAN nodes or terminals. Information transmission and reception can be between RAN nodes and terminals, such as between a base station and a terminal; between two RAN nodes, such as between a CU and a DU; or between different modules within a single device, such as between a terminal chip and other modules of the terminal, or between a base station chip and other modules of the base station.

[0276] It is understood that in this application, "instruction" can include direct instruction, indirect instruction, explicit instruction, and implicit instruction. When describing a certain instruction information to indicate A, it can be understood that the instruction information carries A, directly indicates A, or indirectly indicates A. In this application, the information indicated by the instruction information is called the information to be instructed. In specific implementation, there are many ways to indicate the information to be instructed, such as, but not limited to, directly indicating the information to be instructed, such as the information to be instructed itself or its index, or indirectly indicating the information to be instructed by indicating other information, wherein there is an association between the other information and the information to be instructed. It is also possible to indicate only a part of the information to be instructed, while the other parts of the information to be instructed are known or agreed upon in advance. For example, the instruction of specific information can also be achieved by using the arrangement order of various information in advance (e.g., as specified by a protocol), thereby reducing the instruction overhead to a certain extent. The information to be instructed can be sent as a whole or divided into multiple sub-information to be sent separately, and the sending period and / or sending time of these sub-information can be the same or different. This application does not limit the specific sending method. The sending period and / or timing of these sub-information messages can be predefined, for example, according to a protocol, or configured by the transmitting device by sending configuration information to the receiving device.

[0277] It is understood that the processor in the embodiments of this application can be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, field-programmable gate arrays, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0278] The method steps in the embodiments of this application can be implemented in hardware or in software instructions executable by a processor. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, optical discs, or any other form of storage medium well known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. The storage medium can also be a component of the processor. The processor and the storage medium can reside in an application-specific integrated circuit (ASIC). Alternatively, the ASIC can reside in a base station or terminal. The processor and the storage medium can also exist as discrete components in the base station or terminal.

[0279] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are performed entirely or partially. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user equipment, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both types of storage media.

[0280] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0281] Depending on whether the specification uses "optional": In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates an "or" relationship between the preceding and following related objects; in the formulas of this application, the character " / " indicates a "division" relationship between the preceding and following related objects. "Including at least one of A, B, and C" can mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B, and C.

[0282] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

Claims

1. A communication method, characterized in that, The method includes: Receive first information from the terminal, the first information being used to indicate the layer 3 measurement result; Based on the Layer 3 measurement results, a second message is sent to the source DU. The second message is used to instruct the terminal to switch to one or more candidate cells, and the one or more candidate cells correspond to one or more candidate DUs. A third message is sent to the one or more candidate DUs, the third message being used to instruct the terminal to switch to the one or more candidate cells.

2. The method as described in claim 1, characterized in that, The one or more candidate cells are obtained based on the layer 3 measurement results.

3. The method as described in claim 1 or 2, characterized in that, The third information is used to indicate that the terminal will switch to the first candidate cell. The third information includes the identifiers of multiple Transmission Configuration Indicators (TCIs) corresponding to the first candidate cell.

4. The method according to any one of claims 1-3, characterized in that, The third information is used to instruct the terminal to switch to the first candidate cell and the second candidate cell. The third information includes the identifier of the TCI state corresponding to the first candidate cell and the identifier of the TCI state corresponding to the second candidate cell.

5. The method according to any one of claims 1-4, characterized in that, The method further includes: The terminal receives fourth information from the target DU, the fourth information indicating that the terminal has accessed the cell corresponding to the target DU, and the cell corresponding to the target DU belongs to one or more candidate cells.

6. The method as described in claim 5, characterized in that, The method further includes: Send a fifth message to other candidate DUs besides the target DU, the fifth message indicating that the terminal has switched to the cell corresponding to the target DU.

7. The method according to any one of claims 1-6, characterized in that, The terminal will perform a condition-triggered Layer 1 / Layer 2 Mobility CLTM handover.

8. A communication method, characterized in that, The method includes: Receive sixth information from the terminal, the sixth information being used to indicate the measurement result of layer 1; Based on the Layer 1 measurement results, a seventh message is sent to the centralized unit (CU). The seventh message is used to instruct the terminal to switch to one or more candidate cells, and the one or more candidate cells correspond to one or more candidate distributed units (DUs).

9. The method as described in claim 8, characterized in that, The one or more candidate cells are obtained based on the Layer 1 measurement results.

10. The method as described in claim 8 or 9, characterized in that, The seventh information is used to indicate that the terminal will switch to the first candidate cell. The seventh information includes the identifiers of multiple Transmission Configuration Indicator (TCI) states corresponding to the first candidate cell.

11. The method according to any one of claims 8-10, characterized in that, The seventh information is used to instruct the terminal to switch to the first candidate cell and the second candidate cell. The seventh information includes the identifier of the TCI state corresponding to the first candidate cell and the identifier of the TCI state corresponding to the second candidate cell.

12. The method according to any one of claims 8-11, characterized in that, The terminal will perform a condition-triggered Layer 1 / Layer 2 Mobility CLTM handover.

13. A communication method, characterized in that, Applied to the first candidate distributed DU, the method includes: Receive third information from the centralized unit (CU), the third information being used to instruct the terminal to switch to one or more candidate cells; If the target cell belongs to the first candidate DU, the eighth information is sent to the terminal, and the eighth information is used to indicate uplink resources; If the target cell does not belong to the first candidate DU, the terminal receives fifth information from the CU, which indicates that the terminal has switched to the cell corresponding to the target DU.

14. The method as described in claim 13, characterized in that, The third information includes identifiers of multiple Transmission Configuration Indicators (TCIs) corresponding to the first candidate cell.

15. The method as described in claim 13 or 14, characterized in that, The terminal will perform a condition-triggered Layer 1 / Layer 2 Mobility CLTM handover.

16. A communication method, characterized in that, The method includes: Send condition-triggered Layer 1 / Layer 2 Mobility CLTM configuration information, the CLTM configuration information including the identifiers of one or more third candidate cells and / or the identifiers of the Transmission Configuration Indicator (TCI) status corresponding to the one or more third candidate cells; Send first information to the terminal. The first information includes the identifier of one or more fourth candidate cells and / or the identifier of the Transmission Configuration Indicator (TCI) status corresponding to the one or more fourth candidate cells. The one or more fourth candidate cells correspond to one or more candidate distributed units (DUs). The one or more fourth candidate cells belong to the one or more third candidate cells.

17. The method as described in claim 16, characterized in that, The first information is used to indicate that the priority of the one or more fourth candidate cells is higher than the priority of the other candidate cells in the one or more third candidate cells besides the one or more fourth candidate cells.

18. The method as described in claim 16 or 17, characterized in that, The method further includes: Receive second information from the terminal, the second information being used to indicate the layer 3 measurement result; The one or more fourth candidate cells are determined based on the layer 3 measurement results.

19. The method according to any one of claims 16-18, characterized in that, The method further includes: Send a third message to the source DU, the third message being used to instruct the terminal to switch to one or more fourth candidate cells.

20. The method according to any one of claims 16-19, characterized in that, The method further includes: Send a fourth message to the one or more candidate DUs, the fourth message being used to instruct the terminal to switch to the one or more fourth candidate cells.

21. The method according to any one of claims 16-20, characterized in that, The method further includes: The terminal receives fifth information from the target DU, the fifth information indicating that the terminal has accessed the target cell, the target cell belonging to one or more third candidate cells.

22. A communication method, characterized in that, The method includes: Receive condition-triggered Layer 1 / Layer 2 Mobility CLTM configuration information, wherein the CLTM configuration information includes the identifiers of one or more third candidate cells and / or the identifiers of the Transmission Configuration Indicator (TCI) status corresponding to the one or more third candidate cells; Receive first information from a centralized unit (CU) and / or a source distributed unit (DU), the first information including the identifier of one or more fourth candidate cells and / or the identifier of the Transmission Configuration Indicator (TCI) status corresponding to the one or more fourth candidate cells, the one or more fourth candidate cells corresponding to one or more candidate distributed units (DU), and the one or more fourth candidate cells belonging to the one or more third candidate cells; One of the one or more fourth candidate cells is determined to meet the CLTM handover conditions; The handover is performed to the target cell, which is a fourth candidate cell that meets the CLTM handover conditions.

23. The method as described in claim 22, characterized in that, Determining that one of the one or more fourth candidate cells meets the CLTM handover condition includes: Identify candidate cells that meet the CLTM handover conditions; The candidate cells that meet the CLTM handover conditions include the one or more fourth candidate cells.

24. The method as described in claim 22 or 23, characterized in that, The first information is used to indicate that the priority of the one or more fourth candidate cells is higher than the priority of the other candidate cells in the one or more third candidate cells besides the one or more fourth candidate cells.

25. A communication method, characterized in that, The method includes: Uplink messages are sent on authorized resources, which are associated with an identifier of a first transmission configuration indicator (TCI) state, and the identifier of the first TCI state corresponds to an uplink beam. Send first information to the network device, the first information including an identifier of a second TCI state, the identifier of the second TCI state corresponding to a downlink beam.

26. A communication device, characterized in that, Includes modules for implementing the method as described in any one of claims 1-25.

27. A communication device, characterized in that, The device includes a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices and transmit them to the processor or to send signals from the processor to other communication devices, and the processor is used to implement the method as described in any one of claims 1-25 through logic circuits or executing code instructions.

28. A computer-readable storage medium, characterized in that, The storage medium stores a computer program or instructions, which, when executed by a communication device, implement the method as described in any one of claims 1-25.

29. A computer program product, characterized in that, The computer program product includes relevant program instructions, which, when executed, implement the method as described in any one of claims 1-25.

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