PDCCH (physical downlink control channel) monitoring method, device, equipment and storage medium

Abstract

The invention discloses a PDCCH (Physical Downlink Control Channel) monitoring method and device, equipment and a storage medium, and relates to the technical field of communication. The method comprises: a first network device sends a switching command to a terminal device, the switching command being used for instructing the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to a second network device; and the terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the target BWP of the second cell. According to the invention, after the terminal device receives the switching command, the terminal device monitors the PDCCH sent by the target cell based on the CORESET associated with the target BWP of the target cell, so that the terminal device can accurately monitor the PDCCH, thereby obtaining available uplink resources from the PDCCH to send the switching completion message, and improving the switching success rate.

Description

[0001] This application is a divisional application of the PCT international patent application PCT / CN2021 / 108259 with an application date of July 23, 2021, which has entered the Chinese national phase with Chinese patent application number 202180098050.6 and the invention name being "PDCCH monitoring method, apparatus, device and storage medium". Technical Field

[0002] The embodiments of the present application relate to the field of communication technology, and in particular to a PDCCH (Physical Downlink Control Channel) monitoring method, device, equipment and storage medium. Background Art

[0003] For the cell switching scenario of the terminal device, in some switching modes, the terminal device monitors the PDCCH (Physical Downlink Control Channel) of the target cell, waits for the target cell to schedule uplink transmission, and sends a switching completion message using the scheduled uplink resources.

[0004] Currently, the monitoring method for PDCCH needs further research. Summary of the invention

[0005] The present application provides a PDCCH monitoring method, apparatus, device and storage medium. The technical solution is as follows:

[0006] According to one aspect of an embodiment of the present application, a PDCCH monitoring method is provided, the method being executed by a terminal device, the method comprising:

[0007] receiving a handover command sent by a first network device, wherein the handover command is used to instruct the terminal device to handover from a first cell corresponding to the first network device to a second cell corresponding to a second network device;

[0008] Based on the CORESET (Control Resource Set) associated with the target BWP (Bandwidth Part) of the second cell, monitor the PDCCH sent by the second network device.

[0009] According to one aspect of an embodiment of the present application, a PDCCH monitoring method is provided, the method being performed by a first network device, the method comprising:

[0010] Sending a handover command to a terminal device, wherein the handover command is used to instruct the terminal device to handover from a first cell corresponding to the first network device to a second cell corresponding to the second network device;

[0011] The terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the target BWP of the second cell.

[0012] According to one aspect of an embodiment of the present application, a PDCCH monitoring method is provided, the method being performed by a second network device, the method comprising:

[0013] Sending a handover command to the first network device, wherein the handover command is used to instruct the terminal device to handover from a first cell corresponding to the first network device to a second cell corresponding to the second network device;

[0014] A PDCCH is sent at a target BWP, wherein the terminal device monitors the PDCCH based on a CORESET associated with the target BWP.

[0015] According to one aspect of an embodiment of the present application, a PDCCH monitoring device is provided, the device comprising:

[0016] A receiving module, configured to receive a switching command sent by a first network device, wherein the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to a second network device;

[0017] The monitoring module is used to monitor the PDCCH sent by the second network device based on the CORESET associated with the target BWP of the second cell.

[0018] According to one aspect of an embodiment of the present application, a PDCCH monitoring device is provided, the device comprising:

[0019] A sending module, used to send a switching command to a terminal device, wherein the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device;

[0020] The terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the target BWP of the second cell.

[0021] According to one aspect of an embodiment of the present application, a PDCCH monitoring device is provided, the device comprising:

[0022] A sending module, used to send a switching command to the first network device, wherein the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device;

[0023] The sending module is further used to send the PDCCH in the target BWP, wherein the terminal device monitors the PDCCH based on the CORESET associated with the target BWP.

[0024] According to one aspect of an embodiment of the present application, a PDCCH monitoring device is provided, the device comprising:

[0025] A sending module, used to send a switching command to the first network device, wherein the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device;

[0026] The sending module is further used to send PDCCH in the target bandwidth part BWP, wherein the terminal device monitors the PDCCH based on the control resource set CORESET associated with the target BWP.

[0027] According to one aspect of an embodiment of the present application, a terminal device is provided, the terminal device comprising a processor and a memory, the memory storing a computer program, the processor executing the computer program to implement the PDCCH monitoring method on the terminal device side.

[0028] According to one aspect of an embodiment of the present application, a network device is provided, comprising a processor and a memory, wherein the memory stores a computer program, and the processor executes the computer program to implement the PDCCH monitoring method on the first network device side, or to implement the PDCCH monitoring method on the second network device side.

[0029] According to one aspect of an embodiment of the present application, a computer-readable storage medium is provided, in which a computer program is stored. The computer program is used to be executed by a processor to implement the above-mentioned PDCCH monitoring method.

[0030] According to one aspect of an embodiment of the present application, a chip is provided, wherein the chip includes a programmable logic circuit and / or program instructions, and when the chip is running, it is used to implement the above-mentioned PDCCH monitoring method.

[0031] According to one aspect of an embodiment of the present application, a computer program product or a computer program is provided, wherein the computer program product or the computer program includes computer instructions, wherein the computer instructions are stored in a computer-readable storage medium, and a processor reads and executes the computer instructions from the computer-readable storage medium to implement the above-mentioned PDCCH monitoring method.

[0032] The technical solution provided by the embodiments of the present application may have the following beneficial effects:

[0033] After receiving the switching command, the terminal device monitors the PDCCH sent by the target cell based on the CORESET associated with the target BWP of the target cell, so that the terminal device can accurately monitor the PDCCH, thereby obtaining available uplink resources from the PDCCH to send a switching completion message, thereby improving the switching success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of a network architecture provided by an embodiment of the present application;

[0035] Figure 2 A schematic diagram exemplarily shows the switching relationship between RRC states in the NR system;

[0036] Figure 3 A schematic diagram showing an exemplary cell switching process in an NR system;

[0037] Figure 4 A schematic diagram showing an adaptive change process of bandwidth in an NR system is exemplified;

[0038] Figure 5 A schematic diagram exemplarily shows a MAC CE format for indicating a TCI state corresponding to a PDCCH;

[0039] Figure 6 is a flow chart of a PDCCH monitoring method according to an embodiment of the present application;

[0040] Figure 7 is a flow chart of a PDCCH monitoring method according to another embodiment of the present application;

[0041] Figure 8 is a flow chart of a PDCCH monitoring method according to another embodiment of the present application;

[0042] Fig. 9 is a flow chart of a PDCCH monitoring method according to another embodiment of the present application;

[0043] Fig.10 is a flow chart of a PDCCH monitoring method according to another embodiment of the present application;

[0044] Fig.11 is a block diagram of a PDCCH monitoring device provided by an embodiment of the present application;

[0045] Fig.12 is a block diagram of a PDCCH monitoring device provided by another embodiment of the present application;

[0046] Fig.13 is a block diagram of a PDCCH monitoring device provided by another embodiment of the present application;

[0047] Fig.14 is a schematic diagram of the structure of a terminal device provided by an embodiment of the present application;

[0048] Fig.15 It is a structural diagram of a network device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0050] The network architecture and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. A person of ordinary skill in the art can appreciate that with the evolution of the network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0051] Please refer to Figure 1 , which shows a schematic diagram of a network architecture provided by an embodiment of the present application. The network architecture may include: a terminal device 10, an access network device 20 and a core network device 30.

[0052] The terminal device 10 may refer to UE (User Equipment), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, wireless communication device, user agent or user device. Optionally, the terminal device 10 may also be a cellular phone, a cordless phone, a SIP (Session Initiation Protocol) phone, a WLL (Wireless Local Loop) station, a PDA (Personal Digital Assistant), a handheld device with wireless communication function, a computing device or other processing devices connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal device in a 5GS (5th Generation System) or a terminal device in a future evolved PLMN (Public Land Mobile Network), etc., and the embodiments of the present application are not limited thereto. For the convenience of description, the above-mentioned devices are collectively referred to as terminal devices. The number of terminal devices 10 is usually multiple, and one or more terminal devices 10 may be distributed in a cell managed by each access network device 20.

[0053] The access network device 20 is a device deployed in the access network to provide wireless communication functions for the terminal device 10. The access network device 20 may include various forms of macro base stations, micro base stations, relay stations, access points, etc. In systems using different wireless access technologies, the names of devices with access network device functions may be different, for example, in the 5G NR system, they are called gNodeB or gNB. With the evolution of communication technology, the name "access network device" may change. For the convenience of description, in the embodiment of the present application, the above-mentioned devices that provide wireless communication functions for the terminal device 10 are collectively referred to as access network devices. Optionally, through the access network device 20, a communication relationship can be established between the terminal device 10 and the core network device 30. Exemplarily, in an LTE (Long Term Evolution) system, the access network device 20 may be one or more eNodeBs in EUTRAN (Evolved Universal Terrestrial Radio Access Network) or EUTRAN; in an NR system, the access network device 20 may be one or more gNBs in RAN (Radio Access Network) or RAN. In the embodiment of the present application, the network device referred to refers to the access network device 20 unless otherwise specified.

[0054] The function of the core network device 30 is mainly to provide user connection, user management and service bearing, and to provide an interface to the external network as a bearer network. For example, the core network equipment in the 5G NR system may include devices such as AMF (Access and Mobility Management Function) entity, UPF (UserPlane Function) entity and SMF (Session Management Function) entity.

[0055] In one example, the access network device 20 and the core network device 30 communicate with each other through some air interface technology, such as the NG interface in the 5G NR (New Radio) system. The access network device 20 and the terminal 10 communicate with each other through some air interface technology, such as the Uu interface.

[0056] The "5G NR system" in the embodiment of the present application may also be referred to as a 5G system or an NR system, but those skilled in the art may understand its meaning. The technical solution described in the embodiment of the present application may be applicable to a 5G NR system or to a subsequent evolution system of the 5G NR system.

[0057] The UE and the terminal device in the embodiments of the present application express the same meaning and can be replaced with each other; the network device and the access network device express the same meaning and can be replaced with each other.

[0058] Communication systems usually support the handover process of connected terminal devices. When a user who is using network services moves from one cell to another, or due to wireless transmission service load adjustment, activation operation maintenance, equipment failure, etc., in order to ensure the continuity of communication and the quality of service, the system will transfer the communication link between the user and the original cell to the new cell, that is, perform the handover process. Therefore, the terminal device can switch from the cell of the first network device to the cell of the second network device. In this case, the first network device can be called the source network device, the source access network device or the source base station, and the second network device can be called the target network device, the target access network device or the target base station.

[0059] Before introducing the technical solution of the present application, the RRC (Radio Resource Control) protocol is first introduced and explained.

[0060] The functions of the RRC protocol include: broadcasting system information, RRC connection control, inter-RAT (Radio Access Type) transfer, measurement configuration and reporting, general protocol error handling, self-configuration and self-optimization, etc.

[0061] In the NR system, the RRC state includes the RRC_CONNECTED state, the RRC_IDLE state and the RRC_INACTIVE state, where:

[0062] The RRC_IDLE state is used to control the wireless resources and wireless channels when the terminal device establishes a connection request with its own high-level configuration. The operations supported by the RRC IDLE state include: cell reselection, paging of mobile terminated data initiated by 5GC (5G CoreNetwork), paging broadcast system messages of mobile terminated data areas managed by 5GC, PLMN (Public Land Mobile Network), etc. Among them, paging is initiated by CN (Core Network) and the paging area is configured by CN. There is no UE AS (AccessStratum) context on the network device side. The terminal device in the RRC_IDLE state is characterized in that the terminal device does not retain the RRC context (RRC Context) and the terminal device does not establish an RRC connection with the network device. The RRC context includes parameters in the interface message of the terminal device, etc. The specific content of the RRC context is determined by the behavior of the terminal device and the network device. The terminal device in the RRC_IDLE state has no data to be transmitted, and it will enter a dormant state and turn off the transceiver unit to reduce power consumption. A terminal device in the RRC_IDLE state wakes up only periodically to receive possible paging messages, ie, discontinuous reception.

[0063] The RRC_CONNECTED state is used for the terminal device to establish an RRC connection with the network device and transmit data. The operations supported by the RRC_CONNECTED state include storing the AS context of the terminal device in the terminal device and the network device, and starting unicast data transmission from the terminal device. The terminal device in the RRC_CONNECTED state has established an RRC context, and all the parameters necessary for establishing communication between the terminal device and the network device are known to both communicating parties. The network device allocates a C-RNTI (Cell-Radio Network Temporary Identifier) ​​to the connected terminal device, and the terminal device and the network device are in the CM_CONNECTED (Connection Management) state together. At this time, if the terminal device is transmitting data, the terminal device is in a continuous reception state. Until the data transmission is completed and the terminal device enters the waiting state, it switches to the DRX (Discontinuous Reception) connection state to save power consumption. When the terminal device has data to be transmitted, it switches back to the continuous reception state.

[0064] RRC_INACTIVE is a new RRC state defined in the 5G NR network environment for the purpose of reducing air interface signaling overhead and quickly restoring wireless connections and data services. When the terminal device is in the RRC_INACTIVE state, the RRC context is retained between the terminal device and a network device. A network device refers to any one of all network devices that have established a connection with the terminal device, and the terminal device and the core network are in the CM_CONNECTED state. At this time, the process of the terminal device and the network device switching to the connected state for data reception is relatively fast, and no additional signaling overhead is generated, and the terminal device in the RRC_INACTIVE state will enter a sleep state to reduce power consumption.

[0065] like Figure 2 As shown, it shows a schematic diagram of the switching relationship between RRC states in the NR system.

[0066] There is a two-way switch between the RRC_IDLE state and the RRC_CONNECTED state. The RRC_IDLE state switches to the RRC_CONNECTED state by establishing a new connection, and the RRC_CONNECTED state switches to the RRC_IDLE state by releasing the resources of the terminal device. There is also a two-way switch between the RRC_INACTIVE state and the RRC_CONNECTED state. The RRC_INACTIVE state switches to the RRC_CONNECTED state by establishing a connection, and the RRC_CONNECTED state switches to the RRC_INACTIVE state by deactivation. There is no two-way switch between the RRC_IDLE state and the RRC_INACTIVE state. The RRC_INACTIVE state can switch to the RRC_IDLE state. The specific process is in the FFS (For Further Study) state.

[0067] In addition, the difference between the RRC_IDLE state, RRC_CONNECTED state and RRC_INACTIVE state also lies in the management of mobility. The mobility of the RRC_IDLE state or RRC_INACTIVE state is based on the cell reselection of the terminal device, while the mobility of the RRC_CONNECTED state is achieved by the network side based on measurement.

[0068] Please refer to Figure 3 , which shows a schematic diagram of the terminal switching process in the NR system.

[0069] When the terminal device is in a mobile state, the signal quality of the service cell may deteriorate. The terminal device connects to the cell with better signal quality through the switching process to ensure that the terminal device has continuous and uninterrupted communication services.

[0070] When a user who is using network services moves from one cell to another, or due to reasons such as wireless transmission service load adjustment, activation operation maintenance, equipment failure, etc., in order to ensure communication continuity and service quality, the system must transfer the communication link between the terminal device and the original cell to the new cell, that is, perform a switching process.

[0071] Taking the Xn interface switching process as an example, the entire switching process is divided into the following three stages.

[0072] In the handover preparation phase, the AMF provides mobility control information to the base station, and measurement control and reporting are performed between the terminal device and the source base station. After the source base station makes a handover decision based on the measurement report of the terminal device, it sends a handover request (Handover Request) to the target base station. The target base station performs admission control, and if it determines that the terminal device is allowed to handover, the target base station sends a handover request response (Handover Request Acknowledge) to the source base station.

[0073] In the handover execution phase, the RAN (Radio Access Network) handover is initiated, and the terminal device is separated from the old cell and synchronized to the new cell. The source base station sends an SN (Serial Number) status transfer to the target base station. The source base station obtains the buffered data and new data from the UPF, and then the RAN sends the user data to the target base station. The target base station caches the user data from the source base station. At this point, the RAN handover is completed.

[0074] In the handover completion phase, the target base station sends a path switch request (Path Switch Request) to the AMF, and the AMF and UPF perform path switching. After that, the UPF sends an end indication message (End Marker) to the source base station, and the source base station forwards the end indication message to the target base station. The AMF sends a path switch request response (Path Switch RequestAcknowledge) to the target base station, and the target base station instructs the source base station to release the context information of the terminal device.

[0075] for Figure 3For the handover process shown, in network implementation, the source base station can initiate handover preparation / request messages for multiple target cells simultaneously or successively (can be based on the directly connected X2 / Xn interface, or through the S1 / N2 interface between the MME (Mobility Management Entity) / AMF) according to the measurement report on the terminal device side (including the measurement results of multiple cells). After receiving the handover preparation / request message, each target cell performs access control according to its own RRM (Radio Resource Management) algorithm, and sends a handover request response message to the base station where the source cell is located on the premise of passing the access control (if the access control fails, it responds to the handover request failure message), which carries the handover command generated by the target cell. The source base station selects one as the final handover target cell from the multiple target cells that return the handover response according to its own RRM algorithm, and sends the handover command corresponding to the target cell to the terminal device through the RRC (Radio Resource Control) reconfiguration message, thereby realizing the network's complete control over the handover process.

[0076] The handover process of terminal equipment can be divided into two categories: soft handover and hard handover. Among them, hard handover is the handover process in which the terminal equipment first disconnects from the source cell and then establishes a connection with the target cell under the condition that the carrier frequencies of the source cell and the target cell are different. Soft handover is the handover process in which the terminal equipment first establishes a stable connection with the target cell and then disconnects from the source cell under the condition that the carrier frequencies of the source cell and the target cell are the same. Soft handover can reduce the occurrence of dropped calls and improve the quality of user service.

[0077] The following is an introduction to BWP in the NR system.

[0078] In the NR system, the minimum bandwidth is 5MHz and the maximum bandwidth is 400MHz. The maximum bandwidth is also called a wideband carrier. Terminal devices working on wideband carriers will consume a lot of power, and terminal devices working on wideband carriers need to have higher performance, which will increase the cost of terminal devices. The concept of BWP is introduced in the NR system. BWP is a set of continuous common resource blocks (CRBs) in a subcarrier spacing in a partial bandwidth of a carrier. Each BWP has its own different bandwidth and frequency, and its SCS (Sub-Carrier Space) and SSB (Synchronization Signal and PBCH Block) period can also be configured differently. Network equipment can allocate different BWPs to terminal devices according to their needs at different times. BWP is also called bandwidth adaptive change.

[0079] Please refer to Figure 4 , which exemplarily shows the adaptive change process of bandwidth in the NR system.

[0080] At the first moment, the service volume of the terminal device is large, and the NR system configures BWP1 with a larger bandwidth for the terminal device. At the second moment, the service volume of the terminal device is small, and the system configures BWP 2 with a smaller bandwidth for the terminal device. BWP 2 can meet the communication needs of the terminal device at this time. At the third moment, the system detects that there is selective fading of a large range of frequencies within the bandwidth where BWP 1 is located, or that resources are relatively scarce within the frequency range where BWP 1 is located, and the system configures a new bandwidth BWP 3 for the terminal device.

[0081] The BWP of the terminal device is divided into UL BWP (Uplink BWP) and DL BWP (Downlink BWP) according to the transmission direction. The network configures a maximum of 4 UL BWP and 4 DL BWP for a terminal device in the RRC_CONNECTED state. In addition, a terminal device in the RRC_CONNECTED state has a maximum of one activated ULBWP and one activated DL BWP at a time.

[0082] In a frequency division duplex system (also called a full-duplex system), two independent channels are required for communication between a terminal device and a network device. One channel is used to transmit messages downward, and the other channel is used to transmit messages upward. The two channels do not affect each other, so there is no explicit association relationship between UL BWP and DL BWP. If one of the UL BWP and DLBWP changes, the other will not be affected. For example, the network configures 4 UL BWPs with indices of 0, 1, 2, and 3 for the terminal device; the indices of the 4 DL BWPs are 0, 1, 2, and 3. At a certain moment, the index of the activated ULBWP is 0, and the index of the activated DL BWP is 1. The DL BWP is switched through a DCI (Downlink Control Information) instruction. After the switch, the index of the DL BWP becomes 2, and the index of the UL BWP is 0, which remains unchanged.

[0083] Next, the PDCCH (Physical Downlink Control Channel) configuration in the NR system is introduced.

[0084] PDCCH mainly carries the DCI information of PUSCH (Physical Uplink Control Channel) and PUSCH (Physical Uplink Share Channel). According to different scopes, PDCCH can be divided into public control information (public search space) and dedicated control information (dedicated search space). Public control information and dedicated control information define the starting position of the terminal device for blind detection and the channel search method. The terminal device listens to the PDCCH at a predetermined position in the search space for blind detection. Different terminal devices distinguish their respective PDCCHs through RNTI (Radio Network Temporary Identity) information.

[0085] The terminal device monitors the PDCCH on the PDCCH search space configured by the network. Each DL BWP of the UE is configured with up to 10 PDCCH search spaces, and each PDCCH search space is associated with a CORESET. The network can configure up to 3 CORESETs for each DLBWP of the terminal device, and configure a set of TCI states for each CORESET. At a certain moment, there can only be one active TCI state in a set of TCI states. The terminal device receives the PDCCH using the activated TCI state of the CORESET corresponding to the search space. In particular, since there is no TCI state set corresponding to the CORESET of the initial BWP, the system message broadcast or switching command will configure a CORESET#0 for the initial BWP, and the terminal device needs to monitor the PDCCH on all SSBs.

[0086] Please refer to Figure 5 , which shows the format of the terminal-specific MAC CE (MACControl Element, media access layer control unit) used to indicate the TCI state corresponding to the PDCCH.

[0087] Next, the beam management mechanism in NR is introduced.

[0088] The NR system introduces a beam management mechanism to support multi-beam operation. The beam management mechanism includes beam scanning, beam measurement, beam determination and beam reporting.

[0089] (1) Beam scanning: refers to the transmission and / or reception of a beam in a pre-set manner within a specific period or time period to cover a specific spatial area.

[0090] (2) Beam measurement: This refers to the process by which a terminal device or network device measures the quality and characteristics of the received beamforming signal. During beam management, the terminal device or network device identifies the best beam through relevant measurements.

[0091] (3) Beam determination: This refers to the terminal device or network device selecting the beam resource with the best signal quality.

[0092] (4) Beam reporting: After determining the beam resource with the best signal quality, the terminal device or network device notifies the other end of the selected beam information.

[0093] To support multi-beam operation, 5G adopts a beam management mechanism that can be used for initial access, control channels, and data channels.

[0094] The following is an introduction to RACH-less HO.

[0095] In the LTE (Long Term Evolution) system, for specific scenarios, such as when the target cell determines that the TA (Timing Advance) of the terminal device to the source cell is the same as the TA to the target cell, or the TA of the terminal device to the target cell is 0, the target cell may configure RACH-skip information in the handover command, that is, the handover process may be RACH-less HO. The RACH-skip information may include the uplink resources for the terminal device to access the target cell, so that the terminal device can send a handover completion message. If the uplink resources are not configured in the handover command, the terminal device needs to monitor the PDCCH of the target cell, wait for the target cell to schedule uplink transmission, and use the scheduled uplink resources to transmit the handover completion message.

[0096] In the LTE system, since there is no beamforming, the terminal device performs a RACH-less handover process, and the behavior of monitoring the PDCCH of the target cell is relatively simple.

[0097] In the NR system, due to the introduction of beamforming, the reception of PDCCH needs to refer to a specific SSB or CSI-RS (Channel State Information-Reference Signal), that is, the terminal device uses the activated TCI (Transmission Configuration Indicator) state of PDCCH to receive PDCCH. However, under current circumstances, the terminal device cannot determine which TCI states to use to receive PDCCH based on the switching command, which may cause the terminal device to be unable to obtain available uplink resources after switching, unable to send a switching completion message, and cause a switching failure.

[0098] The technical solution of the present application will be introduced and explained below through several exemplary embodiments.

[0099] Please refer to Figure 6 , which shows a flow chart of a PDCCH monitoring method provided by an embodiment of the present application. The method can be applied to Figure 1 In the network architecture shown in FIG. 1 , the method may include the following steps (610 to 620):

[0100] Step 610: The first network device sends a switching command to the terminal device, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device.

[0101] Correspondingly, the terminal device receives the switching command sent by the first network device.

[0102] The terminal device can be any terminal device. For example, in this application, the terminal device can be any device that can monitor PDCCH in the NR system. Of course, the technical solution of this application is not limited to the application in the NR system, but can also be applied in the LTE system or other subsequently evolved communication systems.

[0103] The first network device is a network device that establishes a connection with the terminal device. The first network device is also called a source network device or a source base station. The first cell is a physical area divided based on information such as carrier frequency and scrambling code in an area covered by a signal with the first network device as the center. The terminal device establishes a connection with the first network device in the first cell. The first network device may have at least one cell, and the first cell may be one of the at least one cell. The first cell is also called a source cell or a serving cell.

[0104] The second network device is a network device to which the terminal device is to establish a connection after executing the handover process, and is also called a target network device or a target base station. The second cell is a physical area divided based on information such as carrier frequency and scrambling code in an area covered by a signal with the second network device as the center. The second network device may have at least one cell, and the second cell may be one of the at least one cell, and the second cell is also called a target cell.

[0105] Optionally, the first network device and the second network device are two different network devices, or the first network device and the second network device may also be the same network device. For example, when the first cell and the second cell belong to the same network device, the first network device and the second network device are the same network device.

[0106] In this embodiment, for different environments, the reasons why the terminal device switches from the first cell of the first network device to the second cell of the second network device include but are not limited to: the service signal quality of the first cell is too low, the first network device fails, etc., and this application does not limit this.

[0107] Optionally, the switching command is a RACH-less switching command, and the RACH-less switching command is used to instruct the terminal device to perform a RACH-less switching process.

[0108] Optionally, the first network device sends an RRC message to the terminal device, and the terminal device receives the RRC message sent by the first network device, wherein the RRC message includes information for instructing the terminal device to perform a RACH-less switching process. Optionally, the above RRC message is an RRC reconfiguration message, which includes ReconfigurationWithSync, representing a switching command. The switching command can be generated by the second network device and forwarded by the first network device.

[0109] Optionally, the information for instructing the terminal device to perform the RACH-less switching process may be a RACH-less switching flag or RACH-skip information. The terminal device can know to perform the RACH-less switching process according to the RACH-less switching flag or RACH-skip information.

[0110] Step 620: The terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the target BWP of the second cell.

[0111] After receiving the handover command, the terminal device determines the CORESET associated with the target BWP of the second cell according to the handover command. Optionally, the target BWP of the second cell may be an initial BWP or an activated BWP or a BWP in another state. Optionally, the terminal device uses the TCI state corresponding to the CORESET associated with the target BWP to monitor the PDCCH sent by the second network device.

[0112] In an exemplary embodiment, the first network device sends a switching command generated by the second network device, the terminal device receives the switching command sent by the first network device, the terminal device determines the target BWP and its associated CORESET and / or other information based on the switching command, and determines the target receiving beam through this information, and the terminal device uses the determined target receiving beam to listen to the PDCCH sent by the second network device.

[0113] Optionally, if the terminal device monitors the PDCCH encrypted with its own C-RNTI, it obtains uplink grant information therefrom, determines the corresponding uplink resource based on the uplink grant information, and sends a handover completion message to the second network device on the determined uplink resource. Optionally, in the case where the handover command is sent using an RRC reconfiguration message, the handover completion message may be an RRC reconfiguration completion message.

[0114] To sum up, the technical solution provided in the embodiment of the present application enables the terminal device to accurately monitor the PDCCH sent by the target cell based on the CORESET associated with the target BWP of the target cell after receiving the switching command, thereby obtaining available uplink resources from the PDCCH to send a switching completion message, thereby improving the switching success rate.

[0115] Please refer to Figure 7 , which shows a flow chart of a PDCCH monitoring method provided by another embodiment of the present application. The method can be applied to Figure 1 In the network architecture shown in FIG. 1 , the method may include the following steps (710 to 720):

[0116] Step 710: The first network device sends a switching command to the terminal device, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device.

[0117] Correspondingly, the terminal device receives the switching command sent by the first network device.

[0118] Optionally, the switching command is sent in the form of an RRC message, and the first network device sends an RRC message (such as an RRC reconfiguration message) to the terminal device, and the RRC message includes the switching command (such as ReconfigurationWithSync).

[0119] Optionally, the switching command also includes information for instructing the terminal device to perform a RACH-less switching process, such as a RACH-less switching identifier or RACH-skip information.

[0120] Optionally, the switching command also includes configuration information of the activated BWP (active BWP) of the second cell, wherein the configuration information of the activated BWP is used to indicate information such as the activated BWP, at least one CORESET associated with the activated BWP, and a set of TCI states configured corresponding to each CORESET in at least one CORESET.

[0121] Optionally, the handover command also includes configuration information of an initial BWP of the second cell, wherein the configuration information of the initial BWP is used to indicate information such as the initial BWP and a CORESET associated with the initial BWP.

[0122] Step 720: The terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the initial BWP of the second cell.

[0123] In this embodiment, the target BWP is the initial BWP of the second cell. Optionally, the CORESET associated with the initial BWP is recorded as CORESET#0. Optionally, the terminal device determines the initial BWP of the second cell according to the handover command.

[0124] Optionally, when the switching command includes configuration information of the initial BWP of the second cell, the terminal device determines the initial BWP of the second cell according to the configuration information of the initial BWP of the second cell.

[0125] Optionally, when the switching command does not include configuration information of the initial BWP of the second cell, the terminal device determines the initial BWP of the first cell as the initial BWP of the second cell.

[0126] Optionally, the configuration information such as CORESET associated with the initial BWP of the second cell follows the delta configuration principle, that is, for the configuration information updated by the second cell, the second cell uses signaling for configuration; for the configuration information that is not updated in the second cell (the same configuration information as the first cell and the second cell), signaling is not used for configuration. The first network device sends a handover request to the second network device, the second network device receives the handover request, and determines the configuration information of the first cell of the first network device based on the handover request (such as the CORESET associated with the initial BWP of the first cell, etc.), the second network device compares the configuration information of the second cell with the configuration information of the first cell determined above, if there is different configuration information, the different configuration information is configured by signaling, if there is no different configuration information, it is not necessary to use signaling for configuration. The terminal device determines the configuration information such as CORESET associated with the BWP of the second cell based on the handover command, if the terminal device does not receive part of the configuration information of the second cell, the relevant configuration information of the first cell is used. If the terminal device receives the configuration information updated by the second cell, the corresponding configuration information is updated according to the signaling. The incremental configuration principle can reduce signaling consumption and ensure that the terminal device can determine the CORESET and other information associated with the initial BWP.

[0127] In addition, since the CORESET associated with the initial BWP does not have a corresponding TCI state set, in one example, when it is determined that the CORESET associated with the initial BWP of the second cell monitors the PDCCH, the terminal device uses a beam scanning method to receive the PDCCH sent by the second network device on all receiving beams of the terminal device. The above-mentioned receiving beam is also called an SSB beam, which refers to the beam used to receive the SSB.

[0128] Since the bandwidth of the initial BWP and the CORESET associated with it is relatively small, and the bandwidth of the low-frequency band and the mid-frequency band in the network is limited, when the terminal device uses all receiving beams to monitor the PDCCH sent by the second network device, there may be some limitations in network scheduling. In another exemplary embodiment, when it is determined that the CORESET associated with the initial BWP based on the second cell monitors the PDCCH, the terminal device determines at least one target receiving beam from all receiving beams of the terminal device according to the beam measurement result, and uses the target receiving beam to receive the PDCCH sent by the second network device.

[0129] The terminal device obtains a beam measurement result through a beam scanning and measurement process. The terminal device selects one or more target receiving beams based on the beam measurement result, and uses the selected target receiving beams to monitor the PDCCH sent by the second network device.

[0130] The terminal device can determine the target receiving beam for monitoring the PDCCH sent by the second network device in the beam measurement result through some selection criteria. Optionally, the criterion for the terminal device to select the target receiving beam through the beam measurement result is to select the first n beams with the best signal quality as the target receiving beam, where n is a positive integer. Optionally, the criterion for the terminal device to select the target receiving beam through the beam measurement result is to set a signal quality threshold X, and the terminal device determines all beams with signal quality exceeding X in the beam measurement result as the target receiving beam. In addition, please refer to the above description for the specific process of beam scanning and beam measurement, which will not be repeated here.

[0131] In one embodiment, the first network device forwards the switching command generated by the second network device, the terminal device receives the switching command and determines the CORESET associated with the initial BWP of the second cell based on the switching command, the terminal device selects a receiving beam with the best signal quality as the target receiving beam according to the beam measurement result, and the terminal device uses the target receiving beam to monitor the PDCCH sent by the second network device.

[0132] In another embodiment, the first network device forwards a switching command generated by the second network device, the terminal device receives the switching command and determines the CORESET associated with the initial BWP of the second cell based on the switching command, the terminal device selects several beams with signal quality higher than a certain threshold as target receiving beams according to the beam measurement results, and the terminal device uses these target receiving beams to monitor the PDCCH sent by the second network device.

[0133] In summary, in the technical solution provided by this embodiment, the terminal device monitors the PDCCH based on the CORESET associated with the initial BWP of the target cell, which can reduce the modification of the RRC message.

[0134] In addition, the terminal device determines the target receiving beam through the beam measurement results and uses the determined target receiving beam to monitor the PDCCH sent by the second network device. Compared with the terminal device using all receiving beams to monitor the PDCCH, this helps to reduce the energy consumption of the terminal device's monitoring process and achieve the purpose of terminal power saving.

[0135] The above embodiment introduces that the terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the initial BWP of the second cell. In some other embodiments, the terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the activated BWP of the second cell. Figure 8 and Fig. 9 Two embodiments are used to illustrate this.

[0136] Please refer to Figure 8 , which shows a flowchart of a PDCCH monitoring method provided by another embodiment of the present application. The method can be applied to Figure 1 In the network architecture shown, the method may include the following steps (810-820):

[0137] Step 810: The first network device sends a switching command to the terminal device, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device.

[0138] Correspondingly, the terminal device receives the switching command sent by the first network device.

[0139] Optionally, the switching command is sent in the form of an RRC message, and the first network device sends an RRC message (such as an RRC reconfiguration message) to the terminal device, and the RRC message includes the switching command (such as ReconfigurationWithSync).

[0140] Optionally, the switching command also includes information for instructing the terminal device to perform a RACH-less switching process, such as a RACH-less switching identifier or RACH-skip information.

[0141] Optionally, the switching command also includes configuration information of the activated BWP (active BWP) of the second cell, wherein the configuration information of the activated BWP is used to indicate information such as the activated BWP, at least one CORESET associated with the activated BWP, and a set of TCI states configured corresponding to each CORESET in at least one CORESET.

[0142] Optionally, the handover command also includes configuration information of an initial BWP of the second cell, wherein the configuration information of the initial BWP is used to indicate information such as the initial BWP and a CORESET associated with the initial BWP.

[0143] Step 820: The terminal device uses a TCI state set configured corresponding to at least one CORESET associated with the activated BWP of the second cell to monitor the PDCCH sent by the second network device.

[0144] In this embodiment, the target BWP is the activated BWP of the second cell. Optionally, the terminal device determines the activated BWP of the second cell based on the handover command. For example, the terminal device determines the activated BWP, at least one CORESET associated with the activated BWP, and a set of TCI states corresponding to each CORESET in the at least one CORESET, based on the configuration information of the activated BWP of the second cell contained in the handover command.

[0145] In one example, the behavior of the terminal device using the above-configured TCI state set to monitor the PDCCH is agreed upon by the protocol. For example, if the handover command contains the configuration information of the activation BWP of the second cell, the terminal device uses the configured TCI state set to monitor the PDCCH. Conversely, if the handover command does not contain the configuration information of the activation BWP of the second cell, the terminal device cannot use the configured TCI state set to monitor the PDCCH.

[0146] In another example, the behavior of the terminal device using the above-configured TCI state set to monitor PDCCH is configured by the network. Optionally, the switching command also includes first information, and the first information is used to indicate that the terminal device uses or does not use the configured TCI state set to monitor PDCCH. If the first information in the switching command indicates that the terminal device uses the configured TCI state set to monitor PDCCH, the terminal device uses the configured TCI state set to monitor PDCCH. If the first information in the switching command indicates that the terminal device does not use the configured TCI state set to monitor PDCCH, the terminal device does not use the configured TCI state set to monitor PDCCH. The above-mentioned first information can be represented by 1 bit, for example, 1 represents use, 0 represents not use, or 1 represents not use, and 0 represents use.

[0147] In addition, since the number of CORESETs associated with the activated BWP of the second cell can be one or more. When the number of CORESETs associated with the activated BWP is one, the terminal device uses the TCI state set configured corresponding to this CORESET to monitor the PDCCH sent by the second network device. When the number of CORESETs associated with the activated BWP is multiple (such as n, where n is an integer greater than 1), the terminal device can use the TCI state sets configured corresponding to all of the n CORESETs to monitor the PDCCH sent by the second network device, or use the TCI state sets configured corresponding to some of the n CORESETs to monitor the PDCCH sent by the second network device. If the terminal device uses the TCI state sets configured corresponding to some of the n CORESETs to monitor the PDCCH sent by the second network device, the method of determining some of the CORESETs from the n CORESETs may depend on the implementation of the terminal device, or may be indicated by the network device, for example, including the indication information corresponding to the some of the CORESETs in the switching command.

[0148] Optionally, in order to assist the second cell in configuring a suitable TCI state set, the terminal device may carry the beam measurement results of the second cell in the measurement report sent to the first cell. The first cell may forward these beam measurement results to the second cell when a switching request is made. This may assist the second cell in configuring a suitable TCI state set, such as selecting several beams with better beam measurement results as the configured TCI states.

[0149] To sum up, the technical solution provided in this embodiment is that the terminal device uses the TCI state set configured corresponding to at least one CORESET associated with the activated BWP of the target cell to monitor the PDCCH sent by the target cell, which can avoid the terminal device monitoring the PDCCH on all receiving beams, thereby achieving the purpose of power saving for the terminal device.

[0150] In addition, the solution of this embodiment is equivalent to activating the TCI state configuration configured in the switching command, so if the network device wants to use other TCI states later, it needs to be added through the RRC reconfiguration message.

[0151] Please refer to Fig. 9 , which shows a flowchart of a PDCCH monitoring method provided by another embodiment of the present application. The method can be applied to Figure 1 In the network architecture shown, the method may include the following steps (910-920):

[0152] Step 910: The first network device sends a switching command to the terminal device, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device.

[0153] Correspondingly, the terminal device receives the switching command sent by the first network device.

[0154] Optionally, the switching command is sent in the form of an RRC message, and the first network device sends an RRC message (such as an RRC reconfiguration message) to the terminal device, and the RRC message includes the switching command (such as ReconfigurationWithSync).

[0155] Optionally, the switching command also includes information for instructing the terminal device to perform a RACH-less switching process, such as a RACH-less switching identifier or RACH-skip information.

[0156] Optionally, the switching command also includes configuration information of the activated BWP (active BWP) of the second cell, wherein the configuration information of the activated BWP is used to indicate information such as the activated BWP, at least one CORESET associated with the activated BWP, and a set of TCI states configured corresponding to each CORESET in at least one CORESET.

[0157] Optionally, the handover command also includes configuration information of an initial BWP of the second cell, wherein the configuration information of the initial BWP is used to indicate information such as the initial BWP and a CORESET associated with the initial BWP.

[0158] Step 920: The terminal device uses at least one TCI state activated corresponding to at least one CORESET associated with the activated BWP of the second cell to monitor the PDCCH sent by the second network device.

[0159] Optionally, the switching command also includes second information, where the second information is used to indicate at least one activated TCI state.

[0160] Optionally, the second information includes a bit sequence, and each bit in the bit sequence is used to indicate whether a corresponding TCI state is activated or inactivated. For example, the bit sequence A1 contains 4 bits, wherein a bit position value of 0 indicates that the corresponding TCI state is inactivated, and a bit position value of 1 indicates that the corresponding TCI state is activated. If the content of the A1 sequence is (0, 0, 0, 1), the TCI state indexed as 3 in the bit sequence A1 is an activated state. For another example, the bit sequence A2 contains 5 bits, wherein a bit position value of 0 indicates that the corresponding TCI state is activated, and a bit position value of 1 indicates that the corresponding TCI state is activated. If the content of the A2 sequence is (1, 0, 1, 1, 1), the TCI state indexed as 1 in the bit sequence A2 is an activated state. In the above example, the indexes are numbered sequentially from 0 downwards.

[0161] Optionally, each CORESET has independently corresponding second information, or there are at least two CORESETs sharing the same second information.

[0162] In an exemplary embodiment, it is assumed that the activated BWP of the second cell is associated with two CORESETs (denoted as CORESET#1 and CORESET#2), and these two CORESETs share the same second information. Taking the second information as a bit sequence as an example, assuming that the second information is (1, 0, 0, 0), where 1 indicates activation and 0 indicates inactivation, it means activating the first TCI state in the TCI state set corresponding to CORESET#1 and activating the first TCI state in the TCI state set corresponding to CORESET#2. The terminal device uses these two activated TCI states to monitor the PDCCH sent by the second network device.

[0163] In another exemplary embodiment, it is assumed that the activated BWP of the second cell is associated with two CORESETs (denoted as CORESET#1 and CORESET#2), and these two CORESETs have independently corresponding second information. Taking the second information as a bit sequence as an example, it is assumed that the second information corresponding to CORESET#1 is (1, 0, 0, 0), and the second information corresponding to CORESET#2 is (0, 1, 0, 1), where 1 indicates activation and 0 indicates inactivation. This means that the first TCI state in the TCI state set corresponding to CORESET#1 is activated, and the second and fourth TCI states in the TCI state set corresponding to CORESET#2 are activated. The terminal device uses the above three activated TCI states to monitor the PDCCH sent by the second network device.

[0164] The description of the bit sequence in the above exemplary embodiments is for illustrative purposes only and does not limit the format of the bit sequence.

[0165] Optionally, in order to assist the second cell in activating a suitable TCI state set, the terminal device may carry the beam measurement results of the second cell in the measurement report sent to the first cell. The first cell may forward these beam measurement results to the second cell when a switching request is made. This may assist the second cell in activating a suitable TCI state set, such as selecting several beams with better beam measurement results as activated TCI states.

[0166] To sum up, the technical solution provided in this embodiment is that the terminal device uses at least one TCI state activated corresponding to at least one CORESET associated with the activated BWP of the target cell to monitor the PDCCH sent by the target network device, which can avoid the terminal device monitoring the PDCCH on all receiving beams, thereby achieving the purpose of power saving for the terminal device.

[0167] In addition, compared with the embodiment Figure 8 An advantage of the implementation scheme is that the TCI state can be configured once, and if the network device subsequently wants to activate other TCI states, it can activate them through MAC CE without adding the corresponding TCI state through RRC reconfiguration message.

[0168] Please refer to Fig.10 , which shows a flowchart of a PDCCH monitoring method provided by another embodiment of the present application. The method can be applied to Figure 1 In the network architecture shown, the method may include the following steps (1010-1020):

[0169] Step 1010: The second network device sends a switching command to the first network device, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device.

[0170] Step 1020: The second network device sends a PDCCH at the target BWP, wherein the terminal device monitors the PDCCH based on the CORESET associated with the target BWP.

[0171] In one example, the target BWP is the initial BWP of the second cell. For the description of the terminal device monitoring the PDCCH based on the CORESET associated with the initial BWP of the second cell, please refer to the above embodiment, which will not be repeated here.

[0172] In another example, the target BWP is the activated BWP of the second cell. For the description of the terminal device monitoring the PDCCH based on the CORESET associated with the activated BWP of the second cell, please refer to the above embodiment, which will not be repeated here.

[0173] In an exemplary embodiment, the target BWP may be determined by the second network device, that is, the second network device determines whether the target BWP is an initial BWP or an activated BWP.

[0174] Optionally, the second network device determines, based on reference information, that the target BWP is an initial BWP of the second cell or an activated BWP of the second cell; wherein the reference information includes at least one of the following: service demand, BWP load, and terminal type.

[0175] The second network device can determine the target BWP according to the service demand. Since the bandwidth corresponding to the initial BWP is small and the service volume that can be carried is small, when the service demand is small, the second network device will determine the initial BWP as the target BWP; conversely, when the service demand is large, the second network device will determine the activated BWP as the target BWP.

[0176] The BWP load can be measured to a certain extent by the number of terminal devices using the BWP. Optionally, the second network device determines the BWP with a smaller load as the target BWP by comparing the load of the initial BWP with the load of the activated BWP. For example, the number of terminal devices using the initial BWP is 3, and the number of terminal devices using the activated BWP is 30. At this time, the load of the initial BWP is smaller, and the second network device determines the initial BWP as the target BWP.

[0177] Exemplarily, the terminal type is distinguished according to the maximum transmit power of the terminal device. According to the maximum transmit power, the terminal device can be divided into the first type of terminal device (also called low-power terminal device, such as RedCap terminal device) and the second type of terminal device (also called ordinary terminal device). The maximum transmit power of the low-power terminal device is very small, the data transmission rate is slow, and the initial BWP with a smaller bandwidth can meet its needs. For example, the transmit power of the low-power terminal device is lower than 20dBm; the maximum transmit power of the ordinary terminal device is relatively large, and the data transmission rate is fast, so a larger bandwidth is required for data transmission. When the second network device determines that the terminal device is a low-power terminal device, the initial BWP is determined as the target BWP. On the contrary, when the terminal device is determined to be an ordinary terminal device, the activated BWP is determined as the target BWP. For example, the second network device determines that the maximum transmit power of the terminal device is 15dBm through the switching request sent by the first network device, and the terminal device is a low-power terminal device. The second network device determines the initial BWP as the target BWP.

[0178] Optionally, the handover command includes third information, and the third information is used to instruct the terminal device to monitor the PDCCH based on the CORESET associated with the initial BWP of the second cell, or to monitor the PDCCH based on the CORESET associated with the activated BWP of the second cell.

[0179] After the second network device determines the type of the target BWP, the third information may be configured in the handover command to indicate the target BWP used by the terminal device to monitor the PDCCH. If the third information in the handover command indicates that the terminal device uses the CORESET associated with the initial BWP to monitor the PDCCH, the terminal device uses the CORESET associated with the initial BWP to monitor the PDCCH; if the third information in the handover command indicates that the terminal device uses the CORESET associated with the activated BWP to monitor the PDCCH, the terminal device uses the CORESET associated with the activated BWP to monitor the PDCCH. Optionally, the third information may be represented by 1 bit, such as 0 indicating that the second network device instructs the terminal device to use the CORESET associated with the initial BWP to monitor the PDCCH, and 1 indicating that the second network device instructs the terminal device to use the CORESET associated with the activated BWP to monitor the PDCCH.

[0180] In an exemplary embodiment, the number of terminal devices connected to the initial BWP of the second cell is 10, and the number of terminal devices connected to the activated BWP is 2. The second network device determines that the load of the activated BWP is small, determines the activated BWP as the target BWP, and writes the relevant configuration and third information of the activated BWP in the switching command, wherein the third information is a bit character with a value of 1, and the third information is used to instruct the terminal device to use the CORESET associated with the activated BWP of the second cell to monitor the PDCCH.

[0181] Optionally, when it is determined that the target BWP is the activated BWP of the second cell, the configuration information of the activated BWP of the second cell is added to the switching command; or, when it is determined that the target BWP is the initial BWP of the second cell, the configuration information of the activated BWP of the second cell is not added to the switching command.

[0182] If the second network device determines that the target BWP is the activated BWP of the second cell, the second network device configures the relevant information of the activated BWP in the handover command, and the relevant information of the activated BWP includes at least one or more TCI state sets corresponding to the CORESET associated with the activated BWP. In addition, the relevant information of the activated BWP may also include the first information and / or the second information described above. If the second network device determines that the target BWP is the initial BWP of the second cell, the second network device does not add the configuration information of the activated BWP of the second cell in the handover command. Optionally, in the case where the configuration information of the activated BWP of the second cell is not added in the handover command, the second network device adds the configuration information of the initial BWP of the second cell in the handover command, and the terminal device determines the initial BWP of the second cell based on the configuration information of the initial BWP in the handover command, and uses the CORESET associated with the initial BWP to monitor the PDCCH sent by the second network device. Optionally, when the configuration information of the activated BWP of the second cell is not added in the switching command, the second network device also does not add the configuration information of the initial BWP of the second cell in the switching command. After the terminal device receives the switching command, it finds that there is no initial BWP or activation BWP configuration information in the switching command. According to the incremental configuration principle, the terminal device determines the initial BWP of the first cell as the initial BWP of the second cell, and uses the CORESET associated with the initial BWP to monitor the PDCCH sent by the second network device.

[0183] For example, the second network device determines through the switching request sent by the first network device that the maximum transmission power of the terminal device is 31dBm, and the terminal device is an ordinary terminal device. The second network device determines the activated BWP as the target BWP, and adds the configuration information of the activated BWP of the second cell in the switching command. The terminal device monitors PDCCH through the CORESET associated with the activated BWP of the second cell.

[0184] For another example, when the second network device determines that the service demand is small and determines the initial BWP as the target BWP, and determines that the target BWP is the initial BWP of the second cell, the configuration information of the activation BWP of the second cell is not added to the handover command, and the configuration information of the initial BWP is not added to the handover command. After receiving the handover command, the terminal device determines that the handover command does not contain the configuration information of the activation BWP and determines that the handover command does not contain the configuration information of the initial BWP. The terminal device uses the configuration information of the initial BWP of the first cell as the initial BWP information of the second cell, and the terminal device uses the CORESET associated with the initial BWP to monitor the PDCCH sent by the second terminal device.

[0185] For the specific process of the first network device forwarding the switching command and the terminal device using the configuration information of the target BWP to monitor the PDCCH in the above embodiment, please refer to the embodiment on the terminal device side, which will not be repeated here.

[0186] It should be noted that the description of reference information such as service requirements, BWP load, terminal type and third information in the above exemplary embodiments is only for illustrative purposes and does not limit the form and content of the above information.

[0187] To sum up, the technical solution provided by the embodiment of the present application generates a switching command through the second network device, and the first network device forwards the switching command. After receiving the switching command, the terminal device monitors the PDCCH sent by the target cell based on the CORESET associated with the target BWP of the target cell, so that the terminal device can accurately monitor the PDCCH, thereby obtaining available uplink resources from the PDCCH to send a switching completion message, thereby improving the switching success rate.

[0188] In addition, this embodiment provides a method for the second network device to determine the target BWP through reference information. The second network device can flexibly determine the target BWP through reference information, which helps to reasonably utilize BWP resources and enables the terminal device to match the target BWP in the switching command.

[0189] It should be noted that the above only introduces and illustrates the technical solution of the present application from the perspective of the interaction between the terminal device, the first network device and the second network device. The above steps executed by the terminal device can be independently implemented as a PDCCH monitoring method on the terminal device side, the above steps executed by the first network device can be independently implemented as a PDCCH monitoring method on the first network device side, and the above steps executed by the second network device can be independently implemented as a PDCCH monitoring method on the second network device side.

[0190] The following is an embodiment of the device of the present application, which can be used to execute the embodiment of the method of the present application. For details not disclosed in the embodiment of the device of the present application, please refer to the embodiment of the method of the present application.

[0191] refer to Fig.11 , which shows a block diagram of a PDCCH monitoring device provided by an embodiment of the present application. The device has the function of implementing the method example on the terminal device side, which can be implemented by hardware or by hardware executing corresponding software. The device can be the terminal device described above, or it can be set in the terminal device. Fig.11 As shown, the device 1100 may include: a receiving module 1110 and a monitoring module 1120 .

[0192] The receiving module 1110 is used to receive a switching command sent by the first network device, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device.

[0193] The monitoring module 1120 is configured to monitor the PDCCH sent by the second network device based on the control resource set CORESET associated with the target bandwidth part BWP of the second cell.

[0194] Optionally, the target BWP is an initial BWP of the second cell.

[0195] Optionally, the monitoring module 1120 is used to receive the PDCCH sent by the second network device on all receiving beams of the terminal device using a beam scanning method when it is determined that the CORESET associated with the initial BWP of the second cell monitors the PDCCH.

[0196] Optionally, the monitoring module 1120 is used to determine at least one target receiving beam from all receiving beams of the terminal device according to the beam measurement result when determining that the CORESET associated with the initial BWP of the second cell monitors the PDCCH, and receive the PDCCH sent by the second network device on the target receiving beam.

[0197] Optionally, the device 1100 further includes a determination module ( Fig.11 (not shown), the determination module is used to determine the initial BWP of the second cell according to the configuration information of the initial BWP of the second cell when the switching command contains the configuration information of the initial BWP of the second cell; or, when the switching command does not contain the configuration information of the initial BWP of the second cell, determine the initial BWP of the first cell as the initial BWP of the second cell.

[0198] Optionally, the target BWP is an activated BWP of the second cell.

[0199] Optionally, the switching command includes configuration information of the activated BWP of the second cell; wherein the configuration information of the activated BWP is used to indicate the activated BWP, at least one CORESET associated with the activated BWP, and a set of TCI states configured corresponding to each CORESET in the at least one CORESET.

[0200] Optionally, the monitoring module 1120 is used to monitor the PDCCH sent by the second network device using a TCI state set configured corresponding to at least one CORESET associated with the activated BWP of the second cell.

[0201] Optionally, the behavior of the terminal device using the configured TCI state set to monitor PDCCH is agreed upon by the protocol.

[0202] Optionally, if the switching command includes configuration information of activating BWP of the second cell, the terminal device uses the configured TCI state set to monitor PDCCH.

[0203] Optionally, the behavior of the terminal device monitoring PDCCH using the configured TCI state set is configured by the network.

[0204] Optionally, the switching command also includes first information, and the first information is used to indicate that the terminal device uses or does not use the configured TCI state set to monitor the PDCCH.

[0205] Optionally, the monitoring module 1120 is used to monitor the PDCCH sent by the second network device using at least one TCI state activated corresponding to at least one CORESET associated with the activated BWP of the second cell.

[0206] Optionally, the switching command also includes second information, where the second information is used to indicate at least one activated TCI state.

[0207] Optionally, the second information includes a bit sequence, and each bit in the bit sequence is used to indicate whether a corresponding TCI state is activated or inactivated.

[0208] Optionally, each CORESET has independently corresponding second information, or there are at least two CORESETs sharing the same second information.

[0209] Optionally, the switching command is a RACH-less switching command, and the RACH-less switching command is used to instruct the terminal device to perform a RACH-less switching process.

[0210] Optionally, the receiving module 1110 is used to receive a radio resource control RRC message sent by the first access network device, where the RRC message includes information for instructing the terminal device to perform a RACH-less switching process.

[0211] Optionally, the switching command includes third information, and the third information is used to instruct the terminal device to monitor the PDCCH based on the CORESET associated with the initial BWP of the second cell, or to monitor the PDCCH based on the CORESET associated with the activated BWP of the second cell.

[0212] Optionally, when the handover command includes configuration information of the activated BWP of the second cell, the terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the activated BWP of the second cell;

[0213] Alternatively, when the switching command does not include the configuration information of the activated BWP of the second cell, the terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the initial BWP of the second cell.

[0214] Optionally, the second network device determines that the target BWP is an initial BWP of the second cell or an activated BWP of the second cell based on reference information; wherein the reference information includes at least one of the following: service requirements, BWP load, and terminal type.

[0215] To sum up, the technical solution provided in this embodiment is that after the terminal device receives the switching command, it monitors the PDCCH sent by the target cell based on the CORESET associated with the target BWP of the target cell, so that the terminal device can accurately monitor the PDCCH, thereby obtaining available uplink resources from the PDCCH to send a switching completion message, thereby improving the switching success rate.

[0216] refer to Fig.12 , which shows a block diagram of a PDCCH monitoring device provided by another embodiment of the present application. The device has the function of implementing the method example on the first network device side mentioned above, and the function can be implemented by hardware, or by hardware executing corresponding software. The device can be the first network device introduced above, or it can be set in the first network device. Fig.12 As shown, the device 1200 may include: a sending module 1210.

[0217] The sending module 1210 is used to send a handover command to the terminal device, where the handover command is used to instruct the terminal device to handover from the first cell corresponding to the first network device to the second cell corresponding to the second network device;

[0218] The terminal device monitors the PDCCH sent by the second network device based on the control resource set CORESET associated with the target bandwidth part BWP of the second cell.

[0219] Optionally, the target BWP is an initial BWP of the second cell.

[0220] Optionally, the terminal device uses a beam scanning method to receive the PDCCH sent by the second network device on all receiving beams of the terminal device.

[0221] Optionally, the terminal device determines at least one target receiving beam from all receiving beams of the terminal device according to the beam measurement result, and receives the PDCCH sent by the second network device on the target receiving beam.

[0222] Optionally, when the switching command includes configuration information of the initial BWP of the second cell, the terminal device determines the initial BWP of the second cell based on the configuration information of the initial BWP of the second cell; or, when the switching command does not include configuration information of the initial BWP of the second cell, the terminal device determines the initial BWP of the first cell as the initial BWP of the second cell.

[0223] Optionally, the target BWP is an activated BWP of the second cell.

[0224] Optionally, the switching command includes configuration information of activating the BWP of the second cell; wherein the configuration information of activating the BWP is used to indicate the activation of the BWP, at least one CORESET associated with the activation of the BWP, and a set of transmission configuration indication TCI states configured corresponding to each CORESET in at least one CORESET.

[0225] Optionally, the terminal device uses a TCI state set configured corresponding to at least one CORESET associated with the activated BWP of the second cell to monitor the PDCCH sent by the second network device.

[0226] Optionally, the behavior of the terminal device to monitor PDCCH using the configured TCI state set is agreed upon by the protocol.

[0227] Optionally, if the switching command includes configuration information for activating the BWP of the second cell, the terminal device uses the configured TCI state set to monitor the PDCCH.

[0228] Optionally, the behavior of the terminal device to monitor PDCCH using the configured TCI state set is configured by the network.

[0229] Optionally, the switching command also includes first information, and the first information is used to instruct the terminal device to use or not use the configured TCI state set to monitor the PDCCH.

[0230] Optionally, the terminal device uses at least one TCI state activated corresponding to at least one CORESET associated with the activated BWP of the second cell to monitor the PDCCH sent by the second network device.

[0231] Optionally, the switching command also includes second information, where the second information is used to indicate at least one activated TCI state.

[0232] Optionally, the second information includes a bit sequence, and each bit in the bit sequence is used to indicate whether a corresponding TCI state is activated or inactivated.

[0233] Optionally, each CORESET has independently corresponding second information, or there are at least two CORESETs sharing the same second information.

[0234] Optionally, the switching command is a RACH-less switching command, and the RACH-less switching command is used to instruct the terminal device to perform a RACH-less switching process.

[0235] Optionally, the sending module 1210 is used to send a radio resource control RRC message to the terminal device, where the RRC message includes information for instructing the terminal device to perform a RACH-less switching process.

[0236] To sum up, the technical solution provided in the embodiment of the present application enables the terminal device to accurately monitor the PDCCH sent by the target cell based on the CORESET associated with the target BWP of the target cell after receiving the switching command, thereby obtaining available uplink resources from the PDCCH to send a switching completion message, thereby improving the switching success rate.

[0237] refer to Fig.13 , which shows a block diagram of a PDCCH monitoring device provided by another embodiment of the present application. The device has the function of implementing the method example of the second network device side mentioned above, and the function can be implemented by hardware, or by hardware executing corresponding software. The device can be the second network device introduced above, or it can be set in the second network device. Fig.13 As shown, the device 1300 may include: a sending module 1310.

[0238] The sending module 1310 is used to send a switching command to the first network device, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device;

[0239] The sending module 1310 is further configured to send a PDCCH in a target bandwidth part BWP, wherein the terminal device monitors the PDCCH based on a control resource set CORESET associated with the target BWP.

[0240] Optionally, the target BWP is an initial BWP of the second cell.

[0241] Optionally, the switching command includes configuration information of the activated BWP of the second cell; wherein the configuration information of the activated BWP is used to indicate the activated BWP, at least one CORESET associated with the activated BWP, and a set of transmission configuration indication TCI states configured corresponding to each CORESET in the at least one CORESET.

[0242] Optionally, the terminal device uses a TCI state set configured corresponding to at least one CORESET associated with the activated BWP of the second cell to monitor the PDCCH sent by the second network device.

[0243] Optionally, if the switching command includes configuration information of activating BWP of the second cell, the terminal device uses the configured TCI state set to monitor PDCCH.

[0244] Optionally, the switching command also includes first information, and the first information is used to indicate that the terminal device uses or does not use the configured TCI state set to monitor the PDCCH.

[0245] Optionally, the terminal device uses at least one TCI state activated corresponding to at least one CORESET associated with the activated BWP of the second cell to monitor the PDCCH sent by the second network device.

[0246] Optionally, the switching command also includes second information, and the second information is used to indicate the at least one activated TCI state.

[0247] Optionally, the second information includes a bit sequence, and each bit in the bit sequence is used to indicate whether a corresponding TCI state is activated or inactivated.

[0248] Optionally, each CORESET has independently corresponding second information;

[0249] or,

[0250] There are at least two CORESETs that share the same second information.

[0251] Optionally, the switching command is a RACH-less switching command, and the RACH-less switching command is used to instruct the terminal device to perform a RACH-less switching process.

[0252] Optionally, the device further includes a determination module ( Fig.13 (not shown) for:

[0253] The target BWP is determined to be an initial BWP of the second cell or an activated BWP of the second cell according to reference information; wherein the reference information includes at least one of the following: service demand, BWP load, and terminal type.

[0254] Optionally, the switching command includes third information, and the third information is used to instruct the terminal device to monitor the PDCCH based on the CORESET associated with the initial BWP of the second cell, or to monitor the PDCCH based on the CORESET associated with the activated BWP of the second cell.

[0255] Optionally, the device further comprises an adding module ( Fig.13 ), for:

[0256] In a case where it is determined that the target BWP is the activated BWP of the second cell, adding configuration information of the activated BWP of the second cell to the handover command;

[0257] or,

[0258] In a case where it is determined that the target BWP is the initial BWP of the second cell, configuration information of the activated BWP of the second cell is not added to the handover command.

[0259] To sum up, the technical solution provided in the embodiment of the present application enables the terminal device to accurately monitor the PDCCH sent by the target cell based on the CORESET associated with the target BWP of the target cell after receiving the switching command, thereby obtaining available uplink resources from the PDCCH to send a switching completion message, thereby improving the switching success rate.

[0260] One point that needs to be explained is that the device provided in the above embodiment only uses the division of the above-mentioned functional modules as an example to implement its functions. In actual applications, the above-mentioned functions can be assigned to different functional modules according to actual needs, that is, the content structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0261] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0262] Please refer to Fig.14, which shows a block diagram of a terminal device 140 provided by an embodiment of the present application. For example, the terminal device 140 may be used to execute the PDCCH monitoring method on the terminal device side. Specifically, the terminal device 140 may include a processor 141, a receiver 142, a transmitter 143, a memory 144, and a bus 145.

[0263] The processor 141 includes one or more processing cores. The processor 141 executes various functional applications and information processing by running software programs and modules.

[0264] The receiver 142 and the transmitter 143 may be implemented as a transceiver 146 , which may be a communication chip.

[0265] The memory 144 is connected to the processor 141 via a bus 145 .

[0266] The memory 144 may be used to store a computer program, and the processor 141 may be used to execute the computer program to implement each step performed by the terminal device in the above method embodiment.

[0267] In addition, the memory 144 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, and the volatile or non-volatile storage device includes but is not limited to: RAM (Random-Access Memory) and ROM (Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory or other solid-state storage technology, CD-ROM (Compact Disc Read-Only Memory), DVD (Digital Video Disc) or other optical storage, tape cassettes, magnetic tapes, disk storage or other magnetic storage devices.

[0268] Optionally, the transceiver 146 is used to receive a switching command sent by a first network device, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to a second network device.

[0269] The transceiver 146 is further configured to monitor the PDCCH sent by the second network device based on the CORESET associated with the target BWP of the second cell.

[0270] For details not described in detail in the above embodiments, please refer to the introduction in the above method embodiments, which will not be repeated here.

[0271] Please refer to Fig.15 , which shows a structural block diagram of a network device 150 provided by an embodiment of the present application. For example, the network device 150 can be used to execute the PDCCH monitoring method on the first network device side or the second network device side. Specifically: the network device 150 may include: a processor 151, a receiver 152, a transmitter 153, a memory 154 and a bus 155.

[0272] The processor 151 includes one or more processing cores. The processor 151 executes various functional applications and information processing by running software programs and modules.

[0273] The receiver 152 and the transmitter 153 may be implemented as a transceiver 156 , which may be a communication chip.

[0274] The memory 154 is connected to the processor 151 via a bus 155 .

[0275] The memory 154 may be used to store a computer program, and the processor 151 may be used to execute the computer program to implement each step performed by the first network device or the second network device in the above method embodiment.

[0276] In addition, the memory 154 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, and the volatile or non-volatile storage device includes but is not limited to: RAM (Random-Access Memory) and ROM (Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory or other solid-state storage technology, CD-ROM (Compact Disc Read-Only Memory), DVD (Digital Video Disc) or other optical storage, tape cassettes, magnetic tapes, disk storage or other magnetic storage devices.

[0277] In an exemplary embodiment, when the network device 150 is a first network device, the transceiver 156 is used to send a switching command to a terminal device, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to a second network device;

[0278] The terminal device monitors the PDCCH sent by the second network device based on the CORESET associated with the target BWP of the second cell.

[0279] In an exemplary embodiment, when the network device 150 is a second network device, the transceiver 156 is used to send a switching command, where the switching command is used to instruct the terminal device to switch from a first cell corresponding to the first network device to a second cell corresponding to the second network device;

[0280] The transceiver 156 is further configured to send a PDCCH in a target bandwidth part BWP, wherein the terminal device monitors the PDCCH based on a control resource set CORESET associated with the target BWP.

[0281] Optionally, the processor 151 is used to determine, based on reference information, that the target BWP is an initial BWP of the second cell or an activated BWP of the second cell; wherein the reference information includes at least one of the following: service demand, BWP load, and terminal type.

[0282] For details not described in detail in the above embodiments, please refer to the introduction in the above method embodiments, which will not be repeated here.

[0283] An embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored. The computer program is used to be executed by a processor of a device to implement the above-mentioned PDCCH monitoring method.

[0284] Optionally, the computer readable storage medium may include: ROM (Read-Only Memory), RAM (Random-Access Memory), SSD (Solid State Drives) or optical disks, etc. Among them, the random access memory may include ReRAM (Resistance Random Access Memory) and DRAM (Dynamic Random Access Memory).

[0285] An embodiment of the present application further provides a chip, which includes a programmable logic circuit and / or program instructions. When the chip runs on a device, it is used to implement the above-mentioned PDCCH monitoring method.

[0286] An embodiment of the present application also provides a computer program product or a computer program, wherein the computer program product or the computer program includes computer instructions, wherein the computer instructions are stored in a computer-readable storage medium, and the processor of the device reads and executes the computer instructions from the computer-readable storage medium to implement the above-mentioned PDCCH monitoring method.

[0287] It should be understood that the "indication" mentioned in the embodiments of the present application can be a direct indication, an indirect indication, or an indication of an association relationship. For example, A indicates B, which can mean that A directly indicates B, for example, B can be obtained through A; it can also mean that A indirectly indicates B, for example, A indicates C, and B can be obtained through C; it can also mean that there is an association relationship between A and B.

[0288] In the description of the embodiments of the present application, the term "corresponding" may indicate a direct or indirect correspondence between two items, or an association relationship between the two items, or a relationship between indication and being indicated, configuration and being configured, and the like.

[0289] The term "multiple" as used herein refers to two or more than two. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

[0290] In addition, the step numbers described in this document only illustrate a possible execution order between the steps. In some other embodiments, the above steps may not be executed in the order of the numbers, such as two steps with different numbers are executed at the same time, or two steps with different numbers are executed in the opposite order to that shown in the figure. The embodiments of the present application are not limited to this.

[0291] Those skilled in the art should be aware that in one or more of the above examples, the functions described in the embodiments of the present application can be implemented with hardware, software, firmware, or any combination thereof. When implemented using software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein the communication media include any media that facilitates the transmission of a computer program from one place to another. The storage medium can be any available medium that a general or special-purpose computer can access.

[0292] The above description is only an exemplary embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for monitoring a physical downlink control channel (PDCCH), characterized in that: The method is performed by a terminal device, and the method includes: receiving a handover command sent by a first network device, wherein the handover command is used to instruct the terminal device to handover from a first cell corresponding to the first network device to a second cell corresponding to a second network device; Based on the control resource set CORESET associated with the target bandwidth part BWP of the second cell, monitor the PDCCH sent by the second network device.

2. The method according to claim 1, characterized in that The target BWP is an activated BWP of the second cell, and the CORESET associated with the target BWP of the second cell monitors the PDCCH sent by the second network device, including: Use at least one CORESET associated with the activated BWP of the second cell to correspond to at least one activated transmission configuration indication TCI state, and monitor the PDCCH sent by the second network device.

3. The method according to claim 2, characterized in that The switching command also includes second information, where the second information is used to indicate the at least one activated TCI state.

4. The method according to claim 3, characterized in that Each CORESET has independently corresponding second information; or, There are at least two CORESETs that share the same second information.

5. The method according to any one of claims 1 to 4, characterized in that: The switching command is a RACH-less switching command, and the RACH-less switching command is used to instruct the terminal device to perform a RACH-less switching process.

6. The method according to claim 5, characterized in that The receiving a switching command sent by the first network device includes: Receive a radio resource control RRC message sent by the first network device, where the RRC message includes information for instructing the terminal device to perform a RACH-less switching process.

7. A method for monitoring a physical downlink control channel (PDCCH), characterized in that: The method is performed by a first network device, and the method includes: Sending a handover command to a terminal device, wherein the handover command is used to instruct the terminal device to handover from a first cell corresponding to the first network device to a second cell corresponding to the second network device; The terminal device monitors the PDCCH sent by the second network device based on the control resource set CORESET associated with the target bandwidth part BWP of the second cell.

8. The method according to claim 7, characterized in that The target BWP is the activated BWP of the second cell, and the terminal device uses at least one CORESET associated with the activated BWP of the second cell to correspond to at least one activated transmission configuration indication TCI state, and monitors the PDCCH sent by the second network device.

9. The method according to claim 7 or 8, characterized in that: The switching command is a RACH-less switching command, and the RACH-less switching command is used to instruct the terminal device to perform a RACH-less switching process.

10. A method for monitoring a physical downlink control channel (PDCCH), characterized in that: The method is performed by a second network device, and the method includes: Sending a handover command to the first network device, wherein the handover command is used to instruct the terminal device to handover from a first cell corresponding to the first network device to a second cell corresponding to the second network device; The PDCCH is sent in the target bandwidth part BWP, wherein the terminal device monitors the PDCCH based on the control resource set CORESET associated with the target BWP.

11. The method according to claim 10, characterized in that The target BWP is the activated BWP of the second cell, and the terminal device uses at least one CORESET associated with the activated BWP of the second cell to correspond to at least one activated transmission configuration indication TCI state, and monitors the PDCCH sent by the second network device.

12. The method according to claim 10 or 11, characterized in that: The switching command is a RACH-less switching command, and the RACH-less switching command is used to instruct the terminal device to perform a RACH-less switching process.

13. A terminal device, characterized in that: The terminal device comprises a processor and a memory, wherein a computer program is stored in the memory, and the processor executes the computer program to implement the method according to any one of claims 1 to 6.

14. A first network device, characterized in that: The first network device comprises a processor and a memory, wherein a computer program is stored in the memory, and the processor executes the computer program to implement the method according to any one of claims 7 to 9.

15. A second network device, characterized in that: The second network device comprises a processor and a memory, wherein a computer program is stored in the memory, and the processor executes the computer program to implement the method according to any one of claims 10 to 12.

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