Cell handover method and apparatus

Abstract

This application discloses a cell handover method and apparatus, which includes the steps of: receiving indication information from a source cell, the indication information instructing to activate a first transmission configuration indicator (TCI) state; initiating random access to a target cell according to the indication information; and returning second response information to the source cell when the target cell has received first response information returned, the second response information indicating that the first TCI state has been successfully activated. The implementation of cell handover by beam switching allows a terminal device to reduce a delay during the cell handover. The terminal device returns the second response information to the source cell only after receiving the first response information returned by the target cell. The improved feedback mechanism allows a terminal device to improve reliability during beam switching based cell handover.

Description

[Technical field]

[0001] This application relates to the field of communication technologies, and in particular to a cell handover method and apparatus. [Background technology]

[0002] The beamforming technique allows a signal to be concentrated in one direction for transmission and to compensate for path loss. The network device and the terminal device communicate with each other by beams. When the terminal device moves, etc., a handover between multiple cells may occur in the terminal device. When a cell handover occurs due to the terminal device moving between multiple cells, a layer 3 (L3) control mechanism, i.e., a radio resource control (RRC) protocol layer control mechanism, may be used. Specifically, the source cell of the terminal device configures a reference signal measurement configuration of the neighboring cells of the terminal device. The network devices of the neighboring cells transmit reference signals for each beam by beam scanning. The terminal device measures the reference signals of the neighboring cells, selects an appropriate reference signal, and informs the network device of the neighboring cell of the selected reference signal upon initial access to the neighboring cell, so that the network device of the neighboring cell can know the beam corresponding to the reference signal selected by the terminal device.

[0003] However, the delay of the current cell handover method is large, and how to reduce the delay of cell handover is a problem that needs to be solved. Summary of the Invention

[0004] This application provides a cell handover method and apparatus to reduce the delay of a terminal device during cell handover.

[0005] According to a first aspect, a cell handover method is provided. The method may be executed by a terminal device or by a component (such as a processor, a chip, or a chip system) of the terminal device. The method may be implemented by the steps of: receiving indication information from a source cell, the indication information instructing to activate a first transmission configuration indicator (TCI) state; initiating random access to a target cell according to the indication information; and returning second response information to the source cell if the target cell has received first response information returned, the second response information indicating that the first TCI state has been successfully activated. The implementation of cell handover by beam switching allows for a reduction in the delay of the terminal device during cell handover. The terminal device returns the second response information to the source cell only after receiving the first response information returned by the target cell. The improved feedback mechanism allows for an improvement in the reliability of the terminal device during beam switching based cell handover.

[0006] In one possible design, the first TCI state indicates a first reference signal, and the step of initiating random access to a target cell according to the indication information may be implemented by initiating the random access to the target cell based on a first random access resource associated with the first reference signal, the target cell knowing an association relationship between the reference signal and the random access resource, and when the terminal device receives a random access request to initiate based on the first random access resource, the target cell may determine a target beam that the terminal device wants to access.

[0007] In one possible design, multiple reference signals of the target cell are associated with multiple random access resources, and the first reference signal is one of the multiple reference signals.

[0008] In one possible design, the first TCI state indicates the first reference signal, and the step of initiating random access to the target cell according to the indication information may be implemented by sending a scheduling request (SR) or a MAC-CE defined in a protocol to the target cell based on a first uplink control channel resource associated with the first reference signal. The target cell knows the association relationship between the reference signal and the uplink control channel resource. When receiving the scheduling request (SR) or a MAC-CE defined in a protocol that the terminal device initiates based on the first uplink control channel resource, the target cell may determine a target beam that the terminal device wants to access.

[0009] Optionally, the plurality of reference signals of the target cell are associated with a plurality of uplink control channel resources, and the first reference signal is one of the plurality of reference signals.

[0010] The source cell may configure an association relationship between the reference signal and the random access resource for the terminal device in advance, and the terminal device may obtain the association relationship from the source cell. The association relationship may be obtained by the source cell by using a received system message of the target cell. The terminal device determines the random access resource based on the configuration of the random access resource of the target cell, and initiates random access to the target cell. Alternatively, after receiving the indication information from the source cell, the terminal device receives system information or a broadcast message in the target cell, obtains the configuration of the random access resource, and attempts to initiate random access in the target cell.

[0011] In one possible design, the first response information includes response information used to respond to the random access. For example, the first response information may be a random access response or other information used to respond to the random access. The terminal device may consider the random access successful only after receiving the response information used to respond to the random access and returned by the target cell, and may further return second response information to the source cell. The source cell may consider the beam switching successful or the first TCI activation successful only after receiving the second response information. In this way, the reliability of cell handover can be improved.

[0012] In one possible design, the terminal device may alternatively attempt to transmit uplink data or an uplink signal in the target cell after receiving the indication information from the source cell, where the uplink data includes data in a PUSCH and data in a PUCCH, and the uplink signal includes an SRS sounding reference signal. Optionally, the first response information may be response information used to respond to the uplink signal or the uplink data.

[0013] In one possible design, the first TCI state indicates the first reference signal, and the method further includes performing beam failure recovery based on a candidate beam configuration of the first reference signal when a beam failure occurs after initiating the random access to the target cell. When a beam switching based cell handover fails, the terminal device can quickly attempt beam failure recovery in the target cell by using the candidate beam configuration, thereby improving the reliability of the terminal device during beam switching based cell handover.

[0014] In one possible design, the first response information includes response information used to respond to the beam failure recovery. For example, the first response information may be a beam failure recovery request response, or other information that may be used to respond to the beam failure recovery. After the terminal device performs a beam switching based cell handover, a beam switching failure may occur. After receiving the response information used to respond to the beam failure recovery, the terminal device sends back to the source cell a second response message indicating that the first TCI state has been successfully activated, that the cell handover has been successful, or that the beam switching has been successful. In this way, it is possible to further ensure the reliability and robustness of the successful cell handover.

[0015] In one possible design, the step of performing beam failure recovery based on candidate beam configurations of the first reference signal may be implemented by measuring one or more reference signals among the candidate beam configurations of the first reference signal, selecting a second reference signal among the candidate beam configurations according to the measurement result, and sending a beam failure recovery request to the target cell based on the uplink resource associated with the second reference signal.

[0016] In one possible design, the method further includes receiving configuration information from the source cell, the configuration information including downlink resources used to receive a beam failure recovery request response, and receiving the beam failure recovery request response from the target cell based on the downlink resources, the downlink resource configuration information being received such that the beam failure recovery request response of the target cell can be received via the downlink resources, thereby completing the beam failure recovery.

[0017] In one possible design, if the first response information returned by the target cell is not received, communication with the source cell is performed based on a second TCI state used before the first TCI state is successfully activated. For example, a PDCCH from a source cell may be received based on a QCL relationship indicated by the second TCI state. When cell handover is unsuccessful, the terminal device may stay in the source cell and continue communication, thereby ensuring that the terminal device does not return to an RRC initial state because the terminal device is disconnected from the network due to a radio link failure, thereby ensuring normal communication of the terminal device.

[0018] According to a second aspect, a cell handover method is provided. The method may be executed by a terminal device or may be executed by a component (such as a processor, a chip, or a chip system) of the terminal device. The method may be implemented by the terminal device receiving instruction information from a source cell, the instruction information instructing to activate a first TCI state, and initiating random access to a target cell according to the instruction information. When a beam failure occurs, the terminal device performs beam failure recovery based on a candidate beam configuration of a first reference signal, the first TCI state indicates the first reference signal, and is used to respond to the beam failure recovery, and when receiving response information returned by the target cell, returns second response information to the source cell. The source cell receives the second response information from the terminal device, and the second response information indicates that the activation of the first TCI state is successful. When a beam switching based cell handover fails, the terminal device can quickly attempt beam failure recovery in the target cell by using a candidate beam configuration, thereby improving the reliability of the terminal device during beam switching based cell handover.

[0019] In one possible design, the first TCI state indicates the first reference signal, and the step of initiating random access to a target cell according to the indication information may be implemented by initiating the random access to the target cell based on a first random access resource associated with the first reference signal, the target cell knowing an association relationship between a reference signal and a random access resource, and when a terminal device receives a random access request to initiate based on the first random access resource, the target cell may determine a target beam that the terminal device desires to access.

[0020] In one possible design, multiple reference signals of the target cell are associated with multiple random access resources, and the first reference signal is one of the multiple reference signals.

[0021] In one possible design, the first TCI state indicates the first reference signal, and the step of initiating random access to the target cell according to the indication information may be implemented by sending a scheduling request (SR) or a MAC-CE defined in a protocol to the target cell based on a first uplink control channel resource associated with the first reference signal. The target cell knows the association relationship between the reference signal and the uplink control channel resource. When receiving the scheduling request (SR) or a MAC-CE defined in a protocol that the terminal device initiates based on the first uplink control channel resource, the target cell may determine a target beam that the terminal device wants to access.

[0022] Optionally, the plurality of reference signals of the target cell are associated with a plurality of uplink control channel resources, and the first reference signal is one of the plurality of reference signals.

[0023] The source cell may configure an association relationship between the reference signal and the random access resource for the terminal device in advance, and the terminal device may obtain the association relationship from the source cell. The association relationship may be obtained by the source cell by using a received system message of the target cell. The terminal device determines the random access resource based on the configuration of the random access resource of the target cell, and initiates random access to the target cell. Alternatively, after receiving the indication information from the source cell, the terminal device receives system information or a broadcast message in the target cell, obtains the configuration of the random access resource, and attempts to initiate random access in the target cell.

[0024] In one possible design, the terminal device may alternatively attempt to transmit uplink data or an uplink signal in the target cell after receiving the indication information from the source cell, where the uplink data includes data in a PUSCH and data in a PUCCH, and the uplink signal includes an SRS sounding reference signal. Optionally, the first response information may be response information used to respond to the uplink signal or the uplink data.

[0025] In one possible design, the step of performing beam failure recovery based on candidate beam configurations of the first reference signal may be implemented by measuring one or more reference signals among the candidate beam configurations of the first reference signal, selecting a second reference signal among the candidate beam configurations according to the measurement result, and sending a beam failure recovery request to the target cell based on the uplink resource associated with the second reference signal.

[0026] In one possible design, the method further includes receiving configuration information from the source cell, the configuration information including downlink resources used to receive the beam failure recovery request response, and receiving the beam failure recovery request response from the target cell based on the downlink resources, whereby the beam failure recovery request response of the target cell can be received via the downlink resources, thereby completing the beam failure recovery.

[0027] In one possible design, if the first response information returned by the target cell is not received, communication with the source cell is performed based on a second TCI state used before the first TCI state is successfully activated. For example, a PDCCH from a source cell may be received based on a QCL relationship indicated by the second TCI state. When cell handover is unsuccessful, the terminal device may stay in the source cell and continue communication, thereby ensuring that the terminal device does not return to an RRC initial state because the terminal device is disconnected from the network due to a radio link failure, thereby ensuring normal communication of the terminal device.

[0028] According to a third aspect, a cell handover method is provided. The method may be executed by a source cell or may be executed by a component (such as a processor, chip, or chip system) of the source cell. The operation performed by the source cell may be executed by a network device in which the source cell is located. The method may be implemented by the steps of: sending indication information to a terminal device based on a quasi-co-location QCL relationship indicated by a first TCI state, the indication information instructing to activate a second TCI state, the indication information being used by the terminal device to initiate random access to a target cell; and receiving an acknowledgement from the terminal device, the acknowledgement indicating that the activation of the second TCI state has been successful. The indication information instructs to activate the second TCI state of the target cell, thereby , beam switching It is possible to implement cell handover by, thereby reducing the delay of cell handover.

[0029] Generally, the acknowledgement may be sent by using physical layer signaling or may be sent by using MAC layer signaling. The delay of the physical layer and the MAC layer is smaller than the delay of layer 3, i.e., the delay of the RRC layer. Therefore, the delay of the cell handover can be reduced.

[0030] In one possible design, communication is performed with the terminal device by using the QCL relationship indicated by the first TCI state if a negative acknowledgement is received from the terminal device, the negative acknowledgement indicating that the cell handover has failed. Even when the cell handover has failed, communication with the terminal device can be continued, thereby ensuring that the terminal device does not return to an RRC initial state because the terminal device is disconnected from the network due to a radio link failure, thereby ensuring normal communication of the terminal device.

[0031] In one possible design, configuration information is requested from the target cell, the configuration information including downlink resources used by the terminal device to receive a beam failure recovery request response, and the configuration information is received from the target cell. Requesting configuration information from the target cell may indicate to the terminal device downlink resources used to receive the beam failure recovery request response, such that the terminal device receives the beam failure recovery request response from the target cell in the downlink resources.

[0032] According to a fourth aspect, a communication apparatus is provided. The communication apparatus may be a terminal device, an apparatus (e.g., a chip, a chip system, or a circuit) located in the terminal device, or an apparatus capable of being used in conjunction with the terminal device. In one design, the apparatus may include a number of modules having a one-to-one correspondence with the methods / operations / steps / actions described in the first aspect. The modules may be implemented by hardware circuits, software, or a combination of hardware circuits and software. In one design, the apparatus may include a processing module and a communication module. The processing module is configured to call the communication module to perform a receiving function and / or a transmitting function. The communication module may also be referred to as a transceiver module and may further include a transmitting module and a receiving module. Specifically, the transmitting module is configured to implement a transmitting operation in the above method, and the receiving module is configured to implement a receiving operation in the above method. Other operations are implemented by the processing module. For example, the communication module is configured to receive indication information from a source cell, the indication information instructing to activate a first TCI state. The processing module is configured to initiate random access to the target cell according to the indication information, and is configured to return second response information to the source cell by using the communication module when the communication module determines that the first response information returned by the target cell is received, the second response information indicating that the first TCI state is successfully activated. The terminal device returns the second response information to the source cell only after receiving the first response information returned by the target cell. The improved feedback mechanism can improve the reliability of the terminal device during beam switching based cell handover.

[0033] In one possible design, the first TCI state indicates the first reference signal, and when initiating the random access to the target cell according to the indication information, the processing module is configured to initiate the random access to the target cell based on, among other things, a first random access resource associated with the first reference signal. The target cell knows an association relationship between a reference signal and a random access resource. When a terminal device receives a random access request to initiate based on the first random access resource, the target cell may determine a target beam that the terminal device wants to access.

[0034] In one possible design, multiple reference signals of the target cell are associated with multiple random access resources, and the first reference signal is one of the multiple reference signals.

[0035] In one possible design, when the first TCI state indicates the first reference signal and initiates random access to a target cell according to the indication information, the processing module is configured to, among other things, send a scheduling request (SR) or a MAC-CE defined in a protocol to the target cell based on a first uplink control channel resource associated with the first reference signal. The target cell knows the association relationship between the reference signal and the uplink control channel resource. When receiving the scheduling request (SR) or a MAC-CE defined in a protocol that the terminal device initiates based on the first uplink control channel resource, the target cell may determine a target beam that the terminal device wants to access.

[0036] Optionally, the plurality of reference signals of the target cell are associated with a plurality of uplink control channel resources, and the first reference signal is one of the plurality of reference signals.

[0037] The source cell may configure an association relationship between the reference signal and the random access resource for the terminal device in advance, and the processing module is further configured to obtain the association relationship from the source cell. The association relationship may be obtained by the source cell by using a received system message of the target cell. The processing module determines the random access resource based on the configuration of the random access resource of the target cell, and initiates random access to the target cell. Alternatively, after receiving the indication information from the source cell by using the communication module, the processing module receives system information or a broadcast message in the target cell, obtains the configuration of the random access resource, and attempts to initiate random access in the target cell.

[0038] In one possible design, the terminal device may alternatively attempt to transmit uplink data or an uplink signal in the target cell after receiving the indication information from the source cell, where the uplink data includes data in a PUSCH and data in a PUCCH, and the uplink signal includes an SRS sounding reference signal. Optionally, the first response information may be response information used to respond to the uplink signal or the uplink data.

[0039] In one possible design, the first response information includes response information used to respond to the random access. For example, the first response information may be a random access response or other information that may be used to respond to the random access. The terminal device may consider the random access successful only after receiving the response information used to respond to the random access and returned by the target cell, and may further return second response information to the source cell. The source cell may consider the beam switching successful or the first TCI activation successful only after receiving the second response information. In this way, it is possible to improve the reliability of cell handover.

[0040] In one possible design, the first TCI state indicates the first reference signal, and the processing module is further configured to perform beam failure recovery based on a candidate beam configuration of the first reference signal when a beam failure occurs after initiating the random access to the target cell. When a beam switching based cell handover fails, the terminal device can quickly attempt beam failure recovery in the target cell by using the candidate beam configuration, thereby improving reliability of the terminal device during beam switching based cell handover.

[0041] In one possible design, the first response information includes response information used to respond to the beam failure recovery. For example, the first response information may be a beam failure recovery request response, or other information that may be used to respond to the beam failure recovery. After the terminal device performs a beam switching based cell handover, a beam switching failure may occur. After receiving the response information used to respond to the beam failure recovery, the terminal device sends back to the source cell a second response message indicating that the first TCI state has been successfully activated, that the cell handover has been successful, or that the beam switching has been successful. In this way, it is possible to further ensure the reliability and robustness of the successful cell handover.

[0042] In one possible design, when performing beam failure recovery based on candidate beam configurations of the first reference signal, the processing module is configured, in particular, to measure one or more reference signals among the candidate beam configurations of the first reference signal, select a second reference signal among the candidate beam configurations according to the measurement result, and send a beam failure recovery request to the target cell based on the uplink resource associated with the second reference signal.

[0043] In one possible design, the communication module is further configured to receive configuration information from the source cell, the configuration information including downlink resources used to receive a beam failure recovery request response, and the processing module is further configured to receive the beam failure recovery request response from the target cell based on the downlink resources, and receive downlink resource configuration information such that the beam failure recovery request response of the target cell can be received via the downlink resources, thereby completing the beam failure recovery.

[0044] In one possible design, the processing module is further configured to communicate with the source cell based on a second TCI state used before the first TCI state is successfully activated if the first response information returned by the target cell is not received. For example, a PDCCH from a source cell may be received based on a QCL relationship indicated by the second TCI state. When cell handover is unsuccessful, the terminal device may stay in the source cell and continue communication, thereby ensuring that the terminal device does not return to an RRC initial state because the terminal device is disconnected from the network due to a radio link failure, thereby ensuring normal communication of the terminal device. Alternatively, the processing module is further configured to communicate with the source cell based on a second TCI state used before the first TCI state is successfully activated if the first response information returned by the target cell is not received. It can be understood that if the processing module determines that it has not received the first response information returned by the target cell, the processing module communicates with the source cell based on the second TCI state used before successfully activating the first TCI state.

[0045] According to a fifth aspect, a communication apparatus is provided. The communication apparatus may be a terminal device, an apparatus (e.g., a chip, a chip system, or a circuit) located in the terminal device, or an apparatus capable of being used in conjunction with the terminal device. In one design, the apparatus may include a number of modules having a one-to-one correspondence with the methods / operations / steps / actions described in the second aspect. The modules may be implemented by hardware circuits, software, or a combination of hardware circuits and software. In one design, the apparatus may include a processing module and a communication module. The processing module is configured to call the communication module to perform a receiving function and / or a transmitting function. The communication module may also be referred to as a transceiver module and may further include a transmitting module and a receiving module. Specifically, the transmitting module is configured to implement a transmitting operation in the above method, and the receiving module is configured to implement a receiving operation in the above method. Other operations are implemented by the processing module. For example, the communication module is configured to receive indication information from a source cell, the indication information instructing to activate a first TCI state. The processing module is configured to initiate random access to a target cell according to the instruction information, perform beam failure recovery based on a candidate beam configuration of a first reference signal when a beam failure occurs, and return second response information to the source cell when the first TCI state indicates the first reference signal and is used to respond to the beam failure recovery and receives response information returned by the target cell. The source cell receives the second response information from the terminal device, and the second response information indicates that the activation of the first TCI state is successful.When a beam switching based cell handover fails, the terminal device can quickly attempt beam failure recovery in the target cell by using a candidate beam configuration, thereby improving the reliability of the terminal device during beam switching based cell handover.

[0046] In one possible design, the first TCI state indicates the first reference signal, and when initiating the random access to the target cell according to the indication information, the processing module is configured to initiate the random access to the target cell based on, among other things, a first random access resource associated with the first reference signal, the target cell being aware of an association relationship between the reference signal and the random access resource. When the terminal device receives a random access request to initiate based on the first random access resource, the target cell may determine a target beam that the terminal device desires to access.

[0047] In one possible design, multiple reference signals of the target cell are associated with multiple random access resources, and the first reference signal is one of the multiple reference signals.

[0048] In one possible design, when the first TCI state indicates the first reference signal and initiates the random access to the target cell according to the indication information, the processing module is configured to, among other things, send a scheduling request (SR) or a MAC-CE defined in a protocol to the target cell based on a first uplink control channel resource associated with the first reference signal. The target cell knows the association relationship between the reference signal and the uplink control channel resource. When receiving the scheduling request (SR) or a MAC-CE defined in a protocol that the terminal device initiates based on the first uplink control channel resource, the target cell may determine a target beam that the terminal device wants to access.

[0049] Optionally, the plurality of reference signals of the target cell are associated with a plurality of uplink control channel resources, and the first reference signal is one of the plurality of reference signals.

[0050] The source cell may configure an association relationship between the reference signal and the random access resource for the terminal device in advance, and the processing module is further configured to obtain the association relationship from the source cell. The association relationship may be obtained by the source cell by using a received system message of the target cell. The processing module determines the random access resource based on the configuration of the random access resource of the target cell, and initiates random access to the target cell. Alternatively, after receiving the indication information from the source cell by using the communication module, the processing module receives system information or a broadcast message in the target cell, obtains the configuration of the random access resource, and attempts to initiate random access in the target cell.

[0051] In one possible design, the terminal device may alternatively attempt to transmit uplink data or an uplink signal in the target cell after receiving the indication information from the source cell, where the uplink data includes data in a PUSCH and data in a PUCCH, and the uplink signal includes an SRS sounding reference signal. Optionally, the first response information may be response information used to respond to the uplink signal or the uplink data.

[0052] In one possible design, when performing the beam failure recovery based on the candidate beam configurations of the first reference signal, the processing module is configured, in particular, to measure one or more reference signals among the candidate beam configurations of the first reference signal, select a second reference signal among the candidate beam configurations according to the measurement result, and send a beam failure recovery request to the target cell based on the uplink resource associated with the second reference signal.

[0053] In one possible design, the communication module is further configured to receive configuration information from the source cell, the configuration information including downlink resources used to receive a beam failure recovery request response. The processing module is further configured to receive the beam failure recovery request response from the target cell by using the communication module based on the downlink resources. By receiving the downlink resource configuration information, the beam failure recovery request response of the target cell can be received by the downlink resources, thereby completing the beam failure recovery.

[0054] In one possible design, the communication module is further configured to communicate with the source cell based on a second TCI state used before the first TCI state is successfully activated if the first response information returned by the target cell is not received. For example, a PDCCH from a source cell may be received based on a QCL relationship indicated by the second TCI state. When cell handover is unsuccessful, the terminal device may stay in the source cell and continue communication, thereby ensuring that the terminal device does not return to an RRC initial state because the terminal device is disconnected from the network due to a radio link failure, thereby ensuring normal communication of the terminal device. Alternatively, the processing module is further configured to communicate with the source cell based on the second TCI state used before the first TCI state is successfully activated if the first response information returned by the target cell is not received. It can be understood that when the processing module is configured to determine that the first response information returned by the target cell is not received, the processing module communicates with the source cell based on the second TCI state used before successfully activating the first TCI state.

[0055] According to a sixth aspect, a communication apparatus is provided. The communication apparatus may be a source cell, a device (e.g., a chip, a chip system, or a circuit) located in the source cell, or a device that can be used in conjunction with the source cell. The operations performed by the source cell may be performed by a network device in which the source cell is located. In one design, the apparatus may include a number of modules having a one-to-one correspondence with the methods / operations / steps / actions described in the third aspect. The modules may be implemented by hardware circuits, software, or a combination of hardware circuits and software. In one design, the apparatus may include a processing module and a communication module. The processing module is configured to call the communication module to perform a receiving function and / or a transmitting function. The communication module may also be referred to as a transceiver module and may further include a transmitting module and a receiving module. Specifically, the transmitting module is configured to implement a transmitting operation in the above method, and the receiving module is configured to implement a receiving operation in the above method. Other operations are implemented by the processing module. For example, the processing module is configured to send, by using the communication module, indication information to the terminal device based on the quasi-co-location QCL relationship indicated by the first TCI state, the indication information instructing to activate a second TCI state, the indication information being used by the terminal device to initiate random access to a target cell. The communication module is further configured to receive an acknowledgement from the terminal device, the acknowledgement indicating that the activation of the second TCI state is successful. The indication information instructs to activate the second TCI state of the target cell, thereby , beam switching It is possible to implement cell handover by, thereby reducing the delay of cell handover.

[0056] Generally, the acknowledgement may be sent by using physical layer signaling or may be sent by using MAC layer signaling. The delay of the physical layer and the MAC layer is smaller than the delay of layer 3, i.e., the delay of the RRC layer. Therefore, the delay of the cell handover can be reduced.

[0057] In one possible design, the processing module is configured to communicate with the terminal device by using the QCL relationship indicated by the first TCI state if a negative acknowledgement is received from the terminal device, the negative acknowledgement indicating a cell handover failure. Even when the cell handover fails, communication with the terminal device can be continued, thereby ensuring that the terminal device does not return to an RRC initial state because the terminal device is disconnected from the network due to a radio link failure, thereby ensuring normal communication of the terminal device.

[0058] In one possible design, the processing module is further configured to request configuration information from the target cell, the configuration information including downlink resources used for the terminal device to receive a beam failure recovery request response, and the communication module is further configured to receive the configuration information from the target cell. Requesting configuration information from the target cell may indicate to the terminal device downlink resources used for receiving the beam failure recovery request response, such that the terminal device receives the beam failure recovery request response from the target cell on the downlink resources.

[0059] According to a seventh aspect, an embodiment of the present application provides a communication device, the communication device including a communication interface and a processor, the communication interface being used by the device to communicate with another device, for example, to transmit and receive data or signals. For example, the communication interface may be a transceiver, a circuit, a bus, a module, or another type of communication interface, and the other device may be a network device of a source cell or a target cell. The processor is configured to call a group of programs, instructions, or data to perform the method described in the first aspect or the second aspect. The device may further include a memory, the memory being configured to store the programs, instructions, or data called by the processor. The memory is coupled to the processor, and when executing the instructions or data stored in the memory, the processor is capable of implementing the method described in the first aspect or the second aspect.

[0060] According to an eighth aspect, an embodiment of the present application provides a communication device, the communication device including a communication interface and a processor, the communication interface being used by the device to communicate with another device, for example, to transmit and receive data or signals. For example, the communication interface may be a transceiver, a circuit, a bus, a module, or another type of communication interface, and the other device may be a terminal device. The processor is configured to call a group of programs, instructions, or data to perform the method described in the third aspect. The device may further include a memory, the memory being configured to store the programs, instructions, or data to be called by the processor. The memory is coupled to the processor, and when executing the instructions or data stored in the memory, the processor is capable of implementing the method described in the third aspect.

[0061] According to a ninth aspect, an embodiment of the present application further provides a computer readable storage medium storing computer readable instructions which, when executed by a computer, perform a method according to the first aspect or any one of a plurality of possible designs of the first aspect, or perform a method according to the second aspect or any one of a plurality of possible designs of the second aspect.

[0062] According to a tenth aspect, an embodiment of the present application further provides a computer-readable storage medium comprising instructions which, when executed by a computer, enable the computer to perform a method according to the third aspect or any one of a number of possible designs of the third aspect.

[0063] According to an eleventh aspect, an embodiment of the present application provides a chip system including one or more processors configured to execute computer programs or instructions in a memory to implement a method according to the first aspect or any one of a number of possible designs of the first aspect. The chip system may include a chip or may include a chip and other individual devices.

[0064] Optionally, the chip system may include a memory or be connected to a memory.

[0065] According to a twelfth aspect, an embodiment of the present application provides a chip system including one or more processors configured to execute computer programs or instructions to implement a method according to the second aspect or any one of a number of possible designs of the second aspect. The chip system may include a chip, or may include a chip and other individual devices.

[0066] Optionally, the chip system may include a memory or be connected to a memory.

[0067] According to a thirteenth aspect, an embodiment of the present application provides a chip system including one or more processors configured to execute computer programs or instructions to implement a method according to the third aspect or any one of a number of possible designs of the third aspect. The chip system may include a chip or may include a chip and other individual devices.

[0068] Optionally, the chip system may include a memory or be connected to a memory.

[0069] According to a fourteenth aspect, an embodiment of the present application provides a communication system, the communication system including a communication device according to the fourth or fifth aspect, a communication device in a source cell, and a communication device in a target cell.

[0070] In one possible design, the communication devices in the source cell include a communication device according to the sixth aspect or a communication device according to the eighth aspect.

[0071] According to a fifteenth aspect, there is provided a computer program product comprising instructions, which when executed by a computer, perform a method according to any one of the above aspects and possible designs of those aspects. [Brief description of the drawings]

[0072] [Figure 1] FIG. 1 is a schematic architecture diagram of a communication system according to an embodiment of the present application. [Diagram 2]2 is a schematic diagram of beam switching from a source cell to a target cell according to one embodiment of the present application; FIG. [Diagram 3] 1 is a first schematic flowchart of a cell handover method according to an embodiment of the present application; [Figure 4] 1 is a schematic block diagram of a MAC-CE used to activate a TCI state according to one embodiment of this application; [Diagram 5] 2 is a second schematic flowchart of a cell handover method according to an embodiment of the present application; [Figure 6] 4 is a third schematic flowchart of a cell handover method according to an embodiment of the present application. [Figure 7] 1 is a schematic flow chart of a beam switching failure according to an embodiment of the present application. [Figure 8] 4 is a fourth schematic flowchart of a cell handover method according to an embodiment of the present application. [Figure 9] 1 is a first schematic configuration diagram of a communication device according to an embodiment of the present application; [Figure 10] FIG. 2 is a second schematic configuration diagram of a communication device according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0073] The embodiments of this application provide a cell handover method and apparatus. These methods and apparatus are based on the same or similar technical concepts. Because the problem-solving principles of these methods and apparatus are similar, the implementations of these apparatuses and methods may be referred to each other, and the repeated parts will not be described. In the description of the embodiments of this application, the words "first", "second", and "third" are only used to distinguish the description, and cannot be understood as indicating or implying relative importance, and cannot be understood as indicating or implying order.

[0074] The cell handover method provided by the embodiments of the present application may be applied to a 4th generation (4G) communication system, such as long term evolution (LTE), or may be applied to a 5th generation (5G) communication system, such as 5G new radio (NR), or may be applied to various future communication systems, such as a 6th generation (6G) communication system.

[0075] The following description will explain in detail several embodiments of the present application with reference to several accompanying drawings.

[0076] 1 shows a possible architecture of a communication system to which a cell handover method according to an embodiment of this application can be applied. Referring to FIG. 1, a communication system 100 includes a network device 101 and a terminal device 102. The network device 101 provides a service to the terminal device 102 within its coverage area.

[0077] The network device 101 is a node in a radio access network (RAN) and may also be referred to as a base station or a RAN node (or device). Examples of some network devices 101 are a next generation NodeB (gNB), a next generation evolved NodeB (gNB), a transmission reception point (TRP), an evolved NodeB (eNB), a radio network controller (RNC), a NodeB (NodeB, NB), a base station controller (BSC), a base transceiver station (BTS), a HeNB (e.g., home evolved NodeB, or home NodeB, HNB), a base band unit (BBU), and a wireless fidelity (Wi-Fi) access point (AP). Alternatively, the network device 101 may be a satellite, which may also be referred to as a high altitude platform, a high altitude aircraft, or a satellite base station. Alternatively, the network device 101 may be another device having a network device function. For example, the network device 101 may be a device that functions as a network device in device-to-device (D2D) communication. Alternatively, the network device 101 may be a network device in a possible future communication system.

[0078] In some deployments, the network device may include a central unit (CU) and a distributed unit (DU). The network device may further include an active antenna unit (AAU). The CU implements some of the network device's functions, and the DU implements some of the other network device's functions. For example, the CU is responsible for processing non-real-time protocols and services, and for implementing radio resource control (RRC) and packet data convergence protocol (PDCP) layer functions. The DU is responsible for processing physical layer protocols and real-time services, and for implementing radio link control (RLC), media access control (MAC), and physical (PHY) layer functions. The AAU implements some of the physical layer processing functions, RF processing functions, and functions related to active antennas. Since the information at the RRC layer is eventually changed to or from the information at the PHY layer, in this architecture, the higher layer signaling, such as the RRC layer signaling, may alternatively be considered to be transmitted by the DU or may be considered to be transmitted by the DU+AAU. It can be understood that the network device may be a device including one or more of a CU node, a DU node, and an AAU node. In addition, the CU may be assigned to a network device in a radio access network (RAN), or the CU may be assigned to a network device in a core network (CN). This is not limited in this application.

[0079] The terminal device 102 may also be referred to as user equipment (UE), mobile station (MS), or mobile terminal (MT), and is a device that provides voice and / or data connectivity to a user. For example, the terminal device 102 includes a handheld device and an in-vehicle device having a wireless connectivity function. At present, the terminal device 102 may be a mobile phone, a tablet computer, a notebook computer, a handheld computer, a mobile internet device (MID), a wearable device (such as a smart watch, a smart band, a pedometer, etc.), an in-vehicle device (such as a car, a bicycle, an electric car, an airplane, a ship, a train, or a high-speed train, etc.), a virtual reality (VR) device, an augmented reality (AR) device, a wireless terminal in industrial control, a smart home device (such as a refrigerator, a television set, an air conditioner, or an electric meter, etc.), an intelligent robot, a workshop device, a wireless terminal in self-driving, a wireless terminal in remote medical surgery, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, or a smart home. The terminal device 102 may be a wireless terminal in a home (e.g., a wireless terminal in a home), or a flying device (e.g., an intelligent robot, a hot air balloon, an unmanned aerial vehicle, or an aircraft). Alternatively, the terminal device 102 may be another device having a terminal device function. For example, the terminal device 102 may be a device that functions as a terminal device in D2D communication.

[0080] Based on the system architecture shown in FIG. 1, the solution provided by the embodiments of this application relates to handover between cells of a terminal device, in other words, the terminal device is handed over from one cell to another cell. The cell from which the handover is performed may be referred to as a source serving cell or a source cell. The cell to which the handover is to be performed or the cell to which the handover is performed may be referred to as a target serving cell or a target cell. In the embodiments of this application, a source cell and a target cell are used as an example for explanation. As shown in FIG. 2, the terminal device performs beam communication in the source cell. Due to the mobility of the terminal device or other reasons, the terminal device may be handed over to the target cell. After the handover, the terminal device performs beam communication with the target cell. In the embodiments of this application, the source cell and the target cell may be provided by the same network device or may be provided by different network devices. The terminal device performing beam communication with the source cell may be understood as the terminal device performing wireless communication with the network device of the source cell by beam. Similarly, a terminal device performing beam communication with a target cell may be understood to mean that the terminal device performs wireless communication with a network device of the target cell via a beam.

[0081] The concept of beams in the embodiments of this application will be explained first to facilitate understanding by those skilled in the art.

[0082] In the NR protocol, a beam may be represented by a spatial domain filter, a spatial filter, a spatial domain parameter, a spatial parameter, a spatial domain setting, a spatial setting, a quasi-colocation (QCL) information, a QCL hypothesis, or a QCL indication, etc. A beam may be indicated by using a TCI state. A beam may alternatively be indicated by using a spatial relation parameter. Thus, in this application, a beam may be replaced by a spatial domain filter, a spatial filter, a spatial domain parameter, a spatial parameter, a spatial domain setting, a spatial setting, a QCL information, a QCL hypothesis, a QCL indication, a TCI state (including a DL TCI state and / or a UL TCI state), or a spatial relation, etc. The above terms are also equivalent to each other. Alternatively, a beam may be replaced by other terms representing a beam. This is not limited in this application.

[0083] The beam may be a wide beam, a narrow beam, or other type of beam. The technology for forming the beam may be a beamforming technology or other technology. The beamforming technology may specifically be a digital beamforming technology, an analog beamforming technology, or a hybrid digital / analog beamforming technology, etc. Optionally, multiple beams having the same or similar communication characteristics are considered as one beam. A beam may correspond to one or more antenna ports and is used to transmit data channels, control channels, audio signals, etc. One or more antenna ports (corresponding to a beam) forming a beam may also be considered as an antenna port set or an antenna port group.

[0084] In embodiments of this application, cell handover is implemented by beam switching, which may be implemented through layer 1 (L1), i.e., the physical layer (PHY), or through layer 2 (L2), i.e., the medium access control (MAC) layer. Compared to a control mechanism implemented through L3, i.e., the RRC protocol layer, it is possible to reduce cell handover delay.

[0085] As shown in FIG. 3, the following description will describe in detail the specific procedures of a cell handover method according to one embodiment of this application.

[0086] S301. A source cell sends indication information to a terminal device, and in response, the terminal device receives indication information from the source cell.

[0087] The instruction information indicates beam switching, or the instruction information indicates to activate a first TCI state, or the instruction information indicates any of a spatial relationship, a beam ID, a joint TCI, a UL-TCI, a common beam, a QCL information, a QCL hypothesis, or a spatial filter. When the instruction information indicates to activate the first TCI state, the instruction information may include an identifier (TCI state ID) of the first TCI state.

[0088] S302. The terminal device initiates random access to the target cell according to the indication information.

[0089] S303. When the terminal device receives the first response information returned by the target cell, the terminal device returns second response information to the source cell.

[0090] It should be noted that in this embodiment of the application, the response information may also be referred to as a response message. For example, the first response information may be referred to as a first response message, and the second response information may be referred to as a second response message.

[0091] The second response information is used to respond to the indication information received in S301. For example, in S301, the indication information may indicate beam switching, and the second response information may indicate that the beam switching is successful. In another example, in S301, the indication information may indicate to activate a first TCI state, and the second response information may indicate that the activation of the first TCI state is successful. The second response information may be acknowledgement (ACK) information. The second response information may be considered to indicate that the terminal device has successfully received physical downlink control channel (PDCCH) information based on the QCL relationship indicated by the first TCI. Alternatively, the second response information indicates that the terminal device has received PDCCH information based on the QCL relationship indicated by the first TCI, and has successfully received physical downlink shared channel (PDSCH) information based on the scheduling of the PDCCH information.

[0092] The indication information may be L1 layer signaling or L2 layer signaling. Generally, after receiving the indication information at L1 or L2, the terminal device returns a response to the indication information at regular intervals. When using a conventional feedback mechanism, after receiving the response returned by the terminal device, the source cell considers that the beam switching of the terminal device is successful. However, the beam switching of the terminal device may fail, in other words, the cell handover may fail. When the beam switching-based cell handover of the terminal device fails, the radio link of the terminal device is interrupted, the terminal device is disconnected from the network, and returns to the RRC initial state. Obviously, the reliability of successful cell handover is It is impossible to guarantee In this embodiment of the present application, the terminal device returns the second response information to the source cell only after receiving the first response information returned by the target cell. The improved feedback mechanism can improve the reliability of the terminal device during beam switching-based cell handover.

[0093] The following description further details optional implementations of the cell handover method provided by this embodiment of the application.

[0094] Before the source cell transmits the indication information to the terminal device in S301, the source cell may transmit a physical layer measurement configuration to the terminal device, and the terminal device receives the physical layer measurement configuration from the source cell. The physical layer measurement configuration includes reference signal information of the neighboring cell, such as a downlink reference signal of the neighboring cell. The downlink reference signal may be a synchronization signal / physical broadcast channel block (SS / PBCH block), and the SS / PBCH block may be abbreviated as a synchronization signal block (SSB), a sounding reference signal (SRS), a demodulation reference signal (DMRS), a channel state information reference signal (CSI-RS), a cell specific reference signal (CSI-RS), or a tracking reference signal (TRS), etc. The terminal device measures the downlink reference signal of the neighboring cell based on the physical layer measurement configuration. The terminal device reports a measurement result of a downlink reference signal of a neighboring cell to the source cell, and the source cell sends indication information to the terminal device according to the measurement result. The indication information may include one or more of an identifier of the terminal device, an identifier of the neighboring cell, a bandwidth part (BWP) identifier, a component carrier (CC) identifier, an identifier of a random access resource, or an identifier of a target beam. The identifier of the target beam may be replaced by an identifier that may represent other parameters of the beam.

[0095] In S301, the source cell sends instruction information to the terminal device. The instruction information may be a beam switching instruction, and instructs the terminal device to switch beams. The terminal device performs cell handover according to the source cell's instruction information to implement a beam switching-based cell handover. In this embodiment of the present application, the beam instruction may be implemented by the following manner:

[0096] In downlink transmission, the network device indicates a transmission configuration number (index) state (TCI state) to the terminal device. The TCI state is a parameter set, and includes a number of parameters related to a downlink transmission beam (a transmission beam of the network device). Therefore, in this application, the beam and the TCI state may be considered equivalent and may be substituted for each other. For example, in S301, the instruction to switch the beam by the instruction information may also be considered to be an instruction to activate the TCI state. The network device may be a network device of a source cell. The following description uses the source cell as an example for explanation.

[0097] First, the source cell configures the TCI state for the terminal device, and the terminal device receives the TCI state from the source cell.

[0098] A source cell configures multiple TCI states for a terminal device by using RRC signaling. Each TCI state includes an index TCI stateId field and two QCL-Info fields. Each QCL-Info field may include a cell field, and may further include a bwp-Id (bandwidth part, BWP) field, a referenceSignal (reference signal) field, and a qcl-Type field. The cell field indicates that the TCI state applies to the cell indicated by the cell field. Different QCL-Info may be configured for different cells, and different QCL-Info may be configured for different BWPs of a cell. The bwp-Id field indicates the BWP in which the bwp-Id field indicates and in which the reference signal in the TCI state is located. The referenceSignal field indicates that the channel or signal transmitted in the TCI state and the reference signal indicated by the referenceSignal field form a quasi-co-location (QCL) relationship. The channel transmitted in the TCI state is, for example, a PDSCH or a PDCCH. The QCL relationship indicates that a terminal may assume some of the same reception compensation and / or spatial filtering parameters when receiving two reference signals. Alternatively, the two reference signal resources may be replaced by two antenna ports, which have a one-to-one correspondence with the reference signal resources. Which reception parameters between the two reference signal resources are the same is determined by the qcl-Type field in the QCL-Info. "The resource of the channel transmitted in the TCI state and the reference signal resource indicated by the referenceSignal field form a QCL relationship."

[0099] The qcl-Type field may have four values: typeA, typeB, typeC, and typeD. TypeA indicates that the two reference signal resources have the same Doppler shift (i.e., frequency shift), Doppler spread (i.e., frequency shift range), average delay (i.e., average time shift), and delay spread (i.e., time shift range). TypeB indicates that the two reference signal resources have the same Doppler shift and Doppler spread. TypeC indicates that the two reference signal resources have the same Doppler shift and average delay. TypeD indicates that the terminal can assume that the same spatial reception parameters are used to receive the two reference signal resources, and the use of the same spatial reception parameters may also be understood to mean that the network device transmits two reference signals by two identical transmission beams. Among the two QCL-Infos included in the TCI state that the source cell configures for the terminal device, the largest QCL-Info may be of type typeD. Alternatively, the TCI state configured by the network device may not include QCL-info of type D, and the TCI state that does not include QCL-info of type D is not used to indicate beam related information, and therefore, no further description is provided herein.

[0100] In this embodiment of the application, the TCI state that the source cell configures for the terminal device may include the TCI state of the neighboring cells.

[0101] After the source cell configures the TCI state for the terminal device, when the terminal device determines that it needs to perform a cell handover, the source cell sends signaling to the terminal device to activate the TCI state.

[0102] Using the PDCCH as an example, the activation of the TCI state for receiving the PDCCH may be indicated by using a medium access control-control element (MAC-CE). In the case of an evolved version of the protocol, the TCI state may also support indication or activation using downlink control indication DCI signaling at the physical layer. The source cell sends a MAC-CE to the terminal device, and each MAC-CE may indicate only one TCI state ID of one control resource set (CORESET). The CORESET is the resource for the terminal device to receive the PDCCH. The terminal device may determine the target beam based on the value of the TCI state ID. The MAC-CE configuration used to activate the TCI state is shown in Figure 4.

[0103] In S301, the indication information may be carried by using MAC-CE, or may be carried by using downlink control information (DCI).

[0104] Alternatively, the source cell may indicate the TCI status by using a TCI field in the DCI. For example, the TCI field may occupy 3 bits and represent 8 different codepoints. Each field value of the TCI field corresponds to a TCI status index, and the TCI status index uniquely identifies a TCI status. The scheme of indicating the TCI status by using the DCI is also applicable to the PDSCH.

[0105] The target beam indicated by the instruction information in S301 may be a transmitting beam used by the terminal device to transmit a signal, or may be a receiving beam used by the terminal device to receive a signal.

[0106] S302. The terminal device initiates random access to the target cell according to the instruction information in S301. The terminal device receives the first TCI situationThe random access resource used by the terminal device to initiate the random access to the target cell may be determined by a scheme in which the terminal device receives, in S301, an indication information instructing the terminal device to activate a first TCI state, the first TCI state indicating one or more parameters, and the first TCI state indicating a first reference signal. An association relationship exists between the reference signal and the random access resource, the first reference signal is associated with the first random access resource, and the terminal device initiates the random access to the target cell based on the first random access resource associated with the first reference signal. The first random access resource may include a physical random access channel (PRACH) time-frequency resource, and may further include a random access preamble. The PRACH time-frequency resource may be represented by a PRACH transmission occasion (RACH occasion, RO). A RO represents a time-frequency resource used to transmit a preamble, and includes one or more subcarriers in the frequency domain and one or more time-domain symbols in the time domain. The terminal device transmits the preamble to the target cell in a PRACH time-frequency resource associated with a first reference signal. A first reference signal may correspond to one or more PRACH time-frequency resources, and the first reference signal may be associated with some or all of the preambles in the corresponding PRACH time-frequency resource. The target cell knows the association relationship between the reference signal and the random access resource. When the terminal device receives a random access request that is initiated based on the first random access resource, the target cell may determine a target beam that the terminal device wants to access. Thus, the target cell may send back first response information to the terminal device by using the target beam.

[0107] The network side may configure an association relationship between a reference signal and a random access resource for a terminal device in advance. The association relationship may be that a reference signal is associated with one or more random access resources, or that multiple reference signals are associated with multiple random access resources. Alternatively, one or more reference signals may be associated with one random access resource. The reference signal for configuring the association relationship is a reference signal of a neighboring cell. The random access resource for configuring the association relationship is also a random access resource of a neighboring cell. The network side may be a network device of a source cell, and the source cell may obtain the association relationship from a target cell. In this specification, the random access resource in the association relationship pre-configured by the network side may be a dedicated random access resource, i.e., a contention-free random access resource. The network side may be a source cell, and the source cell may obtain the association relationship from the target cell, and then configure the association relationship for the terminal device.

[0108] Alternatively, the source cell may receive a broadcast message or system information, such as SIB1 information, from the target cell, where the SIB1 information includes a configuration of random access resources, and the source cell transmits the configuration of random access resources of the target cell to the terminal device. The terminal device determines a random access resource based on the configuration of random access resources of the target cell, and initiates random access to the target cell. If the first reference signal is an SSB, the terminal device may determine a corresponding random access resource based on an SSB index according to a method defined in the protocol. If the first reference signal is a CSI-RS, the terminal device further needs to receive an association relationship between CSI-RS and an SSB transmitted by the network, determine an index of an SSB associated with the CSI-RS by using the association relationship between the CSI-RS and an SSB, and then determine a random access resource.

[0109] Alternatively, after receiving the indication information from the source cell, the terminal device may receive system information or a broadcast message in the target cell, obtain the configuration of the random access resource, and attempt to initiate random access in the target cell. For example, the terminal device is not configured with the association relationship between the multiple reference signals and the multiple random access resources, and does not receive the system information of the target cell from the source cell. This method may be used.

[0110] In S303, the terminal device considers the random access successful only after receiving the first response information returned by the target cell. Before receiving the first response information returned by the target cell, the terminal device needs to hold a hybrid automatic repeat request (HARQ) process until the terminal device returns second response information to the source cell.

[0111] If the terminal device does not receive the first response information returned by the target cell or if the terminal device does not receive the first response information returned by the target cell within an expected reception time window, the terminal device may return negative acknowledge (NACK) information to the source cell. The NACK information indicates a beam switching failure or indicates a first TCI state activation failure. The terminal device may perform wireless communication with the source cell based on a beam before the beam switching. For example, the terminal device receives a PDCCH based on a QCL relationship indicated by a TCI state used to communicate with the source cell. In another example, the terminal device communicates with the source cell based on a TCI state used by the source cell to transmit indication information. Before receiving the second response information returned by the terminal device, the source cell retains a connection configuration to the terminal device, such as retaining a context, carrier, BWP, and / or parameter configuration of each channel of the terminal device, so that the terminal device can quickly restore a communication connection with the source cell after the terminal device fails to switch beams or perform a cell handover.

[0112] After receiving the second response information, the source cell stops the TCI state used by the terminal device to communicate with the source cell.

[0113] In the cell handover method based on beam switching, the terminal device implements cell handover in a beam switching process. If a beam failure occurs in the terminal device during cell handover, the cell handover will also fail. Based on this, an embodiment of this application further provides a cell handover method for performing link recovery when a beam failure occurs during cell handover.

[0114] As shown in Fig. 5, the specific procedure of another cell handover method further provided by an embodiment of this application is described as follows: It can be understood that the embodiment in Fig. 5 and the embodiment in Fig. 3 are based on the same technical concept, and therefore may be referred to each other.

[0115] S501. A source cell sends indication information to a terminal device, and the terminal device receives the indication information from the source cell.

[0116] The instruction information instructs to activate the first TCI state. This step is the same as S301, and the description of S301 may be referred to.

[0117] S502. The terminal device initiates random access to the target cell according to the indication information.

[0118] This step is the same as S302, and the description of S302 may be referred to.

[0119] S503. When a beam failure occurs, the terminal device performs beam failure recovery based on a candidate beam configuration of the first reference signal.

[0120] The first TCI state indicates a first reference signal.

[0121] S504. When the terminal device is used to respond to beam failure recovery and receives response information returned by the target cell, the terminal device returns second response information to the source cell, and the source cell receives the second response information from the terminal device.

[0122] The second response information indicates that the first TCI state is successfully activated. For the second response information, refer to the description of the second response information in the embodiment in FIG.

[0123] According to the embodiment of FIG. 5, when a beam switching based cell handover fails, the terminal device can quickly attempt beam failure recovery in the target cell by using a candidate beam configuration, thereby improving the reliability of the terminal device during beam switching based cell handover.

[0124] After the beam failure, the terminal device sends a beam failure recovery request to the target cell. After determining the beam failure recovery, the target cell returns beam failure recovery request response information to the terminal device. The beam failure recovery request response information may also be referred to as a beam failure recovery request response. After the terminal device receives the beam failure recovery request response, or after the terminal device first successfully receives the PDCCH transmitted by the target cell, the terminal device considers that the target beam of the neighboring cell has been successfully switched or that the TCI state (i.e., the first TCI state) of the neighboring cell has been successfully activated. Before receiving the beam failure recovery request response returned by the target cell, the terminal device needs to hold a hybrid automatic repeat request (HARQ) process until the terminal device returns second response information to the source cell.

[0125] When the terminal device does not receive the beam failure recovery response information returned by the target cell, the terminal device may return NACK information to the source cell, and the NACK information indicates a beam switching failure or indicates a first TCI state activation failure. The terminal device may perform wireless communication with the source cell based on a beam before the beam switching. For example, the terminal device receives a PDCCH based on a QCL relationship indicated by the TCI state used to communicate with the source cell. Before receiving the second response information returned by the terminal device, the source cell retains a connection configuration to the terminal device, for example, retaining a context of the terminal device, so that the communication connection with the source cell can be quickly restored after the terminal device fails to perform a beam switching or a cell handover. After receiving the second response information, the source cell deactivates the TCI state used by the terminal device to communicate with the source cell.

[0126] Optionally, after receiving the random access response returned by the target cell, the terminal device may return second response information to the source cell to indicate that the first TCI state is successfully activated or that the beam switching is successfully performed. This implementation is the same as S303 in the embodiment in FIG. 3.

[0127] The following description describes one possible implementation of beam obstruction in S503.

[0128] After initiating random access to the target cell according to the instruction information, the terminal device accesses the target cell and performs wireless communication with the target cell by using the target beam. For example, the instruction information instructs to activate a first TCI state, and the terminal device receives a first PDCCH according to a QCL relationship indicated by the first TCI state. The terminal device performs beam quality detection on the target beam, and when a beam failure decision condition is satisfied, beam failure occurs.

[0129] The candidate beam configuration is pre-configured by the source cell for the terminal device. Optionally, the source cell transmits the candidate beam configuration to the terminal device, and the terminal device receives the candidate beam configuration from the source cell. The candidate beam configuration includes a candidate beam of the target beam, or the candidate beam configuration includes one or more reference signals related to the first reference signal. The first reference signal corresponds to the target beam, and the one or more reference signals have a one-to-one correspondence with the candidate beam.

[0130] The source cell may send a request message to the target cell, which is used to request a candidate beam configuration. The target cell receives the request message from the source cell and returns the candidate beam configuration to the source cell. If the source cell and the target cell are provided by the same network device, it is possible to know the candidate beam configuration without sending a request message. If the source cell and the target cell are not provided by the same network device, the network device of the source cell may request the candidate beam configuration. n The source cell may send a request message to the network device of the target cell via the F1-AP interface or F1-AP interface protocol. The request message sent by the source cell to the target cell may be used to request candidate beams of the target beam, or may be used to request candidate beams of other beams. For example, the source cell requests candidate beams of beam 1, beam 2, and beam 3 from the target cell according to the measurement results of the terminal device. Beam 1 corresponds to reference signal 1, beam 2 corresponds to reference signal 2, and beam 3 corresponds to reference signal 3. In other words, the source cell requests the relevant reference signal of reference signal 1, the relevant reference signal of reference signal 2, and the relevant reference signal of reference signal 3 from the target cell.

[0131] Optionally, the request message that the source cell may send to the target cell may further include one or more pieces of information: an identifier of the terminal device, configuration information of each physical channel of the terminal device, or measurement results of reference signals of neighboring cells by the terminal device.

[0132] The target cell returns a response message of the request message to the source cell, and the source cell receives the response message from the target cell. The response message of the request message includes the above-mentioned candidate beam configuration. Optionally, the response message of the request message may further include one or more information of uplink resources associated with the candidate beam, uplink resources individually associated with one or more reference signals, or downlink resources used for the terminal device to receive the beam failure recovery request response. The uplink resources may be dedicated uplink resources, and one candidate beam or one reference signal is associated with one dedicated uplink resource. Alternatively, the uplink resources may be contention-free PRACH resources, or may be scheduling request (SR) resources, or may be other PUCCH resources or other PUSCH resources. The downlink resources for receiving the beam failure recovery request response may be a PDCCH configuration for receiving the beam failure recovery request response.

[0133] The source cell may transmit candidate beam configurations to the terminal device, and may also transmit to the terminal device one or more of the above information included in a response message obtained from the target cell.

[0134] During the beam failure recovery in S503, the terminal device may perform the following operations: The terminal device measures one or more reference signals of the candidate beam configurations of the first reference signal, selects a second reference signal of the candidate beam configurations according to the measurement result, and sends a beam failure recovery request to the target cell based on the uplink resource associated with the second reference signal. The target cell returns a beam failure recovery request response to the terminal device, and the terminal device receives the beam failure recovery request response from the target cell based on the downlink resource used to receive the beam failure recovery request response and indicated by the source cell.

[0135] Based on the description of the above embodiment, the following description will describe in detail the cell handover method provided by one embodiment of this application with reference to a specific application scenario, as shown in FIG. 6.

[0136] S601. A source cell sends a physical layer measurement configuration to a terminal device, and the terminal device receives the physical layer measurement configuration from the source cell. S602. The terminal device measures a reference signal of a neighboring cell according to the physical layer measurement configuration.

[0137] S603. The terminal device transmits reference signal measurement results of neighboring cells to the source cell, and the source cell receives the reference signal measurement results of the neighboring cells from the terminal device.

[0138] S604. The source cell sends indication information to the terminal device, and in response, the terminal device receives indication information from the source cell.

[0139] The instruction information may be beam switching instruction information or may be an instruction to activate the TCI state of the target cell.

[0140] The source cell determines that the terminal device needs to perform cell handover based on the received reference signal measurement results of the neighboring cells, and may select a target cell for handover for the terminal device, and may instruct the terminal device to activate the TCI state by using the indication information, or may indicate the target cell for handover.

[0141] The indication information may be carried by using MAC-CE or may be carried by using physical layer signaling.

[0142] S605. After receiving the indication information, the terminal device initiates random access to the target cell.

[0143] The terminal device may initiate random access to the target cell based on a parameter indicated by the TCI state that the indication information indicates to be activated. For example, the terminal device initiates random access to the target cell based on a QCL relationship indicated by the TCI state.

[0144] S606. The target cell returns a random access response to the terminal device. In response, the terminal device receives a random access response from the target cell.

[0145] Alternatively, the target cell may alternatively send back one DCI to the terminal device, and in response, the terminal device receives a DCI from the target cell, which is used to respond to the random access in S605.

[0146] S607. After receiving the random access response, the terminal device returns an ACK message to the source cell, and in response, the source cell receives an ACK message from the terminal device.

[0147] The ACK message is used to indicate that the TCI has been successfully activated or the beam has been successfully switched in response to the indication information in S604.

[0148] The ACK message may be carried in the MAC-CE.

[0149] Before receiving the random access response of the target cell, the terminal device continues communication with the source cell. If the beam switching is unsuccessful, in other words, if the cell handover is unsuccessful, for example, if the random access response from the target cell is not received, the terminal device performs wireless communication with the source cell to ensure that the radio link is not interrupted.

[0150] Before receiving the ACK message, the source cell prevents the TCI used to communicate with the terminal from being stopped. After receiving the ACK message, the source cell stops the TCI used to communicate with the terminal. In this way, when the handover of the terminal fails, the connection to the terminal device can be restored in a timely manner, thereby ensuring normal communication of the terminal device.

[0151] In one possible embodiment, after handing over a terminal to a target cell, a beam failure may occur. As shown in Figure 7, the terminal device receives L1 / L2 indication information from a source cell, which indicates to activate the TCI state of the target cell. The terminal device initiates random access to the target cell and establishes a connection to the target cell by using the target beam, but a beam failure occurs. In this case, the cell handover method provided by this embodiment of the application may be shown in Figure 8.

[0152] S801. A source cell sends a physical layer measurement configuration to a terminal device, and the terminal device receives a physical layer measurement configuration from the source cell.

[0153] S802. A terminal device measures a reference signal of a neighboring cell based on a physical layer measurement configuration.

[0154] S803. The terminal device transmits reference signal measurement results of neighboring cells to the source cell, and the source cell receives the reference signal measurement results of the neighboring cells from the terminal device.

[0155] S804. The source cell sends indication information to the terminal device, and in response, the terminal device receives indication information from the source cell.

[0156] The instruction information may be beam switching instruction information or may be an instruction to activate the TCI state of the target cell.

[0157] The source cell determines that the terminal device needs to perform cell handover based on the received reference signal measurement results of the neighboring cells, and may select a target cell for handover for the terminal device, and may instruct the terminal device to activate the TCI state by using the indication information, or may indicate the target cell for handover.

[0158] The indication information may be carried by using MAC-CE, or may be carried by using physical layer signaling.

[0159] S805. After receiving the indication information, the terminal device initiates random access to the target cell.

[0160] The terminal device may initiate random access to the target cell based on a parameter indicated by the TCI state that the indication information indicates to be activated. For example, the terminal device initiates random access to the target cell based on a QCL relationship indicated by the TCI state.

[0161] S806. The terminal device determines beam obstructions.

[0162] The terminal device may measure the target beam to which it is to be switched. When a condition is satisfied, the terminal device determines that a beam obstruction occurs.

[0163] S807. The terminal device measures candidate beams of the target beam based on preconfigured information, and selects a new beam according to the measurement results.

[0164] S808. The terminal device sends a beam failure recovery request to the target cell via uplink resources associated with the new beam.

[0165] S809. The terminal device receives a beam failure recovery request response from the target cell via downlink resources based on preconfigured information.

[0166] The terminal device may obtain one or more types of information about the candidate beams, uplink resources, or downlink resources of the target beam from preconfigured information, which may be transmitted to the terminal device in advance by the network side, which may be, for example, the source cell. The source cell may obtain the information from the target cell.

[0167] S810. The terminal device returns an ACK message to the source cell. In response, the source cell receives an ACK message from the terminal device.

[0168] The ACK message is used to indicate that the TCI has been successfully activated or the beam has been successfully switched in response to the indication information in S804.

[0169] The ACK message may be carried in the MAC-CE.

[0170] It should be noted that the application scenario examples in this application only show some of multiple possible implementations, and are intended to better understand and explain the method in this application. Those skilled in the art can obtain some advanced form examples according to the reference signal indication method provided by this application.

[0171] In the embodiments provided by this application, the methods provided by the embodiments of this application are described separately in terms of a network device, a terminal device, and the interaction between the network device and the terminal device. To implement the functions in the methods provided by the above embodiments of this application, the network device or the terminal device may include a hardware configuration and / or a software module, and may implement the above functions in the form of a hardware configuration, a software module, or a combination of a hardware configuration and a software module. Whether a particular function among the above functions is implemented by a hardware configuration, a software module, or a combination of a hardware configuration and a software module depends on the specific application and design constraints of the technical solution.

[0172] Based on the same technical concept, an embodiment of this application further provides a communication device 900, as shown in FIG. 9. The communication device 900 may be a terminal device or a network device of a source cell, or may be an apparatus in the terminal device or the network device of the source cell, or may be an apparatus that may be used in conjunction with the terminal device or the network device of the source cell. In one design, the communication device 900 may include modules that have a one-to-one correspondence with the execution of the method / operation / step / action performed by the terminal device or the network device in the above method embodiments. The modules may be hardware circuits, software, or may be implemented by a combination of hardware circuits and software. In one design, the device may include a processing module 901 and a communication module 902. The processing module 901 is configured to call the communication module 902 to perform a receiving function and / or a transmitting function. Furthermore, the communication module 902 may also be referred to as a transceiver module, and may include a receiving module and a transmitting module. The receiving module is configured to perform a receiving operation in a method embodiment, and the transmitting module is configured to perform a sending operation in a method embodiment. In this embodiment of the application, the processing module performing a sending operation or a receiving operation by using the communication module may be understood to mean that the processing module delivers an instruction to the communication module, and the communication module performs the sending operation or the receiving operation, or the processing module instructs the communication module to perform the sending operation or the receiving operation.

[0173] When the apparatus is configured to execute a method executed by a terminal device, in one embodiment, the communication module 902 is configured to receive instruction information from a source cell, the instruction information instructing to activate a first TCI state, the processing module 901 is configured to initiate random access to the target cell according to the instruction information, and when the communication module determines that it has received first response information returned by the target cell, is configured to return second response information to the source cell by using the communication module 902, the second response information indicating that the activation of the first TCI state has been successful.

[0174] Optionally, the first response information includes response information used to respond to the random access. For example, the first response information may be a random access response or other information that may be used to respond to the random access. The terminal device may consider the random access successful only after receiving the response information used to respond to the random access and returned by the target cell, and may further return the second response information to the source cell. The source cell may consider the beam switching successful or the first TCI activation successful only after receiving the second response information. In this way, it is possible to improve the reliability of the cell handover.

[0175] In another embodiment, the communication module 902 is configured to receive instruction information from the source cell, the instruction information instructing to activate a first TCI state, and the processing module 901 is configured to initiate random access to the target cell according to the instruction information, and perform beam failure recovery based on a candidate beam configuration of a first reference signal when a beam failure occurs. The first TCI state indicates the first reference signal.

[0176] Based on two embodiments, some of the alternative implementations are provided.

[0177] Optionally, when the first TCI state indicates a first reference signal and initiates random access to the target cell according to the instruction information, the processing module 901 is configured to initiate random access to the target cell based, in particular, on a first random access resource associated with the first reference signal.

[0178] Optionally, a plurality of reference signals of the target cell are associated with a plurality of random access resources, and the first reference signal is one of the plurality of reference signals.

[0179] The source cell may configure an association relationship between the reference signal and the random access resource for the terminal device in advance, and the processing module 901 is further configured to obtain the association relationship from the source cell. The association relationship may be obtained by the source cell by using a received system message of the target cell. The processing module 901 is configured to determine the random access resource based on the configuration of the random access resource of the target cell, and initiate random access to the target cell. Alternatively, after receiving the indication information from the source cell by using the communication module 902, the processing module 901 may receive system information or a broadcast message in the target cell, obtain the configuration of the random access resource, and attempt to initiate random access in the target cell.

[0180] Optionally, the first TCI state indicates a first reference signal, and the processing module 901 is further configured to perform beam failure recovery based on a candidate beam configuration of the first reference signal when a beam failure occurs after initiating random access to the target cell.

[0181] In one possible design, the first response information includes response information used to respond to a beam obstruction recovery. For example, the first response information may include recoveryThe response information may be a request response, or other information that may be used to respond to beam failure recovery. After the terminal device performs a beam switching based cell handover, a beam switching failure may occur. After receiving the response information used to respond to the beam failure recovery, the terminal device returns to the source cell a second response message indicating that the first TCI state has been successfully activated, that the cell handover has been successful, or that the beam switching has been successful. In this way, it is possible to further ensure the reliability and robustness of the successful cell handover.

[0182] Optionally, when performing beam failure recovery based on candidate beam configurations of a first reference signal, the processing module 901 is configured, in particular, to measure one or more reference signals among the candidate beam configurations of the first reference signal, select a second reference signal among the candidate beam configurations according to the measurement result, and send a beam failure recovery request to the target cell based on an uplink resource associated with the second reference signal.

[0183] Optionally, the communication module 902 is further configured to receive configuration information from the source cell, the configuration information including downlink resources used to receive the beam failure recovery request response. The processing module 901 is further configured to receive a beam failure recovery request response from the target cell based on the downlink resources.

[0184] In one possible design, the processing module 901 is further configured to communicate with the source cell based on a second TCI state used before successfully activating the first TCI state if the target cell does not receive the first response information back from the target cell, for example, to receive a PDCCH from the source cell based on a QCL relationship indicated by the second TCI state.

[0185] The communication module 902 is further configured to perform other receiving or transmitting steps or operations performed by the terminal device in the above method embodiments. The processing module 901 may be further configured to perform other corresponding steps or operations performed by the terminal device in the above method embodiments besides transmitting and receiving. Details will not be described repeatedly in this specification.

[0186] When the apparatus is configured to execute a method performed by a network device, the processing module 901 is configured to use the communication module 902 to send instruction information to the terminal device based on the quasi-co-location QCL relationship indicated by the first TCI state, the instruction information instructing the terminal device to activate a second TCI state, the instruction information being used by the terminal device to initiate random access to the target cell, and the communication module 902 is further configured to receive an acknowledgement from the terminal device, the acknowledgement indicating that the activation of the second TCI state has been successful.

[0187] Generally, the acknowledgement may be sent by using physical layer signaling or may be sent by using MAC layer signaling. The delay of the physical layer and the MAC layer is smaller than the delay of layer 3, i.e., the delay of the RRC layer. Therefore, the delay of the cell handover can be reduced.

[0188] In one possible design, the processing module 901 is configured to communicate with the terminal device by using the QCL relationship indicated by the first TCI state if a negative acknowledgment is received from the terminal device.

[0189] The communication module 902 is further configured to perform other receiving or transmitting steps or operations performed by the source cell in the above method embodiments. The processing module 901 may be further configured to perform other corresponding steps or operations performed by the source cell in the above method embodiments besides transmitting and receiving. Details are not repeated in this specification.

[0190] The division into multiple modules in this embodiment of the present application is one example and is merely a logical division of functions, and other divisions may be used in actual implementation. In addition, the functional modules in one embodiment of the present application may be integrated into one processor, and each of the multiple modules may exist physically alone, or two or more modules may be integrated into one module. The integrated modules may be implemented in the form of hardware or software functional modules.

[0191] FIG. 10 shows a communication device 1000 according to an embodiment of this application. The communication device 1000 is configured to implement the functions of the terminal device or the network device in the above method. When implementing the functions of the source cell, the communication device may be the network device of the source cell, may be an apparatus in the network device of the source cell, or may be an apparatus that may be used in coordination with the network device of the source cell. When implementing the functions of the terminal device, the communication device may be the terminal device, may be an apparatus in the terminal device, or may be an apparatus that may be used in coordination with the terminal device. The communication device may be a chip system. In this embodiment of this application, the chip system may include a chip, or may include a chip and other individual components. The communication device 1000 includes at least one processor 1020, which is configured to implement the functions of the terminal device or the network device of the source cell in the methods provided by the embodiments of this application. The communication device 1000 may further include a communication interface 1010. In this embodiment of the application, the communication interface may be a transceiver, a circuit, a bus, a module, or other type of communication interface, configured to communicate with other devices via a transmission medium. The transceiver may include a receiver and a transmitter. The receiver is configured to implement a receiving operation in the method embodiment, and the transmitter is configured to implement a transmitting operation in the method embodiment. Other operations are performed by a processor. When the communication device is a chip system, the communication interface 1010 may include an input interface and an output interface. The input interface correspondingly performs a receiving operation, and the output interface correspondingly performs a transmitting operation.

[0192] For example, the communication interface 1010 is used by the device in the communication device 1000 to communicate with other devices. For example, when the communication device 1000 is a network device, the other device may be a terminal device. When the communication device 1000 is a terminal device, the other device may be a devicemay be a network device. The processor 1020 is configured to transmit and receive data by the communication interface 1010 and implement the method in the above method embodiment. For example, when implementing the function of the terminal device, in one embodiment, the communication interface 1010 is configured to receive instruction information from a source cell, the instruction information instructing to activate a first TCI state. The processor 1020 is configured to initiate a random access to a target cell according to the instruction information, and is configured to return second response information to the source cell by the communication interface 1010 when receiving first response information returned by the target cell, the second response information indicating that the first TCI state is successfully activated. Optionally, the first response information includes response information used to respond to the random access. For example, the first response information may be a random access response or other information that may be used to respond to the random access. The terminal device may consider the random access successful only after receiving the response information used to respond to the random access and returned by the target cell, and may further return the second response information to the source cell. The source cell may consider the beam switching successful or the first TCI activation successful only after receiving the second response information. In this way, it is possible to improve the reliability of the cell handover. In another embodiment, the communication interface 1010 is configured to receive instruction information from the source cell, the instruction information instructing to activate the first TCI state, and the processor 1020 is configured to initiate the random access to the target cell according to the instruction information, and perform beam failure recovery based on the candidate beam configuration of the first reference signal when a beam failure occurs, the first TCI state indicating the first reference signal. Based on those two embodiments, some of a plurality of selective implementations are provided.

[0193] Optionally, when the first TCI state indicates a first reference signal and initiates random access to the target cell according to the instruction information, the processor 1020 is configured to initiate random access to the target cell based, in particular, on a first random access resource associated with the first reference signal.

[0194] Optionally, a plurality of reference signals of the target cell are associated with a plurality of random access resources, and the first reference signal is one of the plurality of reference signals.

[0195] The source cell may configure an association relationship between the reference signal and the random access resource for the terminal device in advance, and the processor 1020 is further configured to obtain the association relationship from the source cell. The association relationship may be obtained by the source cell by using a received system message of the target cell. The processor 1020 is configured to determine the random access resource based on the configuration of the random access resource of the target cell, and initiate random access to the target cell. Alternatively, after receiving the indication information from the source cell by the communication interface 1010, the processor 1020 may receive system information or a broadcast message in the target cell, obtain the configuration of the random access resource, and attempt to initiate random access in the target cell.

[0196] Optionally, the first TCI state indicates a first reference signal, and the processor 1020 is further configured to perform beam failure recovery based on a candidate beam configuration of the first reference signal when a beam failure occurs after initiating random access to the target cell.

[0197] In one possible design, the first response information includes response information used to respond to the beam failure recovery. For example, the first response information may be a beam failure recovery request response, or other information that may be used to respond to the beam failure recovery. After the terminal device performs a beam switching based cell handover, a beam switching failure may occur. After receiving the response information used to respond to the beam failure recovery, the terminal device sends back to the source cell a second response message indicating that the first TCI state has been successfully activated, that the cell handover has been successful, or that the beam switching has been successful. In this manner, it is possible to further ensure the reliability and robustness of the successful cell handover.

[0198] Optionally, when performing beam failure recovery based on candidate beam configurations of the first reference signal, the processor 1020 is configured, in particular, to measure one or more reference signals among the candidate beam configurations of the first reference signal, select a second reference signal among the candidate beam configurations according to the measurement result, and send a beam failure recovery request to the target cell based on an uplink resource associated with the second reference signal.

[0199] Optionally, the communication module 1010 is further configured to receive configuration information from the source cell, the configuration information including downlink resources used to receive the beam failure recovery request response. The processor 1020 is further configured to receive a beam failure recovery request response from the target cell based on the downlink resources.

[0200] In one possible design, the processor 1020 may be further configured to communicate with the source cell based on a second TCI state used before successfully activating the first TCI state if the processor 1020 does not receive the first response information returned by the target cell, for example, to receive a PDCCH from the source cell based on a QCL relationship indicated by the second TCI state.

[0201] The communication interface 1010 is further configured to perform other receiving or transmitting steps or operations performed by the terminal device in the above method embodiments. The processor 1020 may be further configured to perform other corresponding steps or operations performed by the terminal device in the above method embodiments besides transmitting and receiving. Details will not be described repeatedly in this specification.

[0202] When the apparatus is configured to execute a method performed by a network device, the processor 1020 is configured to send, via the communication interface 1010, indication information to the terminal device based on the quasi-co-location QCL relationship indicated by the first TCI state, the indication information instructing the terminal device to activate a second TCI state, the indication information being used by the terminal device to initiate random access to the target cell, and the communication interface 1010 is further configured to receive an acknowledgement from the terminal device, the acknowledgement indicating that the activation of the second TCI state has been successful.

[0203] Generally, the acknowledgement may be sent by using physical layer signaling or may be sent by using MAC layer signaling. The delay of the physical layer and the MAC layer is smaller than the delay of layer 3, i.e., the delay of the RRC layer. Therefore, the delay of the cell handover can be reduced.

[0204] In one possible design, the processor 1020 is configured to communicate with the terminal device by using the QCL relationship indicated by the first TCI state if a negative acknowledgment is received from the terminal device.

[0205] The communication interface 1010 is further configured to perform other receiving or transmitting steps or operations performed by the source cell in the above method embodiments. The processor 1020 may be further configured to perform other corresponding steps or operations performed by the source cell in the above method embodiments besides transmitting and receiving. Details are not repeated in this specification.

[0206] The communication device 1000 may further include at least one memory 1030 configured to store program instructions and / or data. The memory 1030 is coupled to the processor 1020. The coupling in this embodiment of the application may be an indirect coupling or communication connection between the devices, units, or modules in an electrical, mechanical, or other form, and is used for information exchange between the devices, units, or modules. The processor 1020 may cooperate with the memory 1030. The processor 1020 may execute the program instructions stored in the memory 1030. At least one of the at least one memory may be included in the processor.

[0207] The specific connection medium between the communication interface 1010, the processor 1020, and the memory 1030 is not limited in this embodiment of the application. In this embodiment of the application, the memory 1030, the processor 1020, and the communication interface 1010 are connected by a bus 1040 in FIG. 10. The bus is represented by using a bold line in FIG. 10. The connection manner between the other components is only one example for explanation and is not limited. The bus may be classified into an address bus, a data bus, a control bus, and the like. For ease of representation, only one bold line is used to represent the bus in FIG. 10, but this does not mean that there is only one bus or that there is only one type of bus.

[0208] When the communication device 900 and the communication device 1000 are, in particular, chips or chip systems, the communication module 902 and the communication interface 1010 may output or receive baseband signals. When the communication device 900 and the communication device 1000 are, in particular, devices, the communication module 902 and the communication interface 1010 may output or receive radio frequency signals. In this embodiment of the application, the processor may be a general-purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. The processor is capable of implementing or executing the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the methods disclosed with reference to the embodiments of this application may be performed or completed directly by a hardware processor, or may be performed or completed by using a combination of hardware and software modules in the processor.

[0209] In this embodiment of the application, the memory 1030 may be a non-volatile memory such as a hard disk drive (HDD) or a solid-state drive (SSD), or a volatile memory such as a random access memory (RAM). The memory may be any other medium, including but not limited to, that may be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Alternatively, the memory in this embodiment of the application may be a circuit or any other device capable of implementing a memory function and configured to store program instructions and / or data.

[0210] Some or all of the operations and functions performed by the terminal or the network device described in the above method embodiments of this application may be achieved by using chips or integrated circuits.

[0211] To implement the functions of the communication device in Fig. 9 or Fig. 10, an embodiment of this application further provides a chip including one or more processors, which is configured to assist the communication device in implementing the functions related to the terminal or source cell in the above method embodiments. In one possible design, the chip is connected to or includes a memory. The memory is configured to store program instructions and data required for the communication device.

[0212] One embodiment of the present application provides a computer-readable storage medium, which stores a computer program, the computer program including instructions used to execute the above method embodiments.

[0213] An embodiment of this application provides a computer program product including instructions, which, when executed by a computer, implements the above method embodiments. Those skilled in the art should understand that the embodiments of this application may be provided as a method, a system, or a computer program product. Thus, this application may take the form of a hardware-only embodiment, a software-only embodiment, or an embodiment using a combination of software and hardware. Furthermore, this application may take the form of a computer program product, which is implemented by one or more computer usable storage media including computer usable program code (including, but not limited to, disk memory, CD-ROM, optical memory, etc.).

[0214] This application is described with reference to flowcharts and / or block diagrams of methods, systems, and computer program products according to embodiments of this application. It should be understood that computer program instructions may be used to implement each process and / or each block in the flowcharts and / or block diagrams, and combinations of processes and / or blocks in the flowcharts and / or block diagrams. These computer program instructions may be provided to a processor of a general purpose computer, a special purpose computer, an embedded processor, or other programmable data processing device to generate a machine, whereby the instructions executed by the processor of the computer or other programmable data processing device generate an apparatus for implementing a particular function of one or more processes in the flowcharts and / or one or more blocks in the block diagrams.

[0215] These computer program instructions may alternatively be stored in a computer readable memory capable of causing a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer readable memory generate an artifact that includes an instruction apparatus that implements a particular function(s) in one or more processes of the flowcharts and / or one or more blocks of the block diagrams.

[0216] These computer program instructions may alternatively be loaded into a computer or other programmable data processing device, whereby a series of operational steps are executed on the computer or other programmable device, thereby generating a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing a particular function in one or more processes in the flowcharts and / or one or more blocks in the block diagrams.

[0217] Some of these applications Embodiments of the present invention Although the present invention has been described, once those skilled in the art are familiar with the basic inventive concept, they may make changes and modifications to these multiple embodiments. It is therefore intended that the following claims be interpreted to cover the preferred embodiments and all such changes and modifications that fall within the scope of this application.

[0218] Those skilled in the art will appreciate that multiple embodiments of this application Range It is apparent that various modifications and variations can be made to the embodiments of this application without departing from the spirit and scope of the present invention. Thus, this application intends to cover those modifications and variations of the embodiments of this application as long as they fall within the scope of protection defined by the following claims of this application and their equivalent techniques.

Claims

1. A cell handover method performed by a terminal device, comprising: receiving a configuration of random access resources of a target cell, the configuration of random access resources being used to determine the random access resources of the target cell; receiving, from a source cell, an association relationship between a first random access resource and a first reference signal; receiving indication information from the source cell, the indication information indicating a first transmission configuration indicator (TCI) state or a cell handover, the indication information including one or more of the following: an identifier of a terminal device, an identifier of a neighboring cell, an identifier of a bandwidth portion (BWP), an identifier of a carrier, an identifier of a random access resource, and an identifier of a target beam; initiating random access to a target cell according to the indication information by using the first random access resource associated with the first reference signal; performing communication in the target cell using the first TCI state; returning second response information to the source cell when receiving first response information returned by the target cell, the second response information indicating that the first TCI state has been successfully initiated; The method includes:

2. the first TCI state indicates a first reference signal; 2. The method of claim 1, wherein initiating random access to a target cell according to the indication information comprises initiating the random access to the target cell based on a first random access resource associated with the first reference signal.

3. The method of claim 2 , wherein the first random access resource comprises a physical random access channel time-frequency resource and / or a random access preamble.

4. The method according to claim 2 or 3, wherein an association relationship exists between a plurality of reference signals and a plurality of random access resources of the target cell, and the first reference signal is one of the plurality of reference signals.

5. The method comprises: receiving configuration information from the source cell, the configuration information including a physical layer measurement configuration, the physical layer measurement configuration including synchronization signal block (SSB) information of a neighboring cell; measuring the neighboring cell's SSB according to the physical layer measurement configuration; reporting SSB measurement results of the neighboring cells to the source cell; The method according to any one of claims 1 to 4, wherein the indication information is determined by the source cell based on the SSB measurement results.

6. The method according to any one of claims 1 to 4, wherein the indication information is carried by a Media Access Control Element (MAC-CE).

7. The method according to any one of claims 1 to 5, wherein the instruction information is used to instruct to activate the first TCI state.

8. A terminal device configured to execute a method according to any one of claims 1 to 7.

9. A computer program which, when executed by a communications device, causes the communications device to carry out a method according to any one of claims 1 to 7.

10. A computer-readable storage medium containing instructions which, when executed by a communications device, cause the communications device to perform a method according to any one of claims 1 to 7.

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