EP-4738913-A1 - BEAM-BASED COMMUNICATION METHOD AND RELATED APPARATUS

EP4738913A1EP 4738913 A1EP4738913 A1EP 4738913A1EP-4738913-A1

Abstract

Embodiments of this application provide a beam-based communication method and a related apparatus. The method includes: A terminal device receives first indication information of a transmission configuration indicator, where the first indication information is used for activating a TCI state of a candidate cell, the activated TCI state of the candidate cell includes a first TCI state, and the first TCI state includes one or more TCI states; and the terminal device measures a first synchronization signal block SSB based on the first indication information, to obtain a first measurement result, where the first SSB and at least one channel state information reference signal CSI-RS have a quasi-colocation QCL relationship, the at least one CSI-RS is a reference signal in QCL information of the first TCI state, a type of the QCL information of the first TCI state is type A and/or type D, the first SSB is an SSB of the candidate cell, and the at least one CSI-RS is a CSI-RS of the candidate cell. An SSB associated with a TCI state is measured in advance by using the first indication information, to quickly activate the TCI state. Therefore, communication interruption time of the terminal device is reduced, and communication quality of the terminal device is improved.

Inventors

YUAN, Shitong
ZHANG, JIAYIN
CHEN, LEI

Assignees

Huawei Technologies Co., Ltd.

Dates

Publication Date: 20260506
Application Date: 20240809

Claims (20)

A beam-based communication method, comprising: receiving, by a terminal device, first indication information of a transmission configuration indicator, wherein the first indication information is used for activating a TCI state of a candidate cell, the activated TCI state of the candidate cell comprises a first TCI state, and the first TCI state comprises one or more TCI states; and measuring, by the terminal device, a first synchronization signal block SSB based on the first indication information, to obtain a first measurement result, wherein the first SSB and at least one channel state information reference signal CSI-RS have a quasi-colocation QCL relationship, the at least one CSI-RS is a reference signal in QCL information of the first TCI state, a type of the QCL information of the first TCI state is type A and/or type D, the first SSB is an SSB of the candidate cell, and the at least one CSI-RS is a CSI-RS of the candidate cell.
The method according to claim 1, wherein the method further comprises: receiving, by the terminal device, a handover command, wherein the handover command instructs the terminal device to be handed over from a serving cell to the candidate cell, the handover command indicates a second TCI state, and the second TCI state belongs to the first TCI state; measuring, by the terminal device based on the first measurement result, a reference signal corresponding to the second TCI state, to obtain a second measurement result; and activating, by the terminal device, the second TCI state based on the second measurement result.
The method according to claim 1 or 2, wherein measuring, by the terminal device, the first synchronization signal block SSB based on the first indication information, to obtain the first measurement result comprises: determining, by the terminal device, the QCL information of the first TCI state based on the first indication information; determining, by the terminal device based on the QCL information of the first TCI state, the at least one CSI-RS corresponding to the first TCI state; determining, by the terminal device, a third TCI state based on configuration information of the at least one CSI-RS, wherein the configuration information of the at least one CSI-RS comprises identification information of the third TCI state, and the third TCI state is used for determining a reception parameter for receiving a reference signal corresponding to the first TCI state; determining, by the terminal device, the first SSB based on QCL information of the third TCI state, wherein the QCL information of the third TCI state comprises index information of the first SSB; and measuring, by the terminal device, the first SSB, to obtain the first measurement result.
The method according to claim 3, wherein a quasi-colocation QCL type of the third TCI state is type C and type D.
The method according to any one of claims 1 to 4, wherein the first TCI state further comprises a fourth TCI state, and a quasi-colocation QCL type of the fourth TCI state is type C and type D.
The method according to claim 5, wherein measuring, by the terminal device, the first synchronization signal block SSB based on the first indication information, to obtain the first measurement result comprises: determining, by the terminal device, QCL information of the fourth TCI state based on the first indication information, wherein the QCL information of the fourth TCI state indicates that a source reference signal of the fourth TCI state comprises an SSB; determining, by the terminal device, the first SSB based on the QCL information of the fourth TCI state, wherein the QCL information of the fourth TCI state comprises the index information of the first SSB; and measuring, by the terminal device, the first SSB, to obtain the first measurement result.
The method according to any one of claims 1 to 6, wherein before receiving, by the terminal device, the first indication information, the method further comprises: receiving, by the terminal device, configuration information, wherein the configuration information comprises QCL information of the TCI state of the candidate cell and/or related information of the CSI-RS of the candidate cell.
The method according to any one of claims 1 to 7, wherein before measuring, by the terminal device based on the first measurement result, the reference signal corresponding to the second TCI state, to obtain the second measurement result, the method further comprises: determining, as a default beam by the terminal device based on the first measurement result, a TCI corresponding to the first SSB, wherein the default beam is used for signal transmission with a serving cell after handover, and the serving cell after handover is the candidate cell.
The method according to any one of claims 1 to 8, wherein a TCI corresponding to a reference signal in the first TCI state is not allowed to be indicated by the handover command, or a TCI corresponding to a reference signal in the first TCI state is not allowed to be used for data transmission after the handover command is received.
A beam-based communication method, comprising: receiving, by a terminal device, a handover command, wherein the handover command instructs the terminal device to be handed over from a serving cell to a candidate cell; and determining, by the terminal device, a default beam when any one or more of first conditions are satisfied, wherein the default beam is used for signal transmission with a serving cell after handover, and the serving cell after handover is the candidate cell, wherein the first condition comprises: the handover command does not indicate a transmission configuration indicator TCI, and the terminal device determines a TATA based on a measurement result of a downlink reference signal; or the handover command does not indicate a timing advance TA, and the terminal device determines the TA based on a measurement result of a downlink reference signal; or the handover command indicates a TA, and the terminal device determines that a TA of the candidate cell is the same as a TA of the serving cell; or the handover command indicates a TA, and the terminal device determines that a TA of the candidate cell is 0; or a TCI indicated in the handover command is not activated in advance; or a source reference signal of a TCI indicated in the handover command comprises a channel state information reference signal CSI-RS, and the terminal device does not measure the CSI-RS before receiving the handover command; or the handover command indicates a TCI, the terminal device feeds back a hybrid automatic repeat request acknowledgment HARQ-ACK based on the handover command, and a moment at which the HARQ-ACK is fed back does not reach a beam effective time point.
The method according to claim 10, wherein determining, by the terminal device, the default beam when one or more of the following first conditions are satisfied comprises: the first condition comprises: the handover command does not indicate the transmission configuration indicator TCI, and the terminal device determines the TA based on the measurement result of the downlink reference signal; or the handover command does not indicate the timing advance TA, and the terminal device determines the TA based on the measurement result of the downlink reference signal; determining, by the terminal device, the default beam comprises: determining, by the terminal device, a second synchronization signal block SSB as the default beam, wherein the second SSB is an SSB of the candidate cell, and the second SSB is used for measuring the TA of the candidate cell, or the second SSB and a reference signal for measuring the TA of the candidate cell have a quasi-colocation QCL relationship.
The method according to claim 11, wherein determining, by the terminal device, the default beam when one or more of the following first conditions are satisfied comprises: the first condition comprises: the handover command indicates the TA, and the terminal device determines that the TA of the candidate cell is the same as the TA of the serving cell; or the handover command indicates the TA, and the terminal device determines that the TA of the candidate cell is 0; determining, by the terminal device, the default beam comprises: determining, by the terminal device based on the handover command, a fifth TCI state indicated by the handover command; and determining, by the terminal device, a first reference signal as the default beam, or determining, as the default beam by the terminal device, a synchronization signal block SSB associated with a first reference signal, wherein the first reference signal is a reference signal indicated by quasi-colocation QCL information of the fifth TCI state.
The method according to claim 12, wherein a type of the QCL information of the third TCI state is type D; and the first reference signal is a channel state information reference signal CSI-RS.
The method according to claim 11, wherein determining, by the terminal device, the default beam when one or more of the following first conditions are satisfied comprises: the first condition comprises: the handover command indicates the TA, and the terminal device determines that the TA of the candidate cell is the same as the TA of the serving cell; or the handover command indicates the TA, and the terminal device determines that the TA of the candidate cell is 0; determining, by the terminal device, the default beam comprises: determining, by the terminal device from synchronization signal blocks SSBs that are of the candidate cell and that are reported by the terminal device to a network device, an SSB having a highest reference signal received power; and determining, as the default beam by the terminal device, the SSB having the highest reference signal received power.
The method according to claim 11, wherein the first condition further comprises: the serving cell comprises one primary cell and at least one secondary cell, or the candidate cell comprises one primary cell and at least one secondary cell, and the primary cell and the secondary cell belong to a same timing advance group TAG; and determining, by the terminal device, the default beam comprises: determining, as the default beam by the terminal device, a synchronization signal block SSB for measuring a TA of the primary cell.
The method according to claim 15, wherein the default beam is used by the primary cell for signal transmission, and the default beam is further used by the secondary cell for signal transmission; and the primary cell and the secondary cell are configured in a first set, and the first set is used for configuring a plurality of cells to update a beam based on at least one beam indication.
A communication apparatus, comprising: a transceiver module, configured to receive first indication information of a transmission configuration indicator, wherein the first indication information is used for activating a TCI state of a candidate cell, the activated TCI state of the candidate cell comprises a first TCI state, and the first TCI state comprises one or more TCI states; and a processing module, configured to measure a first synchronization signal block SSB based on the first indication information, to obtain a first measurement result, wherein the first SSB and at least one channel state information reference signal CSI-RS have a quasi-colocation QCL relationship, the at least one CSI-RS is a reference signal in QCL information of the first TCI state, a type of the QCL information of the first TCI state is type A and/or type D, the first SSB is an SSB of the candidate cell, and the at least one CSI-RS is a CSI-RS of the candidate cell.
The communication apparatus according to claim 17, wherein the transceiver module is further configured to receive a handover command, wherein the handover command instructs the terminal device to be handed over from a serving cell to the candidate cell, the handover command indicates a second TCI state, and the second TCI state belongs to the first TCI state; the processing module is further configured to measure, based on the first measurement result, a reference signal corresponding to the second TCI state, to obtain a second measurement result; and the processing module is further configured to activate the second TCI state based on the second measurement result.
The communication apparatus according to claim 17 or 18, wherein the processing module is further configured to determine the QCL information of the first TCI state based on the first indication information; the processing module is further configured to determine, based on the QCL information of the first TCI state, the at least one CSI-RS corresponding to the first TCI state; the processing module is further configured to determine a third TCI state based on configuration information of the at least one CSI-RS, wherein the configuration information of the at least one CSI-RS comprises identification information of the third TCI state, and the third TCI state is used for determining a reception parameter for receiving a reference signal corresponding to the first TCI state; the processing module is further configured to determine the first SSB based on QCL information of the third TCI state, wherein the QCL information of the third TCI state comprises index information of the first SSB; and the processing module is further configured to measure the first SSB to obtain the first measurement result.
The communication apparatus according to claim 19, wherein a quasi-colocation QCL type of the third TCI state is type C and type D.

Description

This application claims priority to Chinese Patent Application No. 202311019046.3, filed with the China National Intellectual Property Administration on August 11, 2024 and entitled "BEAM-BASED COMMUNICATION METHOD AND RELATED APPARATUS", which is incorporated herein by reference in its entirety. TECHNICAL FIELD This application relates to the field of communication technologies, and in particular, to a beam-based communication method and a related apparatus. BACKGROUND The 5th generation (5th generation, 5G) mobile communication system uses high-frequency communication, that is, uses ultra-high frequency band (greater than 6 GHz) signals for data transmission. A main problem of the high-frequency communication is that signal energy sharply decreases with a transmission distance, resulting in a short signal transmission distance. To overcome this problem, high-frequency communication uses an analog beam technology, and adopts a large-scale antenna array for processing, to concentrate signal energy within a small range, to form a beam-like signal known as an analog beam (referred to as a beam for short), thereby extending a transmission distance. A network device may generate different beams pointing in different transmission directions. During downlink data transmission, the network device sends data to a terminal device by using a specific beam, and notifies the terminal device of information about a transmission beam used by the network device. In this way, the terminal device uses a correct reception beam (that is, a reception beam corresponding to the transmission beam) to receive the data sent by the network device. In a process in which the terminal device is handed over from a serving cell to a candidate cell, the terminal device receives a handover command sent by the serving cell. The handover command further indicates a transmission configuration indicator (transmission configuration indicator, TCI) state. In response to the handover command, the terminal device applies configuration information related to the candidate cell, where the configuration information of the candidate cell includes a TCI state indicated by the handover command. The terminal device obtains resource configuration information of a corresponding reference signal based on the TCI state, where the reference signal includes a tracking reference signal (tracking reference signal, TRS). After parsing the configuration information, the terminal device enters a tracking and measurement phase. Details are as follows: First, the terminal device tracks and measures a determined synchronization signal and broadcast channel resource block (Synchronization Signal and PBCH Block, SSB), and determines beam information based on a measurement result of the SSB. Then, the terminal device needs to track and measure the determined TRS based on the beam information, where there is a correspondence between the TRS and the SSB, to obtain a measurement result of the TRS. Finally, the terminal device activates the TCI state based on the measurement result of the TRS. The applicant finds through research that, the terminal device can parse the configuration information related to the candidate cell only after receiving the handover command, then measure the SSB and the TRS that correspond to the TCI state of the candidate cell, and finally activate the TCI state based on the measurement result. The foregoing process involves significant latency, resulting in a long communication suspension for the terminal device, and reducing communication quality. SUMMARY According to a first aspect, an embodiment of this application provides a beam-based communication method, including: A terminal device receives first indication information of a transmission configuration indicator, where the first indication information is used for activating a TCI state of a candidate cell, the activated TCI state of the candidate cell includes a first TCI state, and the first TCI state includes one or more TCI states; and the terminal device measures a first synchronization signal block SSB based on the first indication information, to obtain a first measurement result, where the first SSB and at least one channel state information reference signal CSI-RS have a quasi-colocation QCL relationship, the at least one CSI-RS is a reference signal in QCL information of the first TCI state, a type of the QCL information of the first TCI state is type A and/or type D, the first SSB is an SSB of the candidate cell, and the at least one CSI-RS is a CSI-RS of the candidate cell. Optionally, the first TCI state further includes a TCI state whose QCL information is of type B and/or type C. The type of the QCL information of the first TCI state is not limited in embodiments of this application. In this embodiment of this application, in a scenario in which the terminal device is handed over from a serving cell to the candidate cell, the terminal device may determine, based on the received f