Base station device, terminal device, control method, and program for performing efficient beam control

Abstract

To improve the efficiency of control by shortening a time required for beam control.SOLUTION: A base station device that forms multiple beams to communicate notifies a terminal device of configuration information for measuring and reporting channel state information (CSI) for determining which of the multiple beams to activate, and information indicating conditions for starting or ending CSI reporting, and receives CSI reported from the terminal device when the conditions are satisfied.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to beam control techniques in cellular communication systems. [Background technology]

[0002] In a fifth-generation (5G) cellular communication system, a base station device and a terminal device can form beams to perform high-capacity communication. The 5G cellular communication standard specifies that a base station device uses a Transmission Configuration Indication (TCI) to control a downlink beam. The base station device receives a report of channel state information (CSI) from a UE, and determines the TCI based on the report.

[0003] Here, the CSI is reported in any one of periodic, aperiodic, and semi-persistent modes. Among these, in semi-persistent CSI reporting, the base station device notifies the terminal device of parameters required for CSI measurement using a radio resource control (RRC) message, and then notifies the terminal device of information instructing the start and end of measurement result reporting. For example, this notification is performed using a medium access control control element (MAC CE) when the reporting is to be performed on a physical uplink control channel (PUCCH), and is performed using downlink control information (DCI) when the reporting is to be performed on a physical uplink shared channel (PUSCH). In accordance with the notification, the terminal device performs measurement and reporting at a constant period from when the reporting start is instructed to when the reporting end is instructed. Also, in aperiodic CSI reporting, the base station device notifies the terminal device of parameters required for CSI measurement using an RRC message, and the terminal device is instructed to report the measurement result using, for example, DCI. In the case of non-periodic CSI reporting, the terminal device reports the CSI measurement result to the base station device only once in response to an instruction.

[0004] The base station device determines some of the many available beams as beams to be used in the downlink based on the reported CSI, and notifies the terminal device of the result of the determination using the TCI state indicating whether the many beams are enabled or disabled. Separate identification information (TCI state ID) is assigned to each of the many beams, and information indicating whether the beam is enabled or disabled corresponding to each identification information is notified to the terminal device. This notification is performed so that which beam is being used can be specified by a limited number of bits of DCI. The base station device notifies the terminal device of which of the enabled TCIs is to be used to transmit a downlink signal by the DCI transmitted together with the transmission of the signal. The terminal device performs a reception process of the downlink signal based on the TCI specified in the DCI. Summary of the Invention [Problem to be solved by the invention]

[0005] The TCI to be enabled for the terminal device is changed according to the status of the terminal device. For example, when the terminal device moves, the corresponding TCI state is enabled so that a beam suitable for the moved position is enabled. For such processing, the base station device needs to transmit a control message to the terminal device as described above to have the terminal device report the CSI. The base station device can, for example, monitor the communication status of the terminal device and transmit an instruction to report such CSI according to the result.

[0006] However, in such a procedure, after the base station device determines that CSI reporting is necessary, it transmits a CSI reporting instruction to the terminal device, the terminal device reports the CSI in accordance with the reporting instruction, and then the base station device instructs the terminal device to switch the beam to be activated, which may result in a long time being required to complete the setting of the appropriate beam.

[0007] The present invention provides a technique for shortening the time required for beam control and improving the efficiency of control. [Means for solving the problem]

[0008] A base station device according to one embodiment of the present invention is a base station device that communicates by forming multiple beams, and has a notification means for notifying a terminal device of configuration information for measuring and reporting channel state information (CSI) and information indicating conditions for starting or ending reporting of the CSI, and a receiving means for receiving the CSI reported from the terminal device in response to the conditions being satisfied.

[0009] A terminal device according to one embodiment of the present invention has a receiving means for receiving configuration information for measuring and reporting channel state information (CSI) and information indicating a condition for starting or ending reporting of the CSI from a base station device that forms multiple beams and communicates, an execution means for performing measurement of the CSI based on the configuration information when no instruction has been received from the base station device in response to the condition being satisfied, and a reporting means for reporting the measurement results of the CSI to the base station device based on the configuration information. Effect of the Invention

[0010] According to the present invention, the time required for beam control can be shortened, and the efficiency of control can be improved. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2] FIG. 1 is a diagram showing a conventional example of a process for setting a beam that can be used to transmit a downlink signal to a terminal device. [Diagram 3] FIG. 11 is a diagram illustrating an example of a processing flow of a first technique. [Figure 4] FIG. 11 is a diagram illustrating an example of a processing flow of a second technique. [Diagram 5] FIG. 2 illustrates an example of a hardware configuration of the apparatus. [Figure 6] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station device. [Figure 7]FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the multiple features described in the embodiments may be arbitrarily combined. In addition, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0013] Fig. 1 shows an example of the configuration of a wireless communication system according to this embodiment. The wireless communication system is, for example, a cellular communication system conforming to the fifth generation (5G) cellular communication standard of the Third Generation Partnership Project (3GPP (registered trademark)), and includes a base station device 101 and a terminal device 111. Note that, although Fig. 1 shows only one base station device and one terminal device, it goes without saying that many base station devices and many terminal devices may exist.

[0014] The base station device 101 can form a plurality of beams and provide communication services to the terminal device 111 using some of the plurality of beams. The base station device 101 selects one of the plurality of beams and transmits a downlink signal to the terminal device 111 using the selected beam. When a different beam is used, the characteristics of the transmission path between the terminal device 111 and the base station device 101 differ, and the decoding process of the downlink signal to be executed in the terminal device 111 also differs. For this reason, when transmitting a downlink signal, the base station device 101 notifies the terminal device 111 of which beam the signal was transmitted using by using downlink control information (DCI). Here, since the base station device 101 can set a large number of beams, in a situation where all of the beams can be used, the beam used to transmit the downlink signal cannot be uniquely identified by the limited number of DCI bits. For this reason, a beam that can be used to transmit a downlink signal to the terminal device 111 can be selected from a large number of beams that the base station device 101 can use and can be set in the terminal device 111 in advance. The flow of this process will be described with reference to FIG. 2.

[0015] The base station device 101 notifies the terminal device 111 of setting information for the terminal device 111 to measure and report the radio quality (channel state information (CSI)) of the signal transmitted by the base station device 101 using each beam (S201). This setting information is notified by using, for example, a radio resource control (RRC) message such as an RRC Reconfiguration message. Here, in the example of FIG. 2, it is assumed that the CSI is reported aperiodic or semi-persistent. In this case, the base station device 101 instructs the terminal device 111 to report the CSI by using, for example, a medium access control control element (MAC CE) or DCI (S203). Note that, in the case of aperiodic reporting, the base station device 101 transmits an instruction to the terminal device 111 by using DCI, and the terminal device 111 measures the CSI-reference signal (CSI-RS) transmitted from the base station device 101 according to this instruction and reports the CSI only once. On the other hand, in the case of semi-persistent reporting, the start and end of measurement and reporting are instructed using MAC CE or DCI. The terminal device 111 starts CSI-RS measurement reporting in response to receiving a start instruction, and ends CSI-RS measurement reporting when an end instruction is received while performing semi-persistent CSI reporting. In semi-persistent CSI reporting, CSI measurement reporting is performed periodically between a start instruction and an end instruction. When aperiodic or semi-persistent CSI measurement reporting is used, the base station device 101 transmits this instruction, for example, when a specific condition is satisfied. That is, when the base station device 101 determines that a CSI measurement report is necessary (S202), it transmits an instruction for a CSI measurement report to the terminal device 111. For example, the base station device 101 may determine that a CSI measurement report is necessary when the terminal device 111 fails to continuously receive a downlink signal transmitted by a specific beam, or when it is assumed that the wireless quality of a specific beam is significantly better than the previously reported CSI. The terminal device 111 measures the CSI-RS transmitted from the base station device 101 (S204) and reports the measurement result to the base station device 101 (S205).

[0016] The base station device 101 uses the result of the report received in S205 to determine one or more beams to be enabled (enabled) for downlink signal transmission to the terminal device 111 among a plurality of beams that the base station device 101 can use for transmitting downlink signals (S206). Each of the plurality of beams that the base station device 101 can form is associated with a Transmission Configuration Indication (TCI). A beam that can be used for transmitting downlink signals to the terminal device 111 is set by enabling a TCI state indicating the state of the TCI. For example, the TCI state of a beam heading in a direction significantly different from the direction of the terminal device 111 is disabled, and the TCI state of at least a part of the beam heading in the direction of the terminal device 111 is enabled. Each TCI can be associated with a reference signal to be measured. For example, in the example of FIG. 1, TCI0 ​​to TCI8 can be associated with CSI-RS, and TCI9 to TCI11 can be associated with a synchronization signal / physical broadcast channel (SS / PBCH) block (SSB). Here, TCIn means TCI stateid=n. A plurality of TCIs having different TCI stateids are associated with different reference signals. That is, CSI-RS based on different radio resources (frequency and time resources) or sequences may be associated with TCI0 ​​to TCI8, and SSB based on different radio resources or sequences may be associated with TCI9 to TCI11. The base station device 101 notifies the terminal device 111 of configuration information of these reference signals, and the terminal device 111 can measure these reference signals based on the configuration information. In addition, when the base station device 101 and the terminal device 111 communicate using a plurality of cells, the TCI used by each cell may be associated with a reference signal provided by another cell, not with a reference signal provided by the cells. In this case, information for identifying which cell's reference signal is associated with which cell's TCI may be notified to the terminal device 111.

[0017] Then, the base station device 101 transmits to the terminal device 111 a MAC CE including information specifying one or more beams determined to be enabled for downlink signal transmission to the terminal device 111 (S207). The base station device 101 may notify the terminal device 111 of a TCI stateid specifying one or more beams to be enabled. The base station device 101 may notify the terminal device 111 of information such as a bitmap indicating enabled or disabled as a TCI state corresponding to each of a plurality of beams formed by the base station device 101. Thereafter, when transmitting a downlink signal (for example, a physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH)) to the terminal device 111, the base station device 101 selects a beam to be used from one or more beams determined to be enabled in S206. Then, the base station device 101 includes information specifying the beam to be used in DCI in the PDCCH transmitted when transmitting the downlink signal, and transmits the DCI to the terminal device 111 (S208).

[0018] In this way, in order to set a downlink beam, the terminal device 111 needs to receive a CSI measurement report instruction from the base station device 101, report the CSI, and receive designation of one or more beams that have been determined to be enabled based on the results of the report. Therefore, a certain amount of time is required for transmitting a downlink signal using an appropriate beam between the base station device 101 and the terminal device 111, and it may become impossible to transmit signals in a timely manner.

[0019] In this embodiment, a technique is provided for shortening a period for setting a beam to be enabled for transmitting a downlink signal to a terminal device 111, from among a plurality of beams formed by a base station device 101.

[0020] In the first method in this embodiment, the terminal device 111 autonomously determines whether or not it is a situation in which measurement should be performed, and in a situation in which measurement should be performed, performs measurement without waiting for an instruction from the base station device 101, and reports the measurement result to the base station device 101. Note that the measurement and reporting here may be aperiodic or quasi-persistent CSI measurement and reporting, but the terminal device 111 may, for example, autonomously change the period of periodic CSI measurement and reporting.

[0021] In the first technique, the base station apparatus 101 notifies the terminal apparatus 111 of information indicating a condition for starting or ending CSI reporting, in addition to the measurement and report setting information such as S201. For example, the condition for starting CSI reporting may include that the strength of a predetermined reference signal exceeds a predetermined value (becomes equal to or greater than a predetermined value), and the information indicating the condition notified from the base station apparatus 101 to the terminal apparatus 111 may include, as information indicating the condition for starting reporting, information indicating the predetermined reference signal and information indicating the predetermined value. In addition, the condition for ending reporting may include that the strength of the predetermined reference signal falls below a predetermined value (becomes equal to or less than a predetermined value), and the information indicating the condition notified from the base station apparatus 101 to the terminal apparatus 111 may include, as information indicating the condition for ending reporting, information indicating the predetermined reference signal and information indicating the predetermined value. Note that the information indicating the predetermined reference signal may include, for example, an SS / PBCH Resource Indicator (SSBRI) for identifying an SSB, or a CSI Reference Signal Resource Indicator (CRI) for identifying a CSI-RS. That is, based on the information indicating this condition, when the strength of the SSB or CSI-RS specified by the SSBRI or CRI exceeds a predetermined value (is equal to or greater than the predetermined value), the terminal device 111 can start quasi-persistent or aperiodic CSI measurement and reporting without receiving any further instructions from the base station device 101, based on the setting information notified from the base station device 101. Also, based on the information indicating this condition, when the strength of the SSB or CSI-RS specified by the SSBRI or CRI falls below a predetermined value (is equal to or greater than the predetermined value), the terminal device 111 ends subsequent measurement and reporting, for example, when quasi-persistent CSI measurement and reporting is being performed.

[0022] The above conditions are merely examples, and other conditions may be used. For example, in the state shown in FIG. 1, when the terminal device 111 moves in the direction of the beam of TCI 11 and the radio quality of the beam of TCI 9 deteriorates, CSI reporting may be started. That is, semi-permanent or non-periodic CSI measurement and reporting may be started on the condition that the strength of the SSB or CSI-RS specified by the SSBRI or CRI falls below a predetermined value. In addition, as the conditions here, for example, conditions related to the channel quality information (CQI, PMI, RI) of the CSI-RS may be used. Note that CQI is a channel quality indicator, PMI is a precoding matrix indicator, and RI is a rank indicator.

[0023] The base station apparatus 101 may notify the terminal apparatus 111 of multiple pieces of setting information regarding CSI measurement and reporting. For example, separate setting information is notified to the terminal apparatus 111 for each TCI. In one example, first setting information indicating that a CSI report for a first TCI should be transmitted and second setting information indicating that a CSI report for a second TCI should be transmitted are notified to the terminal apparatus 111. Note that multiple pieces of setting information may be notified to the terminal apparatus 111 for one TCI. For example, third setting information indicating that a CSI report should be transmitted at 50 millisecond intervals and fourth setting information indicating that a CSI report should be transmitted at 500 millisecond intervals may be notified to the terminal apparatus 111 for one specific TCI. In this case, the third setting information and the fourth setting information may be setting information for periodic CSI measurement and reporting, and the terminal apparatus 111 may switch the setting information used for periodic CSI measurement and reporting between the third setting information and the fourth setting information when a specific condition is satisfied. Each piece of configuration information is assigned with identification information (reportConfigID) for identifying the configuration information. For example, when a specific condition is satisfied, the base station device 101 may notify the terminal device 111 of information indicating the condition so that measurement and reporting of CSI based on specific configuration information is started or ended. That is, the information indicating the condition may include information indicating which of a plurality of configuration information the CSI measurement and reporting is related to.

[0024] The base station device 101 may separately define the conditions and the processes to be executed, and may notify the terminal device 111 of the combination of the conditions and the processes in addition to the information on the conditions and the processes. For example, Condition 1: L1-RSRP of SSBRI 1 is A or higher Condition 2: L1-RSRP of SSBRI 2 is B or less Condition 3: L1-RSRP of CRI 1 is C or higher … Execution instruction 1: Start CSI reporting for reportConfigID=1, 2 Execution instruction 2: End CSI report for reportConfigID=1, 2 Execution instruction 3: Start CSI reporting for reportConfigID=3, 4 Execution instruction 4: Execute CSI report for reportConfigID=5, 6 once … Instruction setting 1: Condition 1, Execution instruction 1 Instruction setting 2: Condition 2, Execution instruction 2 Instruction setting 3: Condition 1, Execution instruction 3 Instruction setting 4: Condition 3, Execution instruction 4 … Such information may be notified to the terminal device 111. According to such a notification method, for example, it is not necessary to prepare information indicating conditions individually for multiple execution instructions, and it is possible to reduce the signaling overhead due to notification. Also, according to such a notification method, when changing a combination of a condition and an execution instruction in some instruction settings, it is sufficient to update only the information of the instruction settings, so that it is possible to reduce the signaling overhead even when updating the information indicating the condition. Also, for example, when a specific instruction setting is released, the terminal device 111 may maintain the information of the condition and the execution instruction while deleting the instruction setting. By maintaining the information of the condition and the execution instruction, the base station device 101 can notify the terminal device 111 to enable an instruction setting including at least one of the condition and the execution instruction thereafter. According to this, when the same condition or execution instruction can be reused, the base station device 101 can instruct the terminal device 111 to measure and report CSI under a specific condition with minimal signaling.

[0025] Note that L1-RSRP indicates reference signal reception power in the physical layer. Also, the configuration information can use the conventional reportConfig (CSI-ReportConfig), and reportConfigID is identification information for identifying the configuration information. Note that in CSI-ReportConfig indicating an execution instruction set together with a condition for starting or ending semi-persistent CSI measurement and reporting, reportConfigType can be set to semiPersistent (OnPUCCH or OnPUSCH). On the other hand, in CSI-ReportConfig indicating an execution instruction set together with a condition for starting aperiodic CSI measurement and reporting, reportConfigType can be set to aperiodic. The existing configuration of reportConfig (CSI-ReportConfig) includes information regarding the configuration of CSI-RS resources used for reporting semi-persistent or aperiodic CSI and the timing of reporting to the base station device 101.

[0026] In addition, in one example, the base station device 101 may notify the terminal device 111 of the index of the SSB or CSI-RS as information for identifying the SSB or CSI-RS used in the above-mentioned condition determination. In addition, a reference signal associated with a beam currently used for the condition determination (for example, a reference signal associated with an enabled TCI) or a reference signal associated with a beam not currently used (for example, a reference signal associated with a disabled TCI) may be specified. In addition, multiple reference signals may be used for the condition determination. For example, when one cell is composed of multiple TRPs, the average value of multiple reference signals transmitted by each TRP may be used for the condition determination. In this case, the base station device 101 notifies the terminal device 111 of a list of reference signals used for calculating the average value (a list of SSB or CSI-RS indexes). In addition, the terminal device 111 may calculate the average value of the measurement results for reference signals that exceed or fall below a threshold value specified by the base station device 101. Furthermore, the terminal device 111 may select the measurement results of reference signals from the best quality or the worst quality, the number of which is equal to the number of reference signals specified by the base station device 101, and calculate an average value using the selected samples. Furthermore, the terminal device 111 may set a weighting coefficient for the measurement value of each reference signal and then calculate a weighted average value. Furthermore, when it is determined that the condition is satisfied, the terminal device 111 may send a notification including the measurement results of the reference signals to the base station device 101, and the base station device 101 that receives the notification may instruct the terminal device 111 to start or end quasi-persistent or aperiodic CSI measurement and reporting.

[0027] When the base station device 101 receives a report of the result of the CSI measurement performed by the terminal device 111 because the above-mentioned conditions are satisfied, the base station device 101 determines a beam to be usable in downlink communication with the terminal device 111 from among a plurality of beams formed by the base station device 101. Then, the base station device 101 transmits information indicating whether each beam is enabled or disabled to the terminal device 111. Note that this information may be, for example, information indicating whether the TCI state corresponding to each beam is enabled or disabled. Note that, for example, an index of 0 to 15 is assigned to each enabled beam. After transmitting this information, the base station device 101 may use the index to indicate in the DCI the beam used when transmitting the downlink signal. When receiving the downlink signal, the terminal device 111 may check the index indicating the TCI in the DCI and perform a decoding process suitable for the TCI corresponding to the index.

[0028] The flow of processing of the first technique as described above will be outlined with reference to Fig. 3. First, the base station device 101 notifies the terminal device 111 of information indicating conditions under which the measurement and reporting should be performed, in addition to configuration information for CSI measurement and reporting (for example, by using an RRC message) (S301). Note that in the example of Fig. 3, the configuration information for CSI measurement and reporting and information indicating conditions under which the measurement and reporting should be performed are notified in one RRC message, but this is just one example, and these pieces of information may be notified from the base station device 101 to the terminal device 111 by separate messages. In addition, the base station device 101 can also notify the terminal device 111 of a message for updating only the conditions (for example, at least one of the above-mentioned conditions and instruction configuration) after transmitting the message of S301.

[0029] When the terminal device 111 determines that the notified condition is satisfied (S302), it measures the radio quality (CSI) using the setting information associated with the condition (S303) and reports the measurement result to the base station device 101 (S304). The subsequent processes of S305 to S307 are similar to the above-mentioned processes of S206 to S208. According to such processes, the terminal device 111 can measure and report the CSI without waiting for a measurement and report instruction such as S203 in FIG. 2. Therefore, in S305 to S306, the base station device 101 can determine a beam to be enabled for the downlink communication of the terminal device 111 and notify the terminal device 111, thereby shortening the time until downlink communication can be performed using an appropriate beam.

[0030] In the second technique, the terminal device 111 determines a beam to be enabled for the downlink communication of the terminal device 111. The terminal device 111 receives, for example, configuration information for CSI measurement and reporting, and performs measurement based on the configuration information. Then, the terminal device 111 does not provide the measurement result to the base station device 101, but uses the measurement result to select a beam that can be used for transmitting a downlink signal to the terminal device 111. This eliminates the need for the terminal device 111 to notify the base station device 101 of the measurement result and the base station device 101 to notify the terminal device 111 of the beam to be enabled that the base station device 101 has determined, and therefore it is possible to shorten the time until downlink communication can be performed using an appropriate beam.

[0031] In the second technique, the base station device 101 notifies the terminal device 111 of first setting information related to CSI measurement and second setting information related to selection of a beam to be activated by the terminal device 111. Then, the terminal device 111 performs CSI measurement based on the first setting information, and determines which of the multiple beams formed by the base station device 101 to activate based on the CSI measurement result and the second setting information. Then, the terminal device 111 notifies the base station device 101 of information indicating the beam determined to be activated, and also performs processing to activate the beam. For example, the terminal device 111 may notify the base station device 101 that the TCI state corresponding to the beam to be activated is to be activated. Note that the terminal device 111 may notify the base station device 101 of a bitmap indicating whether each of the TCI states corresponding to each of the multiple beams formed by the base station device 101 is enabled or disabled. Also, the terminal device 111 may notify the base station device 101 of information capable of identifying the CSI-RS or SSB corresponding to the beam to be activated. That is, since a CSI-RS or SSB generated using different radio resources or sequences is transmitted in each beam, the terminal device 111 can identify the corresponding beam by identifying the CSI-RS or SSB. In response to receiving a notification from the terminal device 111, the base station device 101 identifies a beam determined to be valid in the terminal device 111, which is indicated by the notification, and uses the identified beam in the subsequent downlink communication.

[0032] The above-mentioned second setting information may include information indicating the number of beams that can be enabled. For example, the base station device 101 may notify the terminal device 111 of the second setting information indicating that a maximum of two beams may be enabled. When the terminal device 111 receives such second setting information, it determines to enable a number of beams not exceeding the number indicated by the second setting information. For example, in a DCI including information for transmitting a downlink signal after a selected beam is enabled, the number of beams that can be enabled may be determined according to the number of bits available for notifying information specifying a beam to be used for transmitting the signal. For example, when three bits are provided for specifying a beam in the DCI, the number of beams that can be enabled may be determined to be eight, and when four bits are provided for specifying a beam in the DCI, the number of beams that can be enabled may be determined to be 16. The terminal device 111 may notify the base station device 101 of the maximum number of beams that can be enabled in the terminal device 111. In this case, the terminal device 111 may enable a number of beams that does not exceed the maximum number of beams. In addition, the base station device 101 may determine the number of beams that the terminal device 111 may deem valid, within a range not exceeding the maximum number of beams that may be valid as notified by the terminal device 111, and notify the terminal device 111 of that number.

[0033] Furthermore, the above-mentioned second setting information may include, for example, information specifying beams that should always be enabled (i.e., should not be disabled). Conversely, the second setting information may include information specifying beams that the terminal device 111 is allowed to determine whether to enable or disable. For example, in the example of FIG. 1, the base station device 101 may notify the terminal device 111 of second setting information that specifies TCI9 to TCI11 as beams that should not be disabled. The terminal device 111 may determine whether to enable or disable each of the beams that are not to be disabled. Note that, when the number of beams that can be enabled is specified, the terminal device 111 determines the beams to be enabled so that the number of beams that should not be disabled and the number of beams to be enabled among the other beams do not exceed the number of specified beams. According to such a setting, for example, a beam with a wide beam width that enables a minimum level of communication is always enabled, so that a certain communication service can be provided to the terminal device 111 even if the communication quality of a beam with a narrow beam width deteriorates.

[0034] Furthermore, the above-mentioned second setting information may include, for example, information indicating a wireless quality that a beam to be made valid should satisfy. The base station device 101 may, for example, specify a wireless quality according to the type of communication service (communication application) to be provided to the terminal device 111. The terminal device 111 selects a beam to be made valid from among beams that satisfy the specified wireless quality. By specifying such wireless quality, it is possible to prevent a beam that cannot be used for providing a communication service to be provided to the terminal device 111 due to insufficient wireless quality from being unnecessarily selected. The terminal device 111 may make a predetermined number of beams (a number within a range that does not exceed the number of beams that can be made valid, which is specified by the capability of the terminal device 111 or specified by the base station device 101) valid from among beams that exceed the specified wireless quality. At this time, the predetermined number of beams may be selected in order of good wireless quality, or may be selected randomly (from a group of beams that can obtain the specified wireless quality). If the terminal device 111 is not notified of information indicating a wireless quality that a beam to be made valid should satisfy, it may make a predetermined number of beams valid from beams with good wireless quality.

[0035] The base station device 101 and the terminal device 111 may execute the process of activating the beam determined to be activated, for example, after a predetermined period has elapsed since the terminal device 111 notifies the base station device 101 of the beam determined to be activated (the base station device 101 receives the notification). That is, if the terminal device 111 activates the beam determined to be activated at the time of transmitting the beam, the base station device 101 may not be able to activate the beam at that timing due to a propagation delay of the notification or a delay for processing such as decoding, and it is assumed that inconsistency occurs between the base station device 101 and the terminal device 111. For this reason, for example, the base station device 101 and the terminal device 111 may simultaneously activate the selected beam after a predetermined period has elapsed, such as a predetermined number of slots after the time slot in which the terminal device 111 notifies the base station device 101 of the beam determined to be activated. This makes it possible to prevent inconsistency between the base station device 101 and the terminal device 111.

[0036] The base station device 101 may notify the terminal device 111 of third setting information indicating information indicating the length of the predetermined period. That is, the length of the predetermined period may be set by the base station device 101. The base station device 101 may also notify the terminal device 111 of third setting information indicating multiple candidates for the length of the predetermined period. In this case, the terminal device 111 selects a period of any length from the multiple candidates, and activates a beam that has been determined to be valid after the period has elapsed. The terminal device 111 may also notify the base station device 101 of information indicating the length of the selected period, in addition to information indicating the beam that has been determined to be valid. The base station device 101 executes a process of activating the beam determined by the terminal device 111 to be valid after the notified period has elapsed. According to this process, the terminal device 111 can determine the length of the predetermined period (from among the candidates presented by the base station device 101). If the length of the predetermined period is clearly defined, for example, by a standard, all signaling of information regarding the length of the period may be omitted.

[0037] Furthermore, when the base station device 101 receives a notification of information indicating a beam determined to be valid from the terminal device 111, the base station device 101 may transmit an acknowledgement (Ack) to the terminal device 111. For example, the terminal device 111 may notify the base station device 101 of information indicating the beam determined to be valid using an RRC message or a MAC CE included in an uplink data signal. Then, the base station device 101 may transmit an Ack to the terminal device 111 using an RRC message or a MAC CE included in a downlink data signal. Then, after notifying the base station device 101 of information indicating the beam determined to be valid, the terminal device 111 may perform an activation process of the beam determined to be valid based on receiving an Ack in response to the notification. That is, the terminal device 111 may not perform an activation process of the beam determined to be valid unless an Ack is received from the base station device 101. If the terminal device 111 does not receive an Ack even after waiting for a predetermined time, the terminal device 111 may resend a notification of the beam determined to be valid to the base station device 101. The base station device 101 may always return an Ack when it successfully receives a notification of information indicating a beam determined to be valid, or may determine whether or not to accept the contents of the notification and return an Ack only when it determines to accept the contents. This can prevent inconsistency between the beams to be enabled between the base station device 101 and the terminal device 111. The notification from the terminal device 111 to the base station device 101 may be assigned with identification information that can uniquely identify the notification. In this case, the base station device 101 may assign the identification information to the Ack and transmit it.

[0038] Also, the base station device 101 may periodically transmit information on a beam that is valid for the terminal device 111 among a plurality of beams that are formed. For example, the terminal device 111 may notify the base station device 101 of information indicating a beam that has been determined to be valid, using uplink control information (UCI). In this case, the base station device 101 cannot return an Ack, but by periodically transmitting information on a beam that has been valid for the terminal device 111, the terminal device 111 can recognize whether the information on the valid beam is consistent with a beam that has been determined to be valid in the terminal device 111. That is, when the terminal device 111 receives this information, it determines whether the beam that is valid, indicated by the information, matches the beam that has been determined to be valid in the terminal device and notified to the base station device 101. Then, when the beam indicated by the information received from the base station device 101 does not match the beam that the terminal device notified to the base station device 101 by the terminal device, the terminal device 111 may retransmit to the base station device 101 a notification of the beam that has been determined to be valid. That is, when a beam recognized in the base station device 101 and enabled for the terminal device 111 does not match a beam recognized in the terminal device 111 and to be enabled, the terminal device 111 may determine that a notification of the beam determined to be enabled has not correctly reached the base station device 101, and may resend the notification. This makes it possible to correct a mismatch in a beam that is enabled between the base station device 101 and the terminal device 111. The terminal device 111 may suspend the enabling process of the beam that is determined to be enabled until the mismatch is corrected.

[0039] In addition, it may be assumed that the terminal device 111 receives radio resource allocation for the physical downlink shared channel (PDSCH) or the physical uplink shared channel (PUSCH) from the base station device 101 in a state where the recognition of the enabled beam is not consistent between the terminal device 111 and the base station device 101 (TCI state is inconsistent). In this case, the terminal device 111 may notify the base station device 101 that the notified resource allocation cannot be accepted (or that the state is such that resource allocation is not possible). In addition, the base station device 101 may allocate resources for the PDSCH or PUSCH signals in two or more beams for transmitting the PDSCH or PUSCH, assuming that the TCI state is inconsistent. If the two or more beams to which the resources are allocated include a beam that is not enabled in the terminal device 111, the terminal device 111 may perform data communication in a enabled beam without using the beam. This makes it possible to continue communication even when a period in which the TCI state may be inconsistent occurs.

[0040] The flow of processing of the second method as described above will be outlined with reference to FIG. 4. First, the base station device 101 notifies the terminal device 111 of the first setting information related to the measurement of CSI and the second setting information related to the selection of a beam, for example, by using an RRC message (S401). Note that, in the example of FIG. 4, the first setting information and the second setting information are notified by one message, but these setting information may be notified by separate messages. The terminal device 111 performs measurement of the radio quality (CSI) based on the first setting information (S402), and selects a valid beam from among the multiple beams formed by the base station device 101 based on the measurement result (S403). Then, the terminal device 111 transmits a notification including the selection result of the beam to the base station device 101 (S404). Here, the base station device 101 may return an Ack in response to this notification (S405). The base station device 101 may periodically transmit information on the beams that are enabled for the terminal device 111 in the base station device 101 to the terminal device 111. For example, after a predetermined period has elapsed since the transmission and reception of the notification in S404, the base station device 101 and the terminal device 111 execute a process of enabling the beams notified by the terminal device 111 to be enabled (S406, S407). This enabling process is a process for enabling the base station device 101 to specify the beams to be used by DCI in subsequent communications, such as a process of associating a predetermined index with each enabled beam and storing the corresponding beam. After the process is completed, the base station device 101 selects a beam to be used from among the beams that are enabled in the terminal device 111 when transmitting a downlink signal, and transmits DCI including information indicating the selected beam to the terminal device 111 (S408).

[0041] In this way, in the second technique, after the terminal device 111 measures the wireless quality, the terminal device 111 determines the beam to be activated without notifying the base station device 101 of the measurement result and without the base station device 101 determining the beam to be activated and notifying the same. This makes it possible to reduce the number of signaling events between the terminal device 111 and the base station device 101, and shortens the time required for the terminal device 111 to determine and activate the beam to be activated.

[0042] The first method and the second method may be selectively executed, or the first method and the second method may be used in combination. When the first method and the second method are selectively executed, for example, when the base station device 101 notifies the terminal device 111 of the setting information of the first measurement, the base station device 101 may also notify the terminal device 111 of information indicating which method should be used. Note that the notification may be performed implicitly depending on whether the information on the condition (S301) or the setting information on the selection of the beam (S401) is transmitted. When the first method and the second method are used in combination, the base station device 101 may notify the terminal device 111 of both the information indicating the condition under which the measurement should be performed and the setting information on the selection of the beam. The terminal device 111 may perform the measurement when the notified condition is satisfied, and may select a beam based on the result of the measurement. That is, in the second technique, the terminal device 111 can perform wireless quality measurement and beam selection, for example, in response to receiving first setting information regarding measurement and second setting information regarding beam selection in S401, and by being notified of the conditions for starting the processing, the terminal device 111 can autonomously start the processing in response to determining that the conditions are satisfied.

[0043] Although the above description focuses on the setting of beams for transmitting and receiving downlink signals, the setting of beams used for transmitting and receiving uplink signals can be performed in the same manner. That is, when the same frequency channel is used for the downlink and the uplink, it is assumed that the downlink channel characteristics and the uplink channel characteristics are common. Therefore, the uplink communication can also be performed using the beam selected for transmitting the downlink signal as described above.

[0044] FIG. 5 shows an example of the hardware configuration of the base station device 101 and the terminal device 111 according to the present embodiment. In one example, the base station device 101 and the terminal device 111 are configured to include a processor 501, a ROM 502, a RAM 503, a storage device 504, and a communication circuit 505. The processor 501 is a computer configured to include one or more processing circuits such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and executes the overall processing of the device and each of the above-mentioned processes by reading and executing a program stored in the ROM 502 or the storage device 504. The ROM 502 is a read-only memory that stores information such as programs and various parameters related to the processing executed by the base station device 101 and the terminal device 111. The RAM 503 functions as a workspace when the processor 501 executes a program, and is a random access memory that stores temporary information. The storage device 504 is configured, for example, by a removable external storage device. The communication circuit 505 is configured, for example, by a circuit for wireless communication of 5G or its successor standard. Although one communication circuit 505 is illustrated in FIG. 5, the base station device 101 and the terminal device 111 may have multiple communication circuits. For example, the base station device 101 and the terminal device 111 may have wireless communication circuits for 5G and its successor standard, and a common antenna for those circuits. The base station device 101 and the terminal device 111 may have separate antennas suitable for each standard. The base station device 101 may further have a wired communication circuit used when communicating with other base station devices or nodes of the core network. The terminal device 111 may further have a communication circuit conforming to a wireless communication standard other than the cellular communication standard, such as a wireless local area network (LAN) or Bluetooth (registered trademark). The base station device 101 and the terminal device 111 may have separate communication circuits 505 for each of a plurality of available frequency bands, or may have a common communication circuit 505 for at least a part of those frequency bands.

[0045] FIG. 6 shows an example of the functional configuration of the base station device 101 according to this embodiment. The base station device 101 includes, as its functions, a measurement report setting designation unit 601, a condition designation unit 602, a selection setting designation unit 603, an information notification unit 604, an information reception unit 605, a beam selection unit 606, an activation processing unit 607, and a data communication unit 608. Note that FIG. 6 shows only functions particularly related to this embodiment, and other various functions that the base station device 101 may have are omitted from the illustration. For example, the base station device 101 naturally has other functions that a base station device conforming to 5G or its subsequent standards generally has. In addition, the functional blocks in FIG. 6 are shown in a schematic manner, and each functional block may be realized by being integrated, or may be further subdivided. In addition, each function in FIG. 6 may be realized, for example, by the processor 501 executing a program stored in the ROM 502 or the storage device 504, or may be realized, for example, by a processor present inside the communication circuit 505 executing predetermined software. The details of the processes executed by each functional unit have been described above, so the description will not be repeated here, and only the general functions will be outlined.

[0046] The measurement report setting designation unit 601 designates setting information related to measurement and reporting of CSI for the terminal device 111. This setting information is similar to conventional measurement information related to measurement and reporting of CSI. The condition designation unit 602 designates a condition for the terminal device 111 to autonomously start and end measurement and reporting of CSI in the above-mentioned first method. The selection setting designation unit 603 designates setting information used when the terminal device 111 autonomously determines a beam to be enabled in the above-mentioned second method. The information notification unit 604 notifies the terminal device 111 of the setting information designated by the measurement report setting designation unit 601 and information designated by at least one of the condition designation unit 602 and the selection setting designation unit 603. The information receiving unit 605 receives various information notified from the terminal device 111. For example, in the first method, the information receiving unit 605 receives a report of a measurement result of CSI. Also, in the second method, the information receiving unit 605 receives information designating a beam to be enabled. In the first technique, the beam selection unit 606 determines a beam to be activated in communication with the terminal device 111 based on the measurement result of the CSI received by the information receiving unit 605. When the second technique is used, the beam selection unit 606 is not used. The activation processing unit 607 executes a process of activating a beam notified from the terminal device 111 or selected by the beam selection unit 606 and determined to be activated in communication with the terminal device 111. The data communication unit 608 uses any of the beams activated by the activation processing unit 607 to communicate with the terminal device 111.

[0047] FIG. 7 shows an example of the functional configuration of the terminal device 111 according to this embodiment. The terminal device 111 includes, as its functions, a setting receiving unit 701, a condition determining unit 702, a measuring unit 703, a beam selecting unit 704, a reporting unit 705, an enabling processing unit 706, and a data communication unit 707. Note that FIG. 7 shows only functions particularly related to this embodiment, and various other functions that the terminal device 111 may have are omitted from the illustration. For example, the terminal device 111 naturally has other functions that terminal devices that comply with 5G and subsequent standards generally have. In addition, the functional blocks in FIG. 7 are shown in a schematic manner, and each functional block may be realized by being integrated, or may be further subdivided. In addition, each function in FIG. 7 may be realized, for example, by the processor 501 executing a program stored in the ROM 502 or the storage device 504, or may be realized, for example, by a processor present inside the communication circuit 505 executing predetermined software. The details of the processes executed by each functional unit have been described above, so the description will not be repeated here, and only the general functions will be outlined.

[0048] The setting receiver 701 receives information including at least one of setting information for CSI measurement and reporting, and information indicating a condition for starting and ending measurement and reporting, and setting information for selecting a beam, from the base station device 101. For example, when the base station device 101 determines a beam to be enabled for communication with the terminal device 111, the setting receiver 701 receives information indicating the beam from the base station device 101. When the first method is used, the condition determiner 702 determines whether or not a condition included in the information received by the setting receiver 701 is satisfied. The measurement unit 703 measures the wireless quality of a signal transmitted from the base station device 101 based on the setting information for CSI measurement received by the setting receiver 701. When the first method is used, for example, the measurement unit 703 measures the wireless quality in response to the condition determiner 702 determining that the condition is satisfied. When the second method is used, the beam selection unit 704 uses the setting information for selecting a beam received by the setting reception unit 701 to determine which of the multiple beams formed by the base station device 101 is to be usable (enabled) for communication with the base station device 101 based on the measurement result of the measurement unit 703. When the second method is not used, the beam selection unit 704 is not used. For example, the report unit 705 reports the wireless quality measured by the measurement unit 703 to the base station device 101. When the second method is used, the report unit 705 reports information on the beam determined to be enabled by the beam selection unit 704 to the base station device 101. For example, the enablement processing unit 706 executes a process of enabling the beam received by the setting reception unit 701 and determined to be enabled in the base station device 101. When the second method is used, the enablement processing unit 706 executes a process of enabling the beam determined to be enabled by the beam selection unit 704. The data communication unit 707 communicates with the base station device 101 using any of the beams activated by the activation processing unit 706 .

[0049] As described above, the base station device 101 and the terminal device 111 according to this embodiment can determine and activate, in a short period of time, one or more beams that can be used for communication by the terminal device 111, among multiple beams formed by the base station device 101. This makes it possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "build resilient infrastructure, promote sustainable industrialization, and foster innovation."

[0050] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

Claims

1. A base station device that forms a plurality of beams to perform communication, A notification means for notifying a terminal device of setting information for measuring and reporting channel state information (CSI) and information indicating a condition for starting or ending the reporting of the CSI; A receiving means for receiving the CSI reported from the terminal device in response to the condition being satisfied; A base station device comprising:

2. A determination means for determining whether to enable or disable each of the plurality of beams for the terminal device based on the received CSI; a transmitting means for transmitting information indicating whether each of the plurality of beams is to be enabled or disabled to the terminal device; The base station apparatus according to claim 1 , further comprising:

3. The base station device according to claim 1, characterized in that the condition for starting the report includes that the strength of a predetermined reference signal exceeds a predetermined value, and the information indicating the condition includes, as information indicating the condition for starting the report, information indicating the predetermined reference signal and information indicating the predetermined value.

4. The base station device according to claim 1, characterized in that the condition for terminating the report includes that the strength of a predetermined reference signal falls below a predetermined value, and the information indicating the condition includes, as information indicating the condition for terminating the report, information indicating the predetermined reference signal and information indicating the predetermined value.

5. The base station device according to claim 3 or 4, characterized in that the information indicating the condition includes, as information indicating the predetermined reference signal, an SS / PBCH Block Resource Indicator (SSBRI) that specifies an SS / PBCH Block (SSB), or a CSI Reference Signal Resource Indicator (CRI) that specifies a Channel State Information (CSI)-Reference Signal (RS).

6. The notification means notifies the terminal device of a plurality of pieces of setting information; The base station apparatus according to claim 1 , wherein the condition for starting or ending the reporting includes information indicating which of a plurality of pieces of the configuration information is used to start or end the reporting of the CSI.

7. The base station apparatus according to claim 1 , wherein the notification means notifies the terminal apparatus of the setting information and the information indicating the conditions regarding aperiodic reporting of the CSI and quasi-persistent reporting of the CSI.

8. The base station apparatus according to claim 7 , wherein the notification means further notifies the terminal apparatus of information indicating a condition for changing a period for periodic reporting of the CSI.

9. A terminal device, A receiving means for receiving, from a base station device that forms a plurality of beams and performs communication, setting information for measuring and reporting channel state information (CSI) and information indicating a condition for starting or ending the reporting of the CSI; an execution means for executing measurement of the CSI based on the configuration information in a state in which an instruction from the base station device has not been received in response to the condition being satisfied; a reporting means for reporting a measurement result of the CSI to the base station device based on the configuration information; A terminal device comprising:

10. an acquisition means for acquiring information indicating whether each of the plurality of beams is to be enabled or disabled, the information being determined in the base station device based on a measurement result of the CSI; A communication means for performing communication including receiving a signal transmitted using the enabled beam; 10. The terminal device according to claim 9, further comprising:

11. The terminal device according to claim 10, characterized in that the condition for starting the report includes the strength of a predetermined reference signal exceeding a predetermined value, and the information indicating the condition includes, as information indicating the condition for starting the report, information indicating the predetermined reference signal and information indicating the predetermined value.

12. The terminal device according to claim 10, characterized in that the condition for terminating the report includes the strength of a predetermined reference signal falling below a predetermined value, and the information indicating the condition includes information indicating the predetermined reference signal and information indicating the predetermined value as information indicating the condition for terminating the report.

13. The information indicating the condition includes, as information indicating the predetermined reference signal, an SS / PBCH Block Resource Indicator (SSBRI) that specifies an SS / PBCH Block (SSB), or a CSI Reference Signal Resource Indicator (CRI) that specifies a Channel State Information (CSI)-Reference Signal (RS). The terminal device according to claim 11 or 12, characterized in that

14. The receiving means receives a plurality of pieces of the setting information from the base station device, The terminal device according to claim 10, characterized in that the condition for starting or ending the reporting includes information indicating which of the plurality of pieces of configuration information is used to start or end the reporting of the CSI.

15. The terminal device according to claim 10, characterized in that the receiving means receives the setting information and the information indicating the conditions regarding the non-periodic reporting of the CSI and the quasi-persistent reporting of the CSI from the base station device.

16. 16. The terminal device according to claim 15, wherein the receiving means further receives, from the base station device, information indicating a condition for changing a period for periodic reporting of the CSI.

17. A control method executed by a base station device that forms a plurality of beams and performs communication, comprising: Notifying a terminal device of setting information for measuring and reporting channel state information (CSI) and information indicating a condition for starting or ending reporting the CSI; receiving the CSI reported from the terminal device in response to the condition being satisfied; A control method comprising:

18. A control method executed by a terminal device, comprising: receiving, from a base station device that forms a plurality of beams and performs communication, setting information for measuring and reporting channel state information (CSI) and information indicating a condition for starting or ending reporting the CSI; In response to the condition being satisfied, performing measurement of the CSI based on the configuration information in a state in which an instruction from the base station device has not been received; reporting a measurement result of the CSI to the base station device based on the configuration information; A control method comprising:

19. A program for causing a computer installed in a base station device to execute the control method according to claim 17.

20. A program for causing a computer installed in a terminal device to execute the control method according to claim 18.

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