Base station device, terminal device, communication method, and program in wireless communication system in which communication is performed using multiple transmission / reception points (TRPS)

Abstract

To efficiently operate a system in which a base station device communicates with a terminal device using multiple transmission / reception points (TRPs).SOLUTION: A base station device that communicates with a terminal device using multiple transmission / reception points (TRPs) including a first TRP and a second TRP notifies the terminal device of configuration information generated so that a first resource which a channel state information-reference signal (CSI-RS) is transmitted from the first TRP when calibration is not performed between the first TRP and the second TRP is different from a second resource which a CSI-RS is transmitted from the first TRP when calibration is performed between the first TRP and the second TRP, transmits first information associated with the first resource to the terminal device when transmitting a signal in a state in which calibration is not performed between the first TRP and the second TRP to the terminal device, and transmits second information associated with the second resource to the terminal device when transmitting a signal in a state in which calibration is performed between the first TRP and the second TRP to the terminal device.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an operation technique for a wireless communication system in which a base station device performs communication using a plurality of transmission / reception points (TRPs). [Background technology]

[0002] Systems are being considered in which a base station device communicates using multiple transmission / reception points (TRPs) located at geographically distant locations. In such systems, it is expected that the base station device will not only select one of the multiple TRPs to communicate with a terminal device, but also communicate with a terminal device using two or more TRPs simultaneously. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP (registered trademark) Contribution, R1-2203142 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides an efficient operation technique for a system in which a base station device communicates using a plurality of TRPs. [Means for solving the problem]

[0005] A base station device according to one aspect of the present invention is a base station device that communicates with a terminal device using a plurality of TRPs including a first transmission / reception point (TRP) and a second TRP, and includes: a notification means for notifying the terminal device of configuration information generated so that a first resource from which a channel state information-reference signal (CSI-RS) is transmitted from the first TRP when calibration is not performed between the first TRP and the second TRP is different from a second resource from which a CSI-RS is transmitted from the first TRP when calibration is performed between the first TRP and the second TRP; and a transmission means for transmitting first information associated with the first resource to the terminal device when a signal in a state in which calibration is not performed between the first TRP and the second TRP is transmitted to the terminal device, and transmitting second information associated with the second resource to the terminal device when a signal in a state in which calibration is performed between the first TRP and the second TRP is transmitted to the terminal device.

[0006] A terminal device according to one aspect of the present invention includes: an acquisition means for acquiring, from a base station device that communicates with the terminal device using a plurality of TRPs including a first transmission / reception point (TRP) and a second TRP, configuration information generated such that a first resource from which a channel state information-reference signal (CSI-RS) is transmitted from the first TRP when calibration is not performed between the first TRP and the second TRP is different from a second resource from which a CSI-RS is transmitted from the first TRP when calibration is performed between the first TRP and the second TRP; a reception means for receiving from the base station device either first information associated with the first resource or second information associated with the second resource; and an execution means for, when receiving the first information, performing reception processing of a signal transmitted from the base station device after the first information based on a measurement result of the CSI-RS transmitted in the first resource, and, when receiving the second information, performing reception processing of a signal transmitted from the base station device after the second information based on a measurement result of the CSI-RS transmitted in the second resource. [Effects of the Invention]

[0007] According to the present invention, it is possible to efficiently operate a system in which a base station device communicates with a terminal device using a plurality of transmission / reception points (TRPs). [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Figure 2] FIG. 10 is a diagram illustrating the TCI-state notified to the terminal device. [Figure 3] FIG. 1 is a diagram illustrating an example of the flow of communication processing executed in a wireless communication system. [Figure 4] FIG. 10 is a diagram illustrating the TCI-state notified to the terminal device. [Figure 5] FIG. 1 is a diagram illustrating an example of the flow of communication processing executed in a wireless communication system. [Figure 6] FIG. 1 is a diagram illustrating an example of the flow of communication processing executed in a wireless communication system. [Figure 7] FIG. 1 is a diagram illustrating qcl-Type. [Figure 8] FIG. 10 is a diagram illustrating the TCI-state notified to the terminal device. [Figure 9] FIG. 1 is a diagram illustrating an example of the flow of communication processing executed in a wireless communication system. [Figure 10] FIG. 10 is a diagram illustrating NZP-CSI-RS-Resource notified to a terminal device. [Figure 11] FIG. 10 is a diagram illustrating an example of the flow of frequency and timing synchronization and adjustment processing. [Figure 12] FIG. 10 is a diagram illustrating an example of a processing flow regarding measurement and reporting by a terminal device. [Figure 13] FIG. 10 is a diagram illustrating an example of a configuration for measurement and reporting by a terminal device. [Figure 14] FIG. 10 is a diagram illustrating an example of a configuration for measurement and reporting by a terminal device. [Figure 15] FIG. 10 is a diagram illustrating an example of a processing flow regarding measurement and reporting by a terminal device. [Figure 16] FIG. 10 is a diagram illustrating an example of a processing flow regarding measurement and reporting by a terminal device. [Figure 17] FIG. 2 is a diagram illustrating an example of the hardware configuration of a base station device and a terminal device. [Figure 18] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station device. [Figure 19] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. Furthermore, the same reference numerals are used to designate identical or similar components, and redundant descriptions will be omitted.

[0010] FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. This wireless communication system is, for example, a cellular communication system conforming to a cellular communication standard standardized for the fifth generation (5G) or later, and includes a base station device (gNB 101) and terminal devices 121 and 122. The gNB 101 establishes a connection with and communicates with the terminal devices 121 and 122 using, for example, at least one of multiple transmission / reception points (TRPs, for example, a first TRP 111 and a second TRP 112) located at geographically separate locations. Here, a single TRP may include multiple antenna elements. In this case, adjustment (calibration) is performed within the TRP to roughly match the frequencies, timing, etc., between the multiple antenna elements. When this calibration is performed within the TRP, processing is performed within the TRP device, so the terminal devices do not need to be involved in the calibration. For example, the frequencies of the multiple antenna elements are identified within the TRP, and a control unit within the TRP controls the frequencies to match. Furthermore, clock adjustments may be performed so that radio signals are output from each antenna element at approximately the same timing. When radio signals are transmitted from multiple antenna elements included in one TRP at approximately the same timing, the distances between those antenna elements and the terminal device are approximately equal, so it is assumed that the radio signals will be received by the terminal device within a certain period of time. This certain period is, for example, a period corresponding to the length of the cyclic prefix of orthogonal frequency division multiplexing (OFDM). As a result, the radio signals transmitted from those antenna elements are received by the terminal device within a certain frequency difference range and a certain time difference range, and the terminal device can successfully decode the radio signals without being particularly aware of calibration.

[0011] On the other hand, when multiple TRPs are used for communication with a single terminal device, calibration between those TRPs may be required, for example, to receive radio signals from the terminal device. Even if the gNB101, for example, takes the lead in performing calibration across multiple TRPs, it is not easy to accurately synchronize the timing due to differences in the cable length from the gNB101 to each TRP. Furthermore, depending on the location of the terminal device, the distance between the terminal device and the first TRP and the distance between the terminal device and the second TRP are expected to vary significantly. Even if the first TRP and the second TRP can transmit signals at the same time, the reception timing of those signals at the terminal device may differ significantly, and the terminal device may not be able to properly decode those signals. Furthermore, even if the frequencies between multiple TRPs are roughly synchronized, gradual deviations in the operating frequencies may occur due to temperature changes in each TRP, etc.

[0012] For this reason, calibration across multiple TRPs can be performed using feedback such as measurement results by the terminal device of signals transmitted from each TRP. For example, when the terminal device has established frequency synchronization based on a radio signal from the first TRP 111, it performs channel estimation using a radio signal (reference signal) from the second TRP 112, using the frequency at which synchronization with the first TRP 111 is established as a reference. The terminal device further performs channel estimation after a certain time has elapsed to identify the amount of phase rotation of the channel. If there is a frequency shift, its effect appears as a phase rotation of the channel. Here, the magnitude of the frequency shift corresponds to the amount of phase rotation of the channel per certain time. For this reason, by repeatedly performing such channel estimation to identify the amount of phase rotation per unit time of the channel (the direction and magnitude of the phase rotation), the frequency shift between the first TRP 111 and the second TRP 112 can be identified. The terminal device feeds back information indicating the amount of phase rotation or frequency shift to the gNB 101, for example, via at least one of the first TRP 111 and the second TRP 112. Then, based on the feedback, the gNB 101 adjusts, for example, the frequency (or signal phase) of the second TRP 112 so as to suppress the amount of phase rotation of the channel in the terminal device. For example, the gNB 101 transmits an instruction to the control unit of the second TRP 112 to adjust the frequency or to rotate the phase of the transmission signal in the opposite direction to the fed-back phase rotation direction and transmit it. This makes it possible to roughly match the frequencies of the radio signals transmitted from the first TRP 111 and the second TRP 112.

[0013] Furthermore, the terminal device can determine how much the reception timing of the signal from the second TRP 112 deviates from the reception timing of the signal from the first TRP 111, based on the timing at which the signal from the first TRP 111 is received. For example, the terminal device measures a predetermined signal such as a synchronization signal from the second TRP 112, determines the deviation in the reception timing, and feeds back the amount of deviation to the gNB 101, for example, via at least one of the first TRP 111 and the second TRP 112. As a result, the gNB 101 instructs, for example, the second TRP 112 to shift the transmission timing by the amount of deviation when transmitting a signal to the terminal device (for example, if the signal from the second TRP 112 arrives late at the terminal device, advance the transmission timing, and if the signal from the second TRP 112 arrives early at the terminal device, delay the transmission timing). As a result, in the terminal device, the signals (or their main components) transmitted from the first TRP 111 and the second TRP 112 arrive within the time length range of the cyclic prefix, for example.

[0014] Here, the timing at which a radio signal should be transmitted at each TRP and the combination of TRPs used for communication with a terminal device depend on the location of the terminal device. Therefore, calibration can be performed individually for each terminal device. For example, if the combination of TRPs used for a first terminal device is different from the combination of TRPs used for a second terminal device, the TRPs used as a reference for frequency adjustment may also differ. Furthermore, even if the same combination of TRPs is used for calibration for the first terminal device and calibration for the second terminal device, the appropriate transmission timing of the radio signal may differ depending on the location of each terminal device. Therefore, calibration between TRPs is not always performed, and whether calibration is performed may be determined depending on which terminal device is communicating with which device. For example, in communication with a terminal device located sufficiently close to one TRP, communication may be performed only via that one TRP. In this case, calibration between TRPs is not performed.

[0015] At this time, the characteristics of the radio signal arriving at the terminal device differ between when inter-TRP calibration is performed and when such calibration is not performed. For example, when the second TRP 112 performs calibration based on the radio signal arriving at the terminal device from the first TRP 111, the second TRP 112 transmits a signal at a frequency and transmission timing different from when calibration is not performed. As a result, for example, compared to when a signal is transmitted only from the second TRP 112, the average delay and frequency of the received signal at the terminal device differ. For example, the frequency correction value of the terminal device assuming that inter-TRP calibration is performed may differ from the frequency correction value to be used when demodulating a signal in a state in which inter-TRP calibration is not performed. Furthermore, a channel estimation value obtained by the terminal device by measuring, for example, a channel state information-reference signal (CSI-RS) or a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) while calibration is being performed differs from the channel estimation value when calibration is not performed. Therefore, if the terminal device does not perform demodulation processing corresponding to whether or not the calibration between TRPs is performed, the terminal device may perform demodulation processing using an inappropriate frequency correction value or channel estimation value. As a result, the demodulation performance of the terminal device may be degraded due to the difference in frequency or channel estimation value.

[0016] For this reason, in this embodiment, a technique is provided that enables a terminal device to perform demodulation processing appropriate for each TRP depending on whether calibration between TRPs has been performed.

[0017] In this embodiment, for example, each TRP is configured to notify a terminal device whether calibration (adjustment of frequency or transmission timing) between other TRPs is performed or not. For example, each TRP transmits information corresponding to whether the signal transmitted to the terminal device is a signal subjected to inter-TRP calibration in the downlink control information (DCI) of the signal transmitted to the terminal device. In this embodiment, as an example, a Transmission Configuration Indicator (TCI) state is used as information corresponding to whether inter-TRP calibration is performed.

[0018] Here, the TCI state will be described with reference to Fig. 2. Fig. 2 shows part of the TCI state setting information notified to the terminal device by the gNB 101. As shown in Fig. 2, each TCI state includes a TCI-state ID, which is an identifier of that state, and QCL (Quasi Co-Location)-Info. Then, in the QCL-Info, an NZP (Non Zero Power)-CSI-RS-ResourceSetId or an SSB index for indicating a CSI-RS resource is specified. Note that the focus here is on the CSI-RS, and a description of the SSB is omitted. In this way, the TCI state is associated with a resource from which a reference signal (CSI-RS) is transmitted. For example, the terminal device measures a reference signal associated with each TCI state, and performs reception settings for signal demodulation and the like for each TCI state based on the measurement results. Then, when a TCI state identifier (TCI-state ID) is specified in DCI during subsequent communication, the terminal device performs reception processing, such as signal demodulation, using the reception settings associated with the TCI-state identified by that identifier. For example, one TCI state is set for each beam having different characteristics. Therefore, the gNB 101 designates different TCI-state IDs at least when transmitting radio signals via only the first TRP 111 and when transmitting radio signals via only the second TRP 112.

[0019] Here, in this embodiment, a TCI-state is further prepared for the case where calibration is performed between TRPs (for example, between the first TRP 111 and the second TRP 112). In one example, TCI-state ID=0 is assigned to the TCI state when a signal is transmitted using only the first beam formed by the first TRP 111 without performing inter-TRP calibration, and TCI-state ID=1 is assigned to the TCI state when a signal is transmitted using only the second beam formed by the second TRP 112 without performing inter-TRP calibration. Then, in this embodiment, for example, TCI-state ID=2 is assigned to the TCI state when a signal after inter-TRP calibration is transmitted from both the first TRP 111 and the second TRP 112 using the first beam and the second beam. That is, even when the same beam is used, different TCI states can be prepared depending on whether inter-TRP calibration is performed. Note that different beams may be formed when inter-TRP calibration is performed and when such calibration is not performed. The first TRP 111 and the second TRP 112 transmit reference signals without performing calibration in resources corresponding to TCI-state ID=0 and 1, respectively, and transmit reference signals after performing calibration in resources corresponding to TCI-state ID=2. The terminal device measures these reference signals and determines reception settings corresponding to each TCI state. Then, for example, when the second TRP 112 transmits a radio signal without performing calibration with other TRPs, the gNB 101 specifies TCI-state ID=1 in the DCI and transmits a signal (Physical Downlink Shared Channel (PDSCH)). This allows the terminal device to receive the radio signal using reception settings based on the reference signal transmitted by the second TRP 112 without performing calibration.On the other hand, when the first TRP111 and the second TRP112 perform calibration and transmit radio signals, the gNB101 transmits a signal by specifying TCI-state ID=2 in the DCI. This allows the terminal device to receive the radio signals using reception settings based on the reference signals transmitted from each TRP while calibration is being performed between the first TRP111 and the second TRP112.

[0020] An example of the processing flow in this case is shown in Fig. 3. In this processing example, the second TRP 112 transmits an uncalibrated CSI-RS using resources identified by NZP-CSI-RS-ResourceSetID=1, which corresponds to TCI-state ID=1 (S301). The terminal device (UE) measures the CSI-RS and determines a reception configuration corresponding to TCI-state ID=1. Note that the second TRP 112 periodically transmits this CSI-RS, and the terminal device (UE) can measure the CSI-RS multiple times. Furthermore, the first TRP 111 transmits an uncalibrated CSI-RS using resources identified by NZP-CSI-RS-ResourceSetID=0, which corresponds to TCI-state ID=0 (S302). The terminal device performs the measurement and determines a reception configuration corresponding to TCI-state ID=0. Note that the first TRP 111 periodically transmits this CSI-RS, and the terminal device can measure the CSI-RS multiple times. After that, the gNB 101 transmits to the terminal device (S303) a DCI (a downlink control channel (PDCCH) including) in which information corresponding to TCI state ID=1, which corresponds to only the second TRP 112 transmitting data without calibration, is set. Here, in the DCI, an index of 0 to 7 is assigned to each enabled TCI state, and information indicating the TCI state ID is indicated by the index. However, hereinafter, the inclusion (setting) of an index value corresponding to the ID in the DCI will be expressed as "the TCI state ID is included (set)." 3 shows an example in which the gNB 101 transmits DCI to the UE using the first TRP 111, but for example, the DCI may be transmitted using the second TRP 112, or may be transmitted using both the first TRP 111 and the second TRP 112. When the terminal device recognizes the value of the TCI state ID indicated in this DCI, it receives subsequent data using the reception configuration determined based on the CSI-RS transmitted from the second TRP 112 without calibration.As a result, the terminal device performs communications such as receiving a signal (PDSCH) transmitted from the second TRP 112 without calibration and transmitting a composite automatic repeat request acknowledgement (HARQ-ACK) for that PDSCH (S304).

[0021] Here, the gNB101 requests the terminal device to provide assistance information in order to perform calibration between the first TRP111 and the second TRP112, for example (S305). For example, the gNB101 transmits to the terminal device a control signal (PDCCH) requesting the measurement result of the CSI-RS from the first TRP111 and the measurement result of the CSI-RS from the second TRP112. Then, the terminal device transmits the assistance information (UE assistance information) to the gNB101 (S306). According to the information on these measurement results, the phase of the channel estimation value and the rotation speed per time of that phase are identified, and the gNB101 can identify the frequency deviation during reception of each TRP based on this information. Then, the gNB101 identifies the frequency of each TRP based on the difference between the frequency in a state where calibration is not performed in each TRP and the frequency used as a reference for reception in the terminal device, and during calibration, matches the frequencies between the TRPs based on the identified frequency difference. Furthermore, the terminal device may notify the gNB101 of information specifying the reception timing of a signal from each TRP. In this case, the gNB101 adjusts the transmission timing of a signal in each TRP during calibration according to the difference in the reception timing of the signal from each TRP. Note that FIG. 2 illustrates an example in which the gNB101 transmits a control signal using the first TRP111 and the terminal device transmits auxiliary information to the second TRP112, but this is not limiting. That is, the control signal may be transmitted via the second TRP112, and the auxiliary information may be transmitted to the first TRP111. Furthermore, transmission and reception of the control signal and auxiliary information may be performed using both the first TRP111 and the second TRP112.

[0022] Then, the gNB101 transmits the CSI-RS after calibration between the first TRP111 and the second TRP112 from both the first TRP111 and the second TRP112 based on the auxiliary information (S307, S308). At this time, the first TRP111 and the second TRP112 transmit the CSI-RS on resources identified by NZP-CSI-RS-ResourceSetID=2, which corresponds to the TCI state (TCI-state ID=2) after calibration between the TRPs. In this case, too, the first TRP111 and the second TRP112 periodically transmit this CSI-RS, and the terminal device can measure the CSI-RS multiple times. Thereafter, the gNB101 transmits to the terminal device (S309) DCI (including a PDCCH) in which the TCI state ID is set to 2, which corresponds to data transmission in a state in which the first TRP111 and the second TRP112 have been calibrated. Note that the gNB101 may transmit the DCI to the UE using only the first TRP111, or may transmit the DCI using only the second TRP112, or both the first TRP111 and the second TRP112. When the terminal device recognizes the value of the TCI state ID indicated in this DCI, it receives subsequent data using a reception setting determined based on the CSI-RS transmitted from the first TRP111 and the second TRP112 in a state in which calibration has been performed. As a result, the terminal device performs communications between the first TRP 111 and the second TRP 112, such as receiving signals (PDSCH) transmitted from these TRPs in a calibrated state and transmitting a composite automatic repeat request acknowledgment response (HARQ-ACK) for the PDSCH (S310, S311). This makes it possible to prevent the terminal device from receiving the PDSCH transmitted from the second TRP 112 in S304, for example, using a reception setting based on the CSI-RS calibrated between the TRPs.It is also possible to prevent the terminal device from receiving the PDSCH transmitted from the first TRP 111 and the second TRP 112 in S310 and S311 using a reception setting based on CSI-RS for which calibration between the TRPs has not been performed.

[0023] In addition, in FIG. 3, an example has been described in which a TCI state ID is used to indicate whether a reception configuration based on a CSI-RS with inter-TRP calibration should be used or whether a reception configuration based on a CSI-RS with no inter-TRP calibration should be used. However, this is just an example, and other information may be used. For example, as shown in FIG. 4, for one TCI state, information on a reference signal when inter-TRP calibration is not performed and information on a reference signal when inter-TRP calibration is performed are prepared. In FIG. 4, "referenceSignal" indicates information on a reference signal when inter-TRP calibration is not performed, and "referenceSignal-cal" indicates information on a reference signal when inter-TRP calibration is performed. For example, NZP-CSI-RS-ResourceSetID=0 and NZP-CSI-RS-ResourceSetID=2 are associated with TCI state ID=0. Furthermore, NZP-CSI-RS-ResourceSetID=1 and NZP-CSI-RS-ResourceSetID=2 are associated with TCI state ID=1. That is, in the examples of Figures 2 and 3, an example is shown in which a TCI state with TCI state ID=2 corresponding to NZP-CSI-RS-ResourceSetID=2 is prepared, but here, such a TCI state is not prepared.

[0024] Then, the gNB101 uses resources for each reference signal to transmit the CSI-RS after inter-TRP calibration has been performed and the CSI-RS in a state where inter-TRP calibration has not been performed, and the terminal device measures these reference signals and prepares their respective reception settings. After that, the gNB101 includes information indicating whether inter-TRP calibration has been performed or not in DCI together with information indicating the TCI state, and transmits this to the terminal device. An example of the processing flow in this case is shown in FIG. 5. Note that in FIG. 5, the same processes as in FIG. 3 are assigned the same reference symbols. In the processing example of FIG. 5, the first TRP 111 and the second TRP 112 each transmit a CSI-RS in a state where inter-TRP calibration has not been performed (S301, S302) and a CSI-RS in a state where inter-TRP calibration has been performed (S307, S308), and the terminal device performs the measurements and determines the reception settings. In this processing example, gNB101 then transmits information (cal_flg) indicating whether or not signaling is performed when calibration between TRPs has been performed, together with the TCI state ID, in DCI (S501, S502).

[0025] 5, for TCI state ID=1, cal_flg=0 (no calibration) is associated with NZP-CSI-RS-ResourceSetID=1, and cal_flg=1 (with calibration) is associated with NZP-CSI-RS-ResourceSetID=2. Then, in S501, the gNB 101 transmits DCI including TCI state ID=1 and cal_flg=0 to indicate that subsequent signals will be transmitted from the second TRP 112 in a state without inter-TRP calibration. Also, in S502, the gNB 101 transmits DCI including TCI state ID=1 and cal_flg=1 to indicate that subsequent signals will be transmitted from the first TRP 111 and the second TRP 112 in a state after inter-TRP calibration. In this way, by using information (flag) other than the TCI state ID in combination with the TCI state ID, when the number of TCI states enabled in a terminal device is limited to a small number, it is possible to prevent a part of the small number of TCI states from being used to transmit a signal corresponding to whether or not inter-TRP calibration has been performed. Note that, for example, a DCI including cal_flg information may be transmitted when inter-TRP calibration has been performed, and a DCI not including cal_flg information may be transmitted when inter-TRP calibration has not been performed. In other words, whether or not cal_flg information is included may correspond to whether or not inter-TRP calibration has been performed. Furthermore, it is naturally possible to increase the number of TCI states enabled in the terminal device (the number of bits for specifying the TCI state in the DCI) without using cal_flg information, and perform the processing as shown in FIG. 3.

[0026] Although the above example describes the case where two TRPs are used, the number of TRPs may be three or more. An example of processing in this case is shown in FIG. 6. FIG. 6 shows a processing flow when a third TRP (not shown in FIG. 1) is used in addition to the first TRP 111 and the second TRP 112. Here, the third TRP is used alone or together with the second TRP 112. When the third TRP is used together with the second TRP 112, calibration is performed between these TRPs. At this time, for example, it is assumed that an uncalibrated CSI-RS is transmitted from the third TRP using resources identified by NZP-CSI-RS-ResourceSetID=3 (S601). Furthermore, the CSI-RS in a state in which calibration has been performed between the second TRP 112 and the third TRP is transmitted from the second TRP 112 and the third TRP on the resources identified by NZP-CSI-RS-ResourceSetID=4 (S602, S603).

[0027] In this case, these NZP-CSI-RS-ResourceSetIDs may be associated with different TCI states, or may be associated with, for example, one TCI state. For example, for TCI state ID=1, in addition to "referenceSignal" and "referenceSignal-cal" in FIG. 4, information such as "referenceSignal-cal2" may be added. Then, NZP-CSI-RS-ResourceSetID=4 may be specified as the information for "referenceSignal-cal2." In this case, for example, the gNB 101 may transmit DCI including TCI state ID=1 and cal_flg=0, thereby indicating that subsequent signals will be transmitted from the second TRP 112 without inter-TRP calibration. Furthermore, the gNB 101 transmits a DCI including TCI state ID=1 and cal_flg=1 to indicate that subsequent signals will be transmitted from the first TRP 111 and the second TRP 112 in a state in which inter-TRP calibration has been performed (S502, S310, S311). Furthermore, the gNB 101 transmits a DCI including TCI state ID=1 and cal_flg=2 to indicate that subsequent signals will be transmitted from the first TRP 111 and the second TRP 112 in a state in which inter-TRP calibration has been performed (S604, S605, S606). Note that when each NZP-CSI-RS-ResourceSetID is associated with a separate TCI state, as shown in FIG. 3, for example, a TCI state ID associated with resources from which CSI-RS in a state in which calibration has been performed between the second TRP 112 and the third TRP should be transmitted may be included in the DCI and transmitted in S604. In this case, for example, the TCI state ID when communication is performed without calibration in each TRP and the TCI state ID when calibration is performed between TRPs in any combination of TRPs are set to be different from each other.Then, gNB101 may select one TRP or a combination of two or more TRPs to use for communication and transmit DCI with a TCI state ID corresponding to the selected TRP or combination of TRPs.

[0028] As in the above example, reference signal information can be defined for cases where calibration is performed between three or more TRPs. In this case, a separate TCI state or a combination of information such as a TCI state and cal_flg is associated with any combination of TRPs. Each TRP transmits a calibrated CSI-RS and an uncalibrated CSI-RS using separate resources. The gNB 101 transmits a DCI specifying a TCI state ID or a combination of a TCI state ID and cal_flg to the terminal device according to the TRP used when transmitting data to the terminal device. In this way, when three or more TRPs are used, if any one or more of the three or more TRPs are used, the terminal device can perform reception processing corresponding to whether or not calibration between the TRPs has been performed.

[0029] Note that calibration between TRPs may be performed based on the frequency used in one TRP and the reception timing of a signal transmitted from that TRP in a terminal device. That is, calibration between the first TRP 111 and the second TRP 112 may be performed by, for example, adjusting the frequency of the second TRP 112 to match the frequency used in the first TRP 111. Also, based on the reception timing of the main wave of the signal transmitted from the first TRP 111 in the terminal device, the transmission timing of the signal from the second TRP 112 is adjusted so that the main wave of the signal from the second TRP 112 is received by the terminal device at that timing. Note that this is just an example, and a reference frequency or timing may be specified separately.

[0030] In addition, the terminal device can reuse, for example, the channel estimation result in a state where inter-TRP calibration is not performed in a state where inter-TRP calibration is performed. For example, when only transmission timing calibration is performed for a specific TRP, the frequency-related characteristics can be considered to be common to those in a state where inter-TRP calibration is not performed. In this case, the delay spread can also be considered to be common between a state where inter-TRP calibration is performed and a state where inter-TRP calibration is not performed. In addition, for example, when only frequency calibration is performed for a specific TRP, the delay-related characteristics can be considered to be common to those in a state where inter-TRP calibration is not performed. In this case, the Doppler spread can also be considered to be common between a state where inter-TRP calibration is performed and a state where inter-TRP calibration is not performed. Therefore, based on these characteristics that can be considered to be common, the terminal device can perform signal reception processing in a state where inter-TRP calibration is performed by utilizing the CSI-RS measurement result in a state where inter-TRP calibration is not performed. For example, by utilizing a channel estimation value based on the CSI-RS in a state where inter-TRP calibration is not performed, it is possible to improve the accuracy of channel estimation in a state where inter-TRP calibration is performed. In addition, in some cases, transmission of CSI-RS in a state where calibration is performed may be omitted.

[0031] Information indicating a QCL type (qcl-Type) exists as information for notifying a terminal device that such predetermined characteristics are common. qcl-Type is associated with TCI state, as shown in FIG. 2. Type A to type D shown in FIG. 7 have already been set as qcl-Types in the standard. In this embodiment, as shown in FIG. 7, type E, which relates to a case where only transmission timing calibration is performed for a predetermined TRP, and type F, which relates to a case where only frequency calibration is performed for a predetermined TRP, are newly defined. Note that "type E" and "type F" are merely for the purpose of explanation, and any name of information indicating that a value indicating channel characteristics obtained from a reference signal such as a CSI-RS in a state where calibration is not performed can be used in a state where calibration is performed. By notifying this information to the terminal device, the gNB 101 can indicate, in the terminal device, commonalities between channel characteristics in a case where inter-TRP calibration is not performed and channel characteristics in a case where inter-TRP calibration is performed. Based on this information, the terminal device can determine whether to use measurement results of reference signals in a state where inter-TRP calibration is not performed, and how to use the measurement results. For example, the terminal device can use the measurement result of the reference signal in a state where calibration is not performed in the reception process of the signal in a state where calibration between TRPs is performed. Also, for example, the terminal device can use the measurement result of the reference signal in a state where calibration is not performed to improve the accuracy of the channel estimation in a state where calibration is performed and determine the reception setting. Note that, based on this information, the terminal device may use the measurement result of the reference signal in a state where calibration is performed in a state where calibration is not performed.

[0032] Fig. 8 shows an example of information notified from the gNB 101 to the terminal device. The example in Fig. 8 shows an example in which two QCL-Infos are included in information (TCI-state) related to the TCI state when inter-TRP calibration is performed. Each of these two QCL-Infos includes information related to reference signals transmitted for one TRP without inter-TRP calibration.

[0033] For example, it is assumed that the resource from which the first TRP 111 transmits a reference signal in a state where inter-TRP calibration is not performed is indicated by NZP-CSI-RS-ResourceSetID = 0. Also, it is assumed that the resource from which the second TRP 112 transmits a reference signal in a state where inter-TRP calibration is not performed is indicated by NZP-CSI-RS-ResourceSetID = 1. In this case, when calibration is performed between the first TRP 111 and the second TRP 112, the TCI state includes QCL-Info1 for the first TRP 111 and QCL-Info2 for the second TRP 112.

[0034] For example, when the transmission timing of the second TRP 112 is adjusted based on the timing at which a signal transmitted from the first TRP 111 reaches the terminal device, the QCL-Info2 for the second TRP 112 specifies NZP-CSI-RS-ResourceSetID=1 and qcl-Type=typeE. That is, when transmitting a signal while inter-TRP calibration is being performed, the second TRP 112 specifies information about the CSI-RS in a state where inter-TRP calibration is not being performed (NZP-CSI-RS-ResourceSetID=1), and the characteristics of a channel that can be commonly used together with a channel estimate obtained by measuring the CSI-RS are indicated by qcl-Type. On the other hand, since no particular adjustment is performed on the first TRP 111, the QCL-Info1 for the first TRP 111 specifies NZP-CSI-RS-ResourceSetID=0 and qcl-Type=typeA. That is, it is indicated that the signal transmitted from the first TRP 111 can utilize the same channel characteristics as when transmitting CSI-RS in a state where inter-TRP calibration is not performed. Similarly, when the frequency of the second TRP 112 is adjusted based on the frequency of the signal transmitted from the first TRP 111, NZP-CSI-RS-ResourceSetID=1 and qcl-Type=typeF are specified in QCL-Info2, and NZP-CSI-RS-ResourceSetID=0 and qcl-Type=typeA are specified in QCL-Info1. Note that, for example, when communication is performed by performing calibration between three or more TRPs, one TCI-state may include QCL-Info according to the number of TRPs. That is, for each TRP, QCL-Info storing information (NZP-CSI-RS-ResourceSetID) and qcl-Type regarding the reference signal in a state where inter-TRP calibration is not performed may be prepared.

[0035] An example of the processing flow in this case is shown in Figure 9. Note that processes similar to those in Figure 3 are assigned common reference symbols as in Figure 3 and will not be described again. In this processing example, the terminal device measures reference signals transmitted by the first TRP 111 and the second TRP 112 in a state where calibration is not performed (S301, S302). Then, when a signal is subsequently transmitted in a state where calibration is performed, a DCI with TCI state ID set to "2" is transmitted from the gNB 101 to the terminal device. Note that the TCI-state corresponding to TCI state ID = 2 includes the above-mentioned QCL-Info1 and QCL-Info2, and this information is assumed to have been notified to the UE in advance. Based on the information in this TCI-state, the terminal device uses the results of measuring the CSI-RS in S301 and S302 to communicate with the first TRP 111 and the second TRP 112 in a state where inter-TRP calibration is performed (S901, S902). In this way, by newly defining the qcl-Type information, it becomes possible to use the result of channel estimation using a reference signal transmitted without performing calibration between multiple TRPs for processing such as receiving a signal transmitted with calibration. Note that the terminal device can use the qcl-Type information for reception processing, but it is not necessarily required to use it. In other words, it is sufficient for the terminal device to have a reception processing function configured to be able to use the information.

[0036] In the above example, a qcl-Type has been described that enables the measurement results of CSI-RS when inter-TRP calibration is not performed to be used in communication when inter-TRP calibration is performed. Separately, a qcl-Type may be defined that enables timing synchronization, timing correction, frequency synchronization, frequency correction, and the like to be performed using SSB. For example, the qcl-Type between an SSB and a CSI-RS transmitted from one TRP is typically type C. As shown in FIG. 10, the SSB and the CSI-RS are associated with each other by including an identifier (TCI-StateId) of the TCI-state of the SSB in information about the CSI-RS resource (NZP-CSI-RS-Resource associated with NZP-CSI-RS-ResourceSet). The qcl-Type in the QCL-Info of the CSI-RS is specified as type G or type H, for example, as shown in FIG. 7. For example, the channel through which the CSI-RS is transmitted after transmission timing calibration does not maintain the same delay characteristics as the channel through which the SSB is transmitted, but maintains the same frequency characteristics. For this reason, type G is specified as the qcl-Type in this case. Also, for example, the channel when the CSI-RS after frequency calibration is performed does not maintain frequency characteristics compared to the channel when the SSB is transmitted, but maintains delay characteristics. For this reason, type H is specified as the qcl-Type in this case. Then, the terminal device can perform timing correction and frequency correction, for example, by using a channel estimation value by the SSB and a channel estimation value by the CSI-RS in combination. For example, to establish synchronization and correct frequency for a specific TRP, the terminal device can use a CSI-RS for which timing calibration between TRPs has been performed in addition to an SSB and a CSI-RS with a qcl-Type of type C between the SSB (for example, a CSI-RS in a state where inter-TRP calibration has not been performed).Furthermore, in order to establish synchronization and correct timing for a specific TRP, the terminal device can use a CSI-RS that has been calibrated between TRPs in terms of frequency, in addition to an SSB and a CSI-RS whose qcl-Type between the SSBs is type C. In this way, by indicating to the terminal device that the calibrated CSI-RS can be used in addition to the SSB and the CSI-RS before calibration for frequency and timing synchronization and correction in the terminal device, it is possible to improve the synchronization accuracy between the terminal device and the gNB 101, for example.

[0037] 11 shows an example of a procedure for frequency / timing synchronization / adjustment using SSB and CSI-RS. In this processing example, when the first TRP 111 and the second TRP 112 perform inter-TRP calibration, the second TRP 112 operates to adjust the frequency and timing of the signal transmitted by the first TRP 111. That is, even when inter-TRP calibration is performed, the first TRP 111 does not particularly change the frequency or timing. The first TRP 111 and the second TRP 112 transmit SSB without performing inter-TRP calibration (S1101, S1102). Furthermore, the first TRP 111 and the second TRP 112 transmit CSI-RS without performing inter-TRP calibration (S1103, S1104). The terminal device receives the SSB and establishes synchronization of the frequency and reception timing for each of the first TRP 111 and the second TRP 112 (S1106, S1107). The terminal device can also perform channel estimation based on the SSB. Here, the SSB and CSI-RS in a state where inter-TRP calibration has not been performed have a common reference frequency and transmission timing, and the qcl-Type of this CSI-RS is type C in relation to the SSB. Therefore, the terminal device can further adjust the frequency and reception timing between the first TRP 111 and the second TRP 112 based on the assumption that the Doppler shift and average delay of the channel estimated by the CSI-RS are common to those of the channel estimated using the SSB (S1106, S1107).

[0038] Note that even after inter-TRP calibration is performed, the CSI-RS from the first TRP 111 can be treated as having the same channel characteristics as the CSI-RS in an uncalibrated state, with only the transmitted resources being different. Therefore, although not shown in FIG. 11 , the terminal device can adjust the frequency and reception timing based on the calibrated CSI-RS transmitted from the first TRP 111, in the same way as the uncalibrated CSI-RS. On the other hand, the frequency and timing of the CSI-RS from the second TRP 112 may be changed by inter-TRP calibration. Therefore, if the terminal device adjusts the frequency and timing using the calibrated CSI-RS transmitted from the second TRP 112 in the same way as the uncalibrated CSI-RS, the terminal device may end up adjusting the frequency and timing to different frequencies and timings from those between the second TRP 112 and the original TRP 112. Therefore, when adjusting the frequency and timing for the second TRP 112, the terminal device treats the CSI-RS after inter-TRP calibration differently from the CSI-RS in an uncalibrated state.

[0039] For example, if the transmission timing is adjusted but the frequency is not adjusted in the second TRP 112 due to inter-TRP calibration, the terminal device treats the qcl-Type of the CSI-RS after the adjustment as type G in relation to the SSB. In this case, the gNB 101 may, for example, notify the terminal device in advance that the qcl-Type in relation between NZP-CSI-RS-ResourceSetID=2 and the SSB index of the SSB transmitted from the second TRP 112 is type G. Also, for example, if the frequency is adjusted but the transmission timing is not adjusted in the second TRP 112 due to inter-TRP calibration, the terminal device treats the qcl-Type of the CSI-RS after the adjustment as type H in relation to the SSB. In this case, the gNB 101 may, for example, notify the terminal device in advance that the qcl-Type in relation between NZP-CSI-RS-ResourceSetID=2 and the SSB index of the SSB transmitted from the second TRP 112 is type H. In this way, by newly defining the qcl-Type, it is possible to specify the relationship between the SSB and the CSI-RS after the calibration between the TRPs has been performed. Then, by notifying the terminal device of this qcl-Type information from the gNB 101, the terminal device can recognize that it can use the CSI-RS after the calibration between the TRPs has been performed in synchronization and adjustment of the frequency and timing of each TRP.

[0040] In addition to the relationship between the SSB and the CSI-RS after calibration, the relationship between the CSI-RS in an uncalibrated state and the CSI-RS in a calibrated state can also be used for synchronization and adjustment of the frequency and timing related to the second TRP 112. That is, the relationship between the CSI-RS in an uncalibrated state and the CSI-RS in a calibrated state can be specified such that the qcl-Type is type E or type F, as described above. Based on this information, the terminal device can improve the accuracy of synchronization and adjustment of the frequency and timing related to the second TRP 112.

[0041] As described above, the calibration between TRPs is performed based on the UE assistance information (S306 in FIG. 3) from the terminal device. Here, the UE assistance information is assumed to include, for example, information indicating time variations in the amplitude and phase of the channel estimated based on the CSI-RS for each of the multiple TRPs. According to this, when the terminal device uses a common frequency to receive the CSI-RS corresponding to each TRP, the gNB 101 or each TRP can determine the error between the common frequency and the frequency used in each TRP from the phase rotation amount of the channel estimation value obtained based on the CSI-RS. Furthermore, the gNB 101 or each TRP can determine the frequency difference between the TRPs to be calibrated based on the frequency error. An example of such a processing flow is shown in FIG. 12.

[0042] In the process of FIG. 12, the gNB 101 notifies the terminal device, for example, via the first TRP 111, of configuration information for causing the terminal device to report aperiodic measurement results of channel state information (CSI) (S1201). This configuration information may include, for example, a list (CSI-AperiodicTriggerStateList) of information (CSI-AperiodicTriggerState) related to measurement reports for each of a plurality of TRPs. FIG. 13 schematically illustrates the information notified to the terminal device. The CSI-AperiodicTriggerStateList includes, for example, a plurality of CSI-AperiodicTriggerStates (two in the example of FIG. 13). The CSI-AperiodicTriggerState includes an identifier for reporting (CSI-ReportConfigId), information on resources (NZP-CSI-RS-ResourceSetID) on which CSI-RS is transmitted, and information (TCI-StateId) indicating the TCI state to be used by the terminal device. Note that this configuration information is individually transmitted to the terminal device using, for example, a radio resource control (RRC) message (e.g., an RRC Reconfiguration message). Note that, for example, when the number of CSI-AperiodicTriggerStates included in this configuration information exceeds a predetermined number, the gNB101 selects a part of the large number of CSI-AperiodicTriggerStates and notifies the terminal device that the selected configuration information should be enabled (S1202). Note that the predetermined number is determined according to the number of bits used in the DCI to specify which configuration a report is based on. For example, when a 3-bit field is provided in the DCI to specify which configuration to use and the CSI-AperiodicTriggerStateList includes nine or more CSI-AperiodicTriggerStates, up to eight CSI-AperiodicTriggerStates can be selected and enabled from the nine or more CSI-AperiodicTriggerStates.Note that, in cases where all settings in the CSI-AperiodicTriggerStateList should be enabled, such as when the number of CSI-AperiodicTriggerStates is equal to or less than a predetermined number, the processing of S1202 can be omitted.

[0043] The terminal device measures the CSI-RS in the resources indicated by the NZP-CSI-RS-ResourceSetID included in the enabled reporting configuration, using the reception configuration of the TCI state included in the reporting configuration. For example, the terminal device measures the CSI-RS transmitted from the second TRP 112 on the resources corresponding to NZP-CSI-RS-ResourceSetID=1, using the reception configuration of the TCI state with TCI-stateId=1 (S1203). Furthermore, the terminal device measures the CSI-RS transmitted from the first TRP 111 on the resources corresponding to NZP-CSI-RS-ResourceSetID=0, using the reception configuration of the TCI state with TCI-stateId=0 (S1206). Note that the CSI-RS is repeatedly transmitted from each TRP, and the terminal device can repeatedly measure the repeatedly transmitted CSI-RS. Thereafter, the gNB 101 transmits an instruction to the terminal device, for example, via the first TRP 111, to perform a CSI measurement report based on CSI-AperiodicTriggerState:1 (S1204). This instruction is transmitted, for example, using DCI (or a PDCCH including DCI). Furthermore, the fact that a CSI measurement report based on CSI-AperiodicTriggerState:1 should be performed can be indicated by specifying an associated CSI-ReportConfigId. In accordance with this instruction, the terminal device transmits UE assistance information including the measurement results of the CSI-RS transmitted from the second TRP 112 to the gNB 101 (S1205). Note that while FIG. 12 illustrates an example in which the UE assistance information is transmitted to the second TRP 112, this information may also be transmitted to the first TRP 111. For example, information about the first TRP 111 may be transmitted to the first TRP 111, and information about the second TRP 112 may be transmitted to the second TRP 112, or, for example, the DCI of S1204 may specify to which TRP the information should be transmitted. Also, for example, a primary TRP may be preset, and control information may always be transmitted to the primary TRP.Furthermore, the base station device may request the terminal device to report measurement results of CSI-RS related to not only the second TRP 112 but also the first TRP 111 (S1207). Then, based on this request, the terminal device transmits the measurement report results related to CSI-RS transmitted from the first TRP 111 to the gNB 101 (via at least one of the first TRP 111 and the second TRP 112) (S1208).

[0044] According to this processing, based on the measurement results of the CSI-RS transmitted from multiple TRPs in the terminal device, the gNB 101 can identify the error between the frequency used to receive signals in the terminal device and the frequency used to transmit signals in each TRP. As a result, the gNB 101 can identify the frequency difference between multiple TRPs to be calibrated, and when calibration between TRPs is required, can perform control to adjust the frequency of at least one TRP so that the frequency difference is eliminated. Note that, for example, if the frequencies used to receive signals from each TRP are not common in the terminal device, information on the frequencies used for receiving signals from each TRP can be notified to the gNB 101. As a result, even if the terminal device performs reception processing using different frequencies for each TRP, it is possible to identify the frequencies used to transmit signals from the multiple TRPs.

[0045] On the other hand, in order to calibrate the frequencies between TRPs, it is sufficient to be able to identify the frequency difference between the TRPs, and it is not necessary to identify the measurement results of the CSI-RS for each TRP. For this reason, for example, in this embodiment, only information that enables the frequency difference to be identified is transmitted. For example, a terminal device measures the CSI-RS from each TRP using a common reception setting (reception frequency), and the difference value of the channel estimation value (for example, the phase on the I (in-phase)-Q (quadrature) plane) indicated by the measurement result is reported to the gNB 101. Also, for example, instead of the difference value of the phase of the channel estimation value, the difference value of the rotation speed of the phase of the channel estimation value may be reported to the gNB 101. In other words, the reference frequency used for reception in the terminal device and the reference frequency used for transmission in each of the first TRP 111 and the second TRP 112 rarely completely match. It is assumed that the channel estimate value between the first TRP111 and the second TRP112 rotates due to the frequency difference between the first TRP111 and the second TRP112, and that the channel estimate value between the first TRP111 and the second TRP112 also rotates due to the frequency difference between the second TRP112 and the first TRP111. If the difference in the rotation speed of the phase of the channel estimate value between each of these TRPs can be identified, the frequency difference between the first TRP111 and the second TRP112 can be sufficiently reduced by, for example, adjusting the frequency of the second TRP112 or the phase of the signal by the frequency difference corresponding to the rotation speed difference. The terminal device can then adjust the frequency used for reception according to, for example, the phase rotation speed of the channel estimate value between the first TRP111 and the second TRP112, or perform demodulation processing taking the phase rotation into consideration, thereby enabling high-accuracy reception and demodulation of signals in a calibrated state. This reduces the amount of information, or allows information that can identify the frequency difference in more detail to be notified to the gNB101.

[0046] In this embodiment, as shown in Fig. 14, information on resources (NZP-CSI-RS-ResourceSetID) on which CSI-RS from each TRP is transmitted and a TCI-StateId corresponding to the reception configuration to be used are associated with one CSI-AperiodicTriggerState. Then, for example, an identifier (CSI-ReportConfigId) different from the identifier of the configuration information as shown in Fig. 13 is assigned to this CSI-AperiodicTriggerState. Fig. 14 shows a CSI-AperiodicTriggerState with CSI-ReportConfigId=2, which includes resources (NZP-CSI-RS-ResourceSetID=0) on which CSI-RS from the first TRP 111 is transmitted, resources (NZP-CSI-RS-ResourceSetID=1) on which CSI-RS from the second TRP 112 is transmitted, and a TCI state (TCI-StateId=0) associated with reception processing of a signal from the first TRP 111, for example. Then, gNB101 can request information on the difference value from the terminal device by transmitting DCI that specifies the CSI-ReportConfigId.

[0047] 15 shows a processing flow when UE assistance information is provided from the terminal device to the gNB 101 when such configuration information is used. In this processing, the gNB 101 provides the terminal device with configuration information including information such as that shown in FIG. 14 via, for example, the first TRP 111 (S1501). Thereafter, the gNB 101 notifies the terminal device of information on the configuration information to be enabled as necessary (S1502). Then, the terminal device measures the CSI-RS transmitted from the first TRP 111 and the second TRP 112 (S1503, S1504). Thereafter, the gNB 101 transmits DCI specifying CSI-ReportConfigId=2, and requests the terminal device for information on the phase difference value between the channel between the first TRP 111 and the channel between the gNB 101 and the second TRP 112 (S1505). Then, in response to the request, the terminal device provides information on the difference value (for example, for the second TRP 112) to the gNB 101 (S1506). By reporting the difference value in this way, it is no longer necessary to report separate information for each TRP, and therefore the amount of information to be reported can be reduced. Furthermore, by using the reduced amount of information to increase the number of bits of the reported information, the granularity of the reported information can be made finer, and the accuracy of control can be improved. For example, when phase difference information is represented using 4 bits, the phase difference can only be expressed in units of 360 / 16 = 22.5 degrees. However, by increasing this to 6 bits, for example, it becomes possible to express the phase difference in units of approximately 6 degrees, making it possible to determine the rate of increase / decrease of the phase difference with high accuracy and to determine the frequency difference with high accuracy. Note that the setting for reporting the phase difference can coexist with the setting for CSI-RS measurement reporting for each TRP. For example, in the processing of FIG. 15, by transmitting DCI with CSI-ReportConfigId=0 or 1 specified as in FIG. 12, it is possible to transmit the measurement results of the CSI-RS transmitted from each TRP, instead of the differential value, from the terminal device to gNB101.

[0048] FIG. 15 shows an example of a process for identifying a frequency difference between TRPs. Alternatively or in addition to this, a process may be performed in which a terminal device reports a difference in reception timing of CSI-RS. For example, in multiple TRPs to be calibrated, resources from which CSI-RS is transmitted from each TRP are configured so that the CSI-RS is transmitted at the same timing. For example, resources to be used are configured so that the resources from which CSI-RS is transmitted from the second TRP 112 are transmitted at the same timing as the resources from which CSI-RS is transmitted from the first TRP 111. Furthermore, the gNB 101 transmits configuration information such as that shown in FIG. 14 to the terminal device. Then, the terminal device measures the difference in reception timing and reports the time difference to the base station device. For example, as shown in FIG. 16, CSI-RS is transmitted simultaneously from the first TRP 111 and the second TRP 112 (S1601, S1602), and the terminal device measures these CSI-RS. Then, in response to receiving an instruction from the gNB 101 (S1505), the terminal device reports the measurement result of the reception time difference of these CSI-RSs to the gNB 101 (S1603). This allows the gNB 101 to identify the time difference until signals transmitted simultaneously from each TRP reach the terminal device. For example, if the CSI-RS from the first TRP 111 is received earlier than the CSI-RS from the second TRP 112 by ΔT, and calibration is performed between the first TRP 111 and the second TRP 112, the transmission timing of the signal from the second TRP 112 is advanced by ΔT. This allows the signals transmitted from the first TRP 111 and the second TRP 112 to be received simultaneously at the terminal device. Note that the terminal device can also measure and report the frequency difference along with measuring and reporting this time difference. That is, in the processing of FIG. 15, by making the resource for transmitting the CSI-RS in S1503 the resource with the same timing as the resource for transmitting the CSI-RS in S1504, the terminal device is able to measure the time difference and frequency difference at the same time.

[0049] FIG. 17 shows an example of the hardware configuration of a base station device (gNB101) and terminal devices (terminal device 121, terminal device 122) according to this embodiment. In one example, the base station device and terminal device are configured to include a processor 1701, a ROM 1702, a RAM 1703, a storage device 1704, and a communication circuit 1705. The processor 1701 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 performs the overall processing of the device and each of the above-mentioned processes by reading and executing programs stored in the ROM 1702 or the storage device 1704. The ROM 1702 is a read-only memory that stores information such as programs related to the processing executed by the base station device and terminal devices, various parameters, etc. The RAM 1703 functions as a workspace when the processor 1701 executes a program, and is also a random access memory that stores temporary information. The storage device 1704 is configured, for example, by a removable external storage device. The communication circuit 1705 is configured, for example, by a circuit for wireless communication of 5G or a successor standard. Although one communication circuit 1705 is illustrated in FIG. 17 , the base station apparatus and the terminal apparatus may have multiple communication circuits. For example, the base station apparatus and the terminal apparatus may have wireless communication circuits for 5G and a successor standard, respectively, and a common antenna for these circuits. The base station apparatus and the terminal apparatus may also have separate antennas suitable for each standard. The base station apparatus may also have a wired communication circuit used when communicating with other base station apparatuses or nodes in the core network. The terminal apparatus may also 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 apparatus and the terminal apparatus may have separate communication circuits 1705 for each of multiple available frequency bands, or may have a common communication circuit 1705 for at least some of these frequency bands.

[0050] FIG. 18 shows an example of the functional configuration of a base station device. The base station device includes, for example, a setting unit 1801, a report receiving unit 1802, a calibration control unit 1803, and a communication control unit 1804. Note that FIG. 18 only shows functions particularly related to this embodiment, and various other functions that the base station device may have are omitted from the illustration. For example, the base station device naturally has other functions that base station devices compliant with 5G and subsequent standards generally have. The functional blocks in FIG. 18 are shown schematically, and the respective functional blocks may be integrated or further subdivided. Each function in FIG. 18 may be realized, for example, by the processor 1701 executing a program stored in the ROM 1702 or the storage device 1704, or may be realized by a processor within the communication circuit 1705 executing predetermined software. Details of the processing performed by each functional unit will not be described here, and only their general functions will be outlined.

[0051] The setting unit 1801, for example, prepares separate resource configurations for transmitting reference signals (e.g., CSI-RS) when inter-TRP calibration is performed and resource configurations for transmitting reference signals when the calibration is not performed, and notifies the terminal device of configuration information including information for distinguishing between the configurations, such as a TCI state ID. The setting unit 1801 can generate the configuration information described above using, for example, FIG. 2, FIG. 4, etc., and notify the terminal device of the configuration information. The setting unit 1801 can also transmit to the terminal device configuration information as shown in FIG. 8, including information indicating whether a channel estimation result based on another reference signal is usable, such as qcl-Type as shown in FIG. 7. The setting unit 1801 can also generate configuration information as shown in FIG. 13 or FIG. 14 when causing the terminal device to perform measurements to identify a frequency difference or a timing difference for performing calibration, and transmit the configuration information to the terminal device. The report receiving unit 1802, for example, receives UE assistance information from the terminal device. Note that the report receiving unit 1802 uses, for example, the setting information notified to the terminal device by the setting unit 1801 to determine which of the frequency difference and time difference information described with reference to FIG. 15 and FIG. 16 or the measurement results of CSI-RS from each TRP to report. Then, the report receiving unit 1802 transmits an instruction to the terminal device in which an identifier of the report setting corresponding to the determination is set, so that the terminal device receives a report according to the determination. For example, when inter-TRP calibration is performed, the calibration control unit 1803 adjusts the frequency and transmission timing of each TRP, and performs control so that the frequencies and reception timings (for example, of main waves) of signals from multiple TRPs are approximately matched in the terminal device. The communication control unit 1804 transmits DCI including information such as TCI state ID and cal_flg to the terminal device depending on whether inter-TRP calibration is performed when transmitting a signal, based on the information set in the setting unit 1801, and controls communication.

[0052] FIG. 19 shows an example of the functional configuration of a terminal device. The terminal device includes, for example, a setting receiving unit 1901, a report transmitting unit 1902, and a communication control unit 1903. Note that FIG. 19 only shows functions particularly related to this embodiment, and various other functions that the terminal device may have are omitted from the illustration. For example, the terminal device naturally has other functions that terminal devices compliant with 5G or subsequent standards generally have. The functional blocks in FIG. 19 are shown schematically, and the respective functional blocks may be integrated or further subdivided. Each function in FIG. 19 may be realized, for example, by the processor 1701 executing a program stored in the ROM 1702 or the storage device 1704, or may be realized by a processor within the communication circuit 1705 executing predetermined software. Details of the processing performed by each functional unit will not be described here, and only their general functions will be outlined.

[0053] The setting receiver 1901 receives setting information generated by the setting unit 1801 of the base station device. The report transmitter 1902 measures the CSI-RS transmitted from each TRP according to the setting information, and reports the channel estimation value or information on the phase difference and reception timing difference to the base station device in response to an instruction from the base station device. The communication controller 1903 controls communication. For example, the communication controller 1903 establishes and adjusts frequency synchronization and timing synchronization with each TRP by measuring reference signals. Furthermore, the communication controller 1903 establishes and adjusts frequency synchronization and timing synchronization when communicating simultaneously with multiple TRPs by measuring reference signals transmitted from the multiple TRPs (with inter-TRP calibration performed). At this time, the communication controller 1903 may recognize that measurement results of reference signals transmitted using different resources can be mutually utilized based on the qcl-Type information transmitted from the base station device. Then, the communication controller 1903 may establish frequency and timing synchronization and perform reception processing based on the qcl-Type information. Furthermore, the communication control unit 1903 configures a reception setting for each of the reference signals individually based on the measurement results of the reference signals transmitted using different resources. That is, a reception setting is configured for each reference signal resource. Then, when the communication control unit 1903 receives DCI transmitted from the base station device and including information specifying the reference signal resource, the communication control unit 1903 receives the signal from the base station device using the reception setting corresponding to the resource.

[0054] As described above, the terminal device in this embodiment prepares reception settings for each of a state in which calibration between TRPs is performed and a state in which calibration is not performed, using different reference signal settings. Then, the base station device transmits DCI containing identification information that specifies the corresponding reference signal setting depending on whether calibration is performed when communication is performed. The terminal device can perform reception processing appropriate for each of a state in which calibration is performed and a state in which calibration is not performed by using the reception setting corresponding to the identification information to perform reception processing of a signal from the base station device. Furthermore, the base station device can notify the terminal device of newly defined qcl-Type information so that, for example, channel characteristic values ​​obtained from measurement results of reference signals in a state in which calibration is not performed can be used in reception in a calibrated state. This notification allows the terminal device to effectively utilize channel characteristics and efficiently receive signals in a calibrated state. Furthermore, by defining new qcl-Type information, it becomes possible to use CSI-RS information after calibration between TRPs when establishing frequency and timing synchronization in each TRP. Furthermore, by transmitting the phase difference and reception timing difference of channel estimation values ​​between TRPs as UE assistance information, it is possible to reduce the amount of information or provide more detailed information. As described above, according to this embodiment, it is possible to efficiently operate a system in which a base station device simultaneously uses multiple TRPs to transmit signals to a terminal device, thereby contributing to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote sustainable industrialization, and foster innovation."

[0055] 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 communicates with a terminal device using a plurality of TRPs including a first transmission / reception point (TRP) and a second TRP, A notification means for notifying the terminal device of configuration information generated so that a first resource from which a channel state information-reference signal (CSI-RS) is transmitted from the first TRP when calibration is not performed between the first TRP and the second TRP is different from a second resource from which a CSI-RS is transmitted from the first TRP when calibration is performed between the first TRP and the second TRP; A transmitting means for transmitting first information associated with the first resource to the terminal device when transmitting a signal in a state where calibration has not been performed between the first TRP and the second TRP to the terminal device, and transmitting second information associated with the second resource to the terminal device when transmitting a signal in a state where calibration has been performed between the first TRP and the second TRP to the terminal device; A base station device comprising:

2. the notification means generates the configuration information so as to associate different Transmission Configuration Indicator (TCI) states with the first resource and the second resource, respectively; 2. The base station apparatus according to claim 1, wherein the first information corresponds to a first TCI state ID that identifies a TCI state associated with the first resource, and the second information corresponds to a second TCI state ID that identifies a TCI state associated with the second resource.

3. A resource for transmitting a CSI-RS when inter-TRP calibration is not performed in each of the plurality of TRPs, and a resource for transmitting a CSI-RS when inter-TRP calibration is performed in a combination of two or more of the plurality of TRPs, are associated with different TCI state IDs, The transmitting means transmits to the terminal device information corresponding to a TCI state ID corresponding to a TRP or a combination of TRPs used to transmit a signal to the terminal device; 3. The base station device according to claim 2, wherein:

4. the notification means generates the configuration information so as to associate a common Transmission Configuration Indicator (TCI) state with the first resource and the second resource; the first information is a combination of a TCI state ID for identifying the common TCI state and information indicating that calibration is performed, and the second information is a combination of a TCI state ID for identifying the common TCI state and information indicating that calibration is not performed.

2. The base station apparatus according to claim 1, wherein:

5. A terminal device, An acquisition means for acquiring, from a base station device that communicates with a terminal device using a plurality of TRPs including a first transmission / reception point (TRP) and a second TRP, configuration information generated so that a first resource from which a channel state information-reference signal (CSI-RS) is transmitted from the first TRP when calibration is not performed between the first TRP and the second TRP and a second resource from which a CSI-RS is transmitted from the first TRP when calibration is performed between the first TRP and the second TRP are different; a receiving means for receiving from the base station device either first information associated with the first resource or second information associated with the second resource; an execution means for, when receiving the first information, performing reception processing of a signal transmitted from the base station device after the first information based on a measurement result of a CSI-RS transmitted in the first resource, and, when receiving the second information, performing reception processing of a signal transmitted from the base station device after the second information based on a measurement result of a CSI-RS transmitted in the second resource; A terminal device comprising:

6. the configuration information includes information associating different Transmission Configuration Indicator (TCI) states with the first resource and the second resource, respectively; The execution means When a first TCI state ID identifying a TCI state associated with the first resource is received as the first information, performing reception processing of a signal transmitted from the base station device after the first information based on a measurement result of a CSI-RS transmitted in the first resource; When a second TCI state ID identifying a TCI state associated with the second resource is received as the second information, receiving processing of a signal transmitted from the base station device after the second information is performed based on a measurement result of a CSI-RS transmitted in the second resource.

6. The terminal device according to claim 5,

7. A resource for transmitting a CSI-RS when inter-TRP calibration is not performed in each of the plurality of TRPs, and a resource for transmitting a CSI-RS when inter-TRP calibration is performed in a combination of two or more of the plurality of TRPs, are associated with different TCI state IDs, When the execution means receives information corresponding to a TCI state ID corresponding to a TRP or a combination of TRPs used to transmit a signal to the terminal device, the execution means executes reception processing of a signal transmitted from the base station device after the information is received based on a measurement result of a CSI-RS transmitted in a resource associated with the TCI state ID.

7. The terminal device according to claim 6,

8. the configuration information includes information associating a common Transmission Configuration Indicator (TCI) state with the first resource and the second resource; The execution means when a combination of a TCI state ID that identifies the common TCI state and information indicating that calibration is to be performed is received as the first information, performing reception processing of a signal transmitted from the base station device after the first information based on a measurement result of a CSI-RS transmitted in the first resource; When a combination of a TCI state ID that identifies the common TCI state and information indicating that calibration is not performed is received as the second information, receiving processing of a signal transmitted from the base station device after the second information is performed based on a measurement result of a CSI-RS transmitted in the second resource.

6. The terminal device according to claim 5,

9. A communication method executed by a base station device that communicates with a terminal device using a plurality of TRPs including a first transmission / reception point (TRP) and a second TRP, Notifying the terminal device of configuration information generated so that a first resource from which a channel state information-reference signal (CSI-RS) is transmitted from the first TRP when calibration is not performed between the first TRP and the second TRP is different from a second resource from which a CSI-RS is transmitted from the first TRP when calibration is performed between the first TRP and the second TRP; When transmitting a signal in a state where calibration has not been performed between the first TRP and the second TRP to the terminal device, transmitting first information associated with the first resource to the terminal device, and when transmitting a signal in a state where calibration has been performed between the first TRP and the second TRP to the terminal device, transmitting second information associated with the second resource to the terminal device; A communication method comprising:

10. A communication method performed by a terminal device, comprising: Acquire, from a base station device that communicates with a terminal device using a plurality of TRPs including a first transmission / reception point (TRP) and a second TRP, configuration information generated so that a first resource from which a channel state information-reference signal (CSI-RS) is transmitted from the first TRP when calibration is not performed between the first TRP and the second TRP is different from a second resource from which a CSI-RS is transmitted from the first TRP when calibration is performed between the first TRP and the second TRP; receiving, from the base station device, either first information associated with the first resource or second information associated with the second resource; When receiving the first information, performing reception processing of a signal transmitted from the base station device after the first information based on a measurement result of a CSI-RS transmitted in the first resource, and when receiving the second information, performing reception processing of a signal transmitted from the base station device after the second information based on a measurement result of a CSI-RS transmitted in the second resource; A communication method comprising:

11. A program for causing a computer to function as each of the means included in the base station device according to any one of claims 1 to 4.

12. A program for causing a computer to function as each of the means included in the terminal device according to any one of claims 5 to 8.

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