Terminal device, base station device, control method, and program for efficiently operating on-demand SSB in scell of carrier aggregation

Abstract

To provide a terminal device, a base station, a control method thereof, and a program for enabling execution of on-demand SSB operation in an Scell of carrier aggregation.SOLUTION: A terminal device conforming to a third generation partnership project (3GPP: registered mark) cellular communication standard receives second configuration information, for the case where at least a portion of a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) is not transmitted, from a base station device that provides a primary cell of carrier aggregation, the second configuration information being different from first configuration information for the case where transmission of the SSB in a secondary cell is not suppressed, performs measurement configuration of the SSB in the secondary cell on the basis of the second configuration information, and uses the measurement configuration to measure the SSB transmitted in the secondary cell.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a technique for applying on-demand SSB in a cellular communication system. [Background technology]

[0002] The Third Generation Partnership Project (3GPP) is currently discussing the reduction of network power consumption as a key issue. One of the key issues being discussed is the adoption of on-demand SSB operation, which suppresses the transmission of synchronization signals (SS) / physical broadcast channel (PBCH) blocks (SSBs) so that SSBs are transmitted only when necessary. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP (registered trademark) Contribution RP-234065 Summary of the Invention [Problem to be solved by the invention]

[0004] Non-Patent Document 1 points out that a method for supporting on-demand SSB operation in an Scell ​​in an environment where there is a terminal device in a connected state that performs communication using carrier aggregation should be considered. [Means for solving the problem]

[0005] The present invention provides a procedure for enabling on-demand SSB operation of an Scell ​​in carrier aggregation.

[0006] A terminal device according to one embodiment of the present invention is a terminal device that complies with the cellular communication standard of the 3rd Generation Partnership Project (3GPP), and has: a receiving means for receiving, from a base station device that provides a primary cell of carrier aggregation, second setting information for when at least a portion of a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) is not transmitted, which is different from first setting information for when transmission of the SSB in a secondary cell is not suppressed; a setting means for performing measurement settings for the SSB in the secondary cell based on the second setting information; and a measurement means for measuring the SSB transmitted in the secondary cell using the measurement settings.

[0007] A base station device according to one embodiment of the present invention is a base station device that complies with the cellular communication standard of the Third Generation Partnership Project (3GPP), and has: a providing means for providing a primary cell of carrier aggregation to a connected terminal device; and a transmitting means for transmitting to the terminal device second setting information for when at least a portion of a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) is not transmitted, which differs from first setting information for when transmission of the SSB in the secondary cell of the carrier aggregation is not suppressed. [Effects of the Invention]

[0008] According to the present invention, on-demand SSB operation of an Scell ​​in carrier aggregation can be performed. [Brief explanation of the drawings]

[0009] [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 an example of an SSB transmission pattern. [Figure 3] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication system. [Figure 4] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication system. [Figure 5] FIG. 1 is a diagram for explaining the settings for SSB measurement. [Figure 6] FIG. 1 is a diagram illustrating the relationship between Cell-DTX / DRX and SSB transmission. [Figure 7] FIG. 2 is a diagram illustrating an example of the hardware configuration of a base station device and a terminal device. [Figure 8] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. [Figure 9] FIG. 10 is a diagram illustrating an example of the functional configuration of a base station device of a Pcell. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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.

[0011] FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. The wireless communication system is a cellular communication system that complies with a cellular communication standard such as fifth generation (5G) of the Third Generation Partnership Project (3GPP (registered trademark)) or a successor standard thereof. In one example, the wireless communication system includes base station devices 101 to 103 and a terminal device 111. Note that while FIG. 1 shows only one terminal device and three base station devices, this is not limiting and a large number of terminal devices and base station devices may naturally be present. The base station devices 101 to 103 each form one or more cells. In the example of FIG. 1, the base station device 101 forms cells 121 and 122, the base station device 102 forms cell 123, and the base station device 103 forms cell 124. Note that FIG. 1 shows an example in which the base station device 102 and the base station device 103 each form only one cell, but they may each form multiple cells. 1 shows an example in which the base station device 101 forms the cell 122 that is included in the cell 121, but these cells may be formed to cover the same area. Furthermore, for example, the base station devices 101 to 103 may be implemented as transmission / reception points (TRPs) that are connected to a common gNodeB-Central Unit (gNB-CU) and located at geographically separate locations. Each cell may correspond to a component carrier (frequency band). Each cell may correspond to a different frequency band or a common frequency band. In this embodiment, at least the frequency band corresponding to the cell 121 is different from the frequency bands corresponding to the cells 122 to 124, and the frequency bands corresponding to the cells 122 to 124 may be different from each other or may be the same.

[0012] In this embodiment, it is assumed that the terminal device 111 is in an RRC connected state with the base station device 101, for example, with the cell 121 formed by the base station device 101 as a primary cell (Pcell). In this state, the terminal device 111 can perform communication via multiple cells (multiple component carriers) using a carrier aggregation (CA) function. The base station device 101 providing the Pcell to the terminal device 111 can transmit, to the terminal device 111, a radio resource control (RRC) message (for example, an RRC Reconfiguration message) in the cell 121, including a setting that enables the terminal device 111 to use cells 122 to 124 as secondary cells (Scells). Note that the terminal device 111 can establish a connection with an Scell ​​on the premise that a connection with the Pcell has been established (the terminal device 111 is in an RRC connected state with the base station device of the Pcell).

[0013] There are two methods for adding a secondary cell (Scell) in CA. In the first method, the network (base station device 101) adds an Scell ​​based on a measurement report of signal strength or signal quality from the terminal device 111. For example, when the signal strength or signal quality (e.g., Reference Signal Received Power (RSRP) or Reference Signal Received Quality (RSRQ)) of a cell that is a candidate for an Scell ​​(a neighboring cell such as cell 122 to cell 124 relative to cell 121 that is a Pcell) exceeds a predetermined threshold (e.g., when Event A4 specified in the standard occurs), the cell can be added as an Scell. Also, when the signal strength or signal quality of a cell set as an Scell ​​falls below a predetermined threshold (e.g., when Event A2 specified in the standard occurs), the cell can be deleted from the Scell. Here, the terminal device 111 can measure the signal strength or signal quality by, for example, observing a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) transmitted in each cell. In addition to measuring signal strength or signal quality, the SSB is also used by the terminal device 111 to acquire downlink time and frequency synchronization with the cell transmitting the SSB and basic system information. The method of adding an Scell ​​based on the measurement results of signal strength or signal quality requires a certain amount of time for processing, such as transmitting a measurement report from the terminal device to the base station device, and therefore a relatively long delay may occur until the addition of the Scell ​​is completed. On the other hand, this method can be applied to various scenarios, such as when the base station device providing the primary cell (Pcell) and the base station device providing the Scell ​​cannot be considered to be co-located. In the second method, the network adds an Scell ​​without using the measurement results of signal strength or signal quality by the terminal device. This method of adding an Scell ​​without using measurement results requires a relatively short time for the configuration process, thereby reducing the delay until the addition of the Scell ​​is completed. This method can be applied only when the base station device providing the Pcell and the base station device providing the Scell ​​can be considered to be co-located.The addition or deletion of an Scell ​​can be performed, for example, via a radio resource control (RRC) message.

[0014] Apart from adding or deleting an Scell, the added Scell ​​may be activated or deactivated. That is, the added Scell ​​may be activated when actually used, and deactivated when not used. The base station device 101 providing the Pcell may determine whether to activate or deactivate an Scell ​​(e.g., at least one of cells 122 to 124) based on, for example, an increase or decrease in throughput demand of the terminal device 111 or fluctuations in cell quality. Furthermore, the base station device 101 may determine whether to activate or deactivate an Scell ​​when adding an Scell ​​without based on a measurement report. Note that activation or deactivation may be indicated, for example, by an information element sCellState included in an RRC message. This information element sCellState may indicate whether the added Scell ​​is activated (whether it is in the activated state). Furthermore, based on a measurement report from the terminal device 111, a medium access control control element (MAC CE) may specify whether the Scell ​​should be activated or deactivated. This MAC CE may be called an activation / deactivation MAC CE. The terminal device 111 receives a MAC CE for activating an Scell, and after the Scell ​​is activated, starts a timer (scell deactivation timer). Then, when the timer expires or when the terminal device 111 receives a Deactivation MAC CE, the terminal device 111 deactivates the Scell.

[0015] As described above, it is important that the terminal device 111 be able to measure the signal strength or signal quality of an Scell ​​(or a candidate cell to be added as an Scell) in order to add or delete an Scell ​​and to enable or disable an added Scell. For such measurements, the terminal device 111 can receive information such as the SSB transmission period, number of beams, and beam direction (parameters indicating orientation and phase) of surrounding cells in an RRC message (e.g., an RRCReconfiguration message) transmitted from the base station device 101 of the currently connected Pcell. The terminal device 111 can acquire this information from an SSB bitmap specified by the ssb-positionsInBurst for the Scell ​​in the RRC message. Furthermore, the terminal device 111 identifies the timing, measurement period, measurement period, etc. for measuring the SSB of the added Scell ​​from the scellconfig in the RRC message (e.g., an RRCReconfiguration message) received in the Pcell. The terminal device 111 can check the SSB-based RRM Measurement Timing Configuration (SMTC) included in the scellconfig and identify the measurement start timing, measurement period, measurement cycle, etc. for each cell. The period during which this measurement is performed can be called the SMTC window. The terminal device 111 detects and measures the SSB of the Scell ​​during the SMTC window and reports the results to the base station device 101. Furthermore, information on the measurement period (SMTC) can be included in the measobjectNR, which is an information element in an RRC message. That is, the terminal device 111 can check the measobjectNR to identify the measurement period, measure the SSB of the Scell ​​during that period, and report the measurement results to the base station device 101.

[0016] Currently, there is a demand for network power saving, and therefore, suppressing SSB transmission in an Scell ​​is being considered. In this embodiment, such an Scell ​​in which SSB transmission is suppressed is referred to as an SSB-Less Scell. An SSB-Less Scell ​​is a cell, among cells configured as Scells for the terminal device 111, in which SSB transmission is stopped for power saving, the transmission cycle is longer than in non-power saving operation, or some SSBs are not transmitted. In one example, among Scells configured for the terminal device 111, a cell that is not activated and does not provide data communication services can be an SSB-Less Scell. Furthermore, in some cases, even an activated cell may operate as an SSB-Less Scell. For example, SSB transmission can be stopped or the transmission cycle can be extended in some of the beams formed by Scells that provide communication services to the terminal device.

[0017] Here, an example of a method for reducing transmission power by suppressing SSB transmission by an SSB-Less Scell ​​will be described using Figures 2(A) to 2(E). Note that Figure 2(A) shows a conventional case in which SSB transmission is not suppressed, and Figures 2(B) to 2(E) show examples in which SSB transmission is suppressed. Although not shown in Figures 2(A) to 2(E), the SSB-Less Scell ​​may not transmit SSBs at all for a predetermined period of time. In Figures 2(A) to 2(E), rectangles indicate frequency and time resources, and hatched areas indicate resources in which SSBs are transmitted. The example in Figure 2(A) shows a state in which resources in which SSBs are transmitted are provided every 20 milliseconds (ms), and SSBs are transmitted in time-division fashion in the directions of multiple beams formed within the cell using these resources. In an SSB-Less Scell, for example, as shown in FIG. 2(B), extending the SSB transmission period reduces SSB transmission opportunities and enables power saving. The example in FIG. 2(B) shows a case where the SSB transmission period is set to 160 ms. This reduces SSB transmission opportunities to 1 / 8, thereby reducing power consumption in the SSB-Less Scell. The period is not limited to this, and SSBs can be transmitted at periods shorter or longer than 160 ms. However, the period is set longer than when power saving operation is not performed. Furthermore, an SSB-Less Scell ​​can reduce SSB transmission opportunities by providing a separate beam with a wider beamwidth that collectively covers an area covered by multiple beams, as in the example in FIG. 2(C), and transmitting SSBs using that beam. In the state shown in FIG. 2(A), SSBs are transmitted using each of eight beams, whereas in the example in FIG. 2(C), SSBs are transmitted using two wider beamwidths. According to this, the number of SSB transmission opportunities is reduced to 1 / 4, so that the power related to SSB transmission in the SSB-Less Scell ​​can be reduced, and power consumption in the network can be reduced.Furthermore, for example, if it is possible to identify in advance one or more beams corresponding to the location of a terminal device to which communication services are to be provided, the SSB may be transmitted only using those one or more beams. The example of FIG. 2(D) shows a case in which the number of beams for transmitting SSBs is reduced from eight to four. This reduces the number of SSB transmission opportunities by half, thereby reducing the power required for SSB transmission in the SSB-less Scell ​​and thereby reducing network power consumption. Alternatively, as shown in FIG. 2(E), SSBs may be transmitted using all beams, but only some of the beams may be transmitted during a single SSB transmission opportunity. The example of FIG. 2(E) shows an example in which SSBs are transmitted using only four beams during a single SSB transmission opportunity (arriving every 20 ms). In this case, the number of SSBs transmitted during a single transmission opportunity is reduced by half, thereby reducing the power required for SSB transmission in the SSB-less Scell ​​and thereby reducing network power consumption.

[0018] As described above, in an SSB-Less Scell, SSBs can be transmitted in various patterns. Hereinafter, the configuration patterns for SSB transmission, such as those shown in FIGS. 2(A) to 2(E), are referred to as configuration patterns. When a terminal device performs measurements based on conventional measurement information, depending on the SSB configuration pattern, a situation may occur in which the SSB is not transmitted at the specified measurement timing, resulting in inefficiency. Furthermore, since the terminal device cannot recognize the existence of an SSB of an Scell ​​that is not being transmitted, it cannot perform processing using that SSB. Thus, when an SSB-Less Scell ​​is present, the operation efficiency of the system may decrease or the system operation may become unstable if the terminal device operates in the conventional manner. Therefore, this embodiment provides a procedure for efficiently operating an SSB-Less Scell.

[0019] <Notification of setting pattern information> The base station device of the Pcell generates SSB configuration pattern information of the SSB-Less Scell ​​for each of the above-mentioned multiple configuration patterns and notifies the terminal device of the generated information. The configuration pattern information includes information about the above-mentioned SSB configuration pattern, such as the frequency at which the SSB is transmitted (indicated, for example, by the variable ARFCN-ValueNR), the SSB transmission period (indicated, for example, by the variable ssb-periodicityServingCell), the number of beams (specified, for example, by the settings of shortbitmap, mediumbitmap, and longbitmap in ssb-PositionsInBurst), and the beam direction (for example, information indicating at least one of the direction of a beam in which the SSB is transmitted and the direction of a beam in which the SSB is not transmitted). Furthermore, the configuration pattern information may express some of the characteristics of the configuration pattern using the measurement period and timing (SSB-MTC) for SSB measurement. That is, information about the measurement period and timing for SSB measurement may be notified to the terminal device as part of the above-mentioned configuration pattern information.

[0020] Furthermore, the base station device of the Pcell may include, in the configuration pattern information, information indicating whether or not a reference signal, such as a tracking reference signal (TRS) or a channel state information-reference signal (CSI-RS), transmitted by the base station device itself has a common attribute with an SSB whose transmission is suppressed (stopped) in an SSB-less Scell. Whether or not the attribute is common may be notified to the terminal device using, for example, a Quasi Co-Location (QCL) specification (using information such as qcl-Type). For example, the base station device of the Pcell may form an Scell ​​in addition to the Pcell at the same location. Here, if beams are formed in the same direction in these cells, it is expected that the beams corresponding to the same direction in these cells have a common Doppler shift, Doppler spread, average delay, and delay spread, for example, if the frame transmission timings are the same. For this reason, when an Scell ​​is an SSB-Less Scell ​​and SSB transmission is stopped in some of its beams, the base station device of the Pcell may transmit to the terminal device, information indicating that the QCL type of the beam (SSB) whose transmission is stopped is qcl-Type A in relation to the corresponding beam (reference signal) of the Pcell, including the information in the configuration pattern information. If the reference signal of the Pcell and the SSB of the SSB-Less Scell ​​have common attributes, the measurement results of the reference signal of the Pcell can be reused for the SSB-Less Scell. For example, the terminal device can reuse the time and frequency synchronization obtained by the measurement results of the TRS of the Pcell for the SSB-Less Scell. In this case, the terminal device does not need to request SSB transmission from the SSB-Less Scell. Note that the relationship between the SSB (beam) of the SSB-Less Scell ​​and the SSB (beam) of another Scell ​​may be specified. In this embodiment, an SSB transmitted upon request is called an on-demand SSB. When a terminal device needs to receive an SSB for layer 1 or layer 3 measurements or other processing, it can request on-demand SSB transmission of an SSB-Less Scell ​​without relying on QCL.This information can be notified to the terminal device by, for example, an information element scellactivationRS-config for setting a reference signal for fast activation of an Scell. However, this is just one example, and this information may be notified by another existing information element, or a new information element may be defined.

[0021] Furthermore, the configuration pattern information may include information used by the terminal device to identify the SSB index of an SSB whose transmission is suppressed in the SSB-Less Scell ​​based on synchronization with another cell when the terminal device can establish synchronization with the SSB-Less Scell ​​using the synchronization signal of the other cell. This information may be transmitted as information such as deriveSSB-Indexfromcell or deriveSSB-IndexFromCellInter. Here, deriveSSB-Indexfromcell is used to enable deriving the SSB index of another cell among multiple cells based on the SFN and frame position of a cell (serving cell) that is currently providing communication services to the terminal device among the multiple cells, provided that the Super Frame Numbers (SFNs) and frame boundaries in the time domain are aligned among the multiple cells. Note that deriveSSB-indexfromcell can be used regardless of whether the associated cell is provided by a base station device that is (can be considered to be) located at the same location. For example, the terminal device may identify the SSB index of the first Scell ​​based on synchronization with the second Scell ​​that does not perform power saving operation and that is identified based on received information (information related to the time and frequency domains of the second Scell). For example, the first Scell ​​transmits SSBs with SSB indices 1 to 4 when not performing power saving operation, but stops transmitting SSBs with SSB indices 2 and 3 when performing power saving operation. In this case, the terminal device may identify, for example, based on the SSBs transmitted in the second Scell, that the SSBs whose transmission has been stopped in the first Scell ​​have SSB indices 2 and 3, and may request the network side to transmit on-demand SSBs as necessary.

[0022] In addition, if the terminal device determines, for example, that the SSB indices of the SSBs whose transmission has been stopped in the first Scell ​​are 2 and 3, it can request that all of these SSBs be transmitted as on-demand SSBs, or it may request that only some of them be transmitted.

[0023] For example, it is assumed that a base station device of a first Scell ​​that performs power saving operation and a base station device of a second Scell ​​that does not perform power saving operation are treated as being (almost) co-located. Furthermore, it is assumed that the directions of beams corresponding to SSBs with SSB indices 1 to 4 transmitted when the base station device of the first Scell ​​performs non-power saving operation are (almost) identical to the directions of beams of the second Scell ​​with SSB indices 1 to 4. Here, it is assumed that a terminal device receives communication services via the second Scell. Furthermore, it is assumed that when the base station device of the first Scell ​​performs power saving operation, transmission of SSBs with SSB indices 2 and 3 among the SSBs with SSB indices 1 to 4 is suppressed (stopped). Here, consider a case where the terminal device determines that the signal strength or signal quality in the second Scell ​​has become lower than that in the first Scell. In this case, the terminal device compares the signal strength or signal quality of the SSBs with SSB indices 2 and 3 in the second Scell. The terminal device is then assumed to have determined that the signal strength or signal quality of the SSB with SSB index 2 is better than that of the SSB with SSB index 3. In this case, the terminal device can estimate that the signal strength or signal quality of the SSB with SSB index 2 is also better than that of the SSB with SSB index 3 in the first Scell. The terminal device can then request the network to transmit the SSB with SSB index 2, but not to request the network to transmit the SSB with SSB index 3. In this way, when transmission of some SSBs in the first Scell ​​is stopped and there is a correspondence between the beam of the first Scell ​​and the beam of the second Scell ​​(neighboring cell), the terminal device can request on-demand SSB transmission of only some SSBs, without requesting on-demand SSB transmission for all SSBs whose transmission is stopped in the first Scell. This makes it possible to prevent an increase in power consumption in the SSB-less Scell.

[0024] Furthermore, even when a base station device of a first Scell ​​that performs power saving operation and a base station device of a second Scell ​​that does not perform power saving operation and provides communication services to a terminal device are treated as being located in different positions, the terminal device can request transmission of only some of the SSBs whose transmission is stopped (suppressed) in the first Scell ​​without power saving operation. Assume that the terminal device detects, for example, that a beam failure has occurred in a beam corresponding to SSB index 1 of the first Scell, and further fails to recover from the beam failure in a beam corresponding to SSB index 4 that is preset for recovery from the beam failure. In this case, the terminal device can request transmission of SSBs with SSB indexes 2 to 3 in order to measure other beams in the first Scell. Here, the terminal device identifies SSB indexes 2 and 3 of the first Scell ​​based on information about the second Scell, for example, by referring to derivessb-Indexfromcell. If the terminal device recognizes the direction of the beam corresponding to each SSB index of the first Scell, for example, by pre-setting, it can estimate which beam corresponds to which position the terminal device is located. In one example, if the terminal device determines that it is located in the direction of a beam corresponding to an SSB index of 2, it can request the network to transmit on-demand SSBs for the SSBs with an SSB index of 2. In this way, the terminal device can request on-demand SSB transmission for only some SSBs, without requesting on-demand SSB transmission for all SSBs whose transmission is suppressed. This makes it possible to prevent an increase in power consumption in an SSB-less Scell.

[0025] As described above, for example, each Scell ​​may have multiple configuration patterns for power-saving operation, and the Scell ​​may selectively use the multiple configuration patterns as needed. That is, it is assumed that multiple configuration pattern information is required for one Scell. In this case, identification information for identifying each of the multiple configuration pattern information may be assigned. Configuration pattern information for when SSB transmission is suppressed and SSB configuration pattern information for when SSB transmission is not suppressed may be prepared separately, and identification information for identifying them may be assigned. If there is only one configuration pattern information for when SSB transmission is suppressed, the identification information may be information indicating whether SSB transmission is suppressed. Furthermore, if separate information elements are defined for when SSB transmission is suppressed and when it is not, whether SSB transmission is suppressed is identified by the name of the information element. Therefore, identification information may not be required at least for when SSB transmission is not suppressed. The base station device of the Pcell may simultaneously or separately notify the terminal device of information notifying the configuration pattern information for each Scell ​​and identification information indicating the configuration pattern used in the Scell. Based on the identification information associated with the configuration pattern information, the terminal device may identify one (or more) configuration pattern information from the configuration pattern information for when power saving operation is not being performed and one or more configuration pattern information for power saving operation. Note that if multiple configuration pattern information is identified, SSB transmission using both of the multiple configuration pattern information may be performed in the Scell.

[0026] Note that, for example, only the setting pattern information currently being used in the Scell ​​may be notified to the terminal device. For example, when power saving operation is not being performed in the Scell, SSB setting pattern information for that purpose is notified to the terminal device. Also, when power saving operation is being performed in the Scell, only the setting pattern information being used in that power saving operation may be notified to the terminal device. In this case, identification information for identifying the setting pattern information does not need to be prepared.

[0027] The base station apparatus of the Pcell may notify the terminal apparatus of all of the above-mentioned configuration pattern information using one RRC message (e.g., an RRC Reconfiguration message). The base station apparatus of the Pcell may also notify the terminal apparatus of the above-mentioned configuration pattern information in a distributed manner using multiple RRC messages or messages of other layers. The base station apparatus of the Pcell may then notify the terminal apparatus of identification information specifying the configuration pattern information currently in use in the Scell ​​using MAC CE or downlink control information (DCI). As described above, if only the configuration pattern information currently in use in the Scell ​​is notified and unused configuration pattern information is not notified, only the above-mentioned RRC message may be transmitted, and subsequent MAC CE or DCI may not be transmitted. The identification information specifying the configuration pattern information currently in use may be notified dynamically or semi-persistently using MAC CE or DCI. In one example, if the configuration pattern information currently in use is notified dynamically, the notification may include information indicating the validity period of the configuration pattern information. Then, SSB transmission using the configuration pattern information is performed within the indicated period. The terminal device measures the SSB based on the specified configuration pattern information during the specified period and transmits the measurement results to, for example, the base station device of the Pcell. After the period ends, the base station device of the Pcell may use another DCI to indicate to the terminal device identification information specifying the SSB configuration pattern information used when the other DCI is transmitted, and information indicating its validity period. When the configuration pattern information being used is notified semi-permanently, the notification may include, for example, information instructing the activation or deactivation of specific configuration pattern information. The activated configuration pattern information may be used until information instructing deactivation is notified, or until information instructing the activation of another configuration pattern information is notified.

[0028] Here, an example of the above-described processing will be outlined using FIG. 3. Note that this processing can be modified in various ways as described above or later, but here, a rough processing flow will be described and such modifications will not be mentioned. In this processing, a base station device of a Pcell transmits, for example, configuration information including SSB configuration pattern information in an Scell ​​that provides component carriers of carrier aggregation to a terminal device (S301). Here, the SSB configuration pattern information includes configuration pattern information for when SSB transmission is not suppressed and configuration pattern information for when SSB transmission is suppressed, and identification information can be assigned to each of them. Note that, as described above, identification information does not necessarily have to be assigned. The terminal device retains the received configuration pattern information (S302). Note that, when the terminal device receives configuration information in which the configuration pattern information and identification information are associated with each other, the terminal device stores the identification information and the configuration pattern information in association with each other. Thereafter, the base station device of the Pcell transmits a message including identification information instructing the terminal device to use one of the configuration pattern information transmitted in S301 to measure the SSB transmitted from the base station device of the Scell ​​(S303). The terminal device identifies the configuration pattern information to use based on, for example, the identification information included in the instruction, and performs configuration for measurement (S304). Note that, in S303, information indicating whether SSB transmission is suppressed may be notified. Based on the information, the terminal device may select either configuration pattern information when SSB transmission is suppressed or configuration pattern information when SSB transmission is not suppressed, and perform measurement configuration using the selected configuration pattern information. Thereafter, the terminal device may measure the SSB transmitted from the base station device of the Scell ​​(S305) and transmit a report of the measurement results to the base station device of the Pcell (S306). When the base station device of the Pcell transmits only the configuration pattern information in use in the Scell, the notifications of S301 and S303 can be performed at once, and the processes of S302 and S304 can be performed at once in the terminal device.

[0029] Note that an SSB-Less Scell ​​may be associated with, for example, a combination of multiple pieces of configuration pattern information. That is, for one SSB-Less Scell, a set of configuration information may be defined from configuration pattern information relating to one or more of the configuration pattern information shown in FIG. 2(B) to FIG. 2(E), and multiple pieces of configuration information each consisting of one or more configuration patterns (combinations) may be prepared. Then, the base station apparatus of the Pcell may use, for example, an RRC message to notify the terminal apparatus of the configuration information each consisting of one or more configuration pattern information (combinations) for the SSB-Less Scell, in combination with identification information ("#1" to "#3"), such as {#1: configuration information 1; #2: configuration information 2; #3: configuration information 3}. After notifying the terminal apparatus of this information, the base station apparatus of the Pcell may notify the terminal apparatus of which configuration information is to be activated, such as {Activated: #2}, by using a MAC CE or DCI. For example, when information such as {Activated:#2} is notified as described above, one or more configuration patterns of "configuration information 2" corresponding to the identification information "#2" may be activated. Note that when multiple SSB-Less Scells are configured for a terminal device, the above-mentioned information about the multiple SSB-Less Scells may be notified to the terminal device using one or more RRC messages. For example, a base station device of a Pcell notifies the terminal device of information such as {Scell1:#1: configuration information 1; Scell1:#2: configuration information 2; Scell1:#3: configuration information 3; Scell2:#1: configuration information 1; Scell2:#2: configuration information 2; Scell2:#3: configuration information 3; Scell3:#1: configuration information 1; Scell3:#2: configuration information 2; Scell3:#3: configuration information 3; Scell3:#4: configuration information 4} using an RRC message. Thereafter, the base station device of the Pcell may notify the terminal device of information such as {Activated: Scell1:#2; Scell3:#3} by one or more MAC CEs or DCIs, which may indicate that configuration information 2 of the first Scell ​​(Scell1) and configuration information 3 of the third Scell ​​(Scell3) are activated.

[0030] Also, in an SSB-Less Scell, setting pattern information for transmitting an On demand SSB may be defined. In this case, when the On demand SSB is transmitted, identification information corresponding to the setting pattern information is notified to the terminal device, and the terminal device can perform measurement settings based on the setting pattern information to receive the On demand SSB. This is just an example. For example, when the On demand SSB is transmitted, the terminal device may be notified that the setting pattern information when the suppression of SSB transmission is not performed is used. In this case, since the terminal device can be in a state where it can measure all SSBs, it can also perform measurement of the On demand SSB.

[0031] <Request for transmission of On demand SSB> When a predetermined condition is satisfied, the terminal device may transmit a message to the network (a base station device providing a connected Pcell or Scell) requesting transmission of an on-demand SSB for an SSB whose transmission is suppressed (stopped) in the SSB-Less Scell. For example, the terminal device may transmit the above-mentioned request to the network when a predetermined event occurs, such as when the signal strength or signal quality of the beam of the Scell ​​used for communication becomes lower than that of the beam using the SSB of the SSB-Less Scell, as described above. This event may be, for example, a conventional event such as Event A2 (an event that occurs when the signal strength or signal quality of the serving cell in use falls below a predetermined threshold) or Event A6 (an event that occurs when the signal strength or signal quality of a neighboring cell (here, the SSB-Less Scell) exceeds a value obtained by adding a predetermined offset to the signal strength or signal quality of the serving cell in use). Furthermore, the terminal device may request the network to transmit an on-demand SSB of an SSB-Less Scell, for example, when the magnitude of fluctuation per unit time of the signal strength or signal quality of the Scell ​​used for communication exceeds a predetermined threshold, or when the length of the period during which the magnitude of fluctuation exceeds the predetermined threshold exceeds a predetermined period. For example, when the terminal device is moving at high speed, it is expected that the fluctuation amount per unit time of the signal strength or signal quality will be large. In such a state, it is expected that the terminal device will frequently change the beam to which it is connected, and in order to enable rapid measurement for this, the terminal device may request transmission of an on-demand SSB of an SSB-Less Scell. Note that the terminal device may determine its own movement state using a sensor or the like, rather than the measurement results of fluctuations in signal strength or signal quality, and may request transmission of an on-demand SSB of an SSB-Less Scell ​​when it is moving at high speed. Furthermore, for example, when the terminal device detects beam failure in a beam used for communication, it requests transmission of an on-demand SSB to check whether there is a suitable beam other than the preset beam for recovery from the beam failure.Furthermore, when a terminal device uses the above-mentioned derivessb-Indexfromcell or deriveSSB-IndexFromCellInter to identify the SSB index of an SSB-Less Scell ​​based on a reference signal of a specific cell, in addition to the above-mentioned conditions, the terminal device may request transmission of an on-demand SSB for an SSB whose transmission is suppressed (stopped) in the SSB-Less Scell ​​if, for example, the signal strength or signal quality of the cell from which the reference signal is transmitted is lower than the signal strength or signal quality of the SSB transmitted in the SSB-Less Scell.

[0032] These conditions for requesting transmission of on-demand SSBs may be notified in advance to the terminal device by the base station device of the Pcell. Note that some of these conditions may be stored in the terminal device in advance. In addition to the above conditions, the base station device may also indicate the timing at which the terminal device can start requesting transmission of on-demand SSBs. That is, the base station device may allow on-demand SSB transmission requests only within a specific period. The terminal device may request transmission of on-demand SSBs if at least one of the above conditions is satisfied within that period. Note that the terminal device does not request transmission of on-demand SSBs even if the above conditions are satisfied outside that period. The terminal device may not even need to determine whether the conditions are satisfied outside the notified period. Note that even if the base station device receives a transmission request for on-demand SSBs outside that period, it may ignore the transmission request. Note that the base station device may notify the terminal device of information on the above conditions (for example, using an RRC message) along with information on the SSB configuration pattern. Furthermore, the base station apparatus may use MAC CE or DCI to notify the terminal apparatus of information on a period during which an SSB transmission request can be made (for example, start timing and end timing). The base station apparatus may also prepare a Radio Network Temporary Identifier (RNTI) for each group of terminal apparatuses including one or more terminal apparatuses, and use the RNTI to notify information indicating the above-mentioned conditions and a period during which an SSB transmission request can be made on a group-by-group basis. The base station apparatus may also notify information indicating the above-mentioned conditions and a period during which an SSB transmission request can be made on a cell-by-cell basis to which terminal apparatuses belong. In other words, terminal apparatuses belonging to the same cell may be treated as one group, and information may be notified for each group. This notification may be performed, for example, by DCI.

[0033] A terminal device may transmit an SSB transmission request, including an identifier (Scell ​​index) of an SSB-less Scell ​​to which an on-demand SSB should be transmitted, to a base station device of a Pcell (or an Scell ​​currently being used for communication). This transmission request may include, for example, at least one of information requesting a change in the SSB transmission period, information specifying the SSB to be transmitted, and information specifying the beam direction along which the SSB should be transmitted. The transmission request may also include information indicating the use of the on-demand SSB (e.g., for radio resource management (RRM) measurements, time synchronization / frequency synchronization, etc.). Note that transmission of a specific SSB may be requested using an SSB index or an index indicating SSB configuration pattern information.

[0034] The terminal device may transmit an on-demand SSB transmission request to the base station device of the Pcell using a message of layer 3 (RRC layer). For example, UE assistance information or a measurement report sent periodically or due to an event may be used to request the on-demand SSB transmission. The terminal device may also transmit this request using a message of layer 2 (MAC layer). When a beam failure in the Scell ​​is detected, information requesting the on-demand SSB may be included in a BFR MAC CE transmitted to the base station device of the Pcell for beam failure recovery in the Scell. The terminal device may also request the on-demand SSB transmission using another MAC CE, such as an Enhanced BFR MAC CE, a Buffer Status Report MAC CE, a Power Head Room (PHR) MAC CE, or a Configured Grant Confirmation MAC CE. The terminal device may also transmit this request using a message of layer 1 (PHY layer). For example, a terminal device may request transmission of an on-demand SSB of an Scell ​​using resources allocated by a scheduling request (SR) to a base station device of a Pcell or a configured grant (at least one of type 1 and type 2). In this case, a scheduling request identifier and resources different from those of a conventional scheduling request may be used. Furthermore, uplink resources may be prepared by a dedicated configured grant for requests for on-demand SSBs.

[0035] Furthermore, when Cell DTX / DRX specified in the Rel-18 standard is configured in a Pcell, the base station device of the Pcell cannot receive uplink terminal device-specific data or control information during the inactive period of Cell DRX. That is, the terminal device cannot transmit the above-mentioned messages during the inactive period of Cell DRX (even if it transmits the message, the base station device of the Pcell cannot receive the message). On the other hand, Cell DRX does not apply to SSBs, paging, system information blocks (SIBs), and random access channels (RACHs), and it is specified that these signals are transmitted and received even during the inactive period. For this reason, in one example, the terminal device can request transmission of on-demand SSBs of the Scell ​​using a physical random access channel (PRACH) to the base station device of the Pcell. For example, the terminal device transmits a PRACH to the base station device of the Pcell to transition the Pcell to the active state. Note that the active state here refers to a state in which signals can be transmitted and received, and may be, for example, a state in which Cell DTX / DRX is not used, or a state in which signals are transmitted and received during an inactive period of Cell DTX / DRX. Thereafter, the terminal device may transmit an on-demand SSB transmission request for the Scell ​​to the base station device of the Pcell as described above. The terminal device may also transmit a PRACH to the Pcell using a PRACH resource associated with a pre-configured on-demand SSB transmission request for the Scell. In this case, upon receiving the PRACH transmitted on that resource, the base station device of the Pcell may recognize that a transmission request for the on-demand SSB has been received. When such a resource for PRACH is provided, other communications cannot be performed on that resource, but the Pcell in which Cell DTX / DRX is configured does not need to operate in the active state.

[0036] When a base station device of the Pcell receives a transmission request for an on-demand SSB, it forwards the transmission request to a base station device providing an SSB-Less Scell ​​via, for example, the Xn interface. Then, the base station device of the SSB-Less Scell ​​can transmit the on-demand SSB in accordance with the transmission request.

[0037] In the above example, an example has been described in which a terminal device requests transmission of an on-demand SSB, but this is not limiting. For example, when a Pcell instructs a terminal device to enable an Scell ​​that is an SSB-Less Scell, information on the signal strength or signal quality of the terminal device of that Scell, or time / frequency synchronization with that Scell ​​in the terminal device may be required. In such a case, even if the base station device of the Pcell does not receive a request from the terminal device, it may request transmission of an on-demand SSB from the base station device of the SSB-Less Scell. Before transmitting a MAC CE for enabling or disabling an Scell ​​that is an SSB-Less Scell, the base station device of the Pcell may notify the terminal device, by MAC CE or DCI, of the identification information of the (one or more) SSB-Less Scells from which the On-demand SSBs are transmitted, the transmission start timing of the On-demand SSBs transmitted from the SSB-Less Scell ​​(e.g., an offset from the transmission timing of this MAC CE or DCI), the transmission end timing of the On-demand SSBs (the timing after which the On-demand SSBs will no longer be transmitted), and configuration pattern information of the On-demand SSBs (e.g., the SSB index of the SSBs to be transmitted). In addition to the above-described transmission start timing and transmission end timing of the On-demand SSBs, for example, the terminal device may be notified that the On-demand SSBs transmitted from the SSB-Less Scell ​​are transmitted periodically from the configured transmission timing. Even if such a notification is not received, the terminal device may assume that the On-demand SSBs are transmitted at a predetermined interval, for example, between the transmission start timing and the transmission end timing. That is, when a terminal device receives information specifying a transmission start timing, it can measure the on-demand SSB, assuming that the on-demand SSB will be transmitted periodically from that transmission start timing.In this case, if the transmission end timing is not notified in advance, the terminal device may assume that the on-demand SSB is transmitted periodically until it receives a notification, for example from a base station device of the Pcell, that the transmission of the on-demand SSB will be stopped.

[0038] The base station device of the Pcell may notify the terminal device in advance of this information as one of the configuration pattern information described above in <Notification of Configuration Pattern Information>, and then specify the configuration pattern information in MAC CE or DCI when On-demand SSB transmission is actually performed. The base station device of the Pcell may also notify the terminal device of information other than the above-mentioned configuration pattern information, such as the resources on which On-demand SSBs are transmitted, their transmission cycle, and transmission start timing. After receiving the above-mentioned information, the terminal device starts measuring On-demand SSBs based on the specified information and reports the measurement results to the base station device of the Pcell. After receiving the measurement results from the terminal device, the base station device of the Pcell determines whether continued On-demand SSB transmission in the SSB-Less Scell ​​is no longer necessary. If the base station device of the Pcell determines that continued On-demand SSB transmission is no longer necessary, it may request the SSB-Less Scell ​​to stop transmitting On-demand SSBs and notify the terminal device that On-demand SSB transmission in the SSB-Less Scell ​​will be stopped.

[0039] In another example, the base station apparatus of the Pcell may notify the terminal apparatus of the number of transmissions of an On-demand SSB in an SSB-Less Scell ​​instead of the timing of the end of transmission of the On-demand SSB in the SSB-Less Scell. This transmission count is the number of times the On-demand SSB is transmitted in the SSB-Less Scell, and after the On-demand SSB has been transmitted that number of times (for example, at a predetermined period notified to the terminal apparatus), the transmission of the On-demand SSB is stopped. Note that the base station apparatus of the Pcell may notify the terminal apparatus that the transmission of the On-demand SSB in the SSB-Less Scell ​​will be stopped when the number of transmissions of the On-demand SSB in the SSB-Less Scell ​​reaches that number of transmissions. Furthermore, when the terminal receives information including the above-mentioned number of transmissions, it may start measuring the On-demand SSB from the start timing of transmission of the On-demand SSB, count the number of measurements of the On-demand SSB, and stop measuring the On-demand SSB (without receiving a notification from the base station apparatus of the Pcell) when the number of measurements reaches the notified number of transmissions.

[0040] Furthermore, the SSB transmission period may be changed in response to an on-demand SSB request, such as by switching between the setting pattern of FIG. 2(A) and the setting pattern of FIG. 2(B). That is, for example, when an SSB-less Scell ​​suppresses SSB transmission by lengthening the SSB transmission period as shown in FIG. 2(B), the transmission period may be shortened for a certain period as shown in FIG. 2(A) in response to an on-demand SSB transmission request. In this case, the base station device of the Pcell may notify the terminal device that the SSB in the SSB-less Scell ​​will be transmitted at a first period for a predetermined period, and after the period ends, will be transmitted at a second period different from the first period (for example, shorter than the first period). The base station device of the Pcell may notify the terminal device of the transmission start timing and transmission end timing as information specifying the period during which SSB transmission is performed at the first period, or may notify the terminal device of other information such as the transmission start timing and the number of on-demand SSB transmissions. The Pcell base station device may notify the terminal device of information about the SSB transmission period changed in response to an on-demand SSB request. If the SSB transmission period requested by the on-demand SSB is the same as the SSB transmission period for another beam in which SSB transmission is not suppressed, for example, the information about the transmission period need not be notified to the terminal device. The Pcell base station device may also notify the terminal device of information about resources used for transmitting the SSB during the period in which the SSB is transmitted at a first period. Upon receiving this information, the terminal device may perform SSB measurement at a period corresponding to the SSB transmission period for a specified period from the transmission start timing, and change the SSB measurement period when the period ends and the SSB transmission period is switched. The Pcell base station device may also transmit a predetermined notification to the terminal device when it starts transmitting SSBs at a short period in response to an on-demand SSB request, and then transmit another predetermined notification to the terminal device when it starts transmitting SSBs at a long period after the short period SSB transmission ends. In other words, the terminal device does not need to be able to specify the above-mentioned period in advance.

[0041] The base station device of the above-mentioned Pcell may transmit multiple settings related to transmission of on-demand SSBs for each of multiple SSB-Less Scells to the terminal device in one message or in multiple messages. In one example, of three settings related to three SSB-Less Scells, two settings may be transmitted in one message and the remaining setting may be transmitted in another message.

[0042] All or part of the above-mentioned information regarding the transmission of on-demand SSB, or information such as a cell identifier related to the SSB-Less Scell, can be notified to the terminal device using at least one of an RRC message, a MAC CE, and a DCI. Note that the above-mentioned information may be included in a MAC CE instructing the activation or deactivation of the SSB-Less Scell, for example. In addition to this notification, the Pcell may also instruct the terminal device to transmit an event-triggered report, periodic, aperiodic, or semi-persistent report of the on-demand SSB measurement results. Note that this information may be notified for each cell to which the terminal device belongs or for each pre-configured group of terminal devices.

[0043] The terminal device receives an instruction from the base station device of the Pcell, and measures the on-demand SSB of the Scell ​​in accordance with the instruction or from a specified transmission start timing according to a specified configuration pattern, and reports the measurement results to the Pcell. When the base station device of the Pcell receives a report of the measurement results of the on-demand SSB of the Scell ​​from the terminal device, the base station device of the Pcell determines, for example, whether to enable the Scell. If the base station device of the Pcell determines not to enable the Scell, it can notify the Scell ​​that SSB transmission should be suppressed or that SSB transmission may be suppressed. Furthermore, if SSB transmission is suppressed in the Scell, the base station device of the Pcell can notify the terminal device of information regarding the suppression of transmission of the Scell ​​(for example, specification of configuration pattern information, etc.).

[0044] In one example, when a terminal device transmits a transmission request for an on-demand SSB of an Scell ​​to a base station device of a Pcell and the base station device of the Pcell receives the transmission request, the base station device of the Pcell transmits a response message to the terminal device. A conventional message for enabling or disabling an Scell ​​may be used for this response message, or the message may be extended. For example, the terminal device may determine that the request for on-demand SSB transmission has been successful when it receives, from the base station device of the Pcell, a message for enabling the SSB-less Scell ​​that requested the transmission of on-demand SSBs. Furthermore, the terminal device may determine that the request for on-demand SSB transmission has been successful when it receives, from the base station device of the Pcell, a message for disabling the currently enabled Scell ​​within a predetermined period after the request for on-demand SSB transmission. Furthermore, an extended message of the message for enabling / disabling the Scell ​​may include information indicating that the request for on-demand SSB transmission has been accepted. Furthermore, a separate RRC message, MAC CE, or DCI may be used for the response message. In response to receiving the response message, the terminal device may determine that the transmission of the Scell's on-demand SSB transmitted to the Pcell's base station device has been successful, and may not subsequently transmit an SSB transmission request again. This prevents the transmission request from being repeatedly transmitted. The terminal device may perform measurement of the on-demand SSB based on, for example, the Scell's SSB transmission settings notified in advance. If the terminal device does not receive a response message from the base station device, it may repeatedly transmit an on-demand SSB transmission request to the Pcell's base station device. The Pcell's base station device may notify the terminal device of information setting an upper limit on the number of repeated transmissions of the transmission request. If the number of repeated transmissions of the transmission request reaches the upper limit without receiving a response message, the terminal device may stop transmitting the transmission request.

[0045] Furthermore, to prevent on-demand SSB transmission requests for the same Scell ​​from arriving in parallel from multiple terminal devices, the base station device of the Pcell may notify multiple terminal devices simultaneously, on a cell-by-cell or terminal device group-by-terminal device basis, that on-demand SSBs will be transmitted in that Scell. For example, the base station device of the Pcell may set a specific RNTI corresponding to the on-demand SSB request and notify multiple terminal devices of the RNTI in advance. The base station device of the Pcell then transmits a DCI containing an SSB index for the on-demand SSB to be transmitted. The multiple terminal devices that have been notified of the above-mentioned RNTI can identify the SSB index of the on-demand SSB to be transmitted by demodulating the DCI using the RNTI. The multiple terminal devices then do not request transmission of on-demand SSBs with the identified SSB index. This prevents the multiple terminal devices from transmitting on-demand SSB transmission requests in parallel. Note that if the terminal device receives this information while processing for transmitting a transmission request is in progress but not yet completed, it may interrupt (terminate) the processing it is currently performing.

[0046] FIG. 4 shows an example of a processing flow related to a transmission request for an on-demand SSB. While this processing can be modified in various ways, as described above or below, a rough processing flow will be described here, and such modifications will not be mentioned. In this processing, the base station device of the Pcell transmits a transmission request for an on-demand SSB to the base station device of the Scell ​​(S403). When the base station device of the Pcell receives a transmission request for an on-demand SSB from a terminal device (S401), the base station device of the Pcell may transmit this transmission request to the base station device of the Scell. When the base station device of the Pcell receives a transmission request for an on-demand SSB from a terminal device, the base station device of the Pcell may transmit a response message to the terminal device (S402) to prevent the terminal device from repeatedly transmitting transmission requests for an on-demand SSB. The base station device of the Pcell may also transmit a notification to the terminal device, including setting information for receiving the on-demand SSB transmitted from the base station device of the Scell ​​(S404). This notification may be included in the response message of S402. In response to the notification, the terminal device performs configuration for measurement (S405). Then, the terminal device measures the SSB transmitted from the base station device of the Scell ​​(S406) and can transmit a report of the measurement results to the base station device of the Pcell (S407). After the terminal device has completed measurement of the on-demand SSB, the base station device of the Pcell can notify the base station device of the Scell ​​that transmission of the SSB should or may be suppressed (S408).

[0047] Note that the base station apparatus of the Pcell may reject an on-demand SSB transmission request received from a terminal apparatus when there is another Scell ​​that is not suppressing SSB transmission and the signal strength or signal quality of that Scell ​​in the terminal apparatus is equal to or greater than a predetermined threshold. Note that if the Scell ​​is not enabled for the terminal apparatus, the base station apparatus of the Pcell may transmit a MAC CE to the terminal apparatus to enable the Scell. The base station apparatus of the Pcell may then notify the terminal apparatus in the MAC CE that the on-demand SSB transmission request has been rejected. Also, if the Scell ​​is not configured for the terminal apparatus (not added as an Scell ​​for the terminal apparatus), the base station apparatus of the Pcell may notify the terminal apparatus of the additional configuration of the Scell ​​using an RRC message (e.g., an RRC Reconfiguration message) and notify the terminal apparatus in the message that the on-demand SSB transmission request has been rejected.

[0048] When a terminal device transmits a request for transmission of an on-demand SSB of an Scell, transmission of which is suppressed, to a base station device of a Pcell using a PRACH (random access preamble), the terminal device may determine that the transmission request has been accepted in response to receiving a random access response from the base station device of the Pcell. Note that, for example, if the terminal device does not receive a random access response within a period (ra-ResponseWindow) in which a random access response should be received, the terminal device repeatedly transmits the random access preamble. Note that if the terminal device does not receive a random access response even after repeatedly transmitting the random access preamble up to the upper limit value (upper limit value of PREAMBLE_TRANSMISSION_COUNTER), the terminal device stops the transmission request of the on-demand SSB. If the transmission request of the on-demand SSB fails, the terminal device may transmit a notification of the failure to the base station device of the Pcell. Upon receiving the notification from the terminal device, the base station device of the Pcell may instruct the terminal device to add or activate another Scell.

[0049] <Measurement of SSB with suppressed transmission> For measurements of an Scell ​​(serving cell) currently used for communication, the MeasObject associated with the ServingCellMO information element includes ssb-configmobility, and the rstype set in reportconfig is SSB. In this case, the measurement pattern of the ssb-configmobility of the measObject associated with the SSB configuration pattern information of the Scell ​​can be configured and notified to the terminal device. Furthermore, if the SSB configuration pattern information of the Scell ​​is changed, the measurement pattern of the ssb-configmobility of the measObject can also be changed. That is, the measurement pattern can be configured so that SSBs whose transmission is stopped due to transmission suppression are not measured. An instruction to change the measurement pattern can be notified to the terminal device using the same message as the SSB configuration pattern or a message separate from the SSB configuration pattern. In one example, the change in measurement-related parameters can be notified to the terminal device using any of an RRC message, a MAC CE, and a DCI. That is, when ssbconfigmobility is included in the measobject for measurements of an Scell ​​(neighboring cell), the base station device of the Pcell can configure an SSB measurement pattern in a format associated with the SSB configuration pattern in the Scell ​​and notify the terminal device of the measurement pattern information. Note that when the SSB configuration pattern in the Scell ​​is changed, the base station device of the Pcell can change the SSB measurement pattern according to the changed configuration pattern and notify the terminal device of the change.

[0050] In one example, a base station device of a Pcell may generate configuration information (measconfig) including parameters related to measurements for each Scell ​​in accordance with SSB configuration pattern information for that Scell, and notify the terminal device of the generated configuration information. For example, assume that before SSB transmission is suppressed, the SMTC window is set to 2 ms and the measurement gap length (MGL) is set to 4 ms. This state is shown in FIG. 5. In FIG. 5, SSB#0 to SSB#3 correspond to SSBs with SSB indexes 0 to 3, respectively, and this notation may be used hereinafter. In FIG. 5, the SMTC window is set to include the transmission timings of SSBs SSB#0 to SSB#3. Note that actual measurements are performed during a period that includes the SMTC window (a 3 ms interval in FIG. 5). Furthermore, periods when no transmission or reception is performed are provided before and after the period when actual measurements are performed, and the MGL is set to the length of this period. Here, when transmission of some SSBs is stopped and measurement is not necessary, the measurement period can be shortened, that is, the length of the SMTC window and the MGL can be shortened. For example, when transmission of SSB#3 is stopped, the SMTC window may be set to 2 ms and the MGL to 4 ms or 3.5 ms. A setting such as SMTC window = 1.5 ms may also be used. When transmission of SSB#2 and SSB#3 is stopped, the SMTC window may be set to 1 ms and the MGL to 3 ms, and when transmission of SSB#1 to SSB#3 is stopped, the SMTC window may be set to 1 ms or 0.5 ms and the MGL to 3 ms or 2.5 ms. Information indicating this setting may be notified from the base station apparatus of the Pcell to the terminal apparatus. Also, for example, the cycle in which the above-mentioned SMTC window is set (measurement gap repetition period (MGRP)) may be changed. For example, when the setting pattern shown in FIG. 2(B) is used, even if the MGRP is set to 20 ms, there may be many SMTC windows in which no measurement is performed.Therefore, settings such as MGRP = 160 ms or 320 ms can be made. In addition, a plurality of measurement parameters (or combinations thereof) such as the SMTC window, MGL, and MGRP as described above can be prepared in advance, and individual indexes can be assigned to each of the plurality of measurement parameters and notified to the terminal device so that the measurement parameters actually used can be specified by the index.

[0051] In addition, the base station device of the Pcell can notify the terminal device of the report setting (reportconfig) of the measurement result as in the conventional case. Generally, the measurement result is reported in two modes: periodic report and event trigger report according to the occurrence of an event. When the event trigger report is used, the terminal device reports the measurement result to the base station device when it determines that a pre-defined event has occurred. In addition, the terminal device may execute a specific pre-set process when it determines that an event has occurred. On the other hand, when the periodic report is used, the SSB may not be transmitted in the SSB-Less Scell, and it may be impossible to obtain the measurement result. In such a case, the terminal device may stop or interrupt the transmission of the periodic report. In addition, the terminal device may transmit only other measurement reports excluding the report on the SSB that has not been transmitted to the base station device. In addition, the terminal device may report to the base station device that the SSB has not been detected in the measurement report on the SSB that has not been transmitted in the SSB-Less Scell.

[0052] <Suppression of SSB Transmission in SSB-Less Scell> A base station device of an SSB-Less Scell ​​may receive an on-demand SSB transmission request directly from a terminal device. In this case, the base station device of the SSB-Less Scell ​​transmits the SSB with the requested SSB index, and if other SSB transmissions are being suppressed, may continue the suppression of those transmissions. When a base station device of an SSB-Less Scell ​​receives an on-demand SSB transmission request without specifying an SSB index, it may end the suppression of all SSB transmissions and resume normal operation. However, this is just one example, and a base station device of an SSB-Less Scell ​​may end the suppression of all SSB transmissions and resume normal operation in response to receiving an on-demand SSB transmission request for any SSB. Furthermore, a base station device of an SSB-Less Scell ​​may end the suppression of SSB transmissions and resume normal operation when it receives a predetermined request (e.g., an on-demand SSB transmission request for a specific SSB or a cell-wide activation request) from a base station device of a Pcell. When a base station device of an SSB-Less Scell ​​receives a predetermined request for an SSB with a specific SSB index, it may transmit that SSB without suppressing it, and continue suppressing transmission of other SSBs, or it may cancel the suppression of transmission of all SSBs. The base station device of an SSB-Less Scell ​​may transmit a response message to the device that transmitted the request message, such as a request for transmitting an on-demand SSB. For example, when a base station device of an SSB-Less Scell ​​receives a request for transmitting an on-demand SSB from a terminal device, it may transmit a predetermined response message to the terminal device to prevent the transmission request from being repeatedly transmitted. When a base station device of an SSB-Less Scell ​​receives the above-mentioned predetermined request from a base station device of a Pcell, it may return a response message to the base station device of the Pcell. The timing of transmitting the response message may be after or before the start of transmission of the on-demand SSB.

[0053] A base station device of each cell may start suppressing transmission of some or all SSBs in that cell based on the traffic volume of the cell served by the base station device itself and location information that can identify where terminal devices are concentrated within the cell. Furthermore, when a base station device starts transmitting a CSI-RS directed to a specific direction, the base station device may suppress transmission of SSBs in the direction in which the CSI-RS is being transmitted (SSBs for which a predetermined QCL Type is set between the transmitted CSI-RS and the transmitted CSI-RS). Furthermore, when an Scell ​​that was enabled for a terminal device is disabled, the base station device of a Pcell may determine whether transmission of some or all SSBs in that Scell ​​should be suppressed. For example, when there are no terminal devices that have enabled a specific Scell, the base station device of a Pcell may determine that suppression of transmission of at least some SSBs in that Scell ​​should be started. Furthermore, when there are no terminal devices using a specific beam of a specific Scell, the base station device of a Pcell may determine that transmission of SSBs corresponding to that specific beam should be suppressed. Furthermore, when a base station device of a Pcell receives a report of measurement results of the signal strength or signal quality of an Scell ​​from a terminal device, the base station device of the Pcell may determine whether or not to suppress transmission of SSBs in the Scell ​​based on the measurement results. For example, when the signal strength or signal quality of a specific Scell ​​satisfies the conditions of Event A2 or Event A6 as described above, the base station device of the Pcell may not delete the Scell, but may determine whether or not to suppress transmission of at least some SSBs in the Scell ​​based on whether the Scell ​​is being used by other terminal devices and / or whether it is expected to be used.

[0054] As described above, a terminal device can request on-demand SSB transmission from a base station device of an SSB-less Scell ​​in which SSB transmission is suppressed, and can establish time / frequency synchronization or measure radio quality based on the SSB transmitted in response to the request. Here, when the terminal device requests on-demand SSB transmission to establish synchronization, after establishing synchronization in response to the request, the terminal device can report to, for example, the base station device of the Pcell that synchronization has been established or that no further SSB transmission is necessary. This report can be transmitted, for example, using a message such as UE assistant information. Upon receiving the report, the base station device of the Pcell can instruct the base station device of the Scell ​​to resume suppression of SSB transmission. Alternatively, the above-described report can be transmitted directly to the base station device of the Scell, and the base station device of the Scell ​​can resume suppression of SSB transmission in response to receiving the report. Furthermore, in a state where a configuration pattern is used in which only SSBs are transmitted for some beams and SSB transmission for other beams is stopped, as shown in, for example, FIG. 2(D) or 2(E), if a terminal device requests on-demand SSB transmission for a beam for which SSB transmission is stopped, SSB transmission for the beam for which SSB transmission is currently being transmitted may be stopped. That is, the beam for which SSB transmission is stopped may be reselected. In one example, when a base station device of a Pcell receives an on-demand SSB transmission request for a beam for which SSB transmission is stopped, the base station device of an SSB-less Scell ​​that forms that beam may transmit a message recommending suppression of SSB transmission for the beam for which SSB transmission is currently being transmitted. When the base station device of the SSB-less Scell ​​receives the message, it may determine whether to suppress SSB transmission for the beam for which SSB transmission is currently being transmitted.

[0055] Note that the base station device can use Cell DTX / DRX to set periods during which transmission and reception are suspended. Here, in Cell DTX of Rel-18, signals are not transmitted during inactive periods. However, the non-transmission targets are limited to UE-specific channels / signaling, and SSB transmission is still performed. In contrast, for example, in an SSB-Less Scell, SSB transmission may be suppressed by suspending SSB transmission during inactive periods and transmitting SSBs during active periods. Furthermore, partial SSB transmission may be suppressed regardless of inactive and active periods. For example, FIG. 6(A) shows the relationship between the active and inactive periods of Cell DTX and the timing of SSB transmission, as defined in Rel-18. The periods during which SSBs are transmitted are indicated by hatched rectangles. As shown in FIG. 6(A), according to the Rel-18 definition, SSBs are transmitted periodically, regardless of the active and inactive periods of conventional Cell DTX. FIG. 6(B) shows an example of a case where SSB transmission is suppressed regardless of the active / inactive period of Cell DTX. In this example, SSBs are transmitted even during the inactive period of Cell DTX, but the frequency of SSB transmission is suppressed. FIG. 6(C) shows an example of a case where SSB transmission is suppressed in conjunction with the active / inactive period of Cell DTX. In this example, SSBs are transmitted during the active period of Cell DTX, and SSB transmission is stopped during the inactive period. This makes it possible to further reduce power consumption during the inactive period. Also, as shown in FIG. 6(D), FIGS. 6(B) and 6(C) may be combined. That is, the SSBs whose transmission frequency is suppressed in FIG. 6(B) may also be prevented from being transmitted during the inactive period. Also, Cell DTX / DRX may be configured so that an inactive period is set during the period when SSB transmission is stopped, and an active period is set during the period when SSB transmission is transmitted.

[0056] <Notification Regarding SSB Transmission Suppression> The base station device of the Pcell or SSB-Less Scell does not have to notify the terminal device that the transmission of the SSB is suppressed. That is, the transmission of the SSB may be suppressed without notifying the terminal device. Also, the base station device of the Pcell may notify, for example, using a MAC CE that instructs deactivation of the Scell, that the transmission of the SSB is suppressed in that Scell. Further, the base station device of the Pcell may notify the terminal device that the transmission of at least a part of the SSB is suppressed in a specific Scell, using DCI. In one example, the base station device of the Pcell may notify, using DCI, terminal devices belonging to each of a plurality of cells that the transmission of at least a part of the SSB is suppressed in a specific Scell on a per-cell basis. Also, terminal devices are grouped using a predetermined rule, an RNTI is assigned to each group, and the terminal devices belonging to that group may be notified that the transmission of the SSB is suppressed in a specific Scell by DCI scrambled using that RNTI.

[0057] FIG. 7 shows an example of the hardware configuration of a base station apparatus and a terminal apparatus according to this embodiment. In one example, the base station apparatus and the terminal apparatus include a processor 701, a ROM 702, a RAM 703, a storage device 704, and a communication circuit 705. The processor 701 is a computer including 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 control process of the apparatus and the above-mentioned processes by reading and executing programs stored in the ROM 702 or the storage device 704. The ROM 702 is a read-only memory that stores information such as programs and various parameters related to the processes executed by the base station apparatus and the terminal apparatus. The RAM 703 functions as a workspace when the processor 701 executes the programs and is a random access memory that stores temporary information. The storage device 704 is, for example, a removable external storage device. The communication circuit 705 is, for example, a circuit for wireless communication of 5G or its successor standards. Although FIG. 7 illustrates one communication circuit 705, 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 its successor standard, and a common antenna for these circuits. The base station apparatus and the terminal apparatus may 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 705 for each of multiple available frequency bands, or may have a common communication circuit 705 for at least some of these frequency bands.

[0058] FIG. 8 shows an example of the functional configuration of a terminal device. The terminal device includes, for example, a setting information receiving unit 801, a measurement setting unit 802, a measurement unit 803, an on-demand SSB request unit 804, and a reporting unit 805. Note that FIG. 8 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 and subsequent standards generally have. The terminal device may also have functions for executing the various modified examples described above. The functional blocks in FIG. 8 are shown schematically, and the respective functional blocks may be realized as an integrated unit or may be further subdivided. Each function in FIG. 8 may be realized, for example, by the processor 701 executing a program stored in the ROM 702 or the storage device 704, or by a processor within the communication circuit 705 executing predetermined software. Since the details of the processing performed by each functional unit are as described above, only the general functions of the terminal device will be outlined here.

[0059] The configuration information receiver 801 receives various configuration information as described above, for example, from the base station device of the Pcell (or, in some cases, from the base station device of the Scell). The configuration information includes, for example, information enabling measurement configuration, such as configuration pattern information in the SSB-Less Scell, and information such as the period during which on-demand SSB can be requested. Details are as described above, and will not be repeated here. The measurement configuration unit 802 holds the configuration information received by the configuration information receiver 801 and performs SSB measurement configuration, for example, based on identification information for specifying subsequently received configuration pattern information. The measurement unit 803 performs SSB measurement using the measurement configuration by the measurement configuration unit 802. The on-demand SSB request unit 804 transmits a request for transmission of SSBs whose transmission is suppressed (stopped) in the SSB-Less Scell ​​to the base station device of the Pcell. The reporting unit 805 notifies the base station device of the Pcell of the results of the measurement by the measurement unit 803.

[0060] FIG. 9 shows an example of the functional configuration of a Pcell base station device. The Pcell base station device includes, for example, a setting information notification unit 901, a report reception unit 902, and an on-demand SSB request unit 903. Note that FIG. 9 only shows functions particularly related to this embodiment, and omits other functions that the Pcell base station device may have. For example, the Pcell base station device naturally has other functions that base station devices compliant with 5G and subsequent standards generally have. The base station device may also have functions for executing the various modifications described above. The functional blocks in FIG. 9 are shown schematically, and the functional blocks may be integrated or further subdivided. Each function in FIG. 9 may be realized, for example, by the processor 701 executing a program stored in the ROM 702 or the storage device 704, or by a processor within the communication circuit 705 executing predetermined software. Since the details of the processing performed by each functional unit are as described above, only the general functions of the base station device will be outlined here.

[0061] The setting information notification unit 901 transmits, for example, the various setting information described above to a connected terminal device. The report receiving unit 902 receives reports of measurement results such as SSB signal strength or signal quality measured by the terminal device based on the setting information notified by the setting information notification unit 901. The on-demand SSB request unit 903 requests the SSB-less Scell ​​to transmit an SSB whose transmission is suppressed (stopped).

[0062] Although the above description has been given of the process related to transmission of on-demand SSB in an Scell ​​in carrier aggregation, similar processes can also be executed when, for example, dual connectivity is used.

[0063] As described above, this embodiment makes it possible to appropriately utilize on-demand SSB in the Scell ​​of carrier aggregation, 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."

[0064] 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 terminal device conforming to a cellular communication standard of the Third Generation Partnership Project (3GPP), a receiving means for receiving, from a base station device that provides a primary cell of carrier aggregation, second setting information for when at least a part of a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) is not transmitted, which differs from first setting information for when transmission of the SSB in a secondary cell is not suppressed; a setting means for performing measurement configuration of the SSB in the secondary cell based on the second setting information; A measurement means for measuring the SSB transmitted in the secondary cell using the measurement configuration; A terminal device comprising:

2. the first setting information and the second setting information are each assigned with corresponding identification information, the receiving means further receives, after receiving the first setting information and the second setting information, one of identification information of the first setting information and identification information of the second setting information from the base station device; the setting means, when receiving identification information of the first setting information, performs the measurement setting based on the first setting information, and when receiving identification information of the second setting information, performs the measurement setting based on the second setting information; 2. The terminal device according to claim 1, wherein:

3. There are a plurality of the second setting information for a plurality of patterns of transmission of the SSB in the secondary cell when at least a part of the SSB is not transmitted, and identification information is assigned to each of the plurality of the second setting information; the receiving means, after receiving the plurality of pieces of second setting information and the identification information of each of the plurality of pieces of second setting information, further receives identification information of any of the plurality of pieces of second setting information; the setting means performs the measurement setting corresponding to the pattern of the second setting information identified by the identification information.

2. The terminal device according to claim 1, wherein:

4. 4. The terminal device according to claim 2, wherein the receiving means receives a plurality of pieces of configuration information including the first configuration information and the second configuration information via a Radio Resource Control (RRC) message, and receives the identification information via a Medium Access Control (MAC) control element (MAC CE) or Downlink Control Information (DCI).

5. a transmitting unit configured to transmit to the base station device a request for transmission of at least a portion of the SSB that is not being transmitted in the secondary cell; the receiving means receives, from the base station device, configuration information for measuring the SSB transmitted in the secondary cell in response to the request; The setting means performs measurement setting using the setting information.

2. The terminal device according to claim 1, wherein:

6. The receiving means further receives, from the base station device, information indicating a period during which the request can be transmitted; 6. The terminal device according to claim 5, wherein said transmission means transmits said request to said base station device during said period.

7. The receiving means further receives a response message to the request from the base station device, 7. The terminal device according to claim 6, wherein said transmitting means repeatedly transmits said request to said base station device if said response message is not received.

8. A base station device conforming to a cellular communication standard of the Third Generation Partnership Project (3GPP), providing means for providing a primary cell of carrier aggregation to a connected terminal device; A transmitting means for transmitting to the terminal device second setting information when at least a part of a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) is not transmitted, the second setting information being different from first setting information when transmission of the SSB in the secondary cell of the carrier aggregation is not suppressed; A base station device comprising:

9. the first setting information and the second setting information are each assigned with corresponding identification information, the transmitting means, after transmitting the first setting information and the second setting information, further transmits to the terminal device identification information corresponding to the setting information being used out of the first setting information and the second setting information.

9. The base station apparatus according to claim 8,

10. There are a plurality of the second setting information for a plurality of patterns of transmission of the SSB in the secondary cell when at least a part of the SSB is not transmitted, and identification information is assigned to each of the plurality of the second setting information; the transmitting means, after transmitting the plurality of pieces of second setting information, further transmits to the terminal device identification information corresponding to the setting information being used among the plurality of pieces of second setting information; 9. The base station apparatus according to claim 8,

11. 11. The base station device according to claim 9, wherein the transmitting means transmits a plurality of pieces of configuration information including the first configuration information and the second configuration information via a Radio Resource Control (RRC) message, and transmits the identification information via a Medium Access Control (MAC) control element (CE) or Downlink Control Information (DCI).

12. Further comprising a receiving means for receiving from the terminal device a request for transmission of at least a part of the SSB that is not being transmitted in the secondary cell; The transmitting means transmits, to the terminal device, configuration information for measuring the SSB transmitted in the secondary cell in response to the request.

9. The base station apparatus according to claim 8,

13. 13. The base station apparatus according to claim 12, wherein said transmission means further transmits, to said terminal apparatus, information indicating a period during which said request can be transmitted.

14. 14. The base station apparatus according to claim 13, wherein said transmission means further transmits a response message to said terminal apparatus in response to said request.

15. 1. A control method executed by a terminal device conforming to a cellular communication standard of a Third Generation Partnership Project (3GPP), comprising: receiving, from a base station device that provides a primary cell of carrier aggregation, second setting information for when at least a part of a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) is not transmitted, which differs from first setting information for when transmission of the SSB in the secondary cell is not suppressed; performing measurement configuration of the SSB in the secondary cell based on the second configuration information; measuring the SSB transmitted in the secondary cell using the measurement configuration; A control method comprising:

16. A control method executed by a base station device conforming to a cellular communication standard of a Third Generation Partnership Project (3GPP), comprising: Providing a primary cell for carrier aggregation to a connected terminal device; Transmitting to the terminal device second setting information for a case where at least a portion of a synchronization signal (SS) / physical broadcast channel (PBCH) block (SSB) is not transmitted, which is different from first setting information for a case where transmission of the SSB in the secondary cell of the carrier aggregation is not suppressed; A control method comprising:

17. A program for causing a computer provided in a terminal device to execute the control method according to claim 15.

18. A program for causing a computer provided in a base station device to execute the control method according to claim 16.

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