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

Abstract

A terminal device conforming to a third generation partnership project (3GPP) cellular communication standard receives second configuration information, for when 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 when 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.

Description

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

[0001] The present invention relates to a technique for applying On-demand SSB to a cellular communication system.

[0002] The Third Generation Partnership Project (3GPP) is discussing the reduction of network power consumption as an important issue. In this discussion, 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, is being considered.

[0003] 3GPP (registered trademark) Contribution RP-234065

[0004] Non-Patent Document 1 points out that a method for supporting on-demand SSB operation in an Scell ​​in an environment where there are terminal devices in a connected state that perform communication using carrier aggregation should be considered.

[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 aspect of the present invention is a terminal device that complies with the cellular communication standard of the Third Generation Partnership Project (3GPP), and has: a receiving means for receiving, from a base station device that provides a primary cell for 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 aspect 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.

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

[0009] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0010] The accompanying drawings are incorporated in and constitute a part of the specification, illustrate embodiments of the present invention, and together with the description, are used to explain the principles of the present invention. FIG. 1 is a diagram showing an example of the configuration of a wireless communication system. FIG. 2A is a diagram showing an example of an SSB transmission pattern. FIG. 2B is a diagram showing an example of an SSB transmission pattern. FIG. 2C is a diagram showing an example of an SSB transmission pattern. FIG. 2D is a diagram showing an example of an SSB transmission pattern. FIG. 2E is a diagram showing an example of an SSB transmission pattern. FIG. 3 is a diagram showing an example of a process flow executed in a wireless communication system. FIG. 4 is a diagram showing an example of a process flow executed in a wireless communication system. FIG. 5 is a diagram for explaining settings for SSB measurement. FIG. 6A is a diagram showing the relationship between Cell-DTX / DRX and SSB transmission. FIG. 6B is a diagram showing the relationship between Cell-DTX / DRX and SSB transmission. FIG. 6C is a diagram showing the relationship between Cell-DTX / DRX and SSB transmission. Fig. 6D is a diagram explaining the relationship between Cell-DTX / DRX and SSB transmission. Fig. 7 is a diagram showing an example of the hardware configuration of a base station device and a terminal device. Fig. 8 is a diagram showing an example of the functional configuration of a terminal device. Fig. 9 is a diagram showing an example of the functional configuration of a Pcell base station device.

[0011] 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.

[0012] FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. This wireless communication system is a cellular communication system that complies with a cellular communication standard, such as the fifth generation (5G) standard 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. 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 be present. Each of base station devices 101 to 103 forms one or more cells. In the example of FIG. 1, base station device 101 forms cells 121 and 122, base station device 102 forms cell 123, and base station device 103 forms cell 124. While FIG. 1 shows an example in which base station device 102 and base station device 103 each form only one cell, they may form multiple cells. Furthermore, while FIG. 1 illustrates an example in which base station device 101 forms cell 122, which is included in cell 121, these cells may be formed to cover the same area. Furthermore, for example, base station devices 101 to 103 may be implemented as transmission / reception points (TRPs) 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 separate frequency band or a common frequency band. In this embodiment, at least the frequency band corresponding to cell 121 is different from the frequency bands corresponding to cells 122 to 124, and the frequency bands corresponding to cells 122 to 124 may be different from each other or the same.

[0013] In this embodiment, the terminal device 111 is assumed to be in an RRC connected state with the base station device 101, with the cell 121 formed by the base station device 101 as the primary cell (Pcell). In this state, the terminal device 111 can communicate via multiple cells (multiple component carriers) using a carrier aggregation (CA) function. The base station device 101, which provides the Pcell to the terminal device 111, can transmit to the terminal device 111, in the cell 121, a radio resource control (RRC) message (e.g., an RRC Reconfiguration message) 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 the Scell ​​on the assumption that it has established a connection with the Pcell (is in an RRC connected state with the base station device of the Pcell).

[0014] 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 by 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 the Scell ​​(neighboring cells such as cells 122 to 124 relative to cell 121, which is the 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 may measure signal strength or signal quality, for example, by 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 to which the SSB is transmitted and basic system information. The Scell ​​addition method based on the signal strength or signal quality measurement results 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 may result in a relatively long delay until the Scell ​​addition 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 located in the same location. In the second method, the network adds an Scell ​​without using the signal strength or signal quality measurement results by the terminal device. This method of adding an Scell ​​without using measurement results requires a relatively short time for the configuration process, and therefore can reduce the delay until the Scell ​​addition 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 located in the same location.The addition or deletion of an Scell ​​can be performed, for example, via a radio resource control (RRC) message.

[0015] 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 using 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 element (MAC CE) can specify whether to activate or deactivate the Scell. This MAC CE can be called an Activation / Deactivation MAC CE. The terminal device 111 receives a MAC CE for activating the Scell, and after the Scell ​​is activated, starts a timer (scell deactivation timer). Then, when this timer expires or when the terminal device 111 receives a Deactivation MAC CE, the terminal device 111 deactivates the Scell.

[0016] As described above, in order to add or delete an Scell ​​and to enable or disable an added Scell, it is important that the terminal device 111 be able to measure the signal strength or signal quality of the Scell ​​(or a candidate cell to be added as an 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 the 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 cycle, etc. for measuring the SSB of the added Scell ​​from the scellconfig in an RRC message (e.g., an RRCReconfiguration message) received in the Pcell. The terminal device 111 checks the SSB based RRM Measurement Timing Configuration (SMTC) included in the scellconfig, and can 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 ​​in the SMTC window and reports the results to the base station device 101. Furthermore, information on the measurement period (SMTC) may be included in measoobjectNR, which is an information element in an RRC message. That is, the terminal device 111 can check measoobjectNR to identify the measurement period, measure the SSB of the Scell ​​during that period, and report the measurement result to the base station device 101.

[0017] 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 configured as an Scell ​​for the terminal device 111 in which SSB transmission is stopped for power saving, in which the transmission cycle is longer than in non-power saving operation, or in which some SSBs are not transmitted. In one example, among the 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 the Scells that provide communication services to the terminal device.

[0018] Here, an example of a method for reducing transmission power by suppressing SSB transmission by an SSB-Less Scell ​​will be described using Figures 2A to 2E. Note that Figure 2A illustrates a conventional case in which SSB transmission is not suppressed, while Figures 2B to 2E illustrate examples in which SSB transmission is suppressed. Although not illustrated in Figures 2A to 2E, the SSB-Less Scell ​​may not transmit SSB at all for a predetermined period of time. In Figures 2A to 2E, rectangles indicate frequency and time resources, and hatched areas indicate resources in which SSB is transmitted. The example in Figure 2A illustrates a state in which resources in which SSB is transmitted are provided every 20 milliseconds (ms), and SSB is transmitted in time-division fashion in the directions of multiple beams formed within the cell. In an SSB-Less Scell, for example, as shown in FIG. 2B , by lengthening the SSB transmission period, SSB transmission opportunities can be reduced, thereby achieving power savings. The example of FIG. 2B shows a case where the SSB transmission period is set to 160 ms. This reduces the SSB transmission opportunities to 1 / 8, thereby reducing power consumption in the SSB-Less Scell. Note that the period is not limited to this, and SSB can be transmitted at a period shorter or longer than 160 ms. However, this period is set longer than when power saving operation is not performed. Furthermore, in an SSB-Less Scell, as in the example of FIG. 2C , a separate beam with a wide beam width that collectively covers areas covered by multiple beams can be provided, and SSB can be transmitted using this beam, thereby reducing the number of SSB transmission opportunities. In the state of Fig. 2A, SSB is transmitted in each of eight beams, whereas in the example of Fig. 2C, SSB is transmitted in two beams with wider beam widths. This reduces the SSB transmission opportunity to one-fourth, thereby reducing the power related to SSB transmission in the SSB-Less Scell ​​and reducing power consumption in the network.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 a communication service is to be provided, SSB may be transmitted only using those one or more beams. The example of FIG. 2D shows a case in which the number of beams on which SSB is transmitted 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 reducing network power consumption. Furthermore, as shown in FIG. 2E, SSB may be transmitted using all beams, but in one SSB transmission opportunity, SSB may be transmitted using only some of the beams. The example of FIG. 2E shows an example in which SSB is transmitted using only four beams in one SSB transmission opportunity (arriving every 20 ms). In this case, the number of SSBs transmitted in one transmission opportunity is reduced by half, thereby reducing the power required for SSB transmission in the SSB-Less Scell ​​and reducing network power consumption.

[0019] As described above, in an SSB-Less Scell, SSB can be transmitted in various patterns. Hereinafter, the setting patterns for SSB transmission, such as those shown in FIGS. 2A to 2E, are referred to as setting patterns. When a terminal device performs measurements based on conventional measurement information, depending on the SSB setting pattern, a situation may occur in which SSB is not transmitted at the specified measurement timing, resulting in inefficiency. Furthermore, since the terminal device cannot recognize the existence of SSB in an Scell ​​that is not transmitting, 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 same manner as before. For this reason, this embodiment provides a procedure for efficiently operating an SSB-Less Scell.

[0020] <Notification of Configuration Pattern Information> The base station device of the Pcell generates SSB configuration pattern information for 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 related to 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 of 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 setting pattern information may express part of the characteristics of the setting pattern using a measurement period and timing for SSB measurement (SSB-MTC). That is, information on the measurement period and timing for SSB measurement may be notified to the terminal device as part of the setting pattern information.

[0021] 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 common attributes with an SSB whose transmission is suppressed (stopped) in an SSB-Less Scell. Whether or not the attributes are common may be notified to the terminal device using, for example, a provision related to Quasi Co-Location (QCL) (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 assumed that the beams corresponding to the same direction in these cells have common Doppler shift, Doppler spread, average delay, and delay spread, for example, if the frame transmission timing is 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 including information indicating that the QCL type for this beam (SSB) whose transmission is stopped is qcl-Type A in relation to the corresponding beam (reference signal) of the Pcell 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 an 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 transmission of an on-demand SSB of an SSB-Less Scell ​​without relying on a QCL.This information can be notified to the terminal device, for example, by an information element scellactivationRS-config for setting a reference signal for fast activation of the Scell. However, this is just one example, and this information may be notified in another existing information element, or a new information element may be defined.

[0022] Furthermore, the configuration pattern information may include information used by the terminal device to identify the SSB index of the SSB whose transmission is suppressed in the SSB-Less Scell ​​based on synchronization with the other cells when the terminal device can establish synchronization of the SSB-Less Scell ​​using the synchronization signal of the other cells. This information may be transmitted, for example, as information such as deriveSSB-Indexfromcell or deriveSSB-IndexFromCellInter. Here, deriveSSB-Indexfromcell is used to enable the SSB index of another cell among the multiple cells to be derived based on the SFN and frame position of a cell (serving cell) among the multiple cells that is providing communication services to the terminal device, provided that the Super Frame Numbers (SFNs) and frame boundaries in the time domain are aligned in 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 (considered to be) located in the same location. For example, the terminal device may identify the SSB index of the first Scell ​​based on synchronization with a second Scell ​​that does not perform power saving operation, which is identified based on received information (information on the time and frequency domains of the second Scell). For example, the first Scell ​​may transmit SSBs with SSB indexes 1 to 4 when not performing power saving operation, but may stop transmitting SSBs with SSB indexes 2 and 3 when performing power saving operation. In this case, the terminal device can identify, for example, based on the SSB transmitted in the second Scell, that the SSB indexes of the SSBs whose transmission has been stopped in the first Scell ​​are 2 and 3, and can request the network side to transmit on-demand SSBs as necessary.

[0023] In addition, when the terminal device identifies that the SSB indexes of the SSBs whose transmission has been stopped in the first Scell ​​are 2 and 3, the terminal device can request that all of these SSBs be transmitted as on-demand SSBs, or it may request that only some of them be transmitted.

[0024] For example, it is assumed that a base station device of a first Scell ​​performing power saving operation and a base station device of a second Scell ​​not performing power saving operation are treated as being (approximately) in the same location. Furthermore, it is assumed that the directions of beams corresponding to SSBs with SSB indexes 1 to 4 transmitted when the base station device of the first Scell ​​is performing non-power saving operation are (approximately) the same as the directions of beams of the second Scell ​​with SSB indexes 1 to 4. Here, it is assumed that a terminal device is receiving communication services via the second Scell. Furthermore, it is assumed that when the base station device of the first Scell ​​is performing power saving operation, transmission of SSBs with SSB indexes 2 and 3 among the SSBs with SSB indexes 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 the signal strength or signal quality in the first Scell. In this case, the terminal device compares the signal strength or signal quality of SSBs with SSB index 2 and 3 in the second Scell. Then, assume that the terminal device determines that the signal strength or signal quality of the SSB with SSB index 2 is better than 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 the SSB with SSB index 3 in the first Scell. Then, the terminal device can 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 a first Scell ​​is stopped and there is a correspondence between the beam of the first Scell ​​and the beam of a second Scell ​​(neighboring cell), the terminal device can request transmission of only some of the SSBs on demand, without requesting transmission of all of the 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.

[0025] Furthermore, even when a base station device of a first Scell ​​performing power saving operation and a base station device of a second Scell ​​not performing power saving operation and providing communication services to a terminal device are treated as being in different locations, 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. For example, the terminal device detects that a beam failure has occurred in a beam of the first Scell ​​corresponding to an SSB index of 1, and further fails to recover from the beam failure in a beam corresponding to an SSB index of 4 that is pre-configured 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, for example, refers to the derivedSSB-Indexfromcell and identifies SSB indexes = 2 and 3 of the first Scell ​​based on information about the second Scell. If the terminal device recognizes the direction of the beam corresponding to each SSB index of the first Scell, for example, through pre-settings, it can estimate which beam its own location corresponds to. Then, in one example, if the terminal device determines that it is located in the direction of the beam corresponding to SSB index 2, it can request the network to transmit on-demand SSBs for SSB index 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 the SSB-Less Scell.

[0026] 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 pieces of configuration pattern information are required for one Scell. In this case, identification information for identifying each of the multiple pieces of configuration pattern information may be assigned. Alternatively, configuration pattern information for when SSB transmission is suppressed and configuration pattern information for when SSB transmission is not suppressed may be separately prepared, and identification information for identifying each of the pieces of configuration pattern information may be assigned. Note that, if there is only one piece of 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 or not 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 among 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 when multiple configuration pattern information are identified, SSB transmission using both of the multiple configuration pattern information may be performed in the Scell.

[0027] 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 a power-saving operation is not being performed in the Scell, the SSB setting pattern information for that purpose is notified to the terminal device. Also, when a 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.

[0028] The base station apparatus of the Pcell may notify the terminal apparatus of all of the above-mentioned configuration pattern information using a single RRC message (e.g., an RRC Reconfiguration message). The base station apparatus of the Pcell may distribute the above-mentioned configuration pattern information and notify it to the terminal apparatus 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 that specifies the configuration pattern information in use in the Scell ​​using MAC CE or downlink control information (DCI). As described above, if only the configuration pattern information 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. Identification information that specifies the configuration pattern information being used may be notified dynamically or semi-persistently using MAC CE or DCI. In one example, when the configuration pattern information being used is dynamically notified, 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, a 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 being used when the other DCI is transmitted, and information indicating the validity period. When the configuration pattern information being used is semi-persistently notified, the notification may include, for example, information instructing the activation or deactivation of specific configuration pattern information. 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.

[0029] 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. However, here, a general process 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 the configuration pattern information. Note that, as described above, identification information does not necessarily need 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 to the terminal device 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 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 the configuration pattern information for when SSB transmission is suppressed or the configuration pattern information for when SSB transmission is not suppressed, and perform measurement configuration using the selected configuration pattern information. The terminal device may then 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). In addition, 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 are performed at the same time, and the processes of S302 and S304 can be performed at the same time in the terminal device.

[0030] 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 patterns shown in, for example, FIGS. 2B to 2E, and multiple pieces of configuration information consisting of one or more configuration patterns (combinations) may be prepared. Then, the base station device of the Pcell may use, for example, an RRC message to notify the terminal device of the configuration information consisting of one or more configuration pattern information (combinations) for the SSB-Less Scell, combined with identification information ("#1" to "#3"), such as {#1: configuration information 1; #2: configuration information 2; #3: configuration information 3}. After notifying the terminal device of this information, the base station device of the Pcell may notify the terminal device of which configuration information is to be enabled, such as {Activated: #2}, using a MAC CE or DCI. For example, when information such as {Activated: #2} is notified as described above, one or more setting patterns of "setting information 2" corresponding to the identification information "#2" can be activated. Note that when multiple SSB-Less Scells are configured for a terminal device, the above-described information about the multiple SSB-Less Scells can be notified to the terminal device by one or more RRC messages. For example, the base station device of the 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 can notify the terminal device of information such as {Activated: Scell1:#2; Scell3:#3} using one or more MAC CEs or DCIs. This information may indicate that configuration information 2 of the first Scell ​​(Scell1) and configuration information 3 of the third Scell ​​(Scell3) are enabled.

[0031] Furthermore, in the SSB-Less Scell, configuration pattern information for transmitting On-demand SSB may be defined. In this case, when On-demand SSB is transmitted, identification information corresponding to the configuration pattern information is notified to the terminal device, and the terminal device may perform measurement configuration based on the configuration pattern information and receive the On-demand SSB. Note that this is just one example, and for example, when On-demand SSB is transmitted, the terminal device may be notified that configuration pattern information for when SSB transmission is not suppressed will be used. In this case, the terminal device is in a state where it can measure all SSBs, and therefore can also measure On-demand SSB.

[0032] <On-demand SSB Transmission Request> When a predetermined condition is satisfied, the terminal device may transmit a message requesting on-demand SSB transmission for SSBs whose transmission is suppressed (stopped) in the SSB-Less Scell ​​to the network (the connected Pcell or the base station device providing the Scell). For example, as described above, 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 ​​being used for communication becomes lower than that of the beam transmitting the SSB of the SSB-Less Scell. As this event, for example, conventional events such as Event A2 (an event that occurs when the signal strength or signal quality of an Scell ​​(serving cell) in use falls below a predetermined threshold) and Event A6 (an event that occurs when the signal strength or signal quality of a neighboring cell (here, an SSB-Less Scell) exceeds a value obtained by adding a predetermined offset to the signal strength or signal quality of the Scell ​​in use) can be used. Furthermore, the terminal device can request the network to transmit an On-demand SSB of the SSB-Less Scell, for example, when the magnitude of fluctuation per unit time of the signal strength or signal quality of the Scell ​​in use for communication exceeds a predetermined threshold, or when the length of the period during which the magnitude of the 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 amount of fluctuation 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 purpose, it may request transmission of On-demand SSB in the SSB-Less Scell. Note that the terminal device may identify its own moving 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 On-demand SSB in the SSB-Less Scell ​​when its own device is moving at high speed.Furthermore, for example, when a terminal device detects a beam failure for a beam used for communication, the terminal device requests transmission of an On-demand SSB to confirm whether there is a suitable beam other than a preset beam for recovering from the beam failure. Furthermore, when the 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 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 ​​when, 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.

[0033] These conditions for requesting transmission of On-demand SSBs may be notified to the terminal device in advance, for example, from the base station device of the Pcell. Note that some of these conditions may be stored in the terminal device in advance. Furthermore, in addition to the above conditions, the base station device may indicate the timing at which the terminal device can initiate a transmission request for 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 On-demand SSB transmission if at least one of the above conditions is satisfied within that period. Note that the terminal device does not request On-demand SSB transmission 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. Furthermore, even if the base station device receives a transmission request for On-demand SSBs outside that period, the base station device may ignore the transmission request. The base station device may notify the terminal device of the above-mentioned conditions together with the SSB configuration pattern information (for example, using an RRC message). The base station device may also notify the terminal device of information on a period during which an SSB transmission request is possible (for example, a start timing or an end timing) using a MAC CE or DCI. The base station device may also prepare a radio network temporary identifier (RNTI) for each group of terminal devices including one or more terminal devices, and use the RNTI to notify the terminal device of information indicating the above-mentioned conditions and a period during which an SSB transmission request is possible on a group-by-group basis. The base station device may also notify the terminal device of information indicating the above-mentioned conditions and a period during which an SSB transmission request is possible on a cell-by-cell basis to which the terminal device belongs. That is, the terminal devices 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, using DCI.

[0034] For example, 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) measurement, for time synchronization / frequency synchronization, etc.). Note that transmission of a specific SSB may be requested by an SSB index or an index indicating SSB configuration pattern information.

[0035] The terminal device may transmit an On-demand SSB transmission request to the base station device of the Pcell using a Layer 3 (RRC layer) message. For example, UE Assistance information or a Measurement Report that is periodic or triggered by an event occurrence may be used to request On-demand SSB transmission. The terminal device may also transmit this request using a Layer 2 (MAC layer) message. When a beam failure in the Scell ​​is detected, information requesting On-demand SSB may be included in a BFR MAC CE transmitted to the base station device of the Pcell for beam failure recovery of the Scell. Alternatively, the terminal device may request transmission of the on-demand SSB 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. Alternatively, the terminal device may transmit this request using a Layer 1 (PHY layer) message. For example, the terminal device may request transmission of the on-demand SSB of the Scell ​​using a scheduling request (SR) to the base station device of the Pcell or resources allocated by 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, and uplink resources may be provided by a dedicated configured grant for an on-demand SSB request.

[0036] Furthermore, when Cell DTX / DRX specified in the Rel-18 standard is configured in the 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 message during the inactive period of Cell DRX (even if it transmits, the base station device of the Pcell cannot receive the message). On the other hand, Cell DRX does not apply to SSB, paging, system information block (SIB), and random access channel (RACH), 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 an on-demand SSB 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 an active state. 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 inactive periods of Cell DTX / DRX. Thereafter, the terminal device may transmit a transmission request for On-demand SSBs for the Scell ​​to the base station device of the Pcell as described above. Furthermore, the terminal device may transmit the PRACH to the Pcell using a PRACH resource associated with the preconfigured transmission request for On-demand SSBs for the Scell. In this case, upon receiving the PRACH transmitted in that resource, the base station device of the Pcell may recognize that the transmission request for On-demand SSBs has been received. When such resources for PRACH are provided, other communications cannot be performed using those resources, but the Pcell in which Cell DTX / DRX is set does not need to operate in an active state.

[0037] When a base station device of the Pcell receives an On-demand SSB transmission request, the base station device forwards the transmission request to a base station device providing an SSB-Less Scell ​​via, for example, the Xn interface. The base station device of the SSB-Less Scell ​​can then transmit the On-demand SSB in accordance with the transmission request.

[0038] 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 Scell ​​in the terminal device, or time / frequency synchronization with the 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 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 Scells (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 setting pattern information for the On-demand SSBs (e.g., the SSB index of the SSBs to be transmitted). Furthermore, in addition to the above-described transmission start timing and transmission end timing of the On-demand SSB, as an example, the terminal device may be notified that the On-demand SSB transmitted from the SSB-Less Scell ​​is transmitted periodically from the set transmission timing. Note that even if such notification is not received, the terminal device may assume that the On-demand SSB is transmitted at a predetermined interval, for example, between the transmission start timing and the transmission end timing. In other words, when the terminal device receives information specifying the transmission start timing, it can measure the On-demand SSB, assuming that the On-demand SSB will be transmitted periodically from the transmission start timing.In this case, if the transmission end timing is not notified in advance, the terminal device may consider that the On-demand SSB is transmitted periodically until it receives a notification from, for example, the base station device of the Pcell that the transmission of the On-demand SSB will be stopped.

[0039] 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 in the above <Notification of Configuration Pattern Information>, and then specify the configuration pattern information in a 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 the resources on which On-demand SSBs are transmitted, their transmission period, transmission start timing, and the like, individually, as information different from the above-mentioned configuration pattern information. 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. Then, when the base station device of the Pcell determines that it is not necessary to continue transmitting the On-demand SSB, it can request the SSB-Less Scell ​​to stop transmitting the On-demand SSB, and notify the terminal device that transmission of the On-demand SSB in the SSB-Less Scell ​​will be stopped.

[0040] 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 the SSB-Less Scell, instead of the timing of the end of transmission of the On-demand SSB. This number of transmissions is the number of times the On-demand SSB is transmitted in the SSB-Less Scell, and after the On-demand SSB is 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 the information including the above-mentioned number of transmissions, the terminal may start measuring the On-demand SSB from the timing at which the On-demand SSB transmission starts, count the number of measurements of the On-demand SSB, and when the number of measurements reaches the notified number of transmissions, stop measuring the On-demand SSB (without receiving a notification from the base station device of the Pcell).

[0041] 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. 2A and the setting pattern of FIG. 2B. That is, for example, when the SSB-Less Scell ​​suppresses SSB transmission by lengthening the SSB transmission period as shown in FIG. 2B, the transmission period may be shortened for a certain period as shown in FIG. 2A 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 SSBs in the SSB-Less Scell ​​will be transmitted at a first period for a predetermined period, and will be transmitted at a second period different from the first period (for example, shorter than the first period) after the period ends. The base station device in 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 in the first cycle, or may notify the terminal device of other information such as the transmission start timing and the number of On-demand SSB transmissions. The base station device in the Pcell may notify the terminal device of information on the SSB transmission cycle changed in response to an On-demand SSB request. If the SSB transmission cycle requested by the On-demand SSB is the same as the SSB transmission cycle in another beam in which SSB transmission is not suppressed, for example, the information on the transmission cycle does not need to be notified to the terminal device. The base station device in the Pcell may also notify the terminal device of information on resources used to transmit SSBs during the period during which the SSBs are transmitted in the first cycle, for example. When the terminal device receives the information, it performs SSB measurements at a period corresponding to the SSB transmission period for a specified period from the transmission start timing, and may change the SSB measurement period when the period ends and the SSB transmission period is switched. Furthermore, the Pcell base station device may 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 may further transmit another predetermined notification to the terminal device when it starts transmitting SSBs at a long period following the end of the short period SSB transmission. In other words, the terminal device does not need to be able to specify the above-mentioned period in advance.

[0042] The base station device of the Pcell described above may transmit multiple settings related to transmission of On-demand SSB 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.

[0043] All or part of the above-mentioned information related to 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. The above-mentioned information may be included in a MAC CE that instructs the activation or deactivation of the SSB-Less Scell. The Pcell may also instruct the terminal device to transmit, together with this notification, an event-triggered report of the measurement results of the On-demand SSB, or a periodic, aperiodic, or semi-persistent report. This information may be notified for each cell to which the terminal device belongs, or for each pre-configured group of terminal devices.

[0044] 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 may notify the Scell ​​that SSB transmission should be suppressed or that SSB transmission may be suppressed. Furthermore, if SSB transmission suppression is performed in the Scell, the base station device of the Pcell may notify the terminal device of information regarding the suppression of Scell ​​transmission (e.g., specification of configuration pattern information).

[0045] In one example, when a terminal device transmits a request for transmitting on-demand SSBs in the Scell ​​to a base station device in the Pcell and the base station device in the Pcell receives the transmission request, the base station device in the Pcell transmits a response message to the terminal device. A conventional message for enabling or disabling the 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 transmitting on-demand SSBs has been successful when it receives, from the base station device in 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 transmitting on-demand SSBs has been successful when it receives, from the base station device in the Pcell, a message for disabling the currently enabled Scell ​​within a predetermined period after the request for transmitting on-demand SSBs. Furthermore, a message extending the message for enabling / disabling the Scell ​​may include information indicating that the On-demand SSB transmission request has been accepted. Alternatively, a separate RRC message, MAC CE, or DCI may be used for the response message. Upon receiving the response message, the terminal device may determine that the On-demand SSB transmission transmitted to the base station device of the Pcell has been successful, and may refrain from subsequently transmitting the 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 ​​SSB transmission configuration notified in advance. Furthermore, if the terminal device does not receive a response message from the base station device, it may repeatedly transmit the On-demand SSB transmission request to the base station device of the Pcell. The base station device of the Pcell may notify the terminal device of information setting an upper limit on the number of repeated transmissions of the transmission request. If the terminal device has repeatedly transmitted a transmission request the number of times it has reached an upper limit without receiving a response message, the terminal device may stop transmitting the transmission request.

[0046] Furthermore, to prevent On-demand SSB transmission requests for the same Scell ​​from arriving simultaneously 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 including 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 terminal devices then refrain from requesting transmission of the On-demand SSBs of the identified SSB index. This prevents the terminal devices from concurrently transmitting On-demand SSB transmission requests. If the terminal device receives the information while it is in the middle of, but has not yet completed, a process for transmitting a transmission request, the terminal device may interrupt (terminate) the process.

[0047] FIG. 4 shows an example of a process flow related to an On-demand SSB transmission request. While this process can be modified in various ways, as described above or below, a rough outline of the process flow will be described here, and such modifications will not be mentioned. In this process, a base station device in the Pcell transmits an On-demand SSB transmission request to a base station device in the Scell ​​(S403). When the base station device in the Pcell receives a request to transmit On-demand SSBs from a terminal device (S401), the base station device in the Pcell may transmit the request to the base station device in the Scell. When the base station device in the Pcell receives a request to transmit On-demand SSBs from the terminal device, the base station device in the Pcell may transmit a response message to the terminal device (S402) to prevent the terminal device from repeatedly transmitting On-demand SSB transmission requests. Furthermore, the base station device of the Pcell transmits a notification to the terminal device including configuration information for receiving the On-demand SSB transmitted from the base station device of the Scell ​​(S404). Note that 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 may 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 may notify the base station device of the Scell ​​that SSB transmission should or may be suppressed (S408).

[0048] Note that the base station device of the Pcell may reject an On-demand SSB transmission request received from a terminal device when there is another Scell ​​that does not suppress SSB transmission and the signal strength or signal quality in the terminal device for that Scell ​​is equal to or greater than a predetermined threshold. Note that if the Scell ​​is not enabled for the terminal device, the base station device of the Pcell may transmit a MAC CE to the terminal device to enable the Scell. Then, the base station device of the Pcell may notify the terminal device in the MAC CE that the On-demand SSB transmission request has been rejected. Furthermore, if the Scell ​​is not configured for the terminal device (not added as an Scell ​​for the terminal device), the base station device of the Pcell may notify the terminal device of the additional configuration of the Scell ​​using an RRC message (for example, an RRC Reconfiguration message), and may notify the terminal device in the message that the request to transmit the on-demand SSB has been rejected.

[0049] When a terminal device uses a PRACH (random access preamble) to transmit a request for transmission of an on-demand SSB of an Scell, in which transmission is suppressed, to a base station device of a Pcell, 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-Response Window) in which the 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 for the on-demand SSB. If the terminal device fails to transmit the on-demand SSB, the terminal device may transmit a notification of the failure to the base station device of the Pcell. When the base station device of the Pcell receives the notification from the terminal device, it may instruct the terminal device to add or enable another Scell.

[0050] <Measurement of SSB whose transmission is suppressed> For measurement of an Scell ​​(serving cell) currently being used for communication, it is assumed that ssb-configmobility is included in the MeasoObject associated with the information element ServingCellMO, and the rtype set in reportconfig is SSB. In this case, the measurement pattern of ssb-configmobility of the measoObject associated with the SSB configuration pattern information of that Scell ​​is set and can be notified to the terminal device. Furthermore, if the SSB configuration pattern information of that Scell ​​is changed, the measurement pattern of ssb-configmobility of the measoObject is also changed. In other words, the measurement pattern can be set so that SSB whose transmission is stopped due to transmission suppression is not measured. The instruction to change the measurement pattern may 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, a change in measurement-related parameters may be notified to the terminal device using any of an RRC message, a MAC CE, or a DCI. That is, when ssbconfigmobility is included in the measoobject for measurements of an Scell ​​(neighboring cell), the base station device of the Pcell may configure the SSB measurement pattern in a format associated with the SSB configuration pattern in the Scell ​​and notify the terminal device of information about the measurement pattern. Note that when the SSB configuration pattern in the Scell ​​is changed, the base station device of the Pcell may change the SSB measurement pattern according to the changed configuration pattern and notify the terminal device.

[0051] In one example, the base station device of the Pcell generates configuration information (measconfig) including parameters related to measurements for each Scell ​​in accordance with the SSB configuration pattern information for that Scell, and can 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 the 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 in which no transmission or reception occurs are provided before and after the period in which measurement is actually performed, and the MGL is set to a length that includes this period. Here, when transmission of some SSBs is stopped and measurement is not necessary, the measurement period can be shortened, i.e., the length of the SMTC window and the MGL can be shortened. For example, when transmission of SSB #3 is stopped, the SMTC window can be set to 2 ms and the MGL to 4 ms or 3.5 ms. Alternatively, the SMTC window can be set to 1.5 ms. Furthermore, when transmission of SSB #2 and SSB #3 is stopped, the SMTC window can 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 can be set to 1 ms or 0.5 ms and the MGL to 3 ms or 2.5 ms. Information indicating this setting can be notified to the terminal device from the base station device of the Pcell. Furthermore, for example, the period (measurement gap repetition period (MGRP)) at which the above-described SMTC window is set may be changed. For example, when the setting pattern shown in FIG. 2B is used, even if the MGRP is set to 20 ms, many SMTC windows in which no measurement is performed may occur.Therefore, a setting such as MGRP = 160 ms or 320 ms may be performed. Note that a plurality of measurement parameters (or combinations thereof) such as the above-mentioned SMTC window, MGL, MGRP, etc. may be prepared in advance, and an individual index may be assigned to each of the plurality of measurement parameters and notified to the terminal device, so that the measurement parameter to be actually used can be specified by the index.

[0052] Note that, as in the past, a base station device of a Pcell can notify a terminal device of a measurement result report configuration (reportconfig). Generally, measurement result reports are performed in two ways: a periodic report and an event-trigger report. When an event-trigger report is used, the terminal device reports the measurement result to the base station device when it determines that a predefined event has occurred. Furthermore, the terminal device may execute a preconfigured specific process when it determines that an event has occurred. On the other hand, when periodic reporting is used, there may be cases where SSBs are not transmitted in an SSB-Less Scell, making it impossible to obtain measurement results. In such cases, the terminal device may stop or suspend the transmission of periodic reports. Furthermore, the terminal device may transmit only measurement reports other than those related to such untransmitted SSBs to the base station device. Furthermore, the terminal device may report to the base station device in a measurement report about an SSB that is not transmitted in the SSB-Less Scell ​​that the SSB was not detected.

[0053] <Suppression of SSB Transmission in an SSB-Less Scell> A base station device in an SSB-Less Scell ​​may receive an On-demand SSB transmission request directly from a terminal device. In this case, the base station device in the SSB-Less Scell ​​transmits the SSB of the requested SSB index, and if transmission of other SSBs is being suppressed, it may continue to suppress those transmissions. When a base station device in an SSB-Less Scell ​​receives an On-demand SSB transmission request that does not specify an SSB index, it may end the suppression of all SSB transmissions and resume normal operation. However, this is just one example, and the base station device in 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, when a base station device of the SSB-Less Scell ​​receives a predetermined request (for example, an On-demand SSB transmission request related to a specific SSB or a cell-wide activation request) from a base station device of the Pcell, the base station device may end the suppression of SSB transmission and resume normal operation. Note that, when a base station device of the SSB-Less Scell ​​receives a predetermined request for an SSB of a specific SSB index, the base station device may transmit the SSB without suppressing it and continue suppressing transmission of other SSBs, or may cancel the suppression of transmission of all SSBs. Note that the base station device of the SSB-Less Scell ​​may transmit a response message to the device that sent the request message, such as the On-demand SSB transmission request. For example, when a base station device of an SSB-Less Scell ​​receives an On-demand SSB transmission request from a terminal device, the base station device may transmit a predetermined response message to the terminal device to prevent the transmission request from being repeatedly transmitted. Furthermore, when a base station device of an SSB-Less Scell ​​receives the above-mentioned predetermined request from a base station device of a Pcell, the base station device may return a response message to the base station device of the Pcell. The transmission timing of the response message may be after or before the start of On-demand SSB transmission.

[0054] 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 the location within the cell where terminal devices are concentrated. Furthermore, when a base station device starts transmitting a CSI-RS directed in a specific direction, the base station device may suppress transmission of SSBs (SSBs for which a predetermined QCL Type is set between the transmitted CSI-RS and the transmitted CSI-RS) in the direction from which the CSI-RS is being transmitted. Furthermore, when a base station device of a Pcell disables an Scell ​​that was enabled for a terminal device, 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 longer any 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 more terminal devices using a specific beam of a specific Scell, the base station device of the Pcell may determine that transmission of SSBs corresponding to the specific beam should be suppressed. Furthermore, when the base station device of the Pcell receives a report of measurement results of the signal strength or signal quality of the Scell ​​from the 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 or not it is expected to be used.

[0055] As described above, the terminal device can request the base station device of the SSB-Less Scell, in which SSB transmission is suppressed, to transmit on-demand SSBs, and can establish time / frequency synchronization or measure radio quality based on the SSBs 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 further SSB transmission is unnecessary. 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. Furthermore, the above-described report may be transmitted directly to the base station device of the Scell, and the base station device of the Scell ​​may resume suppression of SSB transmission in response to receiving the report. Furthermore, in a state where a configuration pattern is used in which SSBs are transmitted only for some beams and SSB transmission for other beams is stopped, as shown in, for example, FIG. 2D or 2E , 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. In other words, the beam for which SSB transmission is stopped may be reselected. In one example, when a base station device of the Pcell receives a request for on-demand SSB transmission for a beam for which SSB transmission is stopped, the base station device of the 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 to the base station device of the SSB-Less Scell ​​that forms that beam. When the base station device of the SSB-Less Scell ​​receives the message, it can decide whether to suppress SSB transmission in the beam that is currently transmitting SSB.

[0056] Note that the base station device can use Cell DTX / DRX to set a period during which transmission or reception is suspended. Here, in Cell DTX of Rel-18, signals are not transmitted during inactive periods, but 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 SSB during active periods. Furthermore, partial SSB transmission may be suppressed regardless of whether the period is inactive or active. For example, FIG. 6A shows the relationship between the active period / inactive period 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. 6A, according to the provisions of Rel-18, SSBs are transmitted periodically regardless of the active / inactive periods of conventional Cell DTX. FIG. 6B shows an example in which SSB transmission is suppressed regardless of the active / inactive periods of Cell DTX. In this example, SSBs are transmitted even during the inactive periods of Cell DTX, but the frequency of SSB transmission is suppressed. FIG. 6C shows an example in which SSB transmission is suppressed in conjunction with the active / inactive periods of Cell DTX. In this example, SSBs are transmitted during the active periods of Cell DTX, and SSB transmission is stopped during the inactive periods. This makes it possible to further reduce power consumption during inactive periods. Also, as shown in Fig. 6D, Fig. 6B and Fig. 6C may be combined. That is, the SSB whose transmission frequency is suppressed in Fig. 6B may be further prevented from being transmitted during inactive periods. Furthermore, Cell DTX / DRX may be configured so that an inactive period is set during a period in which SSB transmission is stopped, and an active period is set during a period in which SSB is transmitted.

[0057] <Notification of SSB Transmission Suppression> A base station apparatus in a Pcell or an SSB-Less Scell ​​may not notify a terminal apparatus that SSB transmission will be suppressed. That is, SSB transmission may be suppressed without notifying the terminal apparatus. Furthermore, a base station apparatus in a Pcell may notify a terminal apparatus that SSB transmission will be suppressed in an Scell, for example, by using a MAC CE instructing deactivation of the Scell. Furthermore, a base station apparatus in a Pcell may notify a terminal apparatus that transmission of at least a portion of SSBs will be suppressed in a specific Scell ​​by using a DCI. In one example, a base station apparatus in a Pcell may notify terminal apparatuses belonging to each of a plurality of cells, on a cell-by-cell basis, that transmission of at least a portion of SSBs will be suppressed in a specific Scell ​​by using a DCI. In addition, terminal devices may be grouped using a predetermined rule, an RNTI may be assigned to each group, and a DCI scrambled using that RNTI may be used to notify terminal devices belonging to that group that SSB transmission will be suppressed in a specific Scell.

[0058] 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 programs stored in the ROM 702 and the storage device 704 to control the entire apparatus and each of the above-mentioned processes. 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 program 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 core network nodes. 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.

[0059] 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. Furthermore, 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.

[0060] The configuration information receiving unit 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, so they will not be repeated here. The measurement configuring unit 802 holds the configuration information received by the configuration information receiving unit 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 configuring unit 802. The on-demand SSB requesting unit 804 transmits a request for transmission of SSB, the transmission of which 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 measurement results obtained by the measurement unit 803.

[0061] 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 realized as an integrated unit or may be further subdivided. The functions 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 processes executed by each functional unit have been described above, only the general functions of the base station device will be outlined here.

[0062] 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 SSB, the transmission of which has been suppressed (stopped).

[0063] 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.

[0064] As described above, this embodiment makes it possible to appropriately utilize on-demand SSB in a carrier aggregation Scell, 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."

[0065] 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.

[0066] This application claims priority based on Japanese Patent Application No. 2024-060368, filed April 3, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A terminal device conforming to the cellular communication standard of the Third Generation Partnership Project (3GPP), comprising: a receiving means for receiving, from a base station device providing 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 differs 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.

2. The terminal device of claim 1, wherein the first setting information and the second setting information are each assigned corresponding identification information, the receiving means further receives either the identification information of the first setting information or the identification information of the second setting information from the base station device after receiving the first setting information and the second setting information, and the setting means performs the measurement setting based on the first setting information when the identification information of the first setting information is received, and performs the measurement setting based on the second setting information when the identification information of the second setting information is received.

3. A terminal device as described in claim 1, wherein there are multiple second setting information for each of multiple patterns of SSB transmission when at least a portion of the SSB is not transmitted in the secondary cell, and identification information is assigned to each of the multiple second setting information, and the receiving means, after receiving the multiple second setting information and the identification information for each of the multiple second setting information, further receives identification information for any of the multiple second setting information, and the setting means performs the measurement setting corresponding to the pattern of the second setting information identified by the identification information.

4. The terminal device according to claim 2 or 3, 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 control element (MAC CE) or downlink control information (DCI).

5. A terminal device as described in claim 1, further comprising a transmitting means for transmitting to the base station device a request for transmission of at least a portion of the SSB that has not been transmitted in the secondary cell, wherein the receiving means receives from the base station device configuration information for measuring the SSB that is transmitted in the secondary cell in response to the request, and the configuration means performs measurement configuration using the configuration information.

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

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

8. A base station device conforming to the cellular communication standard of the Third Generation Partnership Project (3GPP), comprising: 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.

9. The base station device according to claim 8, wherein the first setting information and the second setting information are each assigned corresponding identification information, and 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 from the first setting information and the second setting information.

10. A base station device as described in claim 8, wherein there are a plurality of second setting information for each of a plurality of patterns of transmission of the SSB in the secondary cell when at least a portion of the SSB is not transmitted, and identification information is assigned to each of the plurality of second setting information, and after transmitting the plurality of second setting information, the transmitting means further transmits to the terminal device identification information corresponding to the setting information being used among the plurality of second setting information.

11. The base station device according to claim 9 or 10, 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 control element (MAC CE) or downlink control information (DCI).

12. The base station device according to claim 8, further comprising a receiving means for receiving from the terminal device a request for transmission of at least a portion of the SSB that is not being transmitted in the secondary cell, and the transmitting means for transmitting to the terminal device configuration information for measuring the SSB that is transmitted in the secondary cell in response to the request.

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

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. A control method executed by a terminal device conforming to the 3rd Generation Partnership Project (3GPP) cellular communication standard, comprising: receiving, from a base station device providing 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 differs from first setting information for when transmission of the SSB in a secondary cell is not suppressed; configuring measurement of the SSB in the secondary cell based on the second setting information; and measuring the SSB transmitted in the secondary cell using the measurement setting.

16. A control method executed by a base station device conforming to the 3rd Generation Partnership Project (3GPP) cellular communication standard, comprising: providing a primary cell of carrier aggregation to a connected terminal device; and 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.

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 installed in a base station device to execute the control method set forth in claim 16.

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