Terminal device and control method for efficiently changing connection destination cell

Abstract

To perform faster switching between primary and secondary cells in DC and CA.SOLUTION: A base station device presets, to a terminal device 111, a control parameter to be used when communicating with a cell used as a secondary cell as a primary cell, and omits a necessary parameter setting when changing the cell from the secondary cell to the primary cell.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a technology for changing a destination cell in a cellular communication system. [Background technology]

[0002] The cellular communication standard of the Third Generation Partnership Project (3GPP (registered trademark)) specifies dual connectivity (DC) and carrier aggregation (CA) that enable a terminal device to simultaneously use multiple component carriers (CC). Summary of the Invention [Problem to be solved by the invention]

[0003] In DC and CA, it is expected that the cell to which the terminal device is connected will be dynamically switched. In particular, when the communication environment changes frequently and significantly due to the use of higher frequencies in the frequency bands used for communication, it is expected that such switching of the connection destination cell will occur frequently. For this reason, it is important that the connection destination cell be switched quickly.

[0004] The present invention provides a technique that enables high-speed switching of a connection destination cell in a terminal device that is connected to a plurality of cells in parallel. [Means for solving the problem]

[0005] A terminal device according to one aspect of the present invention is a terminal device that communicates with a base station device using a primary cell and a secondary cell by carrier aggregation, and for one or more cells, parameters required when using the one or more cells as primary cells and parameters required when using the one or more cells as secondary cells. Boththe first receiving means for receiving the one or more cells, a change means for changing the first cell to a primary cell when the first cell of the one or more cells is used as a secondary cell, and a second receiving means for receiving from the base station device information regarding whether or not a second cell that is no longer a primary cell after the first cell is changed to a primary cell will continue to be used as a secondary cell. Effect of the Invention

[0006] According to the present invention, in a terminal device that is connected to a plurality of cells in parallel, it is possible to perform high-speed switching of the cell to which the terminal device is connected. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication network. [Diagram 2] FIG. 2 illustrates an example of a hardware configuration of the apparatus. [Diagram 3] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station device. [Figure 4] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. [Diagram 5] FIG. 1 is a diagram showing an example of a flow of processing executed in a wireless communication network. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the multiple features described in the embodiments may be arbitrarily combined. In addition, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0009] (System Configuration) 1 shows an example of the configuration of a wireless communication system according to this embodiment. This wireless communication system is, for example, a cellular communication standard such as Long Term Evolution (LTE) or fifth generation (5G), or a successor generation thereof, and includes a base station device 101 and a terminal device 111. Note that, for simplicity of explanation, a small number of base station devices and terminal devices are shown here, but naturally, a large number of base station devices and terminal devices may exist.

[0010] In this embodiment, the terminal device 111 is configured to be able to communicate with the base station device 101 in parallel using multiple component carriers (CCs) at the same time by dual connectivity (DC) or carrier aggregation (CA). Note that FIG. 1 shows an example in which the terminal device 111 is connected to one base station device 101, but the terminal device 111 may be connected to multiple base station devices in parallel. In addition, in the following description, "CC" can also be read as "cell". Although multiple CCs may be configured in the same frequency band, in this embodiment, communication is performed using multiple CCs corresponding to multiple frequency bands respectively. In this embodiment, the terminal device 111 is configured to be able to use only some combinations of frequency bands, not all combinations of multiple frequency bands that are different from each other. For example, the terminal device 111 can use a combination of a first frequency band and a second frequency band, and a combination of a first frequency band and a third frequency band, but cannot use a combination of a second frequency band and a third frequency band, or a combination of a first frequency band, a second frequency band and a third frequency band. The first frequency band, the second frequency band, and the third frequency band can be, for example, band 1, band 18, and band 41, which are specified by the standard. Although three frequency bands are described here, further frequency bands such as a fourth frequency band (for example, band 42) may be provided.

[0011] In this embodiment, for example, the base station device 101 communicates with a terminal device using carrier aggregation (CA) in which a component carrier (CC) of a first frequency band is used as a primary cell and a component carrier (CC) of a second frequency band is used as a secondary cell. Note that both the primary cell and the secondary cell may be configured as LTE cells, or both the primary cell and the secondary cell may be configured as 5G cells. That is, both the primary cell and the secondary cell may be configured as cells of the same wireless system. Also, the primary cell may be configured as an LTE cell and the secondary cell may be configured as a 5G cell, or the primary cell may be configured as a 5G cell and the secondary cell may be configured as a cell defined in LTE or a further next generation. That is, the primary cell and the secondary cell may be configured as cells of different wireless systems.

[0012] In this embodiment, a case where a primary cell and a secondary cell are replaced is considered. For such a replacement, two instructions are required: a handover for changing a currently used primary cell to a new primary cell, and a secondary cell change for changing a currently used secondary cell to a new secondary cell. This instruction is performed using RRC (Radio Resource Control) signaling of layer 3. That is, for example, the base station device 101 instructs the terminal device 111 to change the component carrier (CC) of the second frequency band to the primary cell and the component carrier (CC) of the first frequency band to the secondary cell by an RRC message. At this time, when the terminal device 111 receives an instruction to change from the base station device 101, it usually initializes state variables used for controlling the layer 2 and layer 1 for the primary cell and the secondary cell, respectively. Then, the terminal device 111 reconfigures the control parameters of layer 2 and layer 1 according to the cell after the change. Also, at this time, if the terminal device 111 is executing at least one of the control processes of layer 2 and layer 1, the terminal device 111 stops the process.

[0013] In general, the state variables used for layer 2 and layer 1 control that are initialized include, for example, a counter BFI_COUNTER used for beam failure detection, an SR_COUNTER used for controlling a scheduling request, and an NTA used for timing advance control that realizes uplink transmission timing correction.

[0014] When beamforming is applied, state variables used for controlling layer 2 and layer 1 may include state variables related to beam control. The base station device 101 and the terminal device 111 use a transmission configuration indication (TCI) to control a transmission beam (Tx beam) and a reception beam (Rx beam) of each signal / channel. For example, the base station device 101 determines a transmission beam to be used for downlink transmission in a physical downlink shared channel (PDSCH) from a measurement result of a reference signal reported from the terminal device 111. Then, before data transmission using the PDSCH, the base station device 101 instructs the terminal device 111 to set a TCI for receiving a signal transmitted by the terminal device 111 in the transmission beam, using downlink control information (DCI) included in a physical downlink control channel (PDCCH). The base station device 101 also determines a transmission beam to be used for uplink transmission in a physical uplink shared channel (PUSCH) from a measurement result of a reference signal transmitted from the terminal device 111. Then, when scheduling the PUSCH, the base station apparatus 101 instructs the terminal apparatus 111 of a TCI setting for transmitting a signal using the transmission beam by using the downlink control information (DCI) included in the physical downlink control channel (PDCCH). In this beam control, the base station apparatus 101 may, for example, notify the terminal apparatus 111 of TCI settings that are available for use in the terminal apparatus 111 by layer 3 signaling, and then activate some of the TCI settings and select an appropriate TCI setting from the activated TCI settings. The base station apparatus 111 may instruct the terminal apparatus 101 to activate or deactivate each TCI setting by using a MAC CE (medium access control element). Then, the base station apparatus 101 may notify the terminal apparatus 111 of a TCI setting corresponding to a beam to be used from among the activated TCI settings by using the above-mentioned DCI. In addition, as another beam control method, there is also a method using an SRS Resource Indicator.In this method, the base station device 101 determines an SRS Resource Indicator (SRS-RI) based on a sounding reference signal transmitted from the terminal device 111, and notifies the terminal device 111. The terminal device 111 can determine a precoder to be used for a transmission beam from information such as the SRS Resource Indicator, a codebook, and the number of antenna ports specified by the base station device 101. The terminal device 111 generates a transmission beam to be used for uplink transmission in a physical uplink shared channel (PUSCH) using the determined precoder. When the primary cell or secondary cell is changed, information on Activation / Deactivation of the TCI setting that was set before the change, the beam transmission of channels such as PDSCH and PUSCH, the TCI setting used for beam reception, and the SRS-RI setting are initialized upon the change.

[0015] Also, when carrier aggregation (CA) is performed, HARQ (composite automatic repeat request) control is performed in layer 2 and layer 1, as in the case of single carrier communication. As an example, the terminal device 111 reports a HARQ-ACK / NACK indicating whether the PDSCH data has been successfully decoded to the base station device 101 using a PUCCH. At this time, if the terminal device 111 is instructed to change the primary cell after receiving the PDSCH data of the primary cell and before transmitting the HARQ-ACK / NACK, the terminal device 111 may cancel the scheduled transmission of the HARQ-ACK / NACK. Also, when the secondary cell is changed, the terminal device 111 may cancel the scheduled transmission of the HARQ-ACK / NACK, as in the case of the primary cell described above, if the terminal device 111 is instructed to change the secondary cell after receiving the PDSCH data of the secondary cell and before transmitting the HARQ-ACK / NACK. Furthermore, in the HARQ control, when the terminal device 111 fails to decode the received data (when the decoded data contains an error), the terminal device 111 stores the data in a memory area called a soft buffer for subsequent error correction. Then, the terminal device 111 combines the data newly retransmitted from the base station device 101 with the stored data, and decodes the combined data. This makes it possible to execute communication that is highly resistant to errors. Generally, when an instruction is given to change the primary cell or secondary cell, the terminal device 111 deletes the data stored in the soft buffer for error correction.

[0016] Furthermore, the control of layer 2 and layer 1 may include CDRX (Connected Discontinuous Reception) control. As an example, when changing the primary cell to the secondary cell, the terminal device 111 stops timers related to CDRX control, such as onDurationTimer (a timer that controls a period during which DRX ON is maintained), drx-inactivityTimer (a DRX inactivity timer that is started to maintain DRX ON for a certain period after receiving PDCCH), drx-ShortCycleTimer (a timer that specifies a period according to a Short DRX cycle), drx-HARQ-RTT-TimerDL (a minimum duration until downlink resource allocation for HARQ retransmission), and drx-HARQ-RTT-TimerUL (a minimum duration until downlink resource allocation for HARQ retransmission).

[0017] Furthermore, the control of layer 2 or layer 1 may include a power headroom report (PHR) control. As an example, when the terminal device 111 changes the primary cell to the secondary cell, the terminal device 111 stops timers related to PHR control, such as a phr-PeriodicTimer (a timer for controlling the PHR report period) and a phr-ProhibitTimer (a timer for controlling the PHR report prohibition period).

[0018] On the other hand, when a cell that was a primary cell is changed to a secondary cell, in both the terminal device 111 and the base station device 101, the MAC entity and PHY (physical) layer that perform the control of layer 2 and layer 1 for the primary cell can continue to be used for the control of the secondary cell after the change. For this reason, when the control parameters of layer 2 and layer 1 are changed, it is necessary to initialize the state variables used for the control of layer 2 and layer 1 before the primary cell is changed to the secondary cell, but if the control parameters are not changed, it can be said that there is no need to initialize the state variables. Similarly, when a cell that was a secondary cell is changed to a primary cell, the MAC entity and PHY layer that perform the control of layer 2 and layer 1 for the secondary cell can continue to be used for the control of the primary cell after the change. For this reason, in this case as well, it can be said that there is no need to initialize the state variables used for the control if the control parameters of layer 2 and layer 1 are not changed.

[0019] In this embodiment, in consideration of such circumstances, when the terminal device 111 replaces the primary cell with the secondary cell, it is possible to maintain the state variables for controlling the layer 2 and the layer 1 without initializing them as necessary. In one example, when the terminal device 111 receives an instruction from the base station device 101 to change the cell used as the primary cell to the secondary cell, the terminal device 111 determines whether or not to change at least one of the control parameters of the layer 2 and the layer 1. Then, when the terminal device 111 determines that the control parameters should be changed, it initializes the state variables used for the control of the layer 2 and the layer 1 as in the past. On the other hand, when the terminal device 111 determines that the control parameters should not be changed, it does not initialize the state variables used for the control of the layer 2 and the layer 1. Also, when the terminal device 111 determines that the control parameters should be changed, it terminates the process that was started before the reception of the cell change instruction as in the past. On the other hand, when the terminal device 111 determines that the control parameters should not be changed, it continues the process that was started before the reception of the cell change instruction. In addition, the terminal device 111 may perform the same process when receiving an instruction to change a cell used as a secondary cell to a primary cell. That is, the terminal device 111 determines whether or not to change control parameters for at least one of layer 2 and layer 1, and determines whether or not to initialize state variables used for controlling layer 2 and layer 1, and whether or not to continue processing that was started before receiving the cell change instruction. Note that processing such as determining whether or not to change control parameters may be performed only for some of the above-mentioned control items. For example, the terminal device 111 may determine whether or not to change control parameters only for HARQ, and determine whether or not to initialize state variables and continue processing, and may not perform such determinations for beamforming, PHR, and the like. In addition, the terminal device 111 may separately determine each of the control items for which a determination is made as to whether or not a control parameter has been changed, and individually determine whether or not to initialize state variables and continue processing based on each determination.Furthermore, when the control parameters are not changed, the terminal device 111 may notify the base station device 101 of capability information (UE Capability) indicating whether or not it is possible to implement state variables or continue processing. In this case, the base station device 101 may instruct the terminal device 111 whether or not to initialize state variables or continue processing, depending on the capability information notified from the terminal device 111. Note that the capability information may be notified to the base station device 101 with appropriate information set for each control item.

[0020] When the terminal device 111 receives a secondary cell or primary cell change instruction, if it determines that the parameters related to beam failure detection and beam recovery have not been changed, it maintains the state variables related to beam failure detection and beam recovery without initializing them. Also, the terminal device 111 can continue the beam-related processing that was started before receiving the cell change instruction. For example, if the terminal device 111 detects beam failure detection and starts beamFailureDetectionTimer before receiving the cell change instruction, it holds the beam failure detection counter BFI_COUNTER without initializing it when it receives the change instruction, and continues the beamFailureDetectionTimer without stopping it. Also, if the terminal device 111 starts beam recovery processing before receiving the cell change instruction, it continues the processing without stopping it when it receives the change instruction. For example, when the terminal device 111 receives a cell change instruction after transmitting a RACH preamble for beam recovery, it continues the timer ra-ResponseWindow that controls the monitoring period of the RA response from the base station device 101 without stopping it. Furthermore, when the terminal device 111 receives a cell change instruction after transmitting MAC CE (msg3) for beam recovery, the Contention Resolution Timer (ra-ContentionResolutionTimer) continues without stopping. This allows the terminal device 111 to avoid interruption of beam failure detection and beam recovery triggered by a change of a secondary cell or a primary cell, and to perform beam control more efficiently. Also, for a scheduling request (Scheduling Request), similar to beam failure and recovery, processing can be made more efficient. That is, when the terminal device 111 transmits a scheduling request (Scheduling Request) before receiving a cell change instruction, when the terminal device 111 receives the change instruction, the scheduling request counter SR_COUNTER is held without being initialized, and the scheduling request prohibition timer sr-ProhibitTimer that is running continues without being stopped.As a result, the scheduling request suppression process is continued without being interrupted by a change instruction of the secondary cell or the primary cell, and the process can be made more efficient. Furthermore, when the terminal device 111 determines that a parameter used for timing advance control that realizes correction of the uplink transmission timing has not been changed, the terminal device 111 holds the timing value NTA without initializing it. Furthermore, the terminal device 111 may maintain a time alignment timer (TAT) that was activated before receiving a cell change instruction, without stopping it, until the timer expires. As a result, when the terminal device 111 receives an instruction to change the secondary cell to the primary cell, the terminal device 111 holds the timing value NTA, and therefore, it is possible to omit a random access procedure for newly correcting the uplink transmission timing. Note that, after receiving a change instruction of the primary cell or the secondary cell from the base station device 111, the terminal device 111 may initialize the timing value NTA related to a cell not used for communication and may also stop the time alignment timer (TAT).

[0021] When beamforming is applied, if it is determined that the control parameters of beamforming are not changed, the cell switching process can be accelerated. In one example, the terminal device 111 can hold the activation / deactivation information of the TCI setting received from the base station device 101 before receiving an instruction to change the primary cell to the secondary cell, the beam transmission of channels such as PDSCH and PUSCH, the TCI setting used for beam reception, the information related to beam control related to the SRS-RI setting, and the state variables without initializing them. In this case, after the change of the primary cell to the secondary cell, the base station device 101 does not need to select an optimal beam again from the measurement result of the reference signal from the terminal device 111 and notify the terminal device 111 of information for beam control. Therefore, it is possible to start data transmission and reception using an appropriate transmission beam and reception beam between the base station device 101 and the terminal device 111 earlier.

[0022] When it is determined that the HARQ control parameters are not changed, for example, when the terminal device 111 receives an instruction to change to a secondary cell before transmitting a HARQ-ACK / NACK of a decoded result after receiving a PDSCH, the terminal device 111 can transmit the HARQ-ACK / NACK after changing to a secondary cell. In this case, the HARQ control parameters can be, for example, a parameter nrofHARQ-ProcessesForPDSCH for setting the number of HARQ processes used for PDSCH, a parameter downlinkHARQ-FeedbackDisabled for disabling DL HARQ feedback, a parameter harq-ProcessNumberSizeDCI-1-2 for setting the number of bits of the HARQ process number included in DCI format 1_2, etc. Conventionally, when the terminal device 111 changes the primary cell to a secondary cell, it cannot transmit the HARQ-ACK / NACK in the secondary cell after the change, and the base station device 101 retransmits the PDSCH. In response to this, the terminal device 111 transmits HARQ-ACK / NACK in the changed secondary cell as described above, thereby suppressing the occurrence of unnecessary retransmission of PDSCH and making communication more efficient. In addition, at this time, the terminal device 111 may delay the start of the process of changing the primary cell to the secondary cell after transmitting HARQ-ACK / NACK. In addition, when the terminal device 111 receives an instruction to change the primary cell to the secondary cell and determines that the control parameters related to HARQ are not changed, it continues to hold the data held in the soft buffer of HARQ without deleting it. As a result, it is possible to combine data received before the cell change instruction and data received after the change instruction, and to decode the combined data, thereby making it possible to make the reception process more efficient.

[0023] Also, when it is determined that the parameters of the CDRX control are not changed, the terminal device 111 can continue the timers related to the CDRX control, such as the onDurationTimer, inactivityTimer, drx-ShortCycleTimer, drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerUL, without stopping them. This makes it possible to avoid turning on the power of the terminal device 111 unnecessarily, triggered by a change to a secondary cell, and to improve the efficiency of the CDRX control. When the drx-ShortCycleTimer is activated, the terminal device 111 can transition to LongDRX more quickly when there is no transmission of the PDCCH from the base station device 101 by continuing the drx-ShortCycleTimer. This makes it possible to further save power in the terminal device 111.

[0024] Also, when it is determined that the parameters of the PHR control are not changed, the terminal device 111 can continue the timers related to the PHR control, such as the phr-PeriodicTimer and the phr-ProhibitTimer, without stopping them. When the terminal device 111 stops the phr-PeriodicTimer, the phr-PeriodicTimer is started at the time of the first uplink transmission after changing the primary cell to the secondary cell, and the transmission timing of the PHR is delayed. In contrast, the terminal device 111 can appropriately advance the transmission timing of the PHR by continuing the phr-PeriodicTimer, compared to the case where the phr-PeriodicTimer is stopped. As a result, the control of the uplink transmission power in the terminal device 111 can be performed more precisely. In addition, when the phr-ProhibitTimer is stopped, the PHR transmission prohibition period is reset once, which may cause unnecessary PHR transmission. In contrast, the terminal device 111 can prevent such unnecessary PHR transmission from occurring by continuing the phr-ProhibitTimer.

[0025] In the above, detailed control regarding beamforming control, HARQ control, CDRX control, and PHR control when the terminal device 111 receives an instruction to change the cell used as a primary cell to a secondary cell has been described, but similar control can be performed when an instruction to change the cell used as a secondary cell to a primary cell is received. This allows the terminal device 111 to efficiently perform control regarding scheduling request control, timing advance control, beamforming control, HARQ control, CDRX control, and PHR control.

[0026] Furthermore, when instructing the terminal device 111 to start carrier aggregation (CA), the base station device 101 notifies the terminal device 111 of control parameters to be used when communicating with the cell to be added as a secondary cell by layer 3 signaling such as RRC Reconfiguration for the cell to be added as a secondary cell. At this time, the base station device 101 may further notify the terminal device 111 of control parameters to be used when communicating with the cell to be added as a primary cell. That is, the base station device 101 may notify the terminal device 111 in advance of control parameters to be used when changing the cell to be added as a secondary cell to a primary cell and communicating with the cell. This makes it possible to omit setting of necessary parameters from the base station device 101 when the terminal device 111 changes the cell from a secondary cell to a primary cell. This makes it possible to reduce the message size of the change instruction transmitted from the base station device 101 to the terminal device 111. In addition, if the same control parameters are used when the cell is used as a secondary cell and when the cell is used as a primary cell, the message size can be reduced by transmitting a message that includes information indicating that one of the control parameters is to be omitted and in which that control parameter is omitted.

[0027] Furthermore, by notifying the terminal device 111 in advance of the control parameters to be used when changing the cell to be added as a secondary cell to the primary cell and performing communication, the base station device 101 can issue an instruction to change the cell used as a secondary cell to the primary cell by layer 2 or layer 1 signaling, not layer 3 signaling. This allows the terminal device 111 to execute the process of changing the secondary cell to the primary cell at higher speed. Furthermore, it is sufficient that the change instruction is issued by either the primary cell or the secondary cell. For example, when the primary cell is in DRX or beam recovery and it is difficult to transmit and receive the change instruction, the base station device 101 can reduce the delay in changing the secondary cell to the primary cell by transmitting the change instruction to the terminal device 111 in the secondary cell. Furthermore, the terminal device 111 can transmit a report that the process of changing the secondary cell to the new primary cell has been completed to the base station device 101 by layer 2 or layer 1 signaling, such as uplink MAC CE or uplink control information (UCI). This report may be transmitted to the base station device 101, for example, in the cell that is to be newly used as the primary cell. In addition to the change instruction, the base station device 101 may also notify the terminal device 111 of information indicating whether or not the cell that is no longer the primary cell is to be continued to be used as a secondary cell. The terminal device 111 may change the cell that is no longer the primary cell to a secondary cell according to the instruction from the base station device 101, or may execute a process of disabling the cell.

[0028] In addition, the base station device 101 can set, in the terminal device 111, control parameters to be used when a cell used as a secondary cell is changed to a primary cell and communication is performed, and then request the terminal device 111 to measure and report the radio quality of the primary cell and the secondary cell, and acquire the measurement results. Based on the acquired measurement results, the base station device 101 can instruct the terminal device 111 to change the cell used as a secondary cell to a primary cell. Note that whether the measurement result is to be reported periodically (Periodic) or by event (Event), the period in the case of periodic reporting, and the event type and event threshold in the case of event reporting can be set in a layer 3 message when setting the control parameters. In addition, before setting the control parameters to be used when communication is performed as a primary cell, if there is already a radio quality measurement setting set in the terminal device 111, the base station device 101 may acquire the measurement results according to that setting. Here, the radio quality acquired by the base station device 101 may be, for example, channel state information (CSI)-reference signal (RS), received signal strength indicator (RSSI) of synchronization signal (SS), reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-noise ratio (SNR), signal-to-interference and noise ratio (SINR), and counter value BFI_COUNTER used for beam obstruction detection. In addition, for the radio quality measurement set by the above-mentioned layer 3 message, the start and end of the measurement may be instructed by layer 1 or layer 2 signaling. This allows dynamic switching between execution / non-execution of measurement for each cell, thereby making the measurement more efficient. Here, for example, when a measurement configuration (MeasConfig: Measurement Configuration) is composed of a measurement object (MeasObject: Measurement Object), a report configuration (ReportConfig: Report Configuration), and a measurement identifier (MeasId: Measurement Identifier), a measurement identifier indicating the measurement configuration for which measurement should be started or stopped can be specified by layer 2 signaling such as downlink MAC CE, or by layer 1 signaling such as DCI.

[0029] Furthermore, when changing a secondary cell to a primary cell, the terminal device 111 may determine that the change should be made without an instruction from the base station device 101 and request the base station device 101 to change the cell. In this case, the base station device 101 notifies the terminal device 111 in advance of conditions and criteria for changing a cell used as a secondary cell to a primary cell. At this time, the conditions for implementing the change given to the terminal device 111 may include, for example, that the radio quality of the secondary cell is equal to or higher than a specific threshold, or that the radio quality of the primary cell is equal to or lower than a specific threshold. Note that these conditions and criteria may be set in the terminal device 111 by layer 3 signaling together with control parameters used when communicating with the cell as the primary cell. When the terminal device 111 determines that the given conditions are satisfied, it requests the base station device 101 to change the cell used as the secondary cell to the primary cell. Then, the base station device 101 may determine whether or not to comply with the request of the terminal device 111, and may return a response including the determination result to the terminal device 111. At this time, the terminal device 111 may transmit a request to change to a primary cell to the base station device 101 by layer 2 signaling such as uplink MAC CE, or by layer 1 signaling such as UCI. The base station device 101 may transmit the response to the terminal device 111 by layer 2 signaling such as downlink MAC CE, or by layer 1 signaling such as DCI.

[0030] Control parameters used when the terminal device 111 communicates in the primary cell include radio link failure (RLF) control, low-speed movement judgment control (lowMobilityEvaluation), radio link monitoring power saving control (goodServingCellEvaluationRLM), random access control, etc. Radio link failure control is a control in which the terminal device 111 detects out-of-sync during communication and performs reconnection processing to the base station device 101 as necessary, and the control parameters include a timer value t310 for controlling a count period of the number of consecutive out-of-sync occurrences, n310 specifying the number of consecutive out-of-sync occurrences, and n311 specifying the number of consecutive in-sync occurrences. When out-of-sync occurs n310 times in succession, the terminal device 111 starts t310, and thereafter, when t310 expires without detecting synchronization n311 times in succession, it determines that a radio link failure has occurred and starts reconnection processing. The low-speed movement determination control is a control in which the terminal device 111 determines whether or not it is in a low-speed state, and when it is determined that it is in a low-speed state, reduces the measurement frequency of the radio quality measurement of the serving cell, thereby achieving power saving. Control parameters for the low-speed movement determination control include s-SearchDeltaP-Connected and t-SearchDeltaP-Connected. The terminal device 111 determines whether or not it is in a low-speed state by determining whether or not the fluctuation width of the measured radio quality falls within s-SearchDeltaP-Connected at regular intervals indicated by t-SearchDeltaP-Connected. The radio link monitoring power saving control is a control in which, when the radio quality of the serving cell is good, the cycle of radio link monitoring is lengthened, the measurement frequency is reduced, and power consumption is suppressed. The control parameters for the radio link monitoring power saving control include information specifying criteria and conditions for implementing the function. When communication is performed using carrier aggregation (CA), uplink transmission is performed only in the primary cell. For this reason, the random access control is specific to the primary cell, and the control parameters thereof can be included in the control parameters used when communicating as the primary cell.

[0031] A timer (e.g., t304) used when switching to the primary cell may also be included in the control parameters used when communicating as the primary cell. The terminal device 111 starts timer t304 at the timing when switching to the primary cell is instructed by layer 2 or layer 1 signaling, and stops t304 when the subsequent random access is successfully completed. If t304 expires without successful random access, the terminal device 111 may consider that switching to the primary cell has failed and start a reconnection process. If random access is not performed, the terminal device 111 may stop t304 in response to completion of transmission of a response signal to the base station device 101 in response to the instruction to switch to the primary cell.

[0032] In addition, a Radio Network Temporary Identifier (RNTI) used when a secondary cell is changed to a primary cell may also be included in the control parameters used when communicating as a primary cell. The RNTI is an identifier given to the base station device 101 to distinguish between multiple terminal devices connected to the base station device 101. The terminal device 111 compares the RNTI included in a received signal with its own RNTI to determine whether the received signal is addressed to the terminal device 111. The RNTI may be notified from the base station device 101 to the terminal device 111 by layer 3 signaling at the time of setting the control parameters before changing to the primary cell, or may be notified from the base station device 101 to the terminal device 111 by layer 2 or layer 1 signaling at the time of changing to the primary cell. In one example, the terminal device 111 may change the secondary cell to a primary cell upon obtaining identification information of the cell that was used as a secondary cell and the value of the RNTI (RNTI-Value) from the base station device 101 via MAC CE or DCI.

[0033] Furthermore, the base station device 101 may notify the connected (communicating) terminal device 111 of the control parameters to be used when communicating with a cell not used for communication as a secondary cell and the control parameters to be used when communicating with the cell as a primary cell, for example, by layer 3 signaling such as RRC Reconfiguration. Note that only the control parameters to be used when communicating with the cell as a secondary cell, or only the control parameters to be used when communicating with the cell as a primary cell may be notified to the terminal device 111. In this case, after notifying the control parameters, the base station device 101 may transmit, to the terminal device 111, an instruction to change the primary cell to that cell or an instruction to change the secondary cell to that cell, by layer 2 or layer 1 signaling, based on the wireless quality measurement result reported from the terminal device 111. Also in this case, the terminal device 111 may decide to request a change of the primary cell regardless of the instruction from the base station device 101, and transmit a request signal to the base station device 101. At this time, the base station device 101 may notify the terminal device 111 in advance of conditions and criteria for setting the cell as a primary cell or a secondary cell. These conditions and criteria are notified from the base station device 101 to the terminal device 111 by layer 3 signaling together with control parameters to be used when the terminal device 111 communicates with the cell as a primary cell or a secondary cell. When the terminal device 111 satisfies the given conditions, it transmits a request message to the base station device 101 to set the cell as a primary cell or a secondary cell. Then, the base station device 101 may determine whether or not to comply with the request of the terminal device 111, and may return a response including the determination result to the terminal device 111. At this time, the terminal device 111 may transmit a request to change the cell to a primary cell to the base station device 101 by layer 2 signaling such as uplink MAC CE, or by layer 1 signaling such as UCI. Furthermore, the base station device 101 can transmit a response to the change request to the terminal device 111 by layer 2 signaling such as downlink MAC CE or layer 1 signaling such as DCI.In addition, for a cell not used for communication, notification of the control parameters used when the cell is used as a secondary cell and the control parameters used when the cell is used as a primary cell may be included in the layer 3 message instructing the start of communication. In this case, along with the control parameters used when communicating as a secondary cell of one or more cells and the control parameters used when communicating as a primary cell, information for identifying the primary cell, secondary cell, and cell not used for communication used for communication at the start of communication may be included. In addition, in the case where radio measurement settings are simultaneously instructed, information for identifying the measurement settings to be measured and the measurement settings not to be measured at the time of starting communication may be included. In addition, when the control parameters of multiple cells are notified, the control parameters of some cells are notified by the difference in the setting value from the control parameters of other cells, thereby reducing the data size of the control parameters.

[0034] Furthermore, the terminal device 111 deletes the control parameters to be used when the cell is used as a primary cell or a secondary cell, according to an instruction from the base station device 101. The base station device 101 may transmit a control parameter deletion instruction to the terminal device 111 using signaling of layer 3, layer 2, or layer 1. Furthermore, when setting the control parameter, the base station device 101 may further notify the terminal device 111 of a condition for deleting the control parameter. The terminal device 111 may delete the control parameter not only when an instruction from the base station device 101 is received or when the notified condition is satisfied, but also, for example, when terminating communication and transitioning to a standby state.

[0035] In addition, when the terminal device 111 establishes a connection with one base station device that provides a communication service in a specific area (by initial connection or handover to the base station device, or by adding a cell provided by the base station device as a secondary cell), the base station device may notify the terminal device 111 of information on control parameters. The base station device to which the terminal device 111 is connected may notify the terminal device 111 of pre-setting information including conditions to be satisfied in the terminal device 111 when multiple base station devices belonging to the specific area are set as primary cells or secondary cells, and settings of control parameters to be used when performing communication as a primary cell or secondary cell. Then, the base station device to which the terminal device 111 is connected shares the pre-setting information notified to the terminal device 111 with other base station devices in the specific area. Note that the base station device to which the terminal device 111 is connected may also perform pre-setting when handover from another base station device to itself is performed, and share the pre-setting information with other base station devices in the specific area. Then, the base station device in the predetermined area may delete the pre-configured information in response to the terminal device 111 being handed over to outside the predetermined area. According to this, after the terminal device 111 establishes a connection in the predetermined area, the terminal device 111 can continuously execute a conditional handover in the predetermined area. Note that the predetermined area may be, for example, an area corresponding to the same tracking area identifier (TAI), the same tracking area code (TAC), or the same system information area identifier (systemInformationAreaID), but another area (for example, an area specific to the terminal device 111) may be defined. Also, the predetermined area may be an area corresponding to a RAN-based Notification Area used when the base station device records / manages the location information of the terminal device 111 when the terminal device 111 operates in the RRC_INACTIVE state. Also, the predetermined area may be an area constituted by some or all of the cells accommodated in the same aggregation node (Central Unit: CU).

[0036] The base station device 101 determines whether to change the secondary cell to a primary cell and whether to change the primary cell to a secondary cell, taking into consideration capability information (UE Capability) indicated by the terminal device 111, which includes information on the combination of frequency bands that the terminal device 111 can use when performing carrier aggregation.

[0037] For example, it is assumed that the capability information of the terminal device 111 indicates that only band 1 is capable of uplink transmission in carrier aggregation of band 1 and band 41. In this case, when the primary cell is a cell using band 1 and the secondary cell is a cell using band 41, the base station device 101 cannot change the cell using band 41, which cannot perform uplink transmission, to the primary cell and the cell using band 1 to the secondary cell. That is, in such a case, the base station device 101 does not instruct the terminal device 111 to continue carrier aggregation by replacing the primary cell with the secondary cell. In this case, as an example, the base station device 101 can instruct the terminal device 111 to change the cell using band 41 to the primary cell and to not use the cell using band 1 that was used as the primary cell, without changing it to a secondary cell. Furthermore, when the terminal device 111 receives an instruction from the base station device 101 to set the cell using band 41 as the primary cell and the cell using band 1 as the secondary cell, the terminal device 111 may set the cell using band 41 as the primary cell and notify the base station device 101 that band 1 will not be used. In this case, the terminal device 111 may discard the change instruction from the base station device 101 and start a reconnection process to resolve the discrepancy with the base station device 101.

[0038] Also, for example, it is assumed that the capability information from the terminal device 111 indicates that carrier aggregation of band 1 and band 18 is possible, and that uplink transmission is possible in both band 1 and band 18. Here, when the terminal device 111 is performing carrier aggregation using band 1 in the primary cell and band 18 in the secondary cell, the base station device 101 may instruct the terminal device 111 to change the primary cell to a cell of band 18 and change the secondary cell to a cell of band 1. In addition, at this time, the base station device 101 may instruct the terminal device 111 to change the primary cell to a cell of band 18 and not to use the cell of band 1 as a secondary cell.

[0039] In addition, in the determination of whether or not to change a cell not used for communication to a primary cell or a secondary cell, the capability information (UE Capability) of the terminal device 111 may be taken into consideration, as in the above example. For example, it is assumed that the terminal device 111 changes the primary cell to a cell of band 41 while performing carrier aggregation using band 1 and band 18. Here, when the capability information of the terminal device 111 indicates that carrier aggregation using both the combination of band 1 and band 41 and the combination of band 18 and band 41 is not possible, the base station device 101 may instruct the terminal device 111 not to continue using the cell of band 1 or band 18. In this case, when the capability information of the terminal device 111 indicates that carrier aggregation using both the combination of band 1 and band 41 and the combination of band 18 and band 41 is possible, the base station device 101 may instruct the terminal device 111 whether or not to continue using the cell of band 1 or band 18 as a secondary cell. Furthermore, when the terminal device 111 independently determines whether to change the primary cell to the cell of band 41, the terminal device 111 may determine, for example, from its own capability information, whether it can continue to use the cell of band 1 or band 18. Note that even if the terminal device 111 has the capability to continue to use the cells of band 1 and band 18 when the cell of band 41 is set as the primary cell, it may determine to use only one of the cell of band 1 and the cell of band 18, or to use neither of them, based on, for example, a power saving viewpoint. Then, the terminal device 111 may transmit a request signal based on the result of the determination to the base station device 101. Furthermore, the terminal device 111 may notify the base station device 101 of capability information (UE Capability) including information on whether it is possible to set in advance, before using a control parameter to be used when using a cell not used for communication as a primary cell or a secondary cell, before using the cell for communication.Similarly, the terminal device 111 may notify the base station device 101 of capability information including information on whether or not it is possible to set in advance the control parameters to be used when the cell used as a secondary cell is used as a primary cell before using it for communication, and information on whether or not it is possible to set in advance the control parameters to be used when the cell used as a primary cell is used as a secondary cell before using it for communication. In these cases, the base station device 101 may instruct only the terminal device that has notified capability information indicating that pre-configuration is possible to perform pre-configuration.

[0040] In the above example, the case where the secondary cell and the primary cell are replaced in carrier aggregation (CA) has been described, but the present invention is not limited to this. For example, when the terminal device 111 and the base station device 101 communicate with each other using Transmission and Reception Points (TRP or TRxP) having different physical cell identifiers (PCIs) in inter cell beam management, the above-mentioned method can be applied when replacing the primary TRP and the additional TRP. That is, the same method as the above-mentioned method can be used to improve the efficiency and control of the scheduling request control, timing advance control, beamforming control, HARQ control, CDRX control, and PHR control.

[0041] Also, in the case of replacing the Primary TRP and the Additional TRP in inter cell beam management, for one or more PCIs used as the Additional TRP, the control parameters required when used as the Primary TRP (for example, control information Common Search Space for receiving PDCCH related to broadcast information and paging) may be notified to the terminal device 111 in advance by layer 3 signaling or the like. Then, based on the wireless quality measurement result from the terminal device 111, the base station device 101 instructs the terminal device 111 to replace the Primary TRP and the Additional TRP by layer 2 or layer 1 signaling. Note that the terminal device 111 may determine that the Primary TRP and the Additional TRP should be replaced regardless of the instruction from the base station device 101, and transmit a request signal to the base station device 101 to request the replacement of the TRP based on the determination result. In addition, the base station device 101 may notify the terminal device 111 that the notification of the control parameters required when used as the Primary TRP is omitted if the control parameters are the same as the control parameters used when a TRP (or TRxP) having another PCI is used as the Primary TRP. In addition, the base station device 101 may notify only the change difference from the control parameters used when a TRP (or TRxP) having another PCI is used as the Primary TRP as the control parameters required when used as the Primary TRP.

[0042] (Device Configuration) A hardware configuration example of the base station device and the terminal device will be described with reference to FIG. 2. In one example, the base station device and the terminal device are configured to include a processor 201, a ROM 202, a RAM 203, a storage device 204, and a communication circuit 205. The processor 201 is a computer configured to include one or more processing circuits such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and executes the overall processing of the device and each of the above-mentioned processes by reading and executing a program stored in the ROM 202 or the storage device 204. The ROM 202 is a read-only memory that stores information such as programs and various parameters related to the processing executed by the base station device and the terminal device. The RAM 203 functions as a workspace when the processor 201 executes a program, and is a random access memory that stores temporary information. The storage device 204 is configured, for example, by a removable external storage device. The communication circuit 205 is configured, for example, by a circuit for wireless communication of 5G or its successor standard. In FIG. 2, one communication circuit 205 is illustrated, but for example, the base station device and the terminal device may have two or more communication circuits. In addition, for example, the base station device and the terminal device may have a common antenna with the wireless communication circuit for 5G and its successor standard. In addition, the base station device and the terminal device may have an antenna for 5G and an antenna for its successor standard separately. In addition, the terminal device may have a communication circuit for other wireless communication networks such as wireless LAN. In addition, the base station device and the terminal device may have separate communication circuits for each of a plurality of usable frequency bands, or may have a common communication circuit for at least a part of those frequency bands. In this embodiment, the terminal device has a plurality of communication circuits capable of communication in a common frequency band. In addition, the base station device may further have a wired communication circuit used when communicating with other base station devices and nodes of the core network.

[0043] FIG. 3 is a diagram showing an example of the functional configuration of a base station device. The base station device has, for example, a control parameter setting unit 301, a primary cell change determination unit 202, a primary cell change instruction notification unit 303, and a layer 2 / layer 1 control unit 304 as its functions. Note that FIG. 3 shows only functions particularly related to this embodiment, and various other functions that the base station device may have are omitted from the illustration. For example, the base station device naturally has other functions that base station devices of 5G and its successor standards generally have. In addition, the functional blocks in FIG. 3 are shown in schematic form, and each functional block may be integrated and realized, or may be further subdivided. In addition, each function in FIG. 3 may be realized, for example, by the processor 201 executing a program stored in the ROM 202 or the storage device 204, or may be realized, for example, by a processor existing inside the communication circuit 205 executing a predetermined software. Note that the details of the processing performed by each functional unit will not be described here in detail, and only the rough functions will be outlined.

[0044] When instructing the terminal device 111 to start carrier aggregation (CA), the control parameter setting unit 301 notifies the terminal device 111 of the control parameters to be used when performing communication with the cell to be added as a secondary cell as a secondary cell. Furthermore, the control parameter setting unit 301 also notifies the terminal device 111 of the control parameters to be used when performing communication with the cell as a primary cell. The control parameter setting unit 301 can transmit the above-mentioned control parameters to the terminal device 111 by, for example, layer 3 signaling such as RRC Reconfiguration. The primary cell change determination unit 302 requests the terminal device 111 to measure and report the radio qualities of the primary cell and the secondary cell, and acquires the measurement results of the radio qualities from the terminal device 111. The primary cell change determination unit 302 determines whether to change the cell used as a secondary cell to the primary cell based on, for example, the measurement results acquired from the terminal measurement 111. The primary cell change instruction notifying unit 303 instructs the terminal device 111 to change the cell used as a secondary cell to a primary cell according to the determination result of the primary cell change determining unit 302. Note that the primary cell change instruction notifying unit 303 transmits the instruction to the terminal device 111 by using, for example, layer 2 or layer 1 signaling.

[0045] The layer 2 / layer 1 control unit 304 determines whether or not the control parameters of layer 2 and layer 1 are changed with the change of the primary cell, and determines whether or not the state variables used for the control of layer 2 / layer 1 before the change of the primary cell need to be initialized, and whether or not the process started before the change needs to be continued. For example, when the layer 2 / layer 1 control unit 304 determines that the control parameters related to the beam control are not changed, it selects a beam suitable for after the change of the primary cell based on the measurement result of the beam received from the terminal device 111 before the change of the primary cell. In addition, in this case, the layer 2 / layer 1 control unit 304 may perform beam control by selecting an appropriate TCI setting from the activated TCI settings based on the activation / deactivation information of the TCI setting set in the terminal device 111 before the change of the primary cell. In addition, for example, in the HARQ control, when it determines that the control parameters are not changed after the change of the primary cell, the layer 2 / layer 1 control unit 304 may perform control so that the HARQ-ACK / NACK for the data transmitted to the terminal device 111 before the change of the primary cell is received after the change of the primary cell.

[0046] FIG. 4 is a diagram showing an example of the functional configuration of a terminal device. The terminal device has, for example, a control parameter acquisition unit 401, a primary cell change processing unit 402, and a layer 2 / layer 1 control unit 403 as its functions. Note that FIG. 4 shows only 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 of 5G and its successor standards generally have. In addition, the functional blocks in FIG. 4 are shown in a schematic manner, and each functional block may be integrated and realized, or may be further subdivided. In addition, each function in FIG. 4 may be realized, for example, by the processor 201 executing a program stored in the ROM 202 or the storage device 204, or may be realized, for example, by a processor existing inside the communication circuit 205 executing a predetermined software. Note that the details of the processing performed by each functional unit will not be described in detail here, and only the rough functions will be outlined.

[0047] The control parameter acquisition unit 401 acquires, from the connected base station device, control parameters when each cell is used as a primary cell and control parameters when each cell is used as a secondary cell. The control parameter acquisition unit 401 executes a setting process in the terminal device based on the acquired control parameters. For example, the control parameter acquisition unit 401 receives a setting message (for example, an RRC message such as an RRC Reconfiguration message) to acquire the control parameters included in the setting message. The primary cell change processing unit 402 performs a process of changing the cell currently used as a secondary cell to a primary cell. For example, the primary cell change processing unit 402 receives an instruction to change to a primary cell from the base station device 101 by layer 2 signaling such as downlink MAC CE or layer 1 signaling such as DCI.

[0048] The Layer 2 / Layer 1 control unit 403 determines whether or not the control parameters of Layer 2 and Layer 1 are changed due to the change of the primary cell, and determines whether or not the state variables used for the control of Layer 2 / Layer 1 before the change of the primary cell need to be initialized, and whether or not the process started before the change needs to be continued. For example, when the Layer 2 / Layer 1 control unit 403 determines that the control parameters of HARQ are not changed, it controls so that the data stored in the soft buffer of HARQ is not deleted but is stored. Also, when the Layer 2 / Layer 1 control unit 403 determines that the parameters of CDRX control are not changed, it controls so that timers related to CDRX control, such as onDurationTimer, inactivityTimer, drx-ShortCycleTimer, drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerUL, are not stopped but are continued.

[0049] (Processing flow) Next, an example of the flow of processes executed in the wireless communication system will be described with reference to Fig. 5. Since the details of each process described here are as described above, only the outline of the processes will be described here, and the details will not be described.

[0050] In FIG. 5, it is assumed that an initial connection is established between the terminal device 111 and the base station device 101. In this state, the base station device 101, for example, instructs the terminal device 111 to add a secondary cell, and sets control parameters for the cell as the communication setting of the terminal device 111 (S501). It is assumed that the terminal device 111 uses one or more cells provided by the base station device 101 with which the initial connection is established as a primary cell. In order to add a secondary cell, the base station device 101 notifies the terminal device 111 of control parameters for the terminal device 111 to communicate with the cell as a secondary cell. Based on this setting, the base station device 101 executes a setting process for adding the secondary cell based on the notified control parameters. In addition, the base station device 101 notifies the terminal device 111 of control parameters to be used when the terminal device 111 communicates with the cell as a primary cell. After the secondary cell is added, the terminal device 111 measures the radio quality of the primary cell and the secondary cell, and reports the measurement value to the base station device 101 (S502). Here, it is assumed that the base station device 101 has decided to change the cell used as the secondary cell to the primary cell based on the received measurement result. In this case, the base station device 101 instructs the terminal device 111 to change the cell used as the secondary cell to the primary cell based on the decision result (S503). Upon receiving the instruction, the terminal device 111 determines whether or not the control parameters of layer 2 and layer 1 are changed due to the change of the primary cell, determines whether or not the state variables used for layer 2 / layer 1 control before the change of the primary cell need to be initialized (S504), and determines whether or not the process started before the change needs to be continued (S505). For example, when it is determined that the control parameters of HARQ are not changed, the terminal device 111 decides to continue to hold the data held in the soft buffer of HARQ without deleting it.Also, when the terminal device 111 determines that the control parameters of CDRX and PHR are not changed, it decides to continue the timers related to CDRX control such as onDurationTimer and the timers related to PHR control such as phr-PeriodicTimer without stopping them. In another example, when the terminal device 111 determines that the control parameters related to beam control are not changed, it may decide to continue to hold the Activation / Deactivation information of the TCI setting that was set before the change of the primary cell without deleting it. After that, the terminal device 111 transmits a response to the instruction to change the primary cell to the base station device 101 (S506).

[0051] As described above, according to this embodiment, in DC or CA, it is possible to switch between primary and secondary cells at a higher speed. Therefore, it is possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote sustainable industrialization, and promote innovation."

[0052] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

Claims

1. A terminal device that communicates with a base station device using a primary cell and a secondary cell by carrier aggregation, A first receiving means for receiving, with respect to one or more cells, both a parameter required when using the one or more cells as a primary cell and a parameter required when using the one or more cells as a secondary cell; A change means for changing a first cell of the one or more cells to a primary cell when the first cell is used as a secondary cell; a second receiving means for receiving, from the base station device, information on whether or not a second cell that is no longer a primary cell after the first cell is changed to a primary cell is to be used as a secondary cell; A terminal device comprising:

2. a determination means for determining whether or not a control parameter of a connected discontinuous reception (CDRX) of the second cell is the same when the second cell is used as a primary cell and when the second cell is used as a secondary cell, when the second receiving means receives an instruction to continue using the second cell as a secondary cell; a timer control means for causing a timer related to an active CDRX control to continue without stopping when the second cell is changed to a secondary cell when the determination means determines that the CDRX control parameters are the same; 2. The terminal device according to claim 1, further comprising:

3. a determination means for determining, when an instruction to continue using the second cell as a secondary cell is received in the second receiving means, whether or not a parameter related to beam control of the second cell is the same when the second cell is used as a primary cell and when the second cell is used as a secondary cell; a beam recovery processing continuation means for continuing the beam recovery processing without stopping the beam recovery processing when the second cell is changed to a secondary cell, when the determination means determines that the parameters related to beam control are the same and when the beam recovery processing was started when the second cell was used as a primary cell; 2. The terminal device according to claim 1, further comprising:

4. A determination means for determining whether a setting related to HARQ of the first cell is the same when the first cell is used as a primary cell and when the first cell is used as a secondary cell; a buffer control means for holding data stored in a soft buffer of a HARQ of the terminal device without deleting the data when the determination means determines that the settings related to a composite automatic repeat request (HARQ) are the same; 2. The terminal device according to claim 1, further comprising:

5. The first receiving means receives parameters by an RRC Reconfiguration message; 2. The terminal device according to claim 1, wherein, when changing the first cell to a primary cell, the change unit acquires, from the base station device, a value of a Radio Network Temporary Identifier (RNTI) to be used after the change of the primary cell by a medium access control element (MAC CE) or downlink control information (DCI).

6. The first receiving means receives an RRC Reconfiguration message including a value of a Radio Network Temporary Identifier (RNTI) to be used after changing the primary cell to each of the one or more cells as a primary cell, as a parameter required when using the one or more cells as a primary cell; The change unit changes the first cell to a primary cell in response to receiving an instruction by a medium access control element (MAC CE) or downlink control information (DCI) from the base station device; 2. The terminal device according to claim 1, characterized in that after the first cell is changed to a primary cell, the value of the RNTI received by the first receiving means for the first cell is used.

7. The terminal device according to claim 1 , wherein the change unit executes random access control for the primary cell when changing the first cell to the primary cell.

8. 8. The terminal device according to claim 7, further comprising a timer control means for determining whether the random access control is successful or unsuccessful.

9. The timer control means a start means for starting a timer at a timing when the change is instructed by the change means; a timer stopping means for stopping the timer when the random access control is successful; A timer expiration determination means for determining whether or not a started timer expires; The present invention relates to a method for manufacturing a computer-implemented ... The terminal device according to claim 8, further comprising a determination means for determining success or failure of primary cell switching based on a result of determination of success or failure of random access control by the timer control means.

10. The terminal device according to claim 9, characterized in that, when the timer expiration determination means determines that the timer has expired without successful random access, the determination means determines that switching of the primary cell has failed.

11. 11. The terminal device according to claim 10, further comprising a reconnection process initiating means for initiating a reconnection process in response to the determination by the determination means that switching to the primary cell has failed.

12. A control method executed by a terminal device that communicates with a base station device using a primary cell and a secondary cell by carrier aggregation, comprising: receiving, for one or more cells, both parameters required when using the one or more cells as a primary cell and parameters required when using the one or more cells as a secondary cell; changing a first cell of the one or more cells to a primary cell when the first cell is used as a secondary cell; receiving, from a base station device, information regarding whether or not a second cell that is no longer a primary cell after the first cell is changed to a primary cell is to be continued as a secondary cell; A control method comprising:

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