Terminal device for efficiently changing connection destination cell

Abstract

A base station device omits the setting of a required parameter when changing a cell serving as a secondary cell to a primary cell by previously setting, in a terminal device 111, a control parameter used when performing communication in which the cell serving as the secondary cell is used as the primary cell.

Description

Technical Field

[0001] The present invention relates to a technique for changing a cell of a connection destination in a cellular communication system. Background Art

[0002] The cellular communication standard of 3GPP (3rd Generation Partnership Project (registered trademark)) stipulates DC (Dual Connectivity) and CA (Carrier Aggregation) that enable terminal devices to use a plurality of CCs (Component Carriers) simultaneously. Summary of the invention

[0003] Problem that the invention aims to solve

[0004] It is assumed that, in DC and CA, the cell to which the terminal device is connected is switched dynamically. In particular, when the communication environment changes frequently and significantly due to the frequency band used for communication being shifted to a higher frequency band, it is assumed that such switching between cells of the connection destination occurs frequently. Therefore, it is very important to perform switching between cells of the connection destination at a high speed.

[0005] The present invention provides a technology for enabling a terminal device connected to a plurality of cells in parallel to perform handover between cells of connection destination at high speed.

[0006] Means used to solve problems

[0007] According to one aspect of the present invention, a terminal device communicates with a base station device using a primary cell and a secondary cell through carrier aggregation, and is characterized in that the terminal device has: a first receiving unit, which receives parameters required for using one or more cells as a primary cell, respectively, with respect to one or more cells; a second receiving unit, which receives parameters required for using the one or more cells as secondary cells, respectively; a changing unit, which changes a first cell among the one or more cells to a primary cell when the first cell is used as a secondary cell; and a third receiving unit, which receives information from the base station device regarding whether a second cell that becomes non-primary cell after the first cell is changed to a primary cell will continue to be used as a secondary cell.

[0008] Effects of the Invention

[0009] According to the present invention, a terminal device connected to a plurality of cells in parallel can perform handover between cells of connection destination at high speed.

[0010] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings. Note that throughout the drawings, the same reference numerals represent the same or similar components. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0012] Figure 1 is a diagram showing a configuration example of a wireless communication network.

[0013] Figure 2 is a diagram showing an exemplary hardware configuration of the apparatus.

[0014] Figure 3 is a diagram showing an exemplary functional configuration of a base station apparatus.

[0015] Figure 4 is a diagram showing an exemplary functional configuration of a terminal device.

[0016] Figure 5 is a diagram showing an example of the flow of a process performed in a wireless communication network. DETAILED DESCRIPTION

[0017] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention, and are not intended to limit the invention of the combination of all features that need to be described in the embodiments. Two or more of the multiple features described in the embodiments can be combined arbitrarily. In addition, the same reference numerals are given to the same or similar configurations, and their redundant descriptions are omitted.

[0018] (System Configuration)

[0019] Figure 1 An example of a configuration of a wireless communication system according to an embodiment of the present invention is shown. For example, the wireless communication system complies with the LTE (Long Term Evolution) or 5G (Fifth Generation) cellular communication standard or a cellular communication standard following them, and is configured by including a base station device 101 and a terminal device 111. Note that here, for ease of description, a small number of base station devices and terminal devices are shown, but, of course, a large number of base station devices or terminal devices may also exist.

[0020] In an embodiment of the present invention, the terminal device 111 is configured to be able to communicate with the base station device 101 in parallel using multiple CCs (component carriers) simultaneously through DC (dual connectivity) or CA (carrier aggregation). Note that Figure 1An example in which the terminal device 111 is connected to one base station device 101 is shown, but the terminal device 111 may also be connected to a plurality of base station devices in parallel. In addition, "CC" in the following description may be replaced with "cell". Multiple CCs may be configured in the same frequency band, but in an embodiment of the present invention, communication using multiple CCs corresponding to multiple frequency bands is performed. In an embodiment of the present invention, the terminal device 111 is configured to be able to use only some combinations of multiple different frequency bands, rather than all combinations of multiple frequency bands. For example, the terminal device 111 may use a combination of the first frequency band and the second frequency band and a combination of the first frequency band and the third frequency band, but may not use a combination of the second frequency band and the third frequency band and a combination of the first frequency band, the second frequency band and the third frequency band. Note that, for example, the first frequency band, the second frequency band, and the third frequency band may be, for example, frequency band 1, frequency band 18, and frequency band 41 specified in the standard, respectively. In addition, although three frequency bands will be described here, additional frequency bands such as a fourth frequency band (e.g., frequency band 42) may be prepared.

[0021] In an embodiment of the present invention, for example, the base station device 101 communicates with the terminal device through CA (carrier aggregation), wherein a CC (component carrier) in a first frequency band is designated as a primary cell, and a CC (component carrier) in a second frequency band is designated 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 in the same wireless system. In addition, a configuration may be adopted in which the primary cell is configured as an LTE cell and the secondary cell is configured as a 5G cell, or a configuration may be adopted in which the primary cell is configured as a 5G cell and the secondary cell is configured as a cell specified based on LTE or a subsequent next-generation standard. That is, the primary cell and the secondary cell may also be configured as cells of different wireless systems.

[0022] In an embodiment of the present invention, a situation in which a primary cell and a secondary cell are switched is considered. For such a switch, two handover indications need to be given, for changing the primary cell currently in use to a new primary cell, and for changing the secondary cell currently in use to a new secondary cell. These indications are given using RRC (radio resource control) signaling of layer 3. That is, for example, the base station device 101 uses an RRC message to instruct the terminal device 111 to change the CC (component carrier) in the second frequency band to the primary cell, and to change the CC (component carrier) in the first frequency band to the secondary cell. At this time, usually, when receiving a change indication from the base station device 101, the terminal device 111 initializes the state variables of layer 2 and layer 1 for controlling each of the primary cell and the secondary cell. Then, the terminal device 111 resets the control parameters of layer 2 and layer 1 based on the changed cell. In addition, at this time, if a control process of at least one of layer 2 and layer 1 is being performed, the terminal device 111 stops the process.

[0023] In general, examples of state variables for controlling layer 2 and layer 1 to be initialized include a counter BFI_COUNTER for beam failure detection, an SR_COUNTER for controlling scheduling requests, and an NTA for timing advance control to achieve uplink transmission timing correction.

[0024] In the case where beamforming is applied, the state variables 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 TCI (transmit configuration indication) settings to control the transmit beam (Tx beam) and receive beam (Rx beam) of each signal / channel. For example, the base station device 101 determines the transmit beam used for downlink transmission on the PDSCH (Physical Downlink Shared Channel) based on the measurement result of the reference signal notified by the terminal device 111. Then, before using the PDSCH for data transmission, the base station device 101 uses the DCI (downlink control information) contained in the PDCCH (Physical Downlink Control Channel) to give the terminal device 111 a TCI setting for the terminal device 111 to receive the signal sent using the determined transmit beam. In addition, the base station device 101 determines the transmit beam used for uplink transmission on the PUSCH (Physical Uplink Shared Channel) based on the measurement result of the reference signal sent by the terminal device 111. Then, when scheduling the PUSCH, the base station apparatus 101 uses the DCI (Downlink Control Information) included in the PDCCH (Physical Downlink Control Channel) to give the terminal apparatus 111 a TCI setting for transmitting a signal using the determined transmission beam. Note that, for example, in this beam control, the base station apparatus 111 can use layer 3 signaling to notify the terminal apparatus 111 of the TCI setting that the terminal apparatus 101 can use, and then activate some TCI settings and select an appropriate TCI from the activated TCI settings. The base station apparatus 111 uses MAC CE (Media Access Control / Control Element) to instruct the terminal apparatus 101 to activate or deactivate each TCI setting. Then, the base station apparatus 101 can use the above-mentioned DCI to notify the terminal apparatus 111 of the TCI setting corresponding to the beam to be used from the activated TCI settings. In addition, as another method for beam control, there is also a technology using an SRS resource indicator. Through this technology, the base station device 101 determines the SRS-RI (SRS resource indicator) based on the sounding reference signal sent by the terminal device 111, and notifies the terminal device 111 of the determined SRS-RI. The terminal device 111 can determine the precoder for the transmission beam based on information such as the SRS resource indicator, codebook, and number of antenna ports specified by the base station device 101. The terminal device 111 uses the determined precoder to generate a transmission beam for uplink transmission on the PUSCH (Physical Uplink Shared Channel). In the case where the primary cell or the secondary cell is changed, information about activation / deactivation of the TCI setting, information about the TCI setting for sending and receiving beams on channels such as PDSCH and PUSCH, and information about the SRS-RI setting set before the change are initialized at the time of the change.

[0025] In addition, also when CA (carrier aggregation) is performed, HARQ (Hybrid Automatic Repeat Request) control is performed in Layer 2 and Layer 1 in the same manner as communication using a single carrier. As an example, the terminal device 111 uses PUCCH to notify the base station device 101 of HARQ-ACK / NACK, which indicates whether the PDSCH data is successfully decoded. At this time, in a case where an indication of changing the primary cell is given after the primary cell receives the PDSCH data and before sending the HARQ-ACK / NACK, the terminal device 111 can suspend the scheduled transmission of HARQ-ACK / NACK. In addition, similar to the above-mentioned case of the primary cell, when the secondary cell is changed in a case where an indication of changing the secondary cell is given after the secondary cell receives the PDSCH data and before sending the HARQ-ACK / NACK, the terminal device 111 can suspend the scheduled transmission of HARQ-ACK / NACK. In addition, in HARQ control, if the decoding of the received data fails (the decoded data contains an error), the terminal device 111 saves the data in a memory area called a "soft buffer" so that the error can be corrected later. Then, the terminal device 111 combines the data newly transmitted from the base station device 101 with the saved data and decodes the combined data. Therefore, highly error-resistant communication can be performed. Usually, when an instruction to change the primary cell or the secondary cell is given, the terminal device 111 erases the data saved in the soft buffer to correct the error.

[0026] In addition, the control of layer 2 and layer 1 may include CDRX (connected discontinuous reception) control. As an example, when the primary cell is changed to a secondary cell, the terminal device 111 stops the timers related to the CDRX control, such as onDurationTimer (a timer for controlling the period of time for maintaining the DRX-ON state), drx-inactivityTimer (a DRXinactivity timer started after receiving the PDCCH to maintain the DRX-ON state for a specific period of time), DRX ShortCycleTimer (a timer for specifying the duration of 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).

[0027] In addition, the control of layer 2 and layer 1 may include PHR (power headroom report) control. As an example, when the primary cell is changed to the secondary cell, the terminal device 111 stops the timer related to the PHR control, such as phr-PeriodicTimer (a timer for controlling the PHR reporting period) and phr-ProhibitTimer (a timer for controlling the PHR reporting prohibition period).

[0028] On the other hand, when a cell that has been used as 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 the PHY (physical) layer of layer 2 and layer 1 for controlling the primary cell can continue to be used to control the secondary cell after the change. For this reason, it can be said that when the control parameters of layer 2 and layer 1 are changed, it is necessary to initialize the state variables used to control layer 2 and layer 1 before changing the primary cell to the secondary cell, but when the control parameters are not changed, the state variables do not need to be initialized. In addition, also in the case where the cell that has been used as a secondary cell has been changed to the primary cell, similarly, the MAC entity and the PHY layer of layer 2 and layer 1 for controlling the secondary cell can continue to be used to control the primary cell after the change. For this reason, also in this case, it can be said that when the control parameters of layer 2 and layer 1 are not changed, it is not necessary to initialize the state variables that have been used to control layer 2 and layer 1.

[0029] In an embodiment of the present invention, in view of the above situation, when the terminal device 111 switches between the primary cell and the secondary cell, the state variables for controlling layer 2 and layer 1 can be maintained without initializing the state variables as needed. As an example, when receiving an indication 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 to change the control parameters of at least one of layer 2 and layer 1. If it is determined that the control parameters are to be changed, the terminal device 111 initializes the state variables for controlling layer 2 and layer 1 as in the conventional case. On the other hand, if it is determined that the control parameters are not to be changed, the terminal device 111 does not initialize the state variables that have been used to control layer 2 and layer 1. In addition, if it is determined that the control parameters are to be changed, the terminal device 111 ends the processing that has been started but not completed before receiving the cell change indication as in the conventional case. On the other hand, if it is determined that the control parameters are not to be changed, the terminal device 111 continues the processing that has been started before receiving the cell change indication. In addition, when an indication is received to change the cell used as the secondary cell to the primary cell, the terminal device 111 can perform similar processing. That is, the terminal device 111 determines whether to change the control parameters of at least one of layer 2 and layer 1, determines whether to initialize the state variables that have been used to control layer 2 and layer 1, and determines whether to continue the processing that has been started before receiving the cell change indication. Note that processing such as determining whether to change the control parameters may be performed only on some of the above control items. A configuration may also be adopted in which, for example, the terminal device 111 determines whether to change the control parameters, initialize the state variables, and continue the processing only for HARQ, and does not perform such determinations for beamforming, PHR, etc. In addition, the terminal device 111 may make a determination for each control item separately, and for each control item, determine whether the control parameters have been changed, etc., and determine individually whether to initialize the state variables and continue the processing based on the separately performed determinations. In addition, when the control parameters are not changed, the terminal device 111 may notify the base station device 101 of the UE capability (capability information) indicating whether the state variables can be initialized and the processing can be continued. In this case, base station apparatus 101 can instruct terminal apparatus 111 whether to initialize state variables and continue processing according to capability information notified by terminal apparatus 111. Note that base station apparatus 101 may be notified of capability information in which appropriate information is set for each control item.

[0030] After receiving an indication to change the secondary cell or the primary cell, if it is determined that the parameters related to beam failure detection and beam recovery have not been changed, the terminal device 111 maintains the state variables related to beam failure detection and beam recovery without initializing them. In addition, the terminal device 111 can continue the processing related to the beam that has been started before receiving the cell change indication. In the case where beam failure detection has been detected before receiving the cell change indication and the beam failure detection timer has been started, for example, when receiving the change indication, the terminal device 111 maintains the beam failure detection counter BFI_COUNTER without initializing it, and continues the beam failure detection timer without stopping it. In addition, in the case where the beam recovery processing has been started before receiving the cell change indication, when receiving the change indication, the terminal device 110 continues the processing without stopping it. For example, in the case where a cell change indication is received after sending a RACH preamble code for beam recovery, the terminal device 111 continues the timer ra-ResponseWindow for controlling the monitoring period of the RA response from the base station device 101 without stopping the timer. In addition, in the case where a cell change indication is received after a MAC CE (msg3) for beam recovery has been sent, the terminal device 111 continues the ra-ContentionResolutionTimer (contention resolution timer) without stopping it. Therefore, the terminal device 110 can avoid the situation where beam failure detection or beam recovery is suspended when the secondary cell or the primary cell is changed, and perform beam control more efficiently. In addition, similar to beam failure and recovery, the processing efficiency of scheduling requests can also be improved. That is, in the case where a scheduling request is sent before a cell change indication is received, when the change indication is received, the terminal device 111 maintains the counter SR_COUNTER of the scheduling request without initializing it, and continues to run the sr-ProhibitTimer (scheduling request prohibition timer) without stopping it. Therefore, the scheduling request prohibition processing continues without being suspended by the indication of changing the secondary cell or the primary cell, and the processing efficiency can be improved. In addition, if it is determined that the parameters of the timing advance control for realizing the uplink transmission timing correction have not been changed, the terminal device 111 maintains the timing value NTA without initializing it. In addition, the terminal device 111 can maintain the TAT (time alignment timer) that has been started before receiving the cell change indication without stopping it until the timer expires. Therefore, when receiving the indication to change the secondary cell to the primary cell, the terminal device 111 maintains the timing value NTA, so the random access procedure for correcting the uplink transmission timing again can be omitted.Note that after receiving an instruction to change the primary cell or the secondary cell from the base station device 111 , the terminal device 111 may initialize the timer value NTA related to the cell not used for communication and stop the TAT (time alignment timer).

[0031] In a case where beamforming is applied and it is determined not to change the control parameters for beamforming, the processing speed of switching between cells can be improved. In one example, the terminal device 111 can save the activation / deactivation information about the TCI setting received from the base station device 101 before receiving the indication to change the primary cell to the secondary cell, the TCI setting for sending and receiving beams using channels such as PDSCH and PUSCH, the information about the beam control related to the SRS-RI setting, and the state variables without initializing them. In this case, after changing the primary cell to the secondary cell, the base station device 101 does not need to select the best beam again based on the measurement result of the reference signal from the terminal device 111, and notify the terminal device 111 of the information used for beam control. For this reason, data transmission / reception can be started between the base station device 101 and the terminal device 111 at an earlier stage using appropriate transmission beams and reception beams.

[0032] In the case where it is determined not to change the HARQ control parameters and, for example, an indication of changing the cell to a secondary cell is received before sending HARQ-ACK / NACK as a decoding result after receiving PDSCH, the terminal device 111 may send HARQ-ACK / NACK after the cell has been changed to the secondary cell. In this case, examples of HARQ control parameters may include a parameter nrofHARQ-ProcessesForPDSCH for setting the number of HARQ processes for PDSCH, a parameter downlinkHARQ-FeedbackDisabled for disabling DL HARQ feedback, and a parameter harq-ProcessNumberSizeDCI-1-2 for setting the number of bits of the HARQ process number included in DCI format 1_2. Conventionally, in the case where the primary cell has been changed to the secondary cell, the terminal device 111 cannot use the changed secondary cell to send HARQ-ACK / NACK, so the base station device 101 resends the PDSCH. On the contrary, by sending HARQ-ACK / NACK using the changed secondary cell by the terminal device 111 as described above, unnecessary retransmission of PDSCH can be suppressed and communication efficiency can be improved. In addition, at this time, the terminal device 111 can delay the start of the process for changing the main cell to the secondary cell until after the HARQ-ACK / NACK has been sent. In addition, in the case where an indication is received to change the main cell to the secondary cell, and it is determined that the control parameters related to HARQ are not changed, the terminal device 111 continues to save the data saved in the HARQ soft buffer without erasing it. Therefore, the data received before the cell change indication and the data received after the cell change indication can be combined, and the combined data can be decoded, thereby further improving the efficiency of the receiving process.

[0033] In addition, if it is determined that the CDRX control parameters are not changed, the terminal device 111 can continue the timers related to the CDRX control, such as onDurationTimer, inactivityTimer, drx-ShortCycleTimer, drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerUL, without stopping them. Therefore, it is possible to avoid the situation where the power of the terminal device 111 is unnecessarily turned on when the cell is changed to a secondary cell, and improve the efficiency of the CDRX control. When the drx-ShortCycleTimer is running, in the case where the PDCCH has not yet been sent from the base station device 101, the terminal device 111 can transition to LongDRX faster by continuing the drx-ShortCycleTimer. Therefore, power saving of the terminal device 111 can be further achieved.

[0034] In addition, if it is determined that the PHR control parameters are not changed, the terminal device 111 may continue the timers related to the PHR control, such as the phr-PeriodicTimer and the phr-ProhibitTimer, without stopping them. When the phr-PeriodicTimer is stopped, the terminal device 111 starts the phr-PeriodicTimer at the first uplink transmission after the primary cell has been changed to the secondary cell, thereby delaying the PHR transmission timing. In contrast, compared with the case where the phr-PeriodicTimer is stopped, the terminal device 111 can appropriately advance the PHR transmission timing by continuing the phr-PeriodicTimer. As a result, the uplink transmission power of the terminal device 111 can be controlled more accurately. In addition, when the phr-ProhibitTimer is stopped, wasteful PHR transmission may occur due to a one-time reset of the PHR transmission prohibition period. In contrast, the terminal device 111 can suppress the occurrence of such wasteful PHR transmission by continuing the phr-ProhibitTimer.

[0035] Note that the above describes detailed control related to beamforming control, HARQ control, CDRX control, and PHR control when the terminal device 111 receives an instruction to change the cell being used as the primary cell to the secondary cell, but similar control can also be performed after receiving an instruction to change the cell being used as the secondary cell to the primary cell. Therefore, the terminal device 111 can improve the efficiency of control related to scheduling request control, timing advance control, beamforming control, HARQ control, CDRX control, and PHR control.

[0036] In addition, when instructing the terminal device 111 to start CA (carrier aggregation), the base station device 101 uses layer 3 signaling such as RRC reconfiguration to notify the control parameters of the cell added as the secondary cell, which are used when the cell is used as the secondary cell for communication. In addition, at this time, the base station device 101 can notify the terminal device 111 of the control parameters used when the cell is used as the primary cell for communication. That is, the base station device 101 can notify the terminal device 111 in advance of the control parameters to be used when the cell to be added as the secondary cell is changed to the primary cell and then communicates. Therefore, when the terminal device 111 changes the cell from the secondary cell to the primary cell, the setting of the necessary parameters from the base station device 101 can be omitted. Therefore, the message size of the change indication sent from the base station device 101 to the terminal device 111 can be reduced. In addition, when the same control parameters are used in the case where the cell is used as the secondary cell and in the case where the cell is used as the primary cell, a message containing information indicating that the control parameters of one of the above cases are omitted and in which the control parameters are omitted is sent, so the message size can be reduced.

[0037] In addition, the control parameters to be used in the case where the cell added as the secondary cell is changed to the primary cell and then communicated are notified to the terminal device 111 in advance, so that the base station device 101 can use layer 2 or layer 1 signaling instead of layer 3 signaling to give an indication of changing the cell being used as the secondary cell to the primary cell. Therefore, the processing for changing the secondary cell to the primary cell can be performed at a higher speed in the terminal device 111. In addition, it is sufficient to give a change indication using the primary cell or the secondary cell. For example, when the primary cell is in DRX mode or beam recovery is being performed, so it is difficult to send or receive a change indication, the base station device 101 can reduce the delay of changing the secondary cell to the primary cell by sending a change indication to the terminal device 111 using the secondary cell. In addition, the terminal device 111 can use layer 2 or layer 1 signaling such as uplink MAC CE or UCI (uplink control information) to send a report on the completion of the processing for changing the secondary cell to the new primary cell to the base station device 101. Note that, for example, the report can be sent to the base station device 101 using the cell newly used as the primary cell. In addition to the above-mentioned change indication, the base station device 101 may also notify the terminal device 111 of information indicating whether the cell to be changed from the primary cell continues to be used as a secondary cell. The terminal device 111 may change the cell that is no longer the primary cell to the secondary cell according to the indication from the base station device 101, or may perform processing for making the cell unnecessary.

[0038] In addition, after the control parameters used when the cell being used as a secondary cell is changed to a primary cell and then communicated are set in the terminal device 111, the base station device 101 can request the terminal device 111 to measure and report the wireless quality of the primary cell and the secondary cell, and obtain the measurement results. The base station device 101 can give an instruction to change the cell being used as a secondary cell to the primary cell based on the obtained measurement results. Note that when setting the control parameters, Layer 3 messages can be used to set whether it is based on periodic reporting measurement results or event reporting measurement results, the period in which it is based on periodic reporting measurement results, and the event type and threshold in which it is based on event reporting measurement results. In addition, before setting the control parameters used when communicating using the cell as the primary cell, in a case where the settings for wireless quality measurement have been set in the terminal device 111, the base station device 101 can obtain the measurement results based on the settings. Note that, as an example, the radio quality obtained by the base station device 101 here may be CSI (channel state information)-RS (reference signal), RSSI (received signal strength indicator) of SS (synchronization signal), RSRP (reference signal received power), RSRQ (reference signal received quality), SNR (signal to noise ratio), SINR (signal to interference plus noise ratio), or a counter value BFI_COUNTER for beam failure detection. In addition, the start and end of the radio quality measurement that has been set using the above-mentioned layer 3 message can be indicated using layer 1 or layer 2 signaling. Therefore, the execution and non-execution of the measurement for each cell are dynamically switched, so the efficiency of the measurement can be improved. Here, for example, in the case where MeasConfig (measurement configuration) is configured by MeasObject (measurement object), ReportConfig (report configuration) and MeasId (measurement identifier), a measurement identifier indicating the measurement setting (starting or stopping the measurement according to its needs) can be specified using layer 2 signaling such as downlink MAC CE or layer 1 signaling such as DCI.

[0039] In addition, when changing the secondary cell to the primary cell, the terminal device 111 can determine that the change is required (regardless of the instruction from the base station device 101) and request the base station device 101 to make the change. In this case, the base station device 101 notifies the terminal device 111 in advance of the conditions and benchmarks for changing the cell being used as the secondary cell to the primary cell. At this time, the change conditions provided to the terminal device 111 may include, for example, that the wireless quality of the secondary cell is greater than or equal to a specific threshold, and that the wireless quality of the primary cell is less than or equal to the specific threshold. Note that the terminal device 111 can set the conditions and benchmarks using layer 3 signaling and control parameters used when communicating using the cell as the primary cell. If it is determined that the given condition is met, the terminal device 111 requests the base station device 101 to change the cell being used as the secondary cell to the primary cell. Then, the base station device 101 can determine whether the request from the terminal device 111 is met, and return a response containing the determination result to the terminal device 111. At this time, the terminal device 111 may use layer 2 signaling such as uplink MAC CE or layer 1 signaling such as UCI to send a request to change the cell to the primary cell to the base station device 101. The base station device 101 may use layer 2 signaling such as downlink MAC CE or layer 1 signaling such as DCI to send a response to the request to the terminal device 111.

[0040] The control parameters used when the terminal device 111 uses the primary cell for communication include (RLF) radio link failure control, low mobility evaluation control, good service cell evaluation RLM (power saving control for radio link monitoring), random access control, etc. The radio link failure control is a control performed by the terminal device 111 when it detects an out-of-sync state during communication and performs a process of reconnecting with the base station device 101 when necessary, and the control parameters used for the control include a timer value t310 for controlling the counting period of the number of consecutive occurrences of the out-of-sync state, n310 for specifying the number of consecutive occurrences of the out-of-sync state, and n311 for specifying the number of consecutive occurrences of the in-sync state. When the out-of-sync state occurs n310 times in a continuous manner, the terminal device 111 starts t310, and after that, if t310 expires without detecting the in-sync state n311 times in a continuous manner, the terminal device 111 determines that a radio link failure has occurred and starts the reconnection process. The low mobility evaluation control is a control performed by the terminal device 111 to determine whether the terminal device 111 is in a low mobility state, and if it is determined that the terminal device 110 is in a low mobility mode, the measurement frequency of the wireless quality measurement of the serving cell is reduced to achieve power saving. The control parameters of the low mobility evaluation control include s-SearchDeltaP-Connected and t-SearchDeltaP-Connected. The terminal device 111 determines whether the terminal device 111 is in a low mobility state by determining whether the fluctuation range of the measured wireless quality is within s-SearchDeltaP-Connected within a specific time period indicated by t-SearchDeltaP-Connected. If the wireless quality of the serving cell is good, the power saving control for wireless link monitoring is a control for extending the cycle of wireless link monitoring, reducing the measurement frequency and suppressing power consumption. The control parameters for the power saving control for wireless link monitoring include standards for performing the same function and information for specifying conditions. In the case where communication is performed through CA (carrier aggregation), uplink transmission is performed only in the primary cell. For this reason, random access control is control specific to the primary cell, and control parameters for random access control may be included in control parameters used when communicating using the cell as the primary cell.

[0041] In addition, a timer (e.g., t304) used when switching a cell to a primary cell may also be included in the control parameters used when communicating using the cell as a primary cell. The terminal device 111 starts timer t304 at the moment when an indication of switching the cell to a primary cell is given using layer 2 or layer 1 signaling, and stops t304 thereafter when random access is successfully completed. In addition, if t304 has expired without successful random access, the terminal device 111 may determine that switching the cell to the primary cell has failed and start reconnection processing. In addition, in a case where random access is not performed, the terminal device 111 may stop t304 based on the completion of sending a response signal to the base station device 101 in response to an indication of switching the cell to the primary cell.

[0042] In addition, the RNTI (Radio Network Temporary Identifier) ​​used when the secondary cell is changed to the primary cell may also be included in the control parameters used when the cell is used as the primary cell for communication. RNTI is an identifier provided to the base station device 101 for distinguishing multiple terminal devices connected thereto. The terminal device 111 determines whether the received signal is for the terminal device 111 itself by comparing the RNTI contained in the received signal with the RNTI of the terminal device 111 itself. Before changing the cell to the primary cell, the RNTI may be notified from the base station device 101 to the terminal device 111 using layer 3 signaling when setting the control parameters, or the RNTI may be notified from the base station device 101 to the terminal device 111 using layer 2 or layer 1 signaling when changing the cell to the primary cell.

[0043] In addition, the base station apparatus 101 may notify the terminal apparatus 111 (with which the base station apparatus 101 is communicating) connected to the base station apparatus 101 of the control parameters used when communicating using a cell that is not used for communication as a secondary cell and the control parameters used when communicating using the cell as a primary cell, for example, by using layer 3 signaling such as RRC reconfiguration. Note that a configuration may also be adopted in which only the control parameters used when communicating using a cell as a secondary cell are notified to the terminal apparatus 111, or only the control parameters used when communicating using the cell as a primary cell are notified to the terminal apparatus 111. In this case, after the control parameters are notified, the base station apparatus 101 may send an indication to change the primary cell to the cell or an indication to change the secondary cell to the cell to the terminal apparatus 111 using layer 2 or layer 1 signaling based on the radio quality measurement result notified from the terminal apparatus 111. In addition, also in this case, the terminal apparatus 111 may determine that it is to request to change the primary cell (regardless of the indication from the base station apparatus 101), and send a request signal to the base station apparatus 101. At this time, the base station device 101 may notify the terminal device 111 in advance of the conditions and benchmarks for when the cell is used as a primary cell or a secondary cell. The conditions and benchmarks are notified from the base station device 101 to the terminal device 111 using layer 3 signaling, as well as the control parameters to be used when the terminal device 111 uses the cell as a primary cell or a secondary cell for communication. When a given condition is met, the terminal device 111 sends a request message to the base station device 101, thereby using the cell as a primary cell or a secondary cell. The base station device 101 can then determine whether the request from the terminal device 111 is met, and return a response containing the determination result to the terminal device 111. At this time, the terminal device 111 can send a request to the base station device 101 to change the cell to a primary cell using layer 2 signaling such as an uplink MAC CE or layer 1 signaling such as UCI. In addition, the base station device 101 can send a response to the change request to the terminal device 111 using layer 2 signaling such as a downlink MAC CE or layer 1 signaling such as DCI. In addition, a control parameter used when a cell not used for communication is used as a secondary cell for communication, and a notification of a management parameter used when the cell is used as a primary cell for communication may be included in the layer 3 message indicating the start of communication. In this case, in addition to the control parameters used when one or more cells are used for communication as secondary cells and the control parameters used when one or more cells are used for communication as primary cells, information for identifying the primary cell and secondary cell used for communication when communication is started and the cell not used for communication may be included. In addition, at this time, in the case where the wireless measurement setting is indicated at the same time, information for identifying the measurement setting for setting the measurement object and the measurement setting for setting the non-measurement object at the start of communication may be included.Furthermore, when the control parameters of a plurality of cells are notified, the control parameters of the plurality of cells are notified as a difference between a set value and a control parameter of another cell, so that the data size of the control parameters can be reduced.

[0044] In addition, the terminal device 111 erases the control parameters to be used when the cell is used as a primary cell or a secondary cell according to the instruction from the base station device 101. The base station device 101 may send an instruction to erase the control parameters to the terminal device 111 using layer 3, layer 2, or layer 1 signaling. In addition, when setting the control parameters, the base station device 101 may also notify the terminal device 111 of the conditions under which the control parameters are to be erased. The terminal device 111 may erase the control parameters not only when receiving the instruction from the base station device 101 or satisfying the notified conditions, but also when, for example, communication is ended to transition to the standby state.

[0045] In addition, according to the terminal device 111 establishing a connection with a base station device that provides a communication service in a predetermined area (due to 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 can notify the terminal device 111 of information about the control parameter. The base station device that has been connected to the terminal device 111 can notify the terminal device 111 of preset information, which contains conditions to be satisfied by the terminal device 111 when multiple base station devices belonging to the predetermined area are used as a primary cell or a secondary cell, and the setting of the control parameter to be used when communicating using (multiple base station devices) as a primary cell or a secondary cell. Then, the base station device connected to the terminal device 111 shares the preset information notified to the terminal device 111 with another base station device in the predetermined area. Note that the base station device connected to the terminal device 111 can also perform a preset in the case of a handover from another base station device to the base station device, and share the preset information with other base station devices in the predetermined area. Then, the base station device in the predetermined area can erase the preset information according to the handover of the terminal device 111 to the outside of the predetermined area. Based on this, after establishing a connection in a predetermined area, the terminal device 111 can continuously perform conditional handover in the predetermined area. Note that the predetermined area may be, for example, an area corresponding to the same TAI (tracking area identifier), the same TAC (tracking area code), or the same system information area identifier (systemInformationAreaID), but another area (for example, an area unique to the terminal device 111) may also be defined. In addition, the predetermined area may also be an area corresponding to a RAN-based notification area, which is 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. In addition, the predetermined area may also be an area configured by some or all cells stored in the same aggregation node (CU: Central Unit).

[0046] The base station device 101 determines whether to change the secondary cell to the primary cell and whether to change the primary cell to the secondary cell based on capability information (UE capability), wherein the capability information (UE capability) includes information about the combination of frequency bands that can be used when the terminal device 111 performs carrier aggregation and information presented by the terminal device 111.

[0047] It is assumed that the capability information of the terminal device 111 indicates that, in the carrier aggregation of frequency band 1 and frequency band 41, only frequency band 1 can be used for uplink transmission. In this case, when the primary cell is a cell using frequency band 1 and the secondary cell is a cell using frequency band 41, the base station device 101 cannot change the cell using frequency band 41 that does not enable the terminal device 111 to perform uplink transmission to the primary cell, nor can it change the cell using frequency band 1 to the secondary cell. That is, in this case, the base station device 101 does not instruct the terminal device 111 to switch between the primary cell and the secondary cell and continue the carrier aggregation. In this case, as an example, the base station device 101 can instruct the terminal device 111 to change the cell using frequency band 41 to the primary cell and make the cell that has been used as the primary cell and is using frequency band 1 unnecessary, instead of using the cell as a secondary cell. Furthermore, upon receiving an instruction from the base station apparatus 101 to change the cell using the frequency band 41 to the primary cell and the cell using the frequency band 1 to the secondary cell, the terminal apparatus 111 may change the cell using the frequency band 41 to the primary cell and notify the base station apparatus 101 not to use the frequency band 1. In this case, the terminal apparatus 111 may discard the change instruction from the base station apparatus 101 and start a reconnection process, thereby resolving any inconsistency between the terminal apparatus 111 and the base station apparatus 101.

[0048] Furthermore, for example, it is assumed that the capability information from the terminal device 111 indicates that carrier aggregation of frequency band 1 and frequency band 18 is possible, and at this time, uplink transmission is possible for both frequency band 1 and frequency band 18. Here, when the terminal device 111 is performing carrier aggregation in which the primary cell uses frequency band 1 and the secondary cell uses frequency band 18, the base station device 101 can instruct the terminal device 111 to change the primary cell to a cell of frequency band 18, and to change the secondary cell to a cell of frequency band 1. Furthermore, at this time, the base station device 101 can instruct the terminal device 111 to change the primary cell to a cell of frequency band 18, and not to use the cell of frequency band 1 as a secondary cell.

[0049] Note that also when determining whether to change a cell not used for communication to a primary cell or a secondary cell, similar to the above example, the capability information (UE capability) of the terminal device 111 may be considered. For example, when the terminal device 111 is performing carrier aggregation using frequency band 1 and frequency band 18, the primary cell is changed to a cell of frequency band 41. Here, if the capability information of the terminal device 111 indicates that both carrier aggregation of a combination of frequency band 1 and frequency band 41 and carrier aggregation of a combination of frequency band 18 and frequency band 41 are not possible, the base station device 101 may instruct the terminal device 111 not to continue using the cell of frequency band 1 and frequency band 18. In this case, if the capability information of the terminal device 111 indicates that both carrier aggregation of a combination of frequency band 1 and frequency band 41 and carrier aggregation of a combination of frequency band 18 and frequency band 41 are possible, the base station device 101 may instruct the terminal device 111 to continue using the cell of frequency band 1 or frequency band 18 as a secondary cell or not to continue using the cell of frequency band 1 or frequency band 18 as a secondary cell. In addition, for example, when independently determining whether to change the primary cell to a cell of frequency band 41, the terminal device 111 can determine whether to continue to use the cell of frequency band 1 and the cell of frequency band 18 based on the capability information of the terminal device 111 itself. Note that even if the terminal device 111 has the capability to continue to use the cells of frequency band 1 and frequency band 18, for example, from the perspective of power saving, when the cell of frequency band 41 is set as the primary cell, the terminal device 111 can determine to use only one of the cell of frequency band 1 and the cell of frequency band 18, or not to use both. Then, the terminal device 111 can send a request signal based on the determination result to the base station device 101. In addition, the terminal device 111 can notify the base station device 101 of capability information (UE capability), which includes information on whether control parameters to be used when a cell not used for communication is used as a primary cell or a secondary cell can be set in advance before using the parameters. Similarly, the terminal device 111 may notify the base station device 101 of capability information including information on whether control parameters to be used when a cell being used as a secondary cell is used as a primary cell can be preset before the control parameters are used for communication, and information on whether control parameters to be used when a cell being used as a primary cell is used as a secondary cell can be preset before the control parameters are used for communication. In these cases, the base station device 101 may instruct only the terminal device that has been notified of capability information indicating that preset can be performed to perform preset.

[0050] In addition, in the above example, a case where the secondary cell and the primary cell are switched during CA (carrier aggregation) has been described, but is not limited to this. For example, in a case where the terminal device 111 and the base station device 101 communicate with each other using TRPs or TRxPs (transmit and receive points) containing different PCIs (physical cell identifiers) during inter-cell beam management, the above technology can also be applied when switching the main TRP and the additional TRP. That is, using a method similar to the above method, the efficiency of control related to scheduling request control, timing advance control, beamforming control, HARQ control, CDRX control, and PHR control can be improved and improvements can be achieved.

[0051] In addition, also when the main TRP and the additional TRP are switched during inter-cell beam management, the control parameters required when at least one PCI used as an additional TRP is used as the main TRP (for example, a control information common search space for receiving a PDCCH related to notification information and paging) can be notified to the terminal device 111 in advance using layer 3 signaling or the like. Then, the base station device 101 instructs the terminal device 111 to switch between the main TRP and the additional TRP based on the wireless quality measurement result from the terminal device 111 using layer 2 or layer 1 signaling. Note that the terminal device 111 can determine that the main TRP and the additional TRP are to be switched (regardless of the instruction from the base station device 101), and send a request signal to the base station device 101 requesting switching between TRPs based on the determination result. In addition, when the control parameters required when at least one PCI is used as the main TRP are the same as the control parameters used when a TRP (or TRxP) containing another PCI is used as the main TRP, the base station device 101 can notify the terminal device 111 to omit the notification of the control parameters. In addition, the base station apparatus 101 may perform only notification of a change difference from the control parameters used when a TRP (or TRxP) containing another PCI is used as a main TRP, as control parameters required when a TRP (or TRxP) is used as a main TRP.

[0052] (Device Configuration)

[0053] Will refer to Figure 2Describe an exemplary hardware configuration of a base station device and a terminal device. In one example, the base station device and the terminal device are each configured by including 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 a general-purpose CPU (central processing unit) and one or more processing circuits such as an ASIC (application-specific integrated circuit), and performs the overall processing of the device and the above-mentioned processing by reading out and executing programs stored in the ROM 202 or the storage device 204. ROM 202 is a read-only memory that stores information such as programs and various parameters related to the processing performed by the base station device and the terminal device. RAM 203 is a random access memory that is used as a workspace when the processor 201 executes the program, and also stores temporary information. The storage device 204 is composed of a removable external storage device or the like. For example, the communication circuit 205 is composed of a circuit for wireless communication of 5G and post-5G standards. Note that, Figure 2 The figure shows one communication circuit 205, but, for example, the base station device and the terminal device may each include two or more communication circuits. In addition, for example, the base station device and the terminal device may each include wireless communication circuits and common antennas for 5G and post-5G standards. Note that the base station device and the terminal device may each include an antenna for the 5G standard and an antenna for the post-5G standard. In addition, the terminal device may include a communication circuit for another wireless communication network such as a wireless LAN. Note that the base station device and the terminal device may each include a separate communication circuit for the corresponding available frequency band, or may include a communication circuit shared for at least some frequency bands. Note that in an embodiment of the present invention, the terminal device includes a plurality of communication circuits that can communicate using a common frequency band. In addition, the base station device may also include a wired communication circuit used when communicating with another base station device or a node in a core network.

[0054] Figure 3 2 is a diagram showing an exemplary functional configuration of a base station apparatus. The base station apparatus includes, as its functional units, for example, a control parameter setting unit 301, a primary cell change determination unit 202, a primary cell change indication notification unit 303, and a layer 2 / layer 1 control unit 304. Note that Figure 3 Only functional units particularly relevant to the embodiments of the present invention are shown, and illustrations of various other functional units that the base station apparatus may have are omitted. Of course, for example, the base station apparatus has other functional units that are typically present in base station apparatuses that comply with 5G and post-5G standards. In addition, Figure 3 The functional blocks in are schematically shown, and the functional blocks may be implemented in an integrated manner, or may be further subdivided. In addition, for example, Figure 3The functions in the embodiment may be implemented by the processor 201 executing a program stored in the ROM 202 or the storage device 204, or may be implemented by the processor included in the communication circuit 205 executing predetermined software. Note that the processing performed by each functional unit is not described in detail here with reference to the above detailed description, but its functions will be described only schematically.

[0055] When instructing the terminal device 111 to start CA (carrier aggregation), the control parameter setting unit 301 notifies the control parameters used when using the cell added as the secondary cell for communication as the secondary cell. In addition, the control parameter setting unit 301 also notifies the terminal device 111 of the control parameters used when using the cell as the primary cell for communication. For example, the control parameter setting unit 301 can send control parameters such as those described above to the terminal device 111 using layer 3 signaling such as RRC reconfiguration. The primary cell change determination unit 302 requests the terminal device 111 to measure and report the wireless quality of the primary cell and the secondary cell, and obtains the measurement result of the wireless quality from the terminal device 111. For example, based on the measurement result obtained from the terminal measurement 111, the primary cell change determination unit 302 determines that the cell being used as the secondary cell is to be changed to the primary cell. The primary cell change indication notification unit 303 instructs the terminal device 111 to change the cell being used as the secondary cell to the primary cell based on the determination result of the primary cell change determination unit 302. Note that, for example, the primary cell change instruction notification unit 303 transmits an instruction to the terminal device 111 using layer 2 or layer 1 signaling.

[0056] The layer 2 / layer 1 control unit 304 determines whether the control parameters of layer 2 and layer 1 are changed due to the change of the primary cell, and determines whether it is necessary to initialize the state variables for controlling layer 2 / layer 1 before the primary cell is changed, and whether it is necessary to continue the processing started before the change. For example, if it is determined that the control parameters related to beam control are not changed, the layer 2 / layer 1 control unit 304 selects a suitable beam after the change of the primary cell based on the measurement results of the beams received from the terminal device 111 before the primary cell is changed. In addition, in this case, the layer 2 / layer 1 control unit 304 can perform beam control by selecting an appropriate TCI setting from the activated TCI settings based on the information on activation / deactivation of the TCI setting that has been set in the terminal device 111 before the primary cell is changed. In addition, for example, in HARQ control, if it is determined that the control parameters are not changed after the primary cell is changed, the layer 2 / layer 1 control unit 304 can control so that after the primary cell is changed, HARQ-ACK / NACK in response to the data sent to the terminal device 111 before the primary cell is changed is received.

[0057] Figure 4401, a primary cell change processing unit 402, and a layer 2 / layer 1 control unit 403 as functional units thereof. Note that Figure 4 Only functional units particularly related to the embodiments of the present invention are shown, and illustrations of various other functional units that the terminal device may have are omitted. Of course, for example, the terminal device has other functional units that terminal devices that comply with 5G and post-5G standards generally have. In addition, Figure 4 The functional blocks in are schematically shown, and the functional blocks may be implemented in an integrated manner, or may be further subdivided. In addition, for example, Figure 4 The functions in the embodiment may be implemented by the processor 201 executing a program stored in the ROM 202 or the storage device 204, or may be implemented by the processor included in the communication circuit 205 executing predetermined software. Note that the processing performed by each functional unit is not described in detail here with reference to the above detailed description, but its functions will be described only schematically.

[0058] The control parameter obtaining unit 401 obtains control parameters for a case where each cell is used as a primary cell and control parameters for a case where each cell is used as a secondary cell from a base station device connected thereto. The control parameter obtaining unit 401 performs processing for setting in the terminal device based on the obtained control parameters. For example, the control parameter obtaining unit 401 receives a setting message (an RRC message such as an RRC reconfiguration message) to obtain the control parameters contained in the setting message. The primary cell change processing unit 402 performs processing for changing a cell currently being used as a secondary cell to a primary cell. For example, the primary cell change processing unit 402 receives an indication to change a cell to a primary cell from the base station device 101 using layer 2 signaling such as a downlink MAC CE or layer 1 signaling such as a DCI.

[0059] The layer 2 / layer 1 control unit 403 determines whether the control parameters of layer 2 and layer 1 are changed due to the change of the primary cell, and determines whether it is necessary to initialize the state variables for controlling layer 2 / layer 1 before the primary cell is changed, and whether it is necessary to continue the processing started before the change. For example, if it is determined that the HARQ control parameters are not changed, the layer 2 / layer 1 control unit 403 controls so that the data stored in the HARQ soft buffer is saved without erasing it. In addition, if it is determined that the CDRX control parameters are not changed, the layer 2 / layer 1 control unit 403 controls so that the timers related to the CDRX control, such as onDurationTimer, inactivityTimer, drx-ShortCycleTimer, drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerUL, continue without stopping them.

[0060] (Processing flow)

[0061] Next, we will refer to Figure 5 An example of the flow of a process performed in a wireless communication system is described. Note that the detailed process described here is the same as the detailed process described above, and therefore, the process will only be schematically described here, and its detailed description will be omitted.

[0062] exist Figure 5In this state, an initial connection has been established between the terminal device 111 and the base station device 101. In this state, for example, when instructing the terminal device 111 to add a secondary cell, the base station device 101 sets the control parameters related to the cell as the communication setting of the terminal device 111 (step S501). Note that the terminal device 111 is using one of the one or more cells provided by the base station device 101 that has established the initial connection as the primary cell. In order to add a secondary cell, the base station device 101 notifies the terminal device 111 of the control parameters for communicating using the cell as the secondary cell. Based on the setting, the base station device 101 performs a setting process for adding a secondary cell based on the notified control parameters. In addition to this, the base station device 101 also notifies the terminal device 111 of the control parameters to be used when the terminal device 111 uses the cell as the primary cell for communication. After adding the secondary cell, the terminal device 111 performs wireless quality measurement of the primary cell and the secondary cell, and reports the measurement value to the base station device 101 (step S502). Here, it is assumed that the base station device 101 determines to change the cell used as the secondary cell to the primary cell based on the received measurement result. In this case, based on the determination result, the base station device 101 instructs the terminal device 111 to change the cell being used as the secondary cell to the primary cell (step S503). After receiving the instruction, the terminal device 111 determines whether the control parameters of layer 2 and layer 1 are changed due to the change of the primary cell, determines whether it is necessary to initialize the state variables used for layer 2 / layer 1 control before the primary cell change (step S504), and determines whether it is necessary to continue the processing that has been started before the change (step S505). For example, if it is determined that the HARQ control parameters are not changed, the terminal device 111 determines that the data stored in the HARQ soft buffer will continue to be stored without being erased. In addition, if it is determined that the CDRX and PHR control parameters are not changed, the terminal device 111 determines to continue the timer related to the CDRX control (such as onDurationTimer) and the timer related to the PHR control (such as phr-PeriodicTimer) without stopping. In another example, if it is determined that the control parameters related to beam control are not changed, the terminal device 111 may determine to continue to maintain the activation / deactivation information about the TCI setting that has been set before changing to the primary cell and erase it. Then, the terminal device 111 sends a response to the indication of changing to the primary cell to the base station device 101 (step S506).

[0063] As described above, according to an embodiment of the present invention, in DC and CA, switching between the primary cell and the secondary cell can be performed at a higher speed. Therefore, it is possible to contribute to SDG (Sustainable Development Goal) 9 led by the United Nations: "Building resilient infrastructure, promoting inclusive and sustainable industrialization, and promoting innovation".

[0064] The present invention is not limited to the above-described embodiments, and various changes / alterations can be made within the spirit of the present invention.

[0065] This application claims priority from Japanese Patent Application No. 2022-153890 filed on September 27, 2022, which is hereby incorporated herein by reference.

Claims

1. A terminal device that communicates with a base station device using a primary cell and a secondary cell through carrier aggregation, characterized in that: The terminal device comprises: A first receiving unit, which receives, with respect to one or more cells, parameters required when the one or more cells are used as primary cells; a second receiving unit, configured to respectively receive parameters required when the one or more cells are used as secondary cells; a changing unit, which, when a first cell among the one or more cells is used as a secondary cell, changes the first cell into a primary cell; as well as A third receiving unit receives, from the base station device, information on whether to continue to use as a secondary cell a second cell that becomes a non-primary cell after the first cell is changed to a primary cell.

2. The terminal device according to claim 1, characterized in that The terminal device also has: a determining unit, which determines whether a control parameter of CDRX (connected discontinuous reception) 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 third receiving unit receives an indication that the second cell continues to be used as a secondary cell; as well as The timer control unit is configured to, when the determination unit determines that the control parameters of CDRX are the same, continue the timer related to the CDRX control being activated without stopping it when the second cell is changed to a secondary cell.

3. The terminal device according to claim 1, characterized in that The terminal device also has: a determining unit, which determines whether parameters related to beam control of the second cell are 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 third receiving unit receives an indication that the second cell is continued to be used as a secondary cell; as well as The beam recovery processing continuing unit is configured to continue the processing without stopping the beam recovery processing when the determination unit determines that the parameters related to beam control are the same, that is, when the beam recovery processing is started when the second cell is used as the main cell. The beam recovery processing continuing unit takes the change to the secondary cell as an opportunity.

4. The terminal device according to claim 1, characterized in that: The terminal device also has: a determination unit configured to determine whether a setting related to the 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; and The buffer control unit is configured to hold the data held in the soft buffer of the HARQ of the terminal device without deleting the data when the determination unit determines that the settings related to the hybrid automatic repeat request (HARQ) are the same.

5. The terminal device according to claim 1, characterized in that: The first receiving unit and the second receiving unit receive parameters through an RRC reconfiguration message, and the changing unit changes the first cell to a primary cell according to the identification information of the first cell and the value of the radio network temporary identifier (RNTI-Value) used after the change of the primary cell obtained from the base station device through a media access control / control element (MACCE) or a downlink control information (DCI).

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