Terminal device, control method, and program for executing flexible operation procedure of component carrier

Abstract

To make it possible to easily switch component carriers used in a terminal device.SOLUTION: A terminal device notifies a base station device of information indicating a combination of frequency bands that can be used by the terminal device when communication is made using a plurality of component carriers in mutually different frequency bands, and obtains, from the base station device, setting information for using one or more component carriers that each correspond to one or more frequency bands that are not limited by the combination of usable frequency bands.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for flexible control of the use of multiple component carriers. [Background technology]

[0002] The cellular communication standard of the Third Generation Partnership Project (3GPP) specifies dual connectivity (DC) and carrier aggregation (CA), which enable a terminal device to simultaneously use multiple component carriers (CCs). In DC and CA, multiple CCs that can be simultaneously used by the terminal device are configured based on the terminal device's UE capability. The multiple CCs include a primary CC and a secondary CC. When the terminal device communicates, activation or deactivation is performed for a secondary CC among the CCs configured for the terminal device, thereby making it possible to configure whether the secondary CC is actually used. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS38.331 Summary of the Invention [Problem to be solved by the invention]

[0004] When CCs of multiple different frequency bands are prepared, a combination of usable frequency bands is specified as the capability of the terminal device. Therefore, a combination of CCs of usable frequency bands is configured for the terminal device. Meanwhile, there may be cases where the wireless quality of a second frequency band other than the first frequency band of the CC used by the terminal device is better than the wireless quality of the first frequency band. However, depending on the capability of the terminal device, it is assumed that the first CC used by the terminal device and the second CC of the frequency band with better wireless quality cannot be used simultaneously. In this case, to switch the CC used by the terminal device from the first CC to the second CC, it is necessary to cancel the configuration of the first CC and then configure the second CC, which is a cumbersome process.

[0005] The present invention provides a technique that enables easy switching of component carriers used in a terminal device. [Means for solving the problem]

[0006] A terminal device according to one aspect of the present invention includes a notification unit that notifies a base station device of information indicating a combination of frequency bands that can be used by the terminal device when communicating using a plurality of component carriers having different frequency bands, and a notification unit that notifies a base station device of information indicating the combination of frequency bands that can be used by the terminal device. Either to Included Multiple component carriers corresponding to multiple frequency bands A plurality of pieces of setting information corresponding to each of the component carriers For use , a plurality of combinations of available frequency bands that are not limited to the combination of available frequency bands An acquisition means for acquiring setting information; a setting unit that sets the plurality of component carriers based on the acquired setting information; and an enabling unit that enables a component carrier included in the set plurality of component carriers based on the combination of the available frequency bands. It has. [Effects of the Invention]

[0008] According to the present invention, it is possible to easily switch component carriers used in a terminal device. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Figure 2] FIG. 10 is a diagram illustrating an example of a method for specifying CCs to be enabled / disabled. [Figure 3] FIG. 10 is a diagram illustrating an example of a method for specifying CCs to be enabled / disabled. [Figure 4] FIG. 2 illustrates an example of a hardware configuration of the apparatus. [Figure 5] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. [Figure 6] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station device. [Figure 7] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication system. [Figure 8] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication system. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. Furthermore, the same reference numerals are used to designate identical or similar components, and redundant descriptions will be omitted.

[0011] (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), and is configured to include base station device 101, base station device 102, and 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.

[0012] In this embodiment, the terminal device 111 is configured to be able to communicate in parallel between the base station device 101 and the base station device 102 using multiple component carriers (CCs) simultaneously using dual connectivity (DC) or carrier aggregation (CA). Note that in the following description, "CC" can also be interpreted as "cell." While 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 of the combinations of multiple frequency bands, rather than all of the combinations of multiple different frequency bands. For example, the terminal device 111 is able to use the combination of a first frequency band and a second frequency band, and the combination of the first frequency band and a third frequency band, but is unable to use the combination of the second frequency band and the third frequency band, or the combination of the first frequency band, the second frequency band, and the third frequency band. The first, second, and third frequency bands may be, for example, band 1, band 18, and band 41 defined by the standard. Although three frequency bands are described here, additional frequency bands such as a fourth frequency band (for example, band 42) may also be provided.

[0013] In this case, for example, while the base station device 101 is connected to the terminal device 111 in a first frequency band, the base station device 101 uses a CC in the first frequency band as a primary component carrier (primary CC) or a primary cell, and configures a CC in the second frequency band or the third frequency band as a secondary component carrier (secondary CC) or a secondary cell. In the following description, the base station device providing communication via the primary CC is assumed to be the base station device 101. However, the base station device 102 may also function in that role, and the base station device 101 in the following description can be read as the base station device 102. Furthermore, both the primary CC and the secondary CC may be configured as LTE CCs, or both the primary CC and the secondary CC may be configured as 5G CCs. That is, both the primary CC and the secondary CC may be configured as CCs of the same wireless system. Furthermore, the primary CC may be configured as an LTE CC and the secondary CC as a 5G CC, or the primary CC may be configured as a 5G CC and the secondary CC as a CC defined in LTE or a future generation. That is, the primary CC and the secondary CC may be configured as CCs of different wireless systems.

[0014] For example, the base station device 101 uses an RRC (Radio Resource Control) message to additionally configure a CC for the terminal device 111, with the CC of the second frequency band as the secondary CC. This additional configuration is generally performed according to the capability information (UE Capability) of the terminal device 111. That is, conventionally, a configuration has been made such that additional configuration of a CC is possible only for a combination of frequency bands that the terminal device 111 can use. After completing this configuration, the terminal device 111 can then establish a connection by performing a random access procedure with a base station device (e.g., the base station device 101 or the base station device 102) that provides the secondary CC, and start communication using the secondary CC. Note that after additionally configuring the secondary CC, the terminal device 111 can communicate using the secondary CC by activating the CC. Furthermore, for example, if the required throughput decreases, the secondary CC may not be used, and in that case, the CC may be deactivated. Here, if the terminal device 111 can use all of the first frequency band, the second frequency band, and the third frequency band, it can perform settings to add secondary CCs in both the second frequency band and the third frequency band while setting the CC in the first frequency band as the primary CC. In this case, if the wireless quality of the second frequency band deteriorates and the wireless quality of the third frequency band improves while the CC in the second frequency band is set as the secondary CC, the terminal device 111 can disable the CC in the second frequency band and enable the CC in the third frequency band, thereby selectively using the CC in the frequency band with good wireless quality.

[0015] On the other hand, as described above, in this embodiment, the terminal device 111 can use the combination of the first frequency band and the second frequency band and the combination of the first frequency band and the third frequency band, but cannot use the combination of the second frequency band and the third frequency band or the combination of the first frequency band, the second frequency band, and the third frequency band. Therefore, even if the wireless quality of the CC of the second frequency band deteriorates while the terminal device 111 is communicating using a CC of the first frequency band and a CC of the second frequency band, and a state in which switching to a CC of the third frequency band is required, the switching cannot be performed by enabling and disabling. In other words, in this case, the terminal device 111 cannot use the CC of the third frequency band unless, for example, the base station device 101 cancels the configuration of the CC of the second frequency band and configures the CC of the third frequency band. This setting increases the overhead of complicated processing and signaling, such as the transmission and reception of RRC messages, and may also lengthen the time required to complete the change of CC settings.

[0016] In this embodiment, in consideration of such circumstances, the terminal device 111 notifies the base station device 101 of its own capability information (UE Capability). Here, as described above, in this embodiment, the terminal device 111 notifies the base station device 101 of capability information indicating that the terminal device 111 is able to use a combination of a first frequency band and a second frequency band and a combination of the first frequency band and a third frequency band. Note that this capability information does not include the combination of the second frequency band and the third frequency band, or the combination of the first frequency band, the second frequency band and the third frequency band. In other words, a frequency band combination not included in the capability information is implicitly indicated as a combination that the terminal device 111 is not able to use. In response to this, the base station device 101 executes a setting process for enabling the terminal device 111 to use one or more CCs corresponding to one or more frequency bands, without being limited / constrained by the combination of frequency bands that the terminal device 111 is able to use. As described above, the terminal device 111 cannot use the combination of the first frequency band, the second frequency band, and the third frequency band. However, the base station device 101 performs configuration to enable the CC of the first frequency band provided by the base station device 101 to be used as a primary CC and the CCs of the second frequency band and the third frequency band to be used as secondary CCs. In other words, while the base station device 101 conventionally could configure only one of the second frequency band and the third frequency band as a secondary CC, in this embodiment, the base station device 101 configures both the second frequency band and the third frequency band. The base station device 101 may configure some or all of the frequency bands available to the terminal device 111, as indicated by the capability information of the terminal device 111.

[0017] For example, if there is another base station device that provides communication in the second frequency band or the third frequency band, the base station device 101 transmits a request to add a secondary CC (secondary cell) to that base station device and receives a response thereto. Thereafter, the base station device 101 transmits an RRC message (e.g., an RRCReconfiguration message) to the terminal device 111 and completes the configuration in the terminal device 111 by receiving a response message (e.g., an RRCReconfigurationComplete message) from the terminal device 111. Upon receiving this message, the terminal device 111 acquires configuration information for using CCs in the second frequency band and CCs in the third frequency band and performs configuration based on the configuration information. The terminal device 111 can use the CC configured in this way by activating the CC. At this time, the terminal device 111 selects a CC to activate based on its own capability information. That is, in this embodiment, the base station device 101 configures CC candidates based on the capability information of the terminal device 111 and provides the terminal device 111 with configuration information related to the configuration. Then, the terminal device 111 performs configuration for using CC candidates based on the configuration information, and enables or disables one of the CC candidates as necessary. Note that the base station device 101 may, for example, indicate the CC to be initially enabled by an RRC message for configuring the above-mentioned CC candidates. Note that all CC candidates may be initially disabled. Note that "disabled" here refers to a state in which a CC can be made usable by performing processing for activation, and also refers to a state in which the configuration is complete but the CC is not yet ready for communication.

[0018] According to this procedure, the terminal device 111 can switch the CC to be used by enabling and disabling the CC. Therefore, there is no need to transmit and receive an RRC message again to switch the CC, which simplifies the configuration process, prevents an increase in signaling overhead, and shortens the time required for switching the CC. Note that the activation and deactivation of a CC can be performed by an instruction from the base station device 101. In this case, the activation and deactivation can be performed by a message different from an RRC message such as downlink control information (DCI). In one example, the base station device 101 can notify the terminal device 111 of information indicating whether each secondary CC candidate is in an activated state or a deactivated state. In one example, the base station device 101 can notify the terminal device 111 of a bitmap having the same number of bits as the number of secondary CC candidates, in which "1" is assigned to secondary CC candidates to be activated and "0" is assigned to secondary CC candidates to be deactivated. Furthermore, for example, in an RRC message when configuring each secondary CC candidate, the base station device 101 may include, in the configuration information for each candidate, an information element that specifies a state indicating whether the candidate is initially activated. The base station device 101 can initially specify whether each CC candidate is activated or deactivated by using an information element such as "scellstate" to specify "scellstate=activated" for activation or "scellstate=deactivated" for deactivation. However, this is just one example, and the base station device 101 may also be configured to be able to deactivate the primary CC. In this case, for example, only the secondary CC may be activated and used for communication.

[0019] The base station device 101 may notify the terminal device 111 of, for example, the number of secondary CCs that can be activated. For example, the base station device 101 may set this number depending on the degree of network congestion, the amount of data to be transmitted and received by the terminal device 111, etc. For example, when the amount of data transmitted by the network or the terminal device 111 increases, the base station device 101 may increase the number of CCs that can be simultaneously activated in the terminal device 111, and when the amount of data transmitted by the network or the terminal device 111 decreases, the base station device 101 may decrease the number of CCs that can be simultaneously activated in the terminal device 111. In one example, the base station device 101 may set a small number of secondary CCs when the network is congested, and may set a large number of secondary CCs when the network is not congested.

[0020] Note that the terminal device 111 may determine to perform configuration according to conventional processing, for example, when a number exceeding the number of CCs that the terminal device 111 can activate is specified, when the number is not set, or when the number is set to a predetermined value. In this case, when the terminal device 111 receives configuration information for CCs of a combination of frequency bands that the terminal device 111 cannot use, the terminal device 111 may discard the configuration information. The terminal device 111 may also notify the base station device 101 of the number of CCs that can be simultaneously activated as capability information. In this case, the base station device 101 may notify the terminal device 111 of a number that does not exceed the specified number as the number of secondary CCs that can be activated. The base station device 101 may also notify the terminal device 111 of at least one of information indicating a combination of frequency bands that cannot be simultaneously activated and information indicating a combination of frequency bands that can be simultaneously activated. For example, when some frequency bands should not be used temporarily, the terminal device 111 may be notified that a combination including those frequency bands should not be used. The notification of the number of secondary CCs that can be activated and the combination of frequency bands that can be simultaneously activated may be performed by an RRC message or by a message other than an RRC message, such as DCI. Furthermore, information such as the number of CCs that can be activated and combinations of frequency bands that can be activated together may be notified simultaneously to a plurality of terminal devices by broadcast information (for example, a system information block).

[0021] In the above example, one CC (cell) is configured for one frequency band. However, multiple CCs (cells) may be associated with one frequency band. In this case, CCs may be specified by a cell identifier (e.g., a physical cell identifier (PCI) or a cell group identifier (CGI)), and the configuration and activation / deactivation of these CCs may be performed in the same manner as in the above example. A temporary serial number (index) may be assigned to each secondary CC (cell), and the activation / deactivation of each CC may be specified using the serial number. For example, an index such as "0" may be assigned to the CC corresponding to the first cell identifier of band 18, "1" to the CC corresponding to the second cell identifier of band 18, "2" to the CC of band 41, and "3" to the CC of band 42 may be assigned. The activation and deactivation of each CC may be instructed by the base station device 101 using information specifying the CC by the index. In one example, when four CCs are configured as described above, the activation or deactivation of each CC may be instructed by a 4-bit bitmap corresponding to indexes 0 to 3, respectively. Alternatively, an index may be assigned to each combination of enabled / disabled states of multiple CCs, and the enabled / disabled state of each CC may be specified by specifying the index. An example of this specification method is shown in Fig. 2. As shown in Fig. 2, for example, if no secondary CCs are to be used, an index of "0" is specified, if the secondary CC with PCI=1 in band 18 is to be enabled, an index of "1", if the secondary CC in band 41 is to be enabled, an index of "3", etc.

[0022] In the above example, the primary CC is always enabled, but the primary CC may be disabled. In this case, the primary CC may be enabled / disabled in the same manner as the secondary CC is enabled / disabled. For example, if an index is assigned to each enabled / disabled combination of multiple CCs, an index is also assigned to the CC usage pattern when the primary CC is disabled, as shown in FIG. 3. When a bitmap is used, it is sufficient to add one bit for the primary CC. Note that, here, band 1 is the primary CC, and disabling band 1 is referred to as disabling the primary CC, but any of the enabled CCs may be selected as the primary CC. In other words, multiple CC candidates may be preset, and a process may be performed in which the primary CC is selected from among them.

[0023] When each CC candidate is preset, the setting to be used when selected as the primary CC and the setting to be used when selected as the secondary CC may be set separately. In this case, the terminal device 111 may switch the setting depending on whether the CC is selected as the primary CC or the secondary CC.

[0024] The terminal device 111 may notify the base station device 101 of the measurement results of the radio quality in each frequency band so that the base station device 101 can determine whether to configure or enable / disable a CC. This notification may be performed using a conventional mechanism such as a measurement report (e.g., MEASUREMENT REPORT), or a new notification mechanism (e.g., UE ASSISTANCE INFORMATION) may be provided. The base station device 101 may determine at least one of which CC to enable and which CC to disable based on this notification, and notify the terminal device 111 of this. Furthermore, the terminal device 111 may independently enable or disable CCs and notify the base station device 101 of information indicating at least one of which CC has been enabled and which CC has been disabled. This notification may be performed, for example, using a bitmap or the index shown in FIG. 2 or FIG. 3, as described above. This notification may also be reported using uplink control information (UCI). For example, this notification may be performed by multiplexing information with user data transmitted on the primary CC and transmitting the information. Furthermore, the transmission and reception of information (on the uplink and downlink) between the terminal device 111 and the base station device 101 described above may be performed using a Medium Access Control (MAC) Control Element (CE), UE assistance information, or the like.

[0025] Furthermore, when the terminal device 111 moves, it is assumed that the CC candidates configured as described above will no longer be appropriate. For this reason, as the terminal device 111 moves, the base station device 101 may use an RRC message (e.g., an RRCReconfiguration message) to instruct the terminal device 111 to delete at least some of the information about the CC candidates. For example, when the primary cell of the terminal device 111 is changed, the information about the secondary CC candidates may be deleted. The base station device 101 may also add and delete secondary CC candidates based on a radio quality measurement report from the terminal device 111. For example, when a CC candidate is configured for the terminal device 111, an expiration date for the configuration may also be set, and the configuration may be deleted when the expiration date has passed. The base station device 101 may configure CC candidates at regular intervals, for example, and update the configuration information before the expiration date has passed. For example, the base station device 101 may update the CC candidates to be configured based on measurement results for each CC in the terminal device 111. That is, the base station device 101 can estimate the area of ​​the cell in which the terminal device 111 is located according to changes in the measurement results in the terminal device 111, and can set, for example, the CC of a neighboring cell that is within a predetermined distance from the cell as a candidate CC. The terminal device 111 can also measure the wireless quality of CCs (cells) that are not set as candidate CCs, and request the base station device 101 to add CCs that are detected with sufficient wireless quality as candidate CCs. In response to this request, the base station device 101 can notify the terminal device 111 of the configuration information of the CC.

[0026] The selection of a CC to be activated from among the CC candidates configured in the terminal device 111 may be performed, for example, based on a priority set for each CC candidate. The priority may be set, for example, so that a CC with better wireless quality has a higher priority. This allows CC candidates with higher wireless quality to be preferentially activated. Here, for example, CC candidates whose wireless quality does not exceed a threshold may not be prioritized. This prevents CC candidates with low wireless quality from being activated, resulting in a high priority but insufficient wireless quality. Furthermore, the wireless quality of each CC candidate may be compared with a predetermined wireless quality threshold, and a CC candidate with wireless quality exceeding the threshold may be prioritized. This threshold may be, for example, the wireless quality of a currently used secondary CC. In other words, the priority may be set so that CC candidates with better wireless quality than the currently used CC are more likely to be activated.

[0027] Furthermore, the priority may be set based on the load status of the cell corresponding to each CC candidate. That is, the priority of a CC candidate corresponding to a cell in a high load state may be lowered, or the priority of a CC candidate corresponding to a cell in a low load state may be raised. Furthermore, the priority may be set based on the type of service that can be provided (for example, the slices supported in each cell, whether communication services can be provided to a low-capability terminal device (Reduced Capability UE), etc.). For example, a CC that can provide a communication service executed by the terminal device 111 or a CC that is compatible with the capability information of the terminal device 111 may be set to a high priority, making it more likely to be activated. Furthermore, for example, when some CCs are powered off due to network power saving control, the priority of those CCs may be set to a low priority so that they are less likely to be activated. Note that the process of relatively raising or lowering the priority may be performed, for example, by adding a predetermined offset value to the radio quality of each CC when raising the priority, or by subtracting a predetermined offset value when lowering the priority. Note that there may be multiple levels of offset values ​​corresponding to the priority, so that more appropriate prioritization may be performed. For example, multiple offset values ​​may be prepared according to the magnitude of the load, or multiple offset values ​​may be prepared according to the length of the power-off time.

[0028] Furthermore, as described above, when CC candidates whose wireless quality is not equal to or greater than a threshold are excluded from being prioritized, the threshold may be changed for each CC candidate based on the criteria described above. For example, for a CC candidate in a high-load state, a predetermined offset value may be added to the threshold to make the CC candidate less likely to be prioritized, i.e., less likely to be activated. Similarly, for a CC candidate in a low-load state, a predetermined offset value may be subtracted from the threshold to make the CC candidate more likely to be prioritized, i.e., more likely to be activated. Furthermore, for example, for CCs that can provide communication services executed by the terminal device 111 or CCs that are compatible with the capability information of the terminal device 111, a predetermined offset value may be subtracted to lower the threshold, making the CC more likely to be activated. Furthermore, for example, when some CCs are powered off due to network power saving control, an offset value may be added to the threshold to make the CC less likely to be activated. The offset value applied to this threshold may also be a multi-level value.

[0029] Based on the priorities set as described above, the terminal device 111 may activate the number of CCs available, starting with the highest priority. At this time, the activation process may be performed based on the combination of frequency bands available to the terminal device 111. For example, if one CC with the highest priority is activated, other CCs that cannot be used in combination with that CC may not be activated, even if they have a higher priority. Prioritization may be performed for each combination of frequency bands available to the terminal device 111. For example, prioritization may be performed based on the throughput expected to be obtained by using each combination. Furthermore, as described above, the priorities may be adjusted depending on the load state, the services that can be provided, the power-off state, and the like. The terminal device 111 may select CCs to be activated or deactivated and notify the base station device 101 of the selection result. Alternatively, the terminal device 111 may report the results of measuring wireless quality to the base station device 101, and the base station device 101 may make a similar selection based on the report.

[0030] The activation / invalidation of CC in the terminal device 111 may be triggered by an increase or decrease in the amount of data transmitted or received in the terminal device 111. Furthermore, the activation / invalidation of CC in the terminal device 111 may also be performed in response to, for example, the occurrence of a predetermined event.

[0031] The event may include, for example, the wireless quality of an unused CC candidate (deactivated CC) becoming better than the wireless quality of a used CC (activated CC). If there are multiple used CCs, it may be determined that an event has occurred if the wireless quality of the unused CC candidate becomes better than the lowest quality CC among those CCs. If there are multiple used CCs, it may be determined that an event has occurred if the wireless quality of the unused CC candidate becomes better than the average wireless quality of those CCs. In such cases, the wireless quality used as the evaluation standard for multiple used CCs may be determined based on other criteria. In this way, if there is an unused CC candidate with better wireless quality than the currently used CC, the terminal device 111 can communicate with good wireless quality by using that CC candidate (e.g., by switching CCs).

[0032] Alternatively, the event may be when the wireless quality of an unused CC candidate exceeds a predetermined threshold. In this case, enabling the CC candidate enables the terminal device 111 to communicate with good wireless quality. Alternatively, the event may be when the wireless quality of a used CC falls below a predetermined threshold. When multiple CCs are in use, it may be determined that an event has occurred when the CC with the lowest quality falls below a predetermined threshold. When multiple CCs are in use, it may be determined that an event has occurred when the average value of the wireless qualities of those CCs falls below a predetermined threshold. In such cases, other criteria may be used to determine the wireless quality that serves as the basis for evaluating multiple used CCs. In this case, stopping the use of that CC and disabling it allows the terminal device 111 to use another CC with relatively good wireless quality.

[0033] The event may also be when the wireless quality of a CC in use falls below a first threshold and the wireless quality of a candidate CC that is not in use exceeds a second threshold. The event may also be when the wireless quality of a candidate CC that is not in use is better than the wireless quality of a CC that is in use by a predetermined offset or more. This allows the communication environment in the terminal device 111 to be improved by activating a CC that is not activated but is expected to be capable of performing communication with better wireless quality than a CC in use. The event may also be when the amount of data stored in a radio link control (RLC) buffer exceeds a predetermined value. This allows the number of CCs to be activated to be increased when the amount of data stored in the buffer becomes large.

[0034] Each event may be notified from the base station device 101 to the terminal device 111 by an RRC message (for example, an RRCReconfiguration message or an RRCResume message). When this event occurs, the terminal device 111 transmits the measurement result to the base station device 101. The base station device 101 then decides to activate a CC that is not currently activated or to disable a CC that is currently activated, and instructs the terminal device 111 of the decision. In this case, the base station device 101 may determine the number of CCs to activate based on the amount of data accumulated in the RLC buffer, and may decide to activate that number of CCs. The base station device 101 may exchange information indicating the congestion status of the CC, the type of supported service, and whether or not power-saving control such as power-off is performed, with other base station devices that provide CCs in use or CC candidates. This information may be exchanged between base stations using a RESOURCE STATUS REQUEST, or may be shared between base stations using a new message. Then, the base station device 101 can determine the priority of CCs in use and CC candidates based on the acquired information, and determine CCs to be enabled / disabled.

[0035] When an event occurs, the terminal device 111 may autonomously decide to activate CCs that are not currently activated or to disable CCs that are currently activated. In this case, the terminal device 111 may determine the number of CCs to activate depending on the amount of data accumulated in the RLC buffer, etc. The terminal device 111 may notify the base station device 101 of the CCs to be activated / deactivated, and the information may be stored on the network side.

[0036] In this manner, in this embodiment, CC candidates are set for the terminal device 111, a CC to be actually used (enabled) is selected from the CC candidates, and the selected CC is enabled. This makes it possible to flexibly change the CC used in the terminal device 111. This allows the terminal device 111 to use a CC with good wireless quality depending on the situation, thereby improving communication efficiency.

[0037] In the above example, a method for selecting a CC to be enabled or disabled from the configured candidate CCs was described. However, information about secondary CC candidates may also be added or deleted in response to the occurrence of a predetermined event. For example, the base station device may instruct a terminal device to measure the wireless quality of a CC not configured as a secondary CC candidate. The terminal device may determine that an event has occurred when the wireless quality of a CC not configured as a secondary CC candidate exceeds a predetermined threshold and report the occurrence of the event to the base station device. Based on this report, the base station device may then set the CC as a new secondary CC candidate. Furthermore, the terminal device may determine that an event has occurred when the wireless quality of a CC configured as a secondary CC candidate falls below a predetermined threshold and report the occurrence of the event to the base station device. In this case, the base station device may remove the CC from the secondary CC candidates. Furthermore, an event may be determined to have occurred when the wireless quality of a CC not configured as a secondary CC candidate exceeds the wireless quality of a CC configured as a secondary CC candidate for a certain period of time, and the secondary CC candidate may be replaced.

[0038] (Device configuration) Using FIG. 4, an example of the hardware configuration of a base station device (base station device 101 or 102) and a terminal device 111 will be described. In one example, the base station device and the terminal device include a processor 401, a ROM 402, a RAM 403, a storage device 404, and a communication circuit 405. The processor 401 is a computer including one or more processing circuits, such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and performs overall processing of the device and each of the above-mentioned processes by reading and executing programs stored in the ROM 402 or the storage device 404. The ROM 402 is a read-only memory that stores information such as programs and various parameters related to the processes executed by the base station device and the terminal device. The RAM 403 functions as a workspace when the processor 401 executes a program, and is also a random access memory that stores temporary information. The storage device 404 is, for example, a removable external storage device. The communication circuit 405 is, for example, a circuit for LTE or 5G wireless communication. 4 illustrates one communication circuit 405, the base station device and the terminal device may have multiple communication circuits. For example, the base station device and the terminal device may have a common antenna for both LTE and 5G wireless communication circuits. The base station device and the terminal device may have separate antennas for LTE and 5G.

[0039] 5 is a diagram showing an example of the functional configuration of a terminal device. The terminal device includes, for example, a capability information notification unit 501, an information acquisition unit 502, a candidate CC setting unit 503, and a CC activation unit 504. These functional units can be implemented, for example, by the processor 401 executing a program stored in the ROM 402 or the storage device 402. However, this is not limitative, and for example, some or all of these functional units may be implemented using dedicated hardware. Note that, since the processing to be executed by the terminal device has been described above, only a rough outline of the functional configuration of the terminal device will be given here.

[0040] The capability information notification unit 501 notifies the base station device of the capability information (UE Capability) of the terminal device itself. Note that this capability information includes information indicating a combination of frequency bands that the terminal device can use when communicating using multiple CCs in multiple frequency bands in DC or CA. The information acquisition unit 502 acquires configuration information for using one or more CCs corresponding to one or more frequency bands that are not limited or constrained by the notified combination of usable frequency bands as described above. The candidate CC configuration unit 503 configures one or more CCs based on the acquired configuration information. That is, for example, if the terminal device can use the combination of Band 1 and Band 41 or the combination of Band 1 and Band 42, but cannot use the combination of Band 41 and Band 42, and the CC of Band 1 is set as the primary CC, configuration information for both Band 41 and Band 42 is acquired as information on candidates for the secondary CC, and configuration is performed so that CCs in those frequency bands are usable. That is, in the past, only information on frequency bands that are actually used was acquired and configuration was performed, but in this embodiment, configuration information is also acquired and configuration is performed for frequency bands that are not actually used. The CC validation unit 504 validates CCs that are actually used among the CCs set by the candidate CC setting unit 503, and also invalidates CCs that are in use when they are no longer in use. The CC validation unit 504 selects CCs to be validated based on the combinations of available frequency bands described above. That is, for example, if a terminal device can use the combination of band 1 and band 41 or the combination of band 1 and band 42, but cannot use the combination of band 41 and band 42, processing is performed so that both band 41 and band 42 are not validated.

[0041] The information acquiring unit 502 may further acquire information regarding the number of CCs to be activated. The information regarding the number of CCs to be activated may indicate the maximum number of CCs that are permitted to be activated, or the number of CCs that should actually be activated. The information acquiring unit 502 may acquire, from the base station device, information indicating a combination of frequency bands that cannot be activated together (e.g., temporarily prohibited). The information acquiring unit 502 may acquire, from the base station device, information indicating a combination of frequency bands that can be activated together. The CC enabling unit 504 may determine the CCs to be activated in response to an instruction from the base station device, or may autonomously select CCs to be activated and notify the base station device of information indicating which CCs have been activated after activation. The candidate CC setting unit 503 may delete the configured information in a predetermined case, such as when the primary CC is changed or when an instruction is received from the base station device. If each piece of configuration information includes an expiration date, the candidate CC setting unit 503 may delete the configuration information when the expiration date has elapsed. In addition, when a CC (cell) that is not set as a candidate CC is detected in the terminal device, the information acquisition unit 502 may request the base station device to add that CC as a candidate CC, and receive setting information regarding that CC from the base station device.

[0042] 6 is a diagram showing an example of the functional configuration of a base station device. The base station device includes, for example, a capability information receiving unit 601, an information notifying unit 602, and an activation information acquiring unit 603. These functional units can be implemented, for example, by the processor 401 executing a program stored in the ROM 402 or the storage device 402. However, this is not limitative, and for example, some or all of these functional units may be implemented using dedicated hardware. Note that, since the processing to be executed by the base station device has been described above, only a rough outline of the functional configuration of the base station device will be given here.

[0043] The capability information receiving unit 601 receives the above-mentioned terminal device capability information (UE Capability) from the terminal device. The information notifying unit 602 notifies the terminal device of the configuration information received from the terminal device for using one or more CCs corresponding to one or more frequency bands that are not limited or constrained by the combination of frequency bands that the terminal device can use. The information notifying unit 602 transmits a secondary cell addition request to other base station devices that are expected to provide communication using the one or more CCs, and acquires information such as communication parameters to be used in the cell. The information notifying unit 602 can then notify the terminal device of configuration information including the communication parameter information. The configuration information may include expiration date information. The activation information acquiring unit 603 acquires information indicating which CCs have been activated among the configured candidate CCs in the terminal device. The activation information acquiring unit 603 may, for example, generate and acquire information indicating which CCs to activate within the terminal device. The activation information acquiring unit 603 can specify the CCs to be activated by the terminal device by notifying the terminal device of the generated information. Furthermore, when the terminal device autonomously determines a CC to be activated, the activation information acquisition unit 603 can receive information indicating the activated CC from the terminal device.

[0044] The information notification unit 602 may further notify the terminal device of information regarding the number of CCs to be activated. The information regarding the number of CCs to be activated may indicate the maximum number of CCs that are permitted to be activated, or may indicate the number of CCs that should actually be activated. The information notification unit 602 may also notify the terminal device of information indicating a combination of frequency bands that cannot be activated together (for example, that are temporarily prohibited). The information notification unit 602 may also notify the terminal device of information indicating a combination of frequency bands that can be activated together. When the information notification unit 602 receives a request from the terminal device to add a CC (cell) that has been detected in the terminal device and has not been set as a candidate CC as a candidate CC, the information notification unit 602 may notify the terminal device of setting information regarding the CC.

[0045] (Processing flow) Next, an example of the flow of processing executed in a wireless communication system will be described. Note that, since variations in processing executed by a base station device and a terminal device have been described above, only an overview of the main processing executed between the base station device and the terminal device will be described here, and details will not be repeated. Fig. 7 shows an example of the flow of processing when a terminal device autonomously determines and activates a CC to be used, and Fig. 8 shows an example of the flow of processing when a base station device determines a CC to be used in a terminal device and transmits an instruction to the terminal device.

[0046] 7 and 8, the terminal device notifies the base station device of capability information (UE Capability) including information on the combination of frequency bands that the terminal device can use (S701, S801). Note that the base station device may configure CCs for CA or DC using a conventional method based on this capability information. In this embodiment, for flexible CC operation, CCs that may be used for CA or DC are configured in the terminal device without being restricted by the information on the combination of frequency bands that the terminal device can use simultaneously, which is indicated by the capability information (S702, S802). For example, the base station device transmits to the terminal device configuration information for using CCs for all frequency bands that the terminal device can use (regardless of the combination). This configuration can be performed in the same way as conventional CC configuration, but configuration is performed so that CCs will not be used unless they are enabled. The terminal device pre-configures candidate CCs to be used based on the information from the base station device (S703, S803).

[0047] 7, the terminal device independently selects a CC to be activated and activates the selected CC (S704).Then, the terminal device notifies the base station device of information indicating which CC has been activated (S705).

[0048] 8, the base station device determines a CC to be activated by the terminal device (S804) and transmits an instruction to activate the CC to the terminal device (S805). The terminal device then activates the candidate CC specified in the instruction as the CC to be used (S806). Note that the determination of the CC to be activated and the transmission of the instruction to activate the CC may be performed, for example, at the same timing as the transmission of the instruction in S802. That is, in S802, information indicating the CC to be activated at that time may be transmitted to the terminal device together with information on the candidate CCs. In this case, for example, in response to a change in the wireless environment of the terminal device, a wireless quality measurement report may be transmitted from the terminal device to the base station device, and the base station device may determine the CC to be activated and the CC to be deactivated based on the measurement report and notify the terminal device of the determination result.

[0049] It should be noted that the processing in Figure 7 and the processing in Figure 8 may be combined, that is, either the processing in Figure 7 or the processing in Figure 8 may be selectively executed depending on the situation.

[0050] In the example of FIG. 8, the base station device providing the primary CC determines whether to enable or disable a candidate CC for the terminal device. However, in DC, for example, the base station device providing the secondary CC may also make this determination. That is, the above determination may be made by either the base station device providing the primary CC or the base station device providing the secondary CC. For example, the wireless quality measurement results in the terminal device are notified to the base station device providing the primary CC, and the base station device determines the CC to be enabled based on the wireless quality. The base station device then notifies the other base station devices providing the CC to be enabled of the result of this determination. This notification may be made using, for example, an S-NODE MODIFICATION REQUEST or an RRC TRANSFER. Alternatively, for example, a new Xn message may be defined and notification may be made using this message. The other base station devices that receive this notification respond to the notification. The other base station devices may also refuse connection to the terminal device. For example, another base station device may notify the base station device of the rejection decision using an S-NODE MODIFICATION REQUEST ACKNOWLEDGE or an RRC TRANSFER, or may notify the base station device of the decision using a newly defined Xn message. In this case, the base station device may not activate the rejected CC. Then, the base station device may summarize the results and transmit to the terminal device an instruction to specify the CC to be activated. Note that if it is not possible to activate all secondary CCs, the base station device may also instruct the terminal device to continue measurement.

[0051] Furthermore, when a base station device providing a secondary CC is connected to a terminal device via SRB3 (Signaling Radio Bearer 3), it can receive measurement results for each secondary CC candidate from the terminal device. Based on these measurement results, the base station device providing the secondary CC can select a CC to be activated in a manner similar to the determination made by the base station device providing the primary CC described above. Similarly to the method performed by the base station device providing the primary CC, the base station device providing the secondary CC may also send a message to other base station devices providing the candidate CC, and if rejected, remove the candidate CC from the list of CCs to be activated. After determining the CC to be activated, the base station device providing the secondary CC may transmit information indicating the CC, for example, directly to the terminal device. Furthermore, the first base station device providing the secondary CC may provide this information to the second base station device providing the primary CC, and have the second base station device transmit the information to the terminal device.

[0052] As described above, in this embodiment, CC candidates are set in the terminal device, a CC to be actually used (enabled) is selected from the CC candidates, and the selected CC is enabled. This makes it possible to flexibly change the CC used in the terminal device. This allows the terminal device to use a CC with good wireless quality depending on the situation, thereby improving communication efficiency.

[0053] 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, a notification means for notifying a base station device of information indicating a combination of frequency bands that can be used by the terminal device when communication is performed using a plurality of component carriers having different frequency bands; an acquisition means for acquiring, from the base station device, information on a plurality of settings corresponding to each of a plurality of component carriers corresponding to a plurality of frequency bands included in any of the combinations of usable frequency bands, the information on a plurality of settings for using the corresponding component carriers not being limited to the combinations of usable frequency bands; a configuration means for configuring the plurality of component carriers based on the acquired configuration information; an enabling means for enabling a component carrier included in the set plurality of component carriers based on the combination of the available frequency bands; A terminal device comprising:

2. 2. The terminal device according to claim 1, wherein the acquisition means further acquires information on the number of component carriers to be enabled from the base station device.

3. 3. The terminal device according to claim 1, wherein the acquisition unit further acquires, from the base station device, information indicating a combination of component carriers that cannot both be enabled.

4. 4. The terminal device according to claim 1, wherein the acquisition means further acquires, from the base station device, information indicating a combination of component carriers that can be enabled together.

5. 2. The terminal device according to claim 1, wherein the enabling unit enables a component carrier included in the set plurality of component carriers based on an instruction from the base station device based on the combination of the available frequency bands.

6. The terminal device according to claim 5 , wherein the acquisition means acquires information including an index that identifies a combination of component carriers to be enabled from the base station device.

7. 7. The terminal device according to claim 6, wherein the acquiring means acquires an index indicating a combination of component carriers to be enabled from any one of a Radio Resource Control (RRC) message, a Downlink Control Information (DCI), or a System Information Block, and acquires an instruction to enable the combination of component carriers from a Medium Access Control (MAC) Element (CE).

8. The terminal device according to claim 7 , wherein the acquisition means acquires, from the base station device, an instruction to delete information about the enabled component carrier.

9. A control method executed by a terminal device, comprising: notifying a base station device of information indicating a combination of frequency bands that can be used by the terminal device when communication is performed using a plurality of component carriers having different frequency bands; acquiring, from the base station device, information on a plurality of settings corresponding to each of a plurality of component carriers corresponding to a plurality of frequency bands included in any of the combinations of usable frequency bands, the plurality of settings being for using the corresponding component carriers and not limited to the combinations of usable frequency bands; configuring the plurality of component carriers based on the acquired configuration information; enabling component carriers included in the set plurality of component carriers based on the combination of available frequency bands; A control method comprising:

10. The computer provided in the terminal device notifying a base station device of information indicating a combination of frequency bands that can be used by the terminal device when communication is performed using a plurality of component carriers having different frequency bands; acquires, from the base station device, information on a plurality of settings corresponding to each of a plurality of component carriers corresponding to a plurality of frequency bands included in any of the combinations of usable frequency bands, the information on a plurality of settings for using the respective corresponding component carriers, and is not limited to the combinations of usable frequency bands; configuring the plurality of component carriers based on the acquired configuration information; activating component carriers included in the set plurality of component carriers based on the combination of the available frequency bands; Program for.

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