Terminal, control method, and program for efficient connection processing

Abstract

To efficiently perform setting processing using Reference Config and DeltaConfig related to conditional handover and conditional addition or change of a secondary cell in terminal.SOLUTION: The terminal device acquires, from a base station device to which the terminal device is connected, information for generating configuration information for a candidate cell that is a target of addition or change of a conditional secondary cell (CPACC), the information including a reference configuration and a delta configuration corresponding to a difference between the configuration information and the reference configuration, and a condition for executing the CPACC, and generates configuration information for communication in the candidate cell by using the delta configuration and the reference configuration for the candidate cell. With respect to the generated setting information, appropriateness of the setting information regarding whether the setting information is usable by the terminal is determined, and in response to a condition being satisfied, CPAC is executed using the generated setting information usable by the terminal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a technology for improving the efficiency of wireless connection processing. [Background technology]

[0002] In cellular communication systems, handover techniques are used to ensure communication continuity by switching the connection destination of a terminal device in response to factors such as the movement of the terminal device. A standard handover technique involves initiating a handover configuration process on the core network side after the communication quality of the currently connected wireless link in the terminal device deteriorates, and then transmitting an instruction message from a base station device to the terminal device. However, this technique requires time for the process from the actual deterioration of communication quality to the transmission of the handover instruction, which can result in a prolonged period of time during which communication is unavailable or communication quality is insufficient. In response to this, the Third Generation Partnership Project (3GPP (registered trademark)) is discussing a technique in which this configuration process is performed in advance, and when a predetermined condition is satisfied in the terminal device, the terminal device switches the connection destination cell without receiving an instruction message from a base station device (see Non-Patent Document 1). The predetermined condition includes, for example, when the wireless quality of a neighboring cell becomes better than the wireless quality of the currently connected cell by a predetermined level or more, or when the wireless quality of the currently connected cell falls below a predetermined value. This method significantly reduces the time during which communication is unavailable or communication quality is insufficient because the handover setup process in the core network is completed before a deterioration in communication quality that would require handover occurs. This type of handover is called conditional handover, or CHO.

[0003] Similarly, in multi-connectivity (MC) or the like in which a terminal device is connected to multiple cells, a setting process is performed in advance, and when a predetermined condition is satisfied in the terminal device, the terminal device can add or change a secondary cell without receiving an instruction message from the base station device. Note that, hereinafter, this conditional addition or change of a secondary cell may be referred to as CPAC. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TR38.874, V16.0.0, December 2018 Summary of the Invention [Problem to be solved by the invention]

[0005] In the study of the 3GPP Release 18 standard, it was agreed that the above-mentioned configuration process should be performed using a common reference configuration for multiple candidate cells and a delta configuration that specifies a configuration value different from the reference configuration for each candidate cell. However, the execution procedure for such a configuration process has not been clarified, and it is necessary to define an efficient procedure.

[0006] The present invention provides a method for efficiently performing configuration processing using a reference configuration and a delta configuration for conditional handover in a terminal device or for adding or changing a conditional secondary cell. [Means for solving the problem]

[0007] According to another aspect of the present invention, a terminal device has an acquisition means for acquiring information for generating configuration information for multiple cells for conditional handover (CHO) or conditional secondary cell addition or modification (CPAC) from a base station device to which it is connected, the information including a reference configuration common to two or more of the multiple cells and assigned with identification information that uniquely identifies the reference configuration, a delta configuration unique to each of the two or more cells, and the identification information of the reference configuration to which the delta configuration should be combined, and conditions for executing the CHO or the CPAC; a generation means for generating configuration information for communication in at least one of the two or more cells using the delta configuration and the reference configuration specified by the identification information to be combined with the delta config; and an execution means for executing the CHO or the CPAC using the generated configuration information in response to the condition being met. [Effects of the Invention]

[0008] According to the present invention, it is possible to efficiently perform configuration processing using a reference config and a delta config regarding conditional handover in a terminal device or the addition or change of a conditional secondary cell. [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. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication system. [Figure 3] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication system. [Figure 4] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication system. [Figure 5] FIG. 10 is a diagram illustrating an example of the flow of a setting information update process. [Figure 6] FIG. 10 is a diagram illustrating an example of the flow of a process for determining the appropriateness of setting information. [Figure 7] FIG. 10 is a diagram illustrating an example of the flow of a process for determining the appropriateness of setting information. [Figure 8] FIG. 2 is a diagram illustrating an example of the hardware configuration of an MN, an SN, and a terminal device. [Figure 9] FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. [Figure 10] FIG. 2 is a diagram illustrating an example of a functional configuration of an MN. [Figure 11] FIG. 10 is a diagram illustrating an example of the functional configuration of an SN. DETAILED DESCRIPTION OF THE INVENTION

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

[0011] Fig. 1 shows an example of the configuration of a wireless communication system according to this embodiment. This wireless communication system is a cellular communication system that complies with a cellular communication standard such as the fifth generation (5G) standard defined by the Third Generation Partnership Project (3GPP (registered trademark)). Note that this is just one example, and the following discussion can be applied to any system in which a terminal device can continue communication while switching the cell to which it is connected.

[0012] In the wireless communication system of FIG. 1, a base station device provides wireless communication services to a terminal device 151. The terminal device 151 can be connected to two or more cells in parallel. Of these two or more cells, a cell that controls the communication of the terminal device 151 is called a primary cell, and a cell that connects to the terminal device 151 under the control of the base station device of the primary cell (master node: MN100) is called a secondary cell. Note that in this embodiment, for simplicity of explanation, it is assumed that the terminal device 151 is connected to the MN100 and additionally connects to a secondary cell. The example of FIG. 1 shows an example in which cells that are candidate connection destinations as secondary cells for the terminal device 151 are provided by two base station devices (secondary nodes: SN101 and SN102).

[0013] A base station device may be configured with a central unit (CU) and distributed units (DUs). The DU includes, for example, an antenna and radio frequency signal processing functions, and functions as an interface for transmitting and receiving radio signals to and from terminal devices. Each DU forms at least one cell. Meanwhile, the CU accommodates one or more DUs and is configured to control communications performed by these DUs. For example, the CU generates setting information when a terminal device connects to each DU and notifies the terminal device of the setting information. In the example of FIG. 1, the SN 101 functions as a CU, and can provide cells 131 to 133, respectively, using DUs 111 to 113. Similarly, the SN 102 functions as a CU, and provides cells 141 to 143, respectively, using DUs 121 to 123. The terminal device 151 is configured to connect to at least one of these cells and receive radio signals in the connected cell, thereby receiving radio communication services. Note that the terminal device 151 connects to a base station device that constitutes a cell that includes the location where the terminal device 151 itself is located, and hereinafter this will be referred to as "connecting to a cell (provided by that base station device)."

[0014] In this embodiment, pre-configuration for adding or changing a secondary cell is performed when the terminal device 151 establishes a connection with the primary cell, or when the radio quality in the currently connected secondary cell deteriorates to a certain degree, for example. The pre-configuration state here refers to a state in which the settings of parameters and the like for the case in which the terminal device 151 connects to a candidate cell to which the terminal device 151 is to connect have been completed, while the terminal device 151 does not actually establish a connection to that cell. The pre-configuration includes conditions for connecting to a cell for changing or adding a cell to which the terminal device 151 is to connect, and when the terminal device 151 determines that the conditions are satisfied, the terminal device 151 establishes synchronization with the new cell to which the terminal device 151 is to connect and attempts a connection. When changing the secondary cell to which the terminal device 151 is to connect, the terminal device 151 performs a disconnection process from the secondary cell from which the terminal device 151 is connected. Using such pre-configuration, the terminal device 151 autonomously switches or adds a secondary cell when it determines that the conditions are satisfied is called conditional secondary cell addition or change (CPAC). The terminal device 151 autonomously switches the primary cell to which the terminal device 151 is to connect when it determines that the conditions are satisfied is called conditional handover (CHO). Although the following embodiment will be described with a focus on CPAC, it can also be applied to CHO. That is, by replacing the conditions of CPAC with the conditions of CHO and the presettings for CPAC with the presettings for CHO, the following discussion can be applied to CHO. Note that the types of messages may differ between CHO and CPAC, but those skilled in the art can substitute appropriate messages as appropriate.

[0015] When CPAC is performed, the connected MN 100 transmits a secondary cell addition request message (SgNB Addition Request) to another base station device that provides a cell that is a candidate for the secondary cell to be added or changed. Note that this secondary cell addition request may be initiated, for example, in response to a predetermined message (e.g., SgNB Change Required) being notified to the connected MN 100 from a base station device that provides a secondary cell to which the terminal device 151 is currently connected. In this case, the MN 100 may transmit the above-described secondary cell addition request in response to receiving the predetermined message. Then, the other base station device that provides a cell that is a candidate for the secondary cell to be added or changed (hereinafter, this base station device may be referred to as a "candidate base station") transmits a response message (SgNB Addition Request Acknowledge) to the message to the MN 100, including information such as communication parameters to be used when the terminal device 151 adds or changes the secondary cell. Here, the candidate base station holds the transmitted information such as the communication parameters as pre-configured information. Furthermore, the MN 100 or the candidate base station determines conditions that should be satisfied when adding or changing the secondary cell. Then, the MN 100 notifies the terminal device 151 of preconfiguration information including information on communication parameters that should be used when adding or changing the secondary cell to a cell provided by the candidate base station as the secondary cell, and conditions for performing such connection. This notification can be performed using, for example, a radio resource control (RRC) message. In one example, the preconfiguration information is notified to the terminal device 151 by an RRC Reconfiguration message.

[0016] Here, the pre-configuration information may include reference configuration information (Reference Config) that serves as a reference, and configuration information (Delta Config) that is a difference between each configuration information of a secondary cell candidate and the reference config. The Reference Config is configuration information common to multiple cells, and the Delta Config is information about the part of the configuration information of each cell that differs from the Reference Config. In other words, the Delta Config is configuration information that is unique to each cell. When the terminal device 151 receives the Reference Config and the Delta Config, it uses the configuration values ​​of the configuration items included in the Delta Config. On the other hand, the terminal device 151 uses the configuration values ​​specified in the Reference Config for the configuration items that are not included in the Delta Config and that are specified to need to be maintained in the Reference Config (specified as "Need M"), and may not use the configuration values ​​of the Reference Config for the other configuration items. Furthermore, for a setting item that is not included in the delta config and that is specified in the reference config as requiring an operation related to the setting item to be performed only once (designated as "Need N"), the terminal device 151 may be notified from the MN 100 to the terminal device 151 of information for determining whether to execute the operation related to the setting item only once in accordance with the setting value of the reference config, or to interpret this as an intention to delete the setting value of the reference config and determine not to execute the operation related to the setting item. In this case, the MN 100 and the terminal device 151 may be configured in advance to perform one of the operations in a fixed manner without requiring notification of this information. By using such a combination of the reference config and the delta config, it is possible to reduce the amount of data of setting information notified to the terminal device 151.That is, configuration information common to N cells is notified to the terminal device 151 only once for the multiple cells as the reference config, and configuration information specific to each cell is notified to each cell by the delta config, thereby omitting notification of the portion of the configuration information for the (N-1) cells that corresponds to the reference config, thereby reducing the amount of data of the configuration information to be notified. Also, the MN 100 can use the configuration information of one of multiple candidate cells as the reference config, or use the configuration information of the serving cell currently used for communication (when multiple cells are used as serving cells, any one of the multiple cells) as the reference config, or use the configuration information of a cell other than the candidate cell or the serving cell as the reference config. In this case, the MN 100 can notify the terminal device 151 of information for specifying which cell's configuration information to use as the reference config. As an example, when MN100 uses the configuration information of one of multiple serving cells (or candidate cells) as a reference configuration, it can efficiently specify the configuration information to be used as the reference configuration using existing identification information such as CellGroupId, SCellIndex, and condReconfigId that are uniquely assigned to the configuration information.

[0017] As described above, the delta config is composed of the configuration items in each cell's configuration information that include different setting values ​​from the reference config. Therefore, the smaller the difference between each cell's configuration information and the reference config, the fewer the number of configuration items included in the delta config, and the smaller the overall data volume of the delta config. On the other hand, if there is a large discrepancy between each cell's configuration information and the reference config, the number of configuration items included in the delta config will increase, and the amount of data will also increase. In some cases, almost all of the configuration items in the reference config will be replaced by the delta config's configuration items, which may increase the overall data volume of the configuration information.

[0018] In this embodiment, in consideration of such circumstances, a plurality of reference configurations can be set, and the terminal device 151 is notified of the plurality of reference configurations, as well as information indicating which of the plurality of reference configurations the delta configuration for each candidate cell is based on. For example, the MN 100 First reference configuration (Reference configuration ID = 1) Second reference configuration (Reference configuration ID=2) Cell 131 information (first delta config, reference config ID = 1) Cell 132 information (second delta configuration, reference configuration ID = 1) ... Cell 142 information (5th delta config, reference config ID = 2) Cell 143 information (6th delta config, reference config ID=2) is notified to the terminal device 151. Here, the reference config ID is identification information that can uniquely identify one reference config. Of this information, information on the first reference config and the second reference config is notified to the terminal device 151 as information elements such as ReferenceConfigAddModlist. Also, information on the delta config specific to each cell is notified to the terminal device 151 as a CondReconfigToAddMod information element. The CondReconfigToAddMod information element is prepared, for example, for each candidate cell. The CondReconfigToAddMod information element includes identification information (condReconfigId) specific to the information element, and, for each cell, information indicating the cell identifier, the reference config ID, the conditions under which CPAC should be performed, and the delta config of that cell. Note that CPAC refers to the conditional addition and change of a secondary cell, and different conditions can be prepared for the addition of a secondary cell and the change of a secondary cell. For example, the terminal device 151 may extract a first reference configuration from the received information regarding the cell 131 using information with reference configuration ID=1, and generate configuration information for the cell 131 based on the first reference configuration and the first delta configuration. Similarly, the terminal device 151 may generate configuration information for the cell 143 using the second reference configuration and the sixth delta configuration. With this configuration, even if the configuration information for connection between the cell 131, the cell 132, and the cell 143 is significantly different, it is possible to eliminate the disadvantage of using a common reference configuration. Note that in any of the cells, the reference configuration itself may be used as the configuration information for that cell. In other words, the configuration information of any of the cells may be used as the reference configuration. For example, the configuration information of the cell 131 may be used as the first reference configuration, and / or the configuration information of the cell 143 may be used as the second reference configuration. In this case, for example, the MN 100 may First Reference Config (Cell 131, Reference Config ID = 1) Second Reference Config (Cell 143, Reference Config ID = 2) Cell 132 information (second delta configuration, reference configuration ID = 1) ... Cell 142 information (5th delta config, reference config ID = 2) is notified to the terminal device 151. Note that this is just one example, and information in other formats may be notified to the terminal device 151 as long as the terminal device 151 is able to configure the configuration information for each cell. Note that the configuration information for each cell includes not only communication parameters but also CPAC conditions (condExecutionCond, conditions for adding / changing a cell, and an identifier for specifying a separately defined execution condition).

[0019] In one example, a different reference configuration may be used for each SN, or a common reference configuration may be used for multiple SNs and another reference configuration may be used for one or more other SNs. Also, multiple reference configurations may be used within one SN. A group of cells using such a common reference configuration may be determined, for example, by the MN 100 to which the terminal device 151 is connected, or may be determined by the SN, or such a group of cells may be determined between the MN 100 and the SN 101 and SN 102. Also, a group using a common reference configuration may be determined in advance.

[0020] Next, several examples of the flow of the process of determining the reference config and the delta config will be described.

[0021] First, as a first example, a case where the MN 100 determines a reference configuration will be described. When the MN 100 determines a reference configuration, it notifies the SN that provides a cell that uses the reference configuration of the reference configuration. The SN determines the difference between the setting information in each cell that it provides and the notified reference configuration as the delta configuration of the cell, and notifies the MN 100. Note that the SN may reject the use of the notified reference configuration. In this case, the SN may notify the MN 100 of another reference configuration to be used instead of the notified reference configuration and a delta configuration generated based on the other reference configuration. Note that the MN 100 may notify the SN of identification information (reference configuration ID) of the reference configuration to be notified to the SN, and one or more identification information that can be assigned to another reference configuration when the use of the reference configuration is rejected. In this case, when notifying the MN 100 of the above-mentioned different reference configuration, for example, the SN can notify the MN 100 of the identification information assigned to the different reference configuration.

[0022] For example, as shown in FIG. 2, MN 100 transmits an SgNB addition request including a first reference configuration (Reference config #1) to SN 101 (S201). SN 101 accepts the use of this first reference configuration and notifies each subordinate DU (DU 111 to DU 113) of this first reference configuration to generate a delta configuration (S202). Each DU prepares configuration information for connection of UE 151 to its own device and notifies SN 101 of a delta configuration, which is information on the difference between this configuration information and the first reference configuration (S205). Note that SN 101 may request each DU to notify it of the configuration information for connection of UE 151, and the DU may notify SN 101 of the configuration information. In this case, SN 101 may generate a delta configuration for each DU from the first reference configuration and the notified configuration information. When the SN 101 acquires the delta config for each DU, it can notify the MN 100 of the information on the delta config (S207). Note that the SN 101 may notify the MN 100 that it is using the first reference config notified by the MN 100. Note that the notification from the SN to the MN 100 can be performed by using, for example, an information element in an SgNB addition request ACK. For example, the information can be notified by a CG-CandidateList. Also, a newly defined information element other than the CG-CandidateList may be used. This information exchange may be performed by any message that can be used for information exchange via the Xn interface between the MN 100 and the SN.

[0023] On the other hand, the MN 100 transmits an SgNB addition request including a second reference configuration (Reference config #2) to the SN 102 (S203). The SN 102 may reject the use of this second reference configuration and notify each subordinate DU (DU 121 to DU 123) of the third reference configuration to generate a delta configuration (S204). Each DU prepares configuration information for connecting the UE 151 to its own device, and notifies the SN 102 of a delta configuration, which is information on the difference between the configuration information and the third reference configuration (S206). In this case, as in the above case, each DU may notify the SN 102 of the configuration information itself, and the SN 102 may generate a delta configuration using the third reference configuration. When the SN 102 acquires the delta configuration for each DU, it may notify the MN 100 of the delta configuration information (S208). In this case, the SN 102 notifies the MN 100 of the third reference configuration that is being used instead of the second reference configuration.

[0024] Note that information transmission and reception between the CU and DU of the SN may be performed using an information element (IE) related to CPAC included in a UE context setup request, a UE context setup request response, a UE context release request, a UE context release command, a UE context release complete, a UE context modification request, or a UE context modification response. Furthermore, a new IE for communication setup using a reference configuration may be prepared in an existing F1 interface message, or a new F1 interface message may be prepared. This also applies to the following description. Information from a CU to a DU may be notified using a CU to DU RRC information information element, and information from a DU to a CU may be notified using a DU to CU RRC information information element. Note that when multiple cells are formed in one DU, information specifying which cell the information transmitted and received relates to may also be transmitted and received between the DU and the CU.

[0025] When MN 100 acquires the delta configuration for each cell that is a candidate cell for the secondary cell in this way, MN 100 notifies UE 151 of the delta configuration and information on the reference configuration (S209). In the example of FIG. 2, a first reference configuration related to configuration information of cells under control of SN 101, a third reference configuration related to configuration information of cells under control of SN 102, and the delta configuration of each cell are notified to UE 151. Here, as described above, each delta configuration is notified to UE 151 together with information (reference configuration ID) indicating which reference configuration it is associated with. In the example of FIG. 2, UE 151 is notified that the delta configurations of DU 111 to DU 113 are associated with the first reference configuration, and that the delta configurations of DU 121 to DU 123 are associated with the third reference configuration.

[0026] Next, as a second example, an example in which an SN determines a reference configuration will be described. As shown in FIG. 3, the MN 100 transmits an SgNB addition request to the SNs 101 and 102. In this SgNB addition request, the MN 100 can notify the SNs that a reference configuration and a delta configuration should be generated. At this time, the MN 100 can also notify each SN of usable reference configuration IDs. This can define the maximum number of reference configurations that can be set in an SN. In the example of FIG. 3, the SN 101 is notified of reference configuration IDs=1 and 2 (S301), and the SN 102 is notified of reference configuration IDs=3 and 4 (S304). Note that in the example of FIG. 3, the MN 100 notifies the SNs of the reference configuration IDs so that the MN 100 and the SNs have the same understanding of the reference configuration IDs and so that the reference configuration IDs used in each SN do not overlap. However, this is just an example, and the same ID may be set in multiple SNs. For example, a reference configuration ID may be specified by combining identification information indicating the SN with the ID. In other words, the reference configuration of SN101 with reference configuration ID=1 and the reference configuration of SN102 with reference configuration ID=1 may be mutually different configurations. In this case, Reference configuration of SN=101 First reference configuration (Reference Config ID = 1) Second reference configuration (Reference Config ID = 2) Reference configuration of SN=102 Third reference configuration (Reference configuration ID = 1) Delta config with SN=101 Cell 131 information (first delta config, reference config ID=1) Cell 132 information (second delta config, reference config ID=1) Cell 133 information (third delta config, reference config ID=2) Delta config with SN=102 Cell 141 information (4th delta config, reference config ID=1) Cell 142 information (5th delta config, reference config ID=1) Cell 143 information (6th delta config, reference config ID=1) Such information is notified from the MN 100 to the terminal device 151 (S310). For example, when acquiring configuration information of the cell 132, the terminal device 151 extracts a first reference configuration based on SN=101 and reference configuration ID=1. Then, the terminal device 151 can acquire the configuration information of the cell 132 using the first reference configuration and the second delta configuration. On the other hand, for example, when acquiring configuration information of the cell 143, the terminal device 151 extracts a third reference configuration based on SN=102 and reference configuration ID=1. Then, the terminal device 151 can acquire the configuration information of the cell 143 using the third reference configuration and the sixth delta configuration. Note that, in the above example, an example has been described in which one reference configuration is identified by combining identification information of each SN and a reference configuration ID, but the present invention is not limited to this. For example, more generally, a group of cells may be defined, and one reference configuration may be identified based on the identification information of the group of cells and a reference configuration ID. Here, the group of cells may be multiple cells under multiple SNs. Here, cells under one SN may belong to one group, or one or more cells under one SN may belong to a first group, and other cells under that SN may belong to a second group. Even in this configuration, two or more reference configurations set in two or more groups may be identified using only the reference configuration ID, but by using the reference configuration ID in combination with the identification information of the group, it is possible to uniquely identify one reference configuration.

[0027] Note that the maximum number of SNs that provide candidate cells may be specified in the MN 100. In this case, when configuration information related to cells provided by SNs exceeding the maximum number is to be configured, the MN 100 can instruct the SNs to use normal configuration information (full configuration) as is for the SNs exceeding the maximum number without using the reference configuration and delta configuration. In this case, the SN can instruct the subordinate DUs to provide the full configuration instead of the delta configuration.

[0028] Note that, when the use of overlapping reference configuration IDs is permitted in multiple SNs (or groups of cells), for example, a numerical value indicating the maximum number of reference configurations that can be set in the SN may be notified to each SN. Note that, in addition to the reference configuration IDs notified as described above so that distinct reference configuration IDs are used in multiple SNs, a numerical value indicating the maximum number of reference configurations that can be set in each SN may be notified. As an example, the MN 100 may hold the maximum number of reference configurations that can be set in the terminal device 151, and determine the number of reference configurations that can be further set in the terminal device 151 from the number of reference configurations currently being set (notified) and this maximum number. Then, the MN 100 may determine the above-mentioned maximum number to be notified to each SN based on this number. Also, the MN 100 may notify the SNs only that a reference configuration and a delta configuration should be generated, without notifying the numerical value indicating the maximum number or the reference configuration ID. For example, if the maximum number of reference configurations is predetermined in the SN, it is sufficient to be notified that only the reference configuration and delta configuration should be generated.

[0029] Each SN sets a reference configuration within the range of the maximum number of reference configurations that can be set for each SN. The SN can then notify each of its subordinate DUs of the reference configuration and instruct them to generate a delta configuration (S302, S303, S305). The DU generates a delta configuration based on the notified reference configuration and notifies the SN of the generated delta configuration (S306, S307). The SN aggregates the delta configurations generated in each DU and notifies the MN 100 of all the set reference configurations and delta configurations (S308, S309). The delta configuration is notified to the MN 100 together with information indicating which reference configuration it is associated with. For example, the SN 101 notifies the MN 100 that the delta configs of DU 111 and DU 112 are associated with the reference config with reference config ID=1, and that the delta config of DU 113 is associated with the reference config with reference config ID=2. In the above example, the SN generates a reference config, notifies the DU of the generated reference config, and the DU generates the delta config, but this is not limiting. For example, the SN may request the DU to provide setting information to be notified to the terminal device 151, aggregate the setting information, and generate a reference config based on the setting information. For example, the SN may generate a reference config that minimizes the total data amount of the delta config and the reference config using a common reference config for multiple setting information.

[0030] It should be noted that the SN does not need to use all of the notified reference configuration IDs. In the example of Fig. 3, the SN 102 can use reference configuration IDs = 3 and 4, but can use only one reference configuration (reference configuration ID = 3) and generate delta configurations for DU 121 to DU 123 based on this reference configuration. Then, the SN 102 notifies the MN 100 of all of these delta configurations and reference configurations, and that all delta configurations are associated with the reference configuration with reference configuration ID = 3. Thereafter, the MN 100 notifies the terminal device 151 of the acquired reference configurations and delta configurations, and information indicating which reference configuration each delta configuration is associated with.

[0031] As a third example, when the MN 100 does not have a reference configuration, it can instruct the SN to generate a reference configuration and a delta configuration, and when it has a reference configuration, it can notify the SN of the reference configuration and instruct the SN to generate a delta configuration. For example, as shown in Fig. 4, while the MN 100 does not have a reference configuration, it instructs the SN 101 to generate a reference configuration and a delta configuration (S401). Then, the SN 101 can generate a reference configuration within its own device, for example, and instruct the DUs 111 to 113 to generate delta configurations (S402). Note that the example in Fig. 4 shows an example in which the SN 101 generates a reference configuration, notifies the DUs 111 to 113 of the generated reference configuration, and the DUs 111 to 113 generate delta configurations, but the present invention is not limited to this. For example, the SN 101 may request the DUs 111 to 113 to provide setting information to be notified to the terminal device 151, and may aggregate the setting information to generate a reference config. In either case, the SN 101 notifies the MN 100 of the acquired reference config and the delta config for the cell formed by each DU (S403, S404).

[0032] Thereafter, the MN 100 instructs the SN 102 to generate a delta configuration (S405). In this case, since the MN 100 has the reference configuration notified by the SN 101, it can notify the SN 102 of the reference configuration and instruct it to generate a delta configuration. The SN 102 may accept or reject the use of this reference configuration. In the example of FIG. 4, it is assumed that the SN 102 rejects the use of this reference configuration and decides to use another reference configuration. In this case, the SN 102 notifies the DUs 121 to 123 of this other reference configuration (S406), and the DUs 121 to 123 generate a delta configuration based on the other reference configuration. Then, the SN 102 can collect the delta configurations from the DUs 121 to 123 (S407) and notify the MN 100 of the delta configuration (S408). The SN 102 may, for example, collect configuration information from each of the DUs 121 to 123 and generate a delta configuration candidate based on the difference between the configuration information and the reference configuration notified from the MN 100. If the amount of data in the delta configuration exceeds a predetermined value, the SN 102 may generate another reference configuration. This is just an example, and the criteria for the SN 102 to generate another reference configuration may be determined arbitrarily. The MN 100 notifies the terminal device 151 of the reference configuration it holds and the collected delta configuration (S409).

[0033] As described above, after the processing of Fig. 4 is completed, the MN 100 will hold the first reference configuration used in the SN 101 and the second reference configuration used in the SN 102. Thereafter, when the MN 100 is to pre-configure yet another cell as a secondary cell candidate, the MN 100 can notify the SN of the first reference configuration and the second reference configuration and instruct the SN to generate a delta configuration. In this way, the MN 100 can notify the SN of all of the reference configurations it holds and instruct the SN to generate a delta configuration. However, this is just one example, and the MN 100 may, for example, notify the SN of only a part of the reference configurations it holds and instruct the SN to generate a delta configuration.

[0034] As described above, the terminal device 151 can acquire the reference configuration and the delta configuration for multiple cells that are candidates for addition or change as secondary cells. The MN 100 may transmit an instruction to the terminal device 151 to activate only some of these multiple cells. For example, as the terminal device 151 moves, the MN 100 can activate pre-configuration for cells within a predetermined distance from the location of the terminal device 151 and disable the pre-configuration for other cells. The terminal device 151 can, for example, recreate and store configuration information for cells for which pre-configuration is enabled, using the reference configuration and the delta configuration. Note that the terminal device 151 can measure the radio quality for activated cells and not measure the radio quality for non-activated cells. The MN 100 can specify cells to be activated / deactivated, for example, by using identification information (condReconfigId) unique to an information element for each cell. When enabling / disabling multiple cells that use a common reference configuration at once, you can specify the reference configuration ID of that reference configuration. For example, Reference Config ID=1: Disabled Reference Config ID=2: Partially valid condReconfigId=A: Enabled condReconfigId=B: Disabled Reference Config ID=3: All enabled Such information may be notified to the terminal device 151. In the above example, when a reference configuration is partially enabled, information indicating whether each delta configuration that uses that reference configuration is enabled is specified, and when a reference configuration is fully enabled, all delta configurations that use that reference configuration are enabled. However, this is not limited to this, and the reference configuration may be set to "enabled" in both cases where only a portion of the delta configurations that use the reference configuration are enabled and where all of the delta configurations are enabled, and in that case, the enabled / disabled status may always be indicated individually for each delta configuration that uses that reference configuration.

[0035] The terminal device 151 measures the radio quality of the (enabled) cell to be measured, and in response to determining that the condition for adding / changing a secondary cell is satisfied for a specific cell, notifies the MN 100 of an RRC Reconfiguration Complete message and accesses the specific cell. That is, the terminal device 151 can execute a random access procedure to access the specific cell.

[0036] Note that the terminal device 151 maintains the configuration information related to the candidate cell even after the secondary cell is added or changed, but it is assumed that this configuration information should be deleted, for example, when the terminal device 151 moves far away from the candidate cell. Also, it can be assumed that at least one of the reference configuration and the delta configuration needs to be changed, for example, when a certain amount of time has passed since the reference configuration and the delta configuration were notified to the terminal device 151. Such deletion or change of the configuration is performed, for example, by an instruction from the MN 100.

[0037] The MN 100 or SN connected to the terminal device 151 can decide to delete the reference config set in the terminal device 151, for example, in response to a change or addition of a secondary cell candidate, or in response to the setting of new communication parameters based on the reference config and delta config. Hereinafter, the MN 100 or SN connected to the terminal device 151 may be referred to as the "network." Note that a network node other than the MN 100 or SN may decide to delete the reference config set in the terminal device 151, and the deletion instruction may be transmitted to the terminal device 151 via the MN 100 or SN.

[0038] For example, the network may decide to delete one of the reference configurations when the number of configured reference configurations reaches (exceeds) the maximum number. The network may, for example, transmit an instruction to the terminal device 151 to delete the oldest reference configuration. The network may also determine the reference configuration to delete based on the measurement results of wireless quality in the terminal device 151. For example, the network may identify the maximum wireless quality of the cells using each of multiple reference configurations and decide to delete the reference configuration with the lowest maximum value (or the reference configuration that is not used in a cell whose wireless quality can be determined to be good). The network may also delete delta configurations for cells that are more than a predetermined distance away from the location of the terminal device 151, for example, as the terminal device 151 moves, and may decide to delete the specific reference configuration when all delta configurations that refer to the specific reference configuration have been deleted. The network may also instruct the terminal device 151 that has set a reference configuration to delete the reference configuration, and have the terminal device 151 select which reference configuration to delete. In this case, the terminal device 151 may select and delete a reference configuration, and notify the network of the reference configuration ID of the deleted reference configuration.

[0039] The network removes cells that have generated delta configurations using the reference configuration to be deleted from the secondary cell candidates for the terminal device 151. For example, the MN 100 can transmit an SgNB Release Request to an SN that has a cell using the reference configuration to be deleted under its control, instructing it to delete configuration information related to the cell. Note that when a specific reference configuration is deleted and delta configurations that refer to the specific reference configuration are maintained, all of the delta configurations are also deleted. Furthermore, the cell corresponding to the delta configuration is removed from the secondary cell candidates. Note that when a specific reference configuration is deleted and delta configurations that refer to the specific reference configuration are maintained, the delta configurations may be reconfigured based on a different reference configuration. Note that in this case, the MN 100 can specify a different reference configuration and instruct an SN that has a cell using the delta configuration under its control to update the delta configuration. Note that in this case, the SN may be forced to use a different reference configuration. That is, an SN may not be permitted to reject the use of another reference configuration. For example, assume that in a state in which reference configurations with reference configuration IDs = 1 and 2 are being used in one SN, deletion of the reference configuration with reference configuration ID = 2 is decided. In this case, the MN 100 may instruct the SN to reconfigure a delta configuration based on the reference configuration with reference configuration ID = 2 using the reference configuration with reference configuration ID = 1. Note that a reference configuration being used in any cell may not be deleted.

[0040] Furthermore, even when the terminal device 151 stops using the secondary cell or performs handover of the primary cell, the reference config and delta config may not be deleted unless there is an explicit instruction from the MN 100. However, this is not limited to this. For example, the reference config generated in the handover source MN 100 may be deleted. On the other hand, the reference config generated in the SN may not be deleted. In this case, the handover source MN 100 may notify the handover destination MN 100 of the reference config ID and the corresponding contents of the reference config, the SN that generated the reference config, information on candidate cells for the secondary cell, etc. Furthermore, the handover source MN 100 may notify the handover destination MN 100 of information on the delta config (delta config ID, delta config contents, and conditions for adding / changing a cell corresponding to the delta config) that references the reference config. This eliminates the need to re-execute the setting process for adding / changing a secondary cell in the handover destination MN 100. Furthermore, when the use of the secondary cell is stopped, when a handover of the primary cell is performed, when the use of the primary cell is stopped or suspended (when the RRC state transitions from connected mode to idle mode or inactive mode), etc., the terminal device 151 can voluntarily delete the reference config and / or the delta config without waiting for an explicit instruction from the MN 100. In this case, the dynamic memory for holding the reference config on the network side can be reduced, and there is no need to perform processing for sharing the reference config and the delta config with other base station devices, which simplifies the implementation on the network side.

[0041] When the reference configuration is changed, a "delta reference configuration" may be used, which indicates only the setting items in the reference configuration that should be changed. For setting items set in the delta reference configuration, the reference configuration may be changed based on the value of that setting item, while the reference configuration may be maintained for other setting items. In this case, changing the reference configuration may also change the delta configuration. For this reason, a "delta-delta configuration" may be used, which indicates only the setting items in the delta configuration that should be changed. For setting items set in the delta-delta configuration, the delta configuration may be changed based on the value of that setting item, while the delta configuration for other setting items may be maintained. In this way, when the reference configuration (and delta configuration) is changed, only the difference values ​​are exchanged between the MN 100, SN, and terminal device, making it possible to update the configuration information with a small amount of data. Note that when the reference configuration or delta configuration is significantly changed, the delta-reference configuration or delta-delta configuration may not be used, and the reference configuration or delta configuration previously used may be replaced with a newly generated reference configuration or delta configuration. In other words, the reference configuration or delta configuration previously used may be deleted, and the newly generated reference configuration or delta configuration may be stored in the terminal device 151.

[0042] When changing the reference configuration, the network notifies the terminal device 151 of either (1) a delta reference configuration or (2) a newly generated reference configuration. When the terminal device 151 receives the delta reference configuration, it replaces the configuration items specified by the delta reference configuration among the configuration items of the currently used reference configuration with the configuration values ​​of the delta reference configuration. When the terminal device 151 receives a newly generated reference configuration, it replaces the entire reference configuration it holds with the newly generated reference configuration. When there is a change in a configuration item not specified by the delta configuration for each cell that uses the reference configuration, the terminal device 151 changes the configuration item for that cell and updates the configuration information. With this configuration, even if a change is made to the reference configuration, there may be cases where the configuration information for each cell is not updated due to the delta configuration. However, the terminal device 151 maintains the updated reference configuration for use in generating configuration information using the delta configuration of another cell thereafter. When updating a reference config, the reference config to be updated can be specified using a reference config ID. The updated reference config may inherit the reference config ID of the reference config before the update, or a new reference config ID may be assigned to the updated reference config.

[0043] On the other hand, when changing the delta config, the network notifies the terminal device 151 of either (1) the delta-delta config or (2) a newly generated delta config. When the terminal device 151 receives the delta-delta config for a specific cell, it replaces the configuration items specified by the delta-delta config among the configuration items of the delta config currently being used for that cell with the configuration values ​​of the delta-delta config. Also, when the terminal device 151 receives a newly generated delta config for a specific cell, it replaces the entire delta config of that cell that it holds with the newly generated delta config. Note that when updating the delta config, the delta config to be updated can be specified by a cell identifier or condReconfigId. When the delta config is changed, the terminal device 151 updates the configuration information of the cell that uses that delta config. The terminal device 151 updates the setting information by changing the setting items of the updated delta config in the setting information of the cell corresponding to the updated delta config in accordance with the update of the delta config.

[0044] Note that the network may notify the terminal device 151 of a delta reference configuration for the existing first reference configuration and may instruct the terminal device 151 to maintain the first reference configuration as is when transmitting an instruction to generate a second reference configuration. For example, when the second reference configuration is to be used as the reference configuration for some cells among a plurality of cells using the first reference configuration and the first reference configuration is to be used as the reference configuration for the other cells, a new second reference configuration based on the existing first reference configuration may be generated and the first reference configuration may be maintained. Note that in this case, a new reference configuration ID may be assigned to the second reference configuration, and the reference configuration ID may be notified to the terminal device 151. Note that when the MN 100 decides to change the reference configuration, the MN 100 may instruct the SN using that reference configuration to change the reference configuration in the same manner as in the notification to the terminal device 151 described above. Furthermore, when the SN decides to change the reference configuration, the SN requests the MN 100 to change the reference configuration by specifying the reference configuration, and if the request is permitted, the MN 100 can change the reference configuration. In this case, if the MN 100 permits the change of the reference configuration, it notifies the SN of information indicating the permission, and also notifies the terminal device 151 of the permitted reference configuration.

[0045] In the above description, the process for updating either the reference configuration or the delta configuration has been described. However, as shown in FIG. 5, both the reference configuration and the delta configuration may be updated. That is, it is determined whether the reference configuration or the delta configuration should be updated (S501, S503). If the reference configuration should be updated (YES in S501), the delta-reference configuration or a newly prepared reference configuration is provided to the terminal device (and the SN, if necessary) (S502). Similarly, if the delta configuration should be updated (YES in S503), the delta-delta configuration or a newly prepared delta configuration is provided to the terminal device (and the SN, if necessary) (S504).

[0046] The terminal device 151 may generate configuration information for each cell based on the acquired reference configuration and delta configuration, but it is necessary to confirm whether the configuration information is appropriate. For example, the terminal device 151 may determine that the configuration information is inappropriate if the configuration information includes parameters that exceed the capabilities of the terminal device (i.e., the terminal device 151 cannot execute). The terminal device 151 may also determine that the configuration information is inappropriate if the configuration information does not include necessary parameters or if the terminal device 151 cannot interpret the contents of the configuration information. For example, if the reference configuration is accidentally deleted, the necessary parameters may not exist with only the delta configuration, and the configuration information is therefore determined to be inappropriate.

[0047] For example, as shown in FIG. 6, when the terminal device 151 acquires the reference config and delta config for a secondary cell candidate (S601), it generates configuration information for the cell using the information (S602) and determines whether the configuration information is appropriate (S603). That is, the terminal device 151 determines whether the configuration information can be used for a cell in which an environment for preparing configuration information exists (where the reference config and delta config are available). Then, if the configuration information generated by combining the reference config and delta config is appropriate, the terminal device 151 maintains the configuration information. On the other hand, if the configuration information is not appropriate, the terminal device 151 notifies the network (the connected MN 100 or SN) of the reference config ID and the delta config identification information (condReconfigId) (S604). This notification is performed, for example, by an RRC Reconfiguration Complete message. Here, information indicating that an error has occurred is notified to the network. This notification can be performed, for example, by setting the failure type in the message to srb3-IntegrityFailure or scg-reconfigFailure. Upon receiving this notification, the network notifies the terminal device 151 of the reference config, delta config, and reference config ID based on the identification information of the reference config ID and delta config. Note that the terminal device 151 may determine which of the reference config part and the delta config part is inappropriate, and notify the network to transmit the configuration that caused the inappropriateness. Note that if parameters that cannot be used by the terminal device 151 have been configured, the network can instruct the SN to reconfigure the reference config or delta config. In this way, the terminal device 151 can determine the appropriateness of the configuration information before actually adding / changing a secondary cell, and can prepare appropriate configuration information in advance.

[0048] 7, the terminal device 151 may not generate configuration information at the time of acquiring the reference configuration and the delta configuration, but may generate configuration information for, for example, a cell whose wireless quality measurement results satisfy a predetermined condition (S701, S702). In this case, the terminal device 151 checks the appropriateness of the generated configuration information (S703). If the terminal device 151 determines that the generated configuration information is inappropriate, it may subsequently generate configuration information for another cell whose wireless quality measurement results satisfy a predetermined condition. Note that even if there is no secondary cell whose wireless quality measurement results satisfy a predetermined condition, the terminal device 151 may switch connection to another cell whose wireless quality is better than that of the current secondary cell if the configuration information in that cell is appropriate. If inappropriate configuration information is present, the terminal device 151 may notify the network of the inappropriate configuration information as described above (S704). In one example, after connecting to a cell with appropriate configuration information, the terminal device 151 can notify the network of the reference configuration ID and delta configuration identification information (condReconfigId) corresponding to the inappropriate configuration information using UE assistance information. Upon receiving this notification, the network modifies the reference configuration and delta configuration based on the reference configuration ID and delta configuration identification information, and notifies the terminal device 151 of the reference configuration, delta configuration, and reference configuration ID again. In this way, by not generating the configuration information at the time the reference configuration and delta configuration are acquired, but generating the configuration information when predetermined conditions such as wireless quality conditions are satisfied and evaluating the appropriateness of the configuration information, it is possible to reduce the memory capacity required to store the configuration information in the terminal device 151.

[0049] When the configuration information of the serving cell is used as the reference configuration, the configuration information of the serving cell may be changed between the time when the reference configuration and the delta configuration are acquired and the time when the measurement result of the radio quality of one of the candidate cells satisfies a predetermined condition. In this case, the reference configuration will also be changed, and therefore the generated configuration information may be different between the case where the configuration information of the cell is generated using the reference configuration and the delta configuration when the information is acquired and the case where the configuration information of the cell is generated when the measurement result of the radio quality of the candidate cell satisfies a predetermined condition. Therefore, the network and the terminal device 151 need to agree on the time when the cell configuration information is generated. For this reason, information specifying the timing at which the cell configuration information is generated may be notified from the network to the terminal device 151. Alternatively, the network and the terminal device 151 may be configured in advance to generate the cell configuration information at a fixed timing that is set in advance without notifying the information.

[0050] When using the configuration information of the serving cell as the reference config, the terminal device 151 may save the configuration information of the serving cell held by the terminal device 151 as the reference config at the time when the reference config and delta config are acquired. Also, in order to reduce the memory capacity for saving the configuration information in the terminal device 151, it is also possible to not save the reference config at the time when the reference config and delta config are acquired, but to save the configuration information of the serving cell at that time as the reference config in response to the satisfaction of predetermined conditions such as wireless quality conditions. Note that when the terminal device 151 saves the configuration information of the serving cell as the reference config at the time when the terminal device 151 acquires the reference config and delta config, it is expected that the contents of the serving cell configuration information and the reference config will no longer match when it receives a serving cell configuration change instruction from the network after saving the reference config. Therefore, in order to prevent this inconsistency, when a serving cell configuration change instruction is received from the network after the reference configuration is saved, an instruction may be transmitted from the network to terminal device 151 to make the same changes to both the serving cell and the reference configuration. In this case, instead of instructing the terminal device 151 to make overlapping changes, the network may instruct only the serving cell configuration change, and terminal device 151 may voluntarily make the same changes to the reference configuration as the serving cell configuration without any explicit instruction.

[0051] Furthermore, two types of information are defined for each setting item of the setting information related to a cell: mandatory (essential) and optional (non-essential). If a mandatory (essential) setting item is not notified to the terminal device 151, the setting information is determined to be inappropriate. Therefore, a message format for notifying conventional setting information related to a cell that does not use a reference configuration must include mandatory (essential) setting items. However, when setting information is generated using a reference configuration and a delta configuration, mandatory (essential) setting items among the setting items related to a candidate cell may be notified by including them in the delta configuration rather than in the reference configuration. In this case, mandatory (essential) setting items may be omitted from the reference configuration.

[0052] FIG. 8 is a diagram illustrating an example of the hardware configuration of the MN 100, SN, and terminal device 151 described above. In one example, the MN 100, SN, and terminal device 151 are configured to include a processor 801, a ROM 802, a RAM 803, a storage device 804, and a communication circuit 805. The processor 801 is a computer configured to include one or more processing circuits, such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and executes the overall processing of the MN 100, SN, and terminal device 151 and each processing described below by reading and executing programs stored in the ROM 802 or storage device 804. The ROM 802 is a read-only memory that stores information such as programs and various parameters related to the processing executed by the MN 100, SN, and terminal device 151. The RAM 803 functions as a workspace when the processor 801 executes a program, and is also a random access memory that stores temporary information. The storage device 804 is configured, for example, by a removable external storage device. The communication circuit 805 is a communication circuit including a wired interface or a wireless interface for the MN 100, the SN, and the terminal device 151 to communicate with each other.

[0053] FIG. 9 is a diagram outlining an example of the functional configuration of the terminal device 151. Note that each functional unit shown in FIG. 9 may be realized, for example, by the processor 801 executing a program stored in the ROM 802 or the like, or dedicated hardware may be provided to realize each function. Also, FIG. 9 particularly illustrates functions related to the processing according to this embodiment, and the terminal device 151 may naturally have the functions of a normal terminal device that performs communication in accordance with, for example, the 3GPP (registered trademark) cellular communication standard. Also, two or more functional blocks shown in FIG. 9 may be integrated into one functional block, or one functional block may be divided into multiple functional blocks. The terminal device 151 includes, as its functions, a reference configuration acquisition unit 901, a delta configuration acquisition unit 902, a setting information generation unit 903, an appropriateness determination unit 904, and an information notification unit 905, for example. Note that, although the functions of the secondary cell are described here, the terminal device 151 may also have similar functions for a candidate cell to which the primary cell is to be handed over.

[0054] The reference configuration acquisition unit 901 acquires, for example, from the MN 100, a reference configuration that can be used for configuration information of a candidate cell for adding / changing a secondary cell. The reference configuration acquisition unit 901 acquires information associating a reference configuration with its reference configuration ID. The delta configuration acquisition unit 902 acquires a delta configuration that is used to generate configuration information for each of the above-mentioned candidate cells. The delta configuration is information unique to a cell, and is acquired in a format associated with a reference configuration ID to indicate with which reference configuration the delta configuration should be used in combination. Note that the reference configuration and the delta configuration can be acquired together (in one message) from the MN 100, but this is not necessarily limited to this. That is, the reference configuration may be acquired in a first message, and the delta configuration may be acquired in a second message different from the first message. Furthermore, when the configuration information is updated, only either the reference configuration or the delta configuration may be notified to the terminal device 151. The configuration information generation unit 903 combines the acquired delta config with a reference config having a reference config ID associated with the delta config, and generates configuration information for a candidate cell associated with the delta config. The configuration information generation unit 903 may generate the configuration information when the reference config and delta config are acquired, or may generate the configuration information for a cell whose wireless quality measured in the terminal device 151 satisfies a predetermined condition, and not generate the configuration information unless the predetermined condition is satisfied. The appropriateness determination unit 904 evaluates whether the configuration information generated by the configuration information generation unit 903 is usable by the terminal device 151, whether any required parameters are missing, whether the terminal device 151 can interpret the information, and so on, and determines whether the configuration information is appropriate. If the configuration information is inappropriate, the information notification unit 905 sends a predetermined notification to the connected MN 100 or SN.Thereafter, when at least one of the reference config and the delta config is updated, the information is acquired by the reference config acquisition unit 901 or the delta config acquisition unit 902, and the setting information can be updated.

[0055] FIG. 10 is a diagram outlining an example of the functional configuration of the MN 100. Note that each functional unit shown in FIG. 10 may be realized, for example, by the processor 801 executing a program stored in the ROM 802 or the like, or dedicated hardware for realizing each function may be provided. Also, FIG. 10 particularly shows functions related to the processing according to this embodiment, and the MN 100 may naturally have the functions of a normal base station device that performs communication in accordance with, for example, the 3GPP (registered trademark) cellular communication standard. Also, two or more functional blocks shown in FIG. 10 may be integrated into one functional block, or one functional block may be divided into multiple functional blocks. The MN 100 includes, as its functions, a setting generation instruction unit 1001, a reference configuration acquisition unit 1002, a delta configuration acquisition unit 1003, an update processing unit 1004, and an information notification unit 1005, for example. Note that although the secondary cell will be described here, the MN 100 may also have similar functions for a candidate cell to which the primary cell is to be handovered.

[0056] The configuration generation instruction unit 1001 instructs an SN having a secondary cell candidate cell under its control to generate configuration information for connection to that cell. Here, the configuration generation instruction unit 1001 instructs the SN to generate configuration information, for example, in the form of a combination of a reference config and a delta config. For example, when the number of reference configs reaches a maximum, the configuration generation instruction unit 1001 can instruct the SN to generate a full config so that no new reference configs will be configured thereafter. The reference config acquisition unit 1002 can, for example, generate a reference config in its own device. Also, for example, the reference config acquisition unit 1002 can receive a reference config generated in an SN from that SN. The delta config acquisition unit 1003 acquires, from the SN, a delta config unique to each cell under the SN. The delta config is associated with a reference config ID indicating which reference config it should be combined with. For example, when at least one of the reference config and the delta config needs to be updated, the update processing unit 1004 sends an instruction to the SN to generate a new reference config and a new delta config. After the update processing unit 1004 sends this instruction, at least one of the updated reference config and the new delta config is acquired by the reference config acquisition unit 1002 or the delta config acquisition unit 1003. The information notification unit 1005 provides the acquired reference config and the new delta config to the terminal device 151. The information notification unit 1005 can notify the terminal device 151 of information including a reference config ID indicating which reference config the delta config should be combined with.

[0057] FIG. 11 is a diagram outlining an example of the functional configuration of the SN101 and SN102. Note that each functional unit shown in FIG. 11 may be realized, for example, by the processor 801 executing a program stored in the ROM 802 or the like, or dedicated hardware may be provided to realize each function. Also, FIG. 11 particularly illustrates functions related to the processing according to this embodiment, and the SN101 and SN102 may naturally have the functions of a normal base station device that performs communication in accordance with, for example, the 3GPP (registered trademark) cellular communication standard. Also, two or more functional blocks shown in FIG. 11 may be integrated into a single functional block, or a single functional block may be divided into multiple functional blocks. The SN101 and SN102 each include, for example, an instruction receiving unit 1101, a reference configuration acquiring unit 1102, a delta configuration acquiring unit 1103, and an information notifying unit 1104 as their functions. Although the secondary cell will be described here, a base station device that is a candidate for the MN, instead of the SN, can have the same function as a candidate cell for handover of the primary cell.

[0058] The instruction receiving unit 1101 receives an instruction from the MN. For example, the instruction receiving unit 1101 may receive a message from the MN instructing the MN to generate a delta configuration. The instruction receiving unit 1101 may further receive an instruction from the MN indicating that a reference configuration should be generated. For example, when the instruction receiving unit 1101 receives an instruction including a reference configuration generated by the MN, the instruction receiving unit 1101 may identify that the instruction is an instruction to generate a delta configuration. When the instruction receiving unit 1101 receives an instruction not including a reference configuration, the instruction receiving unit 1101 may identify that the instruction is an instruction to generate a reference configuration and a delta configuration. The instruction receiving unit 1101 may receive an instruction to update at least one of the reference configuration and the delta configuration from the MN. The reference configuration acquiring unit 1102 may acquire, for example, the reference configuration included in the instruction received by the instruction receiving unit 1101. Furthermore, the reference configuration acquisition unit 1102 generates and acquires a new reference configuration, for example, when the instruction received by the instruction receiving unit 1101 does not include a reference configuration or when refusing to use the reference configuration included in the instruction. The delta configuration acquisition unit 1103 acquires, as a delta configuration, the difference between the setting information for communication in the subordinate cell and the reference configuration acquired by the reference configuration acquisition unit 1102. Note that the delta configuration acquisition unit 1103 may, for example, cause a subordinate DU to generate a delta configuration and acquire the generated delta configuration from the DU. The information notification unit 1104 notifies the MN of information about the acquired delta configuration. Note that, when a reference configuration is generated in the SN, the information notification unit 1104 notifies the MN of the reference configuration. The information notification unit 1104 notifies the MN of a reference configuration ID, which indicates which reference configuration the delta configuration should be combined with, in association with the delta configuration.

[0059] At least a part of the functions of the MN described above may be performed by the SN to which the terminal device 151 is connected.

[0060] As described above, according to this embodiment, it is possible to appropriately configure and manage the configuration information for communication in a cell to which a terminal device is to newly connect, using the reference config and delta config. Therefore, it is possible to efficiently perform configuration processing using the reference config and delta config related to conditional handover in the terminal device and the addition or change of a conditional secondary cell. This makes it possible to contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), which is to "Develop resilient infrastructure, promote sustainable industrialization and foster innovation."

[0061] 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, An acquisition means for acquiring, from a connected base station device, information for generating configuration information regarding a candidate cell that is a target of a conditional secondary cell addition or change (CPAC), the information including a reference configuration and a delta configuration corresponding to a difference between the configuration information and the reference configuration, and a condition for executing the CPAC; A generation means for generating the setting information for communication in the candidate cell using the delta configuration and the reference configuration for the candidate cell; a determination means for determining the appropriateness of the setting information generated by the generation means, the appropriateness being whether the setting information is a setting that can be used by the terminal device; an execution means for executing the CPAC using the generated setting information that is usable by the terminal device in response to the condition being satisfied; A terminal device comprising:

2. The terminal device according to claim 1, further comprising a notification means for transmitting a notification including information indicating that an error has occurred to the connected base station device when the determination of the appropriateness by the determination means results in an inappropriateness.

3. 3. The terminal device according to claim 2, wherein the notification includes scg-reconfigFailure as information indicating that the error has occurred.

4. A control method executed by a terminal device, comprising: an acquisition process for acquiring, from a connected base station device, information for generating configuration information regarding a candidate cell that is a target of a conditional secondary cell addition or change (CPAC), the information including a reference configuration and a delta configuration corresponding to a difference between the configuration information and the reference configuration, and a condition for executing the CPAC; A generation step of generating the setting information for communication in the candidate cell using the delta configuration and the reference configuration for the candidate cell; a determination step of determining the appropriateness of the setting information generated in the generation step, the appropriateness being whether the setting information is a setting that can be used by the terminal device; an execution step of executing the CPAC using the generated setting information that is usable by the terminal device in response to the condition being satisfied; A control method comprising:

5. The computer provided in the terminal device acquires, from a connected base station device, information for generating configuration information regarding a candidate cell that is a target of a conditional secondary cell addition or change (CPAC), the information including a reference configuration and a delta configuration corresponding to a difference between the configuration information and the reference configuration, and a condition for executing the CPAC; For the candidate cell, generating the configuration information for communication in the candidate cell using the delta configuration and the reference configuration; determining the appropriateness of the generated setting information, the appropriateness being whether the setting information is a setting that can be used by the terminal device; In response to the condition being satisfied, the CPAC is executed using the generated setting information that is usable by the terminal device. Program for.

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