Base station device, terminal device, control method, and program for efficient management of connection setting information

Abstract

To efficiently perform setting processing using a reference config and a delta config regarding a conditional handover or a conditional secondary cell addition or change in a terminal device.SOLUTION: In a wireless communication system, a base station device provides a terminal device with information including a reference config common to two or more cells, a delta config unique to each of the two or more cells, and identification information on the reference config to which the delta config should be combined, for generating configuration information regarding multiple cells for conditional handover (CHO) or conditional secondary cell addition or change (CPAC) in a connected terminal device, and when at least one of the reference config and the delta config should be deleted or modified, the base station device specifies at least one of the reference config and the delta config and instructs the terminal device to delete or modify it.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a technique for efficiently managing wireless connection settings. [Background technology]

[0002] In a cellular communication system, in order to ensure the continuity of communication, a handover technique is used to switch the connection destination of a terminal device according to the movement of the terminal device. In a standard handover method, after the communication quality of the connected wireless link in the terminal device deteriorates, a setting process for handover on the core network side is started, and an instruction message is transmitted from the base station device to the terminal device. However, in this method, since it takes time for the process from the actual deterioration of the communication quality to the transmission of the handover instruction, the time during which communication is not possible or the communication quality is insufficient may be prolonged. In response to this, the Third Generation Partnership Project (3GPP (registered trademark)) is discussing a method of performing this setting process in advance, and switching the connection destination cell without receiving an instruction message from the base station device when a certain condition is satisfied in the terminal device (see Non-Patent Document 1). The certain condition includes, for example, a case in which the wireless quality of the neighboring cell becomes better than the wireless quality of the connected cell by a certain level or more in the terminal device, or a case in which the wireless quality of the connected cell becomes equal to or lower than a certain 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 occurs that would require a handover to be performed. This type of handover is called conditional handover, or CHO.

[0003] Similarly, in a multi-connectivity (MC) 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, the 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 config for multiple candidate cells and a delta config that specifies a configuration value different from the reference config for each candidate cell. However, the execution procedure of 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 config and a delta config for conditional handover in a terminal device or for conditional addition or change of a secondary cell. [Means for solving the problem]

[0007] A base station device according to one embodiment of the present invention has an acquisition means for acquiring information for generating configuration information regarding a plurality of cells for conditional handover (CHO) or conditional secondary cell addition or modification (CPAC) in a connected terminal device, the information including a reference config common to two or more of the plurality of cells and assigned with identification information that uniquely identifies the reference config, a delta config unique to each of the two or more cells, and the identification information of the reference config to which the delta config is to be combined, a provision means for providing the information and conditions for executing the CHO or the CPAC to the terminal device, and an instruction means for, when at least one of the reference config and the delta config should be deleted or modified, specifying at least one of the reference config and the delta config and instructing the terminal device to delete or modify the reference config and the delta config.

[0008] According to another aspect of the present invention, a terminal device includes an acquisition means for acquiring, from a connected base station device, information for generating configuration information related to a plurality of cells for a conditional handover (CHO) or a conditional secondary cell addition or change (CPAC), the information including a reference config common to two or more cells among the plurality of cells and assigned with identification information that uniquely identifies the reference config, a delta config unique to each of the two or more cells, and the identification information of the reference config to which the delta config should be combined, and a condition for executing the CHO or the CPAC; The communication device has a generating means for generating, for at least one of the two or more cells, configuration information for communication in the cell using the delta config and the reference config specified by the identification information to be combined with the delta config, an execution means for, when a deletion or modification instruction specifying at least one of the reference config and the delta config is received, executing the deletion or modification of at least one of the specified reference config and 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 satisfied. Effect of the Invention

[0009] According to the present invention, it is possible to efficiently perform configuration processing using a reference config and a delta config regarding a conditional handover in a terminal device or a conditional addition or change of a secondary cell. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a wireless communication system. [Diagram 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. [Diagram 5] FIG. 11 is a diagram illustrating an example of the flow of a setting information update process. [Figure 6] FIG. 11 is a diagram illustrating an example of the flow of a process for determining the appropriateness of setting information. [Figure 7] FIG. 11 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. 2 is a diagram illustrating an example of the functional configuration of an SN. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the multiple features described in the embodiments may be arbitrarily combined. In addition, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0012] 1 shows a configuration example of a wireless communication system according to the present embodiment. The wireless communication system is, for example, a cellular communication system conforming to a cellular communication standard such as the fifth generation (5G) standard defined by the 3rd Generation Partnership Project (3GPP (registered trademark)). Note that this is only one example, and the following discussion can be applied to any system in which a terminal device can continue communication while switching a connected cell.

[0013] In the wireless communication system of FIG. 1, a base station device provides a wireless communication service 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 (master node: MN100) of the primary cell is called a secondary cell. Note that in this embodiment, for the sake of 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 candidates for connection destinations as secondary cells of the terminal device 151 are provided by two base station devices (secondary nodes: SN101 and SN102).

[0014] The base station device may be configured with a central unit (CU) and a distributed unit (DU). The DU includes, for example, an antenna and a signal processing function of radio frequency, and functions as an interface for transmitting and receiving radio signals with a terminal device. Each DU forms at least one cell. Meanwhile, the CU is configured to accommodate one or more DUs and control the 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. In the example of FIG. 1, the SN 101 has a function as a CU, and can provide cells 131 to 133 by DUs 111 to 113, respectively. Similarly, the SN 102 has a function as a CU, and provides cells 141 to 143 by DUs 121 to 123, respectively. The terminal device 151 is configured to receive a radio communication service by connecting to at least one of these cells and transmitting and receiving radio signals in the connected cell. Terminal device 151 connects to a base station device that configures a cell that includes the location where terminal device 151 itself is located, and in the following, this will be referred to as "connecting to a cell (provided by that base station device)."

[0015] In this embodiment, when the terminal device 151 establishes a connection with the primary cell, or when the wireless quality in the connected secondary cell deteriorates to a certain degree, a pre-setting for adding or changing a secondary cell is performed. The state in which the pre-setting is performed here is a state in which the setting of parameters and the like in the case where the terminal device 151 connects to a candidate cell to which the connection is made is completed, and the terminal device 151 does not actually establish a connection to the cell. The pre-setting includes a condition for connecting to a cell for changing or adding a cell to which the connection is made, and when the terminal device 151 determines that the condition is satisfied, the terminal device 151 establishes synchronization with a new cell to which the connection is made and attempts a connection. When changing the secondary cell to which the connection is made, the terminal device 151 performs a disconnection process from the secondary cell from which the connection is made. Using such a pre-setting, a process in which the terminal device 151 autonomously switches or adds a secondary cell in response to determining that the condition is satisfied is called a conditional secondary cell addition or change (CPAC). A process in which the terminal device 151 autonomously switches a primary cell to which the connection is made in response to determining that the condition is satisfied is called a conditional handover (CHO). Although the following embodiment will be described with a focus on CPAC, it can also be applied to CHO. That is, the following discussion can be applied to CHO by replacing the conditions of CPAC with the conditions of CHO, and the presettings for CPAC with the presettings for CHO. Note that the types of messages may differ between CHO and CPAC, but those skilled in the art can replace them with appropriate messages as appropriate.

[0016] 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 the base station device that provides the secondary cell to which the terminal device 151 is currently connected. In this case, the MN 100 may transmit the above-mentioned secondary cell addition request in response to receiving the predetermined message. Then, the other base station device (hereinafter, this base station device may be referred to as a "candidate base station") that provides a cell that is a candidate for the secondary cell to be added or changed 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 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 to be used when adding or changing a secondary cell to a cell provided by the candidate base station as a secondary cell, and conditions for such connection. This notification can be performed, for example, by using a radio resource control (RRC) message. In one example, the preconfiguration information is notified to the terminal device 151 by an RRC Reconfiguration message.

[0017] Here, the information of the pre-configuration information may include reference configuration information (Reference Config) as a reference, and configuration information (Delta Config) of the difference between each configuration information of the secondary cell candidate and the reference config. The reference config is configuration information common to a plurality of cells, and the delta config is information on a part of the configuration information of each cell that is different from the reference config. In other words, the delta config is configuration information unique to each cell. When the terminal device 151 receives the reference config and the delta config, the terminal device 151 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 not included in the delta config that are specified 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 needing to perform an operation related to the setting item only once (designated as "Need N"), the terminal device 151 may receive information from the MN 100 to determine whether to execute the operation related to the setting item only once according to the setting value in the reference config, or to interpret the setting value in the reference config as an intention to delete 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 the information. By using such a combination of the reference config and the delta config, the amount of data of setting information to be notified to the terminal device 151 can be reduced.That is, the setting information common to N cells is notified to the terminal device 151 only once for the multiple cells as the reference config, and the setting information specific to each cell is notified to each cell by the delta config, so that the notification of the part of the setting information corresponding to the reference config among the setting information for the (N-1) cells is omitted, and therefore the data amount of the notified setting information can be reduced. Also, the MN 100 can use the setting information of one cell among multiple candidate cells as the reference config, or use the setting information of a 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 setting 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 identifying which cell's setting information is to be used 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 by using existing identification information such as CellGroupId, SCellIndex, and condReconfigId that are uniquely assigned to the configuration information.

[0018] As described above, the delta config is composed of the setting items of the setting information of each cell that include setting values ​​different from those of the reference config. Therefore, the smaller the difference between the setting information of each cell and the reference config, the fewer the number of setting items included in the delta config, and the less data the delta config contains. On the other hand, if the setting information of each cell is significantly different from the reference config, the number of setting items included in the delta config increases, and the amount of data also increases. In some cases, almost all of the setting items of the reference config are replaced by the setting items of the delta config, and the amount of data of the entire setting information may also increase.

[0019] In this embodiment, in consideration of such circumstances, a plurality of reference configurations can be set, and in addition to the plurality of reference configurations, the terminal device 151 is notified of 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 config ID = 1) - Second reference config (Reference config ID = 2) Cell 131 information (first delta config, reference config ID=1) Cell 132 information (2nd delta config, reference config ID=1) ... Cell 142 information (5th delta config, reference config ID=2) Cell 143 information (6th delta config, reference config ID=2) The terminal device 151 is notified of information in the above format. Here, the reference config ID is identification information capable of uniquely identifying one reference config. Among these pieces of information, the information of the first reference config and the second reference config is notified to the terminal device 151 as an information element such as ReferenceConfigAddModlist. In addition, the information of 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 each candidate cell, for example. The CondReconfigToAddMod information element includes identification information (condReconfigId) specific to the information element, a cell identifier for each cell, a reference config ID, a condition under which CPAC should be performed, and information indicating the delta config of the cell. Note that CPAC refers to the conditional addition and change of a secondary cell, but 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 config from the received information regarding the cell 131 using the information of the reference config ID=1, and generate configuration information for the cell 131 based on the first reference config and the first delta config. Similarly, the terminal device 151 may generate configuration information for the cell 143 using the second reference config and the sixth delta config. With this configuration, even if the configuration information for the connection between the cell 131 or the cell 132 and the cell 143 is significantly different, it is possible to eliminate the disadvantage of using a common reference config. Note that in any of the cells, the reference config 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 config. For example, the configuration information of the cell 131 may be used as the first reference config, and / or the configuration information of the cell 143 may be used as the second reference config. 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 (2nd delta config, reference config ID=1) ... Cell 142 information (5th delta config, reference config ID=2) The terminal device 151 is notified of information in such a format. Note that this is just an example, and information in other formats may be notified to the terminal device 151 as long as the terminal device 151 can configure the setting information of each cell. Note that the setting information of each cell includes not only communication parameters but also CPAC conditions (condExecutionCond, a condition for adding / changing a cell, and an identifier for specifying a separately defined execution condition).

[0020] 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 in 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.

[0021] Next, some examples of the flow of the process of determining the reference config and the delta config will be described.

[0022] First, as a first example, a case where the MN 100 determines a reference config will be described. When the MN 100 determines a reference config, it notifies the SN that provides a cell that uses the reference config of the reference config. The SN determines a difference between setting information in each cell that the MN 100 provides and the notified reference config as a delta config of the cell, and notifies the MN 100 of the delta config. The SN may reject the use of the notified reference config. In this case, the SN may notify the MN 100 of another reference config to be used instead of the notified reference config and a delta config generated based on the other reference config. The MN 100 may notify the SN of identification information (reference config ID) of the reference config to be notified to the SN, and one or more pieces of identification information that can be assigned to another reference config when the use of the reference config is rejected. In this case, for example, when notifying the MN 100 of the above-mentioned different reference configuration, the SN can notify the MN 100 of the identification information assigned to the different reference configuration.

[0023] For example, as shown in FIG. 2, MN 100 transmits a SgNB addition request including a first reference config (Reference config #1) to SN 101 (S201). SN 101 accepts the use of this first reference config and notifies each subordinate DU (DU 111 to DU 113) of this first reference config to generate a delta config (S202). Each DU prepares setting information for connection of UE 151 to its own device, and notifies SN 101 of the delta config, which is difference information between the setting information and the first reference config (S205). Note that SN 101 may request each DU to notify setting information for connection of UE 151, and the DU may notify SN 101 of the setting information. In this case, SN 101 may generate a delta config for each DU from the first reference config and the notified setting information. When the SN 101 acquires the delta config for each DU, it can notify the MN 100 of the information of the delta config (S207). The SN 101 may notify the MN 100 that it is using the first reference config notified from the MN 100. The notification from the SN to the MN 100 may be performed, for example, by using an information element in an SgNB addition request ACK. For example, the information may be notified by a CG-CandidateList. A newly defined information element other than the CG-CandidateList may also be used. This information exchange may be performed by any message that can be used for information exchange by the Xn interface between the MN 100 and the SN.

[0024] On the other hand, the MN 100 transmits an SgNB addition request including a second reference config (Reference config #2) to the SN 102 (S203). The SN 102 may reject the use of the second reference config and notify each subordinate DU (DU 121 to DU 123) of the third reference config to generate a delta config (S204). Each DU prepares setting information for connection of the UE 151 to its own device, and notifies the SN 102 of the delta config, which is difference information between the setting information and the third reference config (S206). In this case, as in the above case, each DU may notify the SN 102 of the setting information itself, and the SN 102 may generate a delta config using the third reference config. When the SN 102 acquires the delta config for each DU, it may notify the MN 100 of the delta config information (S208). In this case, the SN 102 notifies the MN 100 of the third reference configuration being used instead of the second reference configuration.

[0025] In addition, the transmission and reception of information 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. In addition, in an existing F1 interface message, an IE for communication setup using a reference configuration may be newly prepared, or a new message of the F1 interface may be prepared. This also applies to the following description. In addition, 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. In addition, when multiple cells are formed in one DU, information specifying which cell the information to be transmitted and received relates to may also be transmitted and received between the DU and the CU.

[0026] When MN100 acquires the delta config for each cell that is a candidate cell for the secondary cell in this way, MN100 notifies UE151 of the delta config and information on the reference config (S209). In the example of FIG. 2, a first reference config related to the setting information of the cell under SN101, a third reference config related to the setting information of the cell under SN102, and the delta config of each cell are notified to UE151. Here, as described above, each delta config is notified to UE151 together with information (reference config ID) indicating which reference config it is associated with. In the example of FIG. 2, UE151 is notified that the delta configs of DU111 to DU113 are associated with the first reference config, and the delta configs of DU121 to DU123 are associated with the third reference config.

[0027] Next, as a second example, an example in which an SN determines a reference config 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 may notify the SNs that a reference config and a delta config should be generated. At this time, the MN 100 may notify each SN of a usable reference config ID. This may define the maximum number of reference configs that can be set in an SN. In the example of FIG. 3, the SN 101 is notified of reference config IDs=1 and 2 (S301), and the SN 102 is notified of reference config IDs=3 and 4 (S304). In the example of FIG. 3, the MN 100 notifies the SNs of the reference config IDs in order to make the MN 100 and the SNs recognize the reference config IDs in the same way and to prevent the reference config IDs used in each SN from overlapping. However, this is just an example, and the same ID may be set in multiple SNs. For example, a reference config ID may be specified by combining identification information indicating the SN with the ID. In other words, the reference config with reference config ID=1 of SN101 and the reference config with reference config ID=1 of SN102 may be mutually different configurations. In this case, Reference configuration for SN=101 First reference configuration (Reference config ID = 1) Second reference config (Reference config ID=2) Reference configuration for SN=102 Third reference configuration (Reference config ID = 1) Delta config with SN=101 Cell 131 information (first delta config, reference config ID=1) Cell 132 information (2nd 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 config based on SN=101 and reference config ID=1. Then, the terminal device 151 can acquire the configuration information of the cell 132 using the first reference config and the second delta config. On the other hand, for example, when acquiring configuration information of the cell 143, the terminal device 151 extracts a third reference config based on SN=102 and reference config ID=1. Then, the terminal device 151 can acquire the configuration information of the cell 143 using the third reference config and the sixth delta config. Note that, in the above example, an example has been described in which one reference config is specified by combining identification information of each SN and a reference config 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 specified based on the identification information of the group of cells and the reference configuration ID. Here, the group of cells may be a plurality of cells under a plurality of SNs. Here, a cell under one SN may belong to one group, or one or more cells under one SN may belong to a first group, and another cell under the SN may belong to a second group. Even in this configuration, two or more reference configurations set in two or more groups may be specified only by the reference configuration ID, but it is possible to uniquely specify one reference configuration by using the reference configuration ID in combination with the identification information of the group.

[0028] In addition, 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 may 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 may instruct the subordinate DUs to provide the full configuration instead of the delta configuration.

[0029] In addition, when the use of overlapping reference configuration IDs is permitted in a plurality of 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. In addition to the reference configuration ID notified as described above so that separate reference configuration IDs are used in a plurality of 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 the maximum number. Then, the MN 100 may determine the above-mentioned maximum number to be notified to each SN based on the number. Also, the MN 100 may notify the SN 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 configs is predefined in the SN, it is sufficient to be notified that only the reference config and delta config should be generated.

[0030] Each SN sets a reference config within the range of the maximum number of reference configs that can be set for each SN. Then, the SN can notify each of its subordinate DUs of the reference config and instruct them to generate a delta config (S302, S303, S305). The DU generates a delta config based on the notified reference config and notifies the SN of the generated delta config (S306, S307). The SN aggregates the delta configs generated in each DU and notifies the MN 100 of all the set reference configs and delta configs (S308, S309). The delta config is notified to the MN 100 together with information indicating which reference config it is associated with. For example, the SN 101 notifies the MN 100 that the delta configs of the DU 111 and DU 112 are associated with the reference config of reference config ID=1, and the delta config of the DU 113 is associated with the reference config of 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 a 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 by using a common reference config for multiple setting information.

[0031] It is not necessary for the SN to use up 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) to generate delta configurations of 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. After that, 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.

[0032] As a third example, when the MN 100 does not have a reference config, it can instruct the SN to generate a reference config and a delta config, and when it has a reference config, it can notify the SN of the reference config and instruct the SN to generate a delta config. For example, as shown in Fig. 4, while the MN 100 does not have a reference config, it instructs the SN 101 to generate a reference config and a delta config (S401). Then, the SN 101 can generate a reference config within its own device, for example, and instruct the DUs 111 to 113 to generate delta configs (S402). Note that in the example of Fig. 4, the SN 101 generates a reference config, notifies the DUs 111 to 113 of the generated reference config, and the DUs 111 to 113 generate delta configs, 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 delta configs for the cells formed by each DU (S403, S404).

[0033] After that, the MN 100 instructs the SN 102 to generate a delta config (S405). In this case, since the MN 100 has the reference config notified from the SN 101, the MN 100 can notify the SN 102 of the reference config and instruct the SN 102 to generate a delta config. The SN 102 can accept or reject the use of the reference config. In the example of FIG. 4, it is assumed that the SN 102 rejects the use of the reference config and decides to use another reference config. In this case, the SN 102 notifies the DUs 121 to 123 of the other reference config (S406), and the DUs 121 to 123 generate a delta config based on the other reference config. Then, the SN 102 can collect the delta configs from the DUs 121 to 123 (S407) and notify the MN 100 of the delta config (S408). For example, the SN 102 may collect setting information from each of the DUs 121 to 123, and generate a difference between the setting information and the reference config notified from the MN 100 as a candidate for a delta config. If the amount of data of the delta config exceeds a predetermined value, the SN 102 may generate another reference config. This is just an example, and the criterion for the SN 102 to generate another reference config may be determined arbitrarily. The MN 100 notifies the terminal device 151 of the reference config it holds and the collected delta config (S409).

[0034] As described above, after the process of Fig. 4 is completed, the MN 100 holds the first reference configuration used in the SN 101 and the second reference configuration used in the SN 102. After that, when the MN 100 causes another cell to be pre-configured 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 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.

[0035] As described above, the terminal device 151 can obtain the reference config and the delta config for a plurality of 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 a part of the plurality of cells. For example, the MN 100 can activate pre-settings for cells within a predetermined distance from the position of the terminal device 151 as the terminal device 151 moves, and can disable the pre-settings for the other cells. The terminal device 151 can reproduce and hold setting information for a cell for which pre-settings are activated, using the reference config and the delta config. The terminal device 151 can measure the wireless quality for an activated cell, and not measure the wireless quality for a cell that is not activated. The MN 100 can specify a cell to be activated / inactivated, using, for example, identification information (condReconfigId) that is unique to an information element for each cell. When enabling / disabling multiple cells that use a common reference configuration at the same time, you may specify the reference configuration ID of the reference configuration. For example, Reference Config ID=1: Disabled Reference config ID=2: Partially valid condReconfigId=A: Valid condReconfigId=B: Disabled Reference config ID=3: All valid Such information may be notified to the terminal device 151. In the above example, when a reference config is partially enabled, information indicating whether each delta config using the reference config is enabled is specified, and when a reference config is fully enabled, all delta configs using the reference config are enabled. However, this is not limited to the above, and in both cases where only a portion of a delta config using the reference config is enabled and where all delta configs are enabled, the reference config may be set to "enabled", and in that case, enabled / disabled may always be indicated individually for each delta config using the reference config.

[0036] The terminal device 151 measures the radio quality of a measurement target (enabled) cell, and in response to determining that a 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.

[0037] Note that the terminal device 151 maintains the configuration information regarding 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 may be assumed that at least one of the reference configuration and the delta configuration needs to be changed, for example, when a certain time has passed after the reference configuration and the delta configuration are notified to the terminal device 151. Such deletion or change of the configuration is performed, for example, by an instruction from the MN 100.

[0038] The MN 100 or SN connected to the terminal device 151 may 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 a deletion instruction may be transmitted to the terminal device 151 via the MN 100 or SN.

[0039] For example, the network may decide to delete one of the reference configurations in response to the number of set reference configurations reaching (exceeding) 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 decide the reference configuration to be deleted based on the measurement result of the wireless quality in the terminal device 151. For example, the network may determine the maximum value of the wireless quality of the cells using each of the multiple reference configurations, and decide to delete the reference configuration with the lowest maximum value (or the reference configuration not used in the cell whose wireless quality can be determined to be good). The network may also delete delta configurations for cells that are a predetermined distance or more away from the position of the terminal device 151, for example, as the terminal device 151 moves, and when all delta configurations that refer to a specific reference configuration are deleted, decide to delete the specific reference configuration. Furthermore, the network may instruct the terminal device 151, which has set a reference configuration, to delete the reference configuration and allow the terminal device 151 to 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.

[0040] The network removes the cell that has generated the delta config using the reference config to be deleted from the candidates of the secondary cell of the terminal device 151. For example, the MN 100 may transmit an SgNB Release Request to an SN having a cell using the reference config to be deleted, and instruct the SN to delete the configuration information related to the cell. Note that when a specific reference config is deleted and a delta config that references the specific reference config is maintained, the delta config is also deleted. The cell corresponding to the delta config is removed from the candidates of the secondary cell. Note that when a specific reference config is deleted and a delta config that references the specific reference config is maintained, the delta config may be reconfigured based on another reference config. Note that in this case, the MN 100 may specify another reference config and instruct an SN having a cell using the delta config to update the delta config. Note that in this case, the SN may be forced to use another reference config. That is, the SN may not be permitted to reject the use of the other reference configuration. For example, in a state in which reference configurations with reference configuration IDs = 1 and 2 are being used in one SN, it is assumed that the 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 used in any cell may not be deleted.

[0041] Also, even if 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 the above. 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 reference config contents, the SN that generated the reference config, information on the candidate cell for the secondary cell, and the like. Also, 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 refers to the reference config. This eliminates the need to execute the setting process for adding / changing a secondary cell again 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 interrupted (when the RRC state transitions from connected mode to idle mode or inactive mode), etc., the terminal device 151 can spontaneously 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, so that the implementation on the network side can be simplified.

[0042] When the reference config is changed, a "delta reference config" may be used which indicates only the configuration items in the reference config that should be changed. For the configuration items set in the delta reference config, the reference config may be changed according to the value of the configuration item, and for the other configuration items, the reference config may be maintained. At this time, the delta config may also be changed by changing the reference config. For this reason, a "delta-delta config" which indicates only the configuration items in the delta config that should be changed may be used. For the configuration items set in the delta-delta config, the delta config may be changed according to the value of the configuration item, and for the other configuration items, the delta config may be maintained. In this way, when the reference config (and delta config) is changed, only the difference value is exchanged between the MN 100, the SN, and the terminal device, so that it becomes possible to update the configuration information with a small amount of data. In addition, when the reference configuration or delta configuration is changed significantly, the delta-reference configuration or delta-delta configuration may not be used, and the reference configuration or delta configuration used up to that point may be replaced by the newly generated reference configuration or delta configuration. In other words, the reference configuration or delta configuration used up to that point may be deleted, and the newly generated reference configuration or delta configuration may be stored in the terminal device 151.

[0043] 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 of the currently used reference configuration that are specified by the delta 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 that it holds with the newly generated reference configuration. When there is a change in a configuration item that is not specified by the delta configuration for each cell that uses the reference configuration, the terminal device 151 changes the configuration item for the cell and updates the configuration information. In such a configuration, even if a change is made to the reference configuration, there may be a case 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 in order to use it for generating configuration information using the delta configuration of another cell thereafter. When updating a reference config, the reference config to be updated may 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.

[0044] 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 used for the cell with the configuration values ​​of the delta-delta config. When the terminal device 151 receives a newly generated delta config for a specific cell, it replaces the entire delta config of the cell that it holds with the newly generated delta config. 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 the delta config. The terminal device 151 updates the configuration information by changing the configuration items of the updated delta config among the configuration information of the cell corresponding to the updated delta config in accordance with the update of the delta config.

[0045] 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. In this case, a reference configuration ID may be newly assigned to the second reference configuration, and the reference configuration ID may be notified to the terminal device 151. When the MN 100 decides to change the reference configuration, the MN 100 may instruct the SN using the reference configuration to change the reference configuration in the same manner as the above-mentioned notification to the terminal device 151. 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.

[0046] In the above description, the process when either the reference config or the delta config is updated has been described, but both the reference config and the delta config may be updated, for example, as shown in FIG. 5. That is, it is determined whether either the reference config or the delta config should be updated (S501, S503). Then, if the reference config should be updated (YES in S501), the delta reference config or a newly prepared reference config is provided to the terminal device (and SN, if necessary) (S502). Similarly, if the delta config should be updated (YES in S503), the delta delta config or a newly prepared delta config is provided to the terminal device (and SN, if necessary) (S504).

[0047] The terminal device 151 may generate configuration information for each cell based on the acquired reference config and delta config, 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 when the configuration information includes parameters that exceed the capabilities of the terminal device itself (i.e., the terminal device 151 cannot execute). The terminal device 151 may also determine that the configuration information is inappropriate when the configuration information does not include necessary parameters or when the terminal device 151 cannot interpret the contents of the configuration information. For example, when the reference config is mistakenly deleted, the necessary parameters may not exist in the delta config alone, and the configuration information is determined to be inappropriate.

[0048] 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), the terminal device 151 generates configuration information for the cell using the information (S602) and can determine 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 the environment for preparing the configuration information (reference config and delta config are available) is established. 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 identification information (condReconfigId) of the delta config (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. When the network receives this notification, it 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. 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 config that caused the inappropriateness. If a parameter that cannot be used by the terminal device 151 is set, the network may 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 prepare appropriate configuration information in advance.

[0049] Also, as shown in FIG. 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 a cell whose measurement result of wireless quality satisfies 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 measurement result of wireless quality satisfies a predetermined condition. Note that even if there is no secondary cell whose measurement result of wireless quality satisfies a predetermined condition, if there is another cell whose wireless quality is better than the current secondary cell and the configuration information in that cell is appropriate, the terminal device 151 may switch the connection to that cell. If there is inappropriate configuration information, the terminal device 151 may notify the network of the inappropriate configuration information as described above (S704). In one example, after the terminal device 151 connects to a cell in which the configuration information is appropriate, the terminal device 151 may 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, the configuration information is not generated at the time when the reference configuration and delta configuration are acquired, but is generated in response to the satisfaction of a predetermined condition such as a wireless quality condition, and the appropriateness of the configuration information is evaluated, thereby reducing the memory capacity for holding the configuration information in the terminal device 151.

[0050] In addition, when the configuration information of the serving cell is used as the reference configuration, the configuration information of the serving cell may be changed from the time when the reference configuration and the delta configuration are acquired to the time when the measurement result of the radio quality of any of the candidate cells satisfies a predetermined condition. In that case, the reference configuration will also be changed, so the configuration information generated may be different between the case where the configuration information of the cell is generated using the information at the time when the reference configuration and the delta configuration are acquired and the case where the configuration information of the cell is generated at the time when the measurement result of the radio quality of the candidate cell satisfies a predetermined condition. Therefore, it is necessary for the network and the terminal device 151 to agree on the time when the configuration information of the cell is generated. For this reason, information specifying the timing at which the configuration information of the cell is generated may be notified from the network to the terminal device 151. In addition, the network and the terminal device 151 may be pre-configured to generate the configuration information of the cell at a fixed timing that is arbitrarily pre-configured without notifying the information.

[0051] When the configuration information of the serving cell is used as the reference config, the terminal device 151 may store the configuration information of the serving cell held by the terminal device 151 as the reference config at the time of acquiring the reference config and the delta config. In addition, in order to reduce the memory capacity for storing the configuration information in the terminal device 151, the reference config may not be stored at the time of acquiring the reference config and the delta config, and the configuration information of the serving cell at that time may be stored as the reference config in response to a predetermined condition such as a condition of wireless quality being satisfied. In addition, when the terminal device 151 stores the configuration information of the serving cell as the reference config at the time of acquiring the reference config and the delta config, it is assumed that the contents of the configuration information of the serving cell and the reference config will not match when a configuration change instruction of the serving cell is received from the network after the reference config is stored. Therefore, in order to prevent this mismatch, when a serving cell setting change instruction is received from the network after the reference config is saved, an instruction may be transmitted from the network to the terminal device 151 to make the same changes to both the serving cell and the reference config. In this case, instead of instructing the overlapping changes, the network may instruct only the serving cell setting change, and the terminal device 151 may spontaneously make the same changes to the reference config as the serving cell setting without an explicit instruction.

[0052] In addition, two types of information types, mandatory (essential) and optional (non-essential), are defined for each setting item of the setting information regarding the cell, and if a mandatory (essential) setting item is not notified to the terminal device 151, the setting information is determined to be inappropriate. Therefore, in a message format for notifying the conventional setting information regarding the cell without using the reference config, the mandatory (essential) setting item must be included. However, when the setting information is generated using the reference config and the delta config, among the setting items regarding the candidate cell, the mandatory (essential) items may be notified by including them in the delta config without including them in the reference config. In this case, the mandatory (essential) setting item may be omitted in the reference config.

[0053] 8 is a diagram showing 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 a program stored in the ROM 802 or the 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 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 allowing the MN 100, the SN, and the terminal device 151 to communicate with each other.

[0054] FIG. 9 is a diagram outlining an example of a functional configuration of the terminal device 151. 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 for realizing each function may be prepared. FIG. 9 particularly shows functions related to the processing according to this embodiment, and the terminal device 151 may naturally have a function as a normal terminal device that performs communication in accordance with the cellular communication standard of 3GPP (registered trademark). Two or more functional blocks shown in FIG. 9 may be integrated and realized as one functional block, or one functional block may be divided into multiple functional blocks. The terminal device 151 includes, for example, 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 as its functions. Here, the functions are described as those of a secondary cell, but the terminal device 151 may have similar functions for a candidate cell to which the primary cell is to be handed over.

[0055] The reference configuration acquisition unit 901 acquires, for example, a reference configuration that can be used for configuration information of a candidate cell for adding / changing a secondary cell from the MN 100. 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 for generating configuration information related to each of the above-mentioned candidate cells. The delta configuration is information specific to a cell, and is acquired in a format associated with a reference configuration ID in order to indicate which reference configuration should be combined with the delta configuration. Note that the reference configuration and the delta configuration can be acquired together (within 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. Also, when the configuration information is updated, only one of the reference configuration and the delta configuration may be notified to the terminal device 151. The setting information generating unit 903 combines the acquired delta config with a reference config having a reference config ID with which the delta config is associated, and generates setting information for a candidate cell associated with the delta config. The setting information generating unit 903 may generate setting information at the time when the reference config and the delta config are acquired, or may generate setting information for a cell whose wireless quality measured in the terminal device 151 satisfies a predetermined condition, and may not generate setting information unless the predetermined condition is satisfied. The appropriateness determining unit 904 evaluates whether the setting information generated by the setting information generating unit 903 is usable by the terminal device 151, whether there is a missing required parameter, whether the terminal device 151 can interpret, and the like, and determines whether the setting information is appropriate. If the setting information is not appropriate, the information notifying unit 905 performs a predetermined notification to the MN 100 or SN currently connected.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.

[0056] FIG. 10 is a diagram outlining an example of a functional configuration of the MN 100. 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 prepared. FIG. 10 particularly shows functions related to the processing according to this embodiment, and the MN 100 may naturally have a function as a normal base station device that performs communication in compliance with the cellular communication standard of 3GPP (registered trademark). Two or more functional blocks shown in FIG. 10 may be integrated and realized as 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. Here, the secondary cell will be described, but the MN 100 may have the same function for a candidate cell to which the primary cell is to be handed over.

[0057] 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 the cell. Here, the configuration generation instruction unit 1001 instructs the SN to generate configuration information in the form of a combination of a reference config and a delta config, for example. For example, when the number of reference configs reaches a maximum number, the configuration generation instruction unit 1001 can instruct the SN to generate a full config so that no new reference configs are set thereafter. The reference config acquisition unit 1002 can generate a reference config in its own device, for example. Also, the reference config acquisition unit 1002 can receive, for example, a reference config generated in an SN from the SN. The delta config acquisition unit 1003 acquires a delta config unique to each of the cells under the SN from the SN. The delta config is associated with a reference config ID indicating which reference config it should be combined with. For example, the update processing unit 1004 transmits an instruction to the SN to generate a new reference configuration and a delta configuration in response to the need to update at least one of the reference configuration and the delta configuration. After the update processing unit 1004 transmits this instruction, at least one of the reference configuration and the delta configuration after the update is acquired by the reference configuration acquisition unit 1002 and the delta configuration acquisition unit 1003. The information notification unit 1005 provides the acquired reference configuration and delta configuration to the terminal device 151. The information notification unit 1005 can notify the terminal device 151 of information including a reference configuration ID indicating which reference configuration the delta configuration should be combined with.

[0058] FIG. 11 is a diagram outlining an example of the functional configuration of the SN101 and the SN102. 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 for realizing each function may be prepared. FIG. 11 particularly shows functions related to the processing according to this embodiment, and the SN101 and the SN102 may naturally have functions as a normal base station device that performs communication in accordance with the cellular communication standard of 3GPP (registered trademark). Two or more functional blocks shown in FIG. 11 may be integrated and realized as one functional block, or one functional block may be divided into multiple functional blocks. The SN101 and the SN102 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 a secondary cell will be described here, a base station device that is a candidate for an MN, instead of an SN, may have a similar function with respect to a candidate cell for handover of the primary cell.

[0059] 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 that a delta config should be generated. The instruction receiving unit 1101 may further receive an instruction from the MN indicating that a reference config should be generated. For example, when the instruction receiving unit 1101 receives an instruction including a reference config generated by the MN, the instruction receiving unit 1101 may identify that the instruction is an instruction to generate a delta config. When the instruction receiving unit 1101 receives an instruction not including a reference config, the instruction receiving unit 1101 may identify that the instruction is an instruction to generate a reference config and a delta config. The instruction receiving unit 1101 may receive an instruction to update at least one of the reference config and the delta config from the MN. The reference config acquiring unit 1102 may acquire, for example, a reference config included in the instruction received by the instruction receiving unit 1101. Also, 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 the use of the reference configuration included in the instruction is rejected. The delta configuration acquisition unit 1103 acquires, as a delta configuration, a difference between setting information for communication in a 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 on the acquired delta configuration. Note that, when a reference configuration is generated in an 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.

[0060] 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.

[0061] In this way, according to the present embodiment, it is possible to appropriately set and manage the setting 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 setting processing using the reference config and delta config for conditional handover in the terminal device and addition or change of a conditional secondary cell. Therefore, it is possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Develop resilient infrastructure, promote sustainable industrialization and foster innovation."

[0062] 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 base station apparatus, comprising: acquisition means for acquiring information for generating setting information regarding a plurality of cells for conditional handover (CHO) or conditional secondary cell addition or change (CPAC) in a connected terminal device, the information including a reference configuration common to two or more of the plurality of cells and having identification information uniquely identifying 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; providing means for providing the information and conditions for executing the CHO or the CPAC to the terminal device; instruction means for instructing the terminal device to delete or change at least one of the reference configuration and the delta configuration when at least one of the reference configuration and the delta configuration should be deleted or changed, by specifying at least one of the reference configuration and the delta configuration; A base station apparatus characterized by comprising the above.

2. The base station apparatus according to claim 1, wherein the instruction means uses the identification information to specify the reference configuration.

3. The base station apparatus according to claim 1, wherein the instruction means uses information for identifying an information element obtained by combining a cell identifier of a cell in which the delta configuration is used, or the identification information of the reference configuration indicating whether the delta configuration should be combined with the conditions for the CHO or the CPAC and the delta configuration, to specify the delta configuration.

4. The base station apparatus according to claim 1, wherein the instruction means instructs deletion of the reference configuration when there is no delta configuration to be combined with the reference configuration.

5. The base station apparatus according to claim 1, wherein when instructing a change in the reference configuration or the delta configuration, the instruction means notifies the terminal device of difference information indicating setting items to be changed in the reference configuration or the delta configuration.

6. The base station device according to claim 1, wherein when the instruction means instructs a change to the reference configuration or the delta configuration, the reference configuration or the delta configuration to be replaced is notified to the terminal device.

7. A terminal device, information for generating setting information regarding a plurality of cells for conditional handover (CHO) or addition or change of a conditional secondary cell (CPAC) from a connected base station device, the information including a reference configuration common to two or more of the plurality of cells and a delta configuration unique to each of the two or more cells, and acquisition means for acquiring the conditions for executing the CHO or the CPAC; generation means for generating setting information for communication in a cell using the delta configuration and the reference configuration for at least one of the two or more cells; execution means for executing deletion or change of at least one of the specified reference configuration and the delta configuration when an instruction for deletion or change specifying at least one of the reference configuration and the delta configuration is received; execution means for executing the CHO or the CPAC using the generated setting information in response to the conditions being satisfied; A terminal device, characterized by comprising the above.

8. The reference configuration is assigned identification information for uniquely identifying the reference configuration, and the information further includes the identification information of the reference configuration to which the delta configuration is to be combined. The terminal device according to claim 7.

9. The terminal device according to claim 8, wherein the deletion or change instruction includes the identification information as information specifying the reference configuration.

10. The terminal device according to claim 8, wherein the deletion or change instruction includes, as information specifying the delta configuration, an information element that combines a cell identifier of a cell in which the delta configuration is used, or the conditions for the CHO or the CPAC, the delta configuration, and the identification information of the reference configuration indicating whether the delta configuration is to be combined therewith.

11. When deletion of the reference configuration is instructed, the terminal device according to claim 7, characterized in that the reference configuration is deleted and the delta configuration to be combined with the reference configuration is deleted.

12. The instruction to change the reference configuration or the delta configuration includes difference information indicating a setting item to be changed among the reference configuration or the delta configuration, and the terminal device according to claim 7 is characterized in that.

13. The instruction to change the reference configuration or the delta configuration includes the reference configuration or the delta configuration to be replaced, and the terminal device according to claim 7 is characterized in that.

14. The execution means, when the terminal device transitions from the connected state to the idle state, automatically deletes the reference configuration and the delta configuration, and the terminal device according to claim 7 is characterized in that.

15. When the use of the secondary cell is stopped without an instruction from the connected base station device, the reference configuration and the delta configuration are not deleted, and the terminal device according to claim 7 is characterized in that.

16. A control method executed by a base station device, Information for generating setting information regarding a plurality of cells for conditional handover (CHO) or conditional addition or change of a secondary cell (CPAC) in a connected terminal device, wherein the reference configuration common to two or more of the plurality of cells and having identification information uniquely identifying 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 is to be combined, obtaining the information including, Providing the information and the conditions for executing the CHO or the CPAC to the terminal device, When at least one of the reference configuration and the delta configuration should be deleted or changed, instructing the terminal device to delete or change at least one of the reference configuration and the delta configuration by designating, A control method characterized by including.

17. A control method executed by a terminal device, comprising: obtaining, from a connected base station device, information for generating setting information regarding a plurality of cells for conditional handover (CHO) or addition or change of a conditional secondary cell (CPAC), the information including a reference configuration common to two or more of the plurality of cells and a delta configuration unique to each of the two or more cells, and conditions for executing the CHO or the CPAC; generating, for at least one of the two or more cells, setting information for communication in the cell using the delta configuration and the reference configuration; when receiving an instruction to delete or change at least one of the reference configuration and the delta configuration, executing the deletion or change of at least one of the specified reference configuration and the delta configuration; executing the CHO or the CPAC using the generated setting information in response to the conditions being satisfied; characterized by including the above. **Claim 18** A program for causing a computer to function as the base station device according to any one of Claims 1 to 6. **Claim 19** A program for causing a computer to function as the terminal device according to any one of Claims 7 to 15.

Images