Base station, communication system, and communication method

Abstract

This base station comprises: a transmission unit that transmits, to another base station, auxiliary information used for determining a band that can be used for the dual connectivity in a terminal; and a reception unit that receives, from the other base station, setting information created on the basis of the auxiliary information.

Description

Base station, wireless communication system, and communication method This invention relates to wireless communication systems and base stations. In 3GPP (3rd Generation Partnership Project), a wireless communication method called 5G or NR (New Radio) (hereinafter referred to as "NR") is being introduced to achieve further increases in system capacity, further increases in data transmission speed, and further decreases in latency in the wireless section. In 5G, various wireless technologies and network architectures have been proposed to meet the requirements of achieving throughput of 10 Gbps or more while keeping the latency in the wireless section to 1 ms or less (for example, Non-Patent Document 1). Furthermore, Dual Connectivity (DC), which allows a terminal to connect to the core network while simultaneously communicating with multiple base stations, has been specified (for example, Non-Patent Documents 2-4). A terminal configured with DC communicates with a base station called the Master Node (MN) and a base station called the Secondary Node (SN). 3GPP TS 38.300 V16.6.0 (2021-06) 3GPP TS 37.340 V16.6.0 (2021-06) 3GPP TS 38.101-3 V16.8.0 (2021-06) 3GPP TS 38.331 V16.4.1 (2021-03) During DC configuration, the MN notifies the SN of potential band combinations that the SN can configure. Furthermore, it is being considered that the MN also sends terminal capability information to the SN indicating whether simultaneous transmission and reception are possible for each band pair. However, because SN cannot know the bands that MN will actually use, it may not be able to properly determine which bands can be set on the terminal in DC, and therefore may not be able to properly create the setting information for the terminal on the SN side. The present invention has been made in view of the above points, and aims to provide a technology for a base station to appropriately determine the bands available for use by a terminal for dual connectivity. According to the disclosed technology, a transmitting unit that transmits auxiliary information used to determine a band available for dual connectivity in a terminal to another base station, a receiving unit that receives configuration information created based on the auxiliary information from the other base station, and a base station including the same are provided. According to the disclosed technology, a technology for a base station to appropriately determine a band available for dual connectivity in a terminal is provided. FIG. for explaining an example of a wireless communication system in an embodiment of the present invention. A diagram showing an example of a band combination in EN-DC. A diagram showing an example of a band combination in EN-DC. A diagram for explaining an example of an operation in an embodiment. A diagram for explaining an example of an operation in an embodiment. A diagram showing an example of a functional configuration of a base station 10 in an embodiment of the present invention. A diagram showing an example of a functional configuration of a terminal 20 in an embodiment of the present invention. A diagram showing an example of a hardware configuration of a device in an embodiment of the present invention. Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are examples, and the embodiments to which the present invention is applied are not limited to the following embodiments. In the operation of the wireless communication system according to the embodiment of the present invention, existing technologies may be appropriately used. The existing technology is, for example, existing NR or LTE, but is not limited to existing NR or LTE. (Example of system configuration) Figure 1 is a diagram illustrating an example of a wireless communication system in an embodiment of the present invention. Figure 1 shows an example configuration of a wireless communication system when dual connectivity (DC) is implemented. As shown in Figure 1, the system is equipped with a base station 10A which acts as a master node (MN) and a base station 10B which acts as a secondary node (SN). Base stations 10A and 10B are each connected to the core network 30. Terminal 20 can communicate with both base station 10A and base station 10B. Base station 10A may be referred to as MN10A and base station 10B as SN10B. The cell group provided by base station 10A, which is the MN, is called the Master Cell Group (MCG), and the cell group provided by base station 10B, which is the SN, is called the Secondary Cell Group (SCG). In dual connectivity, the MCG consists of one PCell and zero or more SCells, and the SCG consists of one PSCell (Primary SCG Cell) and zero or more SCells. Furthermore, the dual connectivity to which the present invention can be applied may be a communication method that utilizes two communication standards, and any combination of communication standards may be used. For example, the combination may be LTE and LTE, NR and NR, NR and LTE, NR and the 6G standard, or LTE and the 6G standard. Note that the eNB of LTE may be NG-eNB. Also, when the two communication standards are different, both may be applied to MN or to SN. For example, taking the combination of NR and LTE as an example, MN may be NR and SN may be LTE, or SN may be LTE and MN may be LTE. Furthermore, the dual connectivity may be a communication method that utilizes three or more communication standards, and may be called by a different name than dual connectivity.Hereafter, when base stations 10A and base stations 10B are described without distinction, they will be referred to as base station 10. Base station 10 is a communication device that provides one or more cells and communicates wirelessly with terminal 20. The physical resources of the wireless signal are defined in the time domain and the frequency domain. The time domain may be defined by the number of OFDM symbols, and the frequency domain may be defined by the number of subcarriers or resource blocks. In addition, the TTI (Transmission Time Interval) in the time domain may be a slot, or the TTI may be a subframe. The base station 10 is capable of performing carrier aggregation, which involves bundling multiple cells (multiple CCs (component carriers)) together to communicate with the terminal 20. Carrier aggregation uses one PCell (primary cell) and one or more SCells (secondary cells). In SCG, PSCell and SCell are used. The base station 10 transmits synchronization signals and system information to the terminal 20. The base station 10 transmits control signals or data to the terminal 20 via DL (Downlink) and receives control signals or data from the terminal 20 via UL (Uplink). Here, signals transmitted on control channels such as PUCCH and PDCCH are referred to as control signals, and signals transmitted on shared channels such as PUSCH and PDSCH are referred to as data, but this is just one example of terminology. Terminal 20 is a communication device equipped with wireless communication capabilities, such as a smartphone, mobile phone, tablet, wearable device, or M2M (Machine-to-Machine) communication module. Terminal 20 receives control signals or data from base station 10 via DL and transmits control signals or data to base station 10 via UL, thereby utilizing various communication services provided by the wireless communication system. Terminal 20 may also be referred to as UE, the NR base station 10 as gNB, and the LTE base station as eNB. In the following description, unless otherwise specified, we will describe, as an example, the case in which MN10A is eNB (or NG-eNB) and SN10B is gNB, that is, the system according to this embodiment is EN-DC (or NGEN-DC). Furthermore, in this embodiment, we will particularly describe Inter-band EN-DC. Inter-band EN-DC is an EN-DC with a band combination having different bands for LTE and NR, such as DC_1A_n8A, DC_1A-42D_n79A (Non-Patent Literature 3), etc. However, the present invention is not limited to EN-DC and can be applied to other DCs as well. (Regarding the challenges) <Existing problem with simultaneousRxTxInterBandENDDC> In existing technologies (e.g., Non-Patent Document 4), the UE Capability transmitted from terminal 20 includes an information element called simultaneousRxTxInterBandENDC. simultaneousRxTxInterBandENDDC is capability information in Inter-band EN-DC that indicates whether it is possible to transmit on another TDD band while receiving on one TDD or FDD band, or whether it is possible to receive on another TDD or FDD band while transmitting on one TDD band. This information is 1-bit (supported / not) for each Band Combination. In addition to Inter-band EN-DC, simultanous Rx / Tx capacities are also defined for NR CA and NR-DC. The problems with the existing simultanous RxTxInterBandENDDC will be explained in detail. Here, as an example, let's assume that the EN-DC band combination is DC_1A-42C_n79A. Also, let's assume that terminal 20 supports the following functions for the LTE and NR band pair in DC_1A-42C_n79A. ・1A (LTE FDD 2GHz) - n79A (NR TDD 4.5GHz): Simultaneous transmission and reception possible ・42C (2CC x LTE TDD 3.5GHz) - n79A (NR TDD 4.5GHz): Simultaneous transmission and reception not possible The existing simultaneousRxTxInterBandENDC is information for each band combination, and if there is even one band pair in the band combination that cannot transmit or receive simultaneously, it is expected that terminal 20 will notify the network that this capability is not supported. Therefore, terminal 20, which supports the above function, cannot perform simultaneous transmission and reception on the 42-n79 band pair, and therefore notifies the network of "not supported" using 1-42_n79 simultaneousRxTxInterBandENDC. Here, we assume that terminal 20, which supports the above functions, wants to connect to a network that provides communication services with the following band configuration (i.e., MN10A and SN10B). Figure 2 illustrates the following band configuration. LTE Band 1: FDD (i.e., transmission and reception possible at any time) LTE Band 42 and NR Band n79: TDD, and DL / UL of TDD are perfectly synchronized (it is impossible to receive n79 while transmitting on Band 42, or vice versa). To connect to this network, terminal 20 does not need to support simultaneous transmission and reception of 42-n79, but it does need to support simultaneous transmission and reception of 1-n79. On the other hand, on the network side, the only way to determine whether simultaneous transmission and reception of 1-n79 is possible is by whether simultaneousRxTxInterBandENDDC is supported or not. In other words, the network can set the EN-DC for 1-42_n79 only for terminals for which simultaneousRxTxInterBandENDDC in 1-42_n79 is supported. In other words, although the terminal 20 having the above-described functions is functionally capable of EN-DC for 1-42_n79 because it satisfies the requirements for simultaneous transmission and reception on a band pair basis (i.e., 1-n79, 42-n79) in the network example above, it cannot configure the EN-DC in signaling because it can only notify that simultaneousRxTxInterBandENDDC in 1-42_n79 is unsupported. <Solution to the problem of simultaneousRxTxInterBandENDDC> The above problem may be resolved by having terminal 20 notify supported / not supported by simultaneousRxTxInterBandENDDC on a band pair basis. Specifically, in the band combination example of 1-42_n79 above, terminal 20 notifies the network of the following information as simultaneousRxTxInterBandENDDC. ・1-n79 band pair: supported 42-n79 band pair: not supported The capability information for simultaneousRxTxInterBandENDDC on a band pair basis, as described above, is notified from MN10A to SN10B. <Issues related to identifying band pairs> In existing technologies, for example, when setting up EN-DC, candidate band combinations that gNB (SN10B) can set are notified to gNB from eNB (MN10A) via allowBC-ListMRDC (Non-Patent Literature 4). The field in the above allowBC-ListMRDC indicates which of the one or more band combinations in the UE Capability notified to MN10A from terminal 20 is available for use by gNB (SN10B). gNB selects the SCG band combination from the available band combinations. In allowedBC-ListMRDC, the band combination of UE Capability is notified, and the fallback band combination is omitted. Note that the fallback band combination corresponds to a subset of the original band combination. For example, if the original band combination is 1-19-42_n79, then examples of fallback band combinations include 1-19-n79, 1-42-n79, 1-19-42, 1_n79, etc., which have bands that eNB cannot actually use removed. As mentioned above, since the fallback band combination is omitted, bands not used by eNB may also be included in each band combination of allowBC-ListMRDC. In other words, with existing technology, the band actually used by the eNB during EN-DC configuration, etc., is unknown to the gNB. Therefore, even if a band pair-based simultaneousRxTxInterBandENDDC is notified from the eNB to the gNB as described above, it is unclear which band pair to refer to in order to determine which band combination the terminal 20 can use. A specific example is explained below. As mentioned above, we will explain using terminal 20, which functionally supports the following, as an example. ・1A (LTE FDD 2GHz) - n79A (NR TDD 4.5GHz): Simultaneous transmission and reception possible ・42C (2CC x LTE TDD 3.5GHz) - n79A (NR TDD 4.5GHz): Simultaneous transmission and reception not possible In this case, terminal 20 notifies the network of the following information as simultaneousRxTxInterBandENDDC per band pair. Terminal 20 also notifies the network of capability information including "1-42_n79" as the band combination it supports. ・1_n79 band pair: supported - Band pair of 42_n79: not supported As mentioned above, when setting up EN-DC, etc., allowBC-ListMRDC does not include fallback band combination. Therefore, whether the eNB performs CA on band 1 + band 42, or whether the eNB uses only band 1 and not band 42, the allowBC-ListMRDC notified from the eNB to the gNB will include "1-42_n79" and will not include "1_n79", etc. Here, we consider the network with the band configuration shown in Figure 3 as an example. The band configuration in Figure 3 is the same as the band configuration shown in Figure 2 in terms of the combination of bands, but it differs from the band configuration shown in Figure 2 in that 42-n79 is asynchronous. In the band configuration shown in Figure 3, simultaneous transmission and reception is possible in either the 1-n79 or 42-n79 band pair. In other words, for a terminal to perform EN-DC communication in the band configuration of Figure 3, the terminal must be capable of simultaneous transmission and reception in either the 1-n79 or 42-n79 band pair. On the other hand, the assumed terminal 20 cannot simultaneously transmit and receive band pairs of 42_n79, but it can simultaneously transmit and receive band pairs of 1_n79. Therefore, when the eNB uses only band 1, the terminal 20 can communicate using 1_n79 and can set the EN-DC for 1_n79. However, it cannot set an EN-DC that includes band 42, such as 1-42_n79. On the other hand, the allowBC-List is set to 1-42_n79 regardless of whether band 42 is used in LTE, and even when eNB uses only band 1, it is not possible to set EN-DC for 1_n79. (Summary of the embodiment) The following describes the technology to solve the above problem. First, an overview of this technology will be given. In the example of the above problem, it is assumed that the eNB (MN10A) uses only band 1. If the gNB (SN10B) can determine that the eNB uses only band 1, it can determine that it is possible to set the EN-DC of 1_n79 for terminal 20 based on the "band pair of 1_n79: supported" information from the following two pieces of information. ・1_n79 band pair: supported - Band pair of 42_n79: not supported Based on the above perspective, in this embodiment, when setting up DC for terminal 20, etc., MN10A notifies SN10B of information that helps SN10B determine which band pair's information to refer to (or evaluate) from the capability information indicating the possibility of simultaneous transmission and reception for each band pair received from MN10A. This "helpful information" may also be called auxiliary information or support information. Hereinafter, it will be referred to as auxiliary information. (Example of basic operation) Referring to Figure 4, a basic example of operation in this embodiment will be described. Here, the operation will be described assuming that MN10A is eNB and SN10B is gNB, that is, when setting EN-DC. However, EN-DC is only one example of DC. The technology according to the present invention is also applicable when MN10A is NG-eNB and SN10B is gNB (NGEN-DC), when MN10A is gNB and SN10B is eNB (NE-DC), when MN10A is gNB and SN10B is gNB (NR-DC), and other combinations of RATs such as DC. In S101, terminal 20 transmits its capability information (UE capability) to MN10A. The UE capability includes information about the configurations or functions supported by terminal 20. For example, the UE capability includes band combinations supported by terminal 20, simultaneous transmission / reception capability information for each band combination, simultaneous transmission / reception capability information for each band pair, etc. In S102, MN10A sends a request message (e.g., CG-ConfigInfo, SgNB addition request) to SN10B. This request message requests SN10B to add an SN (establish an SCG). This request message may also be a request message to modify the SCG. The above request message includes the capability information of terminal 20 received in S101, the allowBC-ListMRDC mentioned above (indicating which band combination(s) among the band combinations supported by terminal 20 are available for use by SN10B), and the aforementioned auxiliary information. In S103, SN10B performs processing related to the EN-DC setting based on the information received from MN10A in S102. For example, based on the information received from MN10A in S102, SN10B selects the SCG band combination, which is the band to be used on the SN side (NR side in this example), from the band combinations shown in allowBC-ListMRDC, and generates configuration information (e.g., NR RRC configuration message) that includes radio resource setting information for the SCG band combination. In S104, SN10B transmits the above configuration information to MN10A. In S105, MN10A transmits configuration information (e.g., RRCConnectionReconfiguration) including the configuration information received from SN10B to terminal 20. Let's explain with a specific example. In S102, SN10B receives "1-42_n79" via allowedBC-ListMRDC, and receives "band pair 1_n79: supported, band pair 42_n79: not supported" as simultaneous transmission / reception capability information for each band pair, and also receives the information that "MN10A will use band 1 and not band 42" as supplementary information. In this case, in S103, SN10B determines that terminal 20 can use "1_n79" as the fallback band combination of "1-42_n79", selects "n79" as the SCG band combination, determines the PSCell (CC) of "n79", determines its wireless resource setting information, and transmits the setting information including the wireless resource setting information to MN10A as the setting information in S104. In S105, MN10A transmits the setting information including the above setting information to terminal 20. (Examples of methods for notifying supplementary information) Examples 1 to 3 below illustrate specific examples of methods for notifying auxiliary information. Examples 1 and 2 utilize existing signaling. Example 3 uses new signaling. Although Examples 1 and 2 utilize existing signaling, using existing signaling in this embodiment is a new technique that does not exist in existing technology. <Example 1> In Example 1, the information element servCellInfoListMCG-EUTRA-r16 (Non-Patent Document 4), which is included in CG-ConfigInfo, is used as auxiliary information. Note that servCellInfoListMCG-EUTRA-r16 used in Example 1 may also be written as servCellInfoListMCG-EUTRA, as an information element not limited to a specific release. CG-ConfigInfo is a message sent from MN10A to SN10B during DC configuration, etc., and in the diagram shown in Figure 4, it is sent at S102. The serveCellInfoListMCG-EUTRA contains information indicating the DL / UL center frequency (EARRFCN) and bandwidth of each serving cell on the MN10A side (LTE side in the case of EN-DC). In S103 of Figure 4, SN10B can use this information as auxiliary information to identify the Band pair to be referenced. In the specific example described above, SN10B can determine from the serveCellInfoListMCG-EUTRA received from MN10A that, for example, "MN10A uses band 1 and does not use band 42," and by referring to the band pair information of 1_n79, it can determine that it is possible to set "1_n79" as the fallback band combination of "1-42_n79" for terminal 20. Furthermore, if the frequency of band 1 is specified as the carrier frequency of the serving cell by serveCellInfoListMCG-EUTRA and the frequency of band 42 is not specified, it can be determined that "MN10A uses band 1 and does not use band 42." Here, the field description of Non-Patent Document 4 states the following regarding serveCellInfoListMCG-EUTRA: "Indicates the carrier frequency and the transmission bandwidth of the serving cell(s) in the MCG in intra-band (NG)EN-DC. The field is needed when MN and SN operate serving cells in the same band for either contiguous or non-contiguous intra-band band combination or LTE NR inter-band band combinations where the frequency range of the E-UTRA band is a subset of the frequency range of the NR band (as specified in Table 5.5B.4.1-1 of TS 38.101-3)."

[0034] It says ") in (NG)EN-DC." In other words, in existing technologies, serveCellInfoListMCG-EUTRA is used when the serving cell operates with MN and SN in the same band, and is not used for the inter-band EN-DC assumed in this embodiment. In this embodiment, assuming, for example, that the above limitations are removed from the specifications, serveCellInfoListMCG-EUTRA can be used for specific applications of the band pair (=band used in MN) of simultaneous Rx / Tx in (NG)EN-DC. ServCellInfoListMCG-EUTRA may also be called the frequency usage information. <Example 2> In Example 2, the selectedBandEntriesMNList (Non-Patent Literature 4) within ConfigRestrictInfoSCG, which is an information element included in CG-ConfigInfo, is used as auxiliary information. The selectedBandEntriesMNList is an information element that indicates which band (one or more bands) among the multiple bands constituting the band combination indicated by the allowedBC-ListMRDC is to be used by the MN in the form of a list of indices in the band combination (a list indicating which band number is to be used). In S103 of FIG. 4, SN10B can use this information as auxiliary information to identify the Band pair to be referenced. In the above-described specific example, based on the selectedBandEntriesMNList received from MN10A, SN10B can determine, for example, that "MN10A uses band 1 and does not use band 42 among band 1 and band 42", and by referring to the information of the band pair of 1_n79, it can be determined that for the terminal 20, "1_n79" can be set as the fallback band combination of "1-42_n79". Here, the field description of Non-Patent Literature 4 states the following regarding selectedBandEntriesMNList: "A list of indices referring to the position of a band entry selected by the MN, in each band combination entry in allowedBC-ListMRDC IE. BandEntryIndex 0 identifies the first band in the bandList of the BandCombination, BandEntryIndex 1 identifies the second band in the bandList of the BandCombination, and so on. This selectedBandEntriesMNList includes the same number of entries and is listed in the same order as in allowedBC-ListMRDC. The SN uses this information to determine which bands out of the NR band combinations in allowedBC-ListMRDC it can configure in SCG. This field is only used in NR-DC." In other words, the selectedBandEntriesMNList in existing technology is used only for NR-DC and not for EN-DC as envisioned in this embodiment. In this embodiment, assuming that the above limitation is removed from the specification, for example, the selectedBandEntriesMNList can be used not only in NR-DC but also in (NG)EN-DC, and is used, for example, for specifying the band pair (=band used in MN) of simultanousRx / Tx. The selectedBandEntriesMNList may also be called selected band information. <Example 3> In Example 3, new information elements not existing in the prior art are used as auxiliary information. As an example, one or a plurality of the following information (1) to (4) is added as a new information element immediately below the CG-ConfigInfo message or at any hierarchical level below the CG-ConfigInfo message. As a result, when the CG-ConfigInfo message is transmitted from MN10A to SN10B, the auxiliary information is also transmitted from MN10A to SN10B. (1) List of frequencies (EARFCN or NR-ARFCN) in use in MN10A (2) List of bands in use in MN10A (3) List of band pairs including the band used in MN10A, or their indexes, among the band pairs notified of simultaneous Rx / Tx (simultaneous transmission / reception availability information) in UE capability (4) List of band pairs including the bands not used in MN10A, or their indexes, among the band pairs notified of simultaneous Rx / Tx (simultaneous transmission / reception availability information) in UE capability SN10B that receives the information of (1) above as auxiliary information can perform the same operations as when receiving servCellInfoListMCG-EUTRA as auxiliary information described in Example 1. Also, SN10B that receives the information of (2) above as auxiliary information can perform the same operations as when receiving selectedBandEntriesMNList as auxiliary information described in Example 2. The case where SN10B receives the information of (3) above as auxiliary information will be described. Similar to the specific example described above, it is assumed that "1-42_n79" is notified to SN10B as allowedBC-ListMRDC, and the following information is notified to SN10B as simultaneous Rx / Tx for each band pair. ・Band pair of 1_n79: supported - Band pair of 42_n79: not supported Furthermore, as part of the information in (3), information indicating that the band pair including the band used by MN10A is "1_n79" is notified to SN10B. This means that in MN10A, band 1 is used and band 42 is not used. In this case, SN10B can determine that it is possible to set EN-DC for terminal 20 using the band combination "1_n79". Furthermore, in the above specific example, SN10B is notified of information as (4) that the band pair including a band not used by MN10A is "42_n79". In this case as well, SN10B can determine that it is possible to set EN-DC for terminal 20 using the band combination "1_n79". Furthermore, one or more of the above information (1) to (4) may be added to an X2AP message or an XnAP message. For example, it may be added to an SgNB Addition Request, SgNB Modification Request, or SgNB Modification Confirm as an X2AP message. Additionally, you may add S-Node Addition Request, S-Node Modification Request, or S-Node Modification Confirm as XnAP messages. (Other examples (variations)) In this embodiment, as shown in Figure 4, a configuration in which auxiliary information is transmitted from MN10A to SN10B has been described, but this is just one example. As shown in Figure 5, MN10A and SN10B may be swapped, with SN10B performing the operations of MN10A described so far, and MN10A performing the operations of SN10B described so far. Furthermore, in the example shown in Figure 4, SN10B may send the configuration information created in S103 directly to terminal 20 instead of sending it to MN10A. Also, in the example shown in Figure 5, MN10A may send the configuration information created in S103 directly to terminal 20 instead of sending it to SN10B. Furthermore, the existing messages described in Examples 1 and 2 are merely examples; for example, you may use an existing message other than those described in Examples 1 and 2 that includes any of the information shown in (1) to (4). Furthermore, auxiliary information may be notified to SN10B (or MN10A) from nodes in the core network 30 (e.g., MME, AMF, SMF, UPF). In this case, for example, MN10A (or SN10B) periodically reports auxiliary information (such as the frequency being used) to the node. (Effects of the embodiment) As explained above, by notifying the SN10B of auxiliary information, the SN10B can appropriately determine the bands available at the terminal for dual connectivity. Therefore, even for band combinations that result in a fallback band combination on UE Capability, it becomes possible to appropriately configure DC settings while considering UE Capability regarding simultaneous transmission and reception. (Device configuration) Next, we will describe an example of the functional configuration of the base station 10 and terminal 20 that perform the processes and operations described above. The base station 10 described below may be an MN10A or an SN10B. The base station 10 and terminal 20 include functions that perform the operations in the above-described embodiment. <Base station 10> Figure 6 shows an example of the functional configuration of a base station 10. As shown in Figure 6, the base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in Figure 6 is merely an example. The names of the functional categories and functional units can be anything as long as they can perform the operations according to the embodiment of the present invention. The transmitting unit 110 and the receiving unit 120 may be called the communication unit. The transmitting unit 110 includes the function of generating a signal to be transmitted to the terminal 20 and transmitting the signal wirelessly. The receiving unit 120 includes the function of receiving various signals transmitted from the terminal 20 and obtaining information from the received signals, for example, information of a higher layer. The transmitting unit 110 also has the function of transmitting information to other base stations, and the receiving unit 120 also has the function of receiving information from other base stations. The setting unit 130 stores pre-configured setting information and various setting information to be transmitted to the terminal 20 in a storage device and reads it from the storage device as needed. The control unit 140 performs control of the entire base station 10, including control related to signal transmission and reception. The signal transmission function unit of the control unit 140 may be included in the transmission unit 110, and the signal reception function unit of the control unit 140 may be included in the reception unit 120. The transmission unit 110 and the reception unit 120 may also be called the transmitter and receiver, respectively. Furthermore, the nodes (devices) in the core network 30, as described above, have the same configuration as the base station 10 shown in Figure 6. However, the nodes in the core network 30 do not transmit or receive signals with the terminal 20, but rather transmit and receive signals with the base station 10 or other nodes using the transmitting unit 110 and the receiving unit 120. <Terminal 20> Figure 7 shows an example of the functional configuration of terminal 20. As shown in Figure 7, terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Figure 7 is merely an example. The names of the functional categories and functional units can be anything as long as they can perform the operations according to the embodiment of the present invention. The transmitting unit 210 and the receiving unit 220 may be called the communication unit. The transmitting unit 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The receiving unit 220 wirelessly receives various signals and obtains signals from higher layers from the received physical layer signals. The setting unit 230 stores various setting information received from the base station 10 by the receiving unit 220 in a storage device and reads it from the storage device as needed. The setting unit 230 also stores pre-set setting information. The control unit 240 controls the entire terminal 20, including control related to signal transmission and reception. The signal transmission function in the control unit 240 may be included in the transmission unit 210, and the signal reception function in the control unit 240 may be included in the reception unit 220. The transmission unit 210 and the reception unit 220 may also be called the transmitter and receiver, respectively. (Hardware configuration) The block diagrams (Figures 6-7) used in the description of the above embodiments show functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may also be realized by combining the one or more devices with software. Functions include, but are not limited to, judgment, decision, determination, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. In all cases, as mentioned above, the method of implementation is not particularly limited. For example, the base station 10, terminal 20, etc. in one embodiment of the present disclosure may function as a computer that processes the wireless communication method of the present disclosure. Figure 8 is a diagram showing an example of the hardware configuration of the base station 10, terminal 20, and core NW-side device 30 according to one embodiment of the present disclosure. The above-mentioned base station 10, terminal 20, and core NW-side device 30 may be physically configured as a computer device including a processor 1001, storage device 1002, auxiliary storage device 1003, communication device 1004, input device 1005, output device 1006, bus 1007, etc. In the following explanation, the term "device" can be read as "circuit," "device," "unit," etc. The hardware configuration of the base station 10 and terminal 20 may include one or more of the devices shown in the figure, or it may be configured without some of the devices. Each function in the base station 10 and terminal 20 is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and storage device 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of data reading and writing in the storage device 1002 and auxiliary storage device 1003. The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control devices, arithmetic units, registers, etc. For example, the control unit 140, control unit 240, etc., described above may be implemented by the processor 1001. Furthermore, the processor 1001 reads programs (program code), software modules, or data from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. For example, the control unit 140 of the base station 10 shown in Figure 6 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Also, for example, the control unit 240 of the terminal 20 shown in Figure 7 may be implemented by a control program stored in the storage device 1002 and operated by the processor 1001. Although the above-described processes have been explained as being executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may also be transmitted from the network via a telecommunications line. The storage device 1002 is a computer-readable recording medium and may consist of at least one of the following: ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. The storage device 1002 may also be called a register, cache, main memory, etc. The storage device 1002 can store executable programs (program code), software modules, etc., for implementing a communication method according to one embodiment of the present disclosure. The auxiliary storage device 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital multipurpose disk, a Blu-ray® disk), a smart card, flash memory (e.g., a card, a stick, a key drive), a floppy® disk, a magnetic strip, etc. The above-mentioned storage medium may also be a database, server, or other suitable medium that includes at least one of the storage device 1002 and the auxiliary storage device 1003. The communication device 1004 is hardware (transmitting / receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc. The communication device 1004 may be configured to include, for example, a high-frequency switch, duplexer, filter, frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the transmitting and receiving antenna, amplifier section, transmitting and receiving section, transmission path interface, etc., may be implemented by the communication device 1004. The transmitting and receiving section may be implemented in a physically or logically separated manner, with a transmitting section and a receiving section. The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel). Furthermore, each device, such as the processor 1001 and the storage device 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device. Furthermore, the base station 10 and terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array), and some or all of each functional block may be realized by such hardware. For example, the processor 1001 may be implemented using at least one of these hardware components. (Summary of the embodiments) This specification discloses base stations, wireless communication systems, and communication methods as described in the following sections. (Section 1) A transmitting unit that transmits auxiliary information to other base stations used to determine the bands available for dual connectivity in the terminal, A receiving unit that receives configuration information created based on the aforementioned auxiliary information from the other base station. A base station equipped with the necessary equipment. (Section 2) A receiving unit that receives auxiliary information from other base stations to determine the bands available for dual connectivity in the terminal, A transmitting unit that transmits configuration information created based on the aforementioned auxiliary information to the other base station. A base station equipped with the necessary equipment. (Section 3) The auxiliary information is one or more of the following: information on the frequency used by the base station transmitting the auxiliary information; information on the band used by the base station transmitting the auxiliary information; information on a band pair including the band used by the base station transmitting the auxiliary information; and information on a band pair including a band not used by the base station transmitting the auxiliary information. A base station as described in paragraph 1 or 2. (Section 4) The bands available for dual connectivity in the terminal are determined based on the auxiliary information and capability information indicating whether simultaneous transmission and reception are possible for each band pair in the terminal. A base station as described in any one of paragraphs 1 through 3. (Section 5) A transmitting unit that transmits auxiliary information to a second base station to determine the bands available for dual connectivity in the terminal, A receiving unit that receives setting information created based on the aforementioned auxiliary information from the second base station. A first base station equipped with, A receiving unit that receives the aforementioned auxiliary information from the first base station, A transmitting unit that transmits configuration information created based on the aforementioned auxiliary information to the first base station. A second base station equipped with, A wireless communication system equipped with [the necessary components]. (Section 6) A transmission step in which auxiliary information used to determine the bands available for dual connectivity at the terminal is transmitted to other base stations, A receiving step in which configuration information created based on the aforementioned auxiliary information is received from the other base station. A communication method performed by a base station, which includes the following features. By any of paragraphs 1 through 6, the base station can appropriately determine the bands available to the terminal for dual connectivity. Furthermore, paragraph 3 allows the use of various auxiliary information, such as existing messages or new messages. Paragraph 4 uses capability information indicating whether simultaneous transmission and reception is possible for each band pair, enabling accurate settings that take into account the possibility of simultaneous transmission and reception. (Supplement to the embodiment) While embodiments of the present invention have been described above, the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, substitutions, etc. Specific numerical examples have been used to facilitate understanding of the invention, but unless otherwise specified, these numerical values ​​are merely examples, and any appropriate values ​​may be used. The division of items in the above description is not essential to the present invention; matters described in two or more items may be combined as needed, and matters described in one item may be applied to matters described in another item (as long as they do not contradict each other). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operation of multiple functional units may be physically performed by one part, or the operation of one functional unit may be physically performed by multiple parts. Regarding the processing procedures described in the embodiments, the order of processing may be changed as long as it does not contradict each other. For the convenience of explaining the processing, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be realized in hardware, software, or a combination thereof. The software operated by the processor of the base station 10 according to an embodiment of the present invention and the software operated by the processor of the terminal 20 according to an embodiment of the present invention may be stored in any suitable storage medium such as random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server, or other appropriate storage medium. Furthermore, notification of information is not limited to the embodiments described herein and may be carried out by other methods. For example, notification of information may be carried out by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), upper layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling, broadcast information (MIB (Master Information Block), SIB (System Information Block))), other signals, or combinations thereof. Also, RRC signaling may be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc. Each aspect / embodiment described in this disclosure may be applied to at least one of the following systems: LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), FRA (Future Radio Access), NR (new Radio), W-CDMA®, GSM®, CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi®), IEEE 802.16 (WiMAX®), IEEE 802.20, UWB (Ultra-WideBand), Bluetooth®, and other appropriate systems, as well as next-generation systems extended based thereon. Furthermore, multiple systems may be applied in combination (for example, a combination of at least one of LTE and LTE-A with 5G). The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described herein may be reordered, provided they are consistent with each other. For example, the methods described herein present various step elements in an exemplary order and are not limited to that specific order. In this specification, specific operations performed by the base station 10 may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station 10, it is clear that various operations performed for communication with the terminal 20 can be performed by the base station 10 and at least one of the other network nodes (for example, an MME or S-GW, but not limited to these). Although the above example illustrates the case where there is one other network node besides the base station 10, the other network node may be a combination of multiple other network nodes (for example, an MME and an S-GW). The information or signals described in this disclosure may be output from a higher layer (or lower layer) to a lower layer (or higher layer). They may also be input and output via multiple network nodes. Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be transmitted to other devices. The determination in this disclosure may be made by a value represented by one bit (0 or 1), by a Boolean value (true or false), or by a numerical comparison (for example, a comparison with a predetermined value). Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name. Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technology (such as coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL)) and wireless technology (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium. The information, signals, etc. described in this disclosure may be represented using any of the various different techniques. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof. In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc. The terms “system” and “network” as used in this disclosure are interchangeable. Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index. The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, and therefore, the various names assigned to these various channels and information elements are not restrictive in any way. In this disclosure, terms such as “Base Station (BS),” “wireless base station,” “base station,” “fixed station,” “NodeB,” “eNodeB (eNB),” “gNodeB (gNB),” “access point,” “transmission point,” “reception point,” “transmission / reception point,” “cell,” “sector,” “cell group,” “carrier,” and “component carrier” may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell. A base station can accommodate one or more (e.g., three) cells. If a base station accommodates multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, each of which may also be provided with communication services by a base station subsystem (e.g., a Remote Radio Head (RRH)). The terms “cell” or “sector” refer to part or all of the coverage area of ​​at least one of the base station and / or base station subsystems that provide communication services in that coverage. In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably. A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or several other appropriate terms. At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile body, the mobile body itself, etc. The mobile body may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may be a device that does not necessarily move during communication operation. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor. Furthermore, the term "base station" in this disclosure may be interpreted as "user terminal." For example, the various aspects / embodiments of this disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple terminals 20 (which may be called, for example, D2D (Device-to-Device), V2X (Vehicle-to-Everything), etc.). In this case, the terminals 20 may have the functions that the base station 10 has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc., may be interpreted as side channel. Similarly, the term "terminal" in this disclosure may be interpreted as "base station." In this case, the base station may be configured to have the same functions as the user terminal described above. As used in this disclosure, the terms “determining” and “determining” may encompass a wide variety of actions. “Determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, or inquiring (e.g., searching in a table, database, or other data structure), or ascertaining. “Determining” may also include receiving (e.g., receiving information), transmitting (e.g., sending information), inputting, outputting, or accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having been "judged" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having been "judged" or "decided" after some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering." The terms “connected,” “coupled,” or any variation thereof, mean any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be reinterpreted as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain. The reference signal can also be abbreviated as RS (Reference Signal), and may be called a pilot depending on the applicable standard. In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on." Any reference to elements using the designations “first,” “second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the first and second elements do not imply that only two elements may be employed, or that the first element must precede the second element in any way. In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc. Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR. A wireless frame may consist of one or more frames in the time domain. Each of these frames in the time domain may be called a subframe. A subframe may further consist of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology. Numerical logic may be communication parameters applied to at least one of the transmission and reception of a signal or channel. Numerical logic may include, for example, at least one of the following: subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame configuration, specific filtering processes performed by the transceiver in the frequency domain, and specific windowing processes performed by the transceiver in the time domain. A slot may consist of one or more symbols in the time domain (such as OFDM (Orthogonal Frequency Division Multiplexing) symbols, SC-FDMA (Single Carrier Frequency Division Multiple Access) symbols, etc.). A slot may also be a time unit based on neurologic. A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. Minislots may also be called subslots. Minislots may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called a PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called a PDSCH (or PUSCH) mapping type B. Wireless frames, subframes, slots, minislots, and symbols all represent units of time when transmitting a signal. Different names may be used for each of these terms. For example, one subframe may be called a Transmission Time Interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. In other words, at least one of a subframe and a TTI may be a subframe in existing LTE (1 ms), a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe. Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, the base station schedules each terminal 20 to allocate wireless resources (such as the frequency bandwidth and transmission power available to each terminal 20) in TTI units. However, the definition of TTI is not limited to this. TTI may be a transmission time unit for channel-encoded data packets (transport blocks), code blocks, code words, etc., or it may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the actual time interval (e.g., number of symbols) in which the transport blocks, code blocks, code words, etc. are mapped may be shorter than the TTI. Furthermore, if one slot or one mini-slot is referred to as a TTI, then one or more TTIs (i.e., one or more slots or one or more mini-slots) may constitute the minimum time unit for scheduling. In addition, the number of slots (number of mini-slots) that constitute this minimum time unit for scheduling may be controlled. A TTI with a time length of 1 ms may be called a normal TTI, a long TTI, a normal subframe, a long subframe, a slot, etc. A TTI shorter than a normal TTI may be called a shortened TTI, a short TTI, a partial or fractional TTI, a shortened subframe, a short subframe, a mini slot, a sub slot, a slot, etc. Furthermore, long TTIs (e.g., normal TTIs, subframes, etc.) may be interpreted as TTIs with a time length exceeding 1 ms, and short TTIs (e.g., shortened TTIs, etc.) may be interpreted as TTIs with a TTI length less than that of a long TTI but 1 ms or more. A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and in the frequency domain, it may contain one or more consecutive subcarriers. The number of subcarriers in an RB may be the same regardless of the neurology, for example, 12. The number of subcarriers in an RB may be determined based on the neurology. Furthermore, the time domain of the RB may contain one or more symbols and may be the length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc., may each consist of one or more resource blocks. One or more RBs may also be called a Physical RB (PRB), Sub-Carrier Group (SCG), Resource Element Group (REG), PRB pair, RB pair, etc. Furthermore, a resource block may consist of one or more resource elements (REs). For example, one RE may be a radio resource area comprising one subcarrier and one symbol. A Bandwidth Part (BWP), also known as a partial bandwidth, may represent a subset of consecutive common resource blocks (RBs) for a particular neurology in a given carrier. These common RBs may be identified by an index of the RBs relative to a common reference point of the carrier. The PRBs may be defined and numbered within a given BWP. A BWP may include a BWP for UL (UL BWP) and a BWP for DL ​​(DL BWP). One or more BWPs may be configured for a terminal 20 within a single carrier. At least one of the configured BWPs may be active, and terminal 20 does not need to be expected to send or receive a predetermined signal / channel outside of the active BWP. In this disclosure, terms such as "cell" and "carrier" may be read as "BWP". The structures described above, such as wireless frames, subframes, slots, minislots, and symbols, are merely illustrative. For example, the number of subframes included in a wireless frame, the number of slots per subframe or wireless frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, and the number of symbols, symbol length, and cyclic prefix (CP) length within a TTI can be varied in various ways. In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural. In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different." Each aspect / embodiment described herein may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is X") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification). Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the intent and scope of the present disclosure as defined by the claims. Therefore, the descriptions in the present disclosure are illustrative and not intended to be restrictive in any way. 10 Base station 110 Transmitter 120 Receiving Unit 130 Setting section 140 Control Unit 20 terminals 210 Transmitter 220 Receiving Unit 230 Setting section 240 Control Unit 30 Core Network 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device

Claims

1. A first base station that is a secondary node that implements dual connectivity, a receiving unit that receives the first setting information and the second setting information from a second base station that is a master node; a control unit that determines a band pair that can be used for the dual connectivity based on the first setting information and the second setting information, the first configuration information is an information element indicating a band used in the second base station, A base station, wherein the second setting information is capability information indicating whether simultaneous transmission and reception are possible for each band pair.

2. The base station according to claim 1 , wherein the first setting information is available in NR-DC and EN-DC.

3. A communication method implemented by a first base station that is a secondary node implementing dual connectivity, comprising: receiving first setting information and second setting information from a second base station that is a master node; determining a band pair available for the dual connectivity based on the first setting information and the second setting information; the first configuration information is an information element indicating a band used in the second base station, The communication method, wherein the second setting information is capability information indicating whether simultaneous transmission and reception are possible for each band pair.

4. A communication system including a first base station which is a secondary node performing dual connectivity, a second base station which is a master node, and a terminal, The first base station a receiving unit that receives first setting information and second setting information from the second base station; a control unit that determines a band pair that can be used for the dual connectivity based on the first setting information and the second setting information, The terminal includes: a transmission unit that transmits the second setting information to the second base station; the first configuration information is an information element indicating a band used in the second base station, A communication system, wherein the second setting information is capability information indicating whether simultaneous transmission and reception are possible for each band pair.