Base station, terminal, communication method, and wireless communication system

Abstract

This base station includes a transmitting unit for transmitting to a terminal, using a first radio access technology (RAT), a message requesting a terminal capability report, a receiving unit for receiving, from the terminal, using the first RAT, a message reporting a terminal capability including a capability relating to the first RAT, a capability relating to a second RAT, and a capability relating to dual connectivity employing the first RAT and the second RAT, and a control unit for determining a candidate list of band combinations used for the dual connectivity, on the basis of the capability relating to the first RAT, wherein: the transmitting unit transmits the candidate list to a base station of the second RAT; and the receiving unit receives, from the base station of the second RAT, information indicating a suitable band combination, selected from the candidate list by the base station of the second RAT on the basis of the capability relating to the second RAT.

Description

[Technical field]

[0001] The present invention relates to a base station, a terminal, and a communication method in a wireless communication system. [Background technology]

[0002] For NR (New Radio) (also known as "5G"), the successor system to LTE (Long Term Evolution), technologies are being considered that satisfy the requirements of a large-capacity system, high-speed data transmission speed, low latency, simultaneous connection of a large number of terminals, low cost, low power consumption, etc. (e.g., Non-Patent Document 1).

[0003] In an LTE system or an NR system, a network queries a UE (User Equipment) to obtain information related to the UE's radio access capabilities (e.g., Non-Patent Document 2). The UE's radio access capabilities include, for example, a supported maximum data rate, a layer 2 total buffer size, a supported band combination, a parameter related to MIMO (multiple-input and multiple-output), a parameter related to a Packet Data Convergence Protocol (PDCP) layer, a parameter related to a Radio Link Control (RLC) layer, a parameter related to a Medium Access Control (MAC) layer, or a parameter related to a physical layer (e.g., Non-Patent Document 3). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TS 38.300 V16.2.0(2020-07) [Non-Patent Document 2] 3GPP TS 38.331 V16.1.0(2020-07) [Non-Patent Document 3] 3GPP TS 38.306 V16.1.0(2020-07) Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional technology, when communication is performed using dual connectivity in multiple radio access technologies (RATs), the UE capability related to each band of the multiple RATs is determined individually, and there are cases where the overall performance is not maximized.

[0006] The present invention has been made in consideration of the above-mentioned points, and has an object to improve performance during dual connectivity in a wireless communication system. [Means for solving the problem]

[0007] According to the disclosed technology, a first base station that performs dual connectivity together with a second base station includes a control unit that determines a candidate list of band combinations to be used for the dual connectivity based on capabilities related to a RAT (Radio access technology) of the first base station, a transmission unit that transmits the candidate list to the second base station, and a reception unit that receives information indicating a suitable band combination selected by the second base station from the candidate list from the second base station. The control unit arranges the band combinations included in the candidate list in an order determined from the viewpoint of the first base station. A base station is provided. Effect of the Invention

[0008] According to the disclosed technology, it is possible to improve performance during dual connectivity in a wireless communication system. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of a network architecture according to an embodiment of the present invention. [Diagram 2]1 is a diagram illustrating an example of a configuration of a wireless communication system according to an embodiment of the present invention. [Diagram 3] FIG. 11 is a sequence diagram for explaining an example (1) of communication settings. [Figure 4] FIG. 13 is a diagram showing an example of terminal capabilities related to band combinations. [Diagram 5] FIG. 11 is a sequence diagram for explaining an example (2) of communication settings. [Figure 6] 1 is a flowchart for explaining an example (1) of band combination selection in an embodiment of the present invention. [Figure 7] 11 is a flowchart for explaining an example (2) of band combination selection in the embodiment of the present invention. [Figure 8] 2 is a diagram illustrating an example of a functional configuration of a base station 10 according to an embodiment of the present invention. [Figure 9] 2 is a diagram illustrating an example of a functional configuration of a terminal 20 according to an embodiment of the present invention. [Figure 10] 2 is a diagram illustrating an example of a hardware configuration of a base station 10 or a terminal 20 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is an example, and the embodiment to which the present invention is applied is not limited to the following embodiment.

[0011] In the operation of the wireless communication system according to the embodiment of the present invention, existing technologies are used as appropriate. However, the existing technologies are, for example, existing LTE, but are not limited to existing LTE. In addition, the term "LTE" used in this specification has a broad meaning including LTE-Advanced and systems after LTE-Advanced (e.g., NR) unless otherwise specified.

[0012] In the embodiment of the present invention described below, terms such as SS (Synchronization signal), PSS (Primary SS), SSS (Secondary SS), PBCH (Physical broadcast channel), PRACH (Physical random access channel), PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel), PUCCH (Physical Uplink Control Channel), and PUSCH (Physical Uplink Shared Channel) used in existing LTE are used. This is for convenience of description, and similar signals, functions, etc. may be called by other names. In addition, the above-mentioned terms in NR correspond to NR-SS, NR-PSS, NR-SSS, NR-PBCH, NR-PRACH, NR-PDCCH, NR-PDSCH, NR-PUCCH, NR-PUSCH, etc. However, even if a signal is used in NR, it is not necessarily specified as "NR-".

[0013] Furthermore, in the embodiment of the present invention, the duplexing method may be a time division duplex (TDD) method, a frequency division duplex (FDD) method, or another method (for example, flexible duplex, etc.).

[0014] Furthermore, in the embodiment of the present invention, when radio parameters, etc. are "configured," this may mean that predetermined values ​​are pre-configured, or that radio parameters notified from base station 10 or terminal 20 are configured.

[0015] Fig. 1 is a diagram showing a configuration example of a network architecture in an embodiment of the present invention. As shown in Fig. 1, the wireless network architecture in the embodiment of the present invention includes a 4G-CU, a 4G-RU (Remote Unit, a remote radio station), an EPC (Evolved Packet Core), etc. on the LTE-Advanced side. The wireless network architecture in the embodiment of the present invention includes a 5G-CU, a 5G-DU, etc. on the 5G side.

[0016] As shown in Fig. 1, the 4G-CU includes layers such as RRC (Radio Resource Control), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and up to L1 (Layer 1, PHY layer or physical layer), and is connected to the 4G-RU via CPRI (Common Public Radio Interface). A network node including the 4G-CU and 4G-RU is called an eNB.

[0017] On the other hand, on the 5G side, as shown in FIG. 1, the 5G-CU includes an RRC layer, is connected to the 5G-DU via an FH (Flonthaul) interface, and is connected to the 5G Core Network (5GC) via an NG interface. The 5G-CU is also connected to the 4G-CU via an X2 interface. The PDCP layer in the 4G-CU is a coupling or separation point when performing 4G-5G DC (Dual Connectivity), i.e., EN-DC (E-UTRA-NR Dual Connectivity). A network node including the 5G-CU and 5G-DU is called a gNB. The 5G-CU may also be called a gNB-CU, and the 5G-DU may also be called a gNB-DU.

[0018] As shown in Fig. 1, CA (Carrier Aggregation) is performed between 4G-RUs, and DC is performed between 4G-RU and 5G-DU. Although not shown, UE (User Equipment) is wirelessly connected via the RF of the 4G-RU or 5G-DU to transmit and receive packets.

[0019] Note that Fig. 1 shows a radio network architecture in LTE-NR DC, i.e., EN-DC (E-UTRA-NR Dual Connectivity). However, a similar radio network architecture may be used when the 4G-CU is separated into CU-DU, or when NR is operated standalone. When the 4G-CU is separated into CU-DU, functions related to the RRC layer and the PDCP layer may be transferred to the 4G-CU, and the RLC layer and below may be included in the 4G-DU. Note that the data rate of the CPRI may be reduced by the CU-DU separation.

[0020] In addition, multiple 5G-DUs may be connected to the 5G-CU. In addition, NR-DC (NR-NR Dual Connectivity) may be performed by connecting a UE to multiple 5G-CUs, or NR-DC may be performed by connecting a UE to multiple 5G-DUs and a single 5G-CU. In addition, the 5G-CU may be directly connected to the EPC without going through the 4G-CU, and the 4G-CU may be directly connected to the 5GC without going through the 5G-CU.

[0021] Also, although FIG. 1 shows a radio network architecture at the time of EN-DC, it is not limited to this. For example, the radio network architecture may be NR-DC, NE-DC (NR-EUTRA Dual Connectivity), or other radio network architecture may be adopted. Note that the radio network architecture may not be operated in DC, and may be operated standalone.

[0022] Fig. 2 is a diagram showing a configuration example of a wireless communication system in an embodiment of the present invention. As shown in Fig. 2, the wireless communication system in the embodiment of the present invention includes a base station 10 and a terminal 20. Although Fig. 2 shows one base station 10 and one terminal 20, this is an example, and there may be a plurality of each.

[0023] The base station 10 is a communication device that provides one or more cells and performs wireless communication with the terminal 20. The physical resources of a wireless signal are defined in a time domain and a frequency domain, and 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 the number of resource blocks. The base station 10 transmits a synchronization signal and system information to the terminal 20. The synchronization signal is, for example, NR-PSS and NR-SSS. The system information is, for example, transmitted by NR-PBCH and is also called broadcast information. As shown in FIG. 2, the base station 10 transmits a control signal or data to the terminal 20 in DL (Downlink) and receives a control signal or data from the terminal 20 in UL (Uplink). Both the base station 10 and the terminal 20 can transmit and receive signals by performing beamforming. In addition, both the base station 10 and the terminal 20 can apply communication by MIMO (Multiple Input Multiple Output) to DL or UL. Furthermore, both the base station 10 and the terminal 20 may communicate via a SCell (Secondary Cell) and a PCell (Primary Cell) using CA (Carrier Aggregation).

[0024] The terminal 20 is a communication device equipped with a wireless communication function, such as a smartphone, a mobile phone, a tablet, a wearable terminal, a communication module for M2M (Machine-to-Machine), etc. As shown in Fig. 2, the terminal 20 receives a control signal or data from the base station 10 via DL and transmits a control signal or data to the base station 10 via UL, thereby using various communication services provided by the wireless communication system.

[0025] Here, in 5G-NSA (Non stand alone), i.e., in non-standalone operation of 5G, the EN-DC band combination is specified such that the base station 10, which is an eNB, presents EN-DC band combination selection candidates to the base station 10, which is a gNB, as the information element allowedBC-ListMRDC based on the EN-DC band combination capabilities (UE-MRDC-Capability, UE-EUTRA-Capability, UE-NR-Capability) received from the terminal 20, and the gNB notifies the eNB of the EN-DC band combination selected by the information element selectedBandCombination. The EN-DC band combination indicates a band combination in communication to which EN-DC is applied.

[0026] Fig. 3 is a sequence diagram for explaining a communication setting example (1). In step S1 shown in Fig. 3, the base station 10A, which is an eNB, transmits an RRC message "UECapabilityEnquiry", i.e., an inquiry about UE capabilities, to the terminal 20. In the following step S2, the terminal 20 transmits an RRC message "UECapabilityInformation", i.e., a report of UE capabilities, for the UE capabilities specified by the received "UECapabilityEnquiry", to the base station 10A. The "UECapabilityInformation" includes UE capabilities supported by the terminal 20. The base station 10A identifies the supported UE capabilities based on the received "UECapabilityInformation", and applies them to wireless communication with the terminal 20.

[0027] For example, "UECapabilityInformation" includes EN-DC band combination capabilities (UE-MRDC-Capability, UE-EUTRA-Capability, UE-NR-Capability). In "UE-MRDC-Capability", an EN-DC band combination is set, and is referenced by the base station 10A, which is an eNB, and the base station 10B, which is a gNB. In "UE-EUTRA-Capability", a bandwidth, number of layers, and modulation method of the LTE part are set, and is referenced by the base station 10A, which is an eNB. In "UE-NR-Capability", a bandwidth, number of layers, and modulation method of the NR part are set, and is referenced by the base station 10B, which is a gNB.

[0028] As described above, the EN-DC band combination capability includes the capability of the LTE part and the capability of the NR part. The detailed capability of the LTE part (bandwidth and number of layers) is specified in the information element "featureSetsEUTRA" included in "UE-EUTRA-Capability" referenced by the base station 10A, which is an eNB. The detailed capability of the NR part (bandwidth and number of layers) is specified in the information element "featureSets" included in "UE-NR-Capability" referenced by the base station 10B, which is a gNB. In the standard specifications, the eNB is not required to interpret and set "UE-NR-Capability", and the gNB is not required to interpret and set "UE-EUTRA-Capability".

[0029] In a subsequent step S3, the base station 10A transmits an "SgNB Addition Request", i.e., a secondary gNB addition request, to the base station 10B, which is a gNB, via the X2 interface. The "SgNB Addition Request" includes RRC information elements "CG-Configinfo" and "allowedBC-ListMRDC".

[0030] "allowedBC-ListMRDC" contains a list of indices referencing EN-DC band combinations included in "UE-MRDC-Capability", selected from the band combinations of secondary cell groups that a secondary gNB is allowed to select.

[0031] Furthermore, "CG-Configinfo" includes an information element "eutra-CapabilityInfo." In "eutra-CapabilityInfo," "UE-MRDC-Capability" and "UE-NR-Capability" acquired from the terminal 20 are set.

[0032] In a subsequent step S4, the base station 10B transmits an "SgNB Addition Request Acknowledge", i.e., a secondary gNB addition request acknowledgement, to the base station 10A via the X2 interface. The "SgNB Addition Request Acknowledge" includes RRC information elements "CG-Config" and "selectedbandCombination".

[0033] "selectedbandCombination" indicates the index of the EN-DC band combination selected by the secondary gNB.

[0034] Subsequently, the base station 10A and the base station 10B may perform communication to which EN-DC is applied with the terminal 20, using the EN-DC band combination selected by the base station 10B.

[0035] Fig. 4 is a diagram showing an example of terminal capabilities related to band combinations. As shown in Fig. 4, "UE-MRDC-Capability" referenced by eNB and gNB corresponds to "Band1", "Band3", "Band19", "Band21", "Band28", and "n78" in the EN-DC band combination example "BC1". Also, "UE-MRDC-Capability" corresponds to "Band1", "Band3", and "n78" in the EN-DC band combination example "BC2".

[0036] As shown in FIG. 4, "UE-EUTRA-Capability" which is referenced by the eNB but not the gNB corresponds to "2L", "4L", "2L", "2L" and "2L" in the EN-DC band combination example "BC1". Note that 2L indicates two layers and 4L indicates four layers. Also, "UE-EUTRA-Capability" corresponds to "2L" and "4L" in the EN-DC band combination example "BC2".

[0037] As shown in Fig. 4, "UE-NR-Capability", which is referred to by the gNB but not by the eNB, corresponds to "(2L)(40MHz)" in the example EN-DC band combination "BC1". Also, "UE-NR-Capability" corresponds to "(4L)(100MHz)" in the example EN-DC band combination "BC2".

[0038] Here, the EN-DC band combination in terminal 20 is managed by the overall bandwidth of terminal 20 (e.g., the number of CCs) and the number of layers in relation to the signal processing capability, and it is assumed that there exist EN-DC band combinations such as 1) and 2) shown below. 1) LTE has a large bandwidth (number of CCs) and number of layers, while NR has a small bandwidth (number of CCs) and number of layers. 2) LTE has a smaller bandwidth (number of CCs) and number of layers, while NR has a larger bandwidth (number of CCs) and number of layers.

[0039] Therefore, it is necessary to select the EN-DC band combination by comprehensively determining the possible settings of the LTE part and the NR part. On the other hand, if the eNB sets only the optimal EN-DC band combination from the LTE perspective in "allowedBC-ListMRDC", only band combinations that cannot be selected from the gNB perspective are notified, and there are cases where EN-DC cannot be set.

[0040] 5 is a sequence diagram for explaining a communication setting example (2). When the bandwidth of the NR part is a bandwidth not operated by the gNB, the band combination is not EN-DC setting possible. For example, assume that the terminal 20 supports the following EN-DC band combinations 1) and 2) as shown in Table 1, and the network operates NR with a 100 MHz bandwidth. 1) LTE5CC+NR (40MHz bandwidth) 2) LTE2CC+NR (100MHz bandwidth)

[0041] [Table 1]

[0042] Here, in step S11 shown in FIG. 5, if base station 10A, which is an eNB, sets only the EN-DC band combination 1) above that is compatible with LTE5CC in "allowedBC-ListMRDC" and transmits it to base station 10B, which is a gNB, via the X2 interface, since the EN-DC band combinations that base station 10B can select are not included in "allowedBC-ListMRDC", as shown in step S12 in FIG. 5, an "SgNB Addition Request Reject", i.e., a secondary gNB addition request rejection response, is transmitted from base station 10B to base station 10A via the X2 interface.

[0043] As described above, in the EN-DC band combinations shown in 1) and 2) above, the base station 10A does not refer to the information on NR (40 MHz bandwidth) and NR (100 MHz bandwidth).

[0044] On the other hand, as another example, assume that terminal 20 supports the EN-DC band combinations 1)-3) shown below as shown in Table 2, the LTE area quality situation is better for LTE 1.7 GHz than for LTE 1.5 GHz, and the NR side is operated with a bandwidth of 100 MHz. 1) LTE5CC+NR (40MHz bandwidth) 2) LTE 2GHz (20MHz bandwidth) + LTE 1.5GHz (15MHz bandwidth) + NR 3.7GHz (100MHz bandwidth) 3) LTE 2GHz (20MHz bandwidth) + LTE 1.7GHz (20MHz bandwidth) + NR 3.7GHz (100MHz bandwidth)

[0045] [Table 2]

[0046] If the base station 10A, which is an eNB, does not narrow down the EN-DC band combination from the perspective of the PCell on the LTE side, the base station 10B, which is a gNB, determines the EN-DC band combination by referring only to the NR unit, and therefore, an EN-DC band combination that takes into account the capabilities of the LTE unit may not be determined.

[0047] In the example in which the above 1)-3) are notified to the base station 10B via "allowedBC-ListMRDC" in step S11, since the NR side is operated with a 100 MHz bandwidth, 1) with a 40 MHz bandwidth is not a selection target in the base station 10B. Furthermore, since 2) and 3) have the same NR side capabilities, it is expected that the base station 10B will select 3) which has a wide total bandwidth on the LTE side and good area quality. However, since the base station 10B does not refer to information on the LTE side, there is a possibility that it will not select 3). In other words, there is a possibility that the base station 10B will select the EN-DC band combination of 2) which has a lower throughput than 3).

[0048] As described above, in the EN-DC band combinations shown in 1)-3) above, the base station 10B does not refer to information on LTE 5CC, LTE 2 GHz (20 MHz bandwidth) + LTE 1.5 GHz (15 MHz bandwidth), and LTE 2 GHz (20 MHz bandwidth) + LTE 1.7 GHz (20 MHz bandwidth).

[0049] Therefore, the following operations may be specified in the eNB and gNB for the EN-DC band combination notified to the gNB as a solution candidate.

[0050] The eNB sets the list in the “allowedBC-ListMRDC” to be notified to the gNB in ​​the order of the optimal EN-DC band combination from the perspective of the LTE section only, without narrowing it down except from the perspective of the LTE PCell.

[0051] The gNB selects an EN-DC band combination from the list of "allowedBC-ListMRDC" from the NR section perspective. If the NR section capabilities are the same, the gNB selects the EN-DC band combination that is first in the list.

[0052] 6 is a flowchart for explaining an example (1) of band combination selection in an embodiment of the present invention. In step S21, the eNB does not narrow down the information element "allowedBC-ListMRDC" notified to the gNB from the viewpoint of PCell on the LTE side, but selects the optimal EN-DC band combination order from the viewpoint of the LTE unit.

[0053] As an example, assume that terminal 20 supports the EN-DC band combinations 1)-3) shown below, the LTE area quality situation is better for LTE 1.7 GHz than for LTE 1.5 GHz, and the NR side operates with a bandwidth of 100 MHz. 1) LTE5CC+NR (40MHz bandwidth) 2) LTE 2GHz (20MHz bandwidth) + LTE 1.5GHz (15MHz bandwidth) + NR 3.7GHz (100MHz bandwidth) 3) LTE 2GHz (20MHz bandwidth) + LTE 1.7GHz (20MHz bandwidth) + NR 3.7GHz (100MHz bandwidth)

[0054] In step S21, a list of EN-DC band combinations, which are 1), 3), and 2) in descending order of performance from the viewpoint of the LTE side, is set in "allowedBC-ListMRDC" as shown in Table 3.

[0055] [Table 3]

[0056] In a subsequent step S22, the eNB sends “allowedBC-ListMRDC” to the gNB.

[0057] In step S23, the gNB selects an EN-DC band combination from the NR unit perspective from "allowedBC-ListMRDC". If the NR unit capabilities do not change for multiple EN-DC band combinations, the gNB selects the EN-DC band combination that is first in the list.

[0058] In the above examples of 1)-3), in step S23, 1) notified by "allowedBC-ListMRDC" is not selected because the NR side does not have a 100 MHz bandwidth. 2) and 3) notified by "allowedBC-ListMRDC" are both 100 MHz bandwidth and have the same NR side capabilities, so the gNB selects 3) which is first in the list.

[0059] In addition, for the EN-DC band combination "allowedBC-ListMRDC" notified to the gNB as a solution candidate, it may be possible to further notify priority from the LTE part's perspective (e.g., notified by a new information element), and the following operations may be specified in the eNB and gNB.

[0060] The eNB does not narrow down the “allowedBC-ListMRDC” to be notified to the gNB from any perspective other than the LTE side PCell perspective, and explicitly notifies the gNB of the priority of each EN-DC band combination from the LTE section perspective.

[0061] The gNB selects an EN-DC band combination from the list of "allowedBC-ListMRDC" from the NR section perspective. If the NR section capabilities are the same, the gNB selects the EN-DC band combination with the highest priority based on the priority notified by the eNB.

[0062] 7 is a flowchart for explaining an example (2) of band combination selection in an embodiment of the present invention. In step S31, the eNB, in the information element "allowedBC-ListMRDC" notified to the gNB, does not narrow down the EN-DC band combinations except from the viewpoint of the LTE side PCell, and further includes information explicitly indicating the priority of each EN-DC band combination from the viewpoint of the LTE unit in the list of EN-DC band combinations.

[0063] As an example, assume that terminal 20 supports the EN-DC band combinations 1)-3) shown below, the LTE area quality situation is better for LTE 1.7 GHz than for LTE 1.5 GHz, and the NR side operates with a bandwidth of 100 MHz. 1) LTE5CC+NR (40MHz bandwidth) 2) LTE 2GHz (20MHz bandwidth) + LTE 1.5GHz (15MHz bandwidth) + NR 3.7GHz (100MHz bandwidth) 3) LTE 2GHz (20MHz bandwidth) + LTE 1.7GHz (20MHz bandwidth) + NR 3.7GHz (100MHz bandwidth)

[0064] In step S31, in "allowedBC-ListMRDC", a list of EN-DC band combinations including information indicating priority 1 for 1), priority 3 for 2), and priority 2 for 3) is set according to performance from the LTE perspective, as shown in Table 4. Here, the value indicating the priority is defined as the lower the value, the higher the priority.

[0065] [Table 4]

[0066] The value indicating the priority may be defined such that the lower the value, the higher the priority, or the higher the value, the higher the priority. Furthermore, the information element indicating the priority may be added to each entry of the EN-DC band combination in the list, or may be an information element notified separately from the entry of the EN-DC band combination in the list.

[0067] In a subsequent step S32, the eNB sends “allowedBC-ListMRDC” to the gNB.

[0068] In step S33, the gNB selects an EN-DC band combination from the NR unit perspective from the "allowedBC-ListMRDC". If the capability of the NR unit does not change in multiple EN-DC band combinations, the gNB selects an EN-DC band combination with a high priority.

[0069] In the above examples of 1)-3), in step S33, 1) notified by "allowedBC-ListMRDC" is not selected because the NR side does not have a 100 MHz bandwidth. 2) and 3) notified by "allowedBC-ListMRDC" are both 100 MHz bandwidth and have the same NR side capabilities, so the gNB selects 3) which has a lower priority value, i.e., a higher priority.

[0070] According to the above-described embodiment, the terminal 20 is able to select the optimal EN-DC band combination from the perspective of throughput taking into consideration the overall performance of the LTE section and the NR section, which is expected to improve the user experience.

[0071] In other words, the performance during dual connectivity in a wireless communication system can be improved.

[0072] (Device configuration) Next, a functional configuration example of the base station 10 and the terminal 20 that execute the processes and operations described above will be described. The base station 10 and the terminal 20 include functions for implementing the above-mentioned embodiments. However, the base station 10 and the terminal 20 may each include only a part of the functions in the embodiments.

[0073] <Base station 10> Fig. 8 is a diagram showing an example of a functional configuration of base station 10 in the embodiment of the present invention. As shown in Fig. 8, 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 Fig. 8 is merely an example. The functional divisions and names of the functional units may be any names as long as they can execute the operations related to the embodiment of the present invention.

[0074] The transmitting unit 110 includes a function of generating a signal to be transmitted to the terminal 20 side and transmitting the signal wirelessly. The transmitting unit 110 also transmits an inter-network node message to another network node. The receiving unit 120 includes a function of receiving various signals transmitted from the terminal 20 and acquiring, for example, information of a higher layer from the received signal. The transmitting unit 110 also has a function of transmitting NR-PSS, NR-SSS, NR-PBCH, DL / UL control signals, etc. to the terminal 20. The receiving unit 120 also receives an inter-network node message from another network node.

[0075] The setting unit 130 stores preset setting information and various setting information to be transmitted to the terminal 20. The content of the setting information is, for example, information related to transmission and reception settings according to the UE capabilities of the terminal 20.

[0076] As described in the embodiment, the control unit 140 performs control related to processing of a UE capability report related to radio parameters received from the terminal 20. Furthermore, the control unit 140 controls communication with the terminal 20 based on the UE capability report related to radio parameters received from the terminal 20. A functional unit related to signal transmission in the control unit 140 may be included in the transmitting unit 110, and a functional unit related to signal reception in the control unit 140 may be included in the receiving unit 120.

[0077] <Terminal 20> Fig. 9 is a diagram showing an example of a functional configuration of terminal 20 in the embodiment of the present invention. As shown in Fig. 9, terminal 20 has transmitting unit 210, receiving unit 220, setting unit 230, and control unit 240. The functional configuration shown in Fig. 9 is merely an example. The functional divisions and names of the functional units may be any names as long as they can execute the operations related to the embodiment of the present invention.

[0078] The transmitter 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The receiver 220 wirelessly receives various signals and acquires a higher layer signal from the received physical layer signal. The receiver 220 also has a function of receiving NR-PSS, NR-SSS, NR-PBCH, DL / UL / SL control signals, etc. transmitted from the base station 10. For example, the transmitter 210 transmits a PSCCH (Physical Sidelink Control Channel), a PSSCH (Physical Sidelink Shared Channel), a PSDCH (Physical Sidelink Discovery Channel), a PSBCH (Physical Sidelink Broadcast Channel), etc. to another terminal 20 as D2D communication, and the receiver 120 receives the PSCCH, the PSSCH, the PSDCH, or the PSBCH, etc. from the other terminal 20.

[0079] The setting unit 230 stores various setting information received from the base station 10 by the receiving unit 220. The setting unit 230 also stores setting information that is set in advance. The content of the setting information is, for example, information related to transmission / reception settings according to UE capabilities.

[0080] As described in the embodiment, the control unit 240 performs control related to UE capability reporting regarding radio parameters of the terminal 20. A functional unit related to signal transmission in the control unit 240 may be included in the transmitting unit 210, and a functional unit related to signal reception in the control unit 240 may be included in the receiving unit 220.

[0081] (Hardware configuration) The block diagrams (FIGS. 8 and 9) used to explain the above embodiments show functional blocks. 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 combined, or may be realized using two or more devices that are physically or logically separated and directly or indirectly connected (e.g., using wires, wirelessly, etc.) and these multiple devices. The functional blocks may be realized by combining the one device or the multiple devices with software.

[0082] Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocation, mapping, assignment, etc. For example, a functional block (component) that performs the function of transmission is called a transmitting unit or a transmitter. In either case, as described above, there is no particular limitation on the method of realization.

[0083] For example, the base station 10, the terminal 20, etc. in an embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 10 is a diagram showing an example of a hardware configuration of the base station 10 and the terminal 20 according to an embodiment of the present disclosure. The above-mentioned base station 10 and the terminal 20 may be physically configured as a computer device including a processor 1001, a storage device 1002, an auxiliary storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0084] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the base station 10 and the terminal 20 may be configured to include one or more of the devices shown in the figure, or may be configured to exclude some of the devices.

[0085] Each function in the base station 10 and the terminal 20 is realized by loading a specific software (program) onto hardware such as a processor 1001, a memory device 1002, etc., so that the processor 1001 performs calculations, controls communications by the communication device 1004, and controls at least one of reading and writing of data in the memory device 1002 and the auxiliary memory device 1003.

[0086] The processor 1001 controls the entire computer by running, for example, an operating system. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

[0087] Moreover, the processor 1001 reads out a program (program code), a software module, data, or the like from at least one of the auxiliary storage device 1003 and the communication device 1004 to the storage device 1002, and executes various processes according to the program. As the program, a program that causes a computer to execute at least a part of the operations described in the above-mentioned embodiment is used. For example, the control unit 140 of the base station 10 shown in FIG. 8 may be realized 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 FIG. 9 may be realized by a control program stored in the storage device 1002 and operated by the processor 1001. Although the above-mentioned various processes have been described as being executed by one processor 1001, they may be executed by two or more processors 1001 simultaneously or sequentially. The processor 1001 may be implemented by one or more chips. The program may be transmitted from a network via a telecommunication line.

[0088] The storage device 1002 is a computer-readable recording medium, and may be configured by at least one of, for example, a Read Only Memory (ROM), an Erasable Programmable ROM (EPROM), an Electrically Erasable Programmable ROM (EEPROM), a Random Access Memory (RAM), etc. The storage device 1002 may also be called a register, a cache, a main memory (primary storage device), etc. The storage device 1002 can store a program (program code), software modules, etc. that are executable to implement a communication method according to an embodiment of the present disclosure.

[0089] The auxiliary storage device 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk 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 versatile disk, a Blu-ray (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. The above-mentioned storage medium may be, for example, a database, a server, or other suitable medium including at least one of the storage device 1002 and the auxiliary storage device 1003.

[0090] The communication device 1004 is hardware (transmission and reception device) for performing communication between computers via at least one of a wired network and a wireless network, and is also called, for example, a network device, a network controller, a network card, a communication module, etc. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc., in order to realize at least one of, for example, Frequency Division Duplex (FDD) and Time Division Duplex (TDD). For example, a transmission and reception antenna, an amplifier unit, a transmission and reception unit, a transmission line interface, etc. may be realized by the communication device 1004. The transmission and reception unit may be implemented as a transmission unit and a reception unit that are physically or logically separated from each other.

[0091] The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that accepts input from the outside. The output device 1006 is an output device (e.g., a display, a speaker, an LED lamp, etc.) that performs output to the outside. The input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

[0092] In addition, 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 may be configured using different buses between each device.

[0093] Furthermore, the base station 10 and the terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), etc., and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0094] (Summary of the embodiment) As described above, according to an embodiment of the present invention, a base station is provided that includes a transmitter that transmits a message requesting a report of terminal capabilities to a terminal in a first RAT (Radio access technology), a receiver that receives a message reporting terminal capabilities from the terminal in the first RAT, including capabilities related to the first RAT, capabilities related to a second RAT, and capabilities related to dual connectivity using the first RAT and the second RAT, and a control unit that determines a candidate list of band combinations to be used for the dual connectivity based on the capabilities related to the first RAT, wherein the transmitter transmits the candidate list to a base station in the second RAT, and the receiver receives information indicating a preferred band combination selected by the base station in the second RAT from the candidate list based on the capabilities related to the second RAT from the base station in the second RAT.

[0095] With the above configuration, the terminal 20 can select an optimal EN-DC band combination from the perspective of throughput that comprehensively considers the performance of the LTE part and the NR part, and is expected to improve the user experience. In other words, it is possible to improve the performance during dual connectivity in a wireless communication system.

[0096] The control unit may arrange the band combinations included in the candidate list in order of performance in the first RAT. With this configuration, the terminal 20 can select an optimal EN-DC band combination from the viewpoint of throughput in which the performance of the LTE unit and the NR unit is comprehensively taken into consideration.

[0097] The control unit may assign a priority to each of the band combinations included in the candidate list. With this configuration, the terminal 20 can select an optimal EN-DC band combination from the perspective of throughput, taking into consideration the performance of the LTE unit and the NR unit in a comprehensive manner.

[0098] Also, according to an embodiment of the present invention, there is provided a base station having a receiving unit that receives, from a base station of a first RAT, a candidate list of band combinations to be used for dual connectivity using the first RAT and a second RAT, the candidate list being determined based on a capability related to the first RAT; a control unit that selects a suitable band combination to be used for the dual connectivity from the candidate list based on a capability related to the second RAT; and a transmitting unit that transmits information indicating the selected band combination to a base station in the first RAT.

[0099] With the above configuration, the terminal 20 can select an optimal EN-DC band combination from the perspective of throughput that comprehensively considers the performance of the LTE part and the NR part, and is expected to improve the user experience. In other words, it is possible to improve the performance during dual connectivity in a wireless communication system.

[0100] Also, according to an embodiment of the present invention, there is provided a terminal having a receiving unit that receives a message requesting a report of terminal capabilities from a base station in a first RAT (Radio access technology), a control unit that includes capabilities related to the first RAT, capabilities related to a second RAT, and capabilities related to dual connectivity using the first RAT and the second RAT in a message reporting terminal capabilities based on the message requesting the report of terminal capabilities, and a transmitting unit that transmits the message reporting terminal capabilities to the base station in the first RAT, wherein the receiving unit and the transmitting unit perform communication via dual connectivity using preferred band combinations in each of the first RAT and the second RAT.

[0101] With the above configuration, the terminal 20 can select an optimal EN-DC band combination from the perspective of throughput that comprehensively considers the performance of the LTE part and the NR part, and is expected to improve the user experience. In other words, it is possible to improve the performance during dual connectivity in a wireless communication system.

[0102] According to an embodiment of the present invention, a base station executes a transmission procedure of transmitting a message requesting a report of terminal capabilities to a terminal in a first RAT (Radio access technology); a reception procedure of receiving a message reporting terminal capabilities including capabilities related to the first RAT, capabilities related to a second RAT, and capabilities related to dual connectivity using the first RAT and the second RAT from the terminal in the first RAT; and a control procedure of determining a candidate list of band combinations to be used for the dual connectivity based on the capabilities related to the first RAT, the transmission procedure including a procedure of transmitting the candidate list to a base station in the second RAT, and the reception procedure including a procedure of receiving information indicating a suitable band combination selected by the base station in the second RAT from the candidate list based on the capabilities related to the second RAT from the base station in the second RAT, from the base station in the second RAT.

[0103] With the above configuration, the terminal 20 can select an optimal EN-DC band combination from the perspective of throughput that comprehensively considers the performance of the LTE part and the NR part, and is expected to improve the user experience. In other words, it is possible to improve the performance during dual connectivity in a wireless communication system.

[0104] (Supplementary embodiment) Although the embodiment of the present invention has been described above, the disclosed invention is not limited to such an embodiment, and those skilled in the art will understand various modifications, modifications, alternatives, replacements, and the like. Although the description has been given using specific numerical examples to facilitate understanding of the invention, unless otherwise specified, those 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, and matters described in two or more items may be used in combination as necessary, and matters described in one item may be applied to matters described in another item (as long as there is no contradiction). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operations of multiple functional units may be physically performed by one part, or the operations of one functional unit may be physically performed by multiple parts. The order of the processing procedures described in the embodiment may be changed as long as there is no contradiction. For convenience of the processing description, the base station 10 and the terminal 20 have been described using functional block diagrams, but such devices may be realized by hardware, software, or a combination thereof. The software operated by the processor possessed by the base station 10 in accordance with an embodiment of the present invention and the software operated by the processor possessed by the terminal 20 in accordance with an embodiment of the present invention may each be stored in a random access memory (RAM), flash memory, read only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server or any other suitable storage medium.

[0105] Furthermore, the notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB)), other signals, or a combination of these. Furthermore, the RRC signaling may be called an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0106] Each aspect / embodiment described in the present disclosure may be applied to at least one of systems using 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 (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, UWB (Ultra-WideBand), Bluetooth (registered trademark), and other suitable systems, and next-generation systems extended based on these. In addition, a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A and 5G, etc.) may be applied.

[0107] The steps, sequences, flow charts, etc. of each aspect / embodiment described herein may be reordered unless inconsistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

[0108] In this specification, a specific operation performed by the base station 10 may be performed by its upper node in some cases. In a network consisting of one or more network nodes having the base station 10, it is clear that various operations performed for communication with the terminal 20 may be performed by at least one of the base station 10 and other network nodes other than the base station 10 (e.g., MME or S-GW, etc., but are not limited to these). Although the above example illustrates a case in which there is one other network node other than the base station 10, the other network node may be a combination of multiple other network nodes (e.g., MME and S-GW).

[0109] The information or signals described in the present disclosure may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input / output via multiple network nodes.

[0110] The input and output information may be stored in a specific location (e.g., memory) or may be managed using a management table. The input and output information may be overwritten, updated, or added to. The output information may be deleted. The input information may be transmitted to another device.

[0111] In the present disclosure, the determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

[0112] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0113] Additionally, software, instructions, information, etc. may be transmitted or received over a transmission medium. For example, if the software is transmitted from a website, server, or other remote source using wired and / or wireless technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave, etc.), then these wired and / or wireless technologies are included within the definition of transmission media.

[0114] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. 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 voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0115] In addition, the terms described in this disclosure and the terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Also, a signal may be a message. Also, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0116] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0117] In addition, the information, parameters, etc. described in the present disclosure may be represented using absolute values, may be represented using relative values ​​from a predetermined value, or may be represented using other corresponding information. For example, a radio resource may be indicated by an index.

[0118] The names used for the above-mentioned parameters are not limiting in any way. Moreover, the formulas using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not limiting in any way.

[0119] In the present disclosure, terms such as "base station (BS)", "wireless base station", "base station device", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point", "transmission point", "reception point", "transmission / reception point", "cell", "sector", "cell group", "carrier", "component carrier", etc. may be used interchangeably. A base station may also be referred to by terms such as a macro cell, a small cell, a femto cell, a pico cell, etc.

[0120] A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can also be provided with communication services by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head). The term "cell" or "sector" refers to a part or the entire coverage area of ​​a base station and / or a base station subsystem that provides communication services in this coverage.

[0121] In this disclosure, the terms "Mobile Station (MS)", "user terminal", "User Equipment (UE)", "terminal", etc. may be used interchangeably.

[0122] 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 some other suitable terminology.

[0123] 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 moving body, the moving body itself, etc. The moving body may be a vehicle (e.g., a car, an airplane, etc.), an unmanned moving 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 include 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.

[0124] Furthermore, the base station in the present disclosure may be read as a user terminal. For example, each aspect / embodiment of the present disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between a plurality of terminals 20 (which may be called, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)). In this case, the terminal 20 may be configured to have the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, an uplink channel, a downlink channel, etc. may be read as a side channel.

[0125] Similarly, a user terminal in the present disclosure may be read as a base station. In this case, the base station may be configured to have the functions of the above-mentioned user terminal.

[0126] As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, search, inquiry (e.g., searching in a table, database, or other data structure), ascertaining, and the like. "Determining" and "determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in a memory), and the like. In addition, "judgment" and "decision" can include considering resolving, selecting, choosing, establishing, comparing, etc., to be a "judgment" or "decision." In other words, "judgment" and "decision" can include considering some action to be a "judgment" or "decision." In addition, "judgment" can be interpreted as "assuming," "expecting," "considering," etc.

[0127] The terms "connected," "coupled," or any variation thereof, refer to 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" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using at least one of one or more wires, cables, and printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0128] The reference signal may be abbreviated as RS (Reference Signal) and may be called a pilot depending on the applicable standard.

[0129] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0130] Any reference to an element using a designation such as "first," "second," etc., 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 method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must precede the second element in some way.

[0131] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0132] When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Further, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0133] A radio frame may be composed of one or more frames in the time domain. Each of the one or more frames in the time domain may be called a subframe. A subframe may further be composed 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.

[0134] The numerology may be communication parameters that apply to the transmission and / or reception of a signal or channel, such as, for example, at least one of a subcarrier spacing (SCS), a bandwidth, a symbol length, a cyclic prefix length, a transmission time interval (TTI), a number of symbols per TTI, a radio frame structure, a particular filtering operation that the transceiver performs in the frequency domain, a particular windowing operation that the transceiver performs in the time domain, etc.

[0135] A slot may be composed of one or more symbols (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol, etc.) in the time domain. A slot may be a time unit based on numerology.

[0136] A slot may include multiple minislots. Each minislot may be composed of one or multiple symbols in the time domain. A minislot may also be called a subslot. A minislot may be composed of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (or PUSCH) mapping type B.

[0137] A radio frame, a subframe, a slot, a minislot, and a symbol each represent a time unit for transmitting a signal. The radio frame, the subframe, the slot, the minislot, and the symbol may each be referred to by a different name.

[0138] 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. That is, at least one of the subframe and the TTI may be a subframe (1 ms) in the existing LTE, a period shorter than 1 ms (for example, 1-13 symbols), or a period longer than 1 ms. Note that the unit expressing the TTI may be called a slot, a minislot, or the like, instead of a subframe.

[0139] Here, TTI refers to, for example, the minimum time unit for scheduling in wireless communication. For example, in an LTE system, a base station performs scheduling to allocate wireless resources (such as frequency bandwidth and transmission power that can be used by each terminal 20) to each terminal 20 in TTI units. Note that the definition of TTI is not limited to this.

[0140] The TTI may be a transmission time unit for a channel-encoded data packet (transport block), a code block, a code word, etc., or may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the time interval (e.g., the number of symbols) in which a transport block, a code block, a code word, etc. are actually mapped may be shorter than the TTI.

[0141] In addition, when one slot or one minislot is called TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit of scheduling. Also, the number of slots (minislots) constituting the minimum time unit of scheduling may be controlled.

[0142] A TTI having a time length of 1 ms may be called a normal TTI (TTI in LTE Rel. 8-12), a normal TTI, a long TTI, a normal subframe, 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 minislot, a subslot, a slot, etc.

[0143] In addition, a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length exceeding 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length shorter than the TTI length of a long TTI and equal to or greater than 1 ms.

[0144] A resource block (RB) is a resource allocation unit in the time domain and the frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of the numerology, for example, 12. The number of subcarriers included in an RB may be determined based on the numerology.

[0145] In addition, the time domain of the RB may include one or more symbols and may be one slot, one minislot, one subframe, or one TTI in length. Each of one TTI, one subframe, etc. may be composed of one or more resource blocks.

[0146] Note that one or more RBs may be called a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, or the like.

[0147] Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

[0148] A Bandwidth Part (BWP), which may also be referred to as a fractional bandwidth, may represent a subset of contiguous common resource blocks (RBs) for a numerology on a carrier, where the common RBs may be identified by an index of the RBs relative to a common reference point of the carrier. PRBs may be defined in a BWP and numbered within the BWP.

[0149] The 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 UE within one carrier.

[0150] At least one of the configured BWPs may be active, and the UE may not expect to transmit or receive a given signal / channel outside the active BWP. Note that the terms "cell", "carrier", etc. in this disclosure may be replaced with "BWP".

[0151] The above-mentioned structures of radio frames, subframes, slots, minislots, symbols, etc. are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio 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, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP) length, etc. may be changed in various ways.

[0152] In this disclosure, where articles have been added due to translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0153] In the present 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 "coupled" may also be interpreted in the same way as "different."

[0154] Each aspect / embodiment described in this disclosure may be used alone, in combination, or switched according to execution. In addition, notification of specific information (e.g., notification that "X is the case") is not limited to being done explicitly, but may be done implicitly (e.g., not notifying the specific information).

[0155] In the present disclosure, "UECapabilityEnquiry" is an example of a message requesting a report of terminal capabilities. "UECapabilityInformation" is an example of a message reporting terminal capabilities. UE-MRDC-Capability is an example of a capability related to dual connectivity. UE-EUTRA-Capability is an example of a capability related to the first RAT. UE-NR-Capability is an example of a capability related to the second RAT. allowedBC-ListMRDC is an example of a candidate list of band combinations to be used for dual connectivity. selectedBandCombination is an example of information indicating a preferred band combination selected by a base station in the second RAT.

[0156] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure. (Section 1) A transmitter that transmits a message requesting a terminal capability report to a terminal in a first RAT (Radio access technology); A receiving unit that receives a message reporting terminal capabilities including capabilities related to the first RAT, capabilities related to a second RAT, and capabilities related to dual connectivity using the first RAT and the second RAT from the terminal in the first RAT; A control unit that determines a candidate list of band combinations to be used for the dual connectivity based on capabilities related to the first RAT, The transmission unit transmits the candidate list to a base station in the second RAT; The receiving unit receives, from the base station in the second RAT, information indicating a suitable band combination selected by the base station in the second RAT from the candidate list based on capabilities related to the second RAT. (Section 2) The base station according to claim 1, wherein the control unit sorts the band combinations included in the candidate list in order of performance in the first RAT. (Section 3) 2. The base station according to claim 1, wherein the control unit assigns a priority to each of the band combinations included in the candidate list. (Section 4) A receiving unit that receives a candidate list of band combinations to be used for dual connectivity using the first RAT and a second RAT from a base station of the first RAT, the candidate list being determined based on capabilities related to the first RAT; A control unit that selects a suitable band combination to be used for the dual connectivity from the candidate list based on capabilities related to the second RAT; A base station comprising: a transmitter that transmits information indicating the selected band combination to a base station in the first RAT. (Section 5) A receiving unit that receives a message requesting a terminal capability report from a base station in a first RAT (Radio access technology); A control unit that includes, based on a message requesting a report of the terminal capabilities, capabilities related to the first RAT, capabilities related to the second RAT, and capabilities related to dual connectivity using the first RAT and the second RAT in a message reporting the terminal capabilities; A transmission unit that transmits a message reporting the terminal capability to the base station in the first RAT, The receiving unit and the transmitting unit are a terminal that performs communication through dual connectivity using a band combination that is suitable for each of the first RAT and the second RAT. (Section 6) A transmission procedure of transmitting a message requesting a terminal capability report to a terminal in a first RAT (Radio access technology); A receiving procedure of receiving, from the terminal in the first RAT, a message reporting terminal capabilities including capabilities related to the first RAT, capabilities related to a second RAT, and capabilities related to dual connectivity using the first RAT and the second RAT; A control procedure for determining a candidate list of band combinations to be used for the dual connectivity based on a capability related to the first RAT by a base station; The transmitting step includes a step of transmitting the candidate list to a base station in the second RAT; The receiving step includes a step of receiving, from a base station in the second RAT, information indicating a preferred band combination selected by the base station in the second RAT from the candidate list based on capabilities related to the second RAT. A communication method including the steps of: [Explanation of symbols]

[0157] 10 base station 110 Transmitter 120 Receiving unit 130 Setting section 140 Control section 20 Terminals 210 Transmitter 220 Receiving unit 230 Setting section 240 Control Unit 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication equipment 1005 Input Device 1006 Output device

Claims

1. A first base station performing dual connectivity with a second base station, A control unit that determines a candidate list of band combinations to be used for the dual connectivity based on capabilities related to a radio access technology (RAT) of the first base station; a transmitter for transmitting the candidate list to a second base station; a receiving unit that receives, from the second base station, information indicating a suitable band combination selected by the second base station from the candidate list; The control unit is a base station that arranges band combinations included in the candidate list in an order determined from the perspective of the first base station.

2. The transmission unit transmits a message requesting a terminal capability report to a terminal in a RAT of the first base station; The base station according to claim 1 , wherein the receiving unit receives a message from the terminal in a RAT of the first base station, the message reporting terminal capabilities including capabilities related to the RAT of the first base station.

3. The transmission unit transmits a message requesting a terminal capability report to a terminal in a RAT of a first base station; 2. The base station according to claim 1, wherein the receiving unit receives a message from the terminal in the RAT of the first base station, the message reporting terminal capabilities including capabilities related to a RAT of the first base station, capabilities related to a RAT of a second base station, and capabilities related to dual connectivity using the RAT of the first base station and the RAT of the second base station.

4. The base station of claim 1 , wherein the information is selected based on a RAT-related capability of the second base station from the candidate list.

5. A receiving unit for receiving a message requesting a terminal capability report from a first base station; A control unit that includes, based on a message requesting a report of the terminal capabilities, capabilities related to a radio access technology (RAT) of the first base station, capabilities related to a RAT of the second base station, and capabilities related to dual connectivity using the RAT of the first base station and the RAT of the second base station in a message reporting the terminal capabilities; a transmission unit configured to transmit a message reporting the terminal capability to the first base station; The receiver and the transmitter are a terminal that performs communication via dual connectivity using a preferred band combination selected by the second base station from a candidate list including band combinations in an order determined from the perspective of the first base station.

6. A second base station performing dual connectivity with the first base station, A receiving unit that receives from the first base station a candidate list of band combinations to be used for dual connectivity based on capabilities related to a radio access technology (RAT) of the first base station; A control unit that selects a candidate band combination to be used for dual connectivity from the candidate list based on a capability of the second base station related to a RAT, a transmitter configured to transmit information indicating the selected band combination candidates to the first base station; A base station in which the band combinations included in the candidate list are in an order determined from the perspective of the first base station.

7. determining a candidate list of band combinations to be used for dual connectivity based on capabilities of a first base station related to a radio access technology (RAT); transmitting the candidate list to a second base station; receiving, from the second base station, information indicating a preferred band combination selected by the second base station from the candidate list; and a procedure of arranging the band combinations included in the candidate list in an order determined from the viewpoint of the first base station.

8. A wireless communication system having a first base station and a second base station, The first base station A control unit that determines a candidate list of band combinations to be used for dual connectivity based on capabilities related to a radio access technology (RAT) of the first base station; a transmitter for transmitting the candidate list to the second base station; a receiving unit that receives, from the second base station, information indicating a suitable band combination selected by the second base station from the candidate list; The control unit arranges the band combinations included in the candidate list in an order determined from the viewpoint of the first base station, The second base station a receiving unit for receiving the candidate list from the first base station; A control unit that selects a candidate band combination to be used for dual connectivity from the candidate list based on a capability of the second base station related to a RAT, a transmitter configured to transmit information indicating the selected band combination candidates to the first base station.

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