Radio base station and radio communication method

Abstract

To provide a radio base station and a radio communication method capable of appropriately updating an executioncondition of addition / change of a secondary cell (PSCell) in Multi-RATDualConnectivity (MR-DC).SOLUTION: Each of the radio base stations 100A and 100B includes a controller configured to control execution of an addition / change procedure of a secondary cell, a receiver configured to receive a first message related to the secondary cell from another radio base station, and a transmitter configured to transmit a second message including update information of an execution condition of the addition / change procedure to the other radio base station when the first message is received.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a radio base station and a radio communication method that support procedures for adding and changing a secondary cell (secondary node). [Background technology]

[0002] The 3rd Generation Partnership Project (3GPP) has developed specifications for the 5th generation mobile communication system (5G, also known as New Radio (NR) or Next Generation (NG)), and is also developing specifications for the next generation, known as Beyond 5G, 5G Evolution, or 6G.

[0003] For example, in Release-17 of 3GPP, an extension of Multi-RAT Dual Connectivity (MR-DC) is being considered (Non-Patent Document 1).

[0004] Specifically, to achieve more efficient addition or change of Primary SCells (PSCells), support for a simplified conditional secondary cell (secondary node) addition / change procedure (conditional PSCell addition / change) is being considered. The conditional PSCell addition / change allows the UE (User Equipment) to specify execution conditions for determining whether to add or change a PSCell.

[0005] On the other hand, there is a problem that PSCell addition / change is likely to fail due to radio wave characteristics, especially when a secondary node (SN) uses a high frequency band such as FR2 (24.25 GHz to 52.6 GHz). Therefore, studies are being conducted to improve the reliability of conditional PSCell addition / change (Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] "Revised WID on Further Multi-RAT Dual-Connectivity enhancements", RP-201040, 3GPP TSG RAN Meeting #88e, 3GPP, June 2020 [Non-patent document 2] "Report of 3GPP TSG RAN WG2 meeting #114-e, Online", 3GPP TSG RAN WG2 meeting #114-e, 3GPP, May 2021 Summary of the Invention

[0007] In order to improve the reliability of conditional PSCell addition / change, methods for updating the execution conditions for PSCell addition / change as appropriate are being considered. However, there is room for further study on the specific update method and reduction of update delays.

[0008] Therefore, the following disclosure has been made in consideration of such circumstances, and aims to provide a radio base station and a radio communication method that can appropriately update the execution condition for adding or changing a PSCell.

[0009] One aspect of the present disclosure is a radio base station (e.g., gNB100B) that includes a control unit (control unit 140) that controls the execution of a secondary cell addition / change procedure, a receiving unit that receives a first message regarding the secondary cell from another radio base station, and a transmitting unit (RRC / Xn processing unit 120) that, when the first message is received, transmits a second message including updated information on the execution conditions of the addition / change procedure to the other radio base station.

[0010] One aspect of the present disclosure is a wireless communication method including the steps of controlling execution of a secondary cell addition / modification procedure, receiving a first message regarding the secondary cell from another radio base station, and, when the first message is received, transmitting a second message including updated information on execution conditions for the addition / modification procedure to the other radio base station.

[0011] One aspect of the present disclosure is a radio base station (e.g., eNB100A) that includes a control unit (control unit 140) that controls the execution of a procedure for adding or changing a secondary cell, and a receiving unit (RRC / Xn processing unit 120) that receives a message regarding the addition or change of the secondary cell from another radio base station, and the control unit is the radio base station that determines whether or not to update the conditions for executing the procedure for adding or changing the secondary cell based on the identification information of the secondary cell included in the message.

[0012] One aspect of the present disclosure is a wireless communication method including the steps of controlling the execution of a procedure for adding or changing a secondary cell, receiving a message regarding the addition or change of the secondary cell from another radio base station, and determining whether or not the conditions for executing the procedure for adding or changing the secondary cell have been updated based on identification information of the secondary cell included in the message. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing the overall schematic configuration of a wireless communication system 10. As shown in FIG. [Figure 2] FIG. 2 is a functional block diagram of the eNB100A and the gNB100B. [Figure 3] FIG. 3 is a functional block diagram of the UE 200. [Figure 4] FIG. 4 is a diagram illustrating a sequence example (part 1) of an SN-initiated conditional PSCell change. [Figure 5] FIG. 5 is a diagram showing an example of the relationship between the serving cell of the T-SN and the candidate cells designated by the S-SN. [Figure 6]FIG. 6 is a diagram illustrating a sequence example (part 2) of an SN-initiated conditional PSCell change. [Figure 7] FIG. 7 is a diagram illustrating a sequence example (part 3) of an SN-initiated conditional PSCell change. [Figure 8] FIG. 8 is a diagram showing an example of the configuration (ASN.1 format) of CG-Config according to the first operation example. [Figure 9] FIG. 9 is a diagram illustrating an example of an operation flow of the MN according to the second operation example. [Figure 10] FIG. 10 is a diagram illustrating an example of the hardware configuration of the eNB100A, the gNB100B, and the UE200. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or similar reference numerals are used to designate the same functions or configurations, and descriptions thereof will be omitted as appropriate.

[0015] (1) Overall configuration of wireless communication system 1 is a schematic diagram of the overall configuration of a wireless communication system 10 according to this embodiment. The wireless communication system 10 is a wireless communication system conforming to Long Term Evolution (LTE) and 5G New Radio (NR). Note that LTE may also be called 4G, and NR may also be called 5G. The wireless communication system 10 may also be a wireless communication system conforming to a scheme called Beyond 5G, 5G Evolution, or 6G.

[0016] LTE and NR may be interpreted as radio access technologies (RATs), and in this embodiment, LTE may be referred to as the first radio access technology, and NR may be referred to as the second radio access technology.

[0017] The wireless communication system 10 includes an Evolved Universal Terrestrial Radio Access Network 20 (hereinafter, E-UTRAN 20) and a Next Generation-Radio Access Network 30 (hereinafter, NG RAN 30). The wireless communication system 10 also includes a terminal 200 (hereinafter, UE 200, User Equipment).

[0018] The E-UTRAN 20 includes an eNB 100A, which is a radio base station conforming to LTE. The NG RAN 30 includes a gNB 100B, which is a radio base station conforming to 5G (NR). Furthermore, the NG RAN 30 is connected to a User Plane Function 40 (hereinafter referred to as UPF 40), which is included in the 5G system architecture and provides user plane functions. Note that the E-UTRAN 20 and the NG RAN 30 (which may be eNB 100A or gNB 100B) may simply be referred to as a network.

[0019] The eNB100A, gNB100B and UE200 are capable of supporting carrier aggregation (CA) using multiple component carriers (CCs), and dual connectivity for simultaneously transmitting component carriers between multiple NG-RAN nodes and the UE.

[0020] The eNB100A, the gNB100B, and the UE200 perform wireless communication via a radio bearer, specifically, a Signaling Radio Bearer (SRB) or a DRB Data Radio Bearer (DRB).

[0021] In this embodiment, Multi-Radio Dual Connectivity (MR-DC) in which the eNB100A constitutes the master node (MN) and the gNB100B constitutes the secondary node (SN), specifically E-UTRA-NR Dual Connectivity (EN-DC), may be implemented, or NR-E-UTRA Dual Connectivity (NE-DC) in which the gNB100B constitutes the MN and the eNB100A constitutes the SN may be implemented, or NR-NR Dual Connectivity (NR-DC) in which the gNB constitutes both the MN and the SN may be implemented.

[0022] In this way, UE200 supports dual connectivity connecting to eNB100A and gNB100B.

[0023] The eNB 100A is included in a master cell group (MCG), and the gNB 100B is included in a secondary cell group (SCG). In other words, the gNB 100B is an SN included in the SCG.

[0024] The eNB100A and the gNB100B may also be referred to as radio base stations or network devices.

[0025] Furthermore, the wireless communication system 10 may support conditional addition or change of a Primary SCell (PSCell). A PSCell is a type of secondary cell. A PSCell means a Primary SCell (secondary cell), and may be interpreted as corresponding to any one of a plurality of SCells.

[0026] The secondary cell may be read as a secondary node (SN) or a secondary cell group (SCG). The conditional PSCell addition / change can realize efficient and rapid addition or change of a secondary cell.

[0027] The conditional PSCell addition / change may be interpreted as a simplified procedure for adding or changing a conditional secondary cell, and may also mean at least one of adding or changing a SCell.

[0028] Furthermore, a conditional inter-SN PSCell change procedure may be supported in the wireless communication system 10. Specifically, an MN-initiated conditional PSCell change and / or an SN-initiated conditional PSCell change may be supported.

[0029] (2) Functional block configuration of wireless communication system Next, a description will be given of the functional block configuration of the wireless communication system 10. Specifically, the functional block configurations of the eNB100A, the gNB100B, and the UE200 will be described.

[0030] (2.1) eNB100A and gNB100B 2 is a functional block diagram of the eNB 100A and the gNB 100B. As shown in FIG. 2, the eNB 100A and the gNB 100B include a radio communication unit 110, an RRC / Xn processing unit 120, a DC processing unit 130, and a control unit 140.

[0031] The wireless communication unit 110 transmits downlink signals (DL signals) conforming to LTE, and also receives uplink signals (UL signals) conforming to LTE.

[0032] The RRC / Xn processing unit 120 executes various processes related to the radio resource control layer (RRC) and the Xn interface. Specifically, the RRC / Xn processing unit 120 can transmit an RRC Reconfiguration to the UE 200. The RRC / Xn processing unit 120 can also receive an RRC Reconfiguration Complete from the UE 200, which is a response to the RRC Reconfiguration.

[0033] In this embodiment, the eNB 100A supports LTE. In this case, the name of the RRC message may be RRC Connection Reconfiguration or RRC Connection Reconfiguration Complete.

[0034] Furthermore, in the case of a radio base station that supports LTE (Evolved Universal Terrestrial Radio Access Network (E-UTRAN)), an X2 interface may be used instead of an Xn interface. Alternatively, the Xn and X2 interfaces may be used together. The following description will be given taking the Xn interface as an example.

[0035] The RRC / Xn processing unit 120 can transmit and receive inter-node messages via the Xn interface. For example, when configuring a secondary node (SN), the RRC / Xn processing unit 120 may receive a message (first message) related to an SCell (which may include a PSCell, the same applies hereinafter) from another radio base station, specifically, a master node (MN). In this embodiment, the RRC / Xn processing unit 120 configures a receiving unit.

[0036] More specifically, the RRC / Xn processing unit 120 may receive a message including SN change confirm or Accepted candidate cell info (PS Cell ID) from the MN.

[0037] Furthermore, when receiving the message (first message), the RRC / Xn processing unit 120 may transmit to the MN (the other radio base station) a message (second message) including update information (execution condition update indication) of the SCell addition / change procedure, specifically, the execution condition of the conditional PSCell addition / change. In this embodiment, the RRC / Xn processing unit 120 constitutes a transmission unit.

[0038] More specifically, the RRC / Xn processing unit 120 may transmit an SN modification required or an SN change required to the MN. Note that the RRC / Xn processing unit 120 may transmit a newly defined message (new message) to the MN instead of an SN modification required or an SN change required.

[0039] Furthermore, the RRC / Xn processing unit 120 may transmit a message (second message) including information elements that distinguish between the execution condition of the conditional PSCell addition / change and a conditional message of the radio resource control layer, specifically, the conditional RRCReconfig.

[0040] Specifically, for the signaling of CG-Config included in SN modification required or SN change required, the execution condition and the conditional RRCReconfig may be distinguished. For example, a condExecutionConId may be assigned to the execution condition and a condReconfigId may be assigned to the conditional RRCReconfig, or the two may be linked by a PSCell ID.

[0041] The conditional RRCReconfig may be interpreted as an RRC Reconfiguration message that is applied when a condition is met. The condition may be the execution condition of the above-mentioned conditional PSCell addition / change.

[0042] On the other hand, when configuring an MN, the RRC / Xn processing unit 120 may receive a message related to the addition or modification of an SCell from another radio base station, specifically, an SN. The RRC / Xn processing unit 120 may receive a message related to the addition of an SCell and a message related to the modification of an SCell.

[0043] More specifically, the RRC / Xn processing unit 120 may receive an SN change required and / or an SN Addition Request Ack from the SN.

[0044] The DC processing unit 130 performs processing related to dual connectivity, specifically, Multi-RAT Dual Connectivity (MR-DC). In this embodiment, the eNB 100A supports LTE and the gNB 100B supports NR, so the DC processing unit 130 may perform processing related to E-UTRA-NR Dual Connectivity (EN-DC). Note that, as described above, the type of DC is not limited, and may correspond to, for example, NR-E-UTRA Dual Connectivity (NE-DC) or NR-NR Dual Connectivity (NR-DC).

[0045] The DC processing unit 130 can transmit and receive messages specified in 3GPP TS37.340 and the like, and perform processing related to setting up and releasing DC between the eNB100A, the gNB100B, and the UE200.

[0046] The control unit 140 controls each functional block constituting the eNB 100A. Controls the addition or modification of secondary nodes.

[0047] The control unit 140 controls the SCell addition / change procedure, in particular, the execution of conditional PSCell addition / change. Specifically, the control unit 140 can execute SCell addition or change in cooperation with the SN (or MN) based on an execution condition.

[0048] Furthermore, the control unit 140 may determine whether or not the execution condition of the conditional PSCell addition / change has been updated based on the SCell identification information (specifically, the PSCell ID) included in a message from the SN, specifically, the SN change required or the SN Addition Request Ack.

[0049] More specifically, the control unit 140 may determine whether the execution condition has been updated based on whether the PSCell IDs included in the messages match. If the PSCell IDs match, the control unit 140 may determine that the execution condition has not been updated, and if the PSCell IDs do not match, the control unit 140 may determine that the execution condition has been updated.

[0050] That is, the control unit 140 may determine the contents of a conditional message of the radio resource control layer, specifically, a conditional RRCReconfig to be transmitted to the UE 200, based on the result of comparing the identification information (PSCell ID) included in a message regarding the addition of an SCell (e.g., an SN Addition Request Ack) with the identification information (PSCell ID) included in a message regarding a change of an SCell (e.g., an SN change required).

[0051] The PSCell ID may be, for example, the NR Physical Cell ID (PCI) or the NR Cell Global Identifier (CGI).

[0052] In this embodiment, the channels include a control channel and a data channel. The control channels include a PDCCH (Physical Downlink Control Channel), a PUCCH (Physical Uplink Control Channel), a PRACH (Physical Random Access Channel), and a PBCH (Physical Broadcast Channel).

[0053] The data channels include a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

[0054] The reference signal includes a Demodulation Reference Signal (DMRS), a Sounding Reference Signal (SRS), a Phase Tracking Reference Signal (PTRS), and a Channel State Information-Reference Signal (CSI-RS), and the signal includes a channel and a reference signal. Furthermore, the data may refer to data transmitted via a data channel.

[0055] (2.2)UE200 3 is a functional block diagram of the UE 200. As shown in FIG. 3, the UE 200 includes a radio communication unit 210, an RRC processing unit 220, a DC processing unit 230, and a control unit 240.

[0056] The radio communication unit 210 transmits an uplink signal (UL signal) conforming to LTE or NR. The radio communication unit 210 also receives a downlink signal (DL signal) conforming to LTE. That is, the UE 200 can access the eNB 100A (E-UTRAN 20) and the gNB 100B (NG RAN 30) and can support dual connectivity (specifically, EN-DC).

[0057] The RRC processing unit 220 executes various processes in the radio resource control layer (RRC). Specifically, the RRC processing unit 220 can send and receive messages in the radio resource control layer.

[0058] The RRC processing unit 220 can receive RRC Reconfiguration from the network, specifically, the E-UTRAN 20 (or the NG RAN 30). The RRC processing unit 220 can also transmit RRC Reconfiguration Complete, which is a response to the RRC Reconfiguration, to the network.

[0059] The RRC processing unit 220 can also receive a conditional RRCReconfig from the network. The conditional RRCReconfig may be transmitted from the MN, for example.

[0060] The DC processing unit 230 performs processing related to dual connectivity, specifically, MR-DC. As described above, in this embodiment, the DC processing unit 230 may perform processing related to EN-DC, but may also support NE-DC and / or NR-DC.

[0061] The DC processing unit 230 can access each of the eNB100A and the gNB100B and perform configurations at multiple layers including RRC (such as the medium access control layer (MAC), the radio link control layer (RLC), and the packet data convergence protocol layer (PDCP)).

[0062] The control unit 240 controls each functional block constituting the UE 200. In particular, in this embodiment, the control unit 240 controls the execution of conditional PSCell addition / change.

[0063] Specifically, the control unit 240 may monitor the execution condition of the conditional PSCell addition / change and determine whether or not a target PSCell that satisfies the execution condition exists. If a target PSCell that satisfies the execution condition exists, the control unit 240 may return an RRC Reconfiguration Complete to the MN to request the MN to perform RRC reconfiguration of the target PSCell.

[0064] (3) Operation of the wireless communication system Next, a description will be given of the operation of the wireless communication system 10. Specifically, a description will be given of the operation of the wireless communication system 10 relating to the conditional secondary cell (secondary node) addition / change procedure (conditional PSCell addition / change).

[0065] (3.1) Prerequisites and Issues Figure 4 shows an example sequence (part 1) of an SN-initiated conditional PSCell change assumed in 3GPP Release 17. As shown in Figure 4, a source secondary node (S-SN) (e.g., gNB 100B) determines a conditional PSCell change (CPC) (step 2) and sends an SN change required to the MN (step 3). The SN change required may include a candidate cell and an execution condition.

[0066] The MN sends an SN Addition Request to the target secondary node (T-SN) (steps 4a and 4b), and the T-SN returns an SN Addition Request Ack (steps 5a and 5b). The SN Addition Request Ack may include cell group configuration information (CG-Config).

[0067] When the MN is an eNB and the SN is a gNB, the UE 200 monitors the execution condition, and if a target PSCell that satisfies the execution condition exists, the UE 200 returns an RRC Reconfiguration Complete to the MN to request the MN to reconfigure the RRC for the target PSCell (steps 7 and 8).

[0068] Here (see the triangle mark in the figure), if the SN uses FR2 (24.25 GHz to 52.6 GHz), an FR2 measurement gap can be set in the cell measurement (in EN-DC, only the SN can set the FR2 measurement gap), but if the candidate cell in which the FR2 measurement gap is set is not accepted by the T-SN, the measGapConfig becomes unnecessary and needs to be deleted. If the measGapConfig is not deleted, the UE 200 cannot transmit or receive data during the gap period, which may lead to a decrease in throughput, etc.

[0069] For this reason, how to update the execution condition (such as deleting unnecessary measGapConfig) has become an issue.

[0070] Figure 5 shows an example of the relationship between the serving cell of T-SN and the candidate cell designated by S-SN. In the example shown in Figure 5, the serving cell of T-SN and candidate cell 1 designated by S-SN use the same band, and candidate cell 2 and candidate cell 3 designated by S-SN use the same band (which may be different from the serving cell of T-SN).

[0071] In such a case, the T-SN may only be able to reserve candidate cell 1 specified by the S-SN, and may not be able to reserve candidate cell 2 and candidate cell 3 specified by the S-SN, and the S-SN decides to change the execution condition.

[0072] Fig. 6 shows a sequence example (part 2) of an SN-initiated conditional PSCell change assumed in 3GPP Release 17. The sequence shown in Fig. 6 is intended to solve the issues with the sequence shown in Fig. 4.

[0073] As shown in FIG. 6, the S-SN can determine the need to update the RRC Reconfiguration (execution condition) (see the triangle mark in the figure) and request the MN to update the RRC Reconfiguration (steps 9 and 12).

[0074] 7 shows a sequence example (part 3) of an SN-initiated conditional PSCell change assumed in 3GPP Release 17. The sequence shown in FIG. 7 is also intended to solve the issues with the sequence shown in FIG.

[0075] As shown in Figure 7, the MN can send "Accepted candidate cell info" to the S-SN, and the S-SN can respond to the "Accepted candidate cell info" and return "Updated source configuration" to the MN (steps 6 and 7). The updated source configuration can include an updated execution condition.

[0076] However, the sequences shown in FIGS. 6 and 7 still have the following problems.

[0077] (Issue 1): When applying an update request like the one shown in Figure 6, it is unclear what specific messages (inter-node messages) should be used. Also, it is unclear how to actually update the execution condition.

[0078] (Issue 2): When using messages such as those shown in Figure 7 (Accepted candidate cell info and Updated source configuration), if the candidate cell designated by the S-SN by the SN change required matches the candidate cell accepted by the T-SN by the SN Addition Request Ack, the Updated source configuration is not necessary. However, according to the sequence in Figure 7, the MN must wait to receive the Updated source configuration, which causes a delay.

[0079] On the other hand, if the candidate cells do not match, the S-SN does not necessarily need to update the execution condition, and the MN may update the execution condition. In other words, there is room for further improvement in this sequence.

[0080] An example of operation that can solve these problems 1 and 2 will be described below.

[0081] (3.2) Example of operation (3.2.1) Example 1 This operation example can solve Problem 1. Specifically, in an SN-initiated conditional PSCell change, when an S-SN receives an SN change confirm from an MN, if the candidate PSCell accepted by the T-SN is different from the PSCell notified to the MN by the S-SN in an SN change required, it is necessary to change the execution condition set by the S-SN.

[0082] For example, as described above, when an SN uses the FR2 band, an FR2 measurement gap may be set in the cell measurement. However, if a candidate cell that has configured the measGap is not accepted by the T-SN, the measGapConfig becomes unnecessary, and if the measGapConfig is not deleted, this may lead to a decrease in the throughput of UE200.

[0083] In this operation example, the message and change method used for the change are specified. Specifically, after receiving a message including SN change confirm or Accepted candidate cell info (PSCell ID), the S-SN may include an execution condition update indication in an SN change required (or SN modification required) or new message.

[0084] For example, as shown in Fig. 6, an SN change required may be used as an update request (step 9), and the SN change required may include an execution condition update indication. Alternatively, as shown in Fig. 7, after receiving Accepted candidate cell info, an SN change required including an execution condition update indication may be transmitted (step X).

[0085] Furthermore, the signaling of CG-Config included in SN change required (or SN modification required) may be separated into execution condition and conditional RRCReconfig. Furthermore, condExecutionConId and condReconfigId may be assigned to each. Furthermore, the two may be linked by the PSCell ID.

[0086] Fig. 8 shows an example of the configuration of CG-Config (ASN.1 format) according to Operation Example 1. As shown in Fig. 8, the CG-Config included in SN change required / SN modification required / SN Addition Request Ack may have separate information elements (which may be read as fields) for execution condition and conditional RRCReconfig (see underlined parts). Furthermore, such a CG-Config may be applied to Operation Example 2, which will be described later.

[0087] The S-SN may identify unaccepted PSCell IDs based on the PSCell ID information of the accepted candidate cell included in the SN change confirm and the candidate cell information (PSCell ID) included in the SN change required, and extract unnecessary execution condition IDs linked to the identified PSCell IDs. Alternatively, if an unnecessary measGap (e.g., gapFR2) is set, the S-SN may delete the measGap and update the measConfig.

[0088] The S-SN may transmit an SN modification required or an SN change required including the condExecutionCondToRemoveList to the MN. The MN may delete unnecessary execution conditions (measId) based on the received condExecutionCondToRemoveList and transmit an updated conditional RRCReconfig to the UE 200. Alternatively, the SN may transmit an updated execution condition list (with unnecessary execution conditions deleted) or an updated measConfig (for example, with unnecessary measGap deleted) to the MN.

[0089] According to this operation example, the message to be used when an execution condition needs to be updated in the conditional PSCell addition / change (CPAC) procedure (sequence) and the method for changing the execution condition are clarified, making it possible to more reliably update the execution condition in CPAC.

[0090] (3.2.2) Example 2 This operation example can solve Problem 2. Specifically, steps 6 and 7 (Accepted candidate cell info, Updated source configuration) shown in Fig. 7 are required to check the candidate cell designated by the S-SN against the resources secured by the T-SN, but if the resources of the designated cell have been secured, the MN does not need to wait for the Updated source configuration.

[0091] Fig. 9 shows an example of the operation flow of the MN according to Operation Example 2. As shown in Fig. 9, the MN decodes the SN Addition Request Ack transmitted from the T-SN (S10).

[0092] The MN compares the cell information (PSCell ID) and execution condition included in the SN change required with the conditional RRCReconfig (CondReconfigToAddModList) included in the SN Addition Request Ack and the PSCell ID obtained by decoding the SN Addition Request Ack, and determines whether the execution condition has been updated (S20). In other words, the MN determines whether the PSCell ID of the candidate cell(s) in the SN change required matches the PSCell ID reserved by the T-SN in the SN Addition Request Ack.

[0093] Here, if the PSCell IDs match, the MN does not need to wait for an Updated source configuration (execution update) from the SN, but may combine the RRC Reconfiguration and the execution condition to generate a conditional RRCReconfig and transmit the generated conditional RRCReconfig to the UE 200 (S30).

[0094] On the other hand, if the PSCell IDs do not match, that is, if the comparison result is a mismatch, the MN may wait for an Updated source configuration (execution update) from the SN, update the execution condition or measConfig, generate a conditional RRCReconfig using the updated execution condition or measConfig, and transmit the generated conditional RRCReconfig to UE200 (S40).

[0095] Alternatively, the MN may identify the candidate cell that the T-SN did not accept from the PSCell ID included in the SN Addition Request Ack, find the execution condition ID from the CondExecutionCondToAddMod associated with the PSCell ID (see FIG. 8), delete the execution condition, combine the updated execution condition with the RRC Reconfiguration of the candidate cell that the T-SN accepted, generate a conditional RRCReconfig, and transmit the generated conditional RRCReconfig to the UE 200. Note that if gapFR2Setup is set to true in the CondExecutionCondToAddMod (see FIG. 8), the MN may wait for an updated source configuration (execution condition and measConfig update) from the SN.

[0096] After that, the MN may delete the execution condition ID and notify the SN (S-SN) that the execution condition has been updated (S50).

[0097] According to this operation example, when it becomes necessary to update the execution condition in the conditional PSCell addition / change (CPAC) procedure (sequence), it becomes possible to send a conditional RRCReconfig to UE200 more quickly, thereby reducing the delay in CPAC-related settings and the number of signalings, and realizing more efficient CPAC.

[0098] (4) Actions and Effects According to the above-described embodiment, when a radio base station constituting an SN receives a specific message (SN change confirm or Accepted candidate cell info), it can transmit a message (SN modification required or SN change required) including an execution condition update indication to the MN.

[0099] Furthermore, the radio base station constituting the MN can determine whether to update the execution condition of the conditional PSCell addition / change based on the PSCell ID included in a specific message (SN change required or SN Addition Request Ack). Therefore, the execution condition of the conditional PSCell addition / change can be updated appropriately.

[0100] This makes it possible to more reliably update the execution condition even in situations where conditional PSCell addition / change is likely to fail, such as FR2, and further improve the reliability of conditional PSCell addition / change.

[0101] (5) Other embodiments Although the embodiments have been described above, it will be obvious to those skilled in the art that the present invention is not limited to the description of the embodiments and that various modifications and improvements are possible.

[0102] For example, in the above-described embodiment, an EN-DC in which the MN is an eNB and the SN is a gNB has been described as an example, but as described above, other DCs may be used. Specifically, it may be an NR-DC in which the MN is a gNB and the SN is a gNB, or an NE-DC in which the MN is a gNB and the SN is an eNB.

[0103] Furthermore, in the above-described embodiment, the description has been given mainly using the example of conditional PSCell addition / change, but the above-described operation example may also be applied to CHO (Conditional Handover) or Conditional SCG change.

[0104] Also, in the above description, "configure," "activate," "update," "indicate," "enable," "specify," and "select" may be interchangeable. Similarly, "link," "associate," "correspond," and "map" may be interchangeable, and "allocate," "assign," "monitor," and "map" may also be interchangeable.

[0105] Furthermore, specific, dedicated, UE-specific, and UE-dedicated may be interchangeable. Similarly, common, shared, group-common, UE-common, and UE-shared may be interchangeable.

[0106] Furthermore, the block diagrams (FIGS. 2 and 3) used in the description of the above-described 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 a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are connected directly or indirectly (for example, by wire, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining the single device or multiple devices with software.

[0107] Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how each is implemented.

[0108] Furthermore, the above-described eNB100A, gNB100B, and UE200 (the devices) 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 the hardware configuration of the devices. As shown in Fig. 10, the devices may be configured as a computer including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0109] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the apparatus may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0110] Each functional block of the device (see Figure 2.3) is realized by any hardware element of the computer device or a combination of the hardware elements.

[0111] In addition, each function of the device is realized by loading specified software (programs) onto hardware such as processor 1001 and memory 1002, causing processor 1001 to perform calculations, control communication via communication device 1004, and control at least one of reading and writing data in memory 1002 and storage 1003.

[0112] The processor 1001 controls the entire computer by running, for example, an operating system, and may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control unit, an arithmetic unit, a register, and the like.

[0113] The processor 1001 also reads programs (program codes), software modules, data, etc. from at least one of the storage 1003 and the communication device 1004 into the memory 1002, and executes various processes in accordance with these. The programs used are those that cause a computer to execute at least some of the operations described in the above-mentioned embodiments. Furthermore, the various processes described above may be executed by one processor 1001, or may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line.

[0114] The memory 1002 is a computer-readable recording medium and may be configured by, for example, at least one of a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), etc. The memory 1002 can store a program (program code), a software module, etc., that can execute a method according to an embodiment of the present disclosure.

[0115] Storage 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, etc. Storage 1003 may also be referred to as an auxiliary storage device. The above-mentioned recording medium may be, for example, a database, a server, or other appropriate medium including at least one of memory 1002 and storage 1003.

[0116] The communication device 1004 is hardware (transmission / reception device) for communicating 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, or a communication module.

[0117] The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize, for example, at least one of Frequency Division Duplex (FDD) and Time Division Duplex (TDD).

[0118] The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (for example, a display, a speaker, an LED lamp, etc.) that outputs to the outside. The input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0119] Furthermore, each device such as the processor 1001 and the memory 1002 is connected to 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.

[0120] Furthermore, the device 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), or a field programmable gate array (FPGA), 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.

[0121] 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., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB))), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0122] Each aspect / embodiment described in the present disclosure may be applied to at least one of a system using Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, a 4th generation mobile communication system (4G), a 5th generation mobile communication system (5G), Future Radio Access (FRA), New Radio (NR), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth (registered trademark), or other suitable system, and a next-generation system extended based on these. Furthermore, a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A and 5G) may also be applied.

[0123] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless it is consistent. 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.

[0124] In the present disclosure, a specific operation described as being performed by a base station may also be performed by its upper node in some cases. In a network consisting of one or more network nodes having a base station, it is clear that various operations performed for communication with a terminal may be performed by at least one of the base station and another network node other than the base station (for example, an MME or an S-GW, etc., but are not limited to these). Although the above example illustrates a case where there is one other network node other than the base station, a combination of multiple other network nodes (for example, an MME and an S-GW) may also be used.

[0125] Information, signals (information, etc.) 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.

[0126] The input and output information may be stored in a specific location (for example, 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 sent to another device.

[0127] 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).

[0128] Each aspect / embodiment described in this disclosure may be used alone, in combination, or switched depending on the implementation. Furthermore, notification of predetermined information (e.g., notification that "X is true") is not limited to being done explicitly, but may be done implicitly (e.g., by not notifying the predetermined information).

[0129] 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.

[0130] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0131] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, 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.

[0132] Note that terms explained 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 a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0133] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0134] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, may be expressed using relative values ​​from a predetermined value, or may be expressed using other corresponding information. For example, a radio resource may be indicated by an index.

[0135] The names used for the above-described parameters are not intended to be limiting in any way. Furthermore, the mathematical expressions 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 intended to be limiting in any way.

[0136] In this disclosure, terms such as "base station (BS)," "radio 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.

[0137] A base station can accommodate one or more (e.g., three) cells (also called sectors). When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0138] The terms "cell" or "sector" refer to part or all of the coverage area of ​​a base station and / or base station subsystem that provides communication services within that coverage area.

[0139] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0140] 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.

[0141] 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 object, or the mobile object itself. The mobile object may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (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 also include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an Internet of Things (IoT) device such as a sensor.

[0142] Furthermore, a base station in the present disclosure may be read as a mobile station (user terminal, the same applies hereinafter). For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a mobile station is replaced with communication between multiple mobile stations (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the mobile station may be configured to have the functions of a base station. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to communication between terminals (for example, "side"). For example, terms such as uplink channel and downlink channel may be read as side channel.

[0143] Similarly, a mobile station in the present disclosure may be interpreted as a base station, in which case the base station may have the functions of a mobile station. 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.

[0144] Numerology may be a communication parameter applied to at least one of transmission and reception of a signal or channel, such as subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, specific filtering operations performed by a transceiver in the frequency domain, and specific windowing operations performed by a transceiver in the time domain.

[0145] A slot may consist of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol, etc.) A slot may be a numerology-based time unit.

[0146] A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. A minislot may also be called a subslot. A minislot may consist 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.

[0147] The radio frame, subframe, slot, minislot, and symbol all represent time units for transmitting signals, and may be referred to by other names corresponding to the radio frame, subframe, slot, minislot, and symbol.

[0148] 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 existing LTE, 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.

[0149] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station performs scheduling to allocate radio resources (such as frequency bandwidth and transmission power that can be used by each user terminal) to each user terminal in TTI units. However, the definition of TTI is not limited to this.

[0150] 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) to which a transport block, a code block, a code word, etc. is actually mapped may be shorter than the TTI.

[0151] When one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit for scheduling. Also, the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0152] A TTI having a time length of 1 ms may be called a regular TTI (TTI in LTE Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0153] In addition, a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length of more than 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.

[0154] A resource block (RB) is a resource allocation unit in the time domain and 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 numerology, for example, 12. The number of subcarriers included in an RB may also be determined based on numerology.

[0155] The time domain of an RB may include one or more symbols and may be one slot, one minislot, one subframe, or one TTI in length. Each TTI, subframe, etc. may be composed of one or more resource blocks.

[0156] Note that one or more RBs may also 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.

[0157] 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.

[0158] 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 given numerology on a given carrier, where the common RBs may be identified by their index relative to a common reference point of the carrier. PRBs may be defined in a given BWP and numbered within that BWP.

[0159] 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.

[0160] 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 read as "BWP."

[0161] The above-described structures of the radio frame, subframe, slot, minislot, and symbol 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, and other configurations can be changed in various ways.

[0162] 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 one or more wires, cables, and / or 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.

[0163] The reference signal may also be abbreviated as Reference Signal (RS), and may also be called a pilot depending on the applicable standard.

[0164] 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."

[0165] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0166] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. 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 therein or that the first element must precede the second element in some way.

[0167] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0168] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0169] 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, searching, inquiring (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 memory), and the like. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0170] 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."

[0171] 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 herein. 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. [Explanation of symbols]

[0172] 10. Wireless communication systems 20 E-UTRAN 30 NG RAN 40 UPF 100A eNB 100B gNB 110 Radio Communication Department 120 RRC / Xn processing unit 130 DC processing section 140 Control Unit 200 UE 210 Radio Communication Department 220 RRC processing unit 230 DC processing section 240 Control Unit 1001 processor 1002 memory 1003 Storage 1004 Communication equipment 1005 Input Device 1006 Output Device 1007 Bus

Claims

1. a control unit that controls execution of a procedure for adding and changing a secondary cell; a receiving unit that receives a message regarding addition or change of the secondary cell from another radio base station; Equipped with The control unit is a radio base station that determines whether or not to update the execution conditions of the addition / change procedure based on identification information of the secondary cell included in the message.

2. The receiving unit receives a message regarding the addition of the secondary cell and a message regarding the change of the secondary cell, 2. The radio base station according to claim 1, wherein the control unit determines content of a conditional message of a radio resource control layer based on a comparison result between the identification information included in the message regarding the addition of the secondary cell and the identification information included in the message regarding the change of the secondary cell.

3. controlling the execution of a secondary cell addition / modification procedure; receiving a message regarding addition or change of the secondary cell from another radio base station; determining whether or not a condition for executing the addition / change procedure has been updated based on identification information of the secondary cell included in the message; A wireless communication method comprising:

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