Primary and Secondary Nodes

Abstract

The SN (100C) comprises: a sending unit (110b) which sends a first message including setting information of a cell formed by the SN (100C) to the MN (100A) to which the terminal (200) is connected; and a control unit (140b) which determines to delete the setting information of the cell according to the state of the cell. The sending unit (110b) sends a second message to the MN (100A) instructing to delete the setting information of the cell.

Description

Technical Field

[0001] The present invention relates to a master node and a slave node that perform a slave node change process. Background Art

[0002] In the 3rd Generation Partnership Project (3GPP), Long Term Evolution (LTE) was standardized, and LTE-Advanced (hereinafter referred to as LTE including LTE-Advanced) was standardized for the purpose of further speeding up LTE. In addition, in 3GPP, the specifications of the successor systems of LTE, such as 5G or New Radio (NR), are further studied.

[0003] 3GPP stipulates dual connectivity (DC) in which a terminal is simultaneously connected to a master node (MN) and a slave node (SN) (see Non-Patent Document 1).

[0004] The group of cells under the MN is called a master cell group (MCG), and the group of cells under the SN is called a secondary cell group (SCG).

[0005] In addition, in 3GPP, a SN change procedure called Conditional SCG change is being studied (Non-Patent Document 2).

[0006] In Conditional SCG change, the MN notifies the terminals connected to the source SN in advance of the candidate cell setting information including "candidate cells of the migration destination under other SNs and migration conditions to the candidate cells".

[0007] Specifically, other SNs send the candidate cell setting information to the MN according to the request from the MN. The MN notifies the terminal of the received candidate cell setting information.

[0008] When the migration condition to the candidate cell is met, the terminal does not wait for instructions from the MN, but performs a random access process with the SN for which the migration condition to the candidate cell is set, and migrates from the source SN to the SN.

[0009] Prior art literature

[0010] Non-patent literature

[0011] Non-patent document 1: 3GPP TS37.340 V15.6.0, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and NR; Multi-connectivity; Stage 2 (Release 15)

[0012] Non-Patent Document 2: “New WID: NR mobility enhancements”, RP-190489, 3GPP TSG RAN Meeting #83, 3GPP, March 2019 Summary of the invention

[0013] However, in Conditional SCG change, the load on the MN may increase.

[0014] Specifically, when the MN determines whether a candidate cell is suitable as a candidate cell of a migration destination based on the load status of the candidate cell notified from each SN, the load of the MN may increase.

[0015] Furthermore, when the MN includes the setting information of each candidate cell in a dedicated message and transmits it to the terminal, the load of the MN may increase.

[0016] Furthermore, when the MN assigns an identifier used to identify the setting information of each candidate cell to the setting information of the candidate cell, the load on the MN may increase.

[0017] Therefore, the present invention has been completed in view of such a situation, and an object thereof is to provide a master node and a slave node that can avoid an increase in the load of the master node even when the terminal changes the slave node based on the setting information of the candidate cell.

[0018] A secondary node (100C) of one embodiment of the present invention comprises: a sending unit (110b) which sends a first message including setting information of a cell formed by the secondary node (100C) to a primary node (100A) to which a terminal (200) is connected; and a control unit (140b) which determines to delete the setting information of the cell based on the state of the cell, and the sending unit (110b) sends a second message indicating the deletion of the setting information of the cell to the primary node (100A).

[0019] A master node (100A) of one embodiment of the present invention comprises: a receiving unit (120a) which receives setting information of a cell formed by each of the plurality of slave nodes (100C, 100D) from each of the plurality of slave nodes (100C, 100D); a control unit (140a) which includes a list of setting information of the plurality of cells in a specific message; and a sending unit (110a) which sends the specific message to a terminal (200).

[0020] A secondary node (100C, 100D) of one embodiment of the present invention comprises: a control unit (140b) which assigns an identifier to the setting information of the cell formed by the secondary node (100C, 100D); and a sending unit (110b) which sends the setting information of the cell assigned with the identifier to the primary node (100A) to which the terminal (200) is connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a diagram schematically showing the overall structure of the wireless communication system 10 .

[0022] Figure 2 This is a functional block diagram of gNB 100A.

[0023] Figure 3 This is a functional block diagram of gNB 100B, 100C, and 100D.

[0024] Figure 4 This is a diagram showing the suspension sequence of SN addition in Conditional SCG change (action example 1).

[0025] Figure 5 This is a diagram showing the suspension sequence of SN addition in Conditional SCG change (action example 2).

[0026] Figure 6 This is a diagram showing the suspension sequence of SN addition in Conditional SCG change (action example 3).

[0027] Figure 7 This is a diagram showing the suspension sequence of SN addition in Conditional SCG change (action example 4).

[0028] Figure 8 It is a diagram showing the action flow of gNB 100A that encapsulates the setting information of candidate cells.

[0029] Fig. 9This is a diagram illustrating the structure (structure example 1) of RRC reconfiguration in Conditional SCG change.

[0030] Fig.10 This is a diagram illustrating the structure of RRC Reconfiguration in Conditional SCG change (Structural Example 2).

[0031] Fig.11 This is a diagram showing the object ID assignment sequence in Conditional SCG change (action example 1).

[0032] Fig.12 This is a diagram showing the object ID assignment sequence in Conditional SCG change (action example 2).

[0033] Fig.13 This is a diagram showing an example of the hardware structure of gNB 100A, 100B, 100C, and 100D. DETAILED DESCRIPTION

[0034] Hereinafter, the embodiments will be described based on the drawings. In addition, the same or similar reference numerals are given to the same functions and structures, and the description thereof will be appropriately omitted.

[0035] (1) Overall schematic structure of wireless communication system

[0036] Figure 1 The wireless communication system 10 is a wireless communication system based on the New Radio (NR) and includes a Next Generation-Radio Access Network (NG-RAN, not shown) and a terminal 200.

[0037] NG-RAN includes radio base stations 100A, 100B, 100C, and 100D (hereinafter referred to as gNBs 100A, 100B, 100C, and 100D). In addition, the specific structure of the wireless communication system 10 including the number of gNBs and terminals is not limited to Figure 1 Example shown.

[0038] NG-RAN actually includes multiple NG-RAN nodes, specifically, gNB (or ng-eNB), which is connected to the core network (5GC, not shown) based on NR. In addition, NG-RAN and 5GC can also be simply expressed as "network".

[0039] gNB 100A, 100B, 100C, and 100D are wireless base stations based on NR, and perform wireless communication based on NR with terminal 200. Each of gNB 100A, 100B, 100C, and 100D and terminal 200 can support Massive MIMO (Massive MIMO) that generates a beam with higher directivity by controlling wireless signals sent from multiple antenna elements, Carrier Aggregation (CA) that bundles and uses multiple component carriers (CCs), and Dual Connection (DC) that simultaneously communicates between multiple NG-RAN nodes and terminals. In addition, CC can also be called a carrier.

[0040] gNB 100A, 100B, 100C, and 100D each form one or more cells and manage the cells. In NR, cells are classified as follows.

[0041] The group of cells associated with the gNB (also called the master node (MN)) that provides the control plane connected to the core network is called the master cell group (MCG). The MCG consists of a primary cell (hereinafter referred to as PCell) and one or more secondary cells (hereinafter referred to as SCell). The PCell is a cell used by the terminal to start the initial connection with the MN. In addition, the MCG can be composed of only the PCell.

[0042] The group of cells associated with "gNB (also called secondary node (SN)) that does not provide a control plane connected to the core network but provides additional resources to the terminal" is called a secondary cell group (SCG). SCG is composed of a primary SCell (hereinafter referred to as PSCell) and one or more SCells. PSCell is a cell used by the terminal to start the initial connection with the SN. In addition, SCG can be composed of only PSCell.

[0043] In addition, PCell is also called a special cell (SpCell) in MCG. In addition, PSCell is also called a SpCell in SCG.

[0044] In this embodiment, gNB 100A constitutes MN, and gNBs 100B, 100C, and 100D constitute SN. In this case, terminal 200 is connected to gNB 100A (MN) and one of gNBs 100B, 100C, and 100D (SN) to perform DC.

[0045] In DC, the terminal 200 is able to migrate between cells formed by gNB 100B, 100C, 100D (SN) while being connected to gNB 100A (MN). In addition, "migrating between cells formed by gNB 100B, 100C, 100D (SN)" can also be expressed as "migrating between PSCells formed by gNB 100B, 100C, 100D (SN)", "migrating between gNB 100B, 100C, 100D (SN)" or "migrating between wireless base stations 100B, 100C, 100D". In addition, "cells under gNB 100B, 100C, 100D (SN)" refers to "cells formed by gNB 100B, 100C, 100D (SN)".

[0046] The so-called "migration" typically refers to switching between cells or switching between gNBs, but it may also include SN changes, such as changes in the connection destination cell (PSCell) or the connection destination gNB (SN), and other such behaviors of the terminal 200.

[0047] The cell of the migration destination to which the terminal 200 is to migrate is also referred to as a target cell. In addition, the SN of the migration destination to which the terminal 200 is to migrate is also referred to as a target SN. In this embodiment, gNB 100C or gNB 100D is the target SN.

[0048] On the other hand, the cell of the migrating party is also referred to as the source cell. The SN of the migrating party is also referred to as the source SN. In this embodiment, gNB 100B is the source SN.

[0049] In the wireless communication system 10, the terminal 200 performs an SN change called a conditional SCG change in the DC. In addition, the Conditional SCG change may be abbreviated as CSC.

[0050] In Conditional SCG change, MN (gNB 100A) notifies terminal 200 connected to source SN (gNB 100B) in advance of candidate cell setting information including "candidate cells (PSCells) of migration destinations under other SNs (gNB 100C, 100D) and migration conditions to the candidate cells." When the migration conditions to the candidate cells are met, terminal 200 performs a random access (RA) process with the SN that has set the migration conditions to the candidate cells without waiting for instructions from MN, and migrates from the source SN to the SN (target SN).

[0051] In addition, the wireless communication system 10 may include an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) instead of NG-RAN. In this case, the E-UTRAN includes a plurality of E-UTRAN nodes, specifically, eNBs (or en-gNBs), connected to a core network (EPC) based on LTE.

[0052] (2) Functional block structure of wireless communication system

[0053] Next, the functional block structure of the wireless communication system 10 is described. Specifically, the functional block structure of gNB 100A, 100B, 100C, and 100D is described. In the following, only the parts related to the features in this embodiment are described. Therefore, gNB 100A, 100B, 100C, and 100D naturally also have other functional blocks that are not directly related to the features in this embodiment.

[0054] Figure 2 Figure 1 is a functional block diagram of gNB 100A. Figure 2 As shown, gNB 100A constitutes an MN, and has a sending unit 110a, a receiving unit 120a, a retaining unit 130a and a control unit 140a.

[0055] The transmitting unit 110a transmits a downlink signal (DL signal) based on NR. The receiving unit 120a receives an uplink signal (UL signal) based on NR. Specifically, the transmitting unit 110a and the receiving unit 120a perform wireless communication with the terminal 200 via a control channel or a data channel.

[0056] The transmitting unit 110 a transmits a radio resource control (RRC) reconfiguration message (RRCReconfiguration) to the terminal 200 .

[0057] The receiving unit 120 a receives an RRC reconfiguration complete message (Reconfiguration Complete) from the terminal 200 .

[0058] The transmitting unit 110a transmits a signal based on NR to the gNBs 100B, 100C, and 100D constituting the SN. The receiving unit 120a receives a signal based on NR from the gNBs 100B, 100C, and 100D constituting the SN.

[0059] When the terminal 200 is connected to the gNB 100A (MN) and the gNB 100B (source SN) to perform DC, in the SN change led by the MN, the sending unit 110a sends an SN release request message (SN ReleaseRequest) to the gNB 100B (source SN). The receiving unit 120a receives the SN release request response message (SN Release RequestAck) from the gNB 100B (source SN).

[0060] When the terminal 200 is connected to the gNB 100A (MN) and the gNB 100B (source SN) to perform DC, in the SN change led by the SN, the receiving unit 120a receives the SN change request message (SN Change Required) from the gNB 100B (source SN). The sending unit 110a sends the SN change confirmation message (SN Change Confirm) to the gNB 100B (source SN).

[0061] When the terminal 200 is connected to the gNB 100A (MN) and the gNB 100B (source SN) and performs DC, during the execution of the SN change, the sending unit 110a sends an SN addition request message (SNAddition Request) to at least one of the gNBs 100C and 100D (SN). The receiving unit 120a receives an SN addition request response message (SN Addition Request Ack) from at least one of the gNBs 100C and 100D (SN).

[0062] When the terminal 200 is connected to the gNB 100A (MN) and the gNB 100B (source SN) and performs DC, during the execution of the SN change, the sending unit 110a sends an SN reconfiguration completion message (SN Reconfiguration Complete) to at least one of the gNBs 100C and 100D (SN). The receiving unit 120a receives an SN addition and deletion message (SN Addition Cancellation) from at least one of the gNBs 100C and 100D (SN).

[0063] In addition, as described later, SN Addition Request Ack includes the configuration information of the candidate cell, and SNAddition Cancellation indicates the deletion of the configuration information of the candidate cell. In addition, as described later, RRCReconfiguration includes a list including the configuration information of a plurality of candidate cells.

[0064] The holding unit 130a holds the setting information of the candidate cells received from at least one of the gNBs 100C and 100D (SN).

[0065] The control unit 140a controls each functional block that constitutes the gNB 100A (MN).

[0066] The control unit 140a includes the setting information of the candidate cells in the RRC Reconfiguration. In particular, the control unit 140a includes a list including the setting information of a plurality of candidate cells in the RRC Reconfiguration.

[0067] The control unit 140a assigns a transaction identifier (ID) to the RRC Reconfiguration. When the terminal 200 receives the RRC Reconfiguration, the reception unit 120a receives the RRC Reconfiguration Complete including the transaction ID from the terminal 200.

[0068] Figure 3 This is a functional block diagram of gNB 100B, 100C, and 100D. In addition, gNB 100B and 100D have the same structure as gNB 100C, so the description of gNB 100B and 100D is omitted. Figure 3 As shown, gNB 100C constitutes SN, and has a sending unit 110b, a receiving unit 120b, an acquisition unit 130b and a control unit 140b.

[0069] The transmitting unit 110b transmits a signal based on NR to the gNB 100A constituting the MN. The receiving unit 120b receives a signal based on NR from the gNB 100A constituting the MN.

[0070] When the terminal 200 is connected to the gNB 100A (MN) and the gNB 100B (source SN) and performs DC, during the execution of the SN change, the receiving unit 120b receives the SN Addition Request from the gNB 100A (MN). The transmitting unit 110b sends the SN Addition Request Ack to the gNB 100A (MN).

[0071] When the terminal 200 is connected to the gNB 100A (MN) and the gNB 100B (source SN) and performs DC, during the execution of the SN change, the receiving unit 120b receives the SN Reconfiguration Complete from the gNB 100A (MN). The sending unit 110b sends the SN Addition Cancellation to the gNB 100A (MN).

[0072] The acquisition unit 130b acquires the setting information of the candidate cells formed by the gNB 100C (SN).

[0073] The control unit 140b controls each functional block that constitutes the gNB 100C (SN).

[0074] The control unit 140b includes the setting information of the candidate cell obtained by the acquisition unit 130b in the SN AdditionRequest Ack and sends it to the gNB 100A (MN).

[0075] The control unit 140b determines to delete the setting information of the candidate cell according to the state of the candidate cell. When the control unit 140b determines to delete the setting information of the candidate cell, the sending unit 110b sends SN AdditionCancellation to the gNB 100A (MN).

[0076] The control unit 140b determines whether the terminal 200 migrates to the gNB 100C within the specified time according to the setting information of the candidate cell. The sending unit 110b sends SN Addition Cancellation to the gNB 100A (MN) when the terminal 200 does not migrate to the gNB 100C (SN) within the specified time according to the setting information of the candidate cell.

[0077] The control unit 140b assigns a transaction ID to the candidate cell setting information. The sending unit 110b uses SN AdditionRequest Ack to send the candidate cell setting information assigned with the transaction ID to the gNB 100A (MN). When the terminal 200 is connected to the gNB 100B (SN), the receiving unit 120b receives the RRC ReconfigurationComplete including the transaction ID from the terminal 200.

[0078] (3) Operation of wireless communication system

[0079] Next, the operation of the wireless communication system 10 will be described. Specifically, the following operations will be described in sequence.

[0080] Suspension of SN addition in Conditional SCG change

[0081] Structure of RRC Reconfiguration in Conditional SCG change

[0082] · Assigning transaction identifiers (IDs) in Conditional SCG changes

[0083] (3.1) Termination of SN addition in Conditional SCG change

[0084] First, the termination of SN addition in Conditional SCG change is described. In this embodiment, after gNB 100C (SN) sends the setting information of the candidate cell to gNB 100A (MN), it instructs gNB 100A (MN) to delete the setting information of the candidate cell. In addition, Terminal 200 first connects to gNB 100A (MN) and gNB 100B (source SN) to perform DC.

[0085] (3.1.1) Action Example 1

[0086] First, the operation example 1 of stopping the addition of SN in Conditional SCG change is described. In this operation example, the SN change is performed under the leadership of the MN.

[0087] Figure 4 FIG. 1 is a diagram showing the suspension sequence of SN addition in Conditional SCG change (action example 1). Figure 4 As shown, gNB 100A (MN) sends SN AdditionRequest (S11) to gNB 100C and 100D (SN) other than gNB 100B (source SN).

[0088] When receiving SN Addition Request from gNB 100A(MN), gNB 100C(SN) sends SN Addition RequestAck(S13) containing setting information of cells under gNB 100C (referred to as candidate cells) to gNB 100A(MN). The setting information of the candidate cells includes information of the candidate cells and migration conditions to the candidate cells.

[0089] Similarly, when gNB 100D(SN) receives SN Addition Request from gNB 100A(MN), it sends SN AdditionRequest Ack(S13) containing setting information of cells under gNB 100D (referred to as candidate cells) to gNB100A(MN). The setting information of candidate cells includes information of candidate cells and migration conditions to candidate cells.

[0090] In addition, the SN Addition Request Ack sent in S13 is also called the first message.

[0091] When gNB 100A (MN) receives SN Addition Request Ack from gNB 100C and 100D (SN), it sends SN Release Request (S15) to gNB 100B (source SN). When gNB 100B (source SN) receives SN Release Request, it sends SN Release Request Ack to gNB 100A (MN), stops sending data to terminal 200, and releases SN resources (S17).

[0092] When receiving SN Release Request Ack from gNB 100B (source SN), gNB 100A (MN) sends RRC Reconfiguration (S19) to terminal 200. RRC Reconfiguration includes the setting information of the candidate cells received from gNB 100C and 100D (SN).

[0093] When receiving RRC Reconfiguration from gNB 100A(MN), Terminal 200 sends RRC Reconfiguration Complete to gNB 100A(MN) and obtains the setting information of the candidate cell from RRC Reconfiguration (S21).

[0094] When gNB 100A(MN) receives RRC Reconfiguration Complete from terminal 200, it sends SN Reconfiguration Complete (S23) to gNB100C and 100D (SN).

[0095] When the terminal 200 sends RRC Reconfiguration Complete to the gNB 100A (MN), the terminal 200 monitors the Conditional SCG change condition (CSC condition) (S25). Specifically, the terminal 200 determines whether the migration condition to the candidate cell included in the setting information of each candidate cell is satisfied.

[0096] When gNB 100C(SN) recognizes that the candidate cell is in a state that is not suitable for the migration of terminal 200, it sends SN Addition Cancellation(S27) to gNB 100A(MN).

[0097] Specifically, gNB 100C (SN) may send SN Addition Cancellation in S27 when the load in the candidate cell increases and it is determined that the candidate cell is in a state that is not suitable for the migration of the terminal 200.

[0098] In this case, when multiple terminals migrate to a candidate cell and the number of connected terminals exceeds the maximum number of connected terminals allowed by the candidate cell, gNB 100C (SN) may also determine that the candidate cell is in a state that is not suitable for terminal 200 migration.

[0099] For example, when the number of connected terminals in a candidate cell exceeds the maximum number of UE contexts in call acceptance control (CAC), gNB 100C (SN) determines that the candidate cell is in a state that is not suitable for terminal 200 migration.

[0100] In addition, when the terminal 200 does not migrate to the candidate cell within the specified time according to the setting information of the candidate cell (for example, when the terminal 200 remains in an inactive state for more than the specified time), the gNB 100C (SN) may send an SN Addition Cancellation in S27.

[0101] Furthermore, in the case where gNB 100C(SN) receives a UE context release from a gNB or ng-eNB other than gNB 100A(MN), gNB 100C(SN) may also send SN AdditionCancellation in S27.

[0102] In addition, in S27, gNB 100C (SN) may also directly send SN Addition Cancellation to gNB 100A (MN). In this case, the sending of SN Addition Cancellation uses, for example, Xn signaling. Alternatively, gNB 100C (SN) may also send SN Addition Cancellation to gNB 100A (MN) via the core network. In this case, the sending of SN Addition Cancellation uses, for example, NG signaling.

[0103] In addition, the SN Addition Cancellation sent in S27 is also called the second message.

[0104] When gNB 100A(MN) receives SN Addition Cancellation from gNB 100C(SN), after receiving RRC Reconfiguration Complete from terminal 200 in S21, it uses RRC Reconfiguration to notify terminal 200 of the change in the setting information of the candidate cell (S29).

[0105] Specifically, gNB 100A(MN) includes information indicating "deleting the setting information of the candidate cells under gNB 100C(SN)" in RRC Reconfiguration.

[0106] When receiving RRC Reconfiguration from gNB 100A(MN), terminal 200 sends RRC Reconfiguration Complete(S31) to gNB 100A(MN). Based on the reception of RRC Reconfiguration, terminal 200 deletes the setting information of the candidate cells under gNB 100C(SN).

[0107] When gNB 100A (MN) receives RRC Reconfiguration Complete from terminal 200, it sends SN Reconfiguration Complete (S33) to gNB100C and gNB 100D.

[0108] When the terminal 200 determines that the migration condition to the candidate cell is satisfied by the movement of the terminal 200, etc., the terminal 200 does not receive an instruction from the gNB 100A (MN), but decides to start the SN change to the gNB (SN) that manages the candidate cell (S35). In this embodiment, the terminal 200 decides to start the SN change to the gNB 100D (SN).

[0109] When the terminal 200 decides to start the SN change to the gNB 100D (SN), a random access (RA) process is performed between the gNB 100D and the terminal 200 to establish synchronization (S37) between the gNB 100D and the terminal 200. As a result, the terminal 200 is connected to the gNB 100D (target SN).

[0110] In addition, gNB 100A (MN) may also receive only the information of candidate cells from gNB 100C and 100D (SN) in S13. In this case, gNB 100A (MN) uses RRC Reconfiguration in S19 to send the information of candidate cells and the conditions for triggering SN change of terminal 200 to terminal 200.

[0111] In this case, the terminal 200 determines in S25 whether the conditions for triggering the SN change are met. When the terminal 200 determines that the conditions for triggering the SN change are met by the movement of the terminal 200, etc., the terminal 200 determines the candidate cell of the migration destination in S35 and starts the SN change to the gNB (SN) that manages the candidate cell. The terminal 200 determines the candidate cell of the migration destination based on, for example, the priority of each candidate cell assigned by the gNB 100A (MN), the state of the cell included in the information of each candidate cell, etc.

[0112] (3.1.2) Action Example 2

[0113] Next, an operation example 2 of stopping the addition of SN in Conditional SCG change is described. In this operation example, the SN change is performed under the leadership of the MN.

[0114] Figure 5 This is a diagram showing the suspension sequence of SN addition in Conditional SCG change (action example 2). Figure 5 S51~S67 shown are Figure 4 The same processing as S11 to S27 shown in the figure is omitted. In addition, in this action example, gNB 100A (MN) only sends SN Addition Request (S51) to gNB 100C (SN), and receives SN Addition Request Ack (S53) containing the setting information of the candidate cell from gNB 100C.

[0115] After receiving SN Addition Cancellation from gNB 100C (SN), gNB 100A (MN) sends SN Addition Request (S69) to gNB 100D when it finds gNB 100D (SN) existing around gNB 100A (MN).

[0116] When gNB 100D(SN) receives SN Addition Request from gNB 100A(MN), it sends SN Addition Request Ack(S71) including setting information of candidate cells under gNB 100D(SN) to gNB 100A(MN).

[0117] When gNB 100A(MN) receives SN Addition cancellation from gNB 100C(SN) and SN Addition Request Ack from gNB 100D(SN), after receiving RRCReconfiguration Complete from terminal 200 in S61, it uses RRC Reconfiguration to notify terminal 200 of the change in the setting information of the candidate cell (S73).

[0118] Specifically, gNB 100A(MN) only includes the setting information of the candidate cells under gNB 100D in RRCReconfiguration.

[0119] When receiving RRC Reconfiguration from gNB 100A(MN), terminal 200 sends RRC Reconfiguration Complete (S75) to gNB 100A(MN). Based on the reception of RRC Reconfiguration, terminal 200 applies the setting information of the candidate cells under gNB 100D.

[0120] When gNB 100A(MN) receives RRC Reconfiguration Complete from terminal 200, it sends SN Reconfiguration Complete (S77) to gNB100C and 100D.

[0121] When the terminal 200 determines that the migration condition to the candidate cell is satisfied by the movement of the terminal 200, etc., the terminal 200 does not receive an instruction from the gNB 100A (MN), but decides to start the SN change to the gNB (SN) that manages the candidate cell (S79). In this embodiment, the terminal 200 decides to start the SN change to the gNB 100D (SN).

[0122] When the terminal 200 decides to start the SN change to the gNB 100D, a random access (RA) process is performed between the gNB 100D and the terminal 200 to establish synchronization (S81) between the gNB 100D and the terminal 200. As a result, the terminal 200 is connected to the gNB 100D (target SN).

[0123] (3.1.3) Action Example 3

[0124] Next, an operation example 3 of stopping the addition of SN in Conditional SCG change will be described. In this operation example, the SN change is performed in a leading manner by the source SN.

[0125] Figure 6 This is a diagram showing the suspension sequence of SN addition in Conditional SCG change (action example 3). Figure 6 S103~S109, S113~127 shown are Figure 4 Since S11, S13, and S19 to S27 shown are the same processes, their description is omitted.

[0126] gNB 100B (source SN) sends SN Change Required (S101) to gNB 100A (MN). When gNB 100A (MN) receives SN Change Required from gNB 100B (source SN), it sends SNAddition Request (S103) to gNB 100C and 100D (SN).

[0127] When gNB 100A (MN) receives RRC Reconfiguration Complete from terminal 200 (S109), it sends SN Change Confirm (S111) to gNB 100B (source SN). When gNB 100B (source SN) sends SN Change Confirm to gNB 100B (source SN), it sends SN Reconfiguration Complete (S113) to gNB 100C and 100D.

[0128] When gNB 100B (source SN) receives SN Change Confirm from gNB 100A (MN), it stops sending data to terminal 200 and releases SN resources.

[0129] (3.1.4) Action Example 4

[0130] Next, an operation example 4 of stopping the addition of SN in Conditional SCG change will be described. In this operation example, the SN change is performed in a manner led by the source SN.

[0131] Figure 7 This is a diagram showing the suspension sequence of SN addition in Conditional SCG change (action example 4). Figure 7 S153~S159, S163~181 shown are Figure 5 Since S51, S53, and S59 to S81 shown are the same processes, their description is omitted.

[0132] gNB 100B (source SN) sends SN Change Required (S151) to gNB 100A (MN). Upon receiving SN Change Required from gNB 100B (source SN), gNB 100A (MN) sends SN AdditionRequest (S153) to gNB 100C (SN).

[0133] When gNB 100A (MN) receives RRC Reconfiguration Complete from terminal 200 (S159), it sends SN Change Confirm (S161) to gNB 100B (source SN). When gNB 100B (source SN) sends SN Change Confirm to gNB 100B (source SN), it sends SN Reconfiguration Complete (S163) to gNB 100C.

[0134] When gNB 100B (source SN) receives SN Change Confirm from gNB 100A (MN), it stops sending data to terminal 200 and releases SN resources.

[0135] (3.2) Structure of RRC Reconfiguration in Conditional SCG change

[0136] Next, the structure of RRC Reconfiguration in Conditional SCG change is explained. In this structure, RRC Reconfiguration stores the setting information of candidate cells under gNB 100C (SN) and the setting information of candidate cells under gNB100D (SN). In addition, "storing the setting information of multiple candidate cells in RRCReconfiguration" is also expressed as "encapsulating the setting information of multiple candidate cells into RRC Reconfiguration."

[0137] First, the operation flow of encapsulating the setting information of the candidate cells will be described. Figure 8 FIG. 2 is a diagram showing the operation flow of encapsulating the setting information of the candidate cells. Figure 8 As shown, gNB 100A (MN) sends SN Addition Request (S201) to gNB 100C and 100D (SN).

[0138] When gNB 100A (MN) receives the setting information of the candidate cell from gNB 100C and 100D (SN) using SN Addition Request Ack (S203), it encapsulates the setting information of the candidate cell into RRC Reconfiguration (S205).

[0139] When gNB 100A (MN) encapsulates the setting information of multiple candidate cells into RRC Reconfiguration, it sends the RRC Reconfiguration (S207) to terminal 200.

[0140] (3.2.1) Structure example 1

[0141] Next, encapsulation of target candidate cell setting information is described in detail. Fig. 9 This is a diagram illustrating the structure of RRC Reconfiguration in ConditionalSCG change (Structural Example 1).

[0142] like Fig. 9 As shown, the message group for the downlink dedicated control channel (DL-DCCH) includes RRCReconfiguration, RRC recovery message (RRC Resume: RRC recovery), RRC release message (RRC Release: RRC release), RRC establishment message (RRC Reestablishment: RRC reestablishment), security mode command (Security Mode Command) and the like.

[0143] DL-DCCH is a downlink dedicated control channel used by the terminal 200 that has established an RRC connection. The terminal 200 receives the above-mentioned RRC message and the like via the DL-DCCH.

[0144] In this structural example, a new information element (IE) is set in the previous RRC Reconfiguration, and the setting information of the candidate cells under gNB100C and the setting information of the candidate cells under gNB 100D are included in the IE.

[0145] Specifically, as a new IE, an RRC reconfiguration list (RRCReconfigurationList) is set in the conventional RRC Reconfiguration, and configuration for cell 1 (configuration for cell1) and configuration for cell 2 (configuration for cell2) are set in the RRCReconfigurationList. In addition, the number of configurations for cells (configuration for cell) is not limited to two.

[0146] In such a structure, when gNB 100A(MN) receives the setting information of the candidate cell from gNB 100C(SN), it includes the setting information of the candidate cell in configuration forcell1 in RRCReconfigurationList. Similarly, when gNB 100A(MN) receives the setting information of the candidate cell from gNB 100D(SN), it includes the setting information of the candidate cell in configuration for cell2 in RRCReconfigurationList.

[0147] In addition, when terminal 200 receives RRC Reconfiguration from gNB 100A (MN), it obtains the setting information of the candidate cells under gNB100C and the setting information of the candidate cells under gNB 100D from configuration for cell1 and configuration for cell2 in RRCReconfiguration.

[0148] The candidate cell setting information may include at least one of the following information in addition to the candidate cell information and the migration conditions to the candidate cell.

[0149] Measurement conditions

[0150] Structure of candidate cells

[0151] Security information (e.g., security key update information)

[0152] Transaction Identifier

[0153] (3.2.2) Structure example 2

[0154] Fig.10 This is a diagram illustrating the structure of RRC Reconfiguration in Conditional SCG change (Structural Example 2). Fig.10As shown, the message group for DL-DCCH includes RRC reconfiguration (RRC Reconfiguration), RRC resume (RRC Resume), RRC release (RRC Release), RRC reestablishment (RRC Reestablishment), security mode command (Security Mode Command), RRC reconfiguration 1 (RRC Reconfiguration1), etc.

[0155] RRC Reconfiguration1 is a new message different from the previous RRC Reconfiguration, and is an RRC reconfiguration message used in Conditional SCG change. In addition, the name of the new message is not limited to RRCReconfiguration1. In this structural example, the setting information of the candidate cells under gNB 100C and the setting information of the candidate cells under gNB 100D are included in the information element (IE) set in RRC Reconfiguration1.

[0156] Specifically, in the new RRC Reconfiguration 1, an RRC reconfiguration list (RRCReconfigurationList) is set, and in the RRCReconfigurationList, configuration for cell 1 and configuration for cell 2 are set. In addition, the number of configuration for cell is not limited to two.

[0157] In such a structure, when gNB 100A(MN) receives the setting information of the candidate cell from gNB 100C(SN), it includes the setting information of the candidate cell in configuration forcell1 in RRCReconfigurationList. Similarly, when gNB 100A(MN) receives the setting information of the candidate cell from gNB 100D(SN), it includes the setting information of the candidate cell in configuration for cell2 in RRCReconfigurationList.

[0158] When terminal 200 receives RRC Reconfiguration1 from gNB 100A (MN), it obtains the setting information of the candidate cells under gNB100B and the setting information of the candidate cells under gNB 100C from configuration for cell1 and configuration for cell2 in RRCReconfiguration1.

[0159] (3.3) Transaction ID assignment in Conditional SCG change

[0160] Next, the assignment of object ID in Conditional SCG change is explained. In this action, gNB100A (MN) or gNB 100C, 100D (SN) performs the assignment of object ID used in Conditional SCG change.

[0161] (3.3.1) Action Example 1

[0162] First, action example 1 of assigning a thing ID in Conditional SCG change is described. In this action example, gNB 100A (MN) performs the assignment of a thing ID used in Conditional SCG change.

[0163] Fig.11 This is a diagram showing the object ID assignment sequence in Conditional SCG change (action example 1). Fig.11 S251~S257, S265~S271 shown are Figure 4 Since S11 to S17, S23, S25, S35, and S37 shown are the same processes, their description is omitted.

[0164] like Fig.11 As shown, when gNB 100A (MN) receives SN Release Request Ack from gNB 100B (source SN), it includes the setting information of the candidate cells received from gNB 100C and 100D (SN) in RRC Reconfiguration, and assigns a transaction ID to RRC Reconfiguration (S259).

[0165] Specifically, gNB 100A (MN) includes the identification information of the candidate cells under gNB 100C (SN) and the identification information of the candidate cells under gNB 100D (SN) in the RRCReconfigurationList in the RRC Reconfiguration, and sets the transaction ID for the predetermined information element (IE) in the RRC Reconfiguration (refer to Fig. 9 ).

[0166] In addition, gNB 100A (MN) may include the identification information of the candidate cells under gNB 100C (SN) and the identification information of the candidate cells under gNB 100D (SN) in the RRCReconfigurationList in RRC Reconfiguration1, an RRC reconfiguration message used in Conditional SCG change, and set a transaction ID for a predetermined information element (IE) in RRCReconfiguration1 (refer to Fig.10 ).

[0167] The transaction ID may be a value from 0 to 3, or may be a fixed value 0. In this embodiment, the transaction ID takes a value from 0 to 3.

[0168] gNB 100A(MN) may also assign a transaction ID to the RRCReconfigurationList contained in the RRCReconfiguration, that is, the group of encapsulated candidate cell setting information, instead of assigning a transaction ID to the RRC Reconfiguration.

[0169] When setting RRC Reconfiguration, gNB 100A (MN) sends the RRC Reconfiguration (S261) to the terminal 200.

[0170] When receiving RRC Reconfiguration from gNB 100A(MN), terminal 200 sends RRC Reconfiguration Complete (S263) to gNB 100A(MN). Based on the reception of RRC Reconfiguration, terminal 200 obtains the setting information of the candidate cell from RRC Reconfiguration.

[0171] In S263, the terminal 200 includes the transaction ID assigned to the RRC Reconfiguration received from the gNB 100A (MN) in the RRC Reconfiguration Complete.

[0172] Terminal 200 performs CSC condition monitoring (S267), starts SN change to gNB 100D (SN) (S269) and RA process (S271) between gNB 100D (SN) and terminal 200, thereby connecting to gNB 100D (target SN).

[0173] In addition, in this operation example, the assignment of the transaction ID in the SN change initiated by the MN is described, but the present invention is not limited to this. This operation example can also be applied to the SN change initiated by the source SN.

[0174] (3.3.2) Action Example 2

[0175] Next, action example 2 of assigning ID in Conditional SCG change is described. In this action example, gNB 100C, 100D (SN) performs the assignment of object ID used in Conditional SCG change.

[0176] Fig.12 This is a diagram showing the object ID assignment sequence in Conditional SCG change (action example 2). Fig.12 S301, S307 to S321 shown are Figure 4 Since S11, S15 to S25, S35, and S37 shown are the same processes, their description is omitted.

[0177] like Fig.12 As shown, when gNB 100C (SN) receives SN Addition Request from gNB 100A (MN), it includes the setting information of the candidate cell under gNB 100C (SN) in SN Addition Request Ack, and assigns a thing ID to the setting information of the candidate cell (S303). Specifically, gNB 100C (SN) includes the thing ID in the setting information of the candidate cell.

[0178] Similarly, when gNB 100D(SN) receives SN Addition Request from gNB 100A(MN), it includes the setting information of the candidate cell under gNB100D(SN) in SN Addition Request Ack, and assigns a transaction ID to the setting information of the candidate cell (S303). Specifically, gNB 100D(SN) includes the transaction ID in the setting information of the candidate cell.

[0179] The transaction ID may be a value from 0 to 3, or may be a fixed value 0. In this embodiment, the transaction ID takes a value from 0 to 3.

[0180] When gNB 100A(MN) receives SN Addition Request Ack from gNB 100C and 100D(SN), it includes the candidate cell setting information received from gNB 100C and 100D(SN) in RRC Reconfiguration. Specifically, gNB 100A(MN) includes the identification information of the candidate cells under gNB 100C(SN) assigned with the object ID and the identification information of the candidate cells under gNB 100D(SN) assigned with the object ID in RRCReconfigurationList in RRC Reconfiguration (refer to Fig. 9 ).

[0181] In addition, gNB 100A (MN) may include the identification information of the candidate cells under gNB 100C (SN) and the identification information of the candidate cells under gNB 100D (SN) in the RRCReconfigurationList in the RRC Reconfiguration1 used in the Conditional SCG change (refer to Fig.10 ).

[0182] When setting RRC Reconfiguration, gNB 100A (MN) sends RRCReconfiguration (S311) to the terminal 200.

[0183] When receiving RRC Reconfiguration from gNB 100A(MN), terminal 200 sends RRC Reconfiguration Complete (S313) to gNB 100A(MN). Based on the reception of RRC Reconfiguration, terminal 200 obtains the setting information of the candidate cell from RRC Reconfiguration.

[0184] Terminal 200 performs CSC condition monitoring (S317), starts SN change to gNB 100D (SN) (S319), and RA process (S321) between gNB 100D (SN) and terminal 200, thereby connecting to gNB 100D (target SN).

[0185] When the terminal 200 is connected to the gNB 100D (target SN), it sends RRCReconfiguration Complete (S323) to the gNB 100D (target SN).

[0186] In S323, the terminal 200 includes the object ID included in the setting information of the candidate cell under the gNB 100D (target SN) in the RRC Reconfiguration Complete.

[0187] In addition, in this operation example, the assignment of the transaction ID in the SN change initiated by the MN is described, but the present invention is not limited to this. This operation example can also be applied to the SN change initiated by the source SN.

[0188] (4) Function / Effect

[0189] According to the above-mentioned embodiment, gNB 100C(SN) sends SN Addition Request Ack including the setting information of the candidate cell formed by gNB 100C(SN) to gNB 100A(MN) to which terminal 200 is connected. gNB 100C(SN) determines to delete the setting information of the candidate cell according to the state of the candidate cell. gNB 100C(SN) sends SN Addition Cancellation to gNB 100A(MN) to instruct to delete the setting information of the candidate cell.

[0190] According to such a structure, gNB 100A (MN) does not need to judge whether the candidate cell is suitable as a candidate cell of the migration destination based on the load status of the candidate cell notified from gNB 100C (SN).

[0191] Therefore, even when the terminal 200 performs an SN change based on the setting information of the candidate cell, the increase in the load of gNB 100A (MN) can be avoided.

[0192] According to the above-mentioned embodiment, when the terminal 200 does not migrate to the gNB 100C (SN) within the specified time according to the setting information of the candidate cell, the gNB 100C (SN) sends SNAdditionCancellation to the gNB 100A (MN).

[0193] According to such a structure, gNB 100C(SN) can give terminals other than terminal 200 the opportunity to migrate to gNB100C(SN).

[0194] According to the above-mentioned embodiment, gNB 100A(MN) receives the setting information of the candidate cells formed by each gNB(SN) from gNB 100C and 100D(SN) respectively. gNB 100A(MN) includes a list of setting information of multiple candidate cells in RRC Reconfiguration. gNB 100A(MN) sends RRC Reconfiguration to terminal 200.

[0195] According to such a structure, gNB 100A (MN) can include the setting information of multiple candidate cells in one message and send it to terminal 200.

[0196] Therefore, even when the terminal 200 performs an SN change based on the setting information of the candidate cell, the increase in the load of gNB 100A (MN) can be avoided.

[0197] According to the above-mentioned implementation, gNB 100A (MN) assigns a transaction ID to RRC Reconfiguration.

[0198] According to such a structure, gNB 100A(MN) does not need to assign a thing ID to the setting information of each candidate cell.

[0199] Therefore, even when the terminal 200 performs an SN change based on the setting information of the candidate cell, the increase in the load of gNB 100A (MN) can be avoided.

[0200] According to the above-mentioned embodiment, gNB 100C(SN) assigns a thing ID to the setting information of the candidate cell formed by gNB 100C(SN). gNB 100C(SN) sends the identification information of the candidate cell assigned with the thing ID to gNB 100A(MN) to which terminal 200 is connected.

[0201] Similarly, gNB 100D(SN) assigns a thing ID to the setting information of the candidate cell formed by gNB 100D(SN). gNB 100D(SN) sends the identification information of the candidate cell assigned with the thing ID to gNB 100A(MN) to which terminal 200 is connected.

[0202] According to such a structure, gNB 100A(MN) does not need to assign a thing ID to the setting information of each candidate cell.

[0203] Therefore, even when the terminal 200 performs an SN change based on the setting information of the candidate cell, the increase in the load of gNB 100A (MN) can be avoided.

[0204] (5) Other Implementation Methods

[0205] As mentioned above, although the content of this invention was demonstrated based on embodiment, this invention is not limited to these descriptions, and it is obvious to a person skilled in the art that various deformation|transformation and improvement can be made.

[0206] For example, in the above-mentioned implementation, NR is used as an example, but Conditional SCG change can also be applied to LTE, and the same actions can be performed in LTE.

[0207] The block diagram used in the description of the above-mentioned embodiment ( Figure 2 and Figure 3 ) shows blocks in units of functions. These functional blocks (structural parts) are implemented by any combination of at least one of hardware and software. In addition, there is no particular limitation on the implementation method of each functional block. That is, each functional block can be implemented using a device that is physically or logically combined, or two or more physically or logically separated devices can be directly or indirectly connected (for example, using wires, wirelessly, etc.) and implemented using these multiple devices. The functional block can also be implemented by combining software with the above-mentioned one device or the above-mentioned multiple devices.

[0208] Functionally, it includes judging, deciding, determining, calculating, calculating, processing, deriving, investigating, searching, confirming, receiving, sending, outputting, accessing, solving, selecting, selecting, establishing, comparing, assuming, expecting, regarding, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, assigning, etc., but is not limited to these. For example, the functional block (structural part) that enables the sending function is called a transmitting unit or a transmitter. In short, as mentioned above, there is no particular limitation on the implementation method.

[0209] In addition, the above-mentioned gNB 100A, 100B, 100C, 100D and terminal 200 can also function as a computer for processing the wireless communication method disclosed in the present invention. Fig.13 FIG. 1 is a diagram showing an example of the hardware structure of the device. Fig.13 As shown, the device may also be configured as a computer device including a processor 1001, a memory 1002 (memory), a storage 1003 (storage), a communication device 1004, an input device 1005, an output device 1006, and a bus 1007.

[0210] In the following description, the word "device" may be replaced by "circuit", "device", "unit", etc. The hardware structure of the device may include one or more of the devices shown in the figure, or may exclude some of the devices.

[0211] Each functional block of the device is implemented by any hardware element of the computer device or a combination of the hardware elements.

[0212] In addition, each function in the device is implemented by the following method: predetermined software (program) is read into hardware such as processor 1001 and memory 1002, so that processor 1001 performs calculations and controls the communication of communication device 1004 or controls at least one of the reading and writing of data in memory 1002 and storage 1003.

[0213] The processor 1001 controls the entire computer by, for example, running an operating system. The processor 1001 may be constituted by a central processing unit (CPU) including an interface with peripheral devices, a control device, a calculation device, a register, and the like.

[0214] In addition, the processor 1001 reads a program (program code), a software module or data, etc. from at least one of the memory 1003 and the communication device 1004 to the memory 1002, and performs various processes accordingly. As a program, a program that causes a computer to perform at least a part of the actions described in the above-mentioned embodiments is used. In addition, with respect to the above-mentioned various processes, although it is described that the above-mentioned various processes are performed by one processor 1001, the above-mentioned various processes can also be performed simultaneously or sequentially by more than two processors 1001. The processor 1001 can also be installed by more than one chip. In addition, the program can also be sent from the network via a telecommunication line.

[0215] The memory 1002 is a computer-readable recording medium, and may be composed of at least one of a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), a RAM (Random Access Memory), etc. The memory 1002 may also be referred to as a register, a cache, a main memory (main storage device), etc. The memory 1002 may store a program (program code), a software module, etc. that can execute a method according to an embodiment of the present disclosure.

[0216] The memory 1003 is a computer-readable recording medium, and may be composed of at least one of an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a floppy disk, a magneto-optical disk (e.g., a compressed 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. For example, the memory 1003 may also be referred to as an auxiliary storage device. The above-mentioned storage medium may be, for example, other appropriate media such as a database, a server, etc. that includes at least one of the memory 1002 and the memory 1003.

[0217] The communication device 1004 is hardware (transceiver) used to communicate between computers via at least one of a wired network and a wireless network, and may also be called a network device, a network controller, a network card, a communication module, etc.

[0218] The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, and the like, for example, in order to realize at least one of frequency division duplex (FDD) and time division duplex (TDD).

[0219] The input device 1005 is an input device that receives input from the outside (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.). The output device 1006 is an output device that implements output to the outside (e.g., a display, a speaker, an LED light, etc.). In addition, the input device 1005 and the output device 1006 may also be integrally formed (e.g., a touch panel).

[0220] In addition, the processor 1001 and the memory 1002 and other devices are connected via a bus 1007 for communicating information. The bus 1007 may be configured using a single bus or may be configured using different buses for each device.

[0221] In addition, the device may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array), and a part or all of each functional block may be implemented by the hardware. For example, the processor 1001 may also be implemented using at least one of these hardware.

[0222] In addition, the notification of information is not limited to the form / implementation method described in the present disclosure, and other methods may also be used. For example, the notification of information may be implemented through physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information)), high-layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling, broadcast information (MIB (Master Information Block), SIB (System Information Block)), other signals or a combination thereof. In addition, RRC signaling may also be referred to as an RRC message, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, etc.

[0223] Each form / embodiment described in the present disclosure may also be applied to at least one of LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 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, UWB (Ultra-WideBand), Bluetooth (registered trademark), systems using other appropriate systems, and next-generation systems extended therefrom. In addition, a combination of a plurality of systems (for example, a combination of at least one of LTE and LTE-A with 5G, etc.) may be applied.

[0224] The processing procedures, timings, processes, etc. of each form / implementation described in this disclosure may be changed in order without contradiction. For example, for the method described in this disclosure, the elements of various steps are presented in an illustrative order, but are not limited to the specific order presented.

[0225] In the present disclosure, specific actions performed by a base station are sometimes performed by its upper node depending on the situation. In a network consisting of one or more network nodes having a base station, various actions performed to communicate with a terminal can be performed by at least one of the base station and other network nodes other than the base station (for example, consider MME or S-GW, etc., but not limited to these). In the above, the case where there is one other network node other than the base station is illustrated, but the other network node may also be a combination of multiple other network nodes (for example, MME and S-GW).

[0226] Information, signals (information, etc.) can be output from a higher layer (or lower layer) to a lower layer (or higher layer), and can also be input or output via multiple network nodes.

[0227] The input or output information can be stored in a specific location (e.g., memory) or managed using a management table. The input or output information can be rewritten, updated, or appended. The output information can also be deleted. The input information can also be sent to other devices.

[0228] The determination may be made by a value represented by one bit (0 or 1), by a Boolean value (Boolean: true or false), or by comparison of numerical values ​​(for example, comparison with a predetermined value).

[0229] Each form / implementation described in the present disclosure may be used alone or in combination, and may be switched according to execution. In addition, notification of scheduled information is not limited to being performed explicitly (e.g., notification of "yes X"), but may also be performed implicitly (e.g., notification of the scheduled information is not performed).

[0230] Software, whether referred to as software, firmware, middleware, microcode, hardware description language, or by other names, shall be interpreted broadly to refer to commands, sets of commands, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, etc.

[0231] In addition, software, commands, information, etc. may be sent and received via a transmission medium. For example, when software is sent from a web page, server, or other remote source using at least one of wired technology (coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), etc.) and wireless technology (infrared, microwave, etc.), at least one of these wired technology and wireless technology is included in the definition of transmission medium.

[0232] The information, signals, etc. described in the present disclosure may also be represented by any of a variety of different technologies. For example, data, commands, instructions, information, signals, bits, symbols, chips, etc. that may be involved in the above description as a whole may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or photons, or any combination thereof.

[0233] In addition, the terms described in the present disclosure and the terms required for understanding the present disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may also be a signal (signaling). In addition, a signal may also be a message. In addition, a component carrier (CC) may be referred to as a carrier frequency, a cell, a frequency carrier, etc.

[0234] As used in this disclosure, the terms "system" and "network" may be used interchangeably.

[0235] In addition, the information, parameters, etc. described in the present disclosure may be represented by absolute values, relative values ​​to predetermined values, or other corresponding information. For example, wireless resources may also be indicated by indexes.

[0236] The names used for the above parameters are not limiting in any way. Furthermore, the formulas etc. using these parameters may sometimes differ from those explicitly disclosed in this disclosure. Various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by appropriate names, and therefore the various names assigned to these various channels and information elements are not limiting in any way.

[0237] In the present disclosure, the terms "base station (BS)", "wireless base station", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point", "transmission point", "reception point", "transmission / reception point", "cell", "sector", "cell group", "carrier", "component carrier" and the like are used interchangeably. Base stations are sometimes referred to as macrocells, small cells, femtocells, picocells, etc.

[0238] A base station can accommodate one or more (for example, 3) 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 also provide communication services through a base station subsystem (for example, a small base station for indoor use (RRH: Remote Radio Head)).

[0239] The terms "cell" or "sector" refer to a part or the entirety of a coverage area of ​​at least one of a base station and a base station subsystem that provide communication services within the coverage area.

[0240] In the present disclosure, terms such as “mobile station (MS)”, “user terminal (user terminal)”, “user equipment (UE)”, and “terminal” may be used interchangeably.

[0241] For mobile stations, those skilled in the art sometimes also use the following terms: 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 appropriate terms.

[0242] At least one of the base station and the mobile station may also be referred to as a transmitting device, a receiving device, a communication device, etc. In addition, at least one of the base station and the mobile station may be a device mounted on a mobile body, the mobile body itself, etc. The mobile body may be a means of transportation (e.g., a car, an airplane, etc.), a mobile body that moves in an unmanned manner (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). In addition, at least one of the base station and the mobile station also includes a device that does not necessarily move during communication operations. 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.

[0243] In addition, the base station in the present disclosure may also be replaced by a mobile station (user terminal, the same below). For example, regarding a structure in which the communication between a base station and a mobile station is replaced by communication between multiple mobile stations (for example, it may also be referred to as D2D (Device-to-Device), V2X (Vehicle-to-Everything, etc.), the various forms / implementations of the present disclosure may also be applied. In this case, it may also be a structure in which the mobile station has the functions of the base station. In addition, terms such as "uplink" and "downlink" may also be replaced by terms corresponding to communication between terminals (for example, "side"). For example, an uplink channel, a downlink channel, etc. may also be replaced by a side channel.

[0244] Likewise, the mobile station in the present disclosure may be replaced by a base station. In this case, the base station may have the same functions as the mobile station.

[0245] A radio frame may be composed of one or more frames in the time domain. In the time domain, one or more frames may be referred to as subframes.

[0246] A subframe may consist of one or more time slots in the time domain. A subframe may be a fixed time length (eg, 1 ms) that is independent of numerology.

[0247] A parameter set may be a communication parameter applied to at least one of the transmission and reception of a certain signal or channel. The parameter set may, for example, represent at least one of a subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, specific filtering processing performed by a transceiver in the frequency domain, specific windowing processing performed by a transceiver in the time domain, and the like.

[0248] A slot may be composed of one or more symbols (OFDM (Orthogonal Frequency Division Multiplexing) symbols, SC-FDMA (Single Carrier Frequency Division Multiple Access) symbols, etc.) in the time domain. A slot may be a time unit based on a parameter set.

[0249] A time slot may contain multiple mini-slots. Each mini-slot may be composed of one or more symbols in the time domain. In addition, a mini-slot may also be referred to as a sub-slot. A mini-slot may be composed of fewer symbols than a time slot. A PDSCH (or PUSCH) transmitted in units of time greater than a mini-slot may be referred to as a PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a mini-slot may be referred to as a PDSCH (or PUSCH) mapping type B.

[0250] A radio frame, a subframe, a time slot, a mini-time slot, and a symbol all represent time units for transmitting signals. A radio frame, a subframe, a time slot, a mini-time slot, and a symbol may be referred to by other corresponding names.

[0251] For example, 1 subframe can be called a transmission time interval (TTI), multiple consecutive subframes can also be called a TTI, and 1 time slot or 1 mini time slot can also be called a TTI. That is, at least one of the subframe and the TTI can be a subframe (1ms) in the existing LTE, or a period shorter than 1ms (for example, 1-13 code elements), or a period longer than 1ms. In addition, the unit representing TTI can be a time slot, a mini time slot, etc. instead of a subframe.

[0252] Here, TTI refers to, for example, the minimum time unit for scheduling in wireless communication. For example, in the LTE system, the base station schedules the allocation of wireless resources (frequency bandwidth, transmission power, etc. that can be used in each user terminal) to each user terminal in units of TTI. In addition, the definition of TTI is not limited to this.

[0253] TTI can be a transmission time unit for data packets (transport blocks), code blocks, code words, etc. after channel coding, or a processing unit for scheduling, link adaptation, etc. In addition, when TTI is assigned, the time interval (e.g., the number of symbols) to which the transport block, code block, code word, etc. is actually mapped can be shorter than the TTI.

[0254] In addition, when 1 time slot or 1 mini time slot is called TTI, more than one TTI (ie, more than one time slot or more than one mini time slot) can constitute the minimum time unit of scheduling. In addition, the number of time slots (mini time slots) constituting the minimum time unit of scheduling can be controlled.

[0255] A TTI having a time length of 1 ms is also 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 time slot, etc. A TTI shorter than a normal TTI may be called a shortened TTI, a short TTI, a partial or fractional TTI, a shortened subframe, a short subframe, a mini-time slot, a sub-time slot, a time slot, etc.

[0256] In addition, for a long TTI (for example, a normal TTI, a subframe, etc.), it can be replaced with a TTI having a time length exceeding 1ms, and for a short TTI (for example, a shortened TTI, etc.), it can be replaced with a TTI length that is smaller than the long TTI (longTTI) and has a TTI length of more than 1ms.

[0257] A resource block (RB) is a resource allocation unit in the time domain and the frequency domain. In the frequency domain, it may contain one or more consecutive subcarriers. The number of subcarriers contained in an RB may be the same regardless of the parameter set, for example, it may be 12. The number of subcarriers contained in an RB may also be determined according to the parameter set.

[0258] In addition, the time domain of an RB may include one or more symbols, and may be the length of 1 slot, 1 mini slot, 1 subframe, or 1 TTI. 1 TTI, 1 subframe, etc. may be composed of one or more resource blocks, respectively.

[0259] In addition, one or more RBs may be referred to as a physical resource block (PRB: Physical RB), a sub-carrier group (SCG: Sub-Carrier Group), a resource element group (REG: Resource Element Group), a PRB pair, an RB pair, and the like.

[0260] In addition, a resource block may be composed of one or more resource elements (REs). For example, 1 RE may be a radio resource region of 1 subcarrier and 1 symbol.

[0261] Bandwidth Part (BWP) (also called partial bandwidth, etc.) represents a subset of contiguous common RBs (common resource blocks) for a parameter set in a certain carrier. Here, the common RB can be determined by the index of the RB based on the common reference point of the carrier. PRBs are defined in a certain BWP and numbered within the BWP.

[0262] 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.

[0263] At least one of the set BWPs may be active, and it is not assumed that the UE transmits or receives a predetermined signal / channel outside the activated BWP. In addition, "cell", "carrier" and the like in the present disclosure may be replaced with "BWP".

[0264] The above structures of radio frames, subframes, time slots, mini-time slots, and symbols are only examples. For example, the number of subframes included in a radio frame, the number of time slots per subframe or radio frame, the number of mini-time slots included in a time slot, the number of symbols and RBs included in a time slot or mini-time slot, the number of subcarriers included in an RB, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP: Cyclic Prefix) length, and the like can be changed in various ways.

[0265] The terms "connected", "coupled" or all variations of these terms are intended to indicate any direct or indirect connection or combination between two or more elements, and may include the situation where there is one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The combination or connection between elements may be a physical combination or connection, a logical combination or connection, or a combination of these. For example, "access" may be used to replace "connection". In the context of the present disclosure, for two elements, it may be considered that they are "connected" or "coupled" to each other by using at least one of one or more wires, cables, and printed electrical connections, and as some non-limiting and non-inclusive examples, by using electromagnetic energy having wavelengths in the wireless frequency domain, microwave region, and light (including both visible and invisible) region, etc.

[0266] The reference signal may be referred to as RS (Reference Signal) for short, or may be referred to as a pilot signal according to the applied standard.

[0267] The phrase "according to" used in the present disclosure does not mean "only according to" unless otherwise expressly stated. In other words, the phrase "according to" means both "only according to" and "at least according to".

[0268] Any reference to an element using the terms "first", "second", etc. used in this disclosure does not necessarily limit the number and order of these elements. These terms are used in this disclosure as a simple method to distinguish between two or more elements. Therefore, a reference to a first and a second element does not mean that only two elements can be used here or that the first element must precede the second element in any form.

[0269] When the terms "include," "including," and variations thereof are used in the present disclosure, these terms are intended to be inclusive, as is the term "comprising." Furthermore, the term "or" used in the present disclosure does not mean an exclusive or.

[0270] In the present disclosure, when an article is added by translation, such as a, an, and the in English, for example, the present disclosure also includes the case where the noun following the article is in plural form.

[0271] The terms "determining" and "determining" used in the present disclosure sometimes also include situations of various actions. "Determining" and "determining" may include, for example, considering matters that have been judged, calculated, calculated, processed, derived, investigated, searched (for example, searched in a table, database or other data structure), confirmed (ascertaining) as matters that have been "judged" or "determined", etc. In addition, "determining" and "determining" may include considering matters that have been received (for example, receiving information), transmitted (for example, transmitting information), input, output, accessed (for example, accessed data in memory) as matters that have been "judged" or "determined", etc. In addition, "determining" and "determining" may include considering matters that have been resolved (resolving), selected (selecting), chosen (choosing), established (establishing), compared (comparing), etc. as matters that have been "judged" or "determined". That is, "determining" and "determining" may include matters that have been "judged" or "determined" by any action. In addition, the word “determine” can also be replaced by “assuming”, “expecting”, “considering”, etc.

[0272] In the present disclosure, the phrase "A and B are different" may also mean "A and B are different from each other". In addition, the phrase may also mean "A and B are different from C, respectively". The phrases such as "separate" and "combine" may also be interpreted as "different".

[0273] The present disclosure is described in detail above, but it should be 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 as a modification and variation without departing from the subject matter and scope of the present disclosure as determined by the claims. Therefore, the purpose of the description of the present disclosure is to illustrate and not to have any limiting meaning on the present disclosure.

[0274] Industrial Applicability

[0275] According to the above-described master node and slave node, even when the terminal changes the slave node based on the setting information of the candidate cell, it is possible to avoid an increase in the load of the master node, which is useful.

[0276] Description of labels:

[0277] 10 Wireless communication system

[0278] 100A, 100B, 100C, 100D gNB

[0279] 110a, 110b Transmitting unit

[0280] 120a, 120b receiving unit

[0281] 130a Holding portion

[0282] 130b Acquisition Section

[0283] 140a, 140b control unit

[0284] 200 Terminal

[0285] 1001 Processor

[0286] 1002 Memory

[0287] 1003 Memory

[0288] 1004: Communication devices;

[0289] 1005: input device;

[0290] 1006: output device;

[0291] 1007: Bus

Claims

1. A terminal, wherein: The terminal has: a receiving unit that receives a setting message from the master node, the setting message including information of a candidate cell to which a transaction ID is assigned by a target slave node and a migration condition; a control unit, which synchronizes with the candidate cell and performs migration from the source secondary node to the target secondary node when the migration condition is met; as well as A sending unit, which sends a completion message including the transaction ID to the target secondary node when the migration condition is satisfied.

2. A secondary node, wherein: The secondary node has: a control unit that assigns a transaction ID to information of the candidate cells; A sending unit, configured to send the information of the candidate cells to the master node; as well as A receiving unit receives a completion message including the transaction ID from a terminal, wherein the terminal receives a setting message including the information of the candidate cell and a migration condition from the master node and synchronizes with the candidate cell by satisfying the migration condition.

3. A wireless communication system comprising a master node, a source slave node, a target slave node and a terminal, wherein: The target secondary node assigns a transaction ID to the information of the candidate cell; The target secondary node sends the information of the candidate cell to the primary node; The master node sends a setting message including information of the candidate cell and a migration condition to the terminal; When the migration condition is met, the terminal synchronizes with the candidate cell and migrates from the source secondary node to the target secondary node; When the migration condition is met, the terminal sends a completion message including the transaction ID to the target secondary node.

4. A wireless communication method, wherein: The wireless communication method comprises the following steps: The target secondary node assigns a transaction ID to the candidate cell information; The target secondary node sends the information of the candidate cell to the primary node; The master node sends a setting message including the information of the candidate cell and the migration condition to the terminal; When the migration condition is met, the terminal synchronizes with the candidate cell and migrates from the source secondary node to the target secondary node; When the migration condition is met, the terminal sends a completion message including the transaction ID to the target secondary node.

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