WO2023013954A1 - Method and device for changing secondary base station in wireless mobile communication system - Google Patents

Abstract

According to one embodiment of the present disclosure, a method for controlling a secondary base station change comprises a step in which a secondary base station central unit receives a first control message from a main base station, transmits a plurality of second control messages to secondary base station distribution units, receives a plurality of third control messages from the secondary base station distribution units, and transmits, to the main base station, a fourth control message including a first container and a second container, wherein the first container includes a plurality of cell group configurations and the second container includes one NR control message.

Description

A method and apparatus for changing a secondary base station in a wireless mobile communication system.

The present disclosure relates to a method and apparatus for changing a secondary node in a wireless communication system.

In order to meet the growing demand for wireless data traffic after the commercialization of 4G communication systems, 5G communication systems are being developed. In order to achieve a high data rate, the 5G communication system has introduced a very high frequency (mmWave) band (eg, such as the 60 GHz band). In order to mitigate the path loss of radio waves and increase the propagation distance of radio waves in the ultra-high frequency band, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) are used in 5G communication systems. ), array antenna, analog beam-forming and large scale antenna technologies are used. In the 5G communication system, scalability is increased by dividing the base station into a central unit and a distribution unit. In addition, the 5G communication system aims to support very high data rates and very low transmission delays in order to support various services.

Disclosed embodiments are intended to provide a method and apparatus for efficiently supporting a secondary base station change in a wireless communication system.

According to an embodiment of the present disclosure, in a method for controlling switching of a secondary base station, the method includes a secondary base station central unit receiving a first control message from a primary base station and transmitting a plurality of second control messages to the secondary base station distribution unit. and receiving a plurality of third control messages from the secondary base station distribution unit and transmitting a fourth control message including a first container and a second container to the primary base station, wherein the first container includes a plurality of cell group settings, The second container contains one NR control message.

The disclosed embodiments provide a method and apparatus for efficiently supporting a secondary base station change in a wireless communication system.

1 is a diagram illustrating the structure of an LTE system and an E-UTRAN according to the present disclosure.

2 is a diagram illustrating a radio protocol structure in an LTE system according to the present disclosure.

3A is a diagram illustrating structures of a 5G system and an NG-RAN according to an embodiment of the present disclosure.

3B is a diagram illustrating the structure of a GNB according to an embodiment of the present disclosure.

4 is a diagram illustrating a radio protocol structure in a 5G system according to an embodiment of the present disclosure.

5 is a diagram illustrating the structure of an EN-DC according to an embodiment of the present disclosure.

6A is a diagram illustrating operations of a terminal and a base station performing an EN-DC operation according to the first embodiment of the present invention.

6B is a diagram illustrating another operation of a terminal and a base station performing an EN-DC operation according to the first embodiment of the present invention.

Figure 7a is a diagram showing the structure of the LTE reconfiguration message for the first procedure.

Figure 7b is a diagram showing the structure of the LTE reconfiguration message for the second procedure.

7c is a diagram illustrating the structure of an SGNB ADD ACK message for the first procedure.

7d is a diagram illustrating the structure of an SGNB ADD ACK message for the second procedure.

8 is a flowchart illustrating an operation of the central apparatus of a target secondary base station according to the first embodiment.

9 is a flowchart for explaining a terminal operation according to the first embodiment.

10 is a block diagram showing the internal structure of a terminal to which the present invention is applied.

11 is a block diagram showing the internal structure of a base station to which the present invention is applied.

Hereinafter, embodiments of the present invention will be described in detail with accompanying drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or operator. Therefore, the definition will have to be made based on the contents throughout this specification.

A term used in the following description to identify a connection node, a term referring to network entities, a term referring to messages, a term referring to an interface between network entities, and a term referring to various types of identification information. Etc. are illustrated for convenience of description. Therefore, the present invention is not limited to the terms described below, and other terms indicating objects having equivalent technical meanings may be used.

For convenience of description below, the present invention uses terms and names defined in the 3rd Generation Partnership Project (3GPP) standard, which is the most up-to-date among existing communication standards. However, the present invention is not limited by the above terms and names, and may be equally applied to systems conforming to other standards.

Table 1 lists the abbreviations used in the present invention.

Acronym	full name	Acronym	full name
5GC	5G Core Network	NG-RAN	NG Radio Access Network
5GS	5G System	NR	NR Radio Access
5QI	5G QoS Identifier	NR-DC	NR-NR Dual Connectivity
ACK	Acknowledgment	PBR	Prioritized Bit Rate
AMF	Access and Mobility Management Function	PCC	Primary Component Carrier
ARQ	Automatic Repeat Request	PCell	Primary Cell
AS	Access Stratum	PCI	Physical Cell Identifier
ASN.1	Abstract Syntax Notation One	PDCCH	Physical Downlink Control Channel
BSR	Buffer Status Report	PDCP	Packet Data Convergence Protocol
BWP	Bandwidth Part	PDSCH	Physical Downlink Shared Channel
CA	Carrier Aggregation	PDUs	Protocol Data Unit
CAG	Closed Access Group	PLMN	Public Land Mobile Network
CAG-ID	Closed Access Group Identifier	PRACH	Physical Random Access Channel
CG	Cell Group	PRB	Physical Resource Block
CHO	Conditional Handover	PSCell	Primary SCG Cell
CIF	Carrier Indicator Field	PSS	Primary Synchronization Signal
CORESET	Control Resource Set	PUCCH	Physical Uplink Control Channel
CPC	Conditional PSCell Change	PUSCH	Physical Uplink Shared Channel
CQI	Channel Quality Indicator	PWS	Public Warning System
C-RNTI	Cell RNTI	QFI	QoS Flow ID
CSI	Channel State Information	QoE	Quality of Experience
DC	Dual Connectivity	QoS	Quality of Service
DCI	Downlink Control Information	RACH	Random Access Channel
DRB	(user) Data Radio Bearer	RAN	Radio Access Network
DRX	Discontinuous Reception	RA-RNTI	Random Access RNTI
ECGI	E-UTRAN Cell Global Identifier	RAT	Radio Access Technology
eNB	E-UTRAN NodeB	RB	Radio Bearer
EN-DC	E-UTRA-NR Dual Connectivity	RLC	Radio Link Control
EPC	Evolved Packet Core	RNA	RAN-based Notification Area
EPS	Evolved Packet System	RNAU	RAN-based Notification Area Update
E-RAB	E-UTRAN Radio Access Bearer	RNTI	Radio Network Temporary Identifier
ETWS	Earthquake and Tsunami Warning System	RRC	Radio Resource Control
E-UTRA	Evolved Universal Terrestrial Radio Access	RRM	Radio Resource Management
E-UTRAN	Evolved Universal Terrestrial Radio Access Network	RSRP	Reference Signal Received Power
FDD	Frequency Division Duplex	RSRQ	Reference Signal Received Quality
FDM	Frequency Division Multiplexing	RSSI	Received Signal Strength Indicator
GBR	Guaranteed Bit Rate	SCC	Secondary Component Carrier
HARQ	Hybrid Automatic Repeat Request	SCell	Secondary Cell
HPLMN	Home Public Land Mobile Network	SCG	Secondary Cell Group
IDC	In-Device Coexistence	SCS	Subcarrier Spacing
IE	Information element	SDAP	Service Data Adaptation Protocol
IMSI	International Mobile Subscriber Identity	SDU	Service Data Unit
KPAS	Korean Public Alert System	SeNB	Secondary eNBs
L1	Layer 1	SFN	System Frame Number
L2	Layer 2	S-GW	Serving Gateway
L3	Layer 3	SI	System Information
LCG	Logical Channel Group	SIB	System Information Block
MAC	Medium Access Control	(S-/T-)SN	(Source/Target) Secondary Node
MBR	Maximum Bit Rate	SpCell	Special Cell
MCG	Master Cell Group	SRB	Signaling Radio Bearer
MCS	Modulation and Coding Schemes	SRS	Sounding Reference Signal
MeNB	Master eNB	SSB	SS/PBCH block
MIB	Master Information Block	SSS	Secondary Synchronization Signal
MIMO	Multiple Input Multiple Output	SUL	Supplementary Uplinks
MME	Mobility Management Entity	TDD	Time Division Duplex
MN	Master Node	TDM	Time Division Multiplexing
MR-DC	Multi-Radio Dual Connectivity	TRP	Transmit/Receive Point
NAS	Non-Access Stratum	UCI	Uplink Control Information
NCGI	NR Cell Global Identifier	UE	User Equipment
NE-DC	NR-E-UTRA Dual Connectivity	UL-SCH	Uplink Shared Channel
NGEN-DC	NG-RAN E-UTRA-NR Dual Connectivity	UPF	User Plane Function

Table 2 defines terms frequently used in the present invention.

Terminology	Definition
Cell	combination of downlink and optionally uplink resources. The linking between the carrier frequency of the downlink resources and the carrier frequency of the uplink resources is indicated in the system information transmitted on the downlink resources.
Global cell identity	An identity to uniquely identify an NR cell. It is consisted of cellIdentity and plmn-Identity of the first PLMN-Identity in plmn-IdentityList in SIB1.
gNB	node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC.
Information element	A structural element containing single or multiple fields is referred as information element.
NR	NR radio access
PCell	SpCell of a master cell group.
Primary SCG Cell	For dual connectivity operation, the SCG cell in which the UE performs random access when performing the Reconfiguration with Sync procedure.
Serving Cell	For a UE in RRC_CONNECTED not configured with CA/DC there is only one serving cell comprising of the primary cell. For a UE in RRC_CONNECTED configured with CA/ DC the term 'serving cells' is used to denote the set of cells comprising of the Special Cell(s) and all secondary cells.
SpCell	primary cell of a master or secondary cell group.
Cell Group	in dual connectivity, a group of serving cells associated with either the MeNB or the SeNB.
En-gNB	node providing NR user plane and control plane protocol terminations towards the UE, and acting as Secondary Node in EN-DC.
Master Cell Group	in MR-DC, a group of serving cells associated with the Master Node, comprising of the SpCell (PCell) and optionally one or more SCells.
master node	in MR-DC, the radio access node that provides the control plane connection to the core network. It may be a Master eNB (in EN-DC), a Master ng-eNB (in NGEN-DC) or a Master gNB (in NR-DC and NE-DC).
NG-RAN node	either a gNB or an ng-eNB.
PSCell	SpCell of a secondary cell group.
Secondary Cell	For a UE configured with CA, a cell providing additional radio resources on top of Special Cell.
Secondary Cell Group	in MR-DC, a group of serving cells associated with the Secondary Node, comprising of the SpCell (PSCell) and optionally one or more SCells.
Secondary node	in MR-DC, the radio access node, with no control plane connection to the core network, providing additional resources to the UE. It may be an en-gNB (in EN-DC), a Secondary ng-eNB (in NE-DC) or a Secondary gNB (in NR-DC and NGEN-DC).
Conditional PSCell Change	a PSCell change procedure that is executed only when PSCell execution condition(s) are met.
gNB Central Unit (gNB-CU)	a logical node hosting RRC, SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected with the gNB-DU.
gNB Distributed Unit (gNB-DU)	a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU. One gNB-DU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected with the gNB-CU.
E-RAB	An E-RAB uniquely identifies the concatenation of an S1 Bearer and the corresponding Data Radio Bearer. When an E-RAB exists, there is a one-to-one mapping between this E-RAB and an EPS bearer of the Non Access Stratum (NAS) as defined in TS 23.401 [3].

Table 3 is an abbreviation of various messages, IEs, and terms of the present invention.

Abbreviation	Message/IE/Terminology
LTE RECNF	RRCConnectionReconfiguration
LTE RECNF CMP	RRCConnectionReconfigurationComplete
CAPENQ	UECapabilityInquiry
CAPINF	UECapabilityInformation
NR RECNF	RRCReconfiguration
NR RECNF CMP	RRCReconfigurationComplete
ULIT	ULInformationTransferMRDC
SGNB ADD REQ	SGNB ADDITION REQUEST
SGNB ADD ACK	SGNB ADDITION REQUEST ACKNOWLEDGE
SGNB REL REQ	SGNB RELEASE REQUEST
SGNB REL ACK	SGNB RELEASE REQUEST ACKNOWLEDGE
SGNB RECNF CMP	SGNB RECONFIGURATION COMPLETE
CON SET REQ	UE CONTEXT SETUP REQUEST
CON SET RES	UE CONTEXT SETUP RESPONE
SN STA TRA	SN STATUS TRANSFER
Transaction ID	rrc-TransactionIdentifier
TCSPCELL	Target Candidate SpCell
CRID	CondReconfigurationId

Table 4 is a description of the main technical terms used in the present invention.

Terminology	Definition
PSCell change	This means that the current PSCell is changed to a new PSCell, and includes a change of the PSCell within the same SN and a change of the PSCell between SNs. In addition, the addition of a PSCell can also be seen as a PSCell change.
CG-ConfigInfo IE	It is transmitted from the MN to the SN or from the CU to the DU and consists of the following information. l Capability information of the UE (ue-CapabilityInfo) l Measurement results of candidate cells that can be added as serving cells (MeasResultList2NR) l MCG's DRX information, etc.
CG-Config IE	SN delivers to MN or CU to DU and consists of the following information l NR RRCReconfiguration message containing SCG configuration information. The MN transmits the RRCReconfiguration message to the UE as it is without processing it. l Information related to the SCG bearer. It includes information specifying a security key to be used in the bearer. l DRX setting information of SCG l ARFCN information indicating the center frequency of PSCell
measConfig	This is measurement-related information set independently by MN and SN. It is composed of at least one measurement object information (MeasObject), at least one report setting information (ReportConfig), and at least one measurement identifier (MeasId). Measurement target information and report setting information are identified as MeasObjectId and ReportConfigId, respectively, and MeasId consists of one MeasObjectId and one ReportConfigId. MeasId is information instructing to perform a predetermined operation when the measurement result for the related MeasObject meets the condition set in ReportConfigId.
TCSPCELL	Indicates the target candidate SpCell. In the first procedure, several cells in one target node may be configured as target candidate SpCells. The TCSPCELL may be a cell selected by the MN or the S-SN from among cells measured by the UE and reporting the measurement result to the BS. Through the first procedure, one of the TCSPCELLs becomes a PSCell.

1 is a diagram illustrating the structure of an LTE system and an E-UTRAN according to an embodiment of the present disclosure. The E-UTRAN 101 includes an E-UTRA user plane (PDCP/RLC/MAC/PHY) and a control plane. It consists of ENBs 102, 103, and 104 that provide (RRC) to the UE. ENBs are interconnected with each other via the X2 interface. The ENB is connected to a Mobility Management Entity (MME) 105 / Serving-Gateway (S-GW) 106 through an S1 interface. The S1 interface supports a many-to-many relationship between MME/S-GW and ENB. MME 105 and S-GW 106 may be configured as one physical node or separate physical nodes.

The eNBs 102, 103, 104 host the functions listed below.

Functions for radio resource management: radio bearer control, radio admission control, link mobility control, dynamic allocation of resources to UEs in uplink, downlink and sidelink (constant);

IP and Ethernet header compression, uplink data decompression and encryption of user data streams

AMF selection when AMF cannot be selected with information provided by the terminal, routing of user plane data to UPF, scheduling and transmission of paging messages, scheduling and transmission of broadcast information (derived from AMF or O&M), for mobility and scheduling Measurement and measurement reporting configuration, session management, QoS flow management and mapping to data radio bearers, RRC_INACTIVE support, radio access network sharing, tight interaction between NR and E-UTRA, network slicing support

MME 105 hosts functions such as NAS signaling, NAS signaling security, AS security control, S-GW selection, authentication, PWS message transmission support and location management.

The S-GW 106 hosts functions such as packet routing and forwarding, uplink and downlink transport level packet marking, and mobility anchoring for handover between eNBs.

2 is a diagram illustrating a radio protocol structure of an LTE system.

The user plane protocol stack is composed of PDCP (201 to 202), RLC (203 to 204), MAC (205 to 206), and PHY (207 to 208). The control clearing protocol stack is composed of NAS (209 to 210), RRC (211 to 212), PDCP, RLC, MAC, PHY.

Each protocol sublayer performs functions related to the operations listed in Table 5.

Sublayer	Functions
NAS	Authentication, mobility management, security control, etc.
RRC	System information, paging, RRC connection management, security functions, signaling radio bearer and data radio bearer management, mobility management, QoS management, recovery from radio link failure detection and recovery, NAS message transmission, etc.
PDCP	Data transmission, header compression and decompression, encryption and decryption, integrity protection and integrity verification, redundant transmission, ordering and out-of-order delivery, etc.
RLC	Upper layer PDU transmission, error correction through ARQ, RLC SDU concatenation/division/reassembly, RLC data PDU reassembly, RLC re-establishment, etc.
MAC	Mapping between logical channels and transport channels, multiplexing/demultiplexing MAC SDUs belonging to one or another logical channel in a transport block (TB) carried in the physical layer, information reporting schedule, priority processing between UEs, priority between single UE logical channels ranking processing, etc.
PHY	Channel coding, physical layer hybrid-ARQ processing, rate matching, scrambling, modulation, layer mapping, downlink control information, uplink control information, etc.

3A is a diagram illustrating structures of a 5G system and an NG-RAN according to an embodiment of the present disclosure. The 5G system consists of NG-RAN (301) and 5GC (302). An NG-RAN node is one of the two below.

gNB providing NR user plane and control plane towards UE; or

ng-eNB providing E-UTRA user plane and control plane towards UE.

The gNBs 305 to 306 and the ng-eNBs 303 to 304 are interconnected through an Xn interface. The gNB and ng-eNB are connected to an Access and Mobility Management Function (AMF) 307 and a User Plane Function (UPF) 308 through an NG interface. AMF 307 and UPF 308 may be configured as one physical node or separate physical nodes.

gNBs 305 to 306 and ng-eNBs 303 to 304 host the functions listed below.

Functions for radio resource management: radio bearer control, radio admission control, link mobility control, dynamic allocation of resources to UEs in uplink, downlink and sidelink (constant);

IP and Ethernet header compression, uplink data decompression and encryption of user data streams

AMF selection when AMF cannot be selected with information provided by the terminal, routing of user plane data to UPF, scheduling and transmission of paging messages, scheduling and transmission of broadcast information (derived from AMF or O&M), for mobility and scheduling Measurement and measurement reporting configuration, session management, QoS flow management and mapping to data radio bearers, RRC_INACTIVE support, radio access network sharing, tight interaction between NR and E-UTRA, network slicing support

AMF 307 hosts functions such as NAS signaling, NAS signal security, AS security control, S-GW selection, authentication, mobility management and location management.

UPF 308 hosts functions such as packet routing and forwarding, transport level packet marking on the uplink and downlink, QoS management, and mobility anchoring for mobility.

3B is a diagram illustrating the structure of a GNB according to an embodiment of the present disclosure.

The gNBs 311 to 312 may include one gNB-CU 313 and one or more gNB-DUs 314 to 315. The gNB-CU and gNB-DU are connected through the F1 interface. One gNB-DU is connected only to one gNB-CU. The gNB-CU provides RRC, SDAP, and PDCP protocol sublayers, and the gNB-DU provides RLC, MAC, and PHY protocol sublayers.

4 is a diagram illustrating a radio protocol structure of a 5G system.

The user plane protocol stack is composed of SDAP (401 to 402), PDCP (403 to 404), RLC (405 to 406), MAC (407 to 408), and PHY (409 to 410). The control clearing protocol stack is composed of NAS (411 to 412), RRC (413 to 414), PDCP, RLC, MAC, PHY.

Each protocol sublayer performs functions related to the operations listed in Table 8.

Sublayer	Functions
NAS	Authentication, mobility management, security control, etc.
RRC	System information, paging, RRC connection management, security functions, signaling radio bearer and data radio bearer management, mobility management, QoS management, recovery from radio link failure detection and recovery, NAS message transmission, etc.
SDAP	Mapping between QoS flows and data radio bearers, QoS flow ID (QFI) marking of DL and UL packets.
PDCP	Data transmission, header compression and decompression, encryption and decryption, integrity protection and integrity verification, redundant transmission, ordering and out-of-order delivery, etc.
RLC	Higher layer PDU transmission, error correction through ARQ, RLC SDU division and re-division, SDU reassembly, RLC re-establishment, etc.
MAC	Mapping between logical channels and transport channels, multiplexing/demultiplexing MAC SDUs belonging to one or another logical channel in a transport block (TB) carried in the physical layer, information reporting schedule, priority processing between UEs, priority between single UE logical channels ranking processing, etc.
PHY	Channel coding, physical layer hybrid-ARQ processing, rate matching, scrambling, modulation, layer mapping, downlink control information, uplink control information, etc.

5 is a diagram showing the structure of EN-DC according to an embodiment of the present disclosure. E-UTRAN supports MR-DC through E-UTRA-NR dual connectivity (EN-DC), and the UE It is connected to one eNB (501 to 502) serving as an MN and one en-gNB (503 to 504) serving as an SN. The eNBs 501 to 502 are connected to the EPC 505 through an S1 interface and connected to the en-gNBs 503 to 504 through an X2 interface. The en-gNBs 503 - 504 may be connected to the EPC 505 via the S1-U interface and another en-gNB via the X2-U interface.

LTE and NR are expected to coexist for a considerable period of time in the future. It will not be uncommon for one operator to have both LTE and NR. In this case, if the terminal simultaneously transmits and receives data in LTE and NR, the terminal can receive a high transmission rate through NR and stably maintain an RRC connection through LTE. When EN-DC is set, the terminal can transmit and receive data through LTE and NR.

When operating as an EN-DC, frequent replacement of SNs is required because the coverage of NRs is narrow. Since the SN change procedure inevitably requires a change of the PSCell, it is also referred to as a PSCell change procedure. The PSCell change procedure generally consists of a process in which the MN or S-SN recognizes the need for change, the T-SN determines configuration information of the new PSCell, and the MN informs the UE of the configuration information of the new PSCell. Depending on the situation of the terminal, there are cases where the PSCell needs to be changed immediately when the PSCell configuration information is given, and there are cases where it is desirable to change the PSCell when a predetermined condition is met. In the present invention, the latter is referred to as first reconstruction (or conditional reconstruction), and the former is referred to as second reconstruction (or immediate reconstruction). In the present invention, operations of a terminal and a base station performing first and second reconfiguration are presented.

6A is a diagram for explaining operations of a terminal and a base station performing a second procedure according to the first embodiment of the present invention.

In step 606, the S-SN GNB-CU 603 determines to change the SN of a predetermined terminal through the second procedure. The determination may be made based on a measurement result reported by the terminal, a load of the base station, a radio resource management policy, and the like. The S-SN GNB-CU initiates the procedure by sending an SGNB CHA REQ (606) to the MN (602). SGNB CHA REQ includes the following information.

Target node identifier information: en-gNB ID of the target node

Container containing cell group configuration information CG-ConfigInfo: CG-ConfigInfo includes configuration information applied to the UE by the S-SN.

In step 608, the MN generates an SGNB ADD REQ based on the information of the SGNB CHA REQ message and transmits it to the T-SN GNB-CU 604 indicated in the target node identifier information. The SGNB ADD REQ includes the following information.

MeNB Cell ID: PCell's ECGI. With this information, the T-SN considers cells around the MeNB Cell as SpCells.

SGNB Addition Trigger Indication: IE indicating one of SN change, inter-eNB HO, and intra-eNB HO.

Container containing CG-ConfigInfo

Information related to data radio bearer setup: Information about the radio bearer to be setup. Can be used for T-SN's call admission control.

Information about the maximum transmission rate: the expected maximum data rate for the call. Can be used for T-SN's call admission control.

Upon receiving the information, the T-SN GNB-CU determines whether to accept the SGNB addition request for the UE. If accepted, it is determined which bearer to accept among the bearers of the UE. Then, PDCP configuration information is determined for each accepted bearer.

In step 611, the T-SN GNB-CU transmits CON SET REQ to the T-SN GNB-DU (605). CON SET REQ includes the following information.

SpCell ID: Identifier of SpCell determined by T-SN GNB-CU

CG-Config: PDCP configuration information for each bearer determined by the T-SN GNB-CU, etc.

Upon receiving the CON SET REQ, the T-SN GNB-DU determines which bearer of the UE to accept the SN change request. If it is decided to accept, RLC configuration information, MAC configuration information, etc. of the accepted bearer are determined. Then, PHY configuration information to be applied to the terminal is determined.

In step 613, the T-SN GNB-DU transmits CON SET RES to the T-SN GNB-CU. CON SET RES includes the following information.

CellGroupConfig: Various setting information such as RLC setting information and MAC setting information determined in the above step. Although the name is similar, it is information different from CG-config.

C-RNTI: C-RNTI to be used by the terminal

Requested Target Cell ID: The SpCell ID that was included in the CON SET REQ. Indicates that CON SET RES is a response message to CON SET REQ.

Upon receiving the CON SET RES, the T-SN GNB-CU generates NR RECNF using CellGroupConfig and various configuration information determined by itself. Then, CG-Config including the NR RECNF and various information useful to the MN is created.

In step 615, the T-SN GNB-CU transmits an SGNB ADD ACK to the MN. SGNB ADD ACK includes CG-Config. The structure of the SGNB ADD ACK is detailed in FIG. 7-4.

Upon receiving the SGNB ADD ACK, the MN generates LTE RECNF including NR RECNF included in CG-Config. LTE RECNF includes NR RECNF, first Transaction id, security key information, and the like. The structure of LTE RECNF for the second procedure is detailed in FIG. 7-2.

In step 617, the MN transmits LTE RECNF to the UE. Upon receiving the LTE RECNF, the terminal processes the NR RECNF information included in the LTE RECNF to recognize in which cell random access should be performed and which setting should be applied in the new cell.

In step 619, the UE transmits an LTE RECNF CMP to the MN. The LTE RECNF CMP includes a first Transaction id and NR RECNF CMP. Upon receiving the LTE RECNF CMP, the MN sees the first Transaction id and recognizes that the LTE RECNF CMP is a response to the LTE RECNF. In addition, MN settings may be adjusted by referring to CG-Config corresponding to the LTE RECNF.

In step 621, the MN transmits the SGNB REC CMP to the T-SN GNB-CU. Upon receiving the SGNB REC CMP, the T-SN GNB-CU recognizes that the UE has received NR RECNF and will initiate a random access procedure.

In step 623, the MN transmits the SGNB CHA CNF to the S-SN GNB-CU. Upon receiving the SGNB CHA CNF, the S-SN GNB-CU may initiate an SN status transmission procedure and data forwarding.

In step 625, the UE performs a random access process in a specific cell of T-SN GNB-DU and a cell designated as SpCell in NR RECNF. Random access consists of the UE transmitting a preamble in the GNB-DU, the GNB-DU transmitting a random access response to the UE, and the UE transmitting the PUSCH in the GNB-DU. Through the PUSCH, the UE transmits the C-RNTI MAC CE. The C-RNTI MAC CE contains the C-RNTI determined by the T-SN GNB-DU for the cell. The T-SN GNB-DU recognizes which terminal the random access is for by looking at the C-RNTI. When the random access with the UE is completed, the T-SN GNB-DU generates an ACC SUC.

In step 627, the T-SN GNB-DU transmits the ACC SUC to the T-SN GNB-CU. The ACC SUC contains the following information.

Terminal identifier on the F1 interface

NR CGI: NR CGI of a cell in which the UE completed random access

In step 629, the S-SN GNB-CU transmits the SN STA TRA. The SN STA TRA includes the PDCP SN and HFN of the bearer to which data forwarding is to be applied. The SN STA TRA is transmitted to the T-SN GNB-CU via the MN. The T-SN GNB-CU refers to the PDCP SN and HFN included in the SN STA TRA to determine a PDCP SN to be applied during data transmission.

In step 631, the S-SN GNB-CU starts data forwarding. The S-SN GNB-CU transmits PDCP SDUs that have not yet been transmitted and PDCP SDUs that have been transmitted but have not been confirmed to be transmitted to the MN through the GTP tunnel, and the MN transmits them to the T-SN GNB-CU. The T-SN GNB-CU processes them as PDCP PDUs and delivers them as T-SN GNB-DUs.

In step 633, the T-SN GNB-DU transmits the PDCP PDU to the UE.

6B is a diagram illustrating operations of a terminal and a base station performing a first procedure according to a first embodiment of the present invention.

In step 641, the S-SN GNB-CU determines to change the SN through the first procedure. The determination may be made based on a measurement result reported by the terminal, a load of the base station, a radio resource management policy, and the like. The S-SN GNB-CU initiates the procedure by sending an SGNB CHA REQ to the MN. SGNB CHA REQ includes the following information.

Target node identifier information: en-gNB ID of the target node

Container containing CG-ConfigInfo: CG-ConfigInfo includes setting information applied to the terminal by the S-SN.

First information related to the first procedure: This may be a list of identifiers of TCSPCELLs related to the first procedure. The S-SN GNB-CU selects k TCSPCELLs based on the measurement results of the UE.

Second information related to the first procedure: Information representing the nature of the first procedure, indicating whether the first procedure for the TCSPCELLs is a start of a new procedure or a replacement of an existing procedure.

In step 643, the MN generates an SGNB ADD REQ based on the information of the SGNB CHA REQ message and transmits it to the T-SN GNB-CU indicated in the target node identifier information. The SGNB ADD REQ includes the following information.

MeNB Cell ID: PCell's ECGI. Upon receiving this information, the T-SN considers cells around the MeNB Cell as SpCells.

Container containing CG-ConfigInfo

*First information related to the first procedure

Second Information Related to Procedure 1

Information related to data radio bearer setup: Information about the radio bearer to be setup. Can be used for T-SN's call admission control.

Information about the maximum transmission rate: the expected maximum data rate for the call. Can be used for T-SN's call admission control.

Unlike the second procedure, the first procedure does not use SGNB Addition Trigger Indication information. This is because information related to the first procedure can inform that the corresponding procedure is related to the SN change. Upon receiving the SGNB ADD REQ, the T-SN GNB-CU determines which TCSPCELL to accept and which bearer of the UE to accept for each accepted TCSPCELL. Then, PDCP configuration information is determined for each accepted bearer. The T-SN GNB-CU generates CG-Config containing the determined information for each accepted TCSPCELL.

In step 645, the T-SN GNB-CU transmits m CON SET REQs to the T-SN GNB-DU. One CON SET REQ corresponds to one TCSPCELL and includes the following information.

SpCell ID: Identifier of accepted TCSPCELL

CG-Config: PDCP setting information determined for the TCSPCELL, etc.

Second Information Related to Procedure 1

Upon receiving the CON SET REQ for any TCSPCELL, the T-SN GNB-DU determines whether to accept it. And, if accepted, it decides which bearer to accept. Determines RLC configuration information, MAC configuration information, etc. of the accepted bearer. Then, PHY configuration information to be applied to the terminal is determined.

In step 647, the T-SN GNB-DU transmits n CON SET RES to the T-SN GNB-CU. One CON SET RES corresponds to one accepted TCSPCELL. Since the T-SN GNB-CU selects m TCSPCELLs out of k TCSPCELLs and the T-SN GNB-DU selects n TCSPCELLs out of m TCSPCELLs, the relationship k >= m >= n holds. Each CON SET RES includes the following information.

CellGroupConfig: Includes various setting information determined for the corresponding TCSPCELL

C-RNTI: C-RNTI to be used by the terminal

Requested Target Cell ID: NR CGI of the corresponding TCSPCELL.

Upon receiving n CON SET RES, the T-SN GNB-CU generates an SGNB ADD ACK. The structure of the SGNB ADD ACK is detailed in FIG. 7-3.

In step 649, the T-SN GNB-CU transmits an SGNB ADD ACK to the MN. MN generates LTE RECNF including NR RECNF received through SGNB ADD ACK. LTE RECNF includes the first Transaction id. The structure of LTE RECNF is detailed in FIG. 7A.

In step 651, the MN transmits LTE RECNF to the terminal. Upon receiving the LTE RECNF, the terminal processes the NR RECNF information included therein to recognize the configuration of TCSPCELLs and the execution conditions corresponding to each TCSPCELL.

In step 653, the UE transmits an LTE RECNF CMP to the MN. LTE RECNF CMP includes the first Transaction id. The terminal that has transmitted the LTE RECNF CMP performs a conditional reconfiguration evaluation procedure to determine whether the conditional reconfiguration condition is satisfied. The UE determines whether the measurement result of the cell (TCSPCELL) corresponding to the cell identifier indicated in the third NR reconfiguration message satisfies the execution condition, and if so, the second NR reconfiguration message corresponding to the cell that satisfies the execution condition is applied. to perform conditional reconstruction.

In step 655, the UE performs a random access process in a specific cell of the T-SN GNB-DU, that is, a cell designated as SpCell in the third NR RECNF for which the execution condition is satisfied. Random access consists of the UE transmitting a preamble in the GNB-DU, the GNB-DU transmitting a random access response to the UE, and the UE transmitting the PUSCH in the GNB-DU. Through the PUSCH, the UE transmits the C-RNTI MAC CE. The C-RNTI MAC CE contains the C-RNTI determined by the T-SN GNB-DU for the cell. The T-SN GNB-DU recognizes which terminal the random access is for by looking at the C-RNTI. When the random access with the UE is completed, the T-SN GNB-DU generates an ACC SUC.

In step 657, the T-SN GNB-DU transmits the ACC SUC to the T-SN GNB-CU. The ACC SUC contains the following information.

Terminal identifier on the F1 interface

NR CGI: NR CGI of a cell in which the UE completed random access

In step 659, the UE transmits the ULIT to the MN. ULIT includes NR RECNF CMP and CRID. The MN identifies the CG-Config corresponding to the CRID and reconfigures the MN's settings according to the CG-Config.

In step 661, the MN transmits the SGNB REC CMP to the T-SN GNB-CU. SGNB REC CMP includes NR RECNF CMP. The NR RECNF CMP includes the Transaction id of the third NR RECNF for which the execution condition is satisfied. The T-SN GNB-CU recognizes that the UE has performed conditional reconfiguration.

In step 663, the MN transmits the SGNB CHA CNF to the S-SN GNB-CU. Upon receiving the SGNB CHA CNF, the S-SN GNB-CU may initiate an SN status transmission procedure and data forwarding.

In step 665, the S-SN GNB-CU transmits the SN STA TRA. The SN STA TRA includes the PDCP SN and HFN of the bearer to which data forwarding is to be applied. The SN STA TRA is transmitted to the T-SN GNB-CU via the MN.

In step 667, the S-SN GNB-CU starts data forwarding. The S-SN GNB-CU transmits PDCP SDUs that have not yet been transmitted and PDCP SDUs that have been transmitted but have not been confirmed to be transmitted to the MN through the GTP tunnel, and the MN transmits them to the T-SN GNB-CU. The T-SN GNB-CU processes them as PDCP PDUs and delivers them as T-SN GNB-DUs.

In step 669, the T-SN GNB-DU transmits the PDCP PDU to the UE.

The structure of LTE RECNF for setting the first procedure to the UE in EN-DC operation is shown in FIG. 7A.

The LTE RECNF includes a 1st Transaction id generated by the MN and a 1NR RECNF 702 generated by the T-SN. The first RECNF may include various information depending on the purpose of the related procedure. If it is for the first procedure (conditional reconstruction), the first NR RECNF includes conditional reconstruction related information 710 . Conditional reconfiguration related information includes at least one CondReconfigToAddMod IE (703 to 720 to 721).

Each CondReconfigToAddMod IE includes a configuration identifier 704, an execution condition 705, a 2nd NR RECNF including various setting information 706, and an execution condition cell group IE 722.

The second NR RECNF includes radio bearer configuration information 708, a counter for calculating a security key 709, and a third NR RECNF 707. The third NR RECNF includes a secondaryCellGroup IE, and the IE includes TCSPCELL configuration information.

As a result, one 1st NR reconstruction message for 1st reconstruction includes a plurality of 2nd NR RECNFs, and one 2nd NR RECNF corresponds to one TCSPCELL. One second NR RECNF corresponds to one configuration identifier, one execution condition, and one execution condition cell group.

The first NR RECNF includes a second Transaction ID, the second NR RECNF includes a third Transaction ID, and the third NR RECNF includes a fourth Transaction ID.

The structure of LTE RECNF for setting the second procedure to the UE in EN-DC operation is shown in FIG. 7B.

The LTE RECNF includes the first Transaction id generated by the MN and the 1NR RECNF 702 generated by the T-SN GNB-CU. The first RECNF may include various information depending on the purpose of the related procedure. For the second procedure, the first NR RECNF includes radio bearer configuration information 728, a counter for calculating a security key 729, and a fourth NR RECNF 727. The fourth NR RECNF includes a secondaryCellGroup IE, and the IE includes SpCell/PSCell configuration information.

As a result, one 1st NR reconstruction message for the second reconstruction includes one 4th NR RECNF.

The 1st NR RECNF includes the 2nd Transaction ID and the 4th NR RECNF includes the 5th Transaction ID, both generated by the T-SN GNB-CU.

The structure of the SGNB ADD ACK for the first procedure of the UE in EN-DC operation is shown in FIG. 7c.

The SGNB ADD ACK 731 includes at least a first container 732 and a second container 733.

The first container stores a number of CG-Configs. CG-config (hereafter, 1st CG-config, 734) stored in the first container includes Assistance Info for MN 735 and CondReconfigurationId (736, hereinafter, CRID). Assistance info for MN includes information that the MN needs to know in order to determine or adjust its configuration, for example, DRX configuration in the SN, band combination information selected in the SN, and the like.

The second container contains one NR RECNF 739. The NR RECNF 739 is the first NR RECNF 702 contained in the LTE RECNF. The first NR RECNF may include a plurality of CondReconfigToAddMod IEs, and one CondReconfigToAddMod may include one second NR RECNF 737 and one CRID 738.

The CG-Config 735 of the first container and the second NR RECNF 737 of the second container correspond one-to-one and are connected by CRIDs 736 and 738. The number of CG-Configs included in the first container is equal to the number of second NR RECNFs included in the first NR RECNF.

The structure of the SGNB ADD ACK for the second procedure of the UE in EN-DC operation is shown in FIG. 7d.

The SGNB ADD ACK 741 includes one container 742, hereinafter a third container, and the third container includes one CG-Config 743. CG-Config (hereinafter referred to as second CG-Config) stored in the third container includes Assistance info for MN 744 and NR RECNF 745, which are information necessary for the MN to adjust its own settings. NR RECNF 745 is NR RECNF 722. Assistance info for MN includes information that the MN needs to know in order to determine or adjust its configuration, for example, DRX configuration in the SN, band combination information selected in the SN, and the like.

The first CG-Config does not include NR RECNF, but instead includes CRID. The CRID corresponds to one of a plurality of NR RECNFs included in the second container.

8 is a flowchart for explaining T-SN GNB-CU operation according to the first embodiment.

In step 801, the T-SN GNB-CU receives a control message requesting preparation of resources for EN-DC operation from the MN.

In step 811, the T-SN GNB-CU determines whether information related to the first procedure is included in the control message. If included, proceed to step 816, otherwise proceed to step 841.

* In step 816, the T-SN GNB-CU selects m TCSPCELLs among the k TCSPCELLs included in the first information related to the first procedure and generates a CON SET REQ for each TCSPCELL. m number of CON SET REQs are transmitted to the T-SN GNB-DU. One CON SET REQ corresponds to one TCSPCELL. Proceeding to step 816 means that the control message received in step 801 includes one cell group setting information, one execution condition information, and a plurality of cell identifiers.

In step 821, the T-SN GNB-CU receives n CON SET RES from the T-SN GNB-CU. One CON SET RES corresponds to one accepted TCSPCELL. CON SET RES includes information such as CellGroupConfig.

In step 826, the T-SN GNB-CU generates an SGNB ADD ACK message including the first container and the second container and transmits it to the MN. The first container is composed of a plurality of first CG-Configs, and the first CG-config does not include NR RECNF but includes Assistance Info for MN and CRID. The second container includes the first NR RECNFs and includes the same number of second NR RECNFs as the plurality of CRIDs. The T-SN GNB-CU creates the first container and the second container so that the first CG-Config of the first container and the NR RECNF of the second container are connected by CRID.

In step 836, the T-SN GNB-CU receives the SN STA TRA from the MN, recognizes a PDCP SN to be applied to downlink data, and processes the PDCP SDU transferred from the MN as a PDCP PDU.

In step 861, the T-SN GNB-CU transmits the PDCP PDU to the T-SN GNB-DU.

In step 841, the T-SN GNB-CU transmits one CON SET REQ to the T-SN GNB-DU. CON SET REQ contains information such as SpCell ID.

In step 846, the T-SN GNB-CU receives one CON SET RES from the T-SN GNB-CU. CON SET RES includes information such as CellGroupConfig.

In step 826, the T-SN GNB-CU generates an SGNB ADD ACK message including the third container and transmits it to the MN. The third container is composed of one second CG-Config, and the second CG-config includes NR RECNF and Assistance Info for MN and does not include a CRID.

In step 856, the T-SN GNB-CU receives the SN STA TRA from the MN, recognizes a PDCP SN to be applied to downlink data, and processes the PDCP SDU transferred from the MN as a PDCP PDU.

In step 861, the T-SN GNB-CU transmits the PDCP PDU to the T-SN GNB-DU.

9 is a flowchart illustrating an operation of a terminal performing a first procedure according to a first embodiment.

In step 901, the UE reports the capabilities of the UE related to the EN-DC and the first reconfiguration procedure to the first base station (MN or MeNB).

First performance information: band combination information in which EN-DC is supported (a list of band combinations supporting EN-DC); and

Second performance information: a list of EN-DC band combinations supporting 1 ^st reconfiguration among band combinations supported by EN-DC; and

Third performance information: NR band combination composed of two NR bands

The second capability information indicates which NR band of a band combination among the band combinations reported as the first capability information supports the first reconstruction. The second capability information is information indicating whether intra-band first reconfiguration is supported.

The third capability information is a combination of NR bands composed of two NR bands, and indicates that inter-band first reconfiguration is supported in the NR band combination included in the third capability information. For example, if a (N1, N2) band combination is included in the third capability information, it means that the first reconstruction between N1 and N2 is supported. In this case, all NR bands (for example, N1 and N2) belonging to the band combination included in the third capability information are NR bands supported by EN-DC.

In step 906, the terminal receives LTE RECNF. The LTE RECNF includes a first NR RECNF. If the LTE RECNF is a message indicating first reconfiguration, the first NR RECNF includes first information. The first information includes at least one or more pieces of second information, and the second information always includes third information and fourth information and optionally includes fifth information.

One piece of second information corresponds to one TCSPCELL. The third information consists of one or two MeasIds, and defines an execution condition for resetting the TCSPCELL. The fourth information is the second NR RECNF, and includes third NR RECNF including radio bearer configuration information, security key related information, and TCSPCELL configuration information. Fifth information is information indicating which of MCG and SCG (or MeNB and SgNB, or MN and S-SN) the execution condition is associated with.

The third information and the fifth information define execution conditions of the first reconstruction for each TCSPCELL (or for each second information). Alternatively, it is also possible to define third information and fifth information commonly applied to all TCSPCELLs (or second information) included in one first NR message. It is also possible to define an operation of the terminal to include common third information and common fifth information as lower IEs of the first information and ignore individual third information included as lower IEs of the second information. In this case, if common third information exists, the terminal applies the common third information to all TCSPCELLs included in one piece of first information, and if common third information does not exist, applies third information indicated for each TCSPCELL. do.

One LTE RECNF includes one 1st NR RECNF, one 1st NR RECNF includes multiple 2nd NR RECNFs, and one 2nd NR RECNF includes one 3rd NR RECNF. That is, one LTE RECNF may include a plurality of third NR RECNFs, the same number of third information and the same number of fourth information, and may include another plurality of fifth information.

One RECNF includes one Transaction ID. The LTE RECNF includes a first Transaction id, and the first NR RECNF includes a second Transaction id. The second NR RECNF and the third NR RECNF include a third Transaction id and a fourth Transaction id, respectively.

In step 911, the terminal transmits the LTE RECNF CMP to the first base station. The LTE RECNF CMP includes a first Transaction id.

In step 916, the UE initiates a first reconfiguration procedure because the first reconfiguration information is included in the first NR RECNF included in the received LTE RECNF.

In step 921, the terminal determines which cell group (or which node) the MeasId indicated in the third information is associated with based on the third and fifth information set for each TCSPCELL. If there is no fifth information, it is determined that the execution condition for the corresponding TCSPCELL is set by the S-SN, and MeasId is related to the Source SCG (or S-SN). And the meaning of MeasId is interpreted according to MeasConfig of Source SCG (or S-SN). If there is fifth information, it is determined that the execution condition for the corresponding TCSPCELL is set by the MN, and MeasId is related to the MCG (or MN). And the meaning of MeasId is interpreted according to MeasConfig of MCG (or MN). Alternatively, if there is 5th information, the execution condition for the corresponding TCSPCELL is set by the CG (or node) indicated by the 5th information among MCG and SCG (or between MN and S-SN), and MeasId is the CG (or node ) is judged to be related to And the meaning of MeasId is interpreted according to MeasConfig of the CG (or node).

In LTE, there are two types of MeasId: MeasId having a value between 1 and 32 and MeasId-v1250 having a value between 33 and 64. The former is named 5 bit MeasId, and the latter is named 5 bit MeasId-Ext. NR has MeasId having a value between 1 and 64, and is named as 6 bit MeasId in the present invention.

In the SGNB ADD REQ, the MN may inform the T-SN of MeasId to be used as an execution condition determined by the MN. MN changes 5 bit MeasId or 5 bit MeasId-Ext to 6 bit MeasId, includes it in SGNB ADD REQ, and informs T-SN. If the MN selects 5-bit MeasId as an execution condition, it sets the MSB of 6-bit MeasId to 0 and sets the remaining 5 bits to 5-bit MeasId. If the MN selects 5 bit MeasId-Ext as an execution condition, it sets the MSB of 6 bit MeasId to 1 and sets the remaining 5 bits to 5 bit MeasId.

The UE receives 6 bit MeasId as an execution condition through RECNF. If the execution condition is determined by the S-SN, that is, if the execution condition cell group IE is SCG, the terminal determines the execution condition as it is without converting the received 6-bit MeasId. If the execution condition is determined by the MN, that is, if the execution condition cell group IE is MCG, the UE determines the execution condition by converting the received 6-bit MeasId into 5-bit MeasId or 5-bit MeasId-Ext. If the MSB of 6-bit MeasId is 0, the remaining 5 bits are interpreted as 5-bit MeasId and related ReportConfig and MeasObject are selected. If the MSB of 6-bit MeasId is 1, the remaining 5 bits are interpreted as 5-bit MeasId-Ext and the related ReportConfig and MeasObject are selected.

In step 926, the terminal performs a conditional reset evaluation operation. For each second information included in the first information, the terminal considers the serving cell (ie, target candidate cell) indicated in the third NR RECNF of each second information as an 'applicable cell', and the applicable cell Among them, it is determined whether there is a cell that satisfies an event related to an execution condition. In addition, a target candidate cell that satisfies the event is regarded as a triggered cell.

In step 931, the terminal performs conditional reset. The UE applies the corresponding second NR RECNF to the triggered cell.

In step 936, the terminal transmits the ULIT to the second base station. The ULIT includes the first NR RECNF CMP. The first NR RECNF CMP includes a third Transaction id. The ULIT also includes a CRID corresponding to the triggered cell (or corresponding to the second NR RECNF corresponding to the triggered cell).

10 is a block diagram showing the internal structure of a terminal to which the present invention is applied.

Referring to the drawing, the terminal includes a control unit 1001, a storage unit 1002, a transceiver 1003, a main processor 1004, and an input/output unit 1005.

The controller 1001 controls overall operations of the UE related to mobile communication. For example, the controller 1001 transmits and receives signals through the transceiver 1003 . Also, the control unit 1001 writes and reads data in the storage unit 1002 . To this end, the controller 1001 may include at least one processor. For example, the control unit 1001 may include a communication processor (CP) that controls communication and an application processor (AP) that controls upper layers such as application programs. The control unit 1001 controls the storage unit and the transceiver so that the operation of the terminal of FIG. 9 is performed.

The storage unit 1002 stores data such as a basic program for operating the terminal, an application program, and setting information. The storage unit 1002 provides stored data according to the request of the control unit 1001 .

The transver 1003 includes an RF processing unit, a baseband processing unit, and an antenna. The RF processing unit performs functions for transmitting and receiving signals through a wireless channel, such as band conversion and amplification of signals. That is, the RF processing unit up-converts the baseband signal provided from the baseband processing unit into an RF band signal, transmits the signal through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. The RF processing unit may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog to digital converter (ADC), and the like. The RF processing unit may perform MIMO, and may receive multiple layers when performing MIMO operation. The baseband processing unit performs a conversion function between a baseband signal and a bit string according to the physical layer standard of the system. For example, during data transmission, the baseband processing unit generates complex symbols by encoding and modulating a transmission bit stream. In addition, when data is received, the baseband processing unit demodulates and decodes the baseband signal provided from the RF processing unit to restore a received bit stream. The transceiver is a transceiver.

The main processor 1004 controls overall operations except for operations related to mobile communication. The main processor 1004 processes user input transmitted by the input/output unit 1005, stores necessary data in the storage unit 1002, controls the control unit 1001 to perform mobile communication-related operations, and the input/output unit ( 1005) to transmit the output information.

The input/output unit 1005 is composed of a device that receives user input, such as a microphone and a screen, and a device that provides information to the user, and performs input and output of user data under the control of a main processor.

11 is a block diagram showing the configuration of a GNB-CU according to the present invention.

* As shown in the figure, the base station includes a control unit 1101, a storage unit 1102, an F1 interface unit 1103, and a backhaul interface unit 1104.

The controller 1101 controls overall operations of the base station. For example, the control unit 1101 transmits and receives signals through the transceiver 1103 or the backhaul interface unit 1104 . Also, the control unit 1101 writes and reads data in the storage unit 1102 . To this end, the controller 1101 may include at least one processor. The controller 1101 is an F1 interface unit so that the base station operations shown in FIGS. 6 and 8 are performed. storage. Controls the backhaul interface.

The storage unit 1102 stores data such as a basic program for the operation of the main base station, an application program, and setting information. In particular, the storage unit 1102 may store information about a bearer allocated to a connected terminal, measurement results reported from the connected terminal, and the like. In addition, the storage unit 1102 may store information that is a criterion for determining whether to provide or stop multiple connections to the terminal. And, the storage unit 1102 provides the stored data according to the request of the control unit 1101.

The interface unit 1103 provides an interface for communicating with the GNB-DU. That is, the F1 interface unit converts a bit stream transmitted through the GNB-DU into a physical signal and converts a physical signal received from the GNB-DU into a bit stream.

The backhaul interface unit 1104 provides an interface for communicating with other nodes in the network. That is, the backhaul communication unit 1104 converts a bit string transmitted from the main base station to another node, for example, a secondary base station, a core network, etc., into a physical signal, and converts the physical signal received from the other node into a bit string. convert

The interface unit and the backhaul interface unit constitute a transmission/reception unit.

Claims (6)

1. In a wireless communication system, in a method of a target secondary base station central unit,

   A first control message requesting preparation of resources for E-UTRA-NR Dual Connectivity (EN-DC) operation from the master base station, including one cell group configuration information, one execution condition information, and a plurality of cell identifiers receiving;

   Transmitting a plurality of second control messages related to context establishment to a target base station distribution unit;

   Receiving a plurality of third control messages related to context setup from a target base station distribution unit;

   Transmitting to the master base station a fourth control message including one first container, which determines preparation for secondary GNB (SGNB) addition,

   A method characterized in that the first container includes a plurality of cell group configurations
2. According to claim 1,

   The fourth control message includes a second container, and the second container includes one NR Radio Resource Control (RRC) reconfiguration message.
3. According to claim 1,

   The number of cell identifiers included in the first control message is greater than or equal to the number of second control messages and the number of second control messages is greater than or equal to the number of third control messages.
4. In a wireless communication system, in a target base station central unit,

   A transmitting and receiving unit configured to transmit and receive signals; and

   It includes a control unit,

   The control unit,

   Receiving a first control message including one cell group configuration information, one execution condition information, and a plurality of cell identifiers requesting preparation of resources for an EN-DC operation from a master base station;

   Transmitting a plurality of second control messages related to context setup to a target base station distribution unit;

   Receiving a plurality of third control messages related to context setup from a target base station distribution unit;

   Transmitting a fourth control message including one first container to confirm SGNB addition preparation to the master base station;

   The first container is a device configured to include a plurality of cell group configurations.
5. According to claim 4,

   The fourth control message includes a second container, and the second container is configured to include one NR RRC reconfiguration message.
6. According to claim 4,

   The number of cell identifiers included in the first control message is greater than or equal to the number of second control messages, and the number of second control messages is greater than or equal to the number of third control messages.

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