CN116686386A

CN116686386A - Method and apparatus for reporting mobility history information in wireless communication system

Info

Publication number: CN116686386A
Application number: CN202180087442.2A
Authority: CN
Inventors: 郑湘烨; 希姆克·范德维尔德
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2020-12-22
Filing date: 2021-12-21
Publication date: 2023-09-01

Abstract

The present disclosure relates to a 5G or quasi-5G communication system supporting a higher data transmission rate than a 4G system such as LTE. A method for a user equipment to perform event-based recording in a wireless communication system according to an embodiment of the present disclosure includes the steps of: the user equipment is in an RRC IDLE state (RRC IDLE) or an RRC INACTIVE state (RRC INACTIVE) and confirms that a suitable cell or acceptable cell cannot be found; when the suitable cell or the acceptable cell cannot be found, the user equipment confirms that the RPLMN is included in the PLMN ID list; the user equipment records a service cell ID, wherein the service cell ID indicates the global cell ID of the proper cell where the user equipment recently resides; and the user equipment records the measurement result of the proper cell where the user equipment recently resides.

Description

Method and apparatus for reporting mobility history information in wireless communication system

Technical Field

The present disclosure relates to a technology for a UE to report cell information to a base station in a mobile communication system.

Background

In order to meet the increasing demand for wireless data services since 4G communication systems have been marketed, efforts have been made to develop enhanced 5G communication systems or quasi 5G communication systems. For these reasons, the 5G communication system or the quasi 5G communication system is called a super 4G network communication system or a post LTE system.

For higher data transmission rates, 5G communication systems are considered to be implemented on ultra-high frequency bands (mmWave) such as, for example, 60 GHz. In order to mitigate path loss over the uhf band and increase the reach of radio waves, the following techniques are considered for 5G communication systems: beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antennas.

Also being developed are various technologies for 5G communication systems with enhanced networks, such as evolved or advanced small cells, cloud radio access networks (cloud RANs), ultra dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, cooperative communications, coordinated multipoint (CoMP), and interference cancellation.

There are also various other schemes in development for 5G systems, including, for example, hybrid FSK and QAM modulation (FQAM) and Sliding Window Superposition Coding (SWSC) as Advanced Code Modulation (ACM) schemes, and Filter Bank Multicarrier (FBMC), non-orthogonal multiple access (NOMA) and Sparse Code Multiple Access (SCMA) as advanced access schemes.

On the other hand, since the UE cannot know whether the current primary cell (PCell) can process (or support) mobility history information recorded for the secondary cell, a need has arisen for a method for transmitting and receiving mobility history information between the UE and the base station.

Disclosure of Invention

Technical problem

The present disclosure proposes a method for a UE to report mobility history information about a recorded cell to a base station when adding or changing a primary and secondary cell (PSCell).

Technical proposal

A method of event-based recording by a UE in a wireless communication system according to an embodiment of the present disclosure includes: identifying that the UE is in a Radio Resource Control (RRC) IDLE state (rrc_idle) or an RRC INACTIVE state (rrc_inactive) and fails to find a suitable cell and an acceptable cell; identifying that a Registered Public Land Mobile Network (RPLMN) is included in a PLMN ID list when the UE fails to find the suitable cell and the acceptable cell; recording a serving cell ID indicating a global cell ID of a suitable cell in which the UE recently resides; and recording the measurement results of the suitable cell in which the UE has recently resided.

A method of reporting mobility history information by a UE in a wireless communication system according to an embodiment of the present disclosure includes: receiving system information including first information from a primary cell (PCell), the first information indicating that mobility history information about a Secondary Cell Group (SCG) is supported; transmitting a UE capability information message (UE capability information) including second information to the PCell, the second information indicating that mobility history information about SCG can be stored; and transmitting a UE information response message (ueinfo response) including mobility history information about the SCG to the PCell.

The method of reporting mobility history information by the UE may further include: a Radio Resource Control (RRC) connection setup complete message including third information indicating that the UE has mobility history information about SCG is transmitted to the PCell.

The method of reporting mobility history information by the UE may further include: a UE information request message (UEInformationRequest) including information for requesting mobility history information about SCG is received from the PCell.

A method of receiving mobility history information by a base station of a primary cell (PCell) in a wireless communication system according to an embodiment of the present disclosure includes: transmitting system information including first information indicating that mobility history information about a Secondary Cell Group (SCG) is supported to a UE; receiving a UE capability information message (UE capability information) including second information from the UE, the second information indicating that mobility history information about SCG can be stored; and receiving a UE information response message (ueinfo response) including mobility history information about the SCG from the UE.

The method of receiving mobility history information by the base station of the PCell may include: a Radio Resource Control (RRC) connection setup complete message is received from the UE that includes third information indicating that the UE has mobility history information about SCG.

The method of receiving mobility history information by the base station of the PCell may further include: a UE information request message (UEInformationRequest) including information for requesting mobility history information about SCG is transmitted to the UE.

A UE performing event-based logging in a wireless communication system according to an embodiment of the present disclosure includes a transceiver and a processor. The processor may: identifying that the UE is in a Radio Resource Control (RRC) IDLE state (rrc_idle) or an RRC INACTIVE state (rrc_inactive) and fails to find a suitable cell and an acceptable cell; identifying that a Registered Public Land Mobile Network (RPLMN) is included in a PLMN ID list when the UE fails to find the suitable cell and the acceptable cell; recording a serving cell ID indicating a global cell ID of a suitable cell in which the UE recently resides; and recording the measurement results of the suitable cell in which the UE has recently resided.

A UE reporting mobility history information in a wireless communication system according to an embodiment of the present disclosure includes: a transceiver; and a controller connected with the transceiver to control the transceiver. The controller may: control to receive system information including first information indicating that mobility history information about a Secondary Cell Group (SCG) is supported from a primary cell (PCell); control to transmit a UE capability information message (UE capability information) including second information to the PCell, the second information indicating that mobility history information about SCG can be stored; and controlling to transmit a UE information response message (ueinfo response) including mobility history information on SCG to the PCell.

According to an embodiment, the controller may control to transmit a Radio Resource Control (RRC) connection setup complete message including third information indicating that the UE has mobility history information on SCG to the PCell.

According to an embodiment, the controller may control to receive a UE information request message (ueinfo request) including information for requesting mobility history information about SCG from the PCell.

A base station for receiving mobility history information located in a primary cell (PCell) in a wireless communication system according to an embodiment of the present disclosure includes: a transceiver; and a controller connected with the transceiver to control the transceiver. The controller may: controlling to transmit system information including first information indicating that mobility history information about a Secondary Cell Group (SCG) is supported to a UE; control to receive a UE capability information message (UE capability information) including second information from the UE, the second information indicating that mobility history information about SCG can be stored; and controlling to receive a UE information response message (ueinfo response) including mobility history information about SCG from the UE.

According to an embodiment, the controller may control to receive a Radio Resource Control (RRC) connection setup complete message including third information from the UE, the third information indicating that the UE has mobility history information on SCG.

According to an embodiment, the controller may control to transmit a UE information request message (ueinfo request) including information for requesting mobility history information about SCG to the UE.

Advantageous effects

In the method and apparatus according to the embodiments of the present disclosure, the UE reports mobility history information about cells recorded when a primary and secondary cell (PScell) is added or changed to a base station, so that efficient communication between the UE and the base station is possible.

Methods and apparatus according to embodiments of the present disclosure may independently process legacy Mobility History Information (MHI) and MHI for a secondary cell group, thereby enabling efficient communication between a UE and a base station.

Drawings

Fig. 1 is a view showing the structure of an LTE system according to an embodiment of the present disclosure;

fig. 2 is a view showing the structure of a wireless protocol in an LTE system according to an embodiment of the present disclosure;

fig. 3 is a view showing the structure of a next generation mobile communication system according to an embodiment of the present disclosure;

Fig. 4 is a view showing the structure of a wireless protocol of a next generation mobile communication system according to an embodiment of the present disclosure;

fig. 5 is a diagram illustrating a technique for collecting and reporting cell measurement information according to an embodiment of the present disclosure;

fig. 6 is a flowchart illustrating a procedure in which a UE reports mobility history information to an LTE base station in an LTE system;

fig. 7 is a view showing a UE operation in which a UE stores mobility history information and reports it to a base station in an LTE system;

fig. 8 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an LTE system according to an embodiment of the present disclosure;

fig. 9 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an LTE system according to an embodiment of the present disclosure;

fig. 10 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an LTE system according to an embodiment of the present disclosure;

fig. 11 is a view showing a UE operation in which a UE reports Secondary Cell Group (SCG) mobility history information (hereinafter "SCG MHI") to a base station in an LTE system according to an embodiment of the present disclosure;

Fig. 12 is a flowchart showing a procedure in which a UE reports mobility history information to an NR base station in an NR system;

fig. 13 is a view showing a UE operation in which a UE stores mobility history information and reports it to a base station in an NR system;

fig. 14 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter "SCG MHI") and reports it to a base station in an NR system according to an embodiment of the present disclosure;

fig. 15 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an NR system according to an embodiment of the present disclosure;

fig. 16 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter "SCG MHI") and reports it to a base station in an NR system according to an embodiment of the present disclosure;

fig. 17 is a view showing a UE operation in which a UE reports Secondary Cell Group (SCG) mobility history information (hereinafter "SCG MHI") to a base station in an NR system according to an embodiment of the present disclosure;

fig. 18 is a view showing UE operation in which a UE directly reports Secondary Cell Group (SCG) mobility history information (hereinafter "SCG MHI") to a Secondary Node (SN) in an NR system according to an embodiment of the present disclosure;

Fig. 19 is a block diagram illustrating an internal structure of a UE according to an embodiment of the present disclosure;

fig. 20 is a block diagram showing a configuration of a base station according to an embodiment of the present disclosure;

fig. 21 is a view showing a procedure in which a UE performs measurement logging according to out-of-coverage based on an event set by an NR base station and reports the logged measurement value to the NR base station according to an embodiment of the present disclosure;

fig. 22 is a view showing a procedure in which a UE performs measurement logging according to out-of-coverage based on an event set by an NR base station and reports the logged measurement value to the NR base station according to an embodiment of the present disclosure.

Detailed Description

Hereinafter, the operation principle of the present disclosure is described below with reference to the drawings. Detailed descriptions of known functions or configurations may be skipped when determined to obscure the subject matter of the present disclosure. The terms as used herein are defined in the present disclosure in consideration of functions, and may be replaced with other terms according to the intention or practice of a user or operator. Accordingly, terms should be defined based on the entire disclosure.

Detailed descriptions of known functions or configurations may be skipped in describing embodiments of the present disclosure when determined to unnecessarily obscure the subject matter of the present disclosure. Hereinafter, the present disclosure is described in detail with reference to the accompanying drawings.

As used herein, for ease of description, terms for identifying access nodes, terms for representing network entities, terms for representing messages, terms for representing interfaces between network entities, and terms for representing pieces of identification information are provided as examples. Accordingly, the present disclosure is not limited to these terms, and these terms may be replaced with other terms representing objects having equivalent technical meanings.

For ease of description, some terms and names defined in the third generation partnership project long term evolution (3 GPP LTE) standard may be used in the present disclosure below. However, the present disclosure is not limited by such terms and names and may be equally applicable to systems conforming to other standards. In this disclosure, for ease of description, enbs may be used interchangeably with gNB. In other words, a base station described as an eNB may represent a gNB.

Fig. 1 is a view showing the structure of an LTE system according to an embodiment of the present disclosure.

Referring to fig. 1, a radio access network of an lte system includes next generation base stations (evolved node bs—hereinafter, "ENBs" or "base stations") 1-05, 1-10, 1-15, and 1-20, mobility Management Entities (MMEs) 1-25, and serving gateways (S-GWs) 1-30. User equipments (hereinafter, referred to as "UEs" or "terminals") 1-35 access an external network through ENBs 1-05 to 120 and S-GWs 1-30.

The ENBs 1-05 to 1-20 of FIG. 1 correspond to node Bs in a conventional Universal Mobile Telecommunications System (UMTS) system. The ENB is connected with the UEs 1-35 through a radio channel and plays a more complex role than the conventional node B. Since all user traffic through an internet protocol and real-time services such as voice over internet protocol (VoIP) services are serviced through a shared channel in the LTE system, means for performing scheduling by compiling state information such as a buffer state, an available transmission power state, or a channel state of the UE are required, and the ENBs 1-05 to 1-20 are responsible for performing scheduling. One ENB generally controls a plurality of cells. For example, the LTE system employs orthogonal frequency division multiplexing (hereinafter, "OFDM") over a 20MHz bandwidth as a radio access technology in order to achieve a transmission speed of 100 Mbps. In addition, the system applies Adaptive Modulation and Coding (AMC) that determines a modulation scheme and a channel coding rate according to the channel state of the UE. The S-GW 1-30 is a device that provides data bearers and the serving gateway 130 generates or removes data bearers under control of the MME 1-25. The MME is a device responsible for various control functions and mobility management functions of the UE and is connected with a plurality of base stations.

Fig. 2 is a view showing the structure of a wireless protocol in an LTE system according to an embodiment of the present disclosure.

Referring to fig. 2, the lte system radio protocol includes Packet Data Convergence Protocol (PDCP) 2-05 and 2-40, radio Link Control (RLC) 2-10 and 2-35, and Medium Access Control (MAC) 2-15 and 2-30 for the UE and the base station, respectively. Packet Data Convergence Protocol (PDCP) 2-05 and 2-40 are responsible for IP header compression/reconstruction. The main functions of PDCP can be summarized as follows.

Header compression and decompression (ROHC only)

-transfer of user data

Sequential delivery of upper layer PDUs in PDCP re-establishment procedure for RLC AM

For split bearers in DC (only RLC AM is supported), PDCP PDU routing for transmission and PDCP PDU reordering for reception

-duplicate detection of lower layer SDUs in PDCP re-establishment procedure for RLC AM

Retransmission of PDCP SDUs at handover, and PDCP PDUs at PDCP data recovery procedure for RLC AM for split bearers in DC

-encryption and decryption

Timer based SDU discard in uplink

RLC 2-10 and 2-35 reconfigure Packet Data Units (PDUs) to the appropriate size and perform ARQ operations. The main functions of RLC can be summarized as follows.

Transmission of upper layer PDUs

Error correction by ARQ (for AM data transfer only)

Concatenation, segmentation and reassembly of RLC SDUs (for UM data transfer and AM data transfer only)

Re-segmentation of RLC data PDU (for AM data transfer only)

Reordering of RLC data PDUs (for UM data transfer and AM data transfer only)

Repetition detection (for UM data transfer and AM data transfer only)

Protocol error detection (for AM data transfer only)

RLC SDU discard (for UM data transfer and AM data transfer only)

RLC re-establishment

The MACs 2-15 and 2-30 are connected with several RLC layer apparatuses configured in one UE, multiplex RLC PDUs into MAC PDUs, and demultiplex MAC PDUs into RLC PDUs. The main functions of the MAC can be summarized as follows.

Mapping between logical channels and transport channels

Multiplexing/de-multiplexing MAC SDUs belonging to one or different logical channels into/from Transport Blocks (TBs) delivered to the physical layer on transport channels

Scheduling information reporting

Error correction by HARQ

Priority handling between logical channels of a UE

Priority handling between UEs by means of dynamic scheduling

MBMS service identification

Transport format selection

-filling

The physical layers 2-20 and 2-25 channel-code and modulate higher layer data into OFDM symbols, transmit the OFDM symbols over a wireless channel or demodulate OFDM symbols received over a wireless channel, channel-decode them and transmit them to higher layers.

Fig. 3 is a view showing the structure of a next generation mobile communication system according to an embodiment of the present disclosure.

Referring to fig. 3, as shown, a radio access network of a next generation mobile communication system (hereinafter, NR or 2 g) includes next generation base stations (new radio node bs, hereinafter, NR gnbs or NR base stations) 3-10 and new radio core networks (NR CN) 3-05. The new wireless user equipment (hereinafter NR UE or terminal) 3-15 accesses the external network through NR gNB 3-10 and NR CN 3-05.

In fig. 3, NR gNB 3-10 corresponds to an evolved node B (eNB) of a legacy LTE system. The NR gNB is connected with NR UEs 3-15 via a radio channel and can provide a service superior to that of the conventional node B. Since all user traffic is served through a shared channel in the next generation mobile communication system, a means for performing scheduling by compiling state information such as a buffer state, an available transmission power state, or a channel state of the UE is required, and the NR NB 3-10 is responsible for performing scheduling. One NR gNB typically controls multiple cells. In order to achieve ultra-high data rate transmission compared to current LTE, a bandwidth higher than the existing maximum bandwidth may be provided, and orthogonal frequency division multiplexing (hereinafter OFDM) may be used as a radio access technology, and a beamforming technology may be additionally combined. In addition, the system applies Adaptive Modulation and Coding (AMC) that determines a modulation scheme and a channel coding rate according to the channel state of the UE. The NR CN 3-05 performs functions such as mobility support, bearer setup, and QoS setup. The NR CN is a device responsible for various control functions and mobility management functions of the UE and connected to a plurality of base stations. In addition, the next generation mobile communication system may be linked with the legacy LTE system. The NR CN is connected to MME 3-25 by a network interface. The MME is connected to eNBs 3-30, which are legacy base stations.

Fig. 4 is a view showing the structure of a wireless protocol of a next generation mobile communication system according to an embodiment of the present disclosure.

Fig. 4 is a view showing the structure of a radio protocol of a next-generation mobile communication system to which the present disclosure is applicable.

Referring to fig. 4, radio protocols of the next generation mobile communication system include NR SDAPs 4-01 and 4-45, NR PDCP 4-05 and 4-40, NR RLC 4-10 and 4-35, and NR MACs 4-15 and 4-30 in the UE and the NR base station, respectively.

The primary functions of NR SDAPs 4-01 and 4-45 may include some of the following functions.

-transmission of user plane data

Mapping between QoS flows and DRB for both DL and UL

Marking QoS flow IDs in both DL and UL packets

-reflected QoS flow to DRB mapping of UL SDAP PDU.

For the SDAP layer device, the UE may be set via an RRC message for whether to use a function of the SDAP layer per PDCP layer device, per bearer, or per logical channel or a header of the SDAP layer device. If the SDAP header has been set, the UE may be instructed to update or reset the mapping information of the uplink and downlink data bearers and QoS flows by a one-bit NAS reflective QoS indicator and a one-bit AS reflective QoS indicator. The SDAP header can include QoS flow ID information indicating QoS. QoS information may be used as data priority handling or scheduling information for seamlessly supporting services.

The main functions of NR PDCP 4-05 and 4-40 can include some of the following functions.

Header compression and decompression (ROHC only)

-transfer of user data

Sequential delivery of upper layer PDUs

Out-of-order delivery of upper layer PDUs

Reordering of PDCP PDUs for reception

Duplicate detection of lower layer SDUs

Retransmission of PDCP SDUs

-encryption and decryption

Timer based SDU discard in uplink

Reordering by NR PDCP refers to reordering PDCP PDUs received by a lower layer based on PDCP Sequence Numbers (SNs), and may include transmitting data to an upper layer in the reordered order or immediately transmitting data to the upper layer regardless of the order, recording PDCP PDUs lost due to reordering, reporting the status of the lost PDCP PDUs to a transmitting part, and requesting retransmission of the lost PDCP PDUs.

The primary functions of NR RLCs 4-10 and 4-35 may include some of the following functions.

Transmission of upper layer PDUs

Sequential delivery of upper layer PDUs

Out-of-order delivery of upper layer PDUs

Error correction by ARQ

Concatenation, segmentation and reassembly of RLC SDUs

Re-segmentation of RLC data PDUs

Reordering of RLC data PDUs

-repeated detection

Protocol error detection

RLC SDU discard

RLC re-establishment

Sequential delivery by the NR RLC apparatus refers to sequentially transferring RLC SDUs received from a lower layer to a higher layer, and if one original RLC SDU is split into several RLC SDUs that are then received, sequential delivery may include reassembling and transferring them, reordering received RLC PDUs based on RLC SNs or PDCP SNs, recording RLC PDUs lost due to reordering, reporting a status of the lost RLC PDUs to a transmitting part, and requesting retransmission of the lost RLC PDUs, whereas if there is a lost RLC SDU, sequential delivery may include sequentially transferring RLC SDUs before the lost RLC SDU to a higher layer only. Although there is a missing RLC SDU, if the predetermined timer has expired, sequential delivery may include sequentially delivering all RLC SDUs received before the timer starts to higher layers. Alternatively, sequential delivery may include sequentially delivering all RLC SDUs received thus far to higher layers if a predetermined timer has expired, despite the presence of missing RLC SDUs. Furthermore, RLC PDUs can be processed in the order of reception (in order of arrival regardless of sequence number order) and delivered to the PDCP device regardless of order (out-of-order delivery). For segmentation, segments stored in a buffer or to be received later may be received and reconstructed into a single complete RLC PDU, which is then processed and delivered to the PDCP device. The NR RLC layer may not include a concatenation function, and the function may be performed by the NR MAC layer or may be replaced with a multiplexing function of the NR MAC layer.

Out-of-order delivery by NR RLC means refers to immediately transferring RLC SDUs received from a lower layer to a higher layer regardless of order, and if one original RLC SDU is split into several RLC SDUs that are subsequently received, out-of-order delivery may include reassembling and transferring them and storing RLC SN or PDCP SN of the received RLC PDU, ordering them, and documenting missing RLC PDUs.

The NR MACs 4-15 and 4-30 may be connected to several NR RLC layer apparatuses configured in one UE, and main functions of the NR MACs may include some of the following functions.

Mapping between logical channels and transport channels

Multiplexing/demultiplexing of MAC SDUs

Scheduling information reporting

Error correction by HARQ

Priority handling between logical channels of a UE

Priority handling between UEs by means of dynamic scheduling

MBMS service identification

Transport format selection

-filling

The NR PHY layers 4-20 and 4-25 channel-encode and modulate higher layer data into OFDM symbols, transmit the OFDM symbols through a wireless channel or demodulate OFDM symbols received through a wireless channel, channel-decode them and transmit them to higher layers.

Fig. 5 is a diagram illustrating a technique for collecting and reporting cell measurement information according to an embodiment of the present disclosure.

When a network is established or optimized, mobile communication service providers typically measure signal strength in the intended service area and deploy or readjust base stations in the service area accordingly. The operator loads the signal measurement device on the vehicle and collects cell measurement information in the service area, which requires a lot of time and money.

This process is commonly referred to as drive test (5-30) because it uses a vehicle. The UE is equipped with a function capable of measuring signals to the base station to support operations such as cell reselection, handover (HO) and addition to a serving cell when moving between cells.

Thus, the UEs 5-25 in the service area may be utilized instead of drive test, which is referred to as Minimization of Drive Test (MDT). The operator may configure MDT operation for a specific UE through various component devices 5-05, 5-10, and 5-15 of the network, and the UE collects and stores signal strength information from the serving cell and neighbor cells in an RRC CONNECTED mode (rrc_connected), an RRC IDLE mode (rrc_idle), or an RRC INACTIVE mode (rrc_inactive). In addition, various information such as location information, time information, and signal quality information is also stored. When the UE is in connected mode, the stored information may be reported to the network 5-15 and the information sent to the specific server 5-20.

The MDT operation is largely divided into immediate MDT and record MDT.

The immediate MDT is characterized by reporting the collected information directly to the network. Since immediate reporting is necessary, only RRC connected mode UEs can perform this. In general, RRM measurement procedures for supporting operations such as handover and serving cell addition are reused, and location information, time information, and the like are additionally reported.

The logging MDT stores the collected information without reporting it to the network immediately, and reports the stored information after the UE switches to the RRC connected mode. This is typically performed by the UE in RRC idle mode or RRC inactive mode, which may not be reported directly to the network.

In the present disclosure, a UE in an RRC inactivity mode introduced in a next generation mobile communication system performs logging MDT. The network provides configuration information for performing the logged MDT operation to the UE when a specific UE is in the RRC connected mode, and the UE collects and stores the configuration information after switching to the RRC idle mode or the RRC inactive mode. The RRC states of the UE performing the immediate MDT operation and the logged MDT operation may be shown in table 1 below.

TABLE 1

	RRC state
		Immediate MDT	RRC_CONNECTED
Recording MDT	RRC_IDLE,RRC_INACTIVE

Fig. 6 is a flowchart illustrating a procedure in which a UE reports mobility history information to an LTE base station in an LTE system.

Referring to fig. 6, the ue 6-01 may be in an RRC IDLE mode (rrc_idle) or an RRC INACTIVE mode (rrc_inactive).

The UE 6-01 in RRC idle mode may send (6-10) an RRC connection request message (RRCConnectionRequest) to the base station to perform an RRC connection setup procedure with the base station 6-02. Upon receiving the RRC connection request message, the base station 6-02 may send (6-15) an RRC connection setup message (RRCConnectionSetup) to the UE 6-01 in response thereto. The UE receiving the RRC connection setup message may apply the RRC connection setup message and transition to the RRC connected mode (6-16). The RRC connected mode UE may then send an RRC connection setup complete message (rrcconnectionsetup complete) to the base station (6-20). If the UE supports storage of mobility history information and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobility historyavail indicator in an RRC connection setup complete message and transmit it to the base station (6-20).

The UE 6-01 in the RRC inactive mode may send an RRC connection resume request message (RRCConnectionResumeRequest) 6-10 to the base station to perform an RRC connection resume procedure with the base station 6-02. Upon receiving the RRC connection resume request message, the base station 6-02 may send (6-15) an RRC connection resume message (RRCConnectionResume) to the UE 6-01 in response thereto. The UE receiving the RRC connection resume message may apply the RRC connection resume message and transition to the RRC connected mode (6-16). The RRC connected mode UE may then send (6-20) an RRC connection resume complete message (rrcconnectionresuxemplete) to the base station. If the UE supports storage of mobility history information and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobility historyavail indicator in an RRC connection restoration complete message and transmit it to the base station (6-20).

The UE 6-01 that has not been configured with security may perform an initial security activation procedure with the base station 6-02 (6-21). For example, a UE that is not configured with security may refer to a UE that has switched from RRC idle mode to RRC connected mode. Specifically, the UE 6-01 may transmit a security mode command message (security modecommand) to the base station 6-02, and in response thereto, the base station may transmit a security mode complete message (security modecomplete) to the UE.

To perform the RRC connection reconfiguration procedure in step 6-25, the base station 6-02 may send an RRC connection reconfiguration message (RRCConnectionReconfiguration) to the RRC connected mode UE 6-01. The UE may apply the received RRC connection reconfiguration message and may send (6-30) an RRC connection reconfiguration complete message (rrcconnectionreconfiguration complete) to the base station in response thereto.

In step 6-35, the base station 6-02 may perform a UE information procedure upon successful performance of the security activation. The base station 6-02 may transmit (6-35) a UE information request message (ueinfo request) to the UE to request mobility history information from the UE 6-01. The UE information request message may include a MobilityHistoryReportReq indicator.

In step 6-40, the UE 6-01 that successfully performs security activation may send (6-40) a UE information response (ueinfo response) to the base station 6-02. If the mobilityHistoryReportReq is set to true in the received UE information request message, the UE may perform the following series of procedures.

Information can be included in the VarMobilityHistoryReport, in the mobilityHistoryReport (including mobilityHistoryReport and set to include entries from the VarMobilityHistoryReport

The oldest information can be deleted if necessary and the information about the current cell can be included in the mobilityHistoryReport as follows (including the entries of the current cell in mobilityHistoryReport, possibly after removing the oldest entries as required, the fields of which are set as follows

The global cell identifier of the current cell may be set to visitedCellId (visitedCellId is set to global cell identifier of the current cell)

The time spent in the current cell can be set in the time-stamp field (the field time stamp is set to the time spent in the current cell)

-the UE may perform the procedure described above to include the mobilityHistoryReport in a UE information response message and send it to the base station (6-40).

The UE according to the LTE system has the following characteristics when storing and reporting mobility history information to the LTE base station.

The UE does not send a separate UE capability information message (UE capability information) to the base station to let the UE know if it supports storing mobility history information. In contrast, the UE transmits an RRC connection setup complete message or an RRC connection restoration complete message including the mobility history avail indicator only when storage of mobility history information is supported and the mobility history information exists in the varmobility historyreport.

The UE does not store information about the PSCell it has accessed or camped on in the mobility history information.

The UE stores only the list of cell information for camping on RRC idle mode or RRC inactive mode, the list of cell information for camping on each cell, the list of cell information for camping on RRC connected mode, and the time information for camping on each cell in mobility history information and reports the information to the base station.

Fig. 7 is a view showing a UE operation in which a UE stores mobility history information and reports it to a base station in an LTE system.

A UE supporting storing mobility history information may change the (suitable) serving cell in RRC IDLE mode (rrc_idle) or RRC INACTIVE mode (rrc_inactive), or the PCell in RRC CONNECTED mode (rrc_connected), or may enter out of service (e.g. when it camps on a cell or does not access a cell, which may mean any cell selection state).

The UE according to an embodiment of the present disclosure may store mobility history information in VarMobilityHistoryReport by performing operations according to the following conditions.

-condition 1-1: when a cell consisting of a PCell in RRC CONNECTED mode or a serving cell in rrc_idle changes (i.e. when it is changed to another E-UTRA cell or inter-RAT cell), or when (when a cell consisting of a PCell in rrc_connected or a serving cell in rrc_idle is changed to another E-UTRA or inter-RAT cell), it goes out of service, or when it goes out of service

-conditions 1-2: when a cell consisting of a PCell in RRC CONNECTED mode or a serving cell in rrc_inactive (E-UTRA cell) or a serving cell in rrc_idle (E-UTRA cell or inter-RAT cell) changes (i.e. when it is changed to another E-UTRA cell or to an inter-RAT cell), or when (when a suitable cell consisting of a PCell in rrc_connected or a serving cell in rrc_inactive (for E-UTRA cell) or in rrc_idle (for E-UTRA or inter-RAT cell) is changed to another E-UTRA or inter-RAT cell) enters any cell selection state from the normal camping state in LTE or inter-RAT, or when entering any cell selection state from the normal camping state in LTE or inter-RAT

Operation 1: when the condition 1-1 or the condition 1-2 is satisfied,

the oldest entry value is deleted if necessary, and the following may be included in the entry for the VarMobilityHistoryReport variable (if necessary, the entry in the variable VarMobilityHistoryReport may be included after the oldest entry is removed, according to the following)

If there is a global cell identifier of the previous PCell or serving cell, the global cell identifier of the previous PCell or serving cell may be stored in the visitedCellId field (if the global cell identifier of the previous PCell/serving cell is available, the global cell identifier of the cell is included in the field visitedCellId of the entry). Otherwise, the carrier frequency and physical cell identifier of the previous PCell or serving cell may be stored in the visitedelld field (otherwise, the physical cell identity and carrier frequency of the cell is included in the entry's field visitedelld). The time spent in the previous PCell or serving cell may be stored in the time stamp field (the field of the entry time stamp is set to the time spent in the previous PCell/serving cell).

Condition 2-1: previously out of service and using another RAT (i.e., a RAT other than E-UTRA), then enter E-UTRA in rrc_connected or rrc_idle. Alternatively, the service is previously stopped or another RAT is used, and then E-UTRA is entered (when it is in RRC_CONNECTED or RRC_IDLE) when it is previously stopped and/or another RAT is used

Condition 2-2: previously in any cell selection state, or in any cell camped state in LTE or inter-RAT, then (when entering the normal camped state in E-UTRA (in rrc_ CONNECTED, RRC _idle, rrc_inactive) while in "any cell selection" state or "camped on any cell" state in LTE or inter-RAT previously) entering the normal camped state to E-UTRA in rrc_connected or rrc_idle or rrc_inactive

Operation 2: when the condition 2-1 or the condition 2-2 is satisfied,

The time spent outside E-UTRA may be stored in the time-stamp field (the field time stamp of the entry is set to the time spent outside E-UTRA), or the time spent in LTE or inter-RAT in any cell-selection state and/or in any on-cell state may be stored in the time-stamp field (the field time stamp of the entry is set to the time spent in LTE or inter-RAT in "any cell-selection" state and/or "on-cell" state)

For reference, the inter-RAT specified above may mean all inter-RAT cells, or may mean only some inter-RAT cells (e.g., NR cells) among inter-RAT cells.

Referring to fig. 7, the ue may store mobility history information in VarMobilityHistoryReport according to the above-described method from steps 7-05 to 7-45. For example, the UE may store at least one of the following information in VarMobilityHistoryReport.

Global cell identifier or carrier frequency and physical cell identifier of E-UTRA cell 1, and time spent in E-UTRA cell 1 10s (7-05)

Global cell identifier or carrier frequency and physical cell identifier of E-UTRA cell 2, and time spent in E-UTRA cell 25 s (7-10)

Time 10s spent in IRAT (inter-RAT) cell 1 or global cell identifier or carrier frequency and physical cell identifier of IRAT (inter-RAT) cell 1, and time 10s spent in IRAT (inter-RAT) cell 1 (7-15)

Global cell identifier or carrier frequency and physical cell identifier of E-UTRA cell 3, and time 2s spent in E-UTRA cell 3 (7-20)

Time spent out of service 3s (7-25)

Global cell identifier or carrier frequency and physical cell identifier of E-UTRA cell 4, and time 5s spent in E-UTRA cell 4 (7-30)

Time 2s spent in IRAT (inter-RAT) cell 2 or global cell identifier or carrier frequency and physical cell identifier of IRAT (inter-RAT) cell 2, and time 2s spent in IRAT (inter-RAT) cell 2 (7-13)

Global cell identifier or carrier frequency and physical cell identifier of E-UTRA cell 5, and time 5s spent in E-UTRA cell 5 (7-30)

-CellGloballdEUTRA

celGlobaldEUTRA information element

-CGI-InfoEUTRALogging

cGI-InfoEUTRALogging information element

/>

For reference, the global cell identifier of the NR cell may mean the following.

-CGl-lnfo-Loggmg

CGI-Info-Logging information element

In steps 7-45, the E-UTRA cell 5 of the UE in the RRC connected mode may be connected to a primary cell (PCell).

In steps 7-50, the UE may receive a UE information request message including a mobilityHistoryReportReq from the LTE base station. If mobilityHistoryReport is set to true, then in steps 7-55 the UE may include the entry value included in VarMobilityHistoryReport in mobilityHistoryReport (including mobilityHistoryReport and set it to include an entry from VarMobilityHistoryReport)

In steps 7-60, the oldest entry value of the current cell (e.g., E-UTRA cell 5) may be deleted, if necessary, and the global cell identifier of the current cell (E-UTRA cell 5) and the time spent in E-UTRA cell 5 may be included in the entry in VarMobility HistolyReport.

In steps 7-65, the UE may include the above-described mobilityHistoryReport in a UE information response message and transmit it to the LTE base station.

Fig. 8 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an LTE system according to an embodiment of the present disclosure.

Referring to fig. 8, an lte base station 8-02 may broadcast system information (8-05). According to an embodiment of the present disclosure, it is proposed that the base station or LTE cell 8-02 broadcasts an indicator in the system information indicating that SCG MHI is supported. If an indicator is broadcast in the system information, the UE 8-01 may store SCG MHI in VarMobilityHistoryReport when changing PSCell or when releasing PSCell.

In step 8-10, the UE 8-01 may be in RRC CONNECTED mode RRC_CONNECTED by establishing an RRC connection (8-10) with the LTE base station 8-02.

In step 8-13, the UE 8-01 may send a UE capability information message (UE capability information) to the LTE base station 8-02 including an indicator that may store the SCG MHI.

It is proposed that a UE according to an embodiment of the present disclosure, when it has the capability to store SCG MHI, sends a UE capability information message (UE capability information) to the LTE base station including an indicator that can store SCG MHI.

Alternatively, even though the UE according to an embodiment of the present disclosure has the capability of storing SCG MHI, as in the above-described embodiment, the UE may not notify the LTE base station of a UE capability information message (UE capability information).

In step 8-15, the Master Node (MN) 8-02 may initiate a secondary node addition procedure to add the Secondary Node (SN) 8-03. The particular secondary node addition procedure may follow section TS 37.340 10.2. NR PSCell 1 8-03 can be added to UE 8-01 by step 8-15.

In step 8-20, for UE 8-01, NR PSCell 1 8-03 can be changed to NR PSCell 2 8-04 by a secondary node modification procedure or a secondary node change procedure. The particular secondary node modification procedure or secondary node change procedure may follow section TS 37.340 10.3 or section TS 37.340 10.5.

In step 8-25, the UE 8-01 may store the SCG MHI of NR PScell 1 in VarMobilyHistory report. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReport.

The operation is as follows:

when the NR PSCell changes (NR PSCell 1. Fwdarw. NR PSCell 2), the oldest entry value is deleted, if necessary, and the following may be included in the entries in the VarMobilyHistolyReport variable (if necessary, the entries in the variable VarMobilyHistolyReport may be included after the oldest entry is removed, according to the following)

If there is a global cell identifier of the previous PSCell (NR PSCell 1), the global cell identifier of the previous PSCell may be stored in the visitedelld field (if the global cell identifier of the previous PSCell is available, the global cell identifier of the previous PSCell is included in the field visitedelld of the entry). Otherwise, the carrier frequency and physical cell identifier of the previous PSCell may be stored in the visitedelld field (otherwise, the physical cell identity and carrier frequency of the cell is included in the entry's field visitedelld).

An indicator for indicating PSCell may be included.

The time spent in the previous PSCell may be stored in the time stamp field (the field time stamp of the entry is set to the time spent in the previous PSCell).

When it is spent in the previous PSCell, a global cell identifier of the PCell or a carrier frequency and physical cell identifier of the PCell may be included. In this case, there may be one or more global cell identifiers of the PCell or carrier frequencies and physical cell identifiers of the PCell.

In step 8-30, NR PScell 2 8-04 configured for UE 8-01 can be released by a secondary node release procedure. The particular secondary node release procedure or secondary node change procedure may follow section TS 37.34010.4.

In step 8-35, the UE 8-01 may store the SCG MHI of NR PScell 2 in VarMobilyHistory report. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReport.

The operation is as follows:

when the NR PSCell is released (release of NR PSCell 2), the oldest entry value is deleted, if necessary, and the following may be included in the entries of the VarMobilityHistoryReport variable (according to which it is possible to include the entries in the variable VarMobilityHistoryReport after removal of the oldest entry

If there is a global cell identifier of the released PSCell (NR PSCell 2), the global cell identifier of the released PSCell may be stored in a visitedelld field (if the global cell identifier of the released PSCell is available, the global cell identifier of the released PSCell is included in the field visitedelld of the entry). Otherwise, the carrier frequency and physical cell identifier of the released PSCell may be stored in the visitedelld field (otherwise, the physical cell identity and carrier frequency of the cell is included in the entry's field visitedelld).

An indicator for indicating PSCell may be included.

The time spent in the released PSCell may be stored in the time stamp field (the field time stamp of the entry is set to the time spent in the released PSCell).

A global cell identifier of the PCell or a carrier frequency and physical cell identifier of the PCell until the PSCell is released. In this case, there may be one or more global cell identifiers of the PCell or carrier frequencies and physical cell identifiers of the PCell.

In step 8-40, the LTE base station 8-02 may send an RRC connection release message to the UE 8-01. If the RRC connection release message includes RRC-Inactive Config information, the UE in the RRC connected mode may transition (8-45) to an RRC INACTIVE mode (RRC_INACTIVE). If the RRC connection release message does not include RRC-Inactive Config information, the UE in the RRC connected mode may transition (8-45) to an RRC IDLE mode (RRC_IDLE).

The UE 8-01 in RRC idle mode may send an RRC connection request message (RRCConnectionRequest) 8-50 to the base station to perform an RRC connection setup procedure with the LTE base station 8-02. Upon receiving the RRC connection request message, the base station 8-02 may send (8-60) an RRC connection setup message (RRCConnectionSetup) to the UE 8-01 in response thereto. The UE receiving the RRC connection setup message may apply the RRC connection setup message and transition to the RRC connected mode (8-61). The RRC connected mode UE may then send an RRC connection setup complete message (rrcconnectionsetup complete) to the base station (8-65). If the UE supports storage of mobility history information or supports SCG MHI according to the above embodiments and the mobility history information exists in the VarMobilityHistoryReport (if the UE supports storage of mobility history information or storage of SCG MHI and the UE has mobility history information available in the VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in the RRC connection setup complete message and transmit it to the base station (8-65).

The UE 8-01 in the RRC inactive mode may send an RRC connection resume request message (RRCConnectionResumeRequest) 8-50 to the base station to perform an RRC connection resume procedure with the LTE base station 8-02. Upon receiving the RRC connection resume request message, the base station 8-02 may send an RRC connection resume message to the UE 8-01 in response thereto (8-60). The UE receiving the RRC connection resume message may apply the RRC connection resume message and transition to the RRC connected mode (8-61). The RRC connected mode UE may then send (8-65) an RRC connection resume complete message (rrcconnectionresuxemplete) to the base station. If the UE supports storage of mobility history information or supports SCG MHI according to the above embodiments and the mobility history information exists in the VarMobilityHistoryReport (if the UE supports storage of mobility history information or storage of SCG MHI and the UE has mobility history information available in the VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in the RRC connection restoration complete message and transmit it to the base station (8-65).

In step 8-70, the LTE base station 8-02 may perform a UE information procedure when security is successfully activated. That is, the base station 8-02 may send (8-70) a UE information request message (ueinfo request) to the UE 8-01 to request conventional mobility history information or SCG MHI from the UE 8-01. The UE information request message may include a MobilityHistoryReportReq indicator.

Upon successful activation of security in step 8-75, the UE 8-01 may send (8-75) a UE information response message (ueinfo response) to the LTE base station 8-02. If the mobilityHistoryReportReq is set to true in the received UE information request message, the UE may perform at least one of the following series of procedures.

Information can be included in VarMobilityHistoryReport, in mobilityHistoryReport (including mobilityHistoryReport and set to include entries from VarMobilityHistoryReport). If the VarMobilty HistolyReport has SCG MHI, the UE may include it in the Mobile HistolyReport. Alternatively, the UE may include the SCG MHI in the mobilityHistoryReport when it exists in the varmobilityhistoryreport only when the LTE base station 8-02 broadcasts an indicator indicating that the SCG MHI is supported in the system information.

The oldest information may be deleted if necessary, and information about the current PCell may be included in the mobilityHistoryReport as follows (including the entry of the current PCell in the mobilityHistoryReport, possibly after removing the oldest entry as needed, its fields are set as follows

The global cell identifier of the current PCell may be set to visitedcylid (visitedcylid is set to the global cell identifier of the current PCell)

The time spent in the current cell can be set in the time-stamp field (set the field time stamp to the time spent in the current PCell)

When PSCell is set, the oldest information can be deleted, if necessary, and information about the current PSCell can be included in the mobilityHistoryReport as follows (including the entry of the current PSCell in mobilityHistoryReport, possibly after removing the oldest entry as required, its fields are set as follows

The global cell identifier of the current PSCell or the carrier frequency and physical cell identifier of the PSCell may be set to visitedCellId visitedCellId (the visitedcelid is set to the global cell identifier or the carrier frequency and physical cell identifier of the current PSCell)

The time spent in the current cell can be set in the time-stamp field (set the field time stamp to the time spent in the current PSCell)

An indicator for indicating PSCell may be included.

-the UE may perform the procedure described above to include the mobilityHistoryReport in a UE information response message and send it to the base station (8-75).

Fig. 9 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an LTE system according to an embodiment of the present disclosure.

Referring to fig. 9, the lte base station 9-02 may broadcast system information (9-05). According to an embodiment of the present disclosure, it is proposed that the base station or LTE cell 9-02 broadcasts an indicator in the system information indicating that SCG MHI is supported. If an indicator is broadcast in the system information, the UE 9-01 may store SCG MHI in VarMobilityHistoryReport when changing PSCell or when releasing PSCell.

In step 9-10, the UE 9-01 may be in RRC CONNECTED mode RRC_CONNECTED by establishing an RRC connection (9-10) with the LTE base station 9-02.

In step 9-13, the UE 9-01 may send a UE capability information message (UE capability information) to the LTE base station 9-02 including an indicator that may store the SCG MHI. It is proposed that a UE according to an embodiment of the present disclosure, when it has the capability to store SCG MHI, sends a UE capability information message (UE capability information) to the LTE base station including an indicator that can store SCG MHI. Alternatively, even though the UE according to an embodiment of the present disclosure has the capability of storing SCG MHI, as in the above-described embodiment, the UE may not notify the LTE base station of a UE capability information message (UE capability information).

In step 9-15, the Master Node (MN) 9-02 may initiate a secondary node addition procedure to add the Secondary Node (SN) 9-03. The particular secondary node addition procedure may follow section TS 37.340 10.2. NR PSCell 1 9-03 can be added to UE 9-01 by step 9-15.

In step 9-20, for UE 9-01, NR PSCell 1 9-03 can be changed to NR PSCell 2 9-04 by a secondary node modification procedure or a secondary node change procedure. The particular secondary node modification procedure or secondary node change procedure may follow section TS 37.340 10.3 or section TS 37.340 10.5.

In step 9-25, the UE 9-01 may store the SCG MHI of NR PSCell 1 in VarMobilty History ReportSCG as a new variable. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReportSCG.

The operation is as follows:

when the NR PSCell changes (NR PSCell 1. Fwdarw. NR PSCell 2), the oldest entry value is deleted, if necessary, and the following may be included in the entries of the VarMobilty HistolyReportSCG variable (possibly including the entries in the variable VarMobilty HistolyReportSCG after removing the oldest entry, if necessary, according to the following)

In step 9-30, NR PScell 2 9-04 configured for UE 9-01 can be released by the secondary node release procedure. The particular secondary node release procedure or secondary node change procedure may follow section TS 37.34010.4.

In step 9-35, the UE 9-01 may store the SCG MHI of NR PScell 2 in VarMobilyHistory report. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReportSCG.

The operation is as follows:

when the NR PScell is released (release of NR PScell 2), the oldest entry value is deleted, if necessary, and the following may be included in the entries of the VarMobilyHistolyReportSCG variable (the entries in the variable VarMobilyHistolyReportSCG may be included after the oldest entry is removed, if necessary, according to the following)

In step 9-40, the LTE base station 9-02 may send an RRC connection release message to the UE 9-01. If the RRC connection release message includes RRC-Inactive Config information, the UE in the RRC connected mode may transition (9-45) to an RRC INACTIVE mode (RRC_INACTIVE). If the RRC connection release message does not include RRC-Inactive Config information, the UE in the RRC connected mode may transition (9-45) to an RRC IDLE mode (RRC_IDLE).

The UE 9-01 in RRC idle mode may send an RRC connection request message (RRCConnectionRequest) 9-50 to the base station to perform an RRC connection setup procedure with the LTE base station 9-02. Upon receiving the RRC connection request message, the base station 9-02 may send (9-60) an RRC connection setup message (RRCConnectionSetup) to the UE 9-01 in response thereto. The UE receiving the RRC connection setup message may apply the RRC connection setup message and transition to the RRC connected mode (9-61). The RRC connected mode UE may then send an RRC connection setup complete message (rrcconnectionsetup complete) to the base station (9-65). If the UE supports storage of mobility history information in the above embodiment and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in an RRC connection setup complete message and transmit it to the base station (9-65). If the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include a mobilityavailscg indicator as a new indicator in an RRC connection setup complete message and send (9-65) it to the base station. Alternatively, if the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include mobility historyavailscg as a new indicator in the RRC connection setup complete message and transmit (9-65) to the base station when the LTE base station 9-02 broadcasts an indicator indicating that SCG MHI is supported in the system information.

The UE 9-01 in the RRC inactive mode may send an RRC connection resume request message (RRCConnectionResumeRequest) 9-50 to the base station to perform an RRC connection resume procedure with the LTE base station 9-02. Upon receiving the RRC connection resume request message, the base station 9-02 may send an RRC connection resume message to the UE 9-01 in response thereto (9-60). The UE receiving the RRC connection resume message may apply the RRC connection resume message and transition to the RRC connected mode (9-61). The RRC connected mode UE may then send (9-65) an RRC connection resume complete message (rrcconnectionresuxemplete) to the base station. If the UE supports storage of mobility history information in the above embodiment and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in an RRC connection restoration complete message and transmit it to the base station (9-65). If the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include a mobilityavailscg indicator as a new indicator in an RRC connection resume complete message and send (9-65) it to the base station. Alternatively, if the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include mobility historyavailscg as a new indicator in the RRC connection resume complete message and transmit (9-65) it to the base station when the LTE base station 9-02 broadcasts an indicator indicating that SCG MHI is supported in the system information.

In step 9-70, the LTE base station 9-02 may perform a UE information procedure when security is successfully activated. That is, the base station 9-02 may transmit (9-70) a UE information request message (ueinfo request) to the UE 9-01 to request conventional mobility history information or SCG MHI from the UE 9-01. The UE information request message may include a MobilityHistoryReportReq indicator.

Upon successful activation of security in step 9-75, the UE 9-01 may send (9-75) a UE information response message (ueinfo response) to the LTE base station 9-02. If the mobilityHistoryReportReq is set to true in the received UE information request message, the UE may perform at least one of the following series of procedures.

If the VarMobilty HistolyReportSCG has a SCG MHI, the UE may include it in the Mobilty HistolyReportSCG. Alternatively, the UE may include the SCG MHI in the mobilityHistoryReportSCG when it exists in the varmobilityreportscg only when the LTE base station 9-02 broadcasts an indicator indicating that the SCG MHI is supported in the system information.

When PSCell is set, the oldest information can be deleted, if necessary, and information about the current PSCell can be included in the mobilityHistoryReportSCG as follows (including the entries of the current PSCell in the mobilityHistoryReportSCG, possibly after removing the oldest entries as required, the fields of which are set as follows

The global cell identifier of the current PSCell or the carrier frequency and physical cell identifier of the PSCell may be set to visitedCellId visitedCellId (the visitedcylid is set to the global cell identifier of the current PSCell or the carrier frequency and physical cell identifier)

The UE may perform the above procedure to include the mobilityHistoryReport and/or mobilityHistoryReport scg in the UE information response message and send it to the base station (9-75).

Fig. 10 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an LTE system according to an embodiment of the present disclosure.

Referring to fig. 10, an lte base station 10-02 may broadcast system information (10-05). According to an embodiment of the present disclosure, it is proposed that the base station or LTE cell 10-02 broadcasts an indicator in the system information indicating that SCG MHI is supported. If an indicator is broadcast in the system information, the UE 10-01 may store SCG MHI in VarMobilityHistoryReport when changing PSCell or when releasing PSCell.

In step 10-10, the UE 10-01 may be in RRC CONNECTED mode RRC_CONNECTED by establishing an RRC connection (10-10) with the LTE base station 10-02.

In step 10-13, the UE 10-01 may send a UE capability information message (UE capability information) to the LTE base station 10-02 including an indicator that may store the SCG MHI. It is proposed that a UE according to an embodiment of the present disclosure, when it has the capability to store SCG MHI, sends a UE capability information message (UE capability information) to the LTE base station including an indicator that can store SCG MHI. Alternatively, even though the UE according to an embodiment of the present disclosure has the capability of storing SCG MHI, as in the above-described embodiment, the UE may not notify the LTE base station of a UE capability information message (UE capability information).

In step 10-15, the Master Node (MN) 10-02 may initiate a secondary node addition procedure to add the Secondary Node (SN) 10-03. The particular secondary node addition procedure may follow section TS 37.340 10.2. NR PSCell 1 10-03 may be added to UE 10-01 by step 10-15.

In step 10-20, for the UE 10-01, the NR PSCell 1-03 may be changed to NR PSCell 2 10-04 by a secondary node modification procedure or a secondary node change procedure. The particular secondary node modification procedure or secondary node change procedure may follow section TS 37.340 10.3 or section TS 37.340 10.5.

In step 10-25, the UE 10-01 may store the SCG MHI of NR PSCell 1 in VarMobilty History ReportSCG as a new variable. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReportSCG.

The operation is as follows:

In step 10-30, NR PScell 2 10-04 configured for UE 10-01 can be released by a secondary node release procedure. The particular secondary node release procedure or secondary node change procedure may follow section TS37.340 10.4.

In step 10-35, the UE 10-01 may store the SCG MHI of NR PScell 2 in VarMobilyHistory report. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReportSCG.

The operation is as follows:

when the NR PSCell is released (release of NR PSCell 2), the oldest entry value is deleted, if necessary, and the following may be included in the entries of the VarMobilityHistoryReportSCG variable (possibly including the entries in the variable VarMobilityHistoryReportSCG after removal of the oldest entry, if necessary, according to the following)

In step 10-40, the LTE base station 10-02 may send an RRC connection release message to the UE 10-01. If the RRC connection release message includes RRC-Inactive Config information, the UE in the RRC connected mode may transition (10-45) to an RRC INACTIVE mode (RRC_INACTIVE). If the RRC connection release message does not include RRC-Inactive Config information, the UE in the RRC connected mode may transition (10-45) to an RRC IDLE mode (RRC_IDLE).

The UE 10-01 in RRC idle mode may send an RRC connection request message (RRCConnectionRequest) 10-50 to the base station to perform an RRC connection setup procedure with the LTE base station 10-02. Upon receiving the RRC connection request message, the base station 10-02 may send (10-60) an RRC connection setup message (RRCConnectionSetup) to the UE 10-01 in response thereto. The UE receiving the RRC connection setup message may apply the RRC connection setup message and transition to the RRC connected mode (10-61). The RRC connected mode UE may then send an RRC connection setup complete message (rrcconnectionsetup complete) to the base station (10-65). If the UE supports storage of mobility history information in the above embodiment and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in an RRC connection setup complete message and transmit it to the base station (10-65). If the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE obtains mobility history information in VarMobilityHistoryReportSCG), the UE may include a mobilityavailscg indicator as a new indicator in an RRC connection setup complete message and send (10-65) it to the base station. Alternatively, if the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include mobility historyavailscg as a new indicator in an RRC connection setup complete message and transmit (10-65) to the base station when the LTE base station 10-02 broadcasts an indicator indicating that SCG MHI is supported in system information.

The UE 10-01 in the RRC inactive mode may send an RRC connection resume request message (RRCConnectionResumeRequest) 10-50 to the base station to perform an RRC connection resume procedure with the LTE base station 10-02. Upon receiving the RRC connection resume request message, the base station 10-02 may transmit an RRC connection resume message (10-60) to the UE 10-01 in response thereto. The UE receiving the RRC connection resume message may apply the RRC connection resume message and transition to the RRC connected mode (10-61). The RRC connected mode UE may then send (10-65) an RRC connection resume complete message (rrcconnectionresuxemplete) to the base station. If the UE supports storage of mobility history information in the above embodiment and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in an RRC connection restoration complete message and transmit it to the base station (10-65). If the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include a mobilityavailscg indicator as a new indicator in an RRC connection resume complete message and send (10-65) it to the base station. Alternatively, if the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include mobility historyavailscg as a new indicator in an RRC connection restoration complete message and transmit (10-65) it to the base station when the LTE base station 10-02 broadcasts an indicator indicating that SCG MHI is supported in system information.

In step 10-70, the LTE base station 10-02 may perform a UE information procedure when security is successfully activated. That is, the base station 10-02 may transmit (10-70) a UE information request message (ueinfo request) to the UE 10-01 to request conventional mobility history information or SCG MHI from the UE 10-01. The UE information request message may include a MobilityHistoryReportReq indicator for reporting regular mobility history information and/or a new MobilityHistoryReportReqSCG indicator for reporting SCG MHI.

Upon successful activation of security in step 10-75, the UE 10-01 may send (10-75) a UE information response message (ueinfo response) to the LTE base station 10-02. If the mobilityHistoryReportReq is set to true in the received UE information request message, the UE may perform at least one of the following series of procedures.

If the mobilityHistoryReportReqSCG is set to true in the received UE information request message, the UE may perform at least one of the following series of procedures.

If the VarMobilty HistolyReportSCG has a SCG MHI, the UE may include it in the Mobilty HistolyReportSCG. Alternatively, the UE may include the SCG MHI in the mobilityHistoryReportSCG when it exists in the varmobilityreportscg only when the LTE base station 10-02 broadcasts an indicator indicating that the SCG MHI is supported in the system information.

The global cell identifier of the current PSCell or the carrier frequency and physical cell identifier of the PSCell may be set to visitedCellId visitedCellId (the visitedcylid is set to the global cell identifier or the carrier frequency and physical cell identifier of the current PSCell)

The UE may perform the above procedure to include the mobilityHistoryReport and/or mobilityHistoryReport scg in the UE information response message and send it to the base station (10-75).

Fig. 11 is a view showing a UE operation in which a UE reports Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") to a base station in an LTE system according to an embodiment of the present disclosure.

Referring to fig. 11, an lte base station 11-02 may broadcast system information (11-05). According to an embodiment of the present disclosure, it is proposed that the base station or LTE cell 11-02 broadcasts an indicator in the system information indicating that SCG MHI is supported. If an indicator is broadcast in the system information, the UE 11-01 may store SCG MHI in VarMobilityHistoryReport when changing PSCell or when releasing PSCell.

In step 11-10, the UE 11-01 may be in RRC CONNECTED mode RRC_CONNECTED by establishing an RRC connection (11-10) with the LTE base station 11-02.

In step 11-13, the UE 11-01 may send a UE capability information message (UE capability information) including an indicator that may store SCG MHI to the LTE base station 11-02. It is proposed that a UE according to an embodiment of the present disclosure, when it has the capability to store SCG MHI, sends a UE capability information message (UE capability information) to the LTE base station including an indicator that can store SCG MHI.

In step 11-15, the LTE base station 11-02 may configure the UE 11-01 to report a mobilityHistoryAvailSCG indicator or mobilityHistoryReportSCG by using predetermined configuration information. For example, the predetermined configuration information may mean an otherConfig field.

In step 11-20, the UE 11-01 may include the mobilityHistoryAvailSCG indicator in a predetermined RRC message and may transmit it to the LTE base station 11-02. The predetermined RRC message may mean, for example, one of an RRC connection restoration complete message (rrcconnectionresuxecomp), an RRC connection reconfiguration complete message (RRCConnectionReconfigurationComplete), and an RRC connection reestablishment complete message (RRCConnectionReestablishmentComplete).

In step 11-25, the LTE base station 11-02 may include the mobilityHistoryReportSCG in a UE information request message (UEInformationRequest) and transmit it to the UE 11-01.

In step 11-30, the UE 11-01 may include the mobilityHistoryReportSCG in a UE information response message (ueinfo response) and transmit it. In other words, in steps 11-25, if the mobilityHistoryReportReqSCG is set to true in the received UE information request message, the UE may perform at least one of the following series of procedures.

If the VarMobilty HistolyReportSCG has a SCG MHI, the UE may include it in the Mobilty HistolyReportSCG.

Alternatively, in step 11-35, the LTE base station 11-02 may send a predetermined RRC message to the UE 11-01 including the mobilityHistory ReportSCG. The predetermined RRC message may mean, for example, one of an RRC connection restoration message (rrcconnectionreset), an RRC connection reconfiguration message (RRCConnectionReconfiguration), and an RRC connection reestablishment message (RRCConnectionReestablishment).

In step 11-40, a predetermined RRC message including a mobilityHistolyReportSCG may be transmitted to the UE 11-01. The predetermined RRC message may mean, for example, one of an RRC connection restoration complete message (rrcconnectionresuxecomp), an RRC connection reconfiguration complete message (RRCConnectionReconfigurationComplete), and an RRC connection reestablishment complete message (RRCConnectionReestablishmentComplete). In other words, if the mobilityHistoryReportReqSCG is set to true in the RRC message received in steps 11-35, the UE may perform the above procedure to include the mobilityHistoryReportReq in the RRC message and transmit a method for doing the same in response to the RRC message received in steps 11-35.

Fig. 12 is a flowchart showing a procedure in which a UE reports mobility history information to an NR base station in an NR system.

Referring to fig. 12, the ue 12-01 may be in an RRC IDLE mode (rrc_idle) or an RRC INACTIVE mode (rrc_inactive).

The UE 12-01 in the RRC idle mode may send an RRC connection request message (rrcsetup request) 12-10 to the base station to perform an RRC connection setup procedure with the base station 12-02. Upon receiving the RRC connection request message, the base station 12-02 may send (12-15) an RRC connection setup message (RRCSetup) to the UE 12-01 in response thereto. The UE receiving the RRC connection setup message may apply the RRC connection setup message and transition to the RRC connected mode (12-16). The RRC connected mode UE may then send an RRC connection setup complete message (rrcsetup complete) to the base station (12-20). If the UE supports storage of mobility history information and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobility historyavail indicator in an RRC connection setup complete message and transmit it to the base station (12-20).

The UE 12-01 in the RRC inactive mode may send (12-10) an RRC connection resume request message (RRCResumeRequest) or an RRC connection resume request1 message (RRCResumeRequest 1) to the base station to perform an RRC connection resume procedure with the base station 12-02. Upon receiving the RRC connection resume request message, the base station 12-02 may send (12-15) an RRC connection resume message (rrreport) to the UE 12-01 in response thereto. The UE receiving the RRC connection resume message may apply the RRC connection resume message and transition to the RRC connected mode (12-16). The RRC connected mode UE may then send (12-20) an RRC connection resume complete message (RRCResumeComplete) to the base station. If the UE supports storage of mobility history information and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobility historyavail indicator in an RRC connection restoration complete message and transmit it to the base station (12-20).

The UE 12-01 that has not been configured with security may perform an initial security activation procedure (12-21) with the base station 12-02. For example, a UE that is not configured with security may refer to a UE that has switched from RRC idle mode to RRC connected mode. Specifically, the UE 12-01 may transmit a security mode command message (security modecommand) to the base station 12-02, and in response thereto, the base station may transmit a security mode complete message (security modecomplete) to the UE.

To perform the RRC connection reconfiguration procedure in step 12-25, the base station 12-02 may send an RRC connection reconfiguration message (rrcrecon configuration) to the RRC connected mode UE 12-01. The UE may apply the received RRC connection reconfiguration message and may send (12-30) an RRC connection reconfiguration complete message (RRCnReconfigurationComplete) to the base station in response thereto.

In step 12-35, the base station 12-02 may perform a UE information procedure upon successful performance of the security activation. The base station 12-02 may send (12-35) a UE information request message (ueinfo request) to the UE to request mobility history information from the UE 12-01. The UE information request message may include a MobilityHistoryReportReq indicator.

In step 12-40, the UE 12-01 that successfully performs the security activation may send (12-40) a UE information response (UEInformationResponse) to the base station 12-02. If the mobilityHistoryReportReq is set to true in the received UE information request message, the UE may perform the following series of procedures.

The UE may perform the above procedure to include the mobilityHistoryReport in a UE information response message and send it to the base station (12-40).

The UE according to the NR system has the following characteristics when storing and reporting mobility history information to the NR base station.

Fig. 13 is a view showing a UE operation in which a UE stores mobility history information and reports it to a base station in an NR system.

A UE supporting storing mobility history information may change the (suitable) serving cell in RRC IDLE mode (rrc_idle) or RRC INACTIVE mode (rrc_inactive), or the PCell in RRC CONNECTED mode (rrc_connected), or may enter out of service (e.g. when it camps on a cell or does not access a cell, which may mean any cell selection state). The UE according to an embodiment of the present disclosure may store mobility history information in VarMobilityHistoryReport by performing operations according to the following conditions.

-condition 1: when a cell consisting of an LTE PCell or an NR PCell in RRC CONNECTED mode or a serving cell (NR cell) in rrc_inactive or a serving cell (NR cell or E-UTRA cell) in rrc_idle changes (i.e. when it is changed to another NR or to an E-UTRA cell), or when a cell consisting of an LTE PCell in rrc_connected (for NR cell or E-UTRA cell) or a serving cell in rrc_inactive (for NR cell) or an appropriate cell consisting of a serving cell in rrc_idle (for NR cell or E-UTRA cell) changes to another NR or E-UTRA cell), enters any cell selection state from the normal stay state in NR or LTE, or when entering any cell selection state from the normal stay state in NR or LTE

Operation 1: if condition 1 is satisfied, then

-condition 2: previously in any cell-selection state in LTE or NR, and/or in camped on any cell in NR or LTE, then (when entering the camped-on state in NR (in rrc_ CONNECTED, RRC _idle, rrc_inactive) while previously in "any cell-selection" state or "camped on any cell" state in NR or LTE) entering the camped-on state to E-UTRA in rrc_connected or rrc_idle or rrc_inactive

Operation 2: if condition 2 is satisfied, then,

the oldest entry value is deleted if necessary, and the following may be included in the entries in the VarMobilityHistoryReport variable (if necessary, the entries in the variable VarMobilityHistoryReport may be included after the oldest entry is removed, according to the following)

In NR or LTE, the time spent in any cell selection state and/or camping on any cell can be stored in the time stamp field (the field of the entry time stamp is set to the time spent in NR or LTE in "any cell selection" state and/or "camping on any cell" state)

Referring to fig. 13, the ue may store mobility history information in VarMobilityHistoryReport according to the above-described method from steps 13-05 to 13-30. For example, the UE may store at least one of the following information in VarMobilityHistoryReport.

Global cell identifier or carrier frequency and physical cell identifier of NR cell 1, and time spent in NR cell 1 10s (13-05)

Global cell identifier or carrier frequency and physical cell identifier of NR cell 2, and time spent in NR cell 25 s (13-10)

Global cell identifier or carrier frequency and physical cell identifier of E-UTRA cell 1, and time spent in E-UTRA cell 1 10s (13-15)

Global cell identifier or carrier frequency and physical cell identifier of NR cell 3, and time 2s spent in E-UTRA cell 3 (13-20)

Time spent out of service 3s (13-25)

-CGI-Info-Logging

cGI-Info-Logging information element

/>

For reference, the global cell identifier of an E-UTRA cell may mean celGlobalIdEUTRA or CGI-InfoEUTRALogging.

-CellGloballdEUTRA

celgioballdeutra information element

--CGI-InfoEUTRALogging

cGI-InfoEUTRALogging information element

/>

In steps 13-30, NR cell 4 of the UE in RRC connected mode may be connected to a primary cell (PCell).

In steps 13-35, the UE may receive a UE information request message including a mobilityHistoryReportReq from the NR base station. If mobilityHistoryReport is set to true, then in steps 13-40 the UE may include the entry value included in VarMobilityHistoryReport in mobilityHistoryReport (including mobilityHistoryReport and set it to include an entry from VarMobilityHistoryReport)

In steps 13-45, the oldest entry value of the current cell (e.g., NR cell 4) may be deleted, and the global cell identifier of the current cell (NR cell 4) and the time spent in NR cell 4 may be included in the entries in VarMobilityHistoryReport, if necessary.

In steps 13-50, the UE may include the above-described mobilityHistoryReport in a UE information response message and transmit it to the NR base station.

Fig. 14 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an NR system according to an embodiment of the present disclosure.

Referring to fig. 14, the nr base station 14-02 may broadcast system information (14-05). According to an embodiment of the present disclosure, it is proposed that the base station or NR cell 14-02 broadcast an indicator in the system information indicating that SCG MHI is supported. If an indicator is broadcast in the system information, the UE 14-01 may store SCG MHI in VarMobilityHistoryReport when changing PSCell or when releasing PSCell.

In step 14-10, the UE 14-01 may be in RRC CONNECTED mode RRC_CONNECTED by establishing an RRC connection (14-10) with the NR base station 14-02.

In step 14-13, the UE 14-01 may send a UE capability information message (UE capability information) to the NR base station 14-02 including an indicator that may store SCG MHI. It is proposed that a UE according to an embodiment of the present disclosure, when it has the capability to store SCG MHI, transmits a UE capability information message (UECapabilityInformation) including an indicator that can store SCG MHI to the NR base station. Alternatively, even if the UE according to the embodiment of the present disclosure has the capability of storing SCG MHI, as in the above-described embodiment, the UE may not notify the NR base station of the UE capability information message (UE capability information).

In step 14-15, the Master Node (MN) 14-02 may initiate a secondary node addition procedure to add the Secondary Node (SN) 14-03. The particular secondary node addition procedure may follow section TS 37.340 10.2. LTE or NR PSCell 1 14-03 may be added to UE 14-01 by steps 14-15.

In step 14-20, for the UE 14-01, LTE or NR PSCell 1-03 may be changed to LTE or NR PSCell2 14-04 by a secondary node modification procedure or a secondary node change procedure. The particular secondary node modification procedure or secondary node change procedure may follow section TS 37.340 10.3 or section TS 37.340 10.5.

In step 14-25, the UE 14-01 may store the SCG MHI of LTE or NR PScell 1 in the VarMobility History report. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReport.

The operation is as follows:

when a change of LTE or NR PSCell occurs (LTE or NR PSCell 1→lte or NR PSCell 2), the oldest entry value is deleted if necessary, and the following may be included in the entry of the VarMobilityHistoryReport variable (possibly including the entry in the variable VarMobilityHistoryReport after removal of the oldest entry, if necessary, according to the following)

If there is a global cell identifier of the previous PSCell (LTE or NR PSCell 1), the global cell identifier of the previous PSCell may be stored in the visitedelld field (if the global cell identifier of the previous PSCell is available, the global cell identifier of the previous PSCell is included in the field visitedelld of the entry). Otherwise, the carrier frequency and physical cell identifier of the previous PSCell may be stored in the visitedelld field (otherwise, the physical cell identity and carrier frequency of the cell is included in the entry's field visitedelld).

An indicator for indicating PSCell may be included.

In step 14-30, the LTE or NR PScell 2 14-04 configured for the UE 14-01 may be released by a secondary node release procedure. The particular secondary node release procedure or secondary node change procedure may follow section TS 37.340 10.4.

In step 14-35, the UE 14-01 may store the SCG MHI of LTE or NR PScell 2 in the VarMobility History report. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReport.

The operation is as follows:

when LTE or NR PSCell is released (release of LTE or NR PSCell 2), the oldest entry value is deleted, if necessary, and the following may be included in the entry of the VarMobilityHistoryReport variable (possibly including an entry in the variable VarMobilityHistoryReport after removal of the oldest entry, if necessary

If there is a global cell identifier of the released PSCell (LTE or NR PSCell 2), the global cell identifier of the released PSCell may be stored in a visitedelld field (if the global cell identifier of the released PSCell is available, the global cell identifier of the released PSCell is included in the field visitedelld of the entry). Otherwise, the carrier frequency and physical cell identifier of the released PSCell may be stored in the visitedelld field (otherwise, the physical cell identity and carrier frequency of the cell is included in the entry's field visitedelld).

An indicator for indicating PSCell may be included.

In step 14-40, the NR base station 14-02 can send an RRC connection release message to the UE 14-01. If the RRC connection release message includes the suptendConfig information, the UE in the RRC connected mode may transition (14-45) to an RRC INACTIVE mode (RRC_INACTIVE). If the RRC connection release message does not include the supensConfig information, the UE in the RRC connected mode may transition (14-45) to an RRC IDLE mode (RRC_IDLE).

The RRC idle mode UE 14-01 may send an RRC connection request message (rrcsetup request) to the base station to perform an RRC connection setup procedure with the NR base station 14-02. Upon receiving the RRC connection request message, the base station 14-02 may send (14-60) an RRC connection setup message (RRCSetup) to the UE 14-01 in response thereto. The UE receiving the RRC connection setup message may apply the RRC connection setup message and transition to the RRC connected mode (14-61). The RRC connected mode UE may then send an RRC connection setup complete message (rrccs setup complete) to the base station (14-65). If the UE supports storage of mobility history information or supports SCG MHI according to the above embodiments and the mobility history information exists in the VarMobilityHistoryReport (if the UE supports storage of mobility history information or storage of SCG MHI and the UE has mobility history information available in the VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in the RRC connection setup complete message and transmit it to the base station (14-65).

The UE 14-01 in the RRC inactive mode may send (14-50) an RRC connection resume request message (RRCResumeRequest) or an RRC connection resume request1 message (RRCResumeRequest 1) to the base station to perform an RRC connection resume procedure with the NR base station 14-02. Upon receiving the RRC connection resume request message, the base station 14-02 may send (14-60) an RRC connection resume message (RRCnResume) to the UE 14-01 in response thereto. The UE receiving the RRC connection resume message may apply the RRC connection resume message and transition to the RRC connected mode (14-61). The RRC connected mode UE can then send (14-65) an RRC connection resume complete message (RRCRESumeCommple) to the base station. If the UE supports storage of mobility history information or supports SCG MHI according to the above embodiments and the mobility history information exists in the VarMobilityHistoryReport (if the UE supports storage of mobility history information or storage of SCG MHI and the UE obtains mobility history information in the VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in the RRC connection restoration complete message and transmit it to the base station (14-65).

In step 14-70, the NR base station 14-02 can perform a UE information procedure when security is successfully activated. That is, the base station 14-02 may send (14-70) a UE information request message (ueinfo request) to the UE 14-01 to request conventional mobility history information or SCG MHI from the UE 14-01. The UE information request message may include a MobilityHistoryReportReq indicator.

Upon successful activation of security in step 14-75, the UE 14-01 may send (14-75) a UE information response message (ueinfo response) to the NR base station 14-02. If the mobilityHistoryReportReq is set to true in the received UE information request message, the UE may perform at least one of the following series of procedures.

Information can be included in VarMobilityHistoryReport, in mobilityHistoryReport (including mobilityHistoryReport and set to include entries from VarMobilityHistoryReport). If the VarMobilty HistolyReport has SCG MHI, the UE may include it in the Mobile HistolyReport. Alternatively, the UE may include the SCG MHI in the mobilityHistoryReport when it exists in the varmobilityhistoryreport only when the NR base station 14-02 broadcasts an indicator indicating that the SCG MHI is supported in the system information.

An indicator for indicating PSCell may be included.

The UE may perform the above procedure to include the mobilityHistoryReport in a UE information response message and send it to the base station (14-75).

Fig. 15 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an NR system according to an embodiment of the present disclosure.

Referring to fig. 15, the nr base station 15-02 may broadcast system information (15-05). According to an embodiment of the present disclosure, it is proposed that the base station or NR cell 15-02 broadcast an indicator in the system information indicating that SCG MHI is supported. If an indicator is broadcast in the system information, the UE 15-01 may store SCG MHI in VarMobilityHistoryReport when changing PSCell or when releasing PSCell.

In step 15-10, the UE 15-01 may be in RRC CONNECTED mode RRC_CONNECTED by establishing an RRC connection (15-10) with the NR base station 15-02.

In step 15-13, the UE 15-01 may send a UE capability information message (UE capability information) to the NR base station 15-02 including an indicator that may store the SCG MHI. It is proposed that a UE according to an embodiment of the present disclosure, when it has the capability to store SCG MHI, transmits a UE capability information message (UECapabilityInformation) including an indicator that can store SCG MHI to the NR base station. Alternatively, even if the UE according to the embodiment of the present disclosure has the capability of storing SCG MHI, as in the above-described embodiment, the UE may not notify the NR base station of the UE capability information message (UE capability information).

In step 15-15, the Master Node (MN) 15-02 may initiate a secondary node addition procedure to add the Secondary Node (SN) 15-03. The particular secondary node addition procedure may follow section TS 37.340 10.2. LTE or NR PSCell 1 15-03 may be added to UE 15-01 through step 15-15.

In step 15-20, for the UE 15-01, LTE or NR PSCell 1-03 may be changed to LTE or NR PSCell2 15-04 by a secondary node modification procedure or a secondary node change procedure. The particular secondary node modification procedure or secondary node change procedure may follow section TS 37.340 10.3 or section TS 37.340 10.5.

In step 15-25, the UE 15-01 may store the SCG MHI of LTE or NR PScell 1 in VarMobilyHistolyReportSCG as a new variable. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReportSCG.

The operation is as follows:

when a change of LTE or NR PSCell occurs (LTE or NR PSCell 1→lte or NR PSCell 2), the oldest entry value is deleted if necessary, and the following may be included in the entry of the VarMobilityHistoryReportSCG variable (possibly including an entry in the variable VarMobilityHistoryReportSCG after removal of the oldest entry, if necessary, according to the following

In step 15-30, the LTE or NR PScell 2 15-04 configured for the UE 15-01 may be released by a secondary node release procedure. The particular secondary node release procedure or secondary node change procedure may follow section TS 37.340 10.4.

In step 15-35, the UE 15-01 may store the SCG MHI of LTE or NR PScell 2 in the VarMobility History report. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReportSCG.

The operation is as follows:

when LTE or NR PSCell is released (release of LTE or NR PSCell 2), the oldest entry value is deleted, if necessary, and the following may be included in the entry of the VarMobilityHistoryReportSCG variable (if necessary, the entry in the variable VarMobilityHistoryReportSCG may be included after the oldest entry is removed, according to the following)

In step 15-40, NR base station 15-02 can send an RRC connection release message to UE 15-01. If the RRC connection release message includes the suptendConfig information, the UE in the RRC connected mode may transition (15-45) to an RRC INACTIVE mode (RRC_INACTIVE). If the RRC connection release message does not include the supensConfig information, the UE in the RRC connected mode may transition (15-45) to an RRC IDLE mode (RRC_IDLE).

The RRC idle mode UE 15-01 may send (15-50) an RRC connection request message (rrcsetup request) to the base station to perform an RRC connection setup procedure with the NR base station 15-02. Upon receiving the RRC connection request message, the base station 15-02 may send (15-60) an RRC connection setup message (RRCSetup) to the UE 15-01 in response thereto.

The UE receiving the RRC connection setup message may apply the RRC connection setup message and transition to the RRC connected mode (15-61). The RRC connected mode UE may then send an RRC connection setup complete message (rrcsetup complete) to the base station (15-65). If the UE supports storage of mobility history information in the above embodiment and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in an RRC connection setup complete message and transmit it to the base station (15-65).

If the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include a mobilityavailscg indicator as a new indicator in an RRC connection setup complete message and send (15-65) it to the base station. Alternatively, if the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include mobility historyavailscg as a new indicator in the RRC connection setup complete message and transmit (15-65) to the base station when the NR base station 15-02 broadcasts an indicator indicating that SCG MHI is supported in the system information.

The UE 15-01 in the RRC inactive mode may transmit (15-50) an RRC connection resume request message (RRCResumeRequest) or an RRC connection resume request1 message (RRCResumeRequest 1) to the base station to perform an RRC connection resume procedure with the NR base station 15-02. Upon receiving the RRC connection resume request message, the base station 15-02 may send (15-60) an RRC connection resume message (rrreport) to the UE 15-01 in response thereto. The UE receiving the RRC connection resume message may apply the RRC connection resume message and transition to the RRC connected mode (15-61). The RRC connected mode UE may then send (15-65) an RRC connection resume complete message (RRCResumeComplete) to the base station. If the UE supports storage of mobility history information in the above embodiment and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in an RRC connection restoration complete message and transmit it to the base station (15-65). If the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include a mobilityavailscg indicator as a new indicator in an RRC connection resume complete message and send (15-65) it to the base station.

Alternatively, if the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include mobility historyavailscg as a new indicator in the RRC connection resume complete message and transmit (15-65) it to the base station when the NR base station 15-02 broadcasts an indicator indicating that SCG MHI is supported in the system information.

In step 15-70, the NR base station 15-02 can perform a UE information procedure when security is successfully activated. That is, the base station 15-02 may transmit (15-70) a UE information request message (ueinfo request) to the UE 15-01 to request conventional mobility history information or SCG MHI from the UE 15-01. The UE information request message may include a MobilityHistoryReportReq indicator.

Upon successful activation of security in step 15-75, the UE 15-01 may send (15-75) a UE information response message (ueinfo response) to the NR base station 15-02. If the mobilityHistoryReportReq is set to true in the received UE information request message, the UE may perform at least one of the following series of procedures.

If the VarMobilty HistolyReportSCG has a SCG MHI, the UE may include it in the Mobilty HistolyReportSCG. Alternatively, the UE may include the SCG MHI in the mobilityHistoryReportSCG when it exists in the varmobilityreportscg only when the NR base station 15-02 broadcasts an indicator indicating that the SCG MHI is supported in the system information.

The UE may perform the above procedure to include the mobilityHistoryReport and/or mobilityHistoryReport scg in the UE information response message and send it to the base station (15-75).

Fig. 16 is a view showing a UE operation in which a UE stores Secondary Cell Group (SCG) mobility history information (hereinafter, referred to as "SCG MHI") and reports it to a base station in an NR system according to an embodiment of the present disclosure.

Referring to fig. 16, nr base station 16-02 may broadcast system information (16-05). According to an embodiment of the present disclosure, it is proposed that the base station or NR cell 16-02 broadcast an indicator in the system information indicating that SCG MHI is supported. If an indicator is broadcast in the system information, UE 16-01 may store SCG MHI in VarMobility HistolyReport when changing PScell or when releasing PScell.

In step 16-10, UE 16-01 may be in RRC CONNECTED mode RRC_CONNECTED by establishing an RRC connection (16-10) with NR base station 16-02.

In step 16-13, UE 16-01 may send a UE capability information message (UECapabilityInformation) to NR base station 16-02 that includes an indicator that may store SCG MHI. It is proposed that a UE according to an embodiment of the present disclosure, when it has the capability to store SCG MHI, transmits a UE capability information message (UECapabilityInformation) including an indicator that can store SCG MHI to the NR base station. Alternatively, even if the UE according to the embodiment of the present disclosure has the capability of storing SCG MHI, as in the above-described embodiment, the UE may not notify the NR base station of the UE capability information message (UE capability information).

In step 16-15, the Master Node (MN) 16-02 may initiate a secondary node addition procedure to add the Secondary Node (SN) 16-03. The particular secondary node addition procedure may follow section TS 37.340 10.2. LTE or NR PSCell 1 16-03 may be added to UE 16-01 by step 16-15.

In step 16-20, for UE 16-01, LTE or NR PSCell 1-03 may be changed to LTE or NR PSCell 2 16-04 by a secondary node modification procedure or a secondary node change procedure. The particular secondary node modification procedure or secondary node change procedure may follow section TS 37.340 10.3 or section TS 37.340 10.5.

In step 16-25, UE 16-01 may store the SCG MHI of LTE or NR PScell 1 in VarMobilyHistolyReportSCG as a new variable. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReportSCG.

The operation is as follows:

In step 16-30, LTE or NR PScell 2 16-04 configured for UE 16-01 may be released by a secondary node release procedure. The particular secondary node release procedure or secondary node change procedure may follow section TS 37.340 10.4.

In step 16-35, UE 16-01 may store the SCG MHI of LTE or NR PScell 2 in the VarMobility History report. In particular, the UE may perform at least one of the following operations to store SCG MHI in VarMobilityHistoryReportSCG.

The operation is as follows:

when LTE or NR PSCell is released (release of LTE or NR PSCell 2), the oldest entry value is deleted, if necessary, and the following may be included in the entry of the VarMobilityHistoryReportSCG variable (possibly including an entry in the variable VarMobilityHistoryReportSCG after removal of the oldest entry, if necessary, according to the following)

In step 16-40, NR base station 16-02 can send an RRC connection release message to UE 16-01. If the RRC connection release message includes the suptendConfig information, the UE in the RRC connected mode may transition (16-45) to an RRC INACTIVE mode (RRC_INACTIVE). If the RRC connection release message does not include the supensConfig information, the UE in the RRC connected mode may transition (16-45) to an RRC IDLE mode (RRC_IDLE).

The RRC idle mode UE 16-01 can send (16-50) an RRC connection request message (RRCSetup request) to the base station to perform an RRC connection setup procedure with the NR base station 16-02. Upon receiving the RRC connection request message, the base station 16-02 may send (16-60) an RRC connection setup message (RRCSetup) to the UE 16-01 in response thereto. The UE receiving the RRC connection setup message may apply the RRC connection setup message and transition to the RRC connected mode (16-61). The RRC connected mode UE may then send an RRC connection setup complete message (rrcsetup complete) to the base station (16-65). If the UE supports storage of mobility history information in the above embodiment and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in an RRC connection setup complete message and transmit it to the base station (16-65). If the UE supports storage of SCG MHI and mobility history information is present in the VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in the VarMobilityHistoryReportSCG), the UE may include a mobilityavailscg indicator as a new indicator in an RRC connection setup complete message and send (16-65) it to the base station. Alternatively, if the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include mobility historyavailscg as a new indicator in the RRC connection setup complete message and send (16-65) to the base station when the NR base station 16-02 broadcasts an indicator in the system information indicating that SCG MHI is supported.

The RRC inactive mode UE 16-01 can send (16-50) an RRC connection resume request message (RRCResumeRequest) or an RRC connection resume request1 message (RRCResumeRequest 1) to the base station to perform an RRC connection resume procedure with the NR base station 16-02. Upon receiving the RRC connection resume request message, the base station 16-02 may send (16-60) an RRC connection resume message (RRCResume) to the UE 16-01 in response thereto. The UE receiving the RRC connection resume message may apply the RRC connection resume message and transition to the RRC connected mode (16-61). The RRC connected mode UE can then send (16-65) an RRC connection resume complete message (RRCRESumeCommple) to the base station. If the UE supports storage of mobility history information in the above embodiment and the mobility history information exists in VarMobilityHistoryReport (if the UE supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport), the UE may include a mobilityHistoryAvail indicator in an RRC connection restoration complete message and transmit it to the base station (16-65). If the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include a mobilityavailscg indicator as a new indicator in an RRC connection resume complete message and send (16-65) it to the base station. Alternatively, if the UE supports storage of SCG MHI and mobility history information exists in VarMobilityHistoryReportSCG (if the UE supports storage of SCG MHI and the UE has mobility history information available in VarMobilityHistoryReportSCG), the UE may include mobility historyavailscg as a new indicator in the RRC connection resume complete message and send (16-65) to the base station when the LTE base station 16-02 broadcasts an indicator in the system information indicating that SCG MHI is supported.

In step 16-70, NR base station 16-02 can perform a UE information procedure when security is successfully activated. That is, base station 16-02 may send (16-70) a UE information request message (ueinfo request) to UE16-01 to request conventional mobility history information or SCG MHI from UE 16-01. The UE information request message may include a MobilityHistoryReportReq indicator for reporting regular mobility history information and/or a new MobilityHistoryReportReqSCG indicator for reporting SCG MHI.

Upon successful activation of security in step 16-75, UE16-01 may send (16-75) a UE information response message (ueinfo response) to NR base station 16-02. If the mobilityHistoryReportReq is set to true in the received UE information request message, the UE may perform at least one of the following series of procedures.

If the VarMobilty HistolyReportSCG has a SCG MHI, the UE may include it in the Mobilty HistolyReportSCG. Alternatively, the UE may include the SCG MHI in the mobilityHistoryReportSCG when it exists in the varmobilityreportscg only when the NR base station 16-02 broadcasts an indicator in the system information indicating that the SCG MHI is supported.

The UE may perform the above procedure to include the mobilityHistoryReport and/or mobilityHistoryReport scg in the UE information response message and send it to the base station (16-75).

Fig. 17 is a view showing a UE operation in which the UE reports Secondary Cell Group (SCG) mobility history information (hereinafter "SCG MHI") to a base station in an NR system according to an embodiment of the present disclosure.

Referring to fig. 17, the nr base station 17-02 may broadcast system information (17-05). According to an embodiment of the present disclosure, it is proposed that the base station or NR cell 17-02 broadcast an indicator in the system information indicating that SCG MHI is supported. If an indicator is broadcast in the system information, the UE 17-01 may store SCG MHI in VarMobilityHistoryReport when changing PSCell or when releasing PSCell.

In step 17-10, the UE 17-01 may be in RRC CONNECTED mode RRC_CONNECTED by establishing an RRC connection (17-10) with the NR base station 17-02.

In step 17-13, the UE 17-01 may send a UE capability information message (UE capability information) to the NR base station 17-02 including an indicator that may store the SCG MHI. It is proposed that a UE according to an embodiment of the present disclosure, when it has the capability to store SCG MHI, transmits a UE capability information message (UECapabilityInformation) including an indicator that can store SCG MHI to the NR base station.

In step 17-15, the NR base station 17-02 can configure the UE 17-01 to report a mobilityHistory AvailSCG indicator or a mobilityHistory ReportSCG by using predetermined configuration information. For example, the predetermined configuration information may mean an otherConfig field.

In step 17-20, the UE 17-01 may include the mobilityHistoryAvailSCG indicator in a predetermined RRC message and may transmit it to the NR base station 17-02. The predetermined RRC message may mean, for example, one of an RRC connection restoration complete message (RRCnResumeComplete), an RRC connection reconfiguration complete message (rrcrecfigurationcomplete), and an RRC connection reestablishment complete message (rrcreestablishcomplete).

In step 17-25, the NR base station 17-02 may include the mobilityHistoryReportSCG in a UE information request message (UEInformationRequest) and transmit it to the UE 17-01.

In step 17-30, the UE 17-01 may include the mobilityHistoryReportSCG in a UE information response message (ueinfo response) and transmit it. In other words, in steps 17-25, if the mobilityHistoryReportReqSCG is set to true in the received UE information request message, the UE may perform at least one of the following series of procedures.

Alternatively, in step 17-35, the NR base station 17-02 can send a predetermined RRC message including the mobilityHistory ReportSCG to the UE 17-01. The predetermined RRC message may mean, for example, one of an RRC connection resume message (rrcreseume), an RRC connection reconfiguration message (rrcrecon configuration), and an RRC connection reestablishment message (rrcreestabliment).

In step 17-40, a predetermined RRC message including a mobilityHistoryReportSCG may be transmitted to the UE 17-01. The predetermined RRC message may mean, for example, one of an RRC connection restoration complete message (rrcrescentecompletion), an RRC connection reconfiguration complete message (rrcrescendo complete), and an RRC connection reestablishment complete message (rrcrescents complete). In other words, if the mobilityHistoryReportReqSCG is set to true in the RRC message received in steps 17-35, the UE may perform the above procedure to include the mobilityHistoryReportReq in the RRC message and transmit it in response to the RRC message received in steps 17-35.

In all the above embodiments, the MN may forward SCG MHI received from the UE to the SN. Alternatively, in all of the above embodiments, the UE may send the SCG MHI to the MN only if the SCG MHI is supported at both the MN and the SN.

Fig. 18 is a view showing UE operation in which a UE directly reports Secondary Cell Group (SCG) mobility history information (hereinafter "SCG MHI") to a Secondary Node (SN) in an NR system according to an embodiment of the present disclosure.

The UE 18-01 and the base stations 18-02 and 18-03 according to embodiments of the present disclosure may follow the operations of the above-described embodiments.

In step 18-05, the UE 18-01 may be in an RRC CONNECTED mode (RRC_CONNECTED) by establishing an RRC connection with the home node (MN) 18-02.

In step 18-10, MR-DC may be configured for the UE 18-01 and a Secondary Node (SN) 18-03 may be configured.

In step 18-15, SRB3 may be configured for UE 18-01, or a new SRB may be configured that is capable of sending RRC messages directly to the SN.

In step 18-20, when the UE 18-01 supports SCG MHI storage and the VarMobilityHistoryReportSCG has mobility history information, the UE 18-01 may send a predetermined RRC message including a mobilityHistoryReportSCG indicator to the SN 18-03 through SRB3 or a new SRB. For example, the predetermined RRC message may mean an RRC connection reconfiguration complete message or an uplink information transfer MRDC message. The operation of the UE in transmitting the RRC message may follow the above-described embodiments.

In step 18-25, the SN 18-03 can send a predetermined RRC message including mobilityHistolyReportSCGReq to the UE 18-01 over SRB3 or new SRB to recover SCG MHI from the UE 18-01. For example, the predetermined RRC message may mean an RRC connection reconfiguration message or a downlink information transfer MRDC message.

In step 18-30, the UE 18-01 can send a predetermined RRC message including mobilityHistory ReportSCG information to the SN 18-03 via SRB3 or a new SRB. For example, the predetermined RRC message may mean an RRC connection reconfiguration complete message or an uplink information transfer MRDC message. The operation of the UE in transmitting the RRC message may follow the above-described embodiments.

Fig. 19 is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present disclosure.

Referring to the figure, the UE includes a Radio Frequency (RF) processing unit 19-10, a baseband processing unit 19-20, a storage unit 19-30, and a controller 19-40.

The RF processing unit 19-10 performs functions for transmitting/receiving signals through a wireless channel, such as signal band conversion or amplification. In other words, the RF processing unit 19-10 up-converts the baseband signal supplied from the baseband processing unit 19-20 into an RF band signal, transmits it through the antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit 19-10 may include, for example, a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), and an analog-to-digital converter (ADC). In this figure, only one antenna is shown, but the UE may include multiple antennas. Furthermore, the RF processing unit 19-10 may comprise a plurality of RF chains. In addition, the RF processing unit 19-10 may perform beamforming. For beamforming, the RF processing unit 19-10 may adjust the phase and amplitude of each signal transmitted/received through multiple antennas or antenna elements. Further, the RF processing unit may perform MIMO and receive several layers when performing MIMO operation.

The baseband processing units 19-20 perform conversion functions between baseband signals and bit streams according to the system physical layer specifications. For example, at the time of data transmission, the baseband processing units 19-20 encode and modulate the transmission bit stream, thereby generating complex symbols. Further, at the time of data reception, the baseband processing unit 19-20 restores the received bit stream by demodulating and decoding the baseband signal supplied from the RF processing unit 19-10. For example, in the case of following an Orthogonal Frequency Division Multiplexing (OFDM) scheme, at the time of data transmission, the baseband processing units 19-20 may generate complex symbols by encoding and modulating a transmission bit stream, map the complex symbols to subcarriers, and then configure OFDM symbols through an Inverse Fast Fourier Transform (IFFT) operation and Cyclic Prefix (CP) insertion. Further, at the time of data reception, the baseband processing unit 19-20 divides the baseband signal supplied from the RF processing unit 19-10 into OFDM symbol units, restores the signal mapped to the subcarrier by Fast Fourier Transform (FFT), and then restores the reception bit stream by demodulation and decoding.

The baseband processing units 19-20 and the RF processing units 19-10 transmit and receive signals as described above. Accordingly, the baseband processing units 19-20 and the RF processing units 19-10 may be referred to as transmitters, receivers, transceivers, or communication units. Further, at least one of the baseband processing units 19-20 and the RF processing units 19-10 may include a plurality of communication modules for supporting a plurality of different radio access technologies. Further, at least one of the baseband processing units 19-20 and the RF processing units 19-10 may include different communication modules for processing signals of different frequency bands. For example, the different radio access technologies may include, for example, a wireless LAN (e.g., IEEE 802.11) or a cellular network (e.g., LTE). Further, the different frequency bands may include an ultra high frequency (SHF) (e.g., 2.NRHz or NRHz) frequency band or a millimeter wave (mmWave) (e.g., 60 GHz) frequency band.

The storage units 19-30 store basic programs, applications, configuration information, or other data for operating the UE. In particular, the storage unit 19-30 may store information related to the second access node performing wireless communication using the second radio access technology. In addition, the storage unit 19-30 provides the stored data upon request of the controller 19-40.

The controllers 19-40 control the overall operation of the UE. For example, the controller 19-40 transmits/receives signals through the baseband processing unit 19-20 and the RF processing unit 19-10. In addition, the controller 19-40 records data in the storage unit 19-30/reads data from the storage unit 19-30. To this end, the controllers 19-40 may include at least one processor. For example, the controllers 19 to 40 may include a Communication Processor (CP) that performs control to communicate and an Application Processor (AP) that controls upper layers such as an application program.

Fig. 20 is a block diagram showing a configuration of a base station according to an embodiment.

As shown, the base station may include an RF processing unit 20-10, a baseband processing unit 20-20, a backhaul communication unit 20-30, a storage unit 20-40, and a controller 20-50.

The RF processing unit 20-10 performs functions for transmitting/receiving signals through a wireless channel, such as signal band conversion or amplification. In other words, the RF processing unit 20-10 up-converts the baseband signal supplied from the baseband processing unit 20-20 into an RF band signal, transmits it through the antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing units 20-10 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC. In this figure, only one antenna is shown, but the first access node may comprise multiple antennas. In addition, the RF processing unit 20-10 may include a plurality of RF chains. In addition, the RF processing unit 20-10 may perform beamforming. For beamforming, the RF processing unit 20-10 may adjust the phase and amplitude of each signal transmitted/received through multiple antennas or antenna elements. The RF processing unit may perform downlink MIMO operation by transmitting one or more layers.

The baseband processing units 20-20 perform conversion functions between baseband signals and bit streams according to the physical layer specifications of the first radio access technology. For example, at the time of data transmission, the baseband processing units 20-20 encode and modulate the transmission bit stream, thereby generating complex symbols. Further, at the time of data reception, the baseband processing unit 20-20 restores the received bit stream by demodulating and decoding the baseband signal supplied from the RF processing unit 20-10. For example, in the case of following the OFDM scheme, at the time of data transmission, the baseband processing unit 20-20 may generate complex symbols by encoding and modulating a transmission bit stream, map the complex symbols to subcarriers, and then configure the OFDM symbols through IFFT operation and CP insertion. Further, at the time of data reception, the baseband processing unit 20-20 divides the baseband signal supplied from the RF processing unit 20-10 into OFDM symbol units, restores the signal mapped to the subcarrier by FFT, and then restores the reception bit stream by demodulation and decoding. The baseband processing unit 20-20 and the RF processing unit 20-10 transmit and receive signals as described above. Accordingly, the baseband processing units 20-20 and the RF processing units 20-10 may be referred to as transmitters, receivers, transceivers, communication units, or wireless communication units.

Backhaul communication units 20-30 provide interfaces for performing communications with other nodes in the network. In other words, the backhaul communication units 20 to 30 convert a bit stream transmitted from the primary base station to another node, such as a secondary base station or a core network, into a physical signal, and convert a physical signal received from the other node into a bit stream.

The memory units 20-40 store basic programs, applications, configuration information or other data for running the master base station. In particular, the storage unit 20-40 may store, for example, information about bearers allocated to the connected UE and the results of measurements reported from the connected UE. Further, the storage unit 20-40 may store information used as a reference for determining whether to provide a plurality of connections or stops to the UE. In addition, the storage units 20-40 provide the stored data upon request of the controllers 20-50.

The controllers 20-50 control the overall operation of the master base station. For example, the controller 20-50 transmits/receives signals through the baseband processing unit 20-20 and the RF processing unit 20-10 or through the backhaul communication unit 20-30. In addition, the controller 20-50 records data in the storage unit 20-30/reads data from the storage unit 19-30. To this end, the controllers 20-50 may include at least one processor.

Fig. 21 is a view showing a procedure in which a UE performs measurement logging according to out-of-coverage based on an event set by an NR base station and reports the logged measurement value to the NR base station according to an embodiment of the present disclosure.

Referring to fig. 21, the ue 21-01 may be in an RRC IDLE mode (rrc_idle) (21-05).

In step 21-10, the UE 21-01 may select a particular Public Land Mobile Network (PLMN) by performing a PLMN selection procedure. In the present disclosure, for convenience of description, a PLMN selected by the UE is referred to as PLMN 1.

In step 21-15, the UE 21-01 may select or reselect the appropriate NR cell belonging to the PLMN selected in step 21-10. The definition of a suitable NR cell may follow the 3gpp TS 38.304 standard. The UE camping on the appropriate NR cell is in a "camping state". In the present disclosure, for convenience of description, an appropriate NR cell selected or reselected by a UE may be referred to as NR cell 1.

In step 21-20, the UE 21-01 may perform an RRC connection establishment procedure with the appropriate NR cell 21-02 selected or reselected in step 21-10 to transition to the RRC connected mode. The UE may successfully perform the NAS registration procedure after the RRC connection establishment procedure of the suitable NR cell 21-02, and thus may register the PLMN selected by the UE in step 21-10 in the NR system. In other words, the PLMN selected by the UE in step 21-10 may become a Registered PLMN (RPLMN). Additionally, the RRC connected mode UE may receive the equivalent PLMN list through the NAS registration procedure and manage/store/use the equivalent PLMN list. The equivalent PLMN list may refer to a list of PLMNs that the UE may consider to be the same as the RPLMM during subsequent cell selection, cell reselection, and handover. In other words, the UE does not need to perform a separate NAS registration procedure when switching from a cell belonging to an equivalent PLMN list to a (re) selected cell or belonging to an equivalent PLMN list. For example, cells belonging to the equivalent PLMN list may be suitable NR cells.

In step 21-25, the UE 21-01 in RRC connected mode may receive a loggaedemeasurementconfiguration message from the NR cell 21-02. The information included in the message is as follows.

LoggedMeasurementconfiguration message

In the present disclosure, for convenience of description, the NR cell 21-02 may configure the loggaedemeasurementconfiguration message as follows and transmit the loggaedemeasurementconfiguration message to the UE 21-01 in the RRC connected mode.

● Setting the reportType to eventTriggered and the eventType of the logedevementtriggeredconfig to outOfCoverage

■ Thus, the UE may store the reportType received from NR cell 21-02 in varlog measconfig.

● Including or not plmn-IdentityList

■ If PLMN-IdentityList is included in the message, the UE may include and set the RPLMN and one or more Public Land Mobile Networks (PLMNs) received in the PLMN-IdentityList included in the message in the PLMN-IdentityList of VarLogMeasReport (if the LoggedMeasurementconfiguration message includes PLMN-IdentityList, the UE should set the PLMN-IdentityList in VarLogMeasReport to include the RPLMN and PLMNs included in the PLMN-IdentityList).

■ If plmn-IdentityList is not included in the message, the UE may include and set RPLMN in plmn-IdentityList of VarLogMeasReport (if the LoggedMeasurementconfiguration message does not include plmn-IdentityList, the UE should set plmn-IdentityList in VarLogMeasReport to include RPLMN).

● Including or excluding AreaConfiguration

■ If the area configuration is included in the message, the UE may perform measurement logging only in the area indicated by the area configuration.

■ If the AreaConfiguration is not included in the message, the UE may perform measurement logging if the RPLMN is included in the plmn-IdentityList stored in the VarLogMeasReport.

● Including the loggingDuration value

■ The UE may drive the T330 timer by setting the T330 timer value to the loggingDuration value.

In step 21-30, the UE 21-01 in RRC connected mode may be released from the RRC connection with the NR base station 21-02 so that the UE may transition to an RRC IDLE mode (rrc_idle) or an RRC INACTIVE mode (rrc_inactive). For example, the UE 21-01 in RRC connected mode may receive the RRCRelease message from the NR base station 21-02 and may transition to an RRC IDLE mode (rrc_idle) or an RRC INACTIVE mode (rrc_inactive).

In step 21-35, the UE 21-01 in RRC idle mode or RRC inactive mode may camp on the appropriate NR cell by performing a cell selection procedure or a cell reselection procedure. Suitable NR cells may be referred to as NR cells in steps 21-15 (NR cell 1) or new NR cells (NR cell 2).

In steps 21-40, a UE in RRC idle mode or RRC inactive mode may not camp on any cell because it may not find a suitable NR cell. The state where a UE in RRC idle mode or RRC inactive mode is not camping on any cell may be referred to as "any cell selection state". In other words, this may mean that the UE in RRC idle mode or RRC inactive mode is out of coverage.

In steps 21 to 45, if the T330 timer driven in steps 21 to 25 continues to run, the UE in the RRC idle mode or the RRC inactive mode may perform a recording operation according to the following conditions.

● Conditions are as follows: if the reportType is set to eventTriggered and the eventType is set to outOfCoverage

● Determining whether to perform recording: the UE may periodically record according to the loginginterval defined in varlog measconfig only when the condition is met and the UE in RRC idle mode or RRC inactive mode is in any cell selection state (recording is performed at regular time intervals as defined by the loginginterval in varlog measconfig only when the UE is in any cell selection state).

● Recording operation: when recording is performed in any cell selection state, the UE may record the following information.

■ An anycell selection detected is recorded to indicate that no cell has been found (an anycell selection detected is set to indicate that no suitable cell has been detected or that an acceptable cell has not been found).

■ When the following condition a is satisfied, the UE may record a global cell identity indicating a most recently camped cell (set servCellIdentity to indicate a global cell identity of a last cell in which the UE resides) and record a measurement result of the most recently camped cell into a measResultServingCell (set measResultServingCell to include the number of last cells in which the UE resides). The global cell identity consists of the first PLMN entry of PLMN-identity list in SIB1 broadcasted by the cell, the cell identity mapped thereto and the tracking area code to which the cell identity belongs. The measurement result of the cell may mean a cell measurement result (RSRP, RSRQ and/or SINR) based on SSB and an optimal SSB index, a beam measurement result (RSRP, RSRQ and/or SINR) of the optimal SSB, a number of SSB beams exceeding a threshold of absthreshold ss-blocksconsiodination (in SIB 2), etc. In accordance with the present disclosure, the most recently camped cell may refer to the appropriate NR cell 1 or the appropriate NR cell 2 selected or reselected by the UE in steps 21-35.

■ Condition a: when the reportType in VarLogMeasConfig is set to eventTriggered, and the plmn-IdentityList stored in VarLogMeasReport includes RPLMN when the UE enters any cell selection state, and the VarLogMeasConfig does not include an area configuration or the cell in which the UE recently resides belongs to an area indicated by the area in VarLogMeasConfig (if the reportType in VarLogMeasConfig is set to eventTriggered, and if the RPLMN at the time of entering any cell selection state is included in the plmn-IdentityList stored in VarLogMeasReport, and if the area Config is not included in VarMeasConfig or if the last cell in which the UE resides is part of the indicated area of the area in VarLogMeasConfig)

In steps 21-50, a UE in RRC idle mode or RRC inactive mode may not find a suitable NR cell in any cell selection state and may select or reselect an acceptable cell. The definition of acceptable cells may follow the 3gpp TS 38.304 standard. The UE may transition to RRC idle mode when the UE selects or reselects an acceptable cell in an inactive mode. The state in which a UE in RRC idle mode camps on an acceptable cell may be referred to as "camping on any cell state". The UE may be provided limited service through an acceptable cell. In other words, the UE may initiate an emergency call or may receive Earthquake and Tsunami Warning System (ETWS) or Commercial Mobile Alert System (CMAS) notifications. The acceptable cells may be NR cells or E-UTRA cells. In this disclosure, for ease of description, an acceptable cell may be referred to as cell 3.

In steps 21-55, the RRC idle mode UE may not camp on any cell, as it may not find a suitable cell or acceptable cell. In other words, this may mean that the RRC idle mode UE is out of coverage.

In steps 21-60, if the T330 timer driven in steps 21-25 continues to run, the UE in the RRC idle mode may perform recording according to the following conditions.

● Determining whether to perform recording: the UE may periodically record according to the loginginterval defined in varlog measconfig only when the condition is met and the UE in RRC idle mode is in any cell selection state (recording is performed at regular time intervals as defined by the loginginterval in varlog measconfig only when the UE is in any cell selection state).

● Recording operation: when the UE performs the recording in any cell selection state, the UE may record the following information.

An anycell selection detected is recorded to indicate that no cell has been found (an anycell selection detected is set to indicate that no suitable cell has been detected or that an acceptable cell has not been found).

When the above condition a is met or satisfied, the UE may record a global cell identity indicating a most recently camped cell (set servCellIdentity to indicate a global cell identity of a last cell in which the UE is camped) and record a measurement result of the most recently camped cell into a measResultServingCell (set measResultServingCell to include the number of last cells in which the UE is camped). The global cell identity consists of the first PLMN entry of PLMN-identity list in SIB1 broadcasted by the cell, the cell identity mapped thereto and the tracking area code to which the cell identity belongs. The measurement result of the cell may mean a cell measurement result (RSRP, RSRQ and/or SINR) based on SSB and an optimal SSB index, a beam measurement result (RSRP, RSRQ and/or SINR) of the optimal SSB, a number of SSB beams exceeding a threshold of absthreshold ss-blocksconsiodination (in SIB 2), etc. In accordance with the present disclosure, the most recently camped cell may refer to the acceptable cell (cell 3) selected or reselected by the UE in steps 21-50.

In step 21-61, the RRC idle mode UE 21-01 can select or reselect the appropriate NR cell 21-03. In this disclosure, for ease of description, a suitable NR cell 21-03 may be referred to as NR cell 4.

In step 21-65, the UE 21-01 in RRC idle mode may transition to RRC connected mode by performing an RRC connection establishment procedure with the appropriate NR cell21-03. In this case, a suitable NR cell21-03 may be an NR primary cell (PCell).

In step 21-70, the UE 21-01 that has transitioned to the RRC connected mode may send an RRCSetup complete message to the NR PCell21-03. If the UE has recorded measurements for the NR and the current RPLMN of the UE is included in the plmn-identity list stored in the VarLogMeasReport (if the UE has provided recorded measurements for the NR and if the RPLMN is included in the plmn-identity list stored in the VarLogMeasReport), the UE may include the logMeasAvailable in the rrcsetup complete message and send it to the NR PCell21-03.

In step 21-75, the RRC connected mode UE 21-01 and NR cell 4-03 can establish a DRB with SRB2 through an RRC reconfiguration procedure.

In step 21-80, the NR cell 4-03 can send a UEInformationRequest message to the RRC connected mode UE 21-01. The message may include logMeasReportReq.

In step 21-85, the RRC connected mode UE 21-01 may transmit a UEInformationResponse message including LogMeasReport to the NR cell 4-03 when the logMeasReportReq is present in the UEInformationRequest message received in step 21-80 and the current RPLMN of the UE is included in the plmn-identity list stored in the VarLogMeasReport.

The UE according to embodiments of the present disclosure has a problem of recording and reporting the global cell identity and measurement result values of acceptable cells to cells belonging to the RPLMN or equivalent PLMN list. Since PLMNs to which acceptable cells belong generally refer to commercial operators other than the commercial operators to which the UE subscribes, security issues may arise when the UE documents/records information about cells of the commercial operators to which the UE does not subscribe and reports them to the commercial operators to which the UE belongs.

Referring to fig. 22, the ue 22-01 may be in an RRC IDLE mode (rrc_idle) (22-05).

In step 22-10, the UE 22-01 may select a particular Public Land Mobile Network (PLMN) by performing a PLMN selection procedure. In the present disclosure, for convenience of description, a PLMN selected by the UE is referred to as PLMN 1.

In step 22-15, the UE 22-01 may select or reselect the appropriate NR cell belonging to the PLMN selected in step 22-10. The definition of a suitable NR cell may follow the 3gpp TS 38.304 standard. The UE camping on the appropriate NR cell is in a "camping state". In the present disclosure, for convenience of description, an appropriate NR cell selected or reselected by a UE may be referred to as NR cell 1.

In step 22-20, the UE 22-01 may perform an RRC connection establishment procedure with the appropriate NR cell 22-02 selected or reselected in step 22-10 to transition to RRC connected mode. The UE 22-01 may successfully perform the NAS registration procedure after the RRC connection establishment procedure of the suitable NR cell 22-02, and thus, the PLMN selected by the UE 22-01 in step 22-10 may be registered in the NR system. In other words, the PLMN selected by the UE 22-01 in step 22-10 may become a Registered PLMN (RPLMN). Additionally, the RRC connected mode UE may receive the equivalent PLMN list through the NAS registration procedure and manage/store/use the equivalent PLMN list. The equivalent PLMN list may refer to a list of PLMNs that the UE 22-01 may consider to be the same as the RPLMM during subsequent cell selection, cell reselection, and handover. In other words, the UE 22-01 does not need to perform a separate NAS registration procedure when switching from a cell belonging to an equivalent PLMN list to a (re) selected cell or belonging to an equivalent PLMN list. For example, cells belonging to the equivalent PLMN list may be suitable NR cells.

In step 22-25, the UE 22-01 in RRC connected mode may receive a loggaedemeasurementconfiguration message from the NR cell 22-02. The information included in the message is as follows.

LoggedMeasurementconfiguration message

In the present disclosure, for convenience of description, the NR cell 22-02 may configure the loggaedemeasurementconfiguration message as follows and transmit the loggaedemeasurementconfiguration message to the UE 22-01 in the RRC connected mode.

■ Thus, the UE 22-01 may store the reportType received from the NR cell 22-02 in the VarLogMeasConFIG.

● Including or not plmn-IdentityList

■ If PLMN-IdentityList is included in the message, the UE may include and set the RPLMN and one or more Public Land Mobile Networks (PLMNs) received in the PLMN-IdentityList included in the message in the plrLogMeasReport (if the LoggedMeasurementconfiguration message includes PLMN-IdentityList, the UE should set the PLMN-IdentityList to include the RPLMN and the PLMN included in the PLMN-IdentityList in the VarLogMeasReport).

● Including or excluding AreaConfiguration

● Including the loggingDuration value

In step 22-30, the UE22-01 in RRC connected mode may be released from the RRC connection with the NR base station 22-02 such that the UE22-01 may transition to an RRC IDLE mode (rrc_idle) or an RRC INACTIVE mode (rrc_inactive). For example, the UE22-01 in RRC connected mode may receive the RRCRelease message from the NR base station 22-02 and may transition to an RRC IDLE mode (rrc_idle) or an RRC INACTIVE mode (rrc_inactive).

In step 22-35, the UE22-01 that has transitioned to the RRC idle mode or RRC inactive mode may camp on the appropriate NR cell by performing a cell selection procedure or a cell reselection procedure. Suitable NR cells may be referred to as NR cells in steps 22-15 (NR cell 1) or new NR cells (NR cell 2).

In step 22-40, the UE 22-01 in RRC idle mode or RRC inactive mode may not camp on any cell because it may not find a suitable NR cell. The state in which the UE 22-01 in the RRC idle mode or the RRC inactive mode does not camp on any cell may be referred to as "any cell selection state". In other words, the UE 22-01 in the RRC idle mode or the RRC inactive mode in the "any cell selection state" may be in an out-of-coverage state.

In step 22-45, if the T330 timer driven in step 22-25 continues to run, the UE 22-01 in the RRC idle mode or the RRC inactive mode may perform a recording operation according to the following condition.

■ When the following condition a is satisfied, the present disclosure proposes that the UE record the global cell identity indicating the most recently camped suitable NR cell (set servCellIdentity to indicate the global cell identity of the last suitable cell in which the UE resides) and record the measurement result of the most recently camped suitable NR cell into the measResultServingCell (set measResultServingCell to include the number of last suitable cells in which the UE resides). The global cell identity consists of the first PLMN entry of PLMN-identity list in SIB1 broadcast by the appropriate NR cell, the cell identity mapped thereto and the tracking area code to which the cell identity belongs. The measurement result of the cell may mean a cell measurement result (RSRP, RSRQ and/or SINR) based on SSB and an optimal SSB index, a beam measurement result (RSRP, RSRQ and/or SINR) of the optimal SSB, a number of SSB beams exceeding a threshold of absthreshold ss-blocksconsiodination (in SIB 2), etc. Thus, the suitable NR cell that the UE has recently camped on may mean the suitable NR cell 1 or the suitable NR cell 2 selected or reselected by the UE in steps 22-35.

Condition a: when the reportType in VarLogMeasConfig is set to eventTriggered, and the plmn-IdentityList stored in VarLogMeasRecort includes RPLMN when the UE enters any cell selection state, and VarLogMeasConfiguration does not include an area indicated by the area of VarLogMeasConfig or the cell in which the UE recently resides belongs to (if the reportType in VarLogMeasConfig is set to eventTriggered, and if the RPLMN at the time of entering any cell selection state is included in the plmn-IdentityList stored in VarLogMeasRecort, and if the area of VarMegMeasConfiguration is not included or if the last cell in which the UE resides is an indicated by the area of VarLogMeasConfiguration

In step 22-50, the UE 22-01 in RRC idle mode or RRC inactive mode may not find a suitable NR cell in any cell selection state and may select or reselect an acceptable cell. The definition of acceptable cells may follow the 3gpp TS 38.304 standard. When the UE 22-01 selects or reselects an acceptable cell in the inactive mode, the UE may transition to the RRC idle mode. The state in which the RRC idle mode UE 22-01 camps on an acceptable cell may be referred to as "camping on any cell state". The UE 22-01 may be provided limited service through an acceptable cell. In other words, the UE 22-01 may initiate an emergency call or may receive Earthquake and Tsunami Warning System (ETWS) or Commercial Mobile Alert System (CMAS) notifications. The acceptable cells may be NR cells or E-UTRA cells. In this disclosure, for ease of description, an acceptable cell may be referred to as cell 3.

In step 22-55, the RRC idle mode UE 22-01 may not camp on any cell because it may not find a suitable cell or acceptable cell. In other words, this may mean that the RRC idle mode UE is out of coverage.

In steps 22-60, if the T330 timer driven in steps 22-25 continues to run, the UE in the RRC idle mode may perform recording according to the following conditions.

■ When the above condition a is met or satisfied, the present disclosure proposes that the UE record a global cell identity indicating the last suitable NR cell in which the UE resides (set servCellIdentity to indicate the global cell identity of the last suitable cell in which the UE resides) and record the measurement result of the last suitable NR cell in which the UE resides into a measResultServingCell (set measResultServingCell to include the number of last suitable cells in which the UE resides). The global cell identity consists of the first PLMN entry of PLMN-identity list in SIB1 broadcast by the appropriate NR cell, the cell identity mapped thereto and the tracking area code to which the cell identity belongs. The measurement result of the cell may mean a cell measurement result (RSRP, RSRQ and/or SINR) based on SSB and an optimal SSB index, a beam measurement result (RSRP, RSRQ and/or SINR) of the optimal SSB, a number of SSB beams exceeding a threshold of absthreshold ss-blocksconsiodination (in SIB 2), etc. Thus, the suitable NR cell in which the UE according to the present disclosure has recently camped may mean the suitable NR cell 1 or the suitable NR cell 2 selected or reselected by the UE in steps 22-35.

Alternatively, when the above condition a is met or satisfied, in the present disclosure, the UE may not record servCellIdentity and measresultserving cell when the last cell camped before entering any cell selection state in steps 22-55 is an acceptable cell. This is because the same servCellIdentity and measResultServingCell are not recorded when periodically recorded according to logginterval, so that the UE memory can be efficiently managed.

In step 22-61, the RRC idle mode UE 22-01 can select or reselect the appropriate NR cell22-03. In this disclosure, for ease of description, a suitable NR cell22-03 may be referred to as NR cell 4.

In step 22-65, the RRC idle mode UE 22-01 can transition to the RRC connected mode by performing an RRC connection setup procedure with the appropriate NR cell22-03. In this case, a suitable NR cell22-03 may be an NR primary cell (PCell).

In step 22-70, the UE 22-01 that has transitioned to the RRC connected mode may send an RRCSetup complete message to the NR PCell22-03. If the UE has recorded measurements for the NR and the current RPLMN of the UE is included in the plmn-identity list stored in the VarLogMeasReport (if the UE has provided recorded measurements for the NR and if the RPLMN is included in the plmn-identity list stored in the VarLogMeasReport), the UE may include the logMeasAvailable in the rrcsetup complete message and send it to the NR PCell22-03.

In step 22-75, the RRC connected mode UE 22-01 and NR cell 4-03 can establish a DRB with SRB2 through an RRC reconfiguration procedure.

In step 22-80, the NR cell 4-03 can send a UEInformationRequest message to the RRC connected mode UE 22-01. The message may include logMeasReportReq.

In step 22-85, the RRC connected mode UE 22-01 may send a UEInformationResponse message including LogMeasReport to the NR cell 4-03 when the logMeasReportReq is present in the UEInformationRequest message received in step 22-80 and the current RPLMN of the UE is included in the plmn-identity list stored in the VarLogMeasReport.

The UE according to embodiments of the present disclosure does not record the global cell identity and measurement result values of acceptable cells, but records the global cell identity and measurement result values of the appropriate NR cells and reports them to cells belonging to the RPLMN or equivalent PLMN list. Alternatively, when the last cell camped on before entering any cell selection state is an acceptable cell, the UE according to embodiments of the present disclosure does not record servCellIdentity and measResultServingCell.

Claims

1. A method of event-based logging by a UE in a wireless communication system, the method comprising:

identifying that the UE is in a radio resource control, RRC IDLE, state, RRC IDLE, or RRC INACTIVE state, RRC INACTIVE, and fails to find a suitable cell and acceptable cell;

identifying that a registered public land mobile network, RPLMN, is included in a PLMN ID list when the UE fails to find the suitable cell and the acceptable cell;

Recording a serving cell ID indicating a global cell ID of a suitable cell in which the UE recently resides; and

and recording the measurement result of the proper cell where the UE recently resides.

2. The event-based recording method according to claim 1, wherein in the RRC idle state or the RRC inactive state, a report type reportType is included in a measurement record configuration varlog measconfig of the UE, and

wherein the report type is set to "eventTriggered".

3. The event based recording method according to claim 2, wherein the area configuration is not included in the measurement record configuration varlog measconfiguration.

4. The event-based recording method according to claim 2, wherein an area configuration is included in the measurement record configuration varlog measconfig, and

wherein the suitable cell in which the UE has recently camped is part of an area indicated by information in the area configuration.

5. The event-based recording method according to claim 1, the method further comprising: configuration information loggaddeasurementconfiguration for a measurement record performed by the UE in the RRC idle state or the RRC inactive state is received from a base station.

6. The event-based recording method according to claim 1, wherein the suitable cell is a cell in which the UE can camp.

7. The event based recording method of claim 6, wherein the suitable cell is a cell belonging to the RPLMN.

8. The event based recording method of claim 6, wherein the acceptable cell is a cell providing limited service to the UE.

9. The event-based recording method of claim 8, wherein the acceptable cell is selected when the UE fails to find the suitable cell in the RRC idle state or the RRC inactive state.

10. A UE that performs event-based logging in a wireless communication system, the UE comprising:

a transceiver; and

a processor configured to:

11. The UE of claim 10, wherein in the RRC idle state or the RRC inactive state, a report type reportType is included in a measurement log configuration varlog measconfig of the UE, and

wherein the report type is set to "eventTriggered".

12. The UE of claim 11, wherein an area configuration is not included in the measurement log configuration varlog measconfiguration.

13. The UE of claim 11, wherein an area configuration is included in the measurement log configuration varlog measconfiguration, and

14. The UE of claim 10, wherein the processor is configured to: control is performed to receive configuration information loggaedemeasurementconfiguration on measurement records performed by the UE in the RRC idle state or the RRC inactive state from a base station.

15. The UE of claim 10, wherein the suitable cell is a cell that belongs to the RPLMN and in which the UE may camp, and

wherein the acceptable cell is a cell providing limited service to the UE.