Method and apparatus for storing pscell mobility history information in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. An operation method of a user equipment (UE) in a wireless communication system, according to an embodiment of the present disclosure, may comprise the steps of: if changing a suitable Cell, entering any cell selection state from a camped normally state, or entering any cell selection state from a suitable cell in a radio resource control (RRC) connected state, generating an entry comprising information related to a previous PCell in a previously visited cell list of information for reporting a mobility history; if the UE supports storage of mobility history information about a primary secondary cell (PSCell) and a PSCell is not configured when entering any cell selection state from the suitable cell in the RRC connected state, generating an entry comprising information about the time at which a PSCell was not present in a previously visited PSCell list of the information for reporting the mobility history; and transmitting, to a base station, a message comprising the information for reporting the mobility history.

Description

Method and device for storing PSCELL movement history information in a wireless communication system

[0001] The present disclosure relates to a wireless communication system. Specifically, the present disclosure relates to a method and apparatus for storing PSCell movement history information in a wireless communication system.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in frequency bands below 6 GHz ('Sub 6 GHz'), such as 3.5 gigahertz (3.5 GHz), but also in ultra-high frequency bands called millimeter waves (mmWave), such as 28 GHz and 39 GHz ('Above 6 GHz'). In addition, for 6G mobile communication technology, which is referred to as a system beyond 5G, implementation in the terahertz (THX) band (e.g., the 3 terahertz band at 95 GHz) is being considered to achieve transmission speeds 50 times faster and ultra-low latency reduced to one-tenth compared to 5G mobile communication technology.

[0003] In the early stages of 5G mobile communication technology, aiming to satisfy service support and performance requirements for enhanced Mobile BroadBand (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), technologies such as beamforming and Massive MIMO to mitigate path loss and increase transmission distance in ultra-high frequency bands, support for various numerologies (such as the operation of multiple subcarrier spacings) and dynamic operation of slot formats for the efficient utilization of ultra-high frequency resources, initial access techniques to support multi-beam transmission and broadband, definition and operation of Band-Width Parts (BWP), Low Density Parity Check (LDPC) codes for high-volume data transmission, new channel coding methods such as Polar Codes for the reliable transmission of control information, and L2 pre-processing (L2 Standardization has been carried out for pre-processing, network slicing which provides a dedicated network specialized for specific services, and other methods.

[0004] Currently, discussions are underway to improve and enhance the performance of the initial 5G mobile communication technology, taking into account the services that the 5G mobile communication technology was intended to support. Additionally, standardization of the physical layer is in progress for technologies such as V2X (Vehicle-to-Everything), which helps autonomous vehicles make driving decisions and enhance user convenience based on their own location and status information transmitted by the vehicle; NR-U (New Radio Unlicensed), which aims for system operation in unlicensed bands to comply with various regulatory requirements; NR terminal low power consumption technology (UE Power Saving); Non-Terrestrial Network (NTN), which is direct terminal-satellite communication for securing coverage in areas where communication with the terrestrial network is impossible; and positioning.

[0005] In addition, standardization is underway in the field of wireless interface architecture / protocols for technologies such as the Industrial Internet of Things (IIoT) for supporting new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) which provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement including Conditional Handover and Dual Active Protocol Stack (DAPS) Handover, and 2-step Random Access (2-step RACH for NR) which simplifies random access procedures. Standardization is also underway in the field of system architecture / services for 5G baseline architectures (e.g., Service based Architecture, Service based Interface) for incorporating Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC), which provides services based on the location of the terminal.

[0006] When such 5G mobile communication systems are commercialized, connected devices, which are increasing explosively, will be connected to communication networks. Accordingly, it is expected that there will be a need to enhance the functionality and performance of 5G mobile communication systems and to integrate the operation of connected devices. To this end, new research is planned to be conducted on 5G performance improvement and complexity reduction, support for AI services, support for metaverse services, and drone communication using eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] Furthermore, the advancement of these 5G mobile communication systems encompasses multi-antenna transmission technologies such as new waveforms to guarantee coverage in the terahertz band of 6G mobile communication technology, Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas; metamaterial-based lenses and antennas to improve terahertz band signal coverage; high-dimensional spatial multiplexing technology using OAM (Orbital Angular Momentum); and Reconfigurable Intelligent Surface (RIS) technology; as well as Full Duplex technology for enhancing frequency efficiency and system networks in 6G mobile communication technology; AI-based communication technologies that realize system optimization by utilizing satellites and AI from the design stage and internalizing end-to-end AI support functions; and the realization of services of complexity exceeding the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources. It could serve as a foundation for the development of next-generation distributed computing technologies.

[0008] The present disclosure provides a method and apparatus for storing PSCell movement history information in a wireless communication system.

[0009] A method of operation of user equipment (UE) in a wireless communication system according to one embodiment of the present disclosure may include: a step of creating an entry containing information related to a previous PCell in a previously visited cell list of information for reporting mobility history when the UE changes a suitable cell, enters an any cell selection state from a camped normally state, or enters an any cell selection state from a suitable cell in a radio resource control (RRC) connected state; a step of creating an entry containing information about a time when the PScell ​​did not exist in a previously visited PScell ​​list of information for reporting mobility history when the UE supports the storage of mobility history information for a primary secondary cell (PSCell) and when the PSCell was not set when entering the any cell selection state from a suitable cell in an RRC connected state; and a step of transmitting a message containing information for reporting mobility history to a base station.

[0010] According to one embodiment of the present disclosure, a method and apparatus for storing PSCell movement history information in a wireless communication system can be provided.

[0011] FIG. 1a is a drawing illustrating the structure of an LTE system according to one embodiment of the present disclosure.

[0012] FIG. 1b is a diagram illustrating a wireless protocol structure in an LTE system according to one embodiment of the present disclosure.

[0013] FIG. 1c is a drawing illustrating the structure of a next-generation mobile communication system according to one embodiment of the present disclosure.

[0014] FIG. 1d is a diagram showing the wireless protocol structure of a next-generation mobile communication system according to one embodiment of the present disclosure.

[0015] Figure 1e is a flowchart of the process in which a terminal reports mobility history information to a base station in a next-generation mobile communication system.

[0016] FIG. 1f is a diagram illustrating a terminal operation in a next-generation mobile communication system according to one embodiment of the present disclosure, in which the terminal stores mobility history information for a PSCell and reports it to a base station.

[0017] FIG. 1g is a diagram illustrating a terminal operation in a next-generation mobile communication system according to one embodiment of the present disclosure, in which the terminal stores mobility history information for a PSCell and reports it to a base station.

[0018] FIG. 1h is a diagram illustrating a terminal operation in a next-generation mobile communication system according to an embodiment of the present disclosure, wherein the terminal stores mobility history information for a PSCell and reports it to a base station.

[0019] FIG. 1i is a diagram illustrating a terminal operation in a next-generation mobile communication system according to one embodiment of the present disclosure, in which the terminal stores mobility history information for a PSCell and reports it to a base station.

[0020] FIG. 1j is a diagram illustrating a terminal operation in a next-generation mobile communication system according to one embodiment of the present disclosure, in which the terminal stores mobility history information for a PSCell and reports it to a base station.

[0021] FIG. 1k is a block diagram illustrating the internal structure of a terminal according to one embodiment of the present disclosure.

[0022] FIG. 11 is a block diagram showing the configuration of an NR base station according to one embodiment of the present disclosure.

[0023] A method of operation of user equipment (UE) in a wireless communication system according to one embodiment of the present disclosure may include: a step of creating an entry containing information related to a previous PCell in a previously visited cell list of information for reporting mobility history when the UE changes a suitable cell, enters an any cell selection state from a camped normally state, or enters an any cell selection state from a suitable cell in a radio resource control (RRC) connected state; a step of creating an entry containing information about a time when the PScell ​​did not exist in a previously visited PScell ​​list of information for reporting mobility history when the UE supports the storage of mobility history information for a primary secondary cell (PSCell) and when the PSCell was not set when entering the any cell selection state from a suitable cell in an RRC connected state; and a step of transmitting a message containing information for reporting mobility history to a base station.

[0024] User equipment (UE) of a wireless communication system according to one embodiment of the present disclosure comprises: at least one transceiver; and at least one processor communicatively coupled to the at least one transceiver. and includes at least one memory that is communicately coupled to the at least one processor and stores instructions, wherein the instructions are executed by the at least one processor individually or in any combination, and when the UE changes a suitable cell, enters any cell selection state from a camped normally state, or enters any cell selection state from a suitable cell in an RRC (radio resource control) connected state, creates an entry containing information related to the previous PCell in the previously visited cell list of information for reporting mobility history, supports the storage of mobility history information for a PSCell (primary secondary cell), and when the UE enters any cell selection state from a suitable cell in an RRC connected state and the PSCell is not set, creates an entry containing information about the time when the PScell ​​was not present in the previously visited PScell ​​list of information for reporting mobility history, and the mobility It is possible to transmit a message containing information for reporting the history to the base station.

[0025] The operating principles of the present disclosure will be described in detail below with reference to the attached drawings. In describing the present disclosure below, specific descriptions of related known functions or configurations will be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present disclosure. Furthermore, the terms described below are defined in consideration of their functions in the present disclosure, and these may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0026] For the same reason, some components in the attached drawings have been exaggerated, omitted, or schematically depicted. Additionally, the dimensions of each component do not entirely reflect their actual dimensions. Identical or corresponding components in each drawing have been assigned the same reference numbers.

[0027] The advantages and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms, and the embodiments are provided merely to make the present disclosure complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims.

[0028] At this point, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing instruction means to perform the function described in the flow diagram block(s). Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that perform a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer can also provide steps for executing the functions described in the flowchart block(s).

[0029] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specific logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For example, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order according to their corresponding functions.

[0030] In this embodiment, the term "part" refers to a software or hardware component such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the "part" performs certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or may be configured to run one or more processors. Accordingly, as an example, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and "parts" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts." In addition, the components and '~parts' may be implemented to utilize one or more CPUs within the device or secure multimedia card. Also, in the embodiment, the '~part' may include one or more processors.

[0031] Terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc., are examples provided for the convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

[0032] For convenience of explanation, the present disclosure uses terms and names defined in the 3GPP LTE (3rd Generation Partnership Project Long Term Evolution) standard. However, the present disclosure is not limited to the above terms and names and may be applied equally to systems conforming to other standards. In the present disclosure, eNB may be used interchangeably with gNB for convenience of explanation. That is, a base station described as an eNB may represent a gNB.

[0033] Hereinafter, the base station is an entity that performs resource allocation for terminals and may be at least one of a gNode B, eNode B, Node B, BS (Base Station), wireless access unit, base station controller, or a node on a network. The terminal may include a UE (User Equipment), MS (Mobile Station), cellular phone, smartphone, computer, or a multimedia system capable of performing communication functions. Of course, it is not limited to the above examples.

[0034] Wireless communication systems are evolving from providing early voice-oriented services to broadband wireless communication systems that provide high-speed, high-quality packet data services, such as communication standards like 3GPP’s HSPA (High Speed ​​Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2’s HRPD (High Rate Packet Data), UMB (Ultra Mobile Broadband), and IEEE’s 802.16e.

[0035] As a representative example of a broadband wireless communication system, the LTE system employs the Orthogonal Frequency Division Multiplexing (OFDM) method for the downlink (DL) and the Single Carrier Frequency Division Multiple Access (SC-FDMA) method for the uplink (UL). The uplink refers to a wireless link through which a terminal (or UE) transmits data or control signals to a base station (or eNB, gNB), and the downlink refers to a wireless link through which a base station transmits data or control signals to a terminal. The above multiple access method distinguishes the data or control information of each user by allocating and operating time-frequency resources to be transmitted for each user so that they do not overlap, that is, so that orthogonality is established.

[0036] As a future communication system following LTE, 5G communication systems must be able to freely reflect the diverse requirements of users and service providers, and therefore, services that satisfy various requirements simultaneously must be supported. Services being considered for 5G communication systems include enhanced mobile broadband communication (eMBB), massive machine-based communication (mMTC), and ultra-reliable low-latency communication (URLLC).

[0037] According to one embodiment, eMBB may aim to provide a data transmission speed that is higher than the data transmission speed supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB must be able to provide a peak data rate of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink from the perspective of a single base station. In addition, the 5G communication system may need to provide a user-perceived data rate while simultaneously providing the peak data rate. To satisfy these requirements, the 5G communication system may require improvements in various transmission and reception technologies, including enhanced Multiple Input Multiple Output (MIMO) transmission technology. Furthermore, while current LTE transmits signals using a maximum transmission bandwidth of 20 MHz in the 2 GHz band, the 5G communication system can satisfy the data transmission speed required by the 5G communication system by using a frequency bandwidth wider than 20 MHz in frequency bands of 3 to 6 GHz or above 6 GHz.

[0038] Simultaneously, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. To efficiently provide IoT services, mMTC may require support for a large number of terminal connections within a cell, improved terminal coverage, enhanced battery life, and reduced terminal costs. Since IoT devices are attached to various sensors and equipment to provide communication functions, a cell must be capable of supporting a large number of terminals (e.g., 1,000,000 terminals / km²). Furthermore, due to the nature of the service, terminals supporting mMTC are likely to be located in dead zones not covered by cells, such as building basements; therefore, wider coverage may be required compared to other services provided by 5G communication systems. Terminals supporting mMTC must consist of low-cost devices, and since it is difficult to frequently replace terminal batteries, a very long battery life of 10 to 15 years may be required.

[0039] Finally, URLLC is a mission-critical cellular-based wireless communication service that can be used for services such as remote control of robots or machinery, industrial automation, unmanned aerial vehicles, remote health care, and emergency alerts. Therefore, the communication provided by URLLC may need to offer very low latency and very high reliability. For example, services supporting URLLC must satisfy an air interface latency of less than 0.5 milliseconds and may simultaneously require a packet error rate of 10^-5 or less. Consequently, for services supporting URLLC, 5G systems must provide a Transmission Time Interval (TTI) smaller than other services, and design considerations may be required to allocate wide resources in the frequency band to ensure the reliability of the communication link.

[0040] The three services considered in the aforementioned 5G communication system, namely eMBB, URLLC, and mMTC, can be multiplexed and transmitted within a single system. In this case, different transmission and reception techniques and parameters may be used between the services to satisfy the different requirements of each service. However, the aforementioned mMTC, URLLC, and eMBB are merely examples of different service types, and the service types to which the present disclosure applies are not limited to the examples mentioned above.

[0041] In addition, although embodiments of the present disclosure are described below using LTE, LTE-A, LTE Pro, or 5G (or NR, next-generation mobile communication) systems as examples, embodiments of the present disclosure may be applied to other communication systems having similar technical backgrounds or channel types. Furthermore, embodiments of the present disclosure may be applied to other communication systems with some modifications made at the discretion of a person with skilled technical knowledge, without significantly departing from the scope of the present disclosure.

[0042] In describing the present disclosure below, specific descriptions of related known functions or configurations will be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the present disclosure. Embodiments of the present disclosure will be described below with reference to the attached drawings.

[0043] FIG. 1a is a diagram illustrating the structure of an LTE system according to one embodiment of the present invention.

[0044] Referring to FIG. 1a, as illustrated, the wireless access network of the LTE system consists of a next-generation base station (Evolved Node B, hereinafter ENB, Node B or base station) (1a-05, 1a-10, 1a-15, 1a-20), an MME (1a-25, Mobility Management Entity), and an S-GW (1a-30, Serving-Gateway). A user terminal (User Equipment, hereinafter UE or terminal) (1a-35) connects to an external network through the ENB (1a-05 ~ 1a-20) and the S-GW (1a-30).

[0045] In FIG. 1a, the ENBs (1a-05 to 1a-20) correspond to the existing Node B of the UMTS (Universal Mobile Telecommunication System) system. The ENBs are connected to the UEs (1a-35) via a wireless channel and perform more complex roles than the existing Node B. In LTE systems, since all user traffic, including real-time services such as VoIP (Voice over IP) via the Internet Protocol, is serviced through a shared channel, a device is required to aggregate status information such as the buffer status, available transmission power status, and channel status of the UEs to perform scheduling; this role is handled by the ENBs (1a-05 to 1a-20). A single ENB generally controls multiple cells. For example, to achieve a transmission speed of 100 Mbps, the LTE system uses Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology, for instance, in a 20 MHz bandwidth. In addition, an Adaptive Modulation & Coding (hereinafter referred to as AMC) method is applied to determine the modulation scheme and channel coding rate according to the channel conditions of the terminal. The S-GW (1a-30) is a device that provides data bearers and creates or removes data bearers under the control of the MME (1a-25). The MME is a device that is responsible for various control functions as well as mobility management functions for the terminal and is connected to multiple base stations.

[0046] FIG. 1b is a diagram illustrating a wireless protocol structure in an LTE system according to one embodiment of the present invention.

[0047] Referring to Fig. 1b, the wireless protocol of the LTE system consists of PDCP (Packet Data Convergence Protocol 1b-05, 1b-40), RLC (Radio Link Control 1b-10, 1b-35), and MAC (Medium Access Control 1b-15, 1b-30) at the terminal and ENB, respectively. PDCP (Packet Data Convergence Protocol) (1b-05, 1b-40) is responsible for operations such as IP header compression / decompression. The main functions of PDCP are summarized as follows.

[0048] - Header compression and decompression (ROHC (robust header compression) only)

[0049] - User data transfer function (Transfer of user data)

[0050] - In-sequence delivery of upper layer PDUs (protocol data units) at PDCP re-establishment procedure for RLC AM (acknowledged mode))

[0051] - Order reordering function (For split bearers in DC (only support for RLC AM): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

[0052] - Duplicate detection function (Duplicate detection of lower layer SDUs (service data units) at PDCP re-establishment procedure for RLC AM)

[0053] - Retransmission function (Retransmission of PDCP SDUs at handover and, for split bearers in DC, of ​​PDCP PDUs at PDCP data-recovery procedure, for RLC AM)

[0054] - Encryption and decryption functions (Ciphering and deciphering)

[0055] - Timer-based SDU discard in uplink.

[0056] Wireless Link Control (RLC) (1b-10, 1b-35) reconstructs PDCP Protocol Data Units (PDUs) into appropriate sizes to perform automatic repeat request (ARQ) operations, etc. The main functions of RLC are summarized as follows.

[0057] - Data transfer function (Transfer of upper layer PDUs)

[0058] - ARQ function (Error Correction through ARQ (only for AM data transfer))

[0059] - Concatenation, segmentation, and reassembly functions (Concatenation, segmentation, and reassembly of RLC SDUs (only for UM (unacknowledged mode) and AM data transfer))

[0060] - Re-segmentation function (Re-segmentation of RLC data PDUs (only for AM data transfer))

[0061] - Reordering function (Reordering of RLC data PDUs (only for UM and AM data transfer)

[0062] - Duplicate detection function (only for UM and AM data transfer)

[0063] - Error detection function (Protocol error detection (only for AM data transfer))

[0064] - RLC SDU deletion function (RLC SDU discard (only for UM and AM data transfer))

[0065] RLC re-establishment function

[0066] MAC (1b-15, 1b-30) is connected to multiple RLC layer devices configured in a terminal and performs the operation of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of MAC are summarized as follows.

[0067] - Mapping function (Mapping between logical channels and transport channels)

[0068] - Multiplexing and demultiplexing function (Multiplexing / demultiplexing of MAC SDUs belonging to one or different logical channels into / from transport blocks (TB) delivered to / from the physical layer on transport channels)

[0069] - Scheduling information reporting function

[0070] - HARQ (hybrid automatic repeat request) function (Error correction through HARQ)

[0071] - Priority handling between logical channels of one UE

[0072] - Priority handling between UEs by means of dynamic scheduling

[0073] - MBMS (Multimedia Broadcast / Multicast Service) service identification function (MBMS service identification)

[0074] - Transport format selection function

[0075] - Padding

[0076] The physical layer (1b-20, 1b-25) performs the operation of channel coding and modulating upper layer data, creating OFDM symbols and transmitting them to the wireless channel, or demodulating OFDM symbols received through the wireless channel and channel decoding them to transmit them to the upper layer.

[0077] FIG. 1c is a diagram illustrating the structure of a next-generation mobile communication system according to one embodiment of the present invention.

[0078] Referring to FIG. 1c, as illustrated, the wireless access network of a next-generation mobile communication system (hereinafter NR or 2g) consists of a next-generation base station (New Radio Node B, NR gNB or NR base station) (1c-10) and an NR CN (1c-05, New Radio Core Network). A user terminal (New Radio User Equipment, hereinafter NR UE or terminal) (1c-15) connects to an external network through the NR gNB (1c-10) and the NR CN (1c-05).

[0079] In FIG. 1c, the NR gNB (1c-10) corresponds to the eNB (Evolved Node B) of the existing LTE system. The NR gNB is connected to the NR UE (1c-15) via a wireless channel and can provide superior service compared to the existing Node B. In the next-generation mobile communication system, since all user traffic is serviced through a shared channel, a device is required to collect status information such as the buffer status, available transmission power status, and channel status of the UEs and perform scheduling, and this is handled by the NR gNB (1c-10). A single NR gNB (1c-10) typically controls multiple cells. To achieve ultra-high-speed data transmission compared to LTE, the NR gNB (1c-10) can have a bandwidth greater than the existing maximum bandwidth, and can additionally incorporate beamforming technology by using Orthogonal Frequency Division Multiplexing (hereinafter referred to as OFDM) as the wireless access technology. In addition, an Adaptive Modulation & Coding (hereinafter referred to as AMC) scheme can be applied to determine the modulation scheme and channel coding rate according to the channel conditions of the terminal.

[0080] The NR CN (1c-05) performs functions such as mobility support, bearer configuration, and QoS (quality of service) configuration. The NR CN is a device responsible for various control functions as well as mobility management functions for terminals, and is connected to multiple base stations. In addition, the next-generation mobile communication system can be interoperable with existing LTE systems, and the NR CN is connected to the MME (1c-25) via a network interface. The MME is connected to the existing base station, eNB (1c-30).

[0081] FIG. 1d is a diagram showing the wireless protocol structure of a next-generation mobile communication system according to one embodiment of the present invention.

[0082] FIG. 1d is a diagram showing the wireless protocol structure of a next-generation mobile communication system to which the present invention can be applied.

[0083] Referring to Fig. 1d, the wireless protocol of the next-generation mobile communication system consists of NR SDAP (service data adaptation protocol) (1d-01, 1d-45), NR PDCP (1d-05, 1d-40), NR RLC (1d-10, 1d-35), and NR MAC (1d-15, 1d-30) at the terminal and the NR base station, respectively.

[0084] The main functions of NR SDAP(1d-01, 1d-45) may include some of the following functions.

[0085] - User data transfer function (transfer of user plane data)

[0086] - Mapping function between a QoS flow and a DRB (data radio bearer) for both DL and UL for uplink and downlink

[0087] - Marking QoS flow ID in both DL and UL packets for uplink and downlink

[0088] - Function to map reflective QoS flow to data bearers for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

[0089] Regarding the above SDAP layer device, the terminal may receive a radio resource control (RRC) message indicating whether to use the header of the SDAP layer device or the functions of the SDAP layer device for each PDCP layer device, bearer, or logical channel. If the SDAP header is configured, the terminal may be instructed to update or reset the mapping information for the uplink and downlink QoS flows and data bearers using the 1-bit NAS (non-access stratum) QoS reflective QoS indicator and the 1-bit AS QoS reflective QoS indicator of the SDAP header. The above SDAP header may include QoS flow ID information indicating QoS. The above QoS information may be used for data processing priority, scheduling information, etc., to support smooth service.

[0090] The main functions of NR PDCP (1d-05, 1d-40) may include some of the following functions.

[0091] Header compression and decompression (ROHC only)

[0092] - User data transfer function (Transfer of user data)

[0093] - Sequential delivery function (In-sequence delivery of upper layer PDUs)

[0094] - Out-of-sequence delivery of upper layer PDUs

[0095] - Reordering function (PDCP PDU reordering for reception)

[0096] - Duplicate detection function (Duplicate detection of lower layer SDUs)

[0097] - Retransmission of PDCP SDUs

[0098] - Encryption and decryption functions (Ciphering and deciphering)

[0099] - Timer-based SDU discard in uplink.

[0100] In the above, the reordering function of the NR PDCP device refers to a function of reordering PDCP PDUs received from a lower layer in order based on the PDCP SN (sequence number), and may include a function of transmitting data to an upper layer in the reordered order, or a function of transmitting immediately without considering the order, may include a function of recording lost PDCP PDUs by reordering, may include a function of reporting the status of lost PDCP PDUs to the transmitting side, and may include a function of requesting retransmission of lost PDCP PDUs.

[0101] The main functions of NR RLC(1d-10, 1d-35) may include some of the following functions.

[0102] - Data transfer function (Transfer of upper layer PDUs)

[0103] - Sequential delivery function (In-sequence delivery of upper layer PDUs)

[0104] - Out-of-sequence delivery of upper layer PDUs

[0105] - ARQ function (Error Correction through ARQ)

[0106] - Concatenation, segmentation, and reassembly functions of RLC SDUs

[0107] - Re-segmentation function (Re-segmentation of RLC data PDUs)

[0108] - Reordering function (Reordering of RLC data PDUs)

[0109] - Duplicate detection

[0110] - Error detection function (Protocol error detection)

[0111] - RLC SDU discard function

[0112] RLC re-establishment function

[0113] In the above, the in-sequence delivery function of the NR RLC device refers to the function of delivering RLC SDUs received from a lower layer to an upper layer in sequence; it may include a function to reassemble and deliver them if a single RLC SDU is received divided into multiple RLC SDUs; it may include a function to rearrange received RLC PDUs based on an RLC SN (sequence number) or PDCP SN (sequence number); it may include a function to record lost RLC PDUs after rearranging the order; it may include a function to report the status of lost RLC PDUs to the transmitting side; it may include a function to request retransmission of lost RLC PDUs; if there are lost RLC SDUs, it may include a function to deliver only the RLC SDUs prior to the lost RLC SDU to the upper layer in sequence; or if a predetermined timer has expired even if there are lost RLC SDUs, it may include a function to deliver all RLC SDUs received before the timer started to the upper layer in sequence; or It may include a function that delivers all RLC SDUs received up to the present to the upper layer in order once a predetermined timer has expired, even if there are lost RLC SDUs. Additionally, the RLC PDUs mentioned above may be processed in the order they are received (regardless of the order of sequence numbers, but in the order of arrival) and delivered to the PDCP device out of order (out-of-sequence delivery). In the case of segments, segments stored in a buffer or to be received later may be received, reconstructed into a single complete RLC PDU, processed, and then delivered to the PDCP device.The above NR RLC layer may not include a concatenation function, and the function may be performed in the NR MAC layer or replaced with the multiplexing function of the NR MAC layer.

[0114] In the above, the out-of-sequence delivery function of the NR RLC device refers to a function of delivering RLC SDUs received from a lower layer directly to an upper layer regardless of order. It may include a function of reassembling and delivering them when a single RLC SDU is received divided into multiple RLC SDUs, and may include a function of storing the RLC SN or PDCP SN of the received RLC PDUs and sorting the order to record the lost RLC PDUs.

[0115] The NR MAC (1d-15, 1d-30) can be connected to multiple NR RLC layer devices configured in a terminal, and the main functions of the NR MAC may include some of the following functions.

[0116] - Mapping function (Mapping between logical channels and transport channels)

[0117] - Multiplexing and demultiplexing functions (Multiplexing / demultiplexing of MAC SDUs)

[0118] - Scheduling information reporting function

[0119] - HARQ function (Error correction through HARQ)

[0120] - Priority handling between logical channels of one UE

[0121] - Priority handling between UEs by means of dynamic scheduling

[0122] - MBMS service identification function

[0123] - Transport format selection function

[0124] - Padding

[0125] The NR PHY layer (1d-20, 1d-25) can perform the operation of channel coding and modulating upper layer data, creating OFDM symbols and transmitting them to the wireless channel, or demodulating OFDM symbols received through the wireless channel and channel decoding them to transmit them to the upper layer.

[0126] Figure 1e is a flowchart of the process in which a terminal reports mobility history information to a base station in a next-generation mobile communication system.

[0127] Referring to FIG. 1e, the terminal (1e-01) may be in RRC idle mode (RRC_IDLE) or RRC disabled mode (RRC_INACTIVE) (1e-10).

[0128] An RRC idle mode terminal (1e-01) can transmit an RRC connection request message (RRCSetupRequest) to a base station (1e-02) (1e-10) to perform an RRC connection setup procedure with the base station (1e-02). Upon receiving the RRC connection request message, the base station (1e-02) can transmit an RRC connection setup message (RRCSetup) to the terminal (1e-01) in response (1e-15). Upon receiving the RRC connection setup message, the terminal (1e-01) can apply it and transition to an RRC connection mode (1e-16). Then, the RRC connection mode terminal (1e-01) can transmit an RRC connection setup completion message (RRCSetupComplete) to the base station (1e-02) (1e-20). If the terminal (1e-01) supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport, the terminal (1e-01) can include the mobilityHistoryAvail indicator in the RRC connection setup completion message and transmit it to the base station (1e-02) (1e-20).

[0129] An RRC disabled mode terminal (1e-01) can transmit an RRC connection resumption request message (RRCResumeRequest or RRCResumeRequest1) to the base station (1e-02) (1e-10) to perform an RRC connection resumption procedure with the base station (1e-02). Upon receiving the RRC connection resumption request message, the base station (1e-02) can transmit an RRC connection resumption message (RRCResume) to the terminal (1e-01) in response (1e-15). Upon receiving the RRC connection resumption message, the terminal (1e-01) can apply it and transition to an RRC connection mode (1e-16). Then, the RRC connection mode terminal (1e-01) can transmit an RRC connection resumption completion message (RRCResumeComplete) to the base station (1e-02) (1e-20). If the terminal (1e-01) supports storage of mobility history information and the UE has mobility history information available in VarMobilityHistoryReport, the terminal (1e-01) can include the mobilityHistoryAvail indicator in the RRC connection resumption completion message and transmit it to the base station (1e-02) (1e-20).

[0130] A terminal (1e-01) that has not set up security settings can perform an initial security activation procedure with a base station (1e-02) (1e-21). For example, a terminal (1e-01) that has not set up security settings may refer to a terminal (1e-01) that has switched from RRC idle mode to RRC connection mode. Specifically, the terminal (1e-01) can send a security mode command message (SecurityModeCommand) to the base station (1e-02), and in response to this, the base station (1e-02) can send a security mode completion message (SecurityModeComplete) to the terminal (1e-01).

[0131] In order to perform the RRC connection reconfiguration procedure in step 1e-25, the base station (1e-02) may transmit an RRC connection reconfiguration message (RRCReconfiguration) to the RRC connection mode terminal (1e-01). The terminal (1e-01) may apply the received RRC connection reconfiguration message and, in response, transmit an RRC connection reconfiguration completion message (RRCReconfigurationComplete) to the base station (1e-02) (1e-30).

[0132] In step 1e-35, the base station (1e-02) may perform a terminal information procedure (UE information procedure) if security activation is successfully performed. The base station (1e-02) may transmit a terminal information request message (UEInformationRequest) to the terminal (1e-35) to request mobility history information from the terminal (1e-01). The terminal information request message may include a MobilityHistoryReportReq indicator.

[0133] A terminal (1e-01) that has successfully performed security activation in step 1e-40 can transmit a terminal information response message (UEInformationResponse) (1e-40) to a base station (1e-02). If mobilityHistoryReportReq is set to true in the received terminal information request message, the terminal can perform the following series of procedures.

[0134] - Information from VarMobilityHistoryReport can be included in mobilityHistoryReport (include themobilityHistoryReport and set it to include entries fromVarMobilityHistoryReport)

[0135] - If necessary, you can delete the oldest information and include information about the current cell in the mobilityHistoryReport as follows (include in themobilityHistoryReportan entry for the current cell, possibly after removing the oldest entry if required, set its fields as follows)

[0136] - You can set the global cell identifier of the current cell to visitedCellId (setvisitedCellIdto the global cell identity of the current cell)

[0137] - You can set the time spent in the current cell in the timeSpent field (set fieldtimeSpent to the time spent in the current cell)

[0138] The terminal (1e-01) can perform the above procedure and include the mobilityHistoryReport in the terminal information response message and transmit it to the base station (1e-40).

[0139] A terminal according to the next-generation mobile communication system has the following characteristics in storing mobility history information and reporting it to the base station.

[0140] - The terminal does not notify the base station of whether it supports saving mobility history information by sending a separate UECapabilityInformation message. Instead, the terminal supports saving mobility history information and sends the mobilityHistoryAvail indicator as an RRC connection establishment complete message or an RRC connection resumption complete message only if mobility history information is present in the VarMobilityHistoryReport.

[0141] - The terminal does not store mobility history information about the PSCells it has connected to or stayed on.

[0142] - The terminal stores only the list of cell information spent in RRC idle mode or RRC disabled mode and the time spent in each cell, as well as the list of cell information spent in RRC connected mode and the time spent in each cell, in the mobility history information and reports it to the base station.

[0143] FIG. 1f is a diagram illustrating a terminal operation in a next-generation mobile communication system according to one embodiment of the present disclosure, in which the terminal stores mobility history information for a PSCell and reports it to a base station.

[0144] Referring to FIG. 1f, the terminal (1f-01) can enter the RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with the base station (1f-02) (1f-10). The base station (1f-02) may be referred to as PCell 1 or Master Node (MN) base station. For reference, PCell 1 is a suitable cell.

[0145] In step 1f-15, the terminal (1f-01) may transmit a terminal capability information message (UECapabilityInformation) to PCell 1 (1f-02). If the terminal (1f-01) according to one embodiment of the present disclosure has the capability to store PSCell mobility history information and report it to the base station as a terminal information response message (UEInformationResponse), it may transmit a terminal capability information message including a pscell-MHI-Report indicator to PCell 1 (1f-02). The terminal (1f-01) according to one embodiment of the present disclosure may support the storage of the mobility history information of the above-described embodiment. For reference, the description of pscell-MHI-Report is as follows.

[0146]

[0147] In step 1f-20, the Master Node (MN) (1f-02) may initiate a Secondary Node Addition procedure to add a Secondary Node (SN) (1f-04) to the terminal (1f-01). In this disclosure, the SN base station may be referred to as PSCell 1 (1f-04). A specific Secondary Node Addition procedure may follow Section 10.2 of TS 37.340. That is, PSCell 1 (1f-04) may be added to the terminal (1f-01) through step 1f-20.

[0148] In step 1f-25, the terminal (1f-01) supports PSCell mobility history information and, upon addition of a PSCell 1 (1f-04), can perform the following operations.

[0149]

[0150] That is, the terminal (1f-01) can store information about the time when there was no PSCell after entering RRC connection mode for PCell 1 (1f-02) in the terminal variable VarMobilityHistoryReport.

[0151] In step 1f-30, PSCell 1 (1f-04) configured for the terminal (1f-01) can be changed to PSCell 2 (1f-05) through the Secondary Node Change procedure. The specific Secondary Node Change procedure may follow Section 10.5 of TS 37.340.

[0152] In step 1f-35, the terminal (1f-01) supports PSCell mobility history information and, when PSCell 1 (1f-04) is changed to PSCell 2 (1f-05) while remaining connected to the current PCell 1 (1f-02), the following operation may be performed.

[0153]

[0154] That is, the terminal (1f-01) can store information about the cell ID (global cell identity or physical cell identity and carrier frequency) for PSCell 1 (1f-04) and the time it was connected to PSCell 1 (1f-04) in the terminal variable VarMobilityHistoryReport.

[0155] In step 1f-40, PSCell 2 (1f-05) configured on the terminal (1f-01) can be released through the Secondary Node Release procedure. The specific Secondary Node Release procedure may follow Section 10.4 of TS 37.340.

[0156] In step 1f-45, the terminal (1f-01) can perform the operation performed in step 1f-30 when the UE supports PSCell mobility history information and upon release of a PSCell while being connected to the current PCell 1 (1f-02). That is, the terminal (1f-01) can store information about the cell ID (global cell identity or physical cell identity and carrier frequency) for PSCell 2 (1f-05) and the time it was connected to PSCell 2 (1f-05) in the terminal variable VarMobilityHistoryReport.

[0157] In step 1f-50, the terminal (1f-01) in RRC connection mode can transition to RRC idle mode (RRC_IDLE) or RRC inactive mode (RRC_INACTIVE) and perform a cell selection process. If the terminal (1f-01) cannot find a suitable cell, it can find a suitable cell according to the stored cell selection information. If the terminal (1f-01) continues not to find a suitable cell, it can perform an initial cell selection process. The specific cell selection process may follow Section 5.2.3 of TS 38.304, and the definition of a suitable cell may follow Section 4.5 of TS 38.304.

[0158] In step 1f-55, a terminal (1f-01) in RRC idle mode or RRC disabled mode may enter the Any Cell Selection state because it cannot find a suitable cell. For reference, a terminal (1f-01) in the Any Cell Selection state does not camp-on to any cell, so it can first find a suitable cell through the cell selection process, and if that fails, find an acceptable cell. The definition of an acceptable cell may follow Section 4.5 of TS 38.304.

[0159] In step 1f-60, when the terminal (1f-01) enters the Any Cell Selection State (when entering 'any cell selection' state from a suitable cell in RRC_CONNECTED state in NR or LTE), it can store mobility history information as follows.

[0160]

[0161]

[0162] A terminal (1f-01) according to the present disclosure has the feature of storing movement history information as follows.

[0163] - If there is a global cell identity for PCell 1 (1f-02) (if the global cell identity of the previous PCell / serving cell is available), the terminal (1f-01) can store information about the global cell identity for PCell 1 (1f-02) in the terminal variable VarMobilityHistoryReport. It can also store the time spent at PCell 1 (1f-02).

[0164] - If steps 1f-20 through 1f-45 are not performed and step 1f-50 is performed, the terminal (1f-01) may not store information about the time spent with no PSCell since entering the current or previous PCell in RRC_CONEECTED in the terminal variable VarMobilityHistoryReport.

[0165] - If steps 1f-20 through 1f-45 are performed and step 1f-50 is performed, the terminal (1f-01) may perform at least one of the following.

[0166] -- The movement history information for PSCell 2 (1f-05) saved in step 1f-45 can be included in the movement history information for PCell 1 (include visitedPSCellInfoList in VarMobilityHistoryReport in the visitedPSCellInfoListReport within the entry of the visitedCellInfoList associated to the latest PCell entry) and stored in the terminal variable VarMobilityHistoryReport.

[0167] -- The time information for PCell 1 (1f-02) after PSCell 2 was released, when PSCell 2 (1f-05) was not present (the time spent with no PSCell since last PSCell release since entering the previous PCell in RRC_CONNECTED, for example, the time from step 1f-40 to step 1f-55) may not be stored in the terminal variable VarMobilityHistoryReport.

[0168] That is, the terminal (1f-01) has the characteristic of not storing information in the terminal variable VarMobilityHistoryReport during the time when there was no PSCell after entering the RRC connection mode with PCell 1 (1f-02). Therefore, since the base station does not have information about the time when there was no PSCell associated with the cell identifier for PCell 1 (1f-02), it cannot determine whether the terminal (1f-01) did not enter the RRC connection mode (i.e., the Serving cell in RRC_IDLE or RRC_INACTIVE) and thus did not store information about the time when there was no PSCell, or whether the terminal entered the RRC connection mode but failed to store information about the time when there was no PSCell.

[0169] In step 1f-65, the terminal (1f-01) finds a suitable cell (1f-02) and camps on

[0170] It can be selected. At this time, the terminal (1f-01) can enter the Camped Normally state.

[0171] In step 1f-70, the terminal (1f-01) is Camped in any cell selection state.

[0172] When entering the Normally state, movement history information can be saved as follows.

[0173]

[0174] In step 1f-75, the terminal (1f-01) can enter RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with the Serving cell / PCell (1f-02).

[0175] In step 1f-80, the terminal (1f-01) may receive a terminal information request message (UEInformationRequest) from PCell 1 (1f-02). In the message, mobilityHistoryReportReq may be set to true.

[0176] In step 1f-85, the terminal (1f-01) can transmit a terminal information response message (UEInformationResponse) to PCell 1 (1f-02). That is, if mobilityHistoryReportReq included in the terminal information request message received in step 1f-50 is set to true, the terminal (1f-01) can perform the following operations.

[0177]

[0178] A terminal (1f-01) according to a next-generation mobile communication system has the following characteristics in storing mobility history information and reporting it to a base station.

[0179] - The terminal (1f-01) has the characteristic of not storing information in the terminal variable VarMobilityHistoryReport during the time when there was no PSCell after entering RRC connection mode with PCell 1 (1f-02). Therefore, when the base station retrieves mobility history information for PCell 1 (1f-02) from the terminal (1f-01), it has cell identifier information for PCell 1 (1f-02) and information on the time spent in PCell 1 (1f-02), but not information on the time when there was no PSCell for PCell 1 (1f-02). Thus, it cannot determine whether the terminal (1f-01) did not enter RRC connection mode and therefore did not store information on the time when there was no PSCell in the mobility history information for PCell 1 (1f-02), or whether the terminal (1f-01) entered RRC connection mode but omitted storing information on the time when there was no PSCell in the mobility history information for PCell 1 (1f-02).

[0180] FIG. 1g is a diagram illustrating a terminal operation in a next-generation mobile communication system according to one embodiment of the present disclosure, in which the terminal stores mobility history information for a PSCell and reports it to a base station.

[0181] Referring to FIG. 1g, the terminal (1g-01) can enter the RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with the base station (1g-02) (1g-10). The base station (1g-02) may be referred to as PCell 1 or Master Node (MN) base station. For reference, PCell 1 (1g-02) is a suitable cell.

[0182] In step 1g-15, the terminal (1g-01) may transmit a terminal capability information message (UECapabilityInformation) to PCell 1 (1g-02). This may follow the previously described embodiment (Fig. 1f). Additionally, the message may include the following information.

[0183] - pscell-MHI-ReportAnyCellSelection: The ability to store time information regarding the time without a PSCell since entering the RRC_CONNECTED state (or since entering the current PCell in RRC_CONNECTED) when entering any cell selection state from a suitable cell in NR or LTE RRC connection mode without being connected to a PSCell (if the UE supports PSCell mobility history information and upon entering 'any cell selection state' from a suitable cell in RRC_CONNECTED state NR or LTE while not connected to a PSCell).

[0184] For reference, pscell-MGI-ReportAnyCellSelection may be supported only by terminals capable of PSCell mobility history information. A terminal (1g-01) may support pscell-MGI-ReportAnyCellSelection starting from a specific specification number or specification release without sending a terminal capability information message to the base station regarding whether it supports pscell-MGI-ReportAnyCellSelection. Alternatively, a terminal (1g-01) capable of PSCell mobility history information may support the aforementioned pscell-MGI-ReportAnyCellSelection capability starting from a specific specification number or specification release.

[0185] In step 1g-20, the Master Node (MN) (1g-02) may initiate a Secondary Node Addition procedure to add a Secondary Node (SN) (1g-04) to the terminal (1g-01). In this disclosure, the SN base station (1g-04) may be referred to as PSCell 1 (1g-04). The specific Secondary Node Addition procedure may follow Section 10.2 of TS 37.340. That is, PSCell 1 (1g-04) may be added to the terminal (1g-01) through step 1g-20.

[0186] In step 1g-25, the terminal (1g-01) supports PSCell mobility history information, and when the PSCell 1 (1g-04) is added (if the UE supports PSCell mobility history information and upon addition of a PSCell), the mobility history information can be stored in the terminal variable VarMobilityHistoryReport according to the aforementioned embodiment (1f).

[0187] In step 1g-30, PSCell 1 (1g-04) set for the terminal (1g-01) can be changed to PSCell 2 (1g-05) through the Secondary Node Change procedure. The specific Secondary Node Change procedure may follow Section 10.5 of TS 37.340.

[0188] In step 1g-35, when the UE (1g-01) supports PSCell mobility history information and is continuously connected to the current PCell 1 (1g-02), and the PSCell 1 (1g-04) is changed to PSCell 2 (1g-05), the mobility history information can be stored in the terminal variable VarMobilityHistoryReport according to the above embodiment (Fig. 1f).

[0189] In step 1g-40, PSCell 2 (1g-05) configured on the terminal (1g-01) can be released through the Secondary Node Release procedure. The specific Secondary Node Release procedure may follow Section 10.4 of TS 37.340.

[0190] In step 1g-45, when the terminal (1g-01) supports PSCell mobility history information and is released from a PSCell 2 (1g-05) while still connected to the current PCell 1 (1g-02), the mobility history information can be stored in the terminal variable VarMobilityHistoryReport according to the aforementioned embodiment (Fig. 1f).

[0191] In step 1g-50, the terminal (1g-01) in RRC connection mode can transition to RRC idle mode (RRC_IDLE) or RRC inactive mode (RRC_INACTIVE) and perform a cell selection process. If the terminal (1g-01) cannot find a suitable cell, it can find a suitable cell according to the stored cell selection information. If the terminal (1g-01) continues not to find a suitable cell, it can perform an initial cell selection process. The specific cell selection process may follow Section 5.2.3 of TS 38.304, and the definition of a suitable cell may follow Section 4.5 of TS 38.304.

[0192] In step 1g-55, a terminal (1g-01) in RRC idle mode or RRC disabled mode may enter the Any Cell Selection state because it cannot find a suitable cell. For reference, a terminal (1g-01) in the Any Cell Selection state does not camp-on to any cell, so it can first find a suitable cell through the cell selection process, and if that fails, find an acceptable cell. The definition of an acceptable cell may follow Section 4.5 of TS 38.304.

[0193] In step 1g-60, when the terminal (1g-01) enters the Any Cell Selection State (when entering 'any cell selection' state from a suitable cell in RRC_CONNECTED state in NR or LTE), mobility history information can be stored in the terminal variable VarMobilityHistoryReport according to the aforementioned embodiment (Fig. 1f). Additionally, the terminal (1g-01) according to the present disclosure proposes storing the following information in the terminal variable VarMobilityHistoryReport.

[0194] - If step 1g-50 is performed without step 1g-20 or step 1g-45 being performed, the terminal (1g-01) can store information about the time spent with no PSCell since entering the current or previous PCell in RRC_CONEECTED after entering connection mode with PCell 1 (1g-02) in the terminal variable VarMobilityHistoryReport.

[0195] - If steps 1f-20 through 1f-45 are performed and step 1f-50 is performed, the terminal (1g-01) can store information about the time when PSCell 2 (1g-05) was not present in PCell 1 (1g-02) after PSCell 2 (1g-05) was released (the time spent with no PSCell since last PSCell release since entering the previous PCell in RRC_CONNECTED, for example, the time from step 1f-40 to step 1f-55) in the terminal variable VarMobilityHistoryReport.

[0196] For example, terminal operation may be as follows.

[0197]

[0198]

[0199]

[0200] A terminal (1g-01) according to the present disclosure has the feature of storing movement history information as follows.

[0201] - If the global cell identity for PCell 1 (1g-02) is available (if the global cell identity of the previous PCell / serving cell is available), the terminal (1g-01) can store information about the global cell identity for PCell 1 (1g-02) in the terminal variable VarMobilityHistoryReport. Otherwise, information about the physical cell identity and carrier frequency for PCell 1 (1g-02) can be stored in the terminal variable VarMobilityHistoryReport. Additionally, the time spent at PCell 1 (1g-02) can be stored.

[0202] - If step 1g-50 is executed instead of step 1g-45 from step 1g-20, the terminal (1g-01) can store information about the time spent with no PSCell since entering the current or previous PCell in RRC_CONEECTED after entering connection mode with PCell 1 (1g-02) in the terminal variable VarMobilityHistoryReport. That is, mobility history information for PCell 1 (1g-02) and information about the time spent without a PSCell in PCell 1 (1g-02) can be stored in the terminal variable VarMobilityHistoryReport.

[0203] - If steps 1g-20 through 1g-45 are executed and step 1g-50 is executed, the terminal (1g-01) can store information regarding the time when PSCell 2 (1g-05) was not present in PCell 1 (1g-02) after PSCell 2 (1g-05) was released (the time spent with no PSCell since the last PSCell release since entering the previous PCell in RRC_CONNECTED, for example, the time from step 1g-40 to step 1g-55) in the terminal variable VarMobilityHistoryReport. That is, mobility history information for PCell 1 (1g-02) and information regarding the time when there was no PSCell in PCell 1 (1g-02) can be stored in the terminal variable VarMobilityHistoryReport.

[0204] In step 1g-65, the terminal (1g-01) can find a suitable cell (1g-02) and camp on. At this time, the terminal (1g-01) can enter the Camped Normally state.

[0205] In step 1g-70, when the terminal (1g-01) enters the Camped Normally state from the Any cell selection state, it can store mobility history information as in the previously described embodiment (Fig. 1e).

[0206] In step 1g-75, the terminal (1g-01) can enter RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with the Serving cell / PCell (1g-02).

[0207] In step 1g-80, the terminal (1g-01) can receive a terminal information request message (UEInformationRequest) from PCell 1 (1g-02). In the message, mobilityHistoryReportReq can be set to true.

[0208] In step 1g-85, the terminal (1g-01) can transmit a terminal information response message (UEInformationResponse) to PCell 1 (1g-02). That is, if mobilityHistoryReportReq included in the terminal information request message received in step 1g-80 is set to true, the terminal (1g-01) can perform the following operations.

[0209]

[0210] A terminal (1g-01) according to a next-generation mobile communication system has the following characteristics in storing mobility history information and reporting it to a base station.

[0211] - The terminal (1g-01) has the characteristic of storing information in the terminal variable VarMobilityHistoryReport during the time when there was no PSCell after the terminal (1g-01) entered the RRC connection mode with PCell 1 (1g-02). Therefore, when the base station retrieves this, it can determine the information regarding the time when there was no PSCell in PCell 1 (1g-02) after the terminal (1g-01) entered the RRC connection mode with PCell 1 (1g-02).

[0212] FIG. 1h is a diagram illustrating a terminal operation in a next-generation mobile communication system according to one embodiment of the present disclosure, in which the terminal stores mobility history information for a PSCell and reports it to a base station.

[0213] Referring to FIG. 1h, the terminal (1h-01) can enter the RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with the base station (1h-02) (1h-10). The base station may be referred to as PCell 1 or Master Node (MN) base station. For reference, PCell 1 (1h-02) is a suitable cell.

[0214] In step 1h-15, the terminal (1h-01) may transmit a terminal capability information message (UECapabilityInformation) to PCell 1 (1h-02). This may follow at least one of the previously described embodiments (Figs. 1f, Fig. 1g). Additionally, the message may include the following capability information.

[0215] - pscell-MHI-ReportCampedNormallyState: The ability to store and report to the base station the cell identifier for the PSCell (global cell identity or physical cell identity and carrier frequency) and information on the time the PSCell was connected (time spent in the PSCell while being connected to the PCell) when the terminal (1h-01) transitions from having both the PCell and PSCell configured (i.e., Dual Connectivity, hereinafter DC configured) to the Camped Normally state.

[0216] -- DC may mean at least one of EN-DC, (NG)EN-DC, NE-DC, and NR-DC.

[0217] For reference, pscell-MGI-ReportCampedNormallyState (support of PSCell mobility history information upon entering camped normally state) may be supported only by a terminal (1h-01) capable of PSCell mobility history information. The terminal (1h-01) may support pscell-MGI-ReportCampedNormallyState starting from a specific specification number or specification release without sending a terminal capability information message to the base station regarding support status. Alternatively, a terminal capable of PSCell mobility history information may support the aforementioned pscell-MGI-ReportCampedNormallyState capability starting from a specific specification number or specification release.

[0218] In step 1h-20, the Master Node (MN) (1h-02) may initiate a Secondary Node Addition procedure to add a Secondary Node (SN) (1h-04) to the terminal (1h-01). In this disclosure, the SN base station (1h-04) may be referred to as PSCell 1. A specific Secondary Node Addition procedure may follow Section 10.2 of TS 37.340. That is, PSCell 1 (1h-04) may be added to the terminal (1h-01) through step 1h-20.

[0219] In step 1h-25, the terminal (1h-01) supports PSCell mobility history information and, upon addition of a PSCell 1 (1h-04), the mobility history information can be stored in the terminal variable VarMobilityHistoryReport according to the aforementioned embodiment (Fig. 1f).

[0220] In step 1h-30, the terminal (1h-01) can transition to RRC idle mode (RRC_IDLE) or RRC inactive mode (RRC_INACTIVE) and perform a cell selection process.

[0221] In step 1h-35, the terminal (1h-01) can find a suitable cell and enter the Camped Normally state.

[0222] In step 1h-40, if the terminal (1h-01) is in at least one DC among EN-DC, (NG)EN-DC, NE-DC, and NR-DC and transitions to the camped normally state, it may perform the following operation.

[0223] - The cell identifier (global cell identity or physical cell identity and carrier frequency) for PCell 1 (1h-02) and the time spent in PCell 1 (1h-02) (time sepnt in the previous PCell / serving cell) can be stored in the terminal variable VarMobilityHistoryReport.

[0224] - The cell identifier (global cell identity or physical cell identity and carrier frequency) for PSCell 1 (1h-04) and the time spent at PSCell 1 (1h-04) while connected to PCell 1 (1h-02) can be stored in the terminal variable VarMobilityReport.

[0225] For example, terminal operation can be represented by the following series of operations.

[0226]

[0227]

[0228]

[0229] In step 1h-45, the terminal (1h-01) can enter RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with the cell (1h-02) selected in step 1h-40.

[0230] In step 1h-50, the terminal (1h-01) may receive a terminal information request message (UEInformationRequest) from PCell 1 (1h-02). In the message, mobilityHistoryReportReq may be set to true.

[0231] In step 1h-55, the terminal (1h-01) can transmit a terminal information response message (UEInformationResponse) to PCell 1 (1h-02). That is, if mobilityHistoryReportReq included in the terminal information request message received in step 1h-50 is set to true, the terminal (1h-01) can report mobility history information through the terminal information response message according to the above-described embodiment (1f).

[0232] A terminal (1h-01) according to a next-generation mobile communication system has the following characteristics in storing mobility history information and reporting it to a base station.

[0233] - The terminal (1h-01) can enter RRC connection mode with PCell 1 (1h-02), then set up PSCell 1 (1h-04) and operate as a DC, and then exit RRC connection mode. When entering the Camped Normally state through the cell selection process in RRC idle mode or RRC disabled mode, the mobility history information for PCell 1 (1h-02) (cell identifier for PCell 1 and time spent in PCell 1) and the mobility history information for PSCell 1 (1h-04) (cell identifier for PSCell 1 and time spent in PSCell 1 while connected to PCell 1) are stored in the terminal variable VarMobilityHistoryReport. Therefore, when the base station retrieves it, the terminal (1h-01) enters the RRC connection mode to PCell 1 (1h-02), and then the base station can identify the mobility history information for PCell 1 (1h-02) and the mobility history information for PSCell 1 (1h-04).

[0234] FIG. 1i is a diagram illustrating a terminal operation in a next-generation mobile communication system according to one embodiment of the present disclosure, in which the terminal stores mobility history information for a PSCell and reports it to a base station.

[0235] Referring to FIG. 1i, the terminal (1i-01) can enter the RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with the base station (1i-02) (1i-10). The base station (1i-02) may be referred to as PCell 1 or Master Node (MN) base station. For reference, PCell 1 (1i-02) is a suitable cell.

[0236] In step 1i-15, the terminal (1i-01) may transmit a terminal capability information message (UECapabilityInformation) to PCell 1 (1i-02). This may follow at least one of the previously described embodiments (Fig. 1f, Fig. 1g). Additionally, the message may include the following capability information.

[0237] - pscell-MHI-ReportAnyCellSelectionOrCampedNormallyState: The ability to store and report to the base station the cell identifier for the PSCell (global cell identity or physical cell identity and carrier frequency) and information on the time the PSCell was connected (time spent in the PSCell while being connected to the PCell) when the terminal (1i-01) transitions from having both the PCell and PSCell configured (i.e., Dual Connectivity, hereinafter DC configured) to the Camped Normally state or the Any Cell Selection state.

[0238] -- DC may mean at least one of EN-DC, (NG)EN-DC, NE-DC, and NR-DC.

[0239] For reference, pscell-MHI-ReportAnyCellSelectionOrCampedNormallyState (support of PSCell mobility history information upon entering camped normally state or any cell selection state) may be supported only by terminals capable of PSCell mobility history information. A terminal may support pscell-MHI-ReportAnyCellSelectionOrCampedNormallyState starting from a specific specification number or specification release, without sending a terminal capability information message to the base station regarding support status. Alternatively, a terminal capable of PSCell mobility history information may support the aforementioned pscell-MHI-ReportAnyCellSelectionOrCampedNormallyState capability starting from a specific specification number or specification release.

[0240] In step 1i-20, the Master Node (MN) (1i-02) may initiate a Secondary Node Addition procedure to add a Secondary Node (SN) (1i-04) to the terminal (1i-01). In this disclosure, the SN base station may be referred to as PSCell 1 (1i-04). A specific Secondary Node Addition procedure may follow Section 10.2 of TS 37.340. That is, PSCell 1 (1i-04) may be added to the terminal (1i-01) through step 1i-20.

[0241] In step 1i-25, the terminal (1i-01) supports PSCell mobility history information and, when PSCell 1 (1i-04) is added (if the UE supports PSCell mobility history information and upon addition of a PSCell), the mobility history information can be stored in the terminal variable VarMobilityHistoryReport according to the aforementioned embodiment (Fig. 1f).

[0242] In step 1i-30, the terminal (1i-01) can transition to RRC idle mode (RRC_IDLE) or RRC inactive mode (RRC_INACTIVE) and perform a cell selection process.

[0243] In step 1i-35, the terminal (1i-01) may enter the Camped Normally state after finding a suitable cell, or it may enter the Any Cell Selection state after failing to find a suitable cell.

[0244] In step 1i-40, if the terminal (1i-01) is in at least one DC among EN-DC, (NG)EN-DC, NE-DC, and NR-DC and transitions to a camped normally state or any cell selection state, it may perform the following operation.

[0245] - The cell identifier for PCell 1 (global cell identity or physical cell identity and carrier frequency) and the time spent in PCell 1 (time sepnt in the previous PCell / serving cell) can be stored in the terminal variable VarMobilityHistoryReport.

[0246] - The cell identifier for PSCell 1 (global cell identity or physical cell identity and carrier frequency) and the time spent connected to PSCell 1 and staying on PSCell 1 can be stored in the terminal variable VarMobilityReport.

[0247] For example, the above terminal operation can be represented by the following series of operations.

[0248]

[0249]

[0250]

[0251] In step 1i-45, the terminal (1i-01) can enter the RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with a predetermined suitable cell (1i-02) in step 1i-40.

[0252] In step 1i-50, the terminal (1i-01) may receive a terminal information request message (UEInformationRequest) from PCell 1 (1i-02). In the message, mobilityHistoryReportReq may be set to true.

[0253] In step 1i-55, the terminal (1i-01) can transmit a terminal information response message (UEInformationResponse) to PCell 1 (1i-02). That is, if mobilityHistoryReportReq included in the terminal information request message received in step 1i-50 is set to true, the terminal (1i-01) can report mobility history information through the terminal information response message according to the above-described embodiment (Fig. 1f).

[0254] A terminal (1i-01) according to a next-generation mobile communication system has the following characteristics in storing mobility history information and reporting it to a base station.

[0255] - The terminal (1i-01) can enter RRC connection mode with PCell 1 (1i-02), then set up PSCell 1 (1i-04) and operate as a DC, and then exit RRC connection mode. When entering the Camped Normally state or Any Cell Selection state through the cell selection process in RRC idle mode or RRC disabled mode, the mobility history information for PCell 1 (1i-02) (cell identifier for PCell 1 and time spent in PCell 1) and the mobility history information for PSCell 1 (1i-04) (cell identifier for PSCell 1 and time spent in PSCell 1 while connected to PCell 1) are stored in the terminal variable VarMobilityHistoryReport. Therefore, when the base station retrieves it, the terminal (1i-01) enters the RRC connection mode to PCell 1 (1i-02), and then the base station can identify the mobility history information for PCell 1 (1i-02) and the mobility history information for PSCell 1 (1i-04).

[0256] FIG. 1j is a diagram illustrating a terminal operation in a next-generation mobile communication system according to one embodiment of the present disclosure, in which the terminal stores mobility history information for a PSCell and reports it to a base station.

[0257] Referring to FIG. 1j, the terminal (1j-01) can enter the RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with the base station (1j-02) (1j-10). The base station may be referred to as PCell 1 or Master Node (MN) base station. For reference, PCell 1 is a suitable cell.

[0258] In step 1j-15, the terminal (1j-01) may transmit a terminal capability information message (UECapabilityInformation) to PCell 1 (1j-02). This may follow at least one of the previously described embodiments (Figs. 1f, 1g). Additionally, the message may include the following capability information.

[0259] - pscell-MHI-ReportAnyCellSelectionOrSuitableCellChange: The ability to store and report to the base station the cell identifier for the PSCell (global cell identity or physical cell identity and carrier frequency) and information on the time the PSCell was connected (time spent in the PSCell while being connected to the PCell) when the terminal (1j-01) has both the PCell and PSCell configured (i.e., Dual Connectivity (DC) configured) and then exits RRC connection mode and the suitable cell changes or transitions to the Any Cell Selection state.

[0260] -- DC may mean at least one of EN-DC, (NG)EN-DC, NE-DC, and NR-DC.

[0261] For reference, pscell-MHI-ReportAnyCellSelectionOrSuitableCellChange (support of PSCell mobility history information upon change of suitable cell or any cell selection state) may be supported only by terminals capable of PSCell mobility history information. A terminal may support pscell-MHI-ReportAnyCellSelectionOrSuitableCellChange starting from a specific specification number or specification release without sending a terminal capability information message to the base station regarding support status. Alternatively, a terminal capable of PSCell mobility history information may support the aforementioned pscell-MHI-ReportAnyCellSelectionOrSuitableCellChange capability starting from a specific specification number or specification release.

[0262] In step 1j-20, the Master Node (MN) (1j-02) may initiate a Secondary Node Addition procedure to add a Secondary Node (SN) (1j-04) to the terminal (1j-01). In this disclosure, the SN base station (1j-04) may be referred to as PSCell 1 (1j-04). A specific Secondary Node Addition procedure may follow Section 10.2 of TS 37.340. That is, PSCell 1 (1j-04) may be added to the terminal (1j-01) through step 1j-20.

[0263] In step 1j-25, the terminal (1j-01) supports PSCell mobility history information and, when PSCell 1 (1j-04) is added (if the UE supports PSCell mobility history information and upon addition of a PSCell), the mobility history information can be stored in the terminal variable VarMobilityHistoryReport according to the above-described embodiment (Fig. 1f).

[0264] In step 1j-30, the terminal (1j-01) can transition to an RRC idle mode (RRC_IDLE) or an RRC inactive mode (RRC_INACTIVE) and perform a cell selection process.

[0265] In step 1j-35, the terminal (1j-01) may enter the Camped Normally state by finding a suitable cell different from PCell 1 (1j-02), or it may enter the Any Cell Selection state by failing to find a suitable cell.

[0266] In step 1j-40, if the terminal (1j-01) is in at least one DC among EN-DC, (NG)EN-DC, NE-DC, and NR-DC and then exits the RRC connection mode and finds a suitable cell other than PCell 1 (1j-02) to camp-on or transitions to any cell selection state, it may perform the following operations.

[0267] - The cell identifier for PCell 1 (global cell identity or physical cell identity and carrier frequency) and the time spent in PCell 1 (time sepnt in the previous PCell / serving cell) can be stored in the terminal variable VarMobilityHistoryReport.

[0268] - The cell identifier for PSCell 1 (global cell identity or physical cell identity and carrier frequency) and the time spent connected to PSCell 1 and staying on PSCell 1 can be stored in the terminal variable VarMobilityReport.

[0269] For example, the above terminal operation can be represented by the following series of operations.

[0270]

[0271]

[0272]

[0273] In step 1j-45, the terminal (1j-01) can enter RRC connection mode (RRC_CONNECTED) by establishing an RRC connection with a suitable cell (1j-02).

[0274] In step 1j-50, the terminal (1j-01) can receive a terminal information request message (UEInformationRequest) from PCell 1 (1j-02). In the message, mobilityHistoryReportReq may be set to true.

[0275] In step 1j-55, the terminal (1j-01) can transmit a terminal information response message (UEInformationResponse) to PCell 1 (1j-02). That is, if mobilityHistoryReportReq included in the terminal information request message received in step 1j-50 is set to true, the terminal (1j-01) can report mobility history information through the terminal information response message according to the above-described embodiment (Fig. 1f).

[0276] A terminal (1j-01) according to a next-generation mobile communication system has the following characteristics in storing mobility history information and reporting it to a base station.

[0277] - The terminal (1j-01) can enter RRC connection mode with PCell 1 (1j-02), then set up PSCell 1 (1j-04) and operate as a DC, and then exit RRC connection mode. When a suitable cell different from PCell 1 (1j-02) is found through a cell selection process in RRC idle mode or RRC disabled mode and the terminal enters Camped Normally state or Any Cell Selection state, the terminal has the feature of storing mobility history information for PCell 1 (1j-02) (cell identifier for PCell 1 and time spent in PCell 1) and mobility history information for PSCell 1 (1j-04) (cell identifier for PSCell 1 and time spent in PSCell 1 (1j-04) while connected to PCell 1 (1j-02)) in the terminal variable VarMobilityHistoryReport. Therefore, when the base station retrieves it, the terminal (1j-01) enters the RRC connection mode to PCell 1 (1j-02), and then the base station can identify the mobility history information for PCell 1 (1j-02) and the mobility history information for PSCell 1.

[0278] FIG. 1k is a block diagram illustrating the internal structure of a terminal according to one embodiment of the present invention.

[0279] Referring to the drawing above, the terminal includes an RF (Radio Frequency) processing unit (1k-10), a baseband processing unit (1k-20), a storage unit (1k-30), and a control unit (1k-40).

[0280] The RF processing unit (1k-10) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (1k-10) up-converts the baseband signal provided by the baseband processing unit (1k-20) into an RF band signal and transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (1k-10) may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC (digital to analog converter), an ADC (analog to digital converter), etc. Although only one antenna is shown in the drawing, the terminal may be equipped with multiple antennas. In addition, the RF processing unit (1k-10) may include multiple RF chains. Furthermore, the RF processing unit (1k-10) may perform beamforming. For the above beamforming, the RF processing unit (1k-10) can adjust the phase and magnitude of each of the signals transmitted and received through a plurality of antennas or antenna elements. In addition, the RF processing unit can perform MIMO and can receive multiple layers when performing MIMO operation.

[0281] The baseband processing unit (1k-20) performs a conversion function between a baseband signal and a bit sequence according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit (1k-20) generates complex symbols by encoding and modulating the transmitted bit sequence. Additionally, when receiving data, the baseband processing unit (1k-20) restores the received bit sequence by demodulating and decoding the baseband signal provided by the RF processing unit (1k-10). For example, in the case of following the orthogonal frequency division multiplexing (OFDM) method, when transmitting data, the baseband processing unit (1k-20) generates complex symbols by encoding and modulating the transmitted bit sequence, maps the complex symbols to subcarriers, and then constructs OFDM symbols through inverse fast Fourier transform (IFFT) operations and cyclic prefix (CP) insertion. Additionally, upon receiving data, the baseband processing unit (1k-20) divides the baseband signal provided by the RF processing unit (1k-10) into OFDM symbol units, restores the signals mapped to subcarriers through a fast Fourier transform (FFT), and then restores the received bit sequence through demodulation and decoding.

[0282] The baseband processing unit (1k-20) and the RF processing unit (1k-10) transmit and receive signals as described above. Accordingly, the baseband processing unit (1k-20) and the RF processing unit (1k-10) may be referred to as a transmitting unit, a receiving unit, a transmitting and receiving unit, or a communication unit. Furthermore, at least one of the baseband processing unit (1k-20) and the RF processing unit (1k-10) may include a plurality of communication modules to support a plurality of different wireless access technologies. Additionally, at least one of the baseband processing unit (1k-20) and the RF processing unit (1k-10) may include different communication modules to process signals of different frequency bands. For example, the different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), cellular network (e.g., LTE), etc. In addition, the above different frequency bands may include super high frequency (SHF) bands (e.g., 2 NRHz, NRHz) and millimeter wave (e.g., 60 GHz) bands.

[0283] The storage unit (1k-30) stores data such as basic programs, application programs, and configuration information for the operation of the terminal. In particular, the storage unit (1k-30) can store information related to a second connection node that performs wireless communication using a second wireless connection technology. Additionally, the storage unit (1k-30) provides the stored data upon the request of the control unit (1k-40).

[0284] The control unit (1k-40) controls the overall operations of the terminal. For example, the control unit (1k-40) transmits and receives signals through the baseband processing unit (1k-20) and the RF processing unit (1k-10). Additionally, the control unit (1k-40) writes and reads data to and from the storage unit (1k-40). To this end, the control unit (1k-40) may include at least one processor. For example, the control unit (1k-40) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as applications. The control unit (1k-40) may further include a multiple connection processing unit (1i-42) that supports multiple connections.

[0285] FIG. 11 is a block diagram showing the configuration of an NR base station according to one embodiment of the present invention.

[0286] As illustrated in the drawing above, the base station is configured to include an RF processing unit (11-10), a baseband processing unit (11-20), a backhaul communication unit (11-30), a storage unit (11-40), and a control unit (11-50).

[0287] The RF processing unit (1l-10) performs functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit (1l-10) upconverts the baseband signal provided by the baseband processing unit (1l-20) into an RF band signal and transmits it through an antenna, and downconverts the RF band signal received through the antenna into a baseband signal. For example, the RF processing unit (1l-10) may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc. Although only one antenna is shown in the drawing, the first connection node may be equipped with multiple antennas. Additionally, the RF processing unit (1l-10) may include multiple RF chains. Furthermore, the RF processing unit (1l-10) may perform beamforming. For the above beamforming, the RF processing unit (1l-10) can adjust the phase and magnitude of each of the signals transmitted and received through a plurality of antennas or antenna elements. The RF processing unit can perform down-to-down MIMO operation by transmitting one or more layers.

[0288] The baseband processing unit (1l-20) performs a conversion function between a baseband signal and a bit sequence according to the physical layer specifications of the first wireless access technology. For example, when transmitting data, the baseband processing unit (1l-20) generates complex symbols by encoding and modulating the transmitted bit sequence. Additionally, when receiving data, the baseband processing unit (1l-20) restores the received bit sequence by demodulating and decoding the baseband signal provided by the RF processing unit (1l-10). For example, in the case of following the OFDM method, when transmitting data, the baseband processing unit (1l-20) generates complex symbols by encoding and modulating the transmitted bit sequence, maps the complex symbols to subcarriers, and then constructs OFDM symbols through IFFT operation and CP insertion. Additionally, upon receiving data, the baseband processing unit (1l-20) divides the baseband signal provided by the RF processing unit (1l-10) into OFDM symbol units, restores the signals mapped to subcarriers through FFT operations, and then restores the received bit sequence through demodulation and decoding. The baseband processing unit (1l-20) and the RF processing unit (1l-10) transmit and receive signals as described above. Accordingly, the baseband processing unit (1l-20) and the RF processing unit (1l-10) may be referred to as a transmitting unit, a receiving unit, a transmitting and receiving unit, a communication unit, or a wireless communication unit.

[0289] The backhaul communication unit (1l-30) provides an interface for communicating with other nodes within the network. That is, the backhaul communication unit (1l-30) converts a bit sequence transmitted from the main base station to another node, e.g., an auxiliary base station, a core network, etc., into a physical signal, and converts a physical signal received from the other node into a bit sequence.

[0290] The storage unit (1l-40) stores data such as basic programs, application programs, and configuration information for the operation of the main station. In particular, the storage unit (1l-40) can store information regarding bearers assigned to connected terminals, measurement results reported from connected terminals, etc. Additionally, the storage unit (1l-40) can store information serving as a criterion for determining whether to provide multiple connections to the terminal or to disconnect them. Furthermore, the storage unit (1l-40) provides the stored data upon the request of the control unit (1l-50).

[0291] The control unit (1l-50) controls the overall operations of the main station. For example, the control unit (1l-50) transmits and receives signals through the baseband processing unit (1l-20) and the RF processing unit (1l-10) or through the backhaul communication unit (1l-30). Additionally, the control unit (1l-50) writes and reads data to and from the storage unit (1l-40). To this end, the control unit (1l-50) may include at least one processor. The control unit (1l-50) may further include a multiple connection processing unit (1j-52) to support multiple connections.

[0292] Methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0293] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of this disclosure.

[0294] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disc storage devices, compact disc-ROM (CD-ROM), digital versatile discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0295] Additionally, the program may be stored on an attachable storage device that can be accessed via a communication network such as the Internet, Intranet, LAN (local area network), WAN (wide area network), or SAN (storage area network), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present disclosure through an external port. Additionally, a separate storage device on a communication network may be connected to a device performing an embodiment of the present disclosure.

[0296] In the specific embodiments of the present disclosure described above, the components included in the disclosure are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present disclosure is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed of a singular form, and even if a component is expressed in the singular form, it may be composed of a plural form.

[0297] Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, it is understood that various modifications are possible within the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof.

[0298] For example, some or all of a specific embodiment of the present disclosure may be combined with some or all of one or more other embodiments, and such combination is also included in the embodiments of the present disclosure.

Claims

1. In a method of operation of UE (user equipment) in a wireless communication system, A step of creating an entry containing information related to the previous PCell in the previously visited cell list of information for reporting mobility history when there is a change in a suitable cell, entry from a camped normally state to an any cell selection state, or entry from a suitable cell in an RRC (radio resource control) connected state to an any cell selection state; The above UE supports the storage of mobility history information for a PSCell (primary secondary cell), and when entering an any cell selection state from a suitable cell in an RRC connection state where the PSCell was not set, the step of creating an item including time information where there was no PScell ​​in the previously visited PScell ​​list for reporting the mobility history; and A method comprising the step of transmitting a message containing information for reporting the above mobility history to a base station.

2. In Paragraph 1, The above information regarding the previous PCell is, A method comprising information on the ID (identity) of a previous PCell or previous serving cell and the time spent in said previous PCell or previous serving cell.

3. In Paragraph 2, The ID of the aforementioned previous PCell or the aforementioned previous serving cell is, A method comprising one of a global cell ID, or a physical cell ID and a carrier frequency.

4. In Paragraph 1, The time information when there was no PScell ​​in the above PSCell information list (visited PScell ​​list) is, A method in which, when PSCell release is experienced after entering an RRC connection state to a previous PCell, the time during which the PSCell was in a state without a PSCell from the last PSCell release point after entering an RRC connection state to the previous PCell is included.

5. In Paragraph 1, The time information when there was no PScell ​​in the above PSCell information list (visited PScell ​​list) is, A method including the time during which there was no PSCell after entering the RRC connection state to the previous PCell, in the case where PSCell release was not experienced after entering the RRC connection state to the previous PCell.

6. In Paragraph 1, The above list of previously visited PSCell information is, A method including the ID of a previously visited PSCell.

7. In Paragraph 1, The step of transmitting a message containing information for reporting the above mobility history to a base station is: A step of receiving a UE information request message from the base station requesting a report of the mobility history for the UE; and A method comprising the step of transmitting a UE information response message to a base station, the message including information for reporting the mobility history, in response to the above UE information request message.

8. In Paragraph 1, A method further comprising the step of transmitting a UE capability information message to the base station, the message including information that the UE supports the storage of mobility history information for the PSCell.

9. In the UE (user equipment) of a wireless communication system, At least one transceiver; At least one processor communicatively coupled to the above at least one transceiver; and It includes at least one memory that is communicationally coupled to the above at least one processor and stores instructions, and The above instructions are executed individually or in any combination by the above at least one processor, so that the UE: In the event of a change in a suitable cell, entry from the camped normally state to the any cell selection state, or entry from a suitable cell in the RRC (radio resource control) connected state to the any cell selection state, an entry containing information related to the previous PCell is created in the previously visited cell list of information for reporting mobility history, and The above UE supports the storage of mobility history information for a PSCell (primary secondary cell), and when entering the any cell selection state from a suitable cell in an RRC connection state, if the PSCell was not configured, it creates an item that includes time information where the PScell ​​was not present in the previously visited PScell ​​list for reporting the mobility history. A UE that transmits a message containing information for reporting the above mobility history to a base station.

10. In Paragraph 9, The above information regarding the previous PCell is, A UE including the ID (identity) of a previous PCell or previous serving cell and information on the time spent in said previous PCell or previous serving cell.

11. In Paragraph 10, The ID of the aforementioned previous PCell or the aforementioned previous serving cell is, UE including one of a global cell ID, or a physical cell ID and a carrier frequency.

12. In Paragraph 9, The time information when there was no PScell ​​in the above PSCell information list (visited PScell ​​list) is, If PSCell release was experienced after entering the RRC connection state to the previous PCell, the time during which the PCell was in a state without a PSCell from the last PSCell release point after entering the RRC connection state to the previous PCell is included, A UE that has not experienced PSCell release since entering the RRC connection state to the previous PCell, including the time that was in a state without PSCell since entering the RRC connection state to the previous PCell.

13. In Paragraph 9, The above list of previously visited PSCell information is, UE containing the ID of a previously visited PSCell.

14. In paragraph 9, the above commands are: the UE A message containing information for reporting the above mobility history is transmitted to a base station, and Receive a UE information request message from the base station requesting a report of the mobility history for the UE, and A UE that transmits a UE information response message containing information for reporting the mobility history to a base station in response to the above UE information request message.

15. In Paragraph 9, In paragraph 9, the above commands are: A UE that transmits a UE capability information message to the base station, the message including information that the UE supports the storage of mobility history information for the PSCell.

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