Method and apparatus for transmitting system information in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Specifically, the present disclosure relates to a method and an apparatus for transmitting system information in a wireless communication system.

Description

Method and apparatus for transmitting system information in a wireless communication system

[0001] The present disclosure relates to the operation of a base station and a terminal in a mobile communication system. Specifically, the present disclosure relates to a method and apparatus for transmitting system 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 band (e.g., the 3 terahertz (3 THz) 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, Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas to guarantee coverage in the terahertz band of 6G mobile communication technology; metamaterial-based lenses and antennas; high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM); and Reconfigurable Intelligent Surface (RIS) technology to improve terahertz band signal coverage; 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 Artificial Intelligence (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] As a result of the aforementioned developments and advancements in mobile communication systems, it has become possible to provide a variety of services, and thus measures to effectively provide these services are required.

[0009] The disclosed embodiments aim to provide an apparatus and method capable of effectively providing services in a mobile communication system.

[0010] According to one embodiment of the present invention for solving the above-mentioned problems, a method performed by a terminal (user equipment) in a wireless communication system may include: a step of identifying a failure to acquire system information divided into a plurality of segments transmitted from a first base station; a step of discarding at least some or all of the received segments among the plurality of segments; a step of storing acquisition failure information including the reason for the failure to acquire the system information; and a step of performing a cell reselection procedure to a second base station.

[0011] The above system information may include a digital signature to which a security algorithm has been applied to the original system information, the original system information, and time information.

[0012] The above original system information may include either a master information block (MIB) or a system information block (SIB).

[0013] The step of identifying the failure of the above acquisition may identify any one of the failure to receive at least some of the plurality of segments, the failure to assemble the plurality of segments, and the failure to authenticate the system information.

[0014] The above system information can be received through the response message of the first base station to the authentication request of the terminal.

[0015] The above method may include the steps of: transmitting an RRC (radio resource control) resume request message or an RRC setup request message to the second base station that includes an indicator indicating the reason for the acquisition failure; receiving an RRC Resume message or an RRC setup message from the second base station; transmitting an RRC resume complete message or an RRC setup complete message to the second base station that includes whether the reason for the acquisition failure can be provided; receiving an RRC DL (download) message from the second base station that includes a request for the acquisition failure information; and transmitting an RRC UL (uplink) message to the second base station that includes the acquisition failure information.

[0016] The above method may include the steps of: transmitting an RRC resume request or RRC setup request message to the second base station that includes an indicator indicating the reason for the acquisition failure; receiving an RRC Resume message or RRC setup message from the second base station that includes a request for the acquisition failure information; and transmitting an RRC resume complete message or RRC setup complete message to the second base station that includes the acquisition failure information.

[0017] The above method may include the steps of: transmitting an RRC resume request message or an RRC setup request message to the second base station, the message including an indicator indicating the reason for the acquisition failure and the acquisition failure information; receiving an RRC Resume message or an RRC setup message from the second base station; and transmitting an RRC resume complete message or an RRC setup complete message to the second base station.

[0018] The above method may include the step of identifying whether a RACH (random access channel) SDT is possible at the second base station based on SDT (small data transmission) setting information; and the step of transmitting a Msg3 containing the acquisition failure information to the second base station based on the identification result.

[0019] The above method may further include the step of receiving measurement setting information instructing the second base station to report a cell global identifier (CGI) for the first base station; and the step of reporting the acquisition failure information.

[0020] The step of reporting the acquisition failure information may include the step of transmitting a UL RRC message or a UL MAC CE message or UCI (uplink control information) containing the acquisition failure information to the second base station.

[0021] According to one embodiment of the present invention for solving the above-mentioned problems, in a user equipment of a wireless communication system, the terminal comprises: a transceiver; and at least one processor coupled to the transceiver, wherein the at least one processor identifies a failure to acquire system information divided into a plurality of segments transmitted from a first base station, discards at least some or all of the received segments among the plurality of segments, stores acquisition failure information including the reason for the failure to acquire the system information, and can perform a cell reselection procedure to a second base station.

[0022] The above system information includes a digital signature to which a security algorithm is applied to the original system information, the original system information, and time information, and the original system information may include either a master information block (MIB) or a system information block (SIB).

[0023] The above at least one processor can identify any one of the failure to receive at least some of the plurality of segments, the failure to assemble the plurality of segments, and the failure to authenticate the system information.

[0024] The above system information can be received through the response message of the first base station to the authentication request of the terminal.

[0025] The above at least one processor may transmit an RRC (radio resource control) resume request message or an RRC setup request message including an indicator indicating the reason for the acquisition failure to the second base station, receive an RRC Resume message or an RRC setup message from the second base station, transmit an RRC resume complete message or an RRC setup complete message including whether the reason for the acquisition failure can be provided to the second base station, receive an RRC DL (download) message including a request for the acquisition failure information from the second base station, and transmit an RRC UL (uplink) message including the acquisition failure information to the second base station.

[0026] The disclosed embodiments provide an apparatus and method capable of effectively providing services in a mobile communication system.

[0027] FIG. 1 illustrates a wireless protocol structure of a next-generation mobile communication system according to one embodiment of the present disclosure.

[0028] FIG. 2 illustrates the structure of a terminal according to one embodiment of the present disclosure.

[0029] FIG. 3 illustrates the configuration of an NR base station according to one embodiment of the present disclosure.

[0030] FIG. 4 illustrates an asymmetric key-based system information transfer process according to one embodiment of the present disclosure.

[0031] FIG. 5 illustrates the operation of a terminal when the terminal according to one embodiment of the present disclosure fails to obtain valid MIB information.

[0032] FIG. 6 illustrates the operation of a terminal when the terminal according to one embodiment of the present disclosure fails to obtain valid SIB1 information.

[0033] FIG. 7 illustrates a signal procedure (Opt 1-1) in which information stored in a terminal according to one embodiment of the present disclosure is transmitted to a base station or network.

[0034] FIG. 8 illustrates a signal procedure (Opt 1-2) in which information stored in a terminal according to one embodiment of the present disclosure is transmitted to a base station or network.

[0035] FIG. 9 illustrates a signal procedure (Opt 1-3) in which information stored in a terminal according to one embodiment of the present disclosure is transmitted to a base station or network.

[0036] FIG. 10 illustrates a flowchart of a case (Opt 2) in which information related to a failure to acquire system information is reported through an SDT function according to one embodiment of the present disclosure.

[0037] FIG. 11 illustrates a flowchart of an operation in which a terminal in a connected mode state reports failure information according to one embodiment of the present disclosure.

[0038] 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.

[0039] 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.

[0040] Hereinafter, a 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), radio access unit, base station controller, or a node on a network. A terminal may include a UE (User Equipment), MS (Mobile Station), cellular phone, smartphone, computer, or a multimedia system capable of performing communication functions. In this disclosure, a downlink (DL) refers to a wireless transmission path of a signal transmitted by a base station to a terminal, and an uplink (UL) refers to a wireless transmission path of a signal transmitted by a terminal to a base station. Furthermore, while an LTE or LTE-A system may be described as an example below, embodiments of this disclosure may be applied to other communication systems having similar technical backgrounds or channel types. For example, 5th generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included in a system to which embodiments of this disclosure can be applied, and the 5G below may be a concept that includes existing LTE, LTE-A, and other similar services. Furthermore, 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 departing significantly from the scope of the present disclosure. In this case, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams may be executed by computer program instructions.

[0041] Since these computer program instructions can be loaded onto the processor of a general-purpose computer, a computer for special purposes, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means for performing the functions described in the flowchart 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 functions in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing means of instruction for performing the functions described in the flowchart block(s). Since the computer program instructions can also be loaded onto the computer or other programmable data processing equipment, the instructions that perform a series of operation steps on the computer or other programmable data processing equipment to create a computer-executable process can also provide steps for performing the functions described in the flowchart block(s).

[0042] 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). Also, it should 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 be executed in reverse order depending on the corresponding function. In this case, the term "part" as used in this embodiment refers to software or hardware components such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), and the "part" may perform 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 configured to run one or more processors. Accordingly, as an example, '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'. Furthermore, the components and 'parts' may be implemented to utilize one or more CPUs within a device or secure multimedia card. Additionally, in an embodiment, 'part' may include one or more processors.

[0043] For convenience of explanation, the present disclosure uses terms and names defined in the 5GS and NR specifications, which are standards defined by the 3GPP (The 3rd Generation Partnership Project) among currently existing communication standards. However, the present disclosure is not limited to the above terms and names and may be applied equally to wireless communication networks conforming to other standards. For example, the present disclosure may be applied to 3GPP 5GS / NR (5th generation mobile communication standard).

[0044] The present disclosure relates to the operation of a base station and a terminal in a wireless communication system. Specifically, the present disclosure relates to a method and apparatus for transmitting system information in a wireless communication system. Furthermore, the present disclosure may provide a method for a terminal to receive information from a base station when the base station performs the transmission of information with security in mind.

[0045] According to one embodiment of the present disclosure, a terminal may perform authentication for system information transmitted by a base station. In this case, processing operations of the terminal for system information that failed authentication may be required.

[0046] According to one embodiment of the present disclosure, if authentication of system information of a specific cell fails, the terminal may notify the system without reusing the system information that failed authentication.

[0047] FIG. 1 is a diagram showing the wireless protocol structure of a next-generation mobile communication system according to one embodiment of the present disclosure.

[0048] Referring to FIG. 1, the wireless protocol of a next-generation mobile communication system may include NR Service Data Adaptation Protocol (SDAP) (1-01, 1-45), NR PDCP (1-05, 1-40), NR RLC (1-10, 1-35), NR MAC (1-15, 1-30), and NR PHY (1-20, 1-25) layers at the terminal and the NR base station, respectively. Of course, the wireless protocol of the next-generation mobile communication system may include more or fewer layers than the configuration shown in FIG. 1.

[0049] Hereinafter, in the present disclosure, 'layered device' is a term meaning a layer of NR and may be referred to interchangeably with 'layer'.

[0050] According to one embodiment of the present disclosure, the main functions of the SDAP layer device (1-01, 1-45) of the NR may include some of the following functions, but the functions of the SDAP layer device (1-01, 1-45) of the NR are not limited to the following examples.

[0051] - User data transfer function (transfer of user plane data)

[0052] - Mapping function between a QoS flow and a DRB for both DL and UL for uplink and downlink

[0053] - Marking QoS flow ID in both DL and UL packets for uplink and downlink

[0054] - Function to map reflective QoS flow to data bearers for uplink SDAP PDUs (reflective QoS flow to DRB mapping for the UL SDAP PDUs).

[0055] For SDAP layer devices (1-01, 1-45), 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 (1-01, 1-45) for each PDCP layer device, for each bearer, or for each logical channel. If the SDAP header is configured, the terminal may be instructed to update or reset the mapping information for the QoS flows of the uplink and downlink and the data bearer using the Non-Access Stratum (NAS) Quality of Service (QoS) reflective setting 1-bit indicator (NAS reflective QoS) and the Access Stratum (AS) QoS reflective setting 1-bit indicator (AS reflective QoS) of the SDAP header. According to one embodiment, the SDAP header may include QoS flow ID information indicating QoS. According to one embodiment, QoS information can be used for data processing priority, scheduling information, etc., to support smooth service.

[0056] According to one embodiment of the present disclosure, the main functions of the NR PDCP layer device (1-05, 1-40) may include some of the following functions, but the functions of the NR PDCP layer device (1-05, 1-40) are not limited to the following examples.

[0057] The main functions of NR PDCP (1-05, 1-40) may include some of the following functions.

[0058] - Header compression and decompression features (ROHC only)

[0059] - User data transfer function (Transfer of user data)

[0060] - Sequential delivery function (In-sequence delivery of upper layer PDUs)

[0061] - Out-of-sequence delivery of upper layer PDUs

[0062] - Reordering function (PDCP PDU reordering for reception)

[0063] - Duplicate detection function (Duplicate detection of lower layer SDUs)

[0064] - Retransmission of PDCP SDUs

[0065] - Encryption and decryption functions (Ciphering and deciphering)

[0066] - Timer-based SDU discard in uplink.

[0067] In the above description, the reordering function of the NR PDCP layer device (1-05, 1-40) may mean a function of reordering PDCP PDUs received from the lower layer in order based on the PDCP SN (sequence number). The reordering function of the NR PDCP layer device (1-05, 1-40) may include a function of transmitting data to the upper layer in the reordered order, or a function of transmitting immediately without considering the order, a function of recording lost PDCP PDUs by reordering the order, a function of reporting the status of lost PDCP PDUs to the transmitting side, or a function of requesting retransmission of lost PDCP PDUs.

[0068] The main functions of the NR RLC layer device (1-10, 1-35) according to one embodiment of the present disclosure may include some of the following functions, but the functions of the NR RLC layer device (1-10, 1-35) are not limited to the following examples.

[0069] - Data transfer function (Transfer of upper layer PDUs)

[0070] - Sequential delivery function (In-sequence delivery of upper layer PDUs)

[0071] - Out-of-sequence delivery of upper layer PDUs

[0072] - ARQ function (Error Correction through ARQ)

[0073] - Concatenation, segmentation, and reassembly functions of RLC SDUs

[0074] - Re-segmentation function (Re-segmentation of RLC data PDUs)

[0075] - Reordering function (Reordering of RLC data PDUs)

[0076] - Duplicate detection

[0077] - Error detection function (Protocol error detection)

[0078] - RLC SDU discard function

[0079] RLC re-establishment function

[0080] In the above description, the in-sequence delivery function of the NR RLC layer device (1-10, 1-35) may mean a function of delivering RLC SDUs received from a lower layer to an upper layer in order. The in-sequence delivery function of the NR RLC layer device (1-10, 1-35) may include a function of reassembling the divided RLC SDUs received and delivering them to an upper layer when a single RLC SDU is originally divided into multiple RLC SDUs.

[0081] According to one embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer device (1-10, 1-35) may include at least one of the following: a function of rearranging received RLC PDUs based on an RLC SN (sequence number) or a PDCP SN (sequence number); a function of recording lost RLC PDUs by rearranging the order; a function of reporting the status of lost RLC PDUs to the transmitting side; or a function of requesting retransmission of lost RLC PDUs.

[0082] According to one embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer device (1-10, 1-35) may include a function to sequentially deliver only the RLC SDUs up to the RLC SDU prior to the lost RLC SDU to the upper layer when there is a lost RLC SDU.

[0083] According to one embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer device (1-10, 1-35) may include the function of delivering all RLC SDUs received before the timer started to the upper layer in order, even if there are lost RLC SDUs, if a predetermined timer has expired.

[0084] According to one embodiment of the present disclosure, the in-sequence delivery function of the NR RLC layer device (1-10, 1-35) may include the function of delivering all RLC SDUs received up to that point to the upper layer in order when a predetermined timer has expired, even if there are lost RLC SDUs.

[0085] According to one embodiment of the present disclosure, an NR RLC layer device (1-10, 1-35) can process RLC PDUs in the order in which they are received, regardless of the sequence number (out-of-sequence delivery), and deliver them to an NR PDCP layer device (1-04, 1-40).

[0086] According to one embodiment of the present disclosure, when an NR RLC layer device (1-10, 1-35) receives a segment, it may receive segments stored in a buffer or to be received later, reconstruct them into a single complete RLC PDU, and then transmit them to an NR PDCP layer device (1-04, 1-40).

[0087] According to one embodiment of the present disclosure, the NR RLC layer device (1-10, 1-35) may not include a concatenation function and may perform the function in the NR MAC layer device (1-15, 1-30) or be replaced by the multiplexing function of the NR MAC layer device (1-15, 1-30).

[0088] In the above description, the out-of-sequence delivery function of the NR RLC layer device (1-10, 1-35) may mean a function that delivers RLC SDUs received from a lower layer directly to an upper layer regardless of order.

[0089] According to one embodiment of the present disclosure, the out-of-sequence delivery function of the NR RLC layer device (1-10, 1-35) may include the function of reassembling the divided RLC SDUs and delivering them to the upper layer when the original one RLC SDU is divided and received into multiple RLC SDUs.

[0090] According to one embodiment of the present disclosure, the out-of-sequence delivery function of the NR RLC layer device (1-10, 1-35) may include the function of storing the RLC SN or PDCP SN of the received RLC PDUs and sorting the order to record the lost RLC PDUs.

[0091] According to one embodiment of the present disclosure, an NR MAC layer device (1-15, 1-30) may be connected to several NR RLC layer devices configured in one terminal (e.g., NR RLC layer devices (1-10, 1-35) of FIG. 1), and the main functions of the NR MAC layer device (1-15, 1-30) may include some of the following functions, but the functions of the NR MAC layer device (1-15, 1-30) are not limited to the following examples.

[0092] - Mapping function (Mapping between logical channels and transport channels)

[0093] - Multiplexing and demultiplexing functions (Multiplexing / demultiplexing of MAC SDUs)

[0094] - Scheduling information reporting function

[0095] - HARQ function (Error correction through HARQ)

[0096] - Priority handling between logical channels of one UE

[0097] - Priority handling between UEs by means of dynamic scheduling

[0098] - MBMS service identification function

[0099] - Transport format selection function

[0100] - Padding

[0101] According to one embodiment of the present disclosure, an NR PHY layer device (1-20, 1-25) can perform the operation of channel coding and modulating data transmitted from an upper layer, making it into an OFDM symbol and transmitting it to a wireless channel, or demodulating and channel decoding an OFDM symbol received through a wireless channel and transmitting it to an upper layer.

[0102] FIG. 2 is a block diagram illustrating the structure of a terminal according to one embodiment of the present disclosure.

[0103] Referring to FIG. 2, a terminal according to one embodiment of the present disclosure may include an RF (Radio Frequency) processing unit (2-10), a baseband processing unit (2-20), a storage unit (2-30), and a control unit (2-40).

[0104] An RF processing unit (2-10) according to one embodiment of the present disclosure can perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. The RF processing unit (2-10) can up-convert a baseband signal provided by a baseband processing unit (2-20) into an RF band signal and transmit it through an antenna, and down-convert an RF band signal received through an antenna into a baseband signal. For example, the RF processing unit (2-10) may include a transmission filter, a reception 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 FIG. 2, the terminal may be equipped with a plurality of antennas. In addition, the RF processing unit (2-10) may include a plurality of RF chains. Furthermore, the RF processing unit (2-10) may perform beamforming. For the above beamforming, the RF processing unit (2-10) can adjust the phase and magnitude of each of the signals transmitted and received through a plurality of antennas or a plurality of antenna elements. Additionally, the RF processing unit (2-10) can perform MIMO. When the RF processing unit (2-10) performs MIMO operation, it can receive multiple layers. The RF processing unit (2-10) can perform receiving beam sweeping by appropriately setting a plurality of antennas or antenna elements according to the control of the control unit, or can adjust the direction and beam width of the receiving beam so that the receiving beam is coordinated with the transmitting beam.

[0105] According to one embodiment of the present disclosure, the baseband processing unit (2-20) can perform 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 (2-20) can generate complex symbols by encoding and modulating the transmitted bit sequence. Additionally, when receiving data, the baseband processing unit (2-20) can restore the received bit sequence by demodulating and decoding the baseband signal provided by the RF processing unit (2-10). For example, in the case of following the orthogonal frequency division multiplexing (OFDM) method, the baseband processing unit (2-20) can generate complex symbols by encoding and modulating the transmitted bit sequence when transmitting data, map the complex symbols to subcarriers, and then construct OFDM symbols through inverse fast Fourier transform (IFFT) operations and cyclic prefix (CP) insertion. Additionally, the baseband processing unit (2-20), upon receiving data, divides the baseband signal provided by the RF processing unit (2-10) 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.

[0106] According to one embodiment of the present disclosure, the baseband processing unit (2-20) and the RF processing unit (2-10) can transmit and receive signals as described above. Accordingly, in the present disclosure, the baseband processing unit (2-20) and the RF processing unit (2-10) 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 (2-20) and the RF processing unit (2-10) 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 (2-20) and the RF processing unit (2-10) may include different communication modules to process signals of different frequency bands. For example, different wireless access technologies may include wireless LAN (e.g., IEEE 802.11), cellular network (e.g., LTE), etc. In addition, different frequency bands may include super high frequency (SHF) bands (e.g., 2 NRHz, NRHz) and millimeter wave (e.g., 60 GHz) bands.

[0107] According to one embodiment of the present disclosure, the storage unit (2-30) can store data such as a basic program, an application program, and setting information for the operation of the terminal. In particular, the storage unit (2-30) can store information related to a second connection node that performs wireless communication using a second wireless connection technology. Additionally, the storage unit (2-30) can provide the stored data upon a request from the control unit (2-40).

[0108] According to one embodiment of the present disclosure, the control unit (2-40) can control the overall operations of the terminal. For example, the control unit (2-40) can transmit and receive signals through the baseband processing unit (2-20) and the RF processing unit (2-10). Additionally, the control unit (2-40) can write data to the storage unit (2-40) and read the data written to the storage unit (2-40). According to one embodiment of the present disclosure, the control unit (2-40) may include at least one processor. For example, the control unit (2-40) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls an upper layer (e.g., an application program).

[0109] FIG. 3 is a block diagram showing the configuration of an NR base station according to one embodiment of the present invention.

[0110] As illustrated in FIG. 3, according to one embodiment of the present disclosure, a base station may include an RF processing unit (3-10), a baseband processing unit (3-20), a backhaul communication unit (3-30), a storage unit (3-40), and a control unit (3-50), but the configuration of the NR base station is not limited to the configuration illustrated in FIG. 3. For example, the NR base station may include fewer configurations or more configurations than the configuration illustrated in FIG. 3.

[0111] According to one embodiment of the present disclosure, the RF processing unit (3-10) can perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. The RF processing unit (3-10) can up-convert a baseband signal provided by the baseband processing unit (3-20) into an RF band signal and transmit it to a terminal through an antenna, and down-convert an RF band signal received from the terminal through an antenna into a baseband signal. For example, the RF processing unit (3-10) 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 FIG. 3, the RF processing unit (3-10) may be equipped with a plurality of antennas. Additionally, the RF processing unit (3-10) may include a plurality of RF chains. According to one embodiment of the present disclosure, the RF processing unit (3-10) may perform beamforming. For beamforming, the RF processing unit (3-10) 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.

[0112] According to one embodiment of the present disclosure, the baseband processing unit (3-20) can perform 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 (3-20) can generate complex symbols by encoding and modulating the transmitted bit sequence. Additionally, when receiving data, the baseband processing unit (3-20) can restore the received bit sequence through demodulation and decoding of the baseband signal provided by the RF processing unit (3-10). For example, in the case of following the OFDM method, when transmitting data, the baseband processing unit (3-20) can generate complex symbols by encoding and modulating the transmitted bit sequence, map the complex symbols to subcarriers, and then construct OFDM symbols through IFFT operation and CP insertion. Additionally, upon receiving data, the baseband processing unit (3-20) can divide the baseband signal provided by the RF processing unit (3-10) into OFDM symbol units, restore the signals mapped to subcarriers through FFT operations, and then restore the received bit sequence through demodulation and decoding. The baseband processing unit (3-20) and the RF processing unit (3-10) can transmit and receive signals as described above. Accordingly, in the present disclosure, the baseband processing unit (3-20) and the RF processing unit (3-10) may be referred to as a transmitting unit, a receiving unit, a transmitting and receiving unit, a communication unit, or a wireless communication unit.

[0113] According to one embodiment of the present disclosure, the backhaul communication unit (3-30) may provide an interface for performing communication with other nodes within the network. For example, the backhaul communication unit (3-30) may convert a bit sequence transmitted from the main base station to another node (e.g., auxiliary base station, core network) into a physical signal, and convert a physical signal received from another node (e.g., auxiliary base station, core network) into a bit sequence.

[0114] According to one embodiment of the present disclosure, the storage unit (3-40) may store data such as a basic program, an application program, and configuration information for the operation of the main station. The storage unit (3-40) may store information regarding a bearer assigned to a connected terminal, measurement results reported from the connected terminal, etc. Additionally, the storage unit (3-40) may store information that serves as a criterion for determining whether to provide or disconnect multiple connections to the terminal. Furthermore, the storage unit (3-40) may provide the stored data upon a request from the control unit (3-50).

[0115] According to one embodiment of the present disclosure, the control unit (3-50) can control the overall operations of the base station. For example, the control unit (3-50) can transmit and receive signals through the baseband processing unit (3-20) and the RF processing unit (3-10) or through the backhaul communication unit (3-30). Additionally, the control unit (3-50) can write data to the storage unit (3-40) and read data stored in the storage unit (3-40). To this end, the control unit (3-50) may include at least one processor.

[0116] In a wireless communication system according to one embodiment, a separate encryption mechanism may not be applied to system information. When a separate encryption mechanism is not applied to system information, the terminal can use system information to communicate with the system by always trusting the information transmitted from the cell and applying the information transmitted from the cell. Consequently, if a false base station (FBS) exists, it may cause the terminal to be unable to receive service or cause a degradation of system performance through incorrect control information.

[0117] Various embodiments according to the present disclosure may provide a method to overcome these problems by using an asymmetric encryption method on system information to encode the system information, generating a digital signature (DS) or MAC-I, and transmitting it together with the system information. For example, if a terminal receiving system information using an asymmetric encryption method succeeds in the decryption process using a given DS, time information, and a given public security key, the terminal may determine that the system information is authenticated. The terminal may use the system information determined to be authenticated for communication with a network.

[0118] FIG. 4 illustrates an asymmetric key-based system information transfer process according to one embodiment of the present disclosure.

[0119] Referring to FIG. 4, according to one embodiment of the present disclosure, a base station may generate a DS through encryption of system information to be transmitted to a terminal. For example, when a base station intends to transmit system information to a terminal, the base station may generate a DS using a PQC or non-PQC security algorithm that takes the original system information to be transmitted to the terminal, time information (time stamp, or time counter), and a private key assigned to the base station as input values. When the base station transmits the generated DS to the terminal, it may transmit information including a public key that can be disclosed to the terminal along with the original system information, time information, and DS information. Here, the public key that can be disclosed to the terminal may correspond to the private key of the base station used when generating the DS. For example, the information including the public key that can be disclosed to the terminal may include certificate information. When the base station transmits the public key that can be disclosed to the terminal to the terminal, the original system information among the information transmitted by the base station to the terminal may be omitted.

[0120] According to one embodiment of the present disclosure, the size of DS may be determined according to the security algorithm used. For example, in the case of non-PQC, the size of DS may correspond substantially to a value between 200 bytes and 400 bytes. For example, in the case of PQC, the size of DS may correspond substantially to a value between 3000 bytes and 7000 bytes.

[0121] According to one embodiment of the present disclosure, a base station may separate a DS into a plurality of fragments and transmit them to a terminal. For example, as described above, if the size of the DS according to one embodiment of the present disclosure is greater than 372 bytes, which is the maximum payload size of an SI message considered by an NR system, the base station may separate the DS into a plurality of fragments such that one fragment corresponds to an SI message and transmit them to the terminal. For example, in the case of non-PQC, the base station may separate the DS into two to three fragments, including original system information and other additional information, and transmit them to the terminal. For example, in the case of PQC, the base station may separate the DS into eight to seventeen fragments and transmit them to the terminal. At this time, each separated fragment may correspond to an SI message and be transmitted to the terminal.

[0122] According to one embodiment of the present disclosure, whenever a base station transmits original system information, the base station may transmit additional information associated with specific system information for which a terminal has requested authentication, without transmitting fragments containing additional information. For example, when a terminal requests authentication for specific system information, the base station may perform the operation of transmitting the original system information corresponding to the specific system information for which the terminal has requested authentication and additional information associated therewith.

[0123] Since the method of the aforementioned base station separating DS into multiple fragments and transmitting it was not considered in existing NR, there was no consideration of the operation performed by the terminal when the terminal acquires system information transmitted in multiple fragments, and the operation performed by the terminal when the terminal fails to acquire system information transmitted in multiple fragments.

[0124] For example, in an NR system, if a terminal fails to acquire an MIB, the terminal may consider the cell to be in a barred state. If the terminal succeeds in acquiring an MIB but fails to acquire SIB1 known from the acquired MIB, the terminal may consider the cell to be in a barred state. In this case, the terminal may perform a cell reselection operation to another cell of the same frequency as the cell.

[0125] According to various embodiments of the present disclosure, the transmission schedule of each fragment may vary depending on the design of the system. Even if the transmission schedule of each fragment varies depending on the design of the system, the terminal can perform authentication of the system information only when it receives all of the multiple fragments corresponding to one original system information. In this regard, the present disclosure may provide operations regarding the acquisition of system information by the terminal.

[0126] FIG. 5 illustrates the operation of a terminal when the terminal according to one embodiment of the present disclosure fails to obtain valid MIB information.

[0127] According to one embodiment of the present disclosure, when asymmetric key-based information authentication for an MIB and the fragments thereof are transmitted from a cell, the terminal may perform a failure handling operation according to OPT 1 and OPT 2 related to the operation of the terminal acquiring MIB information.

[0128] In the present disclosure, regarding the operation of a terminal acquiring MIB information, if a base station transmits data containing original system information and information necessary for the authentication procedure as a segment regardless of the terminal's MIB authentication request, this may be referred to as OPT 1. That is, OPT 1 may mean the case where the terminal intends to receive all the segments including MIB and its associated information for authentication.

[0129] Additionally, in the present disclosure, regarding the operation of a terminal acquiring MIB information, if a base station receives a terminal’s MIB authentication request signal and, in response, transmits data including original system information and information required for the authentication procedure in segments, this may be referred to as OPT 2. That is, OPT 2 may mean the case where the terminal transmits an authentication request signal for MIB to the base station, and the terminal intends to receive all the segments including MIB and its associated information for authentication.

[0130] The original system information in OPT 1 and OPT 2 related to the operation of acquiring the MIB may correspond to the MIB.

[0131] According to one embodiment of the present disclosure, based on the case of OPT 1 related to the operation of the terminal acquiring MIB information, the terminal may perform a handling of failure operation according to cases where it fails to acquire a valid MIB (failure case 1, failure case 2). According to one embodiment of the present disclosure, based on the case of OPT 1 related to the operation of the terminal acquiring MIB information, the terminal may fail to acquire a valid MIB if it fails to receive all data fragments containing all information required for the MIB authentication procedure within a set time, or if the terminal fails to assemble the MIB information or the data fragments containing information required for authentication with the MIB information within a set time. Based on the case of OPT 1 related to the operation of the terminal acquiring MIB information, the case in which the terminal fails to acquire a valid MIB according to the example described above may be referred to as 'failure case 1 (failure case 1 in OPT 1)'.

[0132] According to one embodiment of the present disclosure, in the case of failure case 1 regarding OPT 1 related to the operation of the terminal acquiring MIB information, the terminal may perform at least one of the following operations.

[0133] - The terminal may consider a cell that transmitted a MIB that failed to acquire a valid one as a barred cell.

[0134] - The terminal may discard the MIB that failed to acquire valid valid acquisition stored in the buffer, or fragments of data containing the MIB that failed to acquire valid valid acquisition and all information required for the authentication process.

[0135] - The terminal can perform cell reselection to another cell within the same frequency as the cell that transmitted the MIB that failed to acquire a valid one.

[0136] - The terminal may store within itself the PCI and / or frequency information of the cell that transmitted the MIB for which valid acquisition failed, and information on the cause of failure. Here, the PCI and / or frequency information may include an absolute radio frequency channel number (ARFCN). Additionally, the information on the cause of failure may include information regarding whether the terminal failed to acquire a valid MIB due to a failure to receive the MIB, or whether the terminal failed to acquire a valid MIB due to the terminal failing to assemble a piece of data containing the MIB information or information required for authentication with the MIB information within a specified time.

[0137] According to one embodiment of the present disclosure, based on OPT 1 related to the operation of a terminal acquiring MIB information, even if it does not correspond to failure case 1—that is, even if it successfully receives all pieces of data containing information required for the MIB authentication procedure and successfully assembles the pieces—the terminal may fail to acquire a valid MIB. For example, the terminal may fail to acquire a valid MIB if it fails to pass the authentication procedure for the MIB information. That is, the terminal may fail to acquire a valid MIB if, when performing decryption using the DS, time stamp information, and public key enclosed or associated with the MIB information, the MIB information is corrupted or the decryption fails. Or, for example, the terminal may fail to acquire a valid MIB if the MIB information is corrupted or the decryption fails within a given time. In OPT 1 related to the operation of a terminal acquiring MIB information, the case in which the terminal fails to acquire a valid MIB according to the example described above may be referred to as 'failure case 2 (failure case 2 in OPT 1)'.

[0138] According to one embodiment of the present disclosure, in the case of failure case 2 regarding OPT 1 related to the operation of the terminal acquiring MIB information, the terminal may perform at least one of the following operations.

[0139] - The terminal may consider the cell that transmitted the MIB that failed to acquire a valid one as an FBS (fake base station cell).

[0140] - The terminal may consider a cell that transmitted a MIB that failed to acquire a valid one as a barred cell.

[0141] - The terminal may discard a valid acquisition failed MIB or a data fragment containing all information required for the authentication process that was stored in the buffer and a valid acquisition failed MIB.

[0142] - The terminal can perform cell reselection to another cell within the same frequency as the cell that transmitted the MIB that failed to acquire a valid one.

[0143] - The terminal provides PCI and / or frequency information and cause of failure information of the cell that transmitted the MIB for which valid acquisition failed. Here, the PCI and / or frequency information may include an ARFCN (absolute radio frequency channel number). Additionally, the cause of failure information may include information regarding whether the terminal failed to acquire a valid MIB due to receiving the MIB from the FBS, or due to a failure in MIB authentication.

[0144] According to one embodiment of the present disclosure, based on the case of OPT 2 related to the operation of the terminal acquiring MIB information, the terminal may perform a handling of failure operation according to cases where it fails to acquire a valid MIB (failure case 1, failure case 2). According to one embodiment of the present disclosure, based on OPT 2 related to the operation of the terminal acquiring MIB information, if the terminal fails to receive all data fragments containing all information required for the MIB authentication procedure for a set period of time after transmitting a MIB authentication request signal, or if the terminal fails to assemble the MIB information or the data fragments containing the information required for authentication with the MIB information for a set period of time after transmitting a MIB authentication request signal, the terminal may fail to acquire a valid MIB. In OPT 2 related to the operation of the terminal acquiring MIB information, the case in which the terminal fails to acquire a valid MIB according to the above-described case may be referred to as 'failure case 1 (failure case 1 in OPT 2)'.

[0145] According to one embodiment of the present disclosure, in the case of failure case 1 regarding OPT 2 related to the operation of the terminal acquiring MIB information, the terminal may perform at least one of the following operations.

[0146] - The terminal may consider a cell that transmitted a MIB that failed to acquire a valid one as a barred cell.

[0147] - The terminal may discard the MIB that failed to acquire valid acquisition, or the MIB that failed to acquire valid acquisition and fragments of data containing all information required for the authentication process that were stored in the buffer.

[0148] - The terminal can perform cell reselection to another cell within the same frequency as the cell that transmitted the MIB that failed to acquire a valid one.

[0149] - The terminal may store within itself the PCI and / or frequency information of the cell that transmitted the MIB for which valid acquisition failed, and information on the cause of failure. Here, the PCI and / or frequency information may include an absolute radio frequency channel number (ARFCN). Additionally, the information on the cause of failure may include information regarding whether the terminal failed to acquire a valid MIB due to a failure to receive the MIB, or whether the terminal failed to acquire a valid MIB due to the terminal failing to assemble a piece of data containing the MIB information or information required for authentication with the MIB information within a specified time.

[0150] According to one embodiment of the present disclosure, based on OPT 2 related to the operation of a terminal acquiring MIB information, the terminal may fail to acquire a valid MIB even if it does not correspond to failure case 1, that is, even if it successfully receives all pieces of data containing information required for the MIB authentication procedure and successfully assembles the pieces. For example, the terminal may fail to acquire a valid MIB if it fails to pass the authentication procedure for MIB information. That is, the terminal may fail to acquire a valid MIB if, when performing decryption using the DS, time stamp information, and public key enclosed or associated with the MIB information, the MIB information is corrupted or the decryption fails. Alternatively, for example, the terminal may fail to acquire a valid MIB if the terminal fails to pass the authentication procedure for MIB information within a given time. In OPT 2 related to the operation of a terminal acquiring MIB information, the case in which the terminal fails to acquire a valid MIB according to the example described above may be referred to as 'failure case 2 (failure case 2 in OPT 2)'.

[0151] According to one embodiment of the present disclosure, in the case of failure case 2 regarding OPT 2 related to the operation of the terminal acquiring MIB information, the terminal may perform at least one of the following operations.

[0152] The terminal may consider the cell that transmitted the MIB that failed to acquire a valid one as an FBS (fake base station cell).

[0153] The terminal may consider a cell that transmitted a MIB that failed to acquire a valid one as a barred cell.

[0154] The terminal may discard the MIB that failed to acquire a valid acquisition that was stored in the buffer, or the fragments of data containing the MIB that failed to acquire a valid acquisition and all information required for the authentication process.

[0155] The terminal can perform cell reselection to another cell within the same frequency as the cell that transmitted the MIB that failed to acquire a valid one.

[0156] The terminal may store within itself the PCI and / or frequency information of the cell that transmitted the MIB for which valid acquisition failed, and information on the cause of failure. Here, the PCI and / or frequency information may include an absolute radio frequency channel number (ARFCN). Additionally, the information on the cause of failure may include information regarding whether the terminal failed to acquire a valid MIB due to a failure to receive the MIB from the FBS, or due to a failure in MIB authentication.

[0157] FIG. 6 illustrates the operation of a terminal when the terminal according to one embodiment of the present disclosure fails to obtain valid SIB1 information.

[0158] According to one embodiment of the present disclosure, when a terminal succeeds in acquiring a valid MIB, the terminal may read SIB1 based on the information within the acquired valid MIB and acquire valid SIB1 information.

[0159] According to one embodiment of the present disclosure, when asymmetric key-based information authentication for SIB1 and the corresponding fragments are transmitted from a cell, the terminal may perform a handling of failure operation according to OPT 1 and OPT 2 related to the operation of the terminal acquiring SIB1 information. That is, the terminal may perform the handling of failure operation described above with reference to FIG. 5 when the terminal fails to acquire a valid MIB, and may perform the following operations related to the operation of acquiring SIB1 information when the terminal acquires a valid MIB.

[0160] In the present disclosure, regarding the operation of a terminal acquiring SIB1 information, if a base station transmits data containing original system information and information necessary for the authentication procedure as a segment regardless of the terminal's SIB1 authentication request, it may be referred to as OPT 1. That is, OPT 1 may mean the case where the terminal intends to receive all the segments including SIB1 and its associated information for authentication.

[0161] Additionally, in the present disclosure, regarding the operation of a terminal acquiring SIB1 information, if a base station receives a SIB1 authentication request signal from the terminal and, in response, transmits data including original system information and information necessary for the authentication procedure in segments, this may be referred to as OPT 2. That is, OPT 2 may mean the case where the terminal transmits an authentication request signal for SIB1 to the base station, and the terminal intends to receive all the segments including SIB1 and its associated information for authentication.

[0162] The original system information in OPT 1 and OPT 2 related to the operation of acquiring SIB1 can correspond to SIB1.

[0163] According to one embodiment of the present disclosure, based on the case of OPT 1 associated with the operation of the terminal acquiring SIB1 information, the terminal may perform operations according to cases where the acquisition of a valid SIB1 fails (failure case 1, failure case 2).

[0164] According to one embodiment of the present disclosure, based on OPT 1 associated with the operation of a terminal acquiring SIB1 information, if the terminal fails to receive all data fragments containing all information required for the SIB1 authentication procedure within a set time, or if the terminal fails to assemble SIB1 information or data fragments containing information required for authentication with SIB1 information within a set time, the terminal may fail to acquire a valid SIB1. Based on OPT 1 associated with the operation of a terminal acquiring SIB1 information, the case in which the terminal fails to acquire a valid SIB1 according to the examples described above may be referred to as 'Failure case 1'.

[0165] According to one embodiment of the present disclosure, in the case of failure case 1 regarding OPT 1 related to the operation of the terminal acquiring SIB1 information, the terminal may perform at least one of the following operations.

[0166] - The terminal may consider the cell that transmitted SIB1, which failed to acquire a valid one, as a barred cell.

[0167] - The terminal may discard SIB1 that failed to acquire a valid acquisition that was stored in the buffer, or SIB1 that failed to acquire a valid acquisition and fragments of data containing all information necessary for the authentication process.

[0168] - The terminal can determine cell reselection to another cell based on intra-frequency reselection (IFR) indicators within the previously acquired valid MIB information.

[0169] -- For example, if the IFR indicator in the previously acquired valid MIB information is indicated as allowed (i.e., an indication that if the cell is barred, the terminal can perform cell reselection to another cell on the same frequency as the cell), the terminal can perform cell reselection to another cell on the same frequency as the cell that transmitted the SIB1 for which valid acquisition failed.

[0170] -- On the other hand, for example, if an IFR indicator within previously acquired valid MIB information is indicated as disallowed, the terminal may not perform cell reselection to another cell within the same frequency as this cell.

[0171] - The terminal may store PCI and / or frequency information and failure cause information of this cell within the terminal. Here, the PCI and / or frequency information may include an absolute radio frequency channel number (ARFCN). Additionally, the failure cause information may include information regarding whether the terminal failed to acquire a valid SIB1 because it failed to receive all data fragments containing all information required for the SIB1 authentication procedure within a set time, or whether the terminal failed to acquire a valid SIB1 because it failed to assemble the SIB1 information or the data fragments containing the information required for authentication with the SIB1 information within a set time.

[0172] According to one embodiment of the present disclosure, based on OPT 1 related to the operation of a terminal acquiring SIB1 information, even if it does not correspond to failure case 1—that is, even if it successfully receives all pieces of data containing information required for the SIB1 authentication procedure and successfully assembles the pieces—the terminal may fail to acquire a valid SIB1. For example, if the terminal fails to pass the authentication procedure for SIB1 information, that is, if the SIB1 information is corrupted or decryption fails when decrypted using DS, time stamp information, and public key enclosed or associated with the SIB1 information, the terminal may fail to acquire a valid SIB1. Or, for example, if the SIB1 information is corrupted or decryption fails within a given time, the terminal may fail to acquire a valid SIB1. In OPT 1 related to the operation of a terminal acquiring SIB1 information, the case in which the terminal fails to acquire a valid SIB1 according to the examples described above may be referred to as 'failure case 2'.

[0173] According to one embodiment of the present disclosure, in the case of failure case 2 regarding OPT 1 related to the operation of the terminal acquiring SIB1 information, the terminal may perform at least one of the following operations.

[0174] The terminal may consider the cell that transmitted the SIB1, which failed to acquire a valid one, as an FBS (fake base station cell).

[0175] The terminal may consider the cell that transmitted SIB1, which failed to acquire a valid one, as a barred cell.

[0176] - The terminal may discard the SIB1 that failed to acquire a valid acquisition that was stored in the buffer, or the data fragment containing the SIB1 that failed to acquire a valid acquisition and all information required for the authentication procedure.

[0177] - The terminal can perform cell reselection to another cell within the same frequency as the cell that transmitted the SIB1, for which valid acquisition failed. In the case of failure case 2, the terminal can perform cell reselection to another cell regardless of whether there is an IFR instruction in the MIB. That is, in the case of failure case 2, unlike failure case 1, since the MIB information previously acquired from the cell considered to be the FBS cannot be trusted, the terminal can perform cell reselection to another cell regardless of whether there is an IFR instruction in the MIB.

[0178] - The terminal may store within itself the PCI and / or frequency information and failure cause information of the cell that transmitted the SIB1 for which valid acquisition failed. Here, the PCI and / or frequency information may include an ARFCN (absolute radio frequency channel number). Additionally, the failure cause information may include information regarding whether the terminal failed to acquire a valid SIB1 due to receiving the SIB1 from the FBS, or due to a failure in authentication of the SIB1.

[0179] According to one embodiment of the present disclosure, based on the case of OPT 2 associated with the operation of the terminal acquiring SIB1 information, the terminal may perform operations according to cases where the acquisition of a valid SIB1 fails (failure case 1, failure case 2).

[0180] According to one embodiment of the present disclosure, based on OPT 2 related to the operation of a terminal acquiring SIB1 information, if the terminal fails to receive all data fragments containing all information required for the SIB1 authentication procedure for a set period of time after transmitting a SIB1 authentication request signal, or if the terminal fails to assemble SIB1 information or data fragments containing information required for authentication with SIB1 information for a set period of time after transmitting a SIB1 authentication request signal, the terminal may fail to acquire a valid SIB1. In OPT 2 related to the operation of a terminal acquiring SIB1 information, the case in which the terminal fails to acquire a valid SIB1 according to the above-described case may be referred to as failure case 1.

[0181] According to one embodiment of the present disclosure, for a failure case 1 regarding OPT 2 related to an operation in which the terminal obtains SIB1 information, the terminal may perform at least one of the following operations.

[0182] - The terminal may consider the cell that transmitted SIB1, which failed to acquire a valid one, as a barred cell.

[0183] - The terminal may discard fragments of data containing all information required for the authentication procedure of SIB1 that failed to acquire a valid acquisition, or SIB1 that failed to acquire a valid acquisition, which were stored in the buffer.

[0184] - The terminal can determine cell reselection to another cell based on intra-frequency reselection (IFR) indicators within the previously acquired valid MIB information.

[0185] -- For example, if the IFR indicator in the previously acquired valid MIB information is indicated as allowed (i.e., an indication that if the cell is barred, the terminal can perform cell reselection to another cell on the same frequency as the cell), the terminal can perform cell reselection to another cell on the same frequency as the cell that transmitted the SIB1 for which valid acquisition failed.

[0186] -- On the other hand, for example, if an IFR indicator within previously acquired valid MIB information is indicated as disallowed, the terminal may not perform cell reselection to another cell within the same frequency as this cell.

[0187] - The terminal may store PCI and / or frequency information and failure cause information of this cell within the terminal. Here, the PCI and / or frequency information may include an absolute radio frequency channel number (ARFCN). Additionally, the failure cause information may include information regarding whether the terminal failed to acquire a valid SIB1 because it failed to receive all data fragments containing all information required for the SIB1 authentication procedure within a set time, or whether the terminal failed to acquire a valid SIB1 because it failed to assemble the SIB1 information or the data fragments containing the information required for authentication with the SIB1 information within a set time.

[0188] According to one embodiment of the present disclosure, based on OPT 2 related to the operation of a terminal acquiring SIB1 information, the terminal may fail to acquire a valid SIB1 even if it does not correspond to failure case 1, that is, even if it successfully receives all pieces of data containing information required for the SIB1 authentication procedure and successfully assembles the pieces. For example, the terminal may fail to acquire a valid SIB if it fails to pass the authentication procedure for SIB1 information, that is, if the SIB1 information is corrupted or fails to decrypt when decrypted using the DS, time stamp information, and public key enclosed or associated with the SIB1 information. Alternatively, for example, if the terminal fails to pass the authentication procedure for SIB1 information within a given time, the terminal may fail to acquire a valid SIB1. In OPT 2 related to the operation of a terminal acquiring SIB1 information, the case in which the terminal fails to acquire a valid SIB1 according to the examples described above may be referred to as 'failure case 2'.

[0189] According to one embodiment of the present disclosure, in the case of failure case 2 regarding OPT 2 related to the operation of the terminal acquiring SIB1 information, the terminal may perform at least one of the following operations.

[0190] - The terminal may consider the cell that transmitted the SIB1, which failed to acquire a valid one, as an FBS (fake base station cell).

[0191] - The terminal may consider the cell that transmitted SIB1, which failed to acquire a valid one, as a barred cell.

[0192] - The terminal may discard fragments of data containing all information required for the authentication procedure of SIB1 that failed to acquire a valid acquisition, or SIB1 that failed to acquire a valid acquisition, which were stored in the buffer.

[0193] - The terminal can perform cell reselection to another cell within the same frequency as the cell that transmitted the SIB1, for which valid acquisition failed. In the case of failure case 2, the terminal can perform cell reselection to another cell regardless of whether there is an IFR instruction in the MIB. That is, in the case of failure case 2, unlike failure case 1, the MIB information previously acquired from the cell considered to be an FBS cannot be trusted, so the terminal can perform cell reselection to another cell regardless of whether there is an IFR instruction in the MIB.

[0194] - The terminal may store within itself the PCI and / or frequency information and failure cause information of the cell that transmitted the SIB1 for which valid acquisition failed. Here, the PCI and / or frequency information may include an ARFCN (absolute radio frequency channel number). Additionally, the failure cause information may include information regarding whether the terminal failed to acquire a valid SIB1 due to receiving the SIB1 from the FBS, or due to a failure in authentication of the SIB1.

[0195] In various embodiments of the present disclosure, the terminal may report failure information to a base station or network while storing failure information that occurred upon acquiring MIB and / or SIB1. Since the system information itself is validly applicable to all terminals in an inactive / idle / connected state, if a failure occurs at the time of attempting to acquire system information, the terminal may report information related to the failure to the base station or network. By acquiring information related to the failure, the base station or network may adjust factors related to system information transmission to increase the reliability of system information transmission. Additionally, if an FBS cell is detected at the time the terminal attempts to acquire system information, the terminal may report information regarding the detection of the FBS cell to the base station or network. By acquiring this information, the base station or network may control the terminal to avoid the reported FBS cell.

[0196] For this purpose, the present disclosure may provide an operation in which a terminal reports to a base station or a network stored information regarding a failure to acquire system information.

[0197] In various embodiments of the present disclosure, the terminal may perform an operation of acquiring system information according to the state of the terminal and an operation of reporting failure information to a network and a base station.

[0198] Case 1. When the terminal is in an inactive state or idle mode

[0199] If the terminal attempts to obtain MIB or SIB1 information from the previous cell during the cell selection or re-selection process, and fails to obtain a valid MIB and / or a valid SIB1, the terminal stores the failure information and may perform cell re-selection to a different cell other than the cell. Accordingly, if the terminal camps in the re-selected cell, the terminal may perform the following actions.

[0200] Opt 1. The terminal can perform an RRC resumption (RRC connection resume, or RRC resume) or an RRC connection setup (RRC connection setup or RRC setup) on the corresponding camping cell.

[0201] According to one embodiment, when the terminal transmits an RRC resume request or RRC connection setup request message to a camping cell, the terminal may also transmit the reason for the RRC resume or RRC connection setup. The reason for the RRC resume or RRC connection setup may include information stored in the terminal indicating a failure to acquire system information previously performed by the terminal.

[0202] According to one embodiment, information stored in a terminal may include specific reasons why the terminal failed to acquire system information, such as failure to receive fragments of MIB or SIB1, failure to combine, failure to receive MIB / SIB1 information from FBS, or failure to authenticate MIB / SIB1. Additionally, information stored in the terminal may include PCI and cell frequency information (e.g., AFRCN) as information of the cell where the failure occurred.

[0203] Hereinafter, in relation to Opt 1, a signaling procedure for transmitting information stored in a terminal to a base station or network is described in detail according to various embodiments of the present disclosure.

[0204] FIG. 7 illustrates a signal procedure (Opt 1-1) in which information stored in a terminal according to one embodiment of the present disclosure is transmitted to a base station or network.

[0205] Opt 1-1. A terminal may transmit to a base station or network an RRC resume request or an RRC connection setup request transmitted by the terminal to a valid cell, including an indicator indicating the cause of failure to acquire system information as information indicating the reason for RRC resume or RRC connection setup. A cell that receives an RRC resume request message or an RRC connection setup request message from the terminal may transmit an RRC resume or RRC connection setup message to the terminal.

[0206] According to one embodiment, a terminal that receives an RRC resume request message or an RRC connection setup request message from a base station may apply the information within the message received from the cell and transmit an RRC resume complete message or an RRC connection setup complete message to the cell. In this case, the terminal may transmit to the cell, along with the RRC resume complete message or the RRC connection setup complete message, an indicator that the cell stores information related to the failure to acquire system information.

[0207] According to one embodiment, a base station of a cell that receives an RRC resume complete message or an RRC connection setup complete message from a terminal may transmit a DL RRC message to the terminal that includes a request for logged failure info, which, if necessary, requests information related to the failure to acquire the relevant system information. (This message may be an existing message or a new message.)

[0208] According to one embodiment, a terminal that receives a DL RRC message from a base station may transmit information related to a failed acquisition of stored system information (logged failure info) to the base station via a UL RRC message. Here, the UL RRC message may be an existing UL RRC message or a new message.

[0209] According to one embodiment, a base station that receives a UL RRC message containing information regarding failure to acquire system information may add information about a cell that failed to transmit system information as setting information regarding a measurement object among the measurement setting information of terminals in a connection mode state supported by the base station's cell. For example, the base station may add or update information about a cell that failed to transmit system information to an excluded cell list. As a result, the base station may cause a terminal to exclude the measurement of a cell that failed to transmit system information. Additionally, the base station may allow terminals in an idle / inactive state to exclude a cell that failed to transmit system information from the measurement target by adding information about a cell that failed to transmit system information to the excluded cell list as information about a cell selected / reselected target cell within the base station's system information.

[0210] According to one embodiment, a base station may transmit information about a cell that failed to transmit system information to a SON (self-organizing networks) / MDT (minimization of drive tests) server or a network entity of a core network that performs a role similar to a SON / MDT server, thereby enabling the entity to provide information about the FBS cell to surrounding cells. As a result, the base station may update information about the cell that is the target of measurement or the target of cell selection / reselection in the system information, thereby enabling the terminal to avoid measurement and connection to the cell that failed to transmit system information.

[0211] FIG. 8 illustrates a signal procedure (Opt 1-2) in which information stored in a terminal according to one embodiment of the present disclosure is transmitted to a base station or network.

[0212] Opt 1-2. A terminal may transmit an RRC resume request message or an RRC connection setup request message transmitted by the terminal to a valid cell, including an indicator indicating the cause of failure to obtain system information as information indicating the reason for RRC resume or RRC connection setup.

[0213] According to one embodiment, a cell that receives an RRC resume request message or an RRC connection setup request message from a terminal may transmit an RRC resume message or an RRC connection setup message to the terminal, including an indicator to report information stored due to failure to acquire system information indicated in the RRC resume message or the RRC connection setup message.

[0214] According to one embodiment, a terminal that receives an indicator from a cell to report information stored due to failure to acquire system information may include the information stored in the terminal when the terminal fails to acquire system information in an RRC resume complete or RRC connection setup complete message and transmit it.

[0215] According to one embodiment, a base station that receives an RRC connection setup completion message may add information about a cell that failed to transmit system information as setting information regarding a measurement target among the measurement setting information of terminals in a connection mode state supported by the base station's cell. The operation of the base station adding information about a cell that failed to transmit system information as setting information regarding a measurement target can be understood in the same way as the description of OPT 1-1 above. For example, the base station may add or update information about a cell that failed to transmit system information to an excluded cell list. As a result, the base station may cause a terminal to exclude the measurement of the corresponding cell. Additionally, the base station may allow terminals in an idle / inactive state to exclude a cell that failed to transmit system information from the measurement target by adding information about a cell that failed to transmit system information to the excluded cell list as information about a cell selected / reselected target cell within the base station's system information.

[0216] According to one embodiment, a base station may transmit information about a cell that failed to transmit system information to a SON / MDT server or a network entity performing a role similar to a SON / MDT server, thereby enabling the entity to provide information about the FBS cell to surrounding cells. As a result, the base station may enable a terminal to avoid measurement and connection to the cell that failed to transmit system information by updating information about the measurement target or the cell selection / reselection target cell in the system information.

[0217] FIG. 9 illustrates a signal procedure (Opt 1-3) in which information stored in a terminal according to one embodiment of the present disclosure is transmitted to a base station or network.

[0218] Opt 1-3. The terminal may transmit an RRC resume request message or an RRC connection setup request message that the terminal transmits to a valid cell, including information indicating the reason for RRC resumption or RRC connection setup and an indicator indicating the cause of failure to obtain system information. Additionally, in the case of Opt 1-3, the terminal may additionally transmit an RRC resume request message or an RRC connection setup request message that the terminal transmits to the cell, including information stored in the message.

[0219] The cell can send an RRC resume message or an RRC connection setup message to the terminal.

[0220] The terminal receives and applies an RRC resume message or an RRC connection setup message transmitted from the cell, and can send an RRC resume complete message or an RRC connection setup complete message to the cell.

[0221] According to one embodiment, a base station that receives an RRC resumption completion message or an RRC connection setup completion message may add information about a cell that failed to transmit system information as setting information regarding a measurement target among the measurement setting information of terminals in a connection mode state supported by the base station's cell. The operation of the base station adding information about a cell that failed to transmit system information as setting information regarding a measurement target can be understood in the same way as the description of OPT 1-1 and OPT 1-2 above. For example, the base station may add or update information about a cell that failed to transmit system information to an excluded cell list. As a result, the base station may cause a terminal to exclude the measurement of the corresponding cell. Additionally, the base station may allow terminals in an idle / inactive state to exclude a cell that failed to transmit system information from the measurement target by adding information about a cell that failed to transmit system information to the excluded cell list as information about a cell selected / reselected target cell within the base station's system information.

[0222] According to one embodiment, a base station may transmit information about a cell that failed to transmit system information to a SON / MDT server or a network entity performing a role similar to a SON / MDT server, thereby enabling the entity to provide information about the FBS cell to surrounding cells. As a result, the base station may update information about the measurement target or the cell selection / reselection target cell in the system information, thereby enabling the terminal to avoid measurement and connection to the cell that failed to transmit system information.

[0223] FIG. 10 illustrates a flowchart of a case (Opt 2) in which information related to a failure to acquire system information is reported through an SDT function according to one embodiment of the present disclosure.

[0224] In the present disclosure, regarding a method for a terminal to report information related to a failure to acquire system information to a base station, OPT 2 may mean a case where the terminal reports information related to a failure to acquire system information to the base station through a small data transmission (SDT) function, regardless of the RRC resumption or RRC connection setup procedure. That is, OPT 2 may mean a case where the terminal receives SDT-related configuration information in advance from the base station when transitioning to an idle state or an inactive state.

[0225] According to one embodiment, SDT-related setting information may include at least one of the following information.

[0226] - Information regarding whether SDT transmission based on CG (configured grant) is possible for specific cells

[0227] -- Information regarding uplink grant resources by specific cell

[0228] -- Downlink signal threshold in the cell for using the uplink grant (SDT can be used only if the threshold is exceeded.)

[0229] - Settings regarding whether data transmission using RACH (random access channel) is possible for specific cells (i.e., without setting an uplink grant, resource information can be obtained by monitoring the schedule information of the uplink grant (UL grant) designated by the cell and used for transmission by the terminal).

[0230] According to one embodiment, when a terminal receives information from a base station and transitions to an idle or inactive mode, and then selects or re-selects a specific cell, if the terminal fails to obtain valid system information, the terminal can store information associated with the failure to obtain system information and perform cell re-selection to another cell.

[0231] According to one embodiment, when a terminal successfully acquires valid system information from a cell and camps, the terminal can identify whether CG SDT or RACH SDT is possible in that cell. Subsequently, the terminal can perform a possible SDT operation. If CG SDT is possible, the terminal can transmit stored system information failure information by utilizing resources for CG SDT in that cell if the cell's DL signal is strong relative to a given DL signal threshold. If RACH SDT is possible, when the terminal transmits an RA preamble to the cell, the cell can transmit a random access response (RAR) to the terminal. The RAR may include information on uplink grant resources (frequency / time). Additionally, the RAR may include a timing advance (TA) value. The terminal can transmit system information failure information stored in the terminal to the base station by utilizing available resources and applying the TA value. For example, the terminal can transmit information regarding the failure of system information acquisition to the base station by including it in Msg 3.

[0232] According to one embodiment, a base station that receives a message from a terminal may add information about a cell that failed to transmit system information as setting information regarding a measurement target among the measurement setting information of terminals in a connection mode state serving in the base station's cell. For example, the base station may add or update information about a cell that failed to transmit system information to an excluded cell list. As a result, the base station may cause the terminal to exclude the measurement of a cell that failed to transmit system information. Additionally, by adding information about a cell that failed to transmit system information to the excluded cell list as information about a cell selected / re-selected target cell within the base station's system information, the base station may cause terminals in an idle / inactive state to exclude a cell that failed to transmit system information from the measurement target.

[0233] According to one embodiment, a base station may transmit information about a cell that failed to transmit system information to a SON / MDT server or a network entity performing a similar role, thereby enabling the entity to provide information about the FBS cell to surrounding cells. As a result, the base station may enable a terminal to avoid measurement and connection to the cell that failed to transmit system information by updating information about the measurement target or the cell selection / reselection target cell in the system information.

[0234] FIG. 11 illustrates a flowchart of an operation in which a terminal in a connected mode state reports failure information according to one embodiment of the present disclosure.

[0235] According to one embodiment, a terminal in a connected mode state can perform functions for relations with neighboring cells. For example, a serving cell may command the terminal to obtain CGI and / or PLMN information for a cell of a specific PCI (e.g., cell 2 in FIG. 11). Such a command may be given as a report CGI indicator or a corresponding indicator within the report configuration of the measurement settings. Additionally, a PCI may be given as a measurement object as target cell information. The terminal may locate the cell of the PCI indicated at the frequency of the corresponding measurement object and read the CGI information present in the SIB1 of that cell.

[0236] According to one embodiment, the terminal may attempt to read MIB and SIB1 by checking the SSB of the corresponding cell corresponding to the frequency to be measured for this purpose. At this time, if the terminal fails to obtain valid information of MIB or SIB1, the terminal may store failure-related information as a case of failure to obtain system information, as described above.

[0237] According to one embodiment, failure-related information stored in the terminal may be transmitted to the serving cell via a measurement report or a corresponding UL RRC message or UL MAC CE / UCI.

[0238] According to one embodiment, in accordance with the existing configuration for reporting reportCGI, a specific timer exists, and the terminal may continue attempting to acquire the CGI until the timer expires. When the timer expires, the terminal may not report the acquired CGI or may report the result of the acquisition failure. However, in this case, a problem may arise in which information regarding the acquisition failure cannot be promptly reported to the network even when the acquisition of system information fails due to the presence of an FBS cell. According to one embodiment of the present disclosure, when a failure to acquire system information occurs, the terminal may report the result to the serving cell immediately without waiting for the timer to expire. Since the cause of failure to acquire system information includes the presence of an FBS cell in addition to the cell's wireless signal being weak, it may be important for the terminal to quickly report to the network when a failure to acquire system information occurs.

[0239] According to one embodiment, a base station that receives a message from a terminal may add information about a cell that failed to transmit system information as setting information regarding a measurement target among the measurement setting information of terminals in a connection mode state serving in the base station's cell. For example, the base station may add or update information about a cell that failed to transmit system information to an excluded cell list. As a result, the base station may cause the terminal to exclude the measurement of a cell that failed to transmit system information. Additionally, by adding information about a cell that failed to transmit system information to the excluded cell list as information about a cell selected / re-selected target cell within the base station's system information, the base station may cause terminals in an idle / inactive state to exclude a cell that failed to transmit system information from the measurement target.

[0240] According to one embodiment, a base station may transmit information about a cell that failed to transmit system information to a SON / MDT server or a network entity performing a similar role, thereby enabling the entity to provide information about the FBS cell to surrounding cells. As a result, the base station may enable a terminal to avoid measurement and connection to the cell that failed to transmit system information by updating information about the measurement target or the cell selection / reselection target cell in the system information.

[0241] Methods according to the embodiments described in the claims or specification of the present invention may be implemented in the form of hardware, software, or a combination of hardware and software.

[0242] 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 embodiments described in the claims or specification of the present invention.

[0243] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), magnetic disc storage devices, CD-ROM (Compact Disc-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.

[0244] In addition, the above program may be stored on an attachable storage device that can be accessed via a communication network such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. Such a storage device may be connected to a device performing an embodiment of the present invention 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 invention.

[0245] In the specific embodiments of the present invention described above, the components included in the invention 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 invention is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed in the singular form, or even if a component is expressed in the singular form, it may be composed in the plural form.

[0246] Meanwhile, although specific embodiments have been described in the detailed description of the present invention, it is understood that various modifications are possible within the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof.

Claims

1. A method performed by a terminal (user equipment) in a wireless communication system, wherein the method comprises: A step of identifying failure to acquire system information divided into multiple segments transmitted from a first base station; A step of discarding at least some or all of the received segments among the plurality of segments; A step of storing acquisition failure information including the reason for the failure to acquire the above-mentioned system information; and A method comprising the step of performing a cell reselection procedure to a second base station.

2. In Paragraph 1, The above system information includes a digital signature to which a security algorithm has been applied to the original system information, the original system information, and time information. A method in which the above original system information includes either a master information block (MIB) or a system information block (SIB).

3. In paragraph 1, the step of identifying the failure of the acquisition is, Failure to receive at least some of the above plurality of segments, Failure of assembly of the above plurality of segments, and A method for identifying any one of the failures of authentication of the above system information.

4. In Paragraph 1, A method in which the above system information is received through a response message from the first base station to an authentication request of the terminal.

5. In claim 1, the above method is, A step of transmitting an RRC (radio resource control) resume request message or an RRC setup request message to the second base station, the message including an indicator that indicates the reason for the acquisition failure; A step of receiving an RRC Resume message or an RRC setup message from the second base station; A step of transmitting an RRC resume complete message or an RRC setup complete message to the second base station, including whether the reason for the acquisition failure can be provided; A step of receiving an RRC DL (downlink) message including a request for the acquisition failure information from the second base station; and A method comprising the step of transmitting an RRC UL (uplink) message containing the acquisition failure information to the second base station.

6. In claim 1, the above method is, A step of transmitting an RRC resume request or RRC setup request message to the second base station, the message including an indicator that indicates the reason for the acquisition failure; A step of receiving an RRC Resume message or an RRC setup message including a request for the acquisition failure information from the second base station; and A method comprising the step of transmitting an RRC resume complete message or an RRC setup complete message containing the acquisition failure information to the second base station.

7. In claim 1, the above method is, A step of transmitting to the second base station an RRC resume request message or an RRC setup request message including an indicator indicating the reason for the acquisition failure and the acquisition failure information; A step of receiving an RRC Resume message or an RRC setup message from the second base station; and A method comprising the step of transmitting an RRC resume complete message or an RRC setup complete message to the second base station.

8. In claim 1, the above method is, A step of identifying whether RACH (random access channel) SDT is possible at the second base station based on SDT (small data transmission) setting information; and A method comprising the step of transmitting Msg3 containing the acquisition failure information to the second base station based on the above identification result.

9. In paragraph 1, the above method is, A step of receiving measurement setting information instructing the second base station to report a CGI (cell global identifier) ​​for the first base station; and A method further comprising the step of reporting the above-mentioned acquisition failure information.

10. In Paragraph 9, The step of reporting the above-mentioned acquisition failure information is, A method of transmitting a UL RRC message or a UL MAC CE message or UCI (uplink control information) containing the acquisition failure information to the second base station.

11. In a terminal (user equipment) of a wireless communication system, the terminal, transceiver; and It includes at least one processor coupled to the above transceiver, and the at least one processor, Identifying failure to acquire system information divided into multiple segments transmitted from a first base station, and Discard at least some or all of the received segments among the plurality of segments above, and It stores acquisition failure information including the reason for the failure to acquire the above system information, and A terminal that performs a cell reselection procedure to a second base station.

12. In Paragraph 11, The above system information includes a digital signature to which a security algorithm has been applied to the original system information, the original system information, and time information. A terminal in which the above original system information includes either a master information block (MIB) or a system information block (SIB).

13. In paragraph 1, the at least one processor is, Failure to receive at least some of the above plurality of segments, Failure of assembly of the above plurality of segments, and A terminal that identifies any one of the failures of authentication of the above-mentioned system information.

14. In Paragraph 11, A terminal in which the above system information is received through the response message of the first base station to the authentication request of the terminal.

15. In claim 11, the at least one processor is, Transmitting an RRC (radio resource control) resume request message or an RRC setup request message including an indicator indicating the reason for the acquisition failure to the second base station, and Receive an RRC Resume message or an RRC setup message from the second base station, and Transmit an RRC resume complete message or an RRC setup complete message including whether the reason for the acquisition failure can be provided to the second base station, and Receives an RRC DL (downlink) message including a request for the acquisition failure information from the second base station, A terminal that transmits an RRC UL (uplink) message containing the acquisition failure information to the second base station.

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