Method and device for managing anr in wireless communication system

Abstract

Proposed in the present specification are procedures / configurations such as an extended neighbor relation table (NRT), NG interface setup information, a measurement report, and the like so as to manage a neighbor relation list by distinguishing terrestrial networks (TN) from satellite networks for a smooth handover operation between the terrestrial networks and non-terrestrial networks (NTN).

Description

Method and device for managing ANR in a wireless communication system

[0001] The present invention relates to wireless communication, and more particularly, to a method and apparatus for managing ANR in a wireless communication system.

[0002] Recently, with the rapid proliferation of smartphones and Internet of Things (IoT) devices, the amount of information exchanged via communications networks is increasing. Accordingly, next-generation wireless access technologies need to consider environments that provide faster services to more users than existing communication systems (or existing radio access technologies), such as enhanced mobile broadband communication. To this end, the design of communication systems that consider Machine Type Communication (MTC), which connects multiple devices and objects to provide services, is being discussed. Furthermore, the design of communication systems that consider services and / or terminals sensitive to communication reliability and / or latency (e.g., Ultra-Reliable and Low Latency Communication (URLLC)) is also being discussed.

[0003] A non-terrestrial network (NTN) refers to a wireless network formed using satellites (e.g., geostationary satellites (GEO, GSO, etc.) / low earth orbit satellites (LEO)). Based on the NTN network, coverage expansion and highly reliable network services can be possible. For example, the NTN can be formed alone, or a wireless communication system can be formed in combination with a conventional terrestrial network. For example, the NTN network can be formed by i) a link between a satellite and a terminal, ii) a link between satellites, and iii) a link between a satellite and a gateway. Meanwhile, in this specification, the NTN considers a network utilizing satellites as a main embodiment, but the proposed method related to NTN proposed in this specification can be applied not only to satellites but also to High Altitude Pseudo Satellites (HAPS), Unmanned Aerial Vehicles (UAVs), etc.

[0004] ANR or ANR function refers to the function of requesting the UE / terminal that is currently in RRC_CONNECTED state with the base station to report information related to neighboring cells existing in the vicinity, and managing the NRT (Neighbor Relation Table) or NCRT (Neighbor Cell Relation Table), which is a table that stores information related to neighboring cells required when the base station instructs a handover (HO).

[0005] This specification proposes an improved ANR management method and a device using the method in accordance with the introduction of NTN in a wireless communication system.

[0006] According to one embodiment, a method performed by a base station in a wireless communication system is proposed, the method comprising: transmitting a report request message to a terminal, receiving a report response message from the terminal based on the report request message, and modifying an NCRT (Neighbor Cell Relation Table) based on the report response message, wherein the report response message includes a network type indicator for a network type of a neighboring base station of the terminal, the network type indicator indicating whether the neighboring base station is a TN (Terrestrial Network) base station or an NTN (Non-Terrestrial Network) base station, and the NCRT including a network type field indicating, for each of a plurality of base stations, whether the base station is a TN base station or an NTN base station.

[0007] Here, based on the fact that the identifier for the neighboring base station included in the measurement report message transmitted by the terminal to the base station does not exist in the NCRT, the base station transmits the report request message to the terminal, and based on the fact that the neighboring base station is not included in the NCRT, the base station can add the neighboring base station to the NCRT.

[0008] Here, based on the fact that the report response message does not include the network type indicator, the base station may determine the neighboring base station to be a TN base station.

[0009] Here, the base station transmits an NG setup message including a network type field indicating whether the network type is TN or NTN to an AMF (Access and Mobility Management Function) entity connected to the base station, and based on the base station being a TN base station, the AMF may be an AMF for TN, and based on the base station being an NTN base station, the AMF may be an AMF for NTN.

[0010] Here, the report request message is included in an RRC connection reconfiguration message, the terminal is in an RRC_CONNECTED state with respect to the base station, and the base station can store and manage the NCRT.

[0011] Here, the report response message includes at least one of identifier information, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network) for the neighboring base station, and at least one of identifier information, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network) for the neighboring base station included in the report response message may be included in system information for the neighboring base station.

[0012] Here, based on the system information including an NTN-only access restriction indicator for the neighboring base station and the NTN-only access restriction indicator indicating access restriction, the neighboring base station is determined to be a TN base station; based on the system information including the NTN-only access restriction indicator and the NTN-only access restriction indicator indicating access permission, the neighboring base station is determined to be a NTN base station; and based on the system information not including the NTN-only access restriction indicator, the neighboring base station can be determined to be a TN base station.

[0013] According to another embodiment, a proposed base station includes one or more memories storing commands; one or more transceivers; and one or more processors connecting the one or more memories and the one or more transceivers, wherein the one or more processors execute the commands to transmit a report request message to a terminal, receive a report response message from the terminal based on the report request message, and modify an NCRT (Neighbor Cell Relation Table) based on the report response message, wherein the report response message includes a network type indicator for a network type of a neighboring base station of the terminal, the network type indicator indicating whether the neighboring base station is a TN (Terrestrial Network) base station or an NTN (Non-Terrestrial Network) base station, and the NCRT includes a network type field indicating, for each of a plurality of base stations, whether the base station is a TN base station or an NTN base station.

[0014] Here, based on the fact that the identifier for the neighboring base station included in the measurement report message transmitted by the terminal to the base station does not exist in the NCRT, the base station transmits the report request message to the terminal, and based on the fact that the neighboring base station is not included in the NCRT, the base station can add the neighboring base station to the NCRT.

[0015] Here, based on the fact that the report response message does not include the network type indicator, the base station may determine the neighboring base station to be a TN base station.

[0016] Here, the base station transmits an NG setup message including a network type field indicating whether the network type is TN or NTN to an AMF (Access and Mobility Management Function) entity connected to the base station, and based on the base station being a TN base station, the AMF may be an AMF for TN, and based on the base station being an NTN base station, the AMF may be an AMF for NTN.

[0017] Here, the report request message is included in an RRC connection reconfiguration message, the terminal is in an RRC_CONNECTED state with respect to the base station, and the base station can store and manage the NCRT.

[0018] Here, the report response message includes at least one of identifier information, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network) for the neighboring base station, and at least one of identifier information, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network) for the neighboring base station included in the report response message may be included in system information for the neighboring base station.

[0019] Here, based on the system information including an NTN-only access restriction indicator for the neighboring base station and the NTN-only access restriction indicator indicating access restriction, the neighboring base station is determined to be a TN base station; based on the system information including the NTN-only access restriction indicator and the NTN-only access restriction indicator indicating access permission, the neighboring base station is determined to be a NTN base station; and based on the system information not including the NTN-only access restriction indicator, the neighboring base station can be determined to be a TN base station.

[0020] According to another embodiment, a method performed by a terminal in a wireless communication system is characterized in that the method comprises: receiving a report request message from a base station, and transmitting a report response message to the base station based on the report request message, wherein the report response message is used in a Neighbor Cell Relation Table (NCRT) managed by the base station, and based on the report response message including a network type indicator for a network type of a neighboring base station of the terminal, the network type indicator indicates whether the neighboring base station is a TN (Terrestrial Network) base station or an NTN (Non-Terrestrial Network) base station, and the NCRT includes a network type field indicating, for each of a plurality of base stations, whether the base station is a TN base station or an NTN base station.

[0021] Here, based on the fact that the identifier for the neighboring base station included in the measurement report message transmitted by the terminal to the base station does not exist in the NCRT, the terminal receives the report request message from the base station, and based on the fact that the neighboring base station is not included in the NCRT, information about the neighboring base station can be added to the NCRT.

[0022] Here, the terminal receives request information requesting identifier information of the neighboring base station from the base station, and in response to the request information, the terminal can transmit at least one of the identifier information and the location information of the terminal to the base station.

[0023] Here, before the request information is transmitted, the terminal transmits measurement report information to the base station, and the measurement report information includes a PCI (Physical Cell Identifier) ​​for the neighboring base station, and the request information can be transmitted based on the measurement report information.

[0024] Here, the report request message is included in an RRC connection reconfiguration message, and the terminal may be in an RRC_CONNECTED state with respect to the base station.

[0025] Here, the report response message includes at least one of identifier information, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network) for the neighboring base station, and at least one of identifier information, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network) for the neighboring base station included in the report response message may be included in system information for the neighboring base station.

[0026] According to this specification, the efficiency of NCRT management considering NTN is increased, and further, network efficiency is increased due to the introduction of NTN, such as NTN / TN handover. In addition, according to this specification, the terrestrial network and satellite network where ANR is operated can be linked / integrated, and a dynamic and energy-constrained satellite base station can efficiently operate ANR. In addition, the burden of ANR processing on terrestrial base stations and OAM is reduced by managing and updating the global NCRT in a single satellite constellation. In addition, the NCRT table size can be maintained at a certain level from the perspective of each satellite base station, which reduces the burden on the satellite base station and reduces the table search time in handover and ANR procedures.

[0027] The effects that can be achieved through specific examples of this specification are not limited to the effects listed above. For example, a person with ordinary skill in the relevant technical field may understand or derive various technical effects from this specification. Accordingly, the specific effects of this specification are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of this specification.

[0028] The following drawings are intended to illustrate specific examples of the present specification. The names of specific devices and the names of specific signals, messages, and fields depicted in the drawings are provided for illustrative purposes only, and the technical features of this specification are not limited to the specific names used in the drawings.

[0029] FIG. 1 is a conceptual diagram illustrating a wireless communication system according to one embodiment of the present invention.

[0030] FIG. 2 is an exemplary diagram showing an NR system to which a data transmission method according to one embodiment of the present invention can be applied.

[0031] FIG. 3 is a diagram for explaining a resource grid supported by a wireless access technology to which the present invention can be applied.

[0032] FIG. 4 is a diagram for explaining a bandwidth part supported by a wireless access technology to which the present invention can be applied.

[0033] FIG. 5 is a diagram illustrating an example of a synchronization signal block in a wireless access technology to which the present invention can be applied.

[0034] Figure 6 is a diagram for explaining non-terrestrial networks (NTN, hereinafter referred to as NTN).

[0035] Figure 7 illustrates an example of a scenario in which TN base stations and NTN base stations coexist.

[0036] FIG. 8 illustrates an example of a TN-NTN interworking architecture according to one embodiment of the present specification.

[0037] Figure 9 illustrates an example of a mobile communication network structure in which 5G TN and 5G NTN networks are integrated.

[0038] FIG. 10 is a diagram illustrating an example of ANR-based interaction between a base station and an Operation, Administration and Management (OAM) according to one embodiment of the present specification.

[0039] FIG. 11 is a flowchart of an example of an NRT management method according to one embodiment of the present specification.

[0040] FIG. 12 illustrates an example of an NCRT management method performed by a base station according to one embodiment of the present specification.

[0041] FIG. 13 illustrates an example of a procedure for acquiring an NR Cell Global Identifier (NCGI) according to one embodiment of the present specification.

[0042] Figure 14 is a flowchart illustrating an example of message exchange for TNL address discovery between a base station and an AMF.

[0043] FIG. 15 illustrates an example of a TNL address acquisition procedure of AMF according to one embodiment of the present specification.

[0044] FIG. 16 illustrates an example of a TNL address request procedure according to one embodiment of the present specification.

[0045] Figure 17 illustrates an example of the procedure when the NTN AMF does not have the TNL address of a specific TN base station requested.

[0046] Figure 18 illustrates another example of the procedure when the NTN AMF does not have the TNL address of the specific TN base station requested.

[0047] FIG. 19 is a flowchart of an example of a method performed by a communication device according to one embodiment of the present specification.

[0048] FIG. 20 illustrates an example of a case where NTN cell coverage and multiple TN cell coverages overlap according to one embodiment of the present specification.

[0049] FIG. 21 is a flowchart of an example of an ANR management method according to one embodiment of the present specification.

[0050] FIG. 22 is a drawing for explaining an example of an ANR management method according to one embodiment of the present specification.

[0051] FIG. 23 is a flowchart of an example of a method performed by a base station according to one embodiment of the present specification.

[0052] FIG. 24 is a flowchart of an example of an ANR management method according to one embodiment of the present specification.

[0053] FIG. 25 is a flowchart of an example of an ANR management method according to one embodiment of the present specification.

[0054] FIG. 26 illustrates an example of a local NCRT and a global NCRT according to one embodiment of the present specification.

[0055] FIG. 27 is a diagram of another example of ANR-based interaction between a base station and an Operation, Administration and Management (OAM) according to one embodiment of the present specification.

[0056] FIG. 28 is a flowchart of an example of an NCRT management method according to one embodiment of the present specification.

[0057] Figure 29 illustrates a communication system (1) applied to the present invention.

[0058] Figure 30 illustrates a wireless device applicable to the present invention.

[0059] Figure 31 illustrates a process for generating a transmission signal in a transmitter.

[0060] Figure 32 shows another example of a wireless device applied to the present invention.

[0061] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0062] Although the terms "first," "second," "A," "B," etc. may be used herein to describe various components, the components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, the first component could be referred to as the second component, and similarly, the second component could also be referred to as the first component. Furthermore, the term "and / or" includes any combination of multiple related listed items or any one of multiple related listed items.

[0063] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0064] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0065] Unless otherwise defined, the terms used herein, including technical or scientific terms, have the same meanings commonly understood by those of ordinary skill in the art to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings within the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0066] Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the attached drawings.

[0067] FIG. 1 is a conceptual diagram illustrating a wireless communication system according to one embodiment of the present invention.

[0068] Referring to FIG. 1, a wireless communication system (100) may be composed of a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6).

[0069] Each of the plurality of communication nodes can support at least one communication protocol. For example, each of the plurality of communication nodes can support a communication protocol based on CDMA (Code Division Multiple Access), a communication protocol based on WCDMA (Wideband CDMA), a communication protocol based on TDMA (Time Division Multiple Access), a communication protocol based on FDMA (Frequency Division Multiple Access), a communication protocol based on OFDM (Orthogonal Frequency Division Multiplexing), a communication protocol based on OFDMA (Orthogonal Frequency Division Multiple Access), a communication protocol based on SC (Single Carrier)-FDMA, a communication protocol based on NOMA (Non-Orthogonal Multiple Access), a communication protocol based on SDMA (Space Division Multiple Access), etc.

[0070] A wireless communication system (100) may include a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) and a plurality of user equipments (130-1, 130-2, 130-3, 130-4, 130-5, 130-6).

[0071] The first base station (110-1), the second base station (110-2), and the third base station (110-3) can each form a macro cell. The fourth base station (120-1) and the fifth base station (120-2) can each form a small cell. The fourth base station (120-1), the third terminal (130-3), and the fourth terminal (130-4) can be within the coverage of the first base station (110-1). The second terminal (130-2), the fourth terminal (130-4), and the fifth terminal (130-5) can be within the coverage of the second base station (110-2). The fifth base station (120-2), the fourth terminal (130-4), the fifth terminal (130-5), and the sixth terminal (130-6) may be within the coverage of the third base station (110-3). The first terminal (130-1) may be within the coverage of the fourth base station (120-1). The sixth terminal (130-6) may be within the coverage of the fifth base station (120-2).

[0072] Here, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be referred to as a NodeB, an evolved NodeB, a next generation Node B (gNB), a next generation 6G base station, a Base Transceiver Station (BTS), a radio base station, a radio transceiver, an access point, an access node, a road side unit (RSU), a Digital Unit (DU), a Cloud Digital Unit (CDU), a Radio Remote Head (RRH), a Radio Unit (RU), a Transmission Point (TP), a transmission and reception point (TRP), a relay node, etc. Each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) may be referred to as a terminal, an access terminal, a mobile terminal, a station, a subscriber station, a mobile station, a portable subscriber station, a node, a device, etc.

[0073] Each of the plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6) can support cellular communication (e.g., long term evolution (LTE), advanced LTE-A, New Radio (NR), 6G Radio Access Technology, etc. as specified in the 3rd generation partnership project (3GPP) standard). Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can operate in a different frequency band or can operate in the same frequency band. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can be connected to each other via an ideal backhaul or a non-ideal backhaul, and can exchange information with each other via the ideal backhaul or the non-ideal backhaul. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can be connected to a core network (not shown) via an ideal backhaul or a non-ideal backhaul. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit a signal received from the core network to the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6), and can transmit a signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) to the core network.

[0074] Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can support downlink transmission based on OFDM. In addition, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can support uplink transmission based on OFDM or DFT-Spread-OFDM. In addition, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can support MIMO (Multiple Input Multiple Output) transmission (e.g., SU (Single User)-MIMO, MU (Multi User)-MIMO, massive MIMO, etc.), CoMP (Coordinated Multipoint) transmission, carrier aggregation transmission, transmission in an unlicensed band, device to device (D2D) communication (or, ProSe (proximity services), etc.). Here, each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) can support base stations (110-1, 110-2, 110-3, It is possible to perform operations corresponding to (120-1, 120-2) and / or operations supported by base stations (110-1, 110-2, 110-3, 120-1, 120-2).

[0075] For example, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) based on the SU-MIMO scheme, and the fourth terminal (130-4) can receive a signal from the second base station (110-2) based on the SU-MIMO scheme. Alternatively, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) and the fifth terminal (130-5) based on the MU-MIMO scheme, and each of the fourth terminal (130-4) and the fifth terminal (130-5) can receive a signal from the second base station (110-2) based on the MU-MIMO scheme. Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can transmit a signal to the fourth terminal (130-4) based on the CoMP scheme, and the fourth terminal (130-4) can receive a signal from the first base station (110-1), the second base station (110-2), and the third base station (110-3) based on the CoMP scheme. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit and receive a signal with terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) within its coverage based on the CA scheme.

[0076] Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can coordinate D2D communication between the fourth terminal (130-4) and the fifth terminal (130-5), and each of the fourth terminal (130-4) and the fifth terminal (130-5) can perform D2D communication through coordination by each of the second base station (110-2) and the third base station (110-3).

[0077] Hereinafter, even if a method (e.g., transmitting or receiving a signal) performed by a first communication node among communication nodes is described, a corresponding second communication node can perform a method (e.g., receiving or transmitting a signal) corresponding to the method performed by the first communication node. That is, if an operation of a terminal is described, a corresponding base station can perform an operation corresponding to the operation of the terminal. Conversely, if an operation of a base station is described, a corresponding terminal can perform an operation corresponding to the operation of the base station.

[0078] Also, in the following, downlink (DL) refers to communication from a base station to a terminal, and uplink (UL) refers to communication from a terminal to a base station. In downlink, the transmitter may be part of the base station, and the receiver may be part of the terminal. In uplink, the transmitter may be part of the terminal, and the receiver may be part of the base station.

[0079] Recently, with the rapid proliferation of smartphones and Internet of Things (IoT) devices, the amount of information exchanged via communications networks is increasing. Accordingly, next-generation wireless access technologies need to consider environments that provide faster services to more users than existing communication systems (or existing radio access technologies), such as enhanced mobile broadband communication. To this end, the design of communication systems that consider Machine Type Communication (MTC), which connects multiple devices and objects to provide services, is being discussed. Furthermore, the design of communication systems that consider services and / or terminals sensitive to communication reliability and / or latency (e.g., Ultra-Reliable and Low Latency Communication (URLLC)) is also being discussed.

[0080] Hereinafter, in this specification, for the convenience of explanation, the next-generation wireless access technology is referred to as New RAT (Radio Access Technology), and the wireless communication system to which the New RAT is applied is referred to as an NR (New Radio) system. In this specification, the frequency, frame, subframe, resource, resource block, region, band, subband, control channel, data channel, synchronization signal, various reference signals, various signals, or various messages related to NR may be interpreted as having the meaning used in the past or present, or as having various meanings used in the future.

[0081] FIG. 2 is an exemplary diagram showing an NR system to which a data transmission method according to one embodiment of the present invention can be applied.

[0082] 5G, standardized by 3GPP, is a radio access technology that can provide improved data transmission rates compared to LTE and satisfy various QoS requirements for each segmented and specific usage scenario. In particular, eMBB (enhanced Mobile Broadband), mMTC (massive MTC), and URLLC (Ultra Reliable and Low Latency Communications) are defined as representative usage scenarios of NR. A flexible frame structure compared to LTE is provided as a method to satisfy the requirements of each scenario. The frame structure of 5G NR supports a frame structure based on multiple subcarriers. The default subcarrier spacing (SCS) is 15 kHz, and a total of five SCS types are supported: 15 kHz * 2^n (n = 0, 1, 2, 3, 4).

[0083] Referring to Figure 2, the Next Generation-Radio Access Network (NG-RAN) consists of gNBs that provide NG-RAN user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocol termination for UE (User Equipment). Here, NG-C represents the control plane interface used for the NG2 reference point between the NG-RAN and the 5th Generation Core (5GC). NG-U represents the user plane interface used for the NG3 reference point between the NG-RAN and the 5GC.

[0084] gNBs are interconnected via the Xn interface and connected to the 5GC via the NG interface. More specifically, gNBs are connected to the Access and Mobility Management Function (AMF) via the NG-C interface and to the User Plane Function (UPF) via the NG-U interface.

[0085] The NR system of FIG. 2 can support multiple numerologies. Here, the numerologies can be defined by subcarrier spacing and cyclic prefix (CP) overhead. Multiple subcarrier spacings can be derived by scaling the basic subcarrier spacing to integers. Furthermore, even if it is assumed that very low subcarrier spacing is not utilized at very high carrier frequencies, the numerologies utilized can be selected independently of the frequency band.

[0086] Additionally, the NR system can support various frame structures according to multiple numerologies.

[0087] Below, the NR waveform, numerology, and frame structure are described.

[0088] NR uses the CP-OFDM waveform with a cyclic prefix for downlink transmission, and CP-OFDM or DFT-S-OFDM for uplink transmission. OFDM technology is easily combined with MIMO (Multiple Input Multiple Output) and offers the advantages of high frequency efficiency and low-complexity receivers.

[0089] Meanwhile, in NR, the requirements for data rates, latency, and coverage differ across the three scenarios mentioned above. Therefore, it is necessary to efficiently satisfy these requirements across the frequency bands that comprise any NR system. To this end, technologies have been proposed to efficiently multiplex radio resources based on multiple different numerologies.

[0090] Specifically, the NR transmission numerator is determined based on the sub-carrier spacing and the cyclic prefix (CP), and is changed exponentially using the μ value as an exponent value of 2 based on 15 kHz, as shown in Table 1 below.

[0091] μSubcarrier spacing (kHz)Cyclic prefixSupported for dataSupported for synch015NormalYesYes130NormalYesYes260Normal, ExtendedYesNo3120NormalYesYes4240NormalNoYes

[0092] As shown in Table 1 above, the numerology of NR can be divided into five types according to the subcarrier spacing. This is different from the fixed 15 kHz subcarrier spacing of LTE, one of the 4G communication technologies. Specifically, the subcarrier spacing used for data transmission in NR is 15, 30, 60, and 120 kHz, and the subcarrier spacing used for synchronization signal transmission is 15, 30, 120, and 240 kHz. In addition, the extended CP is applied only to the 60 kHz subcarrier spacing. Meanwhile, the frame structure in NR is defined as a 10 ms frame consisting of 10 subframes of the same length of 1 ms. One frame can be divided into 5 ms half frames, and each half frame contains 5 subframes. For a 15 kHz subcarrier spacing, one subframe consists of one slot, and each slot consists of 14 OFDM symbols.

[0093] Below, NR physical resources are described.

[0094] In relation to physical resources in NR, antenna ports, resource grids, resource elements, resource blocks, and bandwidth parts are considered.

[0095] Antenna ports are defined such that the channel through which a symbol on an antenna port is carried can be inferred from the channel through which another symbol on the same antenna port is carried. Two antenna ports are said to be quasi co-located (QC / QCL) if the large-scale properties of the channel through which a symbol on one antenna port is carried can be inferred from the channel through which a symbol on the other antenna port is carried. Here, the large-scale properties include one or more of delay spread, Doppler spread, Doppler shift, average delay, and spatial Rx parameters.

[0096] FIG. 3 is a diagram for explaining a resource grid supported by a wireless access technology to which the present invention can be applied.

[0097] Referring to Figure 3, a resource grid may exist for each numeral, as NR supports multiple numerals on the same carrier. Furthermore, resource grids may exist based on antenna ports, subcarrier spacing, and transmission direction.

[0098] A resource block (RB) consists of 12 subcarriers and is defined solely in the frequency domain. Furthermore, a resource element (RE) consists of one OFDM symbol and one subcarrier. Therefore, as shown in Figure 3, the size of a single RB can vary depending on the subcarrier spacing. NR also defines "Point A," which serves as a common reference point for the RB grid, as well as common RBs and physical RBs.

[0099] FIG. 4 is a diagram for explaining a bandwidth part supported by a wireless access technology to which the present invention can be applied.

[0100] Unlike LTE, where the carrier bandwidth is fixed at 20 MHz, NR sets the maximum carrier bandwidth from 50 MHz to 400 MHz for each subcarrier interval. Therefore, it is not assumed that all terminals will use the entire carrier bandwidth. Accordingly, NR allows terminals to designate bandwidth parts (BWPs) within the carrier bandwidth, as illustrated in Figure 4. Furthermore, bandwidth parts are associated with a single numerology, consist of a subset of consecutive common resource blocks, and can be dynamically activated over time. Each terminal is configured with up to four bandwidth parts for both the uplink and downlink, and data is transmitted and received using the bandwidth parts activated at a given time.

[0101] In the case of a paired spectrum, the uplink and downlink bandwidth parts are set independently, and in the case of an unpaired spectrum, the downlink and uplink bandwidth parts are set in pairs so that they can share a center frequency to prevent unnecessary frequency re-tuning between downlink and uplink operations.

[0102] Below, the initial connection to NR is described.

[0103] In NR, a terminal performs cell search and random access procedures to connect to a base station and perform communication.

[0104] Cell search is a procedure in which a terminal synchronizes to the cell of a corresponding base station, obtains a physical layer cell ID, and obtains system information using the synchronization signal block (SSB) transmitted by the base station.

[0105] FIG. 5 is a diagram illustrating an example of a synchronization signal block in a wireless access technology to which the present invention can be applied.

[0106] Referring to FIG. 5, SSB is composed of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS), each occupying one symbol and 127 subcarriers, and a PBCH spanning three OFDM symbols and 240 subcarriers.

[0107] The terminal receives SSB by monitoring SSB in the time and frequency domain.

[0108] SSB can be transmitted up to 64 times in 5ms. Multiple SSBs are transmitted in different transmission beams within 5ms, and the terminal performs detection assuming that SSBs are transmitted every 20ms based on a specific beam used for transmission. The number of beams that can be used for SSB transmission within 5ms can increase as the frequency band increases. For example, up to 4 SSB beams can be transmitted below 3GHz, up to 8 in the frequency band between 3GHz and 6GHz, and up to 64 different beams can be used for SSB transmission in the frequency band above 6GHz.

[0109] SSB contains two symbols in one slot, and the starting symbol and number of repetitions within the slot are determined as follows depending on the subcarrier spacing.

[0110] Meanwhile, unlike SS in conventional LTE, SSB is not transmitted at the center frequency of the carrier bandwidth. This means that SSB can be transmitted even in locations other than the center of the system bandwidth, and when supporting wideband operation, multiple SSBs can be transmitted in the frequency domain. Accordingly, the terminal monitors SSB using the synchronization raster, which is a candidate frequency location for monitoring SSB. The carrier raster, which is the center frequency location information of the channel for initial access, and the synchronization raster are newly defined in NR. The synchronization raster has a wider frequency interval than the carrier raster, which can support the terminal's fast SSB search.

[0111] A UE can obtain the MIB through the PBCH of the SSB. The MIB (Master Information Block) includes the minimum information required for the UE to receive the remaining system information (RMSI, Remaining Minimum System Information, or SIB1 (System Information Block 1)) broadcast by the network. In addition, the PBCH may include information on the position of the first DM-RS (demodulation reference signal) symbol in the time domain, information for the UE to monitor SIB1 (e.g., SIB1 numerology information, information related to SIB1 CORESET, search space information, PDCCH (physical downlink control channel) related parameter information, etc.), offset information between the common resource block and the SSB (the absolute position of the SSB within the carrier is transmitted through SIB1), etc. Here, the SIB1 numerology information is also applied equally to some messages used in the random access procedure for the UE to access the base station after completing the cell search procedure. For example, the numerology information of SIB1 may be applied to at least one of messages 1 to 4 for a random access procedure.

[0112] The aforementioned RMSI may refer to SIB1 (System Information Block 1), and SIB1 is broadcast periodically (e.g., every 160 ms) in the cell. SIB1 contains information necessary for the UE to perform the initial random access procedure and is periodically transmitted via PDSCH. In order for the UE to receive SIB1, it must receive numerology information used for SIB1 transmission and CORESET (Control Resource Set) information used for SIB1 scheduling via PBCH. The UE checks the scheduling information for SIB1 using SI-RNTI (Radio Network Temporary Identifier) ​​within CORESET and acquires SIB1 on PDSCH according to the scheduling information. The remaining SIBs, excluding SIB1, may be transmitted periodically or upon request of the UE.

[0113] Below, a non-terrestrial network or NTN (Non-terrestrial network) is described.

[0114] Figure 6 is a diagram illustrating a non-terrestrial network (NTN, hereinafter referred to as NTN). Referring to Figure 6, the NTN may be configured to include one or more satellites (410), one or more NTN gateways (420) capable of communicating with the satellites, and one or more terminals ( / base stations) (430) capable of receiving wireless satellite services from the satellites.

[0115] Non-terrestrial networks (NTNs) refer to wireless networks built using satellites (e.g., geostationary satellites (GEO, GSO, etc.) / low-earth orbit satellites (LEO)). NTN networks can enable expanded coverage and highly reliable network services. For example, NTNs can be configured alone or combined with conventional terrestrial networks to form a wireless communication system. For example, NTN networks can be comprised of i) links between satellites and terminals, ii) links between satellites, and iii) links between satellites and gateways.

[0116] The use cases that can be provided by a communication system utilizing satellite connectivity can be divided into three categories. The “Service Continuity” category can be used to provide network connectivity in geographic areas where 5G services are not accessible via the wireless coverage of terrestrial networks. For example, satellite connectivity can be used for devices associated with pedestrian users or devices on moving terrestrial platforms (e.g., cars, coaches, trucks, trains), air platforms (e.g., commercial or private jets), or maritime platforms (e.g., sea vessels). The “Service Ubiquity” category can be used for IoT / public safety-related emergency networks / home access when terrestrial networks are unavailable (e.g., due to disasters, destruction, or economic reasons). The “Service Scalability” category encompasses services that leverage the extensive coverage of satellite networks.

[0117] For example, a 5G satellite access network can be connected to a 5G core network. In this case, the satellite can be a bent pipe satellite or a regenerative satellite. NR wireless protocols can be used between the terminal and the satellite. Additionally, an F1 interface can be used between the satellite and the gNB.

[0118] As mentioned above, non-terrestrial networks (NTNs) refer to wireless networks built using devices that are not fixed on the ground, such as satellites. Satellite networks are a prime example. NTNs can enable expanded coverage and highly reliable network services. For example, NTNs can be configured independently or combined with existing terrestrial networks to form a wireless communication system.

[0119] Non-Terrestrial Network (NTN) is a network that complements and partially replaces the existing terrestrial network (TN) infrastructure in remote areas, oceans, and airspace where it is difficult to deploy, using satellites in geostationary orbit (GSO), very low earth orbit (VLEO), low earth orbit (LEO), and medium earth orbit (MEO), high altitude platform stations (HAPS), drones, and urban air mobility (UAM). It is being standardized starting from 3GPP Release 17.

[0120] Meanwhile, the coverage area of ​​a single NTN base station using LEO satellites varies depending on satellite altitude and beam specifications, but typically ranges from tens to hundreds of kilometers in diameter. This is significantly larger than the diameter of a TN base station (hundreds of meters to several kilometers). Consequently, at any given time, a single NTN base station can be neighbors with many TN base stations.

[0121] In mobile communications, handover (HO) is a set of technologies that seamlessly transition a user's mobile device from one base station to another without losing communication connectivity while the user is moving. Handover is crucial for maintaining stable communications in situations where the signal strength and quality of the base stations receiving the user device are constantly changing.

[0122] Below, the Automatic Neighbor Relation, ANR, or ANR feature is described.

[0123] ANR or ANR function refers to the function of requesting the UE / terminal that is currently in RRC_CONNECTED state with the current base station to report information related to neighboring cells in the vicinity, and managing the NRT (Neighbor Relation Table) or NCRT (Neighbor Cell Relation Table), which is a table that stores information related to neighboring cells required when the base station instructs a handover (HO). 5G NTN (Non-Terrestrial Networks) is a 5G technology whose standardization began in 3GPP Rel. 17, and broadly refers to 5G non-terrestrial networks including satellites / HAPS (High Altitude Platforms) / ATG (Air-to-Ground) / UAV (Uncrewed Aerial Vehicle). NTN KPI (Key Performance Indicator) / frequency / capability / architecture / device, etc. are being defined, and standardization is underway for areas that require improvement when applying existing 5G technology to satellites. It is expected that there will also be discussions on the future integrated structure of 5G TN and NTN networks.

[0124] Automatic Neighbor Relation (ANR) is a technology that automatically manages relationships between neighboring base stations (neighbor cells) in mobile communications networks. As technology evolves and networks become increasingly complex, seamless management of relationships between neighboring base stations through ANR becomes increasingly important.

[0125] For example, a base station can maintain optimal handover conditions by managing a table (NCRT: Neighbor Cell Relation Table) of attributes for other neighboring base stations. Here, the attributes may include prohibiting deletion of the base station in the NCRT (No Remove), prohibiting handover to the base station (No HO), prohibiting handover of the Xn interface between base stations to the base station (No Xn), etc. In this case, information about other neighboring base stations can be obtained by utilizing a Measurement Report message that the terminal sends to the base station.

[0126] In other words, ANR or ANR function refers to the function of requesting the current base station and the UE / terminal in RRC_CONNECTED state to report information related to neighboring cells existing in the vicinity, and managing the NRT (Neighbor Relation Table) or NCRT (Neighbor Cell Relation Table), which is a table that stores information related to neighboring cells required when the base station instructs a handover (HO).

[0127] For example, LEO satellites used in NTN move at a fast speed of 7.6 km / s, assuming an altitude of 550 km in an orbit. In this case, the time it takes to pass over a specific TN base station's coverage area is relatively short. Therefore, the time for which neighbor relationships established at the base station are maintained is also short, and these neighbor relationships may also be frequently added and / or deleted. Meanwhile, due to the aforementioned difference in cell size, NTN base stations may have a large number of neighbor relationships with TN base stations. For this reason, managing neighbor relationships between NTN base stations and TN base stations can be complex in an environment where they coexist. Figure 7 illustrates an example of a scenario where TN and NTN base stations coexist.

[0128] For example, when integrating a 5G TN (Terrestrial Network) and an NTN network, there may be a method of directly linking a 5G TN (gNB-AMF) and a 5G NTN (gNB-AMF), and FIG. 8 illustrates an example of a TN-NTN interworking structure according to an embodiment of the present specification. In a network structure where TN-NTN interworks as described above, if there is no neighbor relationship between the TN gNB and the NTN gNB during a handover operation, a procedure for registering a neighbor relationship through ANR is required. The existing ANR procedure cannot distinguish between TN cells and NTN cells, and since NRT is also managed without distinguishing between TN and NTN, there is a problem that serving cell information must be broadcast to all AMFs when creating a neighbor relationship.

[0129] This specification proposes procedures / structures such as an extended Neighbor Relation Table (NRT), NG Interface Setup Information, and a Measurement Report to manage a neighbor relationship list by distinguishing between terrestrial and satellite networks for smooth handover operations between Terrestrial Networks (TNs) and Non-Terrestrial Networks (NTNs). In addition, a method for generating a Neighbor Relation Table (NRT) or a Neighbor Cell Relation Table (NCRT) is proposed, thereby enabling smooth handover operations in a mobile communication network structure in which TNs and NTNs are integrated. Fig. 9 illustrates an example of a mobile communication network structure in which 5G TNs and 5G NTNs are integrated. In the example of Fig. 9, the functions of a base station or core network may be provided by a satellite. Although the proposed methods of this specification, including Fig. 9, are described based on a 5G system, the proposed methods of this specification can be applied to not only 5G systems but also next-generation wireless communication systems.

[0130] FIG. 10 is a diagram illustrating an example of ANR-based interaction between a base station and an Operation, Administration and Management (OAM) according to one embodiment of the present specification.

[0131] Referring to FIG. 10, the base station includes an ANR function entity capable of exchanging information with OAM, and the ANR function entity can also exchange information with a terminal through radio resource control (RRC).

[0132] Here, the ANR function entity can internally realize neighbor cell deletion, realize neighbor cell measurement by RRC connection, add or update neighbor cell relationship through interaction with OAM, and also maintain ANR list through neighbor cell relationship table management.

[0133] For example, ANR from a source cell to a target cell may mean that the base station controlling the source cell knows the global and physical IDs of the target cell (e.g., NR Cell Global Identifier (NR CGI) / NR Physical Cell Identifier (PCI), EUTRA Cell Global Identifier (ECGI) / PCI), the base station controlling the source cell has an entry in the NCRT for the source cell that identifies the target cell, and the base station controlling the source cell has attributes of that NCRT entry defined by OAM or set to default.

[0134] Fig. 11 is a flowchart illustrating an example of an NRT management method according to an embodiment of the present disclosure. The example of Fig. 11 is described based on the case where the terminal is in an RRC_CONNECTED state with respect to the TN serving base station and the neighboring base station is an NTN neighboring base station. However, the example of Fig. 11 can be extended to cases where the terminal is in an RRC_CONNECTED state with respect to the NTN serving base station and the neighboring base station is a TN neighboring base station, etc., within a range that does not conflict with the proposed method of the present disclosure. Furthermore, in the embodiment of Fig. 11, at least some of the steps of Fig. 11 may be omitted.

[0135] Referring to Fig. 11, a terminal may be in an RRC_CONNECTED state for a TN serving base station. The terminal may transmit a measurement report message to the TN serving base station (S1110). Here, the measurement report message may include identifiers for the neighboring base station or neighboring cell, such as a PCI, NR CGI (Cell Group Identifier), NR PCI (Physical Cell Identifier), ECGI, etc. for the neighboring base station or neighboring cell. In this case, the neighboring base station may include at least one of a base station supporting TN and a base station supporting NTN. In addition, the measurement report message may include information on RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), RSSI (Received Signal Strength Indicator), SINR (Signal to Interference plus Noise Ratio) of an uplink signal and / or a downlink signal for the TN serving base station and / or the neighboring base station.

[0136] Although not illustrated in FIG. 11, the measurement report message may be transmitted based on measurement settings for the TN serving base station. For example, the TN serving base station may, through the measurement settings, set an event for the terminal to transmit a measurement report message, and when the event occurs, the terminal may transmit a measurement report message to the TN serving base station.

[0137] The TN serving base station can search for the NCRT (S1120). Here, the TN serving base station can search for whether the identifier for the neighboring base station or neighboring cell included in the measurement report message exists in the NCRT stored in the TN serving base station.

[0138] If the identifier of the neighboring base station or neighboring cell included in the measurement report message does not exist in the NCRT stored in the TN serving base station, the TN serving base station may transmit a report request message to the terminal (S1130). Here, the report request message may be a message requesting identifier information of the neighboring base station or neighboring cell included in the measurement report message to the terminal. At this time, the identifier information may include an indicator capable of identifying the neighboring base station, such as the PCI, NR CGI, NR PCI, ECGI, etc. of the neighboring base station. In addition, the report request message may be transmitted by being included in an RRC connection reconfiguration message. In addition to the indicator capable of identifying the neighboring base station, the report request message may indicate a request for information of the neighboring base station (e.g., information on the PCI, network type, Absolute Radio Frequency Channel Number (ARFCN), Tracking Area Code (TAC), Public Land Mobile Network (PLMN), etc. of the neighboring base station).

[0139] Thereafter, the terminal can receive system information from a neighboring base station or neighboring cell included in the measurement report message (S1140). Here, the system information may be at least one of a Master Information Block (MIB) and SIB1.

[0140] The terminal can determine whether the neighboring base station is an NTN base station based on the system information (S1150). Here, the system information may include information on the identifier information (e.g., PCI, CGI, NR PCI, ECGI, etc.) of the neighboring base station, network type, Absolute Radio Frequency Channel Number (ARFCN), Tracking Area Code (TAC), Public Land Mobile Network (PLMN), etc. In addition, the system information may include an NTN-only access restriction indicator (e.g., cellBarredNTN) for the neighboring base station or the neighboring cell. In this case, if the NTN-only access restriction indicator indicates access restriction, the terminal can determine the neighboring base station or the neighboring cell as a TN neighboring base station. In addition, if the NTN-only access restriction indicator indicates access non-restriction or access permission, the terminal can determine the neighboring base station or the neighboring cell as an NTN neighboring base station. Meanwhile, the system information may not include an NTN-only access restriction indicator for the neighboring base station or the neighboring cell, in which case the terminal may determine the neighboring base station or the neighboring cell as a TN neighboring base station.

[0141] Thereafter, the terminal may transmit a report response message to the TN serving base station in response to the report request message (S1160). Here, the report response message may include at least a portion of information about the identifier information of the neighboring base station (e.g., PCI, CGI, NR PCI, ECGI, etc.), network type, Absolute Radio Frequency Channel Number (ARFCN), Tracking Area Code (TAC), Public Land Mobile Network (PLMN), etc. Here, as an example, the information or identifier about the network type may indicate whether the measurement target cell (e.g., the neighboring cell or neighboring base station) is a TN cell or an NTN cell. In addition, as an example, the report response message may not include information or identifier about the network type, and in this case, the TN serving base station receiving the report response message may determine the measurement target cell as a TN neighboring base station or a TN neighboring cell. Additionally, as an example, the report response message may include CGI information, and the CGI information may include an indicator / information indicating a network type for the neighboring cell.

[0142] Here, the report response message may include a field for the report result. For example, the field for the report result may be a MeasResultNR field, and an example of the MeasResultNR field may be as shown in Table 2 below. Referring to Table 2, the MeasResultNR field may include a network-Type field for distinguishing whether it is a TN cell or an NTN cell.

[0143]

[0144] The TN serving base station may perform TN AMF (Access and Mobility Management Function) and NCRT update (S1170). Here, the TN AMF may refer to a network function that manages mobility through NAS (Non Access Stratum) signaling message processing and terminal location registration for terminal network access in the TN network. At this time, the TN serving base station may add or update an adjacent cell relationship for the neighboring base station through interaction with OAM, and may also maintain an ANR list through NCRT management. Here, an example of the NCRT of the TN serving base station may be as shown in Table 3 below. That is, the NCRT may include a network type field for distinguishing between TN cells and NTN cells. For example, based on network type information included in identifier information for the neighboring base station, such as CGI information, the base station may determine the network type of the neighboring base station and reflect it in the NCRT.

[0145] Neighbor RelationNetwork TypePCIPLMNCGIXn HONBR Type1TN123123451232YesInter Freq.2TN124123451233YesIntra Freq.3NTN125123101210NoInter Freq.4NTN126123101211NoIntra Freq.5TN122123451234YesIntra Freq.

[0146] Thereafter, although not illustrated in FIG. 11, the TN serving base station may perform message transmission and reception with the TN AMF and / or NTN AMF based on the NG interface setup information managed by the TN serving base station. Here, the NTN AMF may refer to a network function that manages mobility through NAS (Non Access Stratum) signaling message processing and terminal location registration for terminal network access in the NTN network. For example, in the case of an ANR change related to the TN network based on the NCRT updated through the S1170 step, the base station may perform message transmission and reception with the TN AMF, and in the case of an ANR change related to the NTN network based on the NCRT updated through the S1170 step, the base station may perform message transmission and reception with the NTN AMF. At this time, the message transmission and reception may be performed based on system-to-system signaling.

[0147] Here, the NG interface setup information is information managed by the base station, and may refer to information about AMF, information about network type, etc. Here, as an example, the NG interface setup information may be configured as shown in Table 4.

[0148] NG Interface Setup Information Network Type AMF IP1 TN1.1.1.12 NTN1.1.1.2 TN1.1.1.3

[0149] FIG. 12 illustrates an example of an NCRT management method performed by a base station according to one embodiment of the present disclosure. Here, the base station may include at least some of an eNB, a gNB, and a base station of a next-generation wireless communication system.

[0150] Referring to FIG. 12, the base station transmits a report request message to a terminal (S1210). Here, the terminal may be a terminal connected to the base station in an RRC_CONNECTED state. In addition, the report request message may include information requesting identifier information of a neighboring base station or neighboring cell of the terminal. At this time, the identifier information may include an indicator that can identify the neighboring base station, such as a PCI, NR CGI, NR PCI, ECGI, etc. of the neighboring base station. In addition, the report request message may be transmitted while being included in an RRC connection reconfiguration message. In addition to the indicator that can identify the neighboring base station, the report request message may indicate a request for information of the neighboring base station (e.g., information about the PCI, network type, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), PLMN (Public Land Mobile Network), etc. of the neighboring base station).

[0151] In addition, the step S1210 may correspond to the step S1130 of Fig. 11. That is, if the identifier for a neighboring base station or neighboring cell included in the measurement report message transmitted by the terminal to the base station does not exist in the NCRT stored in the base station, the base station may transmit a report request message to the terminal.

[0152] Based on the report request message, the base station receives a report response message from the terminal (S1220). Here, the report response message may include at least a portion of information about the identifier information of the neighboring base station (e.g., PCI, CGI, NR PCI, ECGI, etc.), network type, Absolute Radio Frequency Channel Number (ARFCN), Tracking Area Code (TAC), Public Land Mobile Network (PLMN), etc. Here, as an example, the information or identifier about the network type may indicate whether the measurement target cell (e.g., the neighboring cell or neighboring base station) is a TN cell or an NTN cell. In addition, as an example, the report response message may not include information or identifier about the network type, and in this case, the TN serving base station receiving the report response message may determine the measurement target cell as a TN neighboring base station or a TN neighboring cell. Additionally, as an example, the report response message may include CGI information, and the CGI information may include an indicator / information indicating a network type for the neighboring cell.

[0153] Additionally, the above step S1220 may correspond to step S1160 of Fig. 11. In this regard, any redundant description is omitted.

[0154] The base station modifies the NCRT based on the report response message (S1230). Here, the base station can add or update the adjacent cell relationship for the neighboring base station, and also maintain an ANR list through NCRT management. Here, an example of the NCRT of the base station may be as shown in Table 3. That is, the NCRT may include a network type field for distinguishing between TN cells and NTN cells. For example, based on network type information included in identifier information for the neighboring base station, such as CGI information, the base station can determine the network type of the neighboring base station and reflect it in the NCRT.

[0155] Additionally, the above step S1230 may correspond to step S1170 of Fig. 11. In this regard, any redundant description is omitted.

[0156] Meanwhile, in an environment where TN base stations and NTN base stations coexist, a method for reducing the complexity of the ANR procedure of the NTN base station may be required. For example, in an environment where TN and NTN coexist, if a user terminal connected to an NTN reports information about a neighboring TN base station detected to the NTN base station and the ANR procedure requires a Transport Network Layer (TNL) address discovery operation, the complexity of the ANR procedure performed by the OAM and the base station can be reduced by performing this operation more smoothly.

[0157] The TNL address discovery operation can be performed as follows. For example, if the NG-RAN node knows the RAN node ID of a candidate NG-RAN node through the ANR function or the like, but does not know the TNL address suitable for the SCTP connection, the NG-RAN node can utilize the 5GC (or the connected AMF) to determine the TNL address as follows.

[0158] - The NG-RAN node may transmit an UPLINK RAN CONFIGURATION TRANSFER message to the AMF to request the TNL address of the candidate NG-RAN node, and may include related information such as source and target RAN node IDs.

[0159] - AMF may convey the request by sending a DOWNLINK RAN CONFIGURATION TRANSFER message to a candidate NG-RAN node identified by the target RAN node ID.

[0160] - The candidate NG-RAN node responds by sending an UPLINK RAN CONFIGURATION TRANSFER message to the initiating NG-RAN node containing one or more TNL addresses to be used for the SCTP connection, and may include other relevant information such as source and target RAN node IDs.

[0161] - AMF may convey the above response by sending a DOWNLINK CONFIGURATION TRANSFER message to the initiating NG-RAN node identified by the target RAN node ID.

[0162] The NG-RAN node can determine the base station ID length of the candidate base station, for example, based on the UE reporting of OAM configuration or ANR functionality. If the NG-RAN node is unable to make this determination, it can include the NR cell identifier in the UPLINK RAN CONFIGURATION TRANSFER message to the AMF. The AMF can, if supported, match the NR cell identifier with the base station ID of the connecting base station to determine the target base station ID.

[0163] FIG. 13 illustrates an example of a procedure for acquiring an NR Cell Global Identifier (NCGI) according to one embodiment of the present specification. The example in FIG. 13 illustrates a case where a terminal is connected to cell A, which has a physical cell ID of 3 and a global cell ID of 17, and a neighboring cell, cell B, which has a physical cell ID of 5 and a global cell ID of 19.

[0164] Referring to Figure 13, the base station (or cell A) manages its relationship with neighboring / adjacent base stations using NCRT. As in Step 1, a user terminal connected to the base station (or in the RRC_Connected state) can transmit a measurement report message according to conditions specified by the base station for handovers, etc.

[0165] If the information about the neighboring base station (or cell B) reported by the terminal does not exist in the NCRT, the base station can update the NRCT. Information about the neighboring base station included in the measurement report may include the physical base station identifier (PCI) and signal strength / quality information of the neighboring base station measured by the terminal. Here, if the base station needs information such as the 5G base station global identifier (NCGI: NR Cell Global Identifier) ​​for the neighboring base station, the base station can request / instruct the user terminal to acquire the NCGI of the neighboring base station, as in step 2.

[0166] Thereafter, as in step 2b, the user terminal can receive and decode the SIB1 of the neighboring base station. Through this, the terminal can obtain information about the NCGI of the neighboring base station. Then, as in step 3, the user terminal can calculate and obtain the NCGI from SIB1 and report it to the base station via a measurement report message.

[0167] Figure 14 is a flowchart illustrating an example of message exchange for TNL address discovery between a base station and an AMF.

[0168] Referring to FIG. 14, for handover, a base station requires a Stream Control Transmission Protocol (SCTP) connection with an adjacent base station. When establishing an initial SCTP connection, a Transport Network Layer (TNL) address of the adjacent base station may be requested. Here, as in (a) of FIG. 14, if the base station does not have information about the TNL address of the adjacent base station, the base station may request the TNL address from a device implementing the Access Management Function (AMF) of the 5G core network. Here, the base station may request the TNL address by transmitting an NGAP UPLINK RAN CONFIGURATION TRANSFER message to the AMF via the N2 interface.

[0169] Referring to (b) of Figure 14, the AMF can transmit the TNL address of a neighboring base station via the DOWNLINK RAN CONFIGURATION TRANSFER message. Here, the address may be in the form of an Internet Protocol address (IP address). Through this, the base station can connect to the neighboring base station via SCTP.

[0170] FIG. 15 illustrates an example of a TNL address acquisition procedure of an AMF according to one embodiment of the present specification. Here, the procedure of FIG. 15 may be an example of a NonUeN2MessageTransfer service operation used by an NF service consumer to transmit N2 information to a 5G-AN (Access Network) via AMF.

[0171] Referring to Figure 15, an NF service consumer can invoke a custom action for transmitting an N2 message that is not associated with a terminal by sending an HTTP POST request, which may include N2 information to be transmitted. Upon success, the AMF may respond with a 200 OK status code along with an N2InformationTransferRspData data structure. Additionally, upon failure or redirection, one of the HTTP status codes may be returned along with a message containing an N2InformationTransferError structure, which may include a ProblemDetails property with the cause property set to one of the application errors.

[0172] For example, if the AMF does not know the TNL address of the neighboring base station requested by the base station, the AMF can refer to the list of other AMFs in the network it manages to inquire / query the TNL address of the base station for the corresponding NCGI to another AMF. At this time, referring to step 1, the AMF can send a NonUeN2MessageTransfer message through the N14 interface to the other AMF. Here, referring to step 2a, if successful, the AMF can receive a 200 OK response. The response can include the TNL address. Also, referring to step 2b, if unsuccessful, the AMF can receive another response.

[0173] Below, the proposed methods of this specification are described.

[0174] AMF can be separated or distinguished into AMF for TN and AMF for NTN, and AMF of NTN can have a list of AMF of coexisting TN. For example, a device providing NTN AMF can receive information about a list of coexisting TN AMF from a network, or can include a memory that stores the information. In this case, when base station of NTN performs ANR procedure for detected adjacent TN base station, and performs TNL address discovery procedure for AMF of NTN, AMF of NTN may not know TNL address of detected TN base station and may query AMF of TN. Here, AMF of NTN can query by sequentially transmitting message to AMF of TN by referring to list of AMF of TN that it manages, or can query by simultaneously transmitting message to AMF of TN using broadcast method or multicast method.

[0175] FIG. 16 illustrates an example of a TNL address request procedure according to one embodiment of the present specification.

[0176] Referring to Fig. 16, a terminal can detect an adjacent TN base station (S1610). For example, the terminal can detect a signal of the adjacent TN base station. In addition, the terminal may be a terminal connected to an NTN base station. Thereafter, the terminal can perform a first report to the NTN base station (S1620). Here, the first report may include information on the detection of the adjacent TN base station. In addition, the first report may be performed through an RRC measurement report, etc. In addition, the first report may be performed by the terminal when the criteria for a measurement report, such as signal strength, are satisfied.

[0177] The NTN base station can check whether the adjacent TN base station is not in the NCRT managed by the NTN base station (S1630). That is, the NTN base station can check whether the NCRT managed by the NTN base station includes information or an identifier for the adjacent TN base station. Through this, the NTN base station can determine whether the adjacent TN base station is in a neighboring relationship.

[0178] If the adjacent TN base station is not in the NCRT, the NTN base station may transmit a measurement report reference to the terminal (S1640). Here, the measurement report reference may be a measurement report reference for confirming the NCGI of the adjacent TN base station. In addition, the measurement report reference may be transmitted via an RRC reconfiguration message.

[0179] The terminal may determine the NCGI of the adjacent TN base station (S1650). Here, the terminal may receive system information (SI) of the adjacent TN base station, and then calculate / determine the NCGI of the adjacent TN base station based on the system information. Here, the system information may be received based on the measurement report criteria. In addition, the system information may be a system information block (SIB) 1.

[0180] Thereafter, the terminal may perform a second report to the NTN base station (S1660). Here, the second report may include information about the NCGI of the adjacent TN base station. In addition, the second report may be performed through an RRC measurement report, etc.

[0181] The NTN base station can determine whether it has the TNL address of the adjacent TN base station (S1670). For example, the NTN base station can receive information about the TNL address from the network, or the information can be stored in a memory included in the NTN base station. Here, Fig. 16 assumes a case where the NTN base station does not have the TNL address of the adjacent TN base station. In this case, the NTN base station can request the TNL address of the adjacent TN base station from the NTN AMF (S1680). Here, the TNL address request can be performed based on a TNL address discovery operation. For example, the NTN base station can request the TNL address of the adjacent TN base station from the connected NTN AMF. In this case, the request can be transmitted, for example, through an NGAP UPLINK RAN CONFIGURATION TRANSFER message, as in (a) of Fig. 14.

[0182] Based on the above request, the NTN AMF can determine whether it has the TNL address (or information about the TNL address) of the adjacent TN base station (S1690). If the NTN AMF has the TNL address of the adjacent TN base station, the NTN AMF can transmit the TNL address of the adjacent TN base station and / or information about the TNL address to the NTN base station in response to the request (S1691).

[0183] In an example such as FIG. 16, if the NTN AMF does not have the TNL address of the adjacent TN base station, the NTN AMF may operate as follows. Hereinafter, procedures for the case where the NTN AMF does not have the TNL address of the requested specific TN base station (e.g., the adjacent TN base station of FIG. 16) are described.

[0184] Fig. 17 illustrates an example of a procedure when the NTN AMF does not have the TNL address of a specific TN base station for which a request has been made. For example, a device providing an NTN AMF may receive information about the TNL address of the specific TN base station from a network or may include a memory for storing the information. The example of Fig. 17 may include a case where the device providing the NTN AMF does not receive the information or the information is not stored in the memory. For convenience of explanation, Fig. 17 is described as an example of a procedure after step S1690 of Fig. 16. That is, the example of Fig. 17 is an example of a case where the NTN AMF of Fig. 16 does not have the TNL address of the adjacent TN base station of Fig. 16, as in the example of Fig. 16.

[0185] Referring to FIG. 17, the NTN AMF can determine whether it has a TNL address (or information about the TNL address) of an adjacent TN base station (S1710). If the NTN AMF has the TNL address of the adjacent TN base station, for example, if the device providing the NTN AMF receives the information or if the information is stored in the memory, the NTN AMF can transmit the TNL address of the adjacent TN base station and / or information about the TNL address to the NTN base station in response to the request (S1711). Each of steps S1710 and S1711 may correspond to each of steps S1690 and S1691 of FIG. 16.

[0186] If the NTN AMF does not have the TNL address of the adjacent TN base station, the NTN AMF may set one TN AMF included in the list of TN AMFs managed by the NTN AMF as a target TN AMF, and transmit a message to the target TN AMF inquiring whether the adjacent TN base station belongs to the target TN AMF, i.e., whether the adjacent TN base station is managed by the target TN AMF (S1712). Here, the message may include the NCGI of the adjacent TN base station. In addition, the message may be a NonUeN2MessageTransfer message, and the NTN AMF may wait to receive a response message after transmitting the message. That is, the step S1712 may be performed based on the step 1 of FIG. 15. Based on the message inquiring whether the adjacent TN base station is managed by the target TN AMF, the target TN AMF may determine whether the adjacent TN base station belongs to itself (S1720). Here, the target TN AMF can determine whether the adjacent TN base station belongs to itself by checking the NCGI of the adjacent TN base station.

[0187] If the adjacent TN base station belongs to the target TN AMF (option 17-1 of FIG. 17), the target TN AMF can transmit a message including the TNL address of the adjacent TN base station to the NTN AMF (S1730). Here, the message of step S1730 can be transmitted based on step 2a of FIG. 15. Thereafter, the NTN AMF can transmit a message including the TNL address of the adjacent TN base station to the NTN base station (S1731). Here, the message of step S1731 can be transmitted through an NGAP DOWNLINK RAN CONFIGURATION TRANSFER message as shown in (b) of FIG. 14. Through this, the TNL address discovery procedure can be completed. In addition, by adding information about the adjacent TN base station, the NTN base station can update the NCRT managed by the NTN base station (S1732). In this case, the NTN AMF does not need to request the TNL address for the adjacent TN base station for any TN AMF other than the target TN AMF included in the list of TN AMFs managed by the NTN AMF.

[0188] If the adjacent TN base station does not belong to the target TN AMF (option 17-2 of FIG. 17), the target TN AMF may transmit an error response to the NTN AMF (S1740). Here, the error response may be transmitted based on step 2b of FIG. 15. Based on the error response, the NTN AMF may check whether it has received the error response from all TN AMFs included in the TN AMF list managed by it (S1741).

[0189] Here, if the NTN AMF does not receive the error response from all the TN AMFs included in the TN AMF list managed by it in step S1741, the NTN AMF may set another TN AMF included in the TN AMF list managed by it as a new target TN AMF, and may transmit a message to the new target TN AMF inquiring whether the adjacent TN base station belongs to the target TN AMF, i.e., whether the adjacent TN base station is managed by the new target TN AMF. That is, step S1712 may be repeatedly performed. Thereafter, step S1720 and option 17-1 or 17-2 may be repeatedly performed.

[0190] Alternatively, if the NTN AMF receives the error response from all TN AMFs included in the TN AMF list managed by the NTN AMF in step S1741, this means that among the base stations belonging to all TN AMFs on the network known to the NTN AMF, the TN base station detected by the terminal does not exist. In this case, since the TNL address discovery procedure cannot be successfully completed, error handling may be performed.

[0191] Fig. 18 illustrates another example of a procedure when the NTN AMF does not have the TNL address of a specific TN base station for which a request has been made. For example, a device providing an NTN AMF may receive information about the TNL address of the specific TN base station from a network or may include a memory for storing the information. The example of Fig. 18 may include a case where the device providing the NTN AMF does not receive the information or the information is not stored in the memory. For convenience of explanation, Fig. 18 is described as another example of a procedure after step S1690 of Fig. 16. That is, the example of Fig. 18 is another example of a case where the NTN AMF of Fig. 16 does not have the TNL address of the adjacent TN base station of Fig. 16, as in the example of Fig. 16.

[0192] Referring to FIG. 18, the NTN AMF can determine whether it has a TNL address (or information about the TNL address) of an adjacent TN base station (S1810). If the NTN AMF has the TNL address of the adjacent TN base station, for example, if the device providing the NTN AMF receives the information or if the information is stored in the memory, the NTN AMF can transmit the TNL address of the adjacent TN base station and / or information about the TNL address to the NTN base station in response to the request (S1811). Each of steps S1810 and S1811 may correspond to each of steps S1690 and S1691 of FIG. 16.

[0193] If the NTN AMF does not have the TNL address of the adjacent TN base station, the NTN AMF may set all TN AMFs included in the TN AMF list managed by the NTN AMF as target TN AMFs, and may transmit a message to each of the target TN AMFs to inquire whether the adjacent TN base station belongs to the target TN AMF, i.e., whether the adjacent TN base station is managed by the target TN AMF (S1812). Here, the message of step S1812 may be transmitted in a unicast manner, a multicast manner, or a broadcast manner. In addition, the message may include the NCGI of the adjacent TN base station. In addition, the message may be a NonUeN2MessageTransfer message, and the NTN AMF may wait to receive a response message after transmitting the message. That is, step S1812 may be performed based on step 1 of FIG. 15. Based on the message inquiring whether the adjacent TN base station is managed by the target TN AMF, each of the target TN AMFs can determine whether the adjacent TN base station belongs to it (S1820). Here, the target TN AMF can determine whether the adjacent TN base station belongs to it by checking the NCGI of the adjacent TN base station.

[0194] If the adjacent TN base station belongs to one of the target TN AMFs (option 18-1 of FIG. 18), one of the target TN AMFs can transmit a message including the TNL address of the adjacent TN base station to the NTN AMF (S1830). Here, the message of step S1830 can be transmitted based on step 2a of FIG. 15. Thereafter, the NTN AMF can transmit a message including the TNL address of the adjacent TN base station to the NTN base station (S1831). Here, the message of step S1831 can be transmitted through an NGAP DOWNLINK RAN CONFIGURATION TRANSFER message as shown in (b) of FIG. 14. Through this, the TNL address discovery procedure can be completed. In addition, by adding information about the adjacent TN base station, the NTN base station can update the NCRT managed by the NTN base station (S1832). In this case, the NTN AMF does not need to wait for a response message for a target TN AMF other than the one that sent the S1830 message among the target TN AMFs.

[0195] If the adjacent TN base station does not belong to all of the target TN AMFs (option 18-2 of FIG. 18), each of the target TN AMFs may transmit an error response to the NTN AMF (S1840). Here, the error response may be transmitted based on step 2b of FIG. 15. Based on the error response, the NTN AMF may check whether it has received the error response from all TN AMFs included in the TN AMF list managed by it (S1841). That is, this means that among the base stations belonging to all TN AMFs on the network known to the NTN AMF, the TN base station detected by the terminal does not exist. In this case, since the TNL address discovery procedure cannot be successfully completed, error handling may be performed.

[0196] FIG. 19 is a flowchart illustrating an example of a method performed by a communication device according to one embodiment of the present disclosure. Here, the communication device may be a device providing the NTN AMF of FIGS. 16 to 18.

[0197] Referring to Fig. 19, a communication device receives a request message from an NTN base station (S1910). Here, the request message may be a message requesting the TNL address of an adjacent TN base station of a terminal connected to the NTN base station.

[0198] Based on the above request message, the communication device determines whether it has the TNL address of the adjacent TN base station (S1920). For example, the communication device may receive information about the TNL address of the adjacent TN base station from the network or include a memory that stores the information.

[0199] Here, if the communication device has the TNL address of the adjacent TN base station, for example, if the communication device receives information about the TNL address of the adjacent TN base station from the network or includes a memory that stores the information, the communication device transmits the TNL address of the adjacent TN base station to the NTN base station in response to the request message (S1931). Or, if the communication device does not have the TNL address of the adjacent TN base station, for example, if the communication device has not received information about the TNL address of the adjacent TN base station from the network or the memory of the communication device does not store the information, the communication device determines a specific TN AMF among all TN AMFs included in the TN AMF list managed by the communication device, and transmits a request message requesting the TNL address of the adjacent TN base station to the specific TN AMF (S1932). Here, the specific TN AMF may be one or more TN AMFs among all TN AMFs. Additionally, after the above step S1932, at least one procedure among option 17-1 of FIG. 17, option 17-2 of FIG. 17, option 18-1 of FIG. 18, and option 18-2 of FIG. 18 may be performed. In this case, redundant descriptions are omitted.

[0200] Although not illustrated in FIG. 19, in response to the request message, the communication device may receive a response message from the specific TN AMF. The response message may include the TNL address of the adjacent TN base station, or may include information / indicator indicating that the adjacent TN base station does not have a TNL address.

[0201] Meanwhile, since non-terrestrial networks generally lack the network capacity and service speed of terrestrial networks, early satellite mobile communication services can serve as a supplement to areas where terrestrial network coverage is lacking. However, the extremely wide coverage of satellites can lead to unnecessary overlap with terrestrial networks, creating unnecessary neighbor cell relationships (NCRs). Figure 20 illustrates an example of an overlapping NTN cell coverage with multiple TN cell coverages according to one embodiment of the present disclosure.

[0202] In order to generate NCR between 5G TN (Terrestrial Networks) and 5G NTN (Non-Terrestrial Networks), the following proposes a method in which a terminal provides location information when reporting signals of different networks to a base station based on the network being served, and the network determines whether to generate NCR based on the location information.

[0203] FIG. 21 is a flowchart illustrating an example of an ANR management method according to one embodiment of the present specification. In the example of FIG. 21, the types of each of the serving base station and the neighboring base station may be either an NTN base station or a TN base station.

[0204] Referring to FIG. 21, a terminal transmits measurement report information to a serving base station (S2110). Here, the terminal may be in an RRC_CONNECTED state with respect to the serving base station. In addition, the measurement report information may be transmitted periodically or upon an event occurrence. For example, if a measurement report condition based on measurement configuration information provided by the serving base station is satisfied, the terminal may transmit the measurement report information to the serving base station. In addition, the measurement report information may include an identifier for a neighboring base station or neighboring cell, such as a PCI (Physical Cell Identifier).

[0205] Based on the measurement report information, the serving base station searches for the NCRT it manages (S2120). Through this search, the serving base station determines whether the NCRT contains information about the neighboring base station.

[0206] If the NCRT does not include information about the neighboring base station, the serving base station requests the terminal to provide CGI (Cell Global Identifier) ​​information (or NR-CGI information) about the neighboring base station (S2130). Here, the request may be performed by transmitting an RRC connection reconfiguration message or an RRC reconfiguration message.

[0207] The terminal receives system information from the neighboring base station (S2140). Here, the system information may include at least one of a Master Information Block (MIB) and a System Information Block 1 (SIB1).

[0208] The terminal determines the type of the neighboring base station based on the system information (S2150). That is, the terminal determines whether the neighboring base station is a TN base station or an NTN base station based on the system information. Here, for example, the determination may be performed based on an NTN-only access restriction indicator (e.g., cellBarredNTN) included in the system information. For example, when the cellBarredNTN information element is used, if the cellBarredNTN indicates “notbarred,” the terminal determines the neighboring base station as an NTN base station, and if the cellBarredNTN indicates “barred” or the cellBarredNTN is not included in the system information, the terminal determines the neighboring base station as a TN base station. Here, the cellBarredNTN information element may be configured as shown in Table 5. However, the configuration is merely an example, and the NTN-only access restriction indicator of the present specification is not limited to Table 5.

[0209]

[0210] If the type of the neighboring base station is the same as the type of the serving base station, for example, if the serving base station and the neighboring base station are TN base stations and / or if the serving base station and the neighboring base station are NTN base stations, the terminal performs the existing adjacent cell management operation. For example, if the type of the neighboring base station is the same as the type of the serving base station, the terminal can transmit CGI information to the serving base station.

[0211] If the type of the neighboring base station is different from the type of the serving base station, for example, if the serving base station is an NTN base station and the neighboring base station is a TN base station and / or if the serving base station is a TN base station and the neighboring base station is an NTN base station, the terminal transmits CGI information for the neighboring base station and location information of the terminal (S2160). Here, the CGI information may be configured to include the location information. In addition, as an example, when the terminal is receiving service from a TN cell and transmits CGI information for an NTN cell, or when the terminal is receiving service from an NTN cell and transmits CGI information for a TN cell, the terminal may transmit the location information of the terminal together with the CGI information. Table 6 shows an example in which the location information of the terminal is included in the CGI information. In addition, the CGI information may be transmitted in a measurement report message or measurement report information.

[0212]

[0213] The serving base station determines whether to add a relationship to the neighboring base station to the NCRT based on the location information (S2170). Here, the serving base station may obtain information on the NTN service area in advance. That is, the serving base station may be a base station for which an NTN service area has been preset. Here, the information on the NTN service area may be information on the latitude and longitude of the NTN service area. If the NTN service area has not been set for the serving base station, the serving base station may not add / create a relationship to the neighboring base station. Here, the NTN service area may include not only cases where it is distinguished based on a geographical location such as latitude and longitude, but also cases where the signal strength of the NTN base station is lower than a threshold value.

[0214] For example, if the serving base station is a TN base station and the location based on the location information in the NTN cell or the CGI information of the NTN base station received from the terminal is within the NTN service area, the serving base station may add / register the NTN neighboring cell relationship to its NCRT. In addition, if the serving base station is a NTN base station and the location based on the location information in the TN cell or the CGI information of the TN base station received from the terminal is within the NTN service area, the serving base station may add / register the TN neighboring cell relationship to its NCRT. On the other hand, if the location based on the location information is not within the NTN service area, the serving base station may not add / register the neighboring cell relationship for the neighboring base station to its NCRT.

[0215] In other words, base stations in areas requiring differentiation / configuration between NTN cells and TN cells can either store geographic location information of the NTN service area in advance or receive it from the network. Here, the network can request CGI information of neighboring cells / neighboring base stations from the terminal to perform ANR operations based on the information received from the terminal.

[0216] FIG. 22 is a drawing for explaining an example of an ANR management method according to one embodiment of the present specification.

[0217] Referring to Fig. 22, when a terminal receiving service from a TN base station discovers an NTN cell / NTN base station, and then transmits a measurement report message for the NTN cell / NTN base station to the TN base station, the TN base station requests a CGI report / CGI information for the NTN cell / NTN base station from the terminal. At this time, according to one embodiment of the present specification, since the type of the base station from which the terminal receives service is different from the type of the neighboring base station discovered by the terminal, the terminal can transmit the CGI report together with current location information.

[0218] Also, referring to Fig. 22, information on NTN service areas can be set for each TN base station based on CoverageAreaPolygon information. The CoverageAreaPolygon information of Fig. 22 is an example of information for configuring NTN service areas for TN base stations, and the method for configuring / setting NTN service areas is not limited to Fig. 22.

[0219] Here, in the case of terminal 1 of FIG. 22, the serving base station of terminal 1 may be set as an area where NTN / TN overlap is unnecessary. That is, the serving base station of terminal 1 may obtain information on the NTN service area in advance, and, based on the information on the NTN service area, determine that the terminal connected to the serving base station is not provided with the NTN service, and / or, based on the location information of the terminal, determine that the terminal is located in a location where the NTN service is not provided. Therefore, in the case of terminal 1 of FIG. 22, terminal 1 and / or the serving base station of terminal 1 exist in a location where the NTN service is not provided, and in this case, the serving base station of terminal 1 may not reflect (i.e., add / update) the relationship with the NTN base station in its NCRT.

[0220] In addition, in the case of terminal 2 of FIG. 22, the serving base station of terminal 2 may be set to an NTN / TN overlapping area. That is, the serving base station of terminal 2 may obtain information about the NTN service area in advance, and determine that a terminal connected to the serving base station can receive NTN service based on the information about the NTN service area, and / or determine that the terminal is located at a location where NTN service can be provided based on the location information of the terminal. Therefore, in the case of terminal 2 of FIG. 22, terminal 2 and / or the serving base station of terminal 2 exist at a location where NTN service is provided, and in this case, the serving base station of terminal 2 may reflect (i.e., add / update) the relationship with the NTN base station in its NCRT.

[0221] For terminal 3 of FIG. 22, the same procedure as for terminal 2 described above is performed, and for terminal 4 of FIG. 22, the same procedure as for terminal 1 described above is performed. Therefore, redundant descriptions are omitted. Furthermore, the example of FIG. 22 can be applied not only to cases where NTN service areas are distinguished based on geographic locations such as latitude and longitude, but also to cases where the signal strength of an NTN base station is lower than a threshold value.

[0222] FIG. 23 is a flowchart of an example of a method performed by a first base station according to one embodiment of the present specification.

[0223] Referring to FIG. 23, the first base station transmits request information requesting identifier information of the second base station to the terminal (S2310). Here, the first base station may be a base station that has information on the NTN service area, either set in advance or received from the network. In addition, the terminal transmits measurement report information to the first base station before transmitting the request information, and the measurement report information may include a PCI for the second base station. Here, the request information may be transmitted based on the measurement report information. In this case, the identifier information requested by the first base station may be CGI information.

[0224] For example, step S2310 may correspond to step S2130 of FIG. 21. That is, the example of FIG. 23 may correspond to at least a part of the procedure of FIG. 21.

[0225] In response to the request information, the first base station receives response information from the terminal (S2320). Here, the response information may include at least one of the identifier information and the location information of the terminal. At this time, the location information of the terminal may be transmitted by the terminal when the types of the first base station and the second base station are different. Here, the type is one of a TN base station and an NTN base station. In addition, when the types of the first base station and the second base station are the same, the terminal may transmit only the identifier information to the first base station and not transmit the location information of the terminal.

[0226] The first base station performs neighbor cell management for the second base station based on the response information (S2330). Here, based on the response information including the location information of the terminal and the location according to the location information of the terminal being included in the NTN service area according to the information about the NTN service area, i.e., based on the terminal being located in an area where the NTN service can be provided, the first base station may add or update the information about the second base station to the NCRT it manages. Conversely, based on the terminal not being located in an area where the NTN service can be provided, the first base station may not reflect (e.g., add, update, etc.) the information about the second base station to the NCRT it manages.

[0227] Meanwhile, a Satellite Terrestrial Integrated Network (STIN) scenario integrating low-Earth orbit satellite-based satellite networks and terrestrial networks could be considered in next-generation wireless communication systems. Low-Earth orbit satellites typically orbit at low altitudes of 2,000 km or less. To maintain a constant orbit and orbit the Earth, these satellites must orbit at a very high speed of approximately 7 km / s. Therefore, handovers are essential for providing communication services via low-Earth orbit satellites, even if the mobile terminal is stationary. For example, even if we assume a fixed cell and maintain the satellite's LoS (Line of Sight) as much as possible for a user in a fixed, stationary location on the ground, a handover to the serving satellite would be required at least once every 10 minutes for a 1,000 km-altitude satellite. However, satellites for commercial purposes are mainly deployed or planned at altitudes below 600 km, and if realistic satellite visibility, minimum elevation angle for connection, and satellite beam switching are taken into consideration, the satellite handover cycle is expected to be reduced even further, requiring handovers in the order of seconds.

[0228] Here, handover refers to the process of switching a connection from a currently connected base station (or source base station) to another base station (or target base station) while a mobile terminal is moving. Handover allows the user to maintain a continuous connection without interrupting calls or data services. Handover is primarily determined based on signal strength, base station capacity, and the user's movement path, and is a key technology in mobile systems that improves network quality and user experience.

[0229] To prepare for handover procedures, the base station currently serving the network must acquire information about neighboring base stations. One way to obtain this information is through the Automatic Neighbor Relation (ANR) feature. ANR automation allows for seamless management of neighboring cell relationships.

[0230] At this time, a base station can maintain optimal handover conditions by managing attributes for other neighboring base stations in a table (Neighbor Cell Relation Table: NCRT). Information about other neighboring base stations can be obtained through the Measurement Report message transmitted by the terminal to the base station. Examples of attributes that serve as NCRT identifiers include the following:

[0231] - No Remove: Prevents deletion of the corresponding base station from NRCT.

[0232] - No HO: Handover to the base station is prohibited.

[0233] - No Xn: Prevent handover of Xn interface between base stations to the corresponding base station.

[0234] Although the importance of handover in satellite scenarios has been widely discussed, most of the existing techniques for satellite handover focus on satellite-to-satellite handover when providing services using only satellites, and little is known about the STIN scenario, which performs handover from satellite to ground cell as needed.

[0235] In STIN, where satellite networks and terrestrial networks coexist, network complexity is expected to increase further, and the ANR function based on terrestrial network standards is expected to become more important. However, due to the dynamic and energy-constrained characteristics of satellites, there are limitations in directly applying the ANR function used in terrestrial networks to satellite communications.

[0236] Hereinafter, in a satellite-terrestrial integrated network (STIN), in particular, when a ground terminal is receiving service through a satellite or NTN base station, an additional function for ANR table update / management is proposed to overcome the different characteristics and limitations of the satellite base station compared to the ground network when using the ANR function for handover to the ground base station.

[0237] Typically, for low-Earth orbit satellites, the Earth rotates while the satellite orbits at high speeds. Therefore, a single satellite will pass around the entire Earth within the inclination of its orbit. This means that, from the perspective of a moving satellite base station, the ANR table for neighboring cells on the ground must either include nearly every terrestrial base station on the planet, or support the addition and deletion of neighboring cells at very high speeds.

[0238] Even for terminals that do not have mobility on the surface of the earth, handover must be decided because the satellite base station has limited service time for the terminal.

[0239] To address the aforementioned issues, this specification defines additional identifiers / delimiters for new attributes in the ANR table and proposes a procedure for updating terrestrial neighbor cell information for satellite base stations by utilizing these attributes. This allows ground terminals to decide to handover to the ground before losing connection with the satellite, and proposes ANR functionality for satellite base stations that can operate on satellites with limited power consumption and capacity.

[0240] Referring to Figure 10, the adjacent cell measurement entity can forward measurement requests to the RRC layer and receive measurement reports from the RRC layer. Additionally, the adjacent cell relationship table management entity can forward NCR reports to the OAM and receive NCR add / update commands. Furthermore, as an example, the NCRT can be configured as shown in the following table.

[0241] NCRTCINo RemoveNo HONo

[0242] Also, in the example of FIG. 13, if Cell A is replaced with a low-Earth orbit satellite base station, one low-Earth orbit satellite base station will ultimately perform the procedure of FIG. 13 for Cell B on the ground that is newly installed or newly encounters coverage globally, and all of this information can be added / updated to the ANR table of Cell A, which is a satellite base station. Here, considering satellites at the same altitude, in the case of satellites that form the same constellation (i.e., arrangement of constellation satellites with the same altitude and inclination but different orbital offsets, etc.), each of the satellites will generate and update an NCRT of a very large volume that is almost identical.

[0243] This structure may not be suitable for satellite base station environments operating under constraints, and it may be inefficient because as the NCRT size increases, the search time in the table also increases significantly. To address this, a novel neighbor cell detection process and NCRT management method for satellite base stations are proposed below. This allows satellite base stations to efficiently operate NCRT, and TN cells that fall outside the satellite base station's coverage area are removed from the satellite base station's local NCRT, effectively controlling the NCRT size.

[0244] Meanwhile, in this specification, NCRT can be divided into Global NCRT and Local NCRT. The Global NCRT of a satellite constellation refers to an ANR table for all TN neighboring cells updated for a single satellite constellation, and the TN neighboring cells can be distinguished / classified by a TN identifier and stored in the Global NCRT. Here, a satellite constellation can refer to a satellite constellation system, which is a group of satellites (tens to tens of thousands) that cooperate with each other and operate as one body. The Global NCRT can be stored and updated in a device that performs the function of a mobility controller of an NTN base station (or satellite base station) of a Satellite Network Operator (SNO). In addition, the Local NCRT of a satellite base station (or NTN base station) refers to an NCRT that stores and updates only the information necessary for ANR for a single satellite base station, and can be stored onboard the satellite base station itself.

[0245] In addition, in this specification, with respect to the NCGI acquisition procedure of the NTN base station, when the terminal calculates and acquires the NCGI through system information such as SIB1 in step 3 of FIG. 13 and reports it to the NTN base station through a measurement report message, additional information may be included in the measurement report message. Here, the additional information may include an identifier for a new TN base station, information about a timer indicating a time at which the NTN base station can perform a handover, etc. For example, the additional information may further include at least one of the following information.

[0246] - TN Group Code: An example of an identifier for a TN base station. Since satellites cover the entire globe, this refers to a code that identifies which TN group the neighboring cell currently passing by the satellite belongs to. For example, the identifier can be defined / distinguished by mobile carrier, region, or TAC (Tracking Area Code).

[0247] - Timestamp: An example of an identifier for a TN base station, indicating the range of times during which the satellite passes that neighboring cell.

[0248] - Out of coverage timer: In the example of Fig. 13, this represents the remaining time that the satellite base station, Cell A, can perform a handover while orbiting the location of the neighboring Cell B. Here, assuming that the satellite base station orbits in a circular orbit, and assuming that the latitude-longitude coordinates and altitude of the satellite and Cell B, the orbital direction of the satellite, and the minimum elevation angle of the satellite are known, the terminal and / or the base station can calculate the remaining service time by utilizing Kepler's law in a polar coordinate system.

[0249] Fig. 24 is a flowchart illustrating an example of an ANR management method according to one embodiment of the present specification. The example of Fig. 24 assumes that a terminal is connected to a satellite base station or an NTN base station. In addition, the NTN base station mobility controller of Fig. 24 is defined as a device or function that stores a global NCRT of a satellite constellation, which may be located in the satellite base station itself depending on the implementation, and may be defined as a base station, software, core network device or function that manages the mobility of multiple base stations, such as the core of a Satellite Network Operator (SNO) or an Access and Mobility Management function (AMF).

[0250] Referring to Figure 24, the terminal detects a neighboring TN base station (S2410). Thereafter, the terminal transmits a first report message regarding the neighboring TN base station to the NTN base station (S2420). The NTN base station checks whether information regarding the neighboring TN base station exists in the NCRT managed by the NTN base station (e.g., the local NCRT of the NTN base station) (S2430).

[0251] Here, for example, if information about the adjacent TN base station is included in the NCRT managed by the NTN base station and an out-of-coverage timer for the adjacent TN base station is not set, the NTN base station calculates the value of the out-of-coverage timer for the adjacent TN base station (S2431).

[0252] As another example, if information about the adjacent TN base station is not included in the NCRT managed by the NTN base station, the NTN base station transmits a request message requesting information about the adjacent TN base station to the terminal (S2432). Based on the request message, the terminal obtains information about the adjacent TN base station (e.g., a CGI (Cell Global Identifier) ​​for the adjacent TN base station, etc.) (S2440). At this time, the terminal can obtain information about the adjacent TN base station through system information transmitted by the adjacent TN base station.

[0253] Thereafter, the terminal transmits the information about the adjacent TN base station obtained to the NTN base station (S2450). Based on the information about the adjacent TN base station, the NTN base station determines whether the NCRT managed by the NTN base station (e.g., the local NCRT of the NTN base station) includes an identifier for the TN base station (S2460).

[0254] FIG. 25 is a flowchart illustrating an example of an ANR management method according to one embodiment of the present specification. Here, FIG. 25 illustrates a flowchart for operations subsequent to step S2460 of FIG. 24.

[0255] Referring to FIG. 25, it is determined whether an identifier for a TN base station is included in an NCRT managed by an NTN base station (e.g., a local NCRT of the NTN base station), and if an identifier for the TN base station exists in the local NCRT but the TN base station is identified as a new base station, the NTN base station requests an update of a global NCRT to an NTN base station mobility controller (S2510). Thereafter, the NTN base station mobility controller transmits a target TN base station information request message requesting information about the target TN base station to a target TN AMF based on the request (S2520). Here, the target TN AMF may be an AMF that manages the adjacent TN base station.

[0256] The target TN AMF transmits an information report message of the target TN base station to the NTN base station mobility controller in response to the target TN base station information request message (S2530). Here, the information report message of the target TN base station may include information about the target TN base station, such as additional information such as the CGI of the adjacent TN base station, the TN identification code, the timestamp, and the value of the out-of-coverage timer. The NTN base station mobility controller updates the NCRT (e.g., global NCRT) it manages based on the information report message of the target TN base station (S2540). Thereafter, the NTN base station mobility controller transmits the information report message of the target TN base station to the NTN base station (S2550). Here, the information report message of the target TN base station in step S2550 may have the same context and format as the information report message of the target TN base station in step S2530, or may have the same context but a different format. Thereafter, the NTN base station updates the NCRT (e.g., local NCRT) it manages based on the information report message of the target TN base station (S2531).

[0257] Alternatively, referring to FIG. 25, it is determined whether an identifier for a TN base station is included in the NCRT managed by the NTN base station (e.g., a local NCRT of the NTN base station), and if an identifier for the TN base station does not exist in the local NCRT, the NTN base station requests NCR information for an identical identifier group from the NTN base station mobility controller (S2511). Here, the identical identifier group may mean a group of base stations having the same TN identification code and timestamp as described above.

[0258] In response to the request, the NTN base station receives NCR information for the same identifier group from the NTN base station mobility controller (S2521). Thereafter, the NTN base station updates the NCRT (e.g., local NCRT) it manages based on the NCR information for the same identifier group (S2531).

[0259] FIG. 26 illustrates an example of a local NCRT and a global NCRT according to one embodiment of the present specification.

[0260] Referring to Fig. 26, the local NCRT is located at the satellite base station, and the satellite base station can store information about the ground neighboring cells activated for the satellite base station as NCRT. In addition, the global NCRT refers to the NCRT for the entire satellite configuration model when it orbits the entire Earth, and the storage location of the global NCRT is not limited to a specific location among the SNO core or the satellite base station, and can be defined according to the implementation. Referring to Fig. 26, the satellite ANR procedure proposed in this specification can be initiated when a new neighboring TN base station, such as ground base station 3, is detected by a user terminal report.

[0261] For example, referring to FIG. 26, a local NCRT managed by a specific satellite base station (or NTN base station) may include TCI (Transmission Configuration Indicator), No Remove, No HO, No XN, identifier, and timer items by NCR (Neighbor Cell Relation) index. Here, the No Remove item may be an item indicating whether to prohibit deletion of the corresponding base station, the No HO item may be an item indicating whether to prohibit handover to the corresponding base station, and the No Xn item may be an item indicating whether to prohibit Xn interface handover between base stations to the corresponding base station. In addition, the TCI item may be an indicator identifying a QCL (quasi co-location) relationship between reference signals such as CSI-RS. In addition, the identifier item may mean a TN identification code or an identifier for identifying a group of base stations having the same TN identification code and timestamp. In addition, the timer item may mean a value of an out-of-coverage timer.

[0262] Also, referring to FIG. 26, a global NCRT managed by a specific satellite base station or NTN base station mobility controller may include TCI (Transmission Configuration Indicator), No Remove, No HO, No XN, and identifier items by NCR (Neighbor Cell Relation) index. Since the descriptions of the above items are the same as those described above, redundant descriptions are omitted.

[0263] FIG. 27 is a diagram of another example of ANR-based interaction between a base station and an Operation, Administration and Management (OAM) according to one embodiment of the present specification.

[0264] Referring to FIG. 27, the ANR function of a satellite base station (or NTN base station) sends a report message to a device that manages the mobility of the satellite base station (e.g., a satellite base station mobility controller), and if there is no NCR identified in the global NCRT managed within the core of the SNO or the satellite base station, the global NCRT update procedure can be performed by sending an NCR report back to the AMF of the ground core. Although FIG. 27 depicts the local NCRT and the global NCRT as being managed by different devices in order to illustrate the logical flow, if the satellite base station mobility controller is implemented within a specific satellite base station, the global NCRT update procedure can also be implemented as a procedure that accesses a memory that stores the global NCRT within the specific satellite base station.

[0265] In the global NCRT, information on the TN group identifier or TN identifier among the identifiers / delimiters proposed in this specification can be additionally stored. In addition, since the global NCRT requires relatively large storage capacity and transmits necessary information to the local NCRT, the necessary NCRs must be efficiently searched. This requirement may be required regardless of the location of the equipment performing the function of the satellite base station mobility controller, and in order for the satellite base station to implement this function, the satellite base station must be able to provide sufficient memory capacity for this. To this end, the global NCRT classifies NCRs by identifier, so that when searching for a specific NCR, only the type of the identifier is searched, and all data corresponding to the classification can be transmitted. For example, the global NCRT can be implemented as a hash table, and the key value of the hash table can be implemented by defining it as an identifier.

[0266] Below, the add algorithm, the NCRT management function of the ANR function, and the additional functions for the existing ANR of the remove algorithm are specifically described to update the local NCRT for one satellite base station.

[0267] Referring to Fig. 27, the additional algorithm of the local NCRT may differ in the information exchanged between the AMF and the ANR function of the satellite base station compared to the example of Fig. 8. Specifically, if there is no NCR information corresponding to an identifier (e.g., a TN identifier or a TN group identifier) ​​identical to the identifier of a neighboring cell (or adjacent base station) included in the report information received from the terminal within the NCRT of a specific satellite base station, the NTN base station mobility controller may transmit information corresponding to all NCRs classified with the same identifier as the neighboring cell in the global NCRT managed by the NTN base station to the ANR function of the specific satellite base station. Thereafter, the satellite base station may add the information to the local NCRT. At this time, the timers of the remaining NCRs excluding the neighboring cell may be added / updated as blank.

[0268] Also, referring to FIG. 27, in relation to the NCRT management function of the ANR function, when the ANR function of the satellite base station receives a measurement report from a terminal, if a timer (out-of-coverage timer) corresponding to the corresponding CID (Cell ID) is not defined, the satellite base station can request location information from the ground cell (or TN base station), and the satellite base station can calculate the remaining service time and add the timer value to the local NCRT.

[0269] In addition, the timer is decreased by a unit of time by the NCRT management function (or the neighboring cell relationship table management entity) by determining an update cycle at the satellite base station. Here, when the value of the timer becomes 0, the NCRT management function (or the neighboring cell relationship table management entity) can update the status of the corresponding NCR within the local NCRT to a handover prohibited state (no HO).

[0270] Furthermore, regarding the local NCRT removal algorithm, when the ANR procedure is applied to a satellite communication system, NCR information from a satellite base station that rapidly moves around the globe may persist even after it has recently left coverage. This can lead to inefficiencies due to excessive storage of unnecessary information. To address this, we propose a removal algorithm that, like the addition algorithm, removes NCRs from the local NCRT on a group basis. Here, even if an NCR is removed from the local NCRT, it may not be removed from the global NCRT of the satellite constellation.

[0271] For example, if both conditions 1 and 2 below are satisfied, it is determined that the satellite base station is out of coverage of the same identifier group, and all NCRs of the group can be removed from the local NCRT.

[0272] - Condition 1: The timer values ​​of all NCRs with non-blank timer entries among the NCRs of the corresponding identifier are 0, and the NCR is in no HO state.

[0273] - Condition 2: No new timer value is generated because there are no measurement reports for that identifier for a period of time (e.g., 1 minute) after the state of Condition 1.

[0274] FIG. 28 is a flowchart of an example of an NCRT management method according to one embodiment of the present specification.

[0275] Referring to FIG. 28, the base station receives a measurement report message from the terminal (S2810). Here, the measurement report message may include at least one of measurement information (e.g., RSRP, RSRQ, etc.) for a neighboring base station to the terminal and a cell identifier (e.g., PCI, etc.) for the neighboring base station. Here, the base station may be an NTN base station (or satellite base station), and the neighboring base station may be a TN base station.

[0276] The base station checks whether the NCRT managed by the base station includes information about the neighboring base station (S2820). Here, the NCRT managed by the base station may refer to the local NCRT proposed in this specification. That is, the NCRT may be divided into a global NCRT and a local NCRT. The global NCRT of a satellite constellation refers to an ANR table for all TN neighboring cells updated for one satellite constellation, and the TN neighboring cells may be distinguished / classified by a TN identifier and stored in the global NCRT. Here, the satellite constellation may refer to a satellite constellation system, which is a group of satellites (tens to tens of thousands) that cooperate with each other and operate as one body. The global NCRT may be stored and updated in a device that performs the function of a mobility controller of an NTN base station (or satellite base station) of an SNO (Satellite Network Operator). Additionally, the local NCRT of a satellite base station (or NTN base station) refers to an NCRT that stores and updates only the information necessary for ANR for a single satellite base station, and can be stored onboard the satellite base station itself. In other words, the local NCRT may be a subset of the global NCRT.

[0277] If information about the neighboring base station is included in the NCRT managed by the base station, the base station adds additional information about the neighboring base station to the NCRT managed by the base station (S2831). Here, the additional information may include the value of an out-of-coverage timer for the neighboring base station. At this time, the out-of-coverage timer may be a timer indicating the remaining time during which the base station can perform a handover while orbiting the location of the neighboring base station. Here, assuming that the base station orbits in a circular orbit and assuming that the latitude-longitude coordinates and altitude of the base station and the neighboring base station, the orbital direction of the base station, and the minimum elevation angle of the base station are known, the base station can calculate the remaining possible handover time for the neighboring base station by utilizing Kepler's law in a polar coordinate system. In addition, the additional information may include an identifier for the neighboring base station. Here, the identifier may be a group identifier that identifies a plurality of base stations including the neighboring base station as a specific group. At this time, the specific group may be defined by mobile carrier unit, regional identifier, or TAC (Tracking Area Code) unit.

[0278] If the information about the adjacent base station is not included in the NCRT managed by the base station, the base station receives the information about the adjacent base station from the terminal (S2832). Here, the information about the adjacent base station may be transmitted in response to a request message transmitted by the base station.

[0279] Thereafter, the base station determines whether the identifier for the neighboring base station is included in the NCRT managed by the base station. Here, if the identifier for the neighboring base station exists in the NCRT managed by the base station as a result of the determination, but the neighboring base station is identified as a new base station, the base station may request an update of the global NCRT to the NTN base station mobility controller. Thereafter, the NTN base station mobility controller may transmit a neighboring base station information request message requesting information about the neighboring base station to a target TN AMF based on the request. Here, the target TN AMF may be an AMF managing the neighboring base station.

[0280] The target TN AMF may transmit an information report message of a neighboring base station to the NTN base station mobility controller in response to the neighboring base station information request message. Here, the information report message of the neighboring base station may include information about the neighboring base station, such as additional information such as a CGI, a TN identification code, a timestamp, and a value of an out-of-coverage timer of the neighboring base station. The NTN base station mobility controller may update an NCRT (or a global NCRT) managed by the NTN base station mobility controller based on the information report message of the neighboring base station. Thereafter, the NTN base station mobility controller may transmit an information report message of the neighboring base station to the base station. Thereafter, the base station may update the NCRT managed by the base station based on the information report message of the neighboring base station.

[0281] Alternatively, if, as a result of the above determination, there is no identifier for the adjacent base station in the NCRT managed by the base station, the base station may request NCR information for the same identifier group from the NTN base station mobility controller. Here, the same identifier group may mean a group of base stations having the same TN identification code and timestamp as described above.

[0282] The base station may receive NCR information for the same identifier group from the NTN base station mobility controller in response to the request. Thereafter, the base station may update the NCRT managed by the base station based on the NCR information for the same identifier group.

[0283] Meanwhile, with regard to the example of Fig. 28, the embodiments and methods proposed in this specification can be applied. Therefore, redundant descriptions are omitted.

[0284] Below, an example of a communication system to which the present invention is applied is described.

[0285] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods and / or operational flowcharts of the present invention disclosed in this document may be applied to various fields requiring wireless communication / connection (e.g., 5G) between devices.

[0286] Hereinafter, more specific examples will be provided with reference to the drawings. In the drawings / descriptions below, the same drawing reference numerals may represent identical or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise described.

[0287] Figure 29 illustrates a communication system (1) applied to the present invention.

[0288] Referring to FIG. 29, a communication system (1) applied to the present invention includes a wireless device, a base station, and a network. Here, the wireless device refers to a device that performs communication using a wireless access technology (e.g., 5G NR (New RAT), LTE (Long Term Evolution)) and may be referred to as a communication / wireless / 5G device. Although not limited thereto, the wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (eXtended Reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Things) device (100f), and an AI device / server (400). For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Here, the vehicle may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). XR devices include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices, and can be implemented in the form of HMD (Head-Mounted Device), HUD (Head-Up Display) installed in a vehicle, television, smartphone, computer, wearable device, home appliance, digital signage, vehicle, robot, etc. Mobile devices can include smartphone, smart pad, wearable device (e.g., smart watch, smart glass), computer (e.g., laptop, etc.), etc. Home appliances can include TV, refrigerator, washing machine, etc. IoT devices can include sensors, smart meters, etc. For example, base stations and networks can also be implemented as wireless devices, and a specific wireless device (200a) can act as a base station / network node to other wireless devices.

[0289] Here, the wireless communication technology implemented in the wireless device of the present specification may include not only LTE, NR, and 6G, but also Narrowband Internet of Things for low-power communication. At this time, for example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology, and may be implemented with standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device of the present specification may perform communication based on LTE-M technology. At this time, for example, LTE-M technology may be an example of LPWAN technology, and may be called by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology can be implemented by at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the above-described names. Additionally or alternatively, the wireless communication technology implemented in the wireless device of the present specification can include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) considering low-power communication, and is not limited to the above-described names. For example, ZigBee technology can create personal area networks (PANs) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and can be called by various names.

[0290] Wireless devices (100a to 100f) can be connected to a network (300) via a base station (200). Artificial Intelligence (AI) technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) via the network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, etc. The wireless devices (100a to 100f) can communicate with each other via the base station (200) / network (300), but can also communicate directly (e.g., sidelink communication) without going through the base station / network. For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (Vehicle to Vehicle) / V2X (Vehicle to Everything) communication). In addition, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0291] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a~100f) / base stations (200), and base stations (200) / base stations (200). Here, wireless communication / connection can be achieved through various wireless access technologies (e.g., 5G NR) such as uplink / downlink communication (150a), sidelink communication (150b) (or D2D communication), and communication between base stations (150c) (e.g., relay, IAB (Integrated Access Backhaul). Through wireless communication / connection (150a, 150b, 150c), wireless devices and base stations / wireless devices, and base stations and base stations can transmit / receive wireless signals to each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, at least some of various configuration information setting processes for transmitting / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation processes can be performed based on various proposals of the present invention.

[0292] Figure 30 illustrates a wireless device applicable to the present invention.

[0293] Referring to FIG. 30, the first wireless device (100) and the second wireless device (200) can transmit and receive wireless signals via various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device (100), the second wireless device (200)} can correspond to {the wireless device (100x), the base station (200)} and / or {the wireless device (100x), the wireless device (100x)} of FIG. 29.

[0294] A first wireless device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (106) and / or one or more antennas (108). The processor (102) controls the memories (104) and / or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein. For example, the processor (102) may process information in the memory (104) to generate first information / signals, and then transmit a wireless signal including the first information / signals via the transceivers (106). Furthermore, the processor (102) may receive a wireless signal including second information / signals via the transceivers (106), and then store information obtained from signal processing of the second information / signals in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed herein. Here, the processor (102) and the memory (104) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (106) may be connected to the processor (102) and may transmit and / or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and / or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present invention, a wireless device may also mean a communication modem / circuit / chip.

[0295] The second wireless device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and / or one or more antennas (208). The processor (202) controls the memories (204) and / or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein. For example, the processor (202) may process information in the memory (204) to generate third information / signals, and then transmit a wireless signal including the third information / signals via the transceivers (206). In addition, the processor (202) may receive a wireless signal including fourth information / signals via the transceivers (206), and then store information obtained from signal processing of the fourth information / signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed herein. Here, the processor (202) and the memory (204) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206) may be connected to the processor (202) and may transmit and / or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and / or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present invention, a wireless device may also mean a communication modem / circuit / chip.

[0296] Hereinafter, the hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this document. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed in this document. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and / or methods disclosed herein, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and / or operational flowcharts disclosed herein.

[0297] One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and / or operational flowcharts disclosed herein may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, suggestions, methods and / or operation flowcharts invented in this document may be implemented using firmware or software configured to perform one or more processors (102, 202) or stored in one or more memories (104, 204) and driven by one or more processors (102, 202). The descriptions, functions, procedures, suggestions, methods and / or operation flowcharts invented in this document may be implemented using firmware or software in the form of codes, instructions and / or sets of instructions.

[0298] One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. The one or more memories (104, 204) may be located internally and / or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

[0299] One or more transceivers (106, 206) can transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or flowcharts of this document, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or flowcharts of this document, from one or more other devices. For example, one or more transceivers (106, 206) can be connected to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals / channels, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and / or operational flowcharts of the present document, via one or more antennas (108, 208). In the present document, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) can convert received user data, control information, wireless signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals / channels, etc. using one or more processors (102, 202).One or more transceivers (106, 206) may convert user data, control information, wireless signals / channels, etc. processed by one or more processors (102, 202) from baseband signals to RF band signals. For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and / or filter.

[0300] Figure 31 illustrates a process for generating a transmission signal in a transmitter.

[0301] Referring to FIG. 31, the signal processing circuit (1000) may include a scrambler (1010), a modulator (1020), a layer mapper (1030), a precoder (1040), a resource mapper (1050), and a signal generator (1060). Although not limited thereto, the operations / functions of FIG. 31 may be performed in the processor (102, 202) and / or the transceiver (106, 206) of FIG. 30. The hardware elements of FIG. 31 may be implemented in the processor (102, 202) and / or the transceiver (106, 206) of FIG. 30. For example, blocks 1010 to 1060 may be implemented in the processor (102, 202) of FIG. 30. Additionally, blocks 1010 to 1050 may be implemented in the processor (102, 202) of FIG. 30, and block 1060 may be implemented in the transceiver (106, 206) of FIG. 30.

[0302] The codeword can be converted into a wireless signal through the signal processing circuit (1000) of FIG. 31. Here, the codeword is an encoded bit sequence of an information block. The information block can include a transport block (e.g., an UL-SCH transport block, a DL-SCH transport block). The wireless signal can be transmitted through various physical channels (e.g., a PUSCH or a PDSCH).

[0303] Specifically, the codeword can be converted into a bit sequence scrambled by a scrambler (1010). The scramble sequence used for scrambling is generated based on an initialization value, and the initialization value may include ID information of the wireless device, etc. The scrambled bit sequence can be modulated into a modulation symbol sequence by a modulator (1020). The modulation method may include pi / 2-BPSK (pi / 2-Binary Phase Shift Keying), m-PSK (m-Phase Shift Keying), m-QAM (m-Quadrature Amplitude Modulation), etc. The complex modulation symbol sequence can be mapped to one or more transmission layers by a layer mapper (1030). The modulation symbols of each transmission layer can be mapped to the corresponding antenna port(s) by a precoder (1040) (precoding). The output z of the precoder (1040) can be obtained by multiplying the output y of the layer mapper (1030) by a precoding matrix W of N*M. Here, N is the number of antenna ports, and M is the number of transmission layers. Here, the precoder (1040) can perform precoding after performing transform precoding (e.g., DFT transform) on complex modulation symbols. In addition, the precoder (1040) can perform precoding without performing transform precoding.

[0304] The resource mapper (1050) can map modulation symbols of each antenna port to time-frequency resources. The time-frequency resources can include multiple symbols (e.g., CP-OFDM symbols, DFT-s-OFDM symbols) in the time domain and multiple subcarriers in the frequency domain. The signal generator (1060) generates a wireless signal from the mapped modulation symbols, and the generated wireless signal can be transmitted to another device through each antenna. To this end, the signal generator (1060) can include an Inverse Fast Fourier Transform (IFFT) module, a Cyclic Prefix (CP) inserter, a Digital-to-Analog Converter (DAC), a frequency uplink converter, etc.

[0305] The signal processing process for receiving signals in a wireless device can be configured in reverse order of the signal processing process (1010 to 1060) of FIG. 31. For example, a wireless device (e.g., 100, 200 of FIG. 30) can receive wireless signals from the outside through an antenna port / transceiver. The received wireless signals can be converted into baseband signals through a signal restorer. For this purpose, the signal restorer can include a frequency downlink converter, an analog-to-digital converter (ADC), a CP remover, and a fast Fourier transform (FFT) module. Thereafter, the baseband signal can be restored to a codeword through a resource demapper process, a postcoding process, a demodulation process, and a descrambling process. The codewords can be restored to the original information blocks through decoding. Accordingly, a signal processing circuit (not shown) for a received signal may include a signal restorer, a resource de-mapper, a postcoder, a demodulator, a de-scrambler, and a decoder.

[0306] Figure 32 illustrates another example of a wireless device applicable to the present invention. The wireless device may be implemented in various forms depending on the use case / service.

[0307] Referring to FIG. 32, the wireless device (100, 200) corresponds to the wireless device (100, 200) of FIG. 30 and may be composed of various elements, components, units / units, and / or modules. For example, the wireless device (100, 200) may include a communication unit (110), a control unit (120), a memory unit (130), and additional elements (140). The communication unit may include a communication circuit (112) and a transceiver(s) (114). For example, the communication circuit (112) may include one or more processors (102, 202) and / or one or more memories (104, 204) of FIG. 30. For example, the transceiver(s) (114) may include one or more transceivers (106, 206) and / or one or more antennas (108, 208) of FIG. 30. The control unit (120) is electrically connected to the communication unit (110), the memory unit (130), and the additional elements (140) and controls the overall operation of the wireless device. For example, the control unit (120) may control the electrical / mechanical operation of the wireless device based on the program / code / command / information stored in the memory unit (130). In addition, the control unit (120) may transmit information stored in the memory unit (130) to an external device (e.g., another communication device) via a wireless / wired interface through the communication unit (110), or store information received from an external device (e.g., another communication device) via a wireless / wired interface in the memory unit (130).

[0308] The additional element (140) may be configured in various ways depending on the type of the wireless device. For example, the additional element (140) may include at least one of a power unit / battery, an input / output unit (I / O unit), a driving unit, and a computing unit. Although not limited thereto, the wireless device may be implemented in the form of a robot (Fig. 29, 100a), a vehicle (Fig. 29, 100b-1, 100b-2), an XR device (Fig. 29, 100c), a portable device (Fig. 29, 100d), a home appliance (Fig. 29, 100e), an IoT device (Fig. 29, 100f), a digital broadcasting terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or a financial device), a security device, a climate / environmental device, an AI server / device (Fig. 29, 400), a base station (Fig. 29, 200), a network node, etc. Wireless devices may be mobile or stationary depending on the use / service.

[0309] In FIG. 32, various elements, components, units / parts, and / or modules within the wireless device (100, 200) may be entirely interconnected via a wired interface, or at least some may be wirelessly connected via a communication unit (110). For example, within the wireless device (100, 200), the control unit (120) and the communication unit (110) may be wired, and the control unit (120) and a first unit (e.g., 130, 140) may be wirelessly connected via the communication unit (110). In addition, each element, component, unit / part, and / or module within the wireless device (100, 200) may further include one or more elements. For example, the control unit (120) may be composed of a set of one or more processors. For example, the control unit (120) may be composed of a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing processor, a memory control processor, etc. As another example, the memory unit (130) may be composed of RAM (Random Access Memory), DRAM (Dynamic RAM), ROM (Read Only Memory), flash memory, volatile memory, non-volatile memory, and / or a combination thereof.

[0310] The claims set forth in this specification may be combined in various ways. For example, the technical features of the method claims of this specification may be combined to implement a device, and the technical features of the device claims of this specification may be combined to implement a method. Furthermore, the technical features of the method claims and the technical features of the device claims of this specification may be combined to implement a device, and the technical features of the method claims and the technical features of the device claims of this specification may be combined to implement a method. Furthermore, the embodiments set forth in this specification may be combined as long as they are not mutually incompatible.

Claims

In a method performed by a base station in a wireless communication system, Send a report request message to the terminal, Receive a report response message from the terminal based on the above report request message, and Modify the NCRT (Neighbor Cell Relation Table) based on the above report response message. Based on the above report response message including a network type indicator for the network type of the neighboring base station of the terminal, the network type indicator indicates whether the neighboring base station is a TN (Terrestrial Network) base station or an NTN (Non-Terrestrial Network) base station, A method characterized in that the NCRT includes a network type field indicating whether each of the plurality of base stations is a TN base station or an NTN base station. In the first paragraph, Based on the fact that the identifier for the neighboring base station included in the measurement report message transmitted by the terminal to the base station does not exist in the NCRT, the base station transmits the report request message to the terminal, A method characterized in that, based on the fact that the neighboring base station is not included in the NCRT, the base station adds the neighboring base station to the NCRT. In the first paragraph, A method characterized in that the base station determines the neighboring base station as a TN base station based on the above report response message not including the network type indicator. In the first paragraph, The base station transmits an NG setup message including a network type field indicating whether the network type is TN or NTN to an AMF (Access and Mobility Management Function) entity connected to the base station, Based on the above base station being a TN base station, the above AMF is an AMF for TN, A method characterized in that the AMF is an AMF for NTN, based on the above base station being an NTN base station. In the first paragraph, The above report request message is included in the RRC connection reconfiguration message, A method characterized in that the terminal is in an RRC_CONNECTED state with respect to the base station, and the base station stores and manages the NCRT. In the first paragraph, The above report response message includes at least one of identifier information for the neighboring base station, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network), A method characterized in that at least one of identifier information, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network) for the neighboring base station included in the above report response message is included in the system information for the neighboring base station. In paragraph 6, Based on the above system information including an NTN-only access restriction indicator for the neighboring base station and the NTN-only access restriction indicator indicating access restriction, the neighboring base station is determined to be a TN base station, Based on the above system information including the NTN-only access restriction indicator and the NTN-only access restriction indicator indicating access permission, the neighboring base station is determined to be an NTN base station, A method characterized in that the neighboring base station is determined to be a TN base station based on the above system information not including the NTN-only access restriction indicator. The base station is, One or more memories that store instructions; one or more transmitters and receivers; and One or more processors connecting the one or more memories and the one or more transceivers, wherein the one or more processors execute the instructions, Send a report request message to the terminal, Receive a report response message from the terminal based on the above report request message, and Modify the NCRT (Neighbor Cell Relation Table) based on the above report response message. Based on the above report response message including a network type indicator for the network type of the neighboring base station of the terminal, the network type indicator indicates whether the neighboring base station is a TN (Terrestrial Network) base station or an NTN (Non-Terrestrial Network) base station, A device characterized in that the NCRT includes a network type field indicating whether each of the plurality of base stations is a TN base station or an NTN base station. In paragraph 8, Based on the fact that the identifier for the neighboring base station included in the measurement report message transmitted by the terminal to the base station does not exist in the NCRT, the base station transmits the report request message to the terminal, A device characterized in that, based on the fact that the neighboring base station is not included in the NCRT, the base station adds the neighboring base station to the NCRT. In paragraph 8, A device characterized in that the base station determines the neighboring base station as a TN base station based on the above report response message not including the network type indicator. In paragraph 8, The base station transmits an NG setup message including a network type field indicating whether the network type is TN or NTN to an AMF (Access and Mobility Management Function) entity connected to the base station, Based on the above base station being a TN base station, the above AMF is an AMF for TN, A device characterized in that the AMF is an AMF for NTN, based on the above base station being an NTN base station. In paragraph 8, The above report request message is included in the RRC connection reconfiguration message, A device characterized in that the terminal is in an RRC_CONNECTED state with respect to the base station, and the base station stores and manages the NCRT. In paragraph 8, The above report response message includes at least one of identifier information for the neighboring base station, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network), A device characterized in that at least one of identifier information, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network) for the neighboring base station included in the report response message is included in the system information for the neighboring base station. In Article 13, Based on the above system information including an NTN-only access restriction indicator for the neighboring base station and the NTN-only access restriction indicator indicating access restriction, the neighboring base station is determined to be a TN base station, Based on the above system information including the NTN-only access restriction indicator and the NTN-only access restriction indicator indicating access permission, the neighboring base station is determined to be an NTN base station, A device characterized in that the neighboring base station is determined to be a TN base station based on the above system information not including the NTN-only access restriction indicator. In a method performed by a terminal in a wireless communication system, Receive a report request message from a base station, and Transmit a report response message to the base station based on the above report request message, The above report response message is used in the NCRT (Neighbor Cell Relation Table) managed by the base station, Based on the above report response message including a network type indicator for the network type of the neighboring base station of the terminal, the network type indicator indicates whether the neighboring base station is a TN (Terrestrial Network) base station or an NTN (Non-Terrestrial Network) base station, A method characterized in that the NCRT includes a network type field indicating whether each of the plurality of base stations is a TN base station or an NTN base station. In Article 15, Based on the fact that the identifier for the neighboring base station included in the measurement report message transmitted by the terminal to the base station does not exist in the NCRT, the terminal receives the report request message from the base station, A method characterized in that information about the neighboring base station is added to the NCRT based on the neighboring base station not being included in the NCRT. In Article 15, The terminal receives request information requesting identifier information of the neighboring base station from the base station, A method characterized in that, in response to the request information, the terminal transmits at least one of the identifier information and the location information of the terminal to the base station. In Article 17, Before the above request information is transmitted, the terminal transmits measurement report information to the base station, The above measurement report information includes a PCI (Physical Cell Identifier) ​​for the neighboring base station, A method characterized in that the above request information is transmitted based on the above measurement report information. In Article 15, The above report request message is included in the RRC connection reconfiguration message, A method characterized in that the terminal is in an RRC_CONNECTED state with respect to the base station. In Article 15, The above report response message includes at least one of identifier information for the neighboring base station, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network), A method characterized in that at least one of identifier information, ARFCN (Absolute Radio Frequency Channel Number), TAC (Tracking Area Code), and PLMN (Public Land Mobile Network) for the neighboring base station included in the above report response message is included in the system information for the neighboring base station.

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